https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112985
--- Comment #1 from chenglulu <chenglulu at loongson dot cn> ---
(In reply to Xi Ruoyao from comment #0)
> /* { dg-do compile } */
> /* { dg-options "-O2 -ffast-math -fdump-tree-gimple" } */
>
> int
> short_circuit (float *a)
> {
> float t1x = a[0];
> float t2x = a[1];
> float t1y = a[2];
> float t2y = a[3];
> float t1z = a[4];
> float t2z = a[5];
>
> if (t1x > t2y || t2x < t1y || t1x > t2z || t2x < t1z || t1y > t2z || t2y
> < t1z)
> return 0;
>
> return 1;
> }
>
> on LoongArch it produces something like:
>
> _1 = t1x > t2y;
> _2 = t2x < t1y;
> _3 = _1 | _2;
> if (_3 != 0) goto <D.2205>; else goto <D.2207>;
> <D.2207>:
> _4 = t1x > t2z;
> _5 = t2x < t1z;
> _6 = _4 | _5;
> if (_6 != 0) goto <D.2205>; else goto <D.2208>;
> <D.2208>:
> _7 = t1y > t2z;
> _8 = t2y < t1z;
> _9 = _7 | _8;
> if (_9 != 0) goto <D.2205>; else goto <D.2206>;
> <D.2205>:
> D.2209 = 0;
>
> but it's better to produce 6 if (per
> https://gcc.gnu.org/pipermail/gcc-patches/2023-December/640313.html it will
> produce a 1.8% improvement in SPECCPU 2017 fprate).
>
> One obvious issue is LoongArch cost model for FP comparison is incorrect
> (PR112936) but even if I set the cost of floating-point comparison to 5000
> the gimple still produces 3 if with non-shorted comparisons.
I agree that the code should generate logic similar to a fixed point:
slt $r17,$r15,$r14
slt $r13,$r16,$r12
or $r13,$r13,$r17
bstrpick.w $r13,$r13,7,0
bnez $r13,.L3
