[Bug tree-optimization/66740] [6 Regression] omp simd reduction miscompiles at -O3 with AVX (recent regression)

[tprince at computer dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66740

--- Comment #4 from tprince at computer dot org ---
It optimizes with implicit simd reduction and gives correct result with option
-ffast-math in place of -fopenmp.