WriteBlockInfoBlock();
Context = &SemaRef.Context;
- if (Chain)
- WriteASTChain(SemaRef, StatCalls, isysroot);
- else
- WriteASTCore(SemaRef, StatCalls, isysroot, OutputFile);
+ WriteASTCore(SemaRef, StatCalls, isysroot, OutputFile);
Context = 0;
}
// Set up predefined declaration IDs.
DeclIDs[Context.getTranslationUnitDecl()] = PREDEF_DECL_TRANSLATION_UNIT_ID;
- // Make sure that we emit IdentifierInfos (and any attached
- // declarations) for builtins.
- {
+ if (!Chain) {
+ // Make sure that we emit IdentifierInfos (and any attached
+ // declarations) for builtins. We don't need to do this when we're
+ // emitting chained PCH files, because all of the builtins will be
+ // in the original PCH file.
+ // FIXME: Modules won't like this at all.
IdentifierTable &Table = PP.getIdentifierTable();
SmallVector<const char *, 32> BuiltinNames;
Context.BuiltinInfo.GetBuiltinNames(BuiltinNames,
AddLazyVectorDecls(*this, SemaRef.UnusedFileScopedDecls,
UnusedFileScopedDecls);
+ // Build a record containing all of the delegating constructors we still need
+ // to resolve.
RecordData DelegatingCtorDecls;
AddLazyVectorDecls(*this, SemaRef.DelegatingCtorDecls, DelegatingCtorDecls);
+ // Write the set of weak, undeclared identifiers. We always write the
+ // entire table, since later PCH files in a PCH chain are only interested in
+ // the results at the end of the chain.
RecordData WeakUndeclaredIdentifiers;
if (!SemaRef.WeakUndeclaredIdentifiers.empty()) {
for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
WriteStatCache(*StatCalls);
WriteSourceManagerBlock(Context.getSourceManager(), PP, isysroot);
- // Form the record of special types.
- RecordData SpecialTypes;
- AddTypeRef(Context.getBuiltinVaListType(), SpecialTypes);
- AddTypeRef(Context.ObjCIdTypedefType, SpecialTypes);
- AddTypeRef(Context.ObjCSelTypedefType, SpecialTypes);
- AddTypeRef(Context.ObjCProtoType, SpecialTypes);
- AddTypeRef(Context.ObjCClassTypedefType, SpecialTypes);
- AddTypeRef(Context.getRawCFConstantStringType(), SpecialTypes);
- AddTypeRef(Context.getFILEType(), SpecialTypes);
- AddTypeRef(Context.getjmp_bufType(), SpecialTypes);
- AddTypeRef(Context.getsigjmp_bufType(), SpecialTypes);
- AddTypeRef(Context.ObjCIdRedefinitionType, SpecialTypes);
- AddTypeRef(Context.ObjCClassRedefinitionType, SpecialTypes);
- AddTypeRef(Context.ObjCSelRedefinitionType, SpecialTypes);
- SpecialTypes.push_back(Context.isInt128Installed());
+ if (Chain) {
+ // Write the mapping information describing our module dependencies and how
+ // each of those modules were mapped into our own offset/ID space, so that
+ // the reader can build the appropriate mapping to its own offset/ID space.
+ // The map consists solely of a blob with the following format:
+ // *(module-name-len:i16 module-name:len*i8
+ // source-location-offset:i32
+ // identifier-id:i32
+ // preprocessed-entity-id:i32
+ // macro-definition-id:i32
+ // selector-id:i32
+ // declaration-id:i32
+ // c++-base-specifiers-id:i32
+ // type-id:i32)
+ //
+ llvm::BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
+ Abbrev->Add(BitCodeAbbrevOp(MODULE_OFFSET_MAP));
+ Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+ unsigned ModuleOffsetMapAbbrev = Stream.EmitAbbrev(Abbrev);
+ llvm::SmallString<2048> Buffer;
+ {
+ llvm::raw_svector_ostream Out(Buffer);
+ for (ModuleManager::ModuleConstIterator M = Chain->ModuleMgr.begin(),
+ MEnd = Chain->ModuleMgr.end();
+ M != MEnd; ++M) {
+ StringRef FileName = (*M)->FileName;
+ io::Emit16(Out, FileName.size());
+ Out.write(FileName.data(), FileName.size());
+ io::Emit32(Out, (*M)->SLocEntryBaseOffset);
+ io::Emit32(Out, (*M)->BaseIdentifierID);
+ io::Emit32(Out, (*M)->BasePreprocessedEntityID);
+ io::Emit32(Out, (*M)->BaseMacroDefinitionID);
+ io::Emit32(Out, (*M)->BaseSelectorID);
+ io::Emit32(Out, (*M)->BaseDeclID);
+ io::Emit32(Out, (*M)->BaseTypeIndex);
+ }
+ }
+ Record.clear();
+ Record.push_back(MODULE_OFFSET_MAP);
+ Stream.EmitRecordWithBlob(ModuleOffsetMapAbbrev, Record,
+ Buffer.data(), Buffer.size());
+ }
- // We don't start with the translation unit, but with its decls that
- // don't come from the chained PCH.
+ // Create a lexical update block containing all of the declarations in the
+ // translation unit that do not come from other AST files.
const TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
SmallVector<KindDeclIDPair, 64> NewGlobalDecls;
for (DeclContext::decl_iterator I = TU->noload_decls_begin(),
- E = TU->noload_decls_end();
+ E = TU->noload_decls_end();
I != E; ++I) {
if ((*I)->getPCHLevel() == 0)
NewGlobalDecls.push_back(std::make_pair((*I)->getKind(), GetDeclRef(*I)));
else if ((*I)->isChangedSinceDeserialization())
(void)GetDeclRef(*I); // Make sure it's written, but don't record it.
}
- // We also need to write a lexical updates block for the TU.
+
llvm::BitCodeAbbrev *Abv = new llvm::BitCodeAbbrev();
Abv->Add(llvm::BitCodeAbbrevOp(TU_UPDATE_LEXICAL));
Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
Stream.EmitRecordWithBlob(TuUpdateLexicalAbbrev, Record,
data(NewGlobalDecls));
- // And a visible updates block for the DeclContexts.
+ // And a visible updates block for the translation unit.
Abv = new llvm::BitCodeAbbrev();
Abv->Add(llvm::BitCodeAbbrevOp(UPDATE_VISIBLE));
Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::VBR, 6));
UpdateVisibleAbbrev = Stream.EmitAbbrev(Abv);
WriteDeclContextVisibleUpdate(TU);
- // If the translation unit has an anonymous namespace, write it as an
- // update block.
+ // If the translation unit has an anonymous namespace, and we don't already
+ // have an update block for it, write it as an update block.
if (NamespaceDecl *NS = TU->getAnonymousNamespace()) {
ASTWriter::UpdateRecord &Record = DeclUpdates[TU];
- Record.push_back(UPD_CXX_ADDED_ANONYMOUS_NAMESPACE);
- AddDeclRef(NS, Record);
+ if (Record.empty()) {
+ Record.push_back(UPD_CXX_ADDED_ANONYMOUS_NAMESPACE);
+ AddDeclRef(NS, Record);
+ }
}
+ // Form the record of special types.
+ RecordData SpecialTypes;
+ AddTypeRef(Context.getBuiltinVaListType(), SpecialTypes);
+ AddTypeRef(Context.ObjCIdTypedefType, SpecialTypes);
+ AddTypeRef(Context.ObjCSelTypedefType, SpecialTypes);
+ AddTypeRef(Context.ObjCProtoType, SpecialTypes);
+ AddTypeRef(Context.ObjCClassTypedefType, SpecialTypes);
+ AddTypeRef(Context.getRawCFConstantStringType(), SpecialTypes);
+ AddTypeRef(Context.getFILEType(), SpecialTypes);
+ AddTypeRef(Context.getjmp_bufType(), SpecialTypes);
+ AddTypeRef(Context.getsigjmp_bufType(), SpecialTypes);
+ AddTypeRef(Context.ObjCIdRedefinitionType, SpecialTypes);
+ AddTypeRef(Context.ObjCClassRedefinitionType, SpecialTypes);
+ AddTypeRef(Context.ObjCSelRedefinitionType, SpecialTypes);
+ SpecialTypes.push_back(Context.isInt128Installed());
+
// Keep writing types and declarations until all types and
// declarations have been written.
