Adding upstream version 115.8.0esr.upstream/115.8.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 999 insertions, 0 deletions

diff --git a/js/src/vm/Stack.h b/js/src/vm/Stack.h
new file mode 100644
index 0000000000..d537cb80af
--- /dev/null
+++ b/js/src/vm/Stack.h
@@ -0,0 +1,999 @@
+/* -*- 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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef vm_Stack_h
+#define vm_Stack_h
+
+#include "mozilla/HashFunctions.h"
+#include "mozilla/MemoryReporting.h"
+
+#include <algorithm>
+#include <type_traits>
+
+#include "js/ErrorReport.h"
+#include "js/friend/ErrorMessages.h"  // js::GetErrorMessage, JSMSG_*
+#include "js/RootingAPI.h"
+#include "js/TypeDecls.h"
+#include "js/ValueArray.h"
+#include "vm/ArgumentsObject.h"
+#include "vm/JSFunction.h"
+#include "vm/JSScript.h"
+#include "wasm/WasmDebugFrame.h"  // js::wasm::DebugFrame
+
+namespace js {
+
+class InterpreterRegs;
+class CallObject;
+class FrameIter;
+class ClassBodyScope;
+class EnvironmentObject;
+class BlockLexicalEnvironmentObject;
+class ExtensibleLexicalEnvironmentObject;
+class GeckoProfilerRuntime;
+class InterpreterFrame;
+class EnvironmentIter;
+class EnvironmentCoordinate;
+
+namespace jit {
+class CommonFrameLayout;
+}
+namespace wasm {
+class Instance;
+}  // namespace wasm
+
+// [SMDOC] VM stack layout
+//
+// A JSRuntime's stack consists of a linked list of activations. Every
+// activation contains a number of scripted frames that are either running in
+// the interpreter (InterpreterActivation) or JIT code (JitActivation). The
+// frames inside a single activation are contiguous: whenever C++ calls back
+// into JS, a new activation is pushed.
+//
+// Every activation is tied to a single JSContext and JS::Compartment. This
+// means we can reconstruct a given context's stack by skipping activations
+// belonging to other contexts. This happens whenever an embedding enters the JS
+// engine on cx1 and then, from a native called by the JS engine, reenters the
+// VM on cx2.
+
+// Interpreter frames (InterpreterFrame)
+//
+// Each interpreter script activation (global or function code) is given a
+// fixed-size header (js::InterpreterFrame). The frame contains bookkeeping
+// information about the activation and links to the previous frame.
+//
+// The values after an InterpreterFrame in memory are its locals followed by its
+// expression stack. InterpreterFrame::argv_ points to the frame's arguments.
+// Missing formal arguments are padded with |undefined|, so the number of
+// arguments is always >= the number of formals.
+//
+// The top of an activation's current frame's expression stack is pointed to by
+// the activation's "current regs", which contains the stack pointer 'sp'. In
+// the interpreter, sp is adjusted as individual values are pushed and popped
+// from the stack and the InterpreterRegs struct (pointed to by the
+// InterpreterActivation) is a local var of js::Interpret.
+
+enum MaybeCheckAliasing { CHECK_ALIASING = true, DONT_CHECK_ALIASING = false };
+
+}  // namespace js
+
+/*****************************************************************************/
+
+namespace js {
+
+namespace jit {
+class BaselineFrame;
+class RematerializedFrame;
+}  // namespace jit
+
+/**
+ * Pointer to a live JS or WASM stack frame.
