LLVM: llvm::gsym::GsymCreator Class Reference (original) (raw)

GsymCreator is used to emit GSYM data to a stand alone file or section within a file. More...

#include "[llvm/DebugInfo/GSYM/GsymCreator.h](GsymCreator%5F8h%5Fsource.html)"

Public Member Functions
LLVM_ABI GsymCreator (bool Quiet=false)
LLVM_ABI llvm::Error save (StringRef Path, llvm::endianness ByteOrder, std::optional< uint64_t > SegmentSize=std::nullopt) const
Save a GSYM file to a stand alone file.
LLVM_ABI llvm::Error encode (FileWriter &O) const
Encode a GSYM into the file writer stream at the current position.
LLVM_ABI uint32_t insertString (StringRef S, bool Copy=true)
Insert a string into the GSYM string table.
LLVM_ABI StringRef getString (uint32_t Offset)
Retrieve a string from the GSYM string table given its offset.
LLVM_ABI uint32_t insertFile (StringRef Path, sys::path::Style Style=sys::path::Style::native)
Insert a file into this GSYM creator.
LLVM_ABI void addFunctionInfo (FunctionInfo &&FI)
Add a function info to this GSYM creator.
LLVM_ABI llvm::Error loadCallSitesFromYAML (StringRef YAMLFile)
Load call site information from a YAML file.
LLVM_ABI void prepareMergedFunctions (OutputAggregator &Out)
Organize merged FunctionInfo's.
LLVM_ABI llvm::Error finalize (OutputAggregator &OS)
Finalize the data in the GSYM creator prior to saving the data out.
void setUUID (llvm::ArrayRef< uint8_t > UUIDBytes)
Set the UUID value.
LLVM_ABI void forEachFunctionInfo (std::function< bool(FunctionInfo &)> const &Callback)
Thread safe iteration over all function infos.
LLVM_ABI void forEachFunctionInfo (std::function< bool(const FunctionInfo &)> const &Callback) const
Thread safe const iteration over all function infos.
LLVM_ABI size_t getNumFunctionInfos () const
Get the current number of FunctionInfo objects contained in this object.
void SetValidTextRanges (AddressRanges &TextRanges)
Set valid .text address ranges that all functions must be contained in.
const std::optional< AddressRanges > GetValidTextRanges () const
Get the valid text ranges.
LLVM_ABI bool IsValidTextAddress (uint64_t Addr) const
Check if an address is a valid code address.
void setBaseAddress (uint64_t Addr)
Set the base address to use for the GSYM file.
bool isQuiet () const
Whether the transformation should be quiet, i.e. not output warnings.
LLVM_ABI llvm::Expected< std::unique_ptr< GsymCreator > > createSegment (uint64_t SegmentSize, size_t &FuncIdx) const
Create a segmented GSYM creator starting with function info index FuncIdx.

GsymCreator is used to emit GSYM data to a stand alone file or section within a file.

The GsymCreator is designed to be used in 3 stages:

The first stage involves creating FunctionInfo objects from another source of information like compiler debug info metadata, DWARF or Breakpad files. Any strings in the FunctionInfo or contained information, like InlineInfo or LineTable objects, should get the string table offsets by calling GsymCreator::insertString(...). Any file indexes that are needed should be obtained by calling GsymCreator::insertFile(...). All of the function calls in GsymCreator are thread safe. This allows multiple threads to create and add FunctionInfo objects while parsing debug information.

Once all of the FunctionInfo objects have been added, the GsymCreator::finalize(...) must be called prior to saving. This function will sort the FunctionInfo objects, finalize the string table, and do any other passes on the information needed to prepare the information to be saved.

Once the object has been finalized, it can be saved to a file or section.

ENCODING

GSYM files are designed to be memory mapped into a process as shared, read only data, and used as is.

The GSYM file format when in a stand alone file consists of:

HEADER

The header is fully described in "llvm/DebugInfo/GSYM/Header.h".

ADDRESS TABLE

The address table immediately follows the header in the file and consists of Header.NumAddresses address offsets. These offsets are sorted and can be binary searched for efficient lookups. Addresses in the address table are stored as offsets from a 64 bit base address found in Header.BaseAddress. This allows the address table to contain 8, 16, or 32 offsets. This allows the address table to not require full 64 bit addresses for each address. The resulting GSYM size is smaller and causes fewer pages to be touched during address lookups when the address table is smaller. The size of the address offsets in the address table is specified in the header in Header.AddrOffSize. The first offset in the address table is aligned to Header.AddrOffSize alignment to ensure efficient access when loaded into memory.

