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  LLVM Testing Infrastructure Guide

  <li><a href="#overview">Overview</a></li>
  <li><a href="#requirements">Requirements</a></li>
  <li><a href="#org">LLVM testing infrastructure organization</a>
      <li><a href="#regressiontests">Regression tests</a></li>
      <li><a href="#testsuite"><tt>test-suite</tt></a></li>
      <li><a href="#debuginfotests">Debugging Information tests</a></li>
  <li><a href="#quick">Quick start</a>
      <li><a href="#quickregressiontests">Regression tests</a></li>
      <li><a href="#quickdebuginfotests">Debugging Information tests</a></li>
  <li><a href="#rtstructure">Regression test structure</a>
      <li><a href="#rtcustom">Writing new regression tests</a></li>
      <li><a href="#FileCheck">The FileCheck utility</a></li>
      <li><a href="#rtvars">Variables and substitutions</a></li>
      <li><a href="#rtfeatures">Other features</a></li>
  <li><a href="#testsuiteoverview"><tt>test-suite</tt> Overview</a>
      <li><a href="#testsuitequickstart"><tt>test-suite</tt> Quickstart</a></li>
      <li><a href="#testsuitemakefiles"><tt>test-suite</tt> Makefiles</a></li>

<div class="doc_author">
  <p>Written by John T. Criswell, Daniel Dunbar, Reid Spencer, and Tanya Lattner</p>

<h2><a name="overview">Overview</a></h2>


<p>This document is the reference manual for the LLVM testing infrastructure. It
documents the structure of the LLVM testing infrastructure, the tools needed to
use it, and how to add and run tests.</p>


<h2><a name="requirements">Requirements</a></h2>


<p>In order to use the LLVM testing infrastructure, you will need all of the
software required to build LLVM, as well
as <a href="http://python.org">Python</a> 2.4 or later.</p>


<h2><a name="org">LLVM testing infrastructure organization</a></h2>


<p>The LLVM testing infrastructure contains two major categories of tests:
regression tests and whole programs. The regression tests are contained inside
the LLVM repository itself under <tt>llvm/test</tt> and are expected to always
pass -- they should be run before every commit.</p>

<p>The whole programs tests are referred to as the "LLVM test suite" (or
"test-suite") and are in the <tt>test-suite</tt> module in subversion. For
historical reasons, these tests are also referred to as the "nightly tests" in
places, which is less ambiguous than "test-suite" and remains in use although we
run them much more often than nightly.</p>

<!-- _______________________________________________________________________ -->
<h3><a name="regressiontests">Regression tests</a></h3>
<!-- _______________________________________________________________________ -->


<p>The regression tests are small pieces of code that test a specific feature of
LLVM or trigger a specific bug in LLVM.  They are usually written in LLVM
assembly language, but can be written in other languages if the test targets a
particular language front end (and the appropriate <tt>--with-llvmgcc</tt>
options were used at <tt>configure</tt> time of the <tt>llvm</tt> module). These
tests are driven by the 'lit' testing tool, which is part of LLVM.</p>

<p>These code fragments are not complete programs. The code generated
from them is never executed to determine correct behavior.</p>

<p>These code fragment tests are located in the <tt>llvm/test</tt>

<p>Typically when a bug is found in LLVM, a regression test containing 
just enough code to reproduce the problem should be written and placed 
somewhere underneath this directory.  In most cases, this will be a small 
piece of LLVM assembly language code, often distilled from an actual 
application or benchmark.</p>


<!-- _______________________________________________________________________ -->
<h3><a name="testsuite"><tt>test-suite</tt></a></h3>
<!-- _______________________________________________________________________ -->


<p>The test suite contains whole programs, which are pieces of code which can be
compiled and linked into a stand-alone program that can be executed.  These
programs are generally written in high level languages such as C or C++.</p>

<p>These programs are compiled using a user specified compiler and set of flags,
and then executed to capture the program output and timing information.  The
output of these programs is compared to a reference output to ensure that the
program is being compiled correctly.</p>

