https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125484
Bug ID: 125484
Summary: `(double)us1 < (double)us0` simplifying to `us1 < us0`
sometimes gets in the way of detecting min/max
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Blocks: 26163
Target Milestone: ---
Take:
```
typedef unsigned short Quantum;
static const double QuantumScale = 1.0/65535.0;
void ConvertRGBToHSB(Quantum red, Quantum green, Quantum blue,
double *hue, double *saturation, double *brightness) {
double b, delta, g, max, min, r;
*hue=0.0; *saturation=0.0; *brightness=0.0;
r=(double) red; g=(double) green; b=(double) blue;
min=r < g ? r : g; if (b < min) min=b;
max=r > g ? r : g; if (b > max) max=b;
if (max == 0.0) return;
delta=max-min;
*saturation=delta/max;
*brightness=QuantumScale*max;
if (delta == 0.0) return;
if (r == max) *hue=(g-b)/delta;
else if (g == max) *hue=2.0+(b-r)/delta;
else *hue=4.0+(r-g)/delta;
*hue/=6.0;
if (*hue < 0.0) *hue+=1.0;
}
```
Which is extracted from imagic. We change `r < g` and `r < g` to use red/green
directly and that produces slightly better code but then we miss that this
should have been min/max. and then lowered.
Even `r == max` should be improved.
So should `delta == 0.0` (but that is related to PR 124571)
I am not sure match patterns will help here.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2026, 2k17, 2k and 2k6 and
95)
