Faster implementation of Math.exp()

src/platform-posix.cc

Index: src/platform-posix.cc
diff --git a/src/platform-posix.cc b/src/platform-posix.cc
index 3bc83733ca21249808c74388dd98de6be4125497..0016d59d3a72ecf3c0609cc87396b1928071b71f 100644
--- a/src/platform-posix.cc
+++ b/src/platform-posix.cc
@@ -142,11 +142,19 @@ 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;
@@ -332,6 +340,7 @@ void POSIXPostSetUp() {
   init_fast_cos_function();
   init_fast_tan_function();
   init_fast_log_function();
+  // fast_exp is initialized lazily.
   init_fast_sqrt_function();
 }