+ */
+class AbstractFramePtr {
+  friend class FrameIter;
+
+  uintptr_t ptr_;
+
+  enum {
+    Tag_InterpreterFrame = 0x1,
+    Tag_BaselineFrame = 0x2,
+    Tag_RematerializedFrame = 0x3,
+    Tag_WasmDebugFrame = 0x4,
+    TagMask = 0x7
+  };
+
+ public:
+  AbstractFramePtr() : ptr_(0) {}
+
+  MOZ_IMPLICIT AbstractFramePtr(InterpreterFrame* fp)
+      : ptr_(fp ? uintptr_t(fp) | Tag_InterpreterFrame : 0) {
+    MOZ_ASSERT_IF(fp, asInterpreterFrame() == fp);
+  }
+
+  MOZ_IMPLICIT AbstractFramePtr(jit::BaselineFrame* fp)
+      : ptr_(fp ? uintptr_t(fp) | Tag_BaselineFrame : 0) {
+    MOZ_ASSERT_IF(fp, asBaselineFrame() == fp);
+  }
+
+  MOZ_IMPLICIT AbstractFramePtr(jit::RematerializedFrame* fp)
+      : ptr_(fp ? uintptr_t(fp) | Tag_RematerializedFrame : 0) {
+    MOZ_ASSERT_IF(fp, asRematerializedFrame() == fp);
+  }
+
+  MOZ_IMPLICIT AbstractFramePtr(wasm::DebugFrame* fp)
+      : ptr_(fp ? uintptr_t(fp) | Tag_WasmDebugFrame : 0) {
+    static_assert(wasm::DebugFrame::Alignment >= TagMask, "aligned");
+    MOZ_ASSERT_IF(fp, asWasmDebugFrame() == fp);
+  }
+
+  bool isInterpreterFrame() const {
+    return (ptr_ & TagMask) == Tag_InterpreterFrame;
+  }
+  InterpreterFrame* asInterpreterFrame() const {
+    MOZ_ASSERT(isInterpreterFrame());
+    InterpreterFrame* res = (InterpreterFrame*)(ptr_ & ~TagMask);
+    MOZ_ASSERT(res);
+    return res;
+  }
+  bool isBaselineFrame() const { return (ptr_ & TagMask) == Tag_BaselineFrame; }
+  jit::BaselineFrame* asBaselineFrame() const {
+    MOZ_ASSERT(isBaselineFrame());
+    jit::BaselineFrame* res = (jit::BaselineFrame*)(ptr_ & ~TagMask);
+    MOZ_ASSERT(res);
+    return res;
+  }
+  bool isRematerializedFrame() const {
+    return (ptr_ & TagMask) == Tag_RematerializedFrame;
+  }
+  jit::RematerializedFrame* asRematerializedFrame() const {
+    MOZ_ASSERT(isRematerializedFrame());
+    jit::RematerializedFrame* res =
+        (jit::RematerializedFrame*)(ptr_ & ~TagMask);
+    MOZ_ASSERT(res);
+    return res;
+  }
+  bool isWasmDebugFrame() const {
+    return (ptr_ & TagMask) == Tag_WasmDebugFrame;
+  }
+  wasm::DebugFrame* asWasmDebugFrame() const {
+    MOZ_ASSERT(isWasmDebugFrame());
+    wasm::DebugFrame* res = (wasm::DebugFrame*)(ptr_ & ~TagMask);
+    MOZ_ASSERT(res);
+    return res;
+  }
+
+  void* raw() const { return reinterpret_cast<void*>(ptr_); }
+
+  bool operator==(const AbstractFramePtr& other) const {
+    return ptr_ == other.ptr_;
+  }
+  bool operator!=(const AbstractFramePtr& other) const {
+    return ptr_ != other.ptr_;
+  }
+
+  explicit operator bool() const { return !!ptr_; }
+
+  inline JSObject* environmentChain() const;
+  inline CallObject& callObj() const;
+  inline bool initFunctionEnvironmentObjects(JSContext* cx);
+  inline bool pushVarEnvironment(JSContext* cx, Handle<Scope*> scope);
+  template <typename SpecificEnvironment>
+  inline void pushOnEnvironmentChain(SpecificEnvironment& env);
+  template <typename SpecificEnvironment>
+  inline void popOffEnvironmentChain();
+
+  inline JS::Realm* realm() const;
+
+  inline bool hasInitialEnvironment() const;
+  inline bool isGlobalFrame() const;
+  inline bool isModuleFrame() const;
+  inline bool isEvalFrame() const;
+  inline bool isDebuggerEvalFrame() const;
+
+  inline bool hasScript() const;
+  inline JSScript* script() const;
+  inline wasm::Instance* wasmInstance() const;
+  inline GlobalObject* global() const;
+  inline bool hasGlobal(const GlobalObject* global) const;
+  inline JSFunction* callee() const;
+  inline Value calleev() const;
+  inline Value& thisArgument() const;
+
+  inline bool isConstructing() const;
+
+  inline bool debuggerNeedsCheckPrimitiveReturn() const;
+
+  inline bool isFunctionFrame() const;
+  inline bool isGeneratorFrame() const;
+
+  inline bool saveGeneratorSlots(JSContext* cx, unsigned nslots,
+                                 ArrayObject* dest) const;
+
+  inline bool hasCachedSavedFrame() const;
+
+  inline unsigned numActualArgs() const;
+  inline unsigned numFormalArgs() const;
+
+  inline Value* argv() const;
+
+  inline bool hasArgs() const;
+  inline bool hasArgsObj() const;
+  inline ArgumentsObject& argsObj() const;
+  inline void initArgsObj(ArgumentsObject& argsobj) const;
+
+  inline Value& unaliasedLocal(uint32_t i);
+  inline Value& unaliasedFormal(
+      unsigned i, MaybeCheckAliasing checkAliasing = CHECK_ALIASING);
+  inline Value& unaliasedActual(
+      unsigned i, MaybeCheckAliasing checkAliasing = CHECK_ALIASING);
+  template <class Op>
+  inline void unaliasedForEachActual(JSContext* cx, Op op);
+
+  inline bool prevUpToDate() const;
+  inline void setPrevUpToDate() const;
+  inline void unsetPrevUpToDate() const;
+
+  inline bool isDebuggee() const;
+  inline void setIsDebuggee();
+  inline void unsetIsDebuggee();
+
+  inline HandleValue returnValue() const;
+  inline void setReturnValue(const Value& rval) const;
+
+  friend void GDBTestInitAbstractFramePtr(AbstractFramePtr&, InterpreterFrame*);
+  friend void GDBTestInitAbstractFramePtr(AbstractFramePtr&,
+                                          jit::BaselineFrame*);
+  friend void GDBTestInitAbstractFramePtr(AbstractFramePtr&,
+                                          jit::RematerializedFrame*);
+  friend void GDBTestInitAbstractFramePtr(AbstractFramePtr& frame,
+                                          wasm::DebugFrame* ptr);
+};
+
+class NullFramePtr : public AbstractFramePtr {
+ public:
+  NullFramePtr() : AbstractFramePtr() {}
+};
+
+enum MaybeConstruct { NO_CONSTRUCT = false, CONSTRUCT = true };
+
+/*****************************************************************************/
+
+class InterpreterFrame {
+  enum Flags : uint32_t {
+    CONSTRUCTING = 0x1, /* frame is for a constructor invocation */
+
+    RESUMED_GENERATOR = 0x2, /* frame is for a resumed generator invocation */
+
+    /* Function prologue state */
+    HAS_INITIAL_ENV =
+        0x4,            /* callobj created for function or var env for eval */
+    HAS_ARGS_OBJ = 0x8, /* ArgumentsObject created for needsArgsObj script */
+
+    /* Lazy frame initialization */
+    HAS_RVAL = 0x10, /* frame has rval_ set */
+
+    /* Debugger state */
+    PREV_UP_TO_DATE = 0x20, /* see DebugScopes::updateLiveScopes */
+
+    /*
+     * See comment above 'isDebuggee' in Realm.h for explanation of
+     * invariants of debuggee compartments, scripts, and frames.
+     */
+    DEBUGGEE = 0x40, /* Execution is being observed by Debugger */
+
+    /* Used in tracking calls and profiling (see vm/GeckoProfiler.cpp) */
+    HAS_PUSHED_PROF_FRAME = 0x80, /* Gecko Profiler was notified of entry */
+
+    /*
+     * If set, we entered one of the JITs and ScriptFrameIter should skip
+     * this frame.
+     */
+    RUNNING_IN_JIT = 0x100,
+
+    /*
+     * If set, this frame has been on the stack when
+     * |js::SavedStacks::saveCurrentStack| was called, and so there is a
+     * |js::SavedFrame| object cached for this frame.
+     */
+    HAS_CACHED_SAVED_FRAME = 0x200,
+  };
+
+  mutable uint32_t flags_; /* bits described by Flags */
+  uint32_t nactual_;       /* number of actual arguments, for function frames */
+  JSScript* script_;       /* the script we're executing */
+  JSObject* envChain_;     /* current environment chain */
+  Value rval_;             /* if HAS_RVAL, return value of the frame */
+  ArgumentsObject* argsObj_; /* if HAS_ARGS_OBJ, the call's arguments object */
+
+  /*
+   * Previous frame and its pc and sp. Always nullptr for
+   * InterpreterActivation's entry frame, always non-nullptr for inline
+   * frames.
+   */
+  InterpreterFrame* prev_;
+  jsbytecode* prevpc_;
+  Value* prevsp_;
+
+  /*
+   * For an eval-in-frame DEBUGGER_EVAL frame, the frame in whose scope
+   * we're evaluating code. Iteration treats this as our previous frame.
+   */
+  AbstractFramePtr evalInFramePrev_;
+
+  Value* argv_;          /* If hasArgs(), points to frame's arguments. */
+  LifoAlloc::Mark mark_; /* Used to release memory for this frame. */
+
+  static void staticAsserts() {
+    static_assert(offsetof(InterpreterFrame, rval_) % sizeof(Value) == 0);
+    static_assert(sizeof(InterpreterFrame) % sizeof(Value) == 0);
+  }
+
+  /*
+   * The utilities are private since they are not able to assert that only
+   * unaliased vars/formals are accessed. Normal code should prefer the
+   * InterpreterFrame::unaliased* members (or InterpreterRegs::stackDepth for
+   * the usual "depth is at least" assertions).
+   */
+  Value* slots() const { return (Value*)(this + 1); }
+  Value* base() const { return slots() + script()->nfixed(); }
+
+  friend class FrameIter;
+  friend class InterpreterRegs;
+  friend class InterpreterStack;
+  friend class jit::BaselineFrame;
+
+  /*
+   * Frame initialization, called by InterpreterStack operations after acquiring
+   * the raw memory for the frame:
+   */
+
+  /* Used for Invoke and Interpret. */
+  void initCallFrame(InterpreterFrame* prev, jsbytecode* prevpc, Value* prevsp,
+                     JSFunction& callee, JSScript* script, Value* argv,
+                     uint32_t nactual, MaybeConstruct constructing);
+
+  /* Used for eval, module or global frames. */
+  void initExecuteFrame(JSContext* cx, HandleScript script,
+                        AbstractFramePtr prev, HandleObject envChain);
+
+ public:
+  /*
+   * Frame prologue/epilogue
+   *
+   * Every stack frame must have 'prologue' called before executing the
+   * first op and 'epilogue' called after executing the last op and before
+   * popping the frame (whether the exit is exceptional or not).
