From fbe19000463a90a5c76921531b61df07feb2baeb Mon Sep 17 00:00:00 2001 From: John Criswell Date: Wed, 11 Jun 2003 20:46:40 +0000 Subject: [PATCH] Updated the documentation to reflect changes in the Makefiles for building projects. Fixed some small grammatical errors. Using Netscape Composer seems to have added stuff that makes the page look exactly the same. Bah! Curse my laziness! llvm-svn: 6685 --- docs/GettingStarted.html | 921 +++++++++++++++++++-------------------- 1 file changed, 456 insertions(+), 465 deletions(-) diff --git a/docs/GettingStarted.html b/docs/GettingStarted.html index 8dadc17f209..f4083f34817 100644 --- a/docs/GettingStarted.html +++ b/docs/GettingStarted.html @@ -1,477 +1,468 @@ - - Getting Started with LLVM System - - - -

Getting Started with the LLVM System
By: Guochun Shi, - Chris Lattner and - Vikram Adve -

- - -

Contents

- - - - - - -
-

Overview

-
- - -

The next section of this guide is meant to get - you up and running with LLVM, and to give you some basic information about - the LLVM environment. The first subsection gives - a short summary for those who are already familiar with the system and - want to get started as quickly as possible. - -

The later sections of this guide describe the general layout of the the LLVM source-tree, a simple example using the LLVM tool chain, and links to find more information about LLVM or to get - help via e-mail. - - -

-

Getting Started

-
- - - - -

Getting Started Quickly (A Summary)

- - - Here's the short story for getting up and running quickly with LLVM: + + Getting Started with LLVM System + + + +
+

Getting Started with the LLVM System
+By: Guochun Shi, Chris Lattner and Vikram Adve

+
+ + +

Contents

+ + + + + +
+

Overview

+
+ + +

The next section of this guide is meant to +get you up and running with LLVM, and to give you some basic information +about the LLVM environment. The first subsection +gives a short summary for those who are already familiar with the system +and want to get started as quickly as possible.

+

The later sections of this guide describe the general +layout of the LLVM source-tree, a simple example +using the LLVM tool chain, and links to find more information +about LLVM or to get help via e-mail. +

+
+

Getting Started

+
+ + + +

Getting Started Quickly (A Summary)

+ + Here's the short story for getting up and running quickly with LLVM: + +
    +
  1. Find the path to the CVS repository containing LLVM (we'll call +this CVSROOTDIR).
    2. +
  2. cd where-you-want-llvm-to-live
    3. +
  3. cvs -d CVSROOTDIR checkout llvm
    4. +
  4. cd llvm
    5. +
  5. Edit Makefile.config to set local paths. This includes + setting the install location of the C frontend and the various paths + to the C and C++ compilers used to build LLVM itself.
    6. +
  6. Set your LLVM_LIB_SEARCH_PATH environment variable.
    7. +
  7. gmake -k |& tee gnumake.out    # this is +csh or tcsh syntax
    8. +
+ +

See Setting up your environment on tips to + simplify working with the LLVM front-end and compiled tools. See the + other sub-sections below for other useful details in working with LLVM, + or go straight to Program Layout to learn about +the layout of the source code tree. +

+

Terminology and Notation

+ + +

Through this manual, the following names are used to denote paths +specific to the local system and working environment. These are not + environment variables you need to set, but just strings used in the rest + of this document below. In any of the examples below, simply replace + each of these names with the appropriate pathname on your local system. All these paths are absolute:

- - - -

Checkout LLVM from CVS

- - -

Before checking out the source code, you will need to know the path to - CVS repository containing LLVM source code (we'll call this - CVSROOTDIR below). Ask the person responsible for your local LLVM - installation to give you this path. - -

To get a fresh copy of the entire source code, all you - need to do is check it out from CVS as follows: -

- -

This will create an 'llvm' directory in the current - directory and fully populate it with the LLVM source code, Makefiles, - test directories, and local copies of documentation files.

- - -

Local Configuration Options

- - -

The file llvm/Makefile.config - defines the following path variables, - which are specific to a particular installation of LLVM. - These should need to be modified only once after checking out a copy - of LLVM (if the default values do not already match your system): - -

- - In addition to settings in this file, you must set a - LLVM_LIB_SEARCH_PATH environment variable in your startup scripts. - This environment variable is used to locate "system" libraries like - "-lc" and "-lm" when linking. This variable should be set - to the absolute path for the bytecode-libs subdirectory of the C front-end - install. For example, - /home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs for the X86 - version of the C front-end, on our research machines.

