Issue #618 - Simplify module resolve hook to be a function pointer

This is an ahead-of time port to try and address #1624.
This is based on BZ 1461751 and Jon Coppeard's work in it.

4 files changed, 15 insertions, 23 deletions

diff --git a/js/src/vm/GlobalObject.h b/js/src/vm/GlobalObject.h
index 720f63e69..a9f07d495 100644
--- a/js/src/vm/GlobalObject.h
+++ b/js/src/vm/GlobalObject.h
@@ -119,7 +119,6 @@ class GlobalObject : public NativeObject
         DEBUGGERS,
         INTRINSICS,
         FOR_OF_PIC_CHAIN,
-        MODULE_RESOLVE_HOOK,
         WINDOW_PROXY,
         GLOBAL_THIS_RESOLVED,
 
@@ -879,19 +878,6 @@ class GlobalObject : public NativeObject
         setReservedSlot(WINDOW_PROXY, ObjectValue(*windowProxy));
     }
 
-    void setModuleResolveHook(HandleFunction hook) {
-        MOZ_ASSERT(hook);
-        setSlot(MODULE_RESOLVE_HOOK, ObjectValue(*hook));
-    }
-
-    JSFunction* moduleResolveHook() {
-        Value value = getSlotRef(MODULE_RESOLVE_HOOK);
-        if (value.isUndefined())
-            return nullptr;
-
-        return &value.toObject().as<JSFunction>();
-    }
-
     // Returns either this global's star-generator function prototype, or null
     // if that object was never created.  Dodgy; for use only in also-dodgy
     // GlobalHelperThreadState::mergeParseTaskCompartment().
diff --git a/js/src/vm/Runtime.cpp b/js/src/vm/Runtime.cpp
index 284a4f3d7..5e0246b85 100644
--- a/js/src/vm/Runtime.cpp
+++ b/js/src/vm/Runtime.cpp
@@ -241,8 +241,10 @@ JSRuntime::JSRuntime(JSRuntime* parentRuntime)
     lastAnimationTime(0),
     performanceMonitoring(thisFromCtor()),
     ionLazyLinkListSize_(0),
-    stackFormat_(parentRuntime ? js::StackFormat::Default
-                               : js::StackFormat::SpiderMonkey)
+    stackFormat_(parentRuntime ?
+                 js::StackFormat::Default :
+                 js::StackFormat::SpiderMonkey),
+    moduleResolveHook()
 {
     setGCStoreBufferPtr(&gc.storeBuffer);
 
diff --git a/js/src/vm/Runtime.h b/js/src/vm/Runtime.h
index e60371e38..247a2dc9d 100644
--- a/js/src/vm/Runtime.h
+++ b/js/src/vm/Runtime.h
@@ -1294,6 +1294,9 @@ struct JSRuntime : public JS::shadow::Runtime,
     // For inherited heap state accessors.
     friend class js::gc::AutoTraceSession;
     friend class JS::AutoEnterCycleCollection;
+
+    // The implementation-defined abstract operation HostResolveImportedModule.
+    JS::ModuleResolveHook moduleResolveHook;
 };
 
 namespace js {
diff --git a/js/src/vm/SelfHosting.cpp b/js/src/vm/SelfHosting.cpp
index 50b0c01de..f324a0a67 100644
--- a/js/src/vm/SelfHosting.cpp
+++ b/js/src/vm/SelfHosting.cpp
@@ -2026,25 +2026,26 @@ intrinsic_HostResolveImportedModule(JSContext* cx, unsigned argc, Value* vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     MOZ_ASSERT(args.length() == 2);
-    MOZ_ASSERT(args[0].toObject().is<ModuleObject>());
-    MOZ_ASSERT(args[1].isString());
+    RootedModuleObject module(cx, &args[0].toObject().as<ModuleObject>());
+    RootedString specifier(cx, args[1].toString());
 
-    RootedFunction moduleResolveHook(cx, cx->global()->moduleResolveHook());
+    JS::ModuleResolveHook moduleResolveHook = cx->runtime()->moduleResolveHook;
     if (!moduleResolveHook) {
         JS_ReportErrorASCII(cx, "Module resolve hook not set");
         return false;
     }
 
-    RootedValue result(cx);
-    if (!JS_CallFunction(cx, nullptr, moduleResolveHook, args, &result))
+    RootedObject result(cx);
+    result = moduleResolveHook(cx, module, specifier);
+    if (!result)
         return false;
 
-    if (!result.isObject() || !result.toObject().is<ModuleObject>()) {
+    if (!result->is<ModuleObject>()) {
         JS_ReportErrorASCII(cx, "Module resolve hook did not return Module object");
         return false;
     }
 
-    args.rval().set(result);
+    args.rval().setObject(*result);
     return true;
 }