Missing if optimization

[Andrew Pinski]

On Sep 8, 2004, at 10:19 PM, Uros Bizjak wrote:

> Hello!
>
> The if optimization, which produces quite optimized code for integer 
> case is missing for floatin-point compares.
>
> This code:
>
> int test(int a) {
>        return a == 0 ? 0 : (a > 0 ? 1 : -1);
> }
>
> produces (with -O2  -fomit-frame-pointer):
>
> test:
>        xorl    %eax, %eax
>        cmpl    $0, 4(%esp)
>        je      .L4
>        setg    %al
>        movzbl  %al, %eax
>        leal    -1(%eax,%eax), %eax
> .L4:
>        ret
>
> However, fp compares:
>
> double testf(double a) {
>        return a == 0.0 ? 0.0 : (a > 0.0 ? 1.0 : -1.0);
> }

On PPC we get only one compare:
(This is with a month old compiler):
_testf:
         lis r2,ha16(LC0)
         la r2,lo16(LC0)(r2)
         lfd f0,0(r2)
         fcmpu cr7,f1,f0 <-- the one and only compare
         beq- cr7,L4
         lis r2,ha16(LC1)
         la r2,lo16(LC1)(r2)
         lfd f0,0(r2)
         bgt- cr7,L8
L4:
         fmr f1,f0
         blr
L8:
         lis r2,ha16(LC2)
         la r2,lo16(LC2)(r2)
         lfd f0,0(r2)
         fmr f1,f0
         blr

Thanks,
Andrew Pinski