[clang] Recommit "Implement [[msvc::no_unique_address]] (#65675)" (PR #67199)
via cfe-commits
cfe-commits at lists.llvm.org
Fri Sep 22 14:47:31 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
<details>
<summary>Changes</summary>
Change the attribute docs so that there is a separate one for the MSVC
attribute.
This reverts commit 71f9e7695b87298f9855d8890f0e6a3b89381eb5.
---
Patch is 25.37 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/67199.diff
9 Files Affected:
- (modified) clang/include/clang/Basic/Attr.td (+16-3)
- (modified) clang/include/clang/Basic/AttrDocs.td (+9)
- (modified) clang/lib/AST/Decl.cpp (+8-3)
- (modified) clang/lib/AST/RecordLayoutBuilder.cpp (+45-8)
- (modified) clang/lib/Parse/ParseDeclCXX.cpp (+2-1)
- (modified) clang/lib/Sema/SemaDeclAttr.cpp (+10)
- (added) clang/test/Layout/ms-no-unique-address.cpp (+381)
- (modified) clang/test/Preprocessor/has_attribute.cpp (+4-1)
- (added) clang/test/SemaCXX/cxx2a-ms-no-unique-address.cpp (+19)
``````````diff
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 21a3b5226623cf2..3da91d25ec97347 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1798,11 +1798,24 @@ def ArmMveStrictPolymorphism : TypeAttr, TargetSpecificAttr<TargetARM> {
let Documentation = [ArmMveStrictPolymorphismDocs];
}
-def NoUniqueAddress : InheritableAttr, TargetSpecificAttr<TargetItaniumCXXABI> {
- let Spellings = [CXX11<"", "no_unique_address", 201803>];
+def NoUniqueAddress : InheritableAttr {
+ let Subjects = SubjectList<[NonBitField], ErrorDiag>;
+ // No spellings because instances of this attribute are created by
+ // MSNoUniqueAddress and ItaniumNoUniqueAddress
+ let Spellings = [];
+ let Documentation = [InternalOnly];
+}
+
+def MSNoUniqueAddress : InheritableAttr, TargetSpecificAttr<TargetMicrosoftCXXABI> {
let Subjects = SubjectList<[NonBitField], ErrorDiag>;
+ let Spellings = [CXX11<"msvc", "no_unique_address", 201803>];
+ let Documentation = [MSNoUniqueAddressDocs];
+}
+
+def ItaniumNoUniqueAddress : InheritableAttr, TargetSpecificAttr<TargetItaniumCXXABI> {
+ let Subjects = SubjectList<[NonBitField], ErrorDiag>;
+ let Spellings = [CXX11<"", "no_unique_address", 201803>];
let Documentation = [NoUniqueAddressDocs];
- let SimpleHandler = 1;
}
def ReturnsTwice : InheritableAttr {
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index b13baa46754cfd4..d16ce23c067982d 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -1408,6 +1408,15 @@ in C++11 onwards.
}];
}
+def MSNoUniqueAddressDocs : Documentation {
+ let Category = DocCatField;
+ let Content = [{
+On MSVC targets, ``[[no_unique_address]]`` is ignored; use
+``[[msvc::no_unique_address]]`` instead. Currently there is no guarantee of ABI
+compatibility or stability with MSVC.
+ }];
+}
+
def ObjCRequiresSuperDocs : Documentation {
let Category = DocCatFunction;
let Content = [{
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 08ae2087cfe70eb..07aee0d87c835a8 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4507,9 +4507,14 @@ bool FieldDecl::isZeroSize(const ASTContext &Ctx) const {
// Otherwise, [...] the circumstances under which the object has zero size
// are implementation-defined.
- // FIXME: This might be Itanium ABI specific; we don't yet know what the MS
- // ABI will do.
- return true;
+ if (!Ctx.getTargetInfo().getCXXABI().isMicrosoft())
+ return true;
+
+ // MS ABI: has nonzero size if it is a class type with class type fields,
+ // whether or not they have nonzero size
+ return !llvm::any_of(CXXRD->fields(), [](const FieldDecl *Field) {
+ return Field->getType()->getAs<RecordType>();
+ });
}
bool FieldDecl::isPotentiallyOverlapping() const {
diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
index 8afd88ae7be27b3..f1f2275da44dcad 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -2545,7 +2545,10 @@ struct MicrosoftRecordLayoutBuilder {
CharUnits Alignment;
};
typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
- MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
+ MicrosoftRecordLayoutBuilder(const ASTContext &Context,
+ EmptySubobjectMap *EmptySubobjects)
+ : Context(Context), EmptySubobjects(EmptySubobjects) {}
+
private:
MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
@@ -2595,6 +2598,8 @@ struct MicrosoftRecordLayoutBuilder {
llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
const CXXRecordDecl *RD) const;
const ASTContext &Context;
+ EmptySubobjectMap *EmptySubobjects;
+
/// The size of the record being laid out.
