Revert r231508 "CodeGen: Emit constant temporaries into read-only globals."

This broke the Chromium build. Links were failing with messages like:

obj/dbus/libdbus_test_support.a(obj/dbus/dbus_test_support.mock_object_proxy.o):../../dbus/mock_object_proxy.cc:function dbus::MockObjectProxy::Detach(): warning: relocation refers to discarded section
/usr/local/google/work/chromium/src/third_party/binutils/Linux_x64/Release/bin/ld.gold: error: treating warnings as errors

llvm-svn: 231541

clang/lib/CodeGen/CGExpr.cpp

@@ -301,25 +301,6 @@ createReferenceTemporary(CodeGenFunction &CGF,
   switch (M->getStorageDuration()) {
   case SD_FullExpression:
   case SD_Automatic:
-    // If we have a constant temporary array or record try to promote it into a
-    // constant global under the same rules a normal constant would've been
-    // promoted. This is easier on the optimizer and generally emits fewer
-    // instructions.
-    if (CGF.CGM.getCodeGenOpts().MergeAllConstants &&
-        (M->getType()->isArrayType() || M->getType()->isRecordType()) &&
-        CGF.CGM.isTypeConstant(M->getType(), true))
-      if (llvm::Constant *Init =
-              CGF.CGM.EmitConstantExpr(Inner, M->getType(), &CGF)) {
-        auto *GV = new llvm::GlobalVariable(
-            CGF.CGM.getModule(), Init->getType(), /*isConstant=*/true,
-            llvm::GlobalValue::PrivateLinkage, Init, ".ref.tmp");
-        GV->setAlignment(
-            CGF.getContext().getTypeAlignInChars(M->getType()).getQuantity());
-        // Put the new global in the same COMDAT the function containing the
-        // temporary is in.
-        GV->setComdat(CGF.CurFn->getComdat());
-        return GV;
-      }
     return CGF.CreateMemTemp(Inner->getType(), "ref.tmp");
 
   case SD_Thread:
@@ -389,9 +370,8 @@ EmitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *M) {
   // Create and initialize the reference temporary.
   llvm::Value *Object = createReferenceTemporary(*this, M, E);
   if (auto *Var = dyn_cast<llvm::GlobalVariable>(Object)) {
-    // If the temporary is a global and has a constant initializer or is a
-    // constant temporary that we promoted to a global, we may have already
-    // initialized it.
+    // If the temporary is a global and has a constant initializer, we may
+    // have already initialized it.
     if (!Var->hasInitializer()) {
       Var->setInitializer(CGM.EmitNullConstant(E->getType()));
       EmitAnyExprToMem(E, Object, Qualifiers(), /*IsInit*/true);

clang/test/CodeGenCXX/compound-literals.cpp

@@ -28,7 +28,7 @@ int f() {
 
 // CHECK-LABEL: define i32 @_Z1gv()
 int g() {
-  // CHECK: store [2 x i32]* @{{.*}}, [2 x i32]** [[V:%[a-z0-9.]+]]
+  // CHECK: store [2 x i32]* %{{[a-z0-9.]+}}, [2 x i32]** [[V:%[a-z0-9.]+]]
   const int (&v)[2] = (int [2]) {1,2};
 
   // CHECK: [[A:%[a-z0-9.]+]] = load [2 x i32]*, [2 x i32]** [[V]]

clang/test/CodeGenCXX/cxx0x-initializer-array.cpp

@@ -42,11 +42,10 @@ namespace ValueInitArrayOfMemPtr {
     // CHECK: call void @llvm.memcpy.p0i8.p0i8.i32(i8* %{{.*}}, i8* bitcast ([3 x i32]* @[[THREE_NULL_MEMPTRS]] to i8*), i32 12, i32 4, i1 false)
   }
 
-  // Test dynamic initialization.
-  // CHECK-LABEL: define void @_ZN22ValueInitArrayOfMemPtr1gEMNS_1SEi
-  void g(p ptr) {
+  // CHECK-LABEL: define void @_ZN22ValueInitArrayOfMemPtr1gEv
+  void g() {
     // CHECK: store i32 -1,
-    f(a{ptr});
+    f(a{});
   }
 }
 

clang/test/CodeGenCXX/cxx0x-initializer-references.cpp

@@ -35,30 +35,22 @@ namespace reference {
     // CHECK-NEXT: ret
   }
 
-  void reference_to_aggregate(int i) {
+  void reference_to_aggregate() {
     // CHECK: getelementptr {{.*}}, i32 0, i32 0
     // CHECK-NEXT: store i32 1
     // CHECK-NEXT: getelementptr {{.*}}, i32 0, i32 1
-    // CHECK-NEXT: %[[I1:.*]] = load i32, i32*
-    // CHECK-NEXT: store i32 %[[I1]]
+    // CHECK-NEXT: store i32 2
     // CHECK-NEXT: store %{{.*}}* %{{.*}}, %{{.*}}** %{{.*}}, align
-    const A &ra1{1, i};
+    const A &ra1{1, 2};
 
     // CHECK-NEXT: getelementptr inbounds [3 x i32], [3 x i32]* %{{.*}}, i{{32|64}} 0, i{{32|64}} 0
     // CHECK-NEXT: store i32 1
     // CHECK-NEXT: getelementptr inbounds i32, i32* %{{.*}}, i{{32|64}} 1
     // CHECK-NEXT: store i32 2
     // CHECK-NEXT: getelementptr inbounds i32, i32* %{{.*}}, i{{32|64}} 1
-    // CHECK-NEXT: %[[I2:.*]] = load i32, i32*
-    // CHECK-NEXT: store i32 %[[I2]]
+    // CHECK-NEXT: store i32 3
     // CHECK-NEXT: store [3 x i32]* %{{.*}}, [3 x i32]** %{{.*}}, align
-    const int (&arrayRef)[] = {1, 2, i};
-
-    // CHECK: store %{{.*}}* @{{.*}}, %{{.*}}** %{{.*}}, align
-    const A &constra1{1, 2};
-
-    // CHECK-NEXT: store [3 x i32]* @{{.*}}, [3 x i32]** %{{.*}}, align
-    const int (&constarrayRef)[] = {1, 2, 3};
+    const int (&arrayRef)[] = {1, 2, 3};
 
     // CHECK-NEXT: ret
   }

clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp

@@ -72,9 +72,6 @@ namespace thread_local_global_array {
 // CHECK: @[[PARTLY_CONSTANT_SECOND:_ZGRN15partly_constant2ilE.*]] = internal global [2 x i32] zeroinitializer, align 4
 // CHECK: @[[PARTLY_CONSTANT_THIRD:_ZGRN15partly_constant2ilE.*]] = internal constant [4 x i32] [i32 5, i32 6, i32 7, i32 8], align 4
 
-// CHECK: @[[REFTMP1:.*]] = private constant [2 x i32] [i32 42, i32 43], comdat($_ZN7PR204451fILi0EEEvv), align 4
-// CHECK: @[[REFTMP2:.*]] = private constant [3 x %{{.*}}] [%{{.*}} { i32 1 }, %{{.*}} { i32 2 }, %{{.*}} { i32 3 }], align 4
-
 // CHECK: appending global
 
 
@@ -218,16 +215,17 @@ void fn9() {
 
 struct haslist1 {
   std::initializer_list<int> il;
-  haslist1(int i);
+  haslist1();
 };
 
-// CHECK-LABEL: define void @_ZN8haslist1C2Ei
-haslist1::haslist1(int i)
+// CHECK-LABEL: define void @_ZN8haslist1C2Ev
+haslist1::haslist1()
 // CHECK: alloca [3 x i32]
-// CHECK: store i32 %
+// CHECK: store i32 1
 // CHECK: store i32 2
 // CHECK: store i32 3
-  : il{i, 2, 3}
+// CHECK: store i{{32|64}} 3
+  : il{1, 2, 3}
 {
   destroyme2 dm2;
 }
@@ -246,15 +244,16 @@ haslist2::haslist2()
   // CHECK: call void @_ZN10destroyme1D1Ev
 }
 
-void fn10(int i) {
-  // CHECK-LABEL: define void @_Z4fn10i
+void fn10() {
+  // CHECK-LABEL: define void @_Z4fn10v
   // CHECK: alloca [3 x i32]
   // CHECK: call noalias i8* @_Znw{{[jm]}}
-  // CHECK: store i32 %
+  // CHECK: store i32 1
   // CHECK: store i32 2
   // CHECK: store i32 3
   // CHECK: store i32*
-  (void) new std::initializer_list<int> {i, 2, 3};
+  // CHECK: store i{{32|64}} 3
+  (void) new std::initializer_list<int> {1, 2, 3};
 }
 
 void fn11() {
@@ -463,22 +462,6 @@ namespace PR20445 {
   template<int x> void f() { new MyClass({42, 43}); }
   template void f<0>();
   // CHECK-LABEL: define {{.*}} @_ZN7PR204451fILi0EEEvv(
-  // CHECK: store i32* getelementptr inbounds ([2 x i32]* @[[REFTMP1]], i64 0, i64 0)
   // CHECK: call void @_ZN7PR204456vectorC1ESt16initializer_listIiE(
   // CHECK: call void @_ZN7PR204457MyClassC1ERKNS_6vectorE(
 }
-
-namespace ConstExpr {
-  class C {
-    int x;
-  public:
-    constexpr C(int x) : x(x) {}
-  };
-  void f(std::initializer_list<C>);
-  void g() {
-// CHECK-LABEL: _ZN9ConstExpr1gEv
-// CHECK: store %"class.ConstExpr::C"* getelementptr inbounds ([3 x %"class.ConstExpr::C"]* @[[REFTMP2]], i64 0, i64 0)
-// CHECK: call void @_ZN9ConstExpr1fESt16initializer_listINS_1CEE
-    f({C(1), C(2), C(3)});
-  }
-}