Stream.EnterSubblock(DECLTYPES_BLOCK_ID, NUM_ALLOWED_ABBREVS_SIZE);
WriteDeclsBlockAbbrevs();
+ for (DeclsToRewriteTy::iterator I = DeclsToRewrite.begin(),
+ E = DeclsToRewrite.end();
+ I != E; ++I)
+ DeclTypesToEmit.push(const_cast<Decl*>(*I));
while (!DeclTypesToEmit.empty()) {
DeclOrType DOT = DeclTypesToEmit.front();
DeclTypesToEmit.pop();
Stream.EmitRecord(SPECIAL_TYPES, SpecialTypes);
- // Write the record containing external, unnamed definitions.
- if (!ExternalDefinitions.empty())
- Stream.EmitRecord(EXTERNAL_DEFINITIONS, ExternalDefinitions);
-
- // Write the record containing tentative definitions.
- if (!TentativeDefinitions.empty())
- Stream.EmitRecord(TENTATIVE_DEFINITIONS, TentativeDefinitions);
-
- // Write the record containing unused file scoped decls.
- if (!UnusedFileScopedDecls.empty())
- Stream.EmitRecord(UNUSED_FILESCOPED_DECLS, UnusedFileScopedDecls);
-
- // Write the record containing weak undeclared identifiers.
- if (!WeakUndeclaredIdentifiers.empty())
- Stream.EmitRecord(WEAK_UNDECLARED_IDENTIFIERS,
- WeakUndeclaredIdentifiers);
-
- // Write the record containing locally-scoped external definitions.
- if (!LocallyScopedExternalDecls.empty())
- Stream.EmitRecord(LOCALLY_SCOPED_EXTERNAL_DECLS,
- LocallyScopedExternalDecls);
-
- // Write the record containing ext_vector type names.
- if (!ExtVectorDecls.empty())
- Stream.EmitRecord(EXT_VECTOR_DECLS, ExtVectorDecls);
-
- // Write the record containing VTable uses information.
- if (!VTableUses.empty())
- Stream.EmitRecord(VTABLE_USES, VTableUses);
-
- // Write the record containing dynamic classes declarations.
- if (!DynamicClasses.empty())
- Stream.EmitRecord(DYNAMIC_CLASSES, DynamicClasses);
-
- // Write the record containing pending implicit instantiations.
- if (!PendingInstantiations.empty())
- Stream.EmitRecord(PENDING_IMPLICIT_INSTANTIATIONS, PendingInstantiations);
-
- // Write the record containing declaration references of Sema.
- if (!SemaDeclRefs.empty())
- Stream.EmitRecord(SEMA_DECL_REFS, SemaDeclRefs);
-
- // Write the record containing CUDA-specific declaration references.
- if (!CUDASpecialDeclRefs.empty())
- Stream.EmitRecord(CUDA_SPECIAL_DECL_REFS, CUDASpecialDeclRefs);
-
- // Write the delegating constructors.
- if (!DelegatingCtorDecls.empty())
- Stream.EmitRecord(DELEGATING_CTORS, DelegatingCtorDecls);
-
- // Write the known namespaces.
- if (!KnownNamespaces.empty())
- Stream.EmitRecord(KNOWN_NAMESPACES, KnownNamespaces);
-
- WriteDeclUpdatesBlocks();
-
- // Some simple statistics
- Record.clear();
- Record.push_back(NumStatements);
- Record.push_back(NumMacros);
- Record.push_back(NumLexicalDeclContexts);
- Record.push_back(NumVisibleDeclContexts);
- Stream.EmitRecord(STATISTICS, Record);
- Stream.ExitBlock();
-}
-
-void ASTWriter::WriteASTChain(Sema &SemaRef, MemorizeStatCalls *StatCalls,
- StringRef isysroot) {
- using namespace llvm;
-
- ASTContext &Context = SemaRef.Context;
- Preprocessor &PP = SemaRef.PP;
-
- // Set up predefined declaration IDs.