CharUnits Size;
/// The non-virtual size of the record layout.
@@ -2908,8 +2913,7 @@ static bool recordUsesEBO(const RecordDecl *RD) {
}
void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
- const CXXRecordDecl *RD,
- const CXXRecordDecl *BaseDecl,
+ const CXXRecordDecl *RD, const CXXRecordDecl *BaseDecl,
const ASTRecordLayout &BaseLayout,
const ASTRecordLayout *&PreviousBaseLayout) {
// Insert padding between two bases if the left first one is zero sized or
@@ -2942,6 +2946,7 @@ void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
}
Bases.insert(std::make_pair(BaseDecl, BaseOffset));
Size += BaseLayout.getNonVirtualSize();
+ DataSize = Size;
PreviousBaseLayout = &BaseLayout;
}
@@ -2959,15 +2964,43 @@ void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
LastFieldIsNonZeroWidthBitfield = false;
ElementInfo Info = getAdjustedElementInfo(FD);
Alignment = std::max(Alignment, Info.Alignment);
- CharUnits FieldOffset;
- if (UseExternalLayout)
+
+ const CXXRecordDecl *FieldClass = FD->getType()->getAsCXXRecordDecl();
+ bool IsOverlappingEmptyField = FD->isPotentiallyOverlapping() &&
+ FieldClass->isEmpty() &&
+ FieldClass->fields().empty();
+ CharUnits FieldOffset = CharUnits::Zero();
+
+ if (UseExternalLayout) {
FieldOffset =
Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
- else if (IsUnion)
+ } else if (IsUnion) {
FieldOffset = CharUnits::Zero();
- else
+ } else if (EmptySubobjects) {
+ if (!IsOverlappingEmptyField)
+ FieldOffset = DataSize.alignTo(Info.Alignment);
+
+ while (!EmptySubobjects->CanPlaceFieldAtOffset(FD, FieldOffset)) {
+ const CXXRecordDecl *ParentClass = cast<CXXRecordDecl>(FD->getParent());
+ bool HasBases = ParentClass && (!ParentClass->bases().empty() ||
+ !ParentClass->vbases().empty());
+ if (FieldOffset == CharUnits::Zero() && DataSize != CharUnits::Zero() &&
+ HasBases) {
+ // MSVC appears to only do this when there are base classes;
+ // otherwise it overlaps no_unique_address fields in non-zero offsets.
+ FieldOffset = DataSize.alignTo(Info.Alignment);
+ } else {
+ FieldOffset += Info.Alignment;
+ }
+ }
+ } else {
FieldOffset = Size.alignTo(Info.Alignment);
+ }
placeFieldAtOffset(FieldOffset);
+
+ if (!IsOverlappingEmptyField)
+ DataSize = std::max(DataSize, FieldOffset + Info.Size);
+
Size = std::max(Size, FieldOffset + Info.Size);
}
@@ -3013,6 +3046,7 @@ void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
Alignment = std::max(Alignment, Info.Alignment);
RemainingBitsInField = Context.toBits(Info.Size) - Width;
}
+ DataSize = Size;
}
void
@@ -3038,6 +3072,7 @@ MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
Size = FieldOffset;
Alignment = std::max(Alignment, Info.Alignment);
}
+ DataSize = Size;
}
void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
@@ -3304,8 +3339,9 @@ ASTContext::getASTRecordLayout(const RecordDecl *D) const {
const ASTRecordLayout *NewEntry = nullptr;
if (isMsLayout(*this)) {
- MicrosoftRecordLayoutBuilder Builder(*this);
if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
+ EmptySubobjectMap EmptySubobjects(*this, RD);
+ MicrosoftRecordLayoutBuilder Builder(*this, &EmptySubobjects);
Builder.cxxLayout(RD);
NewEntry = new (*this) ASTRecordLayout(
*this, Builder.Size, Builder.Alignment, Builder.Alignment,
@@ -3317,6 +3353,7 @@ ASTContext::getASTRecordLayout(const RecordDecl *D) const {
Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
Builder.Bases, Builder.VBases);
} else {
+ MicrosoftRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
Builder.layout(D);
NewEntry = new (*this) ASTRecordLayout(
*this, Builder.Size, Builder.Alignment, Builder.Alignment,
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 5a6b5efbf6c1223..cc93fe7d5461967 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -4374,7 +4374,8 @@ static bool IsBuiltInOrStandardCXX11Attribute(IdentifierInfo *AttrName,
case ParsedAttr::AT_Deprecated:
case ParsedAttr::AT_FallThrough:
case ParsedAttr::AT_CXX11NoReturn:
- case ParsedAttr::AT_NoUniqueAddress:
+ case ParsedAttr::AT_MSNoUniqueAddress:
+ case ParsedAttr::AT_ItaniumNoUniqueAddress:
case ParsedAttr::AT_Likely:
case ParsedAttr::AT_Unlikely:
return true;
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 090a54eedaa07d0..f3839b2c59e0dcf 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -8372,6 +8372,10 @@ static void handleNoMergeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
D->addAttr(NoMergeAttr::Create(S.Context, AL));
}
+static void handleNoUniqueAddressAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+ D->addAttr(NoUniqueAddressAttr::Create(S.Context, AL));
+}
+
static void handleSYCLKernelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
// The 'sycl_kernel' attribute applies only to function templates.
