/// Emit a checked cast of a metatype.
void irgen::emitMetatypeDowncast(IRGenFunction &IGF,
llvm::Value *metatype,
CanMetatypeType toMetatype,
CheckedCastMode mode,
Explosion &ex) {
// Pick a runtime entry point and target metadata based on what kind of
// representation we're casting.
llvm::Value *castFn;
llvm::Value *toMetadata;
switch (toMetatype->getRepresentation()) {
case MetatypeRepresentation::Thick: {
// Get the Swift metadata for the type we're checking.
toMetadata = IGF.emitTypeMetadataRef(toMetatype.getInstanceType());
switch (mode) {
case CheckedCastMode::Unconditional:
castFn = IGF.IGM.getDynamicCastMetatypeUnconditionalFn();
break;
case CheckedCastMode::Conditional:
castFn = IGF.IGM.getDynamicCastMetatypeFn();
break;
}
break;
}
case MetatypeRepresentation::ObjC: {
assert(IGF.IGM.ObjCInterop && "should have objc runtime");
// Get the ObjC metadata for the type we're checking.
toMetadata = emitClassHeapMetadataRef(IGF, toMetatype.getInstanceType(),
MetadataValueType::ObjCClass);
switch (mode) {
case CheckedCastMode::Unconditional:
castFn = IGF.IGM.getDynamicCastObjCClassMetatypeUnconditionalFn();
break;
case CheckedCastMode::Conditional:
castFn = IGF.IGM.getDynamicCastObjCClassMetatypeFn();
break;
}
break;
}
case MetatypeRepresentation::Thin:
llvm_unreachable("not implemented");
}
auto cc = IGF.IGM.DefaultCC;
if (auto fun = dyn_cast<llvm::Function>(castFn))
cc = fun->getCallingConv();
auto call = IGF.Builder.CreateCall(castFn, {metatype, toMetadata});
call->setCallingConv(cc);
call->setDoesNotThrow();
ex.add(call);
}
void
irgen::emitTypeLayoutVerifier(IRGenFunction &IGF,
ArrayRef<CanType> formalTypes) {
llvm::Type *verifierArgTys[] = {
IGF.IGM.TypeMetadataPtrTy,
IGF.IGM.Int8PtrTy,
IGF.IGM.Int8PtrTy,
IGF.IGM.SizeTy,
IGF.IGM.Int8PtrTy,
};
auto verifierFnTy = llvm::FunctionType::get(IGF.IGM.VoidTy,
verifierArgTys,
/*var arg*/ false);
auto verifierFn = IGF.IGM.Module.getOrInsertFunction(
"_swift_debug_verifyTypeLayoutAttribute",
verifierFnTy);
struct VerifierArgumentBuffers {
Address runtimeBuf, staticBuf;
};
llvm::DenseMap<llvm::Type *, VerifierArgumentBuffers>
verifierArgBufs;
auto getSizeConstant = [&](Size sz) -> llvm::Constant * {
return llvm::ConstantInt::get(IGF.IGM.SizeTy, sz.getValue());
};
auto getAlignmentMaskConstant = [&](Alignment a) -> llvm::Constant * {
return llvm::ConstantInt::get(IGF.IGM.SizeTy, a.getValue() - 1);
};
auto getBoolConstant = [&](bool b) -> llvm::Constant * {
return llvm::ConstantInt::get(IGF.IGM.Int1Ty, b);
};
SmallString<20> numberBuf;
for (auto formalType : formalTypes) {
// Runtime type metadata always represents the maximal abstraction level of
// the type.
auto anyTy = ProtocolCompositionType::get(IGF.IGM.Context, {});
auto openedAnyTy = ArchetypeType::getOpened(anyTy);
auto maxAbstraction = AbstractionPattern(openedAnyTy);
auto &ti = IGF.getTypeInfoForUnlowered(maxAbstraction, formalType);
// If there's no fixed type info, we rely on the runtime anyway, so there's
// nothing to verify.
// TODO: There are some traits of partially-fixed layouts we could check too.
auto *fixedTI = dyn_cast<FixedTypeInfo>(&ti);
if (!fixedTI)
return;
auto metadata = IGF.emitTypeMetadataRef(formalType);
auto verify = [&](llvm::Value *runtimeVal,
llvm::Value *staticVal,
const llvm::Twine &description) {
assert(runtimeVal->getType() == staticVal->getType());
// Get or create buffers for the arguments.
VerifierArgumentBuffers bufs;
auto foundBufs = verifierArgBufs.find(runtimeVal->getType());
if (foundBufs != verifierArgBufs.end()) {
bufs = foundBufs->second;
} else {
Address runtimeBuf = IGF.createAlloca(runtimeVal->getType(),
IGF.IGM.getPointerAlignment(),
"runtime");
Address staticBuf = IGF.createAlloca(staticVal->getType(),
IGF.IGM.getPointerAlignment(),
"static");
bufs = {runtimeBuf, staticBuf};
verifierArgBufs[runtimeVal->getType()] = bufs;
}
IGF.Builder.CreateStore(runtimeVal, bufs.runtimeBuf);
IGF.Builder.CreateStore(staticVal, bufs.staticBuf);
auto runtimePtr = IGF.Builder.CreateBitCast(bufs.runtimeBuf.getAddress(),
IGF.IGM.Int8PtrTy);
auto staticPtr = IGF.Builder.CreateBitCast(bufs.staticBuf.getAddress(),
IGF.IGM.Int8PtrTy);
auto count = llvm::ConstantInt::get(IGF.IGM.SizeTy,
IGF.IGM.DataLayout.getTypeStoreSize(runtimeVal->getType()));
auto msg
= IGF.IGM.getAddrOfGlobalString(description.str());
IGF.Builder.CreateCall(
verifierFn, {metadata, runtimePtr, staticPtr, count, msg});
};
// Check that the fixed layout matches the runtime layout.
SILType layoutType = SILType::getPrimitiveObjectType(formalType);
verify(emitLoadOfSize(IGF, layoutType),
getSizeConstant(fixedTI->getFixedSize()),
"size");
verify(emitLoadOfAlignmentMask(IGF, layoutType),
getAlignmentMaskConstant(fixedTI->getFixedAlignment()),
"alignment mask");
verify(emitLoadOfStride(IGF, layoutType),
getSizeConstant(fixedTI->getFixedStride()),
"stride");
verify(emitLoadOfIsInline(IGF, layoutType),
getBoolConstant(fixedTI->getFixedPacking(IGF.IGM)
== FixedPacking::OffsetZero),
"is-inline bit");
verify(emitLoadOfIsPOD(IGF, layoutType),
getBoolConstant(fixedTI->isPOD(ResilienceScope::Component)),
"is-POD bit");
verify(emitLoadOfIsBitwiseTakable(IGF, layoutType),
getBoolConstant(fixedTI->isBitwiseTakable(ResilienceScope::Component)),
"is-bitwise-takable bit");
unsigned xiCount = fixedTI->getFixedExtraInhabitantCount(IGF.IGM);
verify(emitLoadOfHasExtraInhabitants(IGF, layoutType),
getBoolConstant(xiCount != 0),
"has-extra-inhabitants bit");
// Check extra inhabitants.
if (xiCount > 0) {
verify(emitLoadOfExtraInhabitantCount(IGF, layoutType),
getSizeConstant(Size(xiCount)),
"extra inhabitant count");
// Verify that the extra inhabitant representations are consistent.
/* TODO: Update for EnumPayload implementation changes.
auto xiBuf = IGF.createAlloca(fixedTI->getStorageType(),
fixedTI->getFixedAlignment(),
"extra-inhabitant");
auto xiOpaque = IGF.Builder.CreateBitCast(xiBuf, IGF.IGM.OpaquePtrTy);
// TODO: Randomize the set of extra inhabitants we check.
unsigned bits = fixedTI->getFixedSize().getValueInBits();
for (unsigned i = 0, e = std::min(xiCount, 1024u);
i < e; ++i) {
// Initialize the buffer with junk, to help ensure we're insensitive to
// insignificant bits.
// TODO: Randomize the filler.
IGF.Builder.CreateMemSet(xiBuf.getAddress(),
llvm::ConstantInt::get(IGF.IGM.Int8Ty, 0x5A),
fixedTI->getFixedSize().getValue(),
fixedTI->getFixedAlignment().getValue());
// Ask the runtime to store an extra inhabitant.
auto index = llvm::ConstantInt::get(IGF.IGM.Int32Ty, i);
emitStoreExtraInhabitantCall(IGF, layoutType, index,
xiOpaque.getAddress());
// Compare the stored extra inhabitant against the fixed extra
// inhabitant pattern.
auto fixedXI = fixedTI->getFixedExtraInhabitantValue(IGF.IGM, bits, i);
auto xiBuf2 = IGF.Builder.CreateBitCast(xiBuf,
fixedXI->getType()->getPointerTo());
llvm::Value *runtimeXI = IGF.Builder.CreateLoad(xiBuf2);
runtimeXI = fixedTI->maskFixedExtraInhabitant(IGF, runtimeXI);
numberBuf.clear();
{
llvm::raw_svector_ostream os(numberBuf);
os << i;
os.flush();
}
verify(runtimeXI, fixedXI,
llvm::Twine("stored extra inhabitant ") + numberBuf.str());
// Now store the fixed extra inhabitant and ask the runtime to identify
// it.
// Mask in junk to make sure the runtime correctly ignores it.
auto xiMask = fixedTI->getFixedExtraInhabitantMask(IGF.IGM).asAPInt();
auto maskVal = llvm::ConstantInt::get(IGF.IGM.getLLVMContext(), xiMask);
auto notMaskVal
= llvm::ConstantInt::get(IGF.IGM.getLLVMContext(), ~xiMask);
// TODO: Randomize the filler.
auto xiFill = llvm::ConstantInt::getAllOnesValue(fixedXI->getType());
llvm::Value *xiFillMask = IGF.Builder.CreateAnd(notMaskVal, xiFill);
llvm::Value *xiValMask = IGF.Builder.CreateAnd(maskVal, fixedXI);
llvm::Value *filledXI = IGF.Builder.CreateOr(xiFillMask, xiValMask);
IGF.Builder.CreateStore(filledXI, xiBuf2);
auto runtimeIndex = emitGetExtraInhabitantIndexCall(IGF, layoutType,
xiOpaque.getAddress());
verify(runtimeIndex, index,
llvm::Twine("extra inhabitant index calculation ")
+ numberBuf.str());
}
*/
}
// TODO: Verify interesting layout properties specific to the kind of type,
// such as struct or class field offsets, enum case tags, vtable entries,
// etc.
}
}
/// Emit a checked cast to a protocol or protocol composition.
void irgen::emitScalarExistentialDowncast(IRGenFunction &IGF,
llvm::Value *value,
SILType srcType,
SILType destType,
CheckedCastMode mode,
Optional<MetatypeRepresentation> metatypeKind,
Explosion &ex) {
auto srcInstanceType = srcType.getSwiftRValueType();
auto destInstanceType = destType.getSwiftRValueType();
while (auto metatypeType = dyn_cast<ExistentialMetatypeType>(
destInstanceType)) {
destInstanceType = metatypeType.getInstanceType();
srcInstanceType = cast<AnyMetatypeType>(srcInstanceType).getInstanceType();
}
auto layout = destInstanceType.getExistentialLayout();
// Look up witness tables for the protocols that need them and get
// references to the ObjC Protocol* values for the objc protocols.
SmallVector<llvm::Value*, 4> objcProtos;
SmallVector<llvm::Value*, 4> witnessTableProtos;
bool hasClassConstraint = layout.requiresClass();
bool hasClassConstraintByProtocol = false;
bool hasSuperclassConstraint = bool(layout.superclass);
for (auto protoTy : layout.getProtocols()) {
auto *protoDecl = protoTy->getDecl();
// If the protocol introduces a class constraint, track whether we need
// to check for it independent of protocol witnesses.
