r266160 - [modules] Refactor handling of cases where we write an offset to a prior record into the bitstream and simplify a little, in preparation for doing this in more cases.

Richard Smith via cfe-commits cfe-commits at lists.llvm.org
Thu Apr 14 11:09:37 PDT 2016


On Thu, Apr 14, 2016 at 9:00 AM, Nico Weber <thakis at chromium.org> wrote:

> On Wed, Apr 13, 2016 at 10:24 PM, Nico Weber <thakis at chromium.org> wrote:
>
>> On Tue, Apr 12, 2016 at 10:12 PM, Richard Smith via cfe-commits <
>> cfe-commits at lists.llvm.org> wrote:
>>
>>> Author: rsmith
>>> Date: Tue Apr 12 21:12:03 2016
>>> New Revision: 266160
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=266160&view=rev
>>> Log:
>>> [modules] Refactor handling of cases where we write an offset to a prior
>>> record into the bitstream and simplify a little, in preparation for doing
>>> this in more cases.
>>>
>>> Modified:
>>>     cfe/trunk/include/clang/Serialization/ASTWriter.h
>>>     cfe/trunk/lib/Serialization/ASTWriter.cpp
>>>     cfe/trunk/lib/Serialization/ASTWriterDecl.cpp
>>>
>>> Modified: cfe/trunk/include/clang/Serialization/ASTWriter.h
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Serialization/ASTWriter.h?rev=266160&r1=266159&r2=266160&view=diff
>>>
>>> ==============================================================================
>>> --- cfe/trunk/include/clang/Serialization/ASTWriter.h (original)
>>> +++ cfe/trunk/include/clang/Serialization/ASTWriter.h Tue Apr 12
>>> 21:12:03 2016
>>> @@ -787,11 +787,29 @@ class ASTRecordWriter {
>>>    /// declaration or type.
>>>    SmallVector<Stmt *, 16> StmtsToEmit;
>>>
>>> +  static constexpr int MaxOffsetIndices = 4;
>>> +  /// \brief Indices of record elements that describe offsets within the
>>> +  /// bitcode. These will be converted to offsets relative to the
>>> current
>>> +  /// record when emitted.
>>> +  unsigned OffsetIndices[MaxOffsetIndices];
>>> +  unsigned NumOffsetIndices = 0;
>>> +
>>>    /// \brief Flush all of the statements and expressions that have
>>>    /// been added to the queue via AddStmt().
>>>    void FlushStmts();
>>>    void FlushSubStmts();
>>>
>>> +  void PrepareToEmit(uint64_t MyOffset) {
>>> +    // Convert offsets into relative form.
>>> +    for (unsigned I = 0; I != NumOffsetIndices; ++I) {
>>> +      auto &StoredOffset = (*Record)[OffsetIndices[I]];
>>> +      assert(StoredOffset < MyOffset && "invalid offset");
>>> +      if (StoredOffset)
>>> +        StoredOffset = MyOffset - StoredOffset;
>>> +    }
>>> +    NumOffsetIndices = 0;
>>> +  }
>>> +
>>>  public:
>>>    /// Construct a ASTRecordWriter that uses the default encoding scheme.
>>>    ASTRecordWriter(ASTWriter &Writer, ASTWriter::RecordDataImpl &Record)
>>> @@ -802,6 +820,10 @@ public:
>>>    ASTRecordWriter(ASTRecordWriter &Parent, ASTWriter::RecordDataImpl
>>> &Record)
>>>        : Writer(Parent.Writer), Record(&Record) {}
>>>
>>> +  /// Copying an ASTRecordWriter is almost certainly a bug.
>>> +  ASTRecordWriter(const ASTRecordWriter&) = delete;
>>> +  void operator=(const ASTRecordWriter&) = delete;
>>> +
>>>    /// \brief Extract the underlying record storage.
>>>    ASTWriter::RecordDataImpl &getRecordData() const { return *Record; }
>>>
>>> @@ -822,6 +844,7 @@ public:
>>>    // FIXME: Allow record producers to suggest Abbrevs.
>>>    uint64_t Emit(unsigned Code, unsigned Abbrev = 0) {
>>>      uint64_t Offset = Writer->Stream.GetCurrentBitNo();
>>> +    PrepareToEmit(Offset);
>>>      Writer->Stream.EmitRecord(Code, *Record, Abbrev);
>>>      FlushStmts();
>>>      return Offset;
>>> @@ -830,10 +853,19 @@ public:
>>>    /// \brief Emit the record to the stream, preceded by its
>>> substatements.
>>>    uint64_t EmitStmt(unsigned Code, unsigned Abbrev = 0) {
>>>      FlushSubStmts();
>>> +    PrepareToEmit(Writer->Stream.GetCurrentBitNo());
>>>      Writer->Stream.EmitRecord(Code, *Record, Abbrev);
>>>      return Writer->Stream.GetCurrentBitNo();
>>>    }
>>>
>>> +  /// \brief Add a bit offset into the record. This will be converted
>>> into an
>>> +  /// offset relative to the current record when emitted.
>>> +  void AddOffset(uint64_t BitOffset) {
>>> +    assert(NumOffsetIndices != MaxOffsetIndices && "too many offset
>>> indices");
>>>
>>
>> This assert is firing when building chrome with clang-cl on Windows:
>> https://build.chromium.org/p/chromium.fyi/builders/ClangToTWin%28dbg%29/builds/5340/steps/compile/logs/stdio
>>
>
> Repro: https://llvm.org/bugs/show_bug.cgi?id=27351
>

