Programming and Scripting :: Compiler magic

Oh -- thanks for the SSE info. Yes you are right -- the error in x264 was in an assembly function.

If I remember correctly, the '-Os' errors (with both Xpdf and x264) occur both with gcc 3.x and gcc 4.x. I seem to remember I tried both gcc 3.3 and 4.1 (both Xpdf and x264).

Also:
As I understand it, '-O3' increases object size dramatically, unless we use the profiling feature ('-fprofile-generate' and '-fprofile-use'), in which case, the output is both fast AND relatively compact, which is great.