[all-commits] [llvm/llvm-project] 25abe2: [X86] Improve handling of i512 SRA(MSB, Amt) "highb...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 25abe22ed85202a68118dd6f0cc0ac3d513e6d90
      https://github.com/llvm/llvm-project/commit/25abe22ed85202a68118dd6f0cc0ac3d513e6d90
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2026-03-18 (Wed, 18 Mar 2026)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/shift-i512.ll

  Log Message:
  -----------
  [X86] Improve handling of i512 SRA(MSB,Amt) "highbits" mask creation (#187141)

This can be folded from ((1 << 511) >>s Amt) -> (-1 << (511-Amt)) to make use of the existing optimal codegen

Alive2: https://alive2.llvm.org/ce/z/9UMQkm

Last i512 pattern described in #132601



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