diff -r 000000000000 -r 6474c204b198 js/src/jsscript.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jsscript.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,3869 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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/. */
+
+/*
+ * JS script operations.
+ */
+
+#include "jsscriptinlines.h"
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/PodOperations.h"
+
+#include <string.h>
+
+#include "jsapi.h"
+#include "jsatom.h"
+#include "jscntxt.h"
+#include "jsfun.h"
+#include "jsgc.h"
+#include "jsobj.h"
+#include "jsopcode.h"
+#include "jsprf.h"
+#include "jstypes.h"
+#include "jsutil.h"
+#include "jswrapper.h"
+
+#include "frontend/BytecodeCompiler.h"
+#include "frontend/BytecodeEmitter.h"
+#include "frontend/SharedContext.h"
+#include "gc/Marking.h"
+#include "jit/BaselineJIT.h"
+#include "jit/IonCode.h"
+#include "js/MemoryMetrics.h"
+#include "js/OldDebugAPI.h"
+#include "js/Utility.h"
+#include "vm/ArgumentsObject.h"
+#include "vm/Compression.h"
+#include "vm/Debugger.h"
+#include "vm/Opcodes.h"
+#include "vm/SelfHosting.h"
+#include "vm/Shape.h"
+#include "vm/Xdr.h"
+
+#include "jsfuninlines.h"
+#include "jsinferinlines.h"
+#include "jsobjinlines.h"
+
+#include "vm/ScopeObject-inl.h"
+#include "vm/Stack-inl.h"
+
+using namespace js;
+using namespace js::gc;
+using namespace js::frontend;
+
+using mozilla::PodCopy;
+using mozilla::PodZero;
+using mozilla::RotateLeft;
+
+typedef Rooted<GlobalObject *> RootedGlobalObject;
+
+/* static */ uint32_t
+Bindings::argumentsVarIndex(ExclusiveContext *cx, InternalBindingsHandle bindings)
+{
+    HandlePropertyName arguments = cx->names().arguments;
+    BindingIter bi(bindings);
+    while (bi->name() != arguments)
+        bi++;
+    return bi.frameIndex();
+}
+
+bool
+Bindings::initWithTemporaryStorage(ExclusiveContext *cx, InternalBindingsHandle self,
+                                   unsigned numArgs, uint32_t numVars,
+                                   Binding *bindingArray, uint32_t numBlockScoped)
+{
+    JS_ASSERT(!self->callObjShape_);
+    JS_ASSERT(self->bindingArrayAndFlag_ == TEMPORARY_STORAGE_BIT);
+    JS_ASSERT(!(uintptr_t(bindingArray) & TEMPORARY_STORAGE_BIT));
+    JS_ASSERT(numArgs <= ARGC_LIMIT);
+    JS_ASSERT(numVars <= LOCALNO_LIMIT);
+    JS_ASSERT(numBlockScoped <= LOCALNO_LIMIT);
+    JS_ASSERT(numVars <= LOCALNO_LIMIT - numBlockScoped);
+    JS_ASSERT(UINT32_MAX - numArgs >= numVars + numBlockScoped);
+
+    self->bindingArrayAndFlag_ = uintptr_t(bindingArray) | TEMPORARY_STORAGE_BIT;
+    self->numArgs_ = numArgs;
+    self->numVars_ = numVars;
+    self->numBlockScoped_ = numBlockScoped;
+
+    // Get the initial shape to use when creating CallObjects for this script.
+    // After creation, a CallObject's shape may change completely (via direct eval() or
+    // other operations that mutate the lexical scope). However, since the
+    // lexical bindings added to the initial shape are permanent and the
+    // allocKind/nfixed of a CallObject cannot change, one may assume that the
+    // slot location (whether in the fixed or dynamic slots) of a variable is
+    // the same as in the initial shape. (This is assumed by the interpreter and
+    // JITs when interpreting/compiling aliasedvar ops.)
+
+    // Since unaliased variables are, by definition, only accessed by local
+    // operations and never through the scope chain, only give shapes to
+    // aliased variables. While the debugger may observe any scope object at
+    // any time, such accesses are mediated by DebugScopeProxy (see
+    // DebugScopeProxy::handleUnaliasedAccess).
+    uint32_t nslots = CallObject::RESERVED_SLOTS;
+    for (BindingIter bi(self); bi; bi++) {
+        if (bi->aliased())
+            nslots++;
+    }
+
+    // Put as many of nslots inline into the object header as possible.
+    uint32_t nfixed = gc::GetGCKindSlots(gc::GetGCObjectKind(nslots));
+
+    // Start with the empty shape and then append one shape per aliased binding.
+    RootedShape shape(cx,
+        EmptyShape::getInitialShape(cx, &CallObject::class_, nullptr, nullptr, nullptr,
+                                    nfixed, BaseShape::VAROBJ | BaseShape::DELEGATE));
+    if (!shape)
+        return false;
+
+#ifdef DEBUG
+    HashSet<PropertyName *> added(cx);
+    if (!added.init())
+        return false;
+#endif
+
+    uint32_t slot = CallObject::RESERVED_SLOTS;
+    for (BindingIter bi(self); bi; bi++) {
+        if (!bi->aliased())
+            continue;
+
+#ifdef DEBUG
+        // The caller ensures no duplicate aliased names.
+        JS_ASSERT(!added.has(bi->name()));
+        if (!added.put(bi->name()))
+            return false;
+#endif
+
+        StackBaseShape stackBase(cx, &CallObject::class_, nullptr, nullptr,
+                                 BaseShape::VAROBJ | BaseShape::DELEGATE);
+
+        UnownedBaseShape *base = BaseShape::getUnowned(cx, stackBase);
+        if (!base)
+            return false;
+
+        unsigned attrs = JSPROP_PERMANENT |
+                         JSPROP_ENUMERATE |
+                         (bi->kind() == Binding::CONSTANT ? JSPROP_READONLY : 0);
+        StackShape child(base, NameToId(bi->name()), slot, attrs, 0);
+
+        shape = cx->compartment()->propertyTree.getChild(cx, shape, child);
+        if (!shape)
+            return false;
+
+        JS_ASSERT(slot < nslots);
+        slot++;
+    }
+    JS_ASSERT(slot == nslots);
+
+    JS_ASSERT(!shape->inDictionary());
+    self->callObjShape_.init(shape);
+    return true;
+}
+
+uint8_t *
+Bindings::switchToScriptStorage(Binding *newBindingArray)
+{
+    JS_ASSERT(bindingArrayUsingTemporaryStorage());
+    JS_ASSERT(!(uintptr_t(newBindingArray) & TEMPORARY_STORAGE_BIT));
+
+    if (count() > 0)
+        PodCopy(newBindingArray, bindingArray(), count());
+    bindingArrayAndFlag_ = uintptr_t(newBindingArray);
+    return reinterpret_cast<uint8_t *>(newBindingArray + count());
+}
+
+bool
+Bindings::clone(JSContext *cx, InternalBindingsHandle self,
+                uint8_t *dstScriptData, HandleScript srcScript)
+{
+    /* The clone has the same bindingArray_ offset as 'src'. */
+    Bindings &src = srcScript->bindings;
+    ptrdiff_t off = (uint8_t *)src.bindingArray() - srcScript->data;
+    JS_ASSERT(off >= 0);
+    JS_ASSERT(size_t(off) <= srcScript->dataSize());
+    Binding *dstPackedBindings = (Binding *)(dstScriptData + off);
+
+    /*
+     * Since atoms are shareable throughout the runtime, we can simply copy
+     * the source's bindingArray directly.
+     */
+    if (!initWithTemporaryStorage(cx, self, src.numArgs(), src.numVars(), src.bindingArray(),
+                                  src.numBlockScoped()))
+        return false;
+    self->switchToScriptStorage(dstPackedBindings);
+    return true;
+}
+
+/* static */ Bindings
+GCMethods<Bindings>::initial()
+{
+    return Bindings();
+}
+
+template<XDRMode mode>
+static bool
+XDRScriptBindings(XDRState<mode> *xdr, LifoAllocScope &las, unsigned numArgs, uint32_t numVars,
+                  HandleScript script, unsigned numBlockScoped)
+{
+    JSContext *cx = xdr->cx();
+
+    if (mode == XDR_ENCODE) {
+        for (BindingIter bi(script); bi; bi++) {
+            RootedAtom atom(cx, bi->name());
+            if (!XDRAtom(xdr, &atom))
+                return false;
+        }
+
+        for (BindingIter bi(script); bi; bi++) {
+            uint8_t u8 = (uint8_t(bi->kind()) << 1) | uint8_t(bi->aliased());
+            if (!xdr->codeUint8(&u8))
+                return false;
+        }
+    } else {
+        uint32_t nameCount = numArgs + numVars;
+
+        AutoValueVector atoms(cx);
+        if (!atoms.resize(nameCount))
+            return false;
+        for (uint32_t i = 0; i < nameCount; i++) {
+            RootedAtom atom(cx);
+            if (!XDRAtom(xdr, &atom))
+                return false;
+            atoms[i] = StringValue(atom);
+        }
+
+        Binding *bindingArray = las.alloc().newArrayUninitialized<Binding>(nameCount);
+        if (!bindingArray)
+            return false;
+        for (uint32_t i = 0; i < nameCount; i++) {
+            uint8_t u8;
+            if (!xdr->codeUint8(&u8))
+                return false;
+
+            PropertyName *name = atoms[i].toString()->asAtom().asPropertyName();
+            Binding::Kind kind = Binding::Kind(u8 >> 1);
+            bool aliased = bool(u8 & 1);
+
+            bindingArray[i] = Binding(name, kind, aliased);
+        }
+
+        InternalBindingsHandle bindings(script, &script->bindings);
+        if (!Bindings::initWithTemporaryStorage(cx, bindings, numArgs, numVars, bindingArray,
+                                                numBlockScoped))
+            return false;
+    }
+
+    return true;
+}
+
+bool
+Bindings::bindingIsAliased(uint32_t bindingIndex)
+{
+    JS_ASSERT(bindingIndex < count());
+    return bindingArray()[bindingIndex].aliased();
+}
+
+void
+Bindings::trace(JSTracer *trc)
+{
+    if (callObjShape_)
+        MarkShape(trc, &callObjShape_, "callObjShape");
+
+    /*
+     * As the comment in Bindings explains, bindingsArray may point into freed
+     * storage when bindingArrayUsingTemporaryStorage so we don't mark it.
+     * Note: during compilation, atoms are already kept alive by gcKeepAtoms.
+     */
+    if (bindingArrayUsingTemporaryStorage())
+        return;
+
+    for (Binding *b = bindingArray(), *end = b + count(); b != end; b++) {
+        PropertyName *name = b->name();
+        MarkStringUnbarriered(trc, &name, "bindingArray");
+    }
+}
+
+bool
+js::FillBindingVector(HandleScript fromScript, BindingVector *vec)
+{
+    for (BindingIter bi(fromScript); bi; bi++) {
+        if (!vec->append(*bi))
+            return false;
+    }
+
+    return true;
+}
+
+template<XDRMode mode>
+bool
+js::XDRScriptConst(XDRState<mode> *xdr, MutableHandleValue vp)
+{
+    JSContext *cx = xdr->cx();
+
+    /*
+     * A script constant can be an arbitrary primitive value as they are used
+     * to implement JSOP_LOOKUPSWITCH. But they cannot be objects, see
+     * bug 407186.
+     */
+    enum ConstTag {
+        SCRIPT_INT     = 0,
+        SCRIPT_DOUBLE  = 1,
+        SCRIPT_ATOM    = 2,
+        SCRIPT_TRUE    = 3,
+        SCRIPT_FALSE   = 4,
+        SCRIPT_NULL    = 5,
+        SCRIPT_OBJECT  = 6,
+        SCRIPT_VOID    = 7,
+        SCRIPT_HOLE    = 8
+    };
+
+    uint32_t tag;
+    if (mode == XDR_ENCODE) {
+        if (vp.isInt32()) {
+            tag = SCRIPT_INT;
+        } else if (vp.isDouble()) {
+            tag = SCRIPT_DOUBLE;
+        } else if (vp.isString()) {
+            tag = SCRIPT_ATOM;
+        } else if (vp.isTrue()) {
+            tag = SCRIPT_TRUE;
+        } else if (vp.isFalse()) {
+            tag = SCRIPT_FALSE;
+        } else if (vp.isNull()) {
+            tag = SCRIPT_NULL;
+        } else if (vp.isObject()) {
+            tag = SCRIPT_OBJECT;
+        } else if (vp.isMagic(JS_ELEMENTS_HOLE)) {
+            tag = SCRIPT_HOLE;
+        } else {
+            JS_ASSERT(vp.isUndefined());
+            tag = SCRIPT_VOID;
+        }
+    }
+
+    if (!xdr->codeUint32(&tag))
+        return false;
+
+    switch (tag) {
+      case SCRIPT_INT: {
+        uint32_t i;
+        if (mode == XDR_ENCODE)
+            i = uint32_t(vp.toInt32());
+        if (!xdr->codeUint32(&i))
+            return false;
+        if (mode == XDR_DECODE)
+            vp.set(Int32Value(int32_t(i)));
+        break;
+      }
+      case SCRIPT_DOUBLE: {
+        double d;
+        if (mode == XDR_ENCODE)
+            d = vp.toDouble();
+        if (!xdr->codeDouble(&d))
+            return false;
+        if (mode == XDR_DECODE)
+            vp.set(DoubleValue(d));
+        break;
+      }
+      case SCRIPT_ATOM: {
+        RootedAtom atom(cx);
+        if (mode == XDR_ENCODE)
+            atom = &vp.toString()->asAtom();
+        if (!XDRAtom(xdr, &atom))
+            return false;
+        if (mode == XDR_DECODE)
+            vp.set(StringValue(atom));
+        break;
+      }
+      case SCRIPT_TRUE:
+        if (mode == XDR_DECODE)
+            vp.set(BooleanValue(true));
+        break;
+      case SCRIPT_FALSE:
+        if (mode == XDR_DECODE)
+            vp.set(BooleanValue(false));
+        break;
+      case SCRIPT_NULL:
+        if (mode == XDR_DECODE)
+            vp.set(NullValue());
+        break;
+      case SCRIPT_OBJECT: {
+        RootedObject obj(cx);
+        if (mode == XDR_ENCODE)
+            obj = &vp.toObject();
+
+        if (!XDRObjectLiteral(xdr, &obj))
+            return false;
+
+        if (mode == XDR_DECODE)
+            vp.setObject(*obj);
+        break;
+      }
+      case SCRIPT_VOID:
+        if (mode == XDR_DECODE)
+            vp.set(UndefinedValue());
+        break;
+      case SCRIPT_HOLE:
+        if (mode == XDR_DECODE)
+            vp.setMagic(JS_ELEMENTS_HOLE);
+        break;
+    }
+    return true;
+}
+
+template bool
+js::XDRScriptConst(XDRState<XDR_ENCODE> *, MutableHandleValue);
+
+template bool
+js::XDRScriptConst(XDRState<XDR_DECODE> *, MutableHandleValue);
+
+// Code LazyScript's free variables.
+template<XDRMode mode>
+static bool
+XDRLazyFreeVariables(XDRState<mode> *xdr, MutableHandle<LazyScript *> lazy)
+{
+    JSContext *cx = xdr->cx();
+    RootedAtom atom(cx);
+    HeapPtrAtom *freeVariables = lazy->freeVariables();
+    size_t numFreeVariables = lazy->numFreeVariables();
+    for (size_t i = 0; i < numFreeVariables; i++) {
+        if (mode == XDR_ENCODE)
+            atom = freeVariables[i];
+
+        if (!XDRAtom(xdr, &atom))
+            return false;
+
+        if (mode == XDR_DECODE)
+            freeVariables[i] = atom;
+    }
+
+    return true;
+}
+
+// Code the missing part needed to re-create a LazyScript from a JSScript.
+template<XDRMode mode>
+static bool
+XDRRelazificationInfo(XDRState<mode> *xdr, HandleFunction fun, HandleScript script,
+                      MutableHandle<LazyScript *> lazy)
+{
+    MOZ_ASSERT_IF(mode == XDR_ENCODE, script->isRelazifiable() && script->maybeLazyScript());
+    MOZ_ASSERT_IF(mode == XDR_ENCODE, !lazy->numInnerFunctions());
+
+    JSContext *cx = xdr->cx();
+
+    uint64_t packedFields;
+    {
+        uint32_t begin = script->sourceStart();
+        uint32_t end = script->sourceEnd();
+        uint32_t lineno = script->lineno();
+        uint32_t column = script->column();
+
+        if (mode == XDR_ENCODE) {
+            packedFields = lazy->packedFields();
+            MOZ_ASSERT(begin == lazy->begin());
+            MOZ_ASSERT(end == lazy->end());
+            MOZ_ASSERT(lineno == lazy->lineno());
+            MOZ_ASSERT(column == lazy->column());
+        }
+
+        if (!xdr->codeUint64(&packedFields))
+            return false;
+
+        if (mode == XDR_DECODE) {
+            lazy.set(LazyScript::Create(cx, fun, packedFields, begin, end, lineno, column));
+
+            // As opposed to XDRLazyScript, we need to restore the runtime bits
+            // of the script, as we are trying to match the fact this function
+            // has already been parsed and that it would need to be re-lazified.
+            lazy->initRuntimeFields(packedFields);
+        }
+    }
+
+    // Code free variables.
+    if (!XDRLazyFreeVariables(xdr, lazy))
+        return false;
+
+    return true;
+}
+
+static inline uint32_t
+FindScopeObjectIndex(JSScript *script, NestedScopeObject &scope)
+{
+    ObjectArray *objects = script->objects();
+    HeapPtrObject *vector = objects->vector;
+    unsigned length = objects->length;
+    for (unsigned i = 0; i < length; ++i) {
+        if (vector[i] == &scope)
+            return i;
+    }
+
+    MOZ_ASSUME_UNREACHABLE("Scope not found");
+}
+
+static bool
+SaveSharedScriptData(ExclusiveContext *, Handle<JSScript *>, SharedScriptData *, uint32_t);
+
+enum XDRClassKind {
+    CK_BlockObject = 0,
+    CK_WithObject  = 1,
+    CK_JSFunction  = 2,
+    CK_JSObject    = 3
+};
+
+template<XDRMode mode>
+bool
+js::XDRScript(XDRState<mode> *xdr, HandleObject enclosingScope, HandleScript enclosingScript,
+              HandleFunction fun, MutableHandleScript scriptp)
+{
+    /* NB: Keep this in sync with CloneScript. */
+
+    enum ScriptBits {
+        NoScriptRval,
+        SavedCallerFun,
+        Strict,
+        ContainsDynamicNameAccess,
+        FunHasExtensibleScope,
+        FunNeedsDeclEnvObject,
+        FunHasAnyAliasedFormal,
+        ArgumentsHasVarBinding,
+        NeedsArgsObj,
+        IsGeneratorExp,
+        IsLegacyGenerator,
+        IsStarGenerator,
+        OwnSource,
+        ExplicitUseStrict,
+        SelfHosted,
+        IsCompileAndGo,
+        HasSingleton,
+        TreatAsRunOnce,
+        HasLazyScript
+    };
+
+    uint32_t length, lineno, column, nslots, staticLevel;
+    uint32_t natoms, nsrcnotes, i;
+    uint32_t nconsts, nobjects, nregexps, ntrynotes, nblockscopes;
+    uint32_t prologLength, version;
+    uint32_t funLength = 0;
+    uint32_t nTypeSets = 0;
+    uint32_t scriptBits = 0;
+
+    JSContext *cx = xdr->cx();
+    RootedScript script(cx);
+    natoms = nsrcnotes = 0;
+    nconsts = nobjects = nregexps = ntrynotes = nblockscopes = 0;
+
+    /* XDR arguments and vars. */
+    uint16_t nargs = 0;
+    uint16_t nblocklocals = 0;
+    uint32_t nvars = 0;
+    if (mode == XDR_ENCODE) {
+        script = scriptp.get();
+        JS_ASSERT_IF(enclosingScript, enclosingScript->compartment() == script->compartment());
+
+        nargs = script->bindings.numArgs();
+        nblocklocals = script->bindings.numBlockScoped();
+        nvars = script->bindings.numVars();
+    }
+    if (!xdr->codeUint16(&nargs))
+        return false;
+    if (!xdr->codeUint16(&nblocklocals))
+        return false;
+    if (!xdr->codeUint32(&nvars))
+        return false;
+
+    if (mode == XDR_ENCODE)
+        length = script->length();
+    if (!xdr->codeUint32(&length))
+        return false;
+
+    if (mode == XDR_ENCODE) {
+        prologLength = script->mainOffset();
+        JS_ASSERT(script->getVersion() != JSVERSION_UNKNOWN);
+        version = script->getVersion();
+        lineno = script->lineno();
+        column = script->column();
+        nslots = script->nslots();
+        staticLevel = script->staticLevel();
+        natoms = script->natoms();
+
+        nsrcnotes = script->numNotes();
+
+        if (script->hasConsts())
+            nconsts = script->consts()->length;
+        if (script->hasObjects())
+            nobjects = script->objects()->length;
+        if (script->hasRegexps())
+            nregexps = script->regexps()->length;
+        if (script->hasTrynotes())
+            ntrynotes = script->trynotes()->length;
+        if (script->hasBlockScopes())
+            nblockscopes = script->blockScopes()->length;
+
+        nTypeSets = script->nTypeSets();
+        funLength = script->funLength();
+
+        if (script->noScriptRval())
+            scriptBits |= (1 << NoScriptRval);
+        if (script->savedCallerFun())
+            scriptBits |= (1 << SavedCallerFun);
+        if (script->strict())
+            scriptBits |= (1 << Strict);
+        if (script->explicitUseStrict())
+            scriptBits |= (1 << ExplicitUseStrict);
+        if (script->selfHosted())
+            scriptBits |= (1 << SelfHosted);
+        if (script->bindingsAccessedDynamically())
+            scriptBits |= (1 << ContainsDynamicNameAccess);
+        if (script->funHasExtensibleScope())
+            scriptBits |= (1 << FunHasExtensibleScope);
+        if (script->funNeedsDeclEnvObject())
+            scriptBits |= (1 << FunNeedsDeclEnvObject);
+        if (script->funHasAnyAliasedFormal())
+            scriptBits |= (1 << FunHasAnyAliasedFormal);
+        if (script->argumentsHasVarBinding())
+            scriptBits |= (1 << ArgumentsHasVarBinding);
+        if (script->analyzedArgsUsage() && script->needsArgsObj())
+            scriptBits |= (1 << NeedsArgsObj);
+        if (!enclosingScript || enclosingScript->scriptSource() != script->scriptSource())
+            scriptBits |= (1 << OwnSource);
+        if (script->isGeneratorExp())
+            scriptBits |= (1 << IsGeneratorExp);
+        if (script->isLegacyGenerator())
+            scriptBits |= (1 << IsLegacyGenerator);
+        if (script->isStarGenerator())
+            scriptBits |= (1 << IsStarGenerator);
+        if (script->compileAndGo())
+            scriptBits |= (1 << IsCompileAndGo);
+        if (script->hasSingletons())
+            scriptBits |= (1 << HasSingleton);
+        if (script->treatAsRunOnce())
+            scriptBits |= (1 << TreatAsRunOnce);
+        if (script->isRelazifiable())
+            scriptBits |= (1 << HasLazyScript);
+    }
+
+    if (!xdr->codeUint32(&prologLength))
+        return false;
+    if (!xdr->codeUint32(&version))
+        return false;
+
+    // To fuse allocations, we need lengths of all embedded arrays early.
+    if (!xdr->codeUint32(&natoms))
+        return false;
+    if (!xdr->codeUint32(&nsrcnotes))
+        return false;
+    if (!xdr->codeUint32(&nconsts))
+        return false;
+    if (!xdr->codeUint32(&nobjects))
+        return false;
+    if (!xdr->codeUint32(&nregexps))
+        return false;
+    if (!xdr->codeUint32(&ntrynotes))
+        return false;
+    if (!xdr->codeUint32(&nblockscopes))
+        return false;
+    if (!xdr->codeUint32(&nTypeSets))
+        return false;
+    if (!xdr->codeUint32(&funLength))
+        return false;
+    if (!xdr->codeUint32(&scriptBits))
+        return false;
+
+    if (mode == XDR_DECODE) {
+        JSVersion version_ = JSVersion(version);
+        JS_ASSERT((version_ & VersionFlags::MASK) == unsigned(version_));
+
+        // staticLevel is set below.
+        CompileOptions options(cx);
+        options.setVersion(version_)
+               .setNoScriptRval(!!(scriptBits & (1 << NoScriptRval)))
+               .setSelfHostingMode(!!(scriptBits & (1 << SelfHosted)));
+        RootedScriptSource sourceObject(cx);
+        if (scriptBits & (1 << OwnSource)) {
+            ScriptSource *ss = cx->new_<ScriptSource>();
+            if (!ss)
+                return false;
+            ScriptSourceHolder ssHolder(ss);
+
+            /*
+             * We use this CompileOptions only to initialize the
+             * ScriptSourceObject. Most CompileOptions fields aren't used by
+             * ScriptSourceObject, and those that are (element; elementAttributeName)
+             * aren't preserved by XDR. So this can be simple.
+             */
+            CompileOptions options(cx);
+            options.setOriginPrincipals(xdr->originPrincipals());
+            ss->initFromOptions(cx, options);
+            sourceObject = ScriptSourceObject::create(cx, ss, options);
+            if (!sourceObject)
+                return false;
+        } else {
+            JS_ASSERT(enclosingScript);
+            // When decoding, all the scripts and the script source object
+            // are in the same compartment, so the script's source object
+            // should never be a cross-compartment wrapper.
+            JS_ASSERT(enclosingScript->sourceObject()->is<ScriptSourceObject>());
+            sourceObject = &enclosingScript->sourceObject()->as<ScriptSourceObject>();
+        }
+        script = JSScript::Create(cx, enclosingScope, !!(scriptBits & (1 << SavedCallerFun)),
+                                  options, /* staticLevel = */ 0, sourceObject, 0, 0);
+        if (!script)
+            return false;
+    }
+
+    /* JSScript::partiallyInit assumes script->bindings is fully initialized. */
+    LifoAllocScope las(&cx->tempLifoAlloc());
+    if (!XDRScriptBindings(xdr, las, nargs, nvars, script, nblocklocals))
+        return false;
+
+    if (mode == XDR_DECODE) {
+        if (!JSScript::partiallyInit(cx, script, nconsts, nobjects, nregexps, ntrynotes,
+                                     nblockscopes, nTypeSets))
+        {
+            return false;
+        }
+
+        JS_ASSERT(!script->mainOffset());
+        script->mainOffset_ = prologLength;
+        script->setLength(length);
+        script->funLength_ = funLength;
+
+        scriptp.set(script);
+
+        if (scriptBits & (1 << Strict))
+            script->strict_ = true;
+        if (scriptBits & (1 << ExplicitUseStrict))
+            script->explicitUseStrict_ = true;
+        if (scriptBits & (1 << ContainsDynamicNameAccess))
+            script->bindingsAccessedDynamically_ = true;
+        if (scriptBits & (1 << FunHasExtensibleScope))
+            script->funHasExtensibleScope_ = true;
+        if (scriptBits & (1 << FunNeedsDeclEnvObject))
+            script->funNeedsDeclEnvObject_ = true;
+        if (scriptBits & (1 << FunHasAnyAliasedFormal))
+            script->funHasAnyAliasedFormal_ = true;
+        if (scriptBits & (1 << ArgumentsHasVarBinding))
+            script->setArgumentsHasVarBinding();
+        if (scriptBits & (1 << NeedsArgsObj))
+            script->setNeedsArgsObj(true);
+        if (scriptBits & (1 << IsGeneratorExp))
+            script->isGeneratorExp_ = true;
+        if (scriptBits & (1 << IsCompileAndGo))
+            script->compileAndGo_ = true;
+        if (scriptBits & (1 << HasSingleton))
+            script->hasSingletons_ = true;
+        if (scriptBits & (1 << TreatAsRunOnce))
+            script->treatAsRunOnce_ = true;
+
+        if (scriptBits & (1 << IsLegacyGenerator)) {
+            JS_ASSERT(!(scriptBits & (1 << IsStarGenerator)));
+            script->setGeneratorKind(LegacyGenerator);
+        } else if (scriptBits & (1 << IsStarGenerator))
+            script->setGeneratorKind(StarGenerator);
+    }
+
+    JS_STATIC_ASSERT(sizeof(jsbytecode) == 1);
+    JS_STATIC_ASSERT(sizeof(jssrcnote) == 1);
+
+    if (scriptBits & (1 << OwnSource)) {
+        if (!script->scriptSource()->performXDR<mode>(xdr))
+            return false;
+    }
+    if (!xdr->codeUint32(&script->sourceStart_))
+        return false;
+    if (!xdr->codeUint32(&script->sourceEnd_))
+        return false;
+
+    if (!xdr->codeUint32(&lineno) ||
+        !xdr->codeUint32(&column) ||
+        !xdr->codeUint32(&nslots) ||
+        !xdr->codeUint32(&staticLevel))
+    {
+        return false;
+    }
+
+    if (mode == XDR_DECODE) {
+        script->lineno_ = lineno;
+        script->column_ = column;
+        script->nslots_ = nslots;
+        script->staticLevel_ = staticLevel;
+    }
+
+    jsbytecode *code = script->code();
+    SharedScriptData *ssd;
+    if (mode == XDR_DECODE) {
+        ssd = SharedScriptData::new_(cx, length, nsrcnotes, natoms);
+        if (!ssd)
+            return false;
+        code = ssd->data;
+        if (natoms != 0) {
+            script->natoms_ = natoms;
+            script->atoms = ssd->atoms();
+        }
+    }
+
+    if (!xdr->codeBytes(code, length) || !xdr->codeBytes(code + length, nsrcnotes)) {
+        if (mode == XDR_DECODE)
+            js_free(ssd);
+        return false;
+    }
+
+    for (i = 0; i != natoms; ++i) {
+        if (mode == XDR_DECODE) {
+            RootedAtom tmp(cx);
+            if (!XDRAtom(xdr, &tmp))
+                return false;
+            script->atoms[i].init(tmp);
+        } else {
+            RootedAtom tmp(cx, script->atoms[i]);
+            if (!XDRAtom(xdr, &tmp))
+                return false;
+        }
+    }
+
+    if (mode == XDR_DECODE) {
+        if (!SaveSharedScriptData(cx, script, ssd, nsrcnotes))
+            return false;
+    }
+
+    if (nconsts) {
+        HeapValue *vector = script->consts()->vector;
+        RootedValue val(cx);
+        for (i = 0; i != nconsts; ++i) {
+            if (mode == XDR_ENCODE)
+                val = vector[i];
+            if (!XDRScriptConst(xdr, &val))
+                return false;
+            if (mode == XDR_DECODE)
+                vector[i].init(val);
+        }
+    }
+
+    /*
+     * Here looping from 0-to-length to xdr objects is essential to ensure that
+     * all references to enclosing blocks (via FindScopeObjectIndex below) happen
+     * after the enclosing block has been XDR'd.
+     */
+    for (i = 0; i != nobjects; ++i) {
+        HeapPtr<JSObject> *objp = &script->objects()->vector[i];
+        XDRClassKind classk;
+
+        if (mode == XDR_ENCODE) {
+            JSObject *obj = *objp;
+            if (obj->is<BlockObject>())
+                classk = CK_BlockObject;
+            else if (obj->is<StaticWithObject>())
+                classk = CK_WithObject;
+            else if (obj->is<JSFunction>())
+                classk = CK_JSFunction;
+            else if (obj->is<JSObject>() || obj->is<ArrayObject>())
+                classk = CK_JSObject;
+            else
+                MOZ_ASSUME_UNREACHABLE("Cannot encode this class of object.");
+        }
+
+        if (!xdr->codeEnum32(&classk))
+            return false;
+
+        switch (classk) {
+          case CK_BlockObject:
+          case CK_WithObject: {
+            /* Code the nested block's enclosing scope. */
+            uint32_t enclosingStaticScopeIndex = 0;
+            if (mode == XDR_ENCODE) {
+                NestedScopeObject &scope = (*objp)->as<NestedScopeObject>();
+                if (NestedScopeObject *enclosing = scope.enclosingNestedScope())
+                    enclosingStaticScopeIndex = FindScopeObjectIndex(script, *enclosing);
+                else
+                    enclosingStaticScopeIndex = UINT32_MAX;
+            }
+            if (!xdr->codeUint32(&enclosingStaticScopeIndex))
+                return false;
+            Rooted<JSObject*> enclosingStaticScope(cx);
+            if (mode == XDR_DECODE) {
+                if (enclosingStaticScopeIndex != UINT32_MAX) {
+                    JS_ASSERT(enclosingStaticScopeIndex < i);
+                    enclosingStaticScope = script->objects()->vector[enclosingStaticScopeIndex];
+                } else {
+                    enclosingStaticScope = fun;
+                }
+            }
+
+            if (classk == CK_BlockObject) {
+                Rooted<StaticBlockObject*> tmp(cx, static_cast<StaticBlockObject *>(objp->get()));
+                if (!XDRStaticBlockObject(xdr, enclosingStaticScope, tmp.address()))
+                    return false;
+                *objp = tmp;
+            } else {
+                Rooted<StaticWithObject*> tmp(cx, static_cast<StaticWithObject *>(objp->get()));
+                if (!XDRStaticWithObject(xdr, enclosingStaticScope, tmp.address()))
+                    return false;
+                *objp = tmp;
+            }
+            break;
+          }
+
+          case CK_JSFunction: {
+            /* Code the nested function's enclosing scope. */
+            uint32_t funEnclosingScopeIndex = 0;
+            RootedObject funEnclosingScope(cx);
+            if (mode == XDR_ENCODE) {
+                RootedFunction function(cx, &(*objp)->as<JSFunction>());
+
+                if (function->isInterpretedLazy())
+                    funEnclosingScope = function->lazyScript()->enclosingScope();
+                else
+                    funEnclosingScope = function->nonLazyScript()->enclosingStaticScope();
+
+                StaticScopeIter<NoGC> ssi(funEnclosingScope);
+                if (ssi.done() || ssi.type() == StaticScopeIter<NoGC>::FUNCTION) {
+                    JS_ASSERT(ssi.done() == !fun);
+                    funEnclosingScopeIndex = UINT32_MAX;
+                } else if (ssi.type() == StaticScopeIter<NoGC>::BLOCK) {
+                    funEnclosingScopeIndex = FindScopeObjectIndex(script, ssi.block());
+                    JS_ASSERT(funEnclosingScopeIndex < i);
+                } else {
+                    funEnclosingScopeIndex = FindScopeObjectIndex(script, ssi.staticWith());
+                    JS_ASSERT(funEnclosingScopeIndex < i);
+                }
+            }
+
+            if (!xdr->codeUint32(&funEnclosingScopeIndex))
+                return false;
+
+            if (mode == XDR_DECODE) {
+                if (funEnclosingScopeIndex == UINT32_MAX) {
+                    funEnclosingScope = fun;
+                } else {
+                    JS_ASSERT(funEnclosingScopeIndex < i);
+                    funEnclosingScope = script->objects()->vector[funEnclosingScopeIndex];
+                }
+            }
+
+            // Code nested function and script.
+            RootedObject tmp(cx, *objp);
+            if (!XDRInterpretedFunction(xdr, funEnclosingScope, script, &tmp))
+                return false;
+            *objp = tmp;
+            break;
+          }
+
+          case CK_JSObject: {
+            /* Code object literal. */
+            RootedObject tmp(cx, *objp);
+            if (!XDRObjectLiteral(xdr, &tmp))
+                return false;
+            *objp = tmp;
+            break;
+          }
+
+          default: {
+            MOZ_ASSERT(false, "Unknown class kind.");
+            return false;
+          }
+        }
+    }
+
+    for (i = 0; i != nregexps; ++i) {
+        if (!XDRScriptRegExpObject(xdr, &script->regexps()->vector[i]))
+            return false;
+    }
+
+    if (ntrynotes != 0) {
+        JSTryNote *tnfirst = script->trynotes()->vector;
+        JS_ASSERT(script->trynotes()->length == ntrynotes);
+        JSTryNote *tn = tnfirst + ntrynotes;
+        do {
+            --tn;
+            if (!xdr->codeUint8(&tn->kind) ||
+                !xdr->codeUint32(&tn->stackDepth) ||
+                !xdr->codeUint32(&tn->start) ||
+                !xdr->codeUint32(&tn->length)) {
+                return false;
+            }
+        } while (tn != tnfirst);
+    }
+
+    for (i = 0; i < nblockscopes; ++i) {
+        BlockScopeNote *note = &script->blockScopes()->vector[i];
+        if (!xdr->codeUint32(&note->index) ||
+            !xdr->codeUint32(&note->start) ||
+            !xdr->codeUint32(&note->length) ||
+            !xdr->codeUint32(&note->parent))
+        {
+            return false;
+        }
+    }
+
+    if (scriptBits & (1 << HasLazyScript)) {
+        Rooted<LazyScript *> lazy(cx);
+        if (mode == XDR_ENCODE)
+            lazy = script->maybeLazyScript();
+
+        if (!XDRRelazificationInfo(xdr, fun, script, &lazy))
+            return false;
+
+        if (mode == XDR_DECODE)
+            script->setLazyScript(lazy);
+    }
+
+    if (mode == XDR_DECODE) {
+        scriptp.set(script);
+
+        /* see BytecodeEmitter::tellDebuggerAboutCompiledScript */
+        CallNewScriptHook(cx, script, fun);
+        if (!fun) {
+            RootedGlobalObject global(cx, script->compileAndGo() ? &script->global() : nullptr);
+            Debugger::onNewScript(cx, script, global);
+        }
+    }
+
+    return true;
+}
+
+template bool
+js::XDRScript(XDRState<XDR_ENCODE> *, HandleObject, HandleScript, HandleFunction,
+              MutableHandleScript);
+
+template bool
+js::XDRScript(XDRState<XDR_DECODE> *, HandleObject, HandleScript, HandleFunction,
+              MutableHandleScript);
+
+template<XDRMode mode>
+bool
+js::XDRLazyScript(XDRState<mode> *xdr, HandleObject enclosingScope, HandleScript enclosingScript,
+                  HandleFunction fun, MutableHandle<LazyScript *> lazy)
+{
+    JSContext *cx = xdr->cx();
+
+    {
+        uint32_t begin;
+        uint32_t end;
+        uint32_t lineno;
+        uint32_t column;
+        uint64_t packedFields;
+
+        if (mode == XDR_ENCODE) {
+            MOZ_ASSERT(!lazy->maybeScript());
+            MOZ_ASSERT(fun == lazy->functionNonDelazifying());
+
+            begin = lazy->begin();
+            end = lazy->end();
+            lineno = lazy->lineno();
+            column = lazy->column();
+            packedFields = lazy->packedFields();
+        }
+
+        if (!xdr->codeUint32(&begin) || !xdr->codeUint32(&end) ||
+            !xdr->codeUint32(&lineno) || !xdr->codeUint32(&column) ||
+            !xdr->codeUint64(&packedFields))
+        {
+            return false;
+        }
+
+        if (mode == XDR_DECODE)
+            lazy.set(LazyScript::Create(cx, fun, packedFields, begin, end, lineno, column));
+    }
+
+    // Code free variables.
+    if (!XDRLazyFreeVariables(xdr, lazy))
+        return false;
+
+    // Code inner functions.
+    {
+        RootedObject func(cx);
+        HeapPtrFunction *innerFunctions = lazy->innerFunctions();
+        size_t numInnerFunctions = lazy->numInnerFunctions();
+        for (size_t i = 0; i < numInnerFunctions; i++) {
+            if (mode == XDR_ENCODE)
+                func = innerFunctions[i];
+
+            if (!XDRInterpretedFunction(xdr, fun, enclosingScript, &func))
+                return false;
+
+            if (mode == XDR_DECODE)
+                innerFunctions[i] = &func->as<JSFunction>();
+        }
+    }
+
+    if (mode == XDR_DECODE) {
+        JS_ASSERT(!lazy->sourceObject());
+        ScriptSourceObject *sourceObject = &enclosingScript->scriptSourceUnwrap();
+
+        // Set the enclosing scope of the lazy function, this would later be
+        // used to define the environment when the function would be used.
+        lazy->setParent(enclosingScope, sourceObject);
+    }
+
+    return true;
+}
+
+template bool
+js::XDRLazyScript(XDRState<XDR_ENCODE> *, HandleObject, HandleScript,
+                  HandleFunction, MutableHandle<LazyScript *>);
+
+template bool
+js::XDRLazyScript(XDRState<XDR_DECODE> *, HandleObject, HandleScript,
+                  HandleFunction, MutableHandle<LazyScript *>);
+
+void
+JSScript::setSourceObject(JSObject *object)
+{
+    JS_ASSERT(compartment() == object->compartment());
+    sourceObject_ = object;
+}
+
+js::ScriptSourceObject &
+JSScript::scriptSourceUnwrap() const {
+    return UncheckedUnwrap(sourceObject())->as<ScriptSourceObject>();
+}
+
+js::ScriptSource *
+JSScript::scriptSource() const {
+    return scriptSourceUnwrap().source();
+}
+
+bool
+JSScript::initScriptCounts(JSContext *cx)
+{
+    JS_ASSERT(!hasScriptCounts());
+
+    size_t n = 0;
+
+    for (jsbytecode *pc = code(); pc < codeEnd(); pc += GetBytecodeLength(pc))
+        n += PCCounts::numCounts(JSOp(*pc));
+
+    size_t bytes = (length() * sizeof(PCCounts)) + (n * sizeof(double));
+    char *base = (char *) cx->calloc_(bytes);
+    if (!base)
+        return false;
+
+    /* Create compartment's scriptCountsMap if necessary. */
+    ScriptCountsMap *map = compartment()->scriptCountsMap;
+    if (!map) {
+        map = cx->new_<ScriptCountsMap>();
+        if (!map || !map->init()) {
+            js_free(base);
+            js_delete(map);
+            return false;
+        }
+        compartment()->scriptCountsMap = map;
+    }
+
+    char *cursor = base;
+
+    ScriptCounts scriptCounts;
+    scriptCounts.pcCountsVector = (PCCounts *) cursor;
+    cursor += length() * sizeof(PCCounts);
+
+    for (jsbytecode *pc = code(); pc < codeEnd(); pc += GetBytecodeLength(pc)) {
+        JS_ASSERT(uintptr_t(cursor) % sizeof(double) == 0);
+        scriptCounts.pcCountsVector[pcToOffset(pc)].counts = (double *) cursor;
+        size_t capacity = PCCounts::numCounts(JSOp(*pc));
+#ifdef DEBUG
+        scriptCounts.pcCountsVector[pcToOffset(pc)].capacity = capacity;
+#endif
+        cursor += capacity * sizeof(double);
+    }
+
+    if (!map->putNew(this, scriptCounts)) {
+        js_free(base);
+        return false;
+    }
+    hasScriptCounts_ = true; // safe to set this;  we can't fail after this point
+
+    JS_ASSERT(size_t(cursor - base) == bytes);
+
+    /* Enable interrupts in any interpreter frames running on this script. */
+    for (ActivationIterator iter(cx->runtime()); !iter.done(); ++iter) {
+        if (iter->isInterpreter())
+            iter->asInterpreter()->enableInterruptsIfRunning(this);
+    }
+
+    return true;
+}
+
+static inline ScriptCountsMap::Ptr GetScriptCountsMapEntry(JSScript *script)
+{
+    JS_ASSERT(script->hasScriptCounts());
+    ScriptCountsMap *map = script->compartment()->scriptCountsMap;
+    ScriptCountsMap::Ptr p = map->lookup(script);
+    JS_ASSERT(p);
+    return p;
+}
+
+js::PCCounts
+JSScript::getPCCounts(jsbytecode *pc) {
+    JS_ASSERT(containsPC(pc));
+    ScriptCountsMap::Ptr p = GetScriptCountsMapEntry(this);
+    return p->value().pcCountsVector[pcToOffset(pc)];
+}
+
+void
+JSScript::addIonCounts(jit::IonScriptCounts *ionCounts)
+{
+    ScriptCountsMap::Ptr p = GetScriptCountsMapEntry(this);
+    if (p->value().ionCounts)
+        ionCounts->setPrevious(p->value().ionCounts);
+    p->value().ionCounts = ionCounts;
+}
+
+jit::IonScriptCounts *
+JSScript::getIonCounts()
+{
+    ScriptCountsMap::Ptr p = GetScriptCountsMapEntry(this);
+    return p->value().ionCounts;
+}
+
+ScriptCounts
+JSScript::releaseScriptCounts()
+{
+    ScriptCountsMap::Ptr p = GetScriptCountsMapEntry(this);
+    ScriptCounts counts = p->value();
+    compartment()->scriptCountsMap->remove(p);
+    hasScriptCounts_ = false;
+    return counts;
+}
+
+void
+JSScript::destroyScriptCounts(FreeOp *fop)
+{
+    if (hasScriptCounts()) {
+        ScriptCounts scriptCounts = releaseScriptCounts();
+        scriptCounts.destroy(fop);
+    }
+}
+
+void
+ScriptSourceObject::setSource(ScriptSource *source)
+{
+    if (source)
+        source->incref();
+    if (this->source())
+        this->source()->decref();
+    setReservedSlot(SOURCE_SLOT, PrivateValue(source));
+}
+
+JSObject *
+ScriptSourceObject::element() const
+{
+    return getReservedSlot(ELEMENT_SLOT).toObjectOrNull();
+}
+
+void
+ScriptSourceObject::initElement(HandleObject element)
+{
+    JS_ASSERT(getReservedSlot(ELEMENT_SLOT).isNull());
+    setReservedSlot(ELEMENT_SLOT, ObjectOrNullValue(element));
+}
+
+const Value &
+ScriptSourceObject::elementAttributeName() const
+{
+    const Value &prop = getReservedSlot(ELEMENT_PROPERTY_SLOT);
+    JS_ASSERT(prop.isUndefined() || prop.isString());
+    return prop;
+}
+
+void
+ScriptSourceObject::initIntroductionScript(JSScript *script)
+{
+    JS_ASSERT(!getReservedSlot(INTRODUCTION_SCRIPT_SLOT).toPrivate());
+
+    // There is no equivalent of cross-compartment wrappers for scripts. If
+    // the introduction script would be in a different compartment from the
+    // compiled code, we would be creating a cross-compartment script
+    // reference, which would be bogus. In that case, just don't bother to
+    // retain the introduction script.
+    if (script && script->compartment() == compartment())
+        setReservedSlot(INTRODUCTION_SCRIPT_SLOT, PrivateValue(script));
+}
+
+void
+ScriptSourceObject::trace(JSTracer *trc, JSObject *obj)
+{
+    ScriptSourceObject *sso = static_cast<ScriptSourceObject *>(obj);
+
+    if (JSScript *script = sso->introductionScript()) {
+        MarkScriptUnbarriered(trc, &script, "ScriptSourceObject introductionScript");
+        sso->setReservedSlot(INTRODUCTION_SCRIPT_SLOT, PrivateValue(script));
+    }
+}
+
+void
+ScriptSourceObject::finalize(FreeOp *fop, JSObject *obj)
+{
+    // ScriptSource::setSource automatically takes care of the refcount
+    obj->as<ScriptSourceObject>().setSource(nullptr);
+}
+
+const Class ScriptSourceObject::class_ = {
+    "ScriptSource",
+    JSCLASS_HAS_RESERVED_SLOTS(RESERVED_SLOTS) |
+    JSCLASS_IMPLEMENTS_BARRIERS | JSCLASS_IS_ANONYMOUS,
+    JS_PropertyStub,        /* addProperty */
+    JS_DeletePropertyStub,  /* delProperty */
+    JS_PropertyStub,        /* getProperty */
+    JS_StrictPropertyStub,  /* setProperty */
+    JS_EnumerateStub,
+    JS_ResolveStub,
+    JS_ConvertStub,
+    finalize,
+    nullptr,                /* call        */
+    nullptr,                /* hasInstance */
+    nullptr,                /* construct   */
+    trace
+};
+
+ScriptSourceObject *
+ScriptSourceObject::create(ExclusiveContext *cx, ScriptSource *source,
+                           const ReadOnlyCompileOptions &options)
+{
+    RootedObject object(cx, NewObjectWithGivenProto(cx, &class_, nullptr, cx->global()));
+    if (!object)
+        return nullptr;
+    RootedScriptSource sourceObject(cx, &object->as<ScriptSourceObject>());
+
+    source->incref();
+    sourceObject->initSlot(SOURCE_SLOT, PrivateValue(source));
+    sourceObject->initSlot(ELEMENT_SLOT, ObjectOrNullValue(options.element()));
+    if (options.elementAttributeName())
+        sourceObject->initSlot(ELEMENT_PROPERTY_SLOT, StringValue(options.elementAttributeName()));
+    else
+        sourceObject->initSlot(ELEMENT_PROPERTY_SLOT, UndefinedValue());
+
+    sourceObject->initSlot(INTRODUCTION_SCRIPT_SLOT, PrivateValue(nullptr));
+    sourceObject->initIntroductionScript(options.introductionScript());
+
+    return sourceObject;
+}
+
+static const unsigned char emptySource[] = "";
+
+/* Adjust the amount of memory this script source uses for source data,
+   reallocating if needed. */
+bool
+ScriptSource::adjustDataSize(size_t nbytes)
+{
+    // Allocating 0 bytes has undefined behavior, so special-case it.
+    if (nbytes == 0) {
+        if (data.compressed != emptySource)
+            js_free(data.compressed);
+        data.compressed = const_cast<unsigned char *>(emptySource);
+        return true;
+    }
+
+    // |data.compressed| can be nullptr.
+    void *buf = js_realloc(data.compressed, nbytes);
+    if (!buf && data.compressed != emptySource)
+        js_free(data.compressed);
+    data.compressed = static_cast<unsigned char *>(buf);
+    return !!data.compressed;
+}
+
+/* static */ bool
+JSScript::loadSource(JSContext *cx, ScriptSource *ss, bool *worked)
+{
+    JS_ASSERT(!ss->hasSourceData());
+    *worked = false;
+    if (!cx->runtime()->sourceHook || !ss->sourceRetrievable())
+        return true;
+    jschar *src = nullptr;
+    size_t length;
+    if (!cx->runtime()->sourceHook->load(cx, ss->filename(), &src, &length))
+        return false;
+    if (!src)
+        return true;
+    ss->setSource(src, length);
+    *worked = true;
+    return true;
+}
+
+JSFlatString *
+JSScript::sourceData(JSContext *cx)
+{
+    JS_ASSERT(scriptSource()->hasSourceData());
+    return scriptSource()->substring(cx, sourceStart(), sourceEnd());
+}
+
+SourceDataCache::AutoHoldEntry::AutoHoldEntry()
+  : cache_(nullptr), source_(nullptr), charsToFree_(nullptr)
+{
+}
+
+void
+SourceDataCache::AutoHoldEntry::holdEntry(SourceDataCache *cache, ScriptSource *source)
+{
+    // Initialise the holder for a specific cache and script source. This will
+    // hold on to the cached source chars in the event that the cache is purged.
+    JS_ASSERT(!cache_ && !source_ && !charsToFree_);
+    cache_ = cache;
+    source_ = source;
+}
+
+void
+SourceDataCache::AutoHoldEntry::deferDelete(const jschar *chars)
+{
+    // Take ownership of source chars now the cache is being purged. Remove our
+    // reference to the ScriptSource which might soon be destroyed.
+    JS_ASSERT(cache_ && source_ && !charsToFree_);
+    cache_ = nullptr;
+    source_ = nullptr;
+    charsToFree_ = chars;
+}
+
+SourceDataCache::AutoHoldEntry::~AutoHoldEntry()
+{
+    // The holder is going out of scope. If it has taken ownership of cached
+    // chars then delete them, otherwise unregister ourself with the cache.
+    if (charsToFree_) {
+        JS_ASSERT(!cache_ && !source_);
+        js_free(const_cast<jschar *>(charsToFree_));
+    } else if (cache_) {
+        JS_ASSERT(source_);
+        cache_->releaseEntry(*this);
+    }
+}
+
+void
+SourceDataCache::holdEntry(AutoHoldEntry &holder, ScriptSource *ss)
+{
+    JS_ASSERT(!holder_);
+    holder.holdEntry(this, ss);
+    holder_ = &holder;
+}
+
+void
+SourceDataCache::releaseEntry(AutoHoldEntry &holder)
+{
+    JS_ASSERT(holder_ == &holder);
+    holder_ = nullptr;
+}
+
+const jschar *
+SourceDataCache::lookup(ScriptSource *ss, AutoHoldEntry &holder)
+{
+    JS_ASSERT(!holder_);
+    if (!map_)
+        return nullptr;
+    if (Map::Ptr p = map_->lookup(ss)) {
+        holdEntry(holder, ss);
+        return p->value();
+    }
+    return nullptr;
+}
+
+bool
+SourceDataCache::put(ScriptSource *ss, const jschar *str, AutoHoldEntry &holder)
+{
+    JS_ASSERT(!holder_);
+
+    if (!map_) {
+        map_ = js_new<Map>();
+        if (!map_)
+            return false;
+
+        if (!map_->init()) {
+            js_delete(map_);
+            map_ = nullptr;
+            return false;
+        }
+    }
+
+    if (!map_->put(ss, str))
+        return false;
+
+    holdEntry(holder, ss);
+    return true;
+}
+
+void
+SourceDataCache::purge()
+{
+    if (!map_)
+        return;
+
+    for (Map::Range r = map_->all(); !r.empty(); r.popFront()) {
+        const jschar *chars = r.front().value();
+        if (holder_ && r.front().key() == holder_->source()) {
+            holder_->deferDelete(chars);
+            holder_ = nullptr;
+        } else {
+            js_free(const_cast<jschar*>(chars));
+        }
+    }
+
+    js_delete(map_);
+    map_ = nullptr;
+}
+
+size_t
+SourceDataCache::sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf)
+{
+    size_t n = 0;
+    if (map_ && !map_->empty()) {
+        n += map_->sizeOfIncludingThis(mallocSizeOf);
+        for (Map::Range r = map_->all(); !r.empty(); r.popFront()) {
+            const jschar *v = r.front().value();
+            n += mallocSizeOf(v);
+        }
+    }
+    return n;
+}
+
+const jschar *
+ScriptSource::chars(JSContext *cx, SourceDataCache::AutoHoldEntry &holder)
+{
+    if (const jschar *chars = getOffThreadCompressionChars(cx))
+        return chars;
+    JS_ASSERT(ready());
+
+#ifdef USE_ZLIB
+    if (compressed()) {
+        if (const jschar *decompressed = cx->runtime()->sourceDataCache.lookup(this, holder))
+            return decompressed;
+
+        const size_t nbytes = sizeof(jschar) * (length_ + 1);
+        jschar *decompressed = static_cast<jschar *>(js_malloc(nbytes));
+        if (!decompressed)
+            return nullptr;
+
+        if (!DecompressString(data.compressed, compressedLength_,
+                              reinterpret_cast<unsigned char *>(decompressed), nbytes)) {
+            JS_ReportOutOfMemory(cx);
+            js_free(decompressed);
+            return nullptr;
+        }
+
+        decompressed[length_] = 0;
+
+        if (!cx->runtime()->sourceDataCache.put(this, decompressed, holder)) {
+            JS_ReportOutOfMemory(cx);
+            js_free(decompressed);
+            return nullptr;
+        }
+
+        return decompressed;
+    }
+#endif
+    return data.source;
+}
+
+JSFlatString *
+ScriptSource::substring(JSContext *cx, uint32_t start, uint32_t stop)
+{
+    JS_ASSERT(start <= stop);
+    SourceDataCache::AutoHoldEntry holder;
+    const jschar *chars = this->chars(cx, holder);
+    if (!chars)
+        return nullptr;
+    return js_NewStringCopyN<CanGC>(cx, chars + start, stop - start);
+}
+
+bool
+ScriptSource::setSourceCopy(ExclusiveContext *cx, SourceBufferHolder &srcBuf,
+                            bool argumentsNotIncluded, SourceCompressionTask *task)
+{
+    JS_ASSERT(!hasSourceData());
+    length_ = srcBuf.length();
+    argumentsNotIncluded_ = argumentsNotIncluded;
+
+    // There are several cases where source compression is not a good idea:
+    //  - If the script is tiny, then compression will save little or no space.
+    //  - If the script is enormous, then decompression can take seconds. With
+    //    lazy parsing, decompression is not uncommon, so this can significantly
+    //    increase latency.
+    //  - If there is only one core, then compression will contend with JS
+    //    execution (which hurts benchmarketing).
+    //  - If the source contains a giant string, then parsing will finish much
+    //    faster than compression which increases latency (this case is handled
+    //    in Parser::stringLiteral).
+    //
+    // Lastly, since the parsing thread will eventually perform a blocking wait
+    // on the compresion task's worker thread, require that there are at least 2
+    // worker threads:
+    //  - If we are on a worker thread, there must be another worker thread to
+    //    execute our compression task.
+    //  - If we are on the main thread, there must be at least two worker
+    //    threads since at most one worker thread can be blocking on the main
+    //    thread (see WorkerThreadState::canStartParseTask) which would cause a
+    //    deadlock if there wasn't a second worker thread that could make
+    //    progress on our compression task.
+#ifdef JS_THREADSAFE
+    bool canCompressOffThread =
+        WorkerThreadState().cpuCount > 1 &&
+        WorkerThreadState().threadCount >= 2;
+#else
+    bool canCompressOffThread = false;
+#endif
+    const size_t TINY_SCRIPT = 256;
+    const size_t HUGE_SCRIPT = 5 * 1024 * 1024;
+    if (TINY_SCRIPT <= srcBuf.length() && srcBuf.length() < HUGE_SCRIPT && canCompressOffThread) {
+        task->ss = this;
+        task->chars = srcBuf.get();
+        ready_ = false;
+        if (!StartOffThreadCompression(cx, task))
+            return false;
+    } else if (srcBuf.ownsChars()) {
+        data.source = srcBuf.take();
+    } else {
+        if (!adjustDataSize(sizeof(jschar) * srcBuf.length()))
+            return false;
+        PodCopy(data.source, srcBuf.get(), length_);
+    }
+
+    return true;
+}
+
+void
+ScriptSource::setSource(const jschar *src, size_t length)
+{
+    JS_ASSERT(!hasSourceData());
+    length_ = length;
+    JS_ASSERT(!argumentsNotIncluded_);
+    data.source = const_cast<jschar *>(src);
+}
+
+bool
+SourceCompressionTask::work()
+{
+    // A given compression token can be compressed on any thread, and the ss
+    // not being ready indicates to other threads that its fields might change
+    // with no lock held.
+    JS_ASSERT(!ss->ready());
+
+    size_t compressedLength = 0;
+    size_t nbytes = sizeof(jschar) * ss->length_;
+
+    // Memory allocation functions on JSRuntime and JSContext are not
+    // threadsafe. We have to use the js_* variants.
+
+#ifdef USE_ZLIB
+    // Try to keep the maximum memory usage down by only allocating half the
+    // size of the string, first.
+    size_t firstSize = nbytes / 2;
+    if (!ss->adjustDataSize(firstSize))
+        return false;
+    Compressor comp(reinterpret_cast<const unsigned char *>(chars), nbytes);
+    if (!comp.init())
+        return false;
+    comp.setOutput(ss->data.compressed, firstSize);
+    bool cont = !abort_;
+    while (cont) {
+        switch (comp.compressMore()) {
+          case Compressor::CONTINUE:
+            break;
+          case Compressor::MOREOUTPUT: {
+            if (comp.outWritten() == nbytes) {
+                cont = false;
+                break;
+            }
+
+            // The compressed output is greater than half the size of the
+            // original string. Reallocate to the full size.
+            if (!ss->adjustDataSize(nbytes))
+                return false;
+            comp.setOutput(ss->data.compressed, nbytes);
+            break;
+          }
+          case Compressor::DONE:
+            cont = false;
+            break;
+          case Compressor::OOM:
+            return false;
+        }
+        cont = cont && !abort_;
+    }
+    compressedLength = comp.outWritten();
+    if (abort_ || compressedLength == nbytes)
+        compressedLength = 0;
+#endif
+
+    if (compressedLength == 0) {
+        if (!ss->adjustDataSize(nbytes))
+            return false;
+        PodCopy(ss->data.source, chars, ss->length());
+    } else {
+        // Shrink the buffer to the size of the compressed data. Shouldn't fail.
+        JS_ALWAYS_TRUE(ss->adjustDataSize(compressedLength));
+    }
+    ss->compressedLength_ = compressedLength;
+    return true;
+}
+
+void
+ScriptSource::destroy()
+{
+    JS_ASSERT(ready());
+    adjustDataSize(0);
+    if (introducerFilename_ != filename_)
+        js_free(introducerFilename_);
+    js_free(filename_);
+    js_free(displayURL_);
+    js_free(sourceMapURL_);
+    if (originPrincipals_)
+        JS_DropPrincipals(TlsPerThreadData.get()->runtimeFromMainThread(), originPrincipals_);
+    ready_ = false;
+    js_free(this);
+}
+
+void
+ScriptSource::addSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf,
+                                     JS::ScriptSourceInfo *info) const
+{
+    if (ready() && data.compressed != emptySource) {
+        if (compressed())
+            info->compressed += mallocSizeOf(data.compressed);
+        else
+            info->uncompressed += mallocSizeOf(data.source);
+    }
+    info->misc += mallocSizeOf(this) + mallocSizeOf(filename_);
+    info->numScripts++;
+}
+
+template<XDRMode mode>
+bool
+ScriptSource::performXDR(XDRState<mode> *xdr)
+{
+    uint8_t hasSource = hasSourceData();
+    if (!xdr->codeUint8(&hasSource))
+        return false;
+
+    uint8_t retrievable = sourceRetrievable_;
+    if (!xdr->codeUint8(&retrievable))
+        return false;
+    sourceRetrievable_ = retrievable;
+
+    if (hasSource && !sourceRetrievable_) {
+        // Only set members when we know decoding cannot fail. This prevents the
+        // script source from being partially initialized.
+        uint32_t length = length_;
+        if (!xdr->codeUint32(&length))
+            return false;
+
+        uint32_t compressedLength = compressedLength_;
+        if (!xdr->codeUint32(&compressedLength))
+            return false;
+
+        uint8_t argumentsNotIncluded = argumentsNotIncluded_;
+        if (!xdr->codeUint8(&argumentsNotIncluded))
+            return false;
+
+        size_t byteLen = compressedLength ? compressedLength : (length * sizeof(jschar));
+        if (mode == XDR_DECODE) {
+            if (!adjustDataSize(byteLen))
+                return false;
+        }
+        if (!xdr->codeBytes(data.compressed, byteLen)) {
+            if (mode == XDR_DECODE) {
+                js_free(data.compressed);
+                data.compressed = nullptr;
+            }
+            return false;
+        }
+        length_ = length;
+        compressedLength_ = compressedLength;
+        argumentsNotIncluded_ = argumentsNotIncluded;
+    }
+
+    uint8_t haveSourceMap = hasSourceMapURL();
+    if (!xdr->codeUint8(&haveSourceMap))
+        return false;
+
+    if (haveSourceMap) {
+        uint32_t sourceMapURLLen = (mode == XDR_DECODE) ? 0 : js_strlen(sourceMapURL_);
+        if (!xdr->codeUint32(&sourceMapURLLen))
+            return false;
+
+        if (mode == XDR_DECODE) {
+            size_t byteLen = (sourceMapURLLen + 1) * sizeof(jschar);
+            sourceMapURL_ = static_cast<jschar *>(xdr->cx()->malloc_(byteLen));
+            if (!sourceMapURL_)
+                return false;
+        }
+        if (!xdr->codeChars(sourceMapURL_, sourceMapURLLen)) {
+            if (mode == XDR_DECODE) {
+                js_free(sourceMapURL_);
+                sourceMapURL_ = nullptr;
+            }
+            return false;
+        }
+        sourceMapURL_[sourceMapURLLen] = '\0';
+    }
+
+    uint8_t haveDisplayURL = hasDisplayURL();
+    if (!xdr->codeUint8(&haveDisplayURL))
+        return false;
+
+    if (haveDisplayURL) {
+        uint32_t displayURLLen = (mode == XDR_DECODE) ? 0 : js_strlen(displayURL_);
+        if (!xdr->codeUint32(&displayURLLen))
+            return false;
+
+        if (mode == XDR_DECODE) {
+            size_t byteLen = (displayURLLen + 1) * sizeof(jschar);
+            displayURL_ = static_cast<jschar *>(xdr->cx()->malloc_(byteLen));
+            if (!displayURL_)
+                return false;
+        }
+        if (!xdr->codeChars(displayURL_, displayURLLen)) {
+            if (mode == XDR_DECODE) {
+                js_free(displayURL_);
+                displayURL_ = nullptr;
+            }
+            return false;
+        }
+        displayURL_[displayURLLen] = '\0';
+    }
+
+    uint8_t haveFilename = !!filename_;
+    if (!xdr->codeUint8(&haveFilename))
+        return false;
+
+    if (haveFilename) {
+        const char *fn = filename();
+        if (!xdr->codeCString(&fn))
+            return false;
+        if (mode == XDR_DECODE && !setFilename(xdr->cx(), fn))
+            return false;
+    }
+
+    if (mode == XDR_DECODE)
+        ready_ = true;
+
+    return true;
+}
+
+// Format and return a cx->malloc_'ed URL for a generated script like:
+//   {filename} line {lineno} > {introducer}
+// For example:
+//   foo.js line 7 > eval
+// indicating code compiled by the call to 'eval' on line 7 of foo.js.
+static char *
+FormatIntroducedFilename(ExclusiveContext *cx, const char *filename, unsigned lineno,
+                         const char *introducer)
+{
+    // Compute the length of the string in advance, so we can allocate a
+    // buffer of the right size on the first shot.
+    //
+    // (JS_smprintf would be perfect, as that allocates the result
+    // dynamically as it formats the string, but it won't allocate from cx,
+    // and wants us to use a special free function.)
+    char linenoBuf[15];
+    size_t filenameLen = strlen(filename);
+    size_t linenoLen = JS_snprintf(linenoBuf, 15, "%u", lineno);
+    size_t introducerLen = strlen(introducer);
+    size_t len = filenameLen                    +
+                 6 /* == strlen(" line ") */    +
+                 linenoLen                      +
+                 3 /* == strlen(" > ") */       +
+                 introducerLen                  +
+                 1 /* \0 */;
+    char *formatted = cx->pod_malloc<char>(len);
+    if (!formatted)
+        return nullptr;
+    mozilla::DebugOnly<size_t> checkLen = JS_snprintf(formatted, len, "%s line %s > %s",
+                                                      filename, linenoBuf, introducer);
+    JS_ASSERT(checkLen == len - 1);
+
+    return formatted;
+}
+
+bool
+ScriptSource::initFromOptions(ExclusiveContext *cx, const ReadOnlyCompileOptions &options)
+{
+    JS_ASSERT(!filename_);
+    JS_ASSERT(!introducerFilename_);
+
+    originPrincipals_ = options.originPrincipals(cx);
+    if (originPrincipals_)
+        JS_HoldPrincipals(originPrincipals_);
+
+    introductionType_ = options.introductionType;
+    setIntroductionOffset(options.introductionOffset);
+
+    if (options.hasIntroductionInfo) {
+        JS_ASSERT(options.introductionType != nullptr);
+        const char *filename = options.filename() ? options.filename() : "<unknown>";
+        char *formatted = FormatIntroducedFilename(cx, filename, options.introductionLineno,
+                                                   options.introductionType);
+        if (!formatted)
+            return false;
+        filename_ = formatted;
+    } else if (options.filename()) {
+        if (!setFilename(cx, options.filename()))
+            return false;
+    }
+
+    if (options.introducerFilename()) {
+        introducerFilename_ = js_strdup(cx, options.introducerFilename());
+        if (!introducerFilename_)
+            return false;
+    } else {
+        introducerFilename_ = filename_;
+    }
+
+    return true;
+}
+
+bool
+ScriptSource::setFilename(ExclusiveContext *cx, const char *filename)
+{
+    JS_ASSERT(!filename_);
+    filename_ = js_strdup(cx, filename);
+    if (!filename_)
+        return false;
+    return true;
+}
+
+bool
+ScriptSource::setDisplayURL(ExclusiveContext *cx, const jschar *displayURL)
+{
+    JS_ASSERT(displayURL);
+    if (hasDisplayURL()) {
+        if (cx->isJSContext() &&
+            !JS_ReportErrorFlagsAndNumber(cx->asJSContext(), JSREPORT_WARNING,
+                                          js_GetErrorMessage, nullptr,
+                                          JSMSG_ALREADY_HAS_PRAGMA, filename_,
+                                          "//# sourceURL"))
+        {
+            return false;
+        }
+    }
+    size_t len = js_strlen(displayURL) + 1;
+    if (len == 1)
+        return true;
+    displayURL_ = js_strdup(cx, displayURL);
+    if (!displayURL_)
+        return false;
+    return true;
+}
+
+const jschar *
+ScriptSource::displayURL()
+{
+    JS_ASSERT(hasDisplayURL());
+    return displayURL_;
+}
+
+bool
+ScriptSource::setSourceMapURL(ExclusiveContext *cx, const jschar *sourceMapURL)
+{
+    JS_ASSERT(sourceMapURL);
+    if (hasSourceMapURL()) {
+        if (cx->isJSContext() &&
+            !JS_ReportErrorFlagsAndNumber(cx->asJSContext(), JSREPORT_WARNING,
+                                          js_GetErrorMessage, nullptr,
+                                          JSMSG_ALREADY_HAS_PRAGMA, filename_,
+                                          "//# sourceMappingURL"))
+        {
+            return false;
+        }
+    }
+
+    size_t len = js_strlen(sourceMapURL) + 1;
+    if (len == 1)
+        return true;
+    sourceMapURL_ = js_strdup(cx, sourceMapURL);
+    if (!sourceMapURL_)
+        return false;
+    return true;
+}
+
+const jschar *
+ScriptSource::sourceMapURL()
+{
+    JS_ASSERT(hasSourceMapURL());
+    return sourceMapURL_;
+}
+
+/*
+ * Shared script data management.
+ */
+
+SharedScriptData *
+js::SharedScriptData::new_(ExclusiveContext *cx, uint32_t codeLength,
+                           uint32_t srcnotesLength, uint32_t natoms)
+{
+    /*
+     * Ensure the atoms are aligned, as some architectures don't allow unaligned
+     * access.
+     */
+    const uint32_t pointerSize = sizeof(JSAtom *);
+    const uint32_t pointerMask = pointerSize - 1;
+    const uint32_t dataOffset = offsetof(SharedScriptData, data);
+    uint32_t baseLength = codeLength + srcnotesLength;
+    uint32_t padding = (pointerSize - ((baseLength + dataOffset) & pointerMask)) & pointerMask;
+    uint32_t length = baseLength + padding + pointerSize * natoms;
+
+    SharedScriptData *entry = (SharedScriptData *)cx->malloc_(length + dataOffset);
+    if (!entry)
+        return nullptr;
+
+    entry->length = length;
+    entry->natoms = natoms;
+    entry->marked = false;
+    memset(entry->data + baseLength, 0, padding);
+
+    /*
+     * Call constructors to initialize the storage that will be accessed as a
+     * HeapPtrAtom array via atoms().
+     */
+    HeapPtrAtom *atoms = entry->atoms();
+    JS_ASSERT(reinterpret_cast<uintptr_t>(atoms) % sizeof(JSAtom *) == 0);
+    for (unsigned i = 0; i < natoms; ++i)
+        new (&atoms[i]) HeapPtrAtom();
+
+    return entry;
+}
+
+/*
+ * Takes ownership of its *ssd parameter and either adds it into the runtime's
+ * ScriptDataTable or frees it if a matching entry already exists.
+ *
+ * Sets the |code| and |atoms| fields on the given JSScript.
+ */
+static bool
+SaveSharedScriptData(ExclusiveContext *cx, Handle<JSScript *> script, SharedScriptData *ssd,
+                     uint32_t nsrcnotes)
+{
+    ASSERT(script != nullptr);
+    ASSERT(ssd != nullptr);
+
+    AutoLockForExclusiveAccess lock(cx);
+
+    ScriptBytecodeHasher::Lookup l(ssd);
+
+    ScriptDataTable::AddPtr p = cx->scriptDataTable().lookupForAdd(l);
+    if (p) {
+        js_free(ssd);
+        ssd = *p;
+    } else {
+        if (!cx->scriptDataTable().add(p, ssd)) {
+            script->setCode(nullptr);
+            script->atoms = nullptr;
+            js_free(ssd);
+            js_ReportOutOfMemory(cx);
+            return false;
+        }
+    }
+
+#ifdef JSGC_INCREMENTAL
+    /*
+     * During the IGC we need to ensure that bytecode is marked whenever it is
+     * accessed even if the bytecode was already in the table: at this point
+     * old scripts or exceptions pointing to the bytecode may no longer be
+     * reachable. This is effectively a read barrier.
+     */
+    if (cx->isJSContext()) {
+        JSRuntime *rt = cx->asJSContext()->runtime();
+        if (JS::IsIncrementalGCInProgress(rt) && rt->gcIsFull)
+            ssd->marked = true;
+    }
+#endif
+
+    script->setCode(ssd->data);
+    script->atoms = ssd->atoms();
+    return true;
+}
+
+static inline void
+MarkScriptData(JSRuntime *rt, const jsbytecode *bytecode)
+{
+    /*
+     * As an invariant, a ScriptBytecodeEntry should not be 'marked' outside of
+     * a GC. Since SweepScriptBytecodes is only called during a full gc,
+     * to preserve this invariant, only mark during a full gc.
+     */
+    if (rt->gcIsFull)
+        SharedScriptData::fromBytecode(bytecode)->marked = true;
+}
+
+void
+js::UnmarkScriptData(JSRuntime *rt)
+{
+    JS_ASSERT(rt->gcIsFull);
+    ScriptDataTable &table = rt->scriptDataTable();
+    for (ScriptDataTable::Enum e(table); !e.empty(); e.popFront()) {
+        SharedScriptData *entry = e.front();
+        entry->marked = false;
+    }
+}
+
+void
+js::SweepScriptData(JSRuntime *rt)
+{
+    JS_ASSERT(rt->gcIsFull);
+    ScriptDataTable &table = rt->scriptDataTable();
+
+    if (rt->keepAtoms())
+        return;
+
+    for (ScriptDataTable::Enum e(table); !e.empty(); e.popFront()) {
+        SharedScriptData *entry = e.front();
+        if (!entry->marked) {
+            js_free(entry);
+            e.removeFront();
+        }
+    }
+}
+
+void
+js::FreeScriptData(JSRuntime *rt)
+{
+    ScriptDataTable &table = rt->scriptDataTable();
+    if (!table.initialized())
+        return;
+
+    for (ScriptDataTable::Enum e(table); !e.empty(); e.popFront())
+        js_free(e.front());
+
+    table.clear();
+}
+
+/*
+ * JSScript::data and SharedScriptData::data have complex,
+ * manually-controlled, memory layouts.
+ *
+ * JSScript::data begins with some optional array headers. They are optional
+ * because they often aren't needed, i.e. the corresponding arrays often have
+ * zero elements. Each header has a bit in JSScript::hasArrayBits that
+ * indicates if it's present within |data|; from this the offset of each
+ * present array header can be computed. Each header has an accessor function
+ * in JSScript that encapsulates this offset computation.
+ *
+ * Array type       Array elements  Accessor
+ * ----------       --------------  --------
+ * ConstArray       Consts          consts()
+ * ObjectArray      Objects         objects()
+ * ObjectArray      Regexps         regexps()
+ * TryNoteArray     Try notes       trynotes()
+ * BlockScopeArray  Scope notes     blockScopes()
+ *
+ * Then are the elements of several arrays.
+ * - Most of these arrays have headers listed above (if present). For each of
+ *   these, the array pointer and the array length is stored in the header.
+ * - The remaining arrays have pointers and lengths that are stored directly in
+ *   JSScript. This is because, unlike the others, they are nearly always
+ *   non-zero length and so the optional-header space optimization isn't
+ *   worthwhile.
+ *
+ * Array elements   Pointed to by         Length
+ * --------------   -------------         ------
+ * Consts           consts()->vector      consts()->length
+ * Objects          objects()->vector     objects()->length
+ * Regexps          regexps()->vector     regexps()->length
+ * Try notes        trynotes()->vector    trynotes()->length
+ * Scope notes      blockScopes()->vector blockScopes()->length
+ *
+ * IMPORTANT: This layout has two key properties.
+ * - It ensures that everything has sufficient alignment; in particular, the
+ *   consts() elements need jsval alignment.
+ * - It ensures there are no gaps between elements, which saves space and makes
+ *   manual layout easy. In particular, in the second part, arrays with larger
+ *   elements precede arrays with smaller elements.
+ *
+ * SharedScriptData::data contains data that can be shared within a
+ * runtime. These items' layout is manually controlled to make it easier to
+ * manage both during (temporary) allocation and during matching against
+ * existing entries in the runtime. As the jsbytecode has to come first to
+ * enable lookup by bytecode identity, SharedScriptData::data, the atoms part
+ * has to manually be aligned sufficiently by adding padding after the notes
+ * part.
+ *
+ * Array elements   Pointed to by         Length
+ * --------------   -------------         ------
+ * jsbytecode       code                  length
+ * jsscrnote        notes()               numNotes()
+ * Atoms            atoms                 natoms
+ *
+ * The following static assertions check JSScript::data's alignment properties.
+ */
+
+#define KEEPS_JSVAL_ALIGNMENT(T) \
+    (JS_ALIGNMENT_OF(jsval) % JS_ALIGNMENT_OF(T) == 0 && \
+     sizeof(T) % sizeof(jsval) == 0)
+
+#define HAS_JSVAL_ALIGNMENT(T) \
+    (JS_ALIGNMENT_OF(jsval) == JS_ALIGNMENT_OF(T) && \
+     sizeof(T) == sizeof(jsval))
+
+#define NO_PADDING_BETWEEN_ENTRIES(T1, T2) \
+    (JS_ALIGNMENT_OF(T1) % JS_ALIGNMENT_OF(T2) == 0)
+
+/*
+ * These assertions ensure that there is no padding between the array headers,
+ * and also that the consts() elements (which follow immediately afterward) are
+ * jsval-aligned.  (There is an assumption that |data| itself is jsval-aligned;
+ * we check this below).
+ */
+JS_STATIC_ASSERT(KEEPS_JSVAL_ALIGNMENT(ConstArray));
+JS_STATIC_ASSERT(KEEPS_JSVAL_ALIGNMENT(ObjectArray));       /* there are two of these */
+JS_STATIC_ASSERT(KEEPS_JSVAL_ALIGNMENT(TryNoteArray));
+JS_STATIC_ASSERT(KEEPS_JSVAL_ALIGNMENT(BlockScopeArray));
+
+/* These assertions ensure there is no padding required between array elements. */
+JS_STATIC_ASSERT(HAS_JSVAL_ALIGNMENT(HeapValue));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(HeapValue, HeapPtrObject));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(HeapPtrObject, HeapPtrObject));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(HeapPtrObject, JSTryNote));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(JSTryNote, uint32_t));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(uint32_t, uint32_t));
+
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(HeapValue, BlockScopeNote));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(BlockScopeNote, BlockScopeNote));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(JSTryNote, BlockScopeNote));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(HeapPtrObject, BlockScopeNote));
+JS_STATIC_ASSERT(NO_PADDING_BETWEEN_ENTRIES(BlockScopeNote, uint32_t));
+
+static inline size_t
+ScriptDataSize(uint32_t nbindings, uint32_t nconsts, uint32_t nobjects, uint32_t nregexps,
+               uint32_t ntrynotes, uint32_t nblockscopes)
+{
+    size_t size = 0;
+
+    if (nconsts != 0)
+        size += sizeof(ConstArray) + nconsts * sizeof(Value);
+    if (nobjects != 0)
+        size += sizeof(ObjectArray) + nobjects * sizeof(JSObject *);
+    if (nregexps != 0)
+        size += sizeof(ObjectArray) + nregexps * sizeof(JSObject *);
+    if (ntrynotes != 0)
+        size += sizeof(TryNoteArray) + ntrynotes * sizeof(JSTryNote);
+    if (nblockscopes != 0)
+        size += sizeof(BlockScopeArray) + nblockscopes * sizeof(BlockScopeNote);
+
+    if (nbindings != 0) {
+	// Make sure bindings are sufficiently aligned.
+        size = JS_ROUNDUP(size, JS_ALIGNMENT_OF(Binding)) + nbindings * sizeof(Binding);
+    }
+
+    return size;
+}
+
+void
+JSScript::initCompartment(ExclusiveContext *cx)
+{
+    compartment_ = cx->compartment_;
+}
+
+JSScript *
+JSScript::Create(ExclusiveContext *cx, HandleObject enclosingScope, bool savedCallerFun,
+                 const ReadOnlyCompileOptions &options, unsigned staticLevel,
+                 HandleObject sourceObject, uint32_t bufStart, uint32_t bufEnd)
+{
+    JS_ASSERT(bufStart <= bufEnd);
+
+    RootedScript script(cx, js_NewGCScript(cx));
+    if (!script)
+        return nullptr;
+
+    PodZero(script.get());
+    new (&script->bindings) Bindings;
+
+    script->enclosingScopeOrOriginalFunction_ = enclosingScope;
+    script->savedCallerFun_ = savedCallerFun;
+    script->initCompartment(cx);
+
+    script->compileAndGo_ = options.compileAndGo;
+    script->selfHosted_ = options.selfHostingMode;
+    script->noScriptRval_ = options.noScriptRval;
+
+    script->version = options.version;
+    JS_ASSERT(script->getVersion() == options.version);     // assert that no overflow occurred
+
+    // This is an unsigned-to-uint16_t conversion, test for too-high values.
+    // In practice, recursion in Parser and/or BytecodeEmitter will blow the
+    // stack if we nest functions more than a few hundred deep, so this will
+    // never trigger.  Oh well.
+    if (staticLevel > UINT16_MAX) {
+        if (cx->isJSContext()) {
+            JS_ReportErrorNumber(cx->asJSContext(),
+                                 js_GetErrorMessage, nullptr, JSMSG_TOO_DEEP, js_function_str);
+        }
+        return nullptr;
+    }
+    script->staticLevel_ = uint16_t(staticLevel);
+
+    script->setSourceObject(sourceObject);
+    script->sourceStart_ = bufStart;
+    script->sourceEnd_ = bufEnd;
+
+    return script;
+}
+
+static inline uint8_t *
+AllocScriptData(ExclusiveContext *cx, size_t size)
+{
+    uint8_t *data = static_cast<uint8_t *>(cx->calloc_(JS_ROUNDUP(size, sizeof(Value))));
+    if (!data)
+        return nullptr;
+
+    // All script data is optional, so size might be 0. In that case, we don't care about alignment.
+    JS_ASSERT(size == 0 || size_t(data) % sizeof(Value) == 0);
+    return data;
+}
+
+/* static */ bool
+JSScript::partiallyInit(ExclusiveContext *cx, HandleScript script, uint32_t nconsts,
+                        uint32_t nobjects, uint32_t nregexps, uint32_t ntrynotes,
+                        uint32_t nblockscopes, uint32_t nTypeSets)
+{
+    size_t size = ScriptDataSize(script->bindings.count(), nconsts, nobjects, nregexps, ntrynotes,
+                                 nblockscopes);
+    if (size > 0) {
+        script->data = AllocScriptData(cx, size);
+        if (!script->data)
+            return false;
+    } else {
+        script->data = nullptr;
+    }
+    script->dataSize_ = size;
+
+    JS_ASSERT(nTypeSets <= UINT16_MAX);
+    script->nTypeSets_ = uint16_t(nTypeSets);
+
+    uint8_t *cursor = script->data;
+    if (nconsts != 0) {
+        script->setHasArray(CONSTS);
+        cursor += sizeof(ConstArray);
+    }
+    if (nobjects != 0) {
+        script->setHasArray(OBJECTS);
+        cursor += sizeof(ObjectArray);
+    }
+    if (nregexps != 0) {
+        script->setHasArray(REGEXPS);
+        cursor += sizeof(ObjectArray);
+    }
+    if (ntrynotes != 0) {
+        script->setHasArray(TRYNOTES);
+        cursor += sizeof(TryNoteArray);
+    }
+    if (nblockscopes != 0) {
+        script->setHasArray(BLOCK_SCOPES);
+        cursor += sizeof(BlockScopeArray);
+    }
+
+    if (nconsts != 0) {
+        JS_ASSERT(reinterpret_cast<uintptr_t>(cursor) % sizeof(jsval) == 0);
+        script->consts()->length = nconsts;
+        script->consts()->vector = (HeapValue *)cursor;
+        cursor += nconsts * sizeof(script->consts()->vector[0]);
+    }
+
+    if (nobjects != 0) {
+        script->objects()->length = nobjects;
+        script->objects()->vector = (HeapPtr<JSObject> *)cursor;
+        cursor += nobjects * sizeof(script->objects()->vector[0]);
+    }
+
+    if (nregexps != 0) {
+        script->regexps()->length = nregexps;
+        script->regexps()->vector = (HeapPtr<JSObject> *)cursor;
+        cursor += nregexps * sizeof(script->regexps()->vector[0]);
+    }
+
+    if (ntrynotes != 0) {
+        script->trynotes()->length = ntrynotes;
+        script->trynotes()->vector = reinterpret_cast<JSTryNote *>(cursor);
+        size_t vectorSize = ntrynotes * sizeof(script->trynotes()->vector[0]);
+#ifdef DEBUG
+        memset(cursor, 0, vectorSize);
+#endif
+        cursor += vectorSize;
+    }
+
+    if (nblockscopes != 0) {
+        script->blockScopes()->length = nblockscopes;
+        script->blockScopes()->vector = reinterpret_cast<BlockScopeNote *>(cursor);
+        size_t vectorSize = nblockscopes * sizeof(script->blockScopes()->vector[0]);
+#ifdef DEBUG
+        memset(cursor, 0, vectorSize);
+#endif
+        cursor += vectorSize;
+    }
+
+    if (script->bindings.count() != 0) {
+	// Make sure bindings are sufficiently aligned.
+	cursor = reinterpret_cast<uint8_t*>
+	    (JS_ROUNDUP(reinterpret_cast<uintptr_t>(cursor), JS_ALIGNMENT_OF(Binding)));
+    }
+    cursor = script->bindings.switchToScriptStorage(reinterpret_cast<Binding *>(cursor));
+
+    JS_ASSERT(cursor == script->data + size);
+    return true;
+}
+
+/* static */ bool
+JSScript::fullyInitTrivial(ExclusiveContext *cx, Handle<JSScript*> script)
+{
+    if (!partiallyInit(cx, script, 0, 0, 0, 0, 0, 0))
+        return false;
+
+    SharedScriptData *ssd = SharedScriptData::new_(cx, 1, 1, 0);
+    if (!ssd)
+        return false;
+
+    ssd->data[0] = JSOP_RETRVAL;
+    ssd->data[1] = SRC_NULL;
+    script->setLength(1);
+    return SaveSharedScriptData(cx, script, ssd, 1);
+}
+
+/* static */ bool
+JSScript::fullyInitFromEmitter(ExclusiveContext *cx, HandleScript script, BytecodeEmitter *bce)
+{
+    /* The counts of indexed things must be checked during code generation. */
+    JS_ASSERT(bce->atomIndices->count() <= INDEX_LIMIT);
+    JS_ASSERT(bce->objectList.length <= INDEX_LIMIT);
+    JS_ASSERT(bce->regexpList.length <= INDEX_LIMIT);
+
+    uint32_t mainLength = bce->offset();
+    uint32_t prologLength = bce->prologOffset();
+    uint32_t nsrcnotes;
+    if (!FinishTakingSrcNotes(cx, bce, &nsrcnotes))
+        return false;
+    uint32_t natoms = bce->atomIndices->count();
+    if (!partiallyInit(cx, script,
+                       bce->constList.length(), bce->objectList.length, bce->regexpList.length,
+                       bce->tryNoteList.length(), bce->blockScopeList.length(), bce->typesetCount))
+    {
+        return false;
+    }
+
+    JS_ASSERT(script->mainOffset() == 0);
+    script->mainOffset_ = prologLength;
+
+    script->lineno_ = bce->firstLine;
+
+    script->setLength(prologLength + mainLength);
+    script->natoms_ = natoms;
+    SharedScriptData *ssd = SharedScriptData::new_(cx, script->length(), nsrcnotes, natoms);
+    if (!ssd)
+        return false;
+
+    jsbytecode *code = ssd->data;
+    PodCopy<jsbytecode>(code, bce->prolog.code.begin(), prologLength);
+    PodCopy<jsbytecode>(code + prologLength, bce->code().begin(), mainLength);
+    CopySrcNotes(bce, (jssrcnote *)(code + script->length()), nsrcnotes);
+    InitAtomMap(bce->atomIndices.getMap(), ssd->atoms());
+
+    if (!SaveSharedScriptData(cx, script, ssd, nsrcnotes))
+        return false;
+
+    FunctionBox *funbox = bce->sc->isFunctionBox() ? bce->sc->asFunctionBox() : nullptr;
+
+    if (bce->constList.length() != 0)
+        bce->constList.finish(script->consts());
+    if (bce->objectList.length != 0)
+        bce->objectList.finish(script->objects());
+    if (bce->regexpList.length != 0)
+        bce->regexpList.finish(script->regexps());
+    if (bce->tryNoteList.length() != 0)
+        bce->tryNoteList.finish(script->trynotes());
+    if (bce->blockScopeList.length() != 0)
+        bce->blockScopeList.finish(script->blockScopes());
+    script->strict_ = bce->sc->strict;
+    script->explicitUseStrict_ = bce->sc->hasExplicitUseStrict();
+    script->bindingsAccessedDynamically_ = bce->sc->bindingsAccessedDynamically();
+    script->funHasExtensibleScope_ = funbox ? funbox->hasExtensibleScope() : false;
+    script->funNeedsDeclEnvObject_ = funbox ? funbox->needsDeclEnvObject() : false;
+    script->hasSingletons_ = bce->hasSingletons;
+
+    if (funbox) {
+        if (funbox->argumentsHasLocalBinding()) {
+            // This must precede the script->bindings.transfer() call below
+            script->setArgumentsHasVarBinding();
+            if (funbox->definitelyNeedsArgsObj())
+                script->setNeedsArgsObj(true);
+        } else {
+            JS_ASSERT(!funbox->definitelyNeedsArgsObj());
+        }
+
+        script->funLength_ = funbox->length;
+    }
+
+    RootedFunction fun(cx, nullptr);
+    if (funbox) {
+        JS_ASSERT(!bce->script->noScriptRval());
+        script->isGeneratorExp_ = funbox->inGenexpLambda;
+        script->setGeneratorKind(funbox->generatorKind());
+        script->setFunction(funbox->function());
+    }
+
+    // The call to nfixed() depends on the above setFunction() call.
+    if (UINT32_MAX - script->nfixed() < bce->maxStackDepth) {
+        bce->reportError(nullptr, JSMSG_NEED_DIET, "script");
+        return false;
+    }
+    script->nslots_ = script->nfixed() + bce->maxStackDepth;
+
+    for (unsigned i = 0, n = script->bindings.numArgs(); i < n; ++i) {
+        if (script->formalIsAliased(i)) {
+            script->funHasAnyAliasedFormal_ = true;
+            break;
+        }
+    }
+
+    return true;
+}
+
+size_t
+JSScript::computedSizeOfData() const
+{
+    return dataSize();
+}
+
+size_t
+JSScript::sizeOfData(mozilla::MallocSizeOf mallocSizeOf) const
+{
+    return mallocSizeOf(data);
+}
+
+size_t
+JSScript::sizeOfTypeScript(mozilla::MallocSizeOf mallocSizeOf) const
+{
+    return types->sizeOfIncludingThis(mallocSizeOf);
+}
+
+/*
+ * Nb: srcnotes are variable-length.  This function computes the number of
+ * srcnote *slots*, which may be greater than the number of srcnotes.
+ */
+uint32_t
+JSScript::numNotes()
+{
+    jssrcnote *sn;
+    jssrcnote *notes_ = notes();
+    for (sn = notes_; !SN_IS_TERMINATOR(sn); sn = SN_NEXT(sn))
+        continue;
+    return sn - notes_ + 1;    /* +1 for the terminator */
+}
+
+js::GlobalObject&
+JSScript::uninlinedGlobal() const
+{
+    return global();
+}
+
+void
+js::CallNewScriptHook(JSContext *cx, HandleScript script, HandleFunction fun)
+{
+    if (script->selfHosted())
+        return;
+
+    JS_ASSERT(!script->isActiveEval());
+    if (JSNewScriptHook hook = cx->runtime()->debugHooks.newScriptHook) {
+        AutoKeepAtoms keepAtoms(cx->perThreadData);
+        hook(cx, script->filename(), script->lineno(), script, fun,
+             cx->runtime()->debugHooks.newScriptHookData);
+    }
+}
+
+void
+js::CallDestroyScriptHook(FreeOp *fop, JSScript *script)
+{
+    if (script->selfHosted())
+        return;
+
+    // The hook will only call into JS if a GC is not running.
+    if (JSDestroyScriptHook hook = fop->runtime()->debugHooks.destroyScriptHook)
+        hook(fop, script, fop->runtime()->debugHooks.destroyScriptHookData);
+    script->clearTraps(fop);
+}
+
+void
+JSScript::finalize(FreeOp *fop)
+{
+    // NOTE: this JSScript may be partially initialized at this point.  E.g. we
+    // may have created it and partially initialized it with
+    // JSScript::Create(), but not yet finished initializing it with
+    // fullyInitFromEmitter() or fullyInitTrivial().
+
+    CallDestroyScriptHook(fop, this);
+    fop->runtime()->spsProfiler.onScriptFinalized(this);
+
+    if (types)
+        types->destroy();
+
+#ifdef JS_ION
+    jit::DestroyIonScripts(fop, this);
+#endif
+
+    destroyScriptCounts(fop);
+    destroyDebugScript(fop);
+
+    if (data) {
+        JS_POISON(data, 0xdb, computedSizeOfData());
+        fop->free_(data);
+    }
+
+    fop->runtime()->lazyScriptCache.remove(this);
+}
+
+static const uint32_t GSN_CACHE_THRESHOLD = 100;
+
+void
+GSNCache::purge()
+{
+    code = nullptr;
+    if (map.initialized())
+        map.finish();
+}
+
+jssrcnote *
+js::GetSrcNote(GSNCache &cache, JSScript *script, jsbytecode *pc)
+{
+    size_t target = pc - script->code();
+    if (target >= script->length())
+        return nullptr;
+
+    if (cache.code == script->code()) {
+        JS_ASSERT(cache.map.initialized());
+        GSNCache::Map::Ptr p = cache.map.lookup(pc);
+        return p ? p->value() : nullptr;
+    }
+
+    size_t offset = 0;
+    jssrcnote *result;
+    for (jssrcnote *sn = script->notes(); ; sn = SN_NEXT(sn)) {
+        if (SN_IS_TERMINATOR(sn)) {
+            result = nullptr;
+            break;
+        }
+        offset += SN_DELTA(sn);
+        if (offset == target && SN_IS_GETTABLE(sn)) {
+            result = sn;
+            break;
+        }
+    }
+
+    if (cache.code != script->code() && script->length() >= GSN_CACHE_THRESHOLD) {
+        unsigned nsrcnotes = 0;
+        for (jssrcnote *sn = script->notes(); !SN_IS_TERMINATOR(sn);
+             sn = SN_NEXT(sn)) {
+            if (SN_IS_GETTABLE(sn))
+                ++nsrcnotes;
+        }
+        if (cache.code) {
+            JS_ASSERT(cache.map.initialized());
+            cache.map.finish();
+            cache.code = nullptr;
+        }
+        if (cache.map.init(nsrcnotes)) {
+            pc = script->code();
+            for (jssrcnote *sn = script->notes(); !SN_IS_TERMINATOR(sn);
+                 sn = SN_NEXT(sn)) {
+                pc += SN_DELTA(sn);
+                if (SN_IS_GETTABLE(sn))
+                    JS_ALWAYS_TRUE(cache.map.put(pc, sn));
+            }
+            cache.code = script->code();
+        }
+    }
+
+    return result;
+}
+
+jssrcnote *
+js_GetSrcNote(JSContext *cx, JSScript *script, jsbytecode *pc)
+{
+    return GetSrcNote(cx->runtime()->gsnCache, script, pc);
+}
+
+unsigned
+js::PCToLineNumber(unsigned startLine, jssrcnote *notes, jsbytecode *code, jsbytecode *pc,
+                   unsigned *columnp)
+{
+    unsigned lineno = startLine;
+    unsigned column = 0;
+
+    /*
+     * Walk through source notes accumulating their deltas, keeping track of
+     * line-number notes, until we pass the note for pc's offset within
+     * script->code.
+     */
+    ptrdiff_t offset = 0;
+    ptrdiff_t target = pc - code;
+    for (jssrcnote *sn = notes; !SN_IS_TERMINATOR(sn); sn = SN_NEXT(sn)) {
+        offset += SN_DELTA(sn);
+        SrcNoteType type = (SrcNoteType) SN_TYPE(sn);
+        if (type == SRC_SETLINE) {
+            if (offset <= target)
+                lineno = (unsigned) js_GetSrcNoteOffset(sn, 0);
+            column = 0;
+        } else if (type == SRC_NEWLINE) {
+            if (offset <= target)
+                lineno++;
+            column = 0;
+        }
+
+        if (offset > target)
+            break;
+
+        if (type == SRC_COLSPAN) {
+            ptrdiff_t colspan = js_GetSrcNoteOffset(sn, 0);
+
+            if (colspan >= SN_COLSPAN_DOMAIN / 2)
+                colspan -= SN_COLSPAN_DOMAIN;
+            JS_ASSERT(ptrdiff_t(column) + colspan >= 0);
+            column += colspan;
+        }
+    }
+
+    if (columnp)
+        *columnp = column;
+
+    return lineno;
+}
+
+unsigned
+js::PCToLineNumber(JSScript *script, jsbytecode *pc, unsigned *columnp)
+{
+    /* Cope with InterpreterFrame.pc value prior to entering Interpret. */
+    if (!pc)
+        return 0;
+
+    return PCToLineNumber(script->lineno(), script->notes(), script->code(), pc, columnp);
+}
+
+jsbytecode *
+js_LineNumberToPC(JSScript *script, unsigned target)
+{
+    ptrdiff_t offset = 0;
+    ptrdiff_t best = -1;
+    unsigned lineno = script->lineno();
+    unsigned bestdiff = SN_MAX_OFFSET;
+    for (jssrcnote *sn = script->notes(); !SN_IS_TERMINATOR(sn); sn = SN_NEXT(sn)) {
+        /*
+         * Exact-match only if offset is not in the prolog; otherwise use
+         * nearest greater-or-equal line number match.
+         */
+        if (lineno == target && offset >= ptrdiff_t(script->mainOffset()))
+            goto out;
+        if (lineno >= target) {
+            unsigned diff = lineno - target;
+            if (diff < bestdiff) {
+                bestdiff = diff;
+                best = offset;
+            }
+        }
+        offset += SN_DELTA(sn);
+        SrcNoteType type = (SrcNoteType) SN_TYPE(sn);
+        if (type == SRC_SETLINE) {
+            lineno = (unsigned) js_GetSrcNoteOffset(sn, 0);
+        } else if (type == SRC_NEWLINE) {
+            lineno++;
+        }
+    }
+    if (best >= 0)
+        offset = best;
+out:
+    return script->offsetToPC(offset);
+}
+
+JS_FRIEND_API(unsigned)
+js_GetScriptLineExtent(JSScript *script)
+{
+    unsigned lineno = script->lineno();
+    unsigned maxLineNo = lineno;
+    for (jssrcnote *sn = script->notes(); !SN_IS_TERMINATOR(sn); sn = SN_NEXT(sn)) {
+        SrcNoteType type = (SrcNoteType) SN_TYPE(sn);
+        if (type == SRC_SETLINE)
+            lineno = (unsigned) js_GetSrcNoteOffset(sn, 0);
+        else if (type == SRC_NEWLINE)
+            lineno++;
+
+        if (maxLineNo < lineno)
+            maxLineNo = lineno;
+    }
+
+    return 1 + maxLineNo - script->lineno();
+}
+
+void
+js::DescribeScriptedCallerForCompilation(JSContext *cx, MutableHandleScript maybeScript,
+                                         const char **file, unsigned *linenop,
+                                         uint32_t *pcOffset, JSPrincipals **origin,
+                                         LineOption opt)
+{
+    if (opt == CALLED_FROM_JSOP_EVAL) {
+        jsbytecode *pc = nullptr;
+        maybeScript.set(cx->currentScript(&pc));
+        JS_ASSERT(JSOp(*pc) == JSOP_EVAL || JSOp(*pc) == JSOP_SPREADEVAL);
+        JS_ASSERT(*(pc + (JSOp(*pc) == JSOP_EVAL ? JSOP_EVAL_LENGTH
+                                                 : JSOP_SPREADEVAL_LENGTH)) == JSOP_LINENO);
+        *file = maybeScript->filename();
+        *linenop = GET_UINT16(pc + (JSOp(*pc) == JSOP_EVAL ? JSOP_EVAL_LENGTH
+                                                           : JSOP_SPREADEVAL_LENGTH));
+        *pcOffset = pc - maybeScript->code();
+        *origin = maybeScript->originPrincipals();
+        return;
+    }
+
+    NonBuiltinFrameIter iter(cx);
+
+    if (iter.done()) {
+        maybeScript.set(nullptr);
+        *file = nullptr;
+        *linenop = 0;
+        *pcOffset = 0;
+        *origin = cx->compartment()->principals;
+        return;
+    }
+
+    *file = iter.scriptFilename();
+    *linenop = iter.computeLine();
+    *origin = iter.originPrincipals();
+
+    // These values are only used for introducer fields which are debugging
+    // information and can be safely left null for asm.js frames.
+    if (iter.hasScript()) {
+        maybeScript.set(iter.script());
+        *pcOffset = iter.pc() - maybeScript->code();
+    } else {
+        maybeScript.set(nullptr);
+        *pcOffset = 0;
+    }
+}
+
+template <class T>
+static inline T *
+Rebase(JSScript *dst, JSScript *src, T *srcp)
+{
+    size_t off = reinterpret_cast<uint8_t *>(srcp) - src->data;
+    return reinterpret_cast<T *>(dst->data + off);
+}
+
+JSScript *
+js::CloneScript(JSContext *cx, HandleObject enclosingScope, HandleFunction fun, HandleScript src,
+                NewObjectKind newKind /* = GenericObject */)
+{
+    /* NB: Keep this in sync with XDRScript. */
+
+    /* Some embeddings are not careful to use ExposeObjectToActiveJS as needed. */
+    JS_ASSERT(!src->sourceObject()->isMarked(gc::GRAY));
+
+    uint32_t nconsts   = src->hasConsts()   ? src->consts()->length   : 0;
+    uint32_t nobjects  = src->hasObjects()  ? src->objects()->length  : 0;
+    uint32_t nregexps  = src->hasRegexps()  ? src->regexps()->length  : 0;
+    uint32_t ntrynotes = src->hasTrynotes() ? src->trynotes()->length : 0;
+    uint32_t nblockscopes = src->hasBlockScopes() ? src->blockScopes()->length : 0;
+
+    /* Script data */
+
+    size_t size = src->dataSize();
+    uint8_t *data = AllocScriptData(cx, size);
+    if (!data)
+        return nullptr;
+
+    /* Bindings */
+
+    Rooted<Bindings> bindings(cx);
+    InternalHandle<Bindings*> bindingsHandle =
+        InternalHandle<Bindings*>::fromMarkedLocation(bindings.address());
+    if (!Bindings::clone(cx, bindingsHandle, data, src))
+        return nullptr;
+
+    /* Objects */
+
+    AutoObjectVector objects(cx);
+    if (nobjects != 0) {
+        HeapPtrObject *vector = src->objects()->vector;
+        for (unsigned i = 0; i < nobjects; i++) {
+            RootedObject obj(cx, vector[i]);
+            RootedObject clone(cx);
+            if (obj->is<NestedScopeObject>()) {
+                Rooted<NestedScopeObject*> innerBlock(cx, &obj->as<NestedScopeObject>());
+
+                RootedObject enclosingScope(cx);
+                if (NestedScopeObject *enclosingBlock = innerBlock->enclosingNestedScope())
+                    enclosingScope = objects[FindScopeObjectIndex(src, *enclosingBlock)];
+                else
+                    enclosingScope = fun;
+
+                clone = CloneNestedScopeObject(cx, enclosingScope, innerBlock);
+            } else if (obj->is<JSFunction>()) {
+                RootedFunction innerFun(cx, &obj->as<JSFunction>());
+                if (innerFun->isNative()) {
+                    assertSameCompartment(cx, innerFun);
+                    clone = innerFun;
+                } else {
+                    if (innerFun->isInterpretedLazy()) {
+                        AutoCompartment ac(cx, innerFun);
+                        if (!innerFun->getOrCreateScript(cx))
+                            return nullptr;
+                    }
+                    RootedObject staticScope(cx, innerFun->nonLazyScript()->enclosingStaticScope());
+                    StaticScopeIter<CanGC> ssi(cx, staticScope);
+                    RootedObject enclosingScope(cx);
+                    if (ssi.done() || ssi.type() == StaticScopeIter<CanGC>::FUNCTION)
+                        enclosingScope = fun;
+                    else if (ssi.type() == StaticScopeIter<CanGC>::BLOCK)
+                        enclosingScope = objects[FindScopeObjectIndex(src, ssi.block())];
+                    else
+                        enclosingScope = objects[FindScopeObjectIndex(src, ssi.staticWith())];
+
+                    clone = CloneFunctionAndScript(cx, enclosingScope, innerFun);
+                }
+            } else {
+                /*
+                 * Clone object literals emitted for the JSOP_NEWOBJECT opcode. We only emit that
+                 * instead of the less-optimized JSOP_NEWINIT for self-hosted code or code compiled
+                 * with JSOPTION_COMPILE_N_GO set. As we don't clone the latter type of code, this
+                 * case should only ever be hit when cloning objects from self-hosted code.
+                 */
+                clone = CloneObjectLiteral(cx, cx->global(), obj);
+            }
+            if (!clone || !objects.append(clone))
+                return nullptr;
+        }
+    }
+
+    /* RegExps */
+
+    AutoObjectVector regexps(cx);
+    for (unsigned i = 0; i < nregexps; i++) {
+        HeapPtrObject *vector = src->regexps()->vector;
+        for (unsigned i = 0; i < nregexps; i++) {
+            JSObject *clone = CloneScriptRegExpObject(cx, vector[i]->as<RegExpObject>());
+            if (!clone || !regexps.append(clone))
+                return nullptr;
+        }
+    }
+
+    /*
+     * Wrap the script source object as needed. Self-hosted scripts may be
+     * in another runtime, so lazily create a new script source object to
+     * use for them.
+     */
+    RootedObject sourceObject(cx);
+    if (cx->runtime()->isSelfHostingCompartment(src->compartment())) {
+        if (!cx->compartment()->selfHostingScriptSource) {
+            CompileOptions options(cx);
+            FillSelfHostingCompileOptions(options);
+
+            ScriptSourceObject *obj = frontend::CreateScriptSourceObject(cx, options);
+            if (!obj)
+                return nullptr;
+            cx->compartment()->selfHostingScriptSource = obj;
+        }
+        sourceObject = cx->compartment()->selfHostingScriptSource;
+    } else {
+        sourceObject = src->sourceObject();
+        if (!cx->compartment()->wrap(cx, &sourceObject))
+            return nullptr;
+    }
+
+    /* Now that all fallible allocation is complete, create the GC thing. */
+
+    CompileOptions options(cx);
+    options.setOriginPrincipals(src->originPrincipals())
+           .setCompileAndGo(src->compileAndGo())
+           .setSelfHostingMode(src->selfHosted())
+           .setNoScriptRval(src->noScriptRval())
+           .setVersion(src->getVersion());
+
+    RootedScript dst(cx, JSScript::Create(cx, enclosingScope, src->savedCallerFun(),
+                                          options, src->staticLevel(),
+                                          sourceObject, src->sourceStart(), src->sourceEnd()));
+    if (!dst) {
+        js_free(data);
+        return nullptr;
+    }
+
+    dst->bindings = bindings;
+
+    /* This assignment must occur before all the Rebase calls. */
+    dst->data = data;
+    dst->dataSize_ = size;
+    memcpy(data, src->data, size);
+
+    /* Script filenames, bytecodes and atoms are runtime-wide. */
+    dst->setCode(src->code());
+    dst->atoms = src->atoms;
+
+    dst->setLength(src->length());
+    dst->lineno_ = src->lineno();
+    dst->mainOffset_ = src->mainOffset();
+    dst->natoms_ = src->natoms();
+    dst->funLength_ = src->funLength();
+    dst->nTypeSets_ = src->nTypeSets();
+    dst->nslots_ = src->nslots();
+    if (src->argumentsHasVarBinding()) {
+        dst->setArgumentsHasVarBinding();
+        if (src->analyzedArgsUsage())
+            dst->setNeedsArgsObj(src->needsArgsObj());
+    }
+    dst->cloneHasArray(src);
+    dst->strict_ = src->strict();
+    dst->explicitUseStrict_ = src->explicitUseStrict();
+    dst->bindingsAccessedDynamically_ = src->bindingsAccessedDynamically();
+    dst->funHasExtensibleScope_ = src->funHasExtensibleScope();
+    dst->funNeedsDeclEnvObject_ = src->funNeedsDeclEnvObject();
+    dst->funHasAnyAliasedFormal_ = src->funHasAnyAliasedFormal();
+    dst->hasSingletons_ = src->hasSingletons();
+    dst->treatAsRunOnce_ = src->treatAsRunOnce();
+    dst->isGeneratorExp_ = src->isGeneratorExp();
+    dst->setGeneratorKind(src->generatorKind());
+
+    /* Copy over hints. */
+    dst->shouldInline_ = src->shouldInline();
+    dst->shouldCloneAtCallsite_ = src->shouldCloneAtCallsite();
+    dst->isCallsiteClone_ = src->isCallsiteClone();
+
+    if (nconsts != 0) {
+        HeapValue *vector = Rebase<HeapValue>(dst, src, src->consts()->vector);
+        dst->consts()->vector = vector;
+        for (unsigned i = 0; i < nconsts; ++i)
+            JS_ASSERT_IF(vector[i].isMarkable(), vector[i].toString()->isAtom());
+    }
+    if (nobjects != 0) {
+        HeapPtrObject *vector = Rebase<HeapPtr<JSObject> >(dst, src, src->objects()->vector);
+        dst->objects()->vector = vector;
+        for (unsigned i = 0; i < nobjects; ++i)
+            vector[i].init(objects[i]);
+    }
+    if (nregexps != 0) {
+        HeapPtrObject *vector = Rebase<HeapPtr<JSObject> >(dst, src, src->regexps()->vector);
+        dst->regexps()->vector = vector;
+        for (unsigned i = 0; i < nregexps; ++i)
+            vector[i].init(regexps[i]);
+    }
+    if (ntrynotes != 0)
+        dst->trynotes()->vector = Rebase<JSTryNote>(dst, src, src->trynotes()->vector);
+    if (nblockscopes != 0)
+        dst->blockScopes()->vector = Rebase<BlockScopeNote>(dst, src, src->blockScopes()->vector);
+
+    return dst;
+}
+
+bool
+js::CloneFunctionScript(JSContext *cx, HandleFunction original, HandleFunction clone,
+                        NewObjectKind newKind /* = GenericObject */)
+{
+    JS_ASSERT(clone->isInterpreted());
+
+    RootedScript script(cx, clone->nonLazyScript());
+    JS_ASSERT(script);
+    JS_ASSERT(script->compartment() == original->compartment());
+    JS_ASSERT_IF(script->compartment() != cx->compartment(),
+                 !script->enclosingStaticScope());
+
+    RootedObject scope(cx, script->enclosingStaticScope());
+
+    clone->mutableScript().init(nullptr);
+
+    JSScript *cscript = CloneScript(cx, scope, clone, script, newKind);
+    if (!cscript)
+        return false;
+
+    clone->setScript(cscript);
+    cscript->setFunction(clone);
+
+    script = clone->nonLazyScript();
+    CallNewScriptHook(cx, script, clone);
+    RootedGlobalObject global(cx, script->compileAndGo() ? &script->global() : nullptr);
+    Debugger::onNewScript(cx, script, global);
+
+    return true;
+}
+
+DebugScript *
+JSScript::debugScript()
+{
+    JS_ASSERT(hasDebugScript_);
+    DebugScriptMap *map = compartment()->debugScriptMap;
+    JS_ASSERT(map);
+    DebugScriptMap::Ptr p = map->lookup(this);
+    JS_ASSERT(p);
+    return p->value();
+}
+
+DebugScript *
+JSScript::releaseDebugScript()
+{
+    JS_ASSERT(hasDebugScript_);
+    DebugScriptMap *map = compartment()->debugScriptMap;
+    JS_ASSERT(map);
+    DebugScriptMap::Ptr p = map->lookup(this);
+    JS_ASSERT(p);
+    DebugScript *debug = p->value();
+    map->remove(p);
+    hasDebugScript_ = false;
+    return debug;
+}
+
+void
+JSScript::destroyDebugScript(FreeOp *fop)
+{
+    if (hasDebugScript_) {
+        for (jsbytecode *pc = code(); pc < codeEnd(); pc++) {
+            if (BreakpointSite *site = getBreakpointSite(pc)) {
+                /* Breakpoints are swept before finalization. */
+                JS_ASSERT(site->firstBreakpoint() == nullptr);
+                site->clearTrap(fop, nullptr, nullptr);
+                JS_ASSERT(getBreakpointSite(pc) == nullptr);
+            }
+        }
+        fop->free_(releaseDebugScript());
+    }
+}
+
+bool
+JSScript::ensureHasDebugScript(JSContext *cx)
+{
+    if (hasDebugScript_)
+        return true;
+
+    size_t nbytes = offsetof(DebugScript, breakpoints) + length() * sizeof(BreakpointSite*);
+    DebugScript *debug = (DebugScript *) cx->calloc_(nbytes);
+    if (!debug)
+        return false;
+
+    /* Create compartment's debugScriptMap if necessary. */
+    DebugScriptMap *map = compartment()->debugScriptMap;
+    if (!map) {
+        map = cx->new_<DebugScriptMap>();
+        if (!map || !map->init()) {
+            js_free(debug);
+            js_delete(map);
+            return false;
+        }
+        compartment()->debugScriptMap = map;
+    }
+
+    if (!map->putNew(this, debug)) {
+        js_free(debug);
+        return false;
+    }
+    hasDebugScript_ = true; // safe to set this;  we can't fail after this point
+
+    /*
+     * Ensure that any Interpret() instances running on this script have
+     * interrupts enabled. The interrupts must stay enabled until the
+     * debug state is destroyed.
+     */
+    for (ActivationIterator iter(cx->runtime()); !iter.done(); ++iter) {
+        if (iter->isInterpreter())
+            iter->asInterpreter()->enableInterruptsIfRunning(this);
+    }
+
+    return true;
+}
+
+void
+JSScript::setNewStepMode(FreeOp *fop, uint32_t newValue)
+{
+    DebugScript *debug = debugScript();
+    uint32_t prior = debug->stepMode;
+    debug->stepMode = newValue;
+
+    if (!prior != !newValue) {
+#ifdef JS_ION
+        if (hasBaselineScript())
+            baseline->toggleDebugTraps(this, nullptr);
+#endif
+
+        if (!stepModeEnabled() && !debug->numSites)
+            fop->free_(releaseDebugScript());
+    }
+}
+
+bool
+JSScript::setStepModeFlag(JSContext *cx, bool step)
+{
+    if (!ensureHasDebugScript(cx))
+        return false;
+
+    setNewStepMode(cx->runtime()->defaultFreeOp(),
+                   (debugScript()->stepMode & stepCountMask) |
+                   (step ? stepFlagMask : 0));
+    return true;
+}
+
+bool
+JSScript::incrementStepModeCount(JSContext *cx)
+{
+    assertSameCompartment(cx, this);
+    MOZ_ASSERT(cx->compartment()->debugMode());
+
+    if (!ensureHasDebugScript(cx))
+        return false;
+
+    DebugScript *debug = debugScript();
+    uint32_t count = debug->stepMode & stepCountMask;
+    MOZ_ASSERT(((count + 1) & stepCountMask) == count + 1);
+
+    setNewStepMode(cx->runtime()->defaultFreeOp(),
+                   (debug->stepMode & stepFlagMask) |
+                   ((count + 1) & stepCountMask));
+    return true;
+}
+
+void
+JSScript::decrementStepModeCount(FreeOp *fop)
+{
+    DebugScript *debug = debugScript();
+    uint32_t count = debug->stepMode & stepCountMask;
+
+    setNewStepMode(fop,
+                   (debug->stepMode & stepFlagMask) |
+                   ((count - 1) & stepCountMask));
+}
+
+BreakpointSite *
+JSScript::getOrCreateBreakpointSite(JSContext *cx, jsbytecode *pc)
+{
+    if (!ensureHasDebugScript(cx))
+        return nullptr;
+
+    DebugScript *debug = debugScript();
+    BreakpointSite *&site = debug->breakpoints[pcToOffset(pc)];
+
+    if (!site) {
+        site = cx->runtime()->new_<BreakpointSite>(this, pc);
+        if (!site) {
+            js_ReportOutOfMemory(cx);
+            return nullptr;
+        }
+        debug->numSites++;
+    }
+
+    return site;
+}
+
+void
+JSScript::destroyBreakpointSite(FreeOp *fop, jsbytecode *pc)
+{
+    DebugScript *debug = debugScript();
+    BreakpointSite *&site = debug->breakpoints[pcToOffset(pc)];
+    JS_ASSERT(site);
+
+    fop->delete_(site);
+    site = nullptr;
+
+    if (--debug->numSites == 0 && !stepModeEnabled())
+        fop->free_(releaseDebugScript());
+}
+
+void
+JSScript::clearBreakpointsIn(FreeOp *fop, js::Debugger *dbg, JSObject *handler)
+{
+    if (!hasAnyBreakpointsOrStepMode())
+        return;
+
+    for (jsbytecode *pc = code(); pc < codeEnd(); pc++) {
+        BreakpointSite *site = getBreakpointSite(pc);
+        if (site) {
+            Breakpoint *nextbp;
+            for (Breakpoint *bp = site->firstBreakpoint(); bp; bp = nextbp) {
+                nextbp = bp->nextInSite();
+                if ((!dbg || bp->debugger == dbg) && (!handler || bp->getHandler() == handler))
+                    bp->destroy(fop);
+            }
+        }
+    }
+}
+
+bool
+JSScript::hasBreakpointsAt(jsbytecode *pc)
+{
+    BreakpointSite *site = getBreakpointSite(pc);
+    if (!site)
+        return false;
+
+    return site->enabledCount > 0 || site->trapHandler;
+}
+
+void
+JSScript::clearTraps(FreeOp *fop)
+{
+    if (!hasAnyBreakpointsOrStepMode())
+        return;
+
+    for (jsbytecode *pc = code(); pc < codeEnd(); pc++) {
+        BreakpointSite *site = getBreakpointSite(pc);
+        if (site)
+            site->clearTrap(fop);
+    }
+}
+
+void
+JSScript::markChildren(JSTracer *trc)
+{
+    // NOTE: this JSScript may be partially initialized at this point.  E.g. we
+    // may have created it and partially initialized it with
+    // JSScript::Create(), but not yet finished initializing it with
+    // fullyInitFromEmitter() or fullyInitTrivial().
+
+    JS_ASSERT_IF(trc->runtime()->gcStrictCompartmentChecking, zone()->isCollecting());
+
+    for (uint32_t i = 0; i < natoms(); ++i) {
+        if (atoms[i])
+            MarkString(trc, &atoms[i], "atom");
+    }
+
+    if (hasObjects()) {
+        ObjectArray *objarray = objects();
+        MarkObjectRange(trc, objarray->length, objarray->vector, "objects");
+    }
+
+    if (hasRegexps()) {
+        ObjectArray *objarray = regexps();
+        MarkObjectRange(trc, objarray->length, objarray->vector, "objects");
+    }
+
+    if (hasConsts()) {
+        ConstArray *constarray = consts();
+        MarkValueRange(trc, constarray->length, constarray->vector, "consts");
+    }
+
+    if (sourceObject()) {
+        JS_ASSERT(sourceObject()->compartment() == compartment());
+        MarkObject(trc, &sourceObject_, "sourceObject");
+    }
+
+    if (functionNonDelazifying())
+        MarkObject(trc, &function_, "function");
+
+    if (enclosingScopeOrOriginalFunction_)
+        MarkObject(trc, &enclosingScopeOrOriginalFunction_, "enclosing");
+
+    if (maybeLazyScript())
+        MarkLazyScriptUnbarriered(trc, &lazyScript, "lazyScript");
+
+    if (IS_GC_MARKING_TRACER(trc)) {
+        compartment()->mark();
+
+        if (code())
+            MarkScriptData(trc->runtime(), code());
+    }
+
+    bindings.trace(trc);
+
+    if (hasAnyBreakpointsOrStepMode()) {
+        for (unsigned i = 0; i < length(); i++) {
+            BreakpointSite *site = debugScript()->breakpoints[i];
+            if (site && site->trapHandler)
+                MarkValue(trc, &site->trapClosure, "trap closure");
+        }
+    }
+
+#ifdef JS_ION
+    jit::TraceIonScripts(trc, this);
+#endif
+}
+
+void
+LazyScript::markChildren(JSTracer *trc)
+{
+    if (function_)
+        MarkObject(trc, &function_, "function");
+
+    if (sourceObject_)
+        MarkObject(trc, &sourceObject_, "sourceObject");
+
+    if (enclosingScope_)
+        MarkObject(trc, &enclosingScope_, "enclosingScope");
+
+    if (script_)
+        MarkScript(trc, &script_, "realScript");
+
+    HeapPtrAtom *freeVariables = this->freeVariables();
+    for (size_t i = 0; i < numFreeVariables(); i++)
+        MarkString(trc, &freeVariables[i], "lazyScriptFreeVariable");
+
+    HeapPtrFunction *innerFunctions = this->innerFunctions();
+    for (size_t i = 0; i < numInnerFunctions(); i++)
+        MarkObject(trc, &innerFunctions[i], "lazyScriptInnerFunction");
+}
+
+void
+LazyScript::finalize(FreeOp *fop)
+{
+    if (table_)
+        fop->free_(table_);
+}
+
+NestedScopeObject *
+JSScript::getStaticScope(jsbytecode *pc)
+{
+    JS_ASSERT(containsPC(pc));
+
+    if (!hasBlockScopes())
+        return nullptr;
+
+    ptrdiff_t offset = pc - main();
+
+    if (offset < 0)
+        return nullptr;
+
+    BlockScopeArray *scopes = blockScopes();
+    NestedScopeObject *blockChain = nullptr;
+
+    // Find the innermost block chain using a binary search.
+    size_t bottom = 0;
+    size_t top = scopes->length;
+
+    while (bottom < top) {
+        size_t mid = bottom + (top - bottom) / 2;
+        const BlockScopeNote *note = &scopes->vector[mid];
+        if (note->start <= offset) {
+            // Block scopes are ordered in the list by their starting offset, and since
+            // blocks form a tree ones earlier in the list may cover the pc even if
+            // later blocks end before the pc. This only happens when the earlier block
+            // is a parent of the later block, so we need to check parents of |mid| in
+            // the searched range for coverage.
+            size_t check = mid;
+            while (check >= bottom) {
+                const BlockScopeNote *checkNote = &scopes->vector[check];
+                JS_ASSERT(checkNote->start <= offset);
+                if (offset < checkNote->start + checkNote->length) {
+                    // We found a matching block chain but there may be inner ones
+                    // at a higher block chain index than mid. Continue the binary search.
+                    if (checkNote->index == BlockScopeNote::NoBlockScopeIndex)
+                        blockChain = nullptr;
+                    else
+                        blockChain = &getObject(checkNote->index)->as<NestedScopeObject>();
+                    break;
+                }
+                if (checkNote->parent == UINT32_MAX)
+                    break;
+                check = checkNote->parent;
+            }
+            bottom = mid + 1;
+        } else {
+            top = mid;
+        }
+    }
+
+    return blockChain;
+}
+
+void
+JSScript::setArgumentsHasVarBinding()
+{
+    argsHasVarBinding_ = true;
+#ifdef JS_ION
+    needsArgsAnalysis_ = true;
+#else
+    // The arguments analysis is performed by IonBuilder.
+    needsArgsObj_ = true;
+#endif
+}
+
+void
+JSScript::setNeedsArgsObj(bool needsArgsObj)
+{
+    JS_ASSERT_IF(needsArgsObj, argumentsHasVarBinding());
+    needsArgsAnalysis_ = false;
+    needsArgsObj_ = needsArgsObj;
+}
+
+void
+js::SetFrameArgumentsObject(JSContext *cx, AbstractFramePtr frame,
+                            HandleScript script, JSObject *argsobj)
+{
+    /*
+     * Replace any optimized arguments in the frame with an explicit arguments
+     * object. Note that 'arguments' may have already been overwritten.
+     */
+
+    InternalBindingsHandle bindings(script, &script->bindings);
+    const uint32_t var = Bindings::argumentsVarIndex(cx, bindings);
+
+    if (script->varIsAliased(var)) {
+        /*
+         * Scan the script to find the slot in the call object that 'arguments'
+         * is assigned to.
+         */
+        jsbytecode *pc = script->code();
+        while (*pc != JSOP_ARGUMENTS)
+            pc += GetBytecodeLength(pc);
+        pc += JSOP_ARGUMENTS_LENGTH;
+        JS_ASSERT(*pc == JSOP_SETALIASEDVAR);
+
+        // Note that here and below, it is insufficient to only check for
+        // JS_OPTIMIZED_ARGUMENTS, as Ion could have optimized out the
+        // arguments slot.
+        if (IsOptimizedPlaceholderMagicValue(frame.callObj().as<ScopeObject>().aliasedVar(pc)))
+            frame.callObj().as<ScopeObject>().setAliasedVar(cx, pc, cx->names().arguments, ObjectValue(*argsobj));
+    } else {
+        if (IsOptimizedPlaceholderMagicValue(frame.unaliasedLocal(var)))
+            frame.unaliasedLocal(var) = ObjectValue(*argsobj);
+    }
+}
+
+/* static */ bool
+JSScript::argumentsOptimizationFailed(JSContext *cx, HandleScript script)
+{
+    JS_ASSERT(script->functionNonDelazifying());
+    JS_ASSERT(script->analyzedArgsUsage());
+    JS_ASSERT(script->argumentsHasVarBinding());
+
+    /*
+     * It is possible that the arguments optimization has already failed,
+     * everything has been fixed up, but there was an outstanding magic value
+     * on the stack that has just now flowed into an apply. In this case, there
+     * is nothing to do; GuardFunApplySpeculation will patch in the real
+     * argsobj.
+     */
+    if (script->needsArgsObj())
+        return true;
+
+    JS_ASSERT(!script->isGenerator());
+
+    script->needsArgsObj_ = true;
+
+#ifdef JS_ION
+    /*
+     * Since we can't invalidate baseline scripts, set a flag that's checked from
+     * JIT code to indicate the arguments optimization failed and JSOP_ARGUMENTS
+     * should create an arguments object next time.
+     */
+    if (script->hasBaselineScript())
+        script->baselineScript()->setNeedsArgsObj();
+#endif
+
+    /*
+     * By design, the arguments optimization is only made when there are no
+     * outstanding cases of MagicValue(JS_OPTIMIZED_ARGUMENTS) at any points
+     * where the optimization could fail, other than an active invocation of
+     * 'f.apply(x, arguments)'. Thus, there are no outstanding values of
+     * MagicValue(JS_OPTIMIZED_ARGUMENTS) on the stack. However, there are
+     * three things that need fixup:
+     *  - there may be any number of activations of this script that don't have
+     *    an argsObj that now need one.
+     *  - jit code compiled (and possible active on the stack) with the static
+     *    assumption of !script->needsArgsObj();
+     *  - type inference data for the script assuming script->needsArgsObj
+     */
+    for (AllFramesIter i(cx); !i.done(); ++i) {
+        /*
+         * We cannot reliably create an arguments object for Ion activations of
+         * this script.  To maintain the invariant that "script->needsArgsObj
+         * implies fp->hasArgsObj", the Ion bail mechanism will create an
+         * arguments object right after restoring the BaselineFrame and before
+         * entering Baseline code (in jit::FinishBailoutToBaseline).
+         */
+        if (i.isIon())
+            continue;
+        AbstractFramePtr frame = i.abstractFramePtr();
+        if (frame.isFunctionFrame() && frame.script() == script) {
+            ArgumentsObject *argsobj = ArgumentsObject::createExpected(cx, frame);
+            if (!argsobj) {
+                /*
+                 * We can't leave stack frames with script->needsArgsObj but no
+                 * arguments object. It is, however, safe to leave frames with
+                 * an arguments object but !script->needsArgsObj.
+                 */
+                script->needsArgsObj_ = false;
+                return false;
+            }
+
+            SetFrameArgumentsObject(cx, frame, script, argsobj);
+        }
+    }
+
+    return true;
+}
+
+bool
+JSScript::varIsAliased(uint32_t varSlot)
+{
+    return bindings.bindingIsAliased(bindings.numArgs() + varSlot);
+}
+
+bool
+JSScript::formalIsAliased(unsigned argSlot)
+{
+    return bindings.bindingIsAliased(argSlot);
+}
+
+bool
+JSScript::formalLivesInArgumentsObject(unsigned argSlot)
+{
+    return argsObjAliasesFormals() && !formalIsAliased(argSlot);
+}
+
+LazyScript::LazyScript(JSFunction *fun, void *table, uint64_t packedFields, uint32_t begin, uint32_t end, uint32_t lineno, uint32_t column)
+  : script_(nullptr),
+    function_(fun),
+    enclosingScope_(nullptr),
+    sourceObject_(nullptr),
+    table_(table),
+    packedFields_(packedFields),
+    begin_(begin),
+    end_(end),
+    lineno_(lineno),
+    column_(column)
+{
+    JS_ASSERT(begin <= end);
+}
+
+void
+LazyScript::initScript(JSScript *script)
+{
+    JS_ASSERT(script && !script_);
+    script_ = script;
+}
+
+void
+LazyScript::resetScript()
+{
+    JS_ASSERT(script_);
+    script_ = nullptr;
+}
+
+void
+LazyScript::setParent(JSObject *enclosingScope, ScriptSourceObject *sourceObject)
+{
+    JS_ASSERT(!sourceObject_ && !enclosingScope_);
+    JS_ASSERT_IF(enclosingScope, function_->compartment() == enclosingScope->compartment());
+    JS_ASSERT(function_->compartment() == sourceObject->compartment());
+
+    enclosingScope_ = enclosingScope;
+    sourceObject_ = sourceObject;
+}
+
+ScriptSourceObject *
+LazyScript::sourceObject() const
+{
+    return sourceObject_ ? &sourceObject_->as<ScriptSourceObject>() : nullptr;
+}
+
+/* static */ LazyScript *
+LazyScript::CreateRaw(ExclusiveContext *cx, HandleFunction fun,
+                      uint64_t packedFields, uint32_t begin, uint32_t end,
+                      uint32_t lineno, uint32_t column)
+{
+    union {
+        PackedView p;
+        uint64_t packed;
+    };
+
+    packed = packedFields;
+
+    // Reset runtime flags to obtain a fresh LazyScript.
+    p.hasBeenCloned = false;
+    p.treatAsRunOnce = false;
+
+    size_t bytes = (p.numFreeVariables * sizeof(HeapPtrAtom))
+                 + (p.numInnerFunctions * sizeof(HeapPtrFunction));
+
+    ScopedJSFreePtr<void> table(bytes ? cx->malloc_(bytes) : nullptr);
+    if (bytes && !table)
+        return nullptr;
+
+    LazyScript *res = js_NewGCLazyScript(cx);
+    if (!res)
+        return nullptr;
+
+    cx->compartment()->scheduleDelazificationForDebugMode();
+
+    return new (res) LazyScript(fun, table.forget(), packed, begin, end, lineno, column);
+}
+
+/* static */ LazyScript *
+LazyScript::CreateRaw(ExclusiveContext *cx, HandleFunction fun,
+                      uint32_t numFreeVariables, uint32_t numInnerFunctions, JSVersion version,
+                      uint32_t begin, uint32_t end, uint32_t lineno, uint32_t column)
+{
+    union {
+        PackedView p;
+        uint64_t packedFields;
+    };
+
+    p.version = version;
+    p.numFreeVariables = numFreeVariables;
+    p.numInnerFunctions = numInnerFunctions;
+    p.generatorKindBits = GeneratorKindAsBits(NotGenerator);
+    p.strict = false;
+    p.bindingsAccessedDynamically = false;
+    p.hasDebuggerStatement = false;
+    p.directlyInsideEval = false;
+    p.usesArgumentsAndApply = false;
+
+    LazyScript *res = LazyScript::CreateRaw(cx, fun, packedFields, begin, end, lineno, column);
+    JS_ASSERT_IF(res, res->version() == version);
+    return res;
+}
+
+/* static */ LazyScript *
+LazyScript::Create(ExclusiveContext *cx, HandleFunction fun,
+                   uint64_t packedFields, uint32_t begin, uint32_t end,
+                   uint32_t lineno, uint32_t column)
+{
+    // Dummy atom which is not a valid property name.
+    RootedAtom dummyAtom(cx, cx->names().comma);
+
+    // Dummy function which is not a valid function as this is the one which is
+    // holding this lazy script.
+    HandleFunction dummyFun = fun;
+
+    LazyScript *res = LazyScript::CreateRaw(cx, fun, packedFields, begin, end, lineno, column);
+    if (!res)
+        return nullptr;
+
+    // Fill with dummies, to be GC-safe after the initialization of the free
+    // variables and inner functions.
+    size_t i, num;
+    HeapPtrAtom *variables = res->freeVariables();
+    for (i = 0, num = res->numFreeVariables(); i < num; i++)
+        variables[i].init(dummyAtom);
+
+    HeapPtrFunction *functions = res->innerFunctions();
+    for (i = 0, num = res->numInnerFunctions(); i < num; i++)
+        functions[i].init(dummyFun);
+
+    return res;
+}
+
+void
+LazyScript::initRuntimeFields(uint64_t packedFields)
+{
+    union {
+        PackedView p;
+        uint64_t packed;
+    };
+
+    packed = packedFields;
+    p_.hasBeenCloned = p.hasBeenCloned;
+    p_.treatAsRunOnce = p.treatAsRunOnce;
+}
+
+bool
+LazyScript::hasUncompiledEnclosingScript() const
+{
+    // It can happen that we created lazy scripts while compiling an enclosing
+    // script, but we errored out while compiling that script. When we iterate
+    // over lazy script in a compartment, we might see lazy scripts that never
+    // escaped to script and should be ignored.
+    //
+    // If the enclosing scope is a function with a null script or has a script
+    // without code, it was not successfully compiled.
+
+    if (!enclosingScope() || !enclosingScope()->is<JSFunction>())
+        return false;
+
+    JSFunction &fun = enclosingScope()->as<JSFunction>();
+    return fun.isInterpreted() && (!fun.mutableScript() || !fun.nonLazyScript()->code());
+}
+
+uint32_t
+LazyScript::staticLevel(JSContext *cx) const
+{
+    for (StaticScopeIter<NoGC> ssi(enclosingScope()); !ssi.done(); ssi++) {
+        if (ssi.type() == StaticScopeIter<NoGC>::FUNCTION)
+            return ssi.funScript()->staticLevel() + 1;
+    }
+    return 1;
+}
+
+void
+JSScript::updateBaselineOrIonRaw()
+{
+#ifdef JS_ION
+    if (hasIonScript()) {
+        baselineOrIonRaw = ion->method()->raw();
+        baselineOrIonSkipArgCheck = ion->method()->raw() + ion->getSkipArgCheckEntryOffset();
+    } else if (hasBaselineScript()) {
+        baselineOrIonRaw = baseline->method()->raw();
+        baselineOrIonSkipArgCheck = baseline->method()->raw();
+    } else {
+        baselineOrIonRaw = nullptr;
+        baselineOrIonSkipArgCheck = nullptr;
+    }
+#endif
+}
+
+bool
+JSScript::hasLoops()
+{
+    if (!hasTrynotes())
+        return false;
+    JSTryNote *tn = trynotes()->vector;
+    JSTryNote *tnlimit = tn + trynotes()->length;
+    for (; tn < tnlimit; tn++) {
+        if (tn->kind == JSTRY_ITER || tn->kind == JSTRY_LOOP)
+            return true;
+    }
+    return false;
+}
+
+static inline void
+LazyScriptHash(uint32_t lineno, uint32_t column, uint32_t begin, uint32_t end,
+               HashNumber hashes[3])
+{
+    HashNumber hash = lineno;
+    hash = RotateLeft(hash, 4) ^ column;
+    hash = RotateLeft(hash, 4) ^ begin;
+    hash = RotateLeft(hash, 4) ^ end;
+
+    hashes[0] = hash;
+    hashes[1] = RotateLeft(hashes[0], 4) ^ begin;
+    hashes[2] = RotateLeft(hashes[1], 4) ^ end;
+}
+
+void
+LazyScriptHashPolicy::hash(const Lookup &lookup, HashNumber hashes[3])
+{
+    LazyScript *lazy = lookup.lazy;
+    LazyScriptHash(lazy->lineno(), lazy->column(), lazy->begin(), lazy->end(), hashes);
+}
+
+void
+LazyScriptHashPolicy::hash(JSScript *script, HashNumber hashes[3])
+{
+    LazyScriptHash(script->lineno(), script->column(), script->sourceStart(), script->sourceEnd(), hashes);
+}
+
+bool
+LazyScriptHashPolicy::match(JSScript *script, const Lookup &lookup)
+{
+    JSContext *cx = lookup.cx;
+    LazyScript *lazy = lookup.lazy;
+
+    // To be a match, the script and lazy script need to have the same line
+    // and column and to be at the same position within their respective
+    // source blobs, and to have the same source contents and version.
+    //
+    // While the surrounding code in the source may differ, this is
+    // sufficient to ensure that compiling the lazy script will yield an
+    // identical result to compiling the original script.
+    //
+    // Note that the filenames and origin principals of the lazy script and
+    // original script can differ. If there is a match, these will be fixed
+    // up in the resulting clone by the caller.
+
+    if (script->lineno() != lazy->lineno() ||
+        script->column() != lazy->column() ||
+        script->getVersion() != lazy->version() ||
+        script->sourceStart() != lazy->begin() ||
+        script->sourceEnd() != lazy->end())
+    {
+        return false;
+    }
+
+    SourceDataCache::AutoHoldEntry holder;
+
+    const jschar *scriptChars = script->scriptSource()->chars(cx, holder);
+    if (!scriptChars)
+        return false;
+
+    const jschar *lazyChars = lazy->source()->chars(cx, holder);
+    if (!lazyChars)
+        return false;
+
+    size_t begin = script->sourceStart();
+    size_t length = script->sourceEnd() - begin;
+    return !memcmp(scriptChars + begin, lazyChars + begin, length);
+}