https://github.com/auyxs/llvm-optimizations

UNIMORE Compilers Course 2024/25 - collection of assignments
https://github.com/auyxs/llvm-optimizations

compilers llvm llvm-ir

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UNIMORE Compilers Course 2024/25 - collection of assignments

• Host: GitHub
• URL: https://github.com/auyxs/llvm-optimizations
• Owner: Auyxs
• License: mit
• Created: 2025-03-24T22:25:35.000Z (about 1 year ago)
• Default Branch: main
• Last Pushed: 2025-03-26T23:57:30.000Z (about 1 year ago)
• Last Synced: 2025-03-27T00:29:19.254Z (about 1 year ago)
• Topics: compilers, llvm, llvm-ir
• Language: C++
• Homepage:
• Size: 4.88 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# LLVM Optimization Passes

[![LLVM Version](https://img.shields.io/badge/LLVM-19.1.7-orange.svg)](https://llvm.org/)

![License](https://img.shields.io/badge/License-MIT-blue.svg)

Repository containing Compilers Course assignments at **Unimore (2024/2025)** - Implementation of **LLVM IR** optimization passes as plugins.

## 📂 First Assignment 

1. **Algebraic Identity**

    - `x + 0` → `x`

    - `1 × 𝑥` → `x`

2. **Strength Reduction**

    - `15 × 𝑥 = 𝑥 × 15` → `(𝑥 ≪ 4) – x`

    - `y = x / 8` → `y = x >> 3`

3. **Multi-Instruction Optimization**

    - `𝑎 = 𝑏 + 1, 𝑐 = 𝑎 − 1` → `𝑎 = 𝑏 + 1, 𝑐 = b`

### Usage

#### 🔧 Build

To build the LLVM plugin, follow these steps:

```bash

mkdir -p build

cd build

cmake -DLT_LLVM_INSTALL_DIR=$LLVM_DIR /path/to/assignment-01

make

```

The plugin (`libLocalOpts.so`) will be generated in the build directory.

> Note : Ensure that $LLVM_DIR is correctly set to your LLVM installation path. 

> (e.g., /usr/lib/llvm-19/bin on Linux)

#### ▶️ Run Optimization Pass

Once the plugin is built, you can run the optimization script to test the implemented passes:

1. Place your `.cpp` test files in the `test/cpp` directory.

2. Before running the script, set the `OPT_PLUGIN_PATH` environment variable:

```bash

export OPT_PLUGIN_PATH=/path/to/libLocalOpts.so

```

3. Make the script executable and run it:

```bash

chmod +x run_opt.sh

./run_opt.sh

```

## 📂 Second Assignment - Dataflow Analysis

> Note: no code implementation required

1. **Very Busy Expressions**

2. **Dominator Analysis**

3. **Constant Propagation**

## Contributors

- Aurora Lin

- Eleonora Muzzi