1 files changed, 21 insertions, 8 deletions
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp b/clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp
index 19ed656..8f05014 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp
@@ -179,8 +179,23 @@ bool ConstantAggregateBuilder::add(mlir::TypedAttr typedAttr, CharUnits offset,
   }
 
   // Uncommon case: constant overlaps what we've already created.
-  cgm.errorNYI("overlapping constants");
-  return false;
+  std::optional<size_t> firstElemToReplace = splitAt(offset);
+  if (!firstElemToReplace)
+    return false;
+
+  CharUnits cSize = getSize(typedAttr);
+  std::optional<size_t> lastElemToReplace = splitAt(offset + cSize);
+  if (!lastElemToReplace)
+    return false;
+
+  assert((firstElemToReplace == lastElemToReplace || allowOverwrite) &&
+         "unexpectedly overwriting field");
+
+  Element newElt(typedAttr, offset);
+  replace(elements, *firstElemToReplace, *lastElemToReplace, {newElt});
+  size = std::max(size, offset + cSize);
+  naturalLayout = false;
+  return true;
 }
 
 bool ConstantAggregateBuilder::addBits(llvm::APInt bits, uint64_t offsetInBits,
@@ -1011,9 +1026,9 @@ public:
   }
 
   mlir::Attribute VisitCXXDefaultInitExpr(CXXDefaultInitExpr *die, QualType t) {
-    cgm.errorNYI(die->getBeginLoc(),
-                 "ConstExprEmitter::VisitCXXDefaultInitExpr");
-    return {};
+    // No need for a DefaultInitExprScope: we don't handle 'this' in a
+    // constant expression.
+    return Visit(die->getExpr(), t);
   }
 
   mlir::Attribute VisitExprWithCleanups(ExprWithCleanups *e, QualType t) {
@@ -1028,9 +1043,7 @@ public:
 
   mlir::Attribute VisitImplicitValueInitExpr(ImplicitValueInitExpr *e,
                                              QualType t) {
-    cgm.errorNYI(e->getBeginLoc(),
-                 "ConstExprEmitter::VisitImplicitValueInitExpr");
-    return {};
+    return cgm.getBuilder().getZeroInitAttr(cgm.convertType(t));
   }
 
   mlir::Attribute VisitInitListExpr(InitListExpr *ile, QualType t) {