1 files changed, 68 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 6ffc39e2643..03fea467364 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -180,6 +180,12 @@ public:
       Thunk->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);
   }
 
+  llvm::Value *performThisAdjustment(CodeGenFunction &CGF, llvm::Value *This,
+                                     const ThisAdjustment &TA);
+
+  llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret,
+                                       const ReturnAdjustment &RA);
+
   StringRef GetPureVirtualCallName() { return "__cxa_pure_virtual"; }
   StringRef GetDeletedVirtualCallName() { return "__cxa_deleted_virtual"; }
 
@@ -1059,6 +1065,68 @@ void ItaniumCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {
   VTables.EmitVTTDefinition(VTT, CGM.getVTableLinkage(RD), RD);
 }
 
+static llvm::Value *performTypeAdjustment(CodeGenFunction &CGF,
+                                          llvm::Value *Ptr,
+                                          int64_t NonVirtualAdjustment,
+                                          int64_t VirtualAdjustment,
+                                          bool IsReturnAdjustment) {
+  if (!NonVirtualAdjustment && !VirtualAdjustment)
+    return Ptr;
+
+  llvm::Type *Int8PtrTy = CGF.Int8PtrTy;
+  llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy);
+
+  if (NonVirtualAdjustment && !IsReturnAdjustment) {
+    // Perform the non-virtual adjustment for a base-to-derived cast.
+    V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment);
+  }
+
+  if (VirtualAdjustment) {
+    llvm::Type *PtrDiffTy =
+        CGF.ConvertType(CGF.getContext().getPointerDiffType());
+
+    // Perform the virtual adjustment.
+    llvm::Value *VTablePtrPtr =
+        CGF.Builder.CreateBitCast(V, Int8PtrTy->getPointerTo());
+
+    llvm::Value *VTablePtr = CGF.Builder.CreateLoad(VTablePtrPtr);
+
+    llvm::Value *OffsetPtr =
+        CGF.Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment);
+
+    OffsetPtr = CGF.Builder.CreateBitCast(OffsetPtr, PtrDiffTy->getPointerTo());
+
+    // Load the adjustment offset from the vtable.
+    llvm::Value *Offset = CGF.Builder.CreateLoad(OffsetPtr);
+
+    // Adjust our pointer.
+    V = CGF.Builder.CreateInBoundsGEP(V, Offset);
+  }
+
+  if (NonVirtualAdjustment && IsReturnAdjustment) {
+    // Perform the non-virtual adjustment for a derived-to-base cast.
+    V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment);
+  }
+
+  // Cast back to the original type.
+  return CGF.Builder.CreateBitCast(V, Ptr->getType());
+}
+
+llvm::Value *ItaniumCXXABI::performThisAdjustment(CodeGenFunction &CGF,
+                                                  llvm::Value *This,
+                                                  const ThisAdjustment &TA) {
+  return performTypeAdjustment(CGF, This, TA.NonVirtual, TA.VCallOffsetOffset,
+                               /*IsReturnAdjustment=*/false);
+}
+
+llvm::Value *
+ItaniumCXXABI::performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret,
+                                       const ReturnAdjustment &RA) {
+  return performTypeAdjustment(CGF, Ret, RA.NonVirtual,
+                               RA.Virtual.Itanium.VBaseOffsetOffset,
+                               /*IsReturnAdjustment=*/true);
+}
+
 void ARMCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
                                     RValue RV, QualType ResultType) {
   if (!isa<CXXDestructorDecl>(CGF.CurGD.getDecl()))