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//===- Wasm.h - Wasm object file format -------------------------*- 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 file defines manifest constants for the wasm object file format.
// See: https://github.com/WebAssembly/design/blob/main/BinaryEncoding.md
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_BINARYFORMAT_WASM_H
#define LLVM_BINARYFORMAT_WASM_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include <optional>
namespace llvm {
namespace wasm {
// Object file magic string.
const char WasmMagic[] = {'\0', 'a', 's', 'm'};
// Wasm binary format version
const uint32_t WasmVersion = 0x1;
// Wasm linking metadata version
const uint32_t WasmMetadataVersion = 0x2;
// Wasm uses a 64k page size
const uint32_t WasmPageSize = 65536;
enum : unsigned {
WASM_SEC_CUSTOM = 0, // Custom / User-defined section
WASM_SEC_TYPE = 1, // Function signature declarations
WASM_SEC_IMPORT = 2, // Import declarations
WASM_SEC_FUNCTION = 3, // Function declarations
WASM_SEC_TABLE = 4, // Indirect function table and other tables
WASM_SEC_MEMORY = 5, // Memory attributes
WASM_SEC_GLOBAL = 6, // Global declarations
WASM_SEC_EXPORT = 7, // Exports
WASM_SEC_START = 8, // Start function declaration
WASM_SEC_ELEM = 9, // Elements section
WASM_SEC_CODE = 10, // Function bodies (code)
WASM_SEC_DATA = 11, // Data segments
WASM_SEC_DATACOUNT = 12, // Data segment count
WASM_SEC_TAG = 13, // Tag declarations
WASM_SEC_LAST_KNOWN = WASM_SEC_TAG,
};
// Type immediate encodings used in various contexts.
enum : unsigned {
WASM_TYPE_I32 = 0x7F,
WASM_TYPE_I64 = 0x7E,
WASM_TYPE_F32 = 0x7D,
WASM_TYPE_F64 = 0x7C,
WASM_TYPE_V128 = 0x7B,
WASM_TYPE_NULLFUNCREF = 0x73,
WASM_TYPE_NULLEXTERNREF = 0x72,
WASM_TYPE_NULLEXNREF = 0x74,
WASM_TYPE_NULLREF = 0x71,
WASM_TYPE_FUNCREF = 0x70,
WASM_TYPE_EXTERNREF = 0x6F,
WASM_TYPE_EXNREF = 0x69,
WASM_TYPE_ANYREF = 0x6E,
WASM_TYPE_EQREF = 0x6D,
WASM_TYPE_I31REF = 0x6C,
WASM_TYPE_STRUCTREF = 0x6B,
WASM_TYPE_ARRAYREF = 0x6A,
WASM_TYPE_NONNULLABLE = 0x64,
WASM_TYPE_NULLABLE = 0x63,
WASM_TYPE_FUNC = 0x60,
WASM_TYPE_ARRAY = 0x5E,
WASM_TYPE_STRUCT = 0x5F,
WASM_TYPE_SUB = 0x50,
WASM_TYPE_SUB_FINAL = 0x4F,
WASM_TYPE_REC = 0x4E,
WASM_TYPE_NORESULT = 0x40, // for blocks with no result values
};
// Kinds of externals (for imports and exports).
enum : unsigned {
WASM_EXTERNAL_FUNCTION = 0x0,
WASM_EXTERNAL_TABLE = 0x1,
WASM_EXTERNAL_MEMORY = 0x2,
WASM_EXTERNAL_GLOBAL = 0x3,
WASM_EXTERNAL_TAG = 0x4,
};
// Opcodes used in initializer expressions.
enum : unsigned {
WASM_OPCODE_END = 0x0b,
WASM_OPCODE_CALL = 0x10,
WASM_OPCODE_LOCAL_GET = 0x20,
WASM_OPCODE_LOCAL_SET = 0x21,
WASM_OPCODE_LOCAL_TEE = 0x22,
WASM_OPCODE_GLOBAL_GET = 0x23,
WASM_OPCODE_GLOBAL_SET = 0x24,
WASM_OPCODE_I32_STORE = 0x36,
WASM_OPCODE_I64_STORE = 0x37,
WASM_OPCODE_I32_CONST = 0x41,
WASM_OPCODE_I64_CONST = 0x42,
WASM_OPCODE_F32_CONST = 0x43,
WASM_OPCODE_F64_CONST = 0x44,
WASM_OPCODE_I32_ADD = 0x6a,
WASM_OPCODE_I32_SUB = 0x6b,
WASM_OPCODE_I32_MUL = 0x6c,
WASM_OPCODE_I64_ADD = 0x7c,
WASM_OPCODE_I64_SUB = 0x7d,
WASM_OPCODE_I64_MUL = 0x7e,
WASM_OPCODE_REF_NULL = 0xd0,
WASM_OPCODE_REF_FUNC = 0xd2,
WASM_OPCODE_GC_PREFIX = 0xfb,
};
// Opcodes in the GC-prefixed space (0xfb)
enum : unsigned {
WASM_OPCODE_STRUCT_NEW = 0x00,
WASM_OPCODE_STRUCT_NEW_DEFAULT = 0x01,
WASM_OPCODE_ARRAY_NEW = 0x06,
WASM_OPCODE_ARRAY_NEW_DEFAULT = 0x07,
WASM_OPCODE_ARRAY_NEW_FIXED = 0x08,
WASM_OPCODE_REF_I31 = 0x1c,
// any.convert_extern and extern.convert_any don't seem to be supported by
// Binaryen.
};
// Opcodes used in synthetic functions.
enum : unsigned {
WASM_OPCODE_BLOCK = 0x02,
WASM_OPCODE_BR = 0x0c,
WASM_OPCODE_BR_TABLE = 0x0e,
WASM_OPCODE_RETURN = 0x0f,
WASM_OPCODE_DROP = 0x1a,
WASM_OPCODE_MISC_PREFIX = 0xfc,
WASM_OPCODE_MEMORY_INIT = 0x08,
WASM_OPCODE_MEMORY_FILL = 0x0b,
WASM_OPCODE_DATA_DROP = 0x09,
WASM_OPCODE_ATOMICS_PREFIX = 0xfe,
WASM_OPCODE_ATOMIC_NOTIFY = 0x00,
WASM_OPCODE_I32_ATOMIC_WAIT = 0x01,
WASM_OPCODE_I32_ATOMIC_STORE = 0x17,
WASM_OPCODE_I32_RMW_CMPXCHG = 0x48,
};
enum : unsigned {
WASM_LIMITS_FLAG_NONE = 0x0,
WASM_LIMITS_FLAG_HAS_MAX = 0x1,
WASM_LIMITS_FLAG_IS_SHARED = 0x2,
WASM_LIMITS_FLAG_IS_64 = 0x4,
};
enum : unsigned {
WASM_DATA_SEGMENT_IS_PASSIVE = 0x01,
WASM_DATA_SEGMENT_HAS_MEMINDEX = 0x02,
};
enum : unsigned {
WASM_ELEM_SEGMENT_IS_PASSIVE = 0x01,
WASM_ELEM_SEGMENT_IS_DECLARATIVE = 0x02, // if passive == 1
WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER = 0x02, // if passive == 0
WASM_ELEM_SEGMENT_HAS_INIT_EXPRS = 0x04,
};
const unsigned WASM_ELEM_SEGMENT_MASK_HAS_ELEM_KIND = 0x3;
// Feature policy prefixes used in the custom "target_features" section
enum : uint8_t {
WASM_FEATURE_PREFIX_USED = '+',
WASM_FEATURE_PREFIX_REQUIRED = '=',
WASM_FEATURE_PREFIX_DISALLOWED = '-',
};
// Kind codes used in the custom "name" section
enum : unsigned {
WASM_NAMES_MODULE = 0,
WASM_NAMES_FUNCTION = 1,
WASM_NAMES_LOCAL = 2,
WASM_NAMES_GLOBAL = 7,
WASM_NAMES_DATA_SEGMENT = 9,
};
// Kind codes used in the custom "linking" section
enum : unsigned {
WASM_SEGMENT_INFO = 0x5,
WASM_INIT_FUNCS = 0x6,
WASM_COMDAT_INFO = 0x7,
WASM_SYMBOL_TABLE = 0x8,
};
// Kind codes used in the custom "dylink" section
enum : unsigned {
WASM_DYLINK_MEM_INFO = 0x1,
WASM_DYLINK_NEEDED = 0x2,
WASM_DYLINK_EXPORT_INFO = 0x3,
WASM_DYLINK_IMPORT_INFO = 0x4,
};
// Kind codes used in the custom "linking" section in the WASM_COMDAT_INFO
enum : unsigned {
WASM_COMDAT_DATA = 0x0,
WASM_COMDAT_FUNCTION = 0x1,
// GLOBAL, TAG, and TABLE are in here but LLVM doesn't use them yet.
