Nevermind, I got it backwards-- I see correct output from GCC now too.
UPDATE: Although GCC is still compiling its Java front-end
I always build only C/C++, otherwise it is really painful.
By the way, I used to think that extensive use of intXX_t types made Csmith-generated programs absolutely portable, but this is an example of target platform nuances changing the meaning of a Csmith-generated program (not that there is anything wrong with that).
We hoped they would be portable. As you say, that are not. As far as we can tell, the design of the C language prevents it, basically.
John