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[devirtualization] Teach devirtualization how to devirtualize inherited conformances.

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Previously if we had an inherited conformance, we would not put in an
upcast from the subtype to the parent when we called the devirtualized
protocol method.

Swift SVN r16644
This commit is contained in:
Michael Gottesman
2014-04-22 04:45:08 +00:00
parent a65a693ac9
commit 83cf951609
2 changed files with 61 additions and 5 deletions
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29
lib/SILPasses/Devirtualizer.cpp
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@@ -1216,10 +1216,11 @@ void SILDevirtualizer::optimizeApplyInst(ApplyInst *AI) {
// %9 = apply %8<Self = CodeUnit?>(%6#1) : ...
//
WitnessMethodInst *AMI = dyn_cast<WitnessMethodInst>(AI->getCallee());
if (AMI && AMI->getConformance() ) {
if (AMI && AMI->getConformance()) {
ProtocolConformance *C = AMI->getConformance();
// Lookup the function reference in the witness tables.
std::pair<SILWitnessTable *, ArrayRef<Substitution>> Ret =
AI->getModule().lookUpWitnessTable(AMI->getConformance());
AI->getModule().lookUpWitnessTable(C);
if (!Ret.first)
return;
@@ -1229,19 +1230,37 @@ void SILDevirtualizer::optimizeApplyInst(ApplyInst *AI) {
if (Entry.getKind() != SILWitnessTable::WitnessKind::Method)
continue;
SILWitnessTable::MethodWitness MethodEntry = Entry.getMethodWitness();
// Check if this is the member we were looking for.
SILWitnessTable::MethodWitness MethodEntry = Entry.getMethodWitness();
if (MethodEntry.Requirement != AMI->getMember())
continue;
// Ok, we found the member we are looking for. Devirtualize away!
SILBuilder Builder(AI);
SILLocation Loc = AI->getLoc();
SILFunction *F = MethodEntry.Witness;
FunctionRefInst *FRI = Builder.createFunctionRef(Loc, F);
// Collect the function arguments.
// Collect args from the apply inst.
ArrayRef<Operand> ApplyArgs = AI->getArgumentOperands();
SmallVector<SILValue, 4> Args;
for (auto &A : AI->getArgumentOperands())
// Begin by upcasting self to the appropriate type if we have an inherited
// conformance...
SILValue Self = ApplyArgs[0].get();
if (C->getKind() == ProtocolConformanceKind::Inherited) {
CanType Ty = Ret.first->getConformance()->getType()->getCanonicalType();
SILType SILTy = SILType::getPrimitiveType(Ty,
Self.getType().getCategory());
assert(SILTy.isSuperclassOf(Self.getType()) &&
"Should only create upcasts for sub class devirtualization.");
Self = Builder.createUpcast(Loc, Self, SILTy);
}
// and then adding in either the original or newly upcasted value.
Args.push_back(Self);
// Then add the rest of the arguments.
for (auto &A : ApplyArgs.slice(1))
Args.push_back(A.get());
SmallVector<Substitution, 16> NewSubstList(Ret.second.begin(),