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// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#if !V8_ENABLE_WEBASSEMBLY
#error This header should only be included if WebAssembly is enabled.
#endif // !V8_ENABLE_WEBASSEMBLY
#ifndef V8_WASM_WASM_CONSTANTS_H_
#define V8_WASM_WASM_CONSTANTS_H_
#include <cstddef>
#include <cstdint>
#include "src/common/globals.h"
namespace v8 {
namespace internal {
namespace wasm {
// Binary encoding of the module header.
constexpr uint32_t kWasmMagic = 0x6d736100;
constexpr uint32_t kWasmVersion = 0x01;
// Binary encoding of value and heap types.
enum ValueTypeCode : uint8_t {
// Current value types
kVoidCode = 0x40,
kI32Code = 0x7f, // -0x01
kI64Code = 0x7e, // -0x02
kF32Code = 0x7d, // -0x03
kF64Code = 0x7c, // -0x04
kS128Code = 0x7b, // -0x05
kI8Code = 0x78, // -0x08, packed type
kI16Code = 0x77, // -0x09, packed type
kNoFuncCode = 0x73, // -0x0d
kNoExternCode = 0x72, // -0x0e
kNoneCode = 0x71, // -0x0f
kFuncRefCode = 0x70, // -0x10
kExternRefCode = 0x6f, // -0x11
kAnyRefCode = 0x6e, // -0x12
kEqRefCode = 0x6d, // -0x13
kI31RefCode = 0x6c, // -0x14
kStructRefCode = 0x6b, // -0x15
kArrayRefCode = 0x6a, // -0x16
kRefCode = 0x64, // -0x1c
kRefNullCode = 0x63, // -0x1d
// Non-finalized proposals below.
kStringRefCode = 0x67, // -0x19
kStringViewWtf8Code = 0x66, // -0x1a
kStringViewWtf16Code = 0x62, // -0x1e
kStringViewIterCode = 0x61, // -0x1f
};
// Binary encoding of type definitions.
constexpr uint8_t kWasmFunctionTypeCode = 0x60;
constexpr uint8_t kWasmStructTypeCode = 0x5f;
constexpr uint8_t kWasmArrayTypeCode = 0x5e;
constexpr uint8_t kWasmSubtypeCode = 0x50;
constexpr uint8_t kWasmSubtypeFinalCode = 0x4f;
constexpr uint8_t kWasmRecursiveTypeGroupCode = 0x4e;
// Binary encoding of import/export kinds.
enum ImportExportKindCode : uint8_t {
kExternalFunction = 0,
kExternalTable = 1,
kExternalMemory = 2,
kExternalGlobal = 3,
kExternalTag = 4
};
enum LimitsFlags : uint8_t {
kNoMaximum = 0x00, // Also valid for table limits.
kWithMaximum = 0x01, // Also valid for table limits.
kSharedNoMaximum = 0x02, // Only valid for memory limits.
kSharedWithMaximum = 0x03, // Only valid for memory limits.
kMemory64NoMaximum = 0x04, // Only valid for memory limits.
kMemory64WithMaximum = 0x05, // Only valid for memory limits.
kMemory64SharedNoMaximum = 0x06, // Only valid for memory limits.
kMemory64SharedWithMaximum = 0x07 // Only valid for memory limits.
};
// Flags for data and element segments.
enum SegmentFlags : uint8_t {
kActiveNoIndex = 0, // Active segment with a memory/table index of zero.
kPassive = 1, // Passive segment.
kActiveWithIndex = 2, // Active segment with a given memory/table index.
};
// Binary encoding of sections identifiers.
enum SectionCode : int8_t {
kUnknownSectionCode = 0, // code for unknown sections
kTypeSectionCode = 1, // Function signature declarations
kImportSectionCode = 2, // Import declarations
kFunctionSectionCode = 3, // Function declarations
kTableSectionCode = 4, // Indirect function table and others
kMemorySectionCode = 5, // Memory attributes
kGlobalSectionCode = 6, // Global declarations
kExportSectionCode = 7, // Exports
kStartSectionCode = 8, // Start function declaration
kElementSectionCode = 9, // Elements section
kCodeSectionCode = 10, // Function code
kDataSectionCode = 11, // Data segments
kDataCountSectionCode = 12, // Number of data segments
kTagSectionCode = 13, // Tag section
kStringRefSectionCode = 14, // Stringref literal section
// The following sections are custom sections, and are identified using a
// string rather than an integer. Their enumeration values are not guaranteed
// to be consistent.
kNameSectionCode, // Name section (encoded as a string)
kSourceMappingURLSectionCode, // Source Map URL section
kDebugInfoSectionCode, // DWARF section .debug_info
kExternalDebugInfoSectionCode, // Section encoding the external symbol path
kInstTraceSectionCode, // Instruction trace section
kCompilationHintsSectionCode, // Compilation hints section
kBranchHintsSectionCode, // Branch hints section
// Helper values
kFirstSectionInModule = kTypeSectionCode,
kLastKnownModuleSection = kStringRefSectionCode,
kFirstUnorderedSection = kDataCountSectionCode,
};
// Binary encoding of compilation hints.
constexpr uint8_t kDefaultCompilationHint = 0x0;
constexpr uint8_t kNoCompilationHint = kMaxUInt8;
// Binary encoding of name section kinds.
enum NameSectionKindCode : uint8_t {
kModuleCode = 0,
kFunctionCode = 1,
kLocalCode = 2,
// https://github.com/WebAssembly/extended-name-section/
kLabelCode = 3,
kTypeCode = 4,
kTableCode = 5,
kMemoryCode = 6,
kGlobalCode = 7,
kElementSegmentCode = 8,
kDataSegmentCode = 9,
// https://github.com/WebAssembly/gc/issues/193
kFieldCode = 10,
// https://github.com/WebAssembly/exception-handling/pull/213
kTagCode = 11,
};
constexpr size_t kWasmPageSize = 0x10000;
constexpr uint32_t kWasmPageSizeLog2 = 16;
static_assert(kWasmPageSize == size_t{1} << kWasmPageSizeLog2, "consistency");
// TODO(wasm): Wrap WasmCodePosition in a struct.
using WasmCodePosition = int;
constexpr WasmCodePosition kNoCodePosition = -1;
constexpr uint32_t kExceptionAttribute = 0;
constexpr int kAnonymousFuncIndex = -1;
// The number of calls to an exported Wasm function that will be handled
// by the generic wrapper. Once the budget is exhausted, a specific wrapper
// is to be compiled for the function's signature.
// The abstract goal of the tiering strategy for the js-to-wasm wrappers is to
// use the generic wrapper as much as possible (less space, no need to compile),
// but fall back to compiling a specific wrapper for any function (signature)
// that is used often enough for the generic wrapper's small execution penalty
// to start adding up.
// So, when choosing a value for the initial budget, we are interested in a
// value that skips on tiering up functions that are called only a few times and
// the tier-up only wastes resources, but triggers compilation of specific
// wrappers early on for those functions that have the potential to be called
// often enough.
constexpr uint32_t kGenericWrapperBudget = 1000;
// The minimum length of supertype arrays for wasm-gc types. Having a size > 0
// gives up some module size for faster access to the supertypes.
constexpr uint32_t kMinimumSupertypeArraySize = 3;
// Maximum number of call targets tracked per call.
constexpr int kMaxPolymorphism = 4;
// A struct field beyond this limit needs an explicit null check (trapping null
// access not guaranteed to behave properly).
constexpr int kMaxStructFieldIndexForImplicitNullCheck = 4000;
#if V8_TARGET_ARCH_X64
constexpr int32_t kOSRTargetOffset = 4 * kSystemPointerSize;
#endif
} // namespace wasm
} // namespace internal
} // namespace v8
#endif // V8_WASM_WASM_CONSTANTS_H_
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