[RA] Fix the live range for early-clobber

Yuanke Luo · Yuanke Luo · commit 447fec6e0369 · 2025-08-10T15:02:42.000+08:00
When rematerialize a virtual register the register may be early clobbered.
However rematerializeAt(...) just return the slot index of Slot_Register
which cause mis-calculating live range for the register
diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -192,7 +192,9 @@ SlotIndex LiveRangeEdit::rematerializeAt(MachineBasicBlock &MBB,
 
   if (ReplaceIndexMI)
     return LIS.ReplaceMachineInstrInMaps(*ReplaceIndexMI, *MI).getRegSlot();
-  return LIS.getSlotIndexes()->insertMachineInstrInMaps(*MI, Late).getRegSlot();
+  bool EarlyClobber = MI->getOperand(0).isEarlyClobber();
+  return LIS.getSlotIndexes()->insertMachineInstrInMaps(*MI, Late).getRegSlot(
+      EarlyClobber);
 }
 
 void LiveRangeEdit::eraseVirtReg(Register Reg) {

Original file line number	Diff line number	Diff line change
`@@ -192,7 +192,9 @@ SlotIndex LiveRangeEdit::rematerializeAt(MachineBasicBlock &MBB,`
`192`	`192`
`193`	`193`	`if (ReplaceIndexMI)`
`194`	`194`	`return LIS.ReplaceMachineInstrInMaps(ReplaceIndexMI, MI).getRegSlot();`
`195`		`- return LIS.getSlotIndexes()->insertMachineInstrInMaps(*MI, Late).getRegSlot();`
	`195`	`+ bool EarlyClobber = MI->getOperand(0).isEarlyClobber();`
	`196`	`+ return LIS.getSlotIndexes()->insertMachineInstrInMaps(*MI, Late).getRegSlot(`
	`197`	`+ EarlyClobber);`
`196`	`198`	`}`
`197`	`199`
`198`	`200`	`void LiveRangeEdit::eraseVirtReg(Register Reg) {`