Bug 1479058 Part 7 - Store time warp target on Error objects, r=jandem.

--HG--
extra : rebase_source : b848b53d363797e2894630b4f9dac59a51481f6d

js/src/jsapi.h

@@ -5587,6 +5587,15 @@ namespace JS {
 extern JS_PUBLIC_API(JSObject*)
 ExceptionStackOrNull(JS::HandleObject obj);
 
+/**
+ * If this process is recording or replaying and the given value is an
+ * exception object (or an unwrappable cross-compartment wrapper for one),
+ * return the point where this exception was thrown, for time warping later.
+ * Returns zero otherwise.
+ */
+extern JS_PUBLIC_API(uint64_t)
+ExceptionTimeWarpTarget(JS::HandleValue exn);
+
 } /* namespace JS */
 
 /**

js/src/jsexn.cpp

@@ -426,6 +426,19 @@ JS::ExceptionStackOrNull(HandleObject objArg)
     return obj->as<ErrorObject>().stack();
 }
 
+JS_PUBLIC_API(uint64_t)
+JS::ExceptionTimeWarpTarget(JS::HandleValue value)
+{
+    if (!value.isObject())
+        return 0;
+
+    JSObject* obj = CheckedUnwrap(&value.toObject());
+    if (!obj || !obj->is<ErrorObject>())
+        return 0;
+
+    return obj->as<ErrorObject>().timeWarpTarget();
+}
+
 bool
 Error(JSContext* cx, unsigned argc, Value* vp)
 {

js/src/vm/ErrorObject-inl.h

@@ -38,4 +38,11 @@ js::ErrorObject::stack() const
     return getReservedSlotRef(STACK_SLOT).toObjectOrNull();
 }
 
+inline uint64_t
+js::ErrorObject::timeWarpTarget() const
+{
+    const HeapSlot& slot = getReservedSlotRef(TIME_WARP_SLOT);
+    return slot.isDouble() ? slot.toDouble() : 0;
+}
+
 #endif /* vm_ErrorObject_inl_h */

js/src/vm/ErrorObject.cpp

@@ -84,6 +84,16 @@ js::ErrorObject::init(JSContext* cx, Handle<ErrorObject*> obj, JSExnType type,
     if (message)
         obj->setSlotWithType(cx, messageShape, StringValue(message));
 
+    // When recording/replaying and running on the main thread, get a counter
+    // which the devtools can use to warp to this point in the future.
+    if (mozilla::recordreplay::IsRecordingOrReplaying() && !cx->runtime()->parentRuntime) {
+        uint64_t timeWarpTarget = mozilla::recordreplay::NewTimeWarpTarget();
+
+        // Make sure we don't truncate the time warp target by storing it as a double.
+        MOZ_RELEASE_ASSERT(timeWarpTarget < uint64_t(DOUBLE_INTEGRAL_PRECISION_LIMIT));
+        obj->initReservedSlot(TIME_WARP_SLOT, DoubleValue(timeWarpTarget));
+    }
+
     return true;
 }
 

js/src/vm/ErrorObject.h

@@ -50,8 +50,9 @@ class ErrorObject : public NativeObject
     static const uint32_t LINENUMBER_SLOT       = FILENAME_SLOT + 1;
     static const uint32_t COLUMNNUMBER_SLOT     = LINENUMBER_SLOT + 1;
     static const uint32_t MESSAGE_SLOT          = COLUMNNUMBER_SLOT + 1;
+    static const uint32_t TIME_WARP_SLOT        = MESSAGE_SLOT + 1;
 
-    static const uint32_t RESERVED_SLOTS = MESSAGE_SLOT + 1;
+    static const uint32_t RESERVED_SLOTS = TIME_WARP_SLOT + 1;
 
   public:
     static const Class classes[JSEXN_ERROR_LIMIT];
@@ -99,6 +100,7 @@ class ErrorObject : public NativeObject
     inline uint32_t lineNumber() const;
     inline uint32_t columnNumber() const;
     inline JSObject * stack() const;
+    inline uint64_t timeWarpTarget() const;
 
     JSString * getMessage() const {
         const HeapSlot& slot = getReservedSlotRef(MESSAGE_SLOT);