Dylan William Hardison wrote:
> ...
> So, I'll throw something out there to start discussion.
>
> If SDL_BYTEORDER and SDL_BIG_ENDIAN are preprocessor constants,
> is GCC smart enough to optimize this if-else expression away?
> I have no idea, and I'm not sure how to test it.
>
> if (SDL_BYTEORDER == SDL_BIG_ENDIAN) {
> color = SDL_MapRGBA(dst->format, colorptr[0], colorptr[1],
> colorptr[2], colorptr[3]);
> } else {
> color = SDL_MapRGBA(dst->format, colorptr[3], colorptr[2],
> colorptr[1], colorptr[0]);
> }
Gcc is way too smart to emit a runtime test in this case.
To confirm:
I looked up "gcc interspersed listing" with Google and found
http://www.linuxjournal.com/article/7269 which told me that to get
interspersed C/assembler listings from gcc to use "gcc -c -g -Wa,-ahl,-L".
Judging by the output I get from some simple test programs gcc does not emit
the test or instructions for the branch never taken.
-- Mark Polhamus
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