<p>In addition to compiling and executing programs, whole program tests serve as
a way of benchmarking LLVM performance, both in terms of the efficiency of the
programs generated as well as the speed with which LLVM compiles, optimizes, and
generates code.</p>

<p>The test-suite is located in the <tt>test-suite</tt> Subversion module.</p> 


<!-- _______________________________________________________________________ -->
<h3><a name="debuginfotests">Debugging Information tests</a></h3>
<!-- _______________________________________________________________________ -->


<p>The test suite contains tests to check quality of debugging information.
The test are written in C based languages or in LLVM assembly language. </p>

<p>These tests are compiled and run under a debugger. The debugger output
is checked to validate of debugging information. See README.txt in the 
test suite for more information . This test suite is located in the 
<tt>debuginfo-tests</tt> Subversion module. </p>



<h2><a name="quick">Quick start</a></h2>


  <p>The tests are located in two separate Subversion modules. The regressions
  tests are in the main "llvm" module under the directory
  <tt>llvm/test</tt> (so you get these tests for free with the main llvm
  tree). Use "make check-all" to run the regression tests after building

  <p>The more comprehensive test suite that includes whole programs in C and C++
  is in the <tt>test-suite</tt>
  module. See <a href="#testsuitequickstart"><tt>test-suite</tt> Quickstart</a>
  for more information on running these tests.</p>

<!-- _______________________________________________________________________ -->
<h3><a name="quickregressiontests">Regression tests</a></h3>
<!-- _______________________________________________________________________ -->
<p>To run all of the LLVM regression tests, use master Makefile in
 the <tt>llvm/test</tt> directory:</p>

<div class="doc_code">
% gmake -C llvm/test


<div class="doc_code">
% gmake check

<p>If you have <a href="http://clang.llvm.org/">Clang</a> checked out and built,
you can run the LLVM and Clang tests simultaneously using:</p>


<div class="doc_code">
% gmake check-all

<p>To run the tests with Valgrind (Memcheck by default), just append
<tt>VG=1</tt> to the commands above, e.g.:</p>

<div class="doc_code">
% gmake check VG=1

<p>To run individual tests or subsets of tests, you can use the 'llvm-lit'
script which is built as part of LLVM. For example, to run the
'Integer/BitCast.ll' test by itself you can run:</p>

<div class="doc_code">
% llvm-lit ~/llvm/test/Integer/BitCast.ll 

<p>or to run all of the ARM CodeGen tests:</p>

<div class="doc_code">
% llvm-lit ~/llvm/test/CodeGen/ARM

<p>For more information on using the 'lit' tool, see 'llvm-lit --help' or the
'lit' man page.</p>


<!-- _______________________________________________________________________ -->
<h3><a name="quickdebuginfotests">Debugging Information tests</a></h3>
<!-- _______________________________________________________________________ -->

<p> To run debugging information tests simply checkout the tests inside
clang/test directory. </p>

<div class="doc_code">
%cd clang/test
% svn co http://llvm.org/svn/llvm-project/debuginfo-tests/trunk debuginfo-tests

<p> These tests are already set up to run as part of clang regression tests.</p>




<h2><a name="rtstructure">Regression test structure</a></h2>
  <p>The LLVM regression tests are driven by 'lit' and are located in
  the <tt>llvm/test</tt> directory.

