[PATCH] D117957: [AVR] Remove unused register scavenger

[Ben Shi via Phabricator via llvm-commits]

benshi001 added inline comments.


================
Comment at: llvm/lib/Target/AVR/AVRExpandPseudoInsts.cpp:796
 
-  // Use a temporary register if src and dst registers are the same.
-  if (DstReg == SrcReg)
-    TmpReg = scavengeGPR8(MI);
-
-  Register CurDstLoReg = (DstReg == SrcReg) ? TmpReg : DstLoReg;
-  Register CurDstHiReg = (DstReg == SrcReg) ? TmpReg : DstHiReg;
+  assert(DstReg != SrcReg && "SrcReg and DstReg cannot be the same");
 
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benshi001 wrote:
> I did not understand how this assert is guranteed for LPM/ELPM.
Do we need a constraint like `Constraints = "$src != $rd"` in the definition of LPM/ELPM to gurantee that ?


Repository:
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  https://reviews.llvm.org/D117957/new/

https://reviews.llvm.org/D117957