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llvm::gsym::GsymReader Class Reference

GsymReader is used to read GSYM data from a file or buffer. More...

#include "llvm/DebugInfo/GSYM/GsymReader.h"

Public Member Functions

 GsymReader (GsymReader &&RHS)
 
 ~GsymReader ()
 
const HeadergetHeader () const
 Access the GSYM header. More...
 
llvm::Expected< FunctionInfogetFunctionInfo (uint64_t Addr) const
 Get the full function info for an address. More...
 
StringRef getString (uint32_t Offset) const
 Get a string from the string table. More...
 

Static Public Member Functions

static llvm::Expected< GsymReaderopenFile (StringRef Path)
 Construct a GsymReader from a file on disk. More...
 
static llvm::Expected< GsymReadercopyBuffer (StringRef Bytes)
 Construct a GsymReader from a buffer. More...
 

Protected Member Functions

Optional< uint64_t > getAddress (size_t Index) const
 Gets an address from the address table. More...
 
Optional< FileEntrygetFile (uint32_t Index) const
 Get the a file entry for the suppplied file index. More...
 
template<class T >
ArrayRef< TgetAddrOffsets () const
 Get an appropriate address info offsets array. More...
 
template<class T >
Optional< uint64_t > addressForIndex (size_t Index) const
 Get an appropriate address from the address table. More...
 
template<class T >
uint64_t getAddressOffsetIndex (const uint64_t AddrOffset) const
 Lookup an address offset in the AddrOffsets table. More...
 
Expected< uint64_t > getAddressIndex (const uint64_t Addr) const
 Given an address, find the address index. More...
 
Optional< uint64_t > getAddressInfoOffset (size_t Index) const
 Given an address index, get the offset for the FunctionInfo. More...
 

Static Protected Member Functions

static llvm::Expected< llvm::gsym::GsymReadercreate (std::unique_ptr< MemoryBuffer > &MemBuffer)
 Create a GSYM from a memory buffer. More...
 

Detailed Description

GsymReader is used to read GSYM data from a file or buffer.

This class is optimized for very quick lookups when the endianness matches the host system. The Header, address table, address info offsets, and file table is designed to be mmap'ed as read only into memory and used without any parsing needed. If the endianness doesn't match, we swap these objects and tables into GsymReader::SwappedData and then point our header and ArrayRefs to this swapped internal data.

GsymReader objects must use one of the static functions to create an instance: GsymReader::openFile(...) and GsymReader::copyBuffer(...).

Definition at line 48 of file GsymReader.h.

Constructor & Destructor Documentation

◆ GsymReader()

GsymReader::GsymReader ( GsymReader &&  RHS)
default

◆ ~GsymReader()

GsymReader::~GsymReader ( )
default

Member Function Documentation

◆ addressForIndex()

template<class T >
Optional<uint64_t> llvm::gsym::GsymReader::addressForIndex ( size_t  Index) const
inlineprotected

Get an appropriate address from the address table.

The address table in the GSYM file is stored as array of 1, 2, 4 or 8 byte address offsets from the The gsym::Header::BaseAddress. The table is stored internally as a array of bytes that are in the correct endianness. In order to extract an address from the address table we must access the address offset using the correct size and then add it to the BaseAddress in the header.

Parameters
IndexAn index into the AddrOffsets array.
Returns
An virtual address that matches the original object file for the address as the specified index, or llvm::None if Index is out of bounds.

Definition at line 163 of file GsymReader.h.

References llvm::gsym::Header::BaseAddress, llvm::None, and llvm::ArrayRef< T >::size().

◆ copyBuffer()

llvm::Expected< GsymReader > GsymReader::copyBuffer ( StringRef  Bytes)
static

Construct a GsymReader from a buffer.

Parameters
BytesA set of bytes that will be copied and owned by the returned object on success.
Returns
An expected GsymReader that contains the object or an error object that indicates reason for failing to read the GSYM.

Definition at line 45 of file GsymReader.cpp.

References llvm::MemoryBuffer::getMemBufferCopy().

◆ create()

llvm::Expected< llvm::gsym::GsymReader > GsymReader::create ( std::unique_ptr< MemoryBuffer > &  MemBuffer)
staticprotected

Create a GSYM from a memory buffer.

Called by both openFile() and copyBuffer(), this function does all of the work of parsing the GSYM file and returning an error.

Parameters
MemBufferA memory buffer that will transfer ownership into the GsymReader.
Returns
An expected GsymReader that contains the object or an error object that indicates reason for failing to read the GSYM.

Definition at line 51 of file GsymReader.cpp.

References llvm::createStringError().

◆ getAddress()

Optional< uint64_t > GsymReader::getAddress ( size_t  Index) const
protected

Gets an address from the address table.

