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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
*
* Copyright 2016 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef wasm_js_h
#define wasm_js_h
#include "mozilla/HashTable.h" // DefaultHasher
#include "mozilla/Maybe.h" // mozilla::Maybe
#include <stdint.h> // int32_t, int64_t, uint32_t
#include "gc/Barrier.h" // HeapPtr
#include "gc/ZoneAllocator.h" // ZoneAllocPolicy
#include "js/AllocPolicy.h" // SystemAllocPolicy
#include "js/Class.h" // JSClassOps, ClassSpec
#include "js/GCHashTable.h" // GCHashMap, GCHashSet
#include "js/GCVector.h" // GCVector
#include "js/PropertySpec.h" // JSPropertySpec, JSFunctionSpec
#include "js/RootingAPI.h" // MovableCellHasher
#include "js/SweepingAPI.h" // JS::WeakCache
#include "js/TypeDecls.h" // HandleValue, HandleObject, MutableHandleObject, MutableHandleFunction
#include "js/Vector.h" // JS::Vector
#include "js/WasmFeatures.h"
#include "vm/JSFunction.h" // JSFunction
#include "vm/NativeObject.h" // NativeObject
#include "wasm/WasmCodegenTypes.h"
#include "wasm/WasmConstants.h"
#include "wasm/WasmException.h"
#include "wasm/WasmExprType.h"
#include "wasm/WasmInstanceData.h"
#include "wasm/WasmMemory.h"
#include "wasm/WasmModuleTypes.h"
#include "wasm/WasmTypeDecls.h" // MutableHandleWasmInstanceObject
#include "wasm/WasmValType.h"
#include "wasm/WasmValue.h"
class JSObject;
class JSTracer;
struct JSContext;
namespace JS {
class CallArgs;
class Value;
} // namespace JS
namespace js {
class ArrayBufferObject;
class ArrayBufferObjectMaybeShared;
class JSStringBuilder;
class SharedArrayRawBuffer;
class TypedArrayObject;
class WasmFunctionScope;
class WasmInstanceScope;
namespace wasm {
struct ImportValues;
// Return whether WebAssembly can in principle be compiled on this platform (ie
// combination of hardware and OS), assuming at least one of the compilers that
// supports the platform is not disabled by other settings.
//
// This predicate must be checked and must be true to call any of the top-level
// wasm eval/compile methods.
bool HasPlatformSupport(JSContext* cx);
// Return whether WebAssembly is supported on this platform. This determines
// whether the WebAssembly object is exposed to JS in this context / realm and
//
// It does *not* guarantee that a compiler is actually available; that has to be
// checked separately, as it is sometimes run-time variant, depending on whether
// a debugger has been created or not.
bool HasSupport(JSContext* cx);
// Predicates for compiler availability.
//
// These three predicates together select zero or one baseline compiler and zero
// or one optimizing compiler, based on: what's compiled into the executable,
// what's supported on the current platform, what's selected by options, and the
// current run-time environment. As it is possible for the computed values to
// change (when a value changes in about:config or the debugger pane is shown or
// hidden), it is inadvisable to cache these values in such a way that they
// could become invalid. Generally it is cheap always to recompute them.
bool BaselineAvailable(JSContext* cx);
bool IonAvailable(JSContext* cx);
bool CraneliftAvailable(JSContext* cx);
// Test all three.
bool AnyCompilerAvailable(JSContext* cx);
// Asm.JS is translated to wasm and then compiled using the wasm optimizing
// compiler; test whether this compiler is available.
bool WasmCompilerForAsmJSAvailable(JSContext* cx);
// Predicates for white-box compiler disablement testing.
//
// These predicates determine whether the optimizing compilers were disabled by
// features that are enabled at compile-time or run-time. They do not consider
// the hardware platform on whether other compilers are enabled.
//
// If `reason` is not null then it is populated with a string that describes
// the specific features that disable the compiler.
//
// Returns false on OOM (which happens only when a reason is requested),
// otherwise true, with the result in `*isDisabled` and optionally the reason in
// `*reason`.
bool BaselineDisabledByFeatures(JSContext* cx, bool* isDisabled,
JSStringBuilder* reason = nullptr);
bool IonDisabledByFeatures(JSContext* cx, bool* isDisabled,
JSStringBuilder* reason = nullptr);
bool CraneliftDisabledByFeatures(JSContext* cx, bool* isDisabled,
JSStringBuilder* reason = nullptr);
// Predicates for feature availability.
//
// The following predicates check whether particular wasm features are enabled,
// and for each, whether at least one compiler is (currently) available that
// supports the feature.
// Streaming compilation.
bool StreamingCompilationAvailable(JSContext* cx);
// Caching of optimized code. Implies both streaming compilation and an
// optimizing compiler tier.
bool CodeCachingAvailable(JSContext* cx);
// Shared memory and atomics.
bool ThreadsAvailable(JSContext* cx);
#define WASM_FEATURE(NAME, ...) bool NAME##Available(JSContext* cx);
JS_FOR_WASM_FEATURES(WASM_FEATURE, WASM_FEATURE, WASM_FEATURE)
#undef WASM_FEATURE
// Privileged content that can access experimental intrinsics
bool IsSimdPrivilegedContext(JSContext* cx);
// Very experimental SIMD operations.
bool SimdWormholeAvailable(JSContext* cx);
#if defined(ENABLE_WASM_SIMD) && defined(DEBUG)
// Report the result of a Simd simplification to the testing infrastructure.
void ReportSimdAnalysis(const char* data);
#endif
// Returns true if WebAssembly as configured by compile-time flags and run-time
// options can support try/catch, throw, rethrow, and branch_on_exn (evolving).
bool ExceptionsAvailable(JSContext* cx);
// Compiles the given binary wasm module given the ArrayBufferObject
// and links the module's imports with the given import object.
[[nodiscard]] bool Eval(JSContext* cx, Handle<TypedArrayObject*> code,
HandleObject importObj, HandleValue maybeOptions,
MutableHandleWasmInstanceObject instanceObj);
// Extracts the various imports from the given import object into the given
// ImportValues structure while checking the imports against the given module.
// The resulting structure can be passed to WasmModule::instantiate.
struct ImportValues;
[[nodiscard]] bool GetImports(JSContext* cx, const Module& module,
HandleObject importObj, ImportValues* imports);
// For testing cross-process (de)serialization, this pair of functions are
// responsible for, in the child process, compiling the given wasm bytecode
// to a wasm::Module that is serialized into the given byte array, and, in
// the parent process, deserializing the given byte array into a
// WebAssembly.Module object.
[[nodiscard]] bool CompileAndSerialize(JSContext* cx,
const ShareableBytes& bytecode,
Bytes* serialized);
[[nodiscard]] bool DeserializeModule(JSContext* cx, const Bytes& serialized,
MutableHandleObject module);
// A WebAssembly "Exported Function" is the spec name for the JS function
// objects created to wrap wasm functions. This predicate returns false
// for asm.js functions which are semantically just normal JS functions
// (even if they are implemented via wasm under the hood). The accessor
// functions for extracting the instance and func-index of a wasm function
// can be used for both wasm and asm.js, however.
bool IsWasmExportedFunction(JSFunction* fun);
Instance& ExportedFunctionToInstance(JSFunction* fun);
WasmInstanceObject* ExportedFunctionToInstanceObject(JSFunction* fun);
uint32_t ExportedFunctionToFuncIndex(JSFunction* fun);
bool IsSharedWasmMemoryObject(JSObject* obj);
} // namespace wasm
// The class of WebAssembly.Module. Each WasmModuleObject owns a
// wasm::Module. These objects are used both as content-facing JS objects and as
// internal implementation details of asm.js.
class WasmModuleObject : public NativeObject {
static const unsigned MODULE_SLOT = 0;
static const JSClassOps classOps_;
static const ClassSpec classSpec_;
static void finalize(JS::GCContext* gcx, JSObject* obj);
static bool imports(JSContext* cx, unsigned argc, Value* vp);
static bool exports(JSContext* cx, unsigned argc, Value* vp);
static bool customSections(JSContext* cx, unsigned argc, Value* vp);
public:
static const unsigned RESERVED_SLOTS = 1;
static const JSClass class_;
static const JSClass& protoClass_;
static const JSPropertySpec properties[];
static const JSFunctionSpec methods[];
static const JSFunctionSpec static_methods[];
static bool construct(JSContext*, unsigned, Value*);
static WasmModuleObject* create(JSContext* cx, const wasm::Module& module,
HandleObject proto);
const wasm::Module& module() const;
};
// The class of WebAssembly.Global. This wraps a storage location, and there is
// a per-agent one-to-one relationship between the WasmGlobalObject and the
// storage location (the Cell) it wraps: if a module re-exports an imported
// global, the imported and exported WasmGlobalObjects are the same, and if a
// module exports a global twice, the two exported WasmGlobalObjects are the
// same.
// TODO/AnyRef-boxing: With boxed immediates and strings, JSObject* is no longer
// the most appropriate representation for Cell::anyref.
