[DebugInfo][Dexter] Incorrect DBG_VALUE after MCP dead copy instruction removal.
When MachineCopyPropagation eliminates a dead 'copy', its associated debug information becomes invalid. as the recorded register has been removed. It causes the debugger to display wrong variable value.
Differential Revision: https://reviews.llvm.org/D52614
llvm-svn: 343445
diff --git a/llvm/lib/CodeGen/MachineCSE.cpp b/llvm/lib/CodeGen/MachineCSE.cpp
index fa785ac..dcb6f7c 100644
--- a/llvm/lib/CodeGen/MachineCSE.cpp
+++ b/llvm/lib/CodeGen/MachineCSE.cpp
@@ -181,12 +181,8 @@
LLVM_DEBUG(dbgs() << "Coalescing: " << *DefMI);
LLVM_DEBUG(dbgs() << "*** to: " << *MI);
- // Collect matching debug values.
- SmallVector<MachineInstr *, 2> DbgValues;
- DefMI->collectDebugValues(DbgValues);
- // Propagate SrcReg to debug value instructions.
- for (auto *DBI : DbgValues)
- DBI->getOperand(0).setReg(SrcReg);
+ // Update matching debug values.
+ DefMI->changeDebugValuesDefReg(SrcReg);
// Propagate SrcReg of copies to MI.
MO.setReg(SrcReg);