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[Debug Info] Do not emit children of bound generic types #80078

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Merged
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Mar 19, 2025
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[Debug Info] Do not emit children of bound generic types #80078

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42 changes: 25 additions & 17 deletions lib/IRGen/IRGenDebugInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1226,8 +1226,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
return DITy;
}

std::pair<bool, Type>
getUnsubstituedType(Type Ty, StringRef MangledName) {
std::pair<bool, Type> getUnsubstitutedType(Type Ty, StringRef MangledName) {
if (!Ty)
return {false,{}};
// Go from Pair<Int, Double> to Pair<T, U>.
Expand All @@ -1252,7 +1251,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
llvm::DIScope *Scope, llvm::DIFile *File,
unsigned Line, llvm::DINode::DIFlags Flags) {
auto [IsUnsubstituted, UnsubstitutedTy] =
getUnsubstituedType(EnumTy, MangledName);
getUnsubstitutedType(EnumTy, MangledName);
auto UnsubstitutedDbgTy = DebugTypeInfo::getFromTypeInfo(
UnsubstitutedTy, IGM.getTypeInfoForUnlowered(UnsubstitutedTy), IGM);
if (IsUnsubstituted)
Expand Down Expand Up @@ -1301,7 +1300,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
Name);

auto [IsUnsubstitued, UnsubstitutedType] =
getUnsubstituedType(Type, MangledName);
getUnsubstitutedType(Type, MangledName);
auto UnsubstitutedDbgTy = DebugTypeInfo::getFromTypeInfo(
UnsubstitutedType, IGM.getTypeInfoForUnlowered(UnsubstitutedType), IGM);
if (IsUnsubstitued)
Expand All @@ -1326,19 +1325,24 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
}
}

// Recursive types such as `class A<B> { let a : A<A<B>> }` would produce an
// infinite chain of expansions for the type of `a`. Break these cycles by
// emitting any bound generics that still have type parameters as forward
// declarations.
if (Type->hasTypeParameter() || Type->hasPrimaryArchetype())
return createOpaqueStructWithSizedContainer(
Scope, Decl ? Decl->getNameStr() : "", File, Line, SizeInBits,
AlignInBits, Flags, MangledName, collectGenericParams(Type, true),
UnsubstitutedDITy);
// Generally, we don't emit members of a specialized bound generic, because
// these can be reconstructed by substituting the "template parameters" in
// the unspecialized type. We make an exception for inline arrays, because
// DWARF has special support for arrays.
if (Type->isInlineArray() && !Type->hasTypeParameter() &&
!Type->hasPrimaryArchetype())
// Create the substituted type.
return createStructType(Type, Decl, Scope, File, Line, SizeInBits,
AlignInBits, Flags, MangledName,
UnsubstitutedDITy);

// Create the substituted type.
return createStructType(Type, Decl, Scope, File, Line, SizeInBits,
AlignInBits, Flags, MangledName, UnsubstitutedDITy);
// Create the substituted type (without members).
llvm::DIType *SpecializedDITy = createOpaqueStructWithSizedContainer(
Scope, Decl ? Decl->getNameStr() : "", File, Line, SizeInBits,
AlignInBits, Flags, MangledName, collectGenericParams(Type),
UnsubstitutedDITy);
DBuilder.replaceTemporary(std::move(FwdDecl), SpecializedDITy);
return SpecializedDITy;
}

/// Create debug information for an enum with a raw type (enum E : Int {}).
Expand Down Expand Up @@ -1600,6 +1604,10 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {

llvm::Metadata *Elements[] = {DBuilder.createMemberType(
Scope, "", File, 0, SizeInBits, AlignInBits, 0, Flags, UniqueType)};
// FIXME: It's a limitation of LLVM that a forward declaration cannot have a
// specificationOf, so this attritbute is put on the sized container type
// instead. This is confusing consumers, and LLDB has to go out of its way
// to parse these confusing types as intended.
return DBuilder.createStructType(
Scope, "", File, Line, SizeInBits, AlignInBits, Flags,
/* DerivedFrom */ nullptr, DBuilder.getOrCreateArray(Elements),
Expand Down Expand Up @@ -2338,7 +2346,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
if (!isa<llvm::DICompositeType>(CachedType))
return true;
bool IsUnsubstituted =
getUnsubstituedType(DbgTy.getType(), getMangledName(DbgTy).Canonical)
getUnsubstitutedType(DbgTy.getType(), getMangledName(DbgTy).Canonical)
.first;
std::optional<uint64_t> SizeInBits;
if (!IsUnsubstituted)
Expand Down
8 changes: 5 additions & 3 deletions test/DebugInfo/BoundGenericStruct.swift
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Expand Up @@ -12,7 +12,7 @@ public let s = S<Int>(t: 0)
// CHECK: ![[INTPARAM]] = !DITemplateTypeParameter(type: ![[INT:[0-9]+]])
// CHECK: ![[INT]] = !DICompositeType(tag: DW_TAG_structure_type, {{.*}}"$sSiD"

// DWARF-DAG: !DICompositeType(tag: DW_TAG_structure_type, {{.*}}templateParams: ![[PARAMS:[0-9]+]]{{.*}}identifier: "$s18BoundGenericStruct1SVySiGD"{{.*}}specification:
// DWARF-DAG: !DICompositeType(tag: DW_TAG_structure_type, {{.*}}name: "$s18BoundGenericStruct1SVySiGD"{{.*}}templateParams: ![[PARAMS:[0-9]+]]

// DWARF-DAG: ![[PARAMS]] = !{![[INTPARAM:[0-9]+]]}
// DWARF-DAG: ![[INTPARAM]] = !DITemplateTypeParameter(type: ![[INT:[0-9]+]])
Expand All @@ -34,14 +34,16 @@ public let inner = S2<Double>.Inner(t:4.2)
// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "$s18BoundGenericStruct2S2VyxGD",
// CHECK-SAME: flags: DIFlagFwdDecl, runtimeLang: DW_LANG_Swift)

// DWARF-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "Inner", scope: ![[SCOPE1:[0-9]+]],{{.*}} size: 64, elements: ![[ELEMENTS1:[0-9]+]], {{.*}}templateParams: ![[PARAMS2:[0-9]+]], identifier: "$s18BoundGenericStruct2S2V5InnerVySd_GD", specification: ![[SPECIFICATION:[0-9]+]])
// DWARF-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "$s18BoundGenericStruct2S2V5InnerVySd_GD", scope: ![[SCOPE1:[0-9]+]], {{.*}}flags: DIFlagFwdDecl, runtimeLang: DW_LANG_Swift, templateParams: ![[PARAMS2:[0-9]+]])

// DWARF-DAG: ![[SCOPE1]] = !DICompositeType(tag: DW_TAG_structure_type, name: "$s18BoundGenericStruct2S2VyxGD",

// DWARF-DAG: ![[PARAMS2]] = !{![[PARAMS3:[0-9]+]]}
// DWARF-DAG: ![[PARAMS3]] = !DITemplateTypeParameter(type: ![[PARAMS4:[0-9]+]])
// DWARF-DAG: ![[PARAMS4]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Double"{{.*}} size: 64, {{.*}}runtimeLang: DW_LANG_Swift,{{.*}} identifier: "$sSdD")

// DWARF-DAG: [[SPECIFICATION]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Inner", {{.*}}runtimeLang: DW_LANG_Swift, identifier: "$s18BoundGenericStruct2S2V5InnerVyx_GD")
// DWARF-DAG: ![[SPECIFICATION:[0-9]+]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Inner", {{.*}}elements: ![[ELEMENTS1:[0-9]+]], runtimeLang: DW_LANG_Swift, identifier: "$s18BoundGenericStruct2S2V5InnerVyx_GD")
// DWARF-DAG: !DICompositeType(tag: DW_TAG_structure_type, {{.*}}line: 26, size: 64, {{.*}}specification: ![[SPECIFICATION]]

// DWARF-DAG: ![[ELEMENTS1]] = !{![[ELEMENTS2:[0-9]+]]}

Expand Down
4 changes: 2 additions & 2 deletions test/DebugInfo/embedded-recur-c-types.swift
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Expand Up @@ -23,5 +23,5 @@ typedef struct S2 {

public var v: UnsafeMutablePointer<S1_t>? = nil

// CHECK: !DICompositeType(tag: DW_TAG_structure_type, {{.*}} identifier: "$eSpySo4S1_taGD"
// CHECK: !DICompositeType(tag: DW_TAG_structure_type, {{.*}} identifier: "$eSpySo2S2VGD"
// CHECK-DAG: !DICompositeType(tag: DW_TAG_structure_type, {{.*}}name: "$eSpySo4S1_taGD"
// CHECK-DAG: !DICompositeType(tag: DW_TAG_structure_type, {{.*}}name: "$eSpySo2S2VGD"
10 changes: 5 additions & 5 deletions test/DebugInfo/typealias-recursive.swift
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Expand Up @@ -16,14 +16,14 @@ struct Traits32: TraitsProtocol {
let v : MyClass<Traits32>? = nil


// This typedef is not necessary from a semantic point of view, but the result
// of a trade-off done to preserve type sugar (= not generally canonicalizing types).
// CHECK-DAG: !DIDerivedType(tag: DW_TAG_typedef, name: "$s4main7MyClassCyAC6TraitsayAA8Traits32V_GGSgD", {{.*}}baseType: ![[CANONICAL:[0-9]+]])
// CHECK-DAG: ![[CANONICAL]] = !DICompositeType(tag: DW_TAG_structure_type, {{.*}}identifier: "$s4main7MyClassCyAA8Traits32VGSgD", specification: ![[OPTIONAL:[0-9]+]])
// CHECK-DAG: ![[CANONICAL:.*]] = !DICompositeType(tag: DW_TAG_structure_type, {{.*}}identifier: "$s4main7MyClassCyAA8Traits32VGSgD", specification: ![[OPTIONAL:[0-9]+]])

// CHECK-DAG: ![[OPTIONAL]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Optional"

// CHECK-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "MyClass", {{.*}}templateParams: ![[PARAMS:[0-9]+]], identifier: "$s4main7MyClassCyAA8Traits32VGD", specification: ![[SPEC:[0-9]+]])
// CHECK-DAG: ![[CONTAINER:.*]] = !DICompositeType(tag: DW_TAG_structure_type, {{.*}}line: 7, {{.*}}elements: ![[ELTS:[0-9]+]], runtimeLang: DW_LANG_Swift, specification: ![[SPEC:[0-9]+]])
// CHECK-DAG: ![[ELTS]] = !{![[MEMBER:[0-9]+]]}
// CHECK-DAG: ![[MEMBER]] = !DIDerivedType(tag: DW_TAG_member, {{.*}}baseType: ![[UNSIZED:[0-9]+]]
// CHECK-DAG: ![[UNSIZED]] = !DICompositeType(tag: DW_TAG_structure_type, name: "$s4main7MyClassCyAA8Traits32VGD", {{.*}}flags: DIFlagFwdDecl, runtimeLang: DW_LANG_Swift, templateParams: ![[PARAMS:[0-9]+]])
// CHECK-DAG: ![[PARAMS]] = !{![[PARAM:[0-9]+]]}
// CHECK-DAG: ![[PARAM]] = !DITemplateTypeParameter(type: ![[TRAITS32:[0-9]+]])
// CHECK-DAG: ![[TRAITS32]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Traits32"
Expand Down
6 changes: 5 additions & 1 deletion test/DebugInfo/typealias_indirect.swift
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Expand Up @@ -5,7 +5,11 @@
// we cannot preserve that LocalAlias = Bool.

// CHECK: !DIDerivedType(tag: DW_TAG_typedef, name: "$s1a10ClassAliasaD"{{.*}}baseType: ![[LOCAL_BOOLTY:[0-9]+]]
// CHECK: ![[LOCAL_BOOLTY]] = !DICompositeType(tag: DW_TAG_structure_type, name: "MyClass", {{.*}}identifier: "$s1a7MyClassCyAA10LocalAliasaSbGD"
// CHECK: ![[LOCAL_BOOLTY]] = !DICompositeType(tag: DW_TAG_structure_type, {{.*}}elements: ![[ELTS:[0-9]+]], runtimeLang: DW_LANG_Swift, specification: ![[SPEC:[0-9]+]])
// CHECK-DAG: ![[ELTS]] = !{![[MEMBER:[0-9]+]]}
// CHECK-DAG: ![[MEMBER]] = !DIDerivedType(tag: DW_TAG_member, {{.*}}baseType: ![[UNSIZED:[0-9]+]]
// CHECK-DAG: ![[UNSIZED]] = !DICompositeType(tag: DW_TAG_structure_type, name: "$s1a7MyClassCyAA10LocalAliasaSbGD"
// CHECK-DAG: ![[SPEC]] = !DICompositeType(tag: DW_TAG_structure_type, name: "MyClass"{{.*}}identifier: "$s1a7MyClassCyxq_GD")

// FIXME: !DIDerivedType(tag: DW_TAG_typedef, name: "$s1a10LocalAliasaD", {{.*}}baseType: ![[BASETY:[0-9]+]]
// FIXME: ![[BASETY]]{{.*}}$sSbD
Expand Down