https://github.com/shader-slang/slang
Tip revision: d386e27dc319b2feb362acd430ff5c640d8c6fba authored by jsmall-nvidia on 02 June 2020, 19:26:51 UTC
Added spGetBuildTagString. (#1365)
Added spGetBuildTagString. (#1365)
Tip revision: d386e27
slang-lower-to-ir.cpp
// lower.cpp
#include "slang-lower-to-ir.h"
#include "../../slang.h"
#include "slang-check.h"
#include "slang-ir.h"
#include "slang-ir-constexpr.h"
#include "slang-ir-dce.h"
#include "slang-ir-inline.h"
#include "slang-ir-insts.h"
#include "slang-ir-missing-return.h"
#include "slang-ir-sccp.h"
#include "slang-ir-ssa.h"
#include "slang-ir-strip.h"
#include "slang-ir-validate.h"
#include "slang-ir-string-hash.h"
#include "slang-mangle.h"
#include "slang-type-layout.h"
#include "slang-visitor.h"
namespace Slang
{
// This file implements lowering of the Slang AST to a simpler SSA
// intermediate representation.
//
// IR is generated in a context (`IRGenContext`), which tracks the current
// location in the IR where code should be emitted (e.g., what basic
// block to add instructions to). Lowering a statement will emit some
// number of instructions to the context, and possibly change the
// insertion point (because of control flow).
//
// When lowering an expression we have a more interesting challenge, for
// two main reasons:
//
// 1. There might be types that are representible in the AST, but which
// we don't want to support natively in the IR. An example is a `struct`
// type with both ordinary and resource-type members; we might want to
// split values with such a type into distinct values during lowering.
//
// 2. We need to handle the difference between l-value and r-value expressions,
// and in particular the fact that HLSL/Slang supports complicated sorts
// of l-values (e.g., `someVector.zxy` is an l-value, even though it can't
// be represented by a single pointer), and also allows l-values to appear
// in multiple contexts (not just the left-hand side of assignment, but
// also as an argument to match an `out` or `in out` parameter).
//
// Our solution to both of these problems is the same. Rather than having
// the lowering of an expression return a single IR-level value (`IRInst*`),
// we have it return a more complex type (`LoweredValInfo`) which can represent
// a wider range of conceptual "values" which might correspond to multiple IR-level
// values, and/or represent a pointer to an l-value rather than the r-value itself.
// We want to keep the representation of a `LoweringValInfo` relatively light
// - right now it is just a single pointer plus a "tag" to distinguish the cases.
//
// This means that cases that can't fit in a single pointer need a heap allocation
// to store their payload. For simplicity we represent all of these with a class
// hierarchy:
//
struct ExtendedValueInfo : RefObject
{};
// This case is used to indicate a value that is a reference
// to an AST-level subscript declaration.
//
struct SubscriptInfo : ExtendedValueInfo
{
DeclRef<SubscriptDecl> declRef;
};
// This case is used to indicate a reference to an AST-level
// subscript operation bound to particular arguments.
//
// For example in a case like this:
//
// RWStructuredBuffer<Foo> gBuffer;
// ... gBuffer[someIndex] ...
//
// the expression `gBuffer[someIndex]` will be lowered to
// a value that references `RWStructureBuffer<Foo>::operator[]`
// with arguments `(gBuffer, someIndex)`.
//
// Such a value can be an l-value, and depending on the context
// where it is used, can lower into a call to either the getter
// or setter operations of the subscript.
//
struct BoundSubscriptInfo : ExtendedValueInfo
{
DeclRef<SubscriptDecl> declRef;
IRType* type;
List<IRInst*> args;
};
// Some cases of `ExtendedValueInfo` need to
// recursively contain `LoweredValInfo`s, and
// so we forward declare them here and fill
// them in later.
//
struct BoundMemberInfo;
struct SwizzledLValueInfo;
// This type is our core representation of lowered values.
// In the simple case, it just wraps an `IRInst*`.
// More complex cases, representing l-values or aggregate
// values are also supported.
struct LoweredValInfo
{
// Which of the cases of value are we looking at?
enum class Flavor
{
// No value (akin to a null pointer)
None,
// A simple IR value
Simple,
// An l-value represented as an IR
// pointer to the value
Ptr,
// A member declaration bound to a particular `this` value
BoundMember,
// A reference to an AST-level subscript operation
Subscript,
// An AST-level subscript operation bound to a particular
// object and arguments.
BoundSubscript,
// The result of applying swizzling to an l-value
SwizzledLValue,
};
union
{
IRInst* val;
ExtendedValueInfo* ext;
};
Flavor flavor;
LoweredValInfo()
{
flavor = Flavor::None;
val = nullptr;
}
LoweredValInfo(IRType* t)
{
flavor = Flavor::Simple;
val = t;
}
static LoweredValInfo simple(IRInst* v)
{
LoweredValInfo info;
info.flavor = Flavor::Simple;
info.val = v;
return info;
}
static LoweredValInfo ptr(IRInst* v)
{
LoweredValInfo info;
info.flavor = Flavor::Ptr;
info.val = v;
return info;
}
static LoweredValInfo boundMember(
BoundMemberInfo* boundMemberInfo);
BoundMemberInfo* getBoundMemberInfo()
{
SLANG_ASSERT(flavor == Flavor::BoundMember);
return (BoundMemberInfo*)ext;
}
static LoweredValInfo subscript(
SubscriptInfo* subscriptInfo);
SubscriptInfo* getSubscriptInfo()
{
SLANG_ASSERT(flavor == Flavor::Subscript);
return (SubscriptInfo*)ext;
}
static LoweredValInfo boundSubscript(
BoundSubscriptInfo* boundSubscriptInfo);
BoundSubscriptInfo* getBoundSubscriptInfo()
{
SLANG_ASSERT(flavor == Flavor::BoundSubscript);
return (BoundSubscriptInfo*)ext;
}
static LoweredValInfo swizzledLValue(
SwizzledLValueInfo* extInfo);
SwizzledLValueInfo* getSwizzledLValueInfo()
{
SLANG_ASSERT(flavor == Flavor::SwizzledLValue);
return (SwizzledLValueInfo*)ext;
}
};
// Represents some declaration bound to a particular
// object. For example, if we had `obj.f` where `f`
// is a member function, we'd use a `BoundMemberInfo`
// to represnet this.
//
// Note: This case is largely avoided by special-casing
// in the handling of calls (like `obj.f(arg)`), but
// it is being left here as an example of what we might
// need/want to do in the long term.
struct BoundMemberInfo : ExtendedValueInfo
{
// The base object
LoweredValInfo base;
// The (AST-level) declaration reference.
DeclRef<Decl> declRef;
// The type of this value
IRType* type;
};
// Represents the result of a swizzle operation in
// an l-value context. A swizzle without duplicate
// elements is allowed as an l-value, even if the
// element are non-contiguous (`.xz`) or out of
// order (`.zxy`).
//
struct SwizzledLValueInfo : ExtendedValueInfo
{
// The type of the expression.
IRType* type;
// The base expression (this should be an l-value)
LoweredValInfo base;
// The number of elements in the swizzle
UInt elementCount;
// THe indices for the elements being swizzled
UInt elementIndices[4];
};
LoweredValInfo LoweredValInfo::boundMember(
BoundMemberInfo* boundMemberInfo)
{
LoweredValInfo info;
info.flavor = Flavor::BoundMember;
info.ext = boundMemberInfo;
return info;
}
LoweredValInfo LoweredValInfo::subscript(
SubscriptInfo* subscriptInfo)
{
LoweredValInfo info;
info.flavor = Flavor::Subscript;
info.ext = subscriptInfo;
return info;
}
LoweredValInfo LoweredValInfo::boundSubscript(
BoundSubscriptInfo* boundSubscriptInfo)
{
LoweredValInfo info;
info.flavor = Flavor::BoundSubscript;
info.ext = boundSubscriptInfo;
return info;
}
LoweredValInfo LoweredValInfo::swizzledLValue(
SwizzledLValueInfo* extInfo)
{
LoweredValInfo info;
info.flavor = Flavor::SwizzledLValue;
info.ext = extInfo;
return info;
}
// An "environment" for mapping AST declarations to IR values.
//
// This is required because in some cases we might lower the
// same AST declaration to the IR multiple times (e.g., when
// a generic transitively contains multiple functions, we
// will emit a distinct IR generic for each function, with
// its own copies of the generic parameters).
//
struct IRGenEnv
{
// Map an AST-level declaration to the IR-level value that represents it.
Dictionary<Decl*, LoweredValInfo> mapDeclToValue;
// The next outer env around this one
IRGenEnv* outer = nullptr;
};
struct SharedIRGenContext
{
SharedIRGenContext(
Session* session,
DiagnosticSink* sink,
bool obfuscateCode,
ModuleDecl* mainModuleDecl = nullptr)
: m_session(session)
, m_sink(sink)
, m_obfuscateCode(obfuscateCode)
, m_mainModuleDecl(mainModuleDecl)
{}
Session* m_session = nullptr;
DiagnosticSink* m_sink = nullptr;
bool m_obfuscateCode = false;
ModuleDecl* m_mainModuleDecl = nullptr;
// The "global" environment for mapping declarations to their IR values.
IRGenEnv globalEnv;
// Map an AST-level declaration of an interface
// requirement to the IR-level "key" that
// is used to fetch that requirement from a
// witness table.
Dictionary<Decl*, IRStructKey*> interfaceRequirementKeys;
// Arrays we keep around strictly for memory-management purposes:
// Any extended values created during lowering need
// to be cleaned up after the fact. We don't try
// to reference-count these along the way because
// they need to get stored into a `union` inside `LoweredValInfo`
List<RefPtr<ExtendedValueInfo>> extValues;
// Map from an AST-level statement that can be
// used as the target of a `break` or `continue`
// to the appropriate basic block to jump to.
Dictionary<Stmt*, IRBlock*> breakLabels;
Dictionary<Stmt*, IRBlock*> continueLabels;
// List of all string literals used in user code, regardless
// of how they were used (i.e., whether or not they were hashed).
//
// This does *not* collect:
// * String literals that were only used for attributes/modifiers in
// the user's code (e.g., `"compute"` in `[shader("compute")]`)
// * Any IR string literals constructed for the purpose of decorations,
// reflection, or other meta-data that did not appear as a literal
// in the source code.
//
List<IRInst*> m_stringLiterals;
};
struct IRGenContext
{
ASTBuilder* astBuilder;
// Shared state for the IR generation process
SharedIRGenContext* shared;
// environment for mapping AST decls to IR values
IRGenEnv* env;
// IR builder to use when building code under this context
IRBuilder* irBuilder;
// The value to use for any `this` expressions
// that appear in the current context.
//
// TODO: If we ever allow nesting of (non-static)
// types, then we may need to support references
// to an "outer `this`", and this representation
// might be insufficient.
LoweredValInfo thisVal;
explicit IRGenContext(SharedIRGenContext* inShared, ASTBuilder* inAstBuilder)
: shared(inShared)
, astBuilder(inAstBuilder)
, env(&inShared->globalEnv)
, irBuilder(nullptr)
{}
Session* getSession()
{
return shared->m_session;
}
DiagnosticSink* getSink()
{
return shared->m_sink;
}
ModuleDecl* getMainModuleDecl()
{
return shared->m_mainModuleDecl;
}
};
void setGlobalValue(SharedIRGenContext* sharedContext, Decl* decl, LoweredValInfo value)
{
sharedContext->globalEnv.mapDeclToValue[decl] = value;
}
void setGlobalValue(IRGenContext* context, Decl* decl, LoweredValInfo value)
{
setGlobalValue(context->shared, decl, value);
}
void setValue(IRGenContext* context, Decl* decl, LoweredValInfo value)
{
context->env->mapDeclToValue[decl] = value;
}
ModuleDecl* findModuleDecl(Decl* decl)
{
for (auto dd = decl; dd; dd = dd->parentDecl)
{
if (auto moduleDecl = as<ModuleDecl>(dd))
return moduleDecl;
}
return nullptr;
}
bool isFromStdLib(Decl* decl)
{
for (auto dd = decl; dd; dd = dd->parentDecl)
{
if (dd->hasModifier<FromStdLibModifier>())
return true;
}
return false;
}
bool isImportedDecl(IRGenContext* context, Decl* decl)
{
// If the declaration has the extern attribute then it must be imported
// from another module
//
// The [__extern] attribute is a very special case feature (aka "a hack") that allows a symbol to be declared
// as if it is part of the current module for AST purposes, but then expects to be imported from another IR module.
// For that linkage to work, both the exporting and importing modules must have the same name (which would
// usually indicate that they are the same module).
//
// Note that in practice for matching during linking uses the fully qualified name - including module name.
// Thus using extern __attribute isn't useful for symbols that are imported via `import`, only symbols
// that notionally come from the same module but are split into separate compilations (as can be done with -module-name)
if (decl->findModifier<ExternAttribute>())
{
return true;
}
ModuleDecl* moduleDecl = findModuleDecl(decl);
if (!moduleDecl)
return false;
// HACK: don't treat standard library code as
// being imported for right now, just because
// we don't load its IR in the same way as
// for other imports.
//
// TODO: Fix this the right way, by having standard
// library declarations have IR modules that we link
// in via the normal means.
if (isFromStdLib(decl))
return false;
if (moduleDecl != context->getMainModuleDecl())
return true;
return false;
}
/// Is `decl` a function that should be force-inlined early in compilation (before linking)?
static bool isForceInlineEarly(Decl* decl)
{
if(decl->hasModifier<UnsafeForceInlineEarlyAttribute>())
return true;
return false;
}
/// Should the given `decl` nested in `parentDecl` be treated as a static rather than instance declaration?
bool isEffectivelyStatic(
Decl* decl,
ContainerDecl* parentDecl);
// Ensure that a version of the given declaration has been emitted to the IR
LoweredValInfo ensureDecl(
IRGenContext* context,
Decl* decl);
// Emit code as needed to construct a reference to the given declaration with
// any needed specializations in place.
LoweredValInfo emitDeclRef(
IRGenContext* context,
DeclRef<Decl> declRef,
IRType* type);
IRInst* getSimpleVal(IRGenContext* context, LoweredValInfo lowered);
int32_t getIntrinsicOp(
Decl* decl,
IntrinsicOpModifier* intrinsicOpMod)
{
int32_t op = intrinsicOpMod->op;
if(op != 0)
return op;
// No specified modifier? Then we need to look it up
// based on the name of the declaration...
auto name = decl->getName();
auto nameText = getUnownedStringSliceText(name);
IROp irOp = findIROp(nameText);
SLANG_ASSERT(irOp != kIROp_Invalid);
SLANG_ASSERT(int32_t(irOp) >= 0);
return int32_t(irOp);
}
// Given a `LoweredValInfo` for something callable, along with a
// bunch of arguments, emit an appropriate call to it.
LoweredValInfo emitCallToVal(
IRGenContext* context,
IRType* type,
LoweredValInfo funcVal,
UInt argCount,
IRInst* const* args)
{
auto builder = context->irBuilder;
switch (funcVal.flavor)
{
case LoweredValInfo::Flavor::None:
SLANG_UNEXPECTED("null function");
default:
return LoweredValInfo::simple(
builder->emitCallInst(type, getSimpleVal(context, funcVal), argCount, args));
}
}
LoweredValInfo lowerRValueExpr(
IRGenContext* context,
Expr* expr);
IRType* lowerType(
IRGenContext* context,
Type* type);
static IRType* lowerType(
IRGenContext* context,
QualType const& type)
{
return lowerType(context, type.type);
}
// Given a `DeclRef` for something callable, along with a bunch of
// arguments, emit an appropriate call to it.
LoweredValInfo emitCallToDeclRef(
IRGenContext* context,
IRType* type,
DeclRef<Decl> funcDeclRef,
IRType* funcType,
UInt argCount,
IRInst* const* args)
{
auto builder = context->irBuilder;
if (auto subscriptDeclRef = funcDeclRef.as<SubscriptDecl>())
{
// A reference to a subscript declaration is a special case,
// because it is not possible to call a subscript directly;
// we must call one of its accessors.
//
// TODO: everything here will also apply to propery declarations
// once we have them, so some of this code might be shared
// some day.
DeclRef<GetterDecl> getterDeclRef;
bool justAGetter = true;
for (auto accessorDeclRef : getMembersOfType<AccessorDecl>(subscriptDeclRef, MemberFilterStyle::Instance))
{
// We want to track whether this subscript has any accessors other than
// `get` (assuming that everything except `get` can be used for setting...).
if (auto foundGetterDeclRef = accessorDeclRef.as<GetterDecl>())
{
// We found a getter.
getterDeclRef = foundGetterDeclRef;
}
else
{
// There was something other than a getter, so we can't
// invoke an accessor just now.
justAGetter = false;
}
}
if (!justAGetter || !getterDeclRef)
{
// We can't perform an actual call right now, because
// this expression might appear in an r-value or l-value
// position (or *both* if it is being passed as an argument
// for an `in out` parameter!).
//
// Instead, we will construct a special-case value to
// represent the latent subscript operation (abstractly
// this is a reference to a storage location).
// The abstract storage location will need to include
// all the arguments being passed to the subscript operation.
RefPtr<BoundSubscriptInfo> boundSubscript = new BoundSubscriptInfo();
boundSubscript->declRef = subscriptDeclRef;
boundSubscript->type = type;
boundSubscript->args.addRange(args, argCount);
context->shared->extValues.add(boundSubscript);
return LoweredValInfo::boundSubscript(boundSubscript);
}
// Otherwise we are just call the getter, and so that
// is what we need to be emitting a call to...
funcDeclRef = getterDeclRef;
}
auto funcDecl = funcDeclRef.getDecl();
if(auto intrinsicOpModifier = funcDecl->findModifier<IntrinsicOpModifier>())
{
// The intrinsic op maps to a single IR instruction,
// so we will emit an instruction with the chosen
// opcode, and the arguments to the call as its operands.
//
auto intrinsicOp = getIntrinsicOp(funcDecl, intrinsicOpModifier);
return LoweredValInfo::simple(builder->emitIntrinsicInst(
type,
IROp(intrinsicOp),
argCount,
args));
}
if( auto ctorDeclRef = funcDeclRef.as<ConstructorDecl>() )
{
if(!ctorDeclRef.getDecl()->body)
{
// HACK: For legacy reasons, all of the built-in initializers
// in the standard library are declared without proper
// intrinsic-op modifiers, so we will assume that an
// initializer without a body should map to `kIROp_Construct`.
//
// TODO: We should make all the initializers in the
// standard library have either a body or a proper
// intrinsic-op modifier.
//
// TODO: We should eliminate `kIROp_Construct` from the
// IR completely, in favor of more detailed/specific ops
// that cover the cases we actually care about.
//
return LoweredValInfo::simple(builder->emitConstructorInst(type, argCount, args));
}
}
// Fallback case is to emit an actual call.
//
// TODO: We are constructing a type that we expect the function
// being called to have here, but that type doesn't account
// for `in` vs. `out`/`inout` parameters, so it could easily
// be wrong. We should sort out why this path in the code
// even needs to be computing a type (rather than taking
// it directly from the declaration).
//
if(!funcType)
{
List<IRType*> argTypes;
for(UInt ii = 0; ii < argCount; ++ii)
{
argTypes.add(args[ii]->getDataType());
}
funcType = builder->getFuncType(argCount, argTypes.getBuffer(), type);
}
LoweredValInfo funcVal = emitDeclRef(context, funcDeclRef, funcType);
return emitCallToVal(context, type, funcVal, argCount, args);
}
LoweredValInfo emitCallToDeclRef(
IRGenContext* context,
IRType* type,
DeclRef<Decl> funcDeclRef,
IRType* funcType,
List<IRInst*> const& args)
{
return emitCallToDeclRef(context, type, funcDeclRef, funcType, args.getCount(), args.getBuffer());
}
IRInst* getFieldKey(
IRGenContext* context,
DeclRef<VarDecl> field)
{
return getSimpleVal(context, emitDeclRef(context, field, context->irBuilder->getKeyType()));
}
LoweredValInfo extractField(
IRGenContext* context,
IRType* fieldType,
LoweredValInfo base,
DeclRef<VarDecl> field)
{
IRBuilder* builder = context->irBuilder;
switch (base.flavor)
{
default:
{
IRInst* irBase = getSimpleVal(context, base);
return LoweredValInfo::simple(
builder->emitFieldExtract(
fieldType,
irBase,
getFieldKey(context, field)));
}
break;
case LoweredValInfo::Flavor::BoundMember:
case LoweredValInfo::Flavor::BoundSubscript:
{
// The base value is one that is trying to defer a get-vs-set
// decision, so we will need to do the same.
RefPtr<BoundMemberInfo> boundMemberInfo = new BoundMemberInfo();
boundMemberInfo->type = fieldType;
boundMemberInfo->base = base;
boundMemberInfo->declRef = field;
context->shared->extValues.add(boundMemberInfo);
return LoweredValInfo::boundMember(boundMemberInfo);
}
break;
case LoweredValInfo::Flavor::Ptr:
{
// We are "extracting" a field from an lvalue address,
// which means we should just compute an lvalue
// representing the field address.
IRInst* irBasePtr = base.val;
return LoweredValInfo::ptr(
builder->emitFieldAddress(
builder->getPtrType(fieldType),
irBasePtr,
getFieldKey(context, field)));
}
break;
}
}
LoweredValInfo materialize(
IRGenContext* context,
LoweredValInfo lowered)
{
auto builder = context->irBuilder;
top:
switch(lowered.flavor)
{
case LoweredValInfo::Flavor::None:
case LoweredValInfo::Flavor::Simple:
case LoweredValInfo::Flavor::Ptr:
return lowered;
case LoweredValInfo::Flavor::BoundSubscript:
{
auto boundSubscriptInfo = lowered.getBoundSubscriptInfo();
// We are being asked to extract a value from a subscript call
// (e.g., `base[index]`). We will first check if the subscript
// declared a getter and use that if possible, and then fall
// back to a `ref` accessor if one is defined.
//
// (Picking the `get` over the `ref` accessor simplifies things
// in case the `get` operation has a natural translation for
// a target, while the general `ref` case does not...)
auto getters = getMembersOfType<GetterDecl>(boundSubscriptInfo->declRef, MemberFilterStyle::Instance);
if (getters.getCount())
{
lowered = emitCallToDeclRef(
context,
boundSubscriptInfo->type,
*getters.begin(),
nullptr,
boundSubscriptInfo->args);
goto top;
}
auto refAccessors = getMembersOfType<RefAccessorDecl>(boundSubscriptInfo->declRef, MemberFilterStyle::Instance);
if(refAccessors.getCount())
{
// The `ref` accessor will return a pointer to the value, so
// we need to reflect that in the type of our `call` instruction.
IRType* ptrType = context->irBuilder->getPtrType(boundSubscriptInfo->type);
LoweredValInfo refVal = emitCallToDeclRef(
context,
ptrType,
*refAccessors.begin(),
nullptr,
boundSubscriptInfo->args);
// The result from the call needs to be implicitly dereferenced,
// so that it can work as an l-value of the desired result type.
lowered = LoweredValInfo::ptr(getSimpleVal(context, refVal));
goto top;
}
SLANG_UNEXPECTED("subscript had no getter");
UNREACHABLE_RETURN(LoweredValInfo());
}
break;
case LoweredValInfo::Flavor::BoundMember:
{
auto boundMemberInfo = lowered.getBoundMemberInfo();
auto base = materialize(context, boundMemberInfo->base);
auto declRef = boundMemberInfo->declRef;
if( auto fieldDeclRef = declRef.as<VarDecl>() )
{
lowered = extractField(context, boundMemberInfo->type, base, fieldDeclRef);
goto top;
}
else
{
SLANG_UNEXPECTED("unexpected member flavor");
UNREACHABLE_RETURN(LoweredValInfo());
}
}
break;
case LoweredValInfo::Flavor::SwizzledLValue:
{
auto swizzleInfo = lowered.getSwizzledLValueInfo();
return LoweredValInfo::simple(builder->emitSwizzle(
swizzleInfo->type,
getSimpleVal(context, swizzleInfo->base),
swizzleInfo->elementCount,
swizzleInfo->elementIndices));
}
default:
SLANG_UNEXPECTED("unhandled value flavor");
UNREACHABLE_RETURN(LoweredValInfo());
}
}
IRInst* getSimpleVal(IRGenContext* context, LoweredValInfo lowered)
{
auto builder = context->irBuilder;
// First, try to eliminate any "bound" operations along the chain,
// so that we are dealing with an ordinary value, or an l-value pointer.
lowered = materialize(context, lowered);
switch(lowered.flavor)
{
case LoweredValInfo::Flavor::None:
return nullptr;
case LoweredValInfo::Flavor::Simple:
return lowered.val;
case LoweredValInfo::Flavor::Ptr:
return builder->emitLoad(lowered.val);
default:
SLANG_UNEXPECTED("unhandled value flavor");
UNREACHABLE_RETURN(nullptr);
}
}
LoweredValInfo lowerVal(
IRGenContext* context,
Val* val);
IRInst* lowerSimpleVal(
IRGenContext* context,
Val* val)
{
auto lowered = lowerVal(context, val);
return getSimpleVal(context, lowered);
}
LoweredValInfo lowerLValueExpr(
IRGenContext* context,
Expr* expr);
void assign(
IRGenContext* context,
LoweredValInfo const& left,
LoweredValInfo const& right);
IRInst* getAddress(
IRGenContext* context,
LoweredValInfo const& inVal,
SourceLoc diagnosticLocation);
void lowerStmt(
IRGenContext* context,
Stmt* stmt);
LoweredValInfo lowerDecl(
IRGenContext* context,
DeclBase* decl);
IRType* getIntType(
IRGenContext* context)
{
return context->irBuilder->getBasicType(BaseType::Int);
}
static IRGeneric* getOuterGeneric(IRInst* gv)
{
auto parentBlock = as<IRBlock>(gv->getParent());
if (!parentBlock) return nullptr;
auto parentGeneric = as<IRGeneric>(parentBlock->getParent());
return parentGeneric;
}
static void addLinkageDecoration(
IRGenContext* context,
IRInst* inInst,
Decl* decl,
UnownedStringSlice const& mangledName)
{
// If the instruction is nested inside one or more generics,
// then the mangled name should really apply to the outer-most
// generic, and not the declaration nested inside.
auto builder = context->irBuilder;
IRInst* inst = inInst;
while (auto outerGeneric = getOuterGeneric(inst))
{
inst = outerGeneric;
}
if(isImportedDecl(context, decl))
{
builder->addImportDecoration(inst, mangledName);
}
else
{
builder->addExportDecoration(inst, mangledName);
}
}
static void addLinkageDecoration(
IRGenContext* context,
IRInst* inst,
Decl* decl)
{
String mangledName = getMangledName(context->astBuilder, decl);
if (context->shared->m_obfuscateCode)
{
mangledName = getHashedName(mangledName.getUnownedSlice());
}
addLinkageDecoration(context, inst, decl, mangledName.getUnownedSlice());
}
IRStructKey* getInterfaceRequirementKey(
IRGenContext* context,
Decl* requirementDecl)
{
IRStructKey* requirementKey = nullptr;
if(context->shared->interfaceRequirementKeys.TryGetValue(requirementDecl, requirementKey))
{
return requirementKey;
}
IRBuilder builderStorage = *context->irBuilder;
auto builder = &builderStorage;
builder->setInsertInto(builder->sharedBuilder->module->getModuleInst());
// Construct a key to serve as the representation of
// this requirement in the IR, and to allow lookup
// into the declaration.
requirementKey = builder->createStructKey();
addLinkageDecoration(context, requirementKey, requirementDecl);
context->shared->interfaceRequirementKeys.Add(requirementDecl, requirementKey);
return requirementKey;
}
SubstitutionSet lowerSubstitutions(IRGenContext* context, SubstitutionSet subst);
//
struct ValLoweringVisitor : ValVisitor<ValLoweringVisitor, LoweredValInfo, LoweredValInfo>
{
IRGenContext* context;
IRBuilder* getBuilder() { return context->irBuilder; }
LoweredValInfo visitVal(Val* /*val*/)
{
SLANG_UNIMPLEMENTED_X("value lowering");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitGenericParamIntVal(GenericParamIntVal* val)
{
return emitDeclRef(context, val->declRef,
lowerType(context, getType(context->astBuilder, val->declRef)));
}
LoweredValInfo visitDeclaredSubtypeWitness(DeclaredSubtypeWitness* val)
{
return emitDeclRef(context, val->declRef,
context->irBuilder->getWitnessTableType());
}
LoweredValInfo visitTransitiveSubtypeWitness(
TransitiveSubtypeWitness* val)
{
// The base (subToMid) will turn into a value with
// witness-table type.
