0. 前言

联系一下南大程序分析课程（基于Java）的笔记。

LLVM

课程视频：https://www.youtube.com/playlist?list=PLDSTpI7ZVmVnvqtebWnnI8YeB8bJoGOyv

课程的GitHub仓库：https://github.com/lac-dcc/llvm-course/

1. 基础知识

clang-18 -S hello-world.c -emit-llvm -o hello-world.ll
opt-18 -passes=dot-cfg -disable-output ./hello-world.ll
dot -Tsvg .prefix_sum.dot > cfg.svg
dot -Tpdf .prefix_sum.dot -o prefix_sum.pdf

opt-18 --print-passes

# generate x86 assembly code
llc hello-world.ll -march=x86 -o file.x86

# Rust
rustc --emit llvm-ir hello-world.rs
rustc --emit asm hello-world.rs

2.

3. Pass编写实践：常量加法分析

include/AddConst.h:

#ifndef ADD_CONST_H
#define ADD_CONST_H
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/PassManager.h"

namespace addconst {
struct AddConstAnalysis : public llvm::AnalysisInfoMixin<AddConstAnalysis> {
    using Result = llvm::SmallVector<llvm::BinaryOperator *, 0>;
    Result run(llvm::Function &F, llvm::FunctionAnalysisManager &FAM);
    static llvm::AnalysisKey Key;
};

struct AddConstPrinterPass : public llvm::PassInfoMixin<AddConstPrinterPass> {
    explicit AddConstPrinterPass(llvm::raw_ostream &OS) : OS(OS) {}
    llvm::PreservedAnalyses run(llvm::Function &F,
                                llvm::FunctionAnalysisManager &FAM);
  private:
    llvm::raw_ostream &OS;
};

struct AddConstPass : public llvm::PassInfoMixin<AddConstPass> {
    llvm::PreservedAnalyses run(llvm::Function &F,
                                llvm::FunctionAnalysisManager &FAM);
};
}

#endif

; ModuleID = 'llvm-ir/foo.ll'
source_filename = "llvm-ir/foo.ll"

define i32 @foo(i32 %a, i32 %b) {
  %c = add i32 1, 2
  %d = add i32 3, 4
  %e = add i32 %a, %b
  %f = add i32 %c, %d
  %g = add i32 %e, %f
  ret i32 %g
}

export LLVM_INSTALL_DIR=/lib/llvm-18
cmake -G "Unix Makefiles" -B build/ .
cd build; make; cd ..
LLVM_OPT=$LLVM_INSTALL_DIR/bin/opt
$LLVM_OPT -load-pass-plugin build/lib/libAddConst.so -passes="print<add-const>" -disable-output examples/foo.ll
# Output:
# =============================================
# || foo ||
# =============================================
#   %c = add i32 1, 2
#   %d = add i32 3, 4
# =============================================

LLVM原初论文笔记

LLVM在安全研究中的应用

https://elmanto.github.io/posts/llvm_for_security_1_4

https://www.youtube.com/watch?v=JMXhmMQ0bNw

https://github.com/gmh5225/awesome-llvm-security

其他资料

  1. LLVM: A Compilation Framework for Lifelong Program Analysis & Transformation
  2. LLVM学习之基础编程+过程间分析
  3. LLVM in 100 Seconds
  4. 知乎专栏：LLVM每日谈
  5. GitHub: llvm-tutor
  6. Writing an LLVM Pass: 101
  7. 官方文档：Getting Started with the LLVM System
  8. 官方文档：Writing an LLVM Pass
  9. 官方文档：LLVM Programmer’s Manual
  10. 官方文档：LLVM Tutorial
  11. 一本较新的相关书籍：Learn LLVM 17, 2nd Edition
  12. 一本较新的相关书籍：LLVM Techniques, Tips, and Best Practices Clang and Middle-End Libraries
  13. 一篇讲解CMake、Ninja等构建工具的知乎文章