That's why you don't compare the GCC binaries built by different compilers. Instead, you use each of those GCC binaries (which may use different machine code b

That's why you don't compare the GCC binaries built by different compilers. Instead, you use each of those GCC binaries (which may use different machine code but should implement the exact same functionality) to build another GCC, and you compare those binaries. That should result in identical binaries as long as GCC: - is deterministic, - does not invoke undefined behavior, and - was correctly compiled by the original compilers.