[all-commits] [llvm/llvm-project] d8fc9f: [X86][SSE] combineMulToPMADDWD - replace sext(v8i1...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d8fc9f87270146e271eddd551ea98580bef15e82
      https://github.com/llvm/llvm-project/commit/d8fc9f87270146e271eddd551ea98580bef15e82
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-09-24 (Fri, 24 Sep 2021)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/madd.ll

  Log Message:
  -----------
  [X86][SSE] combineMulToPMADDWD - replace sext(v8i16) -> zext(v8i16)

As suggested on D108522, if we're sign extending a v4i16 source before multiplying as a v4i32, then we can replace that with a zero extension and rely on the implicit sign-extension of PMADDWD.