FUNCTION INFO OFFSETS TABLE

The function info offsets table immediately follows the address table and consists of Header.NumAddresses 32 bit file offsets: one for each address in the address table. This data is aligned to a 4 byte boundary. The offsets in this table are the relative offsets from the start offset of the GSYM header and point to the function info data for each address in the address table. Keeping this data separate from the address table helps to reduce the number of pages that are touched when address lookups occur on a GSYM file.

FILE TABLE

The file table immediately follows the function info offsets table. The encoding of the FileTable is:

struct FileTable { uint32_t Count; FileEntry Files[]; };

The file table starts with a 32 bit count of the number of files that are used in all of the function info, followed by that number of FileEntry structures. The file table is aligned to a 4 byte boundary, Each file in the file table is represented with a FileEntry structure. See "llvm/DebugInfo/GSYM/FileEntry.h" for details.

STRING TABLE

The string table follows the file table in stand alone GSYM files and contains all strings for everything contained in the GSYM file. Any string data should be added to the string table and any references to strings inside GSYM information must be stored as 32 bit string table offsets into this string table. The string table always starts with an empty string at offset zero and is followed by any strings needed by the GSYM information. The start of the string table is not aligned to any boundary.

FUNCTION INFO DATA

The function info data is the payload that contains information about the address that is being looked up. It contains all of the encoded FunctionInfo objects. Each encoded FunctionInfo's data is pointed to by an entry in the Function Info Offsets Table. For details on the exact encoding of FunctionInfo objects, see "llvm/DebugInfo/GSYM/FunctionInfo.h".

Definition at line 135 of file GsymCreator.h.

GsymCreator::GsymCreator ( bool Quiet = false )

◆ addFunctionInfo()

Add a function info to this GSYM creator.

All information in the FunctionInfo object must use the GsymCreator::insertString(...) function when creating string table offsets for names and other strings.

Parameters

FI The function info object to emplace into our functions list.

Definition at line 396 of file GsymCreator.cpp.

Referenced by llvm::gsym::ObjectFileTransformer::convert().

◆ createSegment()

Create a segmented GSYM creator starting with function info index FuncIdx.

This function will create a GsymCreator object that will encode into roughly SegmentSize bytes and return it. It is used by the private saveSegments(...) function and also is used by the GSYM unit tests to test segmenting of GSYM files. The returned GsymCreator can be finalized and encoded.

Parameters

[in] SegmentSize The size in bytes to roughly segment the GSYM file into.
[in,out] FuncIdx The index of the first function info to encode into the returned GsymCreator. This index will be updated so it can be used in subsequent calls to this function to allow more segments to be created.

Returns

An expected unique pointer to a GsymCreator or an error. The returned unique pointer can be NULL if there are no more functions to encode.

Definition at line 580 of file GsymCreator.cpp.

References llvm::alignTo(), llvm::createStringError(), and GsymCreator().

◆ encode()

Encode a GSYM into the file writer stream at the current position.

Parameters

O The stream to save the binary data to

Returns

An error object that indicates success or failure of the save.

Definition at line 80 of file GsymCreator.cpp.

References llvm::gsym::Header::AddrOffSize, assert(), llvm::sampleprof::Base, llvm::gsym::Header::BaseAddress, llvm::createStringError(), llvm::gsym::Header::encode(), llvm::gsym::GSYM_MAGIC, llvm::gsym::GSYM_VERSION, llvm::gsym::Header::Magic, llvm::gsym::Header::NumAddresses, llvm::Offset, offsetof, llvm::gsym::Header::StrtabOffset, llvm::gsym::Header::StrtabSize, llvm::gsym::Header::UUID, llvm::gsym::Header::UUIDSize, and llvm::gsym::Header::Version.

Referenced by save().

◆ finalize()

Finalize the data in the GSYM creator prior to saving the data out.

Finalize must be called after all FunctionInfo objects have been added and before GsymCreator::save() is called.

Parameters

OS Output stream to report duplicate function infos, overlapping function infos, and function infos that were merged or removed.

Returns

An error object that indicates success or failure of the finalize.

Definition at line 241 of file GsymCreator.cpp.

