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Revert "[Clang] Reduce the size of Decl and classes derived from it" (#…
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…88654)

Reverts #87361

On 32 bit platforms there is only a single bit available in the
`DeclCtx`, resulting in an assertion failure.
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@philnik777
philnik777 authored Apr 14, 2024
1 parent d48d6ba commit ed06b84
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Showing 3 changed files with 35 additions and 70 deletions.
72 changes: 25 additions & 47 deletions clang/include/clang/AST/DeclBase.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -268,37 +268,17 @@ class alignas(8) Decl {
/// }
/// void A::f(); // SemanticDC == namespace 'A'
/// // LexicalDC == global namespace
llvm::PointerUnion<DeclContext*, MultipleDC*> DeclCtx;

// Compress the InvalidDecl and HasAttrs bits into DeclCtx to keep Decl below
// 32 bytes in size
llvm::PointerIntPair<
llvm::PointerIntPair<llvm::PointerUnion<DeclContext *, MultipleDC *>, 1,
bool>,
1, bool>
DeclCtxWithInvalidDeclAndHasAttrs;

bool isInSemaDC() const {
return DeclCtxWithInvalidDeclAndHasAttrs.getPointer()
.getPointer()
.is<DeclContext *>();
}

bool isOutOfSemaDC() const {
return DeclCtxWithInvalidDeclAndHasAttrs.getPointer()
.getPointer()
.is<MultipleDC *>();
}
bool isInSemaDC() const { return DeclCtx.is<DeclContext*>(); }
bool isOutOfSemaDC() const { return DeclCtx.is<MultipleDC*>(); }

MultipleDC *getMultipleDC() const {
return DeclCtxWithInvalidDeclAndHasAttrs.getPointer()
.getPointer()
.get<MultipleDC *>();
return DeclCtx.get<MultipleDC*>();
}

DeclContext *getSemanticDC() const {
return DeclCtxWithInvalidDeclAndHasAttrs.getPointer()
.getPointer()
.get<DeclContext *>();
return DeclCtx.get<DeclContext*>();
}

/// Loc - The location of this decl.
Expand All @@ -308,6 +288,14 @@ class alignas(8) Decl {
LLVM_PREFERRED_TYPE(Kind)
unsigned DeclKind : 7;

/// InvalidDecl - This indicates a semantic error occurred.
LLVM_PREFERRED_TYPE(bool)
unsigned InvalidDecl : 1;

/// HasAttrs - This indicates whether the decl has attributes or not.
LLVM_PREFERRED_TYPE(bool)
unsigned HasAttrs : 1;

/// Implicit - Whether this declaration was implicitly generated by
/// the implementation rather than explicitly written by the user.
LLVM_PREFERRED_TYPE(bool)
Expand Down Expand Up @@ -405,22 +393,21 @@ class alignas(8) Decl {
protected:
Decl(Kind DK, DeclContext *DC, SourceLocation L)
: NextInContextAndBits(nullptr, getModuleOwnershipKindForChildOf(DC)),
DeclCtxWithInvalidDeclAndHasAttrs({DC, false}, false), Loc(L),
DeclKind(DK), Implicit(false), Used(false), Referenced(false),
DeclCtx(DC), Loc(L), DeclKind(DK), InvalidDecl(false), HasAttrs(false),
Implicit(false), Used(false), Referenced(false),
TopLevelDeclInObjCContainer(false), Access(AS_none), FromASTFile(0),
IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
CacheValidAndLinkage(llvm::to_underlying(Linkage::Invalid)) {
if (StatisticsEnabled)
add(DK);
if (StatisticsEnabled) add(DK);
}

Decl(Kind DK, EmptyShell Empty)
: DeclKind(DK), Implicit(false), Used(false), Referenced(false),
TopLevelDeclInObjCContainer(false), Access(AS_none), FromASTFile(0),
: DeclKind(DK), InvalidDecl(false), HasAttrs(false), Implicit(false),
Used(false), Referenced(false), TopLevelDeclInObjCContainer(false),
Access(AS_none), FromASTFile(0),
IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
CacheValidAndLinkage(llvm::to_underlying(Linkage::Invalid)) {
if (StatisticsEnabled)
add(DK);
if (StatisticsEnabled) add(DK);
}

virtual ~Decl();
Expand Down Expand Up @@ -533,9 +520,7 @@ class alignas(8) Decl {
return AccessSpecifier(Access);
}

bool hasAttrs() const {
return DeclCtxWithInvalidDeclAndHasAttrs.getPointer().getInt();
}
bool hasAttrs() const { return HasAttrs; }

void setAttrs(const AttrVec& Attrs) {
return setAttrsImpl(Attrs, getASTContext());
Expand Down Expand Up @@ -564,17 +549,13 @@ class alignas(8) Decl {
}

template <typename... Ts> void dropAttrs() {
if (!hasAttrs())
return;
if (!HasAttrs) return;

AttrVec &Vec = getAttrs();
llvm::erase_if(Vec, [](Attr *A) { return isa<Ts...>(A); });

if (Vec.empty()) {
auto InnerPtr = DeclCtxWithInvalidDeclAndHasAttrs.getPointer();
InnerPtr.setInt(false);
DeclCtxWithInvalidDeclAndHasAttrs.setPointer(InnerPtr);
}
if (Vec.empty())
HasAttrs = false;
}

template <typename T> void dropAttr() { dropAttrs<T>(); }
Expand Down Expand Up @@ -609,10 +590,7 @@ class alignas(8) Decl {
/// setInvalidDecl - Indicates the Decl had a semantic error. This
/// allows for graceful error recovery.
void setInvalidDecl(bool Invalid = true);

bool isInvalidDecl() const {
return DeclCtxWithInvalidDeclAndHasAttrs.getInt();
}
bool isInvalidDecl() const { return (bool) InvalidDecl; }

/// isImplicit - Indicates whether the declaration was implicitly
/// generated by the implementation. If false, this declaration
Expand Down
31 changes: 9 additions & 22 deletions clang/lib/AST/DeclBase.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -52,8 +52,6 @@

using namespace clang;

static_assert(sizeof(Decl) <= 32, "Decl grew beyond 32 bytes!");

//===----------------------------------------------------------------------===//
// Statistics
//===----------------------------------------------------------------------===//
Expand Down Expand Up @@ -132,7 +130,7 @@ const char *Decl::getDeclKindName() const {
}

void Decl::setInvalidDecl(bool Invalid) {
DeclCtxWithInvalidDeclAndHasAttrs.setInt(Invalid);
InvalidDecl = Invalid;
assert(!isa<TagDecl>(this) || !cast<TagDecl>(this)->isCompleteDefinition());
if (!Invalid) {
return;
Expand Down Expand Up @@ -336,9 +334,7 @@ void PrettyStackTraceDecl::print(raw_ostream &OS) const {
Decl::~Decl() = default;

void Decl::setDeclContext(DeclContext *DC) {
auto InnerPtr = DeclCtxWithInvalidDeclAndHasAttrs.getPointer();
InnerPtr.setPointer(DC);
DeclCtxWithInvalidDeclAndHasAttrs.setPointer(InnerPtr);
DeclCtx = DC;
}

void Decl::setLexicalDeclContext(DeclContext *DC) {
Expand Down Expand Up @@ -368,16 +364,12 @@ void Decl::setLexicalDeclContext(DeclContext *DC) {
void Decl::setDeclContextsImpl(DeclContext *SemaDC, DeclContext *LexicalDC,
ASTContext &Ctx) {
if (SemaDC == LexicalDC) {
auto InnerPtr = DeclCtxWithInvalidDeclAndHasAttrs.getPointer();
InnerPtr.setPointer(SemaDC);
DeclCtxWithInvalidDeclAndHasAttrs.setPointer(InnerPtr);
DeclCtx = SemaDC;
} else {
auto *MDC = new (Ctx) Decl::MultipleDC();
MDC->SemanticDC = SemaDC;
MDC->LexicalDC = LexicalDC;
auto InnerPtr = DeclCtxWithInvalidDeclAndHasAttrs.getPointer();
InnerPtr.setPointer(MDC);
DeclCtxWithInvalidDeclAndHasAttrs.setPointer(InnerPtr);
DeclCtx = MDC;
}
}

Expand Down Expand Up @@ -964,24 +956,19 @@ unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
}

void Decl::setAttrsImpl(const AttrVec &attrs, ASTContext &Ctx) {
assert(!hasAttrs() && "Decl already contains attrs.");
assert(!HasAttrs && "Decl already contains attrs.");

AttrVec &AttrBlank = Ctx.getDeclAttrs(this);
assert(AttrBlank.empty() && "HasAttrs was wrong?");

AttrBlank = attrs;
auto InnerPtr = DeclCtxWithInvalidDeclAndHasAttrs.getPointer();
InnerPtr.setInt(true);
DeclCtxWithInvalidDeclAndHasAttrs.setPointer(InnerPtr);
HasAttrs = true;
}

void Decl::dropAttrs() {
if (!hasAttrs())
return;
if (!HasAttrs) return;

auto InnerPtr = DeclCtxWithInvalidDeclAndHasAttrs.getPointer();
InnerPtr.setInt(false);
DeclCtxWithInvalidDeclAndHasAttrs.setPointer(InnerPtr);
HasAttrs = false;
getASTContext().eraseDeclAttrs(this);
}

Expand Down Expand Up @@ -1009,7 +996,7 @@ void Decl::addAttr(Attr *A) {
}

const AttrVec &Decl::getAttrs() const {
assert(hasAttrs() && "No attrs to get!");
assert(HasAttrs && "No attrs to get!");
return getASTContext().getDeclAttrs(this);
}

Expand Down
2 changes: 1 addition & 1 deletion clang/lib/Serialization/ASTReaderDecl.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -588,7 +588,7 @@ void ASTDeclReader::VisitDecl(Decl *D) {
bool HasStandaloneLexicalDC = DeclBits.getNextBit();
bool HasAttrs = DeclBits.getNextBit();
D->setTopLevelDeclInObjCContainer(DeclBits.getNextBit());
D->DeclCtxWithInvalidDeclAndHasAttrs.setInt(DeclBits.getNextBit());
D->InvalidDecl = DeclBits.getNextBit();
D->FromASTFile = true;

if (D->isTemplateParameter() || D->isTemplateParameterPack() ||
Expand Down

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