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<head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  <link rel="stylesheet" href="llvm.css" type="text/css" media="screen">
  <title>Bootstrapping the LLVM C/C++ Front-End</title>
</head>
<body>

<div class="doc_title">
  Bootstrapping the LLVM C/C++ Front-End
</div>

<ol>
  <li><a href="#cautionarynote">A Cautionary Note</a>
    <ul>
      <li><a href="#cygwin">Building under Cygwin</a></li>
      <li><a href="#aix">Building under AIX</a></li>
    </ul>
  </li>
  <li><a href="#instructions">Instructions</a></li>
  <li><a href="#license">License Information</a></li>
</ol>

<div class="doc_author">    
  <p>Written by <NAME> and 
     <a href="http://nondot.org/sabre"><NAME></a></p>
</div>

<!-- *********************************************************************** -->
<div class="doc_section">
  <a name="cautionarynote">A Cautionary Note</a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">
<p>This document is intended to explain the process of building the
LLVM C/C++ front-end, based on GCC 3.4, from its source code. You
would have to do this, for example, if you are porting LLVM to a new
architecture or operating system.</p>

<p><b>NOTE:</b> This is currently a somewhat fragile, error-prone
process, and you should <b>only</b> try to do it if:</p>

<ol>
  <li>you really, really, really can't use the binaries we distribute</li>
  <li>you need GCC to fix some of the header files on your system</li>
  <li>you are an elite GCC hacker.</li>
</ol>

<p>We welcome patches to help make this process simpler.</p>
</div>

<!--=========================================================================-->
<div class="doc_subsection">
  <a name="cygwin">Building under Cygwin</a>
</div>
<!--=========================================================================-->

<div class="doc_text">
<p>If you are building LLVM and the C front-end under Cygwin, please note that
the LLVM and GCC makefiles do not correctly handle spaces in paths.  To deal
with this issue, make sure that your LLVM and GCC source and build trees are 
located in a top-level directory (like <tt>/cygdrive/c/llvm</tt> and 
<tt>/cygdrive/c/llvm-cfrontend</tt>), not in a directory that contains a space
(which includes your "home directory", because it lives under the "Documents 
and Settings" directory).  We welcome patches to fix this issue.
</p>
</div>

<!--=========================================================================-->
<div class="doc_subsection">
  <a name="aix">Building under AIX</a>
</div>
<!--=========================================================================-->

<div class="doc_text">
<p>If you are building LLVM and the C front-end under AIX, do NOT use GNU
Binutils.  They are not stable under AIX and may produce incorrect and/or
invalid code.  Instead, use the system assembler and linker.
</p>
</div>

<!-- *********************************************************************** -->
<div class="doc_section">
  <a name="instructions">Instructions</a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">
<p>
<ol>
<li><p>Configure and build the LLVM libraries and tools using:</p>
<pre>
 % cd llvm
 % ./configure [options...]
 % gmake tools-only
</pre>
    <p>This will build all of the LLVM tools and libraries.</p></li>

<li><p>Add the directory containing the tools to your PATH.</p>
<pre>
 % set path = ( `cd llvm/tools/Debug &amp;&amp; pwd` $path )
</pre></li>

<li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>

<li><p>Make "build" and "install" directories as siblings of the "src" tree.</p>
<pre>
 % pwd
 /usr/local/example/cfrontend/src
 % cd ..
 % mkdir build install
 % set CFEINSTALL = `pwd`/install
</pre></li>


<li><p>Configure, build, and install the C front-end:</p>

<p>
<b>Linux/x86:</b><br>
<b>MacOS X/PowerPC</b> (requires dlcompat library):<br>
<b>AIX/PowerPC:</b>
</p>

<pre>
 % cd build
 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
   --disable-shared --enable-languages=c,c++
 % gmake
 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc 
 % gmake all; gmake install
</pre>

<p><b>Cygwin/x86:</b></p>

<pre>
 % cd build
 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
   --disable-shared --enable-languages=c,c++ --disable-c-mbchar
 % gmake
 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc 
 % gmake all; gmake install
</pre>

