Implement trigonometric functions using a fdlibm port.

src/rempio2.h

+// Copyright 2014 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.
+
+// ====================================================
+// Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+//
+// Developed at SunSoft, a Sun Microsystems, Inc. business.
+// Permission to use, copy, modify, and distribute this
+// software is freely granted, provided that this notice
+// is preserved.
+// ====================================================
+//
+// The following is adapted from fdlibm (http://www.netlib.org/fdlibm).
+
+#ifndef V8_REMPIO2_H_
+#define V8_REMPIO2_H_
+
+namespace v8 {
+namespace internal {
+
+int rempio2(double x, double* y);
+
+// Constants to be exposed to builtins via Float64Array.
+class TrigonometricConstants : AllStatic {
+ public:
+  static void* constants() { return const_cast<double*>(constants_); }

[Sven Panne, 2014/07/24 10:44:21]

Casting away const here looks wrong: The array itself is in read-only memory,
and any write access will lead to a segfault. If the caller needs a non-const
pointer, the const_cast should be there (still dangerous) or it should copy the
contents into RW memory. In our case: After const_casting in bootstrapper.cc,
writing into kTrig on the JavaScript side leads to a segfault, which is
semi-nice, but it's OK if there is a warning comment.

Now that the const_cast in TrigonometricConstants has been removed, there is not
much need for a real class anymore:

   struct TrigonometricConstants {
     static const double constants[34];
   };

is enough, the size can be calculated via ARRAY_SIZE. I want C++11's uniform
initialization and std::array... :-/

[Yang, 2014/07/24 11:00:33]

Done.

+  static const int kSize = 34;
+
+ private:
+  static const double constants_[kSize];
+};
+}
+}  // namespace v8::internal
+
+#endif  // V8_REMPIO2_H_