https://github.com/shibatch/xpass

A collection of experimental optimizing passes for LLVM
https://github.com/shibatch/xpass

clang compiler llvm llvm-ir llvm-pass optimization sleef

Last synced: about 1 month ago
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A collection of experimental optimizing passes for LLVM

• Host: GitHub
• URL: https://github.com/shibatch/xpass
• Owner: shibatch
• License: mit
• Created: 2020-07-06T05:21:40.000Z (over 4 years ago)
• Default Branch: main
• Last Pushed: 2023-02-19T08:45:49.000Z (almost 2 years ago)
• Last Synced: 2023-10-20T04:30:45.016Z (about 1 year ago)
• Topics: clang, compiler, llvm, llvm-ir, llvm-pass, optimization, sleef
• Language: C++
• Homepage:
• Size: 104 KB
• Stars: 6
• Watchers: 4
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
[![Build Status](https://travis-ci.org/shibatch/xpass.svg?branch=master)](https://travis-ci.org/shibatch/xpass)

# XPASS - An experimental LLVM pass

This is an experimental optimizing pass for LLVM, named

MathPeephole. This pass performs the following transforms.

* a/b + c/d  ->  (ad + bc) / (bd)

* x/y + z > a/b + c  ->  (xb - ay) / (yb) + z > c

* a/b + c > d  ->  b < 0 ? (a - b * (d - c) < 0) : (-(a - b * (d - c)) < 0)

* w sqrt(x) + y > z  ->  w >= 0 ? ((z < y) | (wwx > (z-y)(z-y))) : ((z <= y) & (wwx < (z-y)(z-y)))

This project is based on the llvm-tutor package developed by Andrzej

Warzyński.

## Running the passes

```

clang-14 -S -emit-llvm -O1 -ffast-math example.c -o example.ll

opt -load-pass-plugin=libMathPeephole.so -passes=math-peephole example.ll -S -o example.opt.ll

clang-14 -O1 -ffast-math example.opt.ll -o example

```

Please see [wiki](https://github.com/shibatch/xpass/wiki) for examples of the transforms.