// A utility function for cloning the apply instruction.
static FullApplySite CloneApply(FullApplySite AI, SILBuilder &Builder) {
// Clone the Apply.
Builder.setCurrentDebugScope(AI.getDebugScope());
Builder.addOpenedArchetypeOperands(AI.getInstruction());
auto Args = AI.getArguments();
SmallVector<SILValue, 8> Ret(Args.size());
for (unsigned i = 0, e = Args.size(); i != e; ++i)
Ret[i] = Args[i];
FullApplySite NAI;
switch (AI.getInstruction()->getKind()) {
case SILInstructionKind::ApplyInst:
NAI = Builder.createApply(AI.getLoc(), AI.getCallee(),
AI.getSubstitutions(),
Ret,
cast<ApplyInst>(AI)->isNonThrowing());
break;
case SILInstructionKind::TryApplyInst: {
auto *TryApplyI = cast<TryApplyInst>(AI.getInstruction());
NAI = Builder.createTryApply(AI.getLoc(), AI.getCallee(),
AI.getSubstitutions(),
Ret,
TryApplyI->getNormalBB(),
TryApplyI->getErrorBB());
}
break;
default:
llvm_unreachable("Trying to clone an unsupported apply instruction");
}
NAI.getInstruction();
return NAI;
}
/// Attempt to devirtualize the given apply if possible, and return a
/// new instruction in that case, or nullptr otherwise.
DevirtualizationResult
swift::tryDevirtualizeApply(FullApplySite AI, ClassHierarchyAnalysis *CHA) {
DEBUG(llvm::dbgs() << " Trying to devirtualize: " << *AI.getInstruction());
// Devirtualize apply instructions that call witness_method instructions:
//
// %8 = witness_method $Optional<UInt16>, #LogicValue.boolValue!getter.1
// %9 = apply %8<Self = CodeUnit?>(%6#1) : ...
//
if (isa<WitnessMethodInst>(AI.getCallee()))
return tryDevirtualizeWitnessMethod(AI);
/// Optimize a class_method and alloc_ref pair into a direct function
/// reference:
///
/// \code
/// %XX = alloc_ref $Foo
/// %YY = class_method %XX : $Foo, #Foo.get!1 : $@convention(method)...
/// \endcode
///
/// or
///
/// %XX = metatype $...
/// %YY = class_method %XX : ...
///
/// into
///
/// %YY = function_ref @...
if (auto *CMI = dyn_cast<ClassMethodInst>(AI.getCallee())) {
auto &M = AI.getModule();
auto Instance = stripUpCasts(CMI->getOperand());
auto ClassType = Instance->getType();
if (ClassType.is<MetatypeType>())
ClassType = ClassType.getMetatypeInstanceType(M);
auto *CD = ClassType.getClassOrBoundGenericClass();
if (isEffectivelyFinalMethod(AI, ClassType, CD, CHA))
return tryDevirtualizeClassMethod(AI, Instance);
// Try to check if the exact dynamic type of the instance is statically
// known.
if (auto Instance = getInstanceWithExactDynamicType(CMI->getOperand(),
CMI->getModule(),
CHA))
return tryDevirtualizeClassMethod(AI, Instance);
}
if (isa<SuperMethodInst>(AI.getCallee())) {
if (AI.hasSelfArgument()) {
return tryDevirtualizeClassMethod(AI, AI.getSelfArgument());
}
// It is an invocation of a class method.
// Last operand is the metatype that should be used for dispatching.
return tryDevirtualizeClassMethod(AI, AI.getArguments().back());
}
return std::make_pair(nullptr, FullApplySite());
}
/// \brief Returns true, if a method implementation corresponding to
/// the class_method applied to an instance of the class CD is
/// effectively final, i.e. it is statically known to be not overridden
/// by any subclasses of the class CD.
///
/// \p AI invocation instruction
/// \p ClassType type of the instance
/// \p CD static class of the instance whose method is being invoked
/// \p CHA class hierarchy analysis
bool isEffectivelyFinalMethod(FullApplySite AI,
SILType ClassType,
ClassDecl *CD,
ClassHierarchyAnalysis *CHA) {
if (CD && CD->isFinal())
return true;
const DeclContext *DC = AI.getModule().getAssociatedContext();
// Without an associated context we cannot perform any
// access-based optimizations.
if (!DC)
return false;
auto *CMI = cast<MethodInst>(AI.getCallee());
if (!calleesAreStaticallyKnowable(AI.getModule(), CMI->getMember()))
return false;
auto *Method = CMI->getMember().getAbstractFunctionDecl();
assert(Method && "Expected abstract function decl!");
assert(!Method->isFinal() && "Unexpected indirect call to final method!");
// If this method is not overridden in the module,
// there is no other implementation.
if (!Method->isOverridden())
return true;
// Class declaration may be nullptr, e.g. for cases like:
// func foo<C:Base>(c: C) {}, where C is a class, but
// it does not have a class decl.
if (!CD)
return false;
if (!CHA)
return false;
// This is a private or a module internal class.
//
// We can analyze the class hierarchy rooted at it and
// eventually devirtualize a method call more efficiently.
ClassHierarchyAnalysis::ClassList Subs;
getAllSubclasses(CHA, CD, ClassType, AI.getModule(), Subs);
// This is the implementation of the method to be used
// if the exact class of the instance would be CD.
auto *ImplMethod = CD->findImplementingMethod(Method);
// First, analyze all direct subclasses.
for (auto S : Subs) {
// Check if the subclass overrides a method and provides
// a different implementation.
auto *ImplFD = S->findImplementingMethod(Method);
if (ImplFD != ImplMethod)
return false;
}
return true;
}
bool AliasAnalysis::canApplyDecrementRefCount(FullApplySite FAS, SILValue Ptr) {
// Treat applications of @noreturn functions as decrementing ref counts. This
// causes the apply to become a sink barrier for ref count increments.
if (FAS.getCallee().getType().getAs<SILFunctionType>()->isNoReturn())
return true;
/// If the pointer cannot escape to the function we are done.
if (!EA->canEscapeTo(Ptr, FAS))
return false;
SideEffectAnalysis::FunctionEffects ApplyEffects;
SEA->getEffects(ApplyEffects, FAS);
auto &GlobalEffects = ApplyEffects.getGlobalEffects();
if (ApplyEffects.mayReadRC() || GlobalEffects.mayRelease())
return true;
/// The function has no unidentified releases, so let's look at the arguments
// in detail.
for (unsigned Idx = 0, End = FAS.getNumArguments(); Idx < End; ++Idx) {
auto &ArgEffect = ApplyEffects.getParameterEffects()[Idx];
if (ArgEffect.mayRelease()) {
// The function may release this argument, so check if the pointer can
// escape to it.
if (EA->canEscapeToValue(Ptr, FAS.getArgument(Idx)))
return true;
}
}
return false;
}
/// \brief Check if it is possible to devirtualize an Apply instruction
/// and a class member obtained using the class_method instruction into
/// a direct call to a specific member of a specific class.
///
/// \p AI is the apply to devirtualize.
/// \p ClassOrMetatypeType is the class type or metatype type we are
/// devirtualizing for.
/// return true if it is possible to devirtualize, false - otherwise.
bool swift::canDevirtualizeClassMethod(FullApplySite AI,
SILType ClassOrMetatypeType,
OptRemark::Emitter *ORE,
bool isEffectivelyFinalMethod) {
LLVM_DEBUG(llvm::dbgs() << " Trying to devirtualize : "
<< *AI.getInstruction());
SILModule &Mod = AI.getModule();
// First attempt to lookup the origin for our class method. The origin should
// either be a metatype or an alloc_ref.
LLVM_DEBUG(llvm::dbgs() << " Origin Type: " << ClassOrMetatypeType);
auto *MI = cast<MethodInst>(AI.getCallee());
// Find the implementation of the member which should be invoked.
auto *F = getTargetClassMethod(Mod, ClassOrMetatypeType, MI);
// If we do not find any such function, we have no function to devirtualize
// to... so bail.
if (!F) {
LLVM_DEBUG(llvm::dbgs() << " FAIL: Could not find matching VTable "
"or vtable method for this class.\n");
return false;
}
// We need to disable the “effectively final” opt if a function is inlinable
if (isEffectivelyFinalMethod && AI.getFunction()->getResilienceExpansion() ==
ResilienceExpansion::Minimal) {
LLVM_DEBUG(llvm::dbgs() << " FAIL: Could not optimize function "
"because it is an effectively-final inlinable: "
<< AI.getFunction()->getName() << "\n");
return false;
}
// Mandatory inlining does class method devirtualization. I'm not sure if this
// is really needed, but some test rely on this.
// So even for Onone functions we have to do it if the SILStage is raw.
if (F->getModule().getStage() != SILStage::Raw && !F->shouldOptimize()) {
// Do not consider functions that should not be optimized.
LLVM_DEBUG(llvm::dbgs() << " FAIL: Could not optimize function "
<< " because it is marked no-opt: " << F->getName()
<< "\n");
return false;
}
if (AI.getFunction()->isSerialized()) {
// function_ref inside fragile function cannot reference a private or
// hidden symbol.
if (!F->hasValidLinkageForFragileRef())
return false;
}
return true;
}
/// Attempt to devirtualize the given apply if possible, and return a
/// new instruction in that case, or nullptr otherwise.
DevirtualizationResult swift::tryDevirtualizeApply(FullApplySite AI) {
DEBUG(llvm::dbgs() << " Trying to devirtualize: " << *AI.getInstruction());
// Devirtualize apply instructions that call witness_method instructions:
//
// %8 = witness_method $Optional<UInt16>, #LogicValue.boolValue!getter.1
// %9 = apply %8<Self = CodeUnit?>(%6#1) : ...
//
if (isa<WitnessMethodInst>(AI.getCallee()))
return tryDevirtualizeWitnessMethod(AI);
/// Optimize a class_method and alloc_ref pair into a direct function
/// reference:
///
/// \code
/// %XX = alloc_ref $Foo
/// %YY = class_method %XX : $Foo, #Foo.get!1 : $@convention(method)...
/// \endcode
///
/// or
///
/// %XX = metatype $...
/// %YY = class_method %XX : ...
///
/// into
///
/// %YY = function_ref @...
if (auto *CMI = dyn_cast<ClassMethodInst>(AI.getCallee())) {
// Check if the class member is known to be final.
if (isKnownFinal(CMI->getModule(), CMI->getMember()))
return tryDevirtualizeClassMethod(AI, CMI->getOperand());
// Try to check if the exact dynamic type of the instance is statically
// known.
if (auto Instance = getInstanceWithExactDynamicType(CMI->getOperand()))
return tryDevirtualizeClassMethod(AI, Instance);
}
return std::make_pair(nullptr, FullApplySite());
}
/// \brief Check if it is possible to devirtualize an Apply instruction
/// and a class member obtained using the class_method instruction into
/// a direct call to a specific member of a specific class.
///
/// \p AI is the apply to devirtualize.
/// \p ClassOrMetatypeType is the class type or metatype type we are
/// devirtualizing for.
/// return true if it is possible to devirtualize, false - otherwise.
bool swift::canDevirtualizeClassMethod(FullApplySite AI,
SILType ClassOrMetatypeType) {
DEBUG(llvm::dbgs() << " Trying to devirtualize : " << *AI.getInstruction());
SILModule &Mod = AI.getModule();
// First attempt to lookup the origin for our class method. The origin should
// either be a metatype or an alloc_ref.
DEBUG(llvm::dbgs() << " Origin Type: " << ClassOrMetatypeType);
auto *MI = cast<MethodInst>(AI.getCallee());
// Find the implementation of the member which should be invoked.
auto *F = getTargetClassMethod(Mod, ClassOrMetatypeType, MI);
// If we do not find any such function, we have no function to devirtualize
// to... so bail.
if (!F) {
DEBUG(llvm::dbgs() << " FAIL: Could not find matching VTable or "
"vtable method for this class.\n");
return false;
}
if (!F->shouldOptimize()) {
// Do not consider functions that should not be optimized.
DEBUG(llvm::dbgs() << " FAIL: Could not optimize function "
<< " because it is marked no-opt: " << F->getName()
<< "\n");
return false;
}
if (AI.getFunction()->isSerialized()) {
// function_ref inside fragile function cannot reference a private or
// hidden symbol.
if (!F->hasValidLinkageForFragileRef())
return false;
}
if (MI->isVolatile()) {
// dynamic dispatch is semantically required, can't devirtualize
return false;
}
return true;
}
// Start with the substitutions from the apply.
// Try to propagate them to find out the real substitutions required
// to invoke the method.
static ArrayRef<Substitution>
getSubstitutionsForCallee(SILModule &M, CanSILFunctionType GenCalleeType,
SILType ClassInstanceType, FullApplySite AI) {
// *NOTE*:
// Apply instruction substitutions are for the Member from a protocol or
// class B, where this member was first defined, before it got overridden by
// derived classes.
//
// The implementation F (the implementing method) which was found may have
// a different set of generic parameters, e.g. because it is implemented by a
// class D1 derived from B.
//
// ClassInstanceType may have a type different from both the type B
// the Member belongs to and from the ClassInstanceType, e.g. if
// ClassInstance is of a class D2, which is derived from D1, but does not
// override the Member.
//
// As a result, substitutions provided by AI are for Member, whereas
// substitutions in ClassInstanceType are for D2. And substitutions for D1
// are not available directly in a general case. Therefore, they have to
// be computed.
//
// What we know for sure:
// B is a superclass of D1
// D1 is a superclass of D2.
// D1 can be the same as D2. D1 can be the same as B.
//
// So, substitutions from AI are for class B.
// Substitutions for class D1 by means of bindSuperclass(), which starts
// with a bound type ClassInstanceType and checks its superclasses until it
// finds a bound superclass matching D1 and returns its substitutions.
// Class F belongs to.
CanType FSelfClass = GenCalleeType->getSelfParameter().getType();
SILType FSelfSubstType;
Module *Module = M.getSwiftModule();
ArrayRef<Substitution> ClassSubs;
if (GenCalleeType->isPolymorphic()) {
// Declaration of the class F belongs to.
if (auto *FSelfTypeDecl = FSelfClass.getNominalOrBoundGenericNominal()) {
// Get the unbound generic type F belongs to.
CanType FSelfGenericType =
FSelfTypeDecl->getDeclaredType()->getCanonicalType();
assert((isa<BoundGenericType>(ClassInstanceType.getSwiftRValueType()) ||
isa<NominalType>(ClassInstanceType.getSwiftRValueType())) &&
"Self type should be either a bound generic type"
"or a non-generic type");
assert((isa<UnboundGenericType>(FSelfGenericType) ||
isa<NominalType>(FSelfGenericType)) &&
"Method implementation self type should be generic");
if (isa<BoundGenericType>(ClassInstanceType.getSwiftRValueType())) {
auto BoundBaseType = bindSuperclass(FSelfGenericType,
ClassInstanceType);
if (auto BoundTy = BoundBaseType->getAs<BoundGenericType>()) {
ClassSubs = BoundTy->getSubstitutions(Module, nullptr);
}
}
}
} else {
// If the callee is not polymorphic, no substitutions are required.
return {};
}
if (ClassSubs.empty())
return AI.getSubstitutions();
auto AISubs = AI.getSubstitutions();
CanSILFunctionType AIGenCalleeType =
AI.getCallee().getType().castTo<SILFunctionType>();
CanType AISelfClass = AIGenCalleeType->getSelfParameter().getType();
unsigned NextMethodParamIdx = 0;
unsigned NumMethodParams = 0;
if (AIGenCalleeType->isPolymorphic()) {
NextMethodParamIdx = 0;
// Generic parameters of the method start after generic parameters
// of the instance class.
if (auto AISelfClassSig =
AISelfClass.getClassBound()->getGenericSignature()) {
NextMethodParamIdx = AISelfClassSig->getGenericParams().size();
}
NumMethodParams = AISubs.size() - NextMethodParamIdx;
}
unsigned NumSubs = ClassSubs.size() + NumMethodParams;
if (ClassSubs.size() == NumSubs)
return ClassSubs;
// Mix class subs with method specific subs from the AI substitutions.
// Assumptions: AI substitutions contain first the substitutions for
// a class of the method being invoked and then the substitutions
// for a method being invoked.
auto Subs = M.getASTContext().Allocate<Substitution>(NumSubs);
unsigned i = 0;
for (auto &S : ClassSubs) {
Subs[i++] = S;
}
for (; i < NumSubs; ++i, ++NextMethodParamIdx) {
Subs[i] = AISubs[NextMethodParamIdx];
}
return Subs;
}
/// \brief Inlines all mandatory inlined functions into the body of a function,
/// first recursively inlining all mandatory apply instructions in those
/// functions into their bodies if necessary.
///
/// \param F the function to be processed
/// \param AI nullptr if this is being called from the top level; the relevant
/// ApplyInst requiring the recursive call when non-null
/// \param FullyInlinedSet the set of all functions already known to be fully
/// processed, to avoid processing them over again
/// \param SetFactory an instance of ImmutableFunctionSet::Factory
/// \param CurrentInliningSet the set of functions currently being inlined in
/// the current call stack of recursive calls
///
/// \returns true if successful, false if failed due to circular inlining.
static bool
runOnFunctionRecursively(SILFunction *F, FullApplySite AI,
DenseFunctionSet &FullyInlinedSet,
ImmutableFunctionSet::Factory &SetFactory,
ImmutableFunctionSet CurrentInliningSet,
ClassHierarchyAnalysis *CHA) {
// Avoid reprocessing functions needlessly.
if (FullyInlinedSet.count(F))
return true;
// Prevent attempt to circularly inline.
if (CurrentInliningSet.contains(F)) {
// This cannot happen on a top-level call, so AI should be non-null.
assert(AI && "Cannot have circular inline without apply");
SILLocation L = AI.getLoc();
assert(L && "Must have location for transparent inline apply");
diagnose(F->getModule().getASTContext(), L.getStartSourceLoc(),
diag::circular_transparent);
return false;
}
// Add to the current inlining set (immutably, so we only affect the set
// during this call and recursive subcalls).
CurrentInliningSet = SetFactory.add(CurrentInliningSet, F);
SmallVector<std::pair<SILValue, ParameterConvention>, 16> CaptureArgs;
SmallVector<SILValue, 32> FullArgs;
for (auto BI = F->begin(), BE = F->end(); BI != BE; ++BI) {
for (auto II = BI->begin(), IE = BI->end(); II != IE; ++II) {
FullApplySite InnerAI = FullApplySite::isa(&*II);
if (!InnerAI)
continue;
auto *ApplyBlock = InnerAI.getParent();
// *NOTE* If devirtualization succeeds, sometimes II will not be InnerAI,
// but a casted result of InnerAI or even a block argument due to
// abstraction changes when calling the witness or class method. We still
// know that InnerAI dominates II though.
std::tie(InnerAI, II) = tryDevirtualizeApplyHelper(InnerAI, II, CHA);
if (!InnerAI)
continue;
SILValue CalleeValue = InnerAI.getCallee();
bool IsThick;
PartialApplyInst *PAI;
SILFunction *CalleeFunction = getCalleeFunction(
F, InnerAI, IsThick, CaptureArgs, FullArgs, PAI);
if (!CalleeFunction)
continue;
// Then recursively process it first before trying to inline it.
if (!runOnFunctionRecursively(CalleeFunction, InnerAI,
FullyInlinedSet, SetFactory,
CurrentInliningSet, CHA)) {
// If we failed due to circular inlining, then emit some notes to
// trace back the failure if we have more information.
// FIXME: possibly it could be worth recovering and attempting other
// inlines within this same recursive call rather than simply
// propagating the failure.
if (AI) {
SILLocation L = AI.getLoc();
assert(L && "Must have location for transparent inline apply");
diagnose(F->getModule().getASTContext(), L.getStartSourceLoc(),
diag::note_while_inlining);
}
return false;
}
// Get our list of substitutions.
auto Subs = (PAI
? PAI->getSubstitutionMap()
: InnerAI.getSubstitutionMap());
SILOpenedArchetypesTracker OpenedArchetypesTracker(F);
F->getModule().registerDeleteNotificationHandler(
&OpenedArchetypesTracker);
// The callee only needs to know about opened archetypes used in
// the substitution list.
OpenedArchetypesTracker.registerUsedOpenedArchetypes(
InnerAI.getInstruction());
if (PAI) {
OpenedArchetypesTracker.registerUsedOpenedArchetypes(PAI);
}
SILInliner Inliner(*F, *CalleeFunction,
SILInliner::InlineKind::MandatoryInline, Subs,
OpenedArchetypesTracker);
if (!Inliner.canInlineFunction(InnerAI)) {
// See comment above about casting when devirtualizing and how this
// sometimes causes II and InnerAI to be different and even in different
// blocks.
II = InnerAI.getInstruction()->getIterator();
continue;
}
// Inline function at I, which also changes I to refer to the first
// instruction inlined in the case that it succeeds. We purposely
// process the inlined body after inlining, because the inlining may
// have exposed new inlining opportunities beyond those present in
// the inlined function when processed independently.
LLVM_DEBUG(llvm::errs() << "Inlining @" << CalleeFunction->getName()
<< " into @" << InnerAI.getFunction()->getName()
<< "\n");
// If we intend to inline a thick function, then we need to balance the
// reference counts for correctness.
if (IsThick) {
bool IsCalleeGuaranteed =
PAI &&
PAI->getType().castTo<SILFunctionType>()->isCalleeGuaranteed();
fixupReferenceCounts(II, CalleeValue, CaptureArgs, IsCalleeGuaranteed);
}
// Decrement our iterator (carefully, to avoid going off the front) so it
// is valid after inlining is done. Inlining deletes the apply, and can
// introduce multiple new basic blocks.
II = prev_or_default(II, ApplyBlock->begin(), ApplyBlock->end());
Inliner.inlineFunction(InnerAI, FullArgs);
// We were able to inline successfully. Remove the apply.
InnerAI.getInstruction()->eraseFromParent();
// Reestablish our iterator if it wrapped.
if (II == ApplyBlock->end())
II = ApplyBlock->begin();
// Update the iterator when instructions are removed.
DeleteInstructionsHandler DeletionHandler(II);
// Now that the IR is correct, see if we can remove dead callee
// computations (e.g. dead partial_apply closures).
cleanupCalleeValue(CalleeValue, FullArgs);
// Reposition iterators possibly invalidated by mutation.
BI = SILFunction::iterator(ApplyBlock);
IE = ApplyBlock->end();
assert(BI == SILFunction::iterator(II->getParent()) &&
"Mismatch between the instruction and basic block");
++NumMandatoryInlines;
}
}
// Keep track of full inlined functions so we don't waste time recursively
// reprocessing them.
FullyInlinedSet.insert(F);
return true;
}
/// Return true if inlining this call site is profitable.
bool SILPerformanceInliner::isProfitableToInline(FullApplySite AI,
unsigned loopDepthOfAI,
DominanceAnalysis *DA,
SILLoopAnalysis *LA,
ConstantTracker &callerTracker,
unsigned &NumCallerBlocks) {
SILFunction *Callee = AI.getCalleeFunction();
if (Callee->getInlineStrategy() == AlwaysInline)
return true;
ConstantTracker constTracker(Callee, &callerTracker, AI);
DominanceInfo *DT = DA->get(Callee);
SILLoopInfo *LI = LA->get(Callee);
DominanceOrder domOrder(&Callee->front(), DT, Callee->size());
// Calculate the inlining cost of the callee.
unsigned CalleeCost = 0;
unsigned Benefit = InlineCostThreshold > 0 ? InlineCostThreshold :
RemovedCallBenefit;
Benefit += loopDepthOfAI * LoopBenefitFactor;
int testThreshold = TestThreshold;
while (SILBasicBlock *block = domOrder.getNext()) {
constTracker.beginBlock();
unsigned loopDepth = LI->getLoopDepth(block);
for (SILInstruction &I : *block) {
constTracker.trackInst(&I);
auto ICost = instructionInlineCost(I);
if (testThreshold >= 0) {
// We are in test-mode: use a simplified cost model.
CalleeCost += testCost(&I);
} else {
// Use the regular cost model.
CalleeCost += unsigned(ICost);
}
if (ApplyInst *AI = dyn_cast<ApplyInst>(&I)) {
// Check if the callee is passed as an argument. If so, increase the
// threshold, because inlining will (probably) eliminate the closure.
SILInstruction *def = constTracker.getDefInCaller(AI->getCallee());
if (def && (isa<FunctionRefInst>(def) || isa<PartialApplyInst>(def))) {
DEBUG(llvm::dbgs() << " Boost: apply const function at"
<< *AI);
Benefit += ConstCalleeBenefit + loopDepth * LoopBenefitFactor;
testThreshold *= 2;
}
}
}
// Don't count costs in blocks which are dead after inlining.
SILBasicBlock *takenBlock = getTakenBlock(block->getTerminator(),
constTracker);
if (takenBlock) {
Benefit += ConstTerminatorBenefit + TestOpt;
DEBUG(llvm::dbgs() << " Take bb" << takenBlock->getDebugID() <<
" of" << *block->getTerminator());
domOrder.pushChildrenIf(block, [=] (SILBasicBlock *child) {
return child->getSinglePredecessor() != block || child == takenBlock;
});
} else {
domOrder.pushChildren(block);
}
}
unsigned Threshold = Benefit; // The default.
if (testThreshold >= 0) {
// We are in testing mode.
Threshold = testThreshold;
} else if (AI.getFunction()->isThunk()) {
// Only inline trivial functions into thunks (which will not increase the
// code size).
Threshold = TrivialFunctionThreshold;
} else {
// The default case.
// We reduce the benefit if the caller is too large. For this we use a
// cubic function on the number of caller blocks. This starts to prevent
// inlining at about 800 - 1000 caller blocks.
unsigned blockMinus =
(NumCallerBlocks * NumCallerBlocks) / BlockLimitDenominator *
NumCallerBlocks / BlockLimitDenominator;
if (Threshold > blockMinus + TrivialFunctionThreshold)
Threshold -= blockMinus;
else
Threshold = TrivialFunctionThreshold;
}
if (CalleeCost > Threshold) {
DEBUG(llvm::dbgs() << " NO: Function too big to inline, "
"cost: " << CalleeCost << ", threshold: " << Threshold << "\n");
return false;
}
DEBUG(llvm::dbgs() << " YES: ready to inline, "
"cost: " << CalleeCost << ", threshold: " << Threshold << "\n");
NumCallerBlocks += Callee->size();
return true;
}
/// Insert monomorphic inline caches for a specific class or metatype
/// type \p SubClassTy.
static FullApplySite speculateMonomorphicTarget(FullApplySite AI,
SILType SubType,
CheckedCastBranchInst *&CCBI) {
CCBI = nullptr;
// Bail if this class_method cannot be devirtualized.
if (!canDevirtualizeClassMethod(AI, SubType))
return FullApplySite();
// Create a diamond shaped control flow and a checked_cast_branch
// instruction that checks the exact type of the object.
// This cast selects between two paths: one that calls the slow dynamic
// dispatch and one that calls the specific method.
auto It = AI.getInstruction()->getIterator();
SILFunction *F = AI.getFunction();
SILBasicBlock *Entry = AI.getParent();
// Iden is the basic block containing the direct call.
SILBasicBlock *Iden = F->createBasicBlock();
// Virt is the block containing the slow virtual call.
SILBasicBlock *Virt = F->createBasicBlock();
Iden->createBBArg(SubType);
SILBasicBlock *Continue = Entry->splitBasicBlock(It);
SILBuilderWithScope Builder(Entry, AI.getInstruction());
// Create the checked_cast_branch instruction that checks at runtime if the
// class instance is identical to the SILType.
ClassMethodInst *CMI = cast<ClassMethodInst>(AI.getCallee());
CCBI = Builder.createCheckedCastBranch(AI.getLoc(), /*exact*/ true,
CMI->getOperand(), SubType, Iden,
Virt);
It = CCBI->getIterator();
SILBuilderWithScope VirtBuilder(Virt, AI.getInstruction());
SILBuilderWithScope IdenBuilder(Iden, AI.getInstruction());
// This is the class reference downcasted into subclass SubType.
SILValue DownCastedClassInstance = Iden->getBBArg(0);
// Copy the two apply instructions into the two blocks.
FullApplySite IdenAI = CloneApply(AI, IdenBuilder);
FullApplySite VirtAI = CloneApply(AI, VirtBuilder);
// See if Continue has a release on self as the instruction right after the
// apply. If it exists, move it into position in the diamond.
if (auto *Release =
dyn_cast<StrongReleaseInst>(std::next(Continue->begin()))) {
if (Release->getOperand() == CMI->getOperand()) {
VirtBuilder.createStrongRelease(Release->getLoc(), CMI->getOperand());
IdenBuilder.createStrongRelease(Release->getLoc(),
DownCastedClassInstance);
Release->eraseFromParent();
}
}
// Create a PHInode for returning the return value from both apply
// instructions.
SILArgument *Arg = Continue->createBBArg(AI.getType());
if (!isa<TryApplyInst>(AI)) {
IdenBuilder.createBranch(AI.getLoc(), Continue,
ArrayRef<SILValue>(IdenAI.getInstruction()));
VirtBuilder.createBranch(AI.getLoc(), Continue,
ArrayRef<SILValue>(VirtAI.getInstruction()));
}
// Remove the old Apply instruction.
if (!isa<TryApplyInst>(AI))
AI.getInstruction()->replaceAllUsesWith(Arg);
auto *OriginalBB = AI.getParent();
AI.getInstruction()->eraseFromParent();
if (OriginalBB->empty())
OriginalBB->removeFromParent();
// Update the stats.
NumTargetsPredicted++;
// Devirtualize the apply instruction on the identical path.
auto NewInstPair = devirtualizeClassMethod(IdenAI, DownCastedClassInstance);
assert(NewInstPair.first && "Expected to be able to devirtualize apply!");
replaceDeadApply(IdenAI, NewInstPair.first);
// Split critical edges resulting from VirtAI.
if (auto *TAI = dyn_cast<TryApplyInst>(VirtAI)) {
auto *ErrorBB = TAI->getFunction()->createBasicBlock();
ErrorBB->createBBArg(TAI->getErrorBB()->getBBArg(0)->getType());
Builder.setInsertionPoint(ErrorBB);
Builder.createBranch(TAI->getLoc(), TAI->getErrorBB(),
{ErrorBB->getBBArg(0)});
auto *NormalBB = TAI->getFunction()->createBasicBlock();
NormalBB->createBBArg(TAI->getNormalBB()->getBBArg(0)->getType());
Builder.setInsertionPoint(NormalBB);
Builder.createBranch(TAI->getLoc(), TAI->getNormalBB(),
{NormalBB->getBBArg(0) });
Builder.setInsertionPoint(VirtAI.getInstruction());
SmallVector<SILValue, 4> Args;
for (auto Arg : VirtAI.getArguments()) {
Args.push_back(Arg);
}
FullApplySite NewVirtAI = Builder.createTryApply(VirtAI.getLoc(), VirtAI.getCallee(),
VirtAI.getSubstCalleeSILType(), VirtAI.getSubstitutions(),
Args, NormalBB, ErrorBB);
VirtAI.getInstruction()->eraseFromParent();
VirtAI = NewVirtAI;
}
return VirtAI;
}
/// \brief Inlines all mandatory inlined functions into the body of a function,
/// first recursively inlining all mandatory apply instructions in those
/// functions into their bodies if necessary.
///
/// \param F the function to be processed
/// \param AI nullptr if this is being called from the top level; the relevant
/// ApplyInst requiring the recursive call when non-null
/// \param FullyInlinedSet the set of all functions already known to be fully
/// processed, to avoid processing them over again
/// \param SetFactory an instance of ImmutableFunctionSet::Factory
/// \param CurrentInliningSet the set of functions currently being inlined in
/// the current call stack of recursive calls
///
/// \returns true if successful, false if failed due to circular inlining.
static bool
runOnFunctionRecursively(SILFunction *F, FullApplySite AI,
SILModule::LinkingMode Mode,
DenseFunctionSet &FullyInlinedSet,
ImmutableFunctionSet::Factory &SetFactory,
ImmutableFunctionSet CurrentInliningSet,
ClassHierarchyAnalysis *CHA) {
// Avoid reprocessing functions needlessly.
if (FullyInlinedSet.count(F))
return true;
// Prevent attempt to circularly inline.
if (CurrentInliningSet.contains(F)) {
// This cannot happen on a top-level call, so AI should be non-null.
assert(AI && "Cannot have circular inline without apply");
SILLocation L = AI.getLoc();
assert(L && "Must have location for transparent inline apply");
diagnose(F->getModule().getASTContext(), L.getStartSourceLoc(),
diag::circular_transparent);
return false;
}
// Add to the current inlining set (immutably, so we only affect the set
// during this call and recursive subcalls).
CurrentInliningSet = SetFactory.add(CurrentInliningSet, F);
SmallVector<SILValue, 16> CaptureArgs;
SmallVector<SILValue, 32> FullArgs;
for (auto FI = F->begin(), FE = F->end(); FI != FE; ++FI) {
for (auto I = FI->begin(), E = FI->end(); I != E; ++I) {
FullApplySite InnerAI = FullApplySite::isa(&*I);
if (!InnerAI)
continue;
auto *ApplyBlock = InnerAI.getParent();
auto NewInstPair = tryDevirtualizeApply(InnerAI, CHA);
if (auto *NewInst = NewInstPair.first) {
replaceDeadApply(InnerAI, NewInst);
if (auto *II = dyn_cast<SILInstruction>(NewInst))
I = II->getIterator();
else
I = NewInst->getParentBlock()->begin();
auto NewAI = FullApplySite::isa(NewInstPair.second.getInstruction());
if (!NewAI)
continue;
InnerAI = NewAI;
}
SILLocation Loc = InnerAI.getLoc();
SILValue CalleeValue = InnerAI.getCallee();
bool IsThick;
PartialApplyInst *PAI;
SILFunction *CalleeFunction = getCalleeFunction(InnerAI, IsThick,
CaptureArgs, FullArgs,
PAI,
Mode);
if (!CalleeFunction ||
CalleeFunction->isTransparent() == IsNotTransparent)
continue;
if (F->isFragile() &&
!CalleeFunction->hasValidLinkageForFragileRef()) {
if (!CalleeFunction->hasValidLinkageForFragileInline()) {
llvm::errs() << "caller: " << F->getName() << "\n";
llvm::errs() << "callee: " << CalleeFunction->getName() << "\n";
llvm_unreachable("Should never be inlining a resilient function into "
"a fragile function");
}
continue;
}
// Then recursively process it first before trying to inline it.
if (!runOnFunctionRecursively(CalleeFunction, InnerAI, Mode,
FullyInlinedSet, SetFactory,
CurrentInliningSet, CHA)) {
// If we failed due to circular inlining, then emit some notes to
// trace back the failure if we have more information.
// FIXME: possibly it could be worth recovering and attempting other
// inlines within this same recursive call rather than simply
// propagating the failure.
if (AI) {
SILLocation L = AI.getLoc();
assert(L && "Must have location for transparent inline apply");
diagnose(F->getModule().getASTContext(), L.getStartSourceLoc(),
diag::note_while_inlining);
}
return false;
}
// Inline function at I, which also changes I to refer to the first
// instruction inlined in the case that it succeeds. We purposely
// process the inlined body after inlining, because the inlining may
// have exposed new inlining opportunities beyond those present in
// the inlined function when processed independently.
DEBUG(llvm::errs() << "Inlining @" << CalleeFunction->getName()
<< " into @" << InnerAI.getFunction()->getName()
<< "\n");
// If we intend to inline a thick function, then we need to balance the
// reference counts for correctness.
if (IsThick && I != ApplyBlock->begin()) {
// We need to find an appropriate location for our fix up code
// We used to do this after inlining Without any modifications
// This caused us to add a release in a wrong place:
// It would release a value *before* retaining it!
// It is really problematic to do this after inlining -
// Finding a valid insertion point is tricky:
// Inlining might add new basic blocks and/or remove the apply
// We want to add the fix up *just before* where the current apply is!
// Unfortunately, we *can't* add the fix up code here:
// Inlining might fail for any reason -
// If that occurred we'd need to undo our fix up code.
// Instead, we split the current basic block -
// Making sure we have a basic block that starts with our apply.
SILBuilderWithScope B(I);
ApplyBlock = splitBasicBlockAndBranch(B, &*I, nullptr, nullptr);
I = ApplyBlock->begin();
}
// Decrement our iterator (carefully, to avoid going off the front) so it
// is valid after inlining is done. Inlining deletes the apply, and can
// introduce multiple new basic blocks.
if (I != ApplyBlock->begin())
--I;
else
I = ApplyBlock->end();
std::vector<Substitution> ApplySubs(InnerAI.getSubstitutions());
if (PAI) {
auto PAISubs = PAI->getSubstitutions();
ApplySubs.insert(ApplySubs.end(), PAISubs.begin(), PAISubs.end());
}
SILOpenedArchetypesTracker OpenedArchetypesTracker(*F);
F->getModule().registerDeleteNotificationHandler(
&OpenedArchetypesTracker);
// The callee only needs to know about opened archetypes used in
// the substitution list.
OpenedArchetypesTracker.registerUsedOpenedArchetypes(InnerAI.getInstruction());
if (PAI) {
OpenedArchetypesTracker.registerUsedOpenedArchetypes(PAI);
}
SILInliner Inliner(*F, *CalleeFunction,
SILInliner::InlineKind::MandatoryInline,
ApplySubs, OpenedArchetypesTracker);
if (!Inliner.inlineFunction(InnerAI, FullArgs)) {
I = InnerAI.getInstruction()->getIterator();
continue;
}
// Inlining was successful. Remove the apply.
InnerAI.getInstruction()->eraseFromParent();
// Reestablish our iterator if it wrapped.
if (I == ApplyBlock->end())
I = ApplyBlock->begin();
// Update the iterator when instructions are removed.
DeleteInstructionsHandler DeletionHandler(I);
// If the inlined apply was a thick function, then we need to balance the
// reference counts for correctness.
if (IsThick)
fixupReferenceCounts(I, Loc, CalleeValue, CaptureArgs);
// Now that the IR is correct, see if we can remove dead callee
// computations (e.g. dead partial_apply closures).
cleanupCalleeValue(CalleeValue, CaptureArgs, FullArgs);
// Reposition iterators possibly invalidated by mutation.
FI = SILFunction::iterator(ApplyBlock);
E = ApplyBlock->end();
assert(FI == SILFunction::iterator(I->getParent()) &&
"Mismatch between the instruction and basic block");
++NumMandatoryInlines;
}
}
// Keep track of full inlined functions so we don't waste time recursively
// reprocessing them.
FullyInlinedSet.insert(F);
return true;
}
/// \brief Inlines all mandatory inlined functions into the body of a function,
/// first recursively inlining all mandatory apply instructions in those
/// functions into their bodies if necessary.
///
/// \param F the function to be processed
/// \param AI nullptr if this is being called from the top level; the relevant
/// ApplyInst requiring the recursive call when non-null
/// \param FullyInlinedSet the set of all functions already known to be fully
/// processed, to avoid processing them over again
/// \param SetFactory an instance of ImmutableFunctionSet::Factory
/// \param CurrentInliningSet the set of functions currently being inlined in
/// the current call stack of recursive calls
///
/// \returns true if successful, false if failed due to circular inlining.
static bool
runOnFunctionRecursively(SILFunction *F, FullApplySite AI,
SILModule::LinkingMode Mode,
DenseFunctionSet &FullyInlinedSet,
ImmutableFunctionSet::Factory &SetFactory,
ImmutableFunctionSet CurrentInliningSet,
ClassHierarchyAnalysis *CHA) {
// Avoid reprocessing functions needlessly.
if (FullyInlinedSet.count(F))
return true;
// Prevent attempt to circularly inline.
if (CurrentInliningSet.contains(F)) {
// This cannot happen on a top-level call, so AI should be non-null.
assert(AI && "Cannot have circular inline without apply");
SILLocation L = AI.getLoc();
assert(L && "Must have location for transparent inline apply");
diagnose(F->getModule().getASTContext(), L.getStartSourceLoc(),
diag::circular_transparent);
return false;
}
// Add to the current inlining set (immutably, so we only affect the set
// during this call and recursive subcalls).
CurrentInliningSet = SetFactory.add(CurrentInliningSet, F);
SmallVector<SILValue, 16> CaptureArgs;
SmallVector<SILValue, 32> FullArgs;
for (auto FI = F->begin(), FE = F->end(); FI != FE; ++FI) {
for (auto I = FI->begin(), E = FI->end(); I != E; ++I) {
FullApplySite InnerAI = FullApplySite::isa(&*I);
if (!InnerAI)
continue;
auto *ApplyBlock = InnerAI.getParent();
auto NewInstPair = tryDevirtualizeApply(InnerAI, CHA);
if (auto *NewInst = NewInstPair.first) {
replaceDeadApply(InnerAI, NewInst);
if (auto *II = dyn_cast<SILInstruction>(NewInst))
I = II->getIterator();
else
I = NewInst->getParentBB()->begin();
auto NewAI = FullApplySite::isa(NewInstPair.second.getInstruction());
if (!NewAI)
continue;
InnerAI = NewAI;
}
SILLocation Loc = InnerAI.getLoc();
SILValue CalleeValue = InnerAI.getCallee();
bool IsThick;
PartialApplyInst *PAI;
SILFunction *CalleeFunction = getCalleeFunction(InnerAI, IsThick,
CaptureArgs, FullArgs,
PAI,
Mode);
if (!CalleeFunction ||
CalleeFunction->isTransparent() == IsNotTransparent)
continue;
// Then recursively process it first before trying to inline it.
if (!runOnFunctionRecursively(CalleeFunction, InnerAI, Mode,
FullyInlinedSet, SetFactory,
CurrentInliningSet, CHA)) {
// If we failed due to circular inlining, then emit some notes to
// trace back the failure if we have more information.
// FIXME: possibly it could be worth recovering and attempting other
// inlines within this same recursive call rather than simply
// propagating the failure.
if (AI) {
SILLocation L = AI.getLoc();
assert(L && "Must have location for transparent inline apply");
diagnose(F->getModule().getASTContext(), L.getStartSourceLoc(),
diag::note_while_inlining);
}
return false;
}
// Inline function at I, which also changes I to refer to the first
// instruction inlined in the case that it succeeds. We purposely
// process the inlined body after inlining, because the inlining may
// have exposed new inlining opportunities beyond those present in
// the inlined function when processed independently.
DEBUG(llvm::errs() << "Inlining @" << CalleeFunction->getName()
<< " into @" << InnerAI.getFunction()->getName()
<< "\n");
// Decrement our iterator (carefully, to avoid going off the front) so it
// is valid after inlining is done. Inlining deletes the apply, and can
// introduce multiple new basic blocks.
if (I != ApplyBlock->begin())
--I;
else
I = ApplyBlock->end();
TypeSubstitutionMap ContextSubs;
std::vector<Substitution> ApplySubs(InnerAI.getSubstitutions());
if (PAI) {
auto PAISubs = PAI->getSubstitutions();
ApplySubs.insert(ApplySubs.end(), PAISubs.begin(), PAISubs.end());
}
ContextSubs.copyFrom(CalleeFunction->getContextGenericParams()
->getSubstitutionMap(ApplySubs));
SILInliner Inliner(*F, *CalleeFunction,
SILInliner::InlineKind::MandatoryInline,
ContextSubs, ApplySubs);
if (!Inliner.inlineFunction(InnerAI, FullArgs)) {
I = InnerAI.getInstruction()->getIterator();
continue;
}
// Inlining was successful. Remove the apply.
InnerAI.getInstruction()->eraseFromParent();
// Reestablish our iterator if it wrapped.
if (I == ApplyBlock->end())
I = ApplyBlock->begin();
else
++I;
// If the inlined apply was a thick function, then we need to balance the
// reference counts for correctness.
if (IsThick)
fixupReferenceCounts(I, Loc, CalleeValue, CaptureArgs);
// Now that the IR is correct, see if we can remove dead callee
// computations (e.g. dead partial_apply closures).
cleanupCalleeValue(CalleeValue, CaptureArgs, FullArgs);
// Reposition iterators possibly invalidated by mutation.
FI = SILFunction::iterator(ApplyBlock);
I = ApplyBlock->begin();
E = ApplyBlock->end();
++NumMandatoryInlines;
}
}
// Keep track of full inlined functions so we don't waste time recursively
// reprocessing them.
FullyInlinedSet.insert(F);
return true;
}
/// \brief Check if it is possible to devirtualize an Apply instruction
/// and a class member obtained using the class_method instruction into
/// a direct call to a specific member of a specific class.
///
/// \p AI is the apply to devirtualize.
/// \p ClassOrMetatypeType is the class type or metatype type we are
/// devirtualizing for.
/// return true if it is possible to devirtualize, false - otherwise.
bool swift::canDevirtualizeClassMethod(FullApplySite AI,
SILType ClassOrMetatypeType) {
DEBUG(llvm::dbgs() << " Trying to devirtualize : " << *AI.getInstruction());
SILModule &Mod = AI.getModule();
// Bail if any generic types parameters of the class instance type are
// unbound.
// We cannot devirtualize unbound generic calls yet.
if (isClassWithUnboundGenericParameters(ClassOrMetatypeType, Mod))
return false;
// First attempt to lookup the origin for our class method. The origin should
// either be a metatype or an alloc_ref.
DEBUG(llvm::dbgs() << " Origin Type: " << ClassOrMetatypeType);
auto *CMI = cast<ClassMethodInst>(AI.getCallee());
// Find the implementation of the member which should be invoked.
auto *F = getTargetClassMethod(Mod, ClassOrMetatypeType, CMI->getMember());
// If we do not find any such function, we have no function to devirtualize
// to... so bail.
if (!F) {
DEBUG(llvm::dbgs() << " FAIL: Could not find matching VTable or "
"vtable method for this class.\n");
return false;
}
if (AI.getFunction()->isFragile()) {
// function_ref inside fragile function cannot reference a private or
// hidden symbol.
if (!(F->isFragile() || isValidLinkageForFragileRef(F->getLinkage()) ||
F->isExternalDeclaration()))
return false;
}
CanSILFunctionType GenCalleeType = F->getLoweredFunctionType();
auto Subs = getSubstitutionsForCallee(Mod, GenCalleeType,
ClassOrMetatypeType, AI);
// For polymorphic functions, bail if the number of substitutions is
// not the same as the number of expected generic parameters.
if (GenCalleeType->isPolymorphic()) {
auto GenericSig = GenCalleeType->getGenericSignature();
// Get the number of expected generic parameters, which
// is a sum of the number of explicit generic parameters
// and the number of their recursive member types exposed
// through protocol requirements.
auto DepTypes = GenericSig->getAllDependentTypes();
unsigned ExpectedGenParamsNum = 0;
for (auto DT: DepTypes) {
(void)DT;
ExpectedGenParamsNum++;
}
if (ExpectedGenParamsNum != Subs.size())
return false;
}
// Check if the optimizer knows how to cast the return type.
CanSILFunctionType SubstCalleeType = GenCalleeType;
if (GenCalleeType->isPolymorphic())
SubstCalleeType =
GenCalleeType->substGenericArgs(Mod, Mod.getSwiftModule(), Subs);
// If we have a direct return type, make sure we use the subst callee return
// type. If we have an indirect return type, AI's return type of the empty
// tuple should be ok.
SILType ReturnType = AI.getType();
if (!SubstCalleeType->hasIndirectResult()) {
ReturnType = SubstCalleeType->getSILResult();
}
if (!canCastValueToABICompatibleType(Mod, ReturnType, AI.getType()))
return false;
return true;
}
/// \brief Devirtualize an apply of a class method.
///
/// \p AI is the apply to devirtualize.
/// \p ClassOrMetatype is a class value or metatype value that is the
/// self argument of the apply we will devirtualize.
/// return the result value of the new ApplyInst if created one or null.
FullApplySite swift::devirtualizeClassMethod(FullApplySite AI,
SILValue ClassOrMetatype,
OptRemark::Emitter *ORE) {
LLVM_DEBUG(llvm::dbgs() << " Trying to devirtualize : "
<< *AI.getInstruction());
SILModule &Mod = AI.getModule();
auto *MI = cast<MethodInst>(AI.getCallee());
auto ClassOrMetatypeType = ClassOrMetatype->getType();
auto *F = getTargetClassMethod(Mod, ClassOrMetatypeType, MI);
CanSILFunctionType GenCalleeType = F->getLoweredFunctionType();
SubstitutionMap Subs =
getSubstitutionsForCallee(Mod, GenCalleeType,
ClassOrMetatypeType.getASTType(),
AI);
CanSILFunctionType SubstCalleeType = GenCalleeType;
if (GenCalleeType->isPolymorphic())
SubstCalleeType = GenCalleeType->substGenericArgs(Mod, Subs);
SILFunctionConventions substConv(SubstCalleeType, Mod);
SILBuilderWithScope B(AI.getInstruction());
SILLocation Loc = AI.getLoc();
FunctionRefInst *FRI = B.createFunctionRef(Loc, F);
// Create the argument list for the new apply, casting when needed
// in order to handle covariant indirect return types and
// contravariant argument types.
llvm::SmallVector<SILValue, 8> NewArgs;
auto IndirectResultArgIter = AI.getIndirectSILResults().begin();
for (auto ResultTy : substConv.getIndirectSILResultTypes()) {
NewArgs.push_back(
castValueToABICompatibleType(&B, Loc, *IndirectResultArgIter,
IndirectResultArgIter->getType(), ResultTy));
++IndirectResultArgIter;
}
auto ParamArgIter = AI.getArgumentsWithoutIndirectResults().begin();
// Skip the last parameter, which is `self`. Add it below.
for (auto param : substConv.getParameters().drop_back()) {
auto paramType = substConv.getSILType(param);
NewArgs.push_back(
castValueToABICompatibleType(&B, Loc, *ParamArgIter,
ParamArgIter->getType(), paramType));
++ParamArgIter;
}
// Add the self argument, upcasting if required because we're
// calling a base class's method.
auto SelfParamTy = substConv.getSILType(SubstCalleeType->getSelfParameter());
NewArgs.push_back(castValueToABICompatibleType(&B, Loc,
ClassOrMetatype,
ClassOrMetatypeType,
SelfParamTy));
ApplySite NewAS = replaceApplySite(B, Loc, AI, FRI, Subs, NewArgs, substConv);
FullApplySite NewAI = FullApplySite::isa(NewAS.getInstruction());
assert(NewAI);
LLVM_DEBUG(llvm::dbgs() << " SUCCESS: " << F->getName() << "\n");
if (ORE)
ORE->emit([&]() {
using namespace OptRemark;
return RemarkPassed("ClassMethodDevirtualized", *AI.getInstruction())
<< "Devirtualized call to class method " << NV("Method", F);
});
NumClassDevirt++;
return NewAI;
}
/// Attempt to devirtualize the given apply if possible, and return a
/// new instruction in that case, or nullptr otherwise.
ApplySite swift::tryDevirtualizeApply(ApplySite AI,
ClassHierarchyAnalysis *CHA,
OptRemark::Emitter *ORE) {
LLVM_DEBUG(llvm::dbgs() << " Trying to devirtualize: "
<< *AI.getInstruction());
// Devirtualize apply instructions that call witness_method instructions:
//
// %8 = witness_method $Optional<UInt16>, #LogicValue.boolValue!getter.1
// %9 = apply %8<Self = CodeUnit?>(%6#1) : ...
//
if (isa<WitnessMethodInst>(AI.getCallee()))
return tryDevirtualizeWitnessMethod(AI, ORE);
// TODO: check if we can also de-virtualize partial applies of class methods.
FullApplySite FAS = FullApplySite::isa(AI.getInstruction());
if (!FAS)
return ApplySite();
/// Optimize a class_method and alloc_ref pair into a direct function
/// reference:
///
/// \code
/// %XX = alloc_ref $Foo
/// %YY = class_method %XX : $Foo, #Foo.get!1 : $@convention(method)...
/// \endcode
///
/// or
///
/// %XX = metatype $...
/// %YY = class_method %XX : ...
///
/// into
///
/// %YY = function_ref @...
if (auto *CMI = dyn_cast<ClassMethodInst>(FAS.getCallee())) {
auto &M = FAS.getModule();
auto Instance = stripUpCasts(CMI->getOperand());
auto ClassType = Instance->getType();
if (ClassType.is<MetatypeType>())
ClassType = ClassType.getMetatypeInstanceType(M);
auto *CD = ClassType.getClassOrBoundGenericClass();
if (isEffectivelyFinalMethod(FAS, ClassType, CD, CHA))
return tryDevirtualizeClassMethod(FAS, Instance, ORE,
true /*isEffectivelyFinalMethod*/);
// Try to check if the exact dynamic type of the instance is statically
// known.
if (auto Instance = getInstanceWithExactDynamicType(CMI->getOperand(),
CMI->getModule(),
CHA))
return tryDevirtualizeClassMethod(FAS, Instance, ORE);
if (auto ExactTy = getExactDynamicType(CMI->getOperand(), CMI->getModule(),
CHA)) {
if (ExactTy == CMI->getOperand()->getType())
return tryDevirtualizeClassMethod(FAS, CMI->getOperand(), ORE);
}
}
if (isa<SuperMethodInst>(FAS.getCallee())) {
if (FAS.hasSelfArgument()) {
return tryDevirtualizeClassMethod(FAS, FAS.getSelfArgument(), ORE);
}
// It is an invocation of a class method.
// Last operand is the metatype that should be used for dispatching.
return tryDevirtualizeClassMethod(FAS, FAS.getArguments().back(), ORE);
}
return ApplySite();
}
bool SILPerformanceInliner::isProfitableToInline(FullApplySite AI,
Weight CallerWeight,
ConstantTracker &callerTracker,
int &NumCallerBlocks,
bool IsGeneric) {
SILFunction *Callee = AI.getReferencedFunction();
SILLoopInfo *LI = LA->get(Callee);
ShortestPathAnalysis *SPA = getSPA(Callee, LI);
assert(SPA->isValid());
ConstantTracker constTracker(Callee, &callerTracker, AI);
DominanceInfo *DT = DA->get(Callee);
SILBasicBlock *CalleeEntry = &Callee->front();
DominanceOrder domOrder(CalleeEntry, DT, Callee->size());
// Calculate the inlining cost of the callee.
int CalleeCost = 0;
int Benefit = 0;
// Start with a base benefit.
int BaseBenefit = RemovedCallBenefit;
const SILOptions &Opts = Callee->getModule().getOptions();
// For some reason -Ounchecked can accept a higher base benefit without
// increasing the code size too much.
if (Opts.Optimization == SILOptions::SILOptMode::OptimizeUnchecked)
BaseBenefit *= 2;
CallerWeight.updateBenefit(Benefit, BaseBenefit);
// Go through all blocks of the function, accumulate the cost and find
// benefits.
while (SILBasicBlock *block = domOrder.getNext()) {
constTracker.beginBlock();
Weight BlockW = SPA->getWeight(block, CallerWeight);
for (SILInstruction &I : *block) {
constTracker.trackInst(&I);
CalleeCost += (int)instructionInlineCost(I);
if (FullApplySite AI = FullApplySite::isa(&I)) {
// Check if the callee is passed as an argument. If so, increase the
// threshold, because inlining will (probably) eliminate the closure.
SILInstruction *def = constTracker.getDefInCaller(AI.getCallee());
if (def && (isa<FunctionRefInst>(def) || isa<PartialApplyInst>(def)))
BlockW.updateBenefit(Benefit, RemovedClosureBenefit);
} else if (auto *LI = dyn_cast<LoadInst>(&I)) {
// Check if it's a load from a stack location in the caller. Such a load
// might be optimized away if inlined.
if (constTracker.isStackAddrInCaller(LI->getOperand()))
BlockW.updateBenefit(Benefit, RemovedLoadBenefit);
} else if (auto *SI = dyn_cast<StoreInst>(&I)) {
// Check if it's a store to a stack location in the caller. Such a load
// might be optimized away if inlined.
if (constTracker.isStackAddrInCaller(SI->getDest()))
BlockW.updateBenefit(Benefit, RemovedStoreBenefit);
} else if (isa<StrongReleaseInst>(&I) || isa<ReleaseValueInst>(&I)) {
SILValue Op = stripCasts(I.getOperand(0));
if (SILArgument *Arg = dyn_cast<SILArgument>(Op)) {
if (Arg->isFunctionArg() && Arg->getArgumentConvention() ==
SILArgumentConvention::Direct_Guaranteed) {
BlockW.updateBenefit(Benefit, RefCountBenefit);
}
}
} else if (auto *BI = dyn_cast<BuiltinInst>(&I)) {
if (BI->getBuiltinInfo().ID == BuiltinValueKind::OnFastPath)
BlockW.updateBenefit(Benefit, FastPathBuiltinBenefit);
}
}
// Don't count costs in blocks which are dead after inlining.
SILBasicBlock *takenBlock = constTracker.getTakenBlock(block->getTerminator());
if (takenBlock) {
BlockW.updateBenefit(Benefit, RemovedTerminatorBenefit);
domOrder.pushChildrenIf(block, [=] (SILBasicBlock *child) {
return child->getSinglePredecessor() != block || child == takenBlock;
});
} else {
domOrder.pushChildren(block);
}
}
if (AI.getFunction()->isThunk()) {
// Only inline trivial functions into thunks (which will not increase the
// code size).
if (CalleeCost > TrivialFunctionThreshold)
return false;
DEBUG(
dumpCaller(AI.getFunction());
llvm::dbgs() << " decision {" << CalleeCost << " into thunk} " <<
Callee->getName() << '\n';
);
return true;
}
/// \brief Devirtualize an apply of a class method.
///
/// \p AI is the apply to devirtualize.
/// \p ClassOrMetatype is a class value or metatype value that is the
/// self argument of the apply we will devirtualize.
/// return the result value of the new ApplyInst if created one or null.
DevirtualizationResult swift::devirtualizeClassMethod(FullApplySite AI,
SILValue ClassOrMetatype) {
DEBUG(llvm::dbgs() << " Trying to devirtualize : " << *AI.getInstruction());
SILModule &Mod = AI.getModule();
auto *CMI = cast<ClassMethodInst>(AI.getCallee());
auto ClassOrMetatypeType = ClassOrMetatype.getType();
auto *F = getTargetClassMethod(Mod, ClassOrMetatypeType, CMI->getMember());
CanSILFunctionType GenCalleeType = F->getLoweredFunctionType();
auto Subs = getSubstitutionsForCallee(Mod, GenCalleeType,
ClassOrMetatypeType, AI);
CanSILFunctionType SubstCalleeType = GenCalleeType;
if (GenCalleeType->isPolymorphic())
SubstCalleeType = GenCalleeType->substGenericArgs(Mod, Mod.getSwiftModule(), Subs);
SILBuilderWithScope B(AI.getInstruction());
FunctionRefInst *FRI = B.createFunctionRef(AI.getLoc(), F);
// Create the argument list for the new apply, casting when needed
// in order to handle covariant indirect return types and
// contravariant argument types.
llvm::SmallVector<SILValue, 8> NewArgs;
auto Args = AI.getArguments();
auto ParamTypes = SubstCalleeType->getParameterSILTypes();
for (unsigned i = 0, e = Args.size() - 1; i != e; ++i)
NewArgs.push_back(castValueToABICompatibleType(&B, AI.getLoc(), Args[i],
Args[i].getType(),
ParamTypes[i]).getValue());
// Add the self argument, upcasting if required because we're
// calling a base class's method.
auto SelfParamTy = SubstCalleeType->getSelfParameter().getSILType();
NewArgs.push_back(castValueToABICompatibleType(&B, AI.getLoc(),
ClassOrMetatype,
ClassOrMetatypeType,
SelfParamTy).getValue());
// If we have a direct return type, make sure we use the subst callee return
// type. If we have an indirect return type, AI's return type of the empty
// tuple should be ok.
SILType ResultTy = AI.getType();
if (!SubstCalleeType->hasIndirectResult()) {
ResultTy = SubstCalleeType->getSILResult();
}
SILType SubstCalleeSILType =
SILType::getPrimitiveObjectType(SubstCalleeType);
FullApplySite NewAI;
SILBasicBlock *ResultBB = nullptr;
SILBasicBlock *NormalBB = nullptr;
SILValue ResultValue;
bool ResultCastRequired = false;
SmallVector<Operand *, 4> OriginalResultUses;
if (!isa<TryApplyInst>(AI)) {
NewAI = B.createApply(AI.getLoc(), FRI, SubstCalleeSILType, ResultTy,
Subs, NewArgs, cast<ApplyInst>(AI)->isNonThrowing());
ResultValue = SILValue(NewAI.getInstruction(), 0);
} else {
auto *TAI = cast<TryApplyInst>(AI);
// Create new normal and error BBs only if:
// - re-using a BB would create a critical edge
// - or, the result of the new apply would be of different
// type than the argument of the original normal BB.
if (TAI->getNormalBB()->getSinglePredecessor())
ResultBB = TAI->getNormalBB();
else {
ResultBB = B.getFunction().createBasicBlock();
ResultBB->createBBArg(ResultTy);
}
NormalBB = TAI->getNormalBB();
SILBasicBlock *ErrorBB = nullptr;
if (TAI->getErrorBB()->getSinglePredecessor())
ErrorBB = TAI->getErrorBB();
else {
ErrorBB = B.getFunction().createBasicBlock();
ErrorBB->createBBArg(TAI->getErrorBB()->getBBArg(0)->getType());
}
NewAI = B.createTryApply(AI.getLoc(), FRI, SubstCalleeSILType,
Subs, NewArgs,
ResultBB, ErrorBB);
if (ErrorBB != TAI->getErrorBB()) {
B.setInsertionPoint(ErrorBB);
B.createBranch(TAI->getLoc(), TAI->getErrorBB(),
{ErrorBB->getBBArg(0)});
}
// Does the result value need to be casted?
ResultCastRequired = ResultTy != NormalBB->getBBArg(0)->getType();
if (ResultBB != NormalBB)
B.setInsertionPoint(ResultBB);
else if (ResultCastRequired) {
B.setInsertionPoint(NormalBB->begin());
// Collect all uses, before casting.
for (auto *Use : NormalBB->getBBArg(0)->getUses()) {
OriginalResultUses.push_back(Use);
}
NormalBB->getBBArg(0)->replaceAllUsesWith(SILUndef::get(AI.getType(), Mod));
NormalBB->replaceBBArg(0, ResultTy, nullptr);
}
// The result value is passed as a parameter to the normal block.
ResultValue = ResultBB->getBBArg(0);
}
// Check if any casting is required for the return value.
ResultValue = castValueToABICompatibleType(&B, NewAI.getLoc(), ResultValue,
ResultTy, AI.getType()).getValue();
DEBUG(llvm::dbgs() << " SUCCESS: " << F->getName() << "\n");
NumClassDevirt++;
if (NormalBB) {
if (NormalBB != ResultBB) {
// If artificial normal BB was introduced, branch
// to the original normal BB.
B.createBranch(NewAI.getLoc(), NormalBB, { ResultValue });
} else if (ResultCastRequired) {
// Update all original uses by the new value.
for(auto *Use: OriginalResultUses) {
Use->set(ResultValue);
}
}
return std::make_pair(NewAI.getInstruction(), NewAI);
}
// We need to return a pair of values here:
// - the first one is the actual result of the devirtualized call, possibly
// casted into an appropriate type. This SILValue may be a BB arg, if it
// was a cast between optional types.
// - the second one is the new apply site.
return std::make_pair(ResultValue.getDef(), NewAI);
}
/// \brief Returns true, if a method implementation to be called by the
/// default case handler of a speculative devirtualization is statically
/// known. This happens if it can be proven that generated
/// checked_cast_br instructions cover all other possible cases.
///
/// \p CHA class hierarchy analysis to be used
/// \p AI invocation instruction
/// \p CD static class of the instance whose method is being invoked
/// \p Subs set of direct subclasses of this class
static bool isDefaultCaseKnown(ClassHierarchyAnalysis *CHA,
FullApplySite AI,
ClassDecl *CD,
ClassHierarchyAnalysis::ClassList &Subs) {
ClassMethodInst *CMI = cast<ClassMethodInst>(AI.getCallee());
auto *Method = CMI->getMember().getFuncDecl();
const DeclContext *DC = AI.getModule().getAssociatedContext();
if (CD->isFinal())
return true;
// Without an associated context we cannot perform any
// access-based optimizations.
if (!DC)
return false;
// Only handle classes defined within the SILModule's associated context.
if (!CD->isChildContextOf(DC))
return false;
if (!CD->hasAccessibility())
return false;
// Only consider 'private' members, unless we are in whole-module compilation.
switch (CD->getEffectiveAccess()) {
case Accessibility::Public:
return false;
case Accessibility::Internal:
if (!AI.getModule().isWholeModule())
return false;
break;
case Accessibility::Private:
break;
}
// This is a private or a module internal class.
//
// We can analyze the class hierarchy rooted at it and
// eventually devirtualize a method call more efficiently.
// First, analyze all direct subclasses.
// We know that a dedicated checked_cast_br check is
// generated for each direct subclass by tryToSpeculateTarget.
for (auto S : Subs) {
// Check if the subclass overrides a method
auto *FD = S->findOverridingDecl(Method);
if (!FD)
continue;
if (CHA->hasKnownDirectSubclasses(S)) {
// This subclass has its own subclasses and
// they will use this implementation or provide
// their own. In either case it is not covered by
// checked_cast_br instructions generated by
// tryToSpeculateTarget. Therefore it increases
// the number of remaining cases to be handled
// by the default case handler.
return false;
}
}
// Then, analyze indirect subclasses.
// Set of indirect subclasses for the class.
auto &IndirectSubs = CHA->getIndirectSubClasses(CD);
// Check if any indirect subclasses use an implementation
// of the method different from the implementation in
// the current class. If this is the case, then such
// an indirect subclass would need a dedicated
// checked_cast_br check to be devirtualized. But this is
// not done by tryToSpeculateTarget yet and therefore
// such a subclass should be handled by the "default"
// case handler, which essentially means that "default"
// case cannot be devirtualized since it covers more
// then one alternative.
for (auto S : IndirectSubs) {
auto *ImplFD = S->findImplementingMethod(Method);
if (ImplFD != Method) {
// Different implementation is used by a subclass.
// Therefore, the default case is not known.
return false;
}
}
return true;
}
// Return the list of functions that can be called via the given apply
// site.
CalleeList CalleeCache::getCalleeList(FullApplySite FAS) const {
return getCalleeListForCalleeKind(FAS.getCallee());
}
/// \brief Try to speculate the call target for the call \p AI. This function
/// returns true if a change was made.
static bool tryToSpeculateTarget(FullApplySite AI,
ClassHierarchyAnalysis *CHA) {
ClassMethodInst *CMI = cast<ClassMethodInst>(AI.getCallee());
// We cannot devirtualize in cases where dynamic calls are
// semantically required.
if (CMI->isVolatile())
return false;
// Strip any upcasts off of our 'self' value, potentially leaving us
// with a value whose type is closer (in the class hierarchy) to the
// actual dynamic type.
auto SubTypeValue = CMI->getOperand().stripUpCasts();
SILType SubType = SubTypeValue.getType();
// Bail if any generic types parameters of the class instance type are
// unbound.
// We cannot devirtualize unbound generic calls yet.
if (isNominalTypeWithUnboundGenericParameters(SubType, AI.getModule()))
return false;
auto &M = CMI->getModule();
auto ClassType = SubType;
if (SubType.is<MetatypeType>())
ClassType = SubType.getMetatypeInstanceType(M);
CheckedCastBranchInst *LastCCBI = nullptr;
ClassDecl *CD = ClassType.getClassOrBoundGenericClass();
assert(CD && "Expected decl for class type!");
if (!CHA->hasKnownDirectSubclasses(CD)) {
// If there is only one possible alternative for this method,
// try to devirtualize it completely.
ClassHierarchyAnalysis::ClassList Subs;
if (isDefaultCaseKnown(CHA, AI, CD, Subs)) {
auto NewInstPair = tryDevirtualizeClassMethod(AI, SubTypeValue);
if (NewInstPair.first)
replaceDeadApply(AI, NewInstPair.first);
return NewInstPair.second.getInstruction() != nullptr;
}
DEBUG(llvm::dbgs() << "Inserting monomorphic speculative call for class " <<
CD->getName() << "\n");
return !!speculateMonomorphicTarget(AI, SubType, LastCCBI);
}
// True if any instructions were changed or generated.
bool Changed = false;
// Collect the direct and indirect subclasses for the class.
// Sort these subclasses in the order they should be tested by the
// speculative devirtualization. Different strategies could be used,
// E.g. breadth-first, depth-first, etc.
// Currently, let's use the breadth-first strategy.
// The exact static type of the instance should be tested first.
auto &DirectSubs = CHA->getDirectSubClasses(CD);
auto &IndirectSubs = CHA->getIndirectSubClasses(CD);
SmallVector<ClassDecl *, 8> Subs(DirectSubs);
Subs.append(IndirectSubs.begin(), IndirectSubs.end());
if (isa<BoundGenericClassType>(ClassType.getSwiftRValueType())) {
// Filter out any subclassses that do not inherit from this
// specific bound class.
auto RemovedIt = std::remove_if(Subs.begin(),
Subs.end(),
[&ClassType, &M](ClassDecl *Sub){
auto SubCanTy = Sub->getDeclaredType()->getCanonicalType();
// Unbound generic type can override a method from
// a bound generic class, but this unbound generic
// class is not considered to be a subclass of a
// bound generic class in a general case.
if (isa<UnboundGenericType>(SubCanTy))
return false;
// Handle the usual case here: the class in question
// should be a real subclass of a bound generic class.
return !ClassType.isSuperclassOf(
SILType::getPrimitiveObjectType(SubCanTy));
});
Subs.erase(RemovedIt, Subs.end());
}
// Number of subclasses which cannot be handled by checked_cast_br checks.
int NotHandledSubsNum = 0;
if (Subs.size() > MaxNumSpeculativeTargets) {
DEBUG(llvm::dbgs() << "Class " << CD->getName() << " has too many ("
<< Subs.size() << ") subclasses. Performing speculative "
"devirtualization only for the first "
<< MaxNumSpeculativeTargets << " of them.\n");
NotHandledSubsNum += (Subs.size() - MaxNumSpeculativeTargets);
Subs.erase(&Subs[MaxNumSpeculativeTargets], Subs.end());
}
DEBUG(llvm::dbgs() << "Class " << CD->getName() << " is a superclass. "
"Inserting polymorphic speculative call.\n");
// Try to devirtualize the static class of instance
// if it is possible.
auto FirstAI = speculateMonomorphicTarget(AI, SubType, LastCCBI);
if (FirstAI) {
Changed = true;
AI = FirstAI;
}
// Perform a speculative devirtualization of a method invocation.
// It replaces an indirect class_method-based call by a code to perform
// a direct call of the method implementation based on the dynamic class
// of the instance.
//
// The code is generated according to the following principles:
//
// - For each direct subclass, a dedicated checked_cast_br instruction
// is generated to check if a dynamic class of the instance is exactly
// this subclass.
//
// - If this check succeeds, then it jumps to the code which performs a
// direct call of a method implementation specific to this subclass.
//
// - If this check fails, then a different subclass is checked by means of
// checked_cast_br in a similar way.
//
// - Finally, if the instance does not exactly match any of the direct
// subclasses, the "default" case code is generated, which should handle
// all remaining alternatives, i.e. it should be able to dispatch to any
// possible remaining method implementations. Typically this is achieved by
// using a class_method instruction, which performs an indirect invocation.
// But if it can be proven that only one specific implementation of
// a method will be always invoked by this code, then a class_method-based
// call can be devirtualized and replaced by a more efficient direct
// invocation of this specific method implementation.
//
// Remark: With the current implementation of a speculative devirtualization,
// if devirtualization of the "default" case is possible, then it would
// by construction directly invoke the implementation of the method
// corresponding to the static type of the instance. This may change
// in the future, if we start using PGO for ordering of checked_cast_br
// checks.
// TODO: The ordering of checks may benefit from using a PGO, because
// the most probable alternatives could be checked first.
for (auto S : Subs) {
DEBUG(llvm::dbgs() << "Inserting a speculative call for class "
<< CD->getName() << " and subclass " << S->getName() << "\n");
CanType CanClassType = S->getDeclaredType()->getCanonicalType();
SILType ClassType = SILType::getPrimitiveObjectType(CanClassType);
if (!ClassType.getClassOrBoundGenericClass()) {
// This subclass cannot be handled. This happens e.g. if it is
// a generic class.
NotHandledSubsNum++;
continue;
}
auto ClassOrMetatypeType = ClassType;
if (auto EMT = SubType.getAs<AnyMetatypeType>()) {
auto InstTy = ClassType.getSwiftRValueType();
auto *MetaTy = MetatypeType::get(InstTy, EMT->getRepresentation());
auto CanMetaTy = CanMetatypeType::CanTypeWrapper(MetaTy);
ClassOrMetatypeType = SILType::getPrimitiveObjectType(CanMetaTy);
}
// Pass the metatype of the subclass.
auto NewAI = speculateMonomorphicTarget(AI, ClassOrMetatypeType, LastCCBI);
if (!NewAI) {
NotHandledSubsNum++;
continue;
}
AI = NewAI;
Changed = true;
}
// Check if there is only a single statically known implementation
// of the method which can be called by the default case handler.
if (NotHandledSubsNum || !isDefaultCaseKnown(CHA, AI, CD, Subs)) {
// Devirtualization of remaining cases is not possible,
// because more than one implementation of the method
// needs to be handled here. Thus, an indirect call through
// the class_method cannot be eliminated completely.
//
return Changed;
}
// At this point it is known that there is only one remaining method
// implementation which is not covered by checked_cast_br checks yet.
// So, it is safe to replace a class_method invocation by
// a direct call of this remaining implementation.
if (LastCCBI && SubTypeValue == LastCCBI->getOperand()) {
// Remove last checked_cast_br, because it will always succeed.
SILBuilderWithScope B(LastCCBI);
auto CastedValue = B.createUncheckedBitCast(LastCCBI->getLoc(),
LastCCBI->getOperand(),
LastCCBI->getCastType());
B.createBranch(LastCCBI->getLoc(), LastCCBI->getSuccessBB(), {CastedValue});
LastCCBI->eraseFromParent();
return true;
}
auto NewInstPair = tryDevirtualizeClassMethod(AI, SubTypeValue);
assert(NewInstPair.first && "Expected to be able to devirtualize apply!");
replaceDeadApply(AI, NewInstPair.first);
return true;
}
/// Inlines all mandatory inlined functions into the body of a function,
/// first recursively inlining all mandatory apply instructions in those
/// functions into their bodies if necessary.
///
/// \param F the function to be processed
/// \param AI nullptr if this is being called from the top level; the relevant
/// ApplyInst requiring the recursive call when non-null
/// \param FullyInlinedSet the set of all functions already known to be fully
/// processed, to avoid processing them over again
/// \param SetFactory an instance of ImmutableFunctionSet::Factory
/// \param CurrentInliningSet the set of functions currently being inlined in
/// the current call stack of recursive calls
///
/// \returns true if successful, false if failed due to circular inlining.
static bool
runOnFunctionRecursively(SILOptFunctionBuilder &FuncBuilder,
SILFunction *F, FullApplySite AI,
DenseFunctionSet &FullyInlinedSet,
ImmutableFunctionSet::Factory &SetFactory,
ImmutableFunctionSet CurrentInliningSet,
ClassHierarchyAnalysis *CHA) {
// Avoid reprocessing functions needlessly.
if (FullyInlinedSet.count(F))
return true;
// Prevent attempt to circularly inline.
if (CurrentInliningSet.contains(F)) {
// This cannot happen on a top-level call, so AI should be non-null.
assert(AI && "Cannot have circular inline without apply");
SILLocation L = AI.getLoc();
assert(L && "Must have location for transparent inline apply");
diagnose(F->getModule().getASTContext(), L.getStartSourceLoc(),
diag::circular_transparent);
return false;
}
// Add to the current inlining set (immutably, so we only affect the set
// during this call and recursive subcalls).
CurrentInliningSet = SetFactory.add(CurrentInliningSet, F);
SmallVector<std::pair<SILValue, ParameterConvention>, 16> CaptureArgs;
SmallVector<SILValue, 32> FullArgs;
// Visiting blocks in reverse order avoids revisiting instructions after block
// splitting, which would be quadratic.
for (auto BI = F->rbegin(), BE = F->rend(), nextBB = BI; BI != BE;
BI = nextBB) {
// After inlining, the block iterator will be adjusted to point to the last
// block containing inlined instructions. This way, the inlined function
// body will be reprocessed within the caller's context without revisiting
// any original instructions.
nextBB = std::next(BI);
// While iterating over this block, instructions are inserted and deleted.
// To avoid quadratic block splitting, instructions must be processed in
// reverse order (block splitting reassigned the parent pointer of all
// instructions below the split point).
for (auto II = BI->rbegin(); II != BI->rend(); ++II) {
FullApplySite InnerAI = FullApplySite::isa(&*II);
if (!InnerAI)
continue;
// *NOTE* If devirtualization succeeds, devirtInst may not be InnerAI,
// but a casted result of InnerAI or even a block argument due to
// abstraction changes when calling the witness or class method.
auto *devirtInst = tryDevirtualizeApplyHelper(InnerAI, CHA);
// Restore II to the current apply site.
II = devirtInst->getReverseIterator();
// If the devirtualized call result is no longer a invalid FullApplySite,
// then it has succeeded, but the result is not immediately inlinable.
InnerAI = FullApplySite::isa(devirtInst);
if (!InnerAI)
continue;
SILValue CalleeValue = InnerAI.getCallee();
bool IsThick;
PartialApplyInst *PAI;
SILFunction *CalleeFunction = getCalleeFunction(
F, InnerAI, IsThick, CaptureArgs, FullArgs, PAI);
if (!CalleeFunction)
continue;
// Then recursively process it first before trying to inline it.
if (!runOnFunctionRecursively(FuncBuilder, CalleeFunction, InnerAI,
FullyInlinedSet, SetFactory,
CurrentInliningSet, CHA)) {
// If we failed due to circular inlining, then emit some notes to
// trace back the failure if we have more information.
// FIXME: possibly it could be worth recovering and attempting other
// inlines within this same recursive call rather than simply
// propagating the failure.
if (AI) {
SILLocation L = AI.getLoc();
assert(L && "Must have location for transparent inline apply");
diagnose(F->getModule().getASTContext(), L.getStartSourceLoc(),
diag::note_while_inlining);
}
return false;
}
// Get our list of substitutions.
auto Subs = (PAI
? PAI->getSubstitutionMap()
: InnerAI.getSubstitutionMap());
SILOpenedArchetypesTracker OpenedArchetypesTracker(F);
F->getModule().registerDeleteNotificationHandler(
&OpenedArchetypesTracker);
// The callee only needs to know about opened archetypes used in
// the substitution list.
OpenedArchetypesTracker.registerUsedOpenedArchetypes(
InnerAI.getInstruction());
if (PAI) {
OpenedArchetypesTracker.registerUsedOpenedArchetypes(PAI);
}
SILInliner Inliner(FuncBuilder, SILInliner::InlineKind::MandatoryInline,
Subs, OpenedArchetypesTracker);
if (!Inliner.canInlineApplySite(InnerAI))
continue;
// Inline function at I, which also changes I to refer to the first
// instruction inlined in the case that it succeeds. We purposely
// process the inlined body after inlining, because the inlining may
// have exposed new inlining opportunities beyond those present in
// the inlined function when processed independently.
LLVM_DEBUG(llvm::errs() << "Inlining @" << CalleeFunction->getName()
<< " into @" << InnerAI.getFunction()->getName()
<< "\n");
// If we intend to inline a thick function, then we need to balance the
// reference counts for correctness.
if (IsThick) {
bool IsCalleeGuaranteed =
PAI &&
PAI->getType().castTo<SILFunctionType>()->isCalleeGuaranteed();
fixupReferenceCounts(InnerAI.getInstruction(), CalleeValue, CaptureArgs,
IsCalleeGuaranteed);
}
// Register a callback to record potentially unused function values after
// inlining.
ClosureCleanup closureCleanup;
Inliner.setDeletionCallback([&closureCleanup](SILInstruction *I) {
closureCleanup.recordDeadFunction(I);
});
// Inlining deletes the apply, and can introduce multiple new basic
// blocks. After this, CalleeValue and other instructions may be invalid.
// nextBB will point to the last inlined block
auto firstInlinedInstAndLastBB =
Inliner.inlineFunction(CalleeFunction, InnerAI, FullArgs);
nextBB = firstInlinedInstAndLastBB.second->getReverseIterator();
++NumMandatoryInlines;
// The IR is now valid, and trivial dead arguments are removed. However,
// we may be able to remove dead callee computations (e.g. dead
// partial_apply closures).
closureCleanup.cleanupDeadClosures(F);
// Resume inlining within nextBB, which contains only the inlined
// instructions and possibly instructions in the original call block that
// have not yet been visited.
break;
}
}
// Keep track of full inlined functions so we don't waste time recursively
// reprocessing them.
FullyInlinedSet.insert(F);
return true;
}
/// \brief Check if it is possible to devirtualize an Apply instruction
/// and a class member obtained using the class_method instruction into
/// a direct call to a specific member of a specific class.
///
/// \p AI is the apply to devirtualize.
/// \p ClassOrMetatypeType is the class type or metatype type we are
/// devirtualizing for.
/// return true if it is possible to devirtualize, false - otherwise.
bool swift::canDevirtualizeClassMethod(FullApplySite AI,
SILType ClassOrMetatypeType) {
DEBUG(llvm::dbgs() << " Trying to devirtualize : " << *AI.getInstruction());
SILModule &Mod = AI.getModule();
// First attempt to lookup the origin for our class method. The origin should
// either be a metatype or an alloc_ref.
DEBUG(llvm::dbgs() << " Origin Type: " << ClassOrMetatypeType);
auto *MI = cast<MethodInst>(AI.getCallee());
// Find the implementation of the member which should be invoked.
auto *F = getTargetClassMethod(Mod, ClassOrMetatypeType, MI);
// If we do not find any such function, we have no function to devirtualize
// to... so bail.
if (!F) {
DEBUG(llvm::dbgs() << " FAIL: Could not find matching VTable or "
"vtable method for this class.\n");
return false;
}
if (!F->shouldOptimize()) {
// Do not consider functions that should not be optimized.
DEBUG(llvm::dbgs() << " FAIL: Could not optimize function "
<< " because it is marked no-opt: " << F->getName()
<< "\n");
return false;
}
if (AI.getFunction()->isFragile()) {
// function_ref inside fragile function cannot reference a private or
// hidden symbol.
if (!F->hasValidLinkageForFragileRef())
return false;
}
// Type of the actual function to be called.
CanSILFunctionType GenCalleeType = F->getLoweredFunctionType();
// Type of the actual function to be called with substitutions applied.
CanSILFunctionType SubstCalleeType = GenCalleeType;
// For polymorphic functions, bail if the number of substitutions is
// not the same as the number of expected generic parameters.
if (GenCalleeType->isPolymorphic()) {
// First, find proper list of substitutions for the concrete
// method to be called.
SmallVector<Substitution, 4> Subs;
getSubstitutionsForCallee(Mod, GenCalleeType,
ClassOrMetatypeType.getSwiftRValueType(),
AI, Subs);
SubstCalleeType = GenCalleeType->substGenericArgs(Mod, Subs);
}
// Check if the optimizer knows how to cast the return type.
SILType ReturnType = SubstCalleeType->getSILResult();
if (!canCastValueToABICompatibleType(Mod, ReturnType, AI.getType()))
return false;
return true;
}