if (protoDecl->requiresClass()) {
assert(hasClassConstraint);
hasClassConstraintByProtocol = true;
}
if (Lowering::TypeConverter::protocolRequiresWitnessTable(protoDecl)) {
auto descriptor = emitProtocolDescriptorRef(IGF, protoDecl);
witnessTableProtos.push_back(descriptor);
}
if (protoDecl->isObjC())
objcProtos.push_back(emitReferenceToObjCProtocol(IGF, protoDecl));
}
llvm::Type *resultType;
if (metatypeKind) {
switch (*metatypeKind) {
case MetatypeRepresentation::Thin:
llvm_unreachable("can't cast to thin metatype");
case MetatypeRepresentation::Thick:
resultType = IGF.IGM.TypeMetadataPtrTy;
break;
case MetatypeRepresentation::ObjC:
resultType = IGF.IGM.ObjCClassPtrTy;
break;
}
} else {
auto schema = IGF.getTypeInfo(destType).getSchema();
resultType = schema[0].getScalarType();
}
// The source of a scalar cast is statically known to be a class or a
// metatype, so we only have to check the class constraint in two cases:
//
// 1) The destination type has an explicit superclass constraint that is
// more derived than what the source type is known to be.
//
// 2) We are casting between metatypes, in which case the source might
// be a non-class metatype.
bool checkClassConstraint = false;
if ((bool)metatypeKind &&
hasClassConstraint &&
!hasClassConstraintByProtocol &&
!srcInstanceType->mayHaveSuperclass())
checkClassConstraint = true;
// If the source has an equal or more derived superclass constraint than
// the destination, we can elide the superclass check.
//
// Note that destInstanceType is always an existential type, so calling
// getSuperclass() returns the superclass constraint of the existential,
// not the superclass of some concrete class.
bool checkSuperclassConstraint =
hasSuperclassConstraint &&
!destInstanceType->getSuperclass()->isExactSuperclassOf(srcInstanceType);
if (checkSuperclassConstraint)
checkClassConstraint = true;
llvm::Value *resultValue = value;
// If we don't have anything we really need to check, then trivially succeed.
if (objcProtos.empty() && witnessTableProtos.empty() &&
!checkClassConstraint) {
resultValue = IGF.Builder.CreateBitCast(value, resultType);
ex.add(resultValue);
return;
}
// Check the ObjC protocol conformances if there were any.
llvm::Value *objcCast = nullptr;
if (!objcProtos.empty()) {
// Get the ObjC instance or class object to check for these conformances.
llvm::Value *objcObject;
if (metatypeKind) {
switch (*metatypeKind) {
case MetatypeRepresentation::Thin:
llvm_unreachable("can't cast to thin metatype");
case MetatypeRepresentation::Thick: {
// The metadata might be for a non-class type, which wouldn't have
// an ObjC class object.
objcObject = nullptr;
break;
}
case MetatypeRepresentation::ObjC:
// Metatype is already an ObjC object.
objcObject = value;
break;
}
} else {
// Class instance is already an ObjC object.
objcObject = value;
}
if (objcObject)
objcObject = IGF.Builder.CreateBitCast(objcObject,
IGF.IGM.UnknownRefCountedPtrTy);
// Pick the cast function based on the cast mode and on whether we're
// casting a Swift metatype or ObjC object.
llvm::Constant *castFn;
switch (mode) {
case CheckedCastMode::Unconditional:
castFn = objcObject
? IGF.IGM.getDynamicCastObjCProtocolUnconditionalFn()
: IGF.IGM.getDynamicCastTypeToObjCProtocolUnconditionalFn();
break;
case CheckedCastMode::Conditional:
castFn = objcObject
? IGF.IGM.getDynamicCastObjCProtocolConditionalFn()
: IGF.IGM.getDynamicCastTypeToObjCProtocolConditionalFn();
break;
}
llvm::Value *objcCastObject = objcObject ? objcObject : value;
Address protoRefsBuf = IGF.createAlloca(
llvm::ArrayType::get(IGF.IGM.Int8PtrTy,
objcProtos.size()),
IGF.IGM.getPointerAlignment(),
"objc_protocols");
protoRefsBuf = IGF.Builder.CreateBitCast(protoRefsBuf,
IGF.IGM.Int8PtrPtrTy);
for (unsigned index : indices(objcProtos)) {
Address protoRefSlot = IGF.Builder.CreateConstArrayGEP(
protoRefsBuf, index,
IGF.IGM.getPointerSize());
IGF.Builder.CreateStore(objcProtos[index], protoRefSlot);
++index;
}
auto cc = IGF.IGM.DefaultCC;
if (auto fun = dyn_cast<llvm::Function>(castFn))
cc = fun->getCallingConv();
auto call = IGF.Builder.CreateCall(
castFn,
{objcCastObject, IGF.IGM.getSize(Size(objcProtos.size())),
protoRefsBuf.getAddress()});
call->setCallingConv(cc);
objcCast = call;
resultValue = IGF.Builder.CreateBitCast(objcCast, resultType);
}
// If we don't need to look up any witness tables, we're done.
