/CS426-UnitProject

Primary LanguageC

CS 426 Fall 2022 Unit Project

Summary of Files

  • CMakeLists.txt: Configures the build system for your passes. If using your own install of LLVM (rather than the install provided on EWS) you will need to modify the path on line 6 to a path to the build/ directory of your LLVM install
  • RegisterPasses.cpp: Provides boilerplate code needed to register the passes with LLVM so they can be run
  • UnitLICM.h and UnitLICM.cpp: You should implement your LICM pass in these files. The provided code defines the UnitLICM class as an optimization pass operating on functions and acquires the results of your identification pass.
  • UnitLoopInfo.h and UnitLoopInfo.cpp: You should implement your Loop Analysis pass in these files as well as implement the UnitLoopInfo class which provides the results of your loop analysis to your LICM pass. The provided code includes an empty definition of the UnitLoopInfo class and defines the UnitLoopAnalysis analysis and also acquires the function's DominatorTree which you are allowed to use in your analysis.
  • UnitSCCP.h and UnitSCCP.cpp: You should implement your SCCP pass in these files. The provided code defines UnitSCCP as a function optimization pass.

Build Instructions

If using your own build of LLVM, follow the above directions for modifying your CMakeLists.txt file.

From the directory containing this file, execute the following commands

mkdir build
cd build
cmake ..
make

This should configure and then build the four passes into a single file which can be used with LLVM's opt to run your passes. Note that you need to use the version of opt in the bin/ directory of the path to LLVM listed in the CMakeLists.txt file. You can run your passes as follows:

opt -load-pass-plugin=libUnitProject.so -passes="unit-licm,unit-sccp" <input> -o <output>

You can change the string after -passes to specify what passes and what order to run them in, the example above runs your LICM pass and then your SCCP pass. You can also include LLVM built-in passes in this string. Also, note that you may need to provide the path to the libUnitProject.so file if not in the directory containing it.

Also, when compiling programs to LLVM using Clang, include -O1 in your flags, by default (at -O0) Clang disables optimizations of its generated code.