Revert of [builtins] Introduce proper Float64Exp operator.

src/codegen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_CODEGEN_H_
 #define V8_CODEGEN_H_
 
 #include "src/code-stubs.h"
 #include "src/runtime/runtime.h"
 
@@ skipping 75 matching lines @@
  private:
   DISALLOW_COPY_AND_ASSIGN(CodeGenerator);
 };
 
 
 // Results of the library implementation of transcendental functions may differ
 // from the one we use in our generated code.  Therefore we use the same
 // generated code both in runtime and compiled code.
 typedef double (*UnaryMathFunctionWithIsolate)(double x, Isolate* isolate);
 
+UnaryMathFunctionWithIsolate CreateExpFunction(Isolate* isolate);
 UnaryMathFunctionWithIsolate CreateSqrtFunction(Isolate* isolate);
 
 
 double modulo(double x, double y);
 
 // Custom implementation of math functions.
+double fast_exp(double input, Isolate* isolate);
 double fast_sqrt(double input, Isolate* isolate);
+void lazily_initialize_fast_exp(Isolate* isolate);
 void lazily_initialize_fast_sqrt(Isolate* isolate);
 
 
 class ElementsTransitionGenerator : public AllStatic {
  public:
   // If |mode| is set to DONT_TRACK_ALLOCATION_SITE,
   // |allocation_memento_found| may be NULL.
   static void GenerateMapChangeElementsTransition(
       MacroAssembler* masm,
       Register receiver,
@@ skipping 50 matching lines @@
 #ifdef V8_TARGET_ARCH_ARM64
   const EmbeddedVector<byte, kNoCodeAgeSequenceLength> old_sequence_;
 #endif
 #endif
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CODEGEN_H_