https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66740
Bug ID: 66740 Summary: omp simd reduction miscompiles at -O3 with AVX (recent regression) Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: tprince at computer dot org Target Milestone: --- Created attachment 35897 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35897&action=edit f2c include file This regression is new in the last 2 weeks. gcc -O3 -march=sandybridge -std=c99 -D__assume_aligned= -fopenmp -c s115.c is miscompiled (bad numerical results when run under test harness). It is OK at -O2 or with -march=westmere, or with the omp directive disabled. It doesn't vectorize without the omp directive. It fails the same with -march=haswell. Similar versions using inner_product or Fortran dot_product are vectorizing correctly without omp simd.