/// Try to CSE the users of \p From to the users of \p To.
/// The original users of \p To are passed in ToApplyWitnessUsers.
/// Returns true on success.
static bool tryToCSEOpenExtCall(OpenExistentialAddrInst *From,
OpenExistentialAddrInst *To,
ApplyWitnessPair ToApplyWitnessUsers,
DominanceInfo *DA) {
assert(From != To && "Can't replace instruction with itself");
ApplyInst *FromAI = nullptr;
ApplyInst *ToAI = nullptr;
WitnessMethodInst *FromWMI = nullptr;
WitnessMethodInst *ToWMI = nullptr;
std::tie(FromAI, FromWMI) = getOpenExistentialUsers(From);
std::tie(ToAI, ToWMI) = ToApplyWitnessUsers;
// Make sure that the OEA instruction has exactly two expected users.
if (!FromAI || !ToAI || !FromWMI || !ToWMI)
return false;
// Make sure we are calling the same method.
if (FromWMI->getMember() != ToWMI->getMember())
return false;
// We are going to reuse the TO-WMI, so make sure it dominates the call site.
if (!DA->properlyDominates(ToWMI, FromWMI))
return false;
SILBuilder Builder(FromAI);
// Make archetypes used by the ToAI available to the builder.
SILOpenedArchetypesTracker OpenedArchetypesTracker(*FromAI->getFunction());
OpenedArchetypesTracker.registerUsedOpenedArchetypes(ToAI);
Builder.setOpenedArchetypesTracker(&OpenedArchetypesTracker);
assert(FromAI->getArguments().size() == ToAI->getArguments().size() &&
"Invalid number of arguments");
// Don't handle any apply instructions that involve substitutions.
if (ToAI->getSubstitutions().size() != 1) return false;
// Prepare the Apply args.
SmallVector<SILValue, 8> Args;
for (auto Op : FromAI->getArguments()) {
Args.push_back(Op == From ? To : Op);
}
auto FnTy = ToAI->getSubstCalleeSILType();
auto ResTy = FnTy.castTo<SILFunctionType>()->getSILResult();
ApplyInst *NAI = Builder.createApply(ToAI->getLoc(), ToWMI, FnTy, ResTy,
ToAI->getSubstitutions(), Args,
ToAI->isNonThrowing());
FromAI->replaceAllUsesWith(NAI);
FromAI->eraseFromParent();
NumOpenExtRemoved++;
return true;
}