  <p>This directory contains a large array of small tests
  that exercise various features of LLVM and to ensure that regressions do not
  occur. The directory is broken into several sub-directories, each focused on
  a particular area of LLVM. A few of the important ones are:</p>

    <li><tt>Analysis</tt>: checks Analysis passes.</li>
    <li><tt>Archive</tt>: checks the Archive library.</li>
    <li><tt>Assembler</tt>: checks Assembly reader/writer functionality.</li>
    <li><tt>Bitcode</tt>: checks Bitcode reader/writer functionality.</li>
    <li><tt>CodeGen</tt>: checks code generation and each target.</li>
    <li><tt>Features</tt>: checks various features of the LLVM language.</li>
    <li><tt>Linker</tt>: tests bitcode linking.</li>
    <li><tt>Transforms</tt>: tests each of the scalar, IPO, and utility
    transforms to ensure they make the right transformations.</li>
    <li><tt>Verifier</tt>: tests the IR verifier.</li>

<!-- _______________________________________________________________________ -->
<h3><a name="rtcustom">Writing new regression tests</a></h3>
<!-- _______________________________________________________________________ -->
  <p>The regression test structure is very simple, but does require some
  information to be set. This information is gathered via <tt>configure</tt> and
  is written to a file, <tt>lit.site.cfg</tt>
  in <tt>llvm/test</tt>. The <tt>llvm/test</tt> Makefile does this work for

  <p>In order for the regression tests to work, each directory of tests must
  have a <tt>lit.local.cfg</tt> file. Lit looks for this file to determine how
  to run the tests. This file is just Python code and thus is very flexible,
  but we've standardized it for the LLVM regression tests. If you're adding a
  directory of tests, just copy <tt>lit.local.cfg</tt> from another directory to
  get running. The standard <tt>lit.local.cfg</tt> simply specifies which files
  to look in for tests. Any directory that contains only directories does not
  need the <tt>lit.local.cfg</tt> file. Read the
  <a href="http://llvm.org/cmds/lit.html">Lit documentation</a> for more
  information. </p>

  <p>The <tt>llvm-runtests</tt> function looks at each file that is passed to
  it and gathers any lines together that match "RUN:". These are the "RUN" lines
  that specify how the test is to be run. So, each test script must contain
  RUN lines if it is to do anything. If there are no RUN lines, the
  <tt>llvm-runtests</tt> function will issue an error and the test will

  <p>RUN lines are specified in the comments of the test program using the 
  keyword <tt>RUN</tt> followed by a colon, and lastly the command (pipeline) 
  to execute.  Together, these lines form the "script" that 
  <tt>llvm-runtests</tt> executes to run the test case.  The syntax of the
  RUN lines is similar to a shell's syntax for pipelines including I/O
  redirection and variable substitution.  However, even though these lines 
  may <i>look</i> like a shell script, they are not. RUN lines are interpreted 
  directly by the Tcl <tt>exec</tt> command. They are never executed by a 
  shell. Consequently the syntax differs from normal shell script syntax in a 
  few ways.  You can specify as many RUN lines as needed.</p>

  <p>lit performs substitution on each RUN line to replace LLVM tool
  names with the full paths to the executable built for each tool (in
  $(LLVM_OBJ_ROOT)/$(BuildMode)/bin).  This ensures that lit does not
  invoke any stray LLVM tools in the user's path during testing.</p>

  <p>Each RUN line is executed on its own, distinct from other lines unless
  its last character is <tt>\</tt>. This continuation character causes the RUN
  line to be concatenated with the next one. In this way you can build up long
  pipelines of commands without making huge line lengths. The lines ending in
  <tt>\</tt> are concatenated until a RUN line that doesn't end in <tt>\</tt> is
  found. This concatenated set of RUN lines then constitutes one execution. 
  Tcl will substitute variables and arrange for the pipeline to be executed. If
  any process in the pipeline fails, the entire line (and test case) fails too.

  <p> Below is an example of legal RUN lines in a <tt>.ll</tt> file:</p>

<div class="doc_code">
; RUN: llvm-as &lt; %s | llvm-dis &gt; %t1
; RUN: llvm-dis &lt; %s.bc-13 &gt; %t2
; RUN: diff %t1 %t2