const auto *FD = cast<FunctionDecl>(D);
@@ -9277,6 +9281,12 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
case ParsedAttr::AT_NoMerge:
handleNoMergeAttr(S, D, AL);
break;
+ case ParsedAttr::AT_MSNoUniqueAddress:
+ handleNoUniqueAddressAttr(S, D, AL);
+ break;
+ case ParsedAttr::AT_ItaniumNoUniqueAddress:
+ handleNoUniqueAddressAttr(S, D, AL);
+ break;
case ParsedAttr::AT_AvailableOnlyInDefaultEvalMethod:
handleAvailableOnlyInDefaultEvalMethod(S, D, AL);
diff --git a/clang/test/Layout/ms-no-unique-address.cpp b/clang/test/Layout/ms-no-unique-address.cpp
new file mode 100644
index 000000000000000..51cfd9a6ae3b77f
--- /dev/null
+++ b/clang/test/Layout/ms-no-unique-address.cpp
@@ -0,0 +1,381 @@
+// RUN: %clang_cc1 -std=c++2a -fsyntax-only -triple x86_64-windows-msvc -fms-compatibility -fdump-record-layouts %s | FileCheck %s
+
+namespace Empty {
+ struct A {};
+ struct A2 {};
+ struct A3 { [[msvc::no_unique_address]] A a; };
+ struct alignas(8) A4 {};
+
+ struct B {
+ [[msvc::no_unique_address]] A a;
+ char b;
+ };
+ static_assert(sizeof(B) == 1);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::B
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: 0 | char b
+ // CHECK-NEXT: | [sizeof=1, align=1,
+ // CHECK-NEXT: | nvsize=1, nvalign=1]
+
+ struct C {
+ [[msvc::no_unique_address]] A a;
+ [[msvc::no_unique_address]] A2 a2;
+ char c;
+ };
+ static_assert(sizeof(C) == 1);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::C
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: 0 | struct Empty::A2 a2 (empty)
+ // CHECK-NEXT: 0 | char c
+ // CHECK-NEXT: | [sizeof=1, align=1,
+ // CHECK-NEXT: | nvsize=1, nvalign=1]
+
+ struct D {
+ [[msvc::no_unique_address]] A3 a;
+ int i;
+ };
+ static_assert(sizeof(D) == 8);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::D
+ // CHECK-NEXT: 0 | struct Empty::A3 a (empty)
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: 4 | int i
+ // CHECK-NEXT: | [sizeof=8, align=4,
+ // CHECK-NEXT: | nvsize=8, nvalign=4]
+
+ struct E {
+ [[msvc::no_unique_address]] A a1;
+ [[msvc::no_unique_address]] A a2;
+ char e;
+ };
+ static_assert(sizeof(E) == 2);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::E
+ // CHECK-NEXT: 0 | struct Empty::A a1 (empty)
+ // CHECK-NEXT: 1 | struct Empty::A a2 (empty)
+ // CHECK-NEXT: 0 | char e
+ // CHECK-NEXT: | [sizeof=2, align=1,
+ // CHECK-NEXT: | nvsize=2, nvalign=1]
+
+ struct F {
+ ~F();
+ [[msvc::no_unique_address]] A a1;
+ [[msvc::no_unique_address]] A a2;
+ char f;
+ };
+ static_assert(sizeof(F) == 2);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::F
+ // CHECK-NEXT: 0 | struct Empty::A a1 (empty)
+ // CHECK-NEXT: 1 | struct Empty::A a2 (empty)
+ // CHECK-NEXT: 0 | char f
+ // CHECK-NEXT: | [sizeof=2, align=1,
+ // CHECK-NEXT: | nvsize=2, nvalign=1]
+
+ struct G { [[msvc::no_unique_address]] A a; ~G(); };
+ static_assert(sizeof(G) == 1);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::G
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: | [sizeof=1, align=1,
+ // CHECK-NEXT: | nvsize=1, nvalign=1]
+
+ struct H {
+ [[msvc::no_unique_address]] A a;
+ [[msvc::no_unique_address]] A b;
+ ~H();
+ };