- DeclIDs[Context.getTranslationUnitDecl()] = PREDEF_DECL_TRANSLATION_UNIT_ID;
-
- RecordData Record;
- Stream.EnterSubblock(AST_BLOCK_ID, 5);
- WriteMetadata(Context, isysroot, "");
- if (StatCalls && isysroot.empty())
- WriteStatCache(*StatCalls);
- // FIXME: Source manager block should only write new stuff, which could be
- // done by tracking the largest ID in the chain
- WriteSourceManagerBlock(Context.getSourceManager(), PP, isysroot);
-
- // Write the mapping information describing our module dependencies and how
- // each of those modules were mapped into our own offset/ID space, so that
- // the reader can build the appropriate mapping to its own offset/ID space.
- // The map consists solely of a blob with the following format:
- // *(module-name-len:i16 module-name:len*i8
- // source-location-offset:i32
- // identifier-id:i32
- // preprocessed-entity-id:i32
- // macro-definition-id:i32
- // selector-id:i32
- // declaration-id:i32
- // c++-base-specifiers-id:i32
- // type-id:i32)
- //
- llvm::BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
- Abbrev->Add(BitCodeAbbrevOp(MODULE_OFFSET_MAP));
- Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
- unsigned ModuleOffsetMapAbbrev = Stream.EmitAbbrev(Abbrev);
- llvm::SmallString<2048> Buffer;
- {
- llvm::raw_svector_ostream Out(Buffer);
- for (ModuleManager::ModuleConstIterator M = Chain->ModuleMgr.begin(),
- MEnd = Chain->ModuleMgr.end();
- M != MEnd; ++M) {
- StringRef FileName = (*M)->FileName;
- io::Emit16(Out, FileName.size());
- Out.write(FileName.data(), FileName.size());
- io::Emit32(Out, (*M)->SLocEntryBaseOffset);
- io::Emit32(Out, (*M)->BaseIdentifierID);
- io::Emit32(Out, (*M)->BasePreprocessedEntityID);
- io::Emit32(Out, (*M)->BaseMacroDefinitionID);
- io::Emit32(Out, (*M)->BaseSelectorID);
- io::Emit32(Out, (*M)->BaseDeclID);
- io::Emit32(Out, (*M)->BaseTypeIndex);
- }
- }
- Record.clear();
- Record.push_back(MODULE_OFFSET_MAP);
- Stream.EmitRecordWithBlob(ModuleOffsetMapAbbrev, Record,
- Buffer.data(), Buffer.size());
-
- // The special types are in the chained PCH.
-
- // We don't start with the translation unit, but with its decls that
- // don't come from the chained PCH.
- const TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
- SmallVector<KindDeclIDPair, 64> NewGlobalDecls;
- for (DeclContext::decl_iterator I = TU->noload_decls_begin(),
- E = TU->noload_decls_end();
- I != E; ++I) {
- if ((*I)->getPCHLevel() == 0)
- NewGlobalDecls.push_back(std::make_pair((*I)->getKind(), GetDeclRef(*I)));
- else if ((*I)->isChangedSinceDeserialization())
- (void)GetDeclRef(*I); // Make sure it's written, but don't record it.
- }
- // We also need to write a lexical updates block for the TU.
- llvm::BitCodeAbbrev *Abv = new llvm::BitCodeAbbrev();
- Abv->Add(llvm::BitCodeAbbrevOp(TU_UPDATE_LEXICAL));
- Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
- unsigned TuUpdateLexicalAbbrev = Stream.EmitAbbrev(Abv);
- Record.clear();
- Record.push_back(TU_UPDATE_LEXICAL);
- Stream.EmitRecordWithBlob(TuUpdateLexicalAbbrev, Record,
- data(NewGlobalDecls));
- // And a visible updates block for the DeclContexts.