IRInst* baseWitnessTable = lowerSimpleVal(context, val->subToMid);
// The next step should map to an interface requirement
// that is itself an interface conformance, so the result
// of lowering this value should be a "key" that we can
// use to look up a witness table.
IRInst* requirementKey = getInterfaceRequirementKey(context, val->midToSup.getDecl());
// TODO: There are some ugly cases here if `midToSup` is allowed
// to be an arbitrary witness, rather than just a declared one,
// and we should probably change the front-end representation
// to reflect the right constraints.
return LoweredValInfo::simple(getBuilder()->emitLookupInterfaceMethodInst(
nullptr,
baseWitnessTable,
requirementKey));
}
LoweredValInfo visitTaggedUnionSubtypeWitness(
TaggedUnionSubtypeWitness* val)
{
// The sub-type in this case is a tagged union `A | B | ...`,
// and the witness holds an array of witnesses showing that each
// "case" (`A`, `B`, etc.) is a subtype of the super-type.
// We will start by getting the IR-level representation of the
// sub type (the tagged union type).
//
auto irTaggedUnionType = lowerType(context, val->sub);
// We can turn each of those per-case witnesses into a witness
// table value:
//
auto caseCount = val->caseWitnesses.getCount();
List<IRInst*> caseWitnessTables;
for( auto caseWitness : val->caseWitnesses )
{
auto caseWitnessTable = lowerSimpleVal(context, caseWitness);
caseWitnessTables.add(caseWitnessTable);
}
// Now we need to synthesize a witness table for the tagged union
// value, showing how it can implement all of the requirements
// of the super type by delegating to the appropriate implementation
// on a per-case basis.
//
// We will assume here that the super-type is an interface, and it
// will be left to the front-end to ensure this property.
//
auto supDeclRefType = as<DeclRefType>(val->sup);
if(!supDeclRefType)
{
SLANG_UNEXPECTED("super-type not a decl-ref type when generating tagged union witness table");
UNREACHABLE_RETURN(LoweredValInfo());
}
auto supInterfaceDeclRef = supDeclRefType->declRef.as<InterfaceDecl>();
if( !supInterfaceDeclRef )
{
SLANG_UNEXPECTED("super-type not an interface type when generating tagged union witness table");
UNREACHABLE_RETURN(LoweredValInfo());
}
auto irWitnessTable = getBuilder()->createWitnessTable();
// Now we will iterate over the requirements (members) of the
// interface and try to synthesize an appropriate value for each.
//
for( auto reqDeclRef : getMembers(supInterfaceDeclRef) )
{
// TODO: if there are any members we shouldn't process as a requirement,
// then we should detect and skip them here.
//
// Every interface requirement will have a unique key that is used
// when looking up the requirement in a concrete witness table.
//
auto irReqKey = getInterfaceRequirementKey(context, reqDeclRef.getDecl());
// We expect that each of the witness tables in `caseWitnessTables`
// will have an entry to match these keys. However, we may not
// have a concrete `IRWitnessTable` for each of the case types, either
// because they are a specialization of a generic (so that the witness
// table reference is a `specialize` instruction at this point), or
// they are a type external to this module (so that we have a declaration
// rather than a definition of the witness table).
// Our task is to create an IR value that can satisfy the interface
// requirement for the tagged union type, by appropriately delegating
// to the implementations of the same requirement in the case types.
//
IRInst* irSatisfyingVal = nullptr;
if(auto callableDeclRef = reqDeclRef.as<CallableDecl>())
{
// We have something callable, so we need to synthesize
// a function to satisfy it.
//
auto irFunc = getBuilder()->createFunc();
irSatisfyingVal = irFunc;
IRBuilder subBuilderStorage;
auto subBuilder = &subBuilderStorage;
subBuilder->sharedBuilder = getBuilder()->sharedBuilder;
subBuilder->setInsertInto(irFunc);
// We will start by setting up the function parameters,
// which live in the entry block of the IR function.
//
auto entryBlock = subBuilder->emitBlock();
subBuilder->setInsertInto(entryBlock);
// Create a `this` parameter of the tagged-union type.
//
// TODO: need to handle the `[mutating]` case here...
//
auto irThisType = irTaggedUnionType;
auto irThisParam = subBuilder->emitParam(irThisType);
List<IRType*> irParamTypes;
irParamTypes.add(irThisType);
// Create the remaining parameters of the callable,
// using a decl-ref specialized to the tagged union
// type (so that things like associated types are
// mapped to the correct witness value).
//
List<IRParam*> irParams;
for( auto paramDeclRef : getMembersOfType<ParamDecl>(callableDeclRef) )
{
// TODO: need to handle `out` and `in out` here. Over all
// there is a lot of duplication here with the existing logic
// for emitting the signature of a `CallableDecl`, and we should
// try to re-use that if at all possible.
//
auto irParamType = lowerType(context, getType(context->astBuilder, paramDeclRef));
auto irParam = subBuilder->emitParam(irParamType);
irParams.add(irParam);
irParamTypes.add(irParamType);
}
auto irResultType = lowerType(context, getResultType(context->astBuilder, callableDeclRef));
auto irFuncType = subBuilder->getFuncType(
irParamTypes,
irResultType);
irFunc->setFullType(irFuncType);
// The first thing our function needs to do is extract the tag
// from the incoming `this` parameter.
//
auto irTagVal = subBuilder->emitExtractTaggedUnionTag(irThisParam);
// Next we want to emit a `switch` on the tag value, but before we
// do that we need to generate the code for each of the cases so that
// our `switch` has somewhere to branch to.
//
List<IRInst*> switchCaseOperands;
IRBlock* defaultLabel = nullptr;
for( Index ii = 0; ii < caseCount; ++ii )
{
auto caseTag = subBuilder->getIntValue(irTagVal->getDataType(), ii);
subBuilder->setInsertInto(irFunc);
auto caseLabel = subBuilder->emitBlock();
if(!defaultLabel)
defaultLabel = caseLabel;
switchCaseOperands.add(caseTag);
switchCaseOperands.add(caseLabel);
subBuilder->setInsertInto(caseLabel);
// We need to look up the satisfying value for this interface
// requirement on the witness table of the particular case value.
//
// We already have the witness table, and the requirement key is
// just `irReqKey`.
//
auto caseWitnessTable = caseWitnessTables[ii];
// The subtle bit here is determining the type we expect the
// satisfying value to have, since that depends on the actual
// type that is satisfying the requirement.
//
IRType* caseResultType = irResultType;
IRType* caseFuncType = nullptr;
auto caseFunc = subBuilder->emitLookupInterfaceMethodInst(
caseFuncType,
caseWitnessTable,
irReqKey);
// We are going to emit a `call` to the satisfying value
// for the case type, so we will collect the arguments for that call.
//
List<IRInst*> caseArgs;
// The `this` argument to the call will need to represent the
// appropriate field of our tagged union.
//
IRType* caseThisType = (IRType*) irTaggedUnionType->getOperand(ii);
auto caseThisArg = subBuilder->emitExtractTaggedUnionPayload(
caseThisType,
irThisParam, caseTag);
caseArgs.add(caseThisArg);
// The remaining arguments to the call will just be forwarded from
// the parameters of the wrapper function.
//
// TODO: This would need to change if/when we started allowing `This` type
// or associated-type parameters to be used at call sites where a tagged
// union is used.
//
for( auto param : irParams )
{
caseArgs.add(param);
}
auto caseCall = subBuilder->emitCallInst(caseResultType, caseFunc, caseArgs);
if( as<IRVoidType>(irResultType->getDataType()) )
{
subBuilder->emitReturn();
}
else
{
subBuilder->emitReturn(caseCall);
}
}
// We will create a block to represent the supposedly-unreachable
// code that will run if no `case` matches.
//
subBuilder->setInsertInto(irFunc);
auto invalidLabel = subBuilder->emitBlock();
subBuilder->setInsertInto(invalidLabel);
subBuilder->emitUnreachable();
if(!defaultLabel) defaultLabel = invalidLabel;
// Now we have enough information to go back and emit the `switch` instruction
// into the entry block.
subBuilder->setInsertInto(entryBlock);
subBuilder->emitSwitch(
irTagVal, // value to `switch` on
invalidLabel, // `break` label (block after the `switch` statement ends)
defaultLabel, // `default` label (where to go if no `case` matches)
switchCaseOperands.getCount(),
switchCaseOperands.getBuffer());
}
else
{
// TODO: We need to handle other cases of interface requirements.
SLANG_UNEXPECTED("unexpceted interface requirement when generating tagged union witness table");
UNREACHABLE_RETURN(LoweredValInfo());
}
// Once we've generating a value to satisfying the requirement, we install
// it into the witness table for our tagged-union type.
//
getBuilder()->createWitnessTableEntry(irWitnessTable, irReqKey, irSatisfyingVal);
}
return LoweredValInfo::simple(irWitnessTable);
}
LoweredValInfo visitConstantIntVal(ConstantIntVal* val)
{
// TODO: it is a bit messy here that the `ConstantIntVal` representation
// has no notion of a *type* associated with the value...
auto type = getIntType(context);
return LoweredValInfo::simple(getBuilder()->getIntValue(type, val->value));
}
IRFuncType* visitFuncType(FuncType* type)
{
IRType* resultType = lowerType(context, type->getResultType());
UInt paramCount = type->getParamCount();
List<IRType*> paramTypes;
for (UInt pp = 0; pp < paramCount; ++pp)
{
paramTypes.add(lowerType(context, type->getParamType(pp)));
}
return getBuilder()->getFuncType(
paramCount,
paramTypes.getBuffer(),
resultType);
}
IRType* visitDeclRefType(DeclRefType* type)
{
auto declRef = type->declRef;
auto decl = declRef.getDecl();
// Check for types with teh `__intrinsic_type` modifier.
if(decl->findModifier<IntrinsicTypeModifier>())
{
return lowerSimpleIntrinsicType(type);
}
return (IRType*) getSimpleVal(
context,
emitDeclRef(context, declRef,
context->irBuilder->getTypeKind()));
}
IRType* visitNamedExpressionType(NamedExpressionType* type)
{
return (IRType*)getSimpleVal(context, dispatchType(type->getCanonicalType()));
}
IRType* visitBasicExpressionType(BasicExpressionType* type)
{
return getBuilder()->getBasicType(
type->baseType);
}
IRType* visitVectorExpressionType(VectorExpressionType* type)
{
auto elementType = lowerType(context, type->elementType);
auto elementCount = lowerSimpleVal(context, type->elementCount);
return getBuilder()->getVectorType(
elementType,
elementCount);
}
IRType* visitMatrixExpressionType(MatrixExpressionType* type)
{
auto elementType = lowerType(context, type->getElementType());
auto rowCount = lowerSimpleVal(context, type->getRowCount());
auto columnCount = lowerSimpleVal(context, type->getColumnCount());
return getBuilder()->getMatrixType(
elementType,
rowCount,
columnCount);
}
IRType* visitArrayExpressionType(ArrayExpressionType* type)
{
auto elementType = lowerType(context, type->baseType);
if (type->arrayLength)
{
auto elementCount = lowerSimpleVal(context, type->arrayLength);
return getBuilder()->getArrayType(
elementType,
elementCount);
}
else
{
return getBuilder()->getUnsizedArrayType(
elementType);
}
}
// Lower a type where the type declaration being referenced is assumed
// to be an intrinsic type, which can thus be lowered to a simple IR
// type with the appropriate opcode.
IRType* lowerSimpleIntrinsicType(DeclRefType* type)
{
auto intrinsicTypeModifier = type->declRef.getDecl()->findModifier<IntrinsicTypeModifier>();
SLANG_ASSERT(intrinsicTypeModifier);
IROp op = IROp(intrinsicTypeModifier->irOp);
return getBuilder()->getType(op);
}
// Lower a type where the type declaration being referenced is assumed
// to be an intrinsic type with a single generic type parameter, and
// which can thus be lowered to a simple IR type with the appropriate opcode.
IRType* lowerGenericIntrinsicType(DeclRefType* type, Type* elementType)
{
auto intrinsicTypeModifier = type->declRef.getDecl()->findModifier<IntrinsicTypeModifier>();
SLANG_ASSERT(intrinsicTypeModifier);
IROp op = IROp(intrinsicTypeModifier->irOp);
IRInst* irElementType = lowerType(context, elementType);
return getBuilder()->getType(
op,
1,
&irElementType);
}
IRType* lowerGenericIntrinsicType(DeclRefType* type, Type* elementType, IntVal* count)
{
auto intrinsicTypeModifier = type->declRef.getDecl()->findModifier<IntrinsicTypeModifier>();
SLANG_ASSERT(intrinsicTypeModifier);
IROp op = IROp(intrinsicTypeModifier->irOp);
IRInst* irElementType = lowerType(context, elementType);
IRInst* irCount = lowerSimpleVal(context, count);
IRInst* const operands[2] =
{
irElementType,
irCount,
};
return getBuilder()->getType(
op,
SLANG_COUNT_OF(operands),
operands);
}
IRType* visitResourceType(ResourceType* type)
{
return lowerGenericIntrinsicType(type, type->elementType);
}
IRType* visitSamplerStateType(SamplerStateType* type)
{
return lowerSimpleIntrinsicType(type);
}
IRType* visitBuiltinGenericType(BuiltinGenericType* type)
{
return lowerGenericIntrinsicType(type, type->elementType);
}
IRType* visitUntypedBufferResourceType(UntypedBufferResourceType* type)
{
return lowerSimpleIntrinsicType(type);
}
IRType* visitHLSLPatchType(HLSLPatchType* type)
{
Type* elementType = type->getElementType();
IntVal* count = type->getElementCount();
return lowerGenericIntrinsicType(type, elementType, count);
}
IRType* visitExtractExistentialType(ExtractExistentialType* type)
{
auto declRef = type->declRef;
auto existentialType = lowerType(context, getType(context->astBuilder, declRef));
IRInst* existentialVal = getSimpleVal(context, emitDeclRef(context, declRef, existentialType));
return getBuilder()->emitExtractExistentialType(existentialVal);
}
LoweredValInfo visitExtractExistentialSubtypeWitness(ExtractExistentialSubtypeWitness* witness)
{
auto declRef = witness->declRef;
auto existentialType = lowerType(context, getType(context->astBuilder, declRef));
IRInst* existentialVal = getSimpleVal(context, emitDeclRef(context, declRef, existentialType));
return LoweredValInfo::simple(getBuilder()->emitExtractExistentialWitnessTable(existentialVal));
}
LoweredValInfo visitTaggedUnionType(TaggedUnionType* type)
{
// A tagged union type will lower into an IR `union` over the cases,
// along with an IR `struct` with a field for the union and a tag.
// (Note: we are placing the tag after the payload to avoid padding
// in the case where the payload is more aligned than the tag)
//
// TODO: should we be lowering directly like this, or have
// an IR-level representation of tagged unions?
//
List<IRType*> irCaseTypes;
for(auto caseType : type->caseTypes)
{
auto irCaseType = lowerType(context, caseType);
irCaseTypes.add(irCaseType);
}
auto irType = getBuilder()->getTaggedUnionType(irCaseTypes);
if(!irType->findDecoration<IRLinkageDecoration>())
{
// We need a way for later passes to attach layout information
// to this type, so we will give it a mangled name here.
//
getBuilder()->addExportDecoration(
irType,
getMangledTypeName(context->astBuilder, type).getUnownedSlice());
}
return LoweredValInfo::simple(irType);
}
LoweredValInfo visitExistentialSpecializedType(ExistentialSpecializedType* type)
{
auto irBaseType = lowerType(context, type->baseType);
List<IRInst*> slotArgs;
for(auto arg : type->args)
{
auto irArgVal = lowerSimpleVal(context, arg.val);
slotArgs.add(irArgVal);
if(auto witness = arg.witness)
{
auto irArgWitness = lowerSimpleVal(context, witness);
slotArgs.add(irArgWitness);
}
}
auto irType = getBuilder()->getBindExistentialsType(irBaseType, slotArgs.getCount(), slotArgs.getBuffer());
return LoweredValInfo::simple(irType);
}
LoweredValInfo visitThisType(ThisType* type)
{
// TODO: In theory, we should only run into a `ThisType` when lowering a concrete
// declaration defined on an interface type (e.g., via an `extension`).
//
// There is an open question of how we should emit a concrete method (say) defined
// on an `interface` type. We could emit the code in "object-oriented" style,
// passing in a `this` parameter of type `IFoo`, or we could emit it in a "generic"
// type where the whole member is wrapped in a generic on `<This : IFoo>`.
//
// The generic option has the benefit of having a clear solution in the case of
// static members that don't have a `this` parameter, but might still need `This`,
// but we have so far favored the "object-oriented" lowering for code involving
// bare interface types.
//
// For now we punt and emit the `ThisType` of an interface `IFoo` as `IFoo`.
//
return emitDeclRef(context, type->interfaceDeclRef, getBuilder()->getTypeKind());
}
// We do not expect to encounter the following types in ASTs that have
// passed front-end semantic checking.
#define UNEXPECTED_CASE(NAME) IRType* visit##NAME(NAME*) { SLANG_UNEXPECTED(#NAME); UNREACHABLE_RETURN(nullptr); }
UNEXPECTED_CASE(GenericDeclRefType)
UNEXPECTED_CASE(TypeType)
UNEXPECTED_CASE(ErrorType)
UNEXPECTED_CASE(InitializerListType)
UNEXPECTED_CASE(OverloadGroupType)
UNEXPECTED_CASE(NamespaceType)
#undef UNEXPECTED_CASE
};
LoweredValInfo lowerVal(
IRGenContext* context,
Val* val)
{
ValLoweringVisitor visitor;
visitor.context = context;
return visitor.dispatch(val);
}
IRType* lowerType(
IRGenContext* context,
Type* type)
{
ValLoweringVisitor visitor;
visitor.context = context;
return (IRType*) getSimpleVal(context, visitor.dispatchType(type));
}
void addVarDecorations(
IRGenContext* context,
IRInst* inst,
Decl* decl)
{
auto builder = context->irBuilder;
for(RefPtr<Modifier> mod : decl->modifiers)
{
if(as<HLSLNoInterpolationModifier>(mod))
{
builder->addInterpolationModeDecoration(inst, IRInterpolationMode::NoInterpolation);
}
else if(as<HLSLNoPerspectiveModifier>(mod))
{
builder->addInterpolationModeDecoration(inst, IRInterpolationMode::NoPerspective);
}
else if(as<HLSLLinearModifier>(mod))
{
builder->addInterpolationModeDecoration(inst, IRInterpolationMode::Linear);
}
else if(as<HLSLSampleModifier>(mod))
{
builder->addInterpolationModeDecoration(inst, IRInterpolationMode::Sample);
}
else if(as<HLSLCentroidModifier>(mod))
{
builder->addInterpolationModeDecoration(inst, IRInterpolationMode::Centroid);
}
else if(as<VulkanRayPayloadAttribute>(mod))
{
builder->addSimpleDecoration<IRVulkanRayPayloadDecoration>(inst);
}
else if(as<VulkanCallablePayloadAttribute>(mod))
{
builder->addSimpleDecoration<IRVulkanCallablePayloadDecoration>(inst);
}
else if(as<VulkanHitAttributesAttribute>(mod))
{
builder->addSimpleDecoration<IRVulkanHitAttributesDecoration>(inst);
}
else if(as<GloballyCoherentModifier>(mod))
{
builder->addSimpleDecoration<IRGloballyCoherentDecoration>(inst);
}
else if(as<PreciseModifier>(mod))
{
builder->addSimpleDecoration<IRPreciseDecoration>(inst);
}
else if(auto formatAttr = as<FormatAttribute>(mod))
{
builder->addFormatDecoration(inst, formatAttr->format);
}
// TODO: what are other modifiers we need to propagate through?
}
}
/// If `decl` has a modifier that should turn into a
/// rate qualifier, then apply it to `inst`.
void maybeSetRate(
IRGenContext* context,
IRInst* inst,
Decl* decl)
{
auto builder = context->irBuilder;
if (decl->hasModifier<HLSLGroupSharedModifier>())
{
inst->setFullType(builder->getRateQualifiedType(
builder->getGroupSharedRate(),
inst->getFullType()));
}
}
static String getNameForNameHint(
IRGenContext* context,
Decl* decl)
{
// We will use a bit of an ad hoc convention here for now.
Name* leafName = decl->getName();
// Handle custom name for a global parameter group (e.g., a `cbuffer`)
if(auto reflectionNameModifier = decl->findModifier<ParameterGroupReflectionName>())
{
leafName = reflectionNameModifier->nameAndLoc.name;
}
// There is no point in trying to provide a name hint for something with no name,
// or with an empty name
if(!leafName)
return String();
if(leafName->text.getLength() == 0)
return String();
if(auto varDecl = as<VarDeclBase>(decl))
{
// For an ordinary local variable, global variable,
// parameter, or field, we will just use the name
// as declared, and now work in anything from
// its parent declaration(s).
//
// TODO: consider whether global/static variables should
// follow different rules.
//
return leafName->text;
}
// For other cases of declaration, we want to consider
// merging its name with the name of its parent declaration.
auto parentDecl = decl->parentDecl;
// Skip past a generic parent, if we are a declaration nested in a generic.
if(auto genericParentDecl = as<GenericDecl>(parentDecl))
parentDecl = genericParentDecl->parentDecl;
// A `ModuleDecl` can have a name too, but in the common case
// we don't want to generate name hints that include the module
// name, simply because they would lead to every global symbol
// getting a much longer name.
//
// TODO: We should probably include the module name for symbols
// being `import`ed, and not for symbols being compiled directly
// (those coming from a module that had no name given to it).
//
// For now we skip past a `ModuleDecl` parent.
//
if(auto moduleParentDecl = as<ModuleDecl>(parentDecl))
parentDecl = moduleParentDecl->parentDecl;
if(!parentDecl)
{
return leafName->text;
}
auto parentName = getNameForNameHint(context, parentDecl);
if(parentName.getLength() == 0)
{
return leafName->text;
}
// We will now construct a new `Name` to use as the hint,
// combining the name of the parent and the leaf declaration.
StringBuilder sb;
sb.append(parentName);
sb.append(".");
sb.append(leafName->text);
return sb.ProduceString();
}
/// Try to add an appropriate name hint to the instruction,
/// that can be used for back-end code emission or debug info.
static void addNameHint(
IRGenContext* context,
IRInst* inst,
Decl* decl)
{
String name = getNameForNameHint(context, decl);
if(name.getLength() == 0)
return;
context->irBuilder->addNameHintDecoration(inst, name.getUnownedSlice());
}
/// Add a name hint based on a fixed string.
static void addNameHint(
IRGenContext* context,
IRInst* inst,
char const* text)
{
if (context->shared->m_obfuscateCode)
{
return;
}
context->irBuilder->addNameHintDecoration(inst, UnownedTerminatedStringSlice(text));
}
LoweredValInfo createVar(
IRGenContext* context,
IRType* type,
Decl* decl = nullptr)
{
auto builder = context->irBuilder;
auto irAlloc = builder->emitVar(type);
if (decl)
{
maybeSetRate(context, irAlloc, decl);
addVarDecorations(context, irAlloc, decl);
builder->addHighLevelDeclDecoration(irAlloc, decl);
addNameHint(context, irAlloc, decl);
}
return LoweredValInfo::ptr(irAlloc);
}
void addArgs(
IRGenContext* context,
List<IRInst*>* ioArgs,
LoweredValInfo argInfo)
{
auto& args = *ioArgs;
switch( argInfo.flavor )
{
case LoweredValInfo::Flavor::Simple:
case LoweredValInfo::Flavor::Ptr:
case LoweredValInfo::Flavor::SwizzledLValue:
case LoweredValInfo::Flavor::BoundSubscript:
case LoweredValInfo::Flavor::BoundMember:
args.add(getSimpleVal(context, argInfo));
break;
default:
SLANG_UNIMPLEMENTED_X("addArgs case");
break;
}
}
//
// When we try to turn a `LoweredValInfo` into an address of some temporary storage,
// we can either do it "aggressively" or not (what we'll call the "default" behavior,
// although it isn't strictly more common).
//
// The case that this is mostly there to address is when somebody writes an operation
// like:
//
// foo[a] = b;
//
// In that case, we might as well just use the `set` accessor if there is one, rather
// than complicate things. However, in more complex cases like:
//
// foo[a].x = b;
//
// there is no way to satisfy the semantics of the code the user wrote (in terms of
// only writing one vector component, and not a full vector) by using the `set`
// accessor, and we need to be "aggressive" in turning the lvalue `foo[a]` into
// an address.
//
// TODO: realistically IR lowering is too early to be binding to this choice,
// because different accessors might be supported on different targets.
//
enum class TryGetAddressMode
{
Default,
Aggressive,
};
/// Try to coerce `inVal` into a `LoweredValInfo::ptr()` with a simple address.
LoweredValInfo tryGetAddress(
IRGenContext* context,
LoweredValInfo const& inVal,
TryGetAddressMode mode);
/// Represents the "direction" that a parameter is being passed (e.g., `in` or `out`
enum ParameterDirection
{
kParameterDirection_In, ///< Copy in
kParameterDirection_Out, ///< Copy out
kParameterDirection_InOut, ///< Copy in, copy out
kParameterDirection_Ref, ///< By-reference
};
/// Compute the direction for a parameter based on its declaration
ParameterDirection getParameterDirection(VarDeclBase* paramDecl)
{
if( paramDecl->hasModifier<RefModifier>() )
{
// The AST specified `ref`:
return kParameterDirection_Ref;
}
if( paramDecl->hasModifier<InOutModifier>() )
{
// The AST specified `inout`:
return kParameterDirection_InOut;
}
if (paramDecl->hasModifier<OutModifier>())
{
// We saw an `out` modifier, so now we need
// to check if there was a paired `in`.
if(paramDecl->hasModifier<InModifier>())
return kParameterDirection_InOut;
else
return kParameterDirection_Out;
}
else
{
// No direction modifier, or just `in`:
return kParameterDirection_In;
}
}
/// Compute the direction for a `this` parameter based on the declaration of its parent function
ParameterDirection getThisParamDirection(Decl* parentDecl)
{
// Applications can opt in to a mutable `this` parameter,
// by applying the `[mutating]` attribute to their
// declaration.