+   *
+   * For inline JS calls/returns, it is easy to call the prologue/epilogue
+   * exactly once. When calling JS from C++, Invoke/Execute push the stack
+   * frame but do *not* call the prologue/epilogue. That means Interpret
+   * must call the prologue/epilogue for the entry frame. This scheme
+   * simplifies jit compilation.
+   *
+   * An important corner case is what happens when an error occurs (OOM,
+   * over-recursed) after pushing the stack frame but before 'prologue' is
+   * called or completes fully. To simplify usage, 'epilogue' does not assume
+   * 'prologue' has completed and handles all the intermediate state details.
+   */
+
+  bool prologue(JSContext* cx);
+  void epilogue(JSContext* cx, jsbytecode* pc);
+
+  bool checkReturn(JSContext* cx, HandleValue thisv, MutableHandleValue result);
+
+  bool initFunctionEnvironmentObjects(JSContext* cx);
+
+  /*
+   * Initialize locals of newly-pushed frame to undefined.
+   */
+  void initLocals();
+
+  /*
+   * Stack frame type
+   *
+   * A stack frame may have one of four types, which determines which
+   * members of the frame may be accessed and other invariants:
+   *
+   *  global frame:   execution of global code
+   *  function frame: execution of function code
+   *  module frame:   execution of a module
+   *  eval frame:     execution of eval code
+   */
+
+  bool isGlobalFrame() const { return script_->isGlobalCode(); }
+
+  bool isModuleFrame() const { return script_->isModule(); }
+
+  bool isEvalFrame() const { return script_->isForEval(); }
+
+  bool isFunctionFrame() const { return script_->isFunction(); }
+
+  /*
+   * Previous frame
+   *
+   * A frame's 'prev' frame is either null or the previous frame pointed to
+   * by cx->regs->fp when this frame was pushed. Often, given two prev-linked
+   * frames, the next-frame is a function or eval that was called by the
+   * prev-frame, but not always: the prev-frame may have called a native that
+   * reentered the VM through JS_CallFunctionValue on the same context
+   * (without calling JS_SaveFrameChain) which pushed the next-frame. Thus,
+   * 'prev' has little semantic meaning and basically just tells the VM what
+   * to set cx->regs->fp to when this frame is popped.
+   */
+
+  InterpreterFrame* prev() const { return prev_; }
+
+  AbstractFramePtr evalInFramePrev() const {
+    MOZ_ASSERT(isEvalFrame());
+    return evalInFramePrev_;
+  }
+
+  /*
+   * (Unaliased) locals and arguments
+   *
+   * Only non-eval function frames have arguments. The arguments pushed by
+   * the caller are the 'actual' arguments. The declared arguments of the
+   * callee are the 'formal' arguments. When the caller passes less actual
+   * arguments, missing formal arguments are padded with |undefined|.
+   *
+   * When a local/formal variable is aliased (accessed by nested closures,
+   * environment operations, or 'arguments'), the canonical location for
+   * that value is the slot of an environment object.  Aliased locals don't
+   * have stack slots assigned to them.  These functions assert that
+   * accesses to stack values are unaliased.
+   */
+
+  inline Value& unaliasedLocal(uint32_t i);
+
+  bool hasArgs() const { return isFunctionFrame(); }
+  inline Value& unaliasedFormal(unsigned i,
+                                MaybeCheckAliasing = CHECK_ALIASING);
+  inline Value& unaliasedActual(unsigned i,
+                                MaybeCheckAliasing = CHECK_ALIASING);
+  template <class Op>
+  inline void unaliasedForEachActual(Op op);
+
+  unsigned numFormalArgs() const {
+    MOZ_ASSERT(hasArgs());
+    return callee().nargs();
+  }
+  unsigned numActualArgs() const {
+    MOZ_ASSERT(hasArgs());
+    return nactual_;
+  }
+
+  /* Watch out, this exposes a pointer to the unaliased formal arg array. */
+  Value* argv() const {
+    MOZ_ASSERT(hasArgs());
+    return argv_;
+  }
+
+  /*
+   * Arguments object
+   *
+   * If a non-eval function has script->needsArgsObj, an arguments object is
+   * created in the prologue and stored in the local variable for the
+   * 'arguments' binding (script->argumentsLocal). Since this local is
+   * mutable, the arguments object can be overwritten and we can "lose" the
+   * arguments object. Thus, InterpreterFrame keeps an explicit argsObj_ field
+   * so that the original arguments object is always available.