if (witnessTableProtos.empty() && !checkClassConstraint) {
ex.add(resultValue);
return;
}
// If we're doing a conditional cast, and the ObjC protocol checks failed,
// then the cast is done.
Optional<ConditionalDominanceScope> condition;
llvm::BasicBlock *origBB = nullptr, *successBB = nullptr, *contBB = nullptr;
if (!objcProtos.empty()) {
switch (mode) {
case CheckedCastMode::Unconditional:
break;
case CheckedCastMode::Conditional: {
origBB = IGF.Builder.GetInsertBlock();
successBB = IGF.createBasicBlock("success");
contBB = IGF.createBasicBlock("cont");
auto isNull = IGF.Builder.CreateICmpEQ(objcCast,
llvm::ConstantPointerNull::get(
cast<llvm::PointerType>(objcCast->getType())));
IGF.Builder.CreateCondBr(isNull, contBB, successBB);
IGF.Builder.emitBlock(successBB);
condition.emplace(IGF);
}
}
}
// Get the Swift type metadata for the type.
llvm::Value *metadataValue;
if (metatypeKind) {
switch (*metatypeKind) {
case MetatypeRepresentation::Thin:
llvm_unreachable("can't cast to thin metatype");
case MetatypeRepresentation::Thick:
// The value is already a native metatype.
metadataValue = value;
break;
case MetatypeRepresentation::ObjC:
// Get the type metadata from the ObjC class, which may be a wrapper.
metadataValue = emitObjCMetadataRefForMetadata(IGF, value);
}
} else {
// Get the type metadata for the instance.
metadataValue = emitDynamicTypeOfHeapObject(IGF, value, srcType);
}
// Look up witness tables for the protocols that need them.
auto fn = emitExistentialScalarCastFn(IGF.IGM,
witnessTableProtos.size(),
mode,
checkClassConstraint,
checkSuperclassConstraint);
llvm::SmallVector<llvm::Value *, 4> args;
if (resultValue->getType() != IGF.IGM.Int8PtrTy)
resultValue = IGF.Builder.CreateBitCast(resultValue, IGF.IGM.Int8PtrTy);
args.push_back(resultValue);
args.push_back(metadataValue);
if (checkSuperclassConstraint)
args.push_back(IGF.emitTypeMetadataRef(CanType(layout.superclass)));
for (auto proto : witnessTableProtos)
args.push_back(proto);
auto valueAndWitnessTables = IGF.Builder.CreateCall(fn, args);
resultValue = IGF.Builder.CreateExtractValue(valueAndWitnessTables, 0);
if (resultValue->getType() != resultType)
resultValue = IGF.Builder.CreateBitCast(resultValue, resultType);
ex.add(resultValue);
for (unsigned i = 0, e = witnessTableProtos.size(); i < e; ++i) {
auto wt = IGF.Builder.CreateExtractValue(valueAndWitnessTables, i + 1);
ex.add(wt);
}
// If we had conditional ObjC checks, join the failure paths.
if (contBB) {
condition.reset();
IGF.Builder.CreateBr(contBB);
IGF.Builder.emitBlock(contBB);
// Return null on the failure path.
Explosion successEx = std::move(ex);
ex.reset();
while (!successEx.empty()) {
auto successVal = successEx.claimNext();
auto failureVal = llvm::Constant::getNullValue(successVal->getType());
auto phi = IGF.Builder.CreatePHI(successVal->getType(), 2);
phi->addIncoming(successVal, successBB);
phi->addIncoming(failureVal, origBB);
ex.add(phi);
}
}
}