Thanks, investigating.


> +    OffsetIndices[NumOffsetIndices++] = Record->size();
>>> +    Record->push_back(BitOffset);
>>> +  }
>>> +
>>>    /// \brief Add the given statement or expression to the queue of
>>>    /// statements to emit.
>>>    ///
>>>
>>> Modified: cfe/trunk/lib/Serialization/ASTWriter.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTWriter.cpp?rev=266160&r1=266159&r2=266160&view=diff
>>>
>>> ==============================================================================
>>> --- cfe/trunk/lib/Serialization/ASTWriter.cpp (original)
>>> +++ cfe/trunk/lib/Serialization/ASTWriter.cpp Tue Apr 12 21:12:03 2016
>>> @@ -4694,6 +4694,7 @@ void ASTWriter::WriteDeclUpdatesBlocks(R
>>>          auto *RD = cast<CXXRecordDecl>(D);
>>>          UpdatedDeclContexts.insert(RD->getPrimaryContext());
>>>          Record.AddCXXDefinitionData(RD);
>>> +        // FIXME: Use AddOffset here.
>>>          Record.push_back(WriteDeclContextLexicalBlock(
>>>              *Context, const_cast<CXXRecordDecl *>(RD)));
>>>
>>>
>>> Modified: cfe/trunk/lib/Serialization/ASTWriterDecl.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTWriterDecl.cpp?rev=266160&r1=266159&r2=266160&view=diff
>>>
>>> ==============================================================================
>>> --- cfe/trunk/lib/Serialization/ASTWriterDecl.cpp (original)
>>> +++ cfe/trunk/lib/Serialization/ASTWriterDecl.cpp Tue Apr 12 21:12:03
>>> 2016
>>> @@ -125,8 +125,7 @@ namespace clang {
>>>      void VisitCapturedDecl(CapturedDecl *D);
>>>      void VisitEmptyDecl(EmptyDecl *D);
>>>
>>> -    void VisitDeclContext(DeclContext *DC, uint64_t LexicalOffset,
>>> -                          uint64_t VisibleOffset);
>>> +    void VisitDeclContext(DeclContext *DC);
>>>      template <typename T> void VisitRedeclarable(Redeclarable<T> *D);
>>>
>>>
>>> @@ -149,12 +148,6 @@ namespace clang {
>>>      void VisitOMPDeclareReductionDecl(OMPDeclareReductionDecl *D);
>>>      void VisitOMPCapturedExprDecl(OMPCapturedExprDecl *D);
>>>
>>> -    void AddLocalOffset(uint64_t LocalOffset) {
>>> -      uint64_t Offset = Writer.Stream.GetCurrentBitNo();
>>> -      assert(LocalOffset < Offset && "invalid offset");
>>> -      Record.push_back(LocalOffset ? Offset - LocalOffset : 0);
>>> -    }
>>> -
>>>      /// Add an Objective-C type parameter list to the given record.
>>>      void AddObjCTypeParamList(ObjCTypeParamList *typeParams) {
>>>        // Empty type parameter list.
>>> @@ -284,6 +277,12 @@ void ASTDeclWriter::Visit(Decl *D) {
>>>      if (FD->doesThisDeclarationHaveABody())
>>>        Record.AddFunctionDefinition(FD);
>>>    }
>>> +
>>> +  // If this declaration is also a DeclContext, write blocks for the
