Bug 1618038 - Add some |if constexpr| to eliminate |to{,Mutable}Handle| functions on |FakeRooted|. r=sfink

Depends on D64236

Differential Revision: https://phabricator.services.mozilla.com/D64239

--HG--
extra : moz-landing-system : lando

js/src/gc/MaybeRooted.h

@@ -100,10 +100,6 @@ struct DefineComparisonOps<FakeMutableHandle<T>> : std::true_type {
  * Types for a variable that either should or shouldn't be rooted, depending on
  * the template parameter allowGC. Used for implementing functions that can
  * operate on either rooted or unrooted data.
- *
- * The toHandle() and toMutableHandle() functions are for calling functions
- * which require handle types and are only called in the CanGC case. These
- * allow the calling code to type check.
  */
 
 template <typename T, AllowGC allowGC>
@@ -116,10 +112,6 @@ class MaybeRooted<T, CanGC> {
   using RootType = JS::Rooted<T>;
   using MutableHandleType = JS::MutableHandle<T>;
 
-  static JS::Handle<T> toHandle(HandleType v) { return v; }
-
-  static JS::MutableHandle<T> toMutableHandle(MutableHandleType v) { return v; }
-
   template <typename T2>
   static JS::Handle<T2*> downcastHandle(HandleType v) {
     return v.template as<T2>();
@@ -133,12 +125,6 @@ class MaybeRooted<T, NoGC> {
   using RootType = FakeRooted<T>;
   using MutableHandleType = FakeMutableHandle<T>;
 
-  static JS::Handle<T> toHandle(HandleType v) { MOZ_CRASH("Bad conversion"); }
-
-  static JS::MutableHandle<T> toMutableHandle(MutableHandleType v) {
-    MOZ_CRASH("Bad conversion");
-  }
-
   template <typename T2>
   static T2* downcastHandle(HandleType v) {
     return &v->template as<T2>();

js/src/vm/NativeObject-inl.h

@@ -805,28 +805,24 @@ static MOZ_ALWAYS_INLINE bool LookupOwnPropertyInline(
   // id was not found in obj. Try obj's resolve hook, if any.
   if (obj->getClass()->getResolve()) {
     MOZ_ASSERT(!cx->isHelperThreadContext());
-    if (!allowGC) {
+    if constexpr (!allowGC) {
       return false;
-    }
+    } else {
+      bool recursed;
+      if (!CallResolveOp(cx, obj, id, propp, &recursed)) {
+        return false;
+      }
 
-    bool recursed;
-    if (!CallResolveOp(
-            cx, MaybeRooted<NativeObject*, allowGC>::toHandle(obj),
-            MaybeRooted<jsid, allowGC>::toHandle(id),
-            MaybeRooted<PropertyResult, allowGC>::toMutableHandle(propp),
-            &recursed)) {
-      return false;
-    }
+      if (recursed) {
+        propp.setNotFound();
+        *donep = true;
+        return true;
+      }
 
-    if (recursed) {
-      propp.setNotFound();
-      *donep = true;
-      return true;
-    }
-
-    if (propp) {
-      *donep = true;
-      return true;
+      if (propp) {
+        *donep = true;
+        return true;
+      }
     }
   }
 
@@ -903,14 +899,11 @@ static MOZ_ALWAYS_INLINE bool LookupPropertyInline(
     }
     if (!proto->isNative()) {
       MOZ_ASSERT(!cx->isHelperThreadContext());
-      if (!allowGC) {
+      if constexpr (!allowGC) {
         return false;
+      } else {
+        return LookupProperty(cx, proto, id, objp, propp);
       }
-      return LookupProperty(
-          cx, MaybeRooted<JSObject*, allowGC>::toHandle(proto),
-          MaybeRooted<jsid, allowGC>::toHandle(id),
-          MaybeRooted<JSObject*, allowGC>::toMutableHandle(objp),
-          MaybeRooted<PropertyResult, allowGC>::toMutableHandle(propp));
     }
 
     current = &proto->template as<NativeObject>();

js/src/vm/NativeObject.cpp

@@ -2327,14 +2327,11 @@ static MOZ_ALWAYS_INLINE bool GetExistingProperty(
     }
   }
 
-  if (!allowGC) {
+  if constexpr (!allowGC) {
     return false;
+  } else {
+    return CallGetter(cx, obj, receiver, shape, vp);
   }
-
-  return CallGetter(cx, MaybeRooted<JSObject*, allowGC>::toHandle(obj),
-                    MaybeRooted<Value, allowGC>::toHandle(receiver),
-                    MaybeRooted<Shape*, allowGC>::toHandle(shape),
-                    MaybeRooted<Value, allowGC>::toMutableHandle(vp));
 }
 
 bool js::NativeGetExistingProperty(JSContext* cx, HandleObject receiver,