//
if( parentDecl->hasModifier<MutatingAttribute>() )
{
return kParameterDirection_InOut;
}
// TODO: If/when we support user-defined subscripts or properties,
// we should probably make the `set` accessor on those default to
// `[mutating]` rather than require users to specify it. There
// might need to be a `[nonmutating]` modifier for the rare case
// where a user wants to opt out.
// For now we make any `this` parameter default to `in`.
//
return kParameterDirection_In;
}
DeclRef<Decl> createDefaultSpecializedDeclRefImpl(IRGenContext* context, Decl* decl)
{
DeclRef<Decl> declRef;
declRef.decl = decl;
declRef.substitutions = createDefaultSubstitutions(context->astBuilder, decl);
return declRef;
}
//
// The client should actually call the templated wrapper, to preserve type information.
template<typename D>
DeclRef<D> createDefaultSpecializedDeclRef(IRGenContext* context, D* decl)
{
DeclRef<Decl> declRef = createDefaultSpecializedDeclRefImpl(context, decl);
return declRef.as<D>();
}
/// Get the type of the `this` parameter introduced by `parentDeclRef`, or null.
///
/// E.g., if `parentDeclRef` is a `struct` declaration, then this will
/// return the type of that `struct`.
///
/// If this function is called on a declaration that does not itself directly
/// introduce a notion of `this`, then null will be returned. Note that this
/// includes things like function declarations themselves, which inherit the
/// definition of `this` from their parent/outer declaration.
///
RefPtr<Type> getThisParamTypeForContainer(
IRGenContext* context,
DeclRef<Decl> parentDeclRef)
{
if( auto aggTypeDeclRef = parentDeclRef.as<AggTypeDecl>() )
{
return DeclRefType::create(context->astBuilder, aggTypeDeclRef);
}
else if( auto extensionDeclRef = parentDeclRef.as<ExtensionDecl>() )
{
return getTargetType(context->astBuilder, extensionDeclRef);
}
return nullptr;
}
RefPtr<Type> getThisParamTypeForCallable(
IRGenContext* context,
DeclRef<Decl> callableDeclRef)
{
auto parentDeclRef = callableDeclRef.getParent();
if(auto subscriptDeclRef = parentDeclRef.as<SubscriptDecl>())
parentDeclRef = subscriptDeclRef.getParent();
if(auto genericDeclRef = parentDeclRef.as<GenericDecl>())
parentDeclRef = genericDeclRef.getParent();
return getThisParamTypeForContainer(context, parentDeclRef);
}
//
template<typename Derived>
struct ExprLoweringVisitorBase : ExprVisitor<Derived, LoweredValInfo>
{
IRGenContext* context;
IRBuilder* getBuilder() { return context->irBuilder; }
ASTBuilder* getASTBuilder() { return context->astBuilder; }
// Lower an expression that should have the same l-value-ness
// as the visitor itself.
LoweredValInfo lowerSubExpr(Expr* expr)
{
IRBuilderSourceLocRAII sourceLocInfo(getBuilder(), expr->loc);
return this->dispatch(expr);
}
LoweredValInfo visitVarExpr(VarExpr* expr)
{
LoweredValInfo info = emitDeclRef(
context,
expr->declRef,
lowerType(context, expr->type));
return info;
}
LoweredValInfo visitOverloadedExpr(OverloadedExpr* /*expr*/)
{
SLANG_UNEXPECTED("overloaded expressions should not occur in checked AST");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitOverloadedExpr2(OverloadedExpr2* /*expr*/)
{
SLANG_UNEXPECTED("overloaded expressions should not occur in checked AST");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitIndexExpr(IndexExpr* expr)
{
auto type = lowerType(context, expr->type);
auto baseVal = lowerSubExpr(expr->baseExpression);
auto indexVal = getSimpleVal(context, lowerRValueExpr(context, expr->indexExpression));
return subscriptValue(type, baseVal, indexVal);
}
LoweredValInfo visitThisExpr(ThisExpr* /*expr*/)
{
return context->thisVal;
}
LoweredValInfo visitMemberExpr(MemberExpr* expr)
{
auto loweredType = lowerType(context, expr->type);
auto loweredBase = lowerRValueExpr(context, expr->baseExpression);
auto declRef = expr->declRef;
if (auto fieldDeclRef = declRef.as<VarDecl>())
{
// Okay, easy enough: we have a reference to a field of a struct type...
return extractField(loweredType, loweredBase, fieldDeclRef);
}
else if (auto callableDeclRef = declRef.as<CallableDecl>())
{
RefPtr<BoundMemberInfo> boundMemberInfo = new BoundMemberInfo();
boundMemberInfo->type = nullptr;
boundMemberInfo->base = loweredBase;
boundMemberInfo->declRef = callableDeclRef;
return LoweredValInfo::boundMember(boundMemberInfo);
}
else if(auto constraintDeclRef = declRef.as<TypeConstraintDecl>())
{
// The code is making use of a "witness" that a value of
// some generic type conforms to an interface.
//
// For now we will just emit the base expression as-is.
// TODO: we may need to insert an explicit instruction
// for a cast here (that could become a no-op later).
return loweredBase;
}
SLANG_UNIMPLEMENTED_X("codegen for subscript expression");
UNREACHABLE_RETURN(LoweredValInfo());
}
// We will always lower a dereference expression (`*ptr`)
// as an l-value, since that is the easiest way to handle it.
LoweredValInfo visitDerefExpr(DerefExpr* expr)
{
auto loweredBase = lowerRValueExpr(context, expr->base);
// TODO: handle tupel-type for `base`
// The type of the lowered base must by some kind of pointer,
// in order for a dereference to make senese, so we just
// need to extract the value type from that pointer here.
//
IRInst* loweredBaseVal = getSimpleVal(context, loweredBase);
IRType* loweredBaseType = loweredBaseVal->getDataType();
if (as<IRPointerLikeType>(loweredBaseType)
|| as<IRPtrTypeBase>(loweredBaseType))
{
// Note that we do *not* perform an actual `load` operation
// here, but rather just use the pointer value to construct
// an appropriate `LoweredValInfo` representing the underlying
// dereference.
//
// This is important so that an expression like `&((*foo).bar)`
// (which is desugared from `&foo->bar`) can be handled; such
// an expression does *not* perform a dereference at runtime,
// and is just a bit of pointer math.
//
return LoweredValInfo::ptr(loweredBaseVal);
}
else
{
SLANG_UNIMPLEMENTED_X("codegen for deref expression");
UNREACHABLE_RETURN(LoweredValInfo());
}
}
LoweredValInfo visitParenExpr(ParenExpr* expr)
{
return lowerSubExpr(expr->base);
}
LoweredValInfo getSimpleDefaultVal(IRType* type)
{
if(auto basicType = as<IRBasicType>(type))
{
switch( basicType->getBaseType() )
{
default:
SLANG_UNEXPECTED("missing case for getting IR default value");
UNREACHABLE_RETURN(LoweredValInfo());
break;
case BaseType::Bool:
return LoweredValInfo::simple(getBuilder()->getBoolValue(false));
case BaseType::Int8:
case BaseType::Int16:
case BaseType::Int:
case BaseType::Int64:
case BaseType::UInt8:
case BaseType::UInt16:
case BaseType::UInt:
case BaseType::UInt64:
return LoweredValInfo::simple(getBuilder()->getIntValue(type, 0));
case BaseType::Half:
case BaseType::Float:
case BaseType::Double:
return LoweredValInfo::simple(getBuilder()->getFloatValue(type, 0.0));
}
}
SLANG_UNEXPECTED("missing case for getting IR default value");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo getDefaultVal(Type* type)
{
auto irType = lowerType(context, type);
if (auto basicType = as<BasicExpressionType>(type))
{
return getSimpleDefaultVal(irType);
}
else if (auto vectorType = as<VectorExpressionType>(type))
{
UInt elementCount = (UInt) getIntVal(vectorType->elementCount);
auto irDefaultValue = getSimpleVal(context, getDefaultVal(vectorType->elementType));
List<IRInst*> args;
for(UInt ee = 0; ee < elementCount; ++ee)
{
args.add(irDefaultValue);
}
return LoweredValInfo::simple(
getBuilder()->emitMakeVector(irType, args.getCount(), args.getBuffer()));
}
else if (auto matrixType = as<MatrixExpressionType>(type))
{
UInt rowCount = (UInt) getIntVal(matrixType->getRowCount());
auto rowType = matrixType->getRowType();
auto irDefaultValue = getSimpleVal(context, getDefaultVal(rowType));
List<IRInst*> args;
for(UInt rr = 0; rr < rowCount; ++rr)
{
args.add(irDefaultValue);
}
return LoweredValInfo::simple(
getBuilder()->emitMakeMatrix(irType, args.getCount(), args.getBuffer()));
}
else if (auto arrayType = as<ArrayExpressionType>(type))
{
UInt elementCount = (UInt) getIntVal(arrayType->arrayLength);
auto irDefaultElement = getSimpleVal(context, getDefaultVal(arrayType->baseType));
List<IRInst*> args;
for(UInt ee = 0; ee < elementCount; ++ee)
{
args.add(irDefaultElement);
}
return LoweredValInfo::simple(
getBuilder()->emitMakeArray(irType, args.getCount(), args.getBuffer()));
}
else if (auto declRefType = as<DeclRefType>(type))
{
DeclRef<Decl> declRef = declRefType->declRef;
if (auto aggTypeDeclRef = declRef.as<AggTypeDecl>())
{
List<IRInst*> args;
for (auto ff : getMembersOfType<VarDecl>(aggTypeDeclRef, MemberFilterStyle::Instance))
{
auto irFieldVal = getSimpleVal(context, getDefaultVal(ff));
args.add(irFieldVal);
}
return LoweredValInfo::simple(
getBuilder()->emitMakeStruct(irType, args.getCount(), args.getBuffer()));
}
}
SLANG_UNEXPECTED("unexpected type when creating default value");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo getDefaultVal(VarDeclBase* decl)
{
if(auto initExpr = decl->initExpr)
{
return lowerRValueExpr(context, initExpr);
}
else
{
return getDefaultVal(decl->type);
}
}
LoweredValInfo visitInitializerListExpr(InitializerListExpr* expr)
{
// Allocate a temporary of the given type
auto type = expr->type;
IRType* irType = lowerType(context, type);
List<IRInst*> args;
UInt argCount = expr->args.getCount();
// If the initializer list was empty, then the user was
// asking for default initialization, which should apply
// to (almost) any type.
//
if(argCount == 0)
{
return getDefaultVal(type.type);
}
// Now for each argument in the initializer list,
// fill in the appropriate field of the result
if (auto arrayType = as<ArrayExpressionType>(type))
{
UInt elementCount = (UInt) getIntVal(arrayType->arrayLength);
for (UInt ee = 0; ee < argCount; ++ee)
{
auto argExpr = expr->args[ee];
LoweredValInfo argVal = lowerRValueExpr(context, argExpr);
args.add(getSimpleVal(context, argVal));
}
if(elementCount > argCount)
{
auto irDefaultValue = getSimpleVal(context, getDefaultVal(arrayType->baseType));
for(UInt ee = argCount; ee < elementCount; ++ee)
{
args.add(irDefaultValue);
}
}
return LoweredValInfo::simple(
getBuilder()->emitMakeArray(irType, args.getCount(), args.getBuffer()));
}
else if (auto vectorType = as<VectorExpressionType>(type))
{
UInt elementCount = (UInt) getIntVal(vectorType->elementCount);
for (UInt ee = 0; ee < argCount; ++ee)
{
auto argExpr = expr->args[ee];
LoweredValInfo argVal = lowerRValueExpr(context, argExpr);
args.add(getSimpleVal(context, argVal));
}
if(elementCount > argCount)
{
auto irDefaultValue = getSimpleVal(context, getDefaultVal(vectorType->elementType));
for(UInt ee = argCount; ee < elementCount; ++ee)
{
args.add(irDefaultValue);
}
}
return LoweredValInfo::simple(
getBuilder()->emitMakeVector(irType, args.getCount(), args.getBuffer()));
}
else if (auto matrixType = as<MatrixExpressionType>(type))
{
UInt rowCount = (UInt) getIntVal(matrixType->getRowCount());
for (UInt rr = 0; rr < argCount; ++rr)
{
auto argExpr = expr->args[rr];
LoweredValInfo argVal = lowerRValueExpr(context, argExpr);
args.add(getSimpleVal(context, argVal));
}
if(rowCount > argCount)
{
auto rowType = matrixType->getRowType();
auto irDefaultValue = getSimpleVal(context, getDefaultVal(rowType));
for(UInt rr = argCount; rr < rowCount; ++rr)
{
args.add(irDefaultValue);
}
}
return LoweredValInfo::simple(
getBuilder()->emitMakeMatrix(irType, args.getCount(), args.getBuffer()));
}
else if (auto declRefType = as<DeclRefType>(type))
{
DeclRef<Decl> declRef = declRefType->declRef;
if (auto aggTypeDeclRef = declRef.as<AggTypeDecl>())
{
UInt argCounter = 0;
for (auto ff : getMembersOfType<VarDecl>(aggTypeDeclRef, MemberFilterStyle::Instance))
{
UInt argIndex = argCounter++;
if (argIndex < argCount)
{
auto argExpr = expr->args[argIndex];
LoweredValInfo argVal = lowerRValueExpr(context, argExpr);
args.add(getSimpleVal(context, argVal));
}
else
{
auto irDefaultValue = getSimpleVal(context, getDefaultVal(ff));
args.add(irDefaultValue);
}
}
return LoweredValInfo::simple(
getBuilder()->emitMakeStruct(irType, args.getCount(), args.getBuffer()));
}
}
// If none of the above cases matched, then we had better
// have zero arguments in the initializer list, in which
// case we are just looking for default initialization.
//
SLANG_UNEXPECTED("unhandled case for initializer list codegen");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitBoolLiteralExpr(BoolLiteralExpr* expr)
{
return LoweredValInfo::simple(context->irBuilder->getBoolValue(expr->value));
}
LoweredValInfo visitIntegerLiteralExpr(IntegerLiteralExpr* expr)
{
auto type = lowerType(context, expr->type);
return LoweredValInfo::simple(context->irBuilder->getIntValue(type, expr->value));
}
LoweredValInfo visitFloatingPointLiteralExpr(FloatingPointLiteralExpr* expr)
{
auto type = lowerType(context, expr->type);
return LoweredValInfo::simple(context->irBuilder->getFloatValue(type, expr->value));
}
LoweredValInfo visitStringLiteralExpr(StringLiteralExpr* expr)
{
auto irLit = context->irBuilder->getStringValue(expr->value.getUnownedSlice());
context->shared->m_stringLiterals.add(irLit);
return LoweredValInfo::simple(irLit);
}
LoweredValInfo visitAggTypeCtorExpr(AggTypeCtorExpr* /*expr*/)
{
SLANG_UNIMPLEMENTED_X("codegen for aggregate type constructor expression");
UNREACHABLE_RETURN(LoweredValInfo());
}
// After a call to a function with `out` or `in out`
// parameters, we may need to copy data back into
// the l-value locations used for output arguments.
//
// During lowering of the argument list, we build
// up a list of these "fixup" assignments that need
// to be performed.
struct OutArgumentFixup
{
LoweredValInfo dst;
LoweredValInfo src;
};
/// Add argument(s) corresponding to one parameter to a call
///
/// The `argExpr` is the AST-level expression being passed as an argument to the call.
/// The `paramType` and `paramDirection` represent what is known about the receiving
/// parameter of the callee (e.g., if the parameter `in`, `inout`, etc.).
/// The `ioArgs` array receives the IR-level argument(s) that are added for the given
/// argument expression.
/// The `ioFixups` array receives any "fixup" code that needs to be run *after* the
/// call completes (e.g., to move from a scratch variable used for an `inout` argument back
/// into the original location).
///
void addCallArgsForParam(
IRType* paramType,
ParameterDirection paramDirection,
Expr* argExpr,
List<IRInst*>* ioArgs,
List<OutArgumentFixup>* ioFixups)
{
switch(paramDirection)
{
case kParameterDirection_Ref:
{
// A `ref` qualified parameter must be implemented with by-reference
// parameter passing, so the argument value should be lowered as
// an l-value.
//
LoweredValInfo loweredArg = lowerLValueExpr(context, argExpr);
// According to our "calling convention" we need to
// pass a pointer into the callee. Unlike the case for
// `out` and `inout` below, it is never valid to do
// copy-in/copy-out for a `ref` parameter, so we just
// pass in the actual pointer.
//
IRInst* argPtr = getAddress(context, loweredArg, argExpr->loc);
(*ioArgs).add(argPtr);
}
break;
case kParameterDirection_Out:
case kParameterDirection_InOut:
{
// This is a `out` or `inout` parameter, and so
// the argument must be lowered as an l-value.
LoweredValInfo loweredArg = lowerLValueExpr(context, argExpr);
// According to our "calling convention" we need to
// pass a pointer into the callee.
//
// A naive approach would be to just take the address
// of `loweredArg` above and pass it in, but that
// has two issues:
//
// 1. The l-value might not be something that has a single
// well-defined "address" (e.g., `foo.xzy`).
//
// 2. The l-value argument might actually alias some other
// storage that the callee will access (e.g., we are
// passing in a global variable, or two `out` parameters
// are being passed the same location in an array).
//
// In each of these cases, the safe option is to create
// a temporary variable to use for argument-passing,
// and then do copy-in/copy-out around the call.
//
// TODO: We should consider ruling out case (2) as undefined
// behavior, and specify that whether `inout` and `out` are
// handled via copy-in-copy-out or by-reference parameter
// passing is an implementation detail. That would allow
// us to avoid introducing a copy except where it is required
// for the semantics of (1).
LoweredValInfo tempVar = createVar(context, paramType);
// If the parameter is `in out` or `inout`, then we need
// to ensure that we pass in the original value stored
// in the argument, which we accomplish by assigning
// from the l-value to our temp.
if(paramDirection == kParameterDirection_InOut)
{
assign(context, tempVar, loweredArg);
}
// Now we can pass the address of the temporary variable
// to the callee as the actual argument for the `in out`
SLANG_ASSERT(tempVar.flavor == LoweredValInfo::Flavor::Ptr);
(*ioArgs).add(tempVar.val);
// Finally, after the call we will need
// to copy in the other direction: from our
// temp back to the original l-value.
OutArgumentFixup fixup;
fixup.src = tempVar;
fixup.dst = loweredArg;
(*ioFixups).add(fixup);
}
break;
default:
{
// This is a pure input parameter, and so we will
// pass it as an r-value.
LoweredValInfo loweredArg = lowerRValueExpr(context, argExpr);
addArgs(context, ioArgs, loweredArg);
}
break;
}
}
void addDirectCallArgs(
InvokeExpr* expr,
DeclRef<CallableDecl> funcDeclRef,
List<IRInst*>* ioArgs,
List<OutArgumentFixup>* ioFixups)
{
UInt argCount = expr->arguments.getCount();
UInt argCounter = 0;
for (auto paramDeclRef : getMembersOfType<ParamDecl>(funcDeclRef))
{
auto paramDecl = paramDeclRef.getDecl();
IRType* paramType = lowerType(context, getType(getASTBuilder(), paramDeclRef));
auto paramDirection = getParameterDirection(paramDecl);
UInt argIndex = argCounter++;
RefPtr<Expr> argExpr;
if(argIndex < argCount)
{
argExpr = expr->arguments[argIndex];
}
else
{
// We have run out of arguments supplied at the call site,
// but there are still parameters remaining. This must mean
// that these parameters have default argument expressions
// associated with them.
argExpr = getInitExpr(getASTBuilder(), paramDeclRef);
// Assert that such an expression must have been present.
SLANG_ASSERT(argExpr);
// TODO: The approach we are taking here to default arguments
// is simplistic, and has consequences for the front-end as
// well as binary serialization of modules.
//
// We could consider some more refined approaches where, e.g.,
// functions with default arguments generate multiple IR-level
// functions, that compute and provide the default values.
//
// Alternatively, each parameter with defaults could be generated
// into its own callable function that provides the default value,
// so that calling modules can call into a pre-generated function.
//
// Each of these options involves trade-offs, and we need to
// make a conscious decision at some point.
}
addCallArgsForParam(paramType, paramDirection, argExpr, ioArgs, ioFixups);
}
}
// Add arguments that appeared directly in an argument list
// to the list of argument values for a call.
void addDirectCallArgs(
InvokeExpr* expr,
DeclRef<Decl> funcDeclRef,
List<IRInst*>* ioArgs,
List<OutArgumentFixup>* ioFixups)
{
if (auto callableDeclRef = funcDeclRef.as<CallableDecl>())
{
addDirectCallArgs(expr, callableDeclRef, ioArgs, ioFixups);
}
else
{
SLANG_UNEXPECTED("callee was not a callable decl");
}
}
void addFuncBaseArgs(
LoweredValInfo funcVal,
List<IRInst*>* ioArgs)
{
switch (funcVal.flavor)
{
default:
return;
}
}
void applyOutArgumentFixups(List<OutArgumentFixup> const& fixups)
{
for (auto fixup : fixups)
{
assign(context, fixup.dst, fixup.src);
}
}
struct ResolvedCallInfo
{
DeclRef<Decl> funcDeclRef;
Expr* baseExpr = nullptr;
};
// Try to resolve a the function expression for a call
// into a reference to a specific declaration, along
// with some contextual information about the declaration
// we are calling.
bool tryResolveDeclRefForCall(
RefPtr<Expr> funcExpr,
ResolvedCallInfo* outInfo)
{
// TODO: unwrap any "identity" expressions that might
// be wrapping the callee.
// First look to see if the expression references a
// declaration at all.
auto declRefExpr = as<DeclRefExpr>(funcExpr);
if(!declRefExpr)
return false;
// A little bit of future proofing here: if we ever
// allow higher-order functions, then we might be
// calling through a variable/field that has a function
// type, but is not itself a function.
// In such a case we should be careful to not statically
// resolve things.
//
if(auto callableDecl = as<CallableDecl>(declRefExpr->declRef.getDecl()))
{
// Okay, the declaration is directly callable, so we can continue.
}
else
{
// The callee declaration isn't itself a callable (it must have
// a function type, though).
return false;
}
// Now we can look at the specific kinds of declaration references,
// and try to tease them apart.
if (auto memberFuncExpr = as<MemberExpr>(funcExpr))
{
outInfo->funcDeclRef = memberFuncExpr->declRef;
outInfo->baseExpr = memberFuncExpr->baseExpression;
return true;
}
else if (auto staticMemberFuncExpr = as<StaticMemberExpr>(funcExpr))
{
outInfo->funcDeclRef = staticMemberFuncExpr->declRef;
return true;
}
else if (auto varExpr = as<VarExpr>(funcExpr))
{
outInfo->funcDeclRef = varExpr->declRef;
return true;
}
else
{
// Seems to be a case of declaration-reference we don't know about.
SLANG_UNEXPECTED("unknown declaration reference kind");
return false;
}
}
LoweredValInfo visitInvokeExpr(InvokeExpr* expr)
{
auto type = lowerType(context, expr->type);
// We are going to look at the syntactic form of
// the "function" expression, so that we can avoid
// a lot of complexity that would come from lowering
// it as a general expression first, and then trying
// to apply it. For example, given `obj.f(a,b)` we
// will try to detect that we are trying to compute
// something like `ObjType::f(obj, a, b)` (in pseudo-code),
// rather than trying to construct a meaningful
// intermediate value for `obj.f` first.
//
// Note that this doe not preclude having support
// for directly generating code from `obj.f` - it
// just may be that such usage is more complicated.
// Along the way, we may end up collecting additional
// arguments that will be part of the call.
List<IRInst*> irArgs;
// We will also collect "fixup" actions that need
// to be performed after the call, in order to
// copy the final values for `out` parameters
// back to their arguments.
List<OutArgumentFixup> argFixups;
auto funcExpr = expr->functionExpr;
ResolvedCallInfo resolvedInfo;
if( tryResolveDeclRefForCall(funcExpr, &resolvedInfo) )
{
// In this case we know exactly what declaration we
// are going to call, and so we can resolve things
// appropriately.
auto funcDeclRef = resolvedInfo.funcDeclRef;
auto baseExpr = resolvedInfo.baseExpr;
// First comes the `this` argument if we are calling
// a member function:
if( baseExpr )
{
auto thisType = getThisParamTypeForCallable(context, funcDeclRef);
auto irThisType = lowerType(context, thisType);
addCallArgsForParam(
irThisType,
getThisParamDirection(funcDeclRef.getDecl()),
baseExpr,
&irArgs,
&argFixups);
}
// Then we have the "direct" arguments to the call.
// These may include `out` and `inout` arguments that
// require "fixup" work on the other side.
//
auto funcType = lowerType(context, funcExpr->type);
addDirectCallArgs(expr, funcDeclRef, &irArgs, &argFixups);
auto result = emitCallToDeclRef(
context,
type,
funcDeclRef,
funcType,
irArgs);
applyOutArgumentFixups(argFixups);
return result;
}
// TODO: In this case we should be emitting code for the callee as
// an ordinary expression, then emitting the arguments according
// to the type information on the callee (e.g., which parameters
// are `out` or `inout`, and then finally emitting the `call`
// instruction.
//
// We don't currently have the case of emitting arguments according
// to function type info (instead of declaration info), and really
// this case can't occur unless we start adding first-class functions
// to the source language.
//
// For now we just bail out with an error.
//
SLANG_UNEXPECTED("could not resolve target declaration for call");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitCastToInterfaceExpr(
CastToInterfaceExpr* expr)
{
// We have an expression that is "up-casting" some concrete value
// to an existential type (aka interface type), using a subtype witness
// (which will lower as a witness table) to show that the conversion
// is valid.
//
// At the IR level, this will become a `makeExistential` instruction,
// which collects the above information into a single IR-level value.
// A dynamic CPU implementation of Slang might encode an existential
// as a "fat pointer" representation, which includes a pointer to
// data for the concrete value, plus a pointer to the witness table.
//
// Note: if/when Slang supports more general existential types, such
// as compositions of interface (e.g., `IReadable & IWritable`), then
// we should probably extend the AST and IR mechanism here to accept
// a sequence of witness tables.
//
auto existentialType = lowerType(context, expr->type);
auto concreteValue = getSimpleVal(context, lowerRValueExpr(context, expr->valueArg));
auto witnessTable = lowerSimpleVal(context, expr->witnessArg);
auto existentialValue = getBuilder()->emitMakeExistential(existentialType, concreteValue, witnessTable);
return LoweredValInfo::simple(existentialValue);
}
LoweredValInfo subscriptValue(
IRType* type,
LoweredValInfo baseVal,
IRInst* indexVal)
{
auto builder = getBuilder();
// The `tryGetAddress` operation will take a complex value representation
// and try to turn it into a single pointer, if possible.
//
baseVal = tryGetAddress(context, baseVal, TryGetAddressMode::Aggressive);
// The `materialize` operation should ensure that we only have to deal
// with the small number of base cases for lowered value representations.
