ICC is a proprietary compiler which not only focuses it's optimizations on their own cpu range but also have a history of deliberately generating subpar codepaths for non-Intel cpu's.
MVSC is Windows only proprietary compiler and certainly hasn't had stellar C++ standard support although they are trying to rectify that with their recent 'Go native' push.
I have had no experience with IBM's XLCC compilers though, maybe someone else has?
Are they really that much better? I remember hitting a bunch of incorrectly generated code for MSVC++ at least back in the 6.0 days. Like, the disassembly revealed dangerously incorrect code.
I don't know much about MSVC++, but Intel's compilers are widely considered the most advanced C++ compilers, as long as you stick with Intel hardware. There was some controversy over it generating bad assembly when targeting AMD cores, but this is a non-issue for companies like Boeing and Raytheon, who will be using custom hardware anyway.
The controversy was that it generated a CPUID check for "GenuineIntel" at runtime, and fell back to extremely poorly generated code (like, 386-level, almost 286-level style) for all other CPUs, as far as I remember.
Borderline intentional sabotage against AMD, because they can obviously do better and I don't believe they are unaware of the capabilities of AMD CPUs.
(edit: And they should probably be checking for features instead of vendor IDs anyways. It's like checking for Firefox in the user-agent and sending animated GIFs instead of WebGL if you're on Chrome)