WASM_COMDAT_SECTION = 0x5,
};
// Kind codes used in the custom "linking" section in the WASM_SYMBOL_TABLE
enum WasmSymbolType : unsigned {
WASM_SYMBOL_TYPE_FUNCTION = 0x0,
WASM_SYMBOL_TYPE_DATA = 0x1,
WASM_SYMBOL_TYPE_GLOBAL = 0x2,
WASM_SYMBOL_TYPE_SECTION = 0x3,
WASM_SYMBOL_TYPE_TAG = 0x4,
WASM_SYMBOL_TYPE_TABLE = 0x5,
};
enum WasmSegmentFlag : unsigned {
WASM_SEG_FLAG_STRINGS = 0x1,
WASM_SEG_FLAG_TLS = 0x2,
WASM_SEG_FLAG_RETAIN = 0x4,
};
// Kinds of tag attributes.
enum WasmTagAttribute : uint8_t {
WASM_TAG_ATTRIBUTE_EXCEPTION = 0x0,
};
const unsigned WASM_SYMBOL_BINDING_MASK = 0x3;
const unsigned WASM_SYMBOL_VISIBILITY_MASK = 0xc;
const unsigned WASM_SYMBOL_BINDING_GLOBAL = 0x0;
const unsigned WASM_SYMBOL_BINDING_WEAK = 0x1;
const unsigned WASM_SYMBOL_BINDING_LOCAL = 0x2;
const unsigned WASM_SYMBOL_VISIBILITY_DEFAULT = 0x0;
const unsigned WASM_SYMBOL_VISIBILITY_HIDDEN = 0x4;
const unsigned WASM_SYMBOL_UNDEFINED = 0x10;
const unsigned WASM_SYMBOL_EXPORTED = 0x20;
const unsigned WASM_SYMBOL_EXPLICIT_NAME = 0x40;
const unsigned WASM_SYMBOL_NO_STRIP = 0x80;
const unsigned WASM_SYMBOL_TLS = 0x100;
const unsigned WASM_SYMBOL_ABSOLUTE = 0x200;
#define WASM_RELOC(name, value) name = value,
enum : unsigned {
#include "WasmRelocs.def"
};
#undef WASM_RELOC
struct WasmObjectHeader {
StringRef Magic;
uint32_t Version;
};
// Subset of types that a value can have
enum class ValType {
I32 = WASM_TYPE_I32,
I64 = WASM_TYPE_I64,
F32 = WASM_TYPE_F32,
F64 = WASM_TYPE_F64,
V128 = WASM_TYPE_V128,
FUNCREF = WASM_TYPE_FUNCREF,
EXTERNREF = WASM_TYPE_EXTERNREF,
EXNREF = WASM_TYPE_EXNREF,
// Unmodeled value types include ref types with heap types other than
// func, extern or exn, and type-specialized funcrefs
OTHERREF = 0xff,
};
struct WasmDylinkImportInfo {
StringRef Module;
StringRef Field;
uint32_t Flags;
};
struct WasmDylinkExportInfo {
StringRef Name;
uint32_t Flags;
};
struct WasmDylinkInfo {
uint32_t MemorySize; // Memory size in bytes
uint32_t MemoryAlignment; // P2 alignment of memory
uint32_t TableSize; // Table size in elements
uint32_t TableAlignment; // P2 alignment of table
std::vector<StringRef> Needed; // Shared library dependencies
std::vector<WasmDylinkImportInfo> ImportInfo;
std::vector<WasmDylinkExportInfo> ExportInfo;
};
struct WasmProducerInfo {
