llvm-6502/docs/GettingStarted.html

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<title>Specification for LLVM system code</title>
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<h1>Specification for LLVM system</h1>
<h1><a name="index">Index</a></h1>
<ul>
<li><a href="#cvs">Checkout LLVM from CVS</a>
<li><a href="#compilerun">Compile and Run</a>
<li><a href="#layout">Program layout</a>
<ol>
<li><a href="#d&d">Depend and Debug 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="#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>
For those who are not familar with cvs, there are two steps you should do:<br>
<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>
</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>
<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>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.
<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>
<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>
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Last modified: Wed Jul 17 17:55:16 CDT 2002
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