[PATCH] D72361: [DAGCombiner] reduce extract subvector of concat

[Sanjay Patel via Phabricator via llvm-commits]

spatel created this revision.
spatel added reviewers: craig.topper, RKSimon, lebedev.ri.
Herald added subscribers: hiraditya, mcrosier.
Herald added a project: LLVM.

If we are extracting a chunk of a vector that's smaller than an operand of the concatenated vector operand, we can extract directly from one of those original operands.
This is another suggestion from PR42024:
https://bugs.llvm.org/show_bug.cgi?id=42024#c2

But I'm not sure yet if it will make any difference on those patterns. It seems to help a few existing AVX512 tests though.

Most of the code diff here is refactoring, so I can make that a preliminary commit if preferred.


https://reviews.llvm.org/D72361

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/X86/avg.ll
  llvm/test/CodeGen/X86/pr34657.ll
  llvm/test/CodeGen/X86/x86-interleaved-access.ll

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