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=================================
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LLVM Testing Infrastructure Guide
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=================================
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Written by John T. Criswell, Daniel Dunbar, Reid Spencer, and Tanya
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Lattner
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.. contents::
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:local:
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.. toctree::
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:hidden:
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TestSuiteMakefileGuide
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Overview
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========
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This document is the reference manual for the LLVM testing
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infrastructure. It documents the structure of the LLVM testing
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infrastructure, the tools needed to use it, and how to add and run
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tests.
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Requirements
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============
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In order to use the LLVM testing infrastructure, you will need all of
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the software required to build LLVM, as well as
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`Python <http://python.org>`_ 2.4 or later.
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LLVM testing infrastructure organization
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========================================
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The LLVM testing infrastructure contains two major categories of tests:
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regression tests and whole programs. The regression tests are contained
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inside the LLVM repository itself under ``llvm/test`` and are expected
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to always pass -- they should be run before every commit.
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The whole programs tests are referred to as the "LLVM test suite" (or
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"test-suite") and are in the ``test-suite`` module in subversion. For
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historical reasons, these tests are also referred to as the "nightly
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tests" in places, which is less ambiguous than "test-suite" and remains
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in use although we run them much more often than nightly.
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Regression tests
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----------------
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The regression tests are small pieces of code that test a specific
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feature of LLVM or trigger a specific bug in LLVM. They are usually
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written in LLVM assembly language, but can be written in other languages
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if the test targets a particular language front end (and the appropriate
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``--with-llvmgcc`` options were used at ``configure`` time of the
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``llvm`` module). These tests are driven by the 'lit' testing tool,
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which is part of LLVM.
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These code fragments are not complete programs. The code generated from
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them is never executed to determine correct behavior.
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These code fragment tests are located in the ``llvm/test`` directory.
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Typically when a bug is found in LLVM, a regression test containing just
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enough code to reproduce the problem should be written and placed
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somewhere underneath this directory. In most cases, this will be a small
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piece of LLVM assembly language code, often distilled from an actual
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application or benchmark.
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``test-suite``
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--------------
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The test suite contains whole programs, which are pieces of code which
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can be compiled and linked into a stand-alone program that can be
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executed. These programs are generally written in high level languages
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such as C or C++.
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These programs are compiled using a user specified compiler and set of
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flags, and then executed to capture the program output and timing
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information. The output of these programs is compared to a reference
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output to ensure that the program is being compiled correctly.
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In addition to compiling and executing programs, whole program tests
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serve as a way of benchmarking LLVM performance, both in terms of the
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efficiency of the programs generated as well as the speed with which
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LLVM compiles, optimizes, and generates code.
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The test-suite is located in the ``test-suite`` Subversion module.
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Debugging Information tests
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---------------------------
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The test suite contains tests to check quality of debugging information.
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The test are written in C based languages or in LLVM assembly language.
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These tests are compiled and run under a debugger. The debugger output
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is checked to validate of debugging information. See README.txt in the
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test suite for more information . This test suite is located in the
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``debuginfo-tests`` Subversion module.
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Quick start
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===========
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The tests are located in two separate Subversion modules. The
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regressions tests are in the main "llvm" module under the directory
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``llvm/test`` (so you get these tests for free with the main llvm tree).
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Use "make check-all" to run the regression tests after building LLVM.
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The more comprehensive test suite that includes whole programs in C and C++
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is in the ``test-suite`` module. See :ref:`test-suite Quickstart
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<test-suite-quickstart>` for more information on running these tests.
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Regression tests
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----------------
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To run all of the LLVM regression tests, use master Makefile in the
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``llvm/test`` directory:
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.. code-block:: bash
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% gmake -C llvm/test
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or
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.. code-block:: bash
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% gmake check
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If you have `Clang <http://clang.llvm.org/>`_ checked out and built, you
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can run the LLVM and Clang tests simultaneously using:
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or
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.. code-block:: bash
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% gmake check-all
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To run the tests with Valgrind (Memcheck by default), just append
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``VG=1`` to the commands above, e.g.:
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.. code-block:: bash
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% gmake check VG=1
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To run individual tests or subsets of tests, you can use the 'llvm-lit'
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script which is built as part of LLVM. For example, to run the
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'Integer/BitPacked.ll' test by itself you can run:
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.. code-block:: bash
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% llvm-lit ~/llvm/test/Integer/BitPacked.ll
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or to run all of the ARM CodeGen tests:
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.. code-block:: bash
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% llvm-lit ~/llvm/test/CodeGen/ARM
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For more information on using the 'lit' tool, see 'llvm-lit --help' or
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the 'lit' man page.
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Debugging Information tests
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---------------------------
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To run debugging information tests simply checkout the tests inside
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clang/test directory.
