2 files changed, 50 insertions, 0 deletions
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index ee15a4d2b4f..629037b1755 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -26,6 +26,7 @@
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExternalASTSource.h"
+#include "clang/AST/ODRHash.h"
 #include "clang/AST/PrettyPrinter.h"
 #include "clang/AST/Redeclarable.h"
 #include "clang/AST/Stmt.h"
@@ -3604,6 +3605,25 @@ unsigned FunctionDecl::getMemoryFunctionKind() const {
   return 0;
 }
 
+unsigned FunctionDecl::getODRHash() {
+  if (HasODRHash)
+    return ODRHash;
+
+  if (FunctionDecl *Definition = getDefinition()) {
+    if (Definition != this) {
+      HasODRHash = true;
+      ODRHash = Definition->getODRHash();
+      return ODRHash;
+    }
+  }
+
+  class ODRHash Hash;
+  Hash.AddFunctionDecl(this);
+  HasODRHash = true;
+  ODRHash = Hash.CalculateHash();
+  return ODRHash;
+}
+
 //===----------------------------------------------------------------------===//
 // FieldDecl Implementation
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/AST/ODRHash.cpp b/clang/lib/AST/ODRHash.cpp
index 0f07b6225d9..b6874e7ba42 100644
--- a/clang/lib/AST/ODRHash.cpp
+++ b/clang/lib/AST/ODRHash.cpp
@@ -466,6 +466,36 @@ void ODRHash::AddCXXRecordDecl(const CXXRecordDecl *Record) {
   }
 }
 
+void ODRHash::AddFunctionDecl(const FunctionDecl *Function) {
+  assert(Function && "Expecting non-null pointer.");
+
+  // Skip hashing these kinds of function.
+  if (Function->isImplicit()) return;
+  if (Function->isDefaulted()) return;
+  if (Function->isDeleted()) return;
+  if (!Function->hasBody()) return;
+  if (!Function->getBody()) return;
+
+  // Skip functions that are specializations or in specialization context.
+  const DeclContext *DC = Function;
+  while (DC) {
+    if (isa<ClassTemplateSpecializationDecl>(DC)) return;
+    if (auto *F = dyn_cast<FunctionDecl>(DC))
+      if (F->isFunctionTemplateSpecialization()) return;
+    DC = DC->getParent();
+  }
+
+  AddDecl(Function);
+
+  AddQualType(Function->getReturnType());
+
+  ID.AddInteger(Function->param_size());
+  for (auto Param : Function->parameters())
+    AddSubDecl(Param);
+
+  AddStmt(Function->getBody());
+}
+
 void ODRHash::AddDecl(const Decl *D) {
   assert(D && "Expecting non-null pointer.");
   D = D->getCanonicalDecl();