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- <title>Specification for LLVM system code</title>
+ <title>Getting Started with LLVM System</title>
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<body>
- <h1>Specification for LLVM system</h1>
- <h1><a name="index">Index</a></h1>
+ <h1>Getting Started with the LLVM System</h1>
<ul>
- <li><a href="#cvs">Checkout LLVM from CVS</a>
- <li><a href="#compilerun">Compile and Run</a>
+ <li><a href="#quickstart">Getting started with LLVM</a>
+ <ol>
+ <li><a href="#cvs">Checkout LLVM from CVS</a>
+ <li><a href="#environment">Set up your environment</a>
+ <li><a href="#compile">Compiling the Source Code</a>
+ </ol>
<li><a href="#layout">Program layout</a>
<ol>
- <li><a href="#d&d">Depend and Debug directories</a></li>
+ <li><a href="#cvsdir">CVS directories</a>
+ <li><a href="#dd">Depend, Debug, & Release directories</a></li>
<li><a href="#include">llvm/include</a>
<li><a href="#lib">llvm/lib</a>
<li><a href="#test">llvm/test</a>
<li><a href="#tools">llvm/tools</a>
</ol>
- <li> <a href="#tutorial"> simple example for using tools</li>
+ <li><a href="#tutorial">An example using the LLVM tool chain</a>
<li><a href="#links">Links</a>
</ul>
- <h2><a name="tools">Checkout LLVM from CVS</a></h2>
- <p>
- <dl>
- <dt>cvs root directory:<dd> /home/vadve/vadve/Research/DynOpt/CVSRepository<br>
- <dt>project name:<dd> llvm
- </dl>
+
+
+
+ <!--=====================================================================-->
+ <h2><a name="quickstart">Getting Started with LLVM</a></h2>
+ <!--=====================================================================-->
+
+ <p>This guide is meant to get you up and running with LLVM as quickly as
+ possible. Once you get the basic system running you can choose an area to
+ dive into and learn more about. If you get stuck or something is missing
+ from this document, please email <a
+ href="mailto:sabre@nondot.org">Chris</a>.</p>
+
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="tools">Checkout LLVM from CVS</a></h3>
+ <!------------------------------------------------------------------------->
+
+ <p>First step is to get the actual source code. To do this, all you need to
+ do is check it out from CVS. From your home directory, just enter:</p>
+
+ <p><tt>cvs -d /home/vadve/vadve/Research/DynOpt/CVSRepository checkout llvm</tt></p>
+
+ <p>This will create an '<tt>llvm</tt>' directory in your home directory and fully
+ populate it with the source code for LLVM.</p>
+
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="tools">Set up your environment</a></h3>
+ <!------------------------------------------------------------------------->
- For those who are not familar with cvs, there are two steps you should do:<br>
+ <p>Now that you have the source code available, you should set up your
+ environment to be able to use the LLVM tools (once compiled) with as little
+ hassle as possible. To do this, we recommend that you add the following
+ lines to your <tt>.cshrc</tt> (or the corresponding lines to your
+ <tt>.profile</tt> if you use a bourne shell derivative):
+
+ <pre>
+ # Make the C frontend easy to use...
+ alias llvmgcc /home/vadve/lattner/cvs/gcc_install/bin/gcc
+
+ # Make the LLVM tools easy to use...
+ setenv PATH ~/llvm/tools/Debug:${PATH}
+ </pre>
+
+ <p>The C compiler is not included in the CVS tree you just checked out, so
+ we just point to the cannonical location, and access it with the
+ <tt>llvmgcc</tt> command. The rest of the <a href="#tools">LLVM tools</a>
+ will be built into the llvm/tools/Debug directory inside of the sourcebase.
+ Adding them to your path will make it much easier to use them.</p>
+
+
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="compile">Compiling the Source Code</a></h3>
+ <!------------------------------------------------------------------------->
+
+ <p>Every directory in the LLVM source tree includes a Makefile to build it,
+ and any subdirectories that it contains. These makefiles require that you
+ use <tt>gmake</tt>, instead of <tt>make</tt> to build them, but can
+ otherwise be used freely. To build the entire LLVM system, just enter the
+ top level <tt>llvm</tt> directory and type <tt>gmake</tt>. A few minutes
+ later you will hopefully have a freshly compiled toolchain waiting for you
+ in <tt>llvm/tools/Debug</tt>. If you want to look at the libraries that
+ were compiled, look in <tt>llvm/lib/Debug</tt>.</p>
+
+
+ <!--=====================================================================-->
+ <h2><a name="layout">Program Layout</a></h2>
+ <!--=====================================================================-->
+
+ <p>One useful source of infomation about the LLVM sourcebase is the LLVM
+ doxygen documentation, available at <tt><a
+ href="http://llvm.cs.uiuc.edu/doxygen/">http://llvm.cs.uiuc.edu/doxygen/</a></tt>. The
+ following is a brief introduction to code layout:</p>
+
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="cvsdir">CVS directories</a></h3>
+ <!------------------------------------------------------------------------->
+
+ Every directory checked out of CVS will contain a CVS directory, for the
+ most part these can just be ignored.
+
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="ddr">Depend, Debug, & Release directories</a></h3>
+ <!------------------------------------------------------------------------->
+
+ Most source directories contain two directories, Depend and Debug. The
+ Depend directory contains automatically generated dependance files which are
+ used during compilation to make sure that source files get rebuilt if a
+ header file they use is modified. The Debug directory holds the object
+ files, library files and executables that are used for building a debug
+ enabled build. The Release directory is created to hold the same files when
+ the <tt>ENABLE_OPTIMIZED=1</tt> flag is passed to <tt>gmake</tt>, causing an
+ optimized built to be performed.
+
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="include">llvm/include</a></h3>
+ <!------------------------------------------------------------------------->
+
+ This directory contains public header files exported from the LLVM
+ library. The two main subdirectories of this directory are:
+
<ol>
- <li>
- set CVSROOT. Add the following line into the .cshrc file in your home directory if you are using tcsh or csh:<br>
- <i>setenv CVSROOT /home/vadve/vadve/Research/DynOpt/CVSRepository</i>
- </li>
- <li>
- check out. Go to the directory you want to store LLVM, type <br>
- <i>cvs checkout llvm</i>
- </li>
+ <li><tt>llvm/include/llvm</tt> - This directory contains all of the LLVM
+ specific header files. This directory also has subdirectories for
+ different portions of llvm: <tt>Analysis</tt>, <tt>CodeGen</tt>,
+ <tt>Reoptimizer</tt>, <tt>Target</tt>, <tt>Transforms</tt>, etc...
+
+ <li><tt>llvm/include/Support</tt> - This directory contains generic
+ support libraries that are independant of LLVM, but are used by LLVM.
+ For example, some C++ STL utilities and a Command Line option processing
+ library.
</ol>
-
- note: the c front-end implementation is not in cvs. If you want to use it, you can use excutable in Chris Lattner's directory<br>
- <dd><i>/home/vadve/lattner/cvs/gcc_install/bin/gcc</i><br>
- a brief usage of this gcc and other tools are introduced later. To read it now, click <a href="#tutorial">here</a>.
-
- <h2><a name="compilerun">Compile and Run</a></h2>
- There is a makefile in each directory. You can simple type <i>gmake</i> in the <b>~/llvm</b> directory to compile all the files or you can type <i>gmake</i> in the certain directory to compile all files and subdirectories in that directory.<br>
- You might want to add the the following directory into your path:<br>
- <dd><i>llvm/tools/Debug</i><br>
- so you can run tools in any directory. If you are using csh or tcsh, add <br>
- <dd><i>setenv PATH llvm/tools/Debug:${PATH}</i><br>
- at the end of the file .cshrc in your home directory.
-
- </dl>
- <h2><a name="layout">Program Layout</a></h2>
- Many useful infomation can be obtained from the LLVM doxygen tree available at <a href="http://llvm.cs.uiuc.edu/doxygen/"><i>http://llvm.cs.uiuc.edu/doxygen/ </i><br></a>
- The following is a brief introduction to code layout:
-
- <h3><a name="d&d">Depend and Debug directories</a></h3>
- Most directories contain these two directories. The depend directory contains dependance files which will be used during complilation. The debug directory contains object files, library files or executables after compilation.
- <h3><a name="include">llvm/include</a></h3>
- This directory contains common head files supporting the LLVM library. Specific head files which are only used by certain directory are place in that directory instead of here.
- <h3><a name="lib">llvm/lib</a></h3>
- This directory contains most important files of LLVM system. <br>
- <dl compact>
-
- <dt>llvm/lib/transforms/<dd> This directory contains files and directories for transforming one representation to another representation.
- <dt>llvm/lib/Target/<dd> This directory contains files and directories for target machine. The files under llvm/lib/Target describe the common property for any target machine. The directory llvm/lib/Target/Sparc describe the sparc machine specification. <br>
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="lib">llvm/lib</a></h3>
+ <!------------------------------------------------------------------------->
+
+ This directory contains most source files of LLVM system. In LLVM almost all
+ code exists in libraries, making it very easy to share code among the
+ different <a href="#tools">tools</a>.<p>
+
+ <dl compact>
+ <dt><tt>llvm/lib/VMCore/</tt><dd> This directory holds the core LLVM
+ source files that implement core classes like Instruction and BasicBlock.
+
+ <dt><tt>llvm/lib/AsmParser/</tt><dd> This directory holds the source code
+ for the LLVM assembly language parser library.
+
+ <dt><tt>llvm/lib/ByteCode/</tt><dd> This directory holds code for reading
+ and write LLVM bytecode.
+
+ <dt><tt>llvm/lib/CWrite/</tt><dd> This directory implements the LLVM to C
+ converter.
+
+ <dt><tt>llvm/lib/Analysis/</tt><dd> This directory contains a variety of
+ different program analyses, such as Dominator Information, Call Graphs,
+ Induction Variables, Interval Identification, Natural Loop Identification,
+ etc...
+
+ <dt><tt>llvm/lib/Transforms/</tt><dd> This directory contains the source
+ code for the LLVM to LLVM program transformations, such as Aggressive Dead
+ Code Elimination, Sparse Conditional Constant Propogation, Inlining, Loop
+ Invarient Code Motion, Dead Global Elimination, Pool Allocation, and many
+ others...
+
+ <dt><tt>llvm/lib/Target/</tt><dd> This directory contains files that
+ describe various target architectures for code generation. For example,
+ the llvm/lib/Target/Sparc directory holds the Sparc machine
+ description.<br>
- <dt>llvm/lib/Analysis/<dd> This directory contains files and directories for doing all kinds of data and control analysis.
- <dt>llvm/lib/AsmParser/<dd> This directory contains files and directories for parsing the llvm assemly files.
- <dt>llvm/lib/ByteCode/<dd> This directory contains files and directories for reading and write LLVM bytecode.
- <dt>llvm/lib/CWrite/<dd> This directory contains files and directories for writing c files as output.
- <dt>llvm/lib/CodeGen/<dd> This directory contains files and directories for instruction selection, instruction scheduling and register allocation.
- <dt>llvm/lib/Reoptimizer<dd> This directory contains files and directories for all kinds of optimizations, e.g. dead code elimination, Loop Invariant Code Motion, etc.
+ <dt><tt>llvm/lib/CodeGen/</tt><dd> This directory contains the major parts
+ of the code generator: Instruction Selector, Instruction Scheduling, and
+ Register Allocation.
+
+ <dt><tt>llvm/lib/Reoptimizer/</tt><dd> This directory holds code related
+ to the runtime reoptimizer framework that is currently under development.
- <dt>llvm/lib/Support/<dd> This directory contains some files and directories supporting the library, e.g. commandline processor and statistic reporter.
- <dt>llvm/lib/VMCore/<dd> This directory contains files and directories for implementing the virtual machine instruction set.
- </dl>
- <h3><a name="test">llvm/test</a></h3>
- This directory contains llvm assembly and other files to test the llvm library.
-
- <h3><a name="tools">llvm/tools</a></h3>
- <p> The <b>tools</b> directory contains many tools. You can always get help by typing <i>command_name --help </i>. The following is a brief introduction to each tool.
+ <dt><tt>llvm/lib/Support/</tt><dd> This directory contains the source code
+ that corresponds to the header files located in
+ <tt>llvm/include/Support/</tt>.
+ </dl>
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="test">llvm/test</a></h3>
+ <!------------------------------------------------------------------------->
+
+ <p>This directory contains regression tests and source code that is used to
+ test the LLVM infrastructure...</p>
+
+ <!------------------------------------------------------------------------->
+ <h3><a name="tools">llvm/tools</a></h3>
+ <!------------------------------------------------------------------------->
+
+ <p>The <b>tools</b> directory contains the executables built out of the
+ libraries above, which form the main part of the user interface. You can
+ always get help for a tool by typing <tt>tool_name --help</tt>. The
+ following is a brief introduction to the most important tools.</p>
+
<dl compact>
- <dt><i>analyze</i><dd> ???
