ctflgrdiff

Does side-by-side diffs of control flow graphs by comparing basic blocks in a way that can ignore all differences in block and value names. It only cares about the structure of the code when doing the comparison. It uses an algorithm similar to Needleman–Wunsch algorithm.

Building

You will need a Rust toolchain and LLVM 14 in order to support LLVM IR diffing. To build:

cargo build

This can also build a Python module. To do that:

pip install maturin
cd pylib
maturin build

Usage

First, create the two files you wish to diff:

cat > foo_int.c <<EOI
int foo(int x, int y) {
 return x * y + y;
}
EOI

cat > foo_long.c <<EOI
int foo(long x, long y) {
 return (int)(x * y + y);
}
EOI

clang -emit-llvm -c foo_int.c foo_long.c

Then you can diff the two files:

ctflgrdiff -f ll-bc foo_int.bc foo_long.bc

The demo directory contains example pairs of C code.

Supported Binary Formats

• ll-ir: LLVM text IR; note that LLVM 15+ use a different pointer format that will trigger LLVM 14 to segfault
• ll-bc: LLVM bitcode; note that LLVM 15+ use a different pointer format that will trigger LLVM 14 to segfault
• arm64 aka aarch64 aka armv8: 64-bit ARM code in a binary
• arm32 aka aarch32 aka armv7: 32-bit ARM code in a binary
• avr: ATmel AVR code in a binary; note that it cannot be in a fat MachO binary
• x86 aka x86-32 aka x86_32 aka i386 aka i686: 32-bit Intel code in a binary
• x64 aka x86-64 aka x86_64: 64-bit Intel code in a binary

For all formats in a binary, an ELF, MachO, or PE (Windows) executable, library, or object file can be provided. An archive (.a) file containing ELF, MachO, or PE object files is also supported. MachO multi-architecture (aka fat) binaries are supported and only the instruction set requested will be used.

Where appropriate, function names will go through C++ and Rust symbol demangling.