- Abv = new llvm::BitCodeAbbrev();
- Abv->Add(llvm::BitCodeAbbrevOp(UPDATE_VISIBLE));
- Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::VBR, 6));
- Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Fixed, 32));
- Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
- UpdateVisibleAbbrev = Stream.EmitAbbrev(Abv);
- WriteDeclContextVisibleUpdate(TU);
-
- // Build a record containing all of the new tentative definitions in this
- // file, in TentativeDefinitions order.
- RecordData TentativeDefinitions;
- AddLazyVectorDecls(*this, SemaRef.TentativeDefinitions, TentativeDefinitions);
-
- // Build a record containing all of the file scoped decls in this file.
- RecordData UnusedFileScopedDecls;
- AddLazyVectorDecls(*this, SemaRef.UnusedFileScopedDecls,
- UnusedFileScopedDecls);
-
- // Build a record containing all of the delegating constructor decls in this
- // file.
- RecordData DelegatingCtorDecls;
- AddLazyVectorDecls(*this, SemaRef.DelegatingCtorDecls, DelegatingCtorDecls);
-
- // We write the entire table, overwriting the tables from the chain.
- RecordData WeakUndeclaredIdentifiers;
- if (!SemaRef.WeakUndeclaredIdentifiers.empty()) {
- for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
- I = SemaRef.WeakUndeclaredIdentifiers.begin(),
- E = SemaRef.WeakUndeclaredIdentifiers.end(); I != E; ++I) {
- AddIdentifierRef(I->first, WeakUndeclaredIdentifiers);
- AddIdentifierRef(I->second.getAlias(), WeakUndeclaredIdentifiers);
- AddSourceLocation(I->second.getLocation(), WeakUndeclaredIdentifiers);
- WeakUndeclaredIdentifiers.push_back(I->second.getUsed());
- }
- }
-
- // Build a record containing all of the locally-scoped external
- // declarations in this header file. Generally, this record will be
- // empty.
- RecordData LocallyScopedExternalDecls;
- // FIXME: This is filling in the AST file in densemap order which is
- // nondeterminstic!
- for (llvm::DenseMap<DeclarationName, NamedDecl *>::iterator
- TD = SemaRef.LocallyScopedExternalDecls.begin(),
- TDEnd = SemaRef.LocallyScopedExternalDecls.end();
- TD != TDEnd; ++TD) {
- if (TD->second->getPCHLevel() == 0)
- AddDeclRef(TD->second, LocallyScopedExternalDecls);
- }
-
- // Build a record containing all of the ext_vector declarations.
- RecordData ExtVectorDecls;
- AddLazyVectorDecls(*this, SemaRef.ExtVectorDecls, ExtVectorDecls);
-
- // Build a record containing all of the VTable uses information.
- // We write everything here, because it's too hard to determine whether
- // a use is new to this part.
- RecordData VTableUses;
- if (!SemaRef.VTableUses.empty()) {
- for (unsigned I = 0, N = SemaRef.VTableUses.size(); I != N; ++I) {
- AddDeclRef(SemaRef.VTableUses[I].first, VTableUses);
- AddSourceLocation(SemaRef.VTableUses[I].second, VTableUses);
- VTableUses.push_back(SemaRef.VTablesUsed[SemaRef.VTableUses[I].first]);
- }
- }
-
- // Build a record containing all of dynamic classes declarations.
- RecordData DynamicClasses;
- AddLazyVectorDecls(*this, SemaRef.DynamicClasses, DynamicClasses);
-
- // Build a record containing all of pending implicit instantiations.
- RecordData PendingInstantiations;
- for (std::deque<Sema::PendingImplicitInstantiation>::iterator
- I = SemaRef.PendingInstantiations.begin(),
- N = SemaRef.PendingInstantiations.end(); I != N; ++I) {
- AddDeclRef(I->first, PendingInstantiations);
- AddSourceLocation(I->second, PendingInstantiations);
- }
- assert(SemaRef.PendingLocalImplicitInstantiations.empty() &&
- "There are local ones at end of translation unit!");
-
- // Build a record containing some declaration references.
- // It's not worth the effort to avoid duplication here.
