1 files changed, 29 insertions, 8 deletions
diff --git a/lib/AST/ODRHash.cpp b/lib/AST/ODRHash.cpp
index a4c344ce0a..9d484bd5de 100644
--- a/lib/AST/ODRHash.cpp
+++ b/lib/AST/ODRHash.cpp
@@ -1,9 +1,8 @@
 //===-- ODRHash.cpp - Hashing to diagnose ODR failures ----------*- C++ -*-===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 ///
@@ -704,14 +703,36 @@ public:
   void VisitType(const Type *T) {}
 
   void VisitAdjustedType(const AdjustedType *T) {
-    AddQualType(T->getOriginalType());
-    AddQualType(T->getAdjustedType());
+    QualType Original = T->getOriginalType();
+    QualType Adjusted = T->getAdjustedType();
+
+    // The original type and pointee type can be the same, as in the case of
+    // function pointers decaying to themselves.  Set a bool and only process
+    // the type once, to prevent doubling the work.
+    SplitQualType split = Adjusted.split();
+    if (auto Pointer = dyn_cast<PointerType>(split.Ty)) {
+      if (Pointer->getPointeeType() == Original) {
+        Hash.AddBoolean(true);
+        ID.AddInteger(split.Quals.getAsOpaqueValue());
+        AddQualType(Original);
+        VisitType(T);
+        return;
+      }
+    }
+
+    // The original type and pointee type are different, such as in the case
+    // of a array decaying to an element pointer.  Set a bool to false and
+    // process both types.
+    Hash.AddBoolean(false);
+    AddQualType(Original);
+    AddQualType(Adjusted);
+
     VisitType(T);
   }
 
   void VisitDecayedType(const DecayedType *T) {
-    AddQualType(T->getDecayedType());
-    AddQualType(T->getPointeeType());
+    // getDecayedType and getPointeeType are derived from getAdjustedType
+    // and don't need to be separately processed.
     VisitAdjustedType(T);
   }