use gcc -fdump-translation-unit switch compile old code, compile new code. compare the differenct between the old gcc AST against the new gcc AST (or differenc

use gcc -fdump-translation-unit switch compile old code, compile new code. compare the differenct between the old gcc AST against the new gcc AST (or differences between the AST's generated when different compile switches are used) Doesn't mean there aren't assembly language differeces, but will narrow things down.