[builtins] Unify Cosh, Sinh and Tanh as exports from flibm

src/third_party/fdlibm/fdlibm.js

 // The following is adapted from fdlibm (http://www.netlib.org/fdlibm),
 //
 // ====================================================
 // Copyright (C) 1993-2004 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 original source code covered by the above license above has been
 // modified significantly by Google Inc.
 // Copyright 2014 the V8 project authors. All rights reserved.
 //
 // The following is a straightforward translation of fdlibm routines
 // by Raymond Toy (rtoy@google.com).
 
 (function(global, utils) {
   
 "use strict";
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
 
 var GlobalMath = global.Math;
-var MathAbs;
-var MathExpm1;
 
-utils.Import(function(from) {
-  MathAbs = from.MathAbs;
-  MathExpm1 = from.MathExpm1;
-});
-
-// ES6 draft 09-27-13, section 20.2.2.30.
-// Math.sinh
-// Method :
-// mathematically sinh(x) if defined to be (exp(x)-exp(-x))/2
-//      1. Replace x by |x| (sinh(-x) = -sinh(x)).
-//      2.
-//                                                  E + E/(E+1)
-//          0        <= x <= 22     :  sinh(x) := --------------, E=expm1(x)
-//                                                      2
-//
-//          22       <= x <= lnovft :  sinh(x) := exp(x)/2 
-//          lnovft   <= x <= ln2ovft:  sinh(x) := exp(x/2)/2 * exp(x/2)
-//          ln2ovft  <  x           :  sinh(x) := x*shuge (overflow)
-//
-// Special cases:
-//      sinh(x) is |x| if x is +Infinity, -Infinity, or NaN.
-//      only sinh(0)=0 is exact for finite x.
-//
-define KSINH_OVERFLOW = 710.4758600739439;
-define TWO_M28 = 3.725290298461914e-9;  // 2^-28, empty lower half
-define LOG_MAXD = 709.7822265625;  // 0x40862e42 00000000, empty lower half
-
-function MathSinh(x) {
-  x = x * 1;  // Convert to number.
-  var h = (x < 0) ? -0.5 : 0.5;
-  // |x| in [0, 22]. return sign(x)*0.5*(E+E/(E+1))
-  var ax = MathAbs(x);
-  if (ax < 22) {
-    // For |x| < 2^-28, sinh(x) = x
-    if (ax < TWO_M28) return x;
-    var t = MathExpm1(ax);
-    if (ax < 1) return h * (2 * t - t * t / (t + 1));
-    return h * (t + t / (t + 1));
-  }
-  // |x| in [22, log(maxdouble)], return 0.5 * exp(|x|)
-  if (ax < LOG_MAXD) return h * %math_exp(ax);
-  // |x| in [log(maxdouble), overflowthreshold]
-  // overflowthreshold = 710.4758600739426
-  if (ax <= KSINH_OVERFLOW) {
-    var w = %math_exp(0.5 * ax);
-    var t = h * w;
-    return t * w;
-  }
-  // |x| > overflowthreshold or is NaN.
-  // Return Infinity of the appropriate sign or NaN.
-  return x * INFINITY;
-}
-
-
-// ES6 draft 09-27-13, section 20.2.2.12.
-// Math.cosh
-// Method : 
-// mathematically cosh(x) if defined to be (exp(x)+exp(-x))/2
-//      1. Replace x by |x| (cosh(x) = cosh(-x)). 
-//      2.
-//                                                      [ exp(x) - 1 ]^2 
-//          0        <= x <= ln2/2  :  cosh(x) := 1 + -------------------
-//                                                         2*exp(x)
-//
-//                                                 exp(x) + 1/exp(x)
-//          ln2/2    <= x <= 22     :  cosh(x) := -------------------
-//                                                        2
