[Bug tree-optimization/122236] New: final reduction step not optimal for "omp simd"

[vincenzo.innocente at cern dot ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122236

            Bug ID: 122236
           Summary: final reduction step not optimal for "omp simd"
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vincenzo.innocente at cern dot ch
  Target Milestone: ---

float sum3(float const * v ) {
  float s=0;
  #pragma omp simd reduction(+:s)
  for (int i=0; i<1024; ++i) s += v[i]; 
  return s;
}

produces a not optimal final step when compiled with
-O3 -march=x86-64-v3 -fopenmp-simd
compared with 
-O3 -march=x86-64-v3 -ffast-math

see https://godbolt.org/z/drs8h6qY5