the code is as follow:
inline double fsincos(double x)
First, I compiled it to assembly source with no optimization enabled, just using defaults as follow:
> gcc -c -S fsincos.c -o fsincos.s
and then open the generated assembly code in fsincos.s. Overthere I saw somewhere it called internal library functions for sin and cos trigonometry functions as I expected. I then recompiled it with full optimization flags enabled:
> gcc -c -S -mtune=athlon64 -mfpmath=sse -msse3 -ffast-math -m64 -O3 fsincos.c -o fsincos64.s
Suprisingly, it still called GNU's "sin" and "cos" math functions!. What? I said (not loud, though). I checked again the gcc man page, nothing special about these things. Hm....let's try to add "387" in the mfpmath, I said in my mind.
So, the command is now as follow:
gcc -c -S -mtune=athlon64 -mfpmath=387,sse -msse3 -ffast-math -m64 -O3 fsincos.c -o fsincos64.s
Voila! now the assembly code called inline FP code "fsincos" in it. Since then, I add an environment variable in the enviroment as follow:
export CFLAGS="-mtune=athlon64 -mfpmath=387,sse -msse3 -ffast-math -m64"