- RecordData SemaDeclRefs;
- if (SemaRef.StdNamespace || SemaRef.StdBadAlloc) {
- AddDeclRef(SemaRef.getStdNamespace(), SemaDeclRefs);
- AddDeclRef(SemaRef.getStdBadAlloc(), SemaDeclRefs);
- }
-
- Stream.EnterSubblock(DECLTYPES_BLOCK_ID, NUM_ALLOWED_ABBREVS_SIZE);
- WriteDeclsBlockAbbrevs();
- for (DeclsToRewriteTy::iterator
- I = DeclsToRewrite.begin(), E = DeclsToRewrite.end(); I != E; ++I)
- DeclTypesToEmit.push(const_cast<Decl*>(*I));
- while (!DeclTypesToEmit.empty()) {
- DeclOrType DOT = DeclTypesToEmit.front();
- DeclTypesToEmit.pop();
- if (DOT.isType())
- WriteType(DOT.getType());
- else
- WriteDecl(Context, DOT.getDecl());
- }
- Stream.ExitBlock();
-
- WritePreprocessor(PP);
- WriteSelectors(SemaRef);
- WriteReferencedSelectorsPool(SemaRef);
- WriteIdentifierTable(PP);
- WriteFPPragmaOptions(SemaRef.getFPOptions());
- WriteOpenCLExtensions(SemaRef);
-
- WriteTypeDeclOffsets();
- // FIXME: For chained PCH only write the new mappings (we currently
- // write all of them again).
- WritePragmaDiagnosticMappings(Context.getDiagnostics());
-
- WriteCXXBaseSpecifiersOffsets();
-
/// Build a record containing first declarations from a chained PCH and the
/// most recent declarations in this AST that they point to.
RecordData FirstLatestDeclIDs;
- for (FirstLatestDeclMap::iterator
- I = FirstLatestDecls.begin(), E = FirstLatestDecls.end(); I != E; ++I) {
+ for (FirstLatestDeclMap::iterator I = FirstLatestDecls.begin(),
+ E = FirstLatestDecls.end();
+ I != E; ++I) {
assert(I->first->getPCHLevel() > I->second->getPCHLevel() &&
"Expected first & second to be in different PCHs");
AddDeclRef(I->first, FirstLatestDeclIDs);
AddDeclRef(I->second, FirstLatestDeclIDs);
}
+
if (!FirstLatestDeclIDs.empty())
Stream.EmitRecord(REDECLS_UPDATE_LATEST, FirstLatestDeclIDs);
// Write the record containing declaration references of Sema.
if (!SemaDeclRefs.empty())
Stream.EmitRecord(SEMA_DECL_REFS, SemaDeclRefs);
+
+ // Write the record containing CUDA-specific declaration references.
+ if (!CUDASpecialDeclRefs.empty())
+ Stream.EmitRecord(CUDA_SPECIAL_DECL_REFS, CUDASpecialDeclRefs);
// Write the delegating constructors.
if (!DelegatingCtorDecls.empty())
Stream.EmitRecord(DELEGATING_CTORS, DelegatingCtorDecls);
- // Write the updates to DeclContexts.
+ // Write the known namespaces.
+ if (!KnownNamespaces.empty())
+ Stream.EmitRecord(KNOWN_NAMESPACES, KnownNamespaces);
+
+ // Write the visible updates to DeclContexts.
for (llvm::SmallPtrSet<const DeclContext *, 16>::iterator
- I = UpdatedDeclContexts.begin(),
- E = UpdatedDeclContexts.end();
- I != E; ++I)
+ I = UpdatedDeclContexts.begin(),
+ E = UpdatedDeclContexts.end();
+ I != E; ++I)
WriteDeclContextVisibleUpdate(*I);
WriteDeclUpdatesBlocks();
+ WriteDeclReplacementsBlock();
+ // Some simple statistics
Record.clear();
Record.push_back(NumStatements);
Record.push_back(NumMacros);
Record.push_back(NumLexicalDeclContexts);
Record.push_back(NumVisibleDeclContexts);
- WriteDeclReplacementsBlock();
Stream.EmitRecord(STATISTICS, Record);
Stream.ExitBlock();
}
projects / clang / commitdiff