//
baseVal = materialize(context, baseVal);
switch (baseVal.flavor)
{
case LoweredValInfo::Flavor::Simple:
return LoweredValInfo::simple(
builder->emitElementExtract(
type,
getSimpleVal(context, baseVal),
indexVal));
case LoweredValInfo::Flavor::Ptr:
return LoweredValInfo::ptr(
builder->emitElementAddress(
context->irBuilder->getPtrType(type),
baseVal.val,
indexVal));
default:
SLANG_UNIMPLEMENTED_X("subscript expr");
UNREACHABLE_RETURN(LoweredValInfo());
}
}
LoweredValInfo extractField(
IRType* fieldType,
LoweredValInfo base,
DeclRef<VarDecl> field)
{
return Slang::extractField(context, fieldType, base, field);
}
LoweredValInfo visitStaticMemberExpr(StaticMemberExpr* expr)
{
return emitDeclRef(context, expr->declRef,
lowerType(context, expr->type));
}
LoweredValInfo visitGenericAppExpr(GenericAppExpr* /*expr*/)
{
SLANG_UNIMPLEMENTED_X("generic application expression during code generation");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitSharedTypeExpr(SharedTypeExpr* /*expr*/)
{
SLANG_UNIMPLEMENTED_X("shared type expression during code generation");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitTaggedUnionTypeExpr(TaggedUnionTypeExpr* /*expr*/)
{
SLANG_UNIMPLEMENTED_X("tagged union type expression during code generation");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitThisTypeExpr(ThisTypeExpr* /*expr*/)
{
SLANG_UNIMPLEMENTED_X("this-type expression during code generation");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitAssignExpr(AssignExpr* expr)
{
// Because our representation of lowered "values"
// can encompass l-values explicitly, we can
// lower assignment easily. We just lower the left-
// and right-hand sides, and then perform an assignment
// based on the resulting values.
//
auto leftVal = lowerLValueExpr(context, expr->left);
auto rightVal = lowerRValueExpr(context, expr->right);
assign(context, leftVal, rightVal);
// The result value of the assignment expression is
// the value of the left-hand side (and it is expected
// to be an l-value).
return leftVal;
}
LoweredValInfo visitLetExpr(LetExpr* expr)
{
// TODO: deal with the case where we might want to capture
// a reference to the bound value...
auto initVal = lowerLValueExpr(context, expr->decl->initExpr);
setGlobalValue(context, expr->decl, initVal);
auto bodyVal = lowerSubExpr(expr->body);
return bodyVal;
}
LoweredValInfo visitExtractExistentialValueExpr(ExtractExistentialValueExpr* expr)
{
auto existentialType = lowerType(context, getType(getASTBuilder(), expr->declRef));
auto existentialVal = getSimpleVal(context, emitDeclRef(context, expr->declRef, existentialType));
auto openedType = lowerType(context, expr->type);
return LoweredValInfo::simple(getBuilder()->emitExtractExistentialValue(openedType, existentialVal));
}
};
struct LValueExprLoweringVisitor : ExprLoweringVisitorBase<LValueExprLoweringVisitor>
{
// When visiting a swizzle expression in an l-value context,
// we need to construct a "swizzled l-value."
LoweredValInfo visitMatrixSwizzleExpr(MatrixSwizzleExpr*)
{
SLANG_UNIMPLEMENTED_X("matrix swizzle lvalue case");
}
// When visiting a swizzle expression in an l-value context,
// we need to construct a "sizzled l-value."
LoweredValInfo visitSwizzleExpr(SwizzleExpr* expr)
{
auto irType = lowerType(context, expr->type);
auto loweredBase = lowerRValueExpr(context, expr->base);
RefPtr<SwizzledLValueInfo> swizzledLValue = new SwizzledLValueInfo();
swizzledLValue->type = irType;
UInt elementCount = (UInt)expr->elementCount;
swizzledLValue->elementCount = elementCount;
// As a small optimization, we will detect if the base expression
// has also lowered into a swizzle and only return a single
// swizzle instead of nested swizzles.
//
// E.g., if we have input like `foo[i].zw.y` we should optimize it
// down to just `foo[i].w`.
//
if(loweredBase.flavor == LoweredValInfo::Flavor::SwizzledLValue)
{
auto baseSwizzleInfo = loweredBase.getSwizzledLValueInfo();
// Our new swizzle will use the same base expression (e.g.,
// `foo[i]` in our example above), but will need to remap
// the swizzle indices it uses.
//
swizzledLValue->base = baseSwizzleInfo->base;
for (UInt ii = 0; ii < elementCount; ++ii)
{
// First we get the swizzle element of the "outer" swizzle,
// as it was written by the user. In our running example of
// `foo[i].zw.y` this is the `y` element reference.
//
UInt originalElementIndex = UInt(expr->elementIndices[ii]);
// Next we will use that original element index to figure
// out which of the elements of the original swizzle this
// should map to.
//
// In our example, `y` means index 1, and so we fetch
// element 1 from the inner swizzle sequence `zw`, to get `w`.
//
SLANG_ASSERT(originalElementIndex < baseSwizzleInfo->elementCount);
UInt remappedElementIndex = baseSwizzleInfo->elementIndices[originalElementIndex];
swizzledLValue->elementIndices[ii] = remappedElementIndex;
}
}
else
{
// In the default case, we can just copy the indices being
// used for the swizzle over directly from the expression,
// and use the base as-is.
//
swizzledLValue->base = loweredBase;
for (UInt ii = 0; ii < elementCount; ++ii)
{
swizzledLValue->elementIndices[ii] = (UInt) expr->elementIndices[ii];
}
}
context->shared->extValues.add(swizzledLValue);
return LoweredValInfo::swizzledLValue(swizzledLValue);
}
};
struct RValueExprLoweringVisitor : ExprLoweringVisitorBase<RValueExprLoweringVisitor>
{
// A matrix swizzle in an r-value context can save time by just
// emitting the matrix swizzle instructions directly.
LoweredValInfo visitMatrixSwizzleExpr(MatrixSwizzleExpr* expr)
{
auto resultType = lowerType(context, expr->type);
auto base = lowerSubExpr(expr->base);
auto matType = as<MatrixExpressionType>(expr->base->type.type);
if (!matType)
SLANG_UNEXPECTED("Expected a matrix type in matrix swizzle");
auto subscript2 = lowerType(context, matType->getElementType());
auto subscript1 = lowerType(context, matType->getRowType());
auto builder = getBuilder();
auto irIntType = getIntType(context);
UInt elementCount = (UInt)expr->elementCount;
IRInst* irExtracts[4];
for (UInt ii = 0; ii < elementCount; ++ii)
{
auto index1 = builder->getIntValue(
irIntType,
(IRIntegerValue)expr->elementCoords[ii].row);
auto index2 = builder->getIntValue(
irIntType,
(IRIntegerValue)expr->elementCoords[ii].col);
// First index expression
auto irExtract1 = subscriptValue(
subscript1,
base,
index1);
// Second index expression
irExtracts[ii] = getSimpleVal(context, subscriptValue(
subscript2,
irExtract1,
index2));
}
auto irVector = builder->emitMakeVector(
resultType,
elementCount,
irExtracts
);
return LoweredValInfo::simple(irVector);
}
// A swizzle in an r-value context can save time by just
// emitting the swizzle instructions directly.
LoweredValInfo visitSwizzleExpr(SwizzleExpr* expr)
{
auto irType = lowerType(context, expr->type);
auto irBase = getSimpleVal(context, lowerRValueExpr(context, expr->base));
auto builder = getBuilder();
auto irIntType = getIntType(context);
UInt elementCount = (UInt)expr->elementCount;
IRInst* irElementIndices[4];
for (UInt ii = 0; ii < elementCount; ++ii)
{
irElementIndices[ii] = builder->getIntValue(
irIntType,
(IRIntegerValue)expr->elementIndices[ii]);
}
auto irSwizzle = builder->emitSwizzle(
irType,
irBase,
elementCount,
&irElementIndices[0]);
return LoweredValInfo::simple(irSwizzle);
}
};
LoweredValInfo lowerLValueExpr(
IRGenContext* context,
Expr* expr)
{
IRBuilderSourceLocRAII sourceLocInfo(context->irBuilder, expr->loc);
LValueExprLoweringVisitor visitor;
visitor.context = context;
return visitor.dispatch(expr);
}
LoweredValInfo lowerRValueExpr(
IRGenContext* context,
Expr* expr)
{
IRBuilderSourceLocRAII sourceLocInfo(context->irBuilder, expr->loc);
RValueExprLoweringVisitor visitor;
visitor.context = context;
return visitor.dispatch(expr);
}
struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor>
{
IRGenContext* context;
IRBuilder* getBuilder() { return context->irBuilder; }
void visitEmptyStmt(EmptyStmt*)
{
// Nothing to do.
}
void visitUnparsedStmt(UnparsedStmt*)
{
SLANG_UNEXPECTED("UnparsedStmt not supported by IR");
}
void visitCaseStmtBase(CaseStmtBase*)
{
SLANG_UNEXPECTED("`case` or `default` not under `switch`");
}
void visitCompileTimeForStmt(CompileTimeForStmt* stmt)
{
// The user is asking us to emit code for the loop
// body for each value in the given integer range.
// For now, we will handle this by repeatedly lowering
// the body statement, with the loop variable bound
// to a different integer literal value each time.
//
// TODO: eventually we might handle this as just an
// ordinary loop, with an `[unroll]` attribute on
// it that we would respect.
auto rangeBeginVal = getIntVal(stmt->rangeBeginVal);
auto rangeEndVal = getIntVal(stmt->rangeEndVal);
if (rangeBeginVal >= rangeEndVal)
return;
auto varDecl = stmt->varDecl;
auto varType = lowerType(context, varDecl->type);
IRGenEnv subEnvStorage;
IRGenEnv* subEnv = &subEnvStorage;
subEnv->outer = context->env;
IRGenContext subContextStorage = *context;
IRGenContext* subContext = &subContextStorage;
subContext->env = subEnv;
for (IntegerLiteralValue ii = rangeBeginVal; ii < rangeEndVal; ++ii)
{
auto constVal = getBuilder()->getIntValue(
varType,
ii);
subEnv->mapDeclToValue[varDecl] = LoweredValInfo::simple(constVal);
lowerStmt(subContext, stmt->body);
}
}
// Create a basic block in the current function,
// so that it can be used for a label.
IRBlock* createBlock()
{
return getBuilder()->createBlock();
}
/// Does the given block have a terminator?
bool isBlockTerminated(IRBlock* block)
{
return block->getTerminator() != nullptr;
}
/// Emit a branch to the target block if the current
/// block being inserted into is not already terminated.
void emitBranchIfNeeded(IRBlock* targetBlock)
{
auto builder = getBuilder();
auto currentBlock = builder->getBlock();
// Don't emit if there is no current block.
if(!currentBlock)
return;
// Don't emit if the block already has a terminator.
if(isBlockTerminated(currentBlock))
return;
// The block is unterminated, so cap it off with
// a terminator that branches to the target.
builder->emitBranch(targetBlock);
}
/// Insert a block at the current location (ending
/// the previous block with an unconditional jump
/// if needed).
void insertBlock(IRBlock* block)
{
auto builder = getBuilder();
auto prevBlock = builder->getBlock();
auto parentFunc = prevBlock ? prevBlock->getParent() : builder->getFunc();
// If the previous block doesn't already have
// a terminator instruction, then be sure to
// emit a branch to the new block.
emitBranchIfNeeded(block);
// Add the new block to the function we are building,
// and setit as the block we will be inserting into.
parentFunc->addBlock(block);
builder->setInsertInto(block);
}
// Start a new block at the current location.
// This is just the composition of `createBlock`
// and `insertBlock`.
IRBlock* startBlock()
{
auto block = createBlock();
insertBlock(block);
return block;
}
/// Start a new block if there isn't a current
/// block that we can append to.
///
/// The `stmt` parameter is the statement we
/// are about to emit.
void startBlockIfNeeded(Stmt* stmt)
{
auto builder = getBuilder();
auto currentBlock = builder->getBlock();
// If there is a current block and it hasn't
// been terminated, then we can just use that.
if(currentBlock && !isBlockTerminated(currentBlock))
{
return;
}
// We are about to emit code *after* a terminator
// instruction, and there is no label to allow
// branching into this code, so whatever we are
// about to emit is going to be unreachable.
//
// Let's diagnose that here just to help the user.
//
// TODO: We might want to have a more robust check
// for unreachable code based on IR analysis instead,
// at which point we'd probably disable this check.
//
context->getSink()->diagnose(stmt, Diagnostics::unreachableCode);
startBlock();
}
void visitIfStmt(IfStmt* stmt)
{
auto builder = getBuilder();
startBlockIfNeeded(stmt);
auto condExpr = stmt->predicate;
auto thenStmt = stmt->positiveStatement;
auto elseStmt = stmt->negativeStatement;
auto irCond = getSimpleVal(context,
lowerRValueExpr(context, condExpr));
if (elseStmt)
{
auto thenBlock = createBlock();
auto elseBlock = createBlock();
auto afterBlock = createBlock();
builder->emitIfElse(irCond, thenBlock, elseBlock, afterBlock);
insertBlock(thenBlock);
lowerStmt(context, thenStmt);
emitBranchIfNeeded(afterBlock);
insertBlock(elseBlock);
lowerStmt(context, elseStmt);
insertBlock(afterBlock);
}
else
{
auto thenBlock = createBlock();
auto afterBlock = createBlock();
builder->emitIf(irCond, thenBlock, afterBlock);
insertBlock(thenBlock);
lowerStmt(context, thenStmt);
insertBlock(afterBlock);
}
}
void addLoopDecorations(
IRInst* inst,
Stmt* stmt)
{
if( stmt->findModifier<UnrollAttribute>() )
{
getBuilder()->addLoopControlDecoration(inst, kIRLoopControl_Unroll);
}
// TODO: handle other cases here
}
void visitForStmt(ForStmt* stmt)
{
auto builder = getBuilder();
startBlockIfNeeded(stmt);
// The initializer clause for the statement
// can always safetly be emitted to the current block.
if (auto initStmt = stmt->initialStatement)
{
lowerStmt(context, initStmt);
}
// We will create blocks for the various places
// we need to jump to inside the control flow,
// including the blocks that will be referenced
// by `continue` or `break` statements.
auto loopHead = createBlock();
auto bodyLabel = createBlock();
auto breakLabel = createBlock();
auto continueLabel = createBlock();
// Register the `break` and `continue` labels so
// that we can find them for nested statements.
context->shared->breakLabels.Add(stmt, breakLabel);
context->shared->continueLabels.Add(stmt, continueLabel);
// Emit the branch that will start out loop,
// and then insert the block for the head.
auto loopInst = builder->emitLoop(
loopHead,
breakLabel,
continueLabel);
addLoopDecorations(loopInst, stmt);
insertBlock(loopHead);
// Now that we are within the header block, we
// want to emit the expression for the loop condition:
if (auto condExpr = stmt->predicateExpression)
{
auto irCondition = getSimpleVal(context,
lowerRValueExpr(context, stmt->predicateExpression));
// Now we want to `break` if the loop condition is false.
builder->emitLoopTest(
irCondition,
bodyLabel,
breakLabel);
}
// Emit the body of the loop
insertBlock(bodyLabel);
lowerStmt(context, stmt->statement);
// Insert the `continue` block
insertBlock(continueLabel);
if (auto incrExpr = stmt->sideEffectExpression)
{
lowerRValueExpr(context, incrExpr);
}
// At the end of the body we need to jump back to the top.
emitBranchIfNeeded(loopHead);
// Finally we insert the label that a `break` will jump to
insertBlock(breakLabel);
}
void visitWhileStmt(WhileStmt* stmt)
{
// Generating IR for `while` statement is similar to a
// `for` statement, but without a lot of the complications.
auto builder = getBuilder();
startBlockIfNeeded(stmt);
// We will create blocks for the various places
// we need to jump to inside the control flow,
// including the blocks that will be referenced
// by `continue` or `break` statements.
auto loopHead = createBlock();
auto bodyLabel = createBlock();
auto breakLabel = createBlock();
// A `continue` inside a `while` loop always
// jumps to the head of hte loop.
auto continueLabel = loopHead;
// Register the `break` and `continue` labels so
// that we can find them for nested statements.
context->shared->breakLabels.Add(stmt, breakLabel);
context->shared->continueLabels.Add(stmt, continueLabel);
// Emit the branch that will start out loop,
// and then insert the block for the head.
auto loopInst = builder->emitLoop(
loopHead,
breakLabel,
continueLabel);
addLoopDecorations(loopInst, stmt);
insertBlock(loopHead);
// Now that we are within the header block, we
// want to emit the expression for the loop condition:
if (auto condExpr = stmt->predicate)
{
auto irCondition = getSimpleVal(context,
lowerRValueExpr(context, condExpr));
// Now we want to `break` if the loop condition is false.
builder->emitLoopTest(
irCondition,
bodyLabel,
breakLabel);
}
// Emit the body of the loop
insertBlock(bodyLabel);
lowerStmt(context, stmt->statement);
// At the end of the body we need to jump back to the top.
emitBranchIfNeeded(loopHead);
// Finally we insert the label that a `break` will jump to
insertBlock(breakLabel);
}
void visitDoWhileStmt(DoWhileStmt* stmt)
{
// Generating IR for `do {...} while` statement is similar to a
// `while` statement, just with the test in a different place
auto builder = getBuilder();
startBlockIfNeeded(stmt);
// We will create blocks for the various places
// we need to jump to inside the control flow,
// including the blocks that will be referenced
// by `continue` or `break` statements.
auto loopHead = createBlock();
auto testLabel = createBlock();
auto breakLabel = createBlock();
// A `continue` inside a `do { ... } while ( ... )` loop always
// jumps to the loop test.
auto continueLabel = testLabel;
// Register the `break` and `continue` labels so
// that we can find them for nested statements.
context->shared->breakLabels.Add(stmt, breakLabel);
context->shared->continueLabels.Add(stmt, continueLabel);
// Emit the branch that will start out loop,
// and then insert the block for the head.
auto loopInst = builder->emitLoop(
loopHead,
breakLabel,
continueLabel);
addLoopDecorations(loopInst, stmt);
insertBlock(loopHead);
// Emit the body of the loop
lowerStmt(context, stmt->statement);
insertBlock(testLabel);
// Now that we are within the header block, we
// want to emit the expression for the loop condition:
if (auto condExpr = stmt->predicate)
{
auto irCondition = getSimpleVal(context,
lowerRValueExpr(context, condExpr));
// Now we want to `break` if the loop condition is false,
// otherwise we will jump back to the head of the loop.
builder->emitLoopTest(
irCondition,
loopHead,
breakLabel);
}
// Finally we insert the label that a `break` will jump to
insertBlock(breakLabel);
}
void visitExpressionStmt(ExpressionStmt* stmt)
{
startBlockIfNeeded(stmt);
// The statement evaluates an expression
// (for side effects, one assumes) and then
// discards the result. As such, we simply
// lower the expression, and don't use
// the result.
//
// Note that we lower using the l-value path,
// so that an expression statement that names
// a location (but doesn't load from it)
// will not actually emit a load.
lowerLValueExpr(context, stmt->expression);
}
void visitDeclStmt(DeclStmt* stmt)
{
startBlockIfNeeded(stmt);
// For now, we lower a declaration directly
// into the current context.
//
// TODO: We may want to consider whether
// nested type/function declarations should
// be lowered into the global scope during
// IR generation, or whether they should
// be lifted later (pushing capture analysis
// down to the IR).
//
lowerDecl(context, stmt->decl);
}
void visitSeqStmt(SeqStmt* stmt)
{
// To lower a sequence of statements,
// just lower each in order
for (auto ss : stmt->stmts)
{
lowerStmt(context, ss);
}
}
void visitBlockStmt(BlockStmt* stmt)
{
// To lower a block (scope) statement,
// just lower its body. The IR doesn't
// need to reflect the scoping of the AST.
lowerStmt(context, stmt->body);
}
void visitReturnStmt(ReturnStmt* stmt)
{
startBlockIfNeeded(stmt);
// A `return` statement turns into a return
// instruction. If the statement had an argument
// expression, then we need to lower that to
// a value first, and then emit the resulting value.
if( auto expr = stmt->expression )
{
auto loweredExpr = lowerRValueExpr(context, expr);
getBuilder()->emitReturn(getSimpleVal(context, loweredExpr));
}
else
{
getBuilder()->emitReturn();
}
}
void visitDiscardStmt(DiscardStmt* stmt)
{
startBlockIfNeeded(stmt);
getBuilder()->emitDiscard();
}
void visitBreakStmt(BreakStmt* stmt)
{
startBlockIfNeeded(stmt);
// Semantic checking is responsible for finding
// the statement taht this `break` breaks out of
auto parentStmt = stmt->parentStmt;
SLANG_ASSERT(parentStmt);
// We just need to look up the basic block that
// corresponds to the break label for that statement,
// and then emit an instruction to jump to it.
IRBlock* targetBlock = nullptr;
context->shared->breakLabels.TryGetValue(parentStmt, targetBlock);
SLANG_ASSERT(targetBlock);
getBuilder()->emitBreak(targetBlock);
}
void visitContinueStmt(ContinueStmt* stmt)
{
startBlockIfNeeded(stmt);
// Semantic checking is responsible for finding
// the loop that this `continue` statement continues
auto parentStmt = stmt->parentStmt;
SLANG_ASSERT(parentStmt);
// We just need to look up the basic block that
// corresponds to the continue label for that statement,
// and then emit an instruction to jump to it.
IRBlock* targetBlock = nullptr;
context->shared->continueLabels.TryGetValue(parentStmt, targetBlock);
SLANG_ASSERT(targetBlock);
getBuilder()->emitContinue(targetBlock);
}
// Lowering a `switch` statement can get pretty involved,
// so we need to track a bit of extra data:
struct SwitchStmtInfo
{
// The block that will be made to contain the `switch` statement
IRBlock* initialBlock = nullptr;
// The label for the `default` case, if any.
IRBlock* defaultLabel = nullptr;
// The label of the current "active" case block.
IRBlock* currentCaseLabel = nullptr;
// Has anything been emitted to the current "active" case block?
bool anythingEmittedToCurrentCaseBlock = false;
// The collected (value, label) pairs for
// all the `case` statements.
List<IRInst*> cases;
};
// We need a label to use for a `case` or `default` statement,
// so either create one here, or re-use the current one if
// that is okay.
IRBlock* getLabelForCase(SwitchStmtInfo* info)
{
// Look at the "current" label we are working with.
auto currentCaseLabel = info->currentCaseLabel;
// If there is a current block, and it is empty,
// then it is still a viable target (we are in
// a case of "trivial fall-through" from the previous
// block).
if(currentCaseLabel && !info->anythingEmittedToCurrentCaseBlock)
{
return currentCaseLabel;
}
// Othwerise, we need to start a new block and use that.
IRBlock* newCaseLabel = createBlock();
// Note: if the previous block failed
// to end with a `break`, then inserting
// this block will append an unconditional
// branch to the end of it that will target
// this block.
insertBlock(newCaseLabel);
info->currentCaseLabel = newCaseLabel;
info->anythingEmittedToCurrentCaseBlock = false;
return newCaseLabel;
}
bool hasSwitchCases(Stmt* inStmt)
{
Stmt* stmt = inStmt;
// Unwrap any surrounding `{ ... }` so we can look
// at the statement inside.
while (auto blockStmt = as<BlockStmt>(stmt))
{
stmt = blockStmt->body;
continue;
}
if (auto seqStmt = as<SeqStmt>(stmt))
{
// Walk through the children looking for cases
for (auto childStmt : seqStmt->stmts)
{
if (hasSwitchCases(childStmt))
{
return true;
}
}
}
else if (auto caseStmt = as<CaseStmt>(stmt))
{
return true;
}
else if (auto defaultStmt = as<DefaultStmt>(stmt))
{
// A 'default:' is a kind of case.
return true;
}
return false;
}
// Given a statement that appears as (or in) the body
// of a `switch` statement
void lowerSwitchCases(Stmt* inStmt, SwitchStmtInfo* info)
{
// TODO: in the general case (e.g., if we were going
// to eventual lower to an unstructured format like LLVM),
// the Right Way to handle C-style `switch` statements
// is just to emit the body directly as "normal" statements,
// and then treat `case` and `default` as special statements
// that start a new block and register a label with the
// enclosing `switch`.
//
// For now we will assume that any `case` and `default`
// statements need to be directly nested under the `switch`,
// and so we can find them with a simpler walk.
Stmt* stmt = inStmt;
// Unwrap any surrounding `{ ... }` so we can look
// at the statement inside.
while(auto blockStmt = as<BlockStmt>(stmt))
{
stmt = blockStmt->body;
continue;
}
if(auto seqStmt = as<SeqStmt>(stmt))
{
// Walk through teh children and process each.
for(auto childStmt : seqStmt->stmts)
{
lowerSwitchCases(childStmt, info);
}
}
else if(auto caseStmt = as<CaseStmt>(stmt))
{
// A full `case` statement has a value we need
// to test against. It is expected to be a
// compile-time constant, so we will emit
// it like an expression here, and then hope
// for the best.
//
// TODO: figure out something cleaner.
// Actually, one gotcha is that if we ever allow non-constant
// expressions here (or anything that requires instructions
// to be emitted to yield its value), then those instructions
// need to go into an appropriate block.
IRGenContext subContext = *context;
IRBuilder subBuilder = *getBuilder();
subBuilder.setInsertInto(info->initialBlock);
subContext.irBuilder = &subBuilder;
auto caseVal = getSimpleVal(context, lowerRValueExpr(&subContext, caseStmt->expr));
// Figure out where we are branching to.
auto label = getLabelForCase(info);
// Add this `case` to the list for the enclosing `switch`.
info->cases.add(caseVal);
info->cases.add(label);
}
else if(auto defaultStmt = as<DefaultStmt>(stmt))
{
auto label = getLabelForCase(info);
// We expect to only find a single `default` stmt.
SLANG_ASSERT(!info->defaultLabel);
info->defaultLabel = label;
}
else if(auto emptyStmt = as<EmptyStmt>(stmt))
{
// Special-case empty statements so they don't
// mess up our "trivial fall-through" optimization.
}
else
{
// We have an ordinary statement, that needs to get
// emitted to the current case block.
if(!info->currentCaseLabel)
{
// It possible in full C/C++ to have statements
// before the first `case`. Usually these are
// unreachable, unless they start with a label.
//
// We'll ignore them here, figuring they are
// dead. If we ever add `LabelStmt` then we'd
// need to emit these statements to a dummy
// block just in case.
}
else
{
// Emit the code to our current case block,
// and record that we've done so.
lowerStmt(context, stmt);
info->anythingEmittedToCurrentCaseBlock = true;
}
}
}
void visitSwitchStmt(SwitchStmt* stmt)
{
auto builder = getBuilder();
startBlockIfNeeded(stmt);
// Given a statement:
//
// switch( CONDITION )
// {
// case V0:
// S0;
// break;
//
// case V1:
// default:
// S1;
// break;
// }
//
// we want to generate IR like:
//
// let %c = <CONDITION>;
// switch %c, // value to switch on
// %breakLabel, // join point (and break target)
// %s1, // default label
// %v0, // first case value
// %s0, // first case label
// %v1, // second case value
// %s1 // second case label
// s0:
// <S0>
// break %breakLabel
// s1:
// <S1>
// break %breakLabel
// breakLabel:
//
// First emit code to compute the condition:
auto conditionVal = getSimpleVal(context, lowerRValueExpr(context, stmt->condition));
// Check for any cases or default.
if (!hasSwitchCases(stmt->body))
{
// If we don't have any case/default then nothing inside switch can be executed (other than condition)
// so we are done.
return;
}
// Remember the initial block so that we can add to it
// after we've collected all the `case`s
auto initialBlock = builder->getBlock();
// Next, create a block to use as the target for any `break` statements
auto breakLabel = createBlock();
// Register the `break` label so
// that we can find it for nested statements.
context->shared->breakLabels.Add(stmt, breakLabel);
builder->setInsertInto(initialBlock->getParent());
// Iterate over the body of the statement, looking
// for `case` or `default` statements:
SwitchStmtInfo info;
info.initialBlock = initialBlock;
info.defaultLabel = nullptr;
lowerSwitchCases(stmt->body, &info);
// TODO: once we've discovered the cases, we should
// be able to make a quick pass over the list and eliminate
// any cases that have the exact same label as the `default`
// case, since these don't actually need to be represented.
// If the current block (the end of the last
// `case`) is not terminated, then terminate with a
// `break` operation.
//
// Double check that we aren't in the initial
// block, so we don't get tripped up on an
// empty `switch`.
auto curBlock = builder->getBlock();
if(curBlock != initialBlock)
{
// Is the block already terminated?
if(!curBlock->getTerminator())
{
// Not terminated, so add one.
builder->emitBreak(breakLabel);
}
}
// If there was no `default` statement, then the
// default case will just branch directly to the end.
auto defaultLabel = info.defaultLabel ? info.defaultLabel : breakLabel;
// Now that we've collected the cases, we are
// prepared to emit the `switch` instruction
// itself.
builder->setInsertInto(initialBlock);
builder->emitSwitch(
conditionVal,
breakLabel,
defaultLabel,
info.cases.getCount(),
info.cases.getBuffer());
// Finally we insert the label that a `break` will jump to
// (and that control flow will fall through to otherwise).
// This is the block that subsequent code will go into.
insertBlock(breakLabel);
context->shared->breakLabels.Remove(stmt);
}
};
void lowerStmt(
IRGenContext* context,
Stmt* stmt)
{
IRBuilderSourceLocRAII sourceLocInfo(context->irBuilder, stmt->loc);
StmtLoweringVisitor visitor;
visitor.context = context;
try
{
visitor.dispatch(stmt);
}
// Don't emit any context message for an explicit `AbortCompilationException`
// because it should only happen when an error is already emitted.
catch(const AbortCompilationException&) { throw; }
catch(...)
{
context->getSink()->noteInternalErrorLoc(stmt->loc);
throw;
}
}
/// Create and return a mutable temporary initialized with `val`
static LoweredValInfo moveIntoMutableTemp(
IRGenContext* context,
LoweredValInfo const& val)
{
IRInst* irVal = getSimpleVal(context, val);
auto type = irVal->getDataType();
auto var = createVar(context, type);
assign(context, var, LoweredValInfo::simple(irVal));
return var;
}
LoweredValInfo tryGetAddress(
IRGenContext* context,
LoweredValInfo const& inVal,
TryGetAddressMode mode)
{
LoweredValInfo val = inVal;
switch(val.flavor)
{
case LoweredValInfo::Flavor::Ptr:
// The `Ptr` case means that we already have an IR value with
// the address of our value. Easy!
return val;
case LoweredValInfo::Flavor::BoundSubscript:
{
// If we are are trying to turn a subscript operation like `buffer[index]`
// into a pointer, then we need to find a `ref` accessor declared
// as part of the subscript operation being referenced.
//
auto subscriptInfo = val.getBoundSubscriptInfo();
// We don't want to immediately bind to a `ref` accessor if there is
// a `set` accessor available, unless we are in an "aggressive" mode
// where we really want/need a pointer to be able to make progress.
//
if(mode != TryGetAddressMode::Aggressive
&& getMembersOfType<SetterDecl>(subscriptInfo->declRef, MemberFilterStyle::Instance).isNonEmpty())
{
// There is a setter that we should consider using,
// so don't go and aggressively collapse things just yet.
return val;
}
auto refAccessors = getMembersOfType<RefAccessorDecl>(subscriptInfo->declRef, MemberFilterStyle::Instance);
if(refAccessors.isNonEmpty())
{
// The `ref` accessor will return a pointer to the value, so
// we need to reflect that in the type of our `call` instruction.
IRType* ptrType = context->irBuilder->getPtrType(subscriptInfo->type);
LoweredValInfo refVal = emitCallToDeclRef(
context,
ptrType,
*refAccessors.begin(),
nullptr,
subscriptInfo->args);
// The result from the call should be a pointer, and it
// is the address that we wanted in the first place.
return LoweredValInfo::ptr(getSimpleVal(context, refVal));
}
// Otherwise, there was no `ref` accessor, and so it is not possible
// to materialize this location into a pointer for whatever purpose
// we have in mind (e.g., passing it to an atomic operation).
}
break;
case LoweredValInfo::Flavor::BoundMember:
{
auto boundMemberInfo = val.getBoundMemberInfo();
// If we hit this case, then it means that we have a reference
// to a single field in something, but for whatever reason the
// higher-level logic was not able to turn it into a pointer
// already (maybe the base value for the field reference is
// a `BoundSubscript`, etc.).
//
// We need to read the entire base value out, modify the field
// we care about, and then write it back.
auto declRef = boundMemberInfo->declRef;
if( auto fieldDeclRef = declRef.as<VarDecl>() )
{
auto baseVal = boundMemberInfo->base;
auto basePtr = tryGetAddress(context, baseVal, TryGetAddressMode::Aggressive);
return extractField(context, boundMemberInfo->type, basePtr, fieldDeclRef);
}
}
break;
case LoweredValInfo::Flavor::SwizzledLValue:
{
auto originalSwizzleInfo = val.getSwizzledLValueInfo();
auto originalBase = originalSwizzleInfo->base;
UInt elementCount = originalSwizzleInfo->elementCount;
auto newBase = tryGetAddress(context, originalBase, TryGetAddressMode::Aggressive);
RefPtr<SwizzledLValueInfo> newSwizzleInfo = new SwizzledLValueInfo();
context->shared->extValues.add(newSwizzleInfo);
newSwizzleInfo->base = newBase;
newSwizzleInfo->type = originalSwizzleInfo->type;
newSwizzleInfo->elementCount = elementCount;
for(UInt ee = 0; ee < elementCount; ++ee)
newSwizzleInfo->elementIndices[ee] = originalSwizzleInfo->elementIndices[ee];
return LoweredValInfo::swizzledLValue(newSwizzleInfo);
}
break;
// TODO: are there other cases we need to handled here?
default:
break;
}
// If none of the special cases above applied, then we werent' able to make
// this value into a pointer, and we should just return it as-is.
return val;
}
IRInst* getAddress(
IRGenContext* context,
LoweredValInfo const& inVal,
SourceLoc diagnosticLocation)
{
LoweredValInfo val = tryGetAddress(context, inVal, TryGetAddressMode::Aggressive);
if( val.flavor == LoweredValInfo::Flavor::Ptr )
{
return val.val;
}
context->getSink()->diagnose(diagnosticLocation, Diagnostics::invalidLValueForRefParameter);
return nullptr;
}
void assign(
IRGenContext* context,
LoweredValInfo const& inLeft,
LoweredValInfo const& inRight)
{
LoweredValInfo left = inLeft;
LoweredValInfo right = inRight;
// Before doing the case analysis on the shape of the `left` value,
// we might as well go ahead and see if we can coerce it into
// a simple pointer, since that would make our life a lot easier
// when handling complex cases.
//
left = tryGetAddress(context, left, TryGetAddressMode::Default);
auto builder = context->irBuilder;
top:
switch (left.flavor)
{
case LoweredValInfo::Flavor::Ptr:
{
// The `left` value is just a pointer, so we can emit
// a store to it directly.
//
builder->emitStore(
left.val,
getSimpleVal(context, right));
}
break;
case LoweredValInfo::Flavor::SwizzledLValue:
{
// The `left` value is of the form `<base>.<swizzleElements>`.
// How we will handle this depends on what `base` looks like:
auto swizzleInfo = left.getSwizzledLValueInfo();
auto loweredBase = swizzleInfo->base;
// Note that the call to `tryGetAddress` at the start should
// ensure that `loweredBase` has been simplified as much as
// possible (e.g., if it is possible to turn it into a
// `LoweredValInfo::ptr()` then that will have been done).
switch( loweredBase.flavor )
{
default:
{
// Our fallback position is to lower via a temporary, e.g.:
//
// float4 tmp = <base>;
// tmp.xyz = float3(...);
// <base> = tmp;
//
// Load from the base value
IRInst* irLeftVal = getSimpleVal(context, loweredBase);
// Extract a simple value for the right-hand side
IRInst* irRightVal = getSimpleVal(context, right);
// Apply the swizzle
IRInst* irSwizzled = builder->emitSwizzleSet(
irLeftVal->getDataType(),
irLeftVal,
irRightVal,
swizzleInfo->elementCount,
swizzleInfo->elementIndices);
// And finally, store the value back where we got it.
//
// Note: this is effectively a recursive call to
// `assign()`, so we do a simple tail-recursive call here.
left = loweredBase;
right = LoweredValInfo::simple(irSwizzled);
goto top;
}
break;
case LoweredValInfo::Flavor::Ptr:
{
// We are writing through a pointer, which might be
// pointing into a UAV or other memory resource, so
// we can't introduce use a temporary like the case
// above, because then we would read and write bytes
// that are not strictly required for the store.
//
// Note that the messy case of a "swizzle of a swizzle"
// was handled already in lowering of a `SwizzleExpr`,
// so that we don't need to deal with that case here.
//
// TODO: we may need to consider whether there is
// enough value in a masked store like this to keep
// it around, in comparison to a simpler model where
// we simply form a pointer to each of the vector
// elements and write to them individually.
//
// TODO: we might also consider just special-casing
// single-element swizzles so that the common case
// can turn into a simple `store` instead of a
// `swizzledStore`.
//
IRInst* irRightVal = getSimpleVal(context, right);
builder->emitSwizzledStore(
loweredBase.val,
irRightVal,
swizzleInfo->elementCount,
swizzleInfo->elementIndices);
}
break;
}
}
break;
case LoweredValInfo::Flavor::BoundSubscript:
{
// The `left` value refers to a subscript operation on
// a resource type, bound to particular arguments, e.g.:
// `someStructuredBuffer[index]`.
//
// When storing to such a value, we need to emit a call
// to the appropriate builtin "setter" accessor, if there
// is one, and then fall back to a `ref` accessor if
// there is no setter.
//
auto subscriptInfo = left.getBoundSubscriptInfo();
// Search for an appropriate "setter" declaration
auto setters = getMembersOfType<SetterDecl>(subscriptInfo->declRef, MemberFilterStyle::Instance);
if (setters.isNonEmpty())
{
auto allArgs = subscriptInfo->args;
addArgs(context, &allArgs, right);
emitCallToDeclRef(
context,
builder->getVoidType(),
*setters.begin(),
nullptr,
allArgs);
return;
}
auto refAccessors = getMembersOfType<RefAccessorDecl>(subscriptInfo->declRef, MemberFilterStyle::Instance);
if(refAccessors.isNonEmpty())
{
// The `ref` accessor will return a pointer to the value, so
// we need to reflect that in the type of our `call` instruction.
IRType* ptrType = context->irBuilder->getPtrType(subscriptInfo->type);
LoweredValInfo refVal = emitCallToDeclRef(
context,
ptrType,
*refAccessors.begin(),
nullptr,
subscriptInfo->args);
// The result from the call needs to be implicitly dereferenced,
// so that it can work as an l-value of the desired result type.
left = LoweredValInfo::ptr(getSimpleVal(context, refVal));
// Tail-recursively attempt assignment again on the new l-value.
goto top;
}
// No setter found? Then we have an error!
SLANG_UNEXPECTED("no setter found");
break;
}
break;
case LoweredValInfo::Flavor::BoundMember:
{
auto boundMemberInfo = left.getBoundMemberInfo();
// If we hit this case, then it means that we are trying to set
// a single field in someting that is not atomically set-able.
// (e.g., an element of a value where the `subscript` operation
// has `get` and `set` but not a `ref` accessor).
//
// We need to read the entire base value out, modify the field
// we care about, and then write it back.
auto declRef = boundMemberInfo->declRef;
if( auto fieldDeclRef = declRef.as<VarDecl>() )
{
// materialize the base value and move it into
// a mutable temporary if needed
auto baseVal = boundMemberInfo->base;
auto tempVal = moveIntoMutableTemp(context, baseVal);
// extract the field l-value out of the temporary
auto tempFieldVal = extractField(context, boundMemberInfo->type, tempVal, fieldDeclRef);
// assign to the field of the temporary l-value
assign(context, tempFieldVal, right);
// write back the modified temporary to the base l-value
assign(context, baseVal, tempVal);
return;
}
else
{
SLANG_UNEXPECTED("handled member flavor");
}
}
break;
default:
SLANG_UNIMPLEMENTED_X("assignment");
break;
}
}
struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
{
IRGenContext* context;
DiagnosticSink* getSink() { return context->getSink(); }
IRBuilder* getBuilder()
{
return context->irBuilder;
}
LoweredValInfo visitDeclBase(DeclBase* /*decl*/)
{
SLANG_UNIMPLEMENTED_X("decl catch-all");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitDecl(Decl* /*decl*/)
{
SLANG_UNIMPLEMENTED_X("decl catch-all");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitExtensionDecl(ExtensionDecl* decl)
{
for (auto & member : decl->members)
ensureDecl(context, member);
return LoweredValInfo();
}
#define IGNORED_CASE(NAME) \
LoweredValInfo visit##NAME(NAME*) { return LoweredValInfo(); }
IGNORED_CASE(ImportDecl)
IGNORED_CASE(EmptyDecl)
IGNORED_CASE(SyntaxDecl)
IGNORED_CASE(AttributeDecl)
IGNORED_CASE(NamespaceDecl)
#undef IGNORED_CASE
LoweredValInfo visitTypeDefDecl(TypeDefDecl* decl)
{
// A type alias declaration may be generic, if it is
// nested under a generic type/function/etc.
//
NestedContext nested(this);
auto subBuilder = nested.getBuilder();
auto subContext = nested.getContext();
IRGeneric* outerGeneric = emitOuterGenerics(subContext, decl, decl);
// TODO: if a type alias declaration can have linkage,
// we will need to lower it to some kind of global
// value in the IR so that we can attach a name to it.
//
// For now, we can only attach a name *if* the type
// alias is somehow generic.
if(outerGeneric)
{
addLinkageDecoration(context, outerGeneric, decl);
}
auto type = lowerType(subContext, decl->type.type);
return LoweredValInfo::simple(finishOuterGenerics(subBuilder, type));
}
LoweredValInfo visitGenericTypeParamDecl(GenericTypeParamDecl* /*decl*/)
{
return LoweredValInfo();
}
LoweredValInfo visitGenericTypeConstraintDecl(GenericTypeConstraintDecl* decl)
{
// This might be a type constraint on an associated type,
// in which case it should lower as the key for that
// interface requirement.
if(auto assocTypeDecl = as<AssocTypeDecl>(decl->parentDecl))
{
// TODO: might need extra steps if we ever allow
// generic associated types.
if(auto interfaceDecl = as<InterfaceDecl>(assocTypeDecl->parentDecl))
{
// Okay, this seems to be an interface rquirement, and
// we should lower it as such.
return LoweredValInfo::simple(getInterfaceRequirementKey(decl));
}
}
if(auto globalGenericParamDecl = as<GlobalGenericParamDecl>(decl->parentDecl))
{
// This is a constraint on a global generic type parameters,
// and so it should lower as a parameter of its own.
auto inst = getBuilder()->emitGlobalGenericWitnessTableParam();
addLinkageDecoration(context, inst, decl);
return LoweredValInfo::simple(inst);
}
// Otherwise we really don't expect to see a type constraint
// declaration like this during lowering, because a generic
// should have set up a parameter for any constraints as
// part of being lowered.
SLANG_UNEXPECTED("generic type constraint during lowering");
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitGlobalGenericParamDecl(GlobalGenericParamDecl* decl)
{
auto inst = getBuilder()->emitGlobalGenericTypeParam();
addLinkageDecoration(context, inst, decl);
return LoweredValInfo::simple(inst);
}
LoweredValInfo visitGlobalGenericValueParamDecl(GlobalGenericValueParamDecl* decl)
{
auto builder = getBuilder();
auto type = lowerType(context, decl->type);
auto inst = builder->emitGlobalGenericParam(type);
addLinkageDecoration(context, inst, decl);
return LoweredValInfo::simple(inst);
}
void lowerWitnessTable(
IRGenContext* subContext,
WitnessTable* astWitnessTable,
IRWitnessTable* irWitnessTable,
Dictionary<WitnessTable*, IRWitnessTable*> mapASTToIRWitnessTable)
{
auto subBuilder = subContext->irBuilder;
for(auto entry : astWitnessTable->requirementDictionary)
{
auto requiredMemberDecl = entry.Key;
auto satisfyingWitness = entry.Value;
auto irRequirementKey = getInterfaceRequirementKey(requiredMemberDecl);
IRInst* irSatisfyingVal = nullptr;
switch(satisfyingWitness.getFlavor())
{
case RequirementWitness::Flavor::declRef:
{
auto satisfyingDeclRef = satisfyingWitness.getDeclRef();
irSatisfyingVal = getSimpleVal(subContext,
emitDeclRef(subContext, satisfyingDeclRef,
// TODO: we need to know what type to plug in here...
nullptr));
}
break;
case RequirementWitness::Flavor::val:
{
auto satisfyingVal = satisfyingWitness.getVal();
irSatisfyingVal = lowerSimpleVal(subContext, satisfyingVal);
}
break;
case RequirementWitness::Flavor::witnessTable:
{
auto astReqWitnessTable = satisfyingWitness.getWitnessTable();
IRWitnessTable* irSatisfyingWitnessTable = nullptr;
if(!mapASTToIRWitnessTable.TryGetValue(astReqWitnessTable, irSatisfyingWitnessTable))
{
// Need to construct a sub-witness-table
irSatisfyingWitnessTable = subBuilder->createWitnessTable();
// Recursively lower the sub-table.
lowerWitnessTable(
subContext,
astReqWitnessTable,
irSatisfyingWitnessTable,
mapASTToIRWitnessTable);
irSatisfyingWitnessTable->moveToEnd();
}
irSatisfyingVal = irSatisfyingWitnessTable;
}
break;
default:
SLANG_UNEXPECTED("handled requirement witness case");
break;
}
subBuilder->createWitnessTableEntry(
irWitnessTable,
irRequirementKey,
irSatisfyingVal);
}
}
LoweredValInfo visitInheritanceDecl(InheritanceDecl* inheritanceDecl)
{
// An inheritance clause inside of an `interface`
// declaration should not give rise to a witness
// table, because it represents something the
// interface requires, and not what it provides.
//
auto parentDecl = inheritanceDecl->parentDecl;
if (auto parentInterfaceDecl = as<InterfaceDecl>(parentDecl))
{
return LoweredValInfo::simple(getInterfaceRequirementKey(inheritanceDecl));
}
//
// We also need to cover the case where an `extension`
// declaration is being used to add a conformance to
// an existing `interface`:
//
if(auto parentExtensionDecl = as<ExtensionDecl>(parentDecl))
{
auto targetType = parentExtensionDecl->targetType;
if(auto targetDeclRefType = as<DeclRefType>(targetType))
{
if(auto targetInterfaceDeclRef = targetDeclRefType->declRef.as<InterfaceDecl>())
{
return LoweredValInfo::simple(getInterfaceRequirementKey(inheritanceDecl));
}
}
}
// Find the type that is doing the inheriting.
// Under normal circumstances it is the type declaration that
// is the parent for the inheritance declaration, but if
// the inheritance declaration is on an `extension` declaration,
// then we need to identify the type being extended.
//
RefPtr<Type> subType;
if (auto extParentDecl = as<ExtensionDecl>(parentDecl))
{
subType = extParentDecl->targetType.type;
}
else
{
subType = DeclRefType::create(context->astBuilder, makeDeclRef(parentDecl));
}
// What is the super-type that we have declared we inherit from?
RefPtr<Type> superType = inheritanceDecl->base.type;
// Construct the mangled name for the witness table, which depends
// on the type that is conforming, and the type that it conforms to.
//
// TODO: This approach doesn't really make sense for generic `extension` conformances.
auto mangledName = getMangledNameForConformanceWitness(context->astBuilder, subType, superType);
// A witness table may need to be generic, if the outer
// declaration (either a type declaration or an `extension`)
// is generic.
//
NestedContext nested(this);
auto subBuilder = nested.getBuilder();
auto subContext = nested.getContext();
emitOuterGenerics(subContext, inheritanceDecl, inheritanceDecl);
// Lower the super-type to force its declaration to be lowered.
//
// Note: we are using the "sub-context" here because the
// type being inherited from could reference generic parameters,
// and we need those parameters to lower as references to
// the parameters of our IR-level generic.
//
lowerType(subContext, superType);
// Create the IR-level witness table
auto irWitnessTable = subBuilder->createWitnessTable();
addLinkageDecoration(context, irWitnessTable, inheritanceDecl, mangledName.getUnownedSlice());
// Register the value now, rather than later, to avoid any possible infinite recursion.
setGlobalValue(context, inheritanceDecl, LoweredValInfo::simple(irWitnessTable));
// Make sure that all the entries in the witness table have been filled in,
// including any cases where there are sub-witness-tables for conformances
Dictionary<WitnessTable*, IRWitnessTable*> mapASTToIRWitnessTable;
lowerWitnessTable(
subContext,
inheritanceDecl->witnessTable,
irWitnessTable,
mapASTToIRWitnessTable);
irWitnessTable->moveToEnd();
return LoweredValInfo::simple(finishOuterGenerics(subBuilder, irWitnessTable));
}
LoweredValInfo visitDeclGroup(DeclGroup* declGroup)
{
// To lower a group of declarations, we just
// lower each one individually.
//
for (auto decl : declGroup->decls)
{
IRBuilderSourceLocRAII sourceLocInfo(context->irBuilder, decl->loc);
// Note: I am directly invoking `dispatch` here,
// instead of `ensureDecl` just to try and
// make sure that we don't accidentally
// emit things to an outer context.
//
// TODO: make sure that can't happen anyway.
dispatch(decl);
}
return LoweredValInfo();
}
LoweredValInfo visitSubscriptDecl(SubscriptDecl* decl)
{
// A subscript operation may encompass one or more
// accessors, and these are what should actually
// get lowered (they are effectively functions).
for (auto accessor : decl->getMembersOfType<AccessorDecl>())
{
if (accessor->hasModifier<IntrinsicOpModifier>())
continue;
ensureDecl(context, accessor);
}
// The subscript declaration itself won't correspond
// to anything in the lowered program, so we don't
// bother creating a representation here.
//
// Note: We may want to have a specific lowered value
// that can represent the combination of callables
// that make up the subscript operation.
return LoweredValInfo();
}
bool isGlobalVarDecl(VarDecl* decl)
{
auto parent = decl->parentDecl;
if (as<NamespaceDeclBase>(parent))
{
// Variable declared at global/namespace scope? -> Global.
return true;
}
else if(as<AggTypeDeclBase>(parent))
{
if(decl->hasModifier<HLSLStaticModifier>())
{
// A `static` member variable is effectively global.
return true;
}
}
return false;
}
bool isMemberVarDecl(VarDecl* decl)
{
auto parent = decl->parentDecl;
if (as<AggTypeDecl>(parent))
{
// A variable declared inside of an aggregate type declaration is a member.
return true;
}
return false;
}
LoweredValInfo lowerGlobalShaderParam(VarDecl* decl)
{
IRType* paramType = lowerType(context, decl->getType());
auto builder = getBuilder();
auto irParam = builder->createGlobalParam(paramType);
auto paramVal = LoweredValInfo::simple(irParam);
addLinkageDecoration(context, irParam, decl);
addNameHint(context, irParam, decl);
maybeSetRate(context, irParam, decl);
addVarDecorations(context, irParam, decl);
if (decl)
{
builder->addHighLevelDeclDecoration(irParam, decl);
}
// A global variable's SSA value is a *pointer* to
// the underlying storage.
setGlobalValue(context, decl, paramVal);
irParam->moveToEnd();
return paramVal;
}
LoweredValInfo lowerConstantDeclCommon(VarDeclBase* decl, IRGenContext* subContext)
{
auto builder = subContext->irBuilder;
auto initExpr = decl->initExpr;
// We want to be able to support cases where a global constant is defined in
// another module and we should not bind to its value at (front-end) compile
// time. We handle this by adding a level of indirection where a global constant
// is represented as an IR node with zero or one operands. In the zero-operand
// case the node represents a global constant with an unknown value (perhaps
// an imported constant), while in the one-operand case the operand gives us
// the concrete value to use for the constant.
//
// Using a level of indirection also gives us a well-defined place to attach
// annotation information like name hints, since otherwise two constants
// with the same value would map to identical IR nodes.
//
// TODO: For now we detect whether or not to include the value operand based on
// whether we see an initial-value expression in the AST declaration, but
// eventually we might base this on whether or not the value should be accessible
// to the module we are lowering.
IRInst* irConstant = nullptr;
if(!initExpr)
{
// If we don't know the value we want to use, then we just create
// a global constant IR node with the right type.
//
auto irType = lowerType(subContext, decl->getType());
irConstant = builder->emitGlobalConstant(irType);
}
else
{
// We lower the value expression directly, which yields a
// global instruction to represent the value. There is
// no guarantee that this instruction is unique (e.g.,
// if we have two different constants definitions both
// with the value `5`, then we might have only a single
// instruction to represent `5`.
//
auto irInitVal = getSimpleVal(subContext, lowerRValueExpr(subContext, initExpr));
// We construct a distinct IR instruction to represent the
// constant itself, with the value as an operand.
//
irConstant = builder->emitGlobalConstant(
irInitVal->getFullType(),
irInitVal);
}
// All of the attributes/decorations we can attach
// belong on the IR constant node.
//
addLinkageDecoration(context, irConstant, decl);
addNameHint(context, irConstant, decl);
addVarDecorations(context, irConstant, decl);
getBuilder()->addHighLevelDeclDecoration(irConstant, decl);
// Register the value that was emitted as the value
// for any references to the constant from elsewhere
// in the code.
//
auto constantVal = LoweredValInfo::simple(irConstant);
setGlobalValue(context, decl, constantVal);
return constantVal;
}
LoweredValInfo lowerGlobalConstantDecl(VarDecl* decl)
{
return lowerConstantDeclCommon(decl, context);
}
LoweredValInfo lowerGlobalVarDecl(VarDecl* decl)
{
// A non-`static` global is actually a shader parameter in HLSL.
//
// TODO: We should probably make that case distinct at the AST
// level as well, since global shader parameters are fairly
// different from global variables.
//
if(isGlobalShaderParameter(decl))
{
return lowerGlobalShaderParam(decl);
}
// A `static const` global is actually a compile-time constant.