STATIC_ASSERT_ANYREF_IS_JSOBJECT;
class WasmGlobalObject : public NativeObject {
static const unsigned MUTABLE_SLOT = 0;
static const unsigned VAL_SLOT = 1;
static const JSClassOps classOps_;
static const ClassSpec classSpec_;
static void finalize(JS::GCContext* gcx, JSObject* obj);
static void trace(JSTracer* trc, JSObject* obj);
static bool typeImpl(JSContext* cx, const CallArgs& args);
static bool type(JSContext* cx, unsigned argc, Value* vp);
static bool valueGetterImpl(JSContext* cx, const CallArgs& args);
static bool valueGetter(JSContext* cx, unsigned argc, Value* vp);
static bool valueSetterImpl(JSContext* cx, const CallArgs& args);
static bool valueSetter(JSContext* cx, unsigned argc, Value* vp);
public:
static const unsigned RESERVED_SLOTS = 2;
static const JSClass class_;
static const JSClass& protoClass_;
static const JSPropertySpec properties[];
static const JSFunctionSpec methods[];
static const JSFunctionSpec static_methods[];
static bool construct(JSContext*, unsigned, Value*);
static WasmGlobalObject* create(JSContext* cx, wasm::HandleVal value,
bool isMutable, HandleObject proto);
bool isNewborn() { return getReservedSlot(VAL_SLOT).isUndefined(); }
bool isMutable() const;
wasm::ValType type() const;
wasm::GCPtrVal& val() const;
};
// The class of WebAssembly.Instance. Each WasmInstanceObject owns a
// wasm::Instance. These objects are used both as content-facing JS objects and
// as internal implementation details of asm.js.
class WasmInstanceObject : public NativeObject {
static const unsigned INSTANCE_SLOT = 0;
static const unsigned EXPORTS_OBJ_SLOT = 1;
static const unsigned EXPORTS_SLOT = 2;
static const unsigned SCOPES_SLOT = 3;
static const unsigned INSTANCE_SCOPE_SLOT = 4;
static const unsigned GLOBALS_SLOT = 5;
static const JSClassOps classOps_;
static const ClassSpec classSpec_;
static bool exportsGetterImpl(JSContext* cx, const CallArgs& args);
static bool exportsGetter(JSContext* cx, unsigned argc, Value* vp);
bool isNewborn() const;
static void finalize(JS::GCContext* gcx, JSObject* obj);
static void trace(JSTracer* trc, JSObject* obj);
// ExportMap maps from function index to exported function object.
// This allows the instance to lazily create exported function
// objects on demand (instead up-front for all table elements) while
// correctly preserving observable function object identity.
using ExportMap = GCHashMap<uint32_t, HeapPtr<JSFunction*>,
DefaultHasher<uint32_t>, ZoneAllocPolicy>;
ExportMap& exports() const;
// See the definition inside WasmJS.cpp.
class UnspecifiedScopeMap;
UnspecifiedScopeMap& scopes() const;
public:
static const unsigned RESERVED_SLOTS = 6;
static const JSClass class_;
static const JSClass& protoClass_;
static const JSPropertySpec properties[];
static const JSFunctionSpec methods[];
static const JSFunctionSpec static_methods[];
static bool construct(JSContext*, unsigned, Value*);
static WasmInstanceObject* create(
JSContext* cx, RefPtr<const wasm::Code> code,
const wasm::DataSegmentVector& dataSegments,
const wasm::ElemSegmentVector& elemSegments, uint32_t globalDataLength,
HandleWasmMemoryObject memory,
Vector<RefPtr<wasm::Table>, 0, SystemAllocPolicy>&& tables,
const JSFunctionVector& funcImports,
const wasm::GlobalDescVector& globals,
const wasm::ValVector& globalImportValues,
const WasmGlobalObjectVector& globalObjs,
const WasmTagObjectVector& tagObjs, HandleObject proto,
UniquePtr<wasm::DebugState> maybeDebug);
void initExportsObj(JSObject& exportsObj);
wasm::Instance& instance() const;
JSObject& exportsObj() const;
[[nodiscard]] static bool getExportedFunction(
JSContext* cx, HandleWasmInstanceObject instanceObj, uint32_t funcIndex,
MutableHandleFunction fun);
const wasm::CodeRange& getExportedFunctionCodeRange(JSFunction* fun,
wasm::Tier tier);
static WasmInstanceScope* getScope(JSContext* cx,
HandleWasmInstanceObject instanceObj);
static WasmFunctionScope* getFunctionScope(
JSContext* cx, HandleWasmInstanceObject instanceObj, uint32_t funcIndex);
using GlobalObjectVector =
GCVector<HeapPtr<WasmGlobalObject*>, 0, ZoneAllocPolicy>;
GlobalObjectVector& indirectGlobals() const;
};
// The class of WebAssembly.Memory. A WasmMemoryObject references an ArrayBuffer
// or SharedArrayBuffer object which owns the actual memory.
class WasmMemoryObject : public NativeObject {
static const unsigned BUFFER_SLOT = 0;
static const unsigned OBSERVERS_SLOT = 1;
static const unsigned ISHUGE_SLOT = 2;
static const JSClassOps classOps_;
static const ClassSpec classSpec_;
static void finalize(JS::GCContext* gcx, JSObject* obj);
static bool bufferGetterImpl(JSContext* cx, const CallArgs& args);
static bool bufferGetter(JSContext* cx, unsigned argc, Value* vp);
static bool typeImpl(JSContext* cx, const CallArgs& args);
static bool type(JSContext* cx, unsigned argc, Value* vp);
static bool growImpl(JSContext* cx, const CallArgs& args);
static bool grow(JSContext* cx, unsigned argc, Value* vp);
static uint64_t growShared(HandleWasmMemoryObject memory, uint64_t delta);
using InstanceSet =
JS::WeakCache<GCHashSet<WeakHeapPtrWasmInstanceObject,
MovableCellHasher<WeakHeapPtrWasmInstanceObject>,
ZoneAllocPolicy>>;
bool hasObservers() const;
InstanceSet& observers() const;
InstanceSet* getOrCreateObservers(JSContext* cx);
public:
static const unsigned RESERVED_SLOTS = 3;
static const JSClass class_;
static const JSClass& protoClass_;
static const JSPropertySpec properties[];
static const JSFunctionSpec methods[];
static const JSFunctionSpec static_methods[];
static bool construct(JSContext*, unsigned, Value*);
static WasmMemoryObject* create(JSContext* cx,
Handle<ArrayBufferObjectMaybeShared*> buffer,
bool isHuge, HandleObject proto);
// `buffer()` returns the current buffer object always. If the buffer
// represents shared memory then `buffer().byteLength()` never changes, and
// in particular it may be a smaller value than that returned from
// `volatileMemoryLength()` below.
//
// Generally, you do not want to call `buffer().byteLength()`, but to call
// `volatileMemoryLength()`, instead.
ArrayBufferObjectMaybeShared& buffer() const;
// The current length of the memory in bytes. In the case of shared memory,
// the length can change at any time. Also note that this will acquire a lock
// for shared memory, so do not call this from a signal handler.
size_t volatileMemoryLength() const;
// The current length of the memory in pages. See the comment for
// `volatileMemoryLength` for details on why this is 'volatile'.
wasm::Pages volatilePages() const;
// The maximum length of the memory in pages. This is not 'volatile' in
// contrast to the current length, as it cannot change for shared memories.
wasm::Pages clampedMaxPages() const;
mozilla::Maybe<wasm::Pages> sourceMaxPages() const;
wasm::IndexType indexType() const;
bool isShared() const;
bool isHuge() const;
bool movingGrowable() const;
size_t boundsCheckLimit() const;
// If isShared() is true then obtain the underlying buffer object.
SharedArrayRawBuffer* sharedArrayRawBuffer() const;
bool addMovingGrowObserver(JSContext* cx, WasmInstanceObject* instance);
static uint64_t grow(HandleWasmMemoryObject memory, uint64_t delta,
JSContext* cx);
};
// The class of WebAssembly.Table. A WasmTableObject holds a refcount on a
// wasm::Table, allowing a Table to be shared between multiple Instances
// (eventually between multiple threads).
class WasmTableObject : public NativeObject {
static const unsigned TABLE_SLOT = 0;
static const JSClassOps classOps_;
static const ClassSpec classSpec_;
bool isNewborn() const;
static void finalize(JS::GCContext* gcx, JSObject* obj);
static void trace(JSTracer* trc, JSObject* obj);
static bool lengthGetterImpl(JSContext* cx, const CallArgs& args);
static bool lengthGetter(JSContext* cx, unsigned argc, Value* vp);
static bool typeImpl(JSContext* cx, const CallArgs& args);
static bool type(JSContext* cx, unsigned argc, Value* vp);
static bool getImpl(JSContext* cx, const CallArgs& args);
static bool get(JSContext* cx, unsigned argc, Value* vp);
static bool setImpl(JSContext* cx, const CallArgs& args);
static bool set(JSContext* cx, unsigned argc, Value* vp);
static bool growImpl(JSContext* cx, const CallArgs& args);
static bool grow(JSContext* cx, unsigned argc, Value* vp);
public:
static const unsigned RESERVED_SLOTS = 1;
static const JSClass class_;
static const JSClass& protoClass_;
static const JSPropertySpec properties[];
static const JSFunctionSpec methods[];
static const JSFunctionSpec static_methods[];
static bool construct(JSContext*, unsigned, Value*);
// Note that, after creation, a WasmTableObject's table() is not initialized
// and must be initialized before use.
static WasmTableObject* create(JSContext* cx, uint32_t initialLength,
mozilla::Maybe<uint32_t> maximumLength,
wasm::RefType tableType, HandleObject proto);
wasm::Table& table() const;
// Perform the standard `ToWebAssemblyValue` coercion on `value` and fill the
// range [index, index + length) in the table. Callers are required to ensure
// the range is within bounds. Returns false if the coercion failed.
bool fillRange(JSContext* cx, uint32_t index, uint32_t length,
HandleValue value) const;
#ifdef DEBUG
void assertRangeNull(uint32_t index, uint32_t length) const;
#endif
};
// The class of WebAssembly.Tag. This class is used to track exception tag
// types for exports and imports.
class WasmTagObject : public NativeObject {
static const unsigned TYPE_SLOT = 0;
static const JSClassOps classOps_;
static const ClassSpec classSpec_;
static void finalize(JS::GCContext* gcx, JSObject* obj);
static bool typeImpl(JSContext* cx, const CallArgs& args);
static bool type(JSContext* cx, unsigned argc, Value* vp);
public:
static const unsigned RESERVED_SLOTS = 1;
static const JSClass class_;
static const JSClass& protoClass_;
static const JSPropertySpec properties[];
static const JSFunctionSpec methods[];
static const JSFunctionSpec static_methods[];
static bool construct(JSContext*, unsigned, Value*);
static WasmTagObject* create(JSContext* cx,
const wasm::SharedTagType& tagType,
HandleObject proto);
const wasm::TagType* tagType() const;
const wasm::ValTypeVector& valueTypes() const;
wasm::ResultType resultType() const;
};
// The class of WebAssembly.Exception. This class is used for
// representing exceptions thrown from Wasm in JS. (it is also used as
// the internal representation for exceptions in Wasm)
class WasmExceptionObject : public NativeObject {
static const unsigned TAG_SLOT = 0;
static const unsigned TYPE_SLOT = 1;
static const unsigned DATA_SLOT = 2;
static const unsigned STACK_SLOT = 3;
static const JSClassOps classOps_;
static const ClassSpec classSpec_;
static void trace(JSTracer* trc, JSObject* obj);
static void finalize(JS::GCContext* gcx, JSObject* obj);
// Named isMethod instead of is to avoid name conflict.
static bool isMethod(JSContext* cx, unsigned argc, Value* vp);
static bool isImpl(JSContext* cx, const CallArgs& args);
static bool getArg(JSContext* cx, unsigned argc, Value* vp);
static bool getArgImpl(JSContext* cx, const CallArgs& args);
static bool getStack(JSContext* cx, unsigned argc, Value* vp);
static bool getStack_impl(JSContext* cx, const CallArgs& args);
uint8_t* typedMem() const;
[[nodiscard]] bool loadValue(JSContext* cx, size_t offset, wasm::ValType type,
MutableHandleValue vp);
[[nodiscard]] bool initValue(JSContext* cx, size_t offset, wasm::ValType type,
HandleValue value);
public:
static const unsigned RESERVED_SLOTS = 4;
static const JSClass class_;
static const JSClass& protoClass_;
static const JSPropertySpec properties[];
static const JSFunctionSpec methods[];
static const JSFunctionSpec static_methods[];
static bool construct(JSContext*, unsigned, Value*);
static WasmExceptionObject* create(JSContext* cx, Handle<WasmTagObject*> tag,
HandleObject stack, HandleObject proto);
bool isNewborn() const;
JSObject* stack() const;
const wasm::TagType* tagType() const;
WasmTagObject& tag() const;
static size_t offsetOfData() {
return NativeObject::getFixedSlotOffset(DATA_SLOT);
}
};
// The class of the WebAssembly global namespace object.
class WasmNamespaceObject : public NativeObject {
public:
static const JSClass class_;
private:
static const ClassSpec classSpec_;
};
extern const JSClass WasmFunctionClass;
} // namespace js
#endif // wasm_js_h