PPC/s390: [builtins] Introduce proper Float64Exp operator.

src/compiler/s390/code-generator-s390.cc

 // Copyright 2015 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.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 1234 matching lines @@
     //  Double operations
     case kS390_ModDouble:
       ASSEMBLE_FLOAT_MODULO();
       break;
     case kIeee754Float64Atan:
       ASSEMBLE_IEEE754_UNOP(atan);
       break;
     case kIeee754Float64Atan2:
       ASSEMBLE_IEEE754_BINOP(atan2);
       break;
+    case kIeee754Float64Exp:
+      ASSEMBLE_IEEE754_UNOP(exp);
+      break;
     case kIeee754Float64Log:
       ASSEMBLE_IEEE754_UNOP(log);
       break;
     case kIeee754Float64Log1p:
       ASSEMBLE_IEEE754_UNOP(log1p);
       break;
     case kIeee754Float64Log2:
       ASSEMBLE_IEEE754_UNOP(log2);
       break;
     case kIeee754Float64Log10:
@@ skipping 942 matching lines @@
       padding_size -= 2;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8