//
if (decl->hasModifier<HLSLStaticModifier>() && decl->hasModifier<ConstModifier>())
{
return lowerGlobalConstantDecl(decl);
}
IRType* varType = lowerType(context, decl->getType());
auto builder = getBuilder();
IRGlobalValueWithCode* irGlobal = builder->createGlobalVar(varType);
LoweredValInfo globalVal = LoweredValInfo::ptr(irGlobal);
addLinkageDecoration(context, irGlobal, decl);
addNameHint(context, irGlobal, decl);
maybeSetRate(context, irGlobal, decl);
addVarDecorations(context, irGlobal, decl);
if (decl)
{
builder->addHighLevelDeclDecoration(irGlobal, decl);
}
// A global variable's SSA value is a *pointer* to
// the underlying storage.
setGlobalValue(context, decl, globalVal);
if (isImportedDecl(decl))
{
// Always emit imported declarations as declarations,
// and not definitions.
}
else if( auto initExpr = decl->initExpr )
{
IRBuilder subBuilderStorage = *getBuilder();
IRBuilder* subBuilder = &subBuilderStorage;
subBuilder->setInsertInto(irGlobal);
IRGenContext subContextStorage = *context;
IRGenContext* subContext = &subContextStorage;
subContext->irBuilder = subBuilder;
// TODO: set up a parent IR decl to put the instructions into
IRBlock* entryBlock = subBuilder->emitBlock();
subBuilder->setInsertInto(entryBlock);
LoweredValInfo initVal = lowerLValueExpr(subContext, initExpr);
subContext->irBuilder->emitReturn(getSimpleVal(subContext, initVal));
}
irGlobal->moveToEnd();
return globalVal;
}
bool isFunctionStaticVarDecl(VarDeclBase* decl)
{
// Only a variable marked `static` can be static.
if(!decl->findModifier<HLSLStaticModifier>())
return false;
// The immediate parent of a function-scope variable
// declaration will be a `ScopeDecl`.
//
// TODO: right now the parent links for scopes are *not*
// set correctly, so we can't just scan up and look
// for a function in the parent chain...
auto parent = decl->parentDecl;
if( as<ScopeDecl>(parent) )
{
return true;
}
return false;
}
IRInst* defaultSpecializeOuterGeneric(
IRInst* outerVal,
IRType* type,
GenericDecl* genericDecl)
{
auto builder = getBuilder();
// We need to specialize any generics that are further out...
auto specialiedOuterVal = defaultSpecializeOuterGenerics(
outerVal,
builder->getGenericKind(),
genericDecl);
List<IRInst*> genericArgs;
// Walk the parameters of the generic, and emit an argument for each,
// which will be a reference to binding for that parameter in the
// current scope.
//
// First we start with type and value parameters,
// in the order they were declared.
for (auto member : genericDecl->members)
{
if (auto typeParamDecl = as<GenericTypeParamDecl>(member))
{
genericArgs.add(getSimpleVal(context, ensureDecl(context, typeParamDecl)));
}
else if (auto valDecl = as<GenericValueParamDecl>(member))
{
genericArgs.add(getSimpleVal(context, ensureDecl(context, valDecl)));
}
}
// Then we emit constraint parameters, again in
// declaration order.
for (auto member : genericDecl->members)
{
if (auto constraintDecl = as<GenericTypeConstraintDecl>(member))
{
genericArgs.add(getSimpleVal(context, ensureDecl(context, constraintDecl)));
}
}
return builder->emitSpecializeInst(type, specialiedOuterVal, genericArgs.getCount(), genericArgs.getBuffer());
}
IRInst* defaultSpecializeOuterGenerics(
IRInst* val,
IRType* type,
Decl* decl)
{
if(!val) return nullptr;
auto parentVal = val->getParent();
while(parentVal)
{
if(as<IRGeneric>(parentVal))
break;
parentVal = parentVal->getParent();
}
if(!parentVal)
return val;
for(auto pp = decl->parentDecl; pp; pp = pp->parentDecl)
{
if(auto genericAncestor = as<GenericDecl>(pp))
{
return defaultSpecializeOuterGeneric(parentVal, type, genericAncestor);
}
}
return val;
}
struct NestedContext
{
IRGenEnv subEnvStorage;
IRBuilder subBuilderStorage;
IRGenContext subContextStorage;
NestedContext(DeclLoweringVisitor* outer)
: subBuilderStorage(*outer->getBuilder())
, subContextStorage(*outer->context)
{
auto outerContext = outer->context;
subEnvStorage.outer = outerContext->env;
subContextStorage.irBuilder = &subBuilderStorage;
subContextStorage.env = &subEnvStorage;
}
IRBuilder* getBuilder() { return &subBuilderStorage; }
IRGenContext* getContext() { return &subContextStorage; }
};
LoweredValInfo lowerFunctionStaticConstVarDecl(
VarDeclBase* decl)
{
// We need to insert the constant at a level above
// the function being emitted. This will usually
// be the global scope, but it might be an outer
// generic if we are lowering a generic function.
//
NestedContext nestedContext(this);
auto subBuilder = nestedContext.getBuilder();
auto subContext = nestedContext.getContext();
subBuilder->setInsertInto(subBuilder->getFunc()->getParent());
return lowerConstantDeclCommon(decl, subContext);
}
LoweredValInfo lowerFunctionStaticVarDecl(
VarDeclBase* decl)
{
// We know the variable is `static`, but it might also be `const.
if(decl->hasModifier<ConstModifier>())
return lowerFunctionStaticConstVarDecl(decl);
// A global variable may need to be generic, if one
// of the outer declarations is generic.
NestedContext nestedContext(this);
auto subBuilder = nestedContext.getBuilder();
auto subContext = nestedContext.getContext();
subBuilder->setInsertInto(subBuilder->getModule()->getModuleInst());
emitOuterGenerics(subContext, decl, decl);
IRType* subVarType = lowerType(subContext, decl->getType());
IRGlobalValueWithCode* irGlobal = subBuilder->createGlobalVar(subVarType);
addVarDecorations(subContext, irGlobal, decl);
addNameHint(context, irGlobal, decl);
maybeSetRate(context, irGlobal, decl);
subBuilder->addHighLevelDeclDecoration(irGlobal, decl);
// We are inside of a function, and that function might be generic,
// in which case the `static` variable will be lowered to another
// generic. Let's start with a terrible example:
//
// interface IHasCount { int getCount(); }
// int incrementCounter<T : IHasCount >(T val) {
// static int counter = 0;
// counter += val.getCount();
// return counter;
// }
//
// In this case, `incrementCounter` will lower to a function
// nested in a generic, while `counter` will be lowered to
// a global variable nested in a *different* generic.
// The net result is something like this:
//
// int counter<T:IHasCount> = 0;
//
// int incrementCounter<T:IHasCount>(T val) {
// counter<T> += val.getCount();
// return counter<T>;
//
// The references to `counter` inside of `incrementCounter`
// become references to `counter<T>`.
//
// At the IR level, this means that the value we install
// for `decl` needs to be a specialized reference to `irGlobal`,
// for any outer generics.
//
IRType* varType = lowerType(context, decl->getType());
IRType* varPtrType = getBuilder()->getPtrType(varType);
auto irSpecializedGlobal = defaultSpecializeOuterGenerics(irGlobal, varPtrType, decl);
LoweredValInfo globalVal = LoweredValInfo::ptr(irSpecializedGlobal);
setValue(context, decl, globalVal);
// A `static` variable with an initializer needs special handling,
// at least if the initializer isn't a compile-time constant.
if( auto initExpr = decl->initExpr )
{
// We must create an ordinary global `bool isInitialized = false`
// to represent whether we've initialized this before.
// Then emit code like:
//
// if(!isInitialized) { <globalVal> = <initExpr>; isInitialized = true; }
//
// TODO: we could conceivably optimize this by detecting
// when the `initExpr` lowers to just a reference to a constant,
// and then either deleting the extra code structure there,
// or not generating it in the first place. That is a bit
// more complexity than I'm ready for at the moment.
//
// Of course, if we are under a generic, then the Boolean
// variable need to be generic as well!
NestedContext nestedBoolContext(this);
auto boolBuilder = nestedBoolContext.getBuilder();
auto boolContext = nestedBoolContext.getContext();
boolBuilder->setInsertInto(boolBuilder->getModule()->getModuleInst());
emitOuterGenerics(boolContext, decl, decl);
auto irBoolType = boolBuilder->getBoolType();
auto irBool = boolBuilder->createGlobalVar(irBoolType);
boolBuilder->setInsertInto(irBool);
boolBuilder->setInsertInto(boolBuilder->createBlock());
boolBuilder->emitReturn(boolBuilder->getBoolValue(false));
auto boolVal = LoweredValInfo::ptr(defaultSpecializeOuterGenerics(irBool, irBoolType, decl));
// Okay, with our global Boolean created, we can move on to
// generating the code we actually care about, back in the original function.
auto builder = getBuilder();
auto initBlock = builder->createBlock();
auto afterBlock = builder->createBlock();
builder->emitIfElse(getSimpleVal(context, boolVal), afterBlock, initBlock, afterBlock);
builder->insertBlock(initBlock);
LoweredValInfo initVal = lowerLValueExpr(context, initExpr);
assign(context, globalVal, initVal);
assign(context, boolVal, LoweredValInfo::simple(builder->getBoolValue(true)));
builder->emitBranch(afterBlock);
builder->insertBlock(afterBlock);
}
irGlobal->moveToEnd();
finishOuterGenerics(subBuilder, irGlobal);
return globalVal;
}
LoweredValInfo visitGenericValueParamDecl(GenericValueParamDecl* decl)
{
return emitDeclRef(context, makeDeclRef(decl),
lowerType(context, decl->type));
}
LoweredValInfo visitVarDecl(VarDecl* decl)
{
// Detect global (or effectively global) variables
// and handle them differently.
if (isGlobalVarDecl(decl))
{
return lowerGlobalVarDecl(decl);
}
if(isFunctionStaticVarDecl(decl))
{
return lowerFunctionStaticVarDecl(decl);
}
if(isMemberVarDecl(decl))
{
return lowerMemberVarDecl(decl);
}
// A user-defined variable declaration will usually turn into
// an `alloca` operation for the variable's storage,
// plus some code to initialize it and then store to the variable.
IRType* varType = lowerType(context, decl->getType());
// As a special case, an immutable local variable with an
// initializer can just lower to the SSA value of its initializer.
//
if(as<LetDecl>(decl))
{
if(auto initExpr = decl->initExpr)
{
auto initVal = lowerRValueExpr(context, initExpr);
initVal = LoweredValInfo::simple(getSimpleVal(context, initVal));
setGlobalValue(context, decl, initVal);
return initVal;
}
}
LoweredValInfo varVal = createVar(context, varType, decl);
if( auto initExpr = decl->initExpr )
{
auto initVal = lowerRValueExpr(context, initExpr);
assign(context, varVal, initVal);
}
setGlobalValue(context, decl, varVal);
return varVal;
}
IRStructKey* getInterfaceRequirementKey(Decl* requirementDecl)
{
return Slang::getInterfaceRequirementKey(context, requirementDecl);
}
LoweredValInfo visitInterfaceDecl(InterfaceDecl* decl)
{
// The members of an interface will turn into the keys that will
// be used for lookup operations into witness
// tables that promise conformance to the interface.
//
// TODO: we don't handle the case here of an interface
// with concrete/default implementations for any
// of its members.
//
// TODO: If we want to support using an interface as
// an existential type, then we might need to emit
// a witness table for the interface type's conformance
// to its own interface.
//
for (auto requirementDecl : decl->members)
{
getInterfaceRequirementKey(requirementDecl);
// As a special case, any type constraints placed
// on an associated type will *also* need to be turned
// into requirement keys for this interface.
if (auto associatedTypeDecl = as<AssocTypeDecl>(requirementDecl))
{
for (auto constraintDecl : associatedTypeDecl->getMembersOfType<TypeConstraintDecl>())
{
getInterfaceRequirementKey(constraintDecl);
}
}
}
NestedContext nestedContext(this);
auto subBuilder = nestedContext.getBuilder();
auto subContext = nestedContext.getContext();
// Emit any generics that should wrap the actual type.
emitOuterGenerics(subContext, decl, decl);
IRInterfaceType* irInterface = subBuilder->createInterfaceType();
addNameHint(context, irInterface, decl);
addLinkageDecoration(context, irInterface, decl);
subBuilder->setInsertInto(irInterface);
// TODO: are there any interface members that should be
// nested inside the interface type itself?
irInterface->moveToEnd();
addTargetIntrinsicDecorations(irInterface, decl);
return LoweredValInfo::simple(finishOuterGenerics(subBuilder, irInterface));
}
LoweredValInfo visitEnumCaseDecl(EnumCaseDecl* decl)
{
// A case within an `enum` decl will lower to a value
// of the `enum`'s "tag" type.
//
// TODO: a bit more work will be needed if we allow for
// enum cases that have payloads, because then we need
// a function that constructs the value given arguments.
//
NestedContext nestedContext(this);
auto subContext = nestedContext.getContext();
// Emit any generics that should wrap the actual type.
emitOuterGenerics(subContext, decl, decl);
return lowerRValueExpr(subContext, decl->tagExpr);
}
LoweredValInfo visitEnumDecl(EnumDecl* decl)
{
// Given a declaration of a type, we need to make sure
// to output "witness tables" for any interfaces this
// type has declared conformance to.
for( auto inheritanceDecl : decl->getMembersOfType<InheritanceDecl>() )
{
ensureDecl(context, inheritanceDecl);
}
NestedContext nestedContext(this);
auto subBuilder = nestedContext.getBuilder();
auto subContext = nestedContext.getContext();
emitOuterGenerics(subContext, decl, decl);
// An `enum` declaration will currently lower directly to its "tag"
// type, so that any references to the `enum` become referenes to
// the tag type instead.
//
// TODO: if we ever support `enum` types with payloads, we would
// need to make the `enum` lower to some kind of custom "tagged union"
// type.
IRType* loweredTagType = lowerType(subContext, decl->tagType);
return LoweredValInfo::simple(finishOuterGenerics(subBuilder, loweredTagType));
}
LoweredValInfo visitAggTypeDecl(AggTypeDecl* decl)
{
// Don't generate an IR `struct` for intrinsic types
if(decl->findModifier<IntrinsicTypeModifier>() || decl->findModifier<BuiltinTypeModifier>())
{
return LoweredValInfo();
}
// Given a declaration of a type, we need to make sure
// to output "witness tables" for any interfaces this
// type has declared conformance to.
for( auto inheritanceDecl : decl->getMembersOfType<InheritanceDecl>() )
{
ensureDecl(context, inheritanceDecl);
}
// We are going to create nested IR building state
// to use when emitting the members of the type.
//
NestedContext nestedContext(this);
auto subBuilder = nestedContext.getBuilder();
auto subContext = nestedContext.getContext();
// Emit any generics that should wrap the actual type.
emitOuterGenerics(subContext, decl, decl);
IRStructType* irStruct = subBuilder->createStructType();
addNameHint(context, irStruct, decl);
addLinkageDecoration(context, irStruct, decl);
subBuilder->setInsertInto(irStruct);
for (auto fieldDecl : decl->getMembersOfType<VarDeclBase>())
{
if (fieldDecl->hasModifier<HLSLStaticModifier>())
{
// A `static` field is actually a global variable,
// and we should emit it as such.
ensureDecl(context, fieldDecl);
continue;
}
// Each ordinary field will need to turn into a struct "key"
// that is used for fetching the field.
IRInst* fieldKeyInst = getSimpleVal(context,
ensureDecl(context, fieldDecl));
auto fieldKey = as<IRStructKey>(fieldKeyInst);
SLANG_ASSERT(fieldKey);
// Note: we lower the type of the field in the "sub"
// context, so that any generic parameters that were
// set up for the type can be referenced by the field type.
IRType* fieldType = lowerType(
subContext,
fieldDecl->getType());
// Then, the parent `struct` instruction itself will have
// a "field" instruction.
subBuilder->createStructField(
irStruct,
fieldKey,
fieldType);
}
// There may be members not handled by the above logic (e.g.,
// member functions), but we will not immediately force them
// to be emitted here, so as not to risk a circular dependency.
//
// Instead we will force emission of all children of aggregate
// type declarations later, from the top-level emit logic.
irStruct->moveToEnd();
addTargetIntrinsicDecorations(irStruct, decl);
return LoweredValInfo::simple(finishOuterGenerics(subBuilder, irStruct));
}
LoweredValInfo lowerMemberVarDecl(VarDecl* fieldDecl)
{
// Each field declaration in the AST translates into
// a "key" that can be used to extract field values
// from instances of struct types that contain the field.
//
// It is correct to say struct *types* because a `struct`
// nested under a generic can be used to realize a number
// of different concrete types, but all of these types
// will use the same space of keys.
auto builder = getBuilder();
auto irFieldKey = builder->createStructKey();
addNameHint(context, irFieldKey, fieldDecl);
addVarDecorations(context, irFieldKey, fieldDecl);
addLinkageDecoration(context, irFieldKey, fieldDecl);
if (auto semanticModifier = fieldDecl->findModifier<HLSLSimpleSemantic>())
{
builder->addSemanticDecoration(irFieldKey, semanticModifier->name.getName()->text.getUnownedSlice());
}
// We allow a field to be marked as a target intrinsic,
// so that we can override its mangled name in the
// output for the chosen target.
addTargetIntrinsicDecorations(irFieldKey, fieldDecl);
return LoweredValInfo::simple(irFieldKey);
}
// When lowering something callable (most commonly a function declaration),
// we need to construct an appropriate parameter list for the IR function
// that folds in any contributions from both the declaration itself *and*
// its parent declaration(s).
//
// For example, given code like:
//
// struct Foo { int bar(float y) { ... } };
//
// we need to generate IR-level code something like:
//
// func Foo_bar(Foo this, float y) -> int;
//
// that is, the `this` parameter has become explicit.
//
// The same applies to generic parameters, and these
// should apply even if the nested declaration is `static`:
//
// struct Foo<T> { static int bar(T y) { ... } };
//
// becomes:
//
// func Foo_bar<T>(T y) -> int;
//
// In order to implement this, we are going to do a recursive
// walk over a declaration and its parents, collecting separate
// lists of ordinary and generic parameters that will need
// to be included in the final declaration's parameter list.
//
// When doing code generation for an ordinary value parameter,
// we mostly care about its type, and then also its "direction"
// (`in`, `out`, `in out`). We sometimes need acess to the
// original declaration so that we can inspect it for meta-data,
// but in some cases there is no such declaration (e.g., a `this`
// parameter doesn't get an explicit declaration in the AST).
// To handle this we break out the relevant data into derived
// structures:
//
struct ParameterInfo
{
// This AST-level type of the parameter
RefPtr<Type> type;
// The direction (`in` vs `out` vs `in out`)
ParameterDirection direction;
// The variable/parameter declaration for
// this parameter (if any)
VarDeclBase* decl;
// Is this the representation of a `this` parameter?
bool isThisParam = false;
};
//
// We need a way to be able to create a `ParameterInfo` given the declaration
// of a parameter:
//
ParameterInfo getParameterInfo(VarDeclBase* paramDecl)
{
ParameterInfo info;
info.type = paramDecl->getType();
info.decl = paramDecl;
info.direction = getParameterDirection(paramDecl);
info.isThisParam = false;
return info;
}
//
// Here's the declaration for the type to hold the lists:
struct ParameterLists
{
List<ParameterInfo> params;
};
//
// Because there might be a `static` declaration somewhere
// along the lines, we need to be careful to prohibit adding
// non-generic parameters in some cases.
enum ParameterListCollectMode
{
// Collect everything: ordinary and generic parameters.
kParameterListCollectMode_Default,
// Only collect generic parameters.
kParameterListCollectMode_Static,
};
//
// We also need to be able to detect whether a declaration is
// either explicitly or implicitly treated as `static`:
ParameterListCollectMode getModeForCollectingParentParameters(
Decl* decl,
ContainerDecl* parentDecl)
{
// If we have a `static` parameter, then it is obvious
// that we should use the `static` mode
if(isEffectivelyStatic(decl, parentDecl))
return kParameterListCollectMode_Static;
// Otherwise, let's default to collecting everything
return kParameterListCollectMode_Default;
}
//
// When dealing with a member function, we need to be able to add the `this`
// parameter for the enclosing type:
//
void addThisParameter(
ParameterDirection direction,
Type* type,
ParameterLists* ioParameterLists)
{
ParameterInfo info;
info.type = type;
info.decl = nullptr;
info.direction = direction;
info.isThisParam = true;
ioParameterLists->params.add(info);
}
//
// And here is our function that will do the recursive walk:
void collectParameterLists(
Decl* decl,
ParameterLists* ioParameterLists,
ParameterListCollectMode mode)
{
// The parameters introduced by any "parent" declarations
// will need to come first, so we'll deal with that
// logic here.
if( auto parentDecl = decl->parentDecl )
{
// Compute the mode to use when collecting parameters from
// the outer declaration. The most important question here
// is whether parameters of the outer declaration should
// also count as parameters of the inner declaration.
ParameterListCollectMode innerMode = getModeForCollectingParentParameters(decl, parentDecl);
// Don't down-grade our `static`-ness along the chain.
if(innerMode < mode)
innerMode = mode;
// Now collect any parameters from the parent declaration itself
collectParameterLists(parentDecl, ioParameterLists, innerMode);
// We also need to consider whether the inner declaration needs to have a `this`
// parameter corresponding to the outer declaration.
if( innerMode != kParameterListCollectMode_Static )
{
ParameterDirection direction = getThisParamDirection(decl);
auto thisType = getThisParamTypeForContainer(context, createDefaultSpecializedDeclRef(context, parentDecl));
if(thisType)
{
addThisParameter(direction, thisType, ioParameterLists);
}
}
}
// Once we've added any parameters based on parent declarations,
// we can see if this declaration itself introduces parameters.
//
if( auto callableDecl = as<CallableDecl>(decl) )
{
// Don't collect parameters from the outer scope if
// we are in a `static` context.
if( mode == kParameterListCollectMode_Default )
{
for( auto paramDecl : callableDecl->getParameters() )
{
ioParameterLists->params.add(getParameterInfo(paramDecl));
}
}
}
}
bool isImportedDecl(Decl* decl)
{
return Slang::isImportedDecl(context, decl);
}
bool isConstExprVar(Decl* decl)
{
if( decl->hasModifier<ConstExprModifier>() )
{
return true;
}
else if(decl->hasModifier<HLSLStaticModifier>() && decl->hasModifier<ConstModifier>())
{
return true;
}
return false;
}
IRType* maybeGetConstExprType(IRType* type, Decl* decl)
{
if(isConstExprVar(decl))
{
return getBuilder()->getRateQualifiedType(
getBuilder()->getConstExprRate(),
type);
}
return type;
}
IRGeneric* emitOuterGeneric(
IRGenContext* subContext,
GenericDecl* genericDecl,
Decl* leafDecl)
{
auto subBuilder = subContext->irBuilder;
// Of course, a generic might itself be nested inside of other generics...
emitOuterGenerics(subContext, genericDecl, leafDecl);
// We need to create an IR generic
auto irGeneric = subBuilder->emitGeneric();
subBuilder->setInsertInto(irGeneric);
auto irBlock = subBuilder->emitBlock();
subBuilder->setInsertInto(irBlock);
// Now emit any parameters of the generic
//
// First we start with type and value parameters,
// in the order they were declared.
for (auto member : genericDecl->members)
{
if (auto typeParamDecl = as<GenericTypeParamDecl>(member))
{
// TODO: use a `TypeKind` to represent the
// classifier of the parameter.
auto param = subBuilder->emitParam(nullptr);
addNameHint(context, param, typeParamDecl);
setValue(subContext, typeParamDecl, LoweredValInfo::simple(param));
}
else if (auto valDecl = as<GenericValueParamDecl>(member))
{
auto paramType = lowerType(subContext, valDecl->getType());
auto param = subBuilder->emitParam(paramType);
addNameHint(context, param, valDecl);
setValue(subContext, valDecl, LoweredValInfo::simple(param));
}
}
// Then we emit constraint parameters, again in
// declaration order.
for (auto member : genericDecl->members)
{
if (auto constraintDecl = as<GenericTypeConstraintDecl>(member))
{
// TODO: use a `WitnessTableKind` to represent the
// classifier of the parameter.
auto param = subBuilder->emitParam(nullptr);
addNameHint(context, param, constraintDecl);
setValue(subContext, constraintDecl, LoweredValInfo::simple(param));
}
}
return irGeneric;
}
// If the given `decl` is enclosed in any generic declarations, then
// emit IR-level generics to represent them.
// The `leafDecl` represents the inner-most declaration we are actually
// trying to emit, which is the one that should receive the mangled name.
//
IRGeneric* emitOuterGenerics(IRGenContext* subContext, Decl* decl, Decl* leafDecl)
{
for(auto pp = decl->parentDecl; pp; pp = pp->parentDecl)
{
if(auto genericAncestor = as<GenericDecl>(pp))
{
return emitOuterGeneric(subContext, genericAncestor, leafDecl);
}
}
return nullptr;
}
// If any generic declarations have been created by `emitOuterGenerics`,
// then finish them off by emitting `return` instructions for the
// values that they should produce.
//
// Return the outer-most generic (if there is one), or the original
// value (if there were no generics), which should be the IR-level
// representation of the original declaration.
//
IRInst* finishOuterGenerics(
IRBuilder* subBuilder,
IRInst* val)
{
IRInst* v = val;
for(;;)
{
auto parentBlock = as<IRBlock>(v->getParent());
if (!parentBlock) break;
auto parentGeneric = as<IRGeneric>(parentBlock->getParent());
if (!parentGeneric) break;
subBuilder->setInsertInto(parentBlock);
subBuilder->emitReturn(v);
parentGeneric->moveToEnd();
// There might be more outer generics,
// so we need to loop until we run out.
v = parentGeneric;
}
return v;
}
// Attach target-intrinsic decorations to an instruction,
// based on modifiers on an AST declaration.
void addTargetIntrinsicDecorations(
IRInst* irInst,
Decl* decl)
{
auto builder = getBuilder();
for (auto targetMod : decl->getModifiersOfType<TargetIntrinsicModifier>())
{
String definition;
auto definitionToken = targetMod->definitionToken;
if (definitionToken.type == TokenType::StringLiteral)
{
definition = getStringLiteralTokenValue(definitionToken);
}
else if(definitionToken.type == TokenType::Identifier)
{
definition = definitionToken.getContent();
}
else
{
definition = decl->getName()->text;
}
UnownedStringSlice targetName;
auto& targetToken = targetMod->targetToken;
if( targetToken.type != TokenType::Unknown )
{
targetName = targetToken.getContent();
}
builder->addTargetIntrinsicDecoration(irInst, targetName, definition.getUnownedSlice());
}
}
/// Is `decl` a member function (or effectively a member function) when considered as a stdlib declaration?
bool isStdLibMemberFuncDecl(
CallableDecl* decl)
{
// Constructors aren't really member functions, insofar
// as they aren't called with a `this` parameter.
//
// TODO: We may also want to exclude `static` functions
// here for the same reason, but this routine is only
// used for the stdlib, where we don't currently have
// any `static` member functions to worry about.
//
if(as<ConstructorDecl>(decl))
return false;
auto dd = decl->parentDecl;
for(;;)
{
if(auto genericDecl = as<GenericDecl>(dd))
{
dd = genericDecl->parentDecl;
continue;
}
if( auto subscriptDecl = as<SubscriptDecl>(dd) )
{
dd = subscriptDecl->parentDecl;
}
break;
}
// Note: the use of `AggTypeDeclBase` here instead of just
// `AggTypeDecl` means that we consider a declaration that
// is under a `struct` *or* an `extension` to be a member
// function for our purposes.
//
if(as<AggTypeDeclBase>(dd))
return true;
return false;
}
/// Add a "catch-all" decoration for a stdlib function if it would be needed
void addCatchAllIntrinsicDecorationIfNeeded(
IRInst* irInst,
FunctionDeclBase* decl)
{
// We don't need an intrinsic decoration on a function that has a body,
// since the body can be used as the "catch-all" case.
//
if(decl->body)
return;
// Only standard library declarations should get any kind of catch-all
// treatment by default. Declarations in user case are responsible
// for marking things as target intrinsics if they want to go down
// that (unsupported) route.
//
if(!isFromStdLib(decl))
return;
// No need to worry about functions that lower to intrinsic IR opcodes
// (or pseudo-ops).
//
if(decl->findModifier<IntrinsicOpModifier>())
return;
// We also don't need an intrinsic decoration if the function already
// had a catch-all case on one of its target overloads.
//
for( auto f = decl->primaryDecl; f; f = f->nextDecl )
{
for(auto targetMod : f->getModifiersOfType<TargetIntrinsicModifier>())
{
// If we find a catch-all case (marked as either *no* target
// token or an empty target name), then we should bail out.
//
if(targetMod->targetToken.type == TokenType::Unknown)
return;
else if(!targetMod->targetToken.hasContent())
return;
}
}
String definition;
// If we have a member function, then we want the default intrinsic
// definition to reflect this fact so that we can emit it correctly
// (the assumption is that a catch-all definition of a member function
// is itself implemented as a member function).
//
if( isStdLibMemberFuncDecl(decl) )
{
// We will mark member functions by appending a `.` to the
// start of their name.
//
definition.append(".");
}
// We want to output the name of the declaration,
// but in some cases the actual `decl` that has
// to be emitted is not the one with the name.
//
// In particular, an accessor declaration (e.g.,
// a `get`ter` in a subscript or property) doesn't
// have a name, but its parent should.
//
Decl* declForName = decl;
if(auto accessorDecl = as<AccessorDecl>(decl))
declForName = decl->parentDecl;
definition.append(getText(declForName->getName()));
getBuilder()->addTargetIntrinsicDecoration(irInst, UnownedStringSlice(), definition.getUnownedSlice());
}
void addParamNameHint(IRInst* inst, ParameterInfo info)
{
if(auto decl = info.decl)
{
addNameHint(context, inst, decl);
}
else if( info.isThisParam )
{
addNameHint(context, inst, "this");
}
}
IRIntLit* _getIntLitFromAttribute(IRBuilder* builder, Attribute* attrib)
{
attrib->args.getCount();
SLANG_ASSERT(attrib->args.getCount() ==1);
Expr* expr = attrib->args[0];
auto intLitExpr = as<IntegerLiteralExpr>(expr);
SLANG_ASSERT(intLitExpr);
return as<IRIntLit>(builder->getIntValue(builder->getIntType(), intLitExpr->value));
}
IRStringLit* _getStringLitFromAttribute(IRBuilder* builder, Attribute* attrib)
{
attrib->args.getCount();
SLANG_ASSERT(attrib->args.getCount() == 1);
Expr* expr = attrib->args[0];
auto stringLitExpr = as<StringLiteralExpr>(expr);
SLANG_ASSERT(stringLitExpr);
return as<IRStringLit>(builder->getStringValue(stringLitExpr->value.getUnownedSlice()));
}
LoweredValInfo lowerFuncDecl(FunctionDeclBase* decl)
{
// We are going to use a nested builder, because we will
// change the parent node that things get nested into.
//
NestedContext nestedContext(this);
auto subBuilder = nestedContext.getBuilder();
auto subContext = nestedContext.getContext();
// The actual `IRFunction` that we emit needs to be nested
// inside of one `IRGeneric` for every outer `GenericDecl`
// in the declaration hierarchy.
emitOuterGenerics(subContext, decl, decl);
// Collect the parameter lists we will use for our new function.
ParameterLists parameterLists;
collectParameterLists(decl, ¶meterLists, kParameterListCollectMode_Default);
// TODO: if there are any generic parameters in the collected list, then
// we need to output an IR function with generic parameters (or a generic
// with a nested function... the exact representation is still TBD).
// In most cases the return type for a declaration can be read off the declaration
// itself, but things get a bit more complicated when we have to deal with
// accessors for subscript declarations (and eventually for properties).
//
// We compute a declaration to use for looking up the return type here:
CallableDecl* declForReturnType = decl;
if (auto accessorDecl = as<AccessorDecl>(decl))
{
// We are some kind of accessor, so the parent declaration should
// know the correct return type to expose.
//
auto parentDecl = accessorDecl->parentDecl;
if (auto subscriptDecl = as<SubscriptDecl>(parentDecl))
{
declForReturnType = subscriptDecl;
}
}
// need to create an IR function here
IRFunc* irFunc = subBuilder->createFunc();
addNameHint(context, irFunc, decl);
addLinkageDecoration(context, irFunc, decl);
List<IRType*> paramTypes;
for( auto paramInfo : parameterLists.params )
{
IRType* irParamType = lowerType(subContext, paramInfo.type);
switch( paramInfo.direction )
{
case kParameterDirection_In:
// Simple case of a by-value input parameter.
break;
// If the parameter is declared `out` or `inout`,
// then we will represent it with a pointer type in
// the IR, but we will use a specialized pointer
// type that encodes the parameter direction information.
case kParameterDirection_Out:
irParamType = subBuilder->getOutType(irParamType);
break;
case kParameterDirection_InOut:
irParamType = subBuilder->getInOutType(irParamType);
break;
case kParameterDirection_Ref:
irParamType = subBuilder->getRefType(irParamType);
break;
default:
SLANG_UNEXPECTED("unknown parameter direction");
break;
}
// If the parameter was explicitly marked as being a compile-time
// constant (`constexpr`), then attach that information to its
// IR-level type explicitly.
if( paramInfo.decl )
{
irParamType = maybeGetConstExprType(irParamType, paramInfo.decl);
}
paramTypes.add(irParamType);
}
auto irResultType = lowerType(subContext, declForReturnType->returnType);
if (auto setterDecl = as<SetterDecl>(decl))
{
// We are lowering a "setter" accessor inside a subscript
// declaration, which means we don't want to *return* the
// stated return type of the subscript, but instead take
// it as a parameter.
//
IRType* irParamType = irResultType;
paramTypes.add(irParamType);
// Instead, a setter always returns `void`
//
irResultType = subBuilder->getVoidType();
}
if( auto refAccessorDecl = as<RefAccessorDecl>(decl) )
{
// A `ref` accessor needs to return a *pointer* to the value
// being accessed, rather than a simple value.
irResultType = subBuilder->getPtrType(irResultType);
}
auto irFuncType = subBuilder->getFuncType(
paramTypes.getCount(),
paramTypes.getBuffer(),
irResultType);
irFunc->setFullType(irFuncType);
subBuilder->setInsertInto(irFunc);
// If a function is imported from another module then
// we usually don't want to emit it as a definition, and
// will instead only emit a declaration for it with an
// appropriate `[import(...)]` linkage decoration.
//
// However, if the function is marked with `[__unsafeForceInlineEarly]`
// then we need to make sure the IR for its definition is available
// to the mandatory optimization passes.
//
// TODO: The design here means that we will re-emit the inline
// function from its AST in every module that uses it. We should
// instead have logic to clone the target function in from the
// pre-generated IR for the module that defines it (or do some kind
// of minimal linking to bring in the inline functions).
//
if (isImportedDecl(decl) && !isForceInlineEarly(decl))
{
// Always emit imported declarations as declarations,
// and not definitions.
}
else if (!decl->body)
{
// This is a function declaration without a body.
// In Slang we currently try not to support forward declarations
// (although we might have to give in eventually), so
// this case should really only occur for builtin declarations.
}
else
{
// This is a function definition, so we need to actually
// construct IR for the body...
IRBlock* entryBlock = subBuilder->emitBlock();
subBuilder->setInsertInto(entryBlock);
UInt paramTypeIndex = 0;
for( auto paramInfo : parameterLists.params )
{
auto irParamType = paramTypes[paramTypeIndex++];
LoweredValInfo paramVal;
switch( paramInfo.direction )
{
default:
{
// The parameter is being used for input/output purposes,
// so it will lower to an actual parameter with a pointer type.
//
// TODO: Is this the best representation we can use?
IRParam* irParamPtr = subBuilder->emitParam(irParamType);
if(auto paramDecl = paramInfo.decl)
{
addVarDecorations(context, irParamPtr, paramDecl);
subBuilder->addHighLevelDeclDecoration(irParamPtr, paramDecl);
}
addParamNameHint(irParamPtr, paramInfo);
paramVal = LoweredValInfo::ptr(irParamPtr);
// TODO: We might want to copy the pointed-to value into
// a temporary at the start of the function, and then copy
// back out at the end, so that we don't have to worry
// about things like aliasing in the function body.
//
// For now we will just use the storage that was passed
// in by the caller, knowing that our current lowering
// at call sites will guarantee a fresh/unique location.
}
break;
case kParameterDirection_In:
{
// Simple case of a by-value input parameter.
//
// We start by declaring an IR parameter of the same type.
//
auto paramDecl = paramInfo.decl;
IRParam* irParam = subBuilder->emitParam(irParamType);
if( paramDecl )
{
addVarDecorations(context, irParam, paramDecl);
subBuilder->addHighLevelDeclDecoration(irParam, paramDecl);
}
addParamNameHint(irParam, paramInfo);
paramVal = LoweredValInfo::simple(irParam);
//
// HLSL allows a function parameter to be used as a local
// variable in the function body (just like C/C++), so
// we need to support that case as well.
//
// However, if we notice that the parameter was marked
// `const`, then we can skip this step.
//
// TODO: we should consider having all parameter be implicitly
// immutable except in a specific "compatibility mode."
//
if(paramDecl && paramDecl->findModifier<ConstModifier>())
{
// This parameter was declared to be immutable,
// so there should be no assignment to it in the
// function body, and we don't need a temporary.
}
else
{
// The parameter migth get used as a temporary in
// the function body. We will allocate a mutable
// local variable for is value, and then assign
// from the parameter to the local at the start
// of the function.
//
auto irLocal = subBuilder->emitVar(irParamType);
auto localVal = LoweredValInfo::ptr(irLocal);
assign(subContext, localVal, paramVal);
//
// When code later in the body of the function refers
// to the parameter declaration, it will actually refer
// to the value stored in the local variable.
//
paramVal = localVal;
}
}
break;
}
if( auto paramDecl = paramInfo.decl )
{
setValue(subContext, paramDecl, paramVal);
}
if (paramInfo.isThisParam)
{
subContext->thisVal = paramVal;
}
}
if (auto setterDecl = as<SetterDecl>(decl))
{
// Add the IR parameter for the new value
IRType* irParamType = irResultType;
auto irParam = subBuilder->emitParam(irParamType);
addNameHint(context, irParam, "newValue");
// TODO: we need some way to wire this up to the `newValue`
// or whatever name we give for that parameter inside
// the setter body.
}
{
auto attr = decl->findModifier<PatchConstantFuncAttribute>();
// I needed to test for patchConstantFuncDecl here
// because it is only set if validateEntryPoint is called with Hull as the required stage
// If I just build domain shader, and then the attribute exists, but patchConstantFuncDecl is not set
// and thus leads to a crash.
if (attr && attr->patchConstantFuncDecl)
{
// We need to lower the function
FuncDecl* patchConstantFunc = attr->patchConstantFuncDecl;
assert(patchConstantFunc);
// Convert the patch constant function into IRInst
IRInst* irPatchConstantFunc = getSimpleVal(context, ensureDecl(subContext, patchConstantFunc));
// Attach a decoration so that our IR function references
// the patch constant function.
//
subContext->irBuilder->addPatchConstantFuncDecoration(
irFunc,
irPatchConstantFunc);
}
}
// We will now set about emitting the code for the body of
// the function/callable.
//
// In the case of an initializer ("constructor") declaration,
// the `this` value is not a parameter, but rather a placeholder
// for the value that will be returned. We thus need to set up
// a local variable to represent this value.
//
auto constructorDecl = as<ConstructorDecl>(decl);
if(constructorDecl)
{
auto thisVar = subContext->irBuilder->emitVar(irResultType);
subContext->thisVal = LoweredValInfo::ptr(thisVar);
}
// We lower whatever statement was stored on the declaration
// as the body of the new IR function.
//
lowerStmt(subContext, decl->body);
// We need to carefully add a terminator instruction to the end
// of the body, in case the user didn't do so.
//
if (!subContext->irBuilder->getBlock()->getTerminator())
{
if(constructorDecl)
{
// A constructor declaration should return the
// value of the `this` variable that was set
// up at the start.
//
// TODO: This should also apply if any code
// path in an initializer/constructor attempts
// to do an early `return;`.
//
subContext->irBuilder->emitReturn(
getSimpleVal(subContext, subContext->thisVal));
}
else if(as<IRVoidType>(irResultType))
{
// `void`-returning function can get an implicit
// return on exit of the body statement.
subContext->irBuilder->emitReturn();
}
else
{
// Value-returning function is expected to `return`
// on every control-flow path. We need to enforce
// this by putting an `unreachable` terminator here,
// and then emit a dataflow error if this block
// can't be eliminated.
subContext->irBuilder->emitMissingReturn();
}
}
}
getBuilder()->addHighLevelDeclDecoration(irFunc, decl);
// If this declaration was marked as being an intrinsic for a particular
// target, then we should reflect that here.
for( auto targetMod : decl->getModifiersOfType<SpecializedForTargetModifier>() )
{
// `targetMod` indicates that this particular declaration represents
// a specialized definition of the particular function for the given
// target, and we need to reflect that at the IR level.
getBuilder()->addTargetDecoration(irFunc, targetMod->targetToken.getContent());
}
// If this declaration was marked as having a target-specific lowering
// for a particular target, then handle that here.
addTargetIntrinsicDecorations(irFunc, decl);
addCatchAllIntrinsicDecorationIfNeeded(irFunc, decl);
// If this declaration requires certain GLSL extension (or a particular GLSL version)
// for it to be usable, then declare that here.
//
// TODO: We should wrap this an `SpecializedForTargetModifier` together into a single
// case for enumerating the "capabilities" that a declaration requires.
//
for(auto extensionMod : decl->getModifiersOfType<RequiredGLSLExtensionModifier>())
{
getBuilder()->addRequireGLSLExtensionDecoration(irFunc, extensionMod->extensionNameToken.getContent());
}
for(auto versionMod : decl->getModifiersOfType<RequiredGLSLVersionModifier>())
{
getBuilder()->addRequireGLSLVersionDecoration(irFunc, Int(getIntegerLiteralValue(versionMod->versionNumberToken)));
}
for (auto versionMod : decl->getModifiersOfType<RequiredSPIRVVersionModifier>())
{
getBuilder()->addRequireSPIRVVersionDecoration(irFunc, versionMod->version);
}
for (auto versionMod : decl->getModifiersOfType<RequiredCUDASMVersionModifier>())
{
getBuilder()->addRequireCUDASMVersionDecoration(irFunc, versionMod->version);
}
if (auto attr = decl->findModifier<InstanceAttribute>())
{
IRIntLit* intLit = _getIntLitFromAttribute(getBuilder(), attr);
getBuilder()->addDecoration(irFunc, kIROp_InstanceDecoration, intLit);
}
if(auto attr = decl->findModifier<MaxVertexCountAttribute>())
{
IRIntLit* intLit = _getIntLitFromAttribute(getBuilder(), attr);
getBuilder()->addDecoration(irFunc, kIROp_MaxVertexCountDecoration, intLit);
}
if(auto attr = decl->findModifier<NumThreadsAttribute>())
{
auto builder = getBuilder();
IRType* intType = builder->getIntType();
IRInst* operands[3] = {
builder->getIntValue(intType, attr->x),
builder->getIntValue(intType, attr->y),
builder->getIntValue(intType, attr->z)
};
builder->addDecoration(irFunc, kIROp_NumThreadsDecoration, operands, 3);
}
if(decl->findModifier<ReadNoneAttribute>())
{
getBuilder()->addSimpleDecoration<IRReadNoneDecoration>(irFunc);
}
if (decl->findModifier<EarlyDepthStencilAttribute>())
{
getBuilder()->addSimpleDecoration<IREarlyDepthStencilDecoration>(irFunc);
}
if (auto attr = decl->findModifier<DomainAttribute>())
{
IRStringLit* stringLit = _getStringLitFromAttribute(getBuilder(), attr);
getBuilder()->addDecoration(irFunc, kIROp_DomainDecoration, stringLit);
}
if (auto attr = decl->findModifier<PartitioningAttribute>())
{
IRStringLit* stringLit = _getStringLitFromAttribute(getBuilder(), attr);
getBuilder()->addDecoration(irFunc, kIROp_PartitioningDecoration, stringLit);
}
if (auto attr = decl->findModifier<OutputTopologyAttribute>())
{
IRStringLit* stringLit = _getStringLitFromAttribute(getBuilder(), attr);
getBuilder()->addDecoration(irFunc, kIROp_OutputTopologyDecoration, stringLit);
}
if (auto attr = decl->findModifier<OutputControlPointsAttribute>())
{
IRIntLit* intLit = _getIntLitFromAttribute(getBuilder(), attr);
getBuilder()->addDecoration(irFunc, kIROp_OutputControlPointsDecoration, intLit);
}
if(decl->findModifier<UnsafeForceInlineEarlyAttribute>())
{
getBuilder()->addDecoration(irFunc, kIROp_UnsafeForceInlineEarlyDecoration);
}
// For convenience, ensure that any additional global
// values that were emitted while outputting the function
// body appear before the function itself in the list
// of global values.
irFunc->moveToEnd();
return LoweredValInfo::simple(finishOuterGenerics(subBuilder, irFunc));
}
LoweredValInfo visitGenericDecl(GenericDecl * genDecl)
{
// TODO: Should this just always visit/lower the inner decl?
if (auto innerFuncDecl = as<FunctionDeclBase>(genDecl->inner))
return ensureDecl(context, innerFuncDecl);
else if (auto innerStructDecl = as<StructDecl>(genDecl->inner))
{
ensureDecl(context, innerStructDecl);
return LoweredValInfo();
}
else if( auto extensionDecl = as<ExtensionDecl>(genDecl->inner) )
{
return ensureDecl(context, extensionDecl);
}
SLANG_RELEASE_ASSERT(false);
UNREACHABLE_RETURN(LoweredValInfo());
}
LoweredValInfo visitFunctionDeclBase(FunctionDeclBase* decl)
{
// A function declaration may have multiple, target-specific
// overloads, and we need to emit an IR version of each of these.
// The front end will form a linked list of declarations with
// the same signature, whenever there is any kind of redeclaration.
// We will look to see if that linked list has been formed.
auto primaryDecl = decl->primaryDecl;
if (!primaryDecl)
{
// If there is no linked list then we are in the ordinary
// case with a single declaration, and no special handling
// is needed.
return lowerFuncDecl(decl);
}
// Otherwise, we need to walk the linked list of declarations
// and make sure to emit IR code for any targets that need it.
// TODO: Need to be careful about how this is approached,
// to avoid emitting a bunch of extra definitions in the IR.
auto primaryFuncDecl = as<FunctionDeclBase>(primaryDecl);
SLANG_ASSERT(primaryFuncDecl);
LoweredValInfo result = lowerFuncDecl(primaryFuncDecl);
for (auto dd = primaryDecl->nextDecl; dd; dd = dd->nextDecl)
{
auto funcDecl = as<FunctionDeclBase>(dd);
SLANG_ASSERT(funcDecl);
lowerFuncDecl(funcDecl);
}
return result;
}
};
LoweredValInfo lowerDecl(
IRGenContext* context,
DeclBase* decl)
{
IRBuilderSourceLocRAII sourceLocInfo(context->irBuilder, decl->loc);
DeclLoweringVisitor visitor;
visitor.context = context;
try
{
return visitor.dispatch(decl);
}
// Don't emit any context message for an explicit `AbortCompilationException`
// because it should only happen when an error is already emitted.
catch(const AbortCompilationException&) { throw; }
catch(...)
{
context->getSink()->noteInternalErrorLoc(decl->loc);
throw;
}
}
// Ensure that a version of the given declaration has been emitted to the IR
LoweredValInfo ensureDecl(
IRGenContext* context,
Decl* decl)
{
auto shared = context->shared;
LoweredValInfo result;
// Look for an existing value installed in this context
auto env = context->env;
while(env)
{
if(env->mapDeclToValue.TryGetValue(decl, result))
return result;
env = env->outer;
}
IRBuilder subIRBuilder;
subIRBuilder.sharedBuilder = context->irBuilder->sharedBuilder;
subIRBuilder.setInsertInto(subIRBuilder.sharedBuilder->module->getModuleInst());
IRGenEnv subEnv;
subEnv.outer = context->env;
IRGenContext subContext = *context;
subContext.irBuilder = &subIRBuilder;
subContext.env = &subEnv;
result = lowerDecl(&subContext, decl);
// By default assume that any value we are lowering represents
// something that should be installed globally.
setGlobalValue(shared, decl, result);
return result;
}
IRInst* lowerSubstitutionArg(
IRGenContext* context,
Val* val)
{
if (auto type = dynamicCast<Type>(val))
{
return lowerType(context, type);
}
else if (auto declaredSubtypeWitness = as<DeclaredSubtypeWitness>(val))
{
// We need to look up the IR-level representation of the witness (which will be a witness table).
auto irWitnessTable = getSimpleVal(
context,
emitDeclRef(
context,
declaredSubtypeWitness->declRef,
context->irBuilder->getWitnessTableType()));
return irWitnessTable;
}
else
{
SLANG_UNIMPLEMENTED_X("value cases");
UNREACHABLE_RETURN(nullptr);
}
}
// Can the IR lowered version of this declaration ever be an `IRGeneric`?
bool canDeclLowerToAGeneric(RefPtr<Decl> decl)
{
// A callable decl lowers to an `IRFunc`, and can be generic
if(as<CallableDecl>(decl)) return true;
// An aggregate type decl lowers to an `IRStruct`, and can be generic
if(as<AggTypeDecl>(decl)) return true;
// An inheritance decl lowers to an `IRWitnessTable`, and can be generic
if(as<InheritanceDecl>(decl)) return true;
// A `typedef` declaration nested under a generic will turn into
// a generic that returns a type (a simple type-level function).
if(as<TypeDefDecl>(decl)) return true;
return false;
}
LoweredValInfo emitDeclRef(
IRGenContext* context,
RefPtr<Decl> decl,
RefPtr<Substitutions> subst,
IRType* type)
{
// We need to proceed by considering the specializations that
// have been put in place.
// Ignore any global generic type substitutions during lowering.
// Really, we don't even expect these to appear.
while(auto globalGenericSubst = as<GlobalGenericParamSubstitution>(subst))
subst = globalGenericSubst->outer;
// If the declaration would not get wrapped in a `IRGeneric`,
// even if it is nested inside of an AST `GenericDecl`, then
// we should also ignore any generic substitutions.
if(!canDeclLowerToAGeneric(decl))
{
while(auto genericSubst = as<GenericSubstitution>(subst))
subst = genericSubst->outer;
}
// In the simplest case, there is no specialization going
// on, and the decl-ref turns into a reference to the
// lowered IR value for the declaration.
if(!subst)
{
LoweredValInfo loweredDecl = ensureDecl(context, decl);
return loweredDecl;
}
// Otherwise, we look at the kind of substitution, and let it guide us.
if(auto genericSubst = subst.as<GenericSubstitution>())
{
// A generic substitution means we will need to output
// a `specialize` instruction to specialize the generic.
//
// First we want to emit the value without generic specialization
// applied, to get a correct value for it.
//
// Note: we only "unwrap" a single layer from the
// substitutions here, because the underlying declaration
// might be nested in multiple generics, or it might
// come from an interface.
//
LoweredValInfo genericVal = emitDeclRef(
context,
decl,
genericSubst->outer,
context->irBuilder->getGenericKind());
// There's no reason to specialize something that maps to a NULL pointer.
if (genericVal.flavor == LoweredValInfo::Flavor::None)
return LoweredValInfo();
// We can only really specialize things that map to single values.
// It would be an error if we got a non-`None` value that
// wasn't somehow a single value.
auto irGenericVal = getSimpleVal(context, genericVal);
// We have the IR value for the generic we'd like to specialize,
// and now we need to get the value for the arguments.
List<IRInst*> irArgs;
for (auto argVal : genericSubst->args)
{
auto irArgVal = lowerSimpleVal(context, argVal);
SLANG_ASSERT(irArgVal);
irArgs.add(irArgVal);
}
// Once we have both the generic and its arguments,
// we can emit a `specialize` instruction and use
// its value as the result.
auto irSpecializedVal = context->irBuilder->emitSpecializeInst(
type,
irGenericVal,
irArgs.getCount(),
irArgs.getBuffer());
return LoweredValInfo::simple(irSpecializedVal);
}
else if(auto thisTypeSubst = subst.as<ThisTypeSubstitution>())
{
if(decl.Ptr() == thisTypeSubst->interfaceDecl)
{
// This is a reference to the interface type itself,
// through the this-type substitution, so it is really
// a reference to the this-type.
return lowerType(context, thisTypeSubst->witness->sub);
}
// Somebody is trying to look up an interface requirement
// "through" some concrete type. We need to lower this decl-ref
// as a lookup of the corresponding member in a witness table.
//
// The witness table itself is referenced by the this-type
// substitution, so we can just lower that.
//
// Note: unlike the case for generics above, in the interface-lookup
// case, we don't end up caring about any further outer substitutions.
// That is because even if we are naming `ISomething<Foo>.doIt()`,
// a method inside a generic interface, we don't actually care
// about the substitution of `Foo` for the parameter `T` of
// `ISomething<T>`. That is because we really care about the
// witness table for the concrete type that conforms to `ISomething<Foo>`.
//
auto irWitnessTable = lowerSimpleVal(context, thisTypeSubst->witness);
//
// The key to use for looking up the interface member is
// derived from the declaration.
//
auto irRequirementKey = getInterfaceRequirementKey(context, decl);
//
// Those two pieces of information tell us what we need to
// do in order to look up the value that satisfied the requirement.
//
auto irSatisfyingVal = context->irBuilder->emitLookupInterfaceMethodInst(
type,
irWitnessTable,
irRequirementKey);
return LoweredValInfo::simple(irSatisfyingVal);
}
else
{
SLANG_UNEXPECTED("uhandled substitution type");
UNREACHABLE_RETURN(LoweredValInfo());
}
}
LoweredValInfo emitDeclRef(
IRGenContext* context,
DeclRef<Decl> declRef,
IRType* type)
{
return emitDeclRef(
context,
declRef.decl,
declRef.substitutions.substitutions,
type);
}
static void lowerFrontEndEntryPointToIR(
IRGenContext* context,
EntryPoint* entryPoint)
{
// TODO: We should emit an entry point as a dedicated IR function
// (distinct from the IR function used if it were called normally),
// with a mangled name based on the original function name plus
// the stage for which it is being compiled as an entry point (so
// that entry points for distinct stages always have distinct names).
