--- a/unittests/IR/ConstantsTest.cpp	Thu Dec 12 15:22:36 2013 +0900
+++ b/unittests/IR/ConstantsTest.cpp	Mon Sep 08 22:06:00 2014 +0900
@@ -162,7 +162,7 @@
   }
 
 TEST(ConstantsTest, AsInstructionsTest) {
-  OwningPtr<Module> M(new Module("MyModule", getGlobalContext()));
+  std::unique_ptr<Module> M(new Module("MyModule", getGlobalContext()));
 
   Type *Int64Ty = Type::getInt64Ty(getGlobalContext());
   Type *Int32Ty = Type::getInt32Ty(getGlobalContext());
@@ -254,7 +254,98 @@
         P6STR ", i32 1");
 }
 
+#ifdef GTEST_HAS_DEATH_TEST
+#ifndef NDEBUG
+TEST(ConstantsTest, ReplaceWithConstantTest) {
+  std::unique_ptr<Module> M(new Module("MyModule", getGlobalContext()));
+
+  Type *Int32Ty = Type::getInt32Ty(getGlobalContext());
+  Constant *One = ConstantInt::get(Int32Ty, 1);
+
+  Constant *Global =
+      M->getOrInsertGlobal("dummy", PointerType::getUnqual(Int32Ty));
+  Constant *GEP = ConstantExpr::getGetElementPtr(Global, One);
+  EXPECT_DEATH(Global->replaceAllUsesWith(GEP),
+               "this->replaceAllUsesWith\\(expr\\(this\\)\\) is NOT valid!");
+}
+
+#endif
+#endif
+
 #undef CHECK
 
+TEST(ConstantsTest, ConstantArrayReplaceWithConstant) {
+  LLVMContext Context;
+  std::unique_ptr<Module> M(new Module("MyModule", Context));
+
+  Type *IntTy = Type::getInt8Ty(Context);
+  ArrayType *ArrayTy = ArrayType::get(IntTy, 2);
+  Constant *A01Vals[2] = {ConstantInt::get(IntTy, 0),
+                          ConstantInt::get(IntTy, 1)};
+  Constant *A01 = ConstantArray::get(ArrayTy, A01Vals);
+
+  Constant *Global = new GlobalVariable(*M, IntTy, false,
+                                        GlobalValue::ExternalLinkage, nullptr);
+  Constant *GlobalInt = ConstantExpr::getPtrToInt(Global, IntTy);
+  Constant *A0GVals[2] = {ConstantInt::get(IntTy, 0), GlobalInt};
+  Constant *A0G = ConstantArray::get(ArrayTy, A0GVals);
+  ASSERT_NE(A01, A0G);
+
+  GlobalVariable *RefArray =
+      new GlobalVariable(*M, ArrayTy, false, GlobalValue::ExternalLinkage, A0G);
+  ASSERT_EQ(A0G, RefArray->getInitializer());
+
+  GlobalInt->replaceAllUsesWith(ConstantInt::get(IntTy, 1));
+  ASSERT_EQ(A01, RefArray->getInitializer());
+}
+
+TEST(ConstantsTest, ConstantExprReplaceWithConstant) {
+  LLVMContext Context;
+  std::unique_ptr<Module> M(new Module("MyModule", Context));
+
+  Type *IntTy = Type::getInt8Ty(Context);
+  Constant *G1 = new GlobalVariable(*M, IntTy, false,
+                                    GlobalValue::ExternalLinkage, nullptr);
+  Constant *G2 = new GlobalVariable(*M, IntTy, false,
+                                    GlobalValue::ExternalLinkage, nullptr);
+  ASSERT_NE(G1, G2);
+
+  Constant *Int1 = ConstantExpr::getPtrToInt(G1, IntTy);
+  Constant *Int2 = ConstantExpr::getPtrToInt(G2, IntTy);
+  ASSERT_NE(Int1, Int2);
+
+  GlobalVariable *Ref =
+      new GlobalVariable(*M, IntTy, false, GlobalValue::ExternalLinkage, Int1);
+  ASSERT_EQ(Int1, Ref->getInitializer());
+
+  G1->replaceAllUsesWith(G2);
+  ASSERT_EQ(Int2, Ref->getInitializer());
+}
+
+TEST(ConstantsTest, GEPReplaceWithConstant) {
+  LLVMContext Context;
+  std::unique_ptr<Module> M(new Module("MyModule", Context));
+
+  Type *IntTy = Type::getInt32Ty(Context);
+  Type *PtrTy = PointerType::get(IntTy, 0);
+  auto *C1 = ConstantInt::get(IntTy, 1);
+  auto *Placeholder = new GlobalVariable(
+      *M, IntTy, false, GlobalValue::ExternalWeakLinkage, nullptr);
+  auto *GEP = ConstantExpr::getGetElementPtr(Placeholder, C1);
+  ASSERT_EQ(GEP->getOperand(0), Placeholder);
+
+  auto *Ref =
+      new GlobalVariable(*M, PtrTy, false, GlobalValue::ExternalLinkage, GEP);
+  ASSERT_EQ(GEP, Ref->getInitializer());
+
+  auto *Global = new GlobalVariable(*M, PtrTy, false,
+                                    GlobalValue::ExternalLinkage, nullptr);
+  auto *Alias = GlobalAlias::create(IntTy, 0, GlobalValue::ExternalLinkage,
+                                    "alias", Global, M.get());
+  Placeholder->replaceAllUsesWith(Alias);
+  ASSERT_EQ(GEP, Ref->getInitializer());
+  ASSERT_EQ(GEP->getOperand(0), Alias);
+}
+
 }  // end anonymous namespace
 }  // end namespace llvm