- - -

The location for LLVM object files

- - -

The LLVM make system sends most output files generated during the build - into the directory defined by the variable LLVM_OBJ_DIR in - llvm/Makefile.config. This can be either just your normal LLVM - source tree or some other directory writable by you. You may wish to put - object files on a different filesystem either to keep them from being backed - up or to speed up local builds. - -

If you do not wish to use a different location for object files (building - into the source tree directly), just set this variable to ".".

- - -

Setting up your environment

- - - NOTE: This step is optional but will set up your environment so you - can use the compiled LLVM tools with as little hassle as - possible.) - -

Add the following lines to your .cshrc (or the corresponding - lines to your .profile if you use a bourne shell derivative). - - 

-       # Make the C front end easy to use...
-       alias llvmgcc LLVMGCCDIR/bin/llvm-gcc
+     
+
+       
+    
+
Checkout LLVM from CVS

+      
+     
+
Before checking out the source code, you will need to know the path to 
+    the CVS repository containing LLVM source code (we'll call this     CVSROOTDIR
+below).  Ask the person responsible for your local LLVM     installation
+to give you this path.      

+
To get a fresh copy of the entire source code, all you     need to do
+is check it out from CVS as follows:     

+
+      
+
This will create an 'llvm' directory in the current     directory
+and fully populate it with the LLVM source code, Makefiles,     test directories,
+and local copies of documentation files.

+       
+    
+
Local Configuration Options

+      
+     
+
The file llvm/Makefile.config     defines the following path
+variables     which are specific to a particular installation of LLVM.  
+  These should need to be modified only once after checking out a copy  
+  of LLVM (if the default values do not already match your system):     
+

+
+      In addition to settings in this file, you must set a     LLVM_LIB_SEARCH_PATH
+environment variable in your startup scripts.     This environment variable
+is used to locate "system" libraries like     "-lc" and "-lm"
+when linking.  This variable should be set     to the absolute path for the
+bytecode-libs subdirectory of the C front-end     install.  For example, 
+   /home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs is used
+for the X86     version of the C front-end on our research machines.
+
       
+    

+
The location for LLVM object files

+      
+     
+
The LLVM make system sends most output files generated during the build 
+    into the directory defined by the variable OBJ_ROOT in     llvm/Makefile.config.
+ This can be either just your normal LLVM     source tree or some other directory
+writable by you.  You may wish to put     object files on a different filesystem
+either to keep them from being backed     up or to speed up local builds. 
+     

+
If you do not wish to use a different location for object files (i.e.
+building     into the source tree directly), just set this variable to ".".

+
       
+    

+
Setting up your environment

+      
+     NOTE: This step is optional but will set up your environment so you 
+    can use the compiled LLVM tools with as little hassle as      possible.) 
+     
+
Add the following lines to your .cshrc (or the corresponding 
+   lines to your .profile if you use a bourne shell derivative). 
+     

+
       # Make the C front end easy to use...
       alias llvmgcc LLVMGCCDIR/bin/llvm-gcc
 
        # Make the LLVM tools easy to use...
-       setenv PATH LLVM_OBJ_DIR/llvm/tools/Debug:${PATH}
-    

-    The llvmgcc alias is useful because the C compiler is not
-    included in the CVS tree you just checked out.
+       setenv PATH OBJ_ROOT/llvm/tools/Debug:${PATH}
+ The llvmgcc alias is useful because the C compiler is not + included in the CVS tree you just checked out. +

The other LLVM tools are part of the LLVM source +base and are built when compiling LLVM. They will be built into the +OBJ_ROOT/tools/Debug directory.

+ -

The other LLVM tools are part of the LLVM - source base, and built when compiling LLVM. They will be built into the - LLVM_OBJ_DIR/tools/Debug directory.

- - -

Compiling the source code

- - -

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 gmake, instead of make to build them, but can - otherwise be used freely. To build the entire LLVM system, just enter the - top level llvm directory and type gmake. A few minutes - later you will hopefully have a freshly compiled toolchain waiting for you - in llvm/tools/Debug. If you want to look at the libraries that - were compiled, look in llvm/lib/Debug.

