[all-commits] [llvm/llvm-project] 307890: [X86] Freeze vXi8 shl(x, 1) -> add(x, x) vector fold...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 307890f85b33bc190b563bcb3daeb232b8ecaa73
      https://github.com/llvm/llvm-project/commit/307890f85b33bc190b563bcb3daeb232b8ecaa73
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2021-08-24 (Tue, 24 Aug 2021)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/bitreverse.ll
    M llvm/test/CodeGen/X86/combine-bitreverse.ll
    M llvm/test/CodeGen/X86/vector-bitreverse.ll
    M llvm/test/CodeGen/X86/vector-fshl-rot-128.ll
    M llvm/test/CodeGen/X86/vector-fshl-rot-256.ll
    M llvm/test/CodeGen/X86/vector-fshl-rot-512.ll
    M llvm/test/CodeGen/X86/vector-fshr-128.ll
    M llvm/test/CodeGen/X86/vector-fshr-256.ll
    M llvm/test/CodeGen/X86/vector-fshr-rot-128.ll
    M llvm/test/CodeGen/X86/vector-fshr-rot-256.ll
    M llvm/test/CodeGen/X86/vector-fshr-rot-512.ll
    M llvm/test/CodeGen/X86/vector-rotate-128.ll
    M llvm/test/CodeGen/X86/vector-rotate-256.ll

  Log Message:
  -----------
  [X86] Freeze vXi8 shl(x,1) -> add(x,x) vector fold (PR50468)

We don't have any vXi8 shift instructions (other than on XOP which is handled separately), so replace the shl(x,1) -> add(x,x) fold with shl(x,1) -> add(freeze(x),freeze(x)) to avoid the undef issues identified in PR50468.

Split off from D106675 as I'm still looking at whether we can fix the vXi16/i32/i64 issues with the D106679 alternative.

Differential Revision: https://reviews.llvm.org/D108139