[all-commits] [llvm/llvm-project] e41a13: [X86] LowerShiftByScalarVariable - use getSplatSou...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e41a138520b424a15cf4f2d56cf9bb6fbb14ae09
      https://github.com/llvm/llvm-project/commit/e41a138520b424a15cf4f2d56cf9bb6fbb14ae09
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2022-02-24 (Thu, 24 Feb 2022)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/vector-shift-ashr-128.ll
    M llvm/test/CodeGen/X86/vector-shift-ashr-256.ll
    M llvm/test/CodeGen/X86/vector-shift-ashr-512.ll
    M llvm/test/CodeGen/X86/vector-shift-lshr-128.ll
    M llvm/test/CodeGen/X86/vector-shift-lshr-256.ll
    M llvm/test/CodeGen/X86/vector-shift-lshr-512.ll
    M llvm/test/CodeGen/X86/vector-shift-shl-128.ll
    M llvm/test/CodeGen/X86/vector-shift-shl-256.ll
    M llvm/test/CodeGen/X86/vector-shift-shl-512.ll

  Log Message:
  -----------
  [X86] LowerShiftByScalarVariable - use getSplatSourceVector for vXi8 shift expansion

Using getSplatValue causes poor codegen due to not always being able to remove the EXTRACT_VECTOR_ELT created inside getSplatValue.

The vXi16 shifts/rotates are still showing occasional regressions but vXi8 is a definite improvement.