Change the stack map search to require an exact match.

runtime/vm/object.cc

 // Copyright (c) 2012, 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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
@@ skipping 7032 matching lines @@
   // This code is used only during iterating frames during a GC and hence
   // it should not in turn start a GC.
   NoGCScope no_gc;
   if (stackmaps() == Array::null()) {
     // No stack maps are present in the code object which means this
     // frame relies on tagged pointers.
     return Stackmap::null();
   }
   // A stack map is present in the code object, use the stack map to visit
   // frame slots which are marked as having objects.
-  RawStackmap* previous_map = Stackmap::null();
   *maps = stackmaps();
   *map = Stackmap::null();
   for (intptr_t i = 0; i < maps->Length(); i++) {
     *map ^= maps->At(i);
     ASSERT(!map->IsNull());
     if (map->PC() == pc) {
-      break;  // We found a stack map for this frame.
+      return map->raw();  // We found a stack map for this frame.
     }
-    if (map->PC() > pc) {
-      // We have not found a stackmap corresponding to the PC of this frame,
-      // we will use the closest previous stack map.
-      *map = previous_map;
-      break;
-    }
-    previous_map = map->raw();
   }
-  return map->raw();
+  // If the code has stackmaps, it must have them for all safepoints.
+  UNREACHABLE();
+  return Stackmap::null();
 }
 
 
 RawContext* Context::New(intptr_t num_variables, Heap::Space space) {
   ASSERT(num_variables >= 0);
   ASSERT(Object::context_class() != Class::null());
 
   Context& result = Context::Handle();
   {
     RawObject* raw = Object::Allocate(Context::kInstanceKind,
@@ skipping 3703 matching lines @@
   const String& str = String::Handle(pattern());
   const char* format = "JSRegExp: pattern=%s flags=%s";
   intptr_t len = OS::SNPrint(NULL, 0, format, str.ToCString(), Flags());
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len + 1));
   OS::SNPrint(chars, (len + 1), format, str.ToCString(), Flags());
   return chars;
 }
 
 }  // namespace dart