[X86][AVX] Add combineConcatVectors support to improve subvector handling
Attempt to combine CONCAT_VECTORS nodes, which we only really have pre-legalization.
This encourages a lot of X86ISD::SUBV_BROADCAST generation, so I've added SimplifyDemandedVectorEltsForTargetNode handling for this at the same time.
The X86ISD::VTRUNC regression in shuffle-vs-trunc-256-widen.ll will be handled in a future commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356064
91177308-0d34-0410-b5e6-
96231b3b80d8
projects / llvm / commit