static bool canDevirtualizeWitnessMethod(ApplySite AI) {
SILFunction *F;
SILWitnessTable *WT;
auto *WMI = cast<WitnessMethodInst>(AI.getCallee());
std::tie(F, WT) =
AI.getModule().lookUpFunctionInWitnessTable(WMI->getConformance(),
WMI->getMember());
if (!F)
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;
}
/// In the cases where we can statically determine the function that
/// we'll call to, replace an apply of a witness_method with an apply
/// of a function_ref, returning the new apply.
DevirtualizationResult swift::tryDevirtualizeWitnessMethod(ApplySite AI) {
SILFunction *F;
SILWitnessTable *WT;
auto *WMI = cast<WitnessMethodInst>(AI.getCallee());
std::tie(F, WT) =
AI.getModule().lookUpFunctionInWitnessTable(WMI->getConformance(),
WMI->getMember());
if (!F)
return std::make_pair(nullptr, FullApplySite());
if (AI.getFunction()->isFragile()) {
// function_ref inside fragile function cannot reference a private or
// hidden symbol.
if (!F->hasValidLinkageForFragileRef())
return std::make_pair(nullptr, FullApplySite());
}
auto Result = devirtualizeWitnessMethod(AI, F, WMI->getConformance());
return std::make_pair(Result.getInstruction(), Result);
}
