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[Serialization] Record whether the ODR is skipped (#82302)
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Close #80570.

In

a0b6747,
we skipped ODR checks for decls in GMF. Then it should be natural to
skip storing the ODR values in BMI.

Generally it should be fine as long as the writer and the reader keep
consistent.

However, the use of preamble in clangd shows the tricky part.

For,

```
// test.cpp
module;

// any one off these is enough to crash clangd
// #include <iostream>
// #include <string_view>
// #include <cmath>
// #include <system_error>
// #include <new>
// #include <bit>
// probably many more

// only ok with libc++, not the system provided libstdc++ 13.2.1

// these are ok

export module test;
```

clangd will store the headers as preamble to speedup the parsing and the
preamble reuses the serialization techniques. (Generally we'd call the
preamble as PCH. However it is not true strictly. I've tested the PCH
wouldn't be problematic.) However, the tricky part is that the preamble
is not modules. It literally serialiaze and deserialize things. So
before clangd parsing the above test module, clangd will serialize the
headers into the preamble. Note that there is no concept like GMF now.
So the ODR bits are stored. However, when clangd parse the file
actually, the decls from preamble are thought as in GMF literally, then
hte ODR bits are skipped. Then mismatch happens.

To solve the problem, this patch adds another bit for decls to record
whether or not the ODR bits are skipped.
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ChuanqiXu9 committed Feb 20, 2024
1 parent c8fab88 commit 49775b1
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Showing 5 changed files with 154 additions and 10 deletions.
10 changes: 7 additions & 3 deletions clang/lib/Serialization/ASTReaderDecl.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -800,11 +800,12 @@ void ASTDeclReader::VisitEnumDecl(EnumDecl *ED) {
BitsUnpacker EnumDeclBits(Record.readInt());
ED->setNumPositiveBits(EnumDeclBits.getNextBits(/*Width=*/8));
ED->setNumNegativeBits(EnumDeclBits.getNextBits(/*Width=*/8));
bool ShouldSkipCheckingODR = EnumDeclBits.getNextBit();
ED->setScoped(EnumDeclBits.getNextBit());
ED->setScopedUsingClassTag(EnumDeclBits.getNextBit());
ED->setFixed(EnumDeclBits.getNextBit());

if (!shouldSkipCheckingODR(ED)) {
if (!ShouldSkipCheckingODR) {
ED->setHasODRHash(true);
ED->ODRHash = Record.readInt();
}
Expand Down Expand Up @@ -1073,6 +1074,7 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {

FD->setCachedLinkage((Linkage)FunctionDeclBits.getNextBits(/*Width=*/3));
FD->setStorageClass((StorageClass)FunctionDeclBits.getNextBits(/*Width=*/3));
bool ShouldSkipCheckingODR = FunctionDeclBits.getNextBit();
FD->setInlineSpecified(FunctionDeclBits.getNextBit());
FD->setImplicitlyInline(FunctionDeclBits.getNextBit());
FD->setHasSkippedBody(FunctionDeclBits.getNextBit());
Expand Down Expand Up @@ -1102,7 +1104,7 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
if (FD->isExplicitlyDefaulted())
FD->setDefaultLoc(readSourceLocation());

if (!shouldSkipCheckingODR(FD)) {
if (!ShouldSkipCheckingODR) {
FD->ODRHash = Record.readInt();
FD->setHasODRHash(true);
}
Expand Down Expand Up @@ -1973,6 +1975,8 @@ void ASTDeclReader::ReadCXXDefinitionData(

BitsUnpacker CXXRecordDeclBits = Record.readInt();

bool ShouldSkipCheckingODR = CXXRecordDeclBits.getNextBit();

#define FIELD(Name, Width, Merge) \
if (!CXXRecordDeclBits.canGetNextNBits(Width)) \
CXXRecordDeclBits.updateValue(Record.readInt()); \
Expand All @@ -1982,7 +1986,7 @@ void ASTDeclReader::ReadCXXDefinitionData(
#undef FIELD

// We only perform ODR checks for decls not in GMF.
if (!shouldSkipCheckingODR(D)) {
if (!ShouldSkipCheckingODR) {
// Note: the caller has deserialized the IsLambda bit already.
Data.ODRHash = Record.readInt();
Data.HasODRHash = true;
Expand Down
6 changes: 4 additions & 2 deletions clang/lib/Serialization/ASTWriter.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -6056,6 +6056,9 @@ void ASTRecordWriter::AddCXXDefinitionData(const CXXRecordDecl *D) {

BitsPacker DefinitionBits;

bool ShouldSkipCheckingODR = shouldSkipCheckingODR(D);
DefinitionBits.addBit(ShouldSkipCheckingODR);

#define FIELD(Name, Width, Merge) \
if (!DefinitionBits.canWriteNextNBits(Width)) { \
Record->push_back(DefinitionBits); \
Expand All @@ -6069,11 +6072,10 @@ void ASTRecordWriter::AddCXXDefinitionData(const CXXRecordDecl *D) {
Record->push_back(DefinitionBits);

// We only perform ODR checks for decls not in GMF.
if (!shouldSkipCheckingODR(D)) {
if (!ShouldSkipCheckingODR)
// getODRHash will compute the ODRHash if it has not been previously
// computed.
Record->push_back(D->getODRHash());
}

bool ModulesDebugInfo =
Writer->Context->getLangOpts().ModulesDebugInfo && !D->isDependentType();
Expand Down
15 changes: 10 additions & 5 deletions clang/lib/Serialization/ASTWriterDecl.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -488,13 +488,15 @@ void ASTDeclWriter::VisitEnumDecl(EnumDecl *D) {
BitsPacker EnumDeclBits;
EnumDeclBits.addBits(D->getNumPositiveBits(), /*BitWidth=*/8);
EnumDeclBits.addBits(D->getNumNegativeBits(), /*BitWidth=*/8);
bool ShouldSkipCheckingODR = shouldSkipCheckingODR(D);
EnumDeclBits.addBit(ShouldSkipCheckingODR);
EnumDeclBits.addBit(D->isScoped());
EnumDeclBits.addBit(D->isScopedUsingClassTag());
EnumDeclBits.addBit(D->isFixed());
Record.push_back(EnumDeclBits);

// We only perform ODR checks for decls not in GMF.
if (!shouldSkipCheckingODR(D))
if (!ShouldSkipCheckingODR)
Record.push_back(D->getODRHash());

if (MemberSpecializationInfo *MemberInfo = D->getMemberSpecializationInfo()) {
Expand Down Expand Up @@ -678,6 +680,8 @@ void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
// FIXME: stable encoding
FunctionDeclBits.addBits(llvm::to_underlying(D->getLinkageInternal()), 3);
FunctionDeclBits.addBits((uint32_t)D->getStorageClass(), /*BitWidth=*/3);
bool ShouldSkipCheckingODR = shouldSkipCheckingODR(D);
FunctionDeclBits.addBit(ShouldSkipCheckingODR);
FunctionDeclBits.addBit(D->isInlineSpecified());
FunctionDeclBits.addBit(D->isInlined());
FunctionDeclBits.addBit(D->hasSkippedBody());
Expand All @@ -704,7 +708,7 @@ void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
Record.AddSourceLocation(D->getDefaultLoc());

// We only perform ODR checks for decls not in GMF.
if (!shouldSkipCheckingODR(D))
if (!ShouldSkipCheckingODR)
Record.push_back(D->getODRHash());

if (D->isDefaulted()) {
Expand Down Expand Up @@ -2137,12 +2141,13 @@ getFunctionDeclAbbrev(serialization::DeclCode Code) {
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 11)); // IDNS
Abv->Add(BitCodeAbbrevOp(
BitCodeAbbrevOp::Fixed,
27)); // Packed Function Bits: StorageClass, Inline, InlineSpecified,
28)); // Packed Function Bits: StorageClass, Inline, InlineSpecified,
// VirtualAsWritten, Pure, HasInheritedProto, HasWrittenProto,
// Deleted, Trivial, TrivialForCall, Defaulted, ExplicitlyDefaulted,
// IsIneligibleOrNotSelected, ImplicitReturnZero, Constexpr,
// UsesSEHTry, SkippedBody, MultiVersion, LateParsed,
// FriendConstraintRefersToEnclosingTemplate, Linkage
// FriendConstraintRefersToEnclosingTemplate, Linkage,
// ShouldSkipCheckingODR
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LocEnd
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // ODRHash
// This Array slurps the rest of the record. Fortunately we want to encode
Expand Down Expand Up @@ -2269,7 +2274,7 @@ void ASTWriter::WriteDeclAbbrevs() {
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // AddTypeRef
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // IntegerType
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getPromotionType
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 19)); // Enum Decl Bits
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 20)); // Enum Decl Bits
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));// ODRHash
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InstantiatedMembEnum
// DC
Expand Down
1 change: 1 addition & 0 deletions clang/unittests/Serialization/CMakeLists.txt
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ add_clang_unittest(SerializationTests
InMemoryModuleCacheTest.cpp
ModuleCacheTest.cpp
NoCommentsTest.cpp
PreambleInNamedModulesTest.cpp
SourceLocationEncodingTest.cpp
VarDeclConstantInitTest.cpp
)
Expand Down
132 changes: 132 additions & 0 deletions clang/unittests/Serialization/PreambleInNamedModulesTest.cpp
Original file line number Diff line number Diff line change
@@ -0,0 +1,132 @@
//===- unittests/Serialization/PreambleInNamedModulesTest.cpp -------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/CompilerInvocation.h"
#include "clang/Frontend/FrontendActions.h"
#include "clang/Frontend/PrecompiledPreamble.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/raw_ostream.h"

