Bug 934799 - Part 1: Lazify delazifying lazy scripts in debug mode. (r=jimb)

js/src/frontend/BytecodeCompiler.cpp

@@ -141,8 +141,7 @@ CanLazilyParse(ExclusiveContext *cx, const ReadOnlyCompileOptions &options)
 {
     return options.canLazilyParse &&
         options.compileAndGo &&
-        options.sourcePolicy == CompileOptions::SAVE_SOURCE &&
+        options.sourcePolicy == CompileOptions::SAVE_SOURCE;
-        !cx->compartment()->debugMode();
 }
 
 void

js/src/frontend/BytecodeEmitter.cpp

@@ -1788,7 +1788,9 @@ BytecodeEmitter::tellDebuggerAboutCompiledScript(ExclusiveContext *cx)
 
     RootedFunction function(cx, script->function());
     CallNewScriptHook(cx->asJSContext(), script, function);
-    if (!parent) {
+    // Lazy scripts are never top level (despite always being invoked with a
+    // nullptr parent), and so the hook should never be fired.
+    if (emitterMode != LazyFunction && !parent) {
         GlobalObject *compileAndGoGlobal = nullptr;
         if (script->compileAndGo)
             compileAndGoGlobal = &script->global();

js/src/jscompartment.cpp

@@ -673,20 +673,20 @@ CreateLazyScriptsForCompartment(JSContext *cx)
 {
     AutoObjectVector lazyFunctions(cx);
 
-    // Find all root lazy functions in the compartment: those which have not been
+    // Find all live lazy scripts in the compartment, and via them all root
-    // compiled and which have a source object, indicating that their parent has
+    // lazy functions in the compartment: those which have not been compiled
-    // been compiled.
+    // and which have a source object, indicating that their parent has been
-    for (gc::CellIter i(cx->zone(), JSFunction::FinalizeKind); !i.done(); i.next()) {
+    // compiled.
-        JSObject *obj = i.get<JSObject>();
+    for (gc::CellIter i(cx->zone(), gc::FINALIZE_LAZY_SCRIPT); !i.done(); i.next()) {
-        if (obj->compartment() == cx->compartment() && obj->is<JSFunction>()) {
+        LazyScript *lazy = i.get<LazyScript>();
-            JSFunction *fun = &obj->as<JSFunction>();
+        JSFunction *fun = lazy->function();
-            if (fun->isInterpretedLazy()) {
+        if (fun->compartment() == cx->compartment() &&
-                LazyScript *lazy = fun->lazyScriptOrNull();
+            lazy->sourceObject() && !lazy->maybeScript())
-                if (lazy && lazy->sourceObject() && !lazy->maybeScript()) {
+        {
-                    if (!lazyFunctions.append(fun))
+            MOZ_ASSERT(fun->isInterpretedLazy());
-                        return false;
+            MOZ_ASSERT(lazy == fun->lazyScriptOrNull());
-                }
+            if (!lazyFunctions.append(fun))
-            }
+                return false;
         }
     }
 
@@ -708,19 +708,16 @@ CreateLazyScriptsForCompartment(JSContext *cx)
             return false;
     }
 
-    // Repoint any clones of the original functions to their new script.
+    return true;
-    for (gc::CellIter i(cx->zone(), JSFunction::FinalizeKind); !i.done(); i.next()) {
+}
-        JSObject *obj = i.get<JSObject>();
-        if (obj->compartment() == cx->compartment() && obj->is<JSFunction>()) {
-            JSFunction *fun = &obj->as<JSFunction>();
-            if (fun->isInterpretedLazy()) {
-                LazyScript *lazy = fun->lazyScriptOrNull();
-                if (lazy && lazy->maybeScript())
-                    fun->existingScript();
-            }
-        }
-    }
 
+bool
+JSCompartment::ensureDelazifyScriptsForDebugMode(JSContext *cx)
+{
+    MOZ_ASSERT(cx->compartment() == this);
+    if ((debugModeBits & DebugNeedDelazification) && !CreateLazyScriptsForCompartment(cx))
+        return false;
+    debugModeBits &= ~DebugNeedDelazification;
     return true;
 }
 
@@ -728,7 +725,7 @@ bool
 JSCompartment::setDebugModeFromC(JSContext *cx, bool b, AutoDebugModeInvalidation &invalidate)
 {
     bool enabledBefore = debugMode();
-    bool enabledAfter = (debugModeBits & ~unsigned(DebugFromC)) || b;
+    bool enabledAfter = (debugModeBits & DebugModeFromMask & ~DebugFromC) || b;
 
     // Debug mode can be enabled only when no scripts from the target
     // compartment are on the stack. It would even be incorrect to discard just
@@ -747,11 +744,9 @@ JSCompartment::setDebugModeFromC(JSContext *cx, bool b, AutoDebugModeInvalidatio
             JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_DEBUG_NOT_IDLE);
             return false;
         }
-        if (enabledAfter && !CreateLazyScriptsForCompartment(cx))
-            return false;
     }
 
-    debugModeBits = (debugModeBits & ~unsigned(DebugFromC)) | (b ? DebugFromC : 0);
+    debugModeBits = (debugModeBits & ~DebugFromC) | (b ? DebugFromC : 0);
     JS_ASSERT(debugMode() == enabledAfter);
     if (enabledBefore != enabledAfter) {
         updateForDebugMode(cx->runtime()->defaultFreeOp(), invalidate);
@@ -801,8 +796,6 @@ JSCompartment::addDebuggee(JSContext *cx,
     Rooted<GlobalObject*> global(cx, globalArg);
 
     bool wasEnabled = debugMode();
-    if (!wasEnabled && !CreateLazyScriptsForCompartment(cx))
-        return false;
     if (!debuggees.put(global)) {
         js_ReportOutOfMemory(cx);
         return false;

js/src/jscompartment.h

@@ -278,7 +278,13 @@ struct JSCompartment
     js::WeakMapBase              *gcWeakMapList;
 
   private:
-    enum { DebugFromC = 1, DebugFromJS = 2 };
+    enum {
+        DebugFromC = 1 << 0,
+        DebugFromJS = 1 << 1,
+        DebugNeedDelazification = 1 << 2
+    };
+
+    static const unsigned DebugModeFromMask = DebugFromC | DebugFromJS;
 
     unsigned                     debugModeBits;  // see debugMode() below
 
@@ -356,13 +362,34 @@ struct JSCompartment
      * by Debugger objects. Therefore debugModeBits has the DebugFromC bit set
      * if the C API wants debug mode and the DebugFromJS bit set if debuggees
      * is non-empty.
+     *
+     * When toggling on, DebugNeedDelazification is set to signal that
+     * Debugger methods which depend on seeing all scripts (like findScripts)
+     * need to delazify the scripts in the compartment first.
      */
-    bool debugMode() const { return !!debugModeBits; }
+    bool debugMode() const {
+        return !!(debugModeBits & DebugModeFromMask);
+    }
 
     /* True if any scripts from this compartment are on the JS stack. */
     bool hasScriptsOnStack();
 
+    /*
+     * Schedule the compartment to be delazified. Called from
+     * LazyScript::Create.
+     */
+    void scheduleDelazificationForDebugMode() {
+        debugModeBits |= DebugNeedDelazification;
+    }
+
+    /*
+     * If we scheduled delazification for turning on debug mode, delazify all
+     * scripts.
+     */
+    bool ensureDelazifyScriptsForDebugMode(JSContext *cx);
+
   private:
+
     /* This is called only when debugMode() has just toggled. */
     void updateForDebugMode(js::FreeOp *fop, js::AutoDebugModeInvalidation &invalidate);
 

js/src/jsscript.cpp

@@ -3043,6 +3043,8 @@ LazyScript::Create(ExclusiveContext *cx, HandleFunction fun,
     if (!res)
         return nullptr;
 
+    cx->compartment()->scheduleDelazificationForDebugMode();
+
     return new (res) LazyScript(fun, table, numFreeVariables, numInnerFunctions, version,
                                 begin, end, lineno, column);
 }

js/src/vm/Debugger.cpp

@@ -97,6 +97,25 @@ ReportMoreArgsNeeded(JSContext *cx, const char *name, unsigned required)
     return false;
 }
 
+static inline bool
+EnsureFunctionHasScript(JSContext *cx, JSFunction *fun)
+{
+    if (fun->isInterpretedLazy()) {
+        AutoCompartment ac(cx, fun);
+        return !!fun->getOrCreateScript(cx);
+    }
+    return true;
+}
+
+static inline JSScript *
+GetOrCreateFunctionScript(JSContext *cx, JSFunction *fun)
+{
+    MOZ_ASSERT(fun->isInterpreted());
+    if (!EnsureFunctionHasScript(cx, fun))
+        return nullptr;
+    return fun->nonLazyScript();
+}
+
 #define REQUIRE_ARGC(name, n)                                                 \
     JS_BEGIN_MACRO                                                            \
         if (argc < (n))                                                       \
@@ -686,6 +705,9 @@ Debugger::wrapDebuggeeValue(JSContext *cx, MutableHandleValue vp)
     if (vp.isObject()) {
         RootedObject obj(cx, &vp.toObject());
 
+        if (obj->is<JSFunction>() && !EnsureFunctionHasScript(cx, &obj->as<JSFunction>()))
+            return false;
+
         ObjectWeakMap::AddPtr p = objects.lookupForAdd(obj);
         if (p) {
             vp.setObject(*p->value);
@@ -2403,10 +2425,14 @@ class Debugger::ScriptQuery {
         if (!prepareQuery())
             return false;
 
+        JSCompartment *singletonComp = nullptr;
+        if (compartments.count() == 1)
+            singletonComp = compartments.all().front();
+
         /* Search each compartment for debuggee scripts. */
         vector = v;
         oom = false;
-        IterateScripts(cx->runtime(), nullptr, this, considerScript);
+        IterateScripts(cx->runtime(), singletonComp, this, considerScript);
         if (oom) {
             js_ReportOutOfMemory(cx);
             return false;
@@ -2476,10 +2502,21 @@ class Debugger::ScriptQuery {
     /* Indicates whether OOM has occurred while matching. */
     bool oom;
 
+    bool addCompartment(JSCompartment *comp) {
+        {
+            // All scripts in the debuggee compartment must be visible, so
+            // delazify everything.
+            AutoCompartment ac(cx, comp);
+            if (!comp->ensureDelazifyScriptsForDebugMode(cx))
+                return false;
+        }
+        return compartments.put(comp);
+    }
+
     /* Arrange for this ScriptQuery to match only scripts that run in |global|. */
     bool matchSingleGlobal(GlobalObject *global) {
         JS_ASSERT(compartments.count() == 0);
-        if (!compartments.put(global->compartment())) {
+        if (!addCompartment(global->compartment())) {
             js_ReportOutOfMemory(cx);
             return false;
         }
@@ -2494,7 +2531,7 @@ class Debugger::ScriptQuery {
         JS_ASSERT(compartments.count() == 0);
         /* Build our compartment set from the debugger's set of debuggee globals. */
         for (GlobalObjectSet::Range r = debugger->debuggees.all(); !r.empty(); r.popFront()) {
-            if (!compartments.put(r.front()->compartment())) {
+            if (!addCompartment(r.front()->compartment())) {
                 js_ReportOutOfMemory(cx);
                 return false;
             }
@@ -2937,8 +2974,10 @@ DebuggerScript_getChildScripts(JSContext *cx, unsigned argc, Value *vp)
         for (uint32_t i = script->innerObjectsStart(); i < objects->length; i++) {
             obj = objects->vector[i];
             if (obj->is<JSFunction>()) {
-                fun = static_cast<JSFunction *>(obj.get());
+                fun = &obj->as<JSFunction>();
-                funScript = fun->nonLazyScript();
+                funScript = GetOrCreateFunctionScript(cx, fun);
+                if (!funScript)
+                    return false;
                 s = dbg->wrapScript(cx, funScript);
                 if (!s || !js_NewbornArrayPush(cx, result, ObjectValue(*s)))
                     return false;
@@ -4659,14 +4698,9 @@ DebuggerObject_getParameterNames(JSContext *cx, unsigned argc, Value *vp)
     result->ensureDenseInitializedLength(cx, 0, fun->nargs);
 
     if (fun->isInterpreted()) {
-        RootedScript script(cx);
+        RootedScript script(cx, GetOrCreateFunctionScript(cx, fun));
-
+        if (!script)
-        {
+            return false;
-            AutoCompartment ac(cx, fun);
-            script = fun->getOrCreateScript(cx);
-            if (!script)
-                return false;
-        }
 
         JS_ASSERT(fun->nargs == script->bindings.numArgs());
 
@@ -4708,15 +4742,9 @@ DebuggerObject_getScript(JSContext *cx, unsigned argc, Value *vp)
         return true;
     }
 
-    RootedScript script(cx);
+    RootedScript script(cx, GetOrCreateFunctionScript(cx, fun));
-
+    if (!script)
-    {
+        return false;
-        AutoCompartment ac(cx, obj);
-
-        script = fun->getOrCreateScript(cx);
-        if (!script)
-            return false;
-    }
 
     /* Only hand out debuggee scripts. */
     if (!dbg->observesScript(script)) {