<p><b>Solaris/SPARC:</b></p>

<p>
For Solaris/SPARC, LLVM only supports the SPARC V9.  Therefore, the
configure command line should specify sparcv9, as shown below. Also,
note that Solaris has trouble with various wide (multibyte) character
functions from C as referenced from C++, so we typically configure with
--disable-c-mbchar (cf. <a href="http://llvm.cs.uiuc.edu/PR206">Bug 206</a>).
</p>

<pre>
 % cd build
 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
   --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \
   --disable-c-mbchar
 % gmake
 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc 
 % gmake all; gmake install
</pre>

 <p><b>Common Problem:</b> You may get error messages regarding the fact
 that LLVM does not support inline assembly. Here are two common
 fixes:</p>

 <ul>
  <li><p><b>Fix 1:</b> If you have system header files that include
   inline assembly, you may have to modify them to remove the inline
   assembly, and install the modified versions in
   <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code>.</li>

  <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
   haven't tried yet, you will probably have to edit the appropriate
   version of atomicity.h under
   <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
   and apply a patch so that it does not use inline assembly.</li>
 </ul>

 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
 to a new architecture, or compiling in a different configuration that we have
 previously, there are probably several changes you will have to make to the GCC
 target to get it to work correctly.  These include:<p>

 <ul>
  <li>Often targets include special or assembler linker flags which
      <tt>gccas</tt>/<tt>gccld</tt> does not understand.  In general, these can
      just be removed.</li>
  <li>LLVM currently does not support any floating point values other than 
      32-bit and 64-bit IEEE floating point.  The primary effect of this is
      that you may have to map "long double" onto "double".</li>
  <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
      These may need to be disabled.</li>
  <li>No inline assembly for position independent code.  At the LLVM level,
      everything is position independent.</li>
  <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
  <li>You may have to disable multilib support in your target.  Using multilib<commit_msg>Fix the path to the fixinc'd headers.  Patch contributed by <NAME>!<commit_after><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
                      "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  <link rel="stylesheet" href="llvm.css" type="text/css" media="screen">
  <title>Bootstrapping the LLVM C/C++ Front-End</title>
</head>
<body>

<div class="doc_title">
  Bootstrapping the LLVM C/C++ Front-End
</div>

<ol>
  <li><a href="#cautionarynote">A Cautionary Note</a>
    <ul>
      <li><a href="#cygwin">Building under Cygwin</a></li>
      <li><a href="#aix">Building under AIX</a></li>
    </ul>
  </li>
  <li><a href="#instructions">Instructions</a></li>
  <li><a href="#license">License Information</a></li>
</ol>

<div class="doc_author">    
  <p>Written by <NAME> and 
     <a href="http://nondot.org/sabre"><NAME></a></p>
</div>

<!-- *********************************************************************** -->
<div class="doc_section">
  <a name="cautionarynote">A Cautionary Note</a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">
<p>This document is intended to explain the process of building the
LLVM C/C++ front-end, based on GCC 3.4, from its source code. You
would have to do this, for example, if you are porting LLVM to a new
architecture or operating system.</p>

<p><b>NOTE:</b> This is currently a somewhat fragile, error-prone
process, and you should <b>only</b> try to do it if:</p>

<ol>
  <li>you really, really, really can't use the binaries we distribute</li>
  <li>you need GCC to fix some of the header files on your system</li>
  <li>you are an elite GCC hacker.</li>
</ol>

<p>We welcome patches to help make this process simpler.</p>
</div>

<!--=========================================================================-->
<div class="doc_subsection">
  <a name="cygwin">Building under Cygwin</a>
</div>
<!--=========================================================================-->