+   */
+
+  ArgumentsObject& argsObj() const;
+  void initArgsObj(ArgumentsObject& argsobj);
+
+  ArrayObject* createRestParameter(JSContext* cx);
+
+  /*
+   * Environment chain
+   *
+   * In theory, the environment chain would contain an object for every
+   * lexical scope. However, only objects that are required for dynamic
+   * lookup are actually created.
+   *
+   * Given that an InterpreterFrame corresponds roughly to a ES Execution
+   * Context (ES 10.3), GetVariablesObject corresponds to the
+   * VariableEnvironment component of a Exection Context. Intuitively, the
+   * variables object is where new bindings (variables and functions) are
+   * stored. One might expect that this is either the Call object or
+   * envChain.globalObj for function or global code, respectively, however
+   * the JSAPI allows calls of Execute to specify a variables object on the
+   * environment chain other than the call/global object. This allows
+   * embeddings to run multiple scripts under the same global, each time
+   * using a new variables object to collect and discard the script's global
+   * variables.
+   */
+
+  inline HandleObject environmentChain() const;
+
+  inline EnvironmentObject& aliasedEnvironment(EnvironmentCoordinate ec) const;
+  inline EnvironmentObject& aliasedEnvironmentMaybeDebug(
+      EnvironmentCoordinate ec) const;
+  inline GlobalObject& global() const;
+  inline CallObject& callObj() const;
+  inline ExtensibleLexicalEnvironmentObject& extensibleLexicalEnvironment()
+      const;
+
+  template <typename SpecificEnvironment>
+  inline void pushOnEnvironmentChain(SpecificEnvironment& env);
+  template <typename SpecificEnvironment>
+  inline void popOffEnvironmentChain();
+  inline void replaceInnermostEnvironment(BlockLexicalEnvironmentObject& env);
+
+  // Push a VarEnvironmentObject for function frames of functions that have
+  // parameter expressions with closed over var bindings.
+  bool pushVarEnvironment(JSContext* cx, Handle<Scope*> scope);
+
+  /*
+   * For lexical envs with aliased locals, these interfaces push and pop
+   * entries on the environment chain.  The "freshen" operation replaces the
+   * current lexical env with a fresh copy of it, to implement semantics
+   * providing distinct bindings per iteration of a for(;;) loop whose head
+   * has a lexical declaration.  The "recreate" operation replaces the
+   * current lexical env with a copy of it containing uninitialized
+   * bindings, to implement semantics providing distinct bindings per
+   * iteration of a for-in/of loop.
+   */
+
+  bool pushLexicalEnvironment(JSContext* cx, Handle<LexicalScope*> scope);
+  bool freshenLexicalEnvironment(JSContext* cx);
+  bool recreateLexicalEnvironment(JSContext* cx);
+
+  bool pushClassBodyEnvironment(JSContext* cx, Handle<ClassBodyScope*> scope);
+
+  /*
+   * Script
+   *
+   * All frames have an associated JSScript which holds the bytecode being
+   * executed for the frame.
+   */
+
+  JSScript* script() const { return script_; }
+
+  /* Return the previous frame's pc. */
+  jsbytecode* prevpc() {
+    MOZ_ASSERT(prev_);
+    return prevpc_;
+  }
+
+  /* Return the previous frame's sp. */
+  Value* prevsp() {
+    MOZ_ASSERT(prev_);
+    return prevsp_;
+  }
+
+  /*
+   * Return the 'this' argument passed to a non-eval function frame. This is
+   * not necessarily the frame's this-binding, for instance non-strict
+   * functions will box primitive 'this' values and thisArgument() will
+   * return the original, unboxed Value.
+   */
+  Value& thisArgument() const {
+    MOZ_ASSERT(isFunctionFrame());
+    return argv()[-1];
+  }
+
+  /*
+   * Callee
+   *
+   * Only function frames have a true callee. An eval frame in a function has
+   * the same callee as its containing function frame. An async module has to
+   * create a wrapper callee to allow passing the script to generators for
+   * pausing and resuming.
+   */
+
+  JSFunction& callee() const {
+    MOZ_ASSERT(isFunctionFrame());
+    return calleev().toObject().as<JSFunction>();
+  }
+
+  const Value& calleev() const {
+    MOZ_ASSERT(isFunctionFrame());
+    return argv()[-2];
+  }
+
+  /*
+   * New Target
+   *
+   * Only non-arrow function frames have a meaningful newTarget.
