Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef js_experimental_JSStencil_h
#define js_experimental_JSStencil_h
/* The `JS::Stencil` type holds the output of the JS Parser before it is
* allocated on the GC heap as a `JSScript`. This form may be serialized as
* part of building a bytecode cache. This `Stencil` is not associated with any
* particular Realm and may be generated off-main-thread, making it useful for
* building script loaders.
*/
#include "mozilla/MemoryReporting.h" // mozilla::MallocSizeOf
#include "mozilla/RefPtr.h" // RefPtr, already_AddRefed
#include "mozilla/Utf8.h" // mozilla::Utf8Unit
#include "mozilla/Vector.h" // mozilla::Vector
#include <stddef.h> // size_t
#include "jstypes.h" // JS_PUBLIC_API
#include "js/CompileOptions.h" // JS::ReadOnlyCompileOptions, JS::InstantiateOptions, JS::ReadOnlyDecodeOptions
#include "js/SourceText.h" // JS::SourceText
#include "js/Transcoding.h" // JS::TranscodeBuffer, JS::TranscodeRange
struct JS_PUBLIC_API JSContext;
class JS_PUBLIC_API JSTracer;
// Underlying opaque type.
namespace js {
class FrontendContext;
namespace frontend {
struct CompilationStencil;
struct CompilationGCOutput;
struct CompilationInput;
struct PreallocatedCompilationGCOutput;
struct InitialStencilAndDelazifications;
} // namespace frontend
} // namespace js
// ************************************************************************
// Types
// ************************************************************************
namespace JS {
using Stencil = js::frontend::InitialStencilAndDelazifications;
using FrontendContext = js::FrontendContext;
// Temporary storage used during instantiating Stencil.
//
// Off-thread APIs can allocate this instance off main thread, and pass it back
// to the main thread, in order to reduce the main thread allocation.
struct JS_PUBLIC_API InstantiationStorage {
private:
// Owned CompilationGCOutput.
//
// This uses raw pointer instead of UniquePtr because
// PreallocatedCompilationGCOutput is opaque.
js::frontend::PreallocatedCompilationGCOutput* gcOutput_ = nullptr;
friend JS_PUBLIC_API JSScript* InstantiateGlobalStencil(
JSContext* cx, const InstantiateOptions& options, Stencil* stencil,
InstantiationStorage* storage);
friend JS_PUBLIC_API JSObject* InstantiateModuleStencil(
JSContext* cx, const InstantiateOptions& options, Stencil* stencil,
InstantiationStorage* storage);
friend JS_PUBLIC_API bool PrepareForInstantiate(
JS::FrontendContext* fc, JS::Stencil& stencil,
JS::InstantiationStorage& storage);
public:
InstantiationStorage() = default;
InstantiationStorage(InstantiationStorage&& other)
: gcOutput_(other.gcOutput_) {
other.gcOutput_ = nullptr;
}
~InstantiationStorage();
void operator=(InstantiationStorage&& other) {
gcOutput_ = other.gcOutput_;
other.gcOutput_ = nullptr;
}
private:
InstantiationStorage(const InstantiationStorage& other) = delete;
void operator=(const InstantiationStorage& aOther) = delete;
public:
bool isValid() const { return !!gcOutput_; }
};
} // namespace JS
// ************************************************************************
// Reference Count
// ************************************************************************
namespace JS {
// These non-member functions let us manipulate the ref counts of the opaque
// Stencil type. The RefPtrTraits below calls these for use when using the
// RefPtr type.
JS_PUBLIC_API void StencilAddRef(Stencil* stencil);
JS_PUBLIC_API void StencilRelease(Stencil* stencil);
} // namespace JS
namespace mozilla {
template <>
struct RefPtrTraits<JS::Stencil> {
static void AddRef(JS::Stencil* stencil) { JS::StencilAddRef(stencil); }
static void Release(JS::Stencil* stencil) { JS::StencilRelease(stencil); }
};
} // namespace mozilla
// ************************************************************************
// Properties
// ************************************************************************
namespace JS {
// Return true if the stencil relies on external data as a result of XDR
// decoding.
extern JS_PUBLIC_API bool StencilIsBorrowed(Stencil* stencil);
extern JS_PUBLIC_API size_t SizeOfStencil(Stencil* stencil,
mozilla::MallocSizeOf mallocSizeOf);
} // namespace JS
// ************************************************************************
// Compilation
// ************************************************************************
namespace JS {
// Compile the source text into a JS::Stencil using the provided options. The
// resulting stencil may be instantiated into any Realm on the current runtime
// and may be used multiple times.
//
// NOTE: On error, a null will be returned and an exception will be set on the
// JSContext.
extern JS_PUBLIC_API already_AddRefed<Stencil> CompileGlobalScriptToStencil(
JSContext* cx, const ReadOnlyCompileOptions& options,
SourceText<mozilla::Utf8Unit>& srcBuf);
extern JS_PUBLIC_API already_AddRefed<Stencil> CompileGlobalScriptToStencil(
JSContext* cx, const ReadOnlyCompileOptions& options,
SourceText<char16_t>& srcBuf);
// Compile the source text into a JS::Stencil using "module" parse goal. The
// ECMAScript spec defines special semantics so we use a seperate entry point
// here for clarity. The result is still a JS::Stencil, but should use the
// appropriate instantiate API below.
extern JS_PUBLIC_API already_AddRefed<Stencil> CompileModuleScriptToStencil(
JSContext* cx, const ReadOnlyCompileOptions& options,
SourceText<mozilla::Utf8Unit>& srcBuf);
extern JS_PUBLIC_API already_AddRefed<Stencil> CompileModuleScriptToStencil(
JSContext* cx, const ReadOnlyCompileOptions& options,
SourceText<char16_t>& srcBuf);
} // namespace JS
// ************************************************************************
// Instantiation
// ************************************************************************
namespace JS {
// Instantiate the Stencil into current Realm and return the JSScript.
extern JS_PUBLIC_API JSScript* InstantiateGlobalStencil(
JSContext* cx, const InstantiateOptions& options, Stencil* stencil,
InstantiationStorage* storage = nullptr);
// Instantiate a module Stencil and return the associated object. Inside the
// engine this is a js::ModuleObject.
extern JS_PUBLIC_API JSObject* InstantiateModuleStencil(
JSContext* cx, const InstantiateOptions& options, Stencil* stencil,
InstantiationStorage* storage = nullptr);
} // namespace JS
// ************************************************************************
// Transcoding
// ************************************************************************
namespace JS {
// Serialize the Stencil into the transcode buffer.
extern JS_PUBLIC_API TranscodeResult EncodeStencil(JSContext* cx,
Stencil* stencil,
TranscodeBuffer& buffer);
// Deserialize data and create a new Stencil.
extern JS_PUBLIC_API TranscodeResult
DecodeStencil(JSContext* cx, const ReadOnlyDecodeOptions& options,
const TranscodeRange& range, Stencil** stencilOut);
extern JS_PUBLIC_API TranscodeResult
DecodeStencil(JS::FrontendContext* fc, const ReadOnlyDecodeOptions& options,
const TranscodeRange& range, Stencil** stencilOut);
// ************************************************************************
// Collect delazifications
// ************************************************************************
// Start collecting delazifications for given script or module's source object.
//
// If the source object is already collecting delazifications, alreadyStarted is
// set to true and returns true. alreadyStarted is set to false otherwise.
extern JS_PUBLIC_API bool StartCollectingDelazifications(
JSContext* cx, JS::Handle<JSScript*> script, Stencil* stencil,
bool& alreadyStarted);
extern JS_PUBLIC_API bool StartCollectingDelazifications(
JSContext* cx, JS::Handle<JSObject*> module, Stencil* stencil,
bool& alreadyStarted);
// Finish collecting delazifications and retrieve the result.
//
// With |buffer| out-parameter, the result is encoded and appended to the
// buffer. If failed, the content of |buffer| would be undefined.
//
// If the `buffer` isn't empty, the start of the `buffer` should meet
// JS::IsTranscodingBytecodeAligned, and the length should meet
// JS::IsTranscodingBytecodeOffsetAligned.
//
// NOTE: As long as IsTranscodingBytecodeOffsetAligned is met, that means
// there's JS::BytecodeOffsetAlignment+extra bytes in the buffer,
// IsTranscodingBytecodeAligned should be guaranteed to meet by
// malloc, used by MallocAllocPolicy in mozilla::Vector.
extern JS_PUBLIC_API bool FinishCollectingDelazifications(
JSContext* cx, Handle<JSScript*> script, TranscodeBuffer& buffer);
// Similar to |JS::FinishCollectingDelazifications|, but receives module obect.
extern JS_PUBLIC_API bool FinishCollectingDelazifications(
JSContext* cx, Handle<JSObject*> module, TranscodeBuffer& buffer);
// Instead of transcoding to a buffer, return the JS::Stencil that reflects
// the delazification from the execution.
extern JS_PUBLIC_API bool FinishCollectingDelazifications(
JSContext* cx, Handle<JSScript*> script, JS::Stencil** stencilOut);
extern JS_PUBLIC_API void AbortCollectingDelazifications(
Handle<JSScript*> script);
extern JS_PUBLIC_API void AbortCollectingDelazifications(
Handle<JSObject*> module);
} // namespace JS
#endif // js_experimental_JSStencil_h