hd650 / llvm-practive

Write some classic compiler passes/analysis in LLVM

LLVM_Practice

Environment set up

Need to install:

1. LLVM 15 (build from source or prebuilt distribution)
2. GDB
3. LLVM Lit
4. Cmake
5. Google test

HelloWorld Pass

The first pass that simply prints function names of a module. Mainly for verifying the build and debug system of future passes.

HelloWorld builds a pass as dll/so shared library that does NOT link any LLVM library. Thus it's a standalone pass not within LLVM build system. We could call opt and load that shared library to run the pass on any LLVM IR code. Also a gdb target is generated support debugging the pass in the shared library. This pass and its build system is the base of future passes.

Dominance Analysis (WIP)

A function analysis that compute the dominator information. Dominator info is used extensively in compiler optimization. The unittest system is implemented in this analysis to check the correctness of the analysis.

DominanceAnalysis builds a pass as shared library that invokes an analysis. The analysis library contains:

1. implementation of the Simple Fast Dominator Algorithm and the Lengauer-Tarjan Algorithm (WIP).
2. implementation of a dominator tree that can retrieve dominance information efficiently.
3. a gtest suit that checks the correctness of the implementation of the analysis.

Sparse Conditional Constant Propagation

A optimization pass that do some sort of const propagation and dead code elimination together. It's a good practice of writing a dataflow analysis.