If you've ever stared at a large C codebase wondering whether two function calls touch the same shared state, you know the pain. Manual code review is error-prone, and full program analysis can be overkill. prongC was built to solve exactly this problem. It's a lightweight static analysis tool that detects shared variable accesses between function calls without requiring whole-program analysis.

The Problem It Solves

Consider this scenario: you have two function calls in your code:
foo(arg1, arg2, shared_arg);
bar(shared_arg, arg3);

Can you safely reorder them? Do they both read or modify the same variables? prongC gives you a definitive answer by tracing how each argument flows through the function bodies.

Key features

• No whole-program analysis - prongC only works with the functions and files you specify
• Individual parameter and global tracing - prongC can identify all variable accesses to globals or parameters you specify individually
• Compile database support - works seamlessly with compile_commands.json
• Multithreaded parsing - parse C files faster with -j option

Usage

You tell prongC which files to analyze and which function calls to examine:

prongc --files="file1.c,file2.c" \
       --functions="foo(arg1, arg2, shared_arg);bar(shared_arg, arg3)" \
       -j8

The tool traces how each argument is used through the program and reports any overlaps.

You can also trace individual parameters of functions or globals by name:

prongc --files="file.c" \
       --functions="foo(arg1)" \
       --trace="foo@arg1"

Useful for

• Finding hidden variable access overlaps
• Verifying function call reordering safety
• Investigating side effects in legacy C code you're maintaining
• Exploring data dependencies across multiple files
• Undestanding unfamiliar codebases faster by uncovering data relationships