Define weak and __weak to mean ARC-style weak references, even in MRC.
Previously, __weak was silently accepted and ignored in MRC mode.
That makes this a potentially source-breaking change that we have to
roll out cautiously. Accordingly, for the time being, actual support
for __weak references in MRC is experimental, and the compiler will
reject attempts to actually form such references. The intent is to
eventually enable the feature by default in all non-GC modes.
(It is, of course, incompatible with ObjC GC's interpretation of
__weak.)
If you like, you can enable this feature with
-Xclang -fobjc-weak
but like any -Xclang option, this option may be removed at any point,
e.g. if/when it is eventually enabled by default.
This patch also enables the use of the ARC __unsafe_unretained qualifier
in MRC. Unlike __weak, this is being enabled immediately. Since
variables are essentially __unsafe_unretained by default in MRC,
the only practical uses are (1) communication and (2) changing the
default behavior of by-value block capture.
As an implementation matter, this means that the ObjC ownership
qualifiers may appear in any ObjC language mode, and so this patch
removes a number of checks for getLangOpts().ObjCAutoRefCount
that were guarding the processing of these qualifiers. I don't
expect this to be a significant drain on performance; it may even
be faster to just check for these qualifiers directly on a type
(since it's probably in a register anyway) than to do N dependent
loads to grab the LangOptions.
rdar://9674298
llvm-svn: 251041
diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp
index a44cdf8..44c9a90 100644
--- a/clang/lib/CodeGen/CGObjCMac.cpp
+++ b/clang/lib/CodeGen/CGObjCMac.cpp
@@ -913,10 +913,28 @@
/// BuildIvarLayout - Builds ivar layout bitmap for the class
/// implementation for the __strong or __weak case.
///
+ /// \param hasMRCWeakIvars - Whether we are compiling in MRC and there
+ /// are any weak ivars defined directly in the class. Meaningless unless
+ /// building a weak layout. Does not guarantee that the layout will
+ /// actually have any entries, because the ivar might be under-aligned.
llvm::Constant *BuildIvarLayout(const ObjCImplementationDecl *OI,
CharUnits beginOffset,
CharUnits endOffset,
- bool ForStrongLayout);
+ bool forStrongLayout,
+ bool hasMRCWeakIvars);
+
+ llvm::Constant *BuildStrongIvarLayout(const ObjCImplementationDecl *OI,
+ CharUnits beginOffset,
+ CharUnits endOffset) {
+ return BuildIvarLayout(OI, beginOffset, endOffset, true, false);
+ }
+
+ llvm::Constant *BuildWeakIvarLayout(const ObjCImplementationDecl *OI,
+ CharUnits beginOffset,
+ CharUnits endOffset,
+ bool hasMRCWeakIvars) {
+ return BuildIvarLayout(OI, beginOffset, endOffset, false, hasMRCWeakIvars);
+ }
Qualifiers::ObjCLifetime getBlockCaptureLifetime(QualType QT, bool ByrefLayout);
@@ -1060,7 +1078,8 @@
/// to store the weak ivar layout and properties. The return value
/// has type ClassExtensionPtrTy.
llvm::Constant *EmitClassExtension(const ObjCImplementationDecl *ID,
- CharUnits InstanceSize);
+ CharUnits instanceSize,
+ bool hasMRCWeakIvars);
/// EmitClassRef - Return a Value*, of type ObjCTypes.ClassPtrTy,
/// for the given class.
@@ -2049,8 +2068,7 @@
const CGBlockInfo &blockInfo) {
llvm::Constant *nullPtr = llvm::Constant::getNullValue(CGM.Int8PtrTy);
- if (CGM.getLangOpts().getGC() == LangOptions::NonGC &&
- !CGM.getLangOpts().ObjCAutoRefCount)
+ if (CGM.getLangOpts().getGC() == LangOptions::NonGC)
return nullPtr;
IvarLayoutBuilder builder(CGM, CharUnits::Zero(), blockInfo.BlockSize,
@@ -2129,10 +2147,15 @@
/// the type of the variable captured in the block.
Qualifiers::ObjCLifetime CGObjCCommonMac::getBlockCaptureLifetime(QualType FQT,
bool ByrefLayout) {
+ // If it has an ownership qualifier, we're done.
+ if (auto lifetime = FQT.getObjCLifetime())
+ return lifetime;
+
+ // If it doesn't, and this is ARC, it has no ownership.
if (CGM.getLangOpts().ObjCAutoRefCount)
- return FQT.getObjCLifetime();
+ return Qualifiers::OCL_None;
- // MRR.
+ // In MRC, retainable pointers are owned by non-__block variables.
if (FQT->isObjCObjectPointerType() || FQT->isBlockPointerType())
return ByrefLayout ? Qualifiers::OCL_ExplicitNone : Qualifiers::OCL_Strong;
@@ -3060,11 +3083,24 @@
}
enum FragileClassFlags {
+ /// Apparently: is not a meta-class.
FragileABI_Class_Factory = 0x00001,
+
+ /// Is a meta-class.
FragileABI_Class_Meta = 0x00002,
+
+ /// Has a non-trivial constructor or destructor.
FragileABI_Class_HasCXXStructors = 0x02000,
+
+ /// Has hidden visibility.
FragileABI_Class_Hidden = 0x20000,
- FragileABI_Class_CompiledByARC = 0x04000000
+
+ /// Class implementation was compiled under ARC.
+ FragileABI_Class_CompiledByARC = 0x04000000,
+
+ /// Class implementation was compiled under MRC and has MRC weak ivars.
+ /// Exclusive with CompiledByARC.
+ FragileABI_Class_HasMRCWeakIvars = 0x08000000,
};
enum NonFragileClassFlags {
@@ -3074,7 +3110,7 @@
/// Is a root class.
NonFragileABI_Class_Root = 0x00002,
- /// Has a C++ constructor and destructor.
+ /// Has a non-trivial constructor or destructor.
NonFragileABI_Class_HasCXXStructors = 0x00004,
/// Has hidden visibility.
@@ -3090,9 +3126,46 @@
NonFragileABI_Class_CompiledByARC = 0x00080,
/// Class has non-trivial destructors, but zero-initialization is okay.
- NonFragileABI_Class_HasCXXDestructorOnly = 0x00100
+ NonFragileABI_Class_HasCXXDestructorOnly = 0x00100,
+
+ /// Class implementation was compiled under MRC and has MRC weak ivars.
+ /// Exclusive with CompiledByARC.
+ NonFragileABI_Class_HasMRCWeakIvars = 0x00200,
};
+static bool hasWeakMember(QualType type) {
+ if (type.getObjCLifetime() == Qualifiers::OCL_Weak) {
+ return true;
+ }
+
+ if (auto recType = type->getAs<RecordType>()) {
+ for (auto field : recType->getDecl()->fields()) {
+ if (hasWeakMember(field->getType()))
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/// For compatibility, we only want to set the "HasMRCWeakIvars" flag
+/// (and actually fill in a layout string) if we really do have any
+/// __weak ivars.
+static bool hasMRCWeakIvars(CodeGenModule &CGM,
+ const ObjCImplementationDecl *ID) {
+ if (!CGM.getLangOpts().ObjCWeak) return false;
+ assert(CGM.getLangOpts().getGC() == LangOptions::NonGC);
+
+ for (const ObjCIvarDecl *ivar =
+ ID->getClassInterface()->all_declared_ivar_begin();
+ ivar; ivar = ivar->getNextIvar()) {
+ if (hasWeakMember(ivar->getType()))
+ return true;
+ }
+
+ return false;
+}
+
/*
struct _objc_class {
Class isa;
@@ -3127,8 +3200,12 @@
if (ID->hasNonZeroConstructors() || ID->hasDestructors())
Flags |= FragileABI_Class_HasCXXStructors;
+ bool hasMRCWeak = false;
+
if (CGM.getLangOpts().ObjCAutoRefCount)
Flags |= FragileABI_Class_CompiledByARC;
+ else if ((hasMRCWeak = hasMRCWeakIvars(CGM, ID)))
+ Flags |= FragileABI_Class_HasMRCWeakIvars;
CharUnits Size =
CGM.getContext().getASTObjCImplementationLayout(ID).getSize();
@@ -3183,8 +3260,8 @@
// cache is always NULL.
Values[ 8] = llvm::Constant::getNullValue(ObjCTypes.CachePtrTy);
Values[ 9] = Protocols;
- Values[10] = BuildIvarLayout(ID, CharUnits::Zero(), Size, true);
- Values[11] = EmitClassExtension(ID, Size);
+ Values[10] = BuildStrongIvarLayout(ID, CharUnits::Zero(), Size);
+ Values[11] = EmitClassExtension(ID, Size, hasMRCWeak);
llvm::Constant *Init = llvm::ConstantStruct::get(ObjCTypes.ClassTy,
Values);
std::string Name("OBJC_CLASS_");
@@ -3323,13 +3400,14 @@
*/
llvm::Constant *
CGObjCMac::EmitClassExtension(const ObjCImplementationDecl *ID,
- CharUnits InstanceSize) {
+ CharUnits InstanceSize, bool hasMRCWeakIvars) {
uint64_t Size =
CGM.getDataLayout().getTypeAllocSize(ObjCTypes.ClassExtensionTy);
llvm::Constant *Values[3];
Values[0] = llvm::ConstantInt::get(ObjCTypes.IntTy, Size);
- Values[1] = BuildIvarLayout(ID, CharUnits::Zero(), InstanceSize, false);
+ Values[1] = BuildWeakIvarLayout(ID, CharUnits::Zero(), InstanceSize,
+ hasMRCWeakIvars);
Values[2] = EmitPropertyList("\01l_OBJC_$_PROP_LIST_" + ID->getName(),
ID, ID->getClassInterface(), ObjCTypes);
@@ -4827,10 +4905,13 @@
llvm::Constant *
CGObjCCommonMac::BuildIvarLayout(const ObjCImplementationDecl *OMD,
CharUnits beginOffset, CharUnits endOffset,
- bool ForStrongLayout) {
+ bool ForStrongLayout, bool HasMRCWeakIvars) {
+ // If this is MRC, and we're either building a strong layout or there
+ // are no weak ivars, bail out early.
llvm::Type *PtrTy = CGM.Int8PtrTy;
if (CGM.getLangOpts().getGC() == LangOptions::NonGC &&
- !CGM.getLangOpts().ObjCAutoRefCount)
+ !CGM.getLangOpts().ObjCAutoRefCount &&
+ (ForStrongLayout || !HasMRCWeakIvars))
return llvm::Constant::getNullValue(PtrTy);
const ObjCInterfaceDecl *OI = OMD->getClassInterface();
@@ -4844,8 +4925,10 @@
// runtimes, that means starting at InstanceStart. In fragile runtimes,
// there's no InstanceStart, so it means starting at the end of the
// superclass, rounded up to word alignment.
+ //
+ // MRC weak layout strings follow the ARC style.
CharUnits baseOffset;
- if (CGM.getLangOpts().ObjCAutoRefCount) {
+ if (CGM.getLangOpts().getGC() == LangOptions::NonGC) {
for (const ObjCIvarDecl *IVD = OI->all_declared_ivar_begin();
IVD; IVD = IVD->getNextIvar())
ivars.push_back(IVD);
@@ -5662,8 +5745,11 @@
CharUnits beginInstance = CharUnits::fromQuantity(InstanceStart);
CharUnits endInstance = CharUnits::fromQuantity(InstanceSize);
+ bool hasMRCWeak = false;
if (CGM.getLangOpts().ObjCAutoRefCount)
flags |= NonFragileABI_Class_CompiledByARC;
+ else if ((hasMRCWeak = hasMRCWeakIvars(CGM, ID)))
+ flags |= NonFragileABI_Class_HasMRCWeakIvars;
Values[ 0] = llvm::ConstantInt::get(ObjCTypes.IntTy, flags);
Values[ 1] = llvm::ConstantInt::get(ObjCTypes.IntTy, InstanceStart);
@@ -5671,7 +5757,7 @@
// FIXME. For 64bit targets add 0 here.
Values[ 3] = (flags & NonFragileABI_Class_Meta)
? GetIvarLayoutName(nullptr, ObjCTypes)
- : BuildIvarLayout(ID, beginInstance, endInstance, true);
+ : BuildStrongIvarLayout(ID, beginInstance, endInstance);
Values[ 4] = GetClassName(ID->getObjCRuntimeNameAsString());
// const struct _method_list_t * const baseMethods;
std::vector<llvm::Constant*> Methods;
@@ -5718,7 +5804,8 @@
Values[ 9] = llvm::Constant::getNullValue(ObjCTypes.PropertyListPtrTy);
} else {
Values[ 7] = EmitIvarList(ID);
- Values[ 8] = BuildIvarLayout(ID, beginInstance, endInstance, false);
+ Values[ 8] = BuildWeakIvarLayout(ID, beginInstance, endInstance,
+ hasMRCWeak);
Values[ 9] = EmitPropertyList("\01l_OBJC_$_PROP_LIST_" + ID->getObjCRuntimeNameAsString(),
ID, ID->getClassInterface(), ObjCTypes);
}