rfa (x86): 387<=>sse moves

[Uros Bizjak]

Hello!

> With -march=pentium4 -mfpmath=sse -O2, we get an extra move for code like
>
>    double d = atof(foo);
>    int i = d;
>
>
>        call    atof
>        fstpl   -8(%ebp)
>        movsd   -8(%ebp), %xmm0
>        cvttsd2si       %xmm0, %eax
>
>
> (This is Linux, Darwin is similar.) I think the difficulty is that for

This problem is similar to the problem, described in PR target/19398. 
There is another testcase and a small analysis in the PR that might help 
with this problem.

Uros.