- - If you get an error talking about a /localhome directory, follow - the instructions in the section about Setting Up Your - Environment. - - - - -
-

Program Layout

-
- - -

One useful source of infomation about the LLVM sourcebase is the LLVM doxygen documentation, available at http://llvm.cs.uiuc.edu/doxygen/. The - following is a brief introduction to code layout:

- - - -

CVS directories

- - - Every directory checked out of CVS will contain a CVS directory, - for the most part these can just be ignored. - - - -

Depend, Debug, & Release +

Compiling the source code

+ + +

Every directory in the LLVM source tree includes a Makefile to + build it and any subdirectories that it contains. These makefiles require + GNU Make (gmake) instead of make to build them, but +can otherwise be used freely. To build the entire LLVM system, just +enter the top level llvm directory and type gmake. + A few minutes later you will hopefully have a freshly compiled toolchain +waiting for you in OBJ_ROOT/llvm/tools/Debug. + If you want to look at the libraries that were compiled, look in OBJ_ROOT/llvm/lib/Debug.

+ If you get an error about the /localhome directory, chances +are good that something has been misconfigured.  Follow the instructions +in the section about Setting Up Your Environment. + + +
+

Program Layout

+
+ + +

One useful source of infomation about the LLVM sourcebase is the LLVM +doxygen documentation, available at +http://llvm.cs.uiuc.edu/doxygen/. +The following is a brief introduction to code layout:

+ + +

CVS directories

+ + Every directory checked out of CVS will contain a CVS directory; + for the most part, these can just be ignored. + +

Depend, Debug, & Release directories

- - - If you are building with the "BUILD_ROOT=." option enabled in the - Makefile.common file, most source directories will 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 ENABLE_OPTIMIZED=1 flag is passed to gmake, - causing an optimized built to be performed.

- - - -

llvm/include

- - - This directory contains public header files exported from the LLVM - library. The two main subdirectories of this directory are:

- -

    -
  1. llvm/include/llvm - This directory contains all of the LLVM - specific header files. This directory also has subdirectories for - different portions of LLVM: Analysis, CodeGen, - Reoptimizer, Target, Transforms, etc... - -
  2. llvm/include/Support - 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. -
- - -

llvm/lib

- - - 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 tools.

- -

-
llvm/lib/VMCore/
This directory holds the core LLVM - source files that implement core classes like Instruction and BasicBlock. - -
llvm/lib/AsmParser/
This directory holds the source code - for the LLVM assembly language parser library. - -
llvm/lib/ByteCode/
This directory holds code for reading - and write LLVM bytecode. - -
llvm/lib/CWriter/
This directory implements the LLVM to C - converter. - -
llvm/lib/Analysis/
This directory contains a variety of - different program analyses, such as Dominator Information, Call Graphs, - Induction Variables, Interval Identification, Natural Loop Identification, - etc... - -
llvm/lib/Transforms/
This directory contains the source - code for the LLVM to LLVM program transformations, such as Aggressive Dead - Code Elimination, Sparse Conditional Constant Propagation, Inlining, Loop - Invarient Code Motion, Dead Global Elimination, Pool Allocation, and many - others... - -
llvm/lib/Target/
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.
- -
llvm/lib/CodeGen/
This directory contains the major parts - of the code generator: Instruction Selector, Instruction Scheduling, and - Register Allocation. - -
llvm/lib/Reoptimizer/
This directory holds code related - to the runtime reoptimizer framework that is currently under development. - -
llvm/lib/Support/
This directory contains the source code - that corresponds to the header files located in - llvm/include/Support/. -
- - -

llvm/test

- - -

This directory contains regression tests and source code that is used to - test the LLVM infrastructure...

- - -

llvm/tools

- - -

The tools 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 tool_name --help. The - following is a brief introduction to the most important tools.

- -
-
as
The assembler transforms the human readable - LLVM assembly to LLVM bytecode.

- -

dis
The disassembler transforms the LLVM bytecode - to human readable LLVM assembly. Additionally it can convert LLVM - bytecode to C, which is enabled with the -c option.

- -

lli
lli is the LLVM interpreter, which - can directly execute LLVM bytecode (although very slowly...). In addition - to a simple intepreter, lli is also has debugger and tracing - modes (entered by specifying -debug or -trace on the - command line, respectively).

