//===- llvm/Bitcode/BitcodeReader.h - Bitcode reader ------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This header defines interfaces to read LLVM bitcode files/streams.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_BITCODE_BITCODEREADER_H
#define LLVM_BITCODE_BITCODEREADER_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Bitstream/BitCodeEnums.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/MemoryBufferRef.h"
#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <system_error>
#include <vector>
namespace llvm {
class LLVMContext;
class Module;
class MemoryBuffer;
class Metadata;
class ModuleSummaryIndex;
class Type;
class Value;
// Callback to override the data layout string of an imported bitcode module.
// The first argument is the target triple, the second argument the data layout
// string from the input, or a default string. It will be used if the callback
// returns std::nullopt.
typedef std::function<std::optional<std::string>(StringRef, StringRef)>
DataLayoutCallbackFuncTy;
typedef std::function<Type *(unsigned)> GetTypeByIDTy;
typedef std::function<unsigned(unsigned, unsigned)> GetContainedTypeIDTy;
typedef std::function<void(Value *, unsigned, GetTypeByIDTy,
GetContainedTypeIDTy)>
ValueTypeCallbackTy;
typedef std::function<void(Metadata **, unsigned, GetTypeByIDTy,
GetContainedTypeIDTy)>
MDTypeCallbackTy;
// These functions are for converting Expected/Error values to
// ErrorOr/std::error_code for compatibility with legacy clients. FIXME:
// Remove these functions once no longer needed by the C and libLTO APIs.
std::error_code errorToErrorCodeAndEmitErrors(LLVMContext &Ctx, Error Err);
template <typename T>
ErrorOr<T> expectedToErrorOrAndEmitErrors(LLVMContext &Ctx, Expected<T> Val) {
if (!Val)
return errorToErrorCodeAndEmitErrors(Ctx, Val.takeError());
return std::move(*Val);
}
struct ParserCallbacks {
std::optional<DataLayoutCallbackFuncTy> DataLayout;
/// The ValueType callback is called for every function definition or
/// declaration and allows accessing the type information, also behind
/// pointers. This can be useful, when the opaque pointer upgrade cleans all
/// type information behind pointers.
/// The second argument to ValueTypeCallback is the type ID of the
/// function, the two passed functions can be used to extract type
/// information.
std::optional<ValueTypeCallbackTy> ValueType;
/// The MDType callback is called for every value in metadata.
std::optional<MDTypeCallbackTy> MDType;
ParserCallbacks() = default;
explicit ParserCallbacks(DataLayoutCallbackFuncTy DataLayout)
: DataLayout(DataLayout) {}
};
struct BitcodeFileContents;
/// Basic information extracted from a bitcode module to be used for LTO.
struct BitcodeLTOInfo {
bool IsThinLTO;
bool HasSummary;
bool EnableSplitLTOUnit;
};
/// Represents a module in a bitcode file.
class BitcodeModule {
// This covers the identification (if present) and module blocks.
ArrayRef<uint8_t> Buffer;
StringRef ModuleIdentifier;
// The string table used to interpret this module.
StringRef Strtab;
// The bitstream location of the IDENTIFICATION_BLOCK.
uint64_t IdentificationBit;
// The bitstream location of this module's MODULE_BLOCK.
uint64_t ModuleBit;
BitcodeModule(ArrayRef<uint8_t> Buffer, StringRef ModuleIdentifier,
uint64_t IdentificationBit, uint64_t ModuleBit)
: Buffer(Buffer), ModuleIdentifier(ModuleIdentifier),
IdentificationBit(IdentificationBit), ModuleBit(ModuleBit) {}
// Calls the ctor.
friend Expected<BitcodeFileContents>
getBitcodeFileContents(MemoryBufferRef Buffer);
Expected<std::unique_ptr<Module>>
getModuleImpl(LLVMContext &Context, bool MaterializeAll,
bool ShouldLazyLoadMetadata, bool IsImporting,
ParserCallbacks Callbacks = {});
public:
StringRef getBuffer() const {
return StringRef((const char *)Buffer.begin(), Buffer.size());
}
StringRef getStrtab() const { return Strtab; }
StringRef getModuleIdentifier() const { return ModuleIdentifier; }
/// Read the bitcode module and prepare for lazy deserialization of function
/// bodies. If ShouldLazyLoadMetadata is true, lazily load metadata as well.
