Lecture 14

LLVM and Clang

Lecture

Slides: PDF, PPTX

Notes: PDF

Outline

• LLVM Project: history and architecture
• LLVM IR
• Clang: parser and static analysis tool
• Clang Static Analyzer and its symbolic execution engine
• Clang Extra Tools: Clang-Tidy

Workshop

Outline

• Compiling/Installing LLVM
• Compiling C/C++ programs to executables and LLVM IR
• Exploring C/C++ programs with Clang (tokens, AST, call graph, CFG, exploded graph)
• Running Clang Static Analyzer
• Exploring Clang Static Analyzer and Clang-Tidy checks

Examples

• test.c

Tasks

Exploring test.c:

1. Dump tokens:

   clang -cc1 -dump-tokens test.c
   

2. Dump and view AST:

   clang -cc1 -ast-dump test.c
   clang -cc1 -ast-view test.c
   

3. Dump and view call graph:

   clang -cc1 -analyze -analyzer-checker="debug.DumpCallGraph" test.c
   clang -cc1 -analyze -analyzer-checker="debug.ViewCallGraph" test.c
   

4. View CFG and Exploded Graph:

   clang -cc1 -analyze -analyzer-checker="debug.ViewCFG" test.c
   clang -cc1 -analyze -analyzer-checker="debug.ViewExplodedGraph" test.c
   

References

• LLVM (Wikipedia)
• Clang (Wikipedia)
• LLVM Web Site
• LLVM Project (GitHub)
• Clang Static Analyzer - A Checker Developer’s Guide
• [LLVM] Chapters 2, 3, 4, 5, 9, 10
• LLVM Language Reference Manual