Add counters for write barriers in optimized code.

src/arm/macro-assembler-arm.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 466 matching lines @@
                                  LinkRegisterStatus lr_status,
                                  SaveFPRegsMode fp_mode,
                                  RememberedSetAction remembered_set_action,
                                  SmiCheck smi_check) {
   if (emit_debug_code()) {
     ldr(ip, MemOperand(address));
     cmp(ip, value);
     Check(eq, kWrongAddressOrValuePassedToRecordWrite);
   }
 
+  // Count number of write barriers in generated code.
+  isolate()->counters()->write_barriers_static()->Increment();
+  // TODO(mstarzinger): Dynamic counter missing.
+
+  // First, check if a write barrier is even needed. The tests below
+  // catch stores of smis and stores into the young generation.
   Label done;
 
   if (smi_check == INLINE_SMI_CHECK) {
     JumpIfSmi(value, &done);
   }
 
   CheckPageFlag(value,
                 value,  // Used as scratch.
                 MemoryChunk::kPointersToHereAreInterestingMask,
                 eq,
@@ skipping 3469 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM