[llvm-branch-commits] [CodeGen] Add 2 subtarget hooks canLowerToZeroCycleReg[Move|Zeroing] (PR #148428)

[Matt Arsenault via llvm-branch-commits]

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@@ -185,6 +185,48 @@ class LLVM_ABI TargetSubtargetInfo : public MCSubtargetInfo {
     return false;
   }
 
+  /// Returns true if CopyMI can be lowered to a zero cycle register move.
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arsenm wrote:

Can you avoid adding new hooks for this? Isn't this inferable from the sched model? Plus plenty of places essentially treat copy as free anyway (e.g. isTransient) 

https://github.com/llvm/llvm-project/pull/148428