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Misha Brukmanb9e57892003-10-28 21:09:29 +0000[diff] [blame^]6 <title>Bootstrapping the LLVM C/C++ Front-End</title>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]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">
Misha Brukmanb9e57892003-10-28 21:09:29 +0000[diff] [blame^]11 Bootstrapping the LLVM C/C++ Front-End
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]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
Misha Brukmanb9e57892003-10-28 21:09:29 +0000[diff] [blame^]18process, and you should <b>only</b> try to do it if:</p>
19
20<ol>
21 <li>you really, really, really can't use the binaries we distribute</li>
22 <li>you need GCC to fix some of the header files on your system</li>
23 <li>you are an elite GCC hacker.</li>
24</ol>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]25
26<p>We welcome patches to help make this process simpler.</p>
27
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]28<!-- *********************************************************************** -->
29<div class="doc_section">
30 <a name="instructions">Instructions</a>
31</div>
32<!-- *********************************************************************** -->
33
34<div class="doc_text">
35<p>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]36<ol>
37<li><p>Configure and build the LLVM libraries and tools using:</p>
38<pre>
39 % cd llvm
40 % ./configure [options...]
41 % gmake tools-only
42</pre>
43 <p>The use of the non-default target "tools-only" means that the
44 LLVM tools and libraries will build, and the binaries will be
45 deposited in llvm/tools/Debug, but the runtime (bytecode)
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]46 libraries will not build.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]47
48<li><p>Add the directory containing the tools to your PATH.</p>
49<pre>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]50 % set path = ( `cd llvm/tools/Debug &amp;&amp; pwd` $path )
51</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]52
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]53<li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]54
55<li><p>Edit src/configure. Change the first line (starting w/ #!) to
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]56 contain the correct full pathname of sh.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]57
58<li><p>Make "build" and "install" directories as siblings of the "src"
59 tree.</p>
60<pre>
61 % pwd
62 /usr/local/example/cfrontend/src
63 % cd ..
64 % mkdir build install
65 % set CFEINSTALL = `pwd`/install
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]66</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]67
68<li><p>Configure, build and install the C front-end:</p>
69<pre>
70 % cd build
71 % ../src/configure --prefix=$CFEINSTALL --disable-nls --disable-shared \
72 --enable-languages=c,c++
73 % gmake all-gcc
74 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
75 % gmake all; gmake install
76</pre>
77
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]78 <p><b>Common Problem:</b> You may get error messages regarding the fact
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]79 that LLVM does not support inline assembly. Here are two common
80 fixes:</p>
81
82 <ul>
83 <li><p><b>Fix 1:</b> If you have system header files that include
84 inline assembly, you may have to modify them to remove the inline
85 assembly, and install the modified versions in
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]86 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code>.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]87
88 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
89 haven't tried yet, you will probably have to edit the appropriate
90 version of atomicity.h under
91 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]92 and apply a patch so that it does not use inline assembly.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]93 </ul>
94
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]95 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
96 to a new architecture, or compiling in a different configuration that we have
97 previously, there are probably several changes you will have to make to the GCC
98 target to get it to work correctly. These include:<p>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]99
100 <ul>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]101 <li>Often targets include special or assembler linker flags which
102 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
103 just be removed.</li>
104 <li>LLVM currently does not support any floating point values other than
105 32-bit and 64-bit IEEE floating point. The primary effect of this is
106 that you may have to map "long double" onto "double".</li>
107 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
108 These may need to be disabled.</li>
109 <li>No inline assembly for position independent code. At the LLVM level,
110 everything is position independent.</li>
111 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
Chris Lattner13964e02003-10-24 16:02:34 +0000[diff] [blame]112 <li>You may have to disable multilib support in your target. Using multilib
113 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
114 options to the link line, which do not relate to LLVM and confuse
115 <tt>gccld</tt>. To disable multilibs, delete any
116 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]117 <li>Did we mention that we don't support inline assembly? You'll probably
118 have to add some fixinclude hacks to disable it in the system
119 headers.</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]120 </ul>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]121</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]122
123<li><p>Go back into the LLVM source tree proper. Edit Makefile.config
124to redefine <code>LLVMGCCDIR</code> to the full pathname of the
125<code>$CFEINSTALL</code> directory, which is the directory you just
126installed the C front-end into. (The ./configure script is likely to
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]127have set this to a directory which does not exist on your system.)</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]128
129<li><p>If you edited header files during the C/C++ front-end build as
130described in "Fix 1" above, you must now copy those header files from
131<code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code> to
132<code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.
133(This should be the "include" directory in the same directory as the
134libgcc.a library, which you can find by running
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]135<code>$CFEINSTALL/bin/gcc --print-libgcc-file-name</code>.)</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]136
137<li><p>Build and install the runtime (bytecode) libraries by running:</p>
138<pre>
139 % gmake -C runtime
140 % mkdir $CFEINSTALL/bytecode-libs
141 % gmake -C runtime install
142 % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/bytecode-libs
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]143</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]144
145<li><p>Test the newly-installed C frontend by one or more of the
146following means:</p>
147 <ul>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]148 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
149 <li> running the tests under <tt>test/Programs</tt> using <code>gmake -C
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]150 test/Programs</code></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]151 </ul>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]152 </p>
153</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]154</ol>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]155</div>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]156
157<!-- *********************************************************************** -->
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]158
Misha Brukmanb9e57892003-10-28 21:09:29 +0000[diff] [blame^]159<hr>
160<div class="doc_footer">
161 <address><a href="mailto:gaeke -at- uiuc.edu">Brian Gaeke</a></address>
162 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
163 <br>
164 Last modified: $Date$
165</div>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]166
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]167</body>
168</html>