[Bug c/66740] 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 #2 from tprince at computer dot org ---
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/gcc6.0/libexec/gcc/x86_64-unknown-cygwin/6.0.0/lt
o-wrapper.exe
Target: x86_64-unknown-cygwin
Configured with: ../configure --prefix=/usr/local/gcc6.0 --enable-languages='c
c
++ fortran' --enable-libgomp --enable-threads=posix --with-dwarf2
--without-libi
conv-prefix --without-libintl-prefix --with-system-zlib --disable-werror
--witho
ut-cloog --without-isl
Thread model: posix
gcc version 6.0.0 20150630 (experimental) (GCC)