+ static_assert(sizeof(H) == 2);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::H
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: 1 | struct Empty::A b (empty)
+ // CHECK-NEXT: | [sizeof=2, align=1,
+ // CHECK-NEXT: | nvsize=2, nvalign=1]
+
+ struct I {
+ [[msvc::no_unique_address]] A4 a;
+ [[msvc::no_unique_address]] A4 b;
+ };
+ static_assert(sizeof(I) == 16);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::I
+ // CHECK-NEXT: 0 | struct Empty::A4 a (empty)
+ // CHECK-NEXT: 8 | struct Empty::A4 b (empty)
+ // CHECK-NEXT: | [sizeof=16, align=8,
+ // CHECK-NEXT: | nvsize=16, nvalign=8]
+
+ struct J {
+ [[msvc::no_unique_address]] A4 a;
+ A4 b;
+ };
+ static_assert(sizeof(J) == 16);
+
+ // MSVC puts a and b at the same offset.
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::J
+ // CHECK-NEXT: 0 | struct Empty::A4 a (empty)
+ // CHECK-NEXT: 8 | struct Empty::A4 b (empty)
+ // CHECK-NEXT: | [sizeof=16, align=8,
+ // CHECK-NEXT: | nvsize=16, nvalign=8]
+
+ struct K {
+ [[msvc::no_unique_address]] A4 a;
+ [[msvc::no_unique_address]] char c;
+ [[msvc::no_unique_address]] A4 b;
+ };
+ static_assert(sizeof(K) == 16);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::K
+ // CHECK-NEXT: 0 | struct Empty::A4 a (empty)
+ // CHECK-NEXT: 0 | char c
+ // CHECK-NEXT: 8 | struct Empty::A4 b (empty)
+ // CHECK-NEXT: | [sizeof=16, align=8,
+ // CHECK-NEXT: | nvsize=16, nvalign=8]
+
+ struct OversizedEmpty : A {
+ ~OversizedEmpty();
+ [[msvc::no_unique_address]] A a;
+ };
+ static_assert(sizeof(OversizedEmpty) == 1);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::OversizedEmpty
+ // CHECK-NEXT: 0 | struct Empty::A (base) (empty)
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: | [sizeof=1, align=1,
+ // CHECK-NEXT: | nvsize=1, nvalign=1]
+
+ struct HasOversizedEmpty {
+ [[msvc::no_unique_address]] OversizedEmpty m;
+ };
+ static_assert(sizeof(HasOversizedEmpty) == 1);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::HasOversizedEmpty
+ // CHECK-NEXT: 0 | struct Empty::OversizedEmpty m (empty)
+ // CHECK-NEXT: 0 | struct Empty::A (base) (empty)
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: | [sizeof=1, align=1,
+ // CHECK-NEXT: | nvsize=1, nvalign=1]
+
+ struct EmptyWithNonzeroDSize {
+ [[msvc::no_unique_address]] A a;
+ int x;
+ [[msvc::no_unique_address]] A b;
+ int y;
+ [[msvc::no_unique_address]] A c;
+ };
+ static_assert(sizeof(EmptyWithNonzeroDSize) == 8);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::EmptyWithNonzeroDSize
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: 0 | int x
+ // CHECK-NEXT: 1 | struct Empty::A b (empty)
+ // CHECK-NEXT: 4 | int y
+ // CHECK-NEXT: 2 | struct Empty::A c (empty)
+ // CHECK-NEXT: | [sizeof=8, align=4,
+ // CHECK-NEXT: | nvsize=8, nvalign=4]
+
+ struct EmptyWithNonzeroDSizeNonPOD {
+ ~EmptyWithNonzeroDSizeNonPOD();
+ [[msvc::no_unique_address]] A a;
+ int x;
+ [[msvc::no_unique_address]] A b;
+ int y;
+ [[msvc::no_unique_address]] A c;
+ };
+ static_assert(sizeof(EmptyWithNonzeroDSizeNonPOD) == 8);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct Empty::EmptyWithNonzeroDSizeNonPOD
+ // CHECK-NEXT: 0 | struct Empty::A a (empty)
+ // CHECK-NEXT: 0 | int x