#include "gtest/gtest.h"

using namespace llvm;
using namespace clang;

namespace {

class PreambleInNamedModulesTest : public ::testing::Test {
void SetUp() override {
ASSERT_FALSE(sys::fs::createUniqueDirectory("modules-test", TestDir));
}

void TearDown() override { sys::fs::remove_directories(TestDir); }

public:
using PathType = SmallString<256>;

PathType TestDir;

void addFile(StringRef Path, StringRef Contents, PathType &AbsPath) {
ASSERT_FALSE(sys::path::is_absolute(Path));

AbsPath = TestDir;
sys::path::append(AbsPath, Path);

ASSERT_FALSE(
sys::fs::create_directories(llvm::sys::path::parent_path(AbsPath)));

std::error_code EC;
llvm::raw_fd_ostream OS(AbsPath, EC);
ASSERT_FALSE(EC);
OS << Contents;
}

void addFile(StringRef Path, StringRef Contents) {
PathType UnusedAbsPath;
addFile(Path, Contents, UnusedAbsPath);
}
};

// Testing that the use of Preamble in named modules can work basically.
// See https://github.com/llvm/llvm-project/issues/80570
TEST_F(PreambleInNamedModulesTest, BasicTest) {
addFile("foo.h", R"cpp(
enum class E {
A,
B,
C,
D
};
)cpp");

PathType MainFilePath;
addFile("A.cppm", R"cpp(
module;
#include "foo.h"
export module A;
export using ::E;
)cpp",
MainFilePath);

IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
CompilerInstance::createDiagnostics(new DiagnosticOptions());
IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS =
llvm::vfs::createPhysicalFileSystem();

CreateInvocationOptions CIOpts;
CIOpts.Diags = Diags;
CIOpts.VFS = VFS;

const char *Args[] = {"clang++", "-std=c++20", "-working-directory",
TestDir.c_str(), MainFilePath.c_str()};
std::shared_ptr<CompilerInvocation> Invocation =
createInvocation(Args, CIOpts);
ASSERT_TRUE(Invocation);

llvm::ErrorOr<std::unique_ptr<MemoryBuffer>> ContentsBuffer =
llvm::MemoryBuffer::getFile(MainFilePath, /*IsText=*/true);
EXPECT_TRUE(ContentsBuffer);
std::unique_ptr<MemoryBuffer> Buffer = std::move(*ContentsBuffer);

PreambleBounds Bounds =
ComputePreambleBounds(Invocation->getLangOpts(), *Buffer, 0);

PreambleCallbacks Callbacks;
llvm::ErrorOr<PrecompiledPreamble> BuiltPreamble = PrecompiledPreamble::Build(
*Invocation, Buffer.get(), Bounds, *Diags, VFS,
std::make_shared<PCHContainerOperations>(),
/*StoreInMemory=*/false, /*StoragePath=*/TestDir, Callbacks);

ASSERT_FALSE(Diags->hasErrorOccurred());

EXPECT_TRUE(BuiltPreamble);
EXPECT_TRUE(BuiltPreamble->CanReuse(*Invocation, *Buffer, Bounds, *VFS));
BuiltPreamble->OverridePreamble(*Invocation, VFS, Buffer.get());

auto Clang = std::make_unique<CompilerInstance>(
std::make_shared<PCHContainerOperations>());
Clang->setInvocation(std::move(Invocation));
Clang->setDiagnostics(Diags.get());

if (auto VFSWithRemapping = createVFSFromCompilerInvocation(
Clang->getInvocation(), Clang->getDiagnostics(), VFS))
VFS = VFSWithRemapping;

Clang->createFileManager(VFS);
EXPECT_TRUE(Clang->createTarget());

Buffer.release();

SyntaxOnlyAction Action;
EXPECT_TRUE(Clang->ExecuteAction(Action));
EXPECT_FALSE(Clang->getDiagnosticsPtr()->hasErrorOccurred());
}

} // namespace

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