  <p>As with a Unix shell, the RUN: lines permit pipelines and I/O redirection
  to be used. However, the usage is slightly different than for Bash. To check
  what's legal, see the documentation for the 
  <a href="http://www.tcl.tk/man/tcl8.5/TclCmd/exec.htm#M2">Tcl exec</a>
  command and the 
  <a href="http://www.tcl.tk/man/tcl8.5/tutorial/Tcl26.html">tutorial</a>. 
  The major differences are:</p>
    <li>You can't do <tt>2&gt;&amp;1</tt>. That will cause Tcl to write to a
    file named <tt>&amp;1</tt>. Usually this is done to get stderr to go through
    a pipe. You can do that in tcl with <tt>|&amp;</tt> so replace this idiom:
    <tt>... 2&gt;&amp;1 | grep</tt> with <tt>... |&amp; grep</tt></li>
    <li>You can only redirect to a file, not to another descriptor and not from
    a here document.</li>
    <li>tcl supports redirecting to open files with the @ syntax but you
    shouldn't use that here.</li>

  <p>There are some quoting rules that you must pay attention to when writing
  your RUN lines. In general nothing needs to be quoted. Tcl won't strip off any
  quote characters so they will get passed to the invoked program. For

<div class="doc_code">
... | grep 'find this string'

  <p>This will fail because the ' characters are passed to grep. This would
  instruction grep to look for <tt>'find</tt> in the files <tt>this</tt> and
  <tt>string'</tt>. To avoid this use curly braces to tell Tcl that it should
  treat everything enclosed as one value. So our example would become:</p>

<div class="doc_code">
... | grep {find this string}

  <p>Additionally, the characters <tt>[</tt> and <tt>]</tt> are treated 
  specially by Tcl. They tell Tcl to interpret the content as a command to
  execute. Since these characters are often used in regular expressions this can
  have disastrous results and cause the entire test run in a directory to fail.
  For example, a common idiom is to look for some basicblock number:</p>

<div class="doc_code">
... | grep bb[2-8]

  <p>This, however, will cause Tcl to fail because its going to try to execute
  a program named "2-8". Instead, what you want is this:</p>

<div class="doc_code">
... | grep {bb\[2-8\]}

  <p>Finally, if you need to pass the <tt>\</tt> character down to a program,
  then it must be doubled. This is another Tcl special character. So, suppose
  you had:

<div class="doc_code">
... | grep 'i32\*'

  <p>This will fail to match what you want (a pointer to i32). First, the
  <tt>'</tt> do not get stripped off. Second, the <tt>\</tt> gets stripped off
  by Tcl so what grep sees is: <tt>'i32*'</tt>. That's not likely to match
  anything. To resolve this you must use <tt>\\</tt> and the <tt>{}</tt>, like

<div class="doc_code">
... | grep {i32\\*}

<p>If your system includes GNU <tt>grep</tt>, make sure
that <tt>GREP_OPTIONS</tt> is not set in your environment. Otherwise,
you may get invalid results (both false positives and false


<!-- _______________________________________________________________________ -->
<h3><a name="FileCheck">The FileCheck utility</a></h3>
<!-- _______________________________________________________________________ -->


<p>A powerful feature of the RUN: lines is that it allows any arbitrary commands
   to be executed as part of the test harness.  While standard (portable) unix
   tools like 'grep' work fine on run lines, as you see above, there are a lot
   of caveats due to interaction with Tcl syntax, and we want to make sure the
   run lines are portable to a wide range of systems.  Another major problem is
   that grep is not very good at checking to verify that the output of a tools
   contains a series of different output in a specific order.  The FileCheck
   tool was designed to help with these problems.</p>

<p>FileCheck (whose basic command line arguments are described in <a
   href="http://llvm.org/cmds/FileCheck.html">the FileCheck man page</a> is
   designed to read a file to check from standard input, and the set of things
   to verify from a file specified as a command line argument.  A simple example
   of using FileCheck from a RUN line looks like this:</p>
<div class="doc_code">
; RUN: llvm-as &lt; %s | llc -march=x86-64 | <b>FileCheck %s</b>

