https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112752
Bug ID: 112752
Summary: `~a - MIN<MIN<~a, ~b>, ~c>` is not optimized to
`MAX<MAX<a,b>,c> - a`
Product: gcc
Version: 14.0
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
CC: evstupac at gmail dot com, kirill.yukhin at intel dot com,
pinskia at gcc dot gnu.org, rguenth at gcc dot gnu.org,
unassigned at gcc dot gnu.org
Target Milestone: ---
Target: x86_64-*-*
+++ This bug was initially created as a clone of Bug #52252 +++
This is an example of byte conversion from RGB (Red Green Blue) to CMYK (Cyan
Magenta Yellow blacK):
```
#define byte unsigned char
#define MIN(a, b) ((a) > (b)?(b):(a))
void convert_image(byte *in, byte *out, int size) {
int i;
for(i = 0; i < size; i++) {
byte r = in[0];
byte g = in[1];
byte b = in[2];
byte c, m, y, k, tmp;
c = 255 - r;
m = 255 - g;
y = 255 - b;
tmp = MIN(m, y);
k = MIN(c, tmp);
out[0] = c - k;
out[1] = m - k;
out[2] = y - k;
out[3] = k;
in += 3;
out += 4;
}
}
```
For the scalar (and vectorized versions) we should get instead:
```
#define byte unsigned char
#define MIN(a, b) ((a) > (b)?(b):(a))
#define MAX(a, b) ((a) < (b)?(b):(a))
void convert_image_1(byte *in, byte *out, int size) {
int i;
for(i = 0; i < size; i++) {
byte r = in[0];
byte g = in[1];
byte b = in[2];
byte c, m, y, k, tmp;
tmp = MIN(r, g);
k = MIN(b, tmp);
out[0] = k - r;
out[1] = k - g;
out[2] = k - b;
out[3] = 255 - k;
in += 3;
out += 4;
}
}
```
See bug 52252 comment #10, 11, and 12 also.
