[clang] c3ba6f3 - [Modules] Delay deserialization of preferred_name attribute at r… (#122726)
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cfe-commits at lists.llvm.org
Fri Jan 17 00:11:01 PST 2025
Author: Viktoriia Bakalova
Date: 2025-01-17T09:10:58+01:00
New Revision: c3ba6f378ef80d750e2278560c6f95a300114412
URL: https://github.com/llvm/llvm-project/commit/c3ba6f378ef80d750e2278560c6f95a300114412
DIFF: https://github.com/llvm/llvm-project/commit/c3ba6f378ef80d750e2278560c6f95a300114412.diff
LOG: [Modules] Delay deserialization of preferred_name attribute at r… (#122726)
…ecord level.
This fixes the incorrect diagnostic emitted when compiling the following
snippet
```
// string_view.h
template<class _CharT>
class basic_string_view;
typedef basic_string_view<char> string_view;
template<class _CharT>
class
__attribute__((__preferred_name__(string_view)))
basic_string_view {
public:
basic_string_view()
{
}
};
inline basic_string_view<char> foo()
{
return basic_string_view<char>();
}
// A.cppm
module;
#include "string_view.h"
export module A;
// Use.cppm
module;
#include "string_view.h"
export module Use;
import A;
```
The diagnostic is
```
string_view.h:11:5: error: 'basic_string_view<char>::basic_string_view' from module 'A.<global>' is not present in definition of 'string_view' provided earlier
```
The underlying issue is that deserialization of the `preferred_name`
attribute triggers deserialization of `basic_string_view<char>`, which
triggers the deserialization of the `preferred_name` attribute again
(since it's attached to the `basic_string_view` template).
The deserialization logic is implemented in a way that prevents it from
going on a loop in a literal sense (it detects early on that it has
already seen the `string_view` typedef when trying to start its
deserialization for the second time), but leaves the typedef
deserialization in an unfinished state. Subsequently, the `string_view`
typedef from the deserialized module cannot be merged with the same
typedef from `string_view.h`, resulting in the above diagnostic.
This PR resolves the problem by delaying the deserialization of the
`preferred_name` attribute until the deserialization of the
`basic_string_view` template is completed. As a result of deferring, the
deserialization of the `preferred_name` attribute doesn't need to go on
a loop since the type of the `string_view` typedef is already known when
it's deserialized.
Added:
Modified:
clang/include/clang/AST/Attr.h
clang/include/clang/Basic/Attr.td
clang/include/clang/Serialization/ASTReader.h
clang/include/clang/Serialization/ASTRecordReader.h
clang/lib/Serialization/ASTReader.cpp
clang/lib/Serialization/ASTReaderDecl.cpp
clang/lib/Serialization/ASTWriter.cpp
clang/test/Modules/preferred_name.cppm
clang/utils/TableGen/ClangAttrEmitter.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/AST/Attr.h b/clang/include/clang/AST/Attr.h
index 3365ebe4d9012b..bed532a84a1bde 100644
--- a/clang/include/clang/AST/Attr.h
+++ b/clang/include/clang/AST/Attr.h
@@ -60,6 +60,8 @@ class Attr : public AttributeCommonInfo {
unsigned IsLateParsed : 1;
LLVM_PREFERRED_TYPE(bool)
unsigned InheritEvenIfAlreadyPresent : 1;
+ LLVM_PREFERRED_TYPE(bool)
+ unsigned DeferDeserialization : 1;
void *operator new(size_t bytes) noexcept {
llvm_unreachable("Attrs cannot be allocated with regular 'new'.");
@@ -80,10 +82,11 @@ class Attr : public AttributeCommonInfo {
protected:
Attr(ASTContext &Context, const AttributeCommonInfo &CommonInfo,
- attr::Kind AK, bool IsLateParsed)
+ attr::Kind AK, bool IsLateParsed, bool DeferDeserialization = false)
: AttributeCommonInfo(CommonInfo), AttrKind(AK), Inherited(false),
IsPackExpansion(false), Implicit(false), IsLateParsed(IsLateParsed),
- InheritEvenIfAlreadyPresent(false) {}
+ InheritEvenIfAlreadyPresent(false),
+ DeferDeserialization(DeferDeserialization) {}
public:
attr::Kind getKind() const { return static_cast<attr::Kind>(AttrKind); }
@@ -105,6 +108,8 @@ class Attr : public AttributeCommonInfo {
void setPackExpansion(bool PE) { IsPackExpansion = PE; }
bool isPackExpansion() const { return IsPackExpansion; }
+ bool shouldDeferDeserialization() const { return DeferDeserialization; }
+
// Clone this attribute.
Attr *clone(ASTContext &C) const;
@@ -146,8 +151,9 @@ class InheritableAttr : public Attr {
protected:
InheritableAttr(ASTContext &Context, const AttributeCommonInfo &CommonInfo,
attr::Kind AK, bool IsLateParsed,
- bool InheritEvenIfAlreadyPresent)
- : Attr(Context, CommonInfo, AK, IsLateParsed) {
+ bool InheritEvenIfAlreadyPresent,
+ bool DeferDeserialization = false)
+ : Attr(Context, CommonInfo, AK, IsLateParsed, DeferDeserialization) {
this->InheritEvenIfAlreadyPresent = InheritEvenIfAlreadyPresent;
}
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 408d3adf370c85..3969dd8af5dfae 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -713,6 +713,12 @@ class Attr {
// attribute may be documented under multiple categories, more than one
// Documentation entry may be listed.
list<Documentation> Documentation;
+ // Set to true if deserialization of this attribute must be deferred until
+ // the parent Decl is fully deserialized (during header module file
+ // deserialization). E.g., this is the case for the preferred_name attribute,
+ // since its type deserialization depends on its target Decl type.
+ // (See https://github.com/llvm/llvm-project/issues/56490 for details).
+ bit DeferDeserialization = 0;
}
/// Used to define a set of mutually exclusive attributes.
@@ -3254,6 +3260,11 @@ def PreferredName : InheritableAttr {
let InheritEvenIfAlreadyPresent = 1;
let MeaningfulToClassTemplateDefinition = 1;
let TemplateDependent = 1;
+ // Type of this attribute depends on the target Decl type.
+ // Therefore, its deserialization must be deferred until
+ // deserialization of the target Decl is complete
+ // (for header modules).
+ let DeferDeserialization = 1;
}
def PreserveMost : DeclOrTypeAttr {
diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index d77bb01c5aa596..c839215dc40778 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/clang/include/clang/Serialization/ASTReader.h
@@ -1221,6 +1221,24 @@ class ASTReader
/// been completed.
std::deque<PendingDeclContextInfo> PendingDeclContextInfos;
+ /// Deserialization of some attributes must be deferred since they refer
+ /// to themselves in their type (e.g., preferred_name attribute refers to the
+ /// typedef that refers back to the template specialization of the template
+ /// that the attribute is attached to).
+ /// More attributes that store TypeSourceInfo might be potentially affected,
+ /// see https://github.com/llvm/llvm-project/issues/56490 for details.
+ struct DeferredAttribute {
+ // Index of the deferred attribute in the Record of the TargetedDecl.
+ uint64_t RecordIdx;
+ // Decl to attach a deferred attribute to.
+ Decl *TargetedDecl;
+ };
+
+ /// The collection of Decls that have been loaded but some of their attributes
+ /// have been deferred, paired with the index inside the record pointing
+ /// at the skipped attribute.
+ SmallVector<DeferredAttribute> PendingDeferredAttributes;
+
template <typename DeclTy>
using DuplicateObjCDecls = std::pair<DeclTy *, DeclTy *>;
@@ -1570,6 +1588,7 @@ class ASTReader
void loadPendingDeclChain(Decl *D, uint64_t LocalOffset);
void loadObjCCategories(GlobalDeclID ID, ObjCInterfaceDecl *D,
unsigned PreviousGeneration = 0);
+ void loadDeferredAttribute(const DeferredAttribute &DA);
RecordLocation getLocalBitOffset(uint64_t GlobalOffset);
uint64_t getGlobalBitOffset(ModuleFile &M, uint64_t LocalOffset);
diff --git a/clang/include/clang/Serialization/ASTRecordReader.h b/clang/include/clang/Serialization/ASTRecordReader.h
index 2561418b78ca7f..a29972fcf73a8d 100644
--- a/clang/include/clang/Serialization/ASTRecordReader.h
+++ b/clang/include/clang/Serialization/ASTRecordReader.h
@@ -83,6 +83,12 @@ class ASTRecordReader
/// Returns the current value in this record, without advancing.
uint64_t peekInt() { return Record[Idx]; }
+ /// Returns the next N values in this record, without advancing.
+ uint64_t peekInts(unsigned N) { return Record[Idx + N]; }
+
+ /// Skips the current value.
+ void skipInt() { Idx += 1; }
+
/// Skips the specified number of values.
void skipInts(unsigned N) { Idx += N; }
@@ -335,7 +341,12 @@ class ASTRecordReader
Attr *readAttr();
/// Reads attributes from the current stream position, advancing Idx.
- void readAttributes(AttrVec &Attrs);
+ /// For some attributes (where type depends on itself recursively), defer
+ /// reading the attribute until the type has been read.
+ void readAttributes(AttrVec &Attrs, Decl *D = nullptr);
+
+ /// Reads one attribute from the current stream position, advancing Idx.
+ Attr *readOrDeferAttrFor(Decl *D);
/// Read an BTFTypeTagAttr object.
BTFTypeTagAttr *readBTFTypeTagAttr() {
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 202227b1955855..d08dc6b1b4d938 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -10180,6 +10180,11 @@ void ASTReader::finishPendingActions() {
}
PendingDeducedVarTypes.clear();
+ // Load the delayed preferred name attributes.
+ for (unsigned I = 0; I != PendingDeferredAttributes.size(); ++I)
+ loadDeferredAttribute(PendingDeferredAttributes[I]);
+ PendingDeferredAttributes.clear();
+
// For each decl chain that we wanted to complete while deserializing, mark
// it as "still needs to be completed".
for (unsigned I = 0; I != PendingIncompleteDeclChains.size(); ++I) {
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 1c51a7b5e460f6..06dff02ac61280 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -612,7 +612,7 @@ void ASTDeclReader::VisitDecl(Decl *D) {
if (HasAttrs) {
AttrVec Attrs;
- Record.readAttributes(Attrs);
+ Record.readAttributes(Attrs, D);
// Avoid calling setAttrs() directly because it uses Decl::getASTContext()
// internally which is unsafe during derialization.
D->setAttrsImpl(Attrs, Reader.getContext());
@@ -3093,6 +3093,8 @@ class AttrReader {
return Reader.readInt();
}
+ uint64_t peekInts(unsigned N) { return Reader.peekInts(N); }
+
bool readBool() { return Reader.readBool(); }
SourceRange readSourceRange() {
@@ -3123,18 +3125,29 @@ class AttrReader {
return Reader.readVersionTuple();
}
+ void skipInt() { Reader.skipInts(1); }
+
+ void skipInts(unsigned N) { Reader.skipInts(N); }
+
+ unsigned getCurrentIdx() { return Reader.getIdx(); }
+
OMPTraitInfo *readOMPTraitInfo() { return Reader.readOMPTraitInfo(); }
template <typename T> T *readDeclAs() { return Reader.readDeclAs<T>(); }
};
}
+/// Reads one attribute from the current stream position, advancing Idx.
Attr *ASTRecordReader::readAttr() {
AttrReader Record(*this);
auto V = Record.readInt();
if (!V)
return nullptr;
+ // Read and ignore the skip count, since attribute deserialization is not
+ // deferred on this pass.
+ Record.skipInt();
+
Attr *New = nullptr;
// Kind is stored as a 1-based integer because 0 is used to indicate a null
// Attr pointer.
@@ -3164,13 +3177,28 @@ Attr *ASTRecordReader::readAttr() {
return New;
}
-/// Reads attributes from the current stream position.
-void ASTRecordReader::readAttributes(AttrVec &Attrs) {
+/// Reads attributes from the current stream position, advancing Idx.
+/// For some attributes (where type depends on itself recursively), defer
+/// reading the attribute until the type has been read.
+void ASTRecordReader::readAttributes(AttrVec &Attrs, Decl *D) {
for (unsigned I = 0, E = readInt(); I != E; ++I)
- if (auto *A = readAttr())
+ if (auto *A = readOrDeferAttrFor(D))
Attrs.push_back(A);
}
+/// Reads one attribute from the current stream position, advancing Idx.
+/// For some attributes (where type depends on itself recursively), defer
+/// reading the attribute until the type has been read.
+Attr *ASTRecordReader::readOrDeferAttrFor(Decl *D) {
+ AttrReader Record(*this);
+ unsigned SkipCount = Record.peekInts(1);
+ if (!SkipCount)
+ return readAttr();
+ Reader->PendingDeferredAttributes.push_back({Record.getCurrentIdx(), D});
+ Record.skipInts(SkipCount);
+ return nullptr;
+}
+
//===----------------------------------------------------------------------===//
// ASTReader Implementation
//===----------------------------------------------------------------------===//
@@ -4459,6 +4487,49 @@ void ASTReader::loadPendingDeclChain(Decl *FirstLocal, uint64_t LocalOffset) {
ASTDeclReader::attachLatestDecl(CanonDecl, MostRecent);
}
+void ASTReader::loadDeferredAttribute(const DeferredAttribute &DA) {
+ Decl *D = DA.TargetedDecl;
+ ModuleFile *M = getOwningModuleFile(D);
+
+ unsigned LocalDeclIndex = D->getGlobalID().getLocalDeclIndex();
+ const DeclOffset &DOffs = M->DeclOffsets[LocalDeclIndex];
+ RecordLocation Loc(M, DOffs.getBitOffset(M->DeclsBlockStartOffset));
+
+ llvm::BitstreamCursor &Cursor = Loc.F->DeclsCursor;
+ SavedStreamPosition SavedPosition(Cursor);
+ if (llvm::Error Err = Cursor.JumpToBit(Loc.Offset)) {
+ Error(std::move(Err));
+ }
+
+ Expected<unsigned> MaybeCode = Cursor.ReadCode();
+ if (!MaybeCode) {
+ llvm::report_fatal_error(
+ Twine("ASTReader::loadPreferredNameAttribute failed reading code: ") +
+ toString(MaybeCode.takeError()));
+ }
+ unsigned Code = MaybeCode.get();
+
+ ASTRecordReader Record(*this, *Loc.F);
+ Expected<unsigned> MaybeRecCode = Record.readRecord(Cursor, Code);
+ if (!MaybeRecCode) {
+ llvm::report_fatal_error(
+ Twine(
+ "ASTReader::loadPreferredNameAttribute failed reading rec code: ") +
+ toString(MaybeCode.takeError()));
+ }
+ unsigned RecCode = MaybeRecCode.get();
+ if (RecCode < DECL_TYPEDEF || RecCode > DECL_LAST) {
+ llvm::report_fatal_error(
+ Twine("ASTReader::loadPreferredNameAttribute failed reading rec code: "
+ "expected valid DeclCode") +
+ toString(MaybeCode.takeError()));
+ }
+
+ Record.skipInts(DA.RecordIdx);
+ Attr *A = Record.readAttr();
+ getContext().getDeclAttrs(D).push_back(A);
+}
+
namespace {
/// Given an ObjC interface, goes through the modules and links to the
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 55d3c2bb56f2c5..1c4f5730df312b 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -37,6 +37,7 @@
#include "clang/AST/Type.h"
#include "clang/AST/TypeLoc.h"
#include "clang/AST/TypeLocVisitor.h"
+#include "clang/Basic/AttrKinds.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/DiagnosticOptions.h"
#include "clang/Basic/FileEntry.h"
@@ -5067,15 +5068,14 @@ void ASTWriter::WriteModuleFileExtension(Sema &SemaRef,
void ASTRecordWriter::AddAttr(const Attr *A) {
auto &Record = *this;
- // FIXME: Clang can't handle the serialization/deserialization of
- // preferred_name properly now. See
- // https://github.com/llvm/llvm-project/issues/56490 for example.
- if (!A || (isa<PreferredNameAttr>(A) &&
- Writer->isWritingStdCXXNamedModules()))
+ if (!A)
return Record.push_back(0);
Record.push_back(A->getKind() + 1); // FIXME: stable encoding, target attrs
+ auto SkipIdx = Record.size();
+ // Add placeholder for the size of deferred attribute.
+ Record.push_back(0);
Record.AddIdentifierRef(A->getAttrName());
Record.AddIdentifierRef(A->getScopeName());
Record.AddSourceRange(A->getRange());
@@ -5086,6 +5086,12 @@ void ASTRecordWriter::AddAttr(const Attr *A) {
Record.push_back(A->isRegularKeywordAttribute());
#include "clang/Serialization/AttrPCHWrite.inc"
+
+ if (A->shouldDeferDeserialization()) {
+ // Record the actual size of deferred attribute (+ 1 to count the attribute
+ // kind).
+ Record[SkipIdx] = Record.size() - SkipIdx + 1;
+ }
}
/// Emit the list of attributes to the specified record.
diff --git a/clang/test/Modules/preferred_name.cppm b/clang/test/Modules/preferred_name.cppm
index 806781a81c5ca7..86ba6ae96db998 100644
--- a/clang/test/Modules/preferred_name.cppm
+++ b/clang/test/Modules/preferred_name.cppm
@@ -53,10 +53,16 @@ import A;
export using ::foo_templ;
//--- Use1.cpp
-import A; // expected-warning at foo.h:8 {{attribute declaration must precede definition}}
-#include "foo.h" // expected-note at foo.h:9 {{previous definition is here}}
-
+// expected-no-diagnostics
+import A;
+#include "foo.h"
//--- Use2.cpp
// expected-no-diagnostics
#include "foo.h"
import A;
+
+//--- Use3.cpp
+#include "foo.h"
+import A;
+foo test;
+int size = test.size(); // expected-error {{no member named 'size' in 'foo'}}
diff --git a/clang/utils/TableGen/ClangAttrEmitter.cpp b/clang/utils/TableGen/ClangAttrEmitter.cpp
index cc6a8eaebd44ec..41730eba32ce27 100644
--- a/clang/utils/TableGen/ClangAttrEmitter.cpp
+++ b/clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3043,6 +3043,10 @@ static void emitAttributes(const RecordKeeper &Records, raw_ostream &OS,
<< (R.getValueAsBit("InheritEvenIfAlreadyPresent") ? "true"
: "false");
}
+ if (R.getValueAsBit("DeferDeserialization")) {
+ OS << ", "
+ << "/*DeferDeserialization=*/true";
+ }
OS << ")\n";
for (auto const &ai : Args) {
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