+ // CHECK-NEXT: 1 | struct Empty::A b (empty)
+ // CHECK-NEXT: 4 | int y
+ // CHECK-NEXT: 2 | struct Empty::A c (empty)
+ // CHECK-NEXT: | [sizeof=8, align=4,
+ // CHECK-NEXT: | nvsize=8, nvalign=4]
+}
+
+namespace POD {
+ struct A { int n; char c[3]; };
+ struct B { [[msvc::no_unique_address]] A a; char d; };
+ static_assert(sizeof(B) == 12);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct POD::B
+ // CHECK-NEXT: 0 | struct POD::A a
+ // CHECK-NEXT: 0 | int n
+ // CHECK-NEXT: 4 | char[3] c
+ // CHECK-NEXT: 8 | char d
+ // CHECK-NEXT: | [sizeof=12, align=4,
+ // CHECK-NEXT: | nvsize=12, nvalign=4]
+}
+
+namespace NonPOD {
+ struct A { int n; char c[3]; ~A(); };
+ struct B { [[msvc::no_unique_address]] A a; char d; };
+ static_assert(sizeof(B) == 12);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct NonPOD::B
+ // CHECK-NEXT: 0 | struct NonPOD::A a
+ // CHECK-NEXT: 0 | int n
+ // CHECK-NEXT: 4 | char[3] c
+ // CHECK-NEXT: 8 | char d
+ // CHECK-NEXT: | [sizeof=12, align=4,
+ // CHECK-NEXT: | nvsize=12, nvalign=4]
+}
+
+namespace VBases {
+ // The nvsize of an object includes the complete size of its empty subobjects
+ // (although it's unclear why). Ensure this corner case is handled properly.
+ struct Empty {};
+ struct alignas(8) A {}; // dsize 0, nvsize 0, size 8
+ struct B : A { char c; }; // dsize 1, nvsize 8, size 8
+ static_assert(sizeof(B) == 8);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct VBases::B
+ // CHECK-NEXT: 0 | struct VBases::A (base) (empty)
+ // CHECK-NEXT: 0 | char c
+ // CHECK-NEXT: | [sizeof=8, align=8,
+ // CHECK-NEXT: | nvsize=8, nvalign=8]
+
+ struct V { int n; };
+
+ struct C : B, virtual V {};
+ static_assert(sizeof(C) == 24);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct VBases::C
+ // CHECK-NEXT: 0 | struct VBases::B (base)
+ // CHECK-NEXT: 0 | struct VBases::A (base) (empty)
+ // CHECK-NEXT: 0 | char c
+ // CHECK-NEXT: 8 | (C vbtable pointer)
+ // CHECK-NEXT: 16 | struct VBases::V (virtual base)
+ // CHECK-NEXT: 16 | int n
+ // CHECK-NEXT: | [sizeof=24, align=8,
+ // CHECK-NEXT: | nvsize=16, nvalign=8]
+
+ struct D : virtual Empty {
+ [[msvc::no_unique_address]] Empty a;
+ };
+ static_assert(sizeof(D) == 16);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct VBases::D
+ // CHECK-NEXT: 0 | (D vbtable pointer)
+ // CHECK-NEXT: 8 | struct VBases::Empty a
+ // CHECK-NEXT: 16 | struct VBases::Empty (virtual base) (empty)
+ // CHECK-NEXT: | [sizeof=16, align=8,
+ // CHECK-NEXT: | nvsize=16, nvalign=8]
+
+ struct E : virtual V {
+ [[msvc::no_unique_address]] B b;
+ };
+ static_assert(sizeof(E) == 24);
+
+ // CHECK:*** Dumping AST Record Layout
+ // CHECK: 0 | struct VBases::E
+ // CHECK-NEXT: 0 | (E vbtable pointer)
+ // CHECK-NEXT: 8 | struct VBases::B b
+ // CHECK-NEXT: 8 | struct VBases::A (base) (empty)
+ // CHECK-NEXT: 8 | char c
+ // CHECK-NEXT: 16 | struct VBases::V (virtual base)
+ // CHECK-NEXT: 16 | int n
+ // CHECK-NEXT: | [sizeof=24, align=8,
+ // CHECK-NEXT: | nvsize=16, nvalign=8]
+
+ struct X : virtual A { [[msvc::no_unique_address]] A a; };
+ struct F : virtual ...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/67199
More information about the cfe-commits
mailing list