<p>This syntax says to pipe the current file ("%s") into llvm-as, pipe that into
llc, then pipe the output of llc into FileCheck.  This means that FileCheck will
be verifying its standard input (the llc output) against the filename argument
specified (the original .ll file specified by "%s").  To see how this works,
let's look at the rest of the .ll file (after the RUN line):</p>

<div class="doc_code">
define void @sub1(i32* %p, i32 %v) {
; <b>CHECK: sub1:</b>
; <b>CHECK: subl</b>
        %0 = tail call i32 @llvm.atomic.load.sub.i32.p0i32(i32* %p, i32 %v)
        ret void

define void @inc4(i64* %p) {
; <b>CHECK: inc4:</b>
; <b>CHECK: incq</b>
        %0 = tail call i64 @llvm.atomic.load.add.i64.p0i64(i64* %p, i64 1)
        ret void

<p>Here you can see some "CHECK:" lines specified in comments.  Now you can see
how the file is piped into llvm-as, then llc, and the machine code output is
what we are verifying.  FileCheck checks the machine code output to verify that
it matches what the "CHECK:" lines specify.</p>

<p>The syntax of the CHECK: lines is very simple: they are fixed strings that
must occur in order.  FileCheck defaults to ignoring horizontal whitespace
differences (e.g. a space is allowed to match a tab) but otherwise, the contents
of the CHECK: line is required to match some thing in the test file exactly.</p>

<p>One nice thing about FileCheck (compared to grep) is that it allows merging
test cases together into logical groups.  For example, because the test above
is checking for the "sub1:" and "inc4:" labels, it will not match unless there
is a "subl" in between those labels.  If it existed somewhere else in the file,
that would not count: "grep subl" matches if subl exists anywhere in the

<!-- _______________________________________________________________________ -->
  <a name="FileCheck-check-prefix">The FileCheck -check-prefix option</a>


<p>The FileCheck -check-prefix option allows multiple test configurations to be
driven from one .ll file.  This is useful in many circumstances, for example,
testing different architectural variants with llc.  Here's a simple example:</p>

<div class="doc_code">
; RUN: llvm-as &lt; %s | llc -mtriple=i686-apple-darwin9 -mattr=sse41 \
; RUN:              | <b>FileCheck %s -check-prefix=X32</b>
; RUN: llvm-as &lt; %s | llc -mtriple=x86_64-apple-darwin9 -mattr=sse41 \
; RUN:              | <b>FileCheck %s -check-prefix=X64</b>

define &lt;4 x i32&gt; @pinsrd_1(i32 %s, &lt;4 x i32&gt; %tmp) nounwind {
        %tmp1 = insertelement &lt;4 x i32&gt; %tmp, i32 %s, i32 1
        ret &lt;4 x i32&gt; %tmp1
; <b>X32:</b> pinsrd_1:
; <b>X32:</b>    pinsrd $1, 4(%esp), %xmm0

; <b>X64:</b> pinsrd_1:
; <b>X64:</b>    pinsrd $1, %edi, %xmm0

<p>In this case, we're testing that we get the expected code generation with
both 32-bit and 64-bit code generation.</p>


<!-- _______________________________________________________________________ -->
  <a name="FileCheck-CHECK-NEXT">The "CHECK-NEXT:" directive</a>


<p>Sometimes you want to match lines and would like to verify that matches
happen on exactly consecutive lines with no other lines in between them.  In
this case, you can use CHECK: and CHECK-NEXT: directives to specify this.  If
you specified a custom check prefix, just use "&lt;PREFIX&gt;-NEXT:".  For
example, something like this works as you'd expect:</p>

