GCC 4.0.0 fsincos?

[Uros Bizjak]

Hello!

>If I compile with
>
>$ ~/usr/bin/gcc-4.0.0 -S Com_Code.cc -ffast-math -O2
>
>the relevant generated code section is
>
>#APP
>	fldln2; fxch; fyl2x
>#NO_APP
>	fmulp	%st, %st(2)
>	fxch	%st(1)
>#APP
>	fsqrt
>#NO_APP
>	fld	%st(1)
>#APP
>	fsin
>#NO_APP
>	fxch	%st(2)
>#APP
>	fcos
>#NO_APP
>
>
>So after generating R, a separate fsin and fcos seem to be generated. Am I
>missing an option or something?
>
You should use -ffast-math together with -D__NO_MATH_INLINES in your 
compile flags, or use a newer glibc. -D__NO_MATH_INLINES should also be 
used for -mfpmath=sse to prevent generation of x87 instructions from 
mathinline.h header when SSE code is used for FP math operators. 
Otherwise  xmm reg->mem->x87 reg moves will kill your performance.

Uros.

Uros.