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[Concurrency] Don't attempt to hop to executor inside default argument generators and stored property initializers. #72332

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Merged
merged 1 commit into from
Mar 15, 2024
Merged

[Concurrency] Don't attempt to hop to executor inside default argument generators and stored property initializers. #72332

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54 changes: 33 additions & 21 deletions lib/SILGen/SILGenApply.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3045,35 +3045,47 @@ static void emitDelayedArguments(SILGenFunction &SGF,
done:

if (defaultArgIsolation) {
assert(SGF.F.isAsync());
assert(!isolatedArgs.empty());

auto &firstArg = *std::get<0>(isolatedArgs[0]);
auto loc = firstArg.getDefaultArgLoc();
// Only hop to the default arg isolation if the callee is async.
// If we're in a synchronous function, the isolation has to match,
// so no hop is required. This is enforced by the actor isolation
// checker.
//
// FIXME: Note that we don't end up in this situation for user-written
// synchronous functions, because the default argument is only considered
// isolated to the callee if the call crosses an isolation boundary. We
// do end up here for default argument generators and stored property
// initializers. An alternative (and better) approach is to formally model
// those generator functions as isolated.
if (SGF.F.isAsync()) {
auto &firstArg = *std::get<0>(isolatedArgs[0]);
auto loc = firstArg.getDefaultArgLoc();

SILValue executor;
switch (*defaultArgIsolation) {
case ActorIsolation::GlobalActor:
executor = SGF.emitLoadGlobalActorExecutor(
defaultArgIsolation->getGlobalActor());
break;

SILValue executor;
switch (*defaultArgIsolation) {
case ActorIsolation::GlobalActor:
executor = SGF.emitLoadGlobalActorExecutor(
defaultArgIsolation->getGlobalActor());
break;
case ActorIsolation::ActorInstance:
llvm_unreachable("default arg cannot be actor instance isolated");

case ActorIsolation::ActorInstance:
llvm_unreachable("default arg cannot be actor instance isolated");
case ActorIsolation::Erased:
llvm_unreachable("default arg cannot have erased isolation");

case ActorIsolation::Erased:
llvm_unreachable("default arg cannot have erased isolation");
case ActorIsolation::Unspecified:
case ActorIsolation::Nonisolated:
case ActorIsolation::NonisolatedUnsafe:
llvm_unreachable("Not isolated");
}

case ActorIsolation::Unspecified:
case ActorIsolation::Nonisolated:
case ActorIsolation::NonisolatedUnsafe:
llvm_unreachable("Not isolated");
// Hop to the target isolation domain once to evaluate all
// default arguments.
SGF.emitHopToTargetExecutor(loc, executor);
}

// Hop to the target isolation domain once to evaluate all
// default arguments.
SGF.emitHopToTargetExecutor(loc, executor);

size_t argsEmitted = 0;
for (auto &isolatedArg : isolatedArgs) {
auto &delayedArg = *std::get<0>(isolatedArg);
Expand Down
25 changes: 23 additions & 2 deletions test/Concurrency/isolated_default_argument_eval.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,12 @@
@MainActor
func requiresMainActor() -> Int { 0 }

// CHECK-LABEL: sil hidden [ossa] @$s30isolated_default_argument_eval19mainActorDefaultArg5valueS2i_tFfA_
@discardableResult
@MainActor
func mainActorDefaultArg(value: Int = requiresMainActor()) {}
func mainActorDefaultArg(value: Int = requiresMainActor()) -> Int {
value
}

@MainActor
func mainActorMultiDefaultArg(x: Int = requiresMainActor(),
Expand All @@ -25,7 +29,7 @@ func mainActorMultiDefaultArg(x: Int = requiresMainActor(),
func nonisolatedAsyncCaller() async {
// CHECK: hop_to_executor {{.*}} : $Optional<Builtin.Executor>
// CHECK: hop_to_executor {{.*}} : $MainActor
// CHECK: [[GET_VALUE:%[0-9]+]] = function_ref @$s30isolated_default_argument_eval19mainActorDefaultArg5valueySi_tFfA_
// CHECK: [[GET_VALUE:%[0-9]+]] = function_ref @$s30isolated_default_argument_eval19mainActorDefaultArg5valueS2i_tFfA_
// CHECK-NEXT: apply [[GET_VALUE]]()
// CHECK: hop_to_executor {{.*}} : $Optional<Builtin.Executor>
await mainActorDefaultArg()
Expand Down Expand Up @@ -68,3 +72,20 @@ func passInoutWithDefault() async {
// CHECK: hop_to_executor {{.*}} : $Optional<Builtin.Executor>
await isolatedDefaultInoutMix(x: &x, y: argValue)
}

// default argument 0 of noSuspensionInDefaultArgGenerator(_:)
// CHECK-LABEL: sil hidden [ossa] @$s30isolated_default_argument_eval33noSuspensionInDefaultArgGeneratoryySiFfA_
// CHECK: [[NESTED_DEFAULT_REF:%[0-9]+]] = function_ref @$s30isolated_default_argument_eval19mainActorDefaultArg5valueS2i_tFfA_ : $@convention(thin) () -> Int
// CHECK-NEXT: [[NESTED_DEFAULT:%[0-9]+]] = apply [[NESTED_DEFAULT_REF]]() : $@convention(thin) () -> Int
// CHECK: [[DEFAULT_REF:%[0-9]+]] = function_ref @$s30isolated_default_argument_eval19mainActorDefaultArg5valueS2i_tF : $@convention(thin) (Int) -> Int
// CHECK-NEXT: [[RESULT:%[0-9]+]] = apply [[DEFAULT_REF]]([[NESTED_DEFAULT]]) : $@convention(thin) (Int) -> Int
// CHECK-NEXT: return [[RESULT]] : $Int

// CHECK-LABEL: sil hidden [ossa] @$s30isolated_default_argument_eval33noSuspensionInDefaultArgGeneratoryySiF
@MainActor func noSuspensionInDefaultArgGenerator(
_ x: Int = mainActorDefaultArg()
) {}

func testNoSuspensionInDefaultArgGenerator() async {
await noSuspensionInDefaultArgGenerator()
}