/// Could this operand to an apply escape that function by being
/// stored or returned?
static bool applyArgumentEscapes(FullApplySite Apply, Operand *O) {
SILFunction *F = Apply.getReferencedFunction();
// If we cannot examine the function body, assume the worst.
if (!F || F->empty())
return true;
// Check the uses of the operand, but do not recurse down into other
// apply instructions.
auto calleeArg = F->getArgument(Apply.getCalleeArgIndex(*O));
return partialApplyEscapes(calleeArg, /* examineApply = */ false);
}
/// checkPartialApplyBody - Check the body of a partial apply to see
/// if the box pointer argument passed to it has uses that would
/// disqualify it from being promoted to a stack location. Return
/// true if this partial apply will not block our promoting the box.
static bool checkPartialApplyBody(Operand *O) {
SILFunction *F = ApplySite(O->getUser()).getReferencedFunction();
// If we cannot examine the function body, assume the worst.
if (!F || F->empty())
return false;
// We don't actually use these because we're not recursively
// rewriting the partial applies we find.
llvm::SmallVector<Operand *, 1> PromotedOperands;
auto calleeArg = F->getArgument(ApplySite(O->getUser()).getCalleeArgIndex(*O));
return !findUnexpectedBoxUse(calleeArg, /* examinePartialApply = */ false,
/* inAppliedFunction = */ true,
PromotedOperands);
}
void ClosureSpecializer::gatherCallSites(
SILFunction *Caller,
llvm::SmallVectorImpl<ClosureInfo*> &ClosureCandidates,
llvm::DenseSet<FullApplySite> &MultipleClosureAI) {
// A set of apply inst that we have associated with a closure. We use this to
// make sure that we do not handle call sites with multiple closure arguments.
llvm::DenseSet<FullApplySite> VisitedAI;
// For each basic block BB in Caller...
for (auto &BB : *Caller) {
// For each instruction II in BB...
for (auto &II : BB) {
// If II is not a closure that we support specializing, skip it...
if (!isSupportedClosure(&II))
continue;
ClosureInfo *CInfo = nullptr;
// Go through all uses of our closure.
for (auto *Use : II.getUses()) {
// If this use is not an apply inst or an apply inst with
// substitutions, there is nothing interesting for us to do, so
// continue...
auto AI = FullApplySite::isa(Use->getUser());
if (!AI || AI.hasSubstitutions())
continue;
// Check if we have already associated this apply inst with a closure to
// be specialized. We do not handle applies that take in multiple
// closures at this time.
if (!VisitedAI.insert(AI).second) {
MultipleClosureAI.insert(AI);
continue;
}
// If AI does not have a function_ref definition as its callee, we can
// not do anything here... so continue...
SILFunction *ApplyCallee = AI.getReferencedFunction();
if (!ApplyCallee || ApplyCallee->isExternalDeclaration())
continue;
// Ok, we know that we can perform the optimization but not whether or
// not the optimization is profitable. Find the index of the argument
// corresponding to our partial apply.
Optional<unsigned> ClosureIndex;
for (unsigned i = 0, e = AI.getNumArguments(); i != e; ++i) {
if (AI.getArgument(i) != SILValue(&II))
continue;
ClosureIndex = i;
DEBUG(llvm::dbgs() << " Found callsite with closure argument at "
<< i << ": " << *AI.getInstruction());
break;
}
// If we did not find an index, there is nothing further to do,
// continue.
if (!ClosureIndex.hasValue())
continue;
// Make sure that the Closure is invoked in the Apply's callee. We only
// want to perform closure specialization if we know that we will be
// able to change a partial_apply into an apply.
//
// TODO: Maybe just call the function directly instead of moving the
// partial apply?
SILValue Arg = ApplyCallee->getArgument(ClosureIndex.getValue());
if (std::none_of(Arg->use_begin(), Arg->use_end(),
[&Arg](Operand *Op) -> bool {
auto UserAI = FullApplySite::isa(Op->getUser());
return UserAI && UserAI.getCallee() == Arg;
})) {
continue;
}
auto NumIndirectResults =
AI.getSubstCalleeType()->getNumIndirectResults();
assert(ClosureIndex.getValue() >= NumIndirectResults);
auto ClosureParamIndex = ClosureIndex.getValue() - NumIndirectResults;
auto ParamInfo = AI.getSubstCalleeType()->getParameters();
SILParameterInfo ClosureParamInfo = ParamInfo[ClosureParamIndex];
// Get all non-failure exit BBs in the Apply Callee if our partial apply
// is guaranteed. If we do not understand one of the exit BBs, bail.
//
// We need this to make sure that we insert a release in the appropriate
// locations to balance the +1 from the creation of the partial apply.
llvm::TinyPtrVector<SILBasicBlock *> NonFailureExitBBs;
if (ClosureParamInfo.isGuaranteed() &&
!findAllNonFailureExitBBs(ApplyCallee, NonFailureExitBBs)) {
continue;
}
// Compute the final release points of the closure. We will insert
// release of the captured arguments here.
if (!CInfo) {
CInfo = new ClosureInfo(&II);
ValueLifetimeAnalysis VLA(CInfo->Closure);
VLA.computeFrontier(CInfo->LifetimeFrontier,
ValueLifetimeAnalysis::AllowToModifyCFG);
}
// Now we know that CSDesc is profitable to specialize. Add it to our
// call site list.
CInfo->CallSites.push_back(
CallSiteDescriptor(CInfo, AI, ClosureIndex.getValue(),
ClosureParamInfo, std::move(NonFailureExitBBs)));
}
if (CInfo)
ClosureCandidates.push_back(CInfo);
}
}
}