+   */
+  Value newTarget() const {
+    MOZ_ASSERT(isFunctionFrame());
+    MOZ_ASSERT(!callee().isArrow());
+
+    if (isConstructing()) {
+      unsigned pushedArgs = std::max(numFormalArgs(), numActualArgs());
+      return argv()[pushedArgs];
+    }
+    return UndefinedValue();
+  }
+
+  /* Profiler flags */
+
+  bool hasPushedGeckoProfilerFrame() {
+    return !!(flags_ & HAS_PUSHED_PROF_FRAME);
+  }
+
+  void setPushedGeckoProfilerFrame() { flags_ |= HAS_PUSHED_PROF_FRAME; }
+
+  void unsetPushedGeckoProfilerFrame() { flags_ &= ~HAS_PUSHED_PROF_FRAME; }
+
+  /* Return value */
+
+  bool hasReturnValue() const { return flags_ & HAS_RVAL; }
+
+  MutableHandleValue returnValue() {
+    if (!hasReturnValue()) {
+      rval_.setUndefined();
+    }
+    return MutableHandleValue::fromMarkedLocation(&rval_);
+  }
+
+  void markReturnValue() { flags_ |= HAS_RVAL; }
+
+  void setReturnValue(const Value& v) {
+    rval_ = v;
+    markReturnValue();
+  }
+
+  // Copy values from this frame into a private Array, owned by the
+  // GeneratorObject, for suspending.
+  [[nodiscard]] inline bool saveGeneratorSlots(JSContext* cx, unsigned nslots,
+                                               ArrayObject* dest) const;
+
+  // Copy values from the Array into this stack frame, for resuming.
+  inline void restoreGeneratorSlots(ArrayObject* src);
+
+  void resumeGeneratorFrame(JSObject* envChain) {
+    MOZ_ASSERT(script()->isGenerator() || script()->isAsync());
+    MOZ_ASSERT_IF(!script()->isModule(), isFunctionFrame());
+    flags_ |= HAS_INITIAL_ENV;
+    envChain_ = envChain;
+  }
+
+  /*
+   * Other flags
+   */
+
+  bool isConstructing() const { return !!(flags_ & CONSTRUCTING); }
+
+  void setResumedGenerator() { flags_ |= RESUMED_GENERATOR; }
+  bool isResumedGenerator() const { return !!(flags_ & RESUMED_GENERATOR); }
+
+  /*
+   * These two queries should not be used in general: the presence/absence of
+   * the call/args object is determined by the static(ish) properties of the
+   * JSFunction/JSScript. These queries should only be performed when probing
+   * a stack frame that may be in the middle of the prologue (during which
+   * time the call/args object are created).
+   */
+
+  inline bool hasInitialEnvironment() const;
+
+  bool hasInitialEnvironmentUnchecked() const {
+    return flags_ & HAS_INITIAL_ENV;
+  }
+
+  bool hasArgsObj() const {
+    MOZ_ASSERT(script()->needsArgsObj());
+    return flags_ & HAS_ARGS_OBJ;
+  }
+
+  /*
+   * Debugger eval frames.
+   *
+   * - If evalInFramePrev_ is non-null, frame was created for an "eval in
+   *   frame" call, which can push a successor to any live frame; so its
+   *   logical "prev" frame is not necessarily the previous frame in memory.
+   *   Iteration should treat evalInFramePrev_ as this frame's previous frame.
+   *
+   * - Don't bother to JIT it, because it's probably short-lived.
+   *
+   * - It is required to have a environment chain object outside the
+   *   js::EnvironmentObject hierarchy: either a global object, or a
+   *   DebugEnvironmentProxy.
+   */
+  bool isDebuggerEvalFrame() const {
+    return isEvalFrame() && !!evalInFramePrev_;
+  }
+
+  bool prevUpToDate() const { return !!(flags_ & PREV_UP_TO_DATE); }
+
+  void setPrevUpToDate() { flags_ |= PREV_UP_TO_DATE; }
+
+  void unsetPrevUpToDate() { flags_ &= ~PREV_UP_TO_DATE; }
+
+  bool isDebuggee() const { return !!(flags_ & DEBUGGEE); }
+
+  void setIsDebuggee() { flags_ |= DEBUGGEE; }
+
+  inline void unsetIsDebuggee();
+
+  bool hasCachedSavedFrame() const { return flags_ & HAS_CACHED_SAVED_FRAME; }
+  void setHasCachedSavedFrame() { flags_ |= HAS_CACHED_SAVED_FRAME; }
+  void clearHasCachedSavedFrame() { flags_ &= ~HAS_CACHED_SAVED_FRAME; }
+
+ public:
+  void trace(JSTracer* trc, Value* sp, jsbytecode* pc);
+  void traceValues(JSTracer* trc, unsigned start, unsigned end);
+
+  // Entered Baseline/Ion from the interpreter.
+  bool runningInJit() const { return !!(flags_ & RUNNING_IN_JIT); }
+  void setRunningInJit() { flags_ |= RUNNING_IN_JIT; }
+  void clearRunningInJit() { flags_ &= ~RUNNING_IN_JIT; }
+};
+
+/*****************************************************************************/
+
+class InterpreterRegs {
+ public:
+  Value* sp;
+  jsbytecode* pc;
+
+ private:
+  InterpreterFrame* fp_;
+
+ public:
+  InterpreterFrame* fp() const { return fp_; }
+
+  unsigned stackDepth() const {
+    MOZ_ASSERT(sp >= fp_->base());
+    return sp - fp_->base();
+  }
+
+  Value* spForStackDepth(unsigned depth) const {
+    MOZ_ASSERT(fp_->script()->nfixed() + depth <= fp_->script()->nslots());
+    return fp_->base() + depth;
+  }
+
+  void popInlineFrame() {
+    pc = fp_->prevpc();
+    unsigned spForNewTarget =
+        fp_->isResumedGenerator() ? 0 : fp_->isConstructing();
+    // This code is called when resuming from async and generator code.
+    // In the case of modules, we don't have arguments, so we can't use
+    // numActualArgs, which asserts 'hasArgs'.
+    unsigned nActualArgs = fp_->isModuleFrame() ? 0 : fp_->numActualArgs();
+    sp = fp_->prevsp() - nActualArgs - 1 - spForNewTarget;
+    fp_ = fp_->prev();
+    MOZ_ASSERT(fp_);
+  }
+  void prepareToRun(InterpreterFrame& fp, JSScript* script) {
+    pc = script->code();
+    sp = fp.slots() + script->nfixed();
+    fp_ = &fp;
+  }
+
+  void setToEndOfScript();
+
+  MutableHandleValue stackHandleAt(int i) {
+    return MutableHandleValue::fromMarkedLocation(&sp[i]);
+  }
+
+  HandleValue stackHandleAt(int i) const {
+    return HandleValue::fromMarkedLocation(&sp[i]);
+  }
+
+  friend void GDBTestInitInterpreterRegs(InterpreterRegs&,
+                                         js::InterpreterFrame*, JS::Value*,
+                                         uint8_t*);
+};
+
+/*****************************************************************************/
+
+class InterpreterStack {
+  friend class InterpreterActivation;
+
+  static const size_t DEFAULT_CHUNK_SIZE = 4 * 1024;
+  LifoAlloc allocator_;
+
+  // Number of interpreter frames on the stack, for over-recursion checks.
+  static const size_t MAX_FRAMES = 50 * 1000;
+  static const size_t MAX_FRAMES_TRUSTED = MAX_FRAMES + 1000;
+  size_t frameCount_;
+
+  inline uint8_t* allocateFrame(JSContext* cx, size_t size);
+
+  inline InterpreterFrame* getCallFrame(JSContext* cx, const CallArgs& args,
+                                        HandleScript script,
+                                        MaybeConstruct constructing,
+                                        Value** pargv);
+
+  void releaseFrame(InterpreterFrame* fp) {
+    frameCount_--;
+    allocator_.release(fp->mark_);
+  }
+
+ public:
+  InterpreterStack() : allocator_(DEFAULT_CHUNK_SIZE), frameCount_(0) {}
+
+  ~InterpreterStack() { MOZ_ASSERT(frameCount_ == 0); }
+
+  // For execution of eval, module or global code.
+  InterpreterFrame* pushExecuteFrame(JSContext* cx, HandleScript script,
+                                     HandleObject envChain,
+                                     AbstractFramePtr evalInFrame);
+
+  // Called to invoke a function.
+  InterpreterFrame* pushInvokeFrame(JSContext* cx, const CallArgs& args,
+                                    MaybeConstruct constructing);
+
+  // The interpreter can push light-weight, "inline" frames without entering a
+  // new InterpreterActivation or recursively calling Interpret.
+  bool pushInlineFrame(JSContext* cx, InterpreterRegs& regs,
+                       const CallArgs& args, HandleScript script,
+                       MaybeConstruct constructing);
+
+  void popInlineFrame(InterpreterRegs& regs);
+
+  bool resumeGeneratorCallFrame(JSContext* cx, InterpreterRegs& regs,
+                                HandleFunction callee, HandleObject envChain);
+
+  inline void purge(JSRuntime* rt);
+
+  size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+    return allocator_.sizeOfExcludingThis(mallocSizeOf);
+  }
+};
+
+void TraceInterpreterActivations(JSContext* cx, JSTracer* trc);
+
+/*****************************************************************************/
+
+/** Base class for all function call args. */
+class AnyInvokeArgs : public JS::CallArgs {};
+
+/** Base class for all function construction args. */
+class AnyConstructArgs : public JS::CallArgs {
+  // Only js::Construct (or internal methods that call the qualified CallArgs
+  // versions) should do these things!
+  void setCallee(const Value& v) = delete;
+  void setThis(const Value& v) = delete;
+  MutableHandleValue newTarget() const = delete;
+  MutableHandleValue rval() const = delete;
+};
+
+namespace detail {
+
+/** Function call/construct args of statically-unknown count. */
+template <MaybeConstruct Construct>
+class GenericArgsBase
+    : public std::conditional_t<Construct, AnyConstructArgs, AnyInvokeArgs> {
+ protected:
+  RootedValueVector v_;
+
+  explicit GenericArgsBase(JSContext* cx) : v_(cx) {}
+
+ public:
+  bool init(JSContext* cx, uint64_t argc) {
+    if (argc > ARGS_LENGTH_MAX) {
+      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                                JSMSG_TOO_MANY_ARGUMENTS);
+      return false;
+    }
+
+    // callee, this, arguments[, new.target iff constructing]
+    size_t len = 2 + argc + uint32_t(Construct);
+    MOZ_ASSERT(len > argc);  // no overflow
+    if (!v_.resize(len)) {
+      return false;
+    }
+
+    *static_cast<JS::CallArgs*>(this) = CallArgsFromVp(argc, v_.begin());
+    this->constructing_ = Construct;
+    if (Construct) {
+      this->CallArgs::setThis(MagicValue(JS_IS_CONSTRUCTING));
+    }
+    return true;
+  }
+};
+
+/** Function call/construct args of statically-known count. */
+template <MaybeConstruct Construct, size_t N>
+class FixedArgsBase
+    : public std::conditional_t<Construct, AnyConstructArgs, AnyInvokeArgs> {
+  // Add +1 here to avoid noisy warning on gcc when N=0 (0 <= unsigned).
+  static_assert(N + 1 <= ARGS_LENGTH_MAX + 1, "o/~ too many args o/~");
+
+ protected:
+  JS::RootedValueArray<2 + N + uint32_t(Construct)> v_;
+
+  explicit FixedArgsBase(JSContext* cx) : v_(cx) {
+    *static_cast<JS::CallArgs*>(this) = CallArgsFromVp(N, v_.begin());
+    this->constructing_ = Construct;
+    if (Construct) {
+      this->CallArgs::setThis(MagicValue(JS_IS_CONSTRUCTING));
+    }
+  }
+};
+
+}  // namespace detail
+
+/** Function call args of statically-unknown count. */
+class InvokeArgs : public detail::GenericArgsBase<NO_CONSTRUCT> {
+  using Base = detail::GenericArgsBase<NO_CONSTRUCT>;
+
+ public:
+  explicit InvokeArgs(JSContext* cx) : Base(cx) {}
+};
+
+/** Function call args of statically-unknown count. */
+class InvokeArgsMaybeIgnoresReturnValue
+    : public detail::GenericArgsBase<NO_CONSTRUCT> {
+  using Base = detail::GenericArgsBase<NO_CONSTRUCT>;
+
+ public:
+  explicit InvokeArgsMaybeIgnoresReturnValue(JSContext* cx) : Base(cx) {}
+
+  bool init(JSContext* cx, unsigned argc, bool ignoresReturnValue) {
+    if (!Base::init(cx, argc)) {
+      return false;
+    }
+    this->ignoresReturnValue_ = ignoresReturnValue;
+    return true;
+  }
+};
+
+/** Function call args of statically-known count. */
+template <size_t N>
+class FixedInvokeArgs : public detail::FixedArgsBase<NO_CONSTRUCT, N> {
+  using Base = detail::FixedArgsBase<NO_CONSTRUCT, N>;
+
+ public:
+  explicit FixedInvokeArgs(JSContext* cx) : Base(cx) {}
+};
+
+/** Function construct args of statically-unknown count. */
+class ConstructArgs : public detail::GenericArgsBase<CONSTRUCT> {
+  using Base = detail::GenericArgsBase<CONSTRUCT>;
+
+ public:
+  explicit ConstructArgs(JSContext* cx) : Base(cx) {}
+};
+
+/** Function call args of statically-known count. */
+template <size_t N>
+class FixedConstructArgs : public detail::FixedArgsBase<CONSTRUCT, N> {
+  using Base = detail::FixedArgsBase<CONSTRUCT, N>;
+
+ public:
+  explicit FixedConstructArgs(JSContext* cx) : Base(cx) {}
+};
+
+template <class Args, class Arraylike>
+inline bool FillArgumentsFromArraylike(JSContext* cx, Args& args,
+                                       const Arraylike& arraylike) {
+  uint32_t len = arraylike.length();
+  if (!args.init(cx, len)) {
+    return false;
+  }
+
+  for (uint32_t i = 0; i < len; i++) {
+    args[i].set(arraylike[i]);
+  }
+
+  return true;
+}
+
+}  // namespace js
+
+namespace mozilla {
+
+template <>
+struct DefaultHasher<js::AbstractFramePtr> {
+  using Lookup = js::AbstractFramePtr;
+
+  static js::HashNumber hash(const Lookup& key) {
+    return mozilla::HashGeneric(key.raw());
+  }
+
+  static bool match(const js::AbstractFramePtr& k, const Lookup& l) {
+    return k == l;
+  }
+};
+
+}  // namespace mozilla
+
+#endif  // vm_Stack_h