>>> +  // declarations that lexically stored inside its context and those
>>> +  // declarations that are visible from its context.
>>> +  if (DeclContext *DC = dyn_cast<DeclContext>(D))
>>> +    VisitDeclContext(DC);
>>>  }
>>>
>>>  void ASTDeclWriter::VisitDecl(Decl *D) {
>>> @@ -1553,10 +1552,9 @@ void ASTDeclWriter::VisitStaticAssertDec
>>>  /// that there are no declarations visible from this context. Note
>>>  /// that this value will not be emitted for non-primary declaration
>>>  /// contexts.
>>> -void ASTDeclWriter::VisitDeclContext(DeclContext *DC, uint64_t
>>> LexicalOffset,
>>> -                                     uint64_t VisibleOffset) {
>>> -  AddLocalOffset(LexicalOffset);
>>> -  AddLocalOffset(VisibleOffset);
>>> +void ASTDeclWriter::VisitDeclContext(DeclContext *DC) {
>>> +  Record.AddOffset(Writer.WriteDeclContextLexicalBlock(Context, DC));
>>> +  Record.AddOffset(Writer.WriteDeclContextVisibleBlock(Context, DC));
>>>  }
>>>
>>>  const Decl *ASTWriter::getFirstLocalDecl(const Decl *D) {
>>> @@ -1624,9 +1622,8 @@ void ASTDeclWriter::VisitRedeclarable(Re
>>>        // the declaration itself.
>>>        if (LocalRedecls.empty())
>>>          Record.push_back(0);
>>> -      else {
>>> -        AddLocalOffset(LocalRedeclWriter.Emit(LOCAL_REDECLARATIONS));
>>> -      }
>>> +      else
>>> +        Record.AddOffset(LocalRedeclWriter.Emit(LOCAL_REDECLARATIONS));
>>>      } else {
>>>        Record.push_back(0);
>>>        Record.AddDeclRef(FirstLocal);
>>> @@ -2148,26 +2145,12 @@ void ASTWriter::WriteDecl(ASTContext &Co
>>>    ID = IDR;
>>>
>>>    assert(ID >= FirstDeclID && "invalid decl ID");
>>> -
>>> -  // If this declaration is also a DeclContext, write blocks for the
>>> -  // declarations that lexically stored inside its context and those
>>> -  // declarations that are visible from its context. These blocks
>>> -  // are written before the declaration itself so that we can put
>>> -  // their offsets into the record for the declaration.
>>> -  uint64_t LexicalOffset = 0;
>>> -  uint64_t VisibleOffset = 0;
>>> -  DeclContext *DC = dyn_cast<DeclContext>(D);
>>> -  if (DC) {
>>> -    LexicalOffset = WriteDeclContextLexicalBlock(Context, DC);
>>> -    VisibleOffset = WriteDeclContextVisibleBlock(Context, DC);
>>> -  }
>>>
>>>    RecordData Record;
>>>    ASTDeclWriter W(*this, Context, Record);
>>>
>>>    // Build a record for this declaration
>>>    W.Visit(D);
>>> -  if (DC) W.VisitDeclContext(DC, LexicalOffset, VisibleOffset);
>>>
>>>    // Emit this declaration to the bitstream.
>>>    uint64_t Offset = W.Emit(D);
>>>
>>>
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>>>
>>
>>
>
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