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3<head>
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5 <link rel="stylesheet" href="llvm.css" type="text/css" media="screen" />
6 <title>Bootstrapping the C/C++ Front-End</title>
7</head>
8<body>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]9
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]10<div class="doc_title">
11 Bootstrapping the C/C++ Front-End
12</div>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]13
14<p>This document is intended to explain the process of building the LLVM
15C/C++ front-end, based on GCC 3.4, from source.</p>
16
17<p><b>NOTE:</b> This is currently a somewhat fragile, error-prone
18process, and you should only try to do it if (A) you really, really,
19really can't use the binaries we distribute, and (B) you are a wicked
20good GCC hacker.</p>
21
22<p>We welcome patches to help make this process simpler.</p>
23
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]24<!-- *********************************************************************** -->
25<div class="doc_section">
26 <a name="instructions">Instructions</a>
27</div>
28<!-- *********************************************************************** -->
29
30<div class="doc_text">
31<p>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]32<ol>
33<li><p>Configure and build the LLVM libraries and tools using:</p>
34<pre>
35 % cd llvm
36 % ./configure [options...]
37 % gmake tools-only
38</pre>
39 <p>The use of the non-default target "tools-only" means that the
40 LLVM tools and libraries will build, and the binaries will be
41 deposited in llvm/tools/Debug, but the runtime (bytecode)
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]42 libraries will not build.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]43
44<li><p>Add the directory containing the tools to your PATH.</p>
45<pre>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]46 % set path = ( `cd llvm/tools/Debug &amp;&amp; pwd` $path )
47</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]48
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]49<li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]50
51<li><p>Edit src/configure. Change the first line (starting w/ #!) to
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]52 contain the correct full pathname of sh.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]53
54<li><p>Make "build" and "install" directories as siblings of the "src"
55 tree.</p>
56<pre>
57 % pwd
58 /usr/local/example/cfrontend/src
59 % cd ..
60 % mkdir build install
61 % set CFEINSTALL = `pwd`/install
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]62</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]63
64<li><p>Configure, build and install the C front-end:</p>
65<pre>
66 % cd build
67 % ../src/configure --prefix=$CFEINSTALL --disable-nls --disable-shared \
68 --enable-languages=c,c++
69 % gmake all-gcc
70 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
71 % gmake all; gmake install
72</pre>
73
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]74 <p><b>Common Problem:</b> You may get error messages regarding the fact
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]75 that LLVM does not support inline assembly. Here are two common
76 fixes:</p>
77
78 <ul>
79 <li><p><b>Fix 1:</b> If you have system header files that include
80 inline assembly, you may have to modify them to remove the inline
81 assembly, and install the modified versions in
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]82 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code>.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]83
84 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
85 haven't tried yet, you will probably have to edit the appropriate
86 version of atomicity.h under
87 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]88 and apply a patch so that it does not use inline assembly.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]89 </ul>
90
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]91 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
92 to a new architecture, or compiling in a different configuration that we have
93 previously, there are probably several changes you will have to make to the GCC
94 target to get it to work correctly. These include:<p>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]95
96 <ul>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]97 <li>Often targets include special or assembler linker flags which
98 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
99 just be removed.</li>
100 <li>LLVM currently does not support any floating point values other than
101 32-bit and 64-bit IEEE floating point. The primary effect of this is
102 that you may have to map "long double" onto "double".</li>
103 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
104 These may need to be disabled.</li>
105 <li>No inline assembly for position independent code. At the LLVM level,
106 everything is position independent.</li>
107 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
Chris Lattner13964e02003-10-24 16:02:34 +0000[diff] [blame^]108 <li>You may have to disable multilib support in your target. Using multilib
109 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
110 options to the link line, which do not relate to LLVM and confuse
111 <tt>gccld</tt>. To disable multilibs, delete any
112 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]113 <li>Did we mention that we don't support inline assembly? You'll probably
114 have to add some fixinclude hacks to disable it in the system
115 headers.</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]116 </ul>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]117</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]118
119<li><p>Go back into the LLVM source tree proper. Edit Makefile.config
120to redefine <code>LLVMGCCDIR</code> to the full pathname of the
121<code>$CFEINSTALL</code> directory, which is the directory you just
122installed the C front-end into. (The ./configure script is likely to
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]123have set this to a directory which does not exist on your system.)</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]124
125<li><p>If you edited header files during the C/C++ front-end build as
126described in "Fix 1" above, you must now copy those header files from
127<code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code> to
128<code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.
129(This should be the "include" directory in the same directory as the
130libgcc.a library, which you can find by running
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]131<code>$CFEINSTALL/bin/gcc --print-libgcc-file-name</code>.)</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]132
133<li><p>Build and install the runtime (bytecode) libraries by running:</p>
134<pre>
135 % gmake -C runtime
136 % mkdir $CFEINSTALL/bytecode-libs
137 % gmake -C runtime install
138 % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/bytecode-libs
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]139</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]140
141<li><p>Test the newly-installed C frontend by one or more of the
142following means:</p>
143 <ul>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]144 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
145 <li> running the tests under <tt>test/Programs</tt> using <code>gmake -C
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]146 test/Programs</code></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]147 </ul>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]148 </p>
149</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]150</ol>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]151</div>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]152
153<!-- *********************************************************************** -->
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]154
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]155<hr><font size="-1">
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]156<address><a href="mailto:gaeke -at- uiuc.edu">Brian Gaeke</a></address>
157Last modified: $Date$
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]158</font>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]159
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]160</body>
161</html>