[PATCH] D110995: [X86] combineMulToPMADDWD - handle any pow2 vector type and split to legal types

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: craig.topper, xbolva00, lebedev.ri, pengfei.
Herald added subscribers: hiraditya, inglorion.
RKSimon requested review of this revision.
Herald added a project: LLVM.

combineMulToPMADDWD is currently limited to legal types, but there's no reason why we can't handle any larger type that the existing SplitOpsAndApply code can use to split to legal X86ISD::VPMADDWD ops.

This also exposed a missed opportunity for pre-SSE41 targets to handle SEXT ops from types smaller than vXi16 - without PMOVSX instructions these will always be expanded to unpack+shifts, so we can cheat and convert this into a ZEXT(SEXT()) sequence to make it a valid PMADDWD op.

There's still one regression in the SSE2 larger_mul test that I'm currently investigating.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D110995

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/madd.ll
  llvm/test/CodeGen/X86/pmaddubsw.ll
  llvm/test/CodeGen/X86/pmulh.ll
  llvm/test/CodeGen/X86/shrink_vmul.ll
  llvm/test/CodeGen/X86/slow-pmulld.ll
  llvm/test/CodeGen/X86/vshli-simplify-demanded-bits.ll

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