Bug 726115 - Make the tracer callback take an indirect pointer; r=billm

This will be required for a tracer to move objects.  This patch only
updates the tracer interface and users of the interface.

--HG--
extra : rebase_source : 844d819a80cf6cb1dba0d07ea97f647802c66d40

js/src/jsapi.cpp

@@ -2642,8 +2642,9 @@ typedef struct JSDumpingTracer {
 } JSDumpingTracer;
 
 static void
-DumpNotify(JSTracer *trc, void *thing, JSGCTraceKind kind)
+DumpNotify(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
+    void *thing = *thingp;
     JSDumpingTracer *dtrc;
     JSContext *cx;
     JSDHashEntryStub *entry;

js/src/jsapi.h

@@ -3098,7 +3098,7 @@ JSVAL_TRACE_KIND(jsval v)
  * wants to use the existing liveness of entries.
  */
 typedef void
-(* JSTraceCallback)(JSTracer *trc, void *thing, JSGCTraceKind kind);
+(* JSTraceCallback)(JSTracer *trc, void **thingp, JSGCTraceKind kind);
 
 struct JSTracer {
     JSRuntime           *runtime;

js/src/jsfriendapi.cpp

@@ -483,13 +483,14 @@ struct JSDumpHeapTracer : public JSTracer {
 };
 
 static void
-DumpHeapVisitChild(JSTracer *trc, void *thing, JSGCTraceKind kind);
+DumpHeapVisitChild(JSTracer *trc, void **thingp, JSGCTraceKind kind);
 
 static void
-DumpHeapPushIfNew(JSTracer *trc, void *thing, JSGCTraceKind kind)
+DumpHeapPushIfNew(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
     JS_ASSERT(trc->callback == DumpHeapPushIfNew ||
               trc->callback == DumpHeapVisitChild);
+    void *thing = *thingp;
     JSDumpHeapTracer *dtrc = static_cast<JSDumpHeapTracer *>(trc);
 
     /*
@@ -509,13 +510,13 @@ DumpHeapPushIfNew(JSTracer *trc, void *thing, JSGCTraceKind kind)
 }
 
 static void
-DumpHeapVisitChild(JSTracer *trc, void *thing, JSGCTraceKind kind)
+DumpHeapVisitChild(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
     JS_ASSERT(trc->callback == DumpHeapVisitChild);
     JSDumpHeapTracer *dtrc = static_cast<JSDumpHeapTracer *>(trc);
     const char *edgeName = JS_GetTraceEdgeName(dtrc, dtrc->buffer, sizeof(dtrc->buffer));
-    fprintf(dtrc->output, "> %p %s\n", (void *)thing, edgeName);
+    fprintf(dtrc->output, "> %p %s\n", *thingp, edgeName);
-    DumpHeapPushIfNew(dtrc, thing, kind);
+    DumpHeapPushIfNew(dtrc, thingp, kind);
 }
 
 void

js/src/jsgc.cpp

@@ -1815,7 +1815,7 @@ GCMarker::markDelayedChildren()
 
 #ifdef DEBUG
 static void
-EmptyMarkCallback(JSTracer *trc, void *thing, JSGCTraceKind kind)
+EmptyMarkCallback(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
 }
 #endif
@@ -3393,7 +3393,7 @@ struct VerifyTracer : JSTracer {
  * node.
  */
 static void
-AccumulateEdge(JSTracer *jstrc, void *thing, JSGCTraceKind kind)
+AccumulateEdge(JSTracer *jstrc, void **thingp, JSGCTraceKind kind)
 {
     VerifyTracer *trc = (VerifyTracer *)jstrc;
 
@@ -3406,7 +3406,7 @@ AccumulateEdge(JSTracer *jstrc, void *thing, JSGCTraceKind kind)
     VerifyNode *node = trc->curnode;
     uint32_t i = node->count;
 
-    node->edges[i].thing = thing;
+    node->edges[i].thing = *thingp;
     node->edges[i].kind = kind;
     node->edges[i].label = trc->debugPrinter ? NULL : (char *)trc->debugPrintArg;
     node->count++;
@@ -3547,9 +3547,9 @@ oom:
 }
 
 static void
-CheckAutorooter(JSTracer *jstrc, void *thing, JSGCTraceKind kind)
+CheckAutorooter(JSTracer *jstrc, void **thingp, JSGCTraceKind kind)
 {
-    static_cast<Cell *>(thing)->markIfUnmarked();
+    static_cast<Cell *>(*thingp)->markIfUnmarked();
 }
 
 /*
@@ -3560,13 +3560,13 @@ CheckAutorooter(JSTracer *jstrc, void *thing, JSGCTraceKind kind)
  * modified) must point to marked objects.
  */
 static void
-CheckEdge(JSTracer *jstrc, void *thing, JSGCTraceKind kind)
+CheckEdge(JSTracer *jstrc, void **thingp, JSGCTraceKind kind)
 {
     VerifyTracer *trc = (VerifyTracer *)jstrc;
     VerifyNode *node = trc->curnode;
 
     for (uint32_t i = 0; i < node->count; i++) {
-        if (node->edges[i].thing == thing) {
+        if (node->edges[i].thing == *thingp) {
             JS_ASSERT(node->edges[i].kind == kind);
             node->edges[i].thing = NULL;
             return;

js/src/jsgcmark.cpp

@@ -106,10 +106,13 @@ MarkInternal(JSTracer *trc, T *thing)
      * GC.
      */
     if (!rt->gcCurrentCompartment || thing->compartment() == rt->gcCurrentCompartment) {
-        if (IS_GC_MARKING_TRACER(trc))
+        if (IS_GC_MARKING_TRACER(trc)) {
             PushMarkStack(static_cast<GCMarker *>(trc), thing);
-        else
+        } else {
-            trc->callback(trc, (void *)thing, GetGCThingTraceKind(thing));
+            void *tmp = (void *)thing;
+            trc->callback(trc, &tmp, GetGCThingTraceKind(thing));
+            JS_ASSERT(tmp == thing);
+        }
     }
 
 #ifdef DEBUG

js/src/shell/js.cpp

@@ -1446,11 +1446,12 @@ typedef struct JSCountHeapTracer {
 } JSCountHeapTracer;
 
 static void
-CountHeapNotify(JSTracer *trc, void *thing, JSGCTraceKind kind)
+CountHeapNotify(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
     JSCountHeapTracer *countTracer;
     JSDHashEntryStub *entry;
     JSCountHeapNode *node;
+    void *thing = *thingp;
 
     JS_ASSERT(trc->callback == CountHeapNotify);
     countTracer = (JSCountHeapTracer *)trc;

js/src/shell/jsheaptools.cpp

@@ -232,7 +232,7 @@ class HeapReverser : public JSTracer {
      * A stack of work items. We represent the stack explicitly to avoid
      * overflowing the C++ stack when traversing long chains of objects.
      */
-    Vector<Child> work; 
+    Vector<Child> work;
 
     /* When traverseEdge is called, the Cell and kind at which the edge originated. */
     void *parent;
@@ -249,19 +249,17 @@ class HeapReverser : public JSTracer {
     bool traversalStatus;
 
     /* Static member function wrapping 'traverseEdge'. */
-    static void traverseEdgeWithThis(JSTracer *tracer, void *cell, JSGCTraceKind kind) {
+    static void traverseEdgeWithThis(JSTracer *tracer, void **thingp, JSGCTraceKind kind) {
         HeapReverser *reverser = static_cast<HeapReverser *>(tracer);
-        reverser->traversalStatus = reverser->traverseEdge(cell, kind);
+        reverser->traversalStatus = reverser->traverseEdge(*thingp, kind);
     }
 
     /* Return a jsval representing a node, if possible; otherwise, return JSVAL_VOID. */
     jsval nodeToValue(void *cell, int kind) {
-        if (kind == JSTRACE_OBJECT) {
+        if (kind != JSTRACE_OBJECT)
-            JSObject *object = static_cast<JSObject *>(cell);
-            return OBJECT_TO_JSVAL(object);
-        } else {
             return JSVAL_VOID;
-        }
+        JSObject *object = static_cast<JSObject *>(cell);
+        return OBJECT_TO_JSVAL(object);
     }
 };
 

js/xpconnect/src/nsXPConnect.cpp

@@ -480,9 +480,10 @@ struct NoteWeakMapChildrenTracer : public JSTracer
 };
 
 static void
-TraceWeakMappingChild(JSTracer *trc, void *thing, JSGCTraceKind kind)
+TraceWeakMappingChild(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
     MOZ_ASSERT(trc->callback == TraceWeakMappingChild);
+    void *thing = *thingp;
     NoteWeakMapChildrenTracer *tracer =
         static_cast<NoteWeakMapChildrenTracer *>(trc);
     if (kind == JSTRACE_STRING)
@@ -721,8 +722,9 @@ xpc_GCThingIsGrayCCThing(void *thing)
  * re-coloring.
  */
 static void
-UnmarkGrayChildren(JSTracer *trc, void *thing, JSGCTraceKind kind)
+UnmarkGrayChildren(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
+    void *thing = *thingp;
     int stackDummy;
     if (!JS_CHECK_STACK_SIZE(js::GetContextStackLimit(trc->context), &stackDummy)) {
         /*
@@ -776,9 +778,10 @@ struct TraversalTracer : public JSTracer
 };
 
 static void
-NoteJSChild(JSTracer *trc, void *thing, JSGCTraceKind kind)
+NoteJSChild(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
     TraversalTracer *tracer = static_cast<TraversalTracer*>(trc);
+    void *thing = *thingp;
 
     // Don't traverse non-gray objects, unless we want all traces.
     if (!xpc_IsGrayGCThing(thing) && !tracer->cb.WantAllTraces())
@@ -1166,7 +1169,7 @@ struct VerifyTraceXPCGlobalCalledTracer
 };
 
 static void
-VerifyTraceXPCGlobalCalled(JSTracer *trc, void *thing, JSGCTraceKind kind)
+VerifyTraceXPCGlobalCalled(JSTracer *trc, void **thingp, JSGCTraceKind kind)
 {
     // We don't do anything here, we only want to verify that TraceXPCGlobal
     // was called.