[X86][AVX] Improve (i8 bitcast (v8i1 x)) handling for 256-bit vector compare results.

As commented on D37849, AVX1 targets were missing a chance to use vmovmskps for v8f32/v8i32 results for bool vector bitcasts


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313547 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed