Revert "Implement trigonometric functions using a fdlibm port."

src/math.js

Index: src/math.js
diff --git a/src/math.js b/src/math.js
index 436a41f5c44400609fe7cc446f318ca36ca6aacd..9dc4b37d0ce2115ed9e9b5078f204fd060f926b9 100644
--- a/src/math.js
+++ b/src/math.js
@@ -56,6 +56,12 @@ function MathCeil(x) {
   return -MathFloor(-x);
 }
 
+// ECMA 262 - 15.8.2.7
+function MathCos(x) {
+  x = MathAbs(x);  // Convert to number and get rid of -0.
+  return TrigonometricInterpolation(x, 1);
+}
+
 // ECMA 262 - 15.8.2.8
 function MathExp(x) {
   return %MathExpRT(TO_NUMBER_INLINE(x));
@@ -158,16 +164,97 @@ function MathRound(x) {
   return %RoundNumber(TO_NUMBER_INLINE(x));
 }
 
+// ECMA 262 - 15.8.2.16
+function MathSin(x) {
+  x = x * 1;  // Convert to number and deal with -0.
+  if (%_IsMinusZero(x)) return x;
+  return TrigonometricInterpolation(x, 0);
+}
+
 // ECMA 262 - 15.8.2.17
 function MathSqrt(x) {
   return %_MathSqrtRT(TO_NUMBER_INLINE(x));
 }
 
+// ECMA 262 - 15.8.2.18
+function MathTan(x) {
+  return MathSin(x) / MathCos(x);
+}
+
 // Non-standard extension.
 function MathImul(x, y) {
   return %NumberImul(TO_NUMBER_INLINE(x), TO_NUMBER_INLINE(y));
 }
 
+
+var kInversePiHalf      = 0.636619772367581343;      // 2 / pi
+var kInversePiHalfS26   = 9.48637384723993156e-9;    // 2 / pi / (2^26)
+var kS26                = 1 << 26;
+var kTwoStepThreshold   = 1 << 27;
+// pi / 2 rounded up
+var kPiHalf             = 1.570796326794896780;      // 0x192d4454fb21f93f
+// We use two parts for pi/2 to emulate a higher precision.
+// pi_half_1 only has 26 significant bits for mantissa.
+// Note that pi_half > pi_half_1 + pi_half_2
+var kPiHalf1            = 1.570796325802803040;      // 0x00000054fb21f93f
+var kPiHalf2            = 9.920935796805404252e-10;  // 0x3326a611460b113e
+
+var kSamples;            // Initialized to a number during genesis.
+var kIndexConvert;       // Initialized to kSamples / (pi/2) during genesis.
+var kSinTable;           // Initialized to a Float64Array during genesis.
+var kCosXIntervalTable;  // Initialized to a Float64Array during genesis.
+
+// This implements sine using the following algorithm.
+// 1) Multiplication takes care of to-number conversion.
+// 2) Reduce x to the first quadrant [0, pi/2].
+//    Conveniently enough, in case of +/-Infinity, we get NaN.
+//    Note that we try to use only 26 instead of 52 significant bits for
+//    mantissa to avoid rounding errors when multiplying.  For very large
+//    input we therefore have additional steps.
+// 3) Replace x by (pi/2-x) if x was in the 2nd or 4th quadrant.
+// 4) Do a table lookup for the closest samples to the left and right of x.
+// 5) Find the derivatives at those sampling points by table lookup:
+//    dsin(x)/dx = cos(x) = sin(pi/2-x) for x in [0, pi/2].
+// 6) Use cubic spline interpolation to approximate sin(x).
+// 7) Negate the result if x was in the 3rd or 4th quadrant.
+// 8) Get rid of -0 by adding 0.
+function TrigonometricInterpolation(x, phase) {
+  if (x < 0 || x > kPiHalf) {
+    var multiple;
+    while (x < -kTwoStepThreshold || x > kTwoStepThreshold) {
+      // Let's assume this loop does not terminate.
+      // All numbers x in each loop forms a set S.
+      // (1) abs(x) > 2^27 for all x in S.
+      // (2) abs(multiple) != 0 since (2^27 * inverse_pi_half_s26) > 1
+      // (3) multiple is rounded down in 2^26 steps, so the rounding error is
+      //     at most max(ulp, 2^26).
+      // (4) so for x > 2^27, we subtract at most (1+pi/4)x and at least
+      //     (1-pi/4)x
+      // (5) The subtraction results in x' so that abs(x') <= abs(x)*pi/4.
+      //     Note that this difference cannot be simply rounded off.
+      // Set S cannot exist since (5) violates (1).  Loop must terminate.
+      multiple = MathFloor(x * kInversePiHalfS26) * kS26;
+      x = x - multiple * kPiHalf1 - multiple * kPiHalf2;
+    }
+    multiple = MathFloor(x * kInversePiHalf);
+    x = x - multiple * kPiHalf1 - multiple * kPiHalf2;
+    phase += multiple;
+  }
+  var double_index = x * kIndexConvert;
+  if (phase & 1) double_index = kSamples - double_index;
+  var index = double_index | 0;
+  var t1 = double_index - index;
+  var t2 = 1 - t1;
+  var y1 = kSinTable[index];
+  var y2 = kSinTable[index + 1];
+  var dy = y2 - y1;
+  return (t2 * y1 + t1 * y2 +
+              t1 * t2 * ((kCosXIntervalTable[index] - dy) * t2 +
+                         (dy - kCosXIntervalTable[index + 1]) * t1))
+         * (1 - (phase & 2)) + 0;
+}
+
+
 // ES6 draft 09-27-13, section 20.2.2.28.
 function MathSign(x) {
   x = TO_NUMBER_INLINE(x);
@@ -177,6 +264,7 @@ function MathSign(x) {
   return NAN;
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.34.
 function MathTrunc(x) {
   x = TO_NUMBER_INLINE(x);
@@ -186,6 +274,7 @@ function MathTrunc(x) {
   return NAN;
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.30.
 function MathSinh(x) {
   if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
@@ -194,6 +283,7 @@ function MathSinh(x) {
   return (MathExp(x) - MathExp(-x)) / 2;
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.12.
 function MathCosh(x) {
   if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
@@ -201,6 +291,7 @@ function MathCosh(x) {
   return (MathExp(x) + MathExp(-x)) / 2;
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.33.
 function MathTanh(x) {
   if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
@@ -213,6 +304,7 @@ function MathTanh(x) {
   return (exp1 - exp2) / (exp1 + exp2);
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.5.
 function MathAsinh(x) {
   if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
@@ -223,6 +315,7 @@ function MathAsinh(x) {
   return -MathLog(-x + MathSqrt(x * x + 1));
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.3.
 function MathAcosh(x) {
   if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
@@ -232,6 +325,7 @@ function MathAcosh(x) {
   return MathLog(x + MathSqrt(x + 1) * MathSqrt(x - 1));
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.7.
 function MathAtanh(x) {
   if (!IS_NUMBER(x)) x = NonNumberToNumber(x);
@@ -242,6 +336,7 @@ function MathAtanh(x) {
   return 0.5 * MathLog((1 + x) / (1 - x));
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.21.
 function MathLog10(x) {
   return MathLog(x) * 0.434294481903251828;  // log10(x) = log(x)/log(10).
@@ -253,6 +348,7 @@ function MathLog2(x) {
   return MathLog(x) * 1.442695040888963407;  // log2(x) = log(x)/log(2).
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.17.
 function MathHypot(x, y) {  // Function length is 2.
   // We may want to introduce fast paths for two arguments and when
@@ -285,12 +381,13 @@ function MathHypot(x, y) {  // Function length is 2.
   return MathSqrt(sum) * max;
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.16.
 function MathFroundJS(x) {
   return %MathFround(TO_NUMBER_INLINE(x));
 }
 
-// ES6 draft 07-18-14, section 20.2.2.11
+
 function MathClz32(x) {
   x = ToUint32(TO_NUMBER_INLINE(x));
   if (x == 0) return 32;
@@ -304,6 +401,7 @@ function MathClz32(x) {
   return result;
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.9.
 // Cube root approximation, refer to: http://metamerist.com/cbrt/cbrt.htm
 // Using initial approximation adapted from Kahan's cbrt and 4 iterations
@@ -327,6 +425,8 @@ function CubeRoot(x) {
   return NEWTON_ITERATION_CBRT(x, approx);
 }
 
+
+
 // ES6 draft 09-27-13, section 20.2.2.14.
 // Use Taylor series to approximate.
 // exp(x) - 1 at 0 == -1 + exp(0) + exp'(0)*x/1! + exp''(0)*x^2/2! + ...
@@ -347,6 +447,7 @@ function MathExpm1(x) {
   }
 }
 
+
 // ES6 draft 09-27-13, section 20.2.2.20.
 // Use Taylor series to approximate. With y = x + 1;
 // log(y) at 1 == log(1) + log'(1)(y-1)/1! + log''(1)(y-1)^2/2! + ...
@@ -401,14 +502,14 @@ function SetUpMath() {
     "asin", MathAsinJS,
     "atan", MathAtanJS,
     "ceil", MathCeil,
-    "cos", MathCos,       // implemented by third_party/fdlibm
+    "cos", MathCos,
     "exp", MathExp,
     "floor", MathFloor,
     "log", MathLog,
     "round", MathRound,
-    "sin", MathSin,       // implemented by third_party/fdlibm
+    "sin", MathSin,
     "sqrt", MathSqrt,
-    "tan", MathTan,       // implemented by third_party/fdlibm
+    "tan", MathTan,
     "atan2", MathAtan2JS,
     "pow", MathPow,
     "max", MathMax,
@@ -436,6 +537,8 @@ function SetUpMath() {
   %SetInlineBuiltinFlag(MathRandom);
   %SetInlineBuiltinFlag(MathSin);
   %SetInlineBuiltinFlag(MathCos);
+  %SetInlineBuiltinFlag(MathTan);
+  %SetInlineBuiltinFlag(TrigonometricInterpolation);
 }
 
 SetUpMath();