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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / d9ad5b329f73e36f7f539438867340b98068b857 / . / docs / GettingStarted.html
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2<html>
3 <head>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]4 <title>Getting Started with LLVM System</title>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]5 </head>
6
Chris Lattner945de2d2002-07-24 19:59:33 +0000[diff] [blame]7 <body bgcolor=white>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]8 <center><h1>Getting Started with the LLVM System<br><font size=3>By: <a
9 href="mailto:gshi1@uiuc.edu">Guochun Shi</a>,
10 <a href="mailto:sabre@nondot.org">Chris Lattner</a> and
11 <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>
12 </font></h1></center>
13
14 <!--=====================================================================-->
15 <h2><a name="Contents">Contents</a></h2>
16 <!--=====================================================================-->
Chris Lattner945de2d2002-07-24 19:59:33 +0000[diff] [blame]17
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]18 <ul>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]19 <li><a href="#overview">Overview</a>
20 <li><a href="#starting">Getting started with LLVM</a>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]21 <ol>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]22 <li><a href="#quickstart">Getting started quickly (a summary)</a>
23 <li><a href="#checkout">Checkout LLVM from CVS</a>
24 <li><a href="#terminology">Terminology and Notation</tt></a>
25 <li><a href="#objfiles">The location for object files</tt></a>
26 <li><a href="#config">Local Configuration Options</tt></a>
27 <li><a href="#environment">Setting up your environment</a>
28 <li><a href="#compile">Compiling the source code</a>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]29 </ol>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]30 <li><a href="#layout">Program layout</a>
31 <ol>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]32 <li><a href="#cvsdir">CVS directories</a>
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]33 <li><a href="#dd"><tt>Depend</tt>, <tt>Debug</tt>, &amp;
34 <tt>Release</tt> directories</a></li>
35 <li><a href="#include"><tt>llvm/include</tt></a>
36 <li><a href="#lib"><tt>llvm/lib</tt></a>
37 <li><a href="#test"><tt>llvm/test</tt></a>
38 <li><a href="#tools"><tt>llvm/tools</tt></a>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]39 </ol>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]40 <li><a href="#tutorial">An example using the LLVM tool chain</a>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]41 <li><a href="#links">Links</a>
42 </ul>
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]43
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]44
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]45 <!--=====================================================================-->
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]46 <center>
47 <h2><a name="overview"><b>Overview</b></a></h2>
48 </center>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]49 <!--=====================================================================-->
50
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]51 <p>The <a href"starting">next section</a> of this guide is meant to get
52 you up and running with LLVM, and to give you some basic information about
53 the LLVM environment. The <a href"#quickstart">first subsection</a> gives
54 a short summary for those who are already familiar with the system and
55 want to get started as quickly as possible.
56
57 <p>The later sections of this guide describe the <a
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]58 href"#layout">general layout</a> of the the LLVM source-tree, a <a
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]59 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
60 href="#links">links</a> to find more information about LLVM or to get
61 help via e-mail.
62
63 <!--=====================================================================-->
64 <center>
65 <h2><a name="starting"><b>Getting Started</b></a></h2>
66 </center>
67 <!--=====================================================================-->
68
69
70 <!--=====================================================================-->
71 <h3><a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a></h3>
72 <!--=====================================================================-->
73
74 Here's the short story for getting up and running quickly with LLVM:
Chris Lattner96768ea2003-02-14 04:22:13 +0000[diff] [blame]75 <ol>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]76 <li>Find the path to the CVS repository containing LLVM (we'll call this <i>CVSROOTDIR</i>).
77 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
78 <li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]79 <li><tt>cd llvm</tt>
Chris Lattner96768ea2003-02-14 04:22:13 +0000[diff] [blame]80 <li>Edit <tt>Makefile.config</tt> to set local paths. This includes
81 setting the install location of the C frontend, and the various paths
82 to the C and C++ compilers used to build LLVM itself.
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]83 <li><tt>gmake -k |& tee gnumake.out
84 &nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt>
Chris Lattner96768ea2003-02-14 04:22:13 +0000[diff] [blame]85 </ol>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]86
87 <p>See <a href="#environment">Setting up your environment</a> on tips to
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]88 simplify working with the LLVM front-end and compiled tools. See the
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]89 other sub-sections below for other useful details in working with LLVM,
90 or go straight to <a href="#layout">Program Layout</a> to learn about the
91 layout of the source code tree.
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]92
93 <!------------------------------------------------------------------------->
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]94 <h3><a name="terminology">Terminology and Notation</a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]95 <!------------------------------------------------------------------------->
96
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]97 <p>Through this manual, the following names are used to denote paths
98 specific to the local system and working environment. <i>These are not
99 environment variables you need to set, but just strings used in the rest
100 of this document below.</i>. In any of the examples below, simply replace
101 each of these names with the appropriate pathname on your local system.
102 All these paths are absolute:</p>
103 <ul>
104 </ul>
Chris Lattnercefbd322002-08-13 21:10:30 +0000[diff] [blame]105
106 <!------------------------------------------------------------------------->
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]107 <h3><a name="checkout">Checkout LLVM from CVS</a></h3>
Chris Lattnercefbd322002-08-13 21:10:30 +0000[diff] [blame]108 <!------------------------------------------------------------------------->
109
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]110 <p>Before checking out the source code, you will need to know the path to
111 CVS repository containing LLVM source code (we'll call this
112 <i>CVSROOTDIR</i> below). Ask the person responsible for your local LLVM
113 installation to give you this path.
Chris Lattnercefbd322002-08-13 21:10:30 +0000[diff] [blame]114
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]115 <p>To get a fresh copy of the entire source code, all you
116 need to do is check it out from CVS as follows:
117 <ul>
118 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
119 <li><tt>cvs -d <i>CVSROOTDIR</i> checkout llvm</tt></p>
120 </ul>
121
122 <p>This will create an '<tt>llvm</tt>' directory in the current
123 directory and fully populate it with the LLVM source code, Makefiles,
124 test directories, and local copies of documentation files.</p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]125
126 <!------------------------------------------------------------------------->
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]127 <h3><a name="config">Local Configuration Options</a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]128 <!------------------------------------------------------------------------->
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]129
130 <p>The file <tt>llvm/Makefile.config</tt>
131 defines the following path variables,
132 which are specific to a particular installation of LLVM.
133 These should need to be modified only once after checking out a copy
134 of LLVM (if the default values do not already match your system):
135
136 <ul>
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]137 <p><li><i>CXX</i> = Path to C++ compiler to use.
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]138 <p><li><i>LLVM_OBJ_DIR</i> = Path to the llvm directory where
139 object files should be placed.
140 (See the Section on <a href=#objfiles>
141 The location for LLVM object files</a>
142 for more information.)
143 <p><li><i>LLVMGCCDIR</i> = Path to the location of the LLVM front-end
144 binaries and associated libraries.
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]145 <p><li><i>PURIFY</i> = Path to the purify program.
146 </ul>
147
148 <!------------------------------------------------------------------------->
149 <h3><a name="objfiles">The location for LLVM object files</a></h3>
150 <!------------------------------------------------------------------------->
151
152 <p>The LLVM make system sends most output files generated during the build
153 into the directory defined by the variable LLVM_OBJ_DIR in
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]154 <tt>llvm/Makefile.config</tt>. This can be either just your normal LLVM
155 source tree or some other directory writable by you. You may wish to put
156 object files on a different filesystem either to keep them from being backed
157 up or to speed up local builds.
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]158
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]159 <p>If you do not wish to use a different location for object files (building
160 into the source tree directly), just set this variable to ".".<p>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]161
162 <!------------------------------------------------------------------------->
163 <h3><a name="environment">Setting up your environment</a></h3>
164 <!------------------------------------------------------------------------->
165
166 <i>NOTE: This step is optional but will set up your environment so you
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]167 can use the compiled LLVM tools with as little hassle as
168 possible.</i>)
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]169
170 <p>Add the following lines to your <tt>.cshrc</tt> (or the corresponding
171 lines to your <tt>.profile</tt> if you use a bourne shell derivative).
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]172
173 <pre>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]174 # Make the C front end easy to use...
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]175 alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/llvm-gcc</tt>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]176
177 # Make the LLVM tools easy to use...
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]178 setenv PATH <i>LLVM_OBJ_DIR</i>/tools/Debug:${PATH}
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]179 </pre>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]180 The <tt>llvmgcc</tt> alias is useful because the C compiler is not
181 included in the CVS tree you just checked out.
182
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]183 <p>The other <a href="#tools">LLVM tools</a> are part of the LLVM
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]184 source base, and built when compiling LLVM. They will be built into the
185 <tt><i>LLVM_OBJ_DIR</i>/tools/Debug</tt> directory.</p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]186
187 <!------------------------------------------------------------------------->
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]188 <h3><a name="compile">Compiling the source code</a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]189 <!------------------------------------------------------------------------->
190
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]191 <p>Every directory in the LLVM source tree includes a <tt>Makefile</tt> to
192 build it, and any subdirectories that it contains. These makefiles require
193 that you use <tt>gmake</tt>, instead of <tt>make</tt> to build them, but can
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]194 otherwise be used freely. To build the entire LLVM system, just enter the
195 top level <tt>llvm</tt> directory and type <tt>gmake</tt>. A few minutes
196 later you will hopefully have a freshly compiled toolchain waiting for you
197 in <tt>llvm/tools/Debug</tt>. If you want to look at the libraries that
198 were compiled, look in <tt>llvm/lib/Debug</tt>.</p>
199
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]200 If you get an error talking about a <tt>/localhome</tt> directory, follow
201 the instructions in the section about <a href="#environment">Setting Up Your
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]202 Environment.</a>
Chris Lattnercefbd322002-08-13 21:10:30 +0000[diff] [blame]203
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]204
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]205
206 <!--=====================================================================-->
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]207 <center>
208 <h2><a name="layout"><b>Program Layout</b></a></h2>
209 </center>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]210 <!--=====================================================================-->
211
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]212 <p>One useful source of infomation about the LLVM sourcebase is the LLVM <a
213 href="http://www.doxygen.org">doxygen</a> documentation, available at <tt><a
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]214 href="http://llvm.cs.uiuc.edu/doxygen/">http://llvm.cs.uiuc.edu/doxygen/</a></tt>. The
215 following is a brief introduction to code layout:</p>
216
217
218 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]219 <h3><a name="cvsdir"><tt>CVS</tt> directories</a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]220 <!------------------------------------------------------------------------->
221
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]222 Every directory checked out of CVS will contain a <tt>CVS</tt> directory,
223 for the most part these can just be ignored.
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]224
225
226 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]227 <h3><a name="ddr"><tt>Depend</tt>, <tt>Debug</tt>, &amp; <tt>Release</tt>
228 directories</a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]229 <!------------------------------------------------------------------------->
230
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]231 If you are building with the "<tt>BUILD_ROOT=.</tt>" option enabled in the
232 <tt>Makefile.common</tt> file, most source directories will contain two
233 directories, <tt>Depend</tt> and <tt>Debug</tt>. The <tt>Depend</tt>
234 directory contains automatically generated dependance files which are used
235 during compilation to make sure that source files get rebuilt if a header
236 file they use is modified. The <tt>Debug</tt> directory holds the object
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]237 files, library files and executables that are used for building a debug
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]238 enabled build. The <tt>Release</tt> directory is created to hold the same
239 files when the <tt>ENABLE_OPTIMIZED=1</tt> flag is passed to <tt>gmake</tt>,
240 causing an optimized built to be performed.<p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]241
242
243 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]244 <h3><a name="include"><tt>llvm/include</tt></a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]245 <!------------------------------------------------------------------------->
246
247 This directory contains public header files exported from the LLVM
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]248 library. The two main subdirectories of this directory are:<p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]249
250 <ol>
251 <li><tt>llvm/include/llvm</tt> - This directory contains all of the LLVM
252 specific header files. This directory also has subdirectories for
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]253 different portions of LLVM: <tt>Analysis</tt>, <tt>CodeGen</tt>,
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]254 <tt>Reoptimizer</tt>, <tt>Target</tt>, <tt>Transforms</tt>, etc...
255
256 <li><tt>llvm/include/Support</tt> - This directory contains generic
257 support libraries that are independant of LLVM, but are used by LLVM.
258 For example, some C++ STL utilities and a Command Line option processing
259 library.
260 </ol>
261
262 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]263 <h3><a name="lib"><tt>llvm/lib</tt></a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]264 <!------------------------------------------------------------------------->
265
266 This directory contains most source files of LLVM system. In LLVM almost all
267 code exists in libraries, making it very easy to share code among the
268 different <a href="#tools">tools</a>.<p>
269
270 <dl compact>
271 <dt><tt>llvm/lib/VMCore/</tt><dd> This directory holds the core LLVM
272 source files that implement core classes like Instruction and BasicBlock.
273
274 <dt><tt>llvm/lib/AsmParser/</tt><dd> This directory holds the source code
275 for the LLVM assembly language parser library.
276
277 <dt><tt>llvm/lib/ByteCode/</tt><dd> This directory holds code for reading
278 and write LLVM bytecode.
279
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]280 <dt><tt>llvm/lib/CWriter/</tt><dd> This directory implements the LLVM to C
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]281 converter.
282
283 <dt><tt>llvm/lib/Analysis/</tt><dd> This directory contains a variety of
284 different program analyses, such as Dominator Information, Call Graphs,
285 Induction Variables, Interval Identification, Natural Loop Identification,
286 etc...
287
288 <dt><tt>llvm/lib/Transforms/</tt><dd> This directory contains the source
289 code for the LLVM to LLVM program transformations, such as Aggressive Dead
290 Code Elimination, Sparse Conditional Constant Propogation, Inlining, Loop
291 Invarient Code Motion, Dead Global Elimination, Pool Allocation, and many
292 others...
293
294 <dt><tt>llvm/lib/Target/</tt><dd> This directory contains files that
295 describe various target architectures for code generation. For example,
296 the llvm/lib/Target/Sparc directory holds the Sparc machine
297 description.<br>
298
299 <dt><tt>llvm/lib/CodeGen/</tt><dd> This directory contains the major parts
300 of the code generator: Instruction Selector, Instruction Scheduling, and
301 Register Allocation.
302
303 <dt><tt>llvm/lib/Reoptimizer/</tt><dd> This directory holds code related
304 to the runtime reoptimizer framework that is currently under development.
305
306 <dt><tt>llvm/lib/Support/</tt><dd> This directory contains the source code
307 that corresponds to the header files located in
308 <tt>llvm/include/Support/</tt>.
309 </dl>
310
311 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]312 <h3><a name="test"><tt>llvm/test</tt></a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]313 <!------------------------------------------------------------------------->
314
315 <p>This directory contains regression tests and source code that is used to
316 test the LLVM infrastructure...</p>
317
318 <!------------------------------------------------------------------------->
Chris Lattner44ac6592002-08-09 16:14:56 +0000[diff] [blame]319 <h3><a name="tools"><tt>llvm/tools</tt></a></h3>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]320 <!------------------------------------------------------------------------->
321
322 <p>The <b>tools</b> directory contains the executables built out of the
323 libraries above, which form the main part of the user interface. You can
324 always get help for a tool by typing <tt>tool_name --help</tt>. The
325 following is a brief introduction to the most important tools.</p>
326
327 <dl compact>
328 <dt><tt><b>as</b></tt><dd>The assembler transforms the human readable
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]329 LLVM assembly to LLVM bytecode.<p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]330
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]331 <dt><tt><b>dis</b></tt><dd>The disassembler transforms the LLVM bytecode
332 to human readable LLVM assembly. Additionally it can convert LLVM
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]333 bytecode to C, which is enabled with the <tt>-c</tt> option.<p>
334
335 <dt><tt><b>lli</b></tt><dd> <tt>lli</tt> is the LLVM interpreter, which
336 can directly execute LLVM bytecode (although very slowly...). In addition
337 to a simple intepreter, <tt>lli</tt> is also has debugger and tracing
338 modes (entered by specifying <tt>-debug</tt> or <tt>-trace</tt> on the
339 command line, respectively).<p>
340
341 <dt><tt><b>llc</b></tt><dd> <tt>llc</tt> is the LLVM backend compiler,
342 which translates LLVM bytecode to a SPARC assembly file.<p>
343
344 <dt><tt><b>llvmgcc</b></tt><dd> <tt>llvmgcc</tt> is a GCC based C frontend
345 that has been retargeted to emit LLVM code as the machine code output. It
346 works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
347 -o</tt> options that are typically used. The source code for the
348 <tt>llvmgcc</tt> tool is currently not included in the LLVM cvs tree
349 because it is quite large and not very interesting.<p>
350
351 <ol>
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]352 <dt><tt><b>gccas</b></tt><dd> This tool is invoked by the
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]353 <tt>llvmgcc</tt> frontend as the "assembler" part of the compiler. This
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]354 tool actually assembles LLVM assembly to LLVM bytecode,
355 performs a variety of optimizations,
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]356 and outputs LLVM bytecode. Thus when you invoke <tt>llvmgcc -c x.c -o
357 x.o</tt>, you are causing <tt>gccas</tt> to be run, which writes the
358 <tt>x.o</tt> file (which is an LLVM bytecode file that can be
359 disassembled or manipulated just like any other bytecode file). The
360 command line interface to <tt>gccas</tt> is designed to be as close as
Chris Lattner96768ea2003-02-14 04:22:13 +0000[diff] [blame]361 possible to the <b>system</b> '<tt>as</tt>' utility so that the gcc
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]362 frontend itself did not have to be modified to interface to a "wierd"
363 assembler.<p>
364
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]365 <dt><tt><b>gccld</b></tt><dd> <tt>gccld</tt> links together several LLVM
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]366 bytecode files into one bytecode file and does some optimization. It is
367 the linker invoked by the gcc frontend when multiple .o files need to be
368 linked together. Like <tt>gccas</tt> the command line interface of
369 <tt>gccld</tt> is designed to match the system linker, to aid
370 interfacing with the GCC frontend.<p>
371 </ol>
372
Chris Lattner4b2e2912002-09-19 19:56:53 +0000[diff] [blame]373 <dt><tt><b>opt</b></tt><dd> <tt>opt</tt> reads LLVM bytecode, applies a
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]374 series of LLVM to LLVM transformations (which are specified on the command
375 line), and then outputs the resultant bytecode. The '<tt>opt --help</tt>'
376 command is a good way to get a list of the program transformations
377 available in LLVM.<p>
378
379
380 <dt><tt><b>analyze</b></tt><dd> <tt>analyze</tt> is used to run a specific
381 analysis on an input LLVM bytecode file and print out the results. It is
382 primarily useful for debugging analyses, or familiarizing yourself with
383 what an analysis does.<p>
384
385 </dl>
386
387 <!--=====================================================================-->
388 <h2><a name="tutorial">An example using the LLVM tool chain</h2>
389 <!--=====================================================================-->
390
391 <ol>
392 <li>First, create a simple C file, name it 'hello.c':
393 <pre>
394 #include &lt;stdio.h&gt;
395 int main() {
396 printf("hello world\n");
397 return 0;
398 }
399 </pre>
400
401 <li>Next, compile the C file into a LLVM bytecode file:<p>
402
403 <tt>% llvmgcc hello.c -o hello</tt><p>
404
405 This will create two result files: <tt>hello</tt> and
406 <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
407 corresponds the the compiled program and the library facilities that it
408 required. <tt>hello</tt> is a simple shell script that runs the bytecode
409 file with <tt>lli</tt>, making the result directly executable.<p>
410
411 <li>Run the program. To make sure the program ran, execute one of the
412 following commands:<p>
413
414 <tt>% ./hello</tt><p>
415
416 or<p>
417
418 <tt>% lli hello.bc</tt><p>
419
420 <li>Use the <tt>dis</tt> utility to take a look at the LLVM assembly
421 code:<p>
422
423 <tt>% dis < hello.bc | less</tt><p>
424
425 <li>Compile the program to native Sparc assembly using the code
426 generator:<p>
427
428 <tt>% llc hello.bc -o hello.s</tt><p>
429
430 <li>Assemble the native sparc assemble file into a program:<p>
431
432 <tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc</tt><p>
433
434 <li>Execute the native sparc program:<p>
435
436 <tt>% ./hello.sparc</tt><p>
437
438 </ol>
439
440
441 <!--=====================================================================-->
442 <h2><a name="links">Links</a></h2>
443 <!--=====================================================================-->
444
445 <p>This document is just an <b>introduction</b> to how to use LLVM to do
446 some simple things... there are many more interesting and complicated things
447 that you can do that aren't documented here (but we'll gladly accept a patch
448 if you want to write something up!). For more information about LLVM, check
449 out:</p>
450
451 <ul>
452 <li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
453 <li><a href="http://tank.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li>
454 </ul>
455
456 <hr>
457
458 If you have any questions or run into any snags (or you have any
Chris Lattner1db872d2002-09-06 16:26:13 +0000[diff] [blame]459 additions...), please send an email to
460 <a href="mailto:hldnbrnd@uiuc.edu">Nicholas Hildenbrandt</a> or
461 <a href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
Chris Lattner7fe7f812002-07-24 19:51:14 +0000[diff] [blame]462
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]463 <!-- Created: Mon Jul 1 02:29:02 CDT 2002 -->
464 <!-- hhmts start -->
Chris Lattner96768ea2003-02-14 04:22:13 +0000[diff] [blame]465Last modified: Thu Feb 13 22:20:39 CST 2003
Guochun Shif4688a82002-07-17 23:05:56 +0000[diff] [blame]466<!-- hhmts end -->
467 </body>
468</html>