<div class="doc_code">
define void @t2(&lt;2 x double&gt;* %r, &lt;2 x double&gt;* %A, double %B) {
	%tmp3 = load &lt;2 x double&gt;* %A, align 16
	%tmp7 = insertelement &lt;2 x double&gt; undef, double %B, i32 0
	%tmp9 = shufflevector &lt;2 x double&gt; %tmp3,
                              &lt;2 x double&gt; %tmp7,
                              &lt;2 x i32&gt; &lt; i32 0, i32 2 &gt;
	store &lt;2 x double&gt; %tmp9, &lt;2 x double&gt;* %r, align 16
	ret void
; <b>CHECK:</b> t2:
; <b>CHECK:</b> 	movl	8(%esp), %eax
; <b>CHECK-NEXT:</b> 	movapd	(%eax), %xmm0
; <b>CHECK-NEXT:</b> 	movhpd	12(%esp), %xmm0
; <b>CHECK-NEXT:</b> 	movl	4(%esp), %eax
; <b>CHECK-NEXT:</b> 	movapd	%xmm0, (%eax)
; <b>CHECK-NEXT:</b> 	ret

<p>CHECK-NEXT: directives reject the input unless there is exactly one newline
between it an the previous directive.  A CHECK-NEXT cannot be the first
directive in a file.</p>


<!-- _______________________________________________________________________ -->
  <a name="FileCheck-CHECK-NOT">The "CHECK-NOT:" directive</a>


<p>The CHECK-NOT: directive is used to verify that a string doesn't occur
between two matches (or the first match and the beginning of the file).  For
example, to verify that a load is removed by a transformation, a test like this
can be used:</p>

<div class="doc_code">
define i8 @coerce_offset0(i32 %V, i32* %P) {
  store i32 %V, i32* %P
  %P2 = bitcast i32* %P to i8*
  %P3 = getelementptr i8* %P2, i32 2

  %A = load i8* %P3
  ret i8 %A
; <b>CHECK:</b> @coerce_offset0
; <b>CHECK-NOT:</b> load
; <b>CHECK:</b> ret i8


<!-- _______________________________________________________________________ -->
  <a name="FileCheck-Matching">FileCheck Pattern Matching Syntax</a>


<p>The CHECK: and CHECK-NOT: directives both take a pattern to match.  For most
uses of FileCheck, fixed string matching is perfectly sufficient.  For some
things, a more flexible form of matching is desired.  To support this, FileCheck
allows you to specify regular expressions in matching strings, surrounded by
double braces: <b>{{yourregex}}</b>.  Because we want to use fixed string
matching for a majority of what we do, FileCheck has been designed to support
mixing and matching fixed string matching with regular expressions.  This allows
you to write things like this:</p>

<div class="doc_code">
; CHECK: movhpd	<b>{{[0-9]+}}</b>(%esp), <b>{{%xmm[0-7]}}</b>

<p>In this case, any offset from the ESP register will be allowed, and any xmm
register will be allowed.</p>

<p>Because regular expressions are enclosed with double braces, they are
visually distinct, and you don't need to use escape characters within the double
braces like you would in C.  In the rare case that you want to match double
braces explicitly from the input, you can use something ugly like
<b>{{[{][{]}}</b> as your pattern.</p>


<!-- _______________________________________________________________________ -->
  <a name="FileCheck-Variables">FileCheck Variables</a>


<p>It is often useful to match a pattern and then verify that it occurs again
later in the file.  For codegen tests, this can be useful to allow any register,
but verify that that register is used consistently later.  To do this, FileCheck
allows named variables to be defined and substituted into patterns.  Here is a
simple example:</p>

<div class="doc_code">
; CHECK: test5:
; CHECK:    notw	<b>[[REGISTER:%[a-z]+]]</b>
; CHECK:    andw	{{.*}}<b>[[REGISTER]]</b>

<p>The first check line matches a regex (<tt>%[a-z]+</tt>) and captures it into
the variables "REGISTER".  The second line verifies that whatever is in REGISTER
occurs later in the file after an "andw".  FileCheck variable references are
always contained in <tt>[[ ]]</tt> pairs, are named, and their names can be
formed with the regex "<tt>[a-zA-Z][a-zA-Z0-9]*</tt>".  If a colon follows the
name, then it is a definition of the variable, if not, it is a use.</p>

<p>FileCheck variables can be defined multiple times, and uses always get the
latest value.  Note that variables are all read at the start of a "CHECK" line
and are all defined at the end.  This means that if you have something like
"<tt>CHECK: [[XYZ:.*]]x[[XYZ]]</tt>" that the check line will read the previous
value of the XYZ variable and define a new one after the match is performed.  If
you need to do something like this you can probably take advantage of the fact
that FileCheck is not actually line-oriented when it matches, this allows you to
define two separate CHECK lines that match on the same line.