//
// For now we just have an (implicit) constraint that a given
// function should only be used as an entry point for one stage,
// and any such function should *not* be used as an ordinary function.
auto entryPointFuncDecl = entryPoint->getFuncDecl();
auto builder = context->irBuilder;
builder->setInsertInto(builder->getModule()->getModuleInst());
auto loweredEntryPointFunc = getSimpleVal(context,
ensureDecl(context, entryPointFuncDecl));
// Attach a marker decoration so that we recognize
// this as an entry point.
//
IRInst* instToDecorate = loweredEntryPointFunc;
if(auto irGeneric = as<IRGeneric>(instToDecorate))
{
instToDecorate = findGenericReturnVal(irGeneric);
}
{
Name* entryPointName = entryPoint->getFuncDecl()->getName();
builder->addEntryPointDecoration(instToDecorate, entryPoint->getProfile(), entryPointName->text.getUnownedSlice());
}
// Go through the entry point parameters creating decorations from layout as appropriate
// But only if this is a definition not a declaration
if (isDefinition(instToDecorate))
{
FilteredMemberList<ParamDecl> params = entryPointFuncDecl->getParameters();
IRGlobalValueWithParams* valueWithParams = as<IRGlobalValueWithParams>(instToDecorate);
if (valueWithParams)
{
IRParam* irParam = valueWithParams->getFirstParam();
for (auto param : params)
{
if (auto modifier = param->findModifier<HLSLGeometryShaderInputPrimitiveTypeModifier>())
{
IROp op = kIROp_Invalid;
if (as<HLSLTriangleModifier>(modifier))
op = kIROp_TriangleInputPrimitiveTypeDecoration;
else if (as<HLSLPointModifier>(modifier))
op = kIROp_PointInputPrimitiveTypeDecoration;
else if (as<HLSLLineModifier>(modifier))
op = kIROp_LineInputPrimitiveTypeDecoration;
else if (as<HLSLLineAdjModifier>(modifier))
op = kIROp_LineAdjInputPrimitiveTypeDecoration;
else if (as<HLSLTriangleAdjModifier>(modifier))
op = kIROp_TriangleAdjInputPrimitiveTypeDecoration;
if (op != kIROp_Invalid)
{
builder->addDecoration(irParam, op);
}
else
{
SLANG_UNEXPECTED("unhandled primitive type");
}
}
irParam = irParam->getNextParam();
}
}
}
}
static void lowerProgramEntryPointToIR(
IRGenContext* context,
EntryPoint* entryPoint,
EntryPoint::EntryPointSpecializationInfo* specializationInfo)
{
auto entryPointFuncDeclRef = entryPoint->getFuncDeclRef();
if(specializationInfo)
entryPointFuncDeclRef = specializationInfo->specializedFuncDeclRef;
// First, lower the entry point like an ordinary function
auto entryPointFuncType = lowerType(context, getFuncType(context->astBuilder, entryPointFuncDeclRef));
auto builder = context->irBuilder;
builder->setInsertInto(builder->getModule()->getModuleInst());
auto loweredEntryPointFunc = getSimpleVal(context,
emitDeclRef(context, entryPointFuncDeclRef, entryPointFuncType));
if(!loweredEntryPointFunc->findDecoration<IRLinkageDecoration>())
{
builder->addExportDecoration(loweredEntryPointFunc, getMangledName(context->astBuilder, entryPointFuncDeclRef).getUnownedSlice());
}
// We may have shader parameters of interface/existential type,
// which need us to supply concrete type information for specialization.
//
if(specializationInfo && specializationInfo->existentialSpecializationArgs.getCount() != 0)
{
List<IRInst*> existentialSlotArgs;
for(auto arg : specializationInfo->existentialSpecializationArgs )
{
auto irArgType = lowerSimpleVal(context, arg.val);
existentialSlotArgs.add(irArgType);
if(auto witness = arg.witness)
{
auto irWitnessTable = lowerSimpleVal(context, witness);
existentialSlotArgs.add(irWitnessTable);
}
}
builder->addBindExistentialSlotsDecoration(loweredEntryPointFunc, existentialSlotArgs.getCount(), existentialSlotArgs.getBuffer());
}
}
/// Ensure that `decl` and all relevant declarations under it get emitted.
static void ensureAllDeclsRec(
IRGenContext* context,
Decl* decl)
{
ensureDecl(context, decl);
// Note: We are checking here for aggregate type declarations, and
// not for `ContainerDecl`s in general. This is because many kinds
// of container declarations will already take responsibility for emitting
// their children directly (e.g., a function declaration is responsible
// for emitting its own parameters).
//
// Aggregate types are the main case where we can emit an outer declaration
// and not the stuff nested inside of it.
//
if(auto containerDecl = as<AggTypeDeclBase>(decl))
{
for (auto memberDecl : containerDecl->members)
{
ensureAllDeclsRec(context, memberDecl);
}
}
else if (auto genericDecl = as<GenericDecl>(decl))
{
ensureAllDeclsRec(context, genericDecl->inner);
}
}
IRModule* generateIRForTranslationUnit(
ASTBuilder* astBuilder,
TranslationUnitRequest* translationUnit)
{
auto compileRequest = translationUnit->compileRequest;
SharedIRGenContext sharedContextStorage(
translationUnit->getSession(),
translationUnit->compileRequest->getSink(),
translationUnit->compileRequest->getLinkage()->m_obfuscateCode,
translationUnit->getModuleDecl());
SharedIRGenContext* sharedContext = &sharedContextStorage;
IRGenContext contextStorage(sharedContext, astBuilder);
IRGenContext* context = &contextStorage;
SharedIRBuilder sharedBuilderStorage;
SharedIRBuilder* sharedBuilder = &sharedBuilderStorage;
sharedBuilder->module = nullptr;
sharedBuilder->session = compileRequest->getSession();
IRBuilder builderStorage;
IRBuilder* builder = &builderStorage;
builder->sharedBuilder = sharedBuilder;
IRModule* module = builder->createModule();
sharedBuilder->module = module;
context->irBuilder = builder;
// We need to emit IR for all public/exported symbols
// in the translation unit.
//
// For now, we will assume that *all* global-scope declarations
// represent public/exported symbols.
// First, ensure that all entry points have been emitted,
// in case they require special handling.
for (auto entryPoint : translationUnit->getEntryPoints())
{
lowerFrontEndEntryPointToIR(context, entryPoint);
}
//
// Next, ensure that all other global declarations have
// been emitted.
for (auto decl : translationUnit->getModuleDecl()->members)
{
ensureAllDeclsRec(context, decl);
}
// Build a global instruction to hold all the string
// literals used in the module.
{
auto& stringLits = sharedContext->m_stringLiterals;
auto stringLitCount = stringLits.getCount();
if(stringLitCount != 0)
{
builder->setInsertInto(module->getModuleInst());
builder->emitIntrinsicInst(builder->getVoidType(), kIROp_GlobalHashedStringLiterals, stringLitCount, stringLits.getBuffer());
}
}
#if 0
fprintf(stderr, "### GENERATED\n");
dumpIR(module);
fprintf(stderr, "###\n");
#endif
validateIRModuleIfEnabled(compileRequest, module);
// We will perform certain "mandatory" optimization passes now.
// These passes serve two purposes:
//
// 1. To simplify the code that we use in backend compilation,
// or when serializing/deserializing modules, so that we can
// amortize this effort when we compile multiple entry points
// that use the same module(s).
//
// 2. To ensure certain semantic properties that can't be
// validated without dataflow information. For example, we want
// to detect when a variable might be used before it is initialized.
// Note: if you need to debug the IR that is created before
// any mandatory optimizations have been applied, then
// uncomment this line while debugging.
// dumpIR(module);
// First, inline calls to any functions that have been
// marked for mandatory "early" inlining.
//
performMandatoryEarlyInlining(module);
// Next, attempt to promote local variables to SSA
// temporaries whenever possible.
constructSSA(module);
// Do basic constant folding and dead code elimination
// using Sparse Conditional Constant Propagation (SCCP)
//
applySparseConditionalConstantPropagation(module);
// Propagate `constexpr`-ness through the dataflow graph (and the
// call graph) based on constraints imposed by different instructions.
propagateConstExpr(module, compileRequest->getSink());
// TODO: give error messages if any `undefined` or
// `unreachable` instructions remain.
checkForMissingReturns(module, compileRequest->getSink());
// The "mandatory" optimization passes may make use of the
// `IRHighLevelDeclDecoration` type to relate IR instructions
// back to AST-level code in order to improve the quality
// of diagnostics that are emitted.
//
// While it is important for these passes to have access
// to AST-level information, allowing that information to
// flow into later steps (e.g., code generation) could lead
// to unclean layering of the parts of the compiler.
// In principle, back-end steps should not need to know where
// IR code came from.
//
// In order to avoid problems, we run a pass here to strip
// out any decorations that should not be relied upon by
// later passes.
//
{
// Because we are already stripping out undesired decorations,
// this is also a convenient place to remove any `IRNameHintDecoration`s
// in the case where we are obfuscating code. We handle this
// by setting up the options for the stripping pass appropriately.
//
IRStripOptions stripOptions;
Linkage* linkage = compileRequest->getLinkage();
stripOptions.shouldStripNameHints = linkage->m_obfuscateCode;
stripOptions.stripSourceLocs = linkage->m_obfuscateCode;
stripFrontEndOnlyInstructions(module, stripOptions);
// Stripping out decorations could leave some dead code behind
// in the module, and in some cases that extra code is also
// undesirable (e.g., the string literals referenced by name-hint
// decorations are just as undesirable as the decorations themselves).
// To clean up after ourselves we also run a dead-code elimination
// pass here, but make sure to set our options so that we don't
// eliminate anything that has been marked for export.
//
IRDeadCodeEliminationOptions options;
options.keepExportsAlive = true;
eliminateDeadCode(module, options);
}
// TODO: consider doing some more aggressive optimizations
// (in particular specialization of generics) here, so
// that we can avoid doing them downstream.
//
// Note: doing specialization or inlining involving code
// from other modules potentially makes the IR we generate
// "fragile" in that we'd now need to recompile when
// a module we depend on changes.
validateIRModuleIfEnabled(compileRequest, module);
// If we are being asked to dump IR during compilation,
// then we can dump the initial IR for the module here.
if(compileRequest->shouldDumpIR)
{
DiagnosticSinkWriter writer(compileRequest->getSink());
dumpIR(module, &writer);
}
return module;
}
/// Context for generating IR code to represent a `SpecializedComponentType`
struct SpecializedComponentTypeIRGenContext : ComponentTypeVisitor
{
DiagnosticSink* sink;
Linkage* linkage;
Session* session;
IRGenContext* context;
IRBuilder* builder;
RefPtr<IRModule> process(
SpecializedComponentType* componentType,
DiagnosticSink* inSink)
{
sink = inSink;
linkage = componentType->getLinkage();
session = linkage->getSessionImpl();
SharedIRGenContext sharedContextStorage(
session,
sink,
linkage->m_obfuscateCode
);
SharedIRGenContext* sharedContext = &sharedContextStorage;
IRGenContext contextStorage(sharedContext, linkage->getASTBuilder());
context = &contextStorage;
SharedIRBuilder sharedBuilderStorage;
SharedIRBuilder* sharedBuilder = &sharedBuilderStorage;
sharedBuilder->module = nullptr;
sharedBuilder->session = session;
IRBuilder builderStorage;
builder = &builderStorage;
builder->sharedBuilder = sharedBuilder;
RefPtr<IRModule> module = builder->createModule();
sharedBuilder->module = module;
builder->setInsertInto(module->getModuleInst());
context->irBuilder = builder;
componentType->acceptVisitor(this, nullptr);
return module;
}
void visitEntryPoint(EntryPoint* entryPoint, EntryPoint::EntryPointSpecializationInfo* specializationInfo) SLANG_OVERRIDE
{
// We need to emit symbols for all of the entry
// points in the program; this is especially
// important in the case where a generic entry
// point is being specialized.
//
lowerProgramEntryPointToIR(context, entryPoint, specializationInfo);
}
void visitModule(Module* module, Module::ModuleSpecializationInfo* specializationInfo) SLANG_OVERRIDE
{
// We've hit a leaf module, so we should be able to bind any global
// generic type parameters here...
//
if( specializationInfo )
{
for( auto genericArgInfo : specializationInfo->genericArgs )
{
IRInst* irParam = getSimpleVal(context, ensureDecl(context, genericArgInfo.paramDecl));
IRInst* irVal = lowerSimpleVal(context, genericArgInfo.argVal);
// bind `irParam` to `irVal`
builder->emitBindGlobalGenericParam(irParam, irVal);
}
auto shaderParamCount = module->getShaderParamCount();
Index existentialArgOffset = 0;
for( Index ii = 0; ii < shaderParamCount; ++ii )
{
auto shaderParam = module->getShaderParam(ii);
auto specializationArgCount = shaderParam.specializationParamCount;
IRInst* irParam = getSimpleVal(context, ensureDecl(context, shaderParam.paramDeclRef));
List<IRInst*> irSlotArgs;
for( Index jj = 0; jj < specializationArgCount; ++jj )
{
auto& specializationArg = specializationInfo->existentialArgs[existentialArgOffset++];
auto irType = lowerSimpleVal(context, specializationArg.val);
auto irWitness = lowerSimpleVal(context, specializationArg.witness);
irSlotArgs.add(irType);
irSlotArgs.add(irWitness);
}
builder->addBindExistentialSlotsDecoration(
irParam,
irSlotArgs.getCount(),
irSlotArgs.getBuffer());
}
}
}
void visitComposite(CompositeComponentType* composite, CompositeComponentType::CompositeSpecializationInfo* specializationInfo) SLANG_OVERRIDE
{
visitChildren(composite, specializationInfo);
}
void visitSpecialized(SpecializedComponentType* specialized) SLANG_OVERRIDE
{
visitChildren(specialized);
}
};
RefPtr<IRModule> generateIRForSpecializedComponentType(
SpecializedComponentType* componentType,
DiagnosticSink* sink)
{
SpecializedComponentTypeIRGenContext context;
return context.process(componentType, sink);
}
RefPtr<IRModule> TargetProgram::getOrCreateIRModuleForLayout(DiagnosticSink* sink)
{
getOrCreateLayout(sink);
return m_irModuleForLayout;
}
/// Specialized IR generation context for when generating IR for layouts.
struct IRLayoutGenContext : IRGenContext
{
IRLayoutGenContext(SharedIRGenContext* shared, ASTBuilder* astBuilder)
: IRGenContext(shared, astBuilder)
{}
/// Cache for custom key instructions used for entry-point parameter layout information.
Dictionary<ParamDecl*, IRStructKey*> mapEntryPointParamToKey;
};
/// Lower an AST-level type layout to an IR-level type layout.
IRTypeLayout* lowerTypeLayout(
IRLayoutGenContext* context,
TypeLayout* typeLayout);
/// Lower an AST-level variable layout to an IR-level variable layout.
IRVarLayout* lowerVarLayout(
IRLayoutGenContext* context,
VarLayout* varLayout);
/// Shared code for most `lowerTypeLayout` cases.
///
/// Handles copying of resource usage and pending data type layout
/// from the AST `typeLayout` to the specified `builder`.
///
static IRTypeLayout* _lowerTypeLayoutCommon(
IRLayoutGenContext* context,
IRTypeLayout::Builder* builder,
TypeLayout* typeLayout)
{
for( auto resInfo : typeLayout->resourceInfos )
{
builder->addResourceUsage(resInfo.kind, resInfo.count);
}
if( auto pendingTypeLayout = typeLayout->pendingDataTypeLayout )
{
builder->setPendingTypeLayout(
lowerTypeLayout(context, pendingTypeLayout));
}
return builder->build();
}
IRTypeLayout* lowerTypeLayout(
IRLayoutGenContext* context,
TypeLayout* typeLayout)
{
// TODO: We chould consider caching the layouts we create based on `typeLayout`
// and re-using them. This isn't strictly necessary because we emit the
// instructions as "hoistable" which should give us de-duplication, and it wouldn't
// help much until/unless the AST level gets less wasteful about how it computes layout.
// We will use casting to detect if `typeLayout` is
// one of the cases that requires a dedicated sub-type
// of IR type layout.
//
if( auto paramGroupTypeLayout = as<ParameterGroupTypeLayout>(typeLayout) )
{
IRParameterGroupTypeLayout::Builder builder(context->irBuilder);
builder.setContainerVarLayout(
lowerVarLayout(context, paramGroupTypeLayout->containerVarLayout));
builder.setElementVarLayout(
lowerVarLayout(context, paramGroupTypeLayout->elementVarLayout));
builder.setOffsetElementTypeLayout(
lowerTypeLayout(context, paramGroupTypeLayout->offsetElementTypeLayout));
return _lowerTypeLayoutCommon(context, &builder, paramGroupTypeLayout);
}
else if( auto structTypeLayout = as<StructTypeLayout>(typeLayout) )
{
IRStructTypeLayout::Builder builder(context->irBuilder);
for( auto fieldLayout : structTypeLayout->fields )
{
auto fieldDecl = fieldLayout->varDecl;
IRStructKey* irFieldKey = nullptr;
if(auto paramDecl = as<ParamDecl>(fieldDecl) )
{
// There is a subtle special case here.
//
// A `StructTypeLayout` might be used to represent
// the parameters of an entry point, and this is the
// one and only case where the "fields" being used
// might actually be `ParamDecl`s.
//
// The IR encoding of structure type layouts relies
// on using field "key" instructions to identify
// the fields, but these don't exist (by default)
// for function parameters.
//
// To get around this problem we will create key
// instructions to stand in for the entry-point parameters
// as needed when generating layout.
//
// We need to cache the generated keys on the context,
// so that if we run into another type layout for the
// same entry point we will re-use the same keys.
//
if( !context->mapEntryPointParamToKey.TryGetValue(paramDecl, irFieldKey) )
{
irFieldKey = context->irBuilder->createStructKey();
// TODO: It might eventually be a good idea to attach a mangled
// name to the key we just generated (derived from the entry point
// and parameter name), even though parameters don't usually have
// linkage.
//
// Doing so would ensure that if we ever combined partial layout
// information from different modules they would agree on the key
// to use for entry-point parameters.
//
// For now this is a non-issue because both the creation and use
// of these keys will be local to a single `IREntryPointLayout`,
// and we don't support combination at a finer granularity than that.
context->mapEntryPointParamToKey.Add(paramDecl, irFieldKey);
}
}
else
{
IRInst* irFieldKeyInst = getSimpleVal(context,
ensureDecl(context, fieldDecl));
irFieldKey = as<IRStructKey>(irFieldKeyInst);
}
SLANG_ASSERT(irFieldKey);
auto irFieldLayout = lowerVarLayout(context, fieldLayout);
builder.addField(irFieldKey, irFieldLayout);
}
return _lowerTypeLayoutCommon(context, &builder, structTypeLayout);
}
else if( auto arrayTypeLayout = as<ArrayTypeLayout>(typeLayout) )
{
auto irElementTypeLayout = lowerTypeLayout(context, arrayTypeLayout->elementTypeLayout);
IRArrayTypeLayout::Builder builder(context->irBuilder, irElementTypeLayout);
return _lowerTypeLayoutCommon(context, &builder, arrayTypeLayout);
}
else if( auto taggedUnionTypeLayout = as<TaggedUnionTypeLayout>(typeLayout) )
{
IRTaggedUnionTypeLayout::Builder builder(context->irBuilder, taggedUnionTypeLayout->tagOffset);
for( auto caseTypeLayout : taggedUnionTypeLayout->caseTypeLayouts )
{
builder.addCaseTypeLayout(
lowerTypeLayout(
context,
caseTypeLayout));
}
return _lowerTypeLayoutCommon(context, &builder, taggedUnionTypeLayout);
}
else if( auto streamOutputTypeLayout = as<StreamOutputTypeLayout>(typeLayout) )
{
auto irElementTypeLayout = lowerTypeLayout(context, streamOutputTypeLayout->elementTypeLayout);
IRStreamOutputTypeLayout::Builder builder(context->irBuilder, irElementTypeLayout);
return _lowerTypeLayoutCommon(context, &builder, streamOutputTypeLayout);
}
else if( auto matrixTypeLayout = as<MatrixTypeLayout>(typeLayout) )
{
// TODO: Our support for explicit layouts on matrix types is minimal, so whether
// or not we even include `IRMatrixTypeLayout` doesn't impact any behavior we
// currently test.
//
// Our handling of matrix types and their layout needs a complete overhaul, but
// that isn't something we can get to right away, so we'll just try to pass
// along this data as best we can for now.
IRMatrixTypeLayout::Builder builder(context->irBuilder, matrixTypeLayout->mode);
return _lowerTypeLayoutCommon(context, &builder, matrixTypeLayout);
}
else
{
// If no special case applies we will build a generic `IRTypeLayout`.
//
IRTypeLayout::Builder builder(context->irBuilder);
return _lowerTypeLayoutCommon(context, &builder, typeLayout);
}
}
IRVarLayout* lowerVarLayout(
IRLayoutGenContext* context,
VarLayout* varLayout)
{
auto irTypeLayout = lowerTypeLayout(context, varLayout->typeLayout);
IRVarLayout::Builder irLayoutBuilder(context->irBuilder, irTypeLayout);
for( auto resInfo : varLayout->resourceInfos )
{
auto irResInfo = irLayoutBuilder.findOrAddResourceInfo(resInfo.kind);
irResInfo->offset = resInfo.index;
irResInfo->space = resInfo.space;
}
if( auto pendingVarLayout = varLayout->pendingVarLayout )
{
irLayoutBuilder.setPendingVarLayout(
lowerVarLayout(context, pendingVarLayout));
}
// We will only generate layout information with *either* a system-value
// semantic or a user-defined semantic, and we will always check for
// the system-value semantic first because the AST-level representation
// seems to encode both when a system-value semantic is present.
//
if( varLayout->systemValueSemantic.getLength() )
{
irLayoutBuilder.setSystemValueSemantic(
varLayout->systemValueSemantic,
varLayout->systemValueSemanticIndex);
}
else if( varLayout->semanticName.getLength() )
{
irLayoutBuilder.setUserSemantic(
varLayout->semanticName,
varLayout->semanticIndex);
}
if( varLayout->stage != Stage::Unknown )
{
irLayoutBuilder.setStage(varLayout->stage);
}
return irLayoutBuilder.build();
}
/// Handle the lowering of an entry-point result layout to the IR
IRVarLayout* lowerEntryPointResultLayout(
IRLayoutGenContext* context,
VarLayout* layout)
{
// The easy case is when there is a non-null `layout`, because we
// can handle it like any other var layout.
//
if(layout)
return lowerVarLayout(context, layout);
// Right now the AST-level layout logic will leave a null layout
// for the result when an entry point has a `void` result type.
//
// TODO: We should fix this at the AST level instead of the IR,
// but doing so would impact reflection, where clients could
// be using a null check to test for a `void` result.
//
// As a workaround, we will create an empty type layout and
// an empty var layout that represents it, consistent with the
// way that a `void` value consumes no resources.
//
IRTypeLayout::Builder typeLayoutBuilder(context->irBuilder);
auto irTypeLayout = typeLayoutBuilder.build();
IRVarLayout::Builder varLayoutBuilder(context->irBuilder, irTypeLayout);
return varLayoutBuilder.build();
}
/// Lower AST-level layout information for an entry point to the IR
IREntryPointLayout* lowerEntryPointLayout(
IRLayoutGenContext* context,
EntryPointLayout* entryPointLayout)
{
auto irParamsLayout = lowerVarLayout(context, entryPointLayout->parametersLayout);
auto irResultLayout = lowerEntryPointResultLayout(context, entryPointLayout->resultLayout);
return context->irBuilder->getEntryPointLayout(
irParamsLayout,
irResultLayout);
}
RefPtr<IRModule> TargetProgram::createIRModuleForLayout(DiagnosticSink* sink)
{
if(m_irModuleForLayout)
return m_irModuleForLayout;
// Okay, now we need to fill it in.
auto programLayout = getOrCreateLayout(sink);
if(!programLayout)
return nullptr;
auto program = getProgram();
auto linkage = program->getLinkage();
auto session = linkage->getSessionImpl();
SharedIRGenContext sharedContextStorage(
session,
sink,
linkage->m_obfuscateCode);
auto sharedContext = &sharedContextStorage;
ASTBuilder* astBuilder = linkage->getASTBuilder();
IRLayoutGenContext contextStorage(sharedContext, astBuilder);
auto context = &contextStorage;
SharedIRBuilder sharedBuilderStorage;
auto sharedBuilder = &sharedBuilderStorage;
sharedBuilder->module = nullptr;
sharedBuilder->session = session;
IRBuilder builderStorage;
auto builder = &builderStorage;
builder->sharedBuilder = sharedBuilder;
RefPtr<IRModule> irModule = builder->createModule();
sharedBuilder->module = irModule;
builder->setInsertInto(irModule->getModuleInst());
context->irBuilder = builder;
// Okay, now we need to walk through and decorate everything.
auto globalStructLayout = getScopeStructLayout(programLayout);
for(auto globalVarPair : globalStructLayout->mapVarToLayout)
{
auto varDecl = globalVarPair.Key;
auto varLayout = globalVarPair.Value;
// Ensure that an `[import(...)]` declaration for the variable
// has been emitted to this module, so that we will have something
// to decorate.
//
auto irVar = getSimpleVal(context, ensureDecl(context, varDecl));
auto irLayout = lowerVarLayout(context, varLayout);
// Now attach the decoration to the variable.
//
builder->addLayoutDecoration(irVar, irLayout);
}
for( auto entryPointLayout : programLayout->entryPoints )
{
auto funcDeclRef = entryPointLayout->entryPoint;
// HACK: skip over entry points that came from deserialization,
// and thus don't have AST-level information for us to work with.
//
if(!funcDeclRef)
continue;
auto irFuncType = lowerType(context, getFuncType(astBuilder, funcDeclRef));
auto irFunc = getSimpleVal(context, emitDeclRef(context, funcDeclRef, irFuncType));
if( !irFunc->findDecoration<IRLinkageDecoration>() )
{
builder->addImportDecoration(irFunc, getMangledName(astBuilder, funcDeclRef).getUnownedSlice());
}
auto irEntryPointLayout = lowerEntryPointLayout(context, entryPointLayout);
builder->addLayoutDecoration(irFunc, irEntryPointLayout);
}
for( auto taggedUnionTypeLayout : programLayout->taggedUnionTypeLayouts )
{
auto taggedUnionType = taggedUnionTypeLayout->getType();
auto irType = lowerType(context, taggedUnionType);
auto irTypeLayout = lowerTypeLayout(context, taggedUnionTypeLayout);
builder->addLayoutDecoration(irType, irTypeLayout);
}
// Lets strip and run DCE here
if (linkage->m_obfuscateCode)
{
IRStripOptions stripOptions;
stripOptions.shouldStripNameHints = linkage->m_obfuscateCode;
stripOptions.stripSourceLocs = linkage->m_obfuscateCode;
stripFrontEndOnlyInstructions(irModule, stripOptions);
IRDeadCodeEliminationOptions options;
options.keepExportsAlive = true;
options.keepLayoutsAlive = true;
// Eliminate any dead code
eliminateDeadCode(irModule, options);
}
m_irModuleForLayout = irModule;
return irModule;
}
} // namespace Slang