std::vector<std::pair<std::string, std::string>> Languages;
std::vector<std::pair<std::string, std::string>> Tools;
std::vector<std::pair<std::string, std::string>> SDKs;
};
struct WasmFeatureEntry {
uint8_t Prefix;
std::string Name;
};
struct WasmExport {
StringRef Name;
uint8_t Kind;
uint32_t Index;
};
struct WasmLimits {
uint8_t Flags;
uint64_t Minimum;
uint64_t Maximum;
};
struct WasmTableType {
ValType ElemType;
WasmLimits Limits;
};
struct WasmTable {
uint32_t Index;
WasmTableType Type;
StringRef SymbolName; // from the "linking" section
};
struct WasmInitExprMVP {
uint8_t Opcode;
union {
int32_t Int32;
int64_t Int64;
uint32_t Float32;
uint64_t Float64;
uint32_t Global;
} Value;
};
// Extended-const init exprs and exprs with GC types are not explicitly
// modeled, but the raw body of the expr is attached.
struct WasmInitExpr {
uint8_t Extended; // Set to non-zero if extended const is used (i.e. more than
// one instruction)
WasmInitExprMVP Inst;
ArrayRef<uint8_t> Body;
};
struct WasmGlobalType {
uint8_t Type; // TODO: make this a ValType?
bool Mutable;
};
struct WasmGlobal {
uint32_t Index;
WasmGlobalType Type;
WasmInitExpr InitExpr;
StringRef SymbolName; // from the "linking" section
uint32_t Offset; // Offset of the definition in the binary's Global section
uint32_t Size; // Size of the definition in the binary's Global section
};
struct WasmTag {
uint32_t Index;
uint32_t SigIndex;
StringRef SymbolName; // from the "linking" section
};
struct WasmImport {
StringRef Module;
StringRef Field;
uint8_t Kind;
union {
uint32_t SigIndex;
WasmGlobalType Global;
WasmTableType Table;
WasmLimits Memory;
};
};
struct WasmLocalDecl {
uint8_t Type;
uint32_t Count;
};
struct WasmFunction {
uint32_t Index;
uint32_t SigIndex;
std::vector<WasmLocalDecl> Locals;
ArrayRef<uint8_t> Body;
uint32_t CodeSectionOffset;
uint32_t Size;
uint32_t CodeOffset; // start of Locals and Body
std::optional<StringRef> ExportName; // from the "export" section
StringRef SymbolName; // from the "linking" section
StringRef DebugName; // from the "name" section
uint32_t Comdat; // from the "comdat info" section
};
struct WasmDataSegment {
uint32_t InitFlags;
// Present if InitFlags & WASM_DATA_SEGMENT_HAS_MEMINDEX.
uint32_t MemoryIndex;
// Present if InitFlags & WASM_DATA_SEGMENT_IS_PASSIVE == 0.
WasmInitExpr Offset;
ArrayRef<uint8_t> Content;
StringRef Name; // from the "segment info" section
uint32_t Alignment;
uint32_t LinkingFlags;
uint32_t Comdat; // from the "comdat info" section
};
// Represents a Wasm element segment, with some limitations compared the spec:
// 1) Does not model passive or declarative segments (Segment will end up with
// an Offset field of i32.const 0)
// 2) Does not model init exprs (Segment will get an empty Functions list)
// 3) Does not model types other than basic funcref/externref/exnref (see
// ValType)
struct WasmElemSegment {
uint32_t Flags;
uint32_t TableNumber;
ValType ElemKind;
WasmInitExpr Offset;
std::vector<uint32_t> Functions;
};
// Represents the location of a Wasm data symbol within a WasmDataSegment, as
// the index of the segment, and the offset and size within the segment.
struct WasmDataReference {
uint32_t Segment;
uint64_t Offset;
uint64_t Size;
};
struct WasmRelocation {
uint8_t Type; // The type of the relocation.
uint32_t Index; // Index into either symbol or type index space.
uint64_t Offset; // Offset from the start of the section.
int64_t Addend; // A value to add to the symbol.
};
struct WasmInitFunc {
uint32_t Priority;
uint32_t Symbol;
};
struct WasmSymbolInfo {
StringRef Name;
uint8_t Kind;
uint32_t Flags;
// For undefined symbols the module of the import
std::optional<StringRef> ImportModule;
// For undefined symbols the name of the import
std::optional<StringRef> ImportName;
// For symbols to be exported from the final module
std::optional<StringRef> ExportName;
union {
// For function, table, or global symbols, the index in function, table, or
// global index space.
uint32_t ElementIndex;
// For a data symbols, the address of the data relative to segment.
WasmDataReference DataRef;
};
};
enum class NameType {
FUNCTION,
GLOBAL,
DATA_SEGMENT,
};
struct WasmDebugName {
NameType Type;
uint32_t Index;
StringRef Name;
};
// Info from the linking metadata section of a wasm object file.
struct WasmLinkingData {
uint32_t Version;
std::vector<WasmInitFunc> InitFunctions;
std::vector<StringRef> Comdats;
// The linking section also contains a symbol table. This info (represented
// in a WasmSymbolInfo struct) is stored inside the WasmSymbol object instead
// of in this structure; this allows vectors of WasmSymbols and
// WasmLinkingDatas to be reallocated.
};
struct WasmSignature {
SmallVector<ValType, 1> Returns;
SmallVector<ValType, 4> Params;
// LLVM can parse types other than functions encoded in the type section,
// but does not actually model them. Instead a placeholder signature is
// created in the Object's signature list.
enum { Function, Tag, Placeholder } Kind = Function;
// Support empty and tombstone instances, needed by DenseMap.
enum { Plain, Empty, Tombstone } State = Plain;
WasmSignature(SmallVector<ValType, 1> &&InReturns,
SmallVector<ValType, 4> &&InParams)
: Returns(InReturns), Params(InParams) {}
WasmSignature() = default;
};
// Useful comparison operators
inline bool operator==(const WasmSignature &LHS, const WasmSignature &RHS) {
return LHS.State == RHS.State && LHS.Returns == RHS.Returns &&
LHS.Params == RHS.Params;
}
inline bool operator!=(const WasmSignature &LHS, const WasmSignature &RHS) {
return !(LHS == RHS);
}
inline bool operator==(const WasmGlobalType &LHS, const WasmGlobalType &RHS) {
return LHS.Type == RHS.Type && LHS.Mutable == RHS.Mutable;
}
inline bool operator!=(const WasmGlobalType &LHS, const WasmGlobalType &RHS) {
return !(LHS == RHS);
}
inline bool operator==(const WasmLimits &LHS, const WasmLimits &RHS) {
return LHS.Flags == RHS.Flags && LHS.Minimum == RHS.Minimum &&
(LHS.Flags & WASM_LIMITS_FLAG_HAS_MAX ? LHS.Maximum == RHS.Maximum
: true);
}
inline bool operator==(const WasmTableType &LHS, const WasmTableType &RHS) {
return LHS.ElemType == RHS.ElemType && LHS.Limits == RHS.Limits;
}
llvm::StringRef toString(WasmSymbolType type);
llvm::StringRef relocTypetoString(uint32_t type);
llvm::StringRef sectionTypeToString(uint32_t type);
bool relocTypeHasAddend(uint32_t type);
} // end namespace wasm
} // end namespace llvm
#endif
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