[AVX512] Correct isExtractSubvectorCheap so that it will return the correct answers for extracting 128-bits from a 512-bit vector and for mask registers.
Previously it would not return true for extracting either of the upper quarters of a 512-bit registers.
For mask registers we support extracting anything from index 0. And otherwise we only support extracting the upper half of a register.
Differential Revision: https://reviews.llvm.org/D36638
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310794 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed