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/Features`

  This directory contains sample codes that test various features of the LLVM language. These pieces of sample code are run through various assembler, disassembler, and optimizer passes.

- `llvm/test/Regression`

  This directory contains regression tests for LLVM. 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. This file is a program written in tcl that calls the `llvm-runtests` procedure on each test file. The llvm-runtests procedure is defined in `llvm/test/lib/llvm-dg.exp`. Any directory that contains only directories does not need the `dg.exp` file.

In order for a test to be run, it must contain information within the test file on how to run the test. These are called `RUN` lines. Run lines are specified in the comments of the test program using the keyword `RUN` followed by a colon, and lastly the commands to execute. These commands will be executed in a bash script, so any bash syntax is acceptable. You can specify as many RUN lines as necessary. Each RUN line translates to one line in the resulting bash script. 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

There are a couple patterns within a `RUN` line that the llvm-runtest procedure looks for and replaces with the appropriate syntax:

%p
  The path to the source directory. This is for locating any supporting files that are not generated by the test, but used by the test.
%s
  The test file.
%t
  Temporary filename: testscript.test_filename.tmp, where test_filename is the name of the test file. All temporary files are placed in the Output directory within the directory the test is located.
%prcontext
  Path to a script that performs grep -C. Use this since not all platforms support grep -C.
%llvmgcc
  Full path to the llvm-gcc executable.
%llvmgxx
  Full path to the llvm-g++ executable.

There are also several scripts in the llvm/test/Scripts directory that you might find useful when writing `RUN` lines.

Lastly, you can easily mark a test that is expected to fail on a specific platform or with a specific version of llvmgcc by using the `XFAIL` keyword. Xfail lines are specified in the comments of the test program using `XFAIL`, followed by a colon, and one or more regular expressions (separated by a comma) that will match against the target triplet or llvmgcc version for the machine. You can use * to match all targets. You can specify the major or full version (i.e. 3.4) for llvmgcc. Here is an example of an `XFAIL` line:

    ; XFAIL: darwin,sun,llvmgcc4

`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!