https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121029
Bug ID: 121029 Summary: GCC does not vectorize conditional min/max reduction 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: 53947 Target Milestone: --- Take: ``` #define N 32 unsigned int ub[N]; unsigned int uc[N]; unsigned int doesnot (unsigned int b, unsigned int c) { unsigned int umax = 0; /* max. */ for (int i = 0; i < N; i++) { int t = uc[i]; if (ub[i] < N/2 ) umax = umax > t ? umax : t; } return umax; } ``` GCC does not know how to vectorize conditional min/max reductions. I didn't find a bug report for this so I am filing one. It could be vectorized like: Loop: t = uc[i]; t = ub[i] < N/2 ? t : umax; umax = MAX<umax, t>; endloop MAX_reduction<umax> Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947 [Bug 53947] [meta-bug] vectorizer missed-optimizations