Faster implementation of Math.exp()

src/platform.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 101 matching lines @@
 #else
 typedef intptr_t AtomicWord;
 #endif
 
 class Semaphore;
 class Mutex;
 
 double ceiling(double x);
 double modulo(double x, double y);
 
-// Custom implementation of sin, cos, tan and log.
+// Custom implementation of math functions.
 double fast_sin(double input);
 double fast_cos(double input);
 double fast_tan(double input);
 double fast_log(double input);
+double fast_exp(double input);
 double fast_sqrt(double input);
+// The custom exp implementation needs 16KB of lookup data; initialize it
+// on demand.
+void lazily_initialize_fast_exp();
 
 // Forward declarations.
 class Socket;
 
 // ----------------------------------------------------------------------------
 // OS
 //
 // This class has static methods for the different platform specific
 // functions. Add methods here to cope with differences between the
 // supported platforms.
@@ skipping 673 matching lines @@
   Atomic32 has_processing_thread_;
   PlatformData* data_;  // Platform specific data.
   int samples_taken_;  // Counts stack samples taken.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_