GCC 4.0.0 fsincos?

[Patrick Mitran]

Hi,

I'm interested in gcc 4.0.0 because I believe it's supposed to generate
the fsincos instruction on x86 when appropriate.

I have the following code sample which I use to generate two random
Gaussian numbers, for which I think fsincos should probably be generated
by the compiler,


typedef double realv;
complex<realv> ComplexGaussRandom(realv s2, MTRand& Random)
{
 realv B = 2.0 * pi * Random.rand();
 realv R = sqrt( -s2 * log(1- Random.rand53()));
 return R * complex<realv>(cos(B), sin(B));
}

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
        fxch    %st(2)
        movl    8(%ebp), %eax
        fmul    %st(1), %st
        fxch    %st(1)
        fmulp   %st, %st(2)
        fstpl   8(%eax)
        fstpl   (%eax)
        addl    $12, %esp
        popl    %ebx
        popl    %esi
        popl    %edi
        popl    %ebp
        ret     $4

So after generating R, a separate fsin and fcos seem to be generated. Am I
missing an option or something?

Thanks,
Patrick

$ ~/usr/bin/gcc-4.0.0 -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc-4.0.0/configure --program-suffix=-4.0.0
--prefix=/home/mitran/usr
Thread model: posix
gcc version 4.0.0