Introduce concurrent on-stack replacement.

src/full-codegen.h

 // 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 123 matching lines @@
 #elif V8_TARGET_ARCH_ARM
   static const int kCodeSizeMultiplier = 142;
 #elif V8_TARGET_ARCH_MIPS
   static const int kCodeSizeMultiplier = 142;
 #else
 #error Unsupported target architecture.
 #endif
 
   class BackEdgeTableIterator {
    public:
-    explicit BackEdgeTableIterator(Code* unoptimized) {
+    explicit BackEdgeTableIterator(Code* unoptimized,
+                                   DisallowHeapAllocation* required) {
       ASSERT(unoptimized->kind() == Code::FUNCTION);
       instruction_start_ = unoptimized->instruction_start();
       cursor_ = instruction_start_ + unoptimized->back_edge_table_offset();
       ASSERT(cursor_ < instruction_start_ + unoptimized->instruction_size());
       table_length_ = Memory::uint32_at(cursor_);
       cursor_ += kTableLengthSize;
       end_ = cursor_ + table_length_ * kEntrySize;
     }
 
     bool Done() { return cursor_ >= end_; }
@@ skipping 19 matching lines @@
       return Memory::uint32_at(cursor_ + kPcOffsetOffset);
     }
 
     Address pc() {
       ASSERT(!Done());
       return instruction_start_ + pc_offset();
     }
 
     uint32_t table_length() { return table_length_; }
 
+    bool FindPcOffset(uint32_t target_pc_offset) {
+      while (!Done()) {
+        if (pc_offset() == target_pc_offset) return true;
+        Next();
+      }
+      return false;
+    }
+
    private:
     static const int kTableLengthSize = kIntSize;
     static const int kAstIdOffset = 0 * kIntSize;
     static const int kPcOffsetOffset = 1 * kIntSize;
     static const int kLoopDepthOffset = 2 * kIntSize;
     static const int kEntrySize = 3 * kIntSize;
 
     Address cursor_;
     Address end_;
     Address instruction_start_;
     uint32_t table_length_;
-    DisallowHeapAllocation no_gc_while_iterating_over_raw_addresses_;
 
     DISALLOW_COPY_AND_ASSIGN(BackEdgeTableIterator);
   };
 
 
  private:
   class Breakable;
   class Iteration;
 
   class TestContext;
@@ skipping 730 matching lines @@
   }
 
  private:
   Zone* zone_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FULL_CODEGEN_H_