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[IRGen] Emit null check before swift_conformsToProtocol for nullable … #82240

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[IRGen] Emit null check before swift_conformsToProtocol for nullable … #82240

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49 changes: 39 additions & 10 deletions lib/IRGen/GenCast.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -544,8 +544,8 @@ llvm::Value *irgen::emitMetatypeToAnyObjectDowncast(IRGenFunction &IGF,
/// Emit a checked cast to a protocol or protocol composition.
void irgen::emitScalarExistentialDowncast(
IRGenFunction &IGF, llvm::Value *value, SILType srcType, SILType destType,
CheckedCastMode mode, std::optional<MetatypeRepresentation> metatypeKind,
Explosion &ex) {
CheckedCastMode mode, bool sourceWrappedInOptional,
std::optional<MetatypeRepresentation> metatypeKind, Explosion &ex) {
auto srcInstanceType = srcType.getASTType();
auto destInstanceType = destType.getASTType();
while (auto metatypeType = dyn_cast<ExistentialMetatypeType>(
Expand Down Expand Up @@ -800,7 +800,36 @@ void irgen::emitScalarExistentialDowncast(
for (auto proto : witnessTableProtos)
args.push_back(proto);

auto valueAndWitnessTables = IGF.Builder.CreateCall(fn, args);
llvm::BasicBlock *nilCheckedCont = nullptr;
llvm::BasicBlock *nilBB = nullptr;
llvm::BasicBlock *nonNilBB = nullptr;
if (sourceWrappedInOptional) {
nilBB = IGF.createBasicBlock("is-nil");
nonNilBB = IGF.createBasicBlock("is-non-nil");
nilCheckedCont = IGF.createBasicBlock("nil-checked-cont");

auto isNotNil = IGF.Builder.CreateICmpNE(
metadataValue, llvm::ConstantPointerNull::get(
cast<llvm::PointerType>(IGF.IGM.Int8PtrTy)));

IGF.Builder.CreateCondBr(isNotNil, nonNilBB, nilBB);
IGF.Builder.emitBlock(nilBB);
IGF.Builder.CreateBr(nilCheckedCont);
IGF.Builder.emitBlock(nonNilBB);
}

llvm::Value *valueAndWitnessTables = IGF.Builder.CreateCall(fn, args);

if (nilCheckedCont) {
IGF.Builder.CreateBr(nilCheckedCont);
IGF.Builder.emitBlock(nilCheckedCont);
auto *returnTy = valueAndWitnessTables->getType();
auto failureVal = llvm::Constant::getNullValue(returnTy);
auto phi = IGF.Builder.CreatePHI(returnTy, 2);
phi->addIncoming(valueAndWitnessTables, nonNilBB);
phi->addIncoming(failureVal, nilBB);
valueAndWitnessTables = phi;
}

resultValue = IGF.Builder.CreateExtractValue(valueAndWitnessTables, 0);
if (resultValue->getType() != resultType)
Expand Down Expand Up @@ -945,10 +974,9 @@ void irgen::emitScalarCheckedCast(IRGenFunction &IGF,

// Casts to existential metatypes.
if (auto existential = targetLoweredType.getAs<ExistentialMetatypeType>()) {
emitScalarExistentialDowncast(IGF, metatypeVal, sourceLoweredType,
targetLoweredType, mode,
existential->getRepresentation(),
out);
emitScalarExistentialDowncast(
IGF, metatypeVal, sourceLoweredType, targetLoweredType, mode,
sourceWrappedInOptional, existential->getRepresentation(), out);
return;

// Casts to concrete metatypes.
Expand Down Expand Up @@ -1023,9 +1051,10 @@ void irgen::emitScalarCheckedCast(IRGenFunction &IGF,

if (targetFormalType.isExistentialType()) {
Explosion outRes;
emitScalarExistentialDowncast(
IGF, instance, sourceLoweredType, targetLoweredType, mode,
/*not a metatype*/ std::nullopt, outRes);
emitScalarExistentialDowncast(IGF, instance, sourceLoweredType,
targetLoweredType, mode,
/*sourceWrappedInOptional*/ false,
/*not a metatype*/ std::nullopt, outRes);
returnNilCheckedResult(IGF.Builder, outRes);
return;
}
Expand Down
4 changes: 2 additions & 2 deletions lib/IRGen/GenCast.h
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Original file line number Diff line number Diff line change
Expand Up @@ -99,8 +99,8 @@ namespace irgen {
/// not, the cast is done as a class instance cast.
void emitScalarExistentialDowncast(
IRGenFunction &IGF, llvm::Value *orig, SILType srcType, SILType destType,
CheckedCastMode mode, std::optional<MetatypeRepresentation> metatypeKind,
Explosion &ex);
CheckedCastMode mode, bool sourceWrappedInOptional,
std::optional<MetatypeRepresentation> metatypeKind, Explosion &ex);

/// Emit a checked cast from a metatype to AnyObject.
llvm::Value *emitMetatypeToAnyObjectDowncast(IRGenFunction &IGF,
Expand Down
22 changes: 22 additions & 0 deletions test/IRGen/casts.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ struct NotClass {}
class A {}
class B: A {}
final class F: A {}
protocol Q {}

sil_vtable A {}
sil_vtable B {}
Expand Down Expand Up @@ -435,3 +436,24 @@ bb2:
bb3(%11 : $Optional<C & PAnyObject>):
return %11 : $Optional<C & PAnyObject>
}

// CHECK-LABEL: define{{.*}} @checked_cast_optional_metatype
// CHECK: [[COND:%.*]] = icmp ne ptr {{%.*}}, null
// CHECK-NEXT: br i1 [[COND]], label %is-non-nil, label %is-nil
// CHECK: nil-checked-cont:
// CHECK: %4 = phi { ptr, ptr } [ {{%.*}}, %is-non-nil ], [ zeroinitializer, %is-nil ]
sil @checked_cast_optional_metatype : $@convention(thin) (Optional<@thick any Any.Type>) -> Optional<@thick any Q.Type> {
bb0(%0 : $Optional<@thick any Any.Type>):
checked_cast_br Optional<any Any.Type> in %0 to any Q.Type, bb1, bb2

bb1(%3 : $@thick any Q.Type):
%4 = enum $Optional<@thick any Q.Type>, #Optional.some!enumelt, %3
br bb3(%4)

bb2:
%6 = enum $Optional<@thick any Q.Type>, #Optional.none!enumelt
br bb3(%6)

bb3(%8 : $Optional<@thick any Q.Type>):
return %8
}