[PATCH] D40831: [AArch64] Only use writeback in the load/store optimizer when needed

[John Brawn via Phabricator via llvm-commits]

john.brawn added inline comments.


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Comment at: lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp:1346
+  // We need to use writeback only when the base register is used afterwards.
+  bool UseWriteback = !getLdStBaseOp(*I).isKill();
+  unsigned NewOpc;
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junbuml wrote:
> I'm not  sure if it's safe enough to use the kill marker here? Is this information still valid for us to rely on? 
The load/store optimizer in the ARM backend relies on it, so I would assume so. After some searching around I found TargetRegisterInfo::trackLivenessAfterRegAlloc which the AArch64 backend does return true for, and I couldn't find anything else that we would need to do to make sure it's valid.


Repository:
  rL LLVM

https://reviews.llvm.org/D40831