3 files changed, 17 insertions, 6 deletions
diff --git a/llvm/lib/CodeGen/MachineCSE.cpp b/llvm/lib/CodeGen/MachineCSE.cpp
index fa785ac0c5a..dcb6f7cca4f 100644
--- a/llvm/lib/CodeGen/MachineCSE.cpp
+++ b/llvm/lib/CodeGen/MachineCSE.cpp
@@ -181,12 +181,8 @@ bool MachineCSE::PerformTrivialCopyPropagation(MachineInstr *MI,
     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);
diff --git a/llvm/lib/CodeGen/MachineCopyPropagation.cpp b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
index b5309087d50..dfaa946c913 100644
--- a/llvm/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -598,6 +598,11 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
       LLVM_DEBUG(dbgs() << "MCP: Removing copy due to no live-out succ: ";
                  MaybeDead->dump());
       assert(!MRI->isReserved(MaybeDead->getOperand(0).getReg()));
+
+      // Update matching debug values.
+      assert(MaybeDead->isCopy());
+      MaybeDead->changeDebugValuesDefReg(MaybeDead->getOperand(1).getReg());
+
       MaybeDead->eraseFromParent();
       Changed = true;
       ++NumDeletes;
diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index 092e5859a47..f30290109b7 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -2092,3 +2092,13 @@ void MachineInstr::collectDebugValues(
       DbgValues.push_back(&*DI);
   }
 }
+
+void MachineInstr::changeDebugValuesDefReg(unsigned Reg) {
+  // Collect matching debug values.
+  SmallVector<MachineInstr *, 2> DbgValues;
+  collectDebugValues(DbgValues);
+
+  // Propagate Reg to debug value instructions.
+  for (auto *DBI : DbgValues)
+    DBI->getOperand(0).setReg(Reg);
+}