Make stackmaps store their actual length.

runtime/vm/stack_frame.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/stack_frame.h"
 
 #include "vm/assembler_macros.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
@@ skipping 36 matching lines @@
 void StackFrame::VisitObjectPointers(ObjectPointerVisitor* visitor) {
   // NOTE: This code runs while GC is in progress and runs within
   // a NoHandleScope block. Hence it is not ok to use regular Zone or
   // Scope handles. We use direct stack handles, the raw pointers in
   // these handles are not traversed. The use of handles is mainly to
   // be able to reuse the handle based code and avoid having to add
   // helper functions to the raw object interface.
   ASSERT(visitor != NULL);
   NoGCScope no_gc;
   RawObject** start_addr = reinterpret_cast<RawObject**>(sp());
-  RawObject** end_addr = reinterpret_cast<RawObject**>(
-      fp() + (ParsedFunction::kFirstLocalSlotIndex * kWordSize));
+  RawObject** end_addr = reinterpret_cast<RawObject**>(fp()) +
+      ParsedFunction::kFirstLocalSlotIndex;
   Code code;
   code = LookupDartCode();
   if (!code.IsNull()) {
     Array maps;
     maps = Array::null();
     Stackmap map;
     map = code.GetStackmap(pc(), &maps, &map);
     if (!map.IsNull()) {
       // A stack map is present in the code object, use the stack map to visit
       // frame slots which are marked as having objects.
-      intptr_t end_bit_index = map.MaximumBitIndex();
-      // It's possible that no bits are set.
-      if (end_bit_index != Stackmap::kNoMaximum) {
-        intptr_t bit_index = map.MinimumBitIndex();
-        ASSERT(bit_index != Stackmap::kNoMinimum);
-        ASSERT(bit_index <= end_bit_index);
-        ASSERT(end_bit_index <= (end_addr - start_addr));
-        while (bit_index <= end_bit_index) {
-          if (map.IsObject(bit_index)) {
-            visitor->VisitPointer(end_addr - bit_index);
-          }
-          ++bit_index;
+      intptr_t length = map.Length();
+      for (intptr_t bit_index = 0; bit_index < length; ++bit_index) {
+        if (map.IsObject(bit_index)) {
+          visitor->VisitPointer(end_addr - bit_index);
         }
       }
       // The stack slots that are not spill slots (i.e., outgoing arguments)
       // are tagged objects.
-      end_addr = end_addr - (code.spill_slot_count() - 1);
-      ASSERT(end_addr >= start_addr);
+      end_addr -= length;
+      // The end address can be one slot (but not more) past the start
+      // address in the case that all slots were covered by the stack map.
+      ASSERT((end_addr + 1) >= start_addr);
     }
   }
   // Each slot between the start and end address are tagged objects.
   visitor->VisitPointers(start_addr, end_addr);
 }
 
 
 RawFunction* StackFrame::LookupDartFunction() const {
   const Code& code = Code::Handle(LookupDartCode());
   if (!code.IsNull()) {
@@ skipping 151 matching lines @@
 EntryFrame* StackFrameIterator::NextEntryFrame() {
   ASSERT(!frames_.HasNext());
   entry_.sp_ = frames_.sp_;
   entry_.fp_ = frames_.fp_;
   SetupNextExitFrameData();  // Setup data for next exit frame in chain.
   ASSERT(entry_.IsValid());
   return &entry_;
 }
 
 }  // namespace dart