/// If IsImporting is true, this module is being parsed for ThinLTO
/// importing into another module.
Expected<std::unique_ptr<Module>>
getLazyModule(LLVMContext &Context, bool ShouldLazyLoadMetadata,
bool IsImporting, ParserCallbacks Callbacks = {});
/// Read the entire bitcode module and return it.
Expected<std::unique_ptr<Module>>
parseModule(LLVMContext &Context, ParserCallbacks Callbacks = {});
/// Returns information about the module to be used for LTO: whether to
/// compile with ThinLTO, and whether it has a summary.
Expected<BitcodeLTOInfo> getLTOInfo();
/// Parse the specified bitcode buffer, returning the module summary index.
Expected<std::unique_ptr<ModuleSummaryIndex>> getSummary();
/// Parse the specified bitcode buffer and merge its module summary index
/// into CombinedIndex.
Error
readSummary(ModuleSummaryIndex &CombinedIndex, StringRef ModulePath,
uint64_t ModuleId,
std::function<bool(GlobalValue::GUID)> IsPrevailing = nullptr);
};
struct BitcodeFileContents {
std::vector<BitcodeModule> Mods;
StringRef Symtab, StrtabForSymtab;
};
/// Returns the contents of a bitcode file. This includes the raw contents of
/// the symbol table embedded in the bitcode file. Clients which require a
/// symbol table should prefer to use irsymtab::read instead of this function
/// because it creates a reader for the irsymtab and handles upgrading bitcode
/// files without a symbol table or with an old symbol table.
Expected<BitcodeFileContents> getBitcodeFileContents(MemoryBufferRef Buffer);
/// Returns a list of modules in the specified bitcode buffer.
Expected<std::vector<BitcodeModule>>
getBitcodeModuleList(MemoryBufferRef Buffer);
/// Read the header of the specified bitcode buffer and prepare for lazy
/// deserialization of function bodies. If ShouldLazyLoadMetadata is true,
/// lazily load metadata as well. If IsImporting is true, this module is
/// being parsed for ThinLTO importing into another module.
Expected<std::unique_ptr<Module>>
getLazyBitcodeModule(MemoryBufferRef Buffer, LLVMContext &Context,
bool ShouldLazyLoadMetadata = false,
bool IsImporting = false,
ParserCallbacks Callbacks = {});
/// Like getLazyBitcodeModule, except that the module takes ownership of
/// the memory buffer if successful. If successful, this moves Buffer. On
/// error, this *does not* move Buffer. If IsImporting is true, this module is
/// being parsed for ThinLTO importing into another module.
Expected<std::unique_ptr<Module>> getOwningLazyBitcodeModule(
std::unique_ptr<MemoryBuffer> &&Buffer, LLVMContext &Context,
bool ShouldLazyLoadMetadata = false, bool IsImporting = false,
ParserCallbacks Callbacks = {});
/// Read the header of the specified bitcode buffer and extract just the
/// triple information. If successful, this returns a string. On error, this
/// returns "".
Expected<std::string> getBitcodeTargetTriple(MemoryBufferRef Buffer);
/// Return true if \p Buffer contains a bitcode file with ObjC code (category
/// or class) in it.
Expected<bool> isBitcodeContainingObjCCategory(MemoryBufferRef Buffer);
/// Read the header of the specified bitcode buffer and extract just the
/// producer string information. If successful, this returns a string. On
/// error, this returns "".
Expected<std::string> getBitcodeProducerString(MemoryBufferRef Buffer);
/// Read the specified bitcode file, returning the module.
Expected<std::unique_ptr<Module>>
parseBitcodeFile(MemoryBufferRef Buffer, LLVMContext &Context,
ParserCallbacks Callbacks = {});
/// Returns LTO information for the specified bitcode file.
Expected<BitcodeLTOInfo> getBitcodeLTOInfo(MemoryBufferRef Buffer);
/// Parse the specified bitcode buffer, returning the module summary index.
Expected<std::unique_ptr<ModuleSummaryIndex>>
getModuleSummaryIndex(MemoryBufferRef Buffer);
/// Parse the specified bitcode buffer and merge the index into CombinedIndex.
Error readModuleSummaryIndex(MemoryBufferRef Buffer,
ModuleSummaryIndex &CombinedIndex,
uint64_t ModuleId);
/// Parse the module summary index out of an IR file and return the module
/// summary index object if found, or an empty summary if not. If Path refers
/// to an empty file and IgnoreEmptyThinLTOIndexFile is true, then
/// this function will return nullptr.
Expected<std::unique_ptr<ModuleSummaryIndex>>
getModuleSummaryIndexForFile(StringRef Path,
bool IgnoreEmptyThinLTOIndexFile = false);
/// isBitcodeWrapper - Return true if the given bytes are the magic bytes
/// for an LLVM IR bitcode wrapper.
inline bool isBitcodeWrapper(const unsigned char *BufPtr,
const unsigned char *BufEnd) {
// See if you can find the hidden message in the magic bytes :-).
// (Hint: it's a little-endian encoding.)
return BufPtr != BufEnd &&
BufPtr[0] == 0xDE &&
BufPtr[1] == 0xC0 &&
BufPtr[2] == 0x17 &&
BufPtr[3] == 0x0B;
}
/// isRawBitcode - Return true if the given bytes are the magic bytes for
/// raw LLVM IR bitcode (without a wrapper).
inline bool isRawBitcode(const unsigned char *BufPtr,
const unsigned char *BufEnd) {
// These bytes sort of have a hidden message, but it's not in
// little-endian this time, and it's a little redundant.
return BufPtr != BufEnd &&
BufPtr[0] == 'B' &&
BufPtr[1] == 'C' &&
BufPtr[2] == 0xc0 &&
BufPtr[3] == 0xde;
}
/// isBitcode - Return true if the given bytes are the magic bytes for
/// LLVM IR bitcode, either with or without a wrapper.
inline bool isBitcode(const unsigned char *BufPtr,
const unsigned char *BufEnd) {
return isBitcodeWrapper(BufPtr, BufEnd) ||
isRawBitcode(BufPtr, BufEnd);
}
/// SkipBitcodeWrapperHeader - Some systems wrap bc files with a special
/// header for padding or other reasons. The format of this header is:
///
/// struct bc_header {
/// uint32_t Magic; // 0x0B17C0DE
/// uint32_t Version; // Version, currently always 0.
/// uint32_t BitcodeOffset; // Offset to traditional bitcode file.
/// uint32_t BitcodeSize; // Size of traditional bitcode file.
/// ... potentially other gunk ...
/// };
///
/// This function is called when we find a file with a matching magic number.
/// In this case, skip down to the subsection of the file that is actually a
/// BC file.
/// If 'VerifyBufferSize' is true, check that the buffer is large enough to
/// contain the whole bitcode file.
inline bool SkipBitcodeWrapperHeader(const unsigned char *&BufPtr,
const unsigned char *&BufEnd,
bool VerifyBufferSize) {
// Must contain the offset and size field!
if (unsigned(BufEnd - BufPtr) < BWH_SizeField + 4)
return true;
unsigned Offset = support::endian::read32le(&BufPtr[BWH_OffsetField]);
unsigned Size = support::endian::read32le(&BufPtr[BWH_SizeField]);
uint64_t BitcodeOffsetEnd = (uint64_t)Offset + (uint64_t)Size;
// Verify that Offset+Size fits in the file.
if (VerifyBufferSize && BitcodeOffsetEnd > uint64_t(BufEnd-BufPtr))
return true;
BufPtr += Offset;
BufEnd = BufPtr+Size;
return false;
}
APInt readWideAPInt(ArrayRef<uint64_t> Vals, unsigned TypeBits);
const std::error_category &BitcodeErrorCategory();
enum class BitcodeError { CorruptedBitcode = 1 };
inline std::error_code make_error_code(BitcodeError E) {
return std::error_code(static_cast<int>(E), BitcodeErrorCategory());
}
} // end namespace llvm
namespace std {
template <> struct is_error_code_enum<llvm::BitcodeError> : std::true_type {};
} // end namespace std
#endif // LLVM_BITCODE_BITCODEREADER_H