Merge branch 'master' of ssh://bitbucket.org/czan/honours

author: Carlo Zancanaro <carlo@pc-4w14-0.cs.usyd.edu.au> 2012-10-15 17:10:06 +1100
committer: Carlo Zancanaro <carlo@pc-4w14-0.cs.usyd.edu.au> 2012-10-15 17:10:06 +1100
commit: be1de4be954c80875ad4108e0a33e8e131b2f2c0 (patch)
tree: 1fbbecf276bf7c7bdcbb4dd446099d6d90eaa516 /clang/www/hacking.html
parent: c4626a62754862d20b41e8a46a3574264ea80e6d (diff)
parent: f1bd2e48c5324d3f7cda4090c87f8a5b6f463ce2 (diff)
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+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
+          "http://www.w3.org/TR/html4/strict.dtd">
+<!-- Material used from: HTML 4.01 specs: http://www.w3.org/TR/html401/ -->
+<html>
+<head>
+  <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
+  <title>Hacking on clang</title>
+  <link type="text/css" rel="stylesheet" href="menu.css">
+  <link type="text/css" rel="stylesheet" href="content.css">
+  <style type="text/css">
+  pre { margin-left: 1.5em; }
+  </style>
+</head>
+<body>
+<!--#include virtual="menu.html.incl"-->
+<div id="content">
+  <!--*********************************************************************-->
+  <h1>Hacking on Clang</h1>
+  <!--*********************************************************************-->
+
+  <p>This document provides some hints for how to get started hacking
+  on Clang for developers who are new to the Clang and/or LLVM
+  codebases.</p>
+    <ul>
+      <li><a href="#style">Coding Standards</a></li>
+      <li><a href="#docs">Developer Documentation</a></li>
+      <li><a href="#debugging">Debugging</a></li>
+      <li><a href="#testing">Testing</a>
+      <ul>
+        <li><a href="#testingNonWindows">Testing on Unix-like Systems</a></li>
+        <li><a href="#testingWindows">Testing using Visual Studio on Windows</a></li>
+        <li><a href="#testingCommands">Testing on the Command Line</a></li>
+      </ul>
+      </li>
+      <li><a href="#patches">Creating Patch Files</a></li>
+      <li><a href="#irgen">LLVM IR Generation</a></li>
+    </ul>
+
+  <!--=====================================================================-->
+  <h2 id="style">Coding Standards</h2>
+  <!--=====================================================================-->
+
+  <p>Clang follows the
+  LLVM <a href="http://llvm.org/docs/CodingStandards.html">Coding
+  Standards</a>. When submitting patches, please take care to follow these standards
+  and to match the style of the code to that present in Clang (for example, in
+  terms of indentation, bracing, and statement spacing).</p>
+
+  <p>Clang has a few additional coding standards:</p>
+  <ul>
+    <li><i>cstdio is forbidden</i>: library code should not output diagnostics
+      or other information using <tt>cstdio</tt>; debugging routines should
+      use <tt>llvm::errs()</tt>. Other uses of <tt>cstdio</tt> impose behavior
+      upon clients and block integrating Clang as a library. Libraries should
+      support <tt>raw_ostream</tt> based interfaces for textual
+      output. See <a href="http://llvm.org/docs/CodingStandards.html#ll_raw_ostream">Coding
+      Standards</a>.</li>
+  </ul>
+
+  <!--=====================================================================-->
+  <h2 id="docs">Developer Documentation</h2>
+  <!--=====================================================================-->
+
+  <p>Both Clang and LLVM use doxygen to provide API documentation. Their
+  respective web pages (generated nightly) are here:</p>
+    <ul>
+      <li><a href="http://clang.llvm.org/doxygen">Clang</a></li>
+      <li><a href="http://llvm.org/doxygen">LLVM</a></li>
+    </ul>
+
+  <p>For work on the LLVM IR generation, the LLVM assembly language
+  <a href="http://llvm.org/docs/LangRef.html">reference manual</a> is
+  also useful.</p>
+
+  <!--=====================================================================-->
+  <h2 id="debugging">Debugging</h2>
+  <!--=====================================================================-->
+
+  <p>Inspecting data structures in a debugger:</p>
+    <ul>
+      <li>Many LLVM and Clang data structures provide
+        a <tt>dump()</tt> method which will print a description of the
+        data structure to <tt>stderr</tt>.</li>
+      <li>The <a href="docs/InternalsManual.html#QualType"><tt>QualType</tt></a>
+      structure is used pervasively. This is a simple value class for
+      wrapping types with qualifiers; you can use
+      the <tt>isConstQualified()</tt>, for example, to get one of the
+      qualifiers, and the <tt>getTypePtr()</tt> method to get the
+      wrapped <tt>Type*</tt> which you can then dump.</li>
+    </ul>
+
+  <!--=====================================================================-->
+  <h3 id="debuggingVisualStudio">Debugging using Visual Studio</h3>
+  <!--=====================================================================-->
+
+  <p>The file <tt>utils/clangVisualizers.txt</tt> provides debugger visualizers that make debugging
+  of more complex data types much easier.</p>
+  <p>There are two ways to install them:</p>
+  
+  <ul>
+      <li>Put the path to <tt>clangVisualizers.txt</tt> in the environment variable called
+      <tt>_vcee_autoexp</tt>. This method should work for Visual Studio 2008 and above.
+      </li>
+      <li>Edit your local <tt>autoexp.dat</tt> (make sure you make a backup first!), 
+      located in <tt>Visual Studio Directory\Common7\Packages\Debugger</tt> and append 
+      the contents of <tt>clangVisuailzers.txt</tt> to it. This method should work for 
+      Visual Studio 2008 and above.
+       </li>
+  </ul>
+
+  <p><i>[Note: To disable the visualizer for any specific variable, type 
+  <tt>variable_name,!</tt> inside the watch window.]</i></p>
+
+  <!--=====================================================================-->
+  <h2 id="testing">Testing</h2>
+  <!--=====================================================================-->
+
+  <p><i>[Note: The test running mechanism is currently under revision, so the
+  following might change shortly.]</i></p>
+
+  <!--=====================================================================-->
+  <h3 id="testingNonWindows">Testing on Unix-like Systems</h3>
+  <!--=====================================================================-->
+
+  <p>Clang includes a basic regression suite in the tree which can be
+  run with <tt>make test</tt> from the top-level clang directory, or
+  just <tt>make</tt> in the <em>test</em> sub-directory.
+  <tt>make VERBOSE=1</tt> can be used to show more detail
+  about what is being run.</p>
+
+  <p>If you built LLVM and Clang using CMake, the test suite can be run
+  with <tt>make clang-test</tt> from the top-level LLVM directory.</p>
+
+  <p>The tests primarily consist of a test runner script running the compiler
+  under test on individual test files grouped in the directories under the
+  test directory.  The individual test files include comments at the
+  beginning indicating the Clang compile options to use, to be read
+  by the test runner. Embedded comments also can do things like telling
+  the test runner that an error is expected at the current line.
+  Any output files produced by the test will be placed under
+  a created Output directory.</p>
+
+  <p>During the run of <tt>make test</tt>, the terminal output will
+  display a line similar to the following:</p>
+
+  <pre>--- Running clang tests for i686-pc-linux-gnu ---</pre>
+
+  <p>followed by a line continually overwritten with the current test
+  file being compiled, and an overall completion percentage.</p>
+
+  <p>After the <tt>make test</tt> run completes, the absence of any
+  <tt>Failing Tests (count):</tt> message indicates that no tests
+  failed unexpectedly.  If any tests did fail, the
+  <tt>Failing Tests (count):</tt> message will be followed by a list
+  of the test source file paths that failed.  For example:</p>
+
+  <pre>
+  Failing Tests (3):
+      /home/john/llvm/tools/clang/test/SemaCXX/member-name-lookup.cpp
+      /home/john/llvm/tools/clang/test/SemaCXX/namespace-alias.cpp
+      /home/john/llvm/tools/clang/test/SemaCXX/using-directive.cpp
+</pre>
+
+  <p>If you used the <tt>make VERBOSE=1</tt> option, the terminal
+  output will reflect the error messages from the compiler and
+  test runner.</p>
+
+  <p>The regression suite can also be run with Valgrind by running
+  <tt>make test VG=1</tt> in the top-level clang directory.</p>
+
+  <p>For more intensive changes, running
+  the <a href="http://llvm.org/docs/TestingGuide.html#testsuiterun">LLVM
+  Test Suite</a> with clang is recommended. Currently the best way to
+  override LLVMGCC, as in: <tt>make LLVMGCC="clang -std=gnu89"
+  TEST=nightly report</tt> (make sure <tt>clang</tt> is in your PATH or use the
+  full path).</p>
+
+  <!--=====================================================================-->
+  <h3 id="testingWindows">Testing using Visual Studio on Windows</h3>
+  <!--=====================================================================-->
+
+  <p>The Clang test suite can be run from either Visual Studio or
+  the command line.</p>
+
+  <p>Note that the test runner is based on
+  Python, which must be installed.  Find Python at:
+  <a href="http://www.python.org/download/">http://www.python.org/download/</a>.
+  Download the latest stable version (2.6.2 at the time of this writing).</p>
+
+  <p>The GnuWin32 tools are also necessary for running the tests.
+  Get them from <a href="http://getgnuwin32.sourceforge.net/">
+  http://getgnuwin32.sourceforge.net/</a>.
+  If the environment variable <tt>%PATH%</tt> does not have GnuWin32,
+  or if other grep(s) supercedes GnuWin32 on <tt>%PATH%,</tt>
+  you should specify <tt>LLVM_LIT_TOOLS_DIR</tt>
+  to CMake explicitly.</p>
+
+  <p>The cmake build tool is set up to create Visual Studio project files
+  for running the tests, "clang-test" being the root.  Therefore, to
+  run the test from Visual Studio, right-click the clang-test project
+  and select "Build".</p>
+
+  <p>
+    Please see also
+    <a href="http://llvm.org/docs/GettingStartedVS.html">Getting Started
+    with the LLVM System using Microsoft Visual Studio</a> and
+    <a href="http://llvm.org/docs/CMake.html">Building LLVM with CMake</a>.
+  </p>
+
+  <!--=====================================================================-->
+  <h3 id="testingCommands">Testing on the Command Line</h3>
+  <!--=====================================================================-->
+
+  <p>If you want more control over how the tests are run, it may
+  be convenient to run the test harness on the command-line directly. Before
+  running tests from the command line, you will need to ensure that
+  <tt>lit.site.cfg</tt> files have been created for your build.  You can do
+  this by running the tests as described in the previous sections. Once the
+  tests have started running, you can stop them with control+C, as the
+  files are generated before running any tests.</p>
+
+  <p>Once that is done, to run all the tests from the command line,
+  execute a command like the following:</p>
+
+  <pre>
+  python (path to llvm)\llvm\utils\lit\lit.py -sv
+  --param=build_mode=Win32 --param=build_config=Debug
+  --param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg
+ (path to llvm)\llvm\tools\clang\test
+</pre>
+
+  <p>For CMake builds e.g. on Windows with Visual Studio, you will need
+  to specify your build configuration (Debug, Release, etc.) via
+  <tt>--param=build_config=(build config)</tt>.  You may also need to specify
+  the build mode (Win32, etc) via <tt>--param=build_mode=(build mode)</tt>.</p>
+
+  <p>Additionally, you will need to specify the lit site configuration which
+  lives in (build dir)\tools\clang\test, via
+  <tt>--param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg</tt>.
+  </p>
+
+  <p>To run a single test:</p>
+
+  <pre>
+  python (path to llvm)\llvm\utils\lit\lit.py -sv
+  --param=build_mode=Win32 --param=build_config=Debug
+  --param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg
+  (path to llvm)\llvm\tools\clang\test\(dir)\(test)
+</pre>
+
+  <p>For example:</p>
+
+  <pre>
+  python C:\Tool\llvm\utils\lit\lit.py -sv
+  --param=build_mode=Win32 --param=build_config=Debug
+  --param=clang_site_config=c:\Tools\build\tools\clang\test\lit.site.cfg
+  C:\Tools\llvm\tools\clang\test\Sema\wchar.c
+</pre>
+
+  <p>The -sv option above tells the runner to show the test output if
+  any tests failed, to help you determine the cause of failure.</p>
+
+  <p>You can also pass in the --no-progress-bar option if you wish to disable
+  progress indications while the tests are running.</p>
+
+  <p>Your output might look something like this:</p>
+
+  <pre>lit.py: lit.cfg:152: note: using clang: 'C:\Tools\llvm\bin\Release\clang.EXE'
+-- Testing: Testing: 2534 tests, 4 threads --
+Testing: 0 .. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90..
+Testing Time: 81.52s
+  Expected Passes    : 2503
+  Expected Failures  : 28
+  Unsupported Tests  : 3
+</pre>
+
+  <p>The statistic, "Unexpected Failures" (not shown if all tests pass), is the important one.</p>
+
+  <!--=====================================================================-->
+  <h2 id="patches">Creating Patch Files</h2>
+  <!--=====================================================================-->
+
+  <p>To return changes to the Clang team, unless you have checkin
+  privileges, the preferred way is to send patch files to the
+  cfe-commits mailing list, with an explanation of what the patch is
+  for.  If your patch requires a wider discussion (for example,
+  because it is an architectural change), you can use the cfe-dev
+  mailing list.  </p>
+
+  <p>To create these patch files, change directory
+  to the llvm/tools/clang root and run:</p>
+
+  <pre>svn diff (relative path) >(patch file name)</pre>
+
+  <p>For example, for getting the diffs of all of clang:</p>
+
+  <pre>svn diff . >~/mypatchfile.patch</pre>
+
+  <p>For example, for getting the diffs of a single file:</p>
+
+  <pre>svn diff lib/Parse/ParseDeclCXX.cpp >~/ParseDeclCXX.patch</pre>
+
+  <p>Note that the paths embedded in the patch depend on where you run it,
+  so changing directory to the llvm/tools/clang directory is recommended.</p>
+
+  <!--=====================================================================-->
+  <h2 id="irgen">LLVM IR Generation</h2>
+  <!--=====================================================================-->
+
+  <p>The LLVM IR generation part of clang handles conversion of the
+    AST nodes output by the Sema module to the LLVM Intermediate
+    Representation (IR). Historically, this was referred to as
+    "codegen", and the Clang code for this lives
+    in <tt>lib/CodeGen</tt>.</p>
+
+  <p>The output is most easily inspected using the <tt>-emit-llvm</tt>
+    option to clang (possibly in conjunction with <tt>-o -</tt>). You
+    can also use <tt>-emit-llvm-bc</tt> to write an LLVM bitcode file
+    which can be processed by the suite of LLVM tools
+    like <tt>llvm-dis</tt>, <tt>llvm-nm</tt>, etc. See the LLVM
+    <a href="http://llvm.org/docs/CommandGuide/">Command Guide</a>
+    for more information.</p>
+
+</div>
+</body>
+</html>
author	Carlo Zancanaro <carlo@pc-4w14-0.cs.usyd.edu.au>	2012-10-15 17:10:06 +1100
committer	Carlo Zancanaro <carlo@pc-4w14-0.cs.usyd.edu.au>	2012-10-15 17:10:06 +1100
commit	be1de4be954c80875ad4108e0a33e8e131b2f2c0 (patch)
tree	1fbbecf276bf7c7bdcbb4dd446099d6d90eaa516 /clang/www/hacking.html
parent	c4626a62754862d20b41e8a46a3574264ea80e6d (diff)
parent	f1bd2e48c5324d3f7cda4090c87f8a5b6f463ce2 (diff)