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.. code-block:: bash
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% cd clang/test
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% svn co http://llvm.org/svn/llvm-project/debuginfo-tests/trunk debuginfo-tests
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These tests are already set up to run as part of clang regression tests.
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Regression test structure
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=========================
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The LLVM regression tests are driven by 'lit' and are located in the
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``llvm/test`` directory.
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This directory contains a large array of small tests that exercise
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various features of LLVM and to ensure that regressions do not occur.
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The directory is broken into several sub-directories, each focused on a
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particular area of LLVM. A few of the important ones are:
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- ``Analysis``: checks Analysis passes.
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- ``Archive``: checks the Archive library.
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- ``Assembler``: checks Assembly reader/writer functionality.
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- ``Bitcode``: checks Bitcode reader/writer functionality.
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- ``CodeGen``: checks code generation and each target.
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- ``Features``: checks various features of the LLVM language.
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- ``Linker``: tests bitcode linking.
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- ``Transforms``: tests each of the scalar, IPO, and utility transforms
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to ensure they make the right transformations.
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- ``Verifier``: tests the IR verifier.
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Writing new regression tests
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----------------------------
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The regression test structure is very simple, but does require some
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information to be set. This information is gathered via ``configure``
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and is written to a file, ``lit.site.cfg`` in ``llvm/test``. The
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``llvm/test`` Makefile does this work for you.
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In order for the regression tests to work, each directory of tests must
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have a ``lit.local.cfg`` file. Lit looks for this file to determine how
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to run the tests. This file is just Python code and thus is very
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flexible, but we've standardized it for the LLVM regression tests. If
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you're adding a directory of tests, just copy ``lit.local.cfg`` from
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another directory to get running. The standard ``lit.local.cfg`` simply
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specifies which files to look in for tests. Any directory that contains
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only directories does not need the ``lit.local.cfg`` file. Read the :doc:`Lit
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documentation <CommandGuide/lit>` for more information.
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The ``llvm-runtests`` function looks at each file that is passed to it
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and gathers any lines together that match "RUN:". These are the "RUN"
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lines that specify how the test is to be run. So, each test script must
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contain RUN lines if it is to do anything. If there are no RUN lines,
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the ``llvm-runtests`` function will issue an error and the test will
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fail.
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RUN lines are specified in the comments of the test program using the
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keyword ``RUN`` followed by a colon, and lastly the command (pipeline)
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to execute. Together, these lines form the "script" that
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``llvm-runtests`` executes to run the test case. The syntax of the RUN
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lines is similar to a shell's syntax for pipelines including I/O
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redirection and variable substitution. However, even though these lines
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may *look* like a shell script, they are not. RUN lines are interpreted
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directly by the Tcl ``exec`` command. They are never executed by a
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shell. Consequently the syntax differs from normal shell script syntax
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in a few ways. You can specify as many RUN lines as needed.
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lit performs substitution on each RUN line to replace LLVM tool names
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with the full paths to the executable built for each tool (in
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$(LLVM\_OBJ\_ROOT)/$(BuildMode)/bin). This ensures that lit does not
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invoke any stray LLVM tools in the user's path during testing.
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Each RUN line is executed on its own, distinct from other lines unless
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its last character is ``\``. This continuation character causes the RUN
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line to be concatenated with the next one. In this way you can build up
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long pipelines of commands without making huge line lengths. The lines
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ending in ``\`` are concatenated until a RUN line that doesn't end in
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``\`` is found. This concatenated set of RUN lines then constitutes one
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execution. Tcl will substitute variables and arrange for the pipeline to
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be executed. If any process in the pipeline fails, the entire line (and
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test case) fails too.
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Below is an example of legal RUN lines in a ``.ll`` file:
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.. code-block:: llvm
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; RUN: llvm-as < %s | llvm-dis > %t1
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; RUN: llvm-dis < %s.bc-13 > %t2
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; RUN: diff %t1 %t2
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As with a Unix shell, the RUN: lines permit pipelines and I/O
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redirection to be used. However, the usage is slightly different than
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for Bash. To check what's legal, see the documentation for the `Tcl
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exec <http://www.tcl.tk/man/tcl8.5/TclCmd/exec.htm#M2>`_ command and the
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`tutorial <http://www.tcl.tk/man/tcl8.5/tutorial/Tcl26.html>`_. The
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major differences are:
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- You can't do ``2>&1``. That will cause Tcl to write to a file named
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``&1``. Usually this is done to get stderr to go through a pipe. You
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can do that in tcl with ``|&`` so replace this idiom:
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``... 2>&1 | grep`` with ``... |& grep``
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- You can only redirect to a file, not to another descriptor and not
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from a here document.
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- tcl supports redirecting to open files with the @ syntax but you
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shouldn't use that here.