Addresses are stored as offsets frrom the gsym::Header::BaseAddress.

Parameters
IndexA index into the address table.
Returns
A resolved virtual address for adddress in the address table or llvm::None if Index is out of bounds.

Definition at line 210 of file GsymReader.cpp.

References llvm::None.

Referenced by getString().

◆ getAddressIndex()

Expected< uint64_t > GsymReader::getAddressIndex ( const uint64_t  Addr) const
protected

Given an address, find the address index.

Binary search the address table and find the matching address index.

Parameters
AddrA virtual address that matches the original object file to lookup.
Returns
An index into the address table. This index can be used to extract the FunctionInfo data's offset from the AddrInfoOffsets array. Returns an error if the address isn't in the GSYM with details of why.

Definition at line 228 of file GsymReader.cpp.

References llvm::createStringError().

◆ getAddressInfoOffset()

Optional< uint64_t > GsymReader::getAddressInfoOffset ( size_t  Index) const
protected

Given an address index, get the offset for the FunctionInfo.

Looking up an address is done by finding the corresponding address index for the address. This index is then used to get the offset of the FunctionInfo data that we will decode using this function.

Parameters
IndexAn index into the address table.
Returns
An optional GSYM data offset for the offset of the FunctionInfo that needs to be decoded.

Definition at line 220 of file GsymReader.cpp.

References llvm::None.

◆ getAddressOffsetIndex()

template<class T >
uint64_t llvm::gsym::GsymReader::getAddressOffsetIndex ( const uint64_t  AddrOffset) const
inlineprotected

Lookup an address offset in the AddrOffsets table.

Given an address offset, look it up using a binary search of the AddrOffsets table.

Parameters
AddrOffsetAn address offset, that has already been computed by subtracting the gsym::Header::BaseAddress.
Returns
The matching address offset index. This index will be used to extract the FunctionInfo data's offset from the AddrInfoOffsets array.

Definition at line 179 of file GsymReader.h.

References llvm::ArrayRef< T >::begin().

◆ getAddrOffsets()

template<class T >
ArrayRef<T> llvm::gsym::GsymReader::getAddrOffsets ( ) const
inlineprotected

Get an appropriate address info offsets array.

The address table in the GSYM file is stored as array of 1, 2, 4 or 8 byte offsets from the The gsym::Header::BaseAddress. The table is stored internally as a array of bytes that are in the correct endianness. When we access this table we must get an array that matches those sizes. This templatized helper function is used when accessing address offsets in the AddrOffsets member variable.

Returns
An ArrayRef of an appropriate address offset size.

Definition at line 145 of file GsymReader.h.

References llvm::ArrayRef< T >::data(), llvm::ArrayRef< T >::size(), and T.

◆ getFile()

Optional<FileEntry> llvm::gsym::GsymReader::getFile ( uint32_t  Index) const
inlineprotected

Get the a file entry for the suppplied file index.

Used to convert any file indexes in the FunctionInfo data back into files. This function can be used for iteration, but is more commonly used for random access when doing lookups.

Parameters
IndexAn index into the file table.
Returns
An optional FileInfo that will be valid if the file index is valid, or llvm::None if the file index is out of bounds,

Definition at line 128 of file GsymReader.h.

References llvm::None, and llvm::ArrayRef< T >::size().

◆ getFunctionInfo()

llvm::Expected< FunctionInfo > GsymReader::getFunctionInfo ( uint64_t  Addr) const

Get the full function info for an address.

Parameters
AddrA virtual address from the orignal object file to lookup.
Returns
An expected FunctionInfo that contains the function info object or an error object that indicates reason for failing to lookup the address,

Definition at line 245 of file GsymReader.cpp.

References assert(), llvm::createStringError(), llvm::Data, llvm::gsym::FunctionInfo::decode(), and llvm::Expected< T >::takeError().

◆ getHeader()

const Header & GsymReader::getHeader ( ) const

Access the GSYM header.

Returns
A native endian version of the GSYM header.

Definition at line 202 of file GsymReader.cpp.

References assert().

◆ getString()

StringRef llvm::gsym::GsymReader::getString ( uint32_t  Offset) const
inline

Get a string from the string table.

Parameters
OffsetThe string table offset for the string to retrieve.
Returns
The string from the strin table.

Definition at line 107 of file GsymReader.h.

References getAddress().

◆ openFile()

llvm::Expected< GsymReader > GsymReader::openFile ( StringRef  Path)
static

Construct a GsymReader from a file on disk.

Parameters
PathThe file path the GSYM file to read.
Returns
An expected GsymReader that contains the object or an error object that indicates reason for failing to read the GSYM.

Definition at line 35 of file GsymReader.cpp.

References llvm::MemoryBuffer::getFileOrSTDIN().


The documentation for this class was generated from the following files: