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swift-mirror/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp
Arnold Schwaighofer 2fd904808c ConstantTracker: Look through mark_dependence instructions 
An interposed mark_dependence should not block the heuristic that adds a
benefit when inlining a function that takes a closure argument.
2025-08-25 13:57:23 -07:00

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//===--- PerformanceInlinerUtils.cpp - Performance inliner utilities. -----===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 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
//
//===----------------------------------------------------------------------===//
#include "swift/SILOptimizer/Analysis/ArraySemantic.h"
#include "swift/SILOptimizer/Analysis/BasicCalleeAnalysis.h"
#include "swift/SILOptimizer/Analysis/IsSelfRecursiveAnalysis.h"
#include "swift/SILOptimizer/Utils/PerformanceInlinerUtils.h"
#include "swift/AST/Module.h"
#include "swift/Basic/Assertions.h"
#include "swift/SILOptimizer/Utils/InstOptUtils.h"
#include "llvm/Support/CommandLine.h"
llvm::cl::opt<std::string>
SILInlineNeverFuns("sil-inline-never-functions", llvm::cl::init(""),
llvm::cl::desc("Never inline functions whose name "
"includes this string."));
llvm::cl::list<std::string>
SILInlineNeverFun("sil-inline-never-function", llvm::cl::CommaSeparated,
llvm::cl::desc("Never inline functions whose name "
"is this string"));
//===----------------------------------------------------------------------===//
// ConstantTracker
//===----------------------------------------------------------------------===//
void ConstantTracker::trackInst(SILInstruction *inst) {
if (auto *LI = dyn_cast<LoadInst>(inst)) {
SILValue baseAddr = scanProjections(LI->getOperand());
if (SILInstruction *loadLink = getMemoryContent(baseAddr))
links[LI] = loadLink;
} else if (auto *SI = dyn_cast<StoreInst>(inst)) {
SILValue baseAddr = scanProjections(SI->getOperand(1));
memoryContent[baseAddr] = SI;
} else if (auto *CAI = dyn_cast<CopyAddrInst>(inst)) {
if (!CAI->isTakeOfSrc()) {
// Treat a copy_addr as a load + store
SILValue loadAddr = scanProjections(CAI->getOperand(0));
if (SILInstruction *loadLink = getMemoryContent(loadAddr)) {
links[CAI] = loadLink;
SILValue storeAddr = scanProjections(CAI->getOperand(1));
memoryContent[storeAddr] = CAI;
}
}
}
}
SILValue ConstantTracker::scanProjections(SILValue addr,
SmallVectorImpl<Projection> *Result) {
for (;;) {
if (auto *I = Projection::isAddressProjection(addr)) {
if (Result) {
Result->push_back(Projection(I));
}
addr = I->getOperand(0);
continue;
}
if (SILValue param = getParam(addr)) {
// Go to the caller.
addr = param;
continue;
}
// Return the base address = the first address which is not a projection.
return addr;
}
}
SILValue ConstantTracker::getStoredValue(SILInstruction *loadInst,
ProjectionPath &projStack) {
SILInstruction *store = links[loadInst];
if (!store && callerTracker)
store = callerTracker->links[loadInst];
if (!store) return SILValue();
assert(isa<LoadInst>(loadInst) || isa<CopyAddrInst>(loadInst));
// Push the address projections of the load onto the stack.
SmallVector<Projection, 4> loadProjections;
scanProjections(loadInst->getOperand(0), &loadProjections);
for (const Projection &proj : loadProjections) {
projStack.push_back(proj);
}
// Pop the address projections of the store from the stack.
SmallVector<Projection, 4> storeProjections;
scanProjections(store->getOperand(1), &storeProjections);
for (auto iter = storeProjections.rbegin(); iter != storeProjections.rend();
++iter) {
const Projection &proj = *iter;
// The corresponding load-projection must match the store-projection.
if (projStack.empty() || projStack.back() != proj)
return SILValue();
projStack.pop_back();
}
if (isa<StoreInst>(store))
return store->getOperand(0);
// The copy_addr instruction is both a load and a store. So we follow the link
// again.
assert(isa<CopyAddrInst>(store));
return getStoredValue(store, projStack);
}
// Get the aggregate member based on the top of the projection stack.
static SILValue getMember(SILInstruction *inst, ProjectionPath &projStack) {
if (!projStack.empty()) {
const Projection &proj = projStack.back();
return proj.getOperandForAggregate(inst);
}
return SILValue();
}
SILValue swift::stripFunctionConversions(SILValue val) {
SILValue result = nullptr;
for (;;) {
if (auto ti = dyn_cast<ThinToThickFunctionInst>(val)) {
val = ti->getOperand();
result = val;
continue;
} else if (auto cfi = dyn_cast<ConvertFunctionInst>(val)) {
val = cfi->getOperand();
result = val;
continue;
} else if (auto cvt = dyn_cast<ConvertEscapeToNoEscapeInst>(val)) {
val = cvt->getOperand();
result = val;
continue;
} else if (auto md = dyn_cast<MarkDependenceInst>(val)) {
val = md->getValue();
result = val;
} else {
break;
}
}
return result;
}
SILInstruction *ConstantTracker::getDef(SILValue val,
ProjectionPath &projStack) {
// Track the value up the dominator tree.
for (;;) {
if (auto *inst = dyn_cast<SingleValueInstruction>(val)) {
if (auto pi = Projection::isObjectProjection(val)) {
// Extract a member from a struct/tuple/enum.
projStack.push_back(Projection(pi));
val = pi->getOperand(0);
continue;
} else if (SILValue member = getMember(inst, projStack)) {
// The opposite of a projection instruction: composing a struct/tuple.
projStack.pop_back();
val = member;
continue;
} else if (SILValue loadedVal = getStoredValue(inst, projStack)) {
// A value loaded from memory.
val = loadedVal;
continue;
} else if (auto base = stripFunctionConversions(inst)) {
val = base;
continue;
}
return inst;
} else if (SILValue param = getParam(val)) {
// Continue in the caller.
val = param;
continue;
}
return nullptr;
}
}
ConstantTracker::IntConst ConstantTracker::getBuiltinConst(BuiltinInst *BI, int depth) {
const BuiltinInfo &Builtin = BI->getBuiltinInfo();
OperandValueArrayRef Args = BI->getArguments();
switch (Builtin.ID) {
default: break;
// Fold comparison predicates.
#define BUILTIN(id, name, Attrs)
#define BUILTIN_BINARY_PREDICATE(id, name, attrs, overload) \
case BuiltinValueKind::id:
#include "swift/AST/Builtins.def"
{
IntConst lhs = getIntConst(Args[0], depth);
IntConst rhs = getIntConst(Args[1], depth);
if (lhs.isValid && rhs.isValid) {
return IntConst(
constantFoldComparisonInt(lhs.value, rhs.value, Builtin.ID),
lhs.isFromCaller || rhs.isFromCaller);
}
break;
}
case BuiltinValueKind::SAddOver:
case BuiltinValueKind::UAddOver:
case BuiltinValueKind::SSubOver:
case BuiltinValueKind::USubOver:
case BuiltinValueKind::SMulOver:
case BuiltinValueKind::UMulOver: {
IntConst lhs = getIntConst(Args[0], depth);
IntConst rhs = getIntConst(Args[1], depth);
if (lhs.isValid && rhs.isValid) {
bool IgnoredOverflow;
return IntConst(constantFoldBinaryWithOverflow(lhs.value, rhs.value,
IgnoredOverflow,
getLLVMIntrinsicIDForBuiltinWithOverflow(Builtin.ID)),
lhs.isFromCaller || rhs.isFromCaller);
}
break;
}
case BuiltinValueKind::SDiv:
case BuiltinValueKind::SRem:
case BuiltinValueKind::UDiv:
case BuiltinValueKind::URem: {
IntConst lhs = getIntConst(Args[0], depth);
IntConst rhs = getIntConst(Args[1], depth);
if (lhs.isValid && rhs.isValid && rhs.value != 0) {
bool IgnoredOverflow;
return IntConst(constantFoldDiv(lhs.value, rhs.value,
IgnoredOverflow, Builtin.ID),
lhs.isFromCaller || rhs.isFromCaller);
}
break;
}
case BuiltinValueKind::And:
case BuiltinValueKind::AShr:
case BuiltinValueKind::LShr:
case BuiltinValueKind::Or:
case BuiltinValueKind::Shl:
case BuiltinValueKind::Xor: {
IntConst lhs = getIntConst(Args[0], depth);
IntConst rhs = getIntConst(Args[1], depth);
if (lhs.isValid && rhs.isValid) {
return IntConst(constantFoldBitOperation(lhs.value, rhs.value,
Builtin.ID),
lhs.isFromCaller || rhs.isFromCaller);
}
break;
}
case BuiltinValueKind::Trunc:
case BuiltinValueKind::ZExt:
case BuiltinValueKind::SExt:
case BuiltinValueKind::TruncOrBitCast:
case BuiltinValueKind::ZExtOrBitCast:
case BuiltinValueKind::SExtOrBitCast: {
IntConst val = getIntConst(Args[0], depth);
if (val.isValid) {
return IntConst(constantFoldCast(val.value, Builtin), val.isFromCaller);
}
break;
}
}
return IntConst();
}
// Tries to evaluate the integer constant of a value. The \p depth is used
// to limit the complexity.
ConstantTracker::IntConst ConstantTracker::getIntConst(SILValue val, int depth) {
// Don't spend too much time with constant evaluation.
if (depth >= 10)
return IntConst();
SILInstruction *I = getDef(val);
if (!I)
return IntConst();
if (auto *IL = dyn_cast<IntegerLiteralInst>(I)) {
return IntConst(IL->getValue(), IL->getFunction() != F);
}
if (auto *BI = dyn_cast<BuiltinInst>(I)) {
if (constCache.count(BI) != 0)
return constCache[BI];
IntConst builtinConst = getBuiltinConst(BI, depth + 1);
constCache[BI] = builtinConst;
return builtinConst;
}
return IntConst();
}
// Returns the taken block of a terminator instruction if the condition turns
// out to be constant.
SILBasicBlock *ConstantTracker::getTakenBlock(TermInst *term) {
if (auto *CBI = dyn_cast<CondBranchInst>(term)) {
IntConst condConst = getIntConst(CBI->getCondition());
if (condConst.isFromCaller) {
return condConst.value != 0 ? CBI->getTrueBB() : CBI->getFalseBB();
}
return nullptr;
}
if (auto *SVI = dyn_cast<SwitchValueInst>(term)) {
IntConst switchConst = getIntConst(SVI->getOperand());
if (switchConst.isFromCaller) {
for (unsigned Idx = 0; Idx < SVI->getNumCases(); ++Idx) {
auto switchCase = SVI->getCase(Idx);
if (auto *IL = dyn_cast<IntegerLiteralInst>(switchCase.first)) {
if (switchConst.value == IL->getValue())
return switchCase.second;
} else {
return nullptr;
}
}
if (SVI->hasDefault())
return SVI->getDefaultBB();
}
return nullptr;
}
if (auto *SEI = dyn_cast<SwitchEnumInst>(term)) {
if (SILInstruction *def = getDefInCaller(SEI->getOperand())) {
if (auto *EI = dyn_cast<EnumInst>(def)) {
for (unsigned Idx = 0; Idx < SEI->getNumCases(); ++Idx) {
auto enumCase = SEI->getCase(Idx);
if (enumCase.first == EI->getElement())
return enumCase.second;
}
if (SEI->hasDefault())
return SEI->getDefaultBB();
}
}
return nullptr;
}
if (auto *CCB = dyn_cast<CheckedCastBranchInst>(term)) {
if (SILInstruction *def = getDefInCaller(CCB->getOperand())) {
if (auto *UCI = dyn_cast<UpcastInst>(def)) {
SILType castType = UCI->getOperand()->getType();
if (CCB->getTargetLoweredType().isExactSuperclassOf(castType)) {
return CCB->getSuccessBB();
}
if (!castType.isBindableToSuperclassOf(CCB->getTargetLoweredType())) {
return CCB->getFailureBB();
}
}
}
}
return nullptr;
}
//===----------------------------------------------------------------------===//
// Shortest path analysis
//===----------------------------------------------------------------------===//
int ShortestPathAnalysis::getEntryDistFromPreds(const SILBasicBlock *BB,
int LoopDepth) {
int MinDist = InitialDist;
for (SILBasicBlock *Pred : BB->getPredecessorBlocks()) {
BlockInfo *PredInfo = getBlockInfo(Pred);
Distances &PDists = PredInfo->getDistances(LoopDepth);
int DistFromEntry = PDists.DistFromEntry + PredInfo->Length +
PDists.LoopHeaderLength;
assert(DistFromEntry >= 0);
if (DistFromEntry < MinDist)
MinDist = DistFromEntry;
}
return MinDist;
}
int ShortestPathAnalysis::getExitDistFromSuccs(const SILBasicBlock *BB,
int LoopDepth) {
int MinDist = InitialDist;
for (const SILSuccessor &Succ : BB->getSuccessors()) {
BlockInfo *SuccInfo = getBlockInfo(Succ);
Distances &SDists = SuccInfo->getDistances(LoopDepth);
if (SDists.DistToExit < MinDist)
MinDist = SDists.DistToExit;
}
return MinDist;
}
/// Detect an edge from the loop pre-header's predecessor to the loop exit
/// block. Such an edge "short-cuts" a loop if it is never iterated. But usually
/// it is the less frequent case and we want to ignore it.
/// E.g. it handles the case of N==0 for
/// for i in 0..<N { ... }
/// If the \p Loop has such an edge the source block of this edge is returned,
/// which is the predecessor of the loop pre-header.
static SILBasicBlock *detectLoopBypassPreheader(SILLoop *Loop) {
SILBasicBlock *Pred = Loop->getLoopPreheader();
if (!Pred)
return nullptr;
SILBasicBlock *PredPred = Pred->getSinglePredecessorBlock();
if (!PredPred)
return nullptr;
auto *CBR = dyn_cast<CondBranchInst>(PredPred->getTerminator());
if (!CBR)
return nullptr;
SILBasicBlock *Succ = (CBR->getTrueBB() == Pred ? CBR->getFalseBB() :
CBR->getTrueBB());
for (SILBasicBlock *PredOfSucc : Succ->getPredecessorBlocks()) {
SILBasicBlock *Exiting = PredOfSucc->getSinglePredecessorBlock();
if (!Exiting)
Exiting = PredOfSucc;
if (Loop->contains(Exiting))
return PredPred;
}
return nullptr;
}
void ShortestPathAnalysis::analyzeLoopsRecursively(SILLoop *Loop, int LoopDepth) {
if (LoopDepth >= MaxNumLoopLevels)
return;
// First dive into the inner loops.
for (SILLoop *SubLoop : Loop->getSubLoops()) {
analyzeLoopsRecursively(SubLoop, LoopDepth + 1);
}
BlockInfo *HeaderInfo = getBlockInfo(Loop->getHeader());
Distances &HeaderDists = HeaderInfo->getDistances(LoopDepth);
// Initial values for the entry (== header) and exit-predecessor (== header as
// well).
HeaderDists.DistFromEntry = 0;
HeaderDists.DistToExit = 0;
solveDataFlow(Loop->getBlocks(), LoopDepth);
int LoopLength = getExitDistFromSuccs(Loop->getHeader(), LoopDepth) +
HeaderInfo->getLength(LoopDepth);
HeaderDists.DistToExit = LoopLength;
// If there is a loop bypass edge, add the loop length to the loop pre-pre-
// header instead to the header. This actually let us ignore the loop bypass
// edge in the length calculation for the loop's parent scope.
if (SILBasicBlock *Bypass = detectLoopBypassPreheader(Loop))
HeaderInfo = getBlockInfo(Bypass);
// Add the full loop length (= assumed-iteration-count * length) to the loop
// header so that it is considered in the parent scope.
HeaderInfo->getDistances(LoopDepth - 1).LoopHeaderLength =
LoopCount * LoopLength;
}
ShortestPathAnalysis::Weight ShortestPathAnalysis::
getWeight(SILBasicBlock *BB, Weight CallerWeight) {
assert(BB->getParent() == F);
// Return a conservative default if the analysis was not done due to a high number of blocks.
if (BlockInfos.empty())
return Weight(CallerWeight.ScopeLength + ColdBlockLength, CallerWeight.LoopWeight);
SILLoop *Loop = LI->getLoopFor(BB);
if (!Loop) {
// We are not in a loop. So just account the length of our function scope
// in to the length of the CallerWeight.
return Weight(CallerWeight.ScopeLength + getScopeLength(BB, 0),
CallerWeight.LoopWeight);
}
int LoopDepth = Loop->getLoopDepth();
// Deal with the corner case of having more than 4 nested loops.
while (LoopDepth >= MaxNumLoopLevels) {
--LoopDepth;
Loop = Loop->getParentLoop();
}
Weight W(getScopeLength(BB, LoopDepth), SingleLoopWeight);
// Add weights for all the loops BB is in.
while (Loop) {
assert(LoopDepth > 0);
BlockInfo *HeaderInfo = getBlockInfo(Loop->getHeader());
int InnerLoopLength = HeaderInfo->getScopeLength(LoopDepth) *
ShortestPathAnalysis::LoopCount;
int OuterLoopWeight = SingleLoopWeight;
int OuterScopeLength = HeaderInfo->getScopeLength(LoopDepth - 1);
// Reaching the outermost loop, we use the CallerWeight to get the outer
// length+loopweight.
if (LoopDepth == 1) {
// If the apply in the caller is not in a significant loop, just stop with
// what we have now.
if (CallerWeight.LoopWeight < 4)
return W;
// If this function is part of the caller's scope length take the caller's
// scope length. Note: this is not the case e.g. if the apply is in a
// then-branch of an if-then-else in the caller and the else-branch is
// the short path.
if (CallerWeight.ScopeLength > OuterScopeLength)
OuterScopeLength = CallerWeight.ScopeLength;
OuterLoopWeight = CallerWeight.LoopWeight;
}
assert(OuterScopeLength >= InnerLoopLength);
// If the current loop is only a small part of its outer loop, we don't
// take the outer loop that much into account. Only if the current loop is
// actually the "main part" in the outer loop we add the full loop weight
// for the outer loop.
if (OuterScopeLength < InnerLoopLength * 2) {
W.LoopWeight += OuterLoopWeight - 1;
} else if (OuterScopeLength < InnerLoopLength * 3) {
W.LoopWeight += OuterLoopWeight - 2;
} else if (OuterScopeLength < InnerLoopLength * 4) {
W.LoopWeight += OuterLoopWeight - 3;
} else {
return W;
}
--LoopDepth;
Loop = Loop->getParentLoop();
}
assert(LoopDepth == 0);
return W;
}
void ShortestPathAnalysis::dump() {
printFunction(llvm::errs());
}
void ShortestPathAnalysis::printFunction(llvm::raw_ostream &OS) {
OS << "SPA @" << F->getName() << "\n";
for (SILBasicBlock &BB : *F) {
printBlockInfo(OS, &BB, 0);
}
for (SILLoop *Loop : *LI) {
printLoop(OS, Loop, 1);
}
}
void ShortestPathAnalysis::printLoop(llvm::raw_ostream &OS, SILLoop *Loop,
int LoopDepth) {
if (LoopDepth >= MaxNumLoopLevels)
return;
assert(LoopDepth == (int)Loop->getLoopDepth());
OS << "Loop bb" << Loop->getHeader()->getDebugID() << ":\n";
for (SILBasicBlock *BB : Loop->getBlocks()) {
printBlockInfo(OS, BB, LoopDepth);
}
for (SILLoop *SubLoop : Loop->getSubLoops()) {
printLoop(OS, SubLoop, LoopDepth + 1);
}
}
void ShortestPathAnalysis::printBlockInfo(llvm::raw_ostream &OS,
SILBasicBlock *BB, int LoopDepth) {
BlockInfo *BBInfo = getBlockInfo(BB);
Distances &D = BBInfo->getDistances(LoopDepth);
OS << " bb" << BB->getDebugID() << ": length=" << BBInfo->Length << '+'
<< D.LoopHeaderLength << ", d-entry=" << D.DistFromEntry
<< ", d-exit=" << D.DistToExit << '\n';
}
void ShortestPathAnalysis::Weight::updateBenefit(int &Benefit,
int Importance) const {
assert(isValid());
int newBenefit = 0;
// Use some heuristics. The basic idea is: length is bad, loops are good.
if (ScopeLength > 320) {
newBenefit = Importance;
} else if (ScopeLength > 160) {
newBenefit = Importance + LoopWeight * 4;
} else if (ScopeLength > 80) {
newBenefit = Importance + LoopWeight * 8;
} else if (ScopeLength > 40) {
newBenefit = Importance + LoopWeight * 12;
} else if (ScopeLength > 20) {
newBenefit = Importance + LoopWeight * 16;
} else {
newBenefit = Importance + 20 + LoopWeight * 16;
}
// We don't accumulate the benefit instead we max it.
if (newBenefit > Benefit)
Benefit = newBenefit;
}
SemanticFunctionLevel swift::getSemanticFunctionLevel(SILFunction *function) {
// Currently, we only consider "array" semantic calls to be "optimizable
// semantic functions" (non-transient) because we only have semantic passes
// that recognize array operations, for example, hoisting them out of loops.
//
// Compiler "hints" and informational annotations (like remarks) should
// ideally use a separate annotation rather than @_semantics.
if (isFixedStorageSemanticsCallKind(function)) {
return SemanticFunctionLevel::Fundamental;
}
switch (getArraySemanticsKind(function)) {
case ArrayCallKind::kNone:
return SemanticFunctionLevel::Transient;
case ArrayCallKind::kArrayInitEmpty:
case ArrayCallKind::kArrayPropsIsNativeTypeChecked:
case ArrayCallKind::kCheckSubscript:
case ArrayCallKind::kCheckIndex:
case ArrayCallKind::kGetCount:
case ArrayCallKind::kGetCapacity:
case ArrayCallKind::kGetElement:
case ArrayCallKind::kGetElementAddress:
case ArrayCallKind::kMakeMutable:
case ArrayCallKind::kEndMutation:
case ArrayCallKind::kMutateUnknown:
return SemanticFunctionLevel::Fundamental;
// These have nested semantic calls, but they also expose the underlying
// buffer so must be treated as fundamental, and should not be inlined until
// after array semantic passes have run.
//
// TODO: Once Nested semantics calls are preserved during early inlining,
// change these to Nested.
case ArrayCallKind::kArrayInit:
case ArrayCallKind::kArrayUninitialized:
case ArrayCallKind::kWithUnsafeMutableBufferPointer:
return SemanticFunctionLevel::Fundamental;
case ArrayCallKind::kReserveCapacityForAppend:
case ArrayCallKind::kAppendContentsOf:
case ArrayCallKind::kAppendElement:
return SemanticFunctionLevel::Nested;
// Compiler intrinsics hide "normal" semantic methods, such as
// "array.uninitialized" or "array.end_mutation"--they are intentionally
// transient and should be inlined away immediately.
case ArrayCallKind::kArrayUninitializedIntrinsic:
case ArrayCallKind::kArrayFinalizeIntrinsic:
return SemanticFunctionLevel::Transient;
} // end switch
llvm_unreachable("covered switch");
}
/// Return true if \p apply calls into an optimizable semantic function from
/// within another semantic function, or from a "trivial" wrapper.
///
/// Checking for wrappers, in addition to directly annotated nested semantic
/// functions, allows semantic function calls to be wrapped inside trivial
/// getters and closures without needing to explicitly annotate those wrappers.
///
/// For example:
///
/// public var count: Int { getCount() }
/// @_semantic("count") internal func getCount() { ... }
///
/// Wrappers may be closures, so this semantic "nesting" is allowed:
///
/// @_semantics("append")
/// public func append(...) {
/// defer { endMutation() }
/// ...
/// }
/// @_semantics("endMutation") func endMutation() { ... }
///
/// TODO: if simply checking the call arguments results in too many functions
/// being considered "wrappers", thus preventing useful inlining, consider
/// either using a cost metric to check for low-cost wrappers or directly
/// checking for getters or closures.
///
/// TODO: Move this into PerformanceInlinerUtils and apply it to
/// getEligibleFunction. The mid-level pipeline should not inline semantic
/// functions into their wrappers. If such wrappers have still not been fully
/// inlined by the time late inlining runs, then the semantic call can be
/// inlined into the wrapper at that time.
bool swift::isNestedSemanticCall(FullApplySite apply) {
auto callee = apply.getReferencedFunctionOrNull();
if (!callee) {
return false;
}
if (!isOptimizableSemanticFunction(callee)) {
return false;
}
if (isOptimizableSemanticFunction(apply.getFunction())) {
return true;
}
// In a trivial wrapper, all call arguments are simply forwarded from the
// wrapper's arguments.
auto isForwardedArg = [](SILValue arg) {
while (true) {
if (isa<SILFunctionArgument>(arg) || isa<LiteralInst>(arg)) {
return true;
}
auto *argInst = arg->getDefiningInstruction();
if (!argInst) {
return false;
}
if (!getSingleValueCopyOrCast(argInst)) {
return false;
}
arg = argInst->getOperand(0);
}
};
return llvm::all_of(apply.getArguments(), isForwardedArg);
}
/// Checks if a generic callee and caller have compatible layout constraints.
static bool isCallerAndCalleeLayoutConstraintsCompatible(FullApplySite AI) {
SILFunction *Callee = AI.getReferencedFunctionOrNull();
assert(Callee && "Trying to optimize a dynamic function!?");
auto CalleeSig = Callee->getLoweredFunctionType()
->getInvocationGenericSignature();
auto AISubs = AI.getSubstitutionMap();
SmallVector<GenericTypeParamType *, 4> SubstParams;
CalleeSig->forEachParam([&](GenericTypeParamType *Param, bool Canonical) {
if (Canonical)
SubstParams.push_back(Param);
});
for (auto Param : SubstParams) {
// Map the parameter into context
auto ContextTy = Callee->mapTypeIntoContext(Param->getCanonicalType());
auto Archetype = ContextTy->getAs<ArchetypeType>();
if (!Archetype)
continue;
auto Layout = Archetype->getLayoutConstraint();
if (!Layout)
continue;
// The generic parameter has a layout constraint.
// Check that the substitution has the same constraint.
auto AIReplacement = Type(Param).subst(AISubs);
if (Layout->isClass()) {
if (!AIReplacement->satisfiesClassConstraint())
return false;
} else {
auto AIArchetype = AIReplacement->getAs<ArchetypeType>();
if (!AIArchetype)
return false;
auto AILayout = AIArchetype->getLayoutConstraint();
if (!AILayout)
return false;
if (AILayout != Layout)
return false;
}
}
return true;
}
// Returns the callee of an apply_inst if it is basically inlinable.
SILFunction *swift::getEligibleFunction(FullApplySite AI,
InlineSelection WhatToInline,
IsSelfRecursiveAnalysis *SRA) {
SILFunction *Callee = AI.getReferencedFunctionOrNull();
if (!Callee) {
return nullptr;
}
// Not all apply sites can be inlined, even if they're direct.
if (!SILInliner::canInlineApplySite(AI))
return nullptr;
// If our inline selection is only always inline, do a quick check if we have
// an always inline function and bail otherwise.
if (WhatToInline == InlineSelection::OnlyInlineAlways &&
Callee->getInlineStrategy() != AlwaysInline) {
return nullptr;
}
ModuleDecl *SwiftModule = Callee->getModule().getSwiftModule();
bool IsInStdlib = (SwiftModule->isStdlibModule() ||
SwiftModule->isOnoneSupportModule());
// Don't inline functions that are marked with the @_semantics or @_effects
// attribute if the inliner is asked not to inline them.
if (Callee->hasSemanticsAttrs() || Callee->hasEffectsKind()) {
if (WhatToInline >= InlineSelection::NoSemanticsAndEffects) {
// TODO: for stable optimization of semantics, prevent inlining whenever
// isOptimizableSemanticFunction(Callee) is true.
if (getSemanticFunctionLevel(Callee) == SemanticFunctionLevel::Fundamental
|| Callee->hasEffectsKind()) {
return nullptr;
}
if (Callee->hasSemanticsAttr("inline_late"))
return nullptr;
}
// The "availability" semantics attribute is treated like global-init.
if (Callee->hasSemanticsAttrs() &&
WhatToInline != InlineSelection::Everything &&
(Callee->hasSemanticsAttrThatStartsWith("availability") ||
(Callee->hasSemanticsAttrThatStartsWith("inline_late")))) {
return nullptr;
}
if (Callee->hasSemanticsAttrs() &&
WhatToInline == InlineSelection::Everything) {
if (Callee->hasSemanticsAttrThatStartsWith("inline_late") && IsInStdlib) {
return nullptr;
}
}
}
// We can't inline external declarations.
if (Callee->empty() || Callee->isExternalDeclaration()) {
return nullptr;
}
// Explicitly disabled inlining or optimization.
if (Callee->getInlineStrategy() == NoInline) {
return nullptr;
}
if (!SILInlineNeverFuns.empty() &&
Callee->getName().contains(SILInlineNeverFuns))
return nullptr;
if (!SILInlineNeverFun.empty() &&
SILInlineNeverFun.end() != std::find(SILInlineNeverFun.begin(),
SILInlineNeverFun.end(),
Callee->getName())) {
return nullptr;
}
if (!Callee->shouldOptimize()) {
return nullptr;
}
SILFunction *Caller = AI.getFunction();
// We don't support inlining a function that binds dynamic self because we
// have no mechanism to preserve the original function's local self metadata.
if (mayBindDynamicSelf(Callee)) {
// Check if passed Self is the same as the Self of the caller.
// In this case, it is safe to inline because both functions
// use the same Self.
if (!AI.hasSelfArgument() || !Caller->hasDynamicSelfMetadata()) {
return nullptr;
}
auto CalleeSelf = stripCasts(AI.getSelfArgument());
auto CallerSelf = Caller->getDynamicSelfMetadata();
if (CalleeSelf != SILValue(CallerSelf)) {
return nullptr;
}
}
// Detect self-recursive calls.
if (Caller == Callee) {
return nullptr;
}
// A non-fragile function may not be inlined into a fragile function.
if (!Callee->canBeInlinedIntoCaller(Caller->getSerializedKind())) {
if (Caller->isAnySerialized() &&
!Callee->hasValidLinkageForFragileRef(Caller->getSerializedKind())) {
llvm::errs() << "caller: " << Caller->getName() << "\n";
llvm::errs() << "callee: " << Callee->getName() << "\n";
ASSERT(false && "Should never be inlining a resilient function into "
"a fragile function");
}
return nullptr;
}
// Inlining self-recursive functions into other functions can result
// in excessive code duplication since we run the inliner multiple
// times in our pipeline.
if (SRA->get(Callee)->get()) {
return nullptr;
}
// We cannot inline function with layout constraints on its generic types
// if the corresponding substitution type does not have the same constraints.
// The reason for this restriction is that we'd need to be able to express
// in SIL something like casting a value of generic type T into a value of
// generic type T: _LayoutConstraint, which is impossible currently.
if (AI.hasSubstitutions()) {
if (!isCallerAndCalleeLayoutConstraintsCompatible(AI) &&
// TODO: revisit why we can make an exception for inline-always
// functions. Some tests depend on it.
Callee->getInlineStrategy() != AlwaysInline && !Callee->isTransparent())
return nullptr;
}
return Callee;
}
/// Returns true if the instruction \I has any interesting side effects which
/// might prevent inlining a pure function.
static bool hasInterestingSideEffect(SILInstruction *I) {
switch (I->getKind()) {
// Those instructions turn into no-ops after inlining, redundant load
// elimination, constant folding and dead-object elimination.
case swift::SILInstructionKind::StrongRetainInst:
case swift::SILInstructionKind::StrongReleaseInst:
case swift::SILInstructionKind::RetainValueInst:
case swift::SILInstructionKind::ReleaseValueInst:
case swift::SILInstructionKind::StoreInst:
case swift::SILInstructionKind::DeallocStackRefInst:
case swift::SILInstructionKind::DeallocRefInst:
return false;
default:
return I->getMemoryBehavior() != MemoryBehavior::None;
}
}
/// Returns true if the operand \p Arg is a constant or an object which is
/// initialized with constant values.
///
/// The value is considered to be constant if it is composed of side-effect free
/// instructions, like literal or aggregate instructions.
static bool isConstantArg(Operand *Arg) {
auto *ArgI = Arg->get()->getDefiningInstruction();
if (!ArgI)
return false;
SmallPtrSet<SILInstruction *, 8> Visited;
SmallVector<SILInstruction *, 8> Worklist;
auto addToWorklist = [&](SILInstruction *I) {
if (Visited.insert(I).second)
Worklist.push_back(I);
};
addToWorklist(ArgI);
// Visit the transitive closure of \p Arg and see if there is any side-effect
// instructions which prevents folding away everything after inlining.
while (!Worklist.empty()) {
SILInstruction *I = Worklist.pop_back_val();
if (hasInterestingSideEffect(I))
return false;
for (SILValue Result : I->getResults()) {
for (Operand *Use : Result->getUses()) {
if (Use != Arg)
addToWorklist(Use->getUser());
}
}
for (Operand &Op : I->getAllOperands()) {
if (SILInstruction *OpInst = Op.get()->getDefiningInstruction()) {
addToWorklist(OpInst);
} else {
return false;
}
}
}
return true;
}
bool swift::isPureCall(FullApplySite AI, BasicCalleeAnalysis *BCA) {
// If a call has only constant arguments and the call is pure, i.e. has
// no side effects, then we should always inline it.
// This includes arguments which are objects initialized with constant values.
if (BCA->getMemoryBehavior(AI, /*observeRetains*/ true) != MemoryBehavior::None)
return false;
// Check if all parameters are constant.
auto Args = AI.getArgumentOperands().slice(AI.getNumIndirectSILResults());
for (Operand &Arg : Args) {
if (!isConstantArg(&Arg)) {
return false;
}
}
return true;
}
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