References llvm::AddressRange::contains(), llvm::createStringError(), llvm::gsym::FunctionInfo::hasRichInfo(), llvm::AddressRange::intersects(), llvm::gsym::FunctionInfo::Range, Range, llvm::gsym::OutputAggregator::Report(), llvm::AddressRange::size(), llvm::stable_sort(), llvm::AddressRange::start(), llvm::Error::success(), and std::swap().

◆ forEachFunctionInfo() [1/2]

Thread safe const iteration over all function infos.

Parameters

Callback A callback function that will get called with each FunctionInfo. If the callback returns false, stop iterating.

Definition at line 410 of file GsymCreator.cpp.

◆ forEachFunctionInfo() [2/2]

Thread safe iteration over all function infos.

Parameters

Callback A callback function that will get called with each FunctionInfo. If the callback returns false, stop iterating.

Definition at line 401 of file GsymCreator.cpp.

◆ getNumFunctionInfos()

size_t GsymCreator::getNumFunctionInfos ( ) const

◆ getString()

Retrieve a string from the GSYM string table given its offset.

The offset is assumed to be a valid offset into the string table. otherwise an assert will be triggered.

Parameters

Offset The offset of the string to retrieve, previously returned by insertString.

Returns

The string at the given offset in the string table.

Definition at line 389 of file GsymCreator.cpp.

References assert(), I, and llvm::Offset.

◆ GetValidTextRanges()

const std::optional< AddressRanges > llvm::gsym::GsymCreator::GetValidTextRanges ( ) const inline

◆ insertFile()

◆ insertString()

◆ isQuiet()

bool llvm::gsym::GsymCreator::isQuiet ( ) const inline

Whether the transformation should be quiet, i.e. not output warnings.

Definition at line 468 of file GsymCreator.h.

◆ IsValidTextAddress()

Check if an address is a valid code address.

Any functions whose addresses do not exist within these function bounds will not be converted into the final GSYM. This allows the object file to figure out the valid file address ranges of all the code sections and ensure we don't add invalid functions to the final output. Many linkers have issues when dead stripping functions from DWARF debug info where they set the DW_AT_low_pc to zero, but newer DWARF has the DW_AT_high_pc as an offset from the DW_AT_low_pc and these size attributes have no relocations that can be applied. This results in DWARF where many functions have an DW_AT_low_pc of zero and a valid offset size for DW_AT_high_pc. If we extract all valid ranges from an object file that are marked with executable permissions, we can properly ensure that these functions are removed.

Parameters

Returns

True if the address is in the valid text ranges or if no valid text ranges have been set, false otherwise.

Definition at line 424 of file GsymCreator.cpp.

Referenced by llvm::gsym::ObjectFileTransformer::convert().

◆ loadCallSitesFromYAML()

Load call site information from a YAML file.

This function reads call site information from a specified YAML file and adds it to the GSYM data.

Parameters

YAMLFile The path to the YAML file containing call site information.

Definition at line 192 of file GsymCreator.cpp.

References llvm::gsym::CallSiteInfoLoader::loadYAML().

◆ prepareMergedFunctions()

◆ save()

Save a GSYM file to a stand alone file.

Parameters

Path The file path to save the GSYM file to.
ByteOrder The endianness to use when saving the file.
SegmentSize The size in bytes to segment the GSYM file into. If this option is set this function will create N segments that are all around SegmentSize bytes in size. This allows a very large GSYM file to be broken up into shards. Each GSYM file will have its own file table, and string table that only have the files and strings needed for the shared. If this argument has no value, a single GSYM file that contains all function information will be created.

Returns

An error object that indicates success or failure of the save.

Definition at line 68 of file GsymCreator.cpp.

References encode(), and llvm::errorCodeToError().

◆ setBaseAddress()

void llvm::gsym::GsymCreator::setBaseAddress ( uint64_t Addr) inline

Set the base address to use for the GSYM file.

Setting the base address to use for the GSYM file. Object files typically get loaded from a base address when the OS loads them into memory. Using GSYM files for symbolication becomes easier if the base address in the GSYM header is the same address as it allows addresses to be easily slid and allows symbolication without needing to find the original base address in the original object file.

Parameters

Addr The address to use as the base address of the GSYM file when it is saved to disk.

Definition at line 463 of file GsymCreator.h.

◆ setUUID()

◆ SetValidTextRanges()

void llvm::gsym::GsymCreator::SetValidTextRanges ( AddressRanges & TextRanges) inline

Set valid .text address ranges that all functions must be contained in.

Definition at line 422 of file GsymCreator.h.

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