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diff --git a/docs/users_guide/codegens.xml b/docs/users_guide/codegens.xml deleted file mode 100644 index d9c4859071..0000000000 --- a/docs/users_guide/codegens.xml +++ /dev/null @@ -1,125 +0,0 @@ -<?xml version="1.0" encoding="iso-8859-1"?> -<sect1 id="code-generators"> - <title>GHC Backends</title> - <indexterm><primary>ghc backends</primary></indexterm> - <indexterm><primary>ghc code generators</primary></indexterm> - - <para>GHC supports multiple backend code generators. This is the part - of the compiler responsible for taking the last intermediate - representation that GHC uses (a form called Cmm that is a simple, C like - language) and compiling it to executable code. The backends that GHC - support are described below. - </para> - - <sect2 id="native-code-gen"> - <title>Native code Generator (<option>-fasm</option>)</title> - <indexterm><primary>native code generator</primary></indexterm> - - The default backend for GHC. It is a native code generator, compiling Cmm - all the way to assembly code. It is the fastest backend and generally - produces good performance code. It has the best support for compiling - shared libraries. Select it with the <option>-fasm</option> flag. - </sect2> - - <sect2 id="llvm-code-gen"> - <title>LLVM Code Generator (<option>-fllvm</option>)</title> - <indexterm><primary>LLVM code generator</primary></indexterm> - - <para>This is an alternative backend that uses the - <ulink url="http://llvm.org">LLVM</ulink> compiler to produce - executable code. It generally produces code as with performance as - good as the native code generator but for some cases can produce - much faster code. This is especially true for numeric, array heavy - code using packages like vector. The penalty is a significant increase in - compilation times. Select the LLVM backend with the - <option>-fllvm</option> flag. Currently <emphasis>LLVM 2.8</emphasis> and - later are supported. - </para> - - <para>You must install and have LLVM available on your PATH for the LLVM - code generator to work. Specifically GHC needs to be able to call the - <command>opt</command> and <command>llc</command> tools. Secondly, if you - are running Mac OS X with LLVM 3.0 or greater then - you also need the <ulink url="http://clang.llvm.org">Clang c - compiler</ulink> compiler available on your PATH. - </para> - - <para>To install LLVM and Clang: - <itemizedlist> - <listitem><para><emphasis>Linux</emphasis>: Use your package management tool.</para> - </listitem> - <listitem><para><emphasis>Mac OS X</emphasis>: Clang is included by - default on recent OS X machines when XCode is installed (from - <literal>10.6</literal> and later). LLVM is not included. In - order to use the LLVM based code generator, you should install - the <ulink - url="http://mxcl.github.com/homebrew/">Homebrew</ulink> - package manager for OS X. Alternatively you can download - binaries for LLVM and Clang from <ulink - url="http://llvm.org/releases/download.html">here</ulink>.</para> - </listitem> - - <listitem><para><emphasis>Windows</emphasis>: You should download binaries for - LLVM and clang from - <ulink url="http://llvm.org/releases/download.html">here</ulink>.</para> - </listitem> - </itemizedlist> - </para> - </sect2> - - <sect2 id="c-code-gen"> - <title>C Code Generator (<option>-fvia-C</option>)</title> - <indexterm><primary>C code generator</primary></indexterm> - <indexterm><primary>-fvia-C</primary></indexterm> - - <para>This is the oldest code generator in GHC and is generally not included - any more having been deprecated around GHC 7.0. Select it with the - <option>-fvia-C</option> flag. - </para> - - <para>The C code generator is only supported when GHC is built in - unregisterised mode, a mode where GHC produces 'portable' C code as - output to facilitate porting GHC itself to a new platform. This mode - produces much slower code though so it's unlikely your version of - GHC was built this way. If it has then the native code generator - probably won't be available. You can check this information by calling - <link linkend="ghc-info"><literal>ghc --info</literal></link>. - </para> - </sect2> - - <sect2 id="unreg"> - <title>Unregisterised compilation</title> - <indexterm><primary>unregisterised compilation</primary></indexterm> - - <para>The term "unregisterised" really means "compile via vanilla C", - disabling some of the platform-specific tricks that GHC normally uses to - make programs go faster. When compiling unregisterised, GHC simply - generates a C file which is compiled via gcc.</para> - - <para>When GHC is build in unregisterised mode only the LLVM and C code - generators will be available. The native code generator won't be. LLVM - usually offers a substantial performance benefit over the C backend in - unregisterised mode.</para> - - <para>Unregisterised compilation can be useful when porting GHC to a new - machine, since it reduces the prerequisite tools to - <command>gcc</command>, <command>as</command>, and <command>ld</command> - and nothing more, and furthermore the amount of platform-specific code - that needs to be written in order to get - unregisterised compilation going is usually fairly small.</para> - - <para>Unregisterised compilation cannot be selected at compile-time; you - have to build GHC with the appropriate options set. Consult the GHC - Building Guide for details.</para> - - <para>You can check if your GHC is unregisterised by calling - <link linkend="ghc-info"><literal>ghc --info</literal></link>.</para> - </sect2> - -</sect1> - -<!-- Emacs stuff: - ;;; Local Variables: *** - ;;; sgml-parent-document: ("users_guide.xml" "book" "chapter" "sect1") *** - ;;; End: *** - --> |