[actionfromafar]

No, gcc optimizes code output and can make code shorter and faster. A compiler can make many, many decisions which will show up as differences in the binary output.

[mizzao]

In my question above, both compilers are 30cc, except one of the 30cc's was compiled by gcc and the other self-hosted.

[actionfromafar]

Ah, sorry. In that case, my guess is, probably yes. The outputs of both of these are probably the same. But not for certain - see:

https://www.cs.cmu.edu/~rdriley/487/papers/Thompson_1984_Ref...