LLVM Test Suite Guide

1. Overview
2. Requirements
3. Quick Start
4. LLVM Test Suite Organization
   - Code Fragments
   - Whole Programs
5. LLVM Test Suite Tree
6. DejaGNU Structure
7. `llvm-test` Structure
8. Running the LLVM Tests
   - Writing custom tests for llvm-test
9. Running the nightly tester

Written by John T. Criswell, Reid Spencer, and Tanya Lattner

Overview

This document is the reference manual for the LLVM test suite. It documents the structure of the LLVM test suite, the tools needed to use it, and how to add and run tests.

Requirements

In order to use the LLVM test suite, you will need all of the software required to build LLVM, plus the following:

DejaGNU
  The Feature and Regressions tests are organized and run by DejaGNU.
Expect
  Expect is required by DejaGNU.
tcl
  Tcl is required by DejaGNU.
F2C
  For now, LLVM does not have a Fortran front-end, but using F2C, we can run Fortran benchmarks. F2C support must be enabled via `configure` if not installed in a standard place. F2C requires three items: the `f2c` executable, `f2c.h` to compile the generated code, and `libf2c.a` to link generated code. By default, given an F2C directory `$DIR`, the configure script will search `$DIR/bin` for `f2c`, `$DIR/include` for `f2c.h`, and `$DIR/lib` for `libf2c.a`. The default `$DIR` values are: `/usr`, `/usr/local`, `/sw`, and `/opt`. If you installed F2C in a different location, you must tell `configure`:
  - `./configure --with-f2c=$DIR`
    This will specify a new `$DIR` for the above-described search process. This will only work if the binary, header, and library are in their respective subdirectories of `$DIR`.
  - `./configure --with-f2c-bin=/binary/path --with-f2c-inc=/include/path --with-f2c-lib=/lib/path`
    This allows you to specify the F2C components separately. Note: if you choose this route, you MUST specify all three components, and you need to only specify directories where the files are located; do NOT include the filenames themselves on the `configure` line.

Darwin (Mac OS X) developers can simplify the installation of Expect and tcl by using fink. `fink install expect` will install both. Alternatively, Darwinports users can use `sudo port install expect` to install Expect and tcl.

Quick Start

The tests are located in two separate CVS modules. The basic feature and regression tests are in the main "llvm" module under the directory `llvm/test`. A more comprehensive test suite that includes whole programs in C and C++ is in the `llvm-test` module. This module should be checked out to the `llvm/projects` directory. When you `configure` the `llvm` module, the `llvm-test` module will be automatically configured. Alternatively, you can configure the `llvm-test` module manually.

To run all of the simple tests in LLVM using DejaGNU, use the master Makefile in the `llvm/test` directory:

    % gmake -C llvm/test

or

    % gmake check

To run only a subdirectory of tests in llvm/test using DejaGNU (ie. Regression/Transforms), just set the TESTSUITE variable to the path of the subdirectory (relative to `llvm/test`):

    % gmake -C llvm/test TESTSUITE=Regression/Transforms

Note: If you are running the tests with `objdir != subdir`, you must have run the complete testsuite before you can specify a subdirectory.

To run the comprehensive test suite (tests that compile and execute whole programs), run the `llvm-test` tests:

    % cd llvm/projects
    % cvs co llvm-test
    % cd llvm-test
    % ./configure --with-llvmsrc=$LLVM_SRC_ROOT --with-llvmobj=$LLVM_OBJ_ROOT
    % gmake

LLVM Test Suite Organization

The LLVM test suite contains two major categories of tests: code fragments and whole programs. Code fragments are in the `llvm` module under the `llvm/test` directory. The whole programs test suite is in the `llvm-test` module under the main directory.

Code Fragments

Code fragments 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.

Code fragments are not complete programs, and they are never executed to determine correct behavior.

These code fragment tests are located in the `llvm/test/Features` and `llvm/test/Regression` directories.

Whole Programs

Whole Programs 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++, but sometimes they are written straight in LLVM assembly.

These programs are compiled and then executed using several different methods (native compiler, LLVM C backend, LLVM JIT, LLVM native code generation, etc). The output of these programs is compared to ensure that LLVM is compiling the program correctly.

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.

All "whole program" tests are located in the `llvm-test` CVS module.

LLVM Test Suite Tree

Each type of test in the LLVM test suite has its own directory. The major subtrees of the test suite directory tree are as follows:

- `llvm/test`

  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:

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

  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.

- `llvm-test`

  The `llvm-test` CVS module contains programs that can be compiled with LLVM and executed. These programs are compiled using the native compiler and various LLVM backends. The output from the program compiled with the native compiler is assumed correct; the results from the other programs are compared to the native program output and pass if they match.

  In addition for testing correctness, the `llvm-test` directory also performs timing tests of various LLVM optimizations. It also records compilation times for the compilers and the JIT. This information can be used to compare the effectiveness of LLVM's optimizations and code generation.

- `llvm-test/SingleSource`

  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.

- `llvm-test/MultiSource`

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

- `llvm-test/External`

  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 presence and location of these external programs is configured by the llvm-test `configure` script.

DejaGNU Structure

The LLVM test suite is partially driven by DejaGNU and partially driven by GNU Make. Specifically, the Features and Regression tests are all driven by DejaGNU. The `llvm-test` module is currently driven by a set of Makefiles.

The DejaGNU structure is very simple, but does require some information to be set. This information is gathered via `configure` and is written to a file, `site.exp` in `llvm/test`. The `llvm/test` Makefile does this work for you.

In order for DejaGNU to work, each directory of tests must have a `dg.exp` file. DejaGNU looks for this file to determine how to run the tests. This file is just a Tcl script and it can do anything you want, but we've standardized it for the LLVM regression tests. It simply loads a Tcl library (`test/lib/llvm.exp`) and calls the `llvm_runtests` function defined in that library with a list of file names to run. The names are obtained by using Tcl's glob command. Any directory that contains only directories does not need the `dg.exp` file.

The `llvm-runtests` function lookas at each file that is passed to it and gathers any lines together that match "RUN:". This 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 `llvm-runtests` function will issue an error and the test will fail.

RUN lines are specified in the comments of the test program using the keyword `RUN` followed by a colon, and lastly the command (pipeline) to execute. Together, these lines form the "script" that `llvm-runtests` 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 look like a shell script, they are not. RUN lines are interpreted directly by the Tcl `exec` 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.

Each RUN line is executed on its own, distinct from other lines unless its last character is `\`. 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 `\` are concatenated until a RUN line that doesn't end in `\` is found. This concatenated set or 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.

Below is an example of legal RUN lines in a `.ll` file:

      ; RUN: llvm-as < %s | llvm-dis > %t1
      ; RUN: llvm-dis < %s.bc-13 > %t2
      ; RUN: diff %t1 %t2

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 Tcl exec command and the tutorial. The major differences are:

- You can't do `2>&1`. That will cause Tcl to write to a file named `&1`. Usually this is done to get stderr to go through a pipe. You can do that in tcl with `|&` so replace this idiom: `... 2>&1 | grep` with `... |& grep`
- You can only redirect to a file, not to another descriptor and not from a here document.
- tcl supports redirecting to open files with the @ syntax but you shouldn't use that here.

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 ' or " so they will get passed to the invoked program. For example:

         ... | grep 'find this string'

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

         ... | grep {find this string}

Additionally, the characters `[` and `]` 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:

         ... | grep bb[2-8]

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:

         ... | grep {bb\[2-8\]}

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

         ... | grep 'i32\*'

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

         ... | grep {i32\\*}

Vars And Substitutions

With a RUN line there are a number of substitutions that are permitted. In general, any Tcl variable that is available in the `substitute` function (in `test/lib/llvm.exp`) 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.

Here are the available variable names. The alternate syntax is listed in parentheses.

$test (%s)
  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.
$srcdir
  The source directory from where the "`make check`" was run.
objdir
  The object directory that corresponds to the $srcdir.
subdir
  A partial path from the `test` directory that contains the sub-directory that contains the test source being executed.
srcroot
  The root directory of the LLVM src tree.
objroot
  The root directory of the LLVM object tree. This could be the same as the srcroot.
path
  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.
tmp
  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.
llvmlibsdir (%llvmlibsdir)
  The directory where the LLVM libraries are located.
target_triplet (%target_triplet)
  The target triplet that corresponds to the current host machine (the one running the test cases). This should probably be called "host".
prcontext (%prcontext)
  Path to the prcontext tcl script that prints some context around a line that matches a pattern. This isn't strictly necessary as the test suite is run with its PATH altered to include the test/Scripts directory where the prcontext script is located. Note that this script is similar to `grep -C` but you should use the `prcontext` script because not all platforms support `grep -C`.
llvmgcc (%llvmgcc)
  The full path to the `llvm-gcc` executable as specified in the configured LLVM environment
llvmgxx (%llvmgxx)
  The full path to the `llvm-gxx` executable as specified in the configured LLVM environment
llvmgcc_version (%llvmgcc_version)
  The full version number of the `llvm-gcc` executable.
llvmgccmajvers (%llvmgccmajvers)
  The major version number of the `llvm-gcc` executable.
gccpath
  The full path to the C compiler used to build LLVM. Note that this might not be gcc.
gxxpath
  The full path to the C++ compiler used to build LLVM. Note that this might not be g++.
compile_c (%compile_c)
  The full command line used to compile LLVM C source code. This has all the configured -I, -D and optimization options.
compile_cxx (%compile_cxx)
  The full command used to compile LLVM C++ source code. This has all the configured -I, -D and optimization options.
link (%link)
  This full link command used to link LLVM executables. This has all the configured -I, -L and -l options.
shlibext (%shlibext)
  The suffix for the host platforms share library (dll) files. This includes the period as the first character.

To add more variables, two things need to be changed. First, add a line in the `test/Makefile` that creates the `site.exp` file. This will "set" the variable as a global in the site.exp file. Second, in the `test/lib/llvm.exp` 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.

Other Features

To make RUN line writing easier, there are several shell scripts located in the `llvm/test/Scripts` directory. For example:

ignore
  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
not
  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.

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 `XFAIL:` 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 DejaGnu. 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 or llvmgcc version number 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 `XFAIL: *`. When matching the llvm-gcc version, you can specify the major (e.g. 3) or full version (i.e. 3.4) number. Here is an example of an `XFAIL` line:

       ; XFAIL: darwin,sun,llvmgcc4

To make the output more useful, the `llvm_runtest` 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 numer 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.

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.

`llvm-test` Structure

As mentioned previously, the `llvm-test` module provides three types of tests: MultiSource, SingleSource, and External. Each tree is then subdivided into several categories, including applications, benchmarks, regression tests, code that is strange grammatically, etc. These organizations should be relatively self explanatory.

In addition to the regular "whole program" tests, the `llvm-test` module also provides a mechanism for compiling the programs in different ways. If the variable TEST is defined on the gmake command line, the test system will include a Makefile named `TEST.<value of TEST variable>.Makefile`. This Makefile can modify build rules to yield different results.

For example, the LLVM nightly tester uses `TEST.nightly.Makefile` to create the nightly test reports. To run the nightly tests, run `gmake TEST=nightly`.

There are several TEST Makefiles available in the tree. Some of them are designed for internal LLVM research and will not work outside of the LLVM research group. They may still be valuable, however, as a guide to writing your own TEST Makefile for any optimization or analysis passes that you develop with LLVM.

Note, when configuring the `llvm-test` module, you might want to specify the following configuration options:

--enable-spec2000
--enable-spec2000=<`directory`>
  Enable the use of SPEC2000 when testing LLVM. This is disabled by default (unless `configure` finds SPEC2000 installed). By specifying `directory`, you can tell configure where to find the SPEC2000 benchmarks. If `directory` is left unspecified, `configure` uses the default value `/home/vadve/shared/benchmarks/speccpu2000/benchspec`.

--enable-spec95
--enable-spec95=<`directory`>
  Enable the use of SPEC95 when testing LLVM. It is similar to the --enable-spec2000 option.

--enable-povray
--enable-povray=<`directory`>
  Enable the use of Povray as an external test. Versions of Povray written in C should work. This option is similar to the --enable-spec2000 option.

Running the LLVM Tests

First, all tests are executed within the LLVM object directory tree. They are not executed inside of the LLVM source tree. This is because the test suite creates temporary files during execution.

The master Makefile in llvm/test is capable of running only the DejaGNU driven tests. By default, it will run all of these tests.

To run only the DejaGNU driven tests, run `gmake` at the command line in `llvm/test`. To run a specific directory of tests, use the TESTSUITE variable.

For example, to run the Regression tests, type `gmake TESTSUITE=Regression` in `llvm/tests`.

Note that there are no Makefiles in `llvm/test/Features` and `llvm/test/Regression`. You must use DejaGNU from the `llvm/test` directory to run them.

To run the `llvm-test` suite, you need to use the following steps:

1. cd into the llvm/projects directory
2. check out the `llvm-test` module with:
   `cvs -d :pserver:anon@llvm.org:/var/cvs/llvm co -PR llvm-test`
   This will get the test suite into `llvm/projects/llvm-test`
3. configure the test suite. You can do this one of two ways:
   1. Use the regular llvm configure:
      `cd $LLVM_OBJ_ROOT ; $LLVM_SRC_ROOT/configure`
      This will ensure that the `projects/llvm-test` directory is also properly configured.
   2. Use the `configure` script found in the `llvm-test` source directory:
      `$LLVM_SRC_ROOT/projects/llvm-test/configure --with-llvmsrc=$LLVM_SRC_ROOT --with-llvmobj=$LLVM_OBJ_ROOT`
4. gmake

Note that the second and third steps only need to be done once. After you have the suite checked out and configured, you don't need to do it again (unless the test code or configure script changes).

To make a specialized test (use one of the `llvm-test/TEST.<type>.Makefile`s), just run:
`gmake TEST=<type> test`
For example, you could run the nightly tester tests using the following commands:

     % cd llvm/projects/llvm-test
     % gmake TEST=nightly test

Regardless of which test you're running, the results are printed on standard output and standard error. You can redirect these results to a file if you choose.

Some tests are known to fail. Some are bugs that we have not fixed yet; others are features that we haven't added yet (or may never add). In DejaGNU, the result for such tests will be XFAIL (eXpected FAILure). In this way, you can tell the difference between an expected and unexpected failure.

The tests in `llvm-test` have no such feature at this time. If the test passes, only warnings and other miscellaneous output will be generated. If a test fails, a large <program> FAILED message will be displayed. This will help you separate benign warnings from actual test failures.

Writing custom tests for llvm-test

Assuming you can run llvm-test, (e.g. "`gmake TEST=nightly report`" should work), it is really easy to run optimizations or code generator components against every program in the tree, collecting statistics or running custom checks for correctness. At base, this is how the nightly tester works, it's just one example of a general framework.

Lets say that you have an LLVM optimization pass, and you want to see how many times it triggers. First thing you should do is add an LLVM statistic to your pass, which will tally counts of things you care about.

Following this, you can set up a test and a report that collects these and formats them for easy viewing. This consists of two files, an "`llvm-test/TEST.XXX.Makefile`" fragment (where XXX is the name of your test) and an "`llvm-test/TEST.XXX.report`" file that indicates how to format the output into a table. There are many example reports of various levels of sophistication included with llvm-test, and the framework is very general.

If you are interested in testing an optimization pass, check out the "libcalls" test as an example. It can be run like this:

    % cd llvm/projects/llvm-test/MultiSource/Benchmarks  # or some other level
    % make TEST=libcalls report

This will do a bunch of stuff, then eventually print a table like this:

    Name                                  | total | #exit |
    ...
    FreeBench/analyzer/analyzer           | 51    | 6     |
    FreeBench/fourinarow/fourinarow       | 1     | 1     |
    FreeBench/neural/neural               | 19    | 9     |
    FreeBench/pifft/pifft                 | 5     | 3     |
    MallocBench/cfrac/cfrac               | 1     | *     |
    MallocBench/espresso/espresso         | 52    | 12    |
    MallocBench/gs/gs                     | 4     | *     |
    Prolangs-C/TimberWolfMC/timberwolfmc  | 302   | *     |
    Prolangs-C/agrep/agrep                | 33    | 12    |
    Prolangs-C/allroots/allroots          | *     | *     |
    Prolangs-C/assembler/assembler        | 47    | *     |
    Prolangs-C/bison/mybison              | 74    | *     |
    ...

This basically is grepping the -stats output and displaying it in a table. You can also use the "TEST=libcalls report.html" target to get the table in HTML form, similarly for report.csv and report.tex.

The source for this is in llvm-test/TEST.libcalls.*. The format is pretty simple: the Makefile indicates how to run the test (in this case, "`opt -simplify-libcalls -stats`"), and the report contains one line for each column of the output. The first value is the header for the column and the second is the regex to grep the output of the command for. There are lots of example reports that can do fancy stuff.

Running the nightly tester

The LLVM Nightly Testers automatically check out an LLVM tree, build it, run the "nightly" program test (described above), run all of the feature and regression tests, delete the checked out tree, and then submit the results to http://llvm.org/nightlytest/. After test results are submitted to http://llvm.org/nightlytest/, they are processed and displayed on the tests page. An email to llvm-testresults@cs.uiuc.edu summarizing the results is also generated. This testing scheme is designed to ensure that programs don't break as well as keep track of LLVM's progress over time.

If you'd like to set up an instance of the nightly tester to run on your machine, take a look at the comments at the top of the `utils/NewNightlyTest.pl` file. If you decide to set up a nightly tester please choose a unique nickname and invoke `utils/NewNightlyTest.pl` with the "-nickname [yournickname]" command line option. We usually run it from a crontab entry that looks like this:

    5 3 * * *  $HOME/llvm/utils/NewNightlyTest.pl -parallel -nickname Nickname \
               $CVSROOT $HOME/buildtest $HOME/cvs/testresults

Or, you can create a shell script to encapsulate the running of the script. The optimized x86 Linux nightly test is run from just such a script:

    #!/bin/bash
    BASE=/proj/work/llvm/nightlytest
    export CVSROOT=:pserver:anon@llvm.org:/var/cvs/llvm
    export BUILDDIR=$BASE/build
    export WEBDIR=$BASE/testresults
    export LLVMGCCDIR=/proj/work/llvm/cfrontend/install
    export PATH=/proj/install/bin:$LLVMGCCDIR/bin:$PATH
    export LD_LIBRARY_PATH=/proj/install/lib
    cd $BASE
    cp /proj/work/llvm/llvm/utils/NewNightlyTest.pl .
    nice ./NewNightlyTest.pl -nice -release -verbose -parallel -enable-linscan \
       -nickname NightlyTester -noexternals 2>&1 > output.log

It is also possible to specify the the location your nightly test results are submitted. You can do this by passing the command line option "-submit-server [server_address]" and "-submit-script [script_on_server]" to `utils/NewNightlyTest.pl`. For example, to submit to the llvm.org nightly test results page, you would invoke the nightly test script with "-submit-server llvm.org -submit-script /nightlytest/NightlyTestAccept.cgi". If these options are not specified, the nightly test script sends the results to the llvm.org nightly test results page.

Take a look at the `NewNightlyTest.pl` file to see what all of the flags and strings do. If you start running the nightly tests, please let us know. Thanks!