Simplify implementation of Mutex.

src/assembler.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 873 matching lines @@
   double_constants.min_int = kMinInt;
   double_constants.one_half = 0.5;
   double_constants.minus_one_half = -0.5;
   double_constants.minus_zero = -0.0;
   double_constants.uint8_max_value = 255;
   double_constants.zero = 0.0;
   double_constants.canonical_non_hole_nan = OS::nan_value();
   double_constants.the_hole_nan = BitCast<double>(kHoleNanInt64);
   double_constants.negative_infinity = -V8_INFINITY;
 
-  math_exp_data_mutex = OS::CreateMutex();
+  math_exp_data_mutex = new Mutex;
 }
 
 
 void ExternalReference::InitializeMathExpData() {
   // Early return?
   if (math_exp_data_initialized) return;
 
-  math_exp_data_mutex->Lock();
+  ScopedLock with(math_exp_data_mutex);
   if (!math_exp_data_initialized) {
     // If this is changed, generated code must be adapted too.
     const int kTableSizeBits = 11;
     const int kTableSize = 1 << kTableSizeBits;
     const double kTableSizeDouble = static_cast<double>(kTableSize);
 
     math_exp_constants_array = new double[9];
     // Input values smaller than this always return 0.
     math_exp_constants_array[0] = -708.39641853226408;
     // Input values larger than this always return +Infinity.
@@ skipping 15 matching lines @@
     for (int i = 0; i < kTableSize; i++) {
       double value = pow(2, i / kTableSizeDouble);
       uint64_t bits = BitCast<uint64_t, double>(value);
       bits &= (static_cast<uint64_t>(1) << 52) - 1;
       double mantissa = BitCast<double, uint64_t>(bits);
       math_exp_log_table_array[i] = mantissa;
     }
 
     math_exp_data_initialized = true;
   }
-  math_exp_data_mutex->Unlock();
 }
 
 
 void ExternalReference::TearDownMathExpData() {
   delete[] math_exp_constants_array;
   delete[] math_exp_log_table_array;
   delete math_exp_data_mutex;
 }
 
 
@@ skipping 728 matching lines @@
     assembler_->RecordRelocInfo(RelocInfo::POSITION, state_.current_position);
     state_.written_position = state_.current_position;
     written = true;
   }
 
   // Return whether something was written.
   return written;
 }
 
 } }  // namespace v8::internal