- -

llc
llc is the LLVM backend compiler, - which translates LLVM bytecode to a SPARC assembly file.

- -

llvmgcc
llvmgcc 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 -c, -S, -E, - -o options that are typically used. The source code for the - llvmgcc tool is currently not included in the LLVM cvs tree - because it is quite large and not very interesting.

- -

    -
    gccas
    This tool is invoked by the - llvmgcc frontend as the "assembler" part of the compiler. This - tool actually assembles LLVM assembly to LLVM bytecode, - performs a variety of optimizations, - and outputs LLVM bytecode. Thus when you invoke llvmgcc -c x.c -o - x.o, you are causing gccas to be run, which writes the - x.o file (which is an LLVM bytecode file that can be - disassembled or manipulated just like any other bytecode file). The - command line interface to gccas is designed to be as close as - possible to the system 'as' utility so that the gcc - frontend itself did not have to be modified to interface to a "wierd" - assembler.

    - -

    gccld
    gccld 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 gccas the command line interface of - gccld is designed to match the system linker, to aid - interfacing with the GCC frontend.

    -

- -
opt
opt 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 'opt --help' - command is a good way to get a list of the program transformations - available in LLVM.

- - -

analyze
analyze 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.

- -

- - -

An example using the LLVM tool chain

- - -
    -
  1. First, create a simple C file, name it 'hello.c': - 
    -   #include <stdio.h>
-   int main() {
-     printf("hello world\n");
-     return 0;
-   }
-
    - -
  2. Next, compile the C file into a LLVM bytecode file:

    - - % llvmgcc hello.c -o hello

    - - This will create two result files: hello and - hello.bc. The hello.bc is the LLVM bytecode that - corresponds the the compiled program and the library facilities that it - required. hello is a simple shell script that runs the bytecode - file with lli, making the result directly executable.

    - -

  3. Run the program. To make sure the program ran, execute one of the - following commands:

    + + If you are building with the "OBJ_ROOT=." option enabled in +the Makefile.config file, most source directories will 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 ENABLE_OPTIMIZED=1 flag is passed +to gmake, causing an optimized built to be performed. +

    +

    +

    llvm/include

    + + This directory contains public header files exported from the LLVM + library. The two main subdirectories of this directory are: +

    +
      +
    1. llvm/include/llvm - This directory contains all of the +LLVM specific header files. This directory also has subdirectories +for different portions of LLVM: Analysis, CodeGen, + Reoptimizer, Target, Transforms, etc... +
      2. +
    2. llvm/include/Support - 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.
      3. +
    + + +

    llvm/lib

    + + 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 tools. +

    +
    +
    llvm/lib/VMCore/
    +
    This directory holds the core LLVM source files that implement +core classes like Instruction and BasicBlock.
    +
    llvm/lib/AsmParser/
    +
    This directory holds the source code for the LLVM assembly language +parser library.
    +
    llvm/lib/ByteCode/
    +
    This directory holds code for reading and write LLVM bytecode. +
    +
    llvm/lib/CWriter/
    +
    This directory implements the LLVM to C converter.
    +
    llvm/lib/Analysis/
    +
    This directory contains a variety of different program analyses, +such as Dominator Information, Call Graphs, Induction Variables, Interval +Identification, Natural Loop Identification, etc...
    +
    llvm/lib/Transforms/
    +
    This directory contains the source code for the LLVM to LLVM +program transformations, such as Aggressive Dead Code Elimination, +Sparse Conditional Constant Propagation, Inlining, Loop Invarient Code +Motion, Dead Global Elimination, Pool Allocation, and many others... +
    +
    llvm/lib/Target/
    +
    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.
    +
    +
    llvm/lib/CodeGen/
    +
    This directory contains the major parts of the code generator: +Instruction Selector, Instruction Scheduling, and Register Allocation. +
    +
    llvm/lib/Reoptimizer/
    +
    This directory holds code related to the runtime reoptimizer +framework that is currently under development.
    +
    llvm/lib/Support/
    +
    This directory contains the source code that corresponds to +the header files located in llvm/include/Support/.
    +
    + + +

    llvm/test

    + + +

    This directory contains regression tests and source code that is used +to test the LLVM infrastructure...