<div class="doc_text">
<p>If you are building LLVM and the C front-end under Cygwin, please note that
the LLVM and GCC makefiles do not correctly handle spaces in paths.  To deal
with this issue, make sure that your LLVM and GCC source and build trees are 
located in a top-level directory (like <tt>/cygdrive/c/llvm</tt> and 
<tt>/cygdrive/c/llvm-cfrontend</tt>), not in a directory that contains a space
(which includes your "home directory", because it lives under the "Documents 
and Settings" directory).  We welcome patches to fix this issue.
</p>
</div>

<!--=========================================================================-->
<div class="doc_subsection">
  <a name="aix">Building under AIX</a>
</div>
<!--=========================================================================-->

<div class="doc_text">
<p>If you are building LLVM and the C front-end under AIX, do NOT use GNU
Binutils.  They are not stable under AIX and may produce incorrect and/or
invalid code.  Instead, use the system assembler and linker.
</p>
</div>

<!-- *********************************************************************** -->
<div class="doc_section">
  <a name="instructions">Instructions</a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">
<p>
<ol>
<li><p>Configure and build the LLVM libraries and tools using:</p>
<pre>
 % cd llvm
 % ./configure [options...]
 % gmake tools-only
</pre>
    <p>This will build all of the LLVM tools and libraries.</p></li>

<li><p>Add the directory containing the tools to your PATH.</p>
<pre>
 % set path = ( `cd llvm/tools/Debug &amp;&amp; pwd` $path )
</pre></li>

<li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>

<li><p>Make "build" and "install" directories as siblings of the "src" tree.</p>
<pre>
 % pwd
 /usr/local/example/cfrontend/src
 % cd ..
 % mkdir build install
 % set CFEINSTALL = `pwd`/install
</pre></li>


<li><p>Configure, build, and install the C front-end:</p>

<p>
<b>Linux/x86:</b><br>
<b>MacOS X/PowerPC</b> (requires dlcompat library):<br>
<b>AIX/PowerPC:</b>
</p>

<pre>
 % cd build
 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
   --disable-shared --enable-languages=c,c++
 % gmake
 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc 
 % gmake all; gmake install
</pre>

<p><b>Cygwin/x86:</b></p>

<pre>
 % cd build
 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
   --disable-shared --enable-languages=c,c++ --disable-c-mbchar
 % gmake
 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc 
 % gmake all; gmake install
</pre>

<p><b>Solaris/SPARC:</b></p>

<p>
For Solaris/SPARC, LLVM only supports the SPARC V9.  Therefore, the
configure command line should specify sparcv9, as shown below. Also,
note that Solaris has trouble with various wide (multibyte) character
functions from C as referenced from C++, so we typically configure with
--disable-c-mbchar (cf. <a href="http://llvm.cs.uiuc.edu/PR206">Bug 206</a>).
</p>

<pre>
 % cd build
 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
   --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \
   --disable-c-mbchar
 % gmake
 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc 
 % gmake all; gmake install
</pre>

 <p><b>Common Problem:</b> You may get error messages regarding the fact
 that LLVM does not support inline assembly. Here are two common
 fixes:</p>

 <ul>
  <li><p><b>Fix 1:</b> If you have system header files that include
   inline assembly, you may have to modify them to remove the inline
   assembly, and install the modified versions in
   <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.</li>

  <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
   haven't tried yet, you will probably have to edit the appropriate
   version of atomicity.h under
   <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
   and apply a patch so that it does not use inline assembly.</li>
 </ul>

 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
 to a new architecture, or compiling in a different configuration that we have
 previously, there are probably several changes you will have to make to the GCC
 target to get it to work correctly.  These include:<p>

 <ul>
  <li>Often targets include special or assembler linker flags which
      <tt>gccas</tt>/<tt>gccld</tt> does not understand.  In general, these can
      just be removed.</li>
  <li>LLVM currently does not support any floating point values other than 
      32-bit and 64-bit IEEE floating point.  The primary effect of this is
      that you may have to map "long double" onto "double".</li>
  <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
      These may need to be disabled.</li>
  <li>No inline assembly for position independent code.  At the LLVM level,
      everything is position independent.</li>
  <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
  <li>You may have to disable multilib support in your target.  Using multilib
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