1 files changed, 7 insertions, 15 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 842ea8b4b88..481e40612c3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -268,11 +268,9 @@ Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
       // the second cast (CI). CSrc will then have a good chance of being dead.
       auto *Ty = CI.getType();
       auto *Res = CastInst::Create(NewOpc, CSrc->getOperand(0), Ty);
-      // Replace debug users of the eliminable cast by emitting debug values
-      // which refer to the new cast.
-      if (Ty->isIntegerTy() || Ty->isPointerTy())
-        // TODO: Support floats and vectors (see DW_OP_convert, fragment).
-        insertReplacementDbgValues(*CSrc, *Res, *std::next(CI.getIterator()));
+      // Point debug users of the dying cast to the new one.
+      if (CSrc->hasOneUse())
+        replaceAllDbgUsesWith(*CSrc, *Res, CI, DT);
       return Res;
     }
   }
@@ -1079,16 +1077,10 @@ Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
     Value *Res = EvaluateInDifferentType(Src, DestTy, false);
     assert(Res->getType() == DestTy);
 
-    // When DestTy is integer, try to preserve any debug values referring
-    // to the zext being replaced.
-    // TODO: This should work for vectors as well, possibly via the use
-    // of DWARF fragments.
-    if (DestTy->isIntegerTy()) {
-      insertReplacementDbgValues(
-          *Src, *Res, CI, [](DbgInfoIntrinsic &OldDII) -> DIExpression * {
-            return OldDII.getExpression();
-          });
-    }
+    // Preserve debug values referring to Src if the zext is its last use.
+    if (auto *SrcOp = dyn_cast<Instruction>(Src))
+      if (SrcOp->hasOneUse())
+        replaceAllDbgUsesWith(*SrcOp, *Res, CI, DT);
 
     uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear;
     uint32_t DestBitSize = DestTy->getScalarSizeInBits();