Faster implementation of Math.exp()

src/platform-posix.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 124 matching lines @@
   fast_##name##_function = generator;                    \
 }                                                        \
 double fast_##name(double x) {                           \
   return (*fast_##name##_function)(x);                   \
 }
 
 UNARY_MATH_FUNCTION(sin, CreateTranscendentalFunction(TranscendentalCache::SIN))
 UNARY_MATH_FUNCTION(cos, CreateTranscendentalFunction(TranscendentalCache::COS))
 UNARY_MATH_FUNCTION(tan, CreateTranscendentalFunction(TranscendentalCache::TAN))
 UNARY_MATH_FUNCTION(log, CreateTranscendentalFunction(TranscendentalCache::LOG))
+UNARY_MATH_FUNCTION(exp, CreateExpFunction())
 UNARY_MATH_FUNCTION(sqrt, CreateSqrtFunction())
 
 #undef MATH_FUNCTION
 
 
+void lazily_initialize_fast_exp() {
+  if (fast_exp_function == NULL) {
+    init_fast_exp_function();
+  }
+}
+
+
 double OS::nan_value() {
   // NAN from math.h is defined in C99 and not in POSIX.
   return NAN;
 }
 
 
 int OS::GetCurrentProcessId() {
   return static_cast<int>(getpid());
 }
 
@@ skipping 165 matching lines @@
 
 
 void POSIXPostSetUp() {
 #if defined(V8_TARGET_ARCH_IA32)
   memcopy_function = CreateMemCopyFunction();
 #endif
   init_fast_sin_function();
   init_fast_cos_function();
   init_fast_tan_function();
   init_fast_log_function();
+  // fast_exp is initialized lazily.
   init_fast_sqrt_function();
 }
 
 // ----------------------------------------------------------------------------
 // POSIX string support.
 //
 
 char* OS::StrChr(char* str, int c) {
   return strchr(str, c);
 }
@@ skipping 196 matching lines @@
   return ntohl(value);
 }
 
 
 Socket* OS::CreateSocket() {
   return new POSIXSocket();
 }
 
 
 } }  // namespace v8::internal