As I recall (and I am pulling from stale memory), we generally concluded that Intel had the more strictly correct behavior. Our numerical algorithms were design

As I recall (and I am pulling from stale memory), we generally concluded that Intel had the more strictly correct behavior. Our numerical algorithms were designed in Julia and we had some pretty rigorous formal models for what they should be producing. I had a similar experience compiling complex C++ code bases in both GCC and Clang. There were interesting edge cases that cropped up where the compilers apparently had a fundamental disagreement on how to interpret a bit of code. Every time we did deep dive to understand the discrepancy, we came to the conclusion that Clang was probably correct strictly speaking. This still caused us problems and we ended up designing work arounds to support GCC.