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There are some quoting rules that you must pay attention to when writing
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your RUN lines. In general nothing needs to be quoted. Tcl won't strip
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off any quote characters so they will get passed to the invoked program.
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For example:
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.. code-block:: bash
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... | grep 'find this string'
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This will fail because the ' characters are passed to grep. This would
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instruction grep to look for ``'find`` in the files ``this`` and
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``string'``. To avoid this use curly braces to tell Tcl that it should
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treat everything enclosed as one value. So our example would become:
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.. code-block:: bash
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... | grep {find this string}
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Additionally, the characters ``[`` and ``]`` are treated specially by
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Tcl. They tell Tcl to interpret the content as a command to execute.
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Since these characters are often used in regular expressions this can
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have disastrous results and cause the entire test run in a directory to
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fail. For example, a common idiom is to look for some basicblock number:
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.. code-block:: bash
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... | grep bb[2-8]
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This, however, will cause Tcl to fail because its going to try to
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execute a program named "2-8". Instead, what you want is this:
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.. code-block:: bash
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... | grep {bb\[2-8\]}
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Finally, if you need to pass the ``\`` character down to a program, then
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it must be doubled. This is another Tcl special character. So, suppose
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you had:
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.. code-block:: bash
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... | grep 'i32\*'
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This will fail to match what you want (a pointer to i32). First, the
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``'`` do not get stripped off. Second, the ``\`` gets stripped off by
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Tcl so what grep sees is: ``'i32*'``. That's not likely to match
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anything. To resolve this you must use ``\\`` and the ``{}``, like this:
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.. code-block:: bash
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... | grep {i32\\*}
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If your system includes GNU ``grep``, make sure that ``GREP_OPTIONS`` is
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not set in your environment. Otherwise, you may get invalid results
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(both false positives and false negatives).
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The FileCheck utility
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---------------------
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A powerful feature of the RUN: lines is that it allows any arbitrary
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commands to be executed as part of the test harness. While standard
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(portable) unix tools like 'grep' work fine on run lines, as you see
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above, there are a lot of caveats due to interaction with Tcl syntax,
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and we want to make sure the run lines are portable to a wide range of
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systems. Another major problem is that grep is not very good at checking
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to verify that the output of a tools contains a series of different
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output in a specific order. The FileCheck tool was designed to help with
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these problems.
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FileCheck is designed to read a file to check from standard input, and the set
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of things to verify from a file specified as a command line argument.
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FileCheck is described in :doc:`the FileCheck man page
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<CommandGuide/FileCheck>`.
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Variables and substitutions
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---------------------------
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With a RUN line there are a number of substitutions that are permitted.
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In general, any Tcl variable that is available in the ``substitute``
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function (in ``test/lib/llvm.exp``) can be substituted into a RUN line.
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To make a substitution just write the variable's name preceded by a $.
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Additionally, for compatibility reasons with previous versions of the
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test library, certain names can be accessed with an alternate syntax: a
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% prefix. These alternates are deprecated and may go away in a future
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version.
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Here are the available variable names. The alternate syntax is listed in
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parentheses.
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``$test`` (``%s``)
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The full path to the test case's source. This is suitable for passing on
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the command line as the input to an llvm tool.
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``%(line)``, ``%(line+<number>)``, ``%(line-<number>)``
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The number of the line where this variable is used, with an optional
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integer offset. This can be used in tests with multiple RUN: lines,
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which reference test file's line numbers.
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``$srcdir``
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The source directory from where the "``make check``" was run.
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``objdir``
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The object directory that corresponds to the ``$srcdir``.
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``subdir``
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A partial path from the ``test`` directory that contains the
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sub-directory that contains the test source being executed.
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``srcroot``
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The root directory of the LLVM src tree.
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``objroot``
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The root directory of the LLVM object tree. This could be the same as
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the srcroot.
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``path``
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The path to the directory that contains the test case source. This is
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for locating any supporting files that are not generated by the test,
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but used by the test.
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``tmp``
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The path to a temporary file name that could be used for this test case.
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The file name won't conflict with other test cases. You can append to it
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if you need multiple temporaries. This is useful as the destination of
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some redirected output.
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``target_triplet`` (``%target_triplet``)
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The target triplet that corresponds to the current host machine (the one
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running the test cases). This should probably be called "host".
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``link`` (``%link``)
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This full link command used to link LLVM executables. This has all the
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configured -I, -L and -l options.
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``shlibext`` (``%shlibext``)
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The suffix for the host platforms share library (dll) files. This
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includes the period as the first character.
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To add more variables, two things need to be changed. First, add a line
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in the ``test/Makefile`` that creates the ``site.exp`` file. This will
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"set" the variable as a global in the site.exp file. Second, in the
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``test/lib/llvm.exp`` file, in the substitute proc, add the variable
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name to the list of "global" declarations at the beginning of the proc.
