diff options
Diffstat (limited to 'clang/www/hacking.html')
| -rw-r--r-- | clang/www/hacking.html | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/clang/www/hacking.html b/clang/www/hacking.html new file mode 100644 index 0000000..aa13b8d --- /dev/null +++ b/clang/www/hacking.html @@ -0,0 +1,326 @@ +<!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> |