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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 2015 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,
* See the License for the specific language governing permissions and
* limitations under the License.
#ifndef wasm_module_h
#define wasm_module_h
#include "js/WasmModule.h"
#include "js/BuildId.h"
#include "wasm/WasmCode.h"
#include "wasm/WasmTable.h"
namespace js {
namespace wasm {
struct CompileArgs;
// In the context of wasm, the OptimizedEncodingListener specifically is
// listening for the completion of tier-2.
using Tier2Listener = RefPtr<JS::OptimizedEncodingListener>;
// A struct containing the typed, imported values that are harvested from the
// import object and passed to Module::instantiate(). This struct must be
// stored in a (Persistent)Rooted, not in the heap due to its use of TraceRoot()
// and complete lack of barriers.
struct ImportValues {
JSFunctionVector funcs;
WasmTableObjectVector tables;
WasmMemoryObject* memory;
WasmGlobalObjectVector globalObjs;
ValVector globalValues;
ImportValues() : memory(nullptr) {}
void trace(JSTracer* trc) {
if (memory) {
TraceRoot(trc, &memory, "import values memory");
// Module represents a compiled wasm module and primarily provides three
// operations: instantiation, tiered compilation, serialization. A Module can be
// instantiated any number of times to produce new Instance objects. A Module
// can have a single tier-2 task initiated to augment a Module's code with a
// higher tier. A Module can have its optimized code serialized at any point
// where the LinkData is also available, which is primarily (1) at the end of
// module generation, (2) at the end of tier-2 compilation.
// Fully linked-and-instantiated code (represented by Code and its owned
// ModuleSegment) can be shared between instances, provided none of those
// instances are being debugged. If patchable code is needed then each instance
// must have its own Code. Module eagerly creates a new Code and gives it to the
// first instance; it then instantiates new Code objects from a copy of the
// unlinked code that it keeps around for that purpose.
class Module : public JS::WasmModule {
const SharedCode code_;
const ImportVector imports_;
const ExportVector exports_;
const DataSegmentVector dataSegments_;
const ElemSegmentVector elemSegments_;
const CustomSectionVector customSections_;
// These fields are only meaningful when code_->metadata().debugEnabled.
// `debugCodeClaimed_` is set to false initially and then to true when
// `code_` is already being used for an instance and can't be shared because
// it may be patched by the debugger. Subsequent instances must then create
// copies by linking the `debugUnlinkedCode_` using `debugLinkData_`.
// This could all be removed if debugging didn't need to perform
// per-instance code patching.
mutable Atomic<bool> debugCodeClaimed_;
const UniqueConstBytes debugUnlinkedCode_;
const UniqueLinkData debugLinkData_;
const SharedBytes debugBytecode_;
// This field is set during tier-2 compilation and cleared on success or
// failure. These happen on different threads and are serialized by the
// control flow of helper tasks.
mutable Tier2Listener tier2Listener_;
// This flag is used for logging (and testing) purposes to indicate
// whether the module was deserialized (from a cache).
const bool loggingDeserialized_;
// This flag is only used for testing purposes and is cleared on success or
// failure. The field is racily polled from various threads.
mutable Atomic<bool> testingTier2Active_;
// Cached malloc allocation size for GC memory tracking.
size_t gcMallocBytesExcludingCode_;
bool instantiateFunctions(JSContext* cx,
const JSFunctionVector& funcImports) const;
bool instantiateMemory(JSContext* cx,
MutableHandleWasmMemoryObject memory) const;
bool instantiateImportedTable(JSContext* cx, const TableDesc& td,
Handle<WasmTableObject*> table,
WasmTableObjectVector* tableObjs,
SharedTableVector* tables) const;
bool instantiateLocalTable(JSContext* cx, const TableDesc& td,
WasmTableObjectVector* tableObjs,
SharedTableVector* tables) const;
bool instantiateTables(JSContext* cx,
const WasmTableObjectVector& tableImports,
MutableHandle<WasmTableObjectVector> tableObjs,
SharedTableVector* tables) const;
bool instantiateGlobals(JSContext* cx, const ValVector& globalImportValues,
WasmGlobalObjectVector& globalObjs) const;
bool initSegments(JSContext* cx, HandleWasmInstanceObject instance,
HandleWasmMemoryObject memory,
const ValVector& globalImportValues) const;
SharedCode getDebugEnabledCode() const;
bool makeStructTypeDescrs(
JSContext* cx,
MutableHandle<StructTypeDescrVector> structTypeDescrs) const;
class Tier2GeneratorTaskImpl;
Module(const Code& code, ImportVector&& imports, ExportVector&& exports,
DataSegmentVector&& dataSegments, ElemSegmentVector&& elemSegments,
CustomSectionVector&& customSections,
UniqueConstBytes debugUnlinkedCode = nullptr,
UniqueLinkData debugLinkData = nullptr,
const ShareableBytes* debugBytecode = nullptr,
bool loggingDeserialized = false)
: code_(&code),
testingTier2Active_(false) {
debugUnlinkedCode_ && debugLinkData_);
~Module() override;
const Code& code() const { return *code_; }
const ModuleSegment& moduleSegment(Tier t) const { return code_->segment(t); }
const Metadata& metadata() const { return code_->metadata(); }
const MetadataTier& metadata(Tier t) const { return code_->metadata(t); }
const ImportVector& imports() const { return imports_; }
const ExportVector& exports() const { return exports_; }
const CustomSectionVector& customSections() const { return customSections_; }
const Bytes& debugBytecode() const { return debugBytecode_->bytes; }
uint32_t codeLength(Tier t) const { return code_->segment(t).length(); }
const StructTypeVector& structTypes() const { return code_->structTypes(); }
// Instantiate this module with the given imports:
bool instantiate(JSContext* cx, ImportValues& imports,
HandleObject instanceProto,
MutableHandleWasmInstanceObject instanceObj) const;
// Tier-2 compilation may be initiated after the Module is constructed at
// most once. When tier-2 compilation completes, ModuleGenerator calls
// finishTier2() from a helper thread, passing tier-variant data which will
// be installed and made visible.
void startTier2(const CompileArgs& args, const ShareableBytes& bytecode,
JS::OptimizedEncodingListener* listener);
bool finishTier2(const LinkData& linkData2, UniqueCodeTier code2) const;
void testingBlockOnTier2Complete() const;
bool testingTier2Active() const { return testingTier2Active_; }
// Code caching support.
size_t serializedSize(const LinkData& linkData) const;
void serialize(const LinkData& linkData, uint8_t* begin, size_t size) const;
void serialize(const LinkData& linkData,
JS::OptimizedEncodingListener& listener) const;
static RefPtr<Module> deserialize(const uint8_t* begin, size_t size,
Metadata* maybeMetadata = nullptr);
bool loggingDeserialized() const { return loggingDeserialized_; }
// JS API and JS::WasmModule implementation:
JSObject* createObject(JSContext* cx) const override;
JSObject* createObjectForAsmJS(JSContext* cx) const override;
// about:memory reporting:
void addSizeOfMisc(MallocSizeOf mallocSizeOf, Metadata::SeenSet* seenMetadata,
Code::SeenSet* seenCode, size_t* code, size_t* data) const;
// GC malloc memory tracking:
void initGCMallocBytesExcludingCode();
size_t gcMallocBytesExcludingCode() const {
return gcMallocBytesExcludingCode_;
// Generated code analysis support:
bool extractCode(JSContext* cx, Tier tier, MutableHandleValue vp) const;
using MutableModule = RefPtr<Module>;
using SharedModule = RefPtr<const Module>;
// JS API implementations:
MOZ_MUST_USE bool GetOptimizedEncodingBuildId(JS::BuildIdCharVector* buildId);
} // namespace wasm
} // namespace js
#endif // wasm_module_h