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Diffstat (limited to 'lld/lib/ReaderWriter/Native/NativeFileFormat.h')
| -rw-r--r-- | lld/lib/ReaderWriter/Native/NativeFileFormat.h | 258 |
1 files changed, 0 insertions, 258 deletions
diff --git a/lld/lib/ReaderWriter/Native/NativeFileFormat.h b/lld/lib/ReaderWriter/Native/NativeFileFormat.h deleted file mode 100644 index dec893baa9a..00000000000 --- a/lld/lib/ReaderWriter/Native/NativeFileFormat.h +++ /dev/null @@ -1,258 +0,0 @@ -//===- lib/ReaderWriter/Native/NativeFileFormat.h -------------------------===// -// -// The LLVM Linker -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// - -#ifndef LLD_READER_WRITER_NATIVE_NATIVE_FILE_FORMAT_H -#define LLD_READER_WRITER_NATIVE_NATIVE_FILE_FORMAT_H - -#include "llvm/Support/DataTypes.h" -#include <cstdint> - -namespace lld { - -// -// Overview: -// -// The number one design goal of this file format is enable the linker to -// read object files into in-memory Atom objects extremely quickly. -// The second design goal is to enable future modifications to the -// Atom attribute model. -// -// The llvm native object file format is not like traditional object file -// formats (e.g. ELF, COFF, mach-o). There is no symbol table and no -// sections. Instead the file is essentially an array of archived Atoms. -// It is *not* serialized Atoms which would require deserialization into -// in memory objects. Instead it is an array of read-only info about each -// Atom. The NativeReader bulk creates in-memory Atoms which just have -// an ivar which points to the read-only info for that Atom. No additional -// processing is done to construct the in-memory Atoms. All Atom attribute -// getter methods are virtual calls which dig up the info they need from the -// ivar data. -// -// To support the gradual evolution of Atom attributes, the Atom read-only -// data is versioned. The NativeReader chooses which in-memory Atom class -// to use based on the version. What this means is that if new attributes -// are added (or changed) in the Atom model, a new native atom class and -// read-only atom info struct needs to be defined. Then, all the existing -// native reader atom classes need to be modified to do their best effort -// to map their old style read-only data to the new Atom model. At some point -// some classes to support old versions may be dropped. -// -// -// Details: -// -// The native object file format consists of a header that specifies the -// endianness of the file and the architecture along with a list of "chunks" -// in the file. A Chunk is simply a tagged range of the file. There is -// one chunk for the array of atom infos. There is another chunk for the -// string pool, and another for the content pool. -// -// It turns out there most atoms have very similar sets of attributes, only -// the name and content attribute vary. To exploit this fact to reduce the file -// size, the atom read-only info contains just the name and content info plus -// a reference to which attribute set it uses. The attribute sets are stored -// in another chunk. -// - - -// -// An entry in the NativeFileHeader that describes one chunk of the file. -// -struct NativeChunk { - uint32_t signature; - uint32_t fileOffset; - uint32_t fileSize; - uint32_t elementCount; -}; - - -// -// The header in a native object file -// -struct NativeFileHeader { - uint8_t magic[16]; - uint32_t endian; - uint32_t architecture; - uint32_t fileSize; - uint32_t chunkCount; - // NativeChunk chunks[] -}; - -// -// Possible values for NativeChunk.signature field -// -enum NativeChunkSignatures { - NCS_DefinedAtomsV1 = 1, - NCS_AttributesArrayV1 = 2, - NCS_AbsoluteAttributesV1 = 12, - NCS_UndefinedAtomsV1 = 3, - NCS_SharedLibraryAtomsV1 = 4, - NCS_AbsoluteAtomsV1 = 5, - NCS_Strings = 6, - NCS_ReferencesArrayV1 = 7, - NCS_ReferencesArrayV2 = 8, - NCS_TargetsTable = 9, - NCS_AddendsTable = 10, - NCS_Content = 11, -}; - -// -// The 16-bytes at the start of a native object file -// -#define NATIVE_FILE_HEADER_MAGIC "llvm nat obj v1 " - -// -// Possible values for the NativeFileHeader.endian field -// -enum { - NFH_BigEndian = 0x42696745, - NFH_LittleEndian = 0x4574696c -}; - - -// -// Possible values for the NativeFileHeader.architecture field -// -enum { - NFA_x86 = 1, - NFA_x86_64 = 2, - NFA_armv6 = 3, - NFA_armv7 = 4, -}; - - -// -// The NCS_DefinedAtomsV1 chunk contains an array of these structs -// -struct NativeDefinedAtomIvarsV1 { - uint32_t nameOffset; - uint32_t attributesOffset; - uint32_t referencesStartIndex; - uint32_t referencesCount; - uint32_t contentOffset; - uint32_t contentSize; - uint64_t sectionSize; -}; - - -// -// The NCS_AttributesArrayV1 chunk contains an array of these structs -// -struct NativeAtomAttributesV1 { - uint32_t sectionNameOffset; - uint16_t align; - uint16_t alignModulus; - uint8_t scope; - uint8_t interposable; - uint8_t merge; - uint8_t contentType; - uint8_t sectionChoice; - uint8_t deadStrip; - uint8_t dynamicExport; - uint8_t permissions; - uint8_t alias; - uint8_t codeModel; -}; - - - -// -// The NCS_UndefinedAtomsV1 chunk contains an array of these structs -// -struct NativeUndefinedAtomIvarsV1 { - uint32_t nameOffset; - uint32_t flags; - uint32_t fallbackNameOffset; -}; - - -// -// The NCS_SharedLibraryAtomsV1 chunk contains an array of these structs -// -struct NativeSharedLibraryAtomIvarsV1 { - uint64_t size; - uint32_t nameOffset; - uint32_t loadNameOffset; - uint32_t type; - uint32_t flags; -}; - - - -// -// The NCS_AbsoluteAtomsV1 chunk contains an array of these structs -// -struct NativeAbsoluteAtomIvarsV1 { - uint32_t nameOffset; - uint32_t attributesOffset; - uint32_t reserved; - uint64_t value; -}; - - - -// -// The NCS_ReferencesArrayV1 chunk contains an array of these structs -// -struct NativeReferenceIvarsV1 { - enum { - noTarget = UINT16_MAX - }; - uint32_t offsetInAtom; - uint16_t kindValue; - uint8_t kindNamespace; - uint8_t kindArch; - uint16_t targetIndex; - uint16_t addendIndex; -}; - - -// -// The NCS_ReferencesArrayV2 chunk contains an array of these structs -// -struct NativeReferenceIvarsV2 { - enum : unsigned { - noTarget = UINT32_MAX - }; - uint64_t offsetInAtom; - int64_t addend; - uint16_t kindValue; - uint8_t kindNamespace; - uint8_t kindArch; - uint32_t targetIndex; - uint32_t tag; -}; - - -// -// The NCS_TargetsTable chunk contains an array of uint32_t entries. -// The C++ class Reference has a target() method that returns a -// pointer to another Atom. We can't have pointers in object files, -// so instead NativeReferenceIvarsV1 contains an index to the target. -// The index is into this NCS_TargetsTable of uint32_t entries. -// The values in this table are the index of the (target) atom in this file. -// For DefinedAtoms the value is from 0 to NCS_DefinedAtomsV1.elementCount. -// For UndefinedAtoms the value is from NCS_DefinedAtomsV1.elementCount to -// NCS_DefinedAtomsV1.elementCount+NCS_UndefinedAtomsV1.elementCount. -// - - -// -// The NCS_AddendsTable chunk contains an array of int64_t entries. -// If we allocated space for addends directly in NativeReferenceIvarsV1 -// it would double the size of that struct. But since addends are rare, -// we instead just keep a pool of addends and have NativeReferenceIvarsV1 -// (if it needs an addend) just store the index (into the pool) of the -// addend it needs. -// - - - -} // namespace lld - -#endif // LLD_READER_WRITER_NATIVE_NATIVE_FILE_FORMAT_H |
