[vm, gc] Require a safepoint for heap iteration.

runtime/vm/isolate_reload.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/isolate_reload.h"
 
 #include "vm/become.h"
 #include "vm/bit_vector.h"
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
@@ skipping 1239 matching lines @@
   }
 
   // Rehash constants map for all classes.
   RehashConstants();
 
 #ifdef DEBUG
   // Verify that all canonical instances are correctly setup in the
   // corresponding canonical tables.
   Thread* thread = Thread::Current();
   I->heap()->CollectAllGarbage();
+  HeapIterationScope iteration(thread);
   VerifyCanonicalVisitor check_canonical(thread);
-  I->heap()->IterateObjects(&check_canonical);
+  iteration.IterateObjects(&check_canonical);
 #endif  // DEBUG
 }
 
 void IsolateReloadContext::RehashConstants() {
   TIMELINE_SCOPE(RehashConstants);
   ClassTable* class_table = I->class_table();
   Class& cls = Class::Handle(zone_);
   const intptr_t top = class_table->NumCids();
   for (intptr_t cid = kInstanceCid; cid < top; cid++) {
     if (!class_table->IsValidIndex(cid) || !class_table->HasValidClassAt(cid)) {
@@ skipping 76 matching lines @@
   if (FLAG_trace_reload) {
     LogBlock blocker;
     TIR_Print("MorphInstance: \n");
     for (intptr_t i = 0; i < instance_morphers_.length(); i++) {
       instance_morphers_.At(i)->Dump();
     }
   }
 
   // Find all objects that need to be morphed.
   ObjectLocator locator(this);
-  isolate()->heap()->VisitObjects(&locator);
+  {
+    HeapIterationScope iteration(Thread::Current());
+    iteration.IterateObjects(&locator);
+  }
 
   // Return if no objects are located.
   intptr_t count = locator.count();
   if (count == 0) return;
 
   TIR_Print("Found %" Pd " object%s subject to morphing.\n", count,
             (count > 1) ? "s" : "");
 
   Array& before = Array::Handle();
   Array& after = Array::Handle();
@@ skipping 240 matching lines @@
   IsolateReloadContext* reload_context_;
   Zone* zone_;
 };
 
 void IsolateReloadContext::MarkAllFunctionsForRecompilation() {
   TIMELINE_SCOPE(MarkAllFunctionsForRecompilation);
   TIR_Print("---- MARKING ALL FUNCTIONS FOR RECOMPILATION\n");
   Thread* thread = Thread::Current();
   StackZone stack_zone(thread);
   Zone* zone = stack_zone.GetZone();
-  NoSafepointScope no_safepoint;
-  HeapIterationScope heap_iteration_scope;
+  HeapIterationScope iteration(thread);
   MarkFunctionsForRecompilation visitor(isolate_, this, zone);
-  isolate_->heap()->VisitObjects(&visitor);
+  iteration.IterateObjects(&visitor);
 }
 
 void IsolateReloadContext::InvalidateWorld() {
   TIR_Print("---- INVALIDATING WORLD\n");
   ResetMegamorphicCaches();
   DeoptimizeFunctionsOnStack();
   ResetUnoptimizedICsOnStack();
   MarkAllFunctionsForRecompilation();
 }
 
@@ skipping 189 matching lines @@
         ASSERT(!super_cls.IsNull());
         super_cls.AddDirectSubclass(cls);
       }
     }
   }
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart