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Optimizer: fix handling of dependent existential archetypes in alloc_stack and apply simplification #83898

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merged 2 commits into from
Aug 27, 2025
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Optimizer: fix handling of dependent existential archetypes in alloc_stack and apply simplification #83898

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0a8c602
AST: add `Type.interfaceTypeOfArchetype` and some related APIs
eeckstein Aug 25, 2025
56521f0
Optimizer: fix handling of dependent existential archetypes in `alloc…
eeckstein Aug 25, 2025
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4 changes: 4 additions & 0 deletions SwiftCompilerSources/Sources/AST/Type.swift
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Expand Up @@ -50,6 +50,8 @@ public struct Type: TypeProperties, CustomStringConvertible, NoReflectionChildre

public var staticTypeOfDynamicSelf: Type { Type(bridged: bridged.getStaticTypeOfDynamicSelf()) }

public var interfaceTypeOfArchetype: Type { Type(bridged: bridged.getInterfaceTypeOfArchetype()) }

public var superClassType: Type? {
precondition(isClass)
let bridgedSuperClassTy = bridged.getSuperClassType()
Expand Down Expand Up @@ -134,6 +136,8 @@ extension TypeProperties {
public var isArchetype: Bool { rawType.bridged.isArchetype() }
public var isExistentialArchetype: Bool { rawType.bridged.isExistentialArchetype() }
public var isExistentialArchetypeWithError: Bool { rawType.bridged.isExistentialArchetypeWithError() }
public var isRootArchetype: Bool { rawType.interfaceTypeOfArchetype.isGenericTypeParameter }
public var isRootExistentialArchetype: Bool { isExistentialArchetype && isRootArchetype }
public var isExistential: Bool { rawType.bridged.isExistential() }
public var isClassExistential: Bool { rawType.bridged.isClassExistential() }
public var isGenericTypeParameter: Bool { rawType.bridged.isGenericTypeParam() }
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3 changes: 2 additions & 1 deletion SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyAllocStack.swift
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Expand Up @@ -179,7 +179,8 @@ private extension AllocStackInst {
/// use %3
/// ```
func optimizeExistential(_ context: SimplifyContext) -> Bool {
guard type.isExistential || type.isExistentialArchetype,
// TODO: support non-root existential archetypes
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I would prefer we just fixed this with the right abstractions. You can get this from the conformance of Self to the protocol, stored in the init_existential instruction.

guard type.isExistential || type.isRootExistentialArchetype,
let concreteFormalType = getConcreteTypeOfExistential()
else {
return false
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9 changes: 5 additions & 4 deletions SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyApply.swift
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Expand Up @@ -216,8 +216,9 @@ private extension FullApplySite {
// Make sure that existential archetype _is_ a replacement type and not e.g. _contained_ in a
// replacement type, like
// apply %1<Array<@opened("...")>()
guard substitutionMap.replacementTypes.contains(where: { $0.isExistentialArchetype }),
substitutionMap.replacementTypes.allSatisfy({ $0.isExistentialArchetype || !$0.hasLocalArchetype })
// TODO: support non-root existential archetypes
guard substitutionMap.replacementTypes.contains(where: { $0.isRootExistentialArchetype }),
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Why is this a precondition?

substitutionMap.replacementTypes.allSatisfy({ $0.isRootExistentialArchetype || !$0.hasLocalArchetype })
else {
return false
}
Expand All @@ -237,9 +238,9 @@ private extension FullApplySite {
let type = value.type
// Allow three cases:
// case 1. the argument _is_ the existential archetype
return type.isExistentialArchetype ||
return type.isRootExistentialArchetype ||
// case 2. the argument _is_ a metatype of the existential archetype
(type.isMetatype && type.canonicalType.instanceTypeOfMetatype.isExistentialArchetype) ||
(type.isMetatype && type.canonicalType.instanceTypeOfMetatype.isRootExistentialArchetype) ||
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Can't you handle all the cases by transforming the type recursively?

// case 3. the argument has nothing to do with the existential archetype (or any other local archetype)
!type.hasLocalArchetype
}
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1 change: 1 addition & 0 deletions include/swift/AST/ASTBridging.h
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Expand Up @@ -3009,6 +3009,7 @@ struct BridgedASTType {
SWIFT_IMPORT_UNSAFE BRIDGED_INLINE OptionalBridgedDeclObj getAnyNominal() const;
SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedASTType getInstanceTypeOfMetatype() const;
SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedASTType getStaticTypeOfDynamicSelf() const;
SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedASTType getInterfaceTypeOfArchetype() const;
SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedASTType getSuperClassType() const;
BRIDGED_INLINE MetatypeRepresentation getRepresentationOfMetatype() const;
BRIDGED_INLINE BridgedOptionalInt getValueOfIntegerType() const;
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4 changes: 4 additions & 0 deletions include/swift/AST/ASTBridgingImpl.h
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Expand Up @@ -575,6 +575,10 @@ BridgedASTType BridgedASTType::getStaticTypeOfDynamicSelf() const {
return {unbridged()->getAs<swift::DynamicSelfType>()->getSelfType().getPointer()};
}

BridgedASTType BridgedASTType::getInterfaceTypeOfArchetype() const {
return {unbridged()->getAs<swift::ArchetypeType>()->getInterfaceType().getPointer()};
}

BridgedASTType BridgedASTType::getSuperClassType() const {
return {unbridged()->getSuperclass().getPointer()};
}
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34 changes: 34 additions & 0 deletions test/SILOptimizer/simplify_alloc_stack.sil
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Expand Up @@ -10,11 +10,27 @@ public struct S {}
protocol P {
}

protocol Q {
associatedtype A
}

public class C2: P {}

public struct T: P {
let c: C
let s: S

struct A {
var y: String
}
}

public struct U: Q {
let s: String

struct A {
var y: String
}
}

public struct T1: P {
Expand Down Expand Up @@ -235,6 +251,24 @@ bb0(%0 : @owned $T):
return %r
}

// TODO: we don't support dependent existential archetypes, yet. Once we do, change this test case.
// CHECK-LABEL: sil [ossa] @dont_replace_dependent_archetype :
// CHECK: alloc_stack {{.*}}@opened
// CHECK: } // end sil function 'dont_replace_dependent_archetype'
sil [ossa] @dont_replace_dependent_archetype : $@convention(thin) (@owned U.A) -> () {
bb0(%0 : @owned $U.A):
%1 = metatype $@thick U.Type
%2 = init_existential_metatype %1, $@thick Q.Type
%3 = open_existential_metatype %2 to $@thick (@opened("82105EE0-DCB0-11E5-865D-C8E0EB309914", Q) Self).Type
%4 = alloc_stack $(@opened("82105EE0-DCB0-11E5-865D-C8E0EB309914", Q) Self).A
%5 = unchecked_addr_cast %4 to $*U.A
store %0 to [init] %5
destroy_addr %4
dealloc_stack %4
%r = tuple ()
return %r
}

// CHECK-LABEL: sil [ossa] @replace_existential_with_concrete_type1 :
// CHECK: [[S:%.*]] = alloc_stack $T
// CHECK-NOT: init_existential_addr
Expand Down
32 changes: 32 additions & 0 deletions test/SILOptimizer/simplify_apply.sil
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Expand Up @@ -30,6 +30,21 @@ enum E: String {
case a, b, c, d, e
}

protocol P2 {
associatedtype A: Q
}

protocol Q {
}

public struct S2: P2 {
var x: String
struct A: Q {
var y: String
}
}


sil @cl : $@convention(thin) () -> Int

// CHECK-LABEL: sil [ossa] @thick_to_thin :
Expand Down Expand Up @@ -64,6 +79,7 @@ sil_vtable Bar {
}

sil @createit : $@convention(thin) <τ_0_0 where τ_0_0 : P> (@thick τ_0_0.Type, Int) -> @out τ_0_0
sil @create2 : $@convention(thin) <τ_0_0 where τ_0_0 : Q> (Int) -> @out τ_0_0
sil @useGenS : $@convention(thin) <τ_0_0 where τ_0_0 : P> (GenS<τ_0_0>) -> ()
sil @returnGenS : $@convention(thin) <τ_0_0 where τ_0_0 : P> (@thick τ_0_0.Type) -> GenS<τ_0_0>

Expand Down Expand Up @@ -128,6 +144,22 @@ bb0(%0 : $Int):
return %11
}

// TODO: we don't support dependent existential archetypes, yet. Once we do, change this test case.
// CHECK-LABEL: sil [ossa] @dont_replace_dependent_archetype :
// CHECK: apply %{{[0-9]+}}<(@opened
// CHECK: } // end sil function 'dont_replace_dependent_archetype'
sil [ossa] @dont_replace_dependent_archetype : $@convention(thin) (Int) -> @out any Q {
bb0(%0 : $*any Q, %1 : $Int):
%2 = metatype $@thick S2.Type
%3 = init_existential_metatype %2, $@thick any P2.Type
%4 = open_existential_metatype %3 to $@thick (@opened("0FC03D78-E9DB-11EF-B47C-0EA13E3AABB4", any P2) Self).Type
%6 = function_ref @create2 : $@convention(thin) <τ_0_0 where τ_0_0 : Q> (Int) -> @out τ_0_0
%7 = init_existential_addr %0, $(@opened("0FC03D78-E9DB-11EF-B47C-0EA13E3AABB4", any P2) Self).A
%8 = apply %6<(@opened("0FC03D78-E9DB-11EF-B47C-0EA13E3AABB4", any P2) Self).A>(%7, %1) : $@convention(thin) <τ_0_0 where τ_0_0 : Q> (Int) -> @out τ_0_0
%11 = tuple ()
return %11
}

// CHECK-LABEL: sil [ossa] @dont_replace_returned_embedded_archetype :
// CHECK: apply %{{[0-9]+}}<@opened
// CHECK: } // end sil function 'dont_replace_returned_embedded_archetype'
Expand Down