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Emit correct ivar bounds and offsets.

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I had thought that we could get away with letting the
runtime figure out that these offsets were invalid (and
thus recompute them), but it turns out that the runtime
has some basic consistency requirements:  basically, it
expects the ivars to have been correctly laid out, and
it merely slides them around according to the layout of
the superclass.

Swift SVN r3747
This commit is contained in:
John McCall
2013-01-11 08:09:08 +00:00
parent d4f80a3993
commit 45ed2ef355
2 changed files with 39 additions and 12 deletions
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45
lib/IRGen/GenClass.cpp
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@@ -684,6 +684,7 @@ namespace {
IRGenModule &IGM;
ClassDecl *TheClass;
const LayoutClass &Layout;
const StructLayout &FieldLayout;
bool HasNonTrivialDestructor = false;
bool HasNonTrivialConstructor = false;
@@ -693,10 +694,13 @@ namespace {
SmallVector<llvm::Constant*, 4> Protocols;
SmallVector<llvm::Constant*, 8> Properties;
llvm::Constant *Name = nullptr;
unsigned NextFieldIndex = 0;
public:
ClassDataBuilder(IRGenModule &IGM, ClassDecl *theClass,
const LayoutClass &layout)
: IGM(IGM), TheClass(theClass), Layout(layout) {
const LayoutClass &layout,
const StructLayout &fieldLayout)
: IGM(IGM), TheClass(theClass), Layout(layout),
FieldLayout(fieldLayout) {
visitMembers(TheClass);
}
@@ -741,17 +745,31 @@ namespace {
// uint32_t instanceStart;
// uint32_t instanceSize;
// These are generally filled in by the runtime.
// TODO: it's an optimization to have them have the right values
// at launch-time.
auto zero32 = llvm::ConstantInt::get(IGM.Int32Ty, 0);
fields.push_back(zero32);
fields.push_back(zero32);
// The runtime requires that the ivar offsets be initialized to
// a valid layout of the ivars of this class, bounded by these
// two values. If the instanceSize of the base class equals the
// stored instanceStart of the derived class, the ivar offsets
// will not be changed.
Size instanceStart = Size(0);
Size instanceSize = Size(0);
if (!forMeta) {
instanceSize = FieldLayout.getSize();
if (FieldLayout.getElements().empty()) {
instanceStart = instanceSize;
} else {
// FIXME: assumes layout is always sequential!
instanceStart = FieldLayout.getElements()[0].ByteOffset;
}
}
fields.push_back(llvm::ConstantInt::get(IGM.Int32Ty,
instanceStart.getValue()));
fields.push_back(llvm::ConstantInt::get(IGM.Int32Ty,
instanceSize.getValue()));
// uint32_t reserved; // only when building for 64bit targets
if (IGM.getPointerAlignment().getValue() > 4) {
assert(IGM.getPointerAlignment().getValue() == 8);
fields.push_back(zero32);
fields.push_back(llvm::ConstantInt::get(IGM.Int32Ty, 0));
}
// const uint8_t *ivarLayout;
@@ -907,10 +925,13 @@ namespace {
/// };
llvm::Constant *buildIvar(VarDecl *ivar) {
// FIXME: this is not always the right thing to do!
auto &elt = FieldLayout.getElements()[NextFieldIndex++];
auto offsetAddr = IGM.getAddrOfFieldOffset(ivar, /*direct*/ true);
auto offsetVar = cast<llvm::GlobalVariable>(offsetAddr.getAddress());
offsetVar->setConstant(false);
offsetVar->setInitializer(llvm::ConstantInt::get(IGM.IntPtrTy, 0));
auto offsetVal =
llvm::ConstantInt::get(IGM.IntPtrTy, elt.ByteOffset.getValue());
offsetVar->setInitializer(offsetVal);
// TODO: clang puts this in __TEXT,__objc_methname,cstring_literals
auto name = IGM.getAddrOfGlobalString(ivar->getName().str());
@@ -1062,8 +1083,10 @@ llvm::Constant *irgen::emitClassPrivateData(IRGenModule &IGM,
ClassDecl *cls) {
assert(IGM.ObjCInterop && "emitting RO-data outside of interop mode");
CanType type = cls->getDeclaredTypeInContext()->getCanonicalType();
auto &classTI = IGM.getFragileTypeInfo(type).as<ClassTypeInfo>();
auto &fieldLayout = classTI.getLayout(IGM);
LayoutClass layout(IGM, ResilienceScope::Universal, cls, type);
ClassDataBuilder builder(IGM, cls, layout);
ClassDataBuilder builder(IGM, cls, layout, fieldLayout);
// First, build the metaclass object.
builder.buildMetaclassStub();