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Tip revision: f544a7d02dc5434863cc36ba5ff29b327904164e authored by Fredrik Ekre on 28 February 2022, 17:36:35 UTC
WIP: Package environment propagation for SSH manager.
WIP: Package environment propagation for SSH manager.
Tip revision: f544a7d
abi_arm.cpp
// This file is a part of Julia. License is MIT: https://julialang.org/license
//===----------------------------------------------------------------------===//
//
// The ABI implementation used for ARM targets.
//
//===----------------------------------------------------------------------===//
//
// The Procedure Call Standard can be found here:
// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042f/IHI0042F_aapcs.pdf
//
//===----------------------------------------------------------------------===//
#if defined _CPU_ARM_
#ifndef __ARM_EABI__
# error "the Julia ARM ABI implementation only supports EABI"
#endif
#ifndef __ARM_PCS_VFP
# error "the Julia ARM ABI implementation requires VFP support"
#endif
#endif
struct ABI_ARMLayout : AbiLayout {
bool needPassByRef(jl_datatype_t *dt, AttrBuilder &abi, LLVMContext &ctx, Type *Ty) override
{
return false;
}
#define jl_is_floattype(v) jl_subtype(v,(jl_value_t*)jl_floatingpoint_type)
Type *get_llvm_fptype(jl_datatype_t *dt, LLVMContext &ctx) const
{
// Assume jl_is_datatype(dt) && !jl_is_abstracttype(dt)
if (dt->name->mutabl || jl_datatype_nfields(dt) != 0)
return NULL;
Type *lltype;
// Check size first since it's cheaper.
switch (jl_datatype_size(dt)) {
case 2:
lltype = Type::getHalfTy(ctx);
break;
case 4:
lltype = Type::getFloatTy(ctx);
break;
case 8:
lltype = Type::getDoubleTy(ctx);
break;
default:
return NULL;
}
return ((jl_floatingpoint_type && jl_is_floattype((jl_value_t*)dt)) ?
lltype : NULL);
}
// Check whether a type contained by a candidate homogeneous aggregate is valid
// fundamental type.
//
// Returns the corresponding LLVM type.
Type *isLegalHAType(jl_datatype_t *dt, LLVMContext &ctx) const
{
// single- or double-precision floating-point type
if (Type *fp = get_llvm_fptype(dt, ctx))
return fp;
// NOT SUPPORTED: 64- or 128-bit containerized vectors
return NULL;
}
// Check whether a type is a legal homogeneous aggregate.
// Returns the number of fundamental members.
//
// Legality of the HA is determined by a nonzero return value.
// In case of a non-legal HA, the value of 'base' is undefined.
size_t isLegalHA(jl_datatype_t *dt, Type *&base, LLVMContext &ctx) const
{
// Homogeneous aggregates are only used for VFP registers,
// so use that definition of legality (section 6.1.2.1)
if (jl_is_structtype(dt)) {
// Fast path checks before descending the type hierarchy
// (4 x 128b vector == 64B max size)
if (jl_datatype_size(dt) > 64 || dt->layout->npointers || dt->layout->haspadding)
return 0;
base = NULL;
size_t total_members = 0;
size_t parent_members = jl_datatype_nfields(dt);
for (size_t i = 0; i < parent_members; ++i) {
jl_datatype_t *fdt = (jl_datatype_t*)jl_field_type(dt,i);
Type *T = isLegalHAType(fdt, ctx);
if (T)
total_members++;
else if (size_t field_members = isLegalHA(fdt, T, ctx))
// recursive application (expanding nested composite types)
total_members += field_members;
else
return 0;
if (!base)
base = T;
else if (base != T)
return 0;
}
// ... with one to four Elements.
if (total_members < 1 || total_members > 4)
return 0;
return total_members;
}
return 0;
}
// Determine if an argument can be passed through a coprocessor register.
//
// All the out parameters should be default to `false`.
void classify_cprc(jl_datatype_t *dt, bool *vfp, LLVMContext &ctx) const
{
// Based on section 6.1 of the Procedure Call Standard
// VFP: 6.1.2.1
// - A half-precision floating-point type.
// - A single-precision floating-point type.
// - A double-precision floating-point type.
if (get_llvm_fptype(dt, ctx)) {
*vfp = true;
return;
}
// NOT SUPPORTED: A 64-bit or 128-bit containerized vector type.
