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fuchsia / third_party / swift / f2cf0510d6e25911e9babada46e0025862bd00cd / . / lib / SILOptimizer / Mandatory / DIMemoryUseCollector.cpp
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//===--- DIMemoryUseCollector.cpp -----------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "definite-init"
#include "DIMemoryUseCollector.h"
#include "swift/AST/Expr.h"
#include "swift/SIL/ApplySite.h"
#include "swift/SIL/InstructionUtils.h"
#include "swift/SIL/SILArgument.h"
#include "swift/SIL/SILBuilder.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/SaveAndRestore.h"
using namespace swift;
using namespace ownership;
//===----------------------------------------------------------------------===//
// Utility
//===----------------------------------------------------------------------===//
static void gatherDestroysOfContainer(const DIMemoryObjectInfo &memoryInfo,
DIElementUseInfo &useInfo) {
auto *uninitMemory = memoryInfo.getUninitializedValue();
// The uninitMemory must be used on an alloc_box, alloc_stack, or global_addr.
// If we have an alloc_stack or a global_addr, there is nothing further to do.
if (isa<AllocStackInst>(uninitMemory->getOperand(0)) ||
isa<GlobalAddrInst>(uninitMemory->getOperand(0)) ||
isa<SILArgument>(uninitMemory->getOperand(0)) ||
// FIXME: We only support pointer to address here to not break LLDB. It is
// important that long term we get rid of this since this is a situation
// where LLDB is breaking SILGen/DI invariants by not creating a new
// independent stack location for the pointer to address.
isa<PointerToAddressInst>(uninitMemory->getOperand(0))) {
return;
}
// Otherwise, we assume that we have an alloc_box. Treat destroys of the
// alloc_box as load+destroys of the value stored in the box.
//
// TODO: This should really be tracked separately from other destroys so that
// we distinguish the lifetime of the container from the value itself.
assert(isa<ProjectBoxInst>(uninitMemory));
auto *mui = cast<MarkUninitializedInst>(uninitMemory->getOperand(0));
for (auto *user : mui->getUsersOfType<DestroyValueInst>()) {
useInfo.trackDestroy(user);
}
}
//===----------------------------------------------------------------------===//
// DIMemoryObjectInfo Implementation
//===----------------------------------------------------------------------===//
static unsigned getElementCountRec(TypeExpansionContext context,
SILModule &Module, SILType T,
bool IsSelfOfNonDelegatingInitializer) {
// If this is a tuple, it is always recursively flattened.
if (CanTupleType TT = T.getAs<TupleType>()) {
assert(!IsSelfOfNonDelegatingInitializer && "self never has tuple type");
unsigned NumElements = 0;
for (unsigned i = 0, e = TT->getNumElements(); i < e; ++i)
NumElements +=
getElementCountRec(context, Module, T.getTupleElementType(i), false);
return NumElements;
}
// If this is the top level of a 'self' value, we flatten structs and classes.
// Stored properties with tuple types are tracked with independent lifetimes
// for each of the tuple members.
if (IsSelfOfNonDelegatingInitializer) {
// Protocols never have a stored properties.
if (auto *NTD = T.getNominalOrBoundGenericNominal()) {
unsigned NumElements = 0;
for (auto *VD : NTD->getStoredProperties())
NumElements += getElementCountRec(
context, Module, T.getFieldType(VD, Module, context), false);
return NumElements;
}
}
// Otherwise, it is a single element.
return 1;
}
static std::pair<SILType, bool>
computeMemorySILType(MarkUninitializedInst *MemoryInst) {
// Compute the type of the memory object.
auto *MUI = MemoryInst;
SILValue Address = MUI;
if (auto *PBI = Address->getSingleUserOfType<ProjectBoxInst>()) {
Address = PBI;
}
SILType MemorySILType = Address->getType().getObjectType();
// If this is a let variable we're initializing, remember this so we don't
// allow reassignment.
if (!MUI->isVar())
return {MemorySILType, false};
auto *VDecl = MUI->getLoc().getAsASTNode<VarDecl>();
if (!VDecl)
return {MemorySILType, false};
return {MemorySILType, VDecl->isLet()};
}
DIMemoryObjectInfo::DIMemoryObjectInfo(MarkUninitializedInst *MI)
: MemoryInst(MI) {
auto &Module = MI->getModule();
std::tie(MemorySILType, IsLet) = computeMemorySILType(MemoryInst);
// Compute the number of elements to track in this memory object.
// If this is a 'self' in a delegating initializer, we only track one bit:
// whether self.init is called or not.
if (isDelegatingInit()) {
NumElements = 1;
return;
}
// If this is a derived class init method for which stored properties are
// separately initialized, track an element for the super.init call.
if (isDerivedClassSelfOnly()) {
NumElements = 1;
return;
}
// Otherwise, we break down the initializer.
NumElements =
getElementCountRec(TypeExpansionContext(*MI->getFunction()), Module,
MemorySILType, isNonDelegatingInit());
// If this is a derived class init method, track an extra element to determine
// whether super.init has been called at each program point.
NumElements += unsigned(isDerivedClassSelf());
// Make sure we track /something/ in a cross-module struct initializer.
if (NumElements == 0 && isCrossModuleStructInitSelf()) {
NumElements = 1;
HasDummyElement = true;
}
}
SILInstruction *DIMemoryObjectInfo::getFunctionEntryPoint() const {
return &*getFunction().begin()->begin();
}
/// Given a symbolic element number, return the type of the element.
static SILType getElementTypeRec(TypeExpansionContext context,
SILModule &Module, SILType T, unsigned EltNo,
bool IsSelfOfNonDelegatingInitializer) {
// If this is a tuple type, walk into it.
if (CanTupleType TT = T.getAs<TupleType>()) {
assert(!IsSelfOfNonDelegatingInitializer && "self never has tuple type");
for (unsigned i = 0, e = TT->getNumElements(); i < e; ++i) {
auto FieldType = T.getTupleElementType(i);
unsigned NumFieldElements =
getElementCountRec(context, Module, FieldType, false);
if (EltNo < NumFieldElements)
return getElementTypeRec(context, Module, FieldType, EltNo, false);
EltNo -= NumFieldElements;
}
// This can only happen if we look at a symbolic element number of an empty
// tuple.
llvm::report_fatal_error("invalid element number");
}
// If this is the top level of a 'self' value, we flatten structs and classes.
// Stored properties with tuple types are tracked with independent lifetimes
// for each of the tuple members.
if (IsSelfOfNonDelegatingInitializer) {
if (auto *NTD = T.getNominalOrBoundGenericNominal()) {
bool HasStoredProperties = false;
for (auto *VD : NTD->getStoredProperties()) {
HasStoredProperties = true;
auto FieldType = T.getFieldType(VD, Module, context);
unsigned NumFieldElements =
getElementCountRec(context, Module, FieldType, false);
if (EltNo < NumFieldElements)
return getElementTypeRec(context, Module, FieldType, EltNo, false);
EltNo -= NumFieldElements;
}
// If we do not have any stored properties and were passed an EltNo of 0,
// just return self.
if (!HasStoredProperties && EltNo == 0) {
return T;
}
llvm::report_fatal_error("invalid element number");
}
}
// Otherwise, it is a leaf element.
assert(EltNo == 0);
return T;
}
/// getElementTypeRec - Return the swift type of the specified element.
SILType DIMemoryObjectInfo::getElementType(unsigned EltNo) const {
auto &Module = MemoryInst->getModule();
return getElementTypeRec(TypeExpansionContext(*MemoryInst->getFunction()),
Module, MemorySILType, EltNo, isNonDelegatingInit());
}
/// Given a tuple element number (in the flattened sense) return a pointer to a
/// leaf element of the specified number, so we can insert destroys for it.
SILValue DIMemoryObjectInfo::emitElementAddressForDestroy(
unsigned EltNo, SILLocation Loc, SILBuilder &B,
SmallVectorImpl<std::pair<SILValue, EndScopeKind>> &EndScopeList) const {
SILValue Ptr = getUninitializedValue();
bool IsSelf = isNonDelegatingInit();
auto &Module = MemoryInst->getModule();
auto PointeeType = MemorySILType;
while (1) {
// If we have a tuple, flatten it.
if (CanTupleType TT = PointeeType.getAs<TupleType>()) {
assert(!IsSelf && "self never has tuple type");
// Figure out which field we're walking into.
unsigned FieldNo = 0;
for (unsigned i = 0, e = TT->getNumElements(); i < e; ++i) {
auto EltTy = PointeeType.getTupleElementType(i);
unsigned NumSubElt = getElementCountRec(
TypeExpansionContext(B.getFunction()), Module, EltTy, false);
if (EltNo < NumSubElt) {
Ptr = B.createTupleElementAddr(Loc, Ptr, FieldNo);
PointeeType = EltTy;
break;
}
EltNo -= NumSubElt;
++FieldNo;
}
continue;
}
// If this is the top level of a 'self' value, we flatten structs and
// classes. Stored properties with tuple types are tracked with independent
// lifetimes for each of the tuple members.
if (IsSelf) {
if (auto *NTD = PointeeType.getNominalOrBoundGenericNominal()) {
bool HasStoredProperties = false;
for (auto *VD : NTD->getStoredProperties()) {
if (!HasStoredProperties) {
HasStoredProperties = true;
// If we have a class, we can use a borrow directly and avoid ref
// count traffic.
if (isa<ClassDecl>(NTD) && Ptr->getType().isAddress()) {
SILValue Borrowed = Ptr = B.createLoadBorrow(Loc, Ptr);
EndScopeList.emplace_back(Borrowed, EndScopeKind::Borrow);
}
}
auto expansionContext = TypeExpansionContext(B.getFunction());
auto FieldType =
PointeeType.getFieldType(VD, Module, expansionContext);
unsigned NumFieldElements =
getElementCountRec(expansionContext, Module, FieldType, false);
if (EltNo < NumFieldElements) {
if (isa<StructDecl>(NTD)) {
Ptr = B.createStructElementAddr(Loc, Ptr, VD);
} else {
assert(isa<ClassDecl>(NTD));
SILValue Original, Borrowed;
if (Ptr.getOwnershipKind() != OwnershipKind::Guaranteed) {
Original = Ptr;
Borrowed = Ptr = B.createBeginBorrow(Loc, Ptr);
EndScopeList.emplace_back(Borrowed, EndScopeKind::Borrow);
}
Ptr = B.createRefElementAddr(Loc, Ptr, VD);
Ptr = B.createBeginAccess(
Loc, Ptr, SILAccessKind::Deinit, SILAccessEnforcement::Static,
false /*noNestedConflict*/, false /*fromBuiltin*/);
EndScopeList.emplace_back(Ptr, EndScopeKind::Access);
}
PointeeType = FieldType;
IsSelf = false;
break;
}
EltNo -= NumFieldElements;
}
if (!HasStoredProperties) {
assert(EltNo == 0 && "Element count problem");
return Ptr;
}
continue;
}
}
// Have we gotten to our leaf element?
assert(EltNo == 0 && "Element count problem");
return Ptr;
}
}
/// Push the symbolic path name to the specified element number onto the
/// specified std::string.
static void getPathStringToElementRec(TypeExpansionContext context,
SILModule &Module, SILType T,
unsigned EltNo, std::string &Result) {
CanTupleType TT = T.getAs<TupleType>();
if (!TT) {
// Otherwise, there are no subelements.
assert(EltNo == 0 && "Element count problem");
return;
}
unsigned FieldNo = 0;
for (unsigned i = 0, e = TT->getNumElements(); i < e; ++i) {
auto Field = TT->getElement(i);
SILType FieldTy = T.getTupleElementType(i);
unsigned NumFieldElements = getElementCountRec(context, Module, FieldTy, false);
if (EltNo < NumFieldElements) {
Result += '.';
if (Field.hasName())
Result += Field.getName().str();
else
Result += llvm::utostr(FieldNo);
return getPathStringToElementRec(context, Module, FieldTy, EltNo, Result);
}
EltNo -= NumFieldElements;
++FieldNo;
}
llvm_unreachable("Element number is out of range for this type!");
}
ValueDecl *
DIMemoryObjectInfo::getPathStringToElement(unsigned Element,
std::string &Result) const {
auto &Module = MemoryInst->getModule();
if (isAnyInitSelf())
Result = "self";
else if (ValueDecl *VD =
dyn_cast_or_null<ValueDecl>(getLoc().getAsASTNode<Decl>()))
Result = std::string(VD->getBaseIdentifier());
else
Result = "<unknown>";
// If this is indexing into a field of 'self', look it up.
auto expansionContext = TypeExpansionContext(*MemoryInst->getFunction());
if (isNonDelegatingInit() && !isDerivedClassSelfOnly()) {
if (auto *NTD = MemorySILType.getNominalOrBoundGenericNominal()) {
bool HasStoredProperty = false;
for (auto *VD : NTD->getStoredProperties()) {
HasStoredProperty = true;
auto FieldType =
MemorySILType.getFieldType(VD, Module, expansionContext);
unsigned NumFieldElements =
getElementCountRec(expansionContext, Module, FieldType, false);
if (Element < NumFieldElements) {
Result += '.';
auto originalProperty = VD->getOriginalWrappedProperty();
if (originalProperty) {
Result += originalProperty->getName().str();
} else {
Result += VD->getName().str();
}
getPathStringToElementRec(expansionContext, Module, FieldType,
Element, Result);
return VD;
}
Element -= NumFieldElements;
}
// If we do not have any stored properties, we have nothing of interest.
if (!HasStoredProperty)
return nullptr;
}
}
// Get the path through a tuple, if relevant.
getPathStringToElementRec(expansionContext, Module, MemorySILType, Element,
Result);
// If we are analyzing a variable, we can generally get the decl associated
// with it.
if (MemoryInst->isVar())
return MemoryInst->getLoc().getAsASTNode<VarDecl>();
// Otherwise, we can't.
return nullptr;
}
/// If the specified value is a 'let' property in an initializer, return true.
bool DIMemoryObjectInfo::isElementLetProperty(unsigned Element) const {
// If we aren't representing 'self' in a non-delegating initializer, then we
// can't have 'let' properties.
if (!isNonDelegatingInit())
return IsLet;
auto &Module = MemoryInst->getModule();
auto *NTD = MemorySILType.getNominalOrBoundGenericNominal();
if (!NTD) {
// Otherwise, we miscounted elements?
assert(Element == 0 && "Element count problem");
return false;
}
auto expansionContext = TypeExpansionContext(*MemoryInst->getFunction());
for (auto *VD : NTD->getStoredProperties()) {
auto FieldType = MemorySILType.getFieldType(VD, Module, expansionContext);
unsigned NumFieldElements =
getElementCountRec(expansionContext, Module, FieldType, false);
if (Element < NumFieldElements)
return VD->isLet();
Element -= NumFieldElements;
}
// Otherwise, we miscounted elements?
assert(Element == 0 && "Element count problem");
return false;
}
//===----------------------------------------------------------------------===//
// DIMemoryUse Implementation
//===----------------------------------------------------------------------===//
/// onlyTouchesTrivialElements - Return true if all of the accessed elements
/// have trivial type and the access itself is a trivial instruction.
bool DIMemoryUse::onlyTouchesTrivialElements(
const DIMemoryObjectInfo &MI) const {
// assign_by_wrapper calls functions to assign a value. This is not
// considered as trivial.