- <dt><i>as</i><dd>llvm .ll -> .bc assembler
- <br>The assembler transfroms the human readable assembly to llvm bytecode.
- <dt><i>dis</i><dd>llvm .bc -> .ll disassembler
- <br>The disassembler transfroms the llvm bytecode to human readable assembly.
- <dt><i>extract</i><dd> ???
- <dt><i>gccas</i><dd>llvm .ll -> .bc assembler
- <br>The assembler transfroms the human readable assembly to llvm bytecode.
- <dt><i>gccld</i><dd>many llvm bytecode -> llvm bytecode + optimizations
- <br> gccld links many llvm bytecode files into one bytecode file and does some optimization.
- <dt><i>link</i><dd>many llvm bytecode -> llvm bytecode
- <br> <i>link</i> takes many llvm bytecode files and link them into one llvm bytecode file.
- <dt><i>llc</i><dd>llvm bytecode -> SPARC assembly
- <br> <i>llc</i> takes a llvm bytecode file and output a SPARC assembly file.
- <dt><i>lli</i><dd>llvm interpreter
- <br><i>lli</i> reads a llvm bytecode file and execute it.
- <dt><i>opt</i><dd>llvm .bc -> .bc modular optimizer
- <br> <i>opt</i> reads llvm bytecode and do certain optimization, then output llvm bytecode .
- </dl>
+ <dt><tt><b>as</b></tt><dd>The assembler transforms the human readable
+ llvm assembly to llvm bytecode.<p>
+
+ <dt><tt><b>dis</b></tt><dd>The disassembler transforms the llvm bytecode
+ to human readable llvm assembly. Additionally it can convert LLVM
+ bytecode to C, which is enabled with the <tt>-c</tt> option.<p>
+
+ <dt><tt><b>lli</b></tt><dd> <tt>lli</tt> is the LLVM interpreter, which
+ can directly execute LLVM bytecode (although very slowly...). In addition
+ to a simple intepreter, <tt>lli</tt> is also has debugger and tracing
+ modes (entered by specifying <tt>-debug</tt> or <tt>-trace</tt> on the
+ command line, respectively).<p>
+
+ <dt><tt><b>llc</b></tt><dd> <tt>llc</tt> is the LLVM backend compiler,
+ which translates LLVM bytecode to a SPARC assembly file.<p>
+
+ <dt><tt><b>llvmgcc</b></tt><dd> <tt>llvmgcc</tt> is a GCC based C frontend
+ that has been retargeted to emit LLVM code as the machine code output. It
+ works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
+ -o</tt> options that are typically used. The source code for the
+ <tt>llvmgcc</tt> tool is currently not included in the LLVM cvs tree
+ because it is quite large and not very interesting.<p>
+
+ <ol>
+ <dt><tt><b>gccas</b></tt><dd> This took is invoked by the
+ <tt>llvmgcc</tt> frontend as the "assembler" part of the compiler. This
+ tool actually assembles its input, performs a variety of optimizations,
+ and outputs LLVM bytecode. Thus when you invoke <tt>llvmgcc -c x.c -o
+ x.o</tt>, you are causing <tt>gccas</tt> to be run, which writes the
+ <tt>x.o</tt> file (which is an LLVM bytecode file that can be
+ disassembled or manipulated just like any other bytecode file). The
+ command line interface to <tt>gccas</tt> is designed to be as close as
+ possible to the <b>system</b> <tt>as</tt> utility so that the gcc
+ frontend itself did not have to be modified to interface to a "wierd"
+ assembler.<p>
+
+ <dt><tt><b>gccld</b></tt><dd> <tt>gccld</tt> links together several llvm
+ bytecode files into one bytecode file and does some optimization. It is
+ the linker invoked by the gcc frontend when multiple .o files need to be
+ linked together. Like <tt>gccas</tt> the command line interface of
+ <tt>gccld</tt> is designed to match the system linker, to aid
+ interfacing with the GCC frontend.<p>
+ </ol>
+
+ <dt><tt><b>opt</b></tt><dd> <tt>opt</tt> reads llvm bytecode, applies a
+ series of LLVM to LLVM transformations (which are specified on the command
+ line), and then outputs the resultant bytecode. The '<tt>opt --help</tt>'
+ command is a good way to get a list of the program transformations
+ available in LLVM.<p>
+
+
+ <dt><tt><b>analyze</b></tt><dd> <tt>analyze</tt> is used to run a specific
+ analysis on an input LLVM bytecode file and print out the results. It is
+ primarily useful for debugging analyses, or familiarizing yourself with
