ahatanak created this revision.
ahatanak added a reviewer: rjmccall.
ahatanak added a subscriber: cfe-commits.
When compiling a constexpr NSString initialized with an objective-c string
literal, CodeGen currently emits objc_storeStrong on an uninitialized alloca,
which causes a crash:
constexpr NSString *S = @"abc";
%S = alloca %0*, align 8
%0 = bitcast %0** %S to i8** ; this points to uninitialized memory
call void @objc_storeStrong(i8** %0, i8* bitcast
(%struct.__NSConstantString_tag* @_unnamed_cfstring_ to i8*)) #1
This patch fixes the crash by directly storing the pointer to the
__NSConstantString_tag for the string into the allocated alloca. The rationale
for this change is that retain or release on an Objective-c string literal (or
anything used to initialize a constexpr variable) has no effect and therefore
objc_storeStrong isn't needed in this case.
rdar://problem/28562009
https://reviews.llvm.org/D25547
Files:
lib/CodeGen/CGDecl.cpp
lib/CodeGen/CGExpr.cpp
lib/CodeGen/CodeGenFunction.h
test/CodeGenObjCXX/arc-constexpr.mm
Index: test/CodeGenObjCXX/arc-constexpr.mm
===================================================================
--- /dev/null
+++ test/CodeGenObjCXX/arc-constexpr.mm
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -o - -std=c++11 %s | FileCheck %s
+
+// CHECK: %[[TYPE:[a-z0-9]+]] = type opaque
+// CHECK: @[[CFSTRING:[a-z0-9_]+]] = private global %struct.__NSConstantString_tag
+
+// CHECK: define void @_Z5test1v
+// CHECK: %[[ALLOCA:[A-Z]+]] = alloca %[[TYPE]]*
+// CHECK: store %[[TYPE]]* bitcast (%struct.__NSConstantString_tag* @[[CFSTRING]] to %[[TYPE]]*), %[[TYPE]]** %[[ALLOCA]]
+// CHECK: %[[V0:[a-z0-9]+]] = bitcast %[[TYPE]]** %[[ALLOCA]] to i8**
+// CHECK: call void @objc_storeStrong(i8** %[[V0]], i8* null)
+
+@class NSString;
+
+void test1() {
+ constexpr NSString *S = @"abc";
+}
Index: lib/CodeGen/CodeGenFunction.h
===================================================================
--- lib/CodeGen/CodeGenFunction.h
+++ lib/CodeGen/CodeGenFunction.h
@@ -2709,7 +2709,8 @@
/// EmitStoreThroughLValue - Store the specified rvalue into the specified
/// lvalue, where both are guaranteed to the have the same type, and that type
/// is 'Ty'.
- void EmitStoreThroughLValue(RValue Src, LValue Dst, bool isInit = false);
+ void EmitStoreThroughLValue(RValue Src, LValue Dst, bool isInit = false,
+ bool IsConstExpr = false);
void EmitStoreThroughExtVectorComponentLValue(RValue Src, LValue Dst);
void EmitStoreThroughGlobalRegLValue(RValue Src, LValue Dst);
Index: lib/CodeGen/CGExpr.cpp
===================================================================
--- lib/CodeGen/CGExpr.cpp
+++ lib/CodeGen/CGExpr.cpp
@@ -1593,7 +1593,7 @@
/// lvalue, where both are guaranteed to the have the same type, and that type
/// is 'Ty'.
void CodeGenFunction::EmitStoreThroughLValue(RValue Src, LValue Dst,
- bool isInit) {
+ bool isInit, bool IsConstExpr) {
if (!Dst.isSimple()) {
if (Dst.isVectorElt()) {
// Read/modify/write the vector, inserting the new element.
@@ -1619,62 +1619,63 @@
}
// There's special magic for assigning into an ARC-qualified l-value.
- if (Qualifiers::ObjCLifetime Lifetime = Dst.getQuals().getObjCLifetime()) {
- switch (Lifetime) {
- case Qualifiers::OCL_None:
- llvm_unreachable("present but none");
+ if (!IsConstExpr) {
+ if (Qualifiers::ObjCLifetime Lifetime = Dst.getQuals().getObjCLifetime()) {
+ switch (Lifetime) {
+ case Qualifiers::OCL_None:
+ llvm_unreachable("present but none");
- case Qualifiers::OCL_ExplicitNone:
- // nothing special
- break;
+ case Qualifiers::OCL_ExplicitNone:
+ // nothing special
+ break;
- case Qualifiers::OCL_Strong:
- EmitARCStoreStrong(Dst, Src.getScalarVal(), /*ignore*/ true);
- return;
+ case Qualifiers::OCL_Strong:
+ EmitARCStoreStrong(Dst, Src.getScalarVal(), /*ignore*/ true);
+ return;
- case Qualifiers::OCL_Weak:
- EmitARCStoreWeak(Dst.getAddress(), Src.getScalarVal(), /*ignore*/ true);
- return;
+ case Qualifiers::OCL_Weak:
+ EmitARCStoreWeak(Dst.getAddress(), Src.getScalarVal(), /*ignore*/ true);
+ return;
- case Qualifiers::OCL_Autoreleasing:
- Src = RValue::get(EmitObjCExtendObjectLifetime(Dst.getType(),
- Src.getScalarVal()));
- // fall into the normal path
- break;
+ case Qualifiers::OCL_Autoreleasing:
+ Src = RValue::get(
+ EmitObjCExtendObjectLifetime(Dst.getType(), Src.getScalarVal()));
+ // fall into the normal path
+ break;
+ }
}
- }
- if (Dst.isObjCWeak() && !Dst.isNonGC()) {
- // load of a __weak object.
- Address LvalueDst = Dst.getAddress();
- llvm::Value *src = Src.getScalarVal();
- CGM.getObjCRuntime().EmitObjCWeakAssign(*this, src, LvalueDst);
- return;
- }
+ if (Dst.isObjCWeak() && !Dst.isNonGC()) {
+ // load of a __weak object.
+ Address LvalueDst = Dst.getAddress();
+ llvm::Value *src = Src.getScalarVal();
+ CGM.getObjCRuntime().EmitObjCWeakAssign(*this, src, LvalueDst);
+ return;
+ }
- if (Dst.isObjCStrong() && !Dst.isNonGC()) {
- // load of a __strong object.
- Address LvalueDst = Dst.getAddress();
- llvm::Value *src = Src.getScalarVal();
- if (Dst.isObjCIvar()) {
- assert(Dst.getBaseIvarExp() && "BaseIvarExp is NULL");
- llvm::Type *ResultType = IntPtrTy;
- Address dst = EmitPointerWithAlignment(Dst.getBaseIvarExp());
- llvm::Value *RHS = dst.getPointer();
- RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
- llvm::Value *LHS =
- Builder.CreatePtrToInt(LvalueDst.getPointer(), ResultType,
- "sub.ptr.lhs.cast");
- llvm::Value *BytesBetween = Builder.CreateSub(LHS, RHS, "ivar.offset");
- CGM.getObjCRuntime().EmitObjCIvarAssign(*this, src, dst,
- BytesBetween);
- } else if (Dst.isGlobalObjCRef()) {
- CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst,
- Dst.isThreadLocalRef());
+ if (Dst.isObjCStrong() && !Dst.isNonGC()) {
+ // load of a __strong object.
+ Address LvalueDst = Dst.getAddress();
+ llvm::Value *src = Src.getScalarVal();
+ if (Dst.isObjCIvar()) {
+ assert(Dst.getBaseIvarExp() && "BaseIvarExp is NULL");
+ llvm::Type *ResultType = IntPtrTy;
+ Address dst = EmitPointerWithAlignment(Dst.getBaseIvarExp());
+ llvm::Value *RHS = dst.getPointer();
+ RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
+ llvm::Value *LHS =
+ Builder.CreatePtrToInt(LvalueDst.getPointer(), ResultType,
+ "sub.ptr.lhs.cast");
+ llvm::Value *BytesBetween = Builder.CreateSub(LHS, RHS, "ivar.offset");
+ CGM.getObjCRuntime().EmitObjCIvarAssign(*this, src, dst,
+ BytesBetween);
+ } else if (Dst.isGlobalObjCRef()) {
+ CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst,
+ Dst.isThreadLocalRef());
+ } else
+ CGM.getObjCRuntime().EmitObjCStrongCastAssign(*this, src, LvalueDst);
+ return;
}
- else
- CGM.getObjCRuntime().EmitObjCStrongCastAssign(*this, src, LvalueDst);
- return;
}
assert(Src.isScalar() && "Can't emit an agg store with this method");
Index: lib/CodeGen/CGDecl.cpp
===================================================================
--- lib/CodeGen/CGDecl.cpp
+++ lib/CodeGen/CGDecl.cpp
@@ -1235,7 +1235,7 @@
// For simple scalar/complex initialization, store the value directly.
LValue lv = MakeAddrLValue(Loc, type);
lv.setNonGC(true);
- return EmitStoreThroughLValue(RValue::get(constant), lv, true);
+ return EmitStoreThroughLValue(RValue::get(constant), lv, true, true);
}
// If this is a simple aggregate initialization, we can optimize it
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