class LazyRandomTypeCollection

Declaration

class LazyRandomTypeCollection : public TypeCollection { /* full declaration omitted */ };

Description

Provides amortized O(1) random access to a CodeView type stream. Normally to access a type from a type stream, you must know its byte offset into the type stream, because type records are variable-lengthed. However, this is not the way we prefer to access them. For example, given a symbol record one of the fields may be the TypeIndex of the symbol's type record. Or given a type record such as an array type, there might be a TypeIndex for the element type. Sequential access is perfect when we're just dumping every entry, but it's very poor for real world usage. Type streams in PDBs contain an additional field which is a list of pairs containing indices and their corresponding offsets, roughly every ~8KB of record data. This general idea need not be confined to PDBs though. By supplying such an array, the producer of a type stream can allow the consumer much better access time, because the consumer can find the nearest index in this array, and do a linear scan forward only from there. LazyRandomTypeCollection implements this algorithm, but additionally goes one step further by caching offsets of every record that has been visited at least once. This way, even repeated visits of the same record will never require more than one linear scan. For a type stream of N elements divided into M chunks of roughly equal size, this yields a worst case lookup time of O(N/M) and an amortized time of O(1).

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:50

Inherits from: TypeCollection

Method Overview

• public LazyRandomTypeCollection(llvm::StringRef Data, uint32_t RecordCountHint)
• public LazyRandomTypeCollection(ArrayRef<uint8_t> Data, uint32_t RecordCountHint)
• public LazyRandomTypeCollection(const llvm::codeview::CVTypeArray & Types, uint32_t RecordCountHint, llvm::codeview::LazyRandomTypeCollection::PartialOffsetArray PartialOffsets)
• public LazyRandomTypeCollection(const llvm::codeview::CVTypeArray & Types, uint32_t RecordCountHint)
• public LazyRandomTypeCollection(uint32_t RecordCountHint)
• public uint32_t capacity()
• public bool contains(llvm::codeview::TypeIndex Index)
• public Optional<llvm::codeview::TypeIndex> getFirst()
• public Optional<llvm::codeview::TypeIndex> getNext(llvm::codeview::TypeIndex Prev)
• public uint32_t getOffsetOfType(llvm::codeview::TypeIndex Index)
• public llvm::codeview::CVType getType(llvm::codeview::TypeIndex Index)
• public llvm::StringRef getTypeName(llvm::codeview::TypeIndex Index)
• public void reset(llvm::BinaryStreamReader & Reader, uint32_t RecordCountHint)
• public void reset(llvm::StringRef Data, uint32_t RecordCountHint)
• public void reset(ArrayRef<uint8_t> Data, uint32_t RecordCountHint)
• public uint32_t size()
• public Optional<llvm::codeview::CVType> tryGetType(llvm::codeview::TypeIndex Index)

Inherited from TypeCollection:

• public ForEachRecord
• public capacity
• public contains
• public empty
• public getFirst
• public getNext
• public getType
• public getTypeName
• public size

Methods

¶LazyRandomTypeCollection(llvm::StringRef Data,
                         uint32_t RecordCountHint)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:61

Parameters

llvm::StringRef Data

uint32_t RecordCountHint

¶LazyRandomTypeCollection(ArrayRef<uint8_t> Data,
                         uint32_t RecordCountHint)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:62

Parameters

ArrayRef<uint8_t> Data

uint32_t RecordCountHint

¶LazyRandomTypeCollection(
    const llvm::codeview::CVTypeArray& Types,
    uint32_t RecordCountHint,
    llvm::codeview::LazyRandomTypeCollection::
        PartialOffsetArray PartialOffsets)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:63

Parameters

const llvm::codeview::CVTypeArray& Types

uint32_t RecordCountHint

llvm::codeview::LazyRandomTypeCollection:: PartialOffsetArray PartialOffsets

¶LazyRandomTypeCollection(
    const llvm::codeview::CVTypeArray& Types,
    uint32_t RecordCountHint)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:65

Parameters

const llvm::codeview::CVTypeArray& Types

uint32_t RecordCountHint

¶LazyRandomTypeCollection(uint32_t RecordCountHint)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:60

Parameters

uint32_t RecordCountHint

¶uint32_t capacity()

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:79

¶bool contains(llvm::codeview::TypeIndex Index)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:77

Parameters

llvm::codeview::TypeIndex Index

¶Optional<llvm::codeview::TypeIndex> getFirst()

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:80

¶Optional<llvm::codeview::TypeIndex> getNext(
    llvm::codeview::TypeIndex Prev)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:81

Parameters

llvm::codeview::TypeIndex Prev

¶uint32_t getOffsetOfType(
    llvm::codeview::TypeIndex Index)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:71

Parameters

llvm::codeview::TypeIndex Index

¶llvm::codeview::CVType getType(
    llvm::codeview::TypeIndex Index)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:75

Parameters

llvm::codeview::TypeIndex Index

¶llvm::StringRef getTypeName(
    llvm::codeview::TypeIndex Index)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:76

Parameters

llvm::codeview::TypeIndex Index

¶void reset(llvm::BinaryStreamReader& Reader,
           uint32_t RecordCountHint)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:69

Parameters

llvm::BinaryStreamReader& Reader

uint32_t RecordCountHint

¶void reset(llvm::StringRef Data,
           uint32_t RecordCountHint)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:68

Parameters

llvm::StringRef Data

uint32_t RecordCountHint

¶void reset(ArrayRef<uint8_t> Data,
           uint32_t RecordCountHint)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:67

Parameters

ArrayRef<uint8_t> Data

uint32_t RecordCountHint

¶uint32_t size()

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:78

¶Optional<llvm::codeview::CVType> tryGetType(
    llvm::codeview::TypeIndex Index)

Declared at: llvm/include/llvm/DebugInfo/CodeView/LazyRandomTypeCollection.h:73

Parameters

llvm::codeview::TypeIndex Index