[PATCH] D61671: X86WinAllocaExpander: Drop code looking through register copies (PR41786)

[Hans Wennborg via Phabricator via llvm-commits]

hans updated this revision to Diff 198624.
hans marked 2 inline comments as done.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61671/new/

https://reviews.llvm.org/D61671

Files:
  llvm/lib/Target/X86/X86WinAllocaExpander.cpp


Index: llvm/lib/Target/X86/X86WinAllocaExpander.cpp
===================================================================
--- llvm/lib/Target/X86/X86WinAllocaExpander.cpp
+++ llvm/lib/Target/X86/X86WinAllocaExpander.cpp
@@ -84,10 +84,6 @@
   unsigned AmountReg = MI->getOperand(0).getReg();
   MachineInstr *Def = MRI->getUniqueVRegDef(AmountReg);
 
-  // Look through copies.
-  while (Def && Def->isCopy() && Def->getOperand(1).isReg())
-    Def = MRI->getUniqueVRegDef(Def->getOperand(1).getReg());
-
   if (!Def ||
       (Def->getOpcode() != X86::MOV32ri && Def->getOpcode() != X86::MOV64ri) ||
       !Def->getOperand(1).isImm())
@@ -268,17 +264,10 @@
   unsigned AmountReg = MI->getOperand(0).getReg();
   MI->eraseFromParent();
 
-  // Delete the definition of AmountReg, possibly walking a chain of copies.
-  for (;;) {
-    if (!MRI->use_empty(AmountReg))
-      break;
-    MachineInstr *AmountDef = MRI->getUniqueVRegDef(AmountReg);
-    if (!AmountDef)
-      break;
-    if (AmountDef->isCopy() && AmountDef->getOperand(1).isReg())
-      AmountReg = AmountDef->getOperand(1).isReg();
-    AmountDef->eraseFromParent();
-    break;
+  // Delete the definition of AmountReg.
+  if (MRI->use_empty(AmountReg)) {
+    if (MachineInstr *AmountDef = MRI->getUniqueVRegDef(AmountReg))
+      AmountDef->eraseFromParent();
   }
 }
 


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