<!-- _______________________________________________________________________ -->
<h3><a name="rtvars">Variables and substitutions</a></h3>
<!-- _______________________________________________________________________ -->
  <p>With a RUN line there are a number of substitutions that are permitted. In
  general, any Tcl variable that is available in the <tt>substitute</tt> 
  function (in <tt>test/lib/llvm.exp</tt>) can be substituted into a RUN line.
  To make a substitution just write the variable's name preceded by a $. 
  Additionally, for compatibility reasons with previous versions of the test
  library, certain names can be accessed with an alternate syntax: a % prefix.
  These alternates are deprecated and may go away in a future version.
  <p>Here are the available variable names. The alternate syntax is listed in

  <dl style="margin-left: 25px">
    <dt><b>$test</b> (%s)</dt>
    <dd>The full path to the test case's source. This is suitable for passing
    on the command line as the input to an llvm tool.</dd>

    <dd>The source directory from where the "<tt>make check</tt>" was run.</dd>

    <dd>The object directory that corresponds to the <tt>$srcdir</tt>.</dd>

    <dd>A partial path from the <tt>test</tt> directory that contains the 
    sub-directory that contains the test source being executed.</dd>

    <dd>The root directory of the LLVM src tree.</dd>

    <dd>The root directory of the LLVM object tree. This could be the same
    as the srcroot.</dd>

    <dd>The path to the directory that contains the test case source.  This is 
    for locating any supporting files that are not generated by the test, but 
    used by the test.</dd>

    <dd>The path to a temporary file name that could be used for this test case.
    The file name won't conflict with other test cases. You can append to it if
    you need multiple temporaries. This is useful as the destination of some
    redirected output.</dd>

    <dt><b>target_triplet</b> (%target_triplet)</dt>
    <dd>The target triplet that corresponds to the current host machine (the one
    running the test cases). This should probably be called "host".<dd>

    <dt><b>link</b> (%link)</dt> 
    <dd>This full link command used to link LLVM executables. This has all the
    configured -I, -L and -l options.</dd>

    <dt><b>shlibext</b> (%shlibext)</dt>
    <dd>The suffix for the host platforms share library (dll) files. This
    includes the period as the first character.</dd>
  <p>To add more variables, two things need to be changed. First, add a line in
  the <tt>test/Makefile</tt> that creates the <tt>site.exp</tt> file. This will
  "set" the variable as a global in the site.exp file. Second, in the
  <tt>test/lib/llvm.exp</tt> file, in the substitute proc, add the variable name
  to the list of "global" declarations at the beginning of the proc. That's it,
  the variable can then be used in test scripts.</p>
<!-- _______________________________________________________________________ -->
<h3><a name="rtfeatures">Other Features</a></h3>
<!-- _______________________________________________________________________ -->
  <p>To make RUN line writing easier, there are several shell scripts located
  in the <tt>llvm/test/Scripts</tt> directory. This directory is in the PATH
  when running tests, so you can just call these scripts using their name. For
    <dd>This script runs its arguments and then always returns 0. This is useful
    in cases where the test needs to cause a tool to generate an error (e.g. to
    check the error output). However, any program in a pipeline that returns a
    non-zero result will cause the test to fail. This script overcomes that 
    issue and nicely documents that the test case is purposefully ignoring the
    result code of the tool</dd>

    <dd>This script runs its arguments and then inverts the result code from 
    it. Zero result codes become 1. Non-zero result codes become 0. This is
    useful to invert the result of a grep. For example "not grep X" means
    succeed only if you don't find X in the input.</dd>

