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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
Brian Gaeke7af03e92003-11-12 20:47:30 +0000[diff] [blame^]14<ol>
15 <li><a href="#cautionarynote">A Cautionary Note</a>
16 <li><a href="#instructions">Instructions</a>
17</ol>
18
19<div class="doc_text">
20 <p><b>Written by Brian R. Gaeke</b></p>
21</div>
22
23<!-- *********************************************************************** -->
24<div class="doc_section">
25 <a name="cautionarynote">A Cautionary Note</a>
26</div>
27<!-- *********************************************************************** -->
28
29<div class="doc_text">
30<p>This document is intended to explain the process of building the
31LLVM C/C++ front-end, based on GCC 3.4, from its source code. You
32would have to do this, for example, if you are porting LLVM to a new
33architecture or operating system.</p>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]34
35<p><b>NOTE:</b> This is currently a somewhat fragile, error-prone
Misha Brukmanb9e57892003-10-28 21:09:29 +0000[diff] [blame]36process, and you should <b>only</b> try to do it if:</p>
37
38<ol>
39 <li>you really, really, really can't use the binaries we distribute</li>
40 <li>you need GCC to fix some of the header files on your system</li>
41 <li>you are an elite GCC hacker.</li>
42</ol>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]43
44<p>We welcome patches to help make this process simpler.</p>
Brian Gaeke7af03e92003-11-12 20:47:30 +0000[diff] [blame^]45</div>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]46
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]47<!-- *********************************************************************** -->
48<div class="doc_section">
49 <a name="instructions">Instructions</a>
50</div>
51<!-- *********************************************************************** -->
52
53<div class="doc_text">
54<p>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]55<ol>
56<li><p>Configure and build the LLVM libraries and tools using:</p>
57<pre>
58 % cd llvm
59 % ./configure [options...]
60 % gmake tools-only
61</pre>
62 <p>The use of the non-default target "tools-only" means that the
63 LLVM tools and libraries will build, and the binaries will be
64 deposited in llvm/tools/Debug, but the runtime (bytecode)
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]65 libraries will not build.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]66
67<li><p>Add the directory containing the tools to your PATH.</p>
68<pre>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]69 % set path = ( `cd llvm/tools/Debug &amp;&amp; pwd` $path )
70</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]71
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]72<li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]73
74<li><p>Edit src/configure. Change the first line (starting w/ #!) to
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]75 contain the correct full pathname of sh.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]76
77<li><p>Make "build" and "install" directories as siblings of the "src"
78 tree.</p>
79<pre>
80 % pwd
81 /usr/local/example/cfrontend/src
82 % cd ..
83 % mkdir build install
84 % set CFEINSTALL = `pwd`/install
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]85</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]86
87<li><p>Configure, build and install the C front-end:</p>
88<pre>
89 % cd build
90 % ../src/configure --prefix=$CFEINSTALL --disable-nls --disable-shared \
91 --enable-languages=c,c++
92 % gmake all-gcc
93 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
94 % gmake all; gmake install
95</pre>
96
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]97 <p><b>Common Problem:</b> You may get error messages regarding the fact
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]98 that LLVM does not support inline assembly. Here are two common
99 fixes:</p>
100
101 <ul>
102 <li><p><b>Fix 1:</b> If you have system header files that include
103 inline assembly, you may have to modify them to remove the inline
104 assembly, and install the modified versions in
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]105 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code>.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]106
107 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
108 haven't tried yet, you will probably have to edit the appropriate
109 version of atomicity.h under
110 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]111 and apply a patch so that it does not use inline assembly.</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]112 </ul>
113
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]114 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
115 to a new architecture, or compiling in a different configuration that we have
116 previously, there are probably several changes you will have to make to the GCC
117 target to get it to work correctly. These include:<p>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]118
119 <ul>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]120 <li>Often targets include special or assembler linker flags which
121 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
122 just be removed.</li>
123 <li>LLVM currently does not support any floating point values other than
124 32-bit and 64-bit IEEE floating point. The primary effect of this is
125 that you may have to map "long double" onto "double".</li>
126 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
127 These may need to be disabled.</li>
128 <li>No inline assembly for position independent code. At the LLVM level,
129 everything is position independent.</li>
130 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
Chris Lattner13964e02003-10-24 16:02:34 +0000[diff] [blame]131 <li>You may have to disable multilib support in your target. Using multilib
132 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
133 options to the link line, which do not relate to LLVM and confuse
134 <tt>gccld</tt>. To disable multilibs, delete any
135 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]136 <li>Did we mention that we don't support inline assembly? You'll probably
137 have to add some fixinclude hacks to disable it in the system
138 headers.</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]139 </ul>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]140</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]141
142<li><p>Go back into the LLVM source tree proper. Edit Makefile.config
143to redefine <code>LLVMGCCDIR</code> to the full pathname of the
144<code>$CFEINSTALL</code> directory, which is the directory you just
145installed the C front-end into. (The ./configure script is likely to
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]146have set this to a directory which does not exist on your system.)</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]147
148<li><p>If you edited header files during the C/C++ front-end build as
149described in "Fix 1" above, you must now copy those header files from
150<code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code> to
151<code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.
152(This should be the "include" directory in the same directory as the
153libgcc.a library, which you can find by running
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]154<code>$CFEINSTALL/bin/gcc --print-libgcc-file-name</code>.)</p></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]155
156<li><p>Build and install the runtime (bytecode) libraries by running:</p>
157<pre>
158 % gmake -C runtime
159 % mkdir $CFEINSTALL/bytecode-libs
160 % gmake -C runtime install
161 % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/bytecode-libs
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]162</pre></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]163
164<li><p>Test the newly-installed C frontend by one or more of the
165following means:</p>
166 <ul>
Chris Lattnere38c6282003-10-23 03:55:23 +0000[diff] [blame]167 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
168 <li> running the tests under <tt>test/Programs</tt> using <code>gmake -C
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]169 test/Programs</code></li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]170 </ul>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]171 </p>
172</li>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]173</ol>
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]174</div>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]175
176<!-- *********************************************************************** -->
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]177
Misha Brukmanb9e57892003-10-28 21:09:29 +0000[diff] [blame]178<hr>
179<div class="doc_footer">
Brian Gaeke7af03e92003-11-12 20:47:30 +0000[diff] [blame^]180 <address>Brian Gaeke</address>
Misha Brukmanb9e57892003-10-28 21:09:29 +0000[diff] [blame]181 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
182 <br>
183 Last modified: $Date$
184</div>
Brian Gaeke46079d22003-10-21 21:58:38 +0000[diff] [blame]185
Misha Brukman83bd33a2003-10-23 01:48:33 +0000[diff] [blame]186</body>
187</html>