if (isa<AssignByWrapperInst>(Inst))
return false;
auto *F = Inst->getFunction();
for (unsigned i = FirstElement, e = i + NumElements; i != e; ++i) {
// Skip 'super.init' bit
if (i == MI.getNumMemoryElements())
return false;
auto EltTy = MI.getElementType(i);
if (!EltTy.isTrivial(*F))
return false;
}
return true;
}
//===----------------------------------------------------------------------===//
// DIElementUseInfo Implementation
//===----------------------------------------------------------------------===//
void DIElementUseInfo::trackStoreToSelf(SILInstruction *I) {
StoresToSelf.push_back(I);
}
//===----------------------------------------------------------------------===//
// ElementUseCollector Implementation
//===----------------------------------------------------------------------===//
namespace {
/// Gathers information about a specific address and its uses to determine
/// definite initialization.
class ElementUseCollector {
SILModule &Module;
const DIMemoryObjectInfo &TheMemory;
DIElementUseInfo &UseInfo;
/// IsSelfOfNonDelegatingInitializer - This is true if we're looking at the
/// top level of a 'self' variable in a non-delegating init method.
bool IsSelfOfNonDelegatingInitializer;
/// When walking the use list, if we index into a struct element, keep track
/// of this, so that any indexes into tuple subelements don't affect the
/// element we attribute an access to.
bool InStructSubElement = false;
/// When walking the use list, if we index into an enum slice, keep track
/// of this.
bool InEnumSubElement = false;
public:
ElementUseCollector(const DIMemoryObjectInfo &TheMemory,
DIElementUseInfo &UseInfo)
: Module(TheMemory.getModule()), TheMemory(TheMemory), UseInfo(UseInfo) {}
/// This is the main entry point for the use walker. It collects uses from
/// the address and the refcount result of the allocation.
void collectFrom() {
IsSelfOfNonDelegatingInitializer = TheMemory.isNonDelegatingInit();
// If this is a delegating initializer, collect uses specially.
if (IsSelfOfNonDelegatingInitializer &&
TheMemory.getASTType()->getClassOrBoundGenericClass() != nullptr) {
assert(!TheMemory.isDerivedClassSelfOnly() &&
"Should have been handled outside of here");
// If this is a class pointer, we need to look through ref_element_addrs.
collectClassSelfUses();
return;
}
collectUses(TheMemory.getUninitializedValue(), 0);
gatherDestroysOfContainer(TheMemory, UseInfo);
}
void trackUse(DIMemoryUse Use) { UseInfo.trackUse(Use); }
void trackDestroy(SILInstruction *Destroy) { UseInfo.trackDestroy(Destroy); }
/// Return the raw number of elements including the 'super.init' value.
unsigned getNumMemoryElements() const { return TheMemory.getNumElements(); }
private:
void collectUses(SILValue Pointer, unsigned BaseEltNo);
void collectClassSelfUses();
void collectClassSelfUses(SILValue ClassPointer, SILType MemorySILType,
llvm::SmallDenseMap<VarDecl *, unsigned> &EN);
void addElementUses(unsigned BaseEltNo, SILType UseTy, SILInstruction *User,
DIUseKind Kind);
void collectTupleElementUses(TupleElementAddrInst *TEAI, unsigned BaseEltNo);
void collectStructElementUses(StructElementAddrInst *SEAI,
unsigned BaseEltNo);
};
} // end anonymous namespace
/// addElementUses - An operation (e.g. load, store, inout use, etc) on a value
/// acts on all of the aggregate elements in that value. For example, a load
/// of $*(Int,Int) is a use of both Int elements of the tuple. This is a helper
/// to keep the Uses data structure up to date for aggregate uses.
void ElementUseCollector::addElementUses(unsigned BaseEltNo, SILType UseTy,
SILInstruction *User, DIUseKind Kind) {
// If we're in a subelement of a struct or enum, just mark the struct, not
// things that come after it in a parent tuple.
unsigned NumElements = 1;
if (TheMemory.getNumElements() != 1 && !InStructSubElement &&
!InEnumSubElement)
NumElements =
getElementCountRec(TypeExpansionContext(*User->getFunction()), Module,
UseTy, IsSelfOfNonDelegatingInitializer);
trackUse(DIMemoryUse(User, Kind, BaseEltNo, NumElements));
}
/// Given a tuple_element_addr or struct_element_addr, compute the new
/// BaseEltNo implicit in the selected member, and recursively add uses of
/// the instruction.
void ElementUseCollector::collectTupleElementUses(TupleElementAddrInst *TEAI,
unsigned BaseEltNo) {
// If we're walking into a tuple within a struct or enum, don't adjust the
// BaseElt. The uses hanging off the tuple_element_addr are going to be
// counted as uses of the struct or enum itself.
if (InStructSubElement || InEnumSubElement)
return collectUses(TEAI, BaseEltNo);
assert(!IsSelfOfNonDelegatingInitializer && "self doesn't have tuple type");
// tuple_element_addr P, 42 indexes into the current tuple element.
// Recursively process its uses with the adjusted element number.
unsigned FieldNo = TEAI->getFieldIndex();
auto T = TEAI->getOperand()->getType();
if (T.is<TupleType>()) {
for (unsigned i = 0; i != FieldNo; ++i) {
SILType EltTy = T.getTupleElementType(i);
BaseEltNo += getElementCountRec(TypeExpansionContext(*TEAI->getFunction()),
Module, EltTy, false);
}
}
collectUses(TEAI, BaseEltNo);
}
void ElementUseCollector::collectStructElementUses(StructElementAddrInst *SEAI,
unsigned BaseEltNo) {
// Generally, we set the "InStructSubElement" flag and recursively process
// the uses so that we know that we're looking at something within the
// current element.
if (!IsSelfOfNonDelegatingInitializer) {
llvm::SaveAndRestore<bool> X(InStructSubElement, true);
collectUses(SEAI, BaseEltNo);
return;
}
// If this is the top level of 'self' in an init method, we treat each
// element of the struct as an element to be analyzed independently.
llvm::SaveAndRestore<bool> X(IsSelfOfNonDelegatingInitializer, false);
for (auto *VD : SEAI->getStructDecl()->getStoredProperties()) {
if (SEAI->getField() == VD)
break;
auto expansionContext = TypeExpansionContext(*SEAI->getFunction());
auto FieldType = SEAI->getOperand()->getType().getFieldType(VD, Module, expansionContext);
BaseEltNo += getElementCountRec(expansionContext, Module, FieldType, false);
}
collectUses(SEAI, BaseEltNo);
}
/// Return the underlying accessed pointer value. This peeks through
/// begin_access patterns such as:
///
/// %mark = mark_uninitialized [rootself] %alloc : $*T
/// %access = begin_access [modify] [unknown] %mark : $*T
/// apply %f(%access) : $(@inout T) -> ()
static SILValue getAccessedPointer(SILValue Pointer) {
if (auto *Access = dyn_cast<BeginAccessInst>(Pointer))
return Access->getSource();
return Pointer;
}
void ElementUseCollector::collectUses(SILValue Pointer, unsigned BaseEltNo) {
assert(Pointer->getType().isAddress() &&
"Walked through the pointer to the value?");
SILType PointeeType = Pointer->getType().getObjectType();
for (auto *Op : Pointer->getUses()) {
auto *User = Op->getUser();
// struct_element_addr P, #field indexes into the current element.
if (auto *SEAI = dyn_cast<StructElementAddrInst>(User)) {
collectStructElementUses(SEAI, BaseEltNo);
continue;
}
// Instructions that compute a subelement are handled by a helper.
if (auto *TEAI = dyn_cast<TupleElementAddrInst>(User)) {
collectTupleElementUses(TEAI, BaseEltNo);
continue;
}
// Look through begin_access.
if (isa<BeginAccessInst>(User)) {
auto begin = cast<SingleValueInstruction>(User);
collectUses(begin, BaseEltNo);
continue;
}
// Ignore end_access.
if (isa<EndAccessInst>(User)) {
continue;
}
// Loads are a use of the value.
if (isa<LoadInst>(User)) {
addElementUses(BaseEltNo, PointeeType, User, DIUseKind::Load);
continue;
}
// Load borrows are similar to loads except that we do not support
// scalarizing them now.
if (isa<LoadBorrowInst>(User)) {
addElementUses(BaseEltNo, PointeeType, User, DIUseKind::Load);
continue;
}
#define NEVER_OR_SOMETIMES_LOADABLE_CHECKED_REF_STORAGE(Name, ...) \
if (isa<Load##Name##Inst>(User)) { \
trackUse(DIMemoryUse(User, DIUseKind::Load, BaseEltNo, 1)); \
continue; \
}
#include "swift/AST/ReferenceStorage.def"
// Stores *to* the allocation are writes.
if ((isa<StoreInst>(User) || isa<AssignInst>(User) ||
isa<AssignByWrapperInst>(User)) &&
Op->getOperandNumber() == 1) {
// Coming out of SILGen, we assume that raw stores are initializations,
// unless they have trivial type (which we classify as InitOrAssign).
DIUseKind Kind;
if (InStructSubElement)
Kind = DIUseKind::PartialStore;
else if (isa<AssignInst>(User) || isa<AssignByWrapperInst>(User))
Kind = DIUseKind::InitOrAssign;
else if (PointeeType.isTrivial(*User->getFunction()))
Kind = DIUseKind::InitOrAssign;
else
Kind = DIUseKind::Initialization;
addElementUses(BaseEltNo, PointeeType, User, Kind);
continue;
}
#define NEVER_OR_SOMETIMES_LOADABLE_CHECKED_REF_STORAGE(Name, ...) \
if (auto SWI = dyn_cast<Store##Name##Inst>(User)) \
if (Op->getOperandNumber() == 1) { \
DIUseKind Kind; \
if (InStructSubElement) \
Kind = DIUseKind::PartialStore; \
else if (SWI->isInitializationOfDest()) \
Kind = DIUseKind::Initialization; \
else \
Kind = DIUseKind::InitOrAssign; \
trackUse(DIMemoryUse(User, Kind, BaseEltNo, 1)); \
continue; \
}
#include "swift/AST/ReferenceStorage.def"
if (auto *CAI = dyn_cast<CopyAddrInst>(User)) {
// If this is the source of the copy_addr, then this is a load. If it is
// the destination, then this is an unknown assignment. Note that we'll
// revisit this instruction and add it to Uses twice if it is both a load
// and store to the same aggregate.
DIUseKind Kind;
if (Op->getOperandNumber() == 0)
Kind = DIUseKind::Load;
else if (InStructSubElement)
Kind = DIUseKind::PartialStore;
else if (CAI->isInitializationOfDest())
Kind = DIUseKind::Initialization;
else
Kind = DIUseKind::InitOrAssign;
addElementUses(BaseEltNo, PointeeType, User, Kind);
continue;
}
// The apply instruction does not capture the pointer when it is passed
// through 'inout' arguments or for indirect returns. InOut arguments are
// treated as uses and may-store's, but an indirect return is treated as a
// full store.
//
// Note that partial_apply instructions always close over their argument.
//
auto Apply = FullApplySite::isa(User);
if (Apply) {
auto substConv = Apply.getSubstCalleeConv();
unsigned ArgumentNumber = Op->getOperandNumber() - 1;
// If this is an out-parameter, it is like a store.
unsigned NumIndirectResults = substConv.getNumIndirectSILResults();
if (ArgumentNumber < NumIndirectResults) {
assert(!InStructSubElement && "We're initializing sub-members?");
addElementUses(BaseEltNo, PointeeType, User, DIUseKind::Initialization);
continue;
// Otherwise, adjust the argument index.
} else {
ArgumentNumber -= NumIndirectResults;
}
auto ParamConvention =
substConv.getParameters()[ArgumentNumber].getConvention();
switch (ParamConvention) {
case ParameterConvention::Direct_Owned:
case ParameterConvention::Direct_Unowned:
case ParameterConvention::Direct_Guaranteed:
llvm_unreachable("address value passed to indirect parameter");
// If this is an in-parameter, it is like a load.
case ParameterConvention::Indirect_In:
case ParameterConvention::Indirect_In_Constant:
case ParameterConvention::Indirect_In_Guaranteed:
addElementUses(BaseEltNo, PointeeType, User, DIUseKind::IndirectIn);
continue;
// If this is an @inout parameter, it is like both a load and store.
case ParameterConvention::Indirect_InoutAliasable: {
// FIXME: The @inout_aliasable convention is used for indirect captures
// of both 'let' and 'var' variables. Using a more specific convention
// for 'let' properties like @in_guaranteed unfortunately exposes bugs
// elsewhere in the pipeline. A 'let' capture cannot really be mutated
// by the callee, and this is enforced by sema, so we can consider it
// a nonmutating use.
bool isLet = true;
for (unsigned i = 0; i < TheMemory.getNumElements(); ++i) {
if (!TheMemory.isElementLetProperty(i)) {
isLet = false;
break;
}
}
if (isLet) {
addElementUses(BaseEltNo, PointeeType, User, DIUseKind::IndirectIn);
continue;
}
LLVM_FALLTHROUGH;
}
case ParameterConvention::Indirect_Inout: {
// If we're in the initializer for a struct, and this is a call to a
// mutating method, we model that as an escape of self. If an
// individual sub-member is passed as inout, then we model that as an
// inout use.
DIUseKind Kind;
if (TheMemory.isStructInitSelf() &&
getAccessedPointer(Pointer) == TheMemory.getUninitializedValue()) {
Kind = DIUseKind::Escape;
} else if (Apply.hasSelfArgument() &&
Op == &Apply.getSelfArgumentOperand()) {
Kind = DIUseKind::InOutSelfArgument;
} else {
Kind = DIUseKind::InOutArgument;
}
addElementUses(BaseEltNo, PointeeType, User, Kind);
continue;
}
}
llvm_unreachable("bad parameter convention");
}
if (isa<AddressToPointerInst>(User)) {
// address_to_pointer is a mutable escape, which we model as an inout use.
addElementUses(BaseEltNo, PointeeType, User,
DIUseKind::InOutArgument);
continue;
}
// init_enum_data_addr is treated like a tuple_element_addr or other
// instruction
// that is looking into the memory object (i.e., the memory object needs to
// be explicitly initialized by a copy_addr or some other use of the
// projected address).
if (auto init = dyn_cast<InitEnumDataAddrInst>(User)) {
assert(!InStructSubElement &&
"init_enum_data_addr shouldn't apply to struct subelements");
// Keep track of the fact that we're inside of an enum. This informs our
// recursion that tuple stores are not scalarized outside, and that stores
// should not be treated as partial stores.
llvm::SaveAndRestore<bool> X(InEnumSubElement, true);
collectUses(init, BaseEltNo);
continue;
}
// init_existential_addr is modeled as an initialization store.
if (isa<InitExistentialAddrInst>(User)) {
assert(!InStructSubElement &&
"init_existential_addr should not apply to struct subelements");
trackUse(DIMemoryUse(User, DIUseKind::Initialization, BaseEltNo, 1));
continue;
}
// inject_enum_addr is modeled as an initialization store.
if (isa<InjectEnumAddrInst>(User)) {
assert(!InStructSubElement &&
"inject_enum_addr the subelement of a struct unless in a ctor");
trackUse(DIMemoryUse(User, DIUseKind::Initialization, BaseEltNo, 1));
continue;
}
// open_existential_addr is either a load or a modification depending on
// how it's marked. Note that the difference is just about immutability
// checking rather than checking initialization before use.
if (auto open = dyn_cast<OpenExistentialAddrInst>(User)) {
// TODO: Is it reasonable to just honor the marking, or should we look
// at all the uses of the open_existential_addr in case one they're
// all really just loads?
switch (open->getAccessKind()) {
case OpenedExistentialAccess::Immutable:
trackUse(DIMemoryUse(User, DIUseKind::Load, BaseEltNo, 1));
continue;
case OpenedExistentialAccess::Mutable:
trackUse(DIMemoryUse(User, DIUseKind::InOutArgument, BaseEltNo, 1));
continue;
}
llvm_unreachable("bad access kind");
}
// unchecked_take_enum_data_addr takes the address of the payload of an
// optional, which could be used to update the payload. So, visit the
// users of this instruction and ensure that there are no overwrites to an
// immutable optional. Note that this special handling is for checking
// immutability and is not for checking initialization before use.
if (auto *enumDataAddr = dyn_cast<UncheckedTakeEnumDataAddrInst>(User)) {
// Keep track of the fact that we're inside of an enum. This informs our
// recursion that tuple stores should not be treated as a partial
// store. This is needed because if the enum has data it would be accessed
// through tuple_element_addr instruction. The entire enum is expected
// to be initialized before any such access.
llvm::SaveAndRestore<bool> X(InEnumSubElement, true);
collectUses(enumDataAddr, BaseEltNo);
continue;
}
// 'select_enum_addr' selects one of the two operands based on the case
// of an enum value.
// 'switch_enum_addr' jumps to one of the two branch labels (provided as
// operands) based on the case of the enum value.
if (isa<SelectEnumAddrInst>(User) || isa<SwitchEnumAddrInst>(User)) {
trackUse(DIMemoryUse(User, DIUseKind::Load, BaseEltNo, 1));
continue;
}
// We model destroy_addr as a release of the entire value.
if (isa<DestroyAddrInst>(User)) {
trackDestroy(User);
continue;
}
if (isa<DeallocStackInst>(User)) {
continue;
}
if (auto *PAI = dyn_cast<PartialApplyInst>(User)) {
if (onlyUsedByAssignByWrapper(PAI))
continue;
}
// Sanitizer instrumentation is not user visible, so it should not
// count as a use and must not affect compile-time diagnostics.
if (isSanitizerInstrumentation(User))
continue;
// Otherwise, the use is something complicated, it escapes.
addElementUses(BaseEltNo, PointeeType, User, DIUseKind::Escape);
}
}
/// collectClassSelfUses - Collect all the uses of a 'self' pointer in a class
/// constructor. The memory object has class type.
void ElementUseCollector::collectClassSelfUses() {
assert(IsSelfOfNonDelegatingInitializer &&
TheMemory.getASTType()->getClassOrBoundGenericClass() != nullptr);
// For efficiency of lookup below, compute a mapping of the local ivars in the
// class to their element number.
llvm::SmallDenseMap<VarDecl *, unsigned> EltNumbering;
{
SILType T = TheMemory.getType();
auto *NTD = T.getNominalOrBoundGenericNominal();
unsigned NumElements = 0;
for (auto *VD : NTD->getStoredProperties()) {
EltNumbering[VD] = NumElements;
auto expansionContext = TypeExpansionContext(TheMemory.getFunction());
NumElements += getElementCountRec(
expansionContext, Module,
T.getFieldType(VD, Module, expansionContext), false);
}
}
// If we are looking at the init method for a root class, just walk the
// MUI use-def chain directly to find our uses.
if (TheMemory.isRootSelf()) {
collectClassSelfUses(TheMemory.getUninitializedValue(), TheMemory.getType(),
EltNumbering);
return;
}
// The number of stores of the initial 'self' argument into the self box
// that we saw.
unsigned StoresOfArgumentToSelf = 0;
// Okay, given that we have a proper setup, we walk the use chains of the self
// box to find any accesses to it. The possible uses are one of:
//
// 1) The initialization store.
// 2) Loads of the box, which have uses of self hanging off of them.
// 3) An assign to the box, which happens at super.init.
// 4) Potential escapes after super.init, if self is closed over.
//
// Handle each of these in turn.
SmallVector<Operand *, 8> Uses(TheMemory.getUninitializedValue()->getUses());
while (!Uses.empty()) {
Operand *Op = Uses.pop_back_val();
SILInstruction *User = Op->getUser();
// Stores to self.
if (auto *SI = dyn_cast<StoreInst>(User)) {
if (Op->getOperandNumber() == 1) {
// The initial store of 'self' into the box at the start of the
// function. Ignore it.
if (auto *Arg = dyn_cast<SILArgument>(SI->getSrc())) {
if (Arg->getParent() == TheMemory.getParentBlock()) {
++StoresOfArgumentToSelf;
continue;
}
}
// A store of a load from the box is ignored.
// SILGen emits these if delegation to another initializer was
// interrupted before the initializer was called.
SILValue src = SI->getSrc();
// Look through conversions.
while (auto conversion = dyn_cast<ConversionInst>(src))
src = conversion->getConverted();
if (auto *LI = dyn_cast<LoadInst>(src))
if (LI->getOperand() == TheMemory.getUninitializedValue())
continue;
// Any other store needs to be recorded.
UseInfo.trackStoreToSelf(SI);
continue;
}
}
// Ignore end_borrows. These can only come from us being the source of a
// load_borrow.
if (isa<EndBorrowInst>(User))
continue;
// Recurse through begin_access.
if (auto *beginAccess = dyn_cast<BeginAccessInst>(User)) {
Uses.append(beginAccess->getUses().begin(), beginAccess->getUses().end());
continue;
}
if (isa<EndAccessInst>(User))
continue;
// Loads of the box produce self, so collect uses from them.
if (isa<LoadInst>(User) || isa<LoadBorrowInst>(User)) {
auto load = cast<SingleValueInstruction>(User);
collectClassSelfUses(load, TheMemory.getType(), EltNumbering);
continue;
}
// destroy_addr on the box is load+release, which is treated as a release.
if (isa<DestroyAddrInst>(User) || isa<StrongReleaseInst>(User) ||
isa<DestroyValueInst>(User)) {
trackDestroy(User);
continue;
}
// Ignore the deallocation of the stack box. Its contents will be
// uninitialized by the point it executes.
if (isa<DeallocStackInst>(User))
continue;
// We can safely handle anything else as an escape. They should all happen
// after super.init is invoked. As such, all elements must be initialized
// and super.init must be called.
trackUse(DIMemoryUse(User, DIUseKind::Load, 0, TheMemory.getNumElements()));
}
assert(StoresOfArgumentToSelf == 1 &&
"The 'self' argument should have been stored into the box exactly once");
}
static bool isSuperInitUse(SILInstruction *User) {
auto *LocExpr = User->getLoc().getAsASTNode<ApplyExpr>();
if (!LocExpr) {
// If we're reading a .sil file, treat a call to "superinit" as a
// super.init call as a hack to allow us to write testcases.
auto *AI = dyn_cast<ApplyInst>(User);
if (AI && AI->getLoc().isSILFile())
if (auto *Fn = AI->getReferencedFunctionOrNull())
if (Fn->getName() == "superinit")
return true;
return false;
}
// This is a super.init call if structured like this:
// (call_expr type='SomeClass'
// (dot_syntax_call_expr type='() -> SomeClass' super
// (other_constructor_ref_expr implicit decl=SomeClass.init)
// (super_ref_expr type='SomeClass'))
// (...some argument...)
LocExpr = dyn_cast<ApplyExpr>(LocExpr->getFn());
if (!LocExpr || !isa<OtherConstructorDeclRefExpr>(LocExpr->getFn()))
return false;
if (LocExpr->getArg()->isSuperExpr())
return true;
// Instead of super_ref_expr, we can also get this for inherited delegating
// initializers:
// (derived_to_base_expr implicit type='C'
// (declref_expr type='D' decl='self'))
if (auto *DTB = dyn_cast<DerivedToBaseExpr>(LocExpr->getArg())) {
if (auto *DRE = dyn_cast<DeclRefExpr>(DTB->getSubExpr())) {
ASTContext &Ctx = DRE->getDecl()->getASTContext();
if (DRE->getDecl()->isImplicit() &&
DRE->getDecl()->getBaseName() == Ctx.Id_self)
return true;
}
}
return false;
}
/// Return true if this SILBBArgument is the result of a call to super.init.
static bool isSuperInitUse(SILArgument *Arg) {
// We only handle a very simple pattern here where there is a single
// predecessor to the block, and the predecessor instruction is a try_apply
// of a throwing delegated init.
auto *BB = Arg->getParent();
auto *Pred = BB->getSinglePredecessorBlock();
// The two interesting cases are where self.init throws, in which case
// the argument came from a try_apply, or if self.init is failable,
// in which case we have a switch_enum.
if (!Pred || (!isa<TryApplyInst>(Pred->getTerminator()) &&
!isa<SwitchEnumInst>(Pred->getTerminator())))
return false;
return isSuperInitUse(Pred->getTerminator());
}
static bool isUninitializedMetatypeInst(SILInstruction *I) {
// A simple reference to "type(of:)" is always fine,
// even if self is uninitialized.
if (isa<ValueMetatypeInst>(I))
return true;
// Sometimes we get an upcast whose sole usage is a value_metatype_inst,
// for example when calling a convenience initializer from a superclass.
if (auto *UCI = dyn_cast<UpcastInst>(I)) {
for (auto *Op : UCI->getUses()) {
auto *User = Op->getUser();
if (isa<ValueMetatypeInst>(User))
continue;
return false;
}
return true;
}
return false;
}
/// isSelfInitUse - Return true if this apply_inst is a call to self.init.
static bool isSelfInitUse(SILInstruction *I) {
// If we're reading a .sil file, treat a call to "selfinit" as a
// self.init call as a hack to allow us to write testcases.
if (I->getLoc().isSILFile()) {
if (auto *AI = dyn_cast<ApplyInst>(I))
if (auto *Fn = AI->getReferencedFunctionOrNull())
if (Fn->getName().startswith("selfinit"))
return true;
return false;
}
// Otherwise, a self.init call must have location info, and must be an expr
// to be considered.
auto *LocExpr = I->getLoc().getAsASTNode<Expr>();
if (!LocExpr)
return false;
// If this is a force_value_expr, it might be a self.init()! call, look
// through it.
if (auto *FVE = dyn_cast<ForceValueExpr>(LocExpr))
LocExpr = FVE->getSubExpr();
// If we have the rebind_self_in_constructor_expr, then the call is the
// sub-expression.
if (auto *RB = dyn_cast<RebindSelfInConstructorExpr>(LocExpr)) {
LocExpr = RB->getSubExpr();
// Look through TryExpr or ForceValueExpr, but not both.
if (auto *TE = dyn_cast<AnyTryExpr>(LocExpr))
LocExpr = TE->getSubExpr();
else if (auto *FVE = dyn_cast<ForceValueExpr>(LocExpr))
LocExpr = FVE->getSubExpr();
}
// Look through covariant return, if any.
if (auto CRE = dyn_cast<CovariantReturnConversionExpr>(LocExpr))
LocExpr = CRE->getSubExpr();
// This is a self.init call if structured like this:
//
// (call_expr type='SomeClass'
// (dot_syntax_call_expr type='() -> SomeClass' self
// (other_constructor_ref_expr implicit decl=SomeClass.init)
// (decl_ref_expr type='SomeClass', "self"))
// (...some argument...)
//
// Or like this:
//
// (call_expr type='SomeClass'
// (dot_syntax_call_expr type='() -> SomeClass' self
// (decr_ref_expr implicit decl=SomeClass.init)
// (decl_ref_expr type='SomeClass', "self"))
// (...some argument...)
//
if (auto *AE = dyn_cast<ApplyExpr>(LocExpr)) {
if ((AE = dyn_cast<ApplyExpr>(AE->getFn()))) {
if (isa<OtherConstructorDeclRefExpr>(AE->getFn()))
return true;
if (auto *DRE = dyn_cast<DeclRefExpr>(AE->getFn()))
if (auto *CD = dyn_cast<ConstructorDecl>(DRE->getDecl()))
if (CD->isFactoryInit())
return true;
}
}
return false;
}
/// Return true if this SILBBArgument is the result of a call to self.init.
static bool isSelfInitUse(SILArgument *Arg) {
// We only handle a very simple pattern here where there is a single
// predecessor to the block, and the predecessor instruction is a try_apply
// of a throwing delegated init.
auto *BB = Arg->getParent();
auto *Pred = BB->getSinglePredecessorBlock();
// The two interesting cases are where self.init throws, in which case
// the argument came from a try_apply, or if self.init is failable,
// in which case we have a switch_enum.
if (!Pred || (!isa<TryApplyInst>(Pred->getTerminator()) &&
!isa<SwitchEnumInst>(Pred->getTerminator())))
return false;
return isSelfInitUse(Pred->getTerminator());
}
static bool isSelfOperand(const Operand *Op, const SILInstruction *User) {
unsigned operandNum = Op->getOperandNumber();
unsigned numOperands;
// FIXME: This should just be cast<FullApplySite>(User) but that doesn't
// work
if (auto *AI = dyn_cast<ApplyInst>(User))
numOperands = AI->getNumOperands();
else
numOperands = cast<TryApplyInst>(User)->getNumOperands();
return (operandNum == numOperands - 1);
}
void ElementUseCollector::collectClassSelfUses(
SILValue ClassPointer, SILType MemorySILType,
llvm::SmallDenseMap<VarDecl *, unsigned> &EltNumbering) {
llvm::SmallVector<Operand *, 16> Worklist(ClassPointer->use_begin(),
ClassPointer->use_end());
while (!Worklist.empty()) {
auto *Op = Worklist.pop_back_val();
auto *User = Op->getUser();
// Ignore any method lookup use.
if (isa<SuperMethodInst>(User) ||
isa<ObjCSuperMethodInst>(User) ||
isa<ClassMethodInst>(User) ||
isa<ObjCMethodInst>(User)) {
continue;
}
// Skip end_borrow and end_access.
if (isa<EndBorrowInst>(User) || isa<EndAccessInst>(User))
continue;
// ref_element_addr P, #field lookups up a field.
if (auto *REAI = dyn_cast<RefElementAddrInst>(User)) {
// FIXME: This is a Sema bug and breaks resilience, we should not
// emit ref_element_addr in such cases at all.
if (EltNumbering.count(REAI->getField()) != 0) {
assert(EltNumbering.count(REAI->getField()) &&
"ref_element_addr not a local field?");
// Recursively collect uses of the fields. Note that fields of the class
// could be tuples, so they may be tracked as independent elements.
llvm::SaveAndRestore<bool> X(IsSelfOfNonDelegatingInitializer, false);
collectUses(REAI, EltNumbering[REAI->getField()]);
continue;
}
}
// retains of self in class constructors can be ignored since we do not care
// about the retain that we are producing, but rather the consumer of the
// retain. This /should/ be true today and will be verified as true in
// Semantic SIL.
if (isa<StrongRetainInst>(User)) {
continue;
}
// Destroys of self are tracked as a release.
//
// *NOTE* In the case of a failing initializer, the release on the exit path
// needs to cleanup the partially initialized elements.
if (isa<StrongReleaseInst>(User) || isa<DestroyValueInst>(User)) {
trackDestroy(User);
continue;
}
// Look through begin_borrow, upcast, unchecked_ref_cast
// and copy_value.
if (isa<BeginBorrowInst>(User) || isa<BeginAccessInst>(User)
|| isa<UpcastInst>(User) || isa<UncheckedRefCastInst>(User)
|| isa<CopyValueInst>(User)) {
auto value = cast<SingleValueInstruction>(User);
std::copy(value->use_begin(), value->use_end(),
std::back_inserter(Worklist));
continue;
}
// If this is an ApplyInst, check to see if this is part of a self.init
// call in a delegating initializer.
DIUseKind Kind = DIUseKind::Load;
if (isa<FullApplySite>(User) &&
(isSelfInitUse(User) || isSuperInitUse(User))) {
if (isSelfOperand(Op, User)) {
Kind = DIUseKind::SelfInit;
}
}
if (isUninitializedMetatypeInst(User))
continue;
// If this is a partial application of self, then this is an escape point
// for it.
if (auto *PAI = dyn_cast<PartialApplyInst>(User)) {
if (onlyUsedByAssignByWrapper(PAI))
continue;
Kind = DIUseKind::Escape;
}
trackUse(DIMemoryUse(User, Kind, 0, TheMemory.getNumElements()));
}
}
//===----------------------------------------------------------------------===//
// DelegatingInitUseCollector
//===----------------------------------------------------------------------===//
static void
collectDelegatingInitUses(const DIMemoryObjectInfo &TheMemory,
DIElementUseInfo &UseInfo,
SingleValueInstruction *I) {
for (auto *Op : I->getUses()) {
SILInstruction *User = Op->getUser();
// destroy_addr is a release of the entire value. This can result from an
// early release due to a conditional initializer.
if (isa<DestroyAddrInst>(User)) {
UseInfo.trackDestroy(User);
continue;
}
// For delegating initializers, we only track calls to self.init with
// specialized code. All other uses are modeled as escapes.
//
// *NOTE* This intentionally ignores all stores, which (if they got emitted
// as copyaddr or assigns) will eventually get rewritten as assignments (not
// initializations), which is the right thing to do.
DIUseKind Kind = DIUseKind::Escape;
// Stores *to* the allocation are writes. If the value being stored is a
// call to self.init()... then we have a self.init call.
if (auto *AI = dyn_cast<AssignInst>(User)) {
if (AI->getDest() == I) {
UseInfo.trackStoreToSelf(AI);
Kind = DIUseKind::InitOrAssign;
}
}
if (auto *CAI = dyn_cast<CopyAddrInst>(User)) {
if (CAI->getDest() == I) {
UseInfo.trackStoreToSelf(CAI);
Kind = DIUseKind::InitOrAssign;
}
}
// Look through begin_access
if (auto *BAI = dyn_cast<BeginAccessInst>(User)) {
collectDelegatingInitUses(TheMemory, UseInfo, BAI);
continue;
}
// Ignore end_access
if (isa<EndAccessInst>(User))
continue;
// A load of the value that's only used to handle a type(of:) query before
// self has been initialized can just use the initializer's metatype
// argument. For value types, there's no metatype subtyping to worry about,
// and for class convenience initializers, `self` notionally has the
// original Self type as its dynamic type before theoretically being
// rebound.
//
// This is necessary for source compatibility; previously, convenience
// initializers behaved like in Objective-C where the initializer received
// an uninitialized object to fill in, and type(of: self) worked by asking
// for the dynamic type of that uninitialized object.
if (isa<LoadInst>(User)) {
auto UserVal = cast<SingleValueInstruction>(User);
if (UserVal->hasOneUse()
&& isa<ValueMetatypeInst>(UserVal->getSingleUse()->get())) {
Kind = DIUseKind::LoadForTypeOfSelf;
}
}
// value_metatype may appear on a borrowed load, in which case there'll
// be an end_borrow use in addition to the value_metatype.
if (isa<LoadBorrowInst>(User)) {
auto UserVal = cast<SingleValueInstruction>(User);
bool onlyUseIsValueMetatype = false;
for (auto use : UserVal->getUses()) {
auto *user = use->getUser();
if (isa<EndBorrowInst>(user))
continue;
if (isa<ValueMetatypeInst>(user)) {
onlyUseIsValueMetatype = true;
continue;
}
onlyUseIsValueMetatype = false;
break;
}
if (onlyUseIsValueMetatype) {
Kind = DIUseKind::LoadForTypeOfSelf;
}
}
// value_metatype may also use the 'self' value directly, if it has an
// address-only type.
if (isa<ValueMetatypeInst>(User))
Kind = DIUseKind::TypeOfSelf;
// We can safely handle anything else as an escape. They should all happen
// after self.init is invoked.
UseInfo.trackUse(DIMemoryUse(User, Kind, 0, 1));
}
}
//===----------------------------------------------------------------------===//
// ClassInitElementUseCollector
//===----------------------------------------------------------------------===//
namespace {
class ClassInitElementUseCollector {
const DIMemoryObjectInfo &TheMemory;
DIElementUseInfo &UseInfo;
public:
ClassInitElementUseCollector(const DIMemoryObjectInfo &TheMemory,
DIElementUseInfo &UseInfo)
: TheMemory(TheMemory), UseInfo(UseInfo) {}
void collectClassInitSelfUses();
// *NOTE* Even though this takes a SILInstruction it actually only accepts
// load_borrow and load instructions. This is enforced via an assert.
void collectClassInitSelfLoadUses(SingleValueInstruction *MUI,
SingleValueInstruction *LI);
};
} // end anonymous namespace
/// collectDelegatingClassInitSelfUses - Collect uses of the self argument in a
/// delegating-constructor-for-a-class case.
void ClassInitElementUseCollector::collectClassInitSelfUses() {
// When we're analyzing a delegating constructor, we aren't field sensitive at
// all. Just treat all members of self as uses of the single
// non-field-sensitive value.
assert(TheMemory.getNumElements() == 1 && "delegating inits only have 1 bit");
auto *uninitMemory = TheMemory.getUninitializedValue();
// The number of stores of the initial 'self' argument into the self box
// that we saw.
unsigned StoresOfArgumentToSelf = 0;
// We walk the use chains of the self uninitMemory to find any accesses to it.
// The possible uses are:
// 1) The initialization store.
// 2) Loads of the box, which have uses of self hanging off of them.
// 3) An assign to the box, which happens at super.init.
// 4) Potential escapes after super.init, if self is closed over.
// Handle each of these in turn.
//
SmallVector<Operand *, 8> Uses(uninitMemory->getUses());
while (!Uses.empty()) {
Operand *Op = Uses.pop_back_val();
SILInstruction *User = Op->getUser();
// Ignore end_borrow. If we see an end_borrow it can only come from a
// load_borrow from ourselves.
if (isa<EndBorrowInst>(User))
continue;
// Recurse through begin_access.
if (auto *beginAccess = dyn_cast<BeginAccessInst>(User)) {
Uses.append(beginAccess->getUses().begin(), beginAccess->getUses().end());
continue;
}
if (isa<EndAccessInst>(User))
continue;
// Stores to self.
if (auto *SI = dyn_cast<StoreInst>(User)) {
if (Op->getOperandNumber() == 1) {
// A store of 'self' into the box at the start of the
// function. Ignore it.
if (auto *Arg = dyn_cast<SILArgument>(SI->getSrc())) {
if (Arg->getParent() == uninitMemory->getParent()) {
++StoresOfArgumentToSelf;
continue;
}
}
// A store of a load from the box is ignored.
//
// SILGen emits these if delegation to another initializer was
// interrupted before the initializer was called.
SILValue src = SI->getSrc();
// Look through conversions.
while (auto conversion = dyn_cast<ConversionInst>(src))
src = conversion->getConverted();
if (auto *LI = dyn_cast<LoadInst>(src))
if (LI->getOperand() == uninitMemory)
continue;
// Any other store needs to be recorded.
UseInfo.trackStoreToSelf(SI);
continue;
}
}
// For class initializers, the assign into the self box may be
// captured as SelfInit or SuperInit elsewhere.
if (isa<AssignInst>(User) &&
Op->getOperandNumber() == 1) {
// If the source of the assignment is an application of a C
// function, there is no metatype argument, so treat the
// assignment to the self box as the initialization.
if (auto *AI = dyn_cast<ApplyInst>(cast<AssignInst>(User)->getSrc())) {
if (auto *Fn = AI->getCalleeFunction()) {
if (Fn->getRepresentation() ==
SILFunctionTypeRepresentation::CFunctionPointer) {
UseInfo.trackStoreToSelf(User);
UseInfo.trackUse(DIMemoryUse(User, DIUseKind::SelfInit, 0, 1));
continue;
}
}
}
}
// Stores *to* the allocation are writes. If the value being stored is a
// call to self.init()... then we have a self.init call.
if (auto *AI = dyn_cast<AssignInst>(User)) {
if (auto *AssignSource = AI->getOperand(0)->getDefiningInstruction()) {
if (isSelfInitUse(AssignSource) || isSuperInitUse(AssignSource)) {
UseInfo.trackStoreToSelf(User);
UseInfo.trackUse(DIMemoryUse(User, DIUseKind::SelfInit, 0, 1));
continue;
}
}
if (auto *AssignSource = dyn_cast<SILArgument>(AI->getOperand(0))) {
if (AssignSource->getParent() == AI->getParent() &&
(isSelfInitUse(AssignSource) || isSuperInitUse(AssignSource))) {
UseInfo.trackStoreToSelf(User);
UseInfo.trackUse(DIMemoryUse(User, DIUseKind::SelfInit, 0, 1));
continue;
}
}
}
// Loads of the box produce self, so collect uses from them.
if (isa<LoadInst>(User) || isa<LoadBorrowInst>(User)) {
collectClassInitSelfLoadUses(uninitMemory,
cast<SingleValueInstruction>(User));
continue;
}
// destroy_addr on the box is load+release, which is treated as a release.
if (isa<DestroyAddrInst>(User)) {
UseInfo.trackDestroy(User);
continue;
}
// We can safely handle anything else as an escape. They should all happen
// after self.init is invoked.
UseInfo.trackUse(DIMemoryUse(User, DIUseKind::Escape, 0, 1));
}
assert(StoresOfArgumentToSelf == 1 &&
"The 'self' argument should have been stored into the box exactly once");
}
void ClassInitElementUseCollector::collectClassInitSelfLoadUses(
SingleValueInstruction *MUI, SingleValueInstruction *LI) {
assert(isa<ProjectBoxInst>(MUI) || isa<MarkUninitializedInst>(MUI));
assert(isa<LoadBorrowInst>(LI) || isa<LoadInst>(LI));
// If we have a load, then this is a use of the box. Look at the uses of
// the load to find out more information.
llvm::SmallVector<Operand *, 8> Worklist(LI->use_begin(), LI->use_end());
while (!Worklist.empty()) {
auto *Op = Worklist.pop_back_val();
auto *User = Op->getUser();
// Ignore any method lookup use.
if (isa<SuperMethodInst>(User) ||
isa<ObjCSuperMethodInst>(User) ||
isa<ClassMethodInst>(User) ||
isa<ObjCMethodInst>(User)) {
continue;
}
// We ignore retains of self.
if (isa<StrongRetainInst>(User))
continue;
// Ignore end_borrow.
if (isa<EndBorrowInst>(User))
continue;
// A release of a load from the self box in a class delegating
// initializer might be releasing an uninitialized self, which requires
// special processing.
if (isa<StrongReleaseInst>(User) || isa<DestroyValueInst>(User)) {
UseInfo.trackDestroy(User);
continue;
}
// Look through begin_borrow, upcast and unchecked_ref_cast.
if (isa<BeginBorrowInst>(User) ||
isa<UpcastInst>(User) ||
isa<UncheckedRefCastInst>(User)) {
auto I = cast<SingleValueInstruction>(User);
llvm::copy(I->getUses(), std::back_inserter(Worklist));
continue;
}
// We only track two kinds of uses for delegating initializers:
// calls to self.init, and "other", which we choose to model as escapes.
// This intentionally ignores all stores, which (if they got emitted as
// copyaddr or assigns) will eventually get rewritten as assignments
// (not initializations), which is the right thing to do.
DIUseKind Kind = DIUseKind::Escape;
// If this is an ApplyInst, check to see if this is part of a self.init
// call in a delegating initializer.
if (isa<FullApplySite>(User) &&
(isSelfInitUse(User) || isSuperInitUse(User))) {
if (isSelfOperand(Op, User)) {
Kind = DIUseKind::SelfInit;
}
}
// If this load's value is being stored immediately back into the delegating
// mark_uninitialized buffer, skip the use.
//
// This is to handle situations where we do not actually consume self as a
// result of situations such as:
//
// 1. The usage of a metatype to allocate the object.
//
// 2. If our self init call has a throwing function as an argument that
// actually throws.
if (auto *SI = dyn_cast<StoreInst>(User)) {
if (SI->getDest() == MUI) {
SILValue src = SI->getSrc();
// Look through conversions.
while (auto *conversion = dyn_cast<ConversionInst>(src)) {
src = conversion->getConverted();
}
if (auto *li = dyn_cast<LoadInst>(src)) {
if (li->getOperand() == MUI) {
continue;
}
}
}
}
if (isUninitializedMetatypeInst(User))
continue;
UseInfo.trackUse(DIMemoryUse(User, Kind, 0, 1));
}
}
//===----------------------------------------------------------------------===//
// Top Level Entrypoint
//===----------------------------------------------------------------------===//
static bool shouldPerformClassInitSelf(const DIMemoryObjectInfo &MemoryInfo) {
if (MemoryInfo.isDelegatingSelfAllocated())
return true;
return MemoryInfo.isNonDelegatingInit() &&
MemoryInfo.getASTType()->getClassOrBoundGenericClass() != nullptr &&
MemoryInfo.isDerivedClassSelfOnly();
}
/// Analyze all uses of the specified allocation instruction (alloc_box,
/// alloc_stack or mark_uninitialized), classifying them and storing the
/// information found into the Uses and Releases lists.
void swift::ownership::collectDIElementUsesFrom(
const DIMemoryObjectInfo &MemoryInfo, DIElementUseInfo &UseInfo) {
if (shouldPerformClassInitSelf(MemoryInfo)) {
ClassInitElementUseCollector UseCollector(MemoryInfo, UseInfo);
UseCollector.collectClassInitSelfUses();
gatherDestroysOfContainer(MemoryInfo, UseInfo);
return;
}
if (MemoryInfo.isDelegatingInit()) {
// When we're analyzing a delegating constructor, we aren't field sensitive
// at all. Just treat all members of self as uses of the single
// non-field-sensitive value.
assert(MemoryInfo.getNumElements() == 1 &&
"delegating inits only have 1 bit");
collectDelegatingInitUses(MemoryInfo, UseInfo,
MemoryInfo.getUninitializedValue());
gatherDestroysOfContainer(MemoryInfo, UseInfo);
return;
}
ElementUseCollector(MemoryInfo, UseInfo).collectFrom();
}