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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:
* 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
* file, You can obtain one at */
#ifndef vm_SelfHosting_h_
#define vm_SelfHosting_h_
#include "NamespaceImports.h"
#include "js/CallNonGenericMethod.h"
#include "js/RootingAPI.h"
#include "js/TypeDecls.h"
// [SMDOC] Self-hosted JS
// Self-hosted JS allows implementing a part of the JS engine using JavaScript.
// This allows implementing new feature easily, and also enables JIT
// compilation to achieve better performance, for example with higher order
// functions. Self-hosted functions can be inlined in, and optimized with, the
// JS caller functions.
// Self-hosted JS code is compiled into a stencil during the initialization of
// the engine, and each function is instantiated into each global on demand.
// Self-hosted JS has several differences between regular JavaScript code,
// for performance optimization, security, and some other reasons.
// # Always strict mode
// Unlike regular JavaScript, self-hosted JS code is always in strict mode.
// # Prohibited syntax
// * Regular expression `/foo/` cannot be used
// * `obj.method(...)` and `obj[method](...)` style call cannot be used.
// See `callFunction` below
// * Object literal cannot contain duplicate property names
// * `yield*` cannot be used
// # No lazy parsing
// Self-hosted JS does not use lazy/syntax parsing: bytecode is generated
// eagerly for each function. However, we do instantiate the BaseScript lazily
// from the stencil for JSFunctions created for self-hosted built-ins. See
// `SelfHostedLazyScript` and `JSRuntime::selfHostedLazyScript`.
// # Extended function
// Functions with "$"-prefix in their name are allocated as extended function.
// See "SetCanonicalName" below.
// # Intrinsic helper functions
// Self-hosted JS has access to special functions that can interact with
// native code or internal representation of JS values and objects.
// See `intrinsic_functions` array in SelfHosting.cpp.
// # Stack Frame
// Stack frame inside self-hosted JS is hidden from Error.prototype.stack by
// default, to hide the internal from user code.
// During debugging self-hosted JS code, `MOZ_SHOW_ALL_JS_FRAMES` environment
// variable can be used to expose those frames
// # Debugger interaction
// Self-hosted JS is hidden from debugger, and no source notes or breakpoint
// is generated.
// Most function calls inside self-hosted JS are hidden from Debugger's
// `onNativeCall` hook, except for the following (see below for each):
// * `callContentFunction`
// * `constructContentFunction`
// * `allowContentIter`
// * `allowContentIterWith`
// * `allowContentIterWithNext`
// # XDR cache
// Compiling self-hosted JS code takes some time.
// To improve the startup performance, the bytecode for self-hosted JS code
// can be saved as XDR, and used by other instance. This is used to speed up
// JS shell tests and Firefox content process startup.
// See `JSRuntime::initSelfHostingStencil` function.
// # Special functions
// Self-hosted JS code has special functions, to emit special bytecode
// sequence, or directly operate on internals:
// callFunction(callee, thisV, arg0, ...)
// Call `callee` function with `thisV` as "this" value, passing
// arg0, ..., as arguments.
// This is used when "this" value is not `undefined.
// `obj.method(...)` syntax is forbidden in self-hosted JS, to avoid
// accidentally exposing the internal, or allowing user code to modify the
// behavior.
// If the `callee` can be user-provided, `callContentFunction` must be
// used instead.
// callContentFunction(callee, thisV, arg0, ...)
// Same as `callFunction`, but this must be used when calling possibly
// user-provided functions, even if "this" value is `undefined`.
// This exposes function calls to debuggers, using `JSOp::CallContent`
// opcode.
// constructContentFunction(callee, newTarget, arg0, ...)
// Construct `callee` function using `newTarget` as ``.
// This must be used when constructing possibly user-provided functions.
// This exposes constructs to debuggers, using `JSOp::NewContent` opcode.
// allowContentIter(iterable)
// Iteration such as for-of and spread on user-provided value is
// prohibited inside self-hosted JS by default.
// `allowContentIter` marks iteration allowed for given possibly
// user-provided iterable.
// This exposes implicit function calls around iteration to debuggers,
// using `JSOp::CallContentIter` opcode.
// Used in the following contexts:
// for (var item of allowContentIter(iterable)) { ... }
// [...allowContentIter(iterable)]
// allowContentIterWith(iterable, iteratorFunc)
// Special form of `allowContentIter`, where `iterable[Symbol.iterator]` is
// already retrieved.
// This directly uses `iteratorFunc` instead of accessing
// `iterable[Symbol.iterator]` again inside for-of bytecode.
// for (var item of allowContentIterWith(iterable, iteratorFunc)) { ... }
// allowContentIterWith(iterator, nextFunc)
// Special form of `allowContentIter`, where `iterable[Symbol.iterator]()`
// is already called and the iterator's `next` property retrieved.
// This form doesn't call `iterable[Symbol.iterator]` and directly uses
// `nextFunc` instead of retrieving it inside for-of bytecode.
// for (var item of allowContentIterWithNext(iterator, nextFunc)) { ... }
// DefineDataProperty(obj, key, value)
// Initialize `obj`'s `key` property with `value`, like
// `Object.defineProperty(obj, key, {value})`, using `JSOp::InitElem`
// opcode. This is almost always better than `obj[key] = value` because it
// ignores setters and other properties on the prototype chain.
// hasOwn(key, obj)
// Return `true` if `obj` has an own `key` property, using `JSOp::HasOwn`
// opcode.
// getPropertySuper(obj, key, receiver)
// Return `obj.[[Get]](key, receiver)`, using `JSOp::GetElemSuper` opcode.
// ToNumeric(v)
// Convert `v` to number, using `JSOp::ToNumeric` opcode
// ToString(v)
// Convert `v` to string, `JSOp::ToString` opcode
// GetBuiltinConstructor(name)
// Return built-in constructor for `name`, e.g. `"Array"`, using
// `JSOp::BuiltinObject` opcode.
// GetBuiltinPrototype(name)
// Return built-in prototype for `name`, e.g. `"RegExp"`, using
// `JSOp::BuiltinObject` opcode.
// GetBuiltinSymbol(name)
// Return built-in symbol `Symbol[name]`, using `JSOp::Symbol` opcode.
// SetIsInlinableLargeFunction(fun)
// Mark the large function `fun` inlineable.
// `fun` must be the last function declaration before this call.
// SetCanonicalName(fun)
// Set canonical name for the function `fun`.
// `fun` must be the last function declaration before this call, and also
// its function name must be prefixed with "$", to make it extended
// function and store the original function name in the extended slot.
// UnsafeGetReservedSlot(obj, slot)
// UnsafeGetObjectFromReservedSlot(obj, slot)
// UnsafeGetInt32FromReservedSlot(obj, slot)
// UnsafeGetStringFromReservedSlot(obj, slot)
// UnsafeGetBooleanFromReservedSlot(obj, slot)
// Get `obj`'s reserved slot specified by integer value `slot`.
// They are intrinsic helper functions, and also optimized during JIT
// compilation.
// UnsafeSetReservedSlot(obj, slot, value)
// Set `obj`'s reserved slot specified by integer value `slot` to `value`.
// This is an intrinsic helper function, and also optimized during JIT
// compilation.
// resumeGenerator(gen, value, kind)
// Resume generator `gen`, using `kind`, which is one of "next", "throw",
// or "return", pasing `value` as parameter, using `JSOp::Resume` opcode.
// forceInterpreter()
// Force interpreter execution for this function, using
// `JSOp::ForceInterpreter` opcode.
// This must be the first statement inside the function.
namespace JS {
class JS_PUBLIC_API CompileOptions;
namespace js {
class AnyInvokeArgs;
class PropertyName;
class ScriptSourceObject;
ScriptSourceObject* SelfHostingScriptSourceObject(JSContext* cx);
* Check whether the given JSFunction or Value is a self-hosted function whose
* self-hosted name is the given name.
bool IsSelfHostedFunctionWithName(JSFunction* fun, JSAtom* name);
bool IsSelfHostedFunctionWithName(const Value& v, JSAtom* name);
* Returns the name of the cloned function's binding in the self-hosted global.
* This returns a non-null value only when this is a top level function
* declaration in the self-hosted global.
PropertyName* GetClonedSelfHostedFunctionName(const JSFunction* fun);
void SetClonedSelfHostedFunctionName(JSFunction* fun, PropertyName* name);
constexpr char ExtendedUnclonedSelfHostedFunctionNamePrefix = '$';
* Uncloned self-hosted functions with `$` prefix are allocated as
* extended function, to store the original name in `_SetCanonicalName`.
bool IsExtendedUnclonedSelfHostedFunctionName(JSAtom* name);
void SetUnclonedSelfHostedCanonicalName(JSFunction* fun, JSAtom* name);
bool IsCallSelfHostedNonGenericMethod(NativeImpl impl);
bool ReportIncompatibleSelfHostedMethod(JSContext* cx, Handle<Value> thisValue);
/* Get the compile options used when compiling self hosted code. */
void FillSelfHostingCompileOptions(JS::CompileOptions& options);
const JSFunctionSpec* FindIntrinsicSpec(PropertyName* name);
#ifdef DEBUG
* Calls a self-hosted function by name.
* This function is only available in debug mode, because it always atomizes
* its |name| parameter. Use the alternative function below in non-debug code.
bool CallSelfHostedFunction(JSContext* cx, char const* name, HandleValue thisv,
const AnyInvokeArgs& args, MutableHandleValue rval);
* Calls a self-hosted function by name.
bool CallSelfHostedFunction(JSContext* cx, Handle<PropertyName*> name,
HandleValue thisv, const AnyInvokeArgs& args,
MutableHandleValue rval);
bool intrinsic_NewArrayIterator(JSContext* cx, unsigned argc, JS::Value* vp);
bool intrinsic_NewStringIterator(JSContext* cx, unsigned argc, JS::Value* vp);
bool intrinsic_NewRegExpStringIterator(JSContext* cx, unsigned argc,
JS::Value* vp);
bool IsTupleUnchecked(JSContext* cx, const CallArgs& args);
bool intrinsic_IsTuple(JSContext* cx, unsigned argc, JS::Value* vp);
} /* namespace js */
#endif /* vm_SelfHosting_h_ */