Commit d5f281b734425fc1d930ff2c3f8441aad731343e
2018-09-28T15:46:35
SIMD: Fix c000001d exception on Win 7 w/o SP1 Apparently Windows 7 without SP1 has O/S support for XSAVE but not for YMM registers, and this exposed a bug in our usage of xgetbv. The test instruction will set ZF only if none of the bits match between the two operarands, so in effect, we were enabling AVX2 instructions if the O/S supported XSAVE and the CPU supported AVX2 but the O/S only supported XMM registers. This bug was not exposed on, for instance, Windows XP or RHEL 5 because those O/S's do not support XSAVE. Fixes #288