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