[x86] be more selective about converting 'and' to shuffle (PR37749)
isVectorClearMaskLegal() is the TLI hook used by the generic
DAGCombiner::XformToShuffleWithZero().
We've grown to accomodate/expect this transform to shuffle
(disabling it more generally results in many regressions).
So I'm narrowly excluding the 256-bit types that clearly
are not worthwhile for AVX1.
I think in most cases we are able to recover by converting
the shuffle back into 'and' ops, but the cases in:
https://bugs.llvm.org/show_bug.cgi?id=37749
...show that there are cracks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334759 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed