Fix unaligned accesses in back_edge tables.

src/runtime.cc

 // Copyright 2012 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 8526 matching lines @@
     ASSERT(frame->LookupCode() == *unoptimized);
     ASSERT(unoptimized->contains(frame->pc()));
 
     // Use linear search of the unoptimized code's back edge table to find
     // the AST id matching the PC.
     Address start = unoptimized->instruction_start();
     unsigned target_pc_offset = static_cast<unsigned>(frame->pc() - start);
     Address table_cursor = start + unoptimized->back_edge_table_offset();
     uint32_t table_length = Memory::uint32_at(table_cursor);
     table_cursor += kIntSize;
-    uint8_t loop_depth = 0;
+    uint32_t loop_depth = 0;
     for (unsigned i = 0; i < table_length; ++i) {
       // Table entries are (AST id, pc offset) pairs.
       uint32_t pc_offset = Memory::uint32_at(table_cursor + kIntSize);
       if (pc_offset == target_pc_offset) {
         ast_id = BailoutId(static_cast<int>(Memory::uint32_at(table_cursor)));
-        loop_depth = Memory::uint8_at(table_cursor + 2 * kIntSize);
+        loop_depth = Memory::uint32_at(table_cursor + 2 * kIntSize);
         break;
       }
       table_cursor += FullCodeGenerator::kBackEdgeEntrySize;
     }
     ASSERT(!ast_id.IsNone());
     if (FLAG_trace_osr) {
       PrintF("[replacing on-stack at AST id %d, loop depth %d in ",
               ast_id.ToInt(), loop_depth);
       function->PrintName();
       PrintF("]\n");
@@ skipping 5421 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal