LLVM test-suite Guide¶

Overview
Test suite Structure
Running the test suite via CMake
Running the test suite via Makefiles (deprecated)

Overview ¶

This document describes the features of the Makefile-based LLVM test-suite as well as the cmake based replacement. This way of interacting with the test-suite is deprecated in favor of running the test-suite using LNT, but may continue to prove useful for some users. See the Testing Guide’s test-suite Quickstart section for more information.

Test suite Structure ¶

The test-suite module contains a number of 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.

When executing tests, it is usually a good idea to start out with a subset of the available tests or programs. This makes test run times smaller at first and later on this is useful to investigate individual test failures. To run some test only on a subset of programs, simply change directory to the programs you want tested and run gmake there. Alternatively, you can run a different test using the TEST variable to change what tests or run on the selected programs (see below for more info).

In addition for testing correctness, the test-suite 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.

test-suite tests are divided into three types of tests: MultiSource, SingleSource, and External.

test-suite/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.
test-suite/MultiSource

The MultiSource directory contains subdirectories which contain entire programs with multiple source files. Large benchmarks and whole applications go here.
test-suite/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 External directory does not contain these actual tests, but only the Makefiles that know how to properly compile these programs from somewhere else. The presence and location of these external programs is configured by the test-suite configure script.

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.

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 the regression tests, 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 the test suite 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.

Running the test suite via CMake ¶

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

The test suite uses the lit test runner to run the test-suite, you need to have lit installed first. Check out LLVM and install lit:

% svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm
% cd llvm/utils/lit
% sudo python setup.py install # Or without sudo, install in virtual-env.
running install
running bdist_egg
running egg_info
writing lit.egg-info/PKG-INFO
...
% lit --version
lit 0.5.0dev

Check out the test-suite module with:

% svn co http://llvm.org/svn/llvm-project/test-suite/trunk test-suite

Use CMake to configure the test suite in a new directory. You cannot build the test suite in the source tree.
```
% mkdir test-suite-build
% cd test-suite-build
% cmake ../test-suite
```
Build the benchmarks, using the makefiles CMake generated.

% make
Scanning dependencies of target timeit-target
[  0%] Building C object tools/CMakeFiles/timeit-target.dir/timeit.c.o
[  0%] Linking C executable timeit-target
[  0%] Built target timeit-target
Scanning dependencies of target fpcmp-host
[  0%] [TEST_SUITE_HOST_CC] Building host executable fpcmp
[  0%] Built target fpcmp-host
Scanning dependencies of target timeit-host
[  0%] [TEST_SUITE_HOST_CC] Building host executable timeit
[  0%] Built target timeit-host

Run the tests with lit:

% lit -v -j 1 . -o results.json
-- Testing: 474 tests, 1 threads --
PASS: test-suite :: MultiSource/Applications/ALAC/decode/alacconvert-decode.test (1 of 474)
********** TEST 'test-suite :: MultiSource/Applications/ALAC/decode/alacconvert-decode.test' RESULTS **********
compile_time: 0.2192
exec_time: 0.0462
hash: "59620e187c6ac38b36382685ccd2b63b"
size: 83348
**********
PASS: test-suite :: MultiSource/Applications/ALAC/encode/alacconvert-encode.test (2 of 474)

Running the test suite via Makefiles (deprecated)¶

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.

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

cd into the llvm/projects directory in your source tree.
Check out the test-suite module with:
```
% svn co http://llvm.org/svn/llvm-project/test-suite/trunk test-suite
```
This will get the test suite into llvm/projects/test-suite.
Configure and build llvm.
Configure and build llvm-gcc.
Install llvm-gcc somewhere.
Re-configure llvm from the top level of each build tree (LLVM object directory tree) in which you want to run the test suite, just as you do before building LLVM.

During the re-configuration, you must either: (1) have llvm-gcc you just built in your path, or (2) specify the directory where your just-built llvm-gcc is installed using --with-llvmgccdir=$LLVM_GCC_DIR.

You must also tell the configure machinery that the test suite is available so it can be configured for your build tree:
```
% cd $LLVM_OBJ_ROOT ; $LLVM_SRC_ROOT/configure [--with-llvmgccdir=$LLVM_GCC_DIR]
```
[Remember that $LLVM_GCC_DIR is the directory where you installed llvm-gcc, not its src or obj directory.]
You can now run the test suite from your build tree as follows:
```
% cd $LLVM_OBJ_ROOT/projects/test-suite
% make
```

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).

Configuring External Tests ¶

In order to run the External tests in the test-suite module, you must specify –with-externals. This must be done during the re-configuration step (see above), and the llvm re-configuration must recognize the previously-built llvm-gcc. If any of these is missing or neglected, the External tests won’t work.

–with-externals
–with-externals=<directory>

This tells LLVM where to find any external tests. They are expected to be in specifically named subdirectories of <directory>. If directory is left unspecified, configure uses the default value /home/vadve/shared/benchmarks/speccpu2000/benchspec. Subdirectory names known to LLVM include:

spec95
speccpu2000
speccpu2006
povray31

Others are added from time to time, and can be determined from configure.

Running different tests ¶

In addition to the regular “whole program” tests, the test-suite 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.

Generating test output ¶

There are a number of ways to run the tests and generate output. The most simple one is simply running gmake with no arguments. This will compile and run all programs in the tree using a number of different methods and compare results. Any failures are reported in the output, but are likely drowned in the other output. Passes are not reported explicitly.

Somewhat better is running gmake TEST=sometest test, which runs the specified test and usually adds per-program summaries to the output (depending on which sometest you use). For example, the nightly test explicitly outputs TEST-PASS or TEST-FAIL for every test after each program. Though these lines are still drowned in the output, it’s easy to grep the output logs in the Output directories.

Even better are the report and report.format targets (where format is one of html, csv, text or graphs). The exact contents of the report are dependent on which TEST you are running, but the text results are always shown at the end of the run and the results are always stored in the report.<type>.format file (when running with TEST=<type>). The report also generate a file called report.<type>.raw.out containing the output of the entire test run.

Writing custom tests for the test suite ¶

Assuming you can run the test suite, (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, a “test-suite/TEST.XXX.Makefile” fragment (where XXX is the name of your test) and a “test-suite/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 the test suite, 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/test-suite/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 test-suite/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.