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That's it, the variable can then be used in test scripts.
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Other Features
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--------------
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To make RUN line writing easier, there are several shell scripts located
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in the ``llvm/test/Scripts`` directory. This directory is in the PATH
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when running tests, so you can just call these scripts using their name.
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For example:
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``ignore``
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This script runs its arguments and then always returns 0. This is useful
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in cases where the test needs to cause a tool to generate an error (e.g.
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to check the error output). However, any program in a pipeline that
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returns a non-zero result will cause the test to fail. This script
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overcomes that issue and nicely documents that the test case is
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purposefully ignoring the result code of the tool
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``not``
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This script runs its arguments and then inverts the result code from it.
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Zero result codes become 1. Non-zero result codes become 0. This is
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useful to invert the result of a grep. For example "not grep X" means
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succeed only if you don't find X in the input.
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Sometimes it is necessary to mark a test case as "expected fail" or
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XFAIL. You can easily mark a test as XFAIL just by including ``XFAIL:``
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on a line near the top of the file. This signals that the test case
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should succeed if the test fails. Such test cases are counted separately
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by the testing tool. To specify an expected fail, use the XFAIL keyword
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in the comments of the test program followed by a colon and one or more
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failure patterns. Each failure pattern can be either ``*`` (to specify
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fail everywhere), or a part of a target triple (indicating the test
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should fail on that platform), or the name of a configurable feature
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(for example, ``loadable_module``). If there is a match, the test is
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expected to fail. If not, the test is expected to succeed. To XFAIL
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everywhere just specify ``XFAIL: *``. Here is an example of an ``XFAIL``
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line:
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.. code-block:: llvm
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; XFAIL: darwin,sun
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To make the output more useful, the ``llvm_runtest`` function wil scan
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the lines of the test case for ones that contain a pattern that matches
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``PR[0-9]+``. This is the syntax for specifying a PR (Problem Report) number
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that is related to the test case. The number after "PR" specifies the
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LLVM bugzilla number. When a PR number is specified, it will be used in
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the pass/fail reporting. This is useful to quickly get some context when
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a test fails.
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Finally, any line that contains "END." will cause the special
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interpretation of lines to terminate. This is generally done right after
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the last RUN: line. This has two side effects:
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(a) it prevents special interpretation of lines that are part of the test
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program, not the instructions to the test case, and
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(b) it speeds things up for really big test cases by avoiding
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interpretation of the remainder of the file.
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``test-suite`` Overview
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=======================
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The ``test-suite`` module contains a number of programs that can be
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compiled and executed. The ``test-suite`` includes reference outputs for
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all of the programs, so that the output of the executed program can be
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checked for correctness.
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``test-suite`` tests are divided into three types of tests: MultiSource,
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SingleSource, and External.
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- ``test-suite/SingleSource``
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The SingleSource directory contains test programs that are only a
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single source file in size. These are usually small benchmark
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programs or small programs that calculate a particular value. Several
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such programs are grouped together in each directory.
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- ``test-suite/MultiSource``
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The MultiSource directory contains subdirectories which contain
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entire programs with multiple source files. Large benchmarks and
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whole applications go here.
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- ``test-suite/External``
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The External directory contains Makefiles for building code that is
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external to (i.e., not distributed with) LLVM. The most prominent
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members of this directory are the SPEC 95 and SPEC 2000 benchmark
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suites. The ``External`` directory does not contain these actual
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tests, but only the Makefiles that know how to properly compile these
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programs from somewhere else. When using ``LNT``, use the
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``--test-externals`` option to include these tests in the results.
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.. _test-suite-quickstart:
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``test-suite`` Quickstart
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-------------------------
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The modern way of running the ``test-suite`` is focused on testing and
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benchmarking complete compilers using the
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`LNT <http://llvm.org/docs/lnt>`_ testing infrastructure.
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|
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For more information on using LNT to execute the ``test-suite``, please
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|
see the `LNT Quickstart <http://llvm.org/docs/lnt/quickstart.html>`_
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documentation.
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|
``test-suite`` Makefiles
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|
------------------------
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|
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|
Historically, the ``test-suite`` was executed using a complicated setup
|
|
of Makefiles. The LNT based approach above is recommended for most
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|
users, but there are some testing scenarios which are not supported by
|
|
the LNT approach. In addition, LNT currently uses the Makefile setup
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|
under the covers and so developers who are interested in how LNT works
|
|
under the hood may want to understand the Makefile based setup.
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|
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For more information on the ``test-suite`` Makefile setup, please see
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|
the :doc:`Test Suite Makefile Guide <TestSuiteMakefileGuide>`.
|