  <p>Sometimes it is necessary to mark a test case as "expected fail" or XFAIL.
  You can easily mark a test as XFAIL just by including <tt>XFAIL: </tt> on a
  line near the top of the file. This signals that the test case should succeed
  if the test fails. Such test cases are counted separately by the testing tool. To
  specify an expected fail, use the XFAIL keyword in the comments of the test
  program followed by a colon and one or more regular expressions (separated by
  a comma). The regular expressions allow you to XFAIL the test conditionally by
  host platform. The regular expressions following the : are matched against the
  target triplet for the host machine. If there is a match, the test is expected
  to fail. If not, the test is expected to succeed. To XFAIL everywhere just
  specify <tt>XFAIL: *</tt>. Here is an example of an <tt>XFAIL</tt> line:</p>

<div class="doc_code">
; XFAIL: darwin,sun

  <p>To make the output more useful, the <tt>llvm_runtest</tt> function wil
  scan the lines of the test case for ones that contain a pattern that matches
  PR[0-9]+. This is the syntax for specifying a PR (Problem Report) number that
  is related to the test case. The number after "PR" specifies the LLVM bugzilla
  number. When a PR number is specified, it will be used in the pass/fail
  reporting. This is useful to quickly get some context when a test fails.</p>

  <p>Finally, any line that contains "END." will cause the special
  interpretation of lines to terminate. This is generally done right after the
  last RUN: line. This has two side effects: (a) it prevents special
  interpretation of lines that are part of the test program, not the
  instructions to the test case, and (b) it speeds things up for really big test
  cases by avoiding interpretation of the remainder of the file.</p>



<h2><a name="testsuiteoverview"><tt>test-suite</tt> Overview</a></h2>


<p>The <tt>test-suite</tt> module contains a number of programs that can be
compiled and executed. The <tt>test-suite</tt> includes reference outputs for
all of the programs, so that the output of the executed program can be checked
for correctness.</p>

<p><tt>test-suite</tt> tests are divided into three types of tests: MultiSource,
SingleSource, and External.</p> 

<p>The SingleSource directory contains test programs that are only a single 
source file in size.  These are usually small benchmark programs or small 
programs that calculate a particular value.  Several such programs are grouped 
together in each directory.</p></li>

<p>The MultiSource directory contains subdirectories which contain entire 
programs with multiple source files.  Large benchmarks and whole applications 
go here.</p></li>

<p>The External directory contains Makefiles for building code that is external
to (i.e., not distributed with) LLVM.  The most prominent members of this
directory are the SPEC 95 and SPEC 2000 benchmark suites. The <tt>External</tt>
directory does not contain these actual tests, but only the Makefiles that know
how to properly compile these programs from somewhere else. When
using <tt>LNT</tt>, use the <tt>--test-externals</tt> option to include these
tests in the results.</p></li>

<h2><a name="testsuitequickstart"><tt>test-suite</tt> Quickstart</a></h2>

<p>The modern way of running the <tt>test-suite</tt> is focused on testing and
benchmarking complete compilers using
the <a href="http://llvm.org/docs/lnt">LNT</a> testing infrastructure.</p>

<p>For more information on using LNT to execute the <tt>test-suite</tt>, please
see the <a href="http://llvm.org/docs/lnt/quickstart.html">LNT Quickstart</a>

<h2><a name="testsuitemakefiles"><tt>test-suite</tt> Makefiles</a></h2>

<p>Historically, the <tt>test-suite</tt> was executed using a complicated setup
of Makefiles. The LNT based approach above is recommended for most users, but
there are some testing scenarios which are not supported by the LNT approach. In
addition, LNT currently uses the Makefile setup under the covers and so
developers who are interested in how LNT works under the hood may want to
understand the Makefile based setup.</p>

<p>For more information on the <tt>test-suite</tt> Makefile setup, please see
the <a href="TestSuiteMakefileGuide.html">Test Suite Makefile Guide.</a></p>

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