-//          22       <= x <= lnovft :  cosh(x) := exp(x)/2 
-//          lnovft   <= x <= ln2ovft:  cosh(x) := exp(x/2)/2 * exp(x/2)
-//          ln2ovft  <  x           :  cosh(x) := huge*huge (overflow)
-//
-// Special cases:
-//      cosh(x) is |x| if x is +INF, -INF, or NaN.
-//      only cosh(0)=1 is exact for finite x.
-//
-define KCOSH_OVERFLOW = 710.4758600739439;
-
-function MathCosh(x) {
-  x = x * 1;  // Convert to number.
-  var ix = %_DoubleHi(x) & 0x7fffffff;
-  // |x| in [0,0.5*log2], return 1+expm1(|x|)^2/(2*exp(|x|))
-  if (ix < 0x3fd62e43) {
-    var t = MathExpm1(MathAbs(x));
-    var w = 1 + t;
-    // For |x| < 2^-55, cosh(x) = 1
-    if (ix < 0x3c800000) return w;
-    return 1 + (t * t) / (w + w);
-  }
-  // |x| in [0.5*log2, 22], return (exp(|x|)+1/exp(|x|)/2
-  if (ix < 0x40360000) {
-    var t = %math_exp(MathAbs(x));
-    return 0.5 * t + 0.5 / t;
-  }
-  // |x| in [22, log(maxdouble)], return half*exp(|x|)
-  if (ix < 0x40862e42) return 0.5 * %math_exp(MathAbs(x));
-  // |x| in [log(maxdouble), overflowthreshold]
-  if (MathAbs(x) <= KCOSH_OVERFLOW) {
-    var w = %math_exp(0.5 * MathAbs(x));
-    var t = 0.5 * w;
-    return t * w;
-  }
-  if (NUMBER_IS_NAN(x)) return x;
-  // |x| > overflowthreshold.
-  return INFINITY;
-}
-
-// ES6 draft 09-27-13, section 20.2.2.33.
-// Math.tanh(x)
-// Method :
-//                                    x    -x
-//                                   e  - e
-//     0. tanh(x) is defined to be -----------
-//                                    x    -x
-//                                   e  + e
-//     1. reduce x to non-negative by tanh(-x) = -tanh(x).
-//     2.  0      <= x <= 2**-55 : tanh(x) := x*(one+x)
-//                                             -t
-//         2**-55 <  x <=  1     : tanh(x) := -----; t = expm1(-2x)
-//                                            t + 2
-//                                                  2
-//         1      <= x <=  22.0  : tanh(x) := 1-  ----- ; t = expm1(2x)
-//                                                t + 2
-//         22.0   <  x <= INF    : tanh(x) := 1.
-//
-// Special cases:
-//     tanh(NaN) is NaN;
-//     only tanh(0) = 0 is exact for finite argument.
-//
-
-define TWO_M55 = 2.77555756156289135105e-17;  // 2^-55, empty lower half
-
-function MathTanh(x) {
-  x = x * 1;  // Convert to number.
-  // x is Infinity or NaN
-  if (!NUMBER_IS_FINITE(x)) {
-    if (x > 0) return 1;
-    if (x < 0) return -1;
-    return x;
-  }
-
-  var ax = MathAbs(x);
-  var z;
-  // |x| < 22
-  if (ax < 22) {
-    if (ax < TWO_M55) {
-      // |x| < 2^-55, tanh(small) = small.
-      return x;
-    }
-    if (ax >= 1) {
-      // |x| >= 1
-      var t = MathExpm1(2 * ax);
-      z = 1 - 2 / (t + 2);
-    } else {
-      var t = MathExpm1(-2 * ax);
-      z = -t / (t + 2);
-    }
-  } else {
-    // |x| > 22, return +/- 1
-    z = 1;
-  }
-  return (x >= 0) ? z : -z;
-}
+utils.Import(function(from) {});
 
 //-------------------------------------------------------------------
 
-utils.InstallFunctions(GlobalMath, DONT_ENUM, [
-  "sinh", MathSinh,
-  "cosh", MathCosh,
-  "tanh", MathTanh
-]);
+utils.InstallFunctions(GlobalMath, DONT_ENUM, []);
 
 })