Fix pc to code cache so it can cope with a pointer to the start of the code

src/frames.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1152 matching lines @@
 
 
 static int GcSafeSizeOfCodeSpaceObject(HeapObject* object) {
   MapWord map_word = object->map_word();
   Map* map = map_word.IsForwardingAddress() ?
       map_word.ToForwardingAddress()->map() : map_word.ToMap();
   return object->SizeFromMap(map);
 }
 
 
 Code* PcToCodeCache::GcSafeFindCodeForPc(Address pc) {

[Rico, 2011/09/20 09:10:35]

We should consider renaming pc to something else since this can be any pointer
into a code object - I am fine with not doing this now to get gc stable

   Heap* heap = isolate_->heap();
   // Check if the pc points into a large object chunk.
   LargePage* large_page = heap->lo_space()->FindPageContainingPc(pc);
   if (large_page != NULL) return GcSafeCastToCode(large_page->GetObject(), pc);
 
   // Iterate through the page until we reach the end or find an object starting
   // after the pc.
   Page* page = Page::FromAddress(pc);
 
   Address addr = page->skip_list()->StartFor(pc);
 
   Address top = heap->code_space()->top();
   Address limit = heap->code_space()->limit();
 
   while (true) {
     if (addr == top && addr != limit) {
       addr = limit;
       continue;
     }
 
     HeapObject* obj = HeapObject::FromAddress(addr);
     int obj_size = GcSafeSizeOfCodeSpaceObject(obj);
     Address next_addr = addr + obj_size;
-    if (next_addr >= pc) return GcSafeCastToCode(obj, pc);
+    if (next_addr > pc) return GcSafeCastToCode(obj, pc);
     addr = next_addr;
   }
 }
 
 
 PcToCodeCache::PcToCodeCacheEntry* PcToCodeCache::GetCacheEntry(Address pc) {
   isolate_->counters()->pc_to_code()->Increment();
   ASSERT(IsPowerOf2(kPcToCodeCacheSize));
   uint32_t hash = ComputeIntegerHash(
       static_cast<uint32_t>(reinterpret_cast<uintptr_t>(pc)));
@@ skipping 79 matching lines @@
   ZoneList<StackFrame*> list(10);
   for (StackFrameIterator it; !it.done(); it.Advance()) {
     StackFrame* frame = AllocateFrameCopy(it.frame());
     list.Add(frame);
   }
   return list.ToVector();
 }
 
 
 } }  // namespace v8::internal