[X86][AVX] Improve (i4 bitcast (v4i1 x)) handling for 256-bit vector compare results.

As commented on D37849 and rL313547, AVX1 targets were missing a chance to use vmovmskpd for v4f64/v4i64 results for bool vector bitcasts


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314293 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed