narrowed down the problem area

[downs]

downs wrote:
> Especially interesting to note (slow case):
> 
>     fstpl    -24(%ebp)
> [...]
>     movl    -24(%ebp), %eax
>     movl    %eax, -48(%ebp)
>     movl    -20(%ebp), %eax
>     movl    %eax, -44(%ebp)
> 
> Translation:
> 	Store floating-point number to ebp[-24]. No, wait, move it to ebp[-48].

I left something out.

    fstpl    -24(%ebp)
[...]
    movl    -24(%ebp), %eax
    movl    %eax, -48(%ebp)
    movl    -20(%ebp), %eax
    movl    %eax, -44(%ebp)
[...]
    fldl    -48(%ebp)


So, the whole thing comes down to "Store FP number to memory. No wait, move it somewhere else! No wait, read it back!"

No wonder it's slow.