// - A Homogeneous Aggregate
Type *base = NULL;
if (isLegalHA(dt, base, ctx)) {
*vfp = true;
return;
}
}
void classify_return_arg(jl_datatype_t *dt, bool *reg, bool *onstack,
bool *need_rewrite, LLVMContext &ctx) const
{
// Based on section 5.4 of the Procedure Call Standard
// VFP standard variant: see 6.1.2.2
// Any result whose type would satisfy the conditions for a VFP CPRC is
// returned in the appropriate number of consecutive VFP registers
// starting with the lowest numbered register (s0, d0, q0).
classify_cprc(dt, reg, ctx);
if (*reg)
return;
// - A Half-precision Floating Point Type is returned in the least
// significant 16 bits of r0.
if (dt == jl_float16_type) {
*reg = true;
return;
}
// - A Fundamental Data Type that is smaller than 4 bytes is zero- or
// sign-extended to a word and returned in r0.
// - A double-word sized Fundamental Data Type (e.g., long long, double and
// 64-bit containerized vectors) is returned in r0 and r1.
// - A word-sized Fundamental Data Type (eg., int, float) is returned in r0.
// NOTE: assuming "fundamental type" == jl_is_primitivetype, might need exact def
if (jl_is_primitivetype(dt) && jl_datatype_size(dt) <= 8) {
*reg = true;
return;
}
// If we ever support containerized vectors on an ARMv7 without VFP,
// these can be returned in r0-r3 as well.
// NOTE: we don't check for jl_is_structtype below, because at this point
// everything will be rewritten to look like a composite aggregate
*need_rewrite = true;
// - A Composite Type not larger than 4 bytes is returned in r0. The format
// is as if the result had been stored in memory at a word-aligned address
// and then loaded into r0 with an LDR instruction. Any bits in r0 that
// lie outside the bounds of the result have unspecified values.
// - A Composite Type larger than 4 bytes, or whose size cannot be
// determined statically by both caller and callee, is stored in memory at
// an address passed as an extra argument when the function was called
// (ยง5.5, rule A.4). The memory to be used for the result may be modified
// at any point during the function call.
if (jl_datatype_size(dt) <= 4)
*reg = true;
else
*onstack = true;
}
bool use_sret(jl_datatype_t *dt, LLVMContext &ctx) override
{
bool reg = false;
bool onstack = false;
bool need_rewrite = false;
classify_return_arg(dt, ®, &onstack, &need_rewrite, ctx);
return onstack;
}
// Determine which kind of register the argument will be passed in and
// if the argument has to be passed on stack (including by reference).
//
// If the argument should be passed in SIMD and floating-point registers,
// we may need to rewrite the argument types to [n x ftype].
// If the argument should be passed in general purpose registers, we may need
// to rewrite the argument types to [n x i64].
//
// If the argument has to be passed on stack, we need to use sret.
//
// All the out parameters should be default to `false`.
void classify_arg(jl_datatype_t *dt, bool *reg,
bool *onstack, bool *need_rewrite, LLVMContext &ctx) const
{
// Based on section 5.5 of the Procedure Call Standard
// C.1.cp
// If the argument is a CPRC and there are sufficient unallocated
// co-processor registers of the appropriate class, the argument is
// allocated to co-processor registers.
classify_cprc(dt, reg, ctx);
if (*reg)
return;
// Handle fundamental types
if (jl_is_primitivetype(dt) && jl_datatype_size(dt) <= 8) {
*reg = true;
return;
}
*need_rewrite = true;
}
Type *preferred_llvm_type(jl_datatype_t *dt, bool isret, LLVMContext &ctx) const override
{
if (Type *fptype = get_llvm_fptype(dt, ctx))
return fptype;
bool reg = false;
bool onstack = false;
bool need_rewrite = false;
if (isret)
classify_return_arg(dt, ®, &onstack, &need_rewrite, ctx);
else
classify_arg(dt, ®, &onstack, &need_rewrite, ctx);
if (!need_rewrite)
return NULL;
// Based on section 4 of the Procedure Call Standard
// If some type is illegal and needs to be rewritten,
// represent it as an aggregate composite type.
// 4.3.1: aggregates
// - The alignment of an aggregate shall be the alignment of its
// most-aligned component.
// - The size of an aggregate shall be the smallest multiple of its
// alignment that is sufficient to hold all of its members when they are
// laid out according to these rules.
// 5.5 B.5
// For a Composite Type, the alignment of the copy will have 4-byte
// alignment if its natural alignment is <= 4 and 8-byte alignment if
// its natural alignment is >= 8
size_t align = jl_datatype_align(dt);
if (align < 4)
align = 4;
if (align > 8)
align = 8;
Type *T = Type::getIntNTy(ctx, align*8);
return ArrayType::get(T, (jl_datatype_size(dt) + align - 1) / align);
}
};