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.