    + + +

    llvm/tools

    + + +

    The tools 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 tool_name --help. +The following is a brief introduction to the most important tools.

    - % ./hello

    - - or

    - - % lli hello.bc

    - -

  4. Use the dis utility to take a look at the LLVM assembly - code:

    - - % dis < hello.bc | less

    - -

  5. Compile the program to native Sparc assembly using the code - generator:

    - - % llc hello.bc -o hello.s

    - -

  6. Assemble the native sparc assemble file into a program:

    - - % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc

    - -

  7. Execute the native sparc program:

    - - % ./hello.sparc

    - +

    +
    as
    +
    The assembler transforms the human readable LLVM assembly to +LLVM bytecode. +

    +
    +
    dis
    +
    The disassembler transforms the LLVM bytecode to human readable +LLVM assembly. Additionally it can convert LLVM bytecode to C, which +is enabled with the -c option. +

    +
    +
    lli
    +
    lli is the LLVM interpreter, which can directly execute +LLVM bytecode (although very slowly...). In addition to a simple intepreter, + lli is also has debugger and tracing modes (entered by +specifying -debug or -trace on the command line, +respectively). +

    +
    +
    llc
    +
    llc is the LLVM backend compiler, which translates +LLVM bytecode to a SPARC assembly file. +

    +
    +
    llvmgcc
    +
    llvmgcc 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 -c, -S, -E, -o options +that are typically used. The source code for the llvmgcc +tool is currently not included in the LLVM cvs tree because it is quite +large and not very interesting. +

    +
      +
      gccas
      +
      This tool is invoked by the llvmgcc frontend +as the "assembler" part of the compiler. This tool actually assembles +LLVM assembly to LLVM bytecode, performs a variety of optimizations, + and outputs LLVM bytecode. Thus when you invoke llvmgcc -c x.c +-o x.o, you are causing gccas to be run, which writes +the x.o file (which is an LLVM bytecode file that can be + disassembled or manipulated just like any other bytecode file). +The command line interface to gccas is designed to be as +close as possible to the system 'as' utility so that +the gcc frontend itself did not have to be modified to interface +to a "wierd" assembler. +

      +
      +
      gccld
      +
      gccld 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 gccas the command line interface of gccld +is designed to match the system linker, to aid interfacing with the +GCC frontend. +

      +
    - - - -

    Links

    - - -

    This document is just an introduction 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:

    - - - -
    - - If you have any questions or run into any snags (or you have any - additions...), please send an email to - Chris Lattner.

    - - - -Last modified: Tue Jun 3 22:06:43 CDT 2003 - - +
    +
    opt
    +
    opt 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 'opt --help' command +is a good way to get a list of the program transformations available +in LLVM. +

    +
    +
    analyze
    +
    analyze 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. +

    +
    +
    + + +

    An example using the LLVM tool chain

    + + +
      +
    1. First, create a simple C file, name it 'hello.c': + + 
         #include <stdio.h>
         int main() {
           printf("hello world\n");
           return 0;
         }
      +
      2. +
    2. Next, compile the C file into a LLVM bytecode file: +

      % llvmgcc hello.c -o hello

      +

      This will create two result files: hello and + hello.bc. The hello.bc is the LLVM bytecode that + corresponds the the compiled program and the library facilities that it + required. hello is a simple shell script that runs the bytecode + file with lli, making the result directly executable.

      +

      +
      3. +
    3. Run the program. To make sure the program ran, execute one of the + following commands: +

      % ./hello

      +

      or

      +

      % lli hello.bc

      +

      +
      4. +
    4. Use the dis utility to take a look at the LLVM assembly + code: +

      % dis < hello.bc | less

      +

      +
      5. +
    5. Compile the program to native Sparc assembly using the code generator: +

      % llc hello.bc -o hello.s

      +

      +
      6. +
    6. Assemble the native sparc assemble file into a program: +

      % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc

      +

      +
      7. +
    7. Execute the native sparc program: +

      % ./hello.sparc

      +

      +
      8. +       +
    + + +

    Links

    + + +

    This document is just an introduction 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:

    + + + +
    If you have any questions or run into any snags (or you have any + additions...), please send an email to Chris Lattner. +

    + +Last modified: Tue Jun 3 22:06:43 CDT 2003
    +