[PATCH] D136672: [ExpandMemCmp][AArch64] Add a new option PreferCmpToExpand in inMemCmpExpansionOptions and enable on AArch64

[Allen zhong via Phabricator via llvm-commits]

Allen added a comment.

> I have rebase to the code already include D136244 <https://reviews.llvm.org/D136244>. These two tickets looks the same but it looks D136244 <https://reviews.llvm.org/D136244> can't fix the original case bcmp 3bytes. 
> And not only AArch64, maybe this change also help some potential platform.



- For the case bcmp3, the combine pattern is mismatch as we restrict to **ISD::XOR**, so the **ISD::AND** may be enhanced too ?

  (gdb) p LHS.getOperand(0)->getOpcode() == ISD::XOR && LHS.getOperand(1)->getOpcode() == ISD::XOR
  $16 = false
  (gdb) p LHS.dump()
  t20: i32 = or t46, t50
  $17 = void
  (gdb) p LHS.getOperand(0).dump()
  t46: i32 = and t44, Constant:i32<65535>
  $18 = void
  (gdb) p LHS.getOperand(1).dump()
  t50: i32 = and t48, Constant:i32<255>




CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D136672/new/

https://reviews.llvm.org/D136672