[all-commits] [llvm/llvm-project] aaca8e: [AArch64] Don't recreate nodes in tryCombineLongOp...

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: aaca8e2c3489652ebdf27712ab396984fa577c1e
      https://github.com/llvm/llvm-project/commit/aaca8e2c3489652ebdf27712ab396984fa577c1e
  Author: David Green <david.green at arm.com>
  Date:   2023-06-26 (Mon, 26 Jun 2023)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    M llvm/test/CodeGen/AArch64/abd-combine.ll

  Log Message:
  -----------
  [AArch64] Don't recreate nodes in tryCombineLongOpWithDup

If we don't find a node with either operand through
isEssentiallyExtractHighSubvector, there is little point
recreating the node with the same operands. Returning
SDValue better communicates that no changes were made.

This fixes #63491 by not recreating uabd nodes with swapped
operands. As noted in the ticket there are other fixes that
might be useful to make too, but this should prevent the
infinite combine.