1 files changed, 15 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index d9f0ae38e3a..392e8bc0db4 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2362,6 +2362,8 @@ class TypePromotionTransaction {
 
     /// Keep track of the original uses (pair Instruction, Index).
     SmallVector<InstructionAndIdx, 4> OriginalUses;
+    /// Keep track of the debug users.
+    SmallVector<DbgValueInst *, 1> DbgValues;
 
     using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
 
@@ -2375,6 +2377,10 @@ class TypePromotionTransaction {
         Instruction *UserI = cast<Instruction>(U.getUser());
         OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
       }
+      // Record the debug uses separately. They are not in the instruction's
+      // use list, but they are replaced by RAUW.
+      findDbgValues(DbgValues, Inst);
+
       // Now, we can replace the uses.
       Inst->replaceAllUsesWith(New);
     }
@@ -2387,6 +2393,15 @@ class TypePromotionTransaction {
            UseIt != EndIt; ++UseIt) {
         UseIt->Inst->setOperand(UseIt->Idx, Inst);
       }
+      // RAUW has replaced all original uses with references to the new value,
+      // including the debug uses. Since we are undoing the replacements,
+      // the original debug uses must also be reinstated to maintain the
+      // correctness and utility of debug value instructions.
+      for (auto *DVI: DbgValues) {
+        LLVMContext &Ctx = Inst->getType()->getContext();
+        auto *MV = MetadataAsValue::get(Ctx, ValueAsMetadata::get(Inst));
+        DVI->setOperand(0, MV);
+      }
     }
   };