vsapsai created this revision.
vsapsai added reviewers: ahatanak, rjmccall.
Herald added a subscriber: dexonsmith.
Failed assertion is
> Assertion failed: ((ND->isUsed(false) || !isa<VarDecl>(ND) ||
> !E->getLocation().isValid()) && "Should not use decl without marking it
> used!"), function EmitDeclRefLValue, file
> llvm-project/clang/lib/CodeGen/CGExpr.cpp, line 2437.
`EmitDeclRefLValue` mentions
> // A DeclRefExpr for a reference initialized by a constant expression can
> // appear without being odr-used. Directly emit the constant initializer.
The fix is in using the similar approach for non-references of
non-odr-used variables. `EmitScalarExpr` will try to emit constant if
possible and we can use resulting `llvm::Value *` without performing
`EmitLValue`.
rdar://problem/40650504
https://reviews.llvm.org/D53674
Files:
clang/lib/CodeGen/CGObjC.cpp
clang/test/CodeGenObjCXX/arc-constexpr.mm
Index: clang/test/CodeGenObjCXX/arc-constexpr.mm
===================================================================
--- clang/test/CodeGenObjCXX/arc-constexpr.mm
+++ clang/test/CodeGenObjCXX/arc-constexpr.mm
@@ -1,18 +1,50 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -o - -std=c++11 %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -fobjc-runtime-has-weak -o - -std=c++11 %s | FileCheck %s
// CHECK: %[[TYPE:[a-z0-9]+]] = type opaque
// CHECK: @[[CFSTRING:[a-z0-9_]+]] = private global %struct.__NSConstantString_tag
+@class NSString;
-// CHECK: define void @_Z5test1v
+// CHECK-LABEL: define void @_Z5test1v
// CHECK: %[[ALLOCA:[A-Z]+]] = alloca %[[TYPE]]*
// CHECK: %[[V0:[0-9]+]] = call i8* @objc_retain(i8* bitcast (%struct.__NSConstantString_tag* @[[CFSTRING]]
// CHECK: %[[V1:[0-9]+]] = bitcast i8* %[[V0]] to %[[TYPE]]*
// CHECK: store %[[TYPE]]* %[[V1]], %[[TYPE]]** %[[ALLOCA]]
// CHECK: %[[V2:[0-9]+]] = bitcast %[[TYPE]]** %[[ALLOCA]]
// CHECK: call void @objc_storeStrong(i8** %[[V2]], i8* null)
-
-@class NSString;
-
void test1() {
constexpr NSString *S = @"abc";
}
+
+// CHECK-LABEL: define void @_Z5test2v
+// CHECK: %[[CONST:[a-zA-Z]+]] = alloca %[[TYPE]]*
+// CHECK: %[[REF_CONST:[a-zA-Z]+]] = alloca %[[TYPE]]*
+// CHECK: %[[V0:[0-9]+]] = call i8* @objc_retain(i8* bitcast (%struct.__NSConstantString_tag* @[[CFSTRING]]
+// CHECK-NEXT: %[[V1:[0-9]+]] = bitcast i8* %[[V0]] to %[[TYPE]]*
+// CHECK-NEXT: store %[[TYPE]]* %[[V1]], %[[TYPE]]** %[[CONST]]
+// CHECK: %[[V2:[0-9]+]] = call i8* @objc_retain(i8* bitcast (%struct.__NSConstantString_tag* @[[CFSTRING]]
+// CHECK-NEXT: %[[V3:[0-9]+]] = bitcast i8* %[[V2]] to %[[TYPE]]*
+// CHECK-NEXT: store %[[TYPE]]* %[[V3]], %[[TYPE]]** %[[REF_CONST]]
+// CHECK: %[[V4:[0-9]+]] = bitcast %[[TYPE]]** %[[REF_CONST]]
+// CHECK-NEXT: call void @objc_storeStrong(i8** %[[V4]], i8* null)
+// CHECK: %[[V5:[0-9]+]] = bitcast %[[TYPE]]** %[[CONST]]
+// CHECK-NEXT: call void @objc_storeStrong(i8** %[[V5]], i8* null)
+void test2() {
+ constexpr NSString *Const = @"abc";
+ // Initialize RefConst with Const initializer instead of reading from variable.
+ NSString* RefConst = Const;
+}
+
+// CHECK-LABEL: define void @_Z5test3v
+// CHECK: %[[WEAK_CONST:[a-zA-Z]+]] = alloca %[[TYPE]]*
+// CHECK: %[[REF_WEAK_CONST:[a-zA-Z]+]] = alloca %[[TYPE]]*
+// CHECK: %[[V0:[0-9]+]] = bitcast %[[TYPE]]** %[[WEAK_CONST]]
+// CHECK-NEXT: %[[V1:[0-9]+]] = call i8* @objc_initWeak(i8** %[[V0]], i8* bitcast (%struct.__NSConstantString_tag* @[[CFSTRING]]
+// CHECK: store %[[TYPE]]* bitcast (%struct.__NSConstantString_tag* @[[CFSTRING]] to %[[TYPE]]*), %[[TYPE]]** %[[REF_WEAK_CONST]]
+// CHECK: %[[V2:[0-9]+]] = bitcast %[[TYPE]]** %[[REF_WEAK_CONST]]
+// CHECK-NEXT: call void @objc_storeStrong(i8** %[[V2]], i8* null)
+// CHECK: %[[V3:[0-9]+]] = bitcast %[[TYPE]]** %[[WEAK_CONST]]
+// CHECK-NEXT: call void @objc_destroyWeak(i8** %[[V3]])
+void test3() {
+ __weak constexpr NSString *WeakConst = @"abc";
+ NSString* RefWeakConst = WeakConst;
+}
Index: clang/lib/CodeGen/CGObjC.cpp
===================================================================
--- clang/lib/CodeGen/CGObjC.cpp
+++ clang/lib/CodeGen/CGObjC.cpp
@@ -2446,21 +2446,37 @@
EHStack.pushCleanup<CallObjCMRRAutoreleasePoolObject>(NormalCleanup, Ptr);
}
+static bool shouldRetainObjCLifetime(Qualifiers::ObjCLifetime Lifetime) {
+ switch (Lifetime) {
+ case Qualifiers::OCL_None:
+ case Qualifiers::OCL_ExplicitNone:
+ case Qualifiers::OCL_Strong:
+ case Qualifiers::OCL_Autoreleasing:
+ return true;
+
+ case Qualifiers::OCL_Weak:
+ return false;
+ }
+
+ llvm_unreachable("impossible lifetime!");
+}
+
static TryEmitResult tryEmitARCRetainLoadOfScalar(CodeGenFunction &CGF,
LValue lvalue,
QualType type) {
+ bool SuppressResultRetain = !shouldRetainObjCLifetime(type.getObjCLifetime());
switch (type.getObjCLifetime()) {
case Qualifiers::OCL_None:
case Qualifiers::OCL_ExplicitNone:
case Qualifiers::OCL_Strong:
case Qualifiers::OCL_Autoreleasing:
- return TryEmitResult(CGF.EmitLoadOfLValue(lvalue,
- SourceLocation()).getScalarVal(),
- false);
+ return TryEmitResult(
+ CGF.EmitLoadOfLValue(lvalue, SourceLocation()).getScalarVal(),
+ SuppressResultRetain);
case Qualifiers::OCL_Weak:
return TryEmitResult(CGF.EmitARCLoadWeakRetained(lvalue.getAddress()),
- true);
+ SuppressResultRetain);
}
llvm_unreachable("impossible lifetime!");
@@ -2500,6 +2516,17 @@
cast<BinaryOperator>(e)->getOpcode() == BO_Assign)
return TryEmitResult(CGF.EmitScalarExpr(e), false);
+ // DeclRefExpr referencing non-odr-used variable might be constant-evaluated
+ // and in this case we don't have l-value. Emit code for scalar expression
+ // instead of emitting LValue and loading it.
+ if (const auto *DRE = dyn_cast<DeclRefExpr>(e)) {
+ const ValueDecl *Decl = DRE->getDecl();
+ if (isa<VarDecl>(Decl) && !Decl->isUsed(false) &&
+ !Decl->getType()->isReferenceType())
+ return TryEmitResult(CGF.EmitScalarExpr(e),
+ !shouldRetainObjCLifetime(type.getObjCLifetime()));
+ }
+
return tryEmitARCRetainLoadOfScalar(CGF, CGF.EmitLValue(e), type);
}
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