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ReStructuredText
516 lines
19 KiB
ReStructuredText
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LLVM Testing Infrastructure Guide
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=================================
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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. The language they are
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written in depends on the part of LLVM being tested. These tests are driven by
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the :doc:`Lit <CommandGuide/lit>` testing tool (which is part of LLVM), and
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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. For example, it can be a small
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piece of LLVM IR distilled from an actual 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 the master Makefile in the
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``llvm/test`` directory. LLVM Makefiles require GNU Make (read the :doc:`LLVM
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Makefile Guide <MakefileGuide>` for more details):
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.. code-block:: bash
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% make -C llvm/test
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or:
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.. code-block:: bash
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% make 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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.. code-block:: bash
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% make 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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% make 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 :program:`lit` tool, see ``llvm-lit --help``
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or the :doc:`lit man page <CommandGuide/lit>`.
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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 :program:`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.
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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, ``test/lit.site.cfg`` in the build directory.
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The ``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. :program:`lit` looks for this file to determine
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how 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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Each test file must contain lines starting with "RUN:" that tell :program:`lit`
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how to run it. If there are no RUN lines, :program:`lit` will issue an error
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while running a test.
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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 :program:`lit`
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executes to run the test case. The syntax of the RUN lines is similar to a
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shell's syntax for pipelines including I/O redirection and variable
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substitution. However, even though these lines may *look* like a shell
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script, they are not. RUN lines are interpreted by :program:`lit`.
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Consequently, the syntax differs from shell in a few ways. You can specify
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as many RUN lines as needed.
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:program:`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 :program:`lit` does
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not 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. :program:`lit` will substitute variables and arrange for the pipeline
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to 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.
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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. :program:`lit` won't
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strip off any quote characters so they will get passed to the invoked program.
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To avoid this use curly braces to tell :program:`lit` that it should treat
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everything enclosed as one value.
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In general, you should strive to keep your RUN lines as simple as possible,
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using them only to run tools that generate textual output you can then examine.
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The recommended way to examine output to figure out if the test passes is using
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the :doc:`FileCheck tool <CommandGuide/FileCheck>`. *[The usage of grep in RUN
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lines is deprecated - please do not send or commit patches that use it.]*
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Fragile tests
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-------------
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It is easy to write a fragile test that would fail spuriously if the tool being
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tested outputs a full path to the input file. For example, :program:`opt` by
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default outputs a ``ModuleID``:
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.. code-block:: console
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$ cat example.ll
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define i32 @main() nounwind {
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ret i32 0
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}
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$ opt -S /path/to/example.ll
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; ModuleID = '/path/to/example.ll'
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define i32 @main() nounwind {
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ret i32 0
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}
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``ModuleID`` can unexpetedly match against ``CHECK`` lines. For example:
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.. code-block:: llvm
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; RUN: opt -S %s | FileCheck
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define i32 @main() nounwind {
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; CHECK-NOT: load
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ret i32 0
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}
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This test will fail if placed into a ``download`` directory.
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To make your tests robust, always use ``opt ... < %s`` in the RUN line.
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:program:`opt` does not output a ``ModuleID`` when input comes from stdin.
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Platform-Specific Tests
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-----------------------
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Whenever adding tests that require the knowledge of a specific platform,
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either related to code generated, specific output or back-end features,
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you must make sure to isolate the features, so that buildbots that
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run on different architectures (and don't even compile all back-ends),
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don't fail.
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The first problem is to check for target-specific output, for example sizes
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of structures, paths and architecture names, for example:
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* Tests containing Windows paths will fail on Linux and vice-versa.
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* Tests that check for ``x86_64`` somewhere in the text will fail anywhere else.
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* Tests where the debug information calculates the size of types and structures.
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Also, if the test rely on any behaviour that is coded in any back-end, it must
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go in its own directory. So, for instance, code generator tests for ARM go
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into ``test/CodeGen/ARM`` and so on. Those directories contain a special
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``lit`` configuration file that ensure all tests in that directory will
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only run if a specific back-end is compiled and available.
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For instance, on ``test/CodeGen/ARM``, the ``lit.local.cfg`` is:
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.. code-block:: python
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config.suffixes = ['.ll', '.c', '.cpp', '.test']
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targets = set(config.root.targets_to_build.split())
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if not 'ARM' in targets:
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config.unsupported = True
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Other platform-specific tests are those that depend on a specific feature
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of a specific sub-architecture, for example only to Intel chips that support ``AVX2``.
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For instance, ``test/CodeGen/X86/psubus.ll`` tests three sub-architecture
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variants:
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.. code-block:: llvm
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; RUN: llc -mcpu=core2 < %s | FileCheck %s -check-prefix=SSE2
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; RUN: llc -mcpu=corei7-avx < %s | FileCheck %s -check-prefix=AVX1
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; RUN: llc -mcpu=core-avx2 < %s | FileCheck %s -check-prefix=AVX2
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And the checks are different:
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.. code-block:: llvm
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; SSE2: @test1
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; SSE2: psubusw LCPI0_0(%rip), %xmm0
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; AVX1: @test1
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; AVX1: vpsubusw LCPI0_0(%rip), %xmm0, %xmm0
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; AVX2: @test1
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; AVX2: vpsubusw LCPI0_0(%rip), %xmm0, %xmm0
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So, if you're testing for a behaviour that you know is platform-specific or
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depends on special features of sub-architectures, you must add the specific
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triple, test with the specific FileCheck and put it into the specific
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directory that will filter out all other architectures.
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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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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 shared library (DLL) files. This
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includes the period as the first character.
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To add more variables, look at ``test/lit.cfg``.
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Other Features
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--------------
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To make RUN line writing easier, there are several helper scripts and programs
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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.
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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, :program:`lit` will 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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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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Historically, the ``test-suite`` was executed using a complicated setup
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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
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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
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under the hood may want to understand the Makefile based setup.
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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>`.
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