+ what an analysis does.<p>
+
+ </dl>
- <h2><a name="tutorial">tutorial for using tools</h2>
- <ul>
- <li>create a simple c file:<br>
- <pre>
- hello.c
-
- int main() {
- printf("hello world\n");
- return 0;
- }
- </pre>
- </li>
- <li>compile the c file into a llvm bytecode file<br>
- <i>% alias llvmgcc /home/vadve/lattner/cvs/gcc_install/bin/gcc</i><br>
- <i>% llvmgcc hello.c </i><br>
- there will be two output files: <b>a.out</b> and <b>a.out.bc</b>. The file <b>a.out</b> is a shell script and <b>a.out.bc</b> is the llvm bytecode. You can run a.out to excute or directly call the interpreter: <br>
- % <i>lli a.out.bc</i><br>
- <li> dissembler and assembler <br>
- read llvm bytecode and output human readable llvm assembly<br>
- %<i>dis a.out.bc -o hello.ll</i><br>
- read human readable llvm assembly code and output llvm bytecode<br>
- %<i>as hello.ll -o hello.bc</i>
- </li>
- <li> compile to sparc assembly<br>
- <i>%llc hello.bc -o hello.s</i>
- </li>
- </ul>
- <h2><a name="links">Links</a></h2>
- <ul>
- <li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
- <li><a href="http://tank.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li>
- </ul>
- <hr>
- If you have any question, please send an email to <a href="mailto:lattner@uiuc.edu">Lattner Chris Arthur</a> or <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>. <p>
+ <!--=====================================================================-->
+ <h2><a name="tutorial">An example using the LLVM tool chain</h2>
+ <!--=====================================================================-->
+
+ <ol>
+ <li>First, create a simple C file, name it 'hello.c':
+ <pre>
+ #include <stdio.h>
+ int main() {
+ printf("hello world\n");
+ return 0;
+ }
+ </pre>
+
+ <li>Next, compile the C file into a LLVM bytecode file:<p>
+
+ <tt>% llvmgcc hello.c -o hello</tt><p>
+
+ This will create two result files: <tt>hello</tt> and
+ <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
+ corresponds the the compiled program and the library facilities that it
+ required. <tt>hello</tt> is a simple shell script that runs the bytecode
+ file with <tt>lli</tt>, making the result directly executable.<p>
+
+ <li>Run the program. To make sure the program ran, execute one of the
+ following commands:<p>
+
+ <tt>% ./hello</tt><p>
+
+ or<p>
+
+ <tt>% lli hello.bc</tt><p>
+
+ <li>Use the <tt>dis</tt> utility to take a look at the LLVM assembly
+ code:<p>
+
+ <tt>% dis < hello.bc | less</tt><p>
+
+ <li>Compile the program to native Sparc assembly using the code
+ generator:<p>
+
+ <tt>% llc hello.bc -o hello.s</tt><p>
+
+ <li>Assemble the native sparc assemble file into a program:<p>
+
+ <tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc</tt><p>
+
+ <li>Execute the native sparc program:<p>
+
+ <tt>% ./hello.sparc</tt><p>
+
+ </ol>
+
+
+ <!--=====================================================================-->
+ <h2><a name="links">Links</a></h2>
+ <!--=====================================================================-->
+
+ <p>This document is just an <b>introduction</b> to how to use LLVM to do
+ some simple things... there are many more interesting and complicated things
+ that you can do that aren't documented here (but we'll gladly accept a patch
+ if you want to write something up!). For more information about LLVM, check
+ out:</p>
+
+ <ul>
+ <li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
+ <li><a href="http://tank.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li>
+ </ul>
+
+ <hr>
+
+ If you have any questions or run into any snags (or you have any
+ additions...), please send an email to <a
+ href="mailto:sabre@nondot.org">Chris Lattner</a> or <a
+ href="mailto:gshi1@uiuc.edu">Guochun Shi</a>. <p>
+
<!-- Created: Mon Jul 1 02:29:02 CDT 2002 -->
<!-- hhmts start -->
-Last modified: Wed Jul 17 17:55:16 CDT 2002
+Last modified: Wed Jul 24 14:43:12 CDT 2002
<!-- hhmts end -->
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