https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93806
--- Comment #12 from Rich Felker <bugdal at aerifal dot cx> --- To me the meaning of internal consistency is very clear: that the semantics of the C language specification are honored and that the only valid transformations are those that follow the "as-if rule". Since C without Annex F allows arbitrarily awful floating point results, your example in comment 11 is fine. Each instance of 1/a can evaluate to a different value. They could even evaluate to random values. However, if you had written: int b = 1/a == 1/0.; int c = b; return b == c; then the function must necessarily return 1, because the single instance of 1/a==1/0. in the abstract machine has a single value, either 0 or 1, and in the abstract machine that value is stored to b, then copied to c, and b and c necessarily have the same value. While I don't think it's likely that GCC would mess up this specific example, it seems that it currently _can_ make transformations such that a more elaborate version of the same idea would be broken.
