code review 5484076: pkg/math: undo manual inlining of IsInf and IsNaN

src/pkg/math/sin.go

 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package math
 
 /*
         Floating-point sine and cosine.
 */
 
@@ skipping 105 matching lines @@
 //      Cos(NaN) = NaN
 func Cos(x float64) float64
 
 func cos(x float64) float64 {
         const (
                 PI4A = 7.85398125648498535156E-1                             // 0x3fe921fb40000000, Pi/4 split into three parts
                 PI4B = 3.77489470793079817668E-8                             // 0x3e64442d00000000,
                 PI4C = 2.69515142907905952645E-15                            // 0x3ce8469898cc5170,
                 M4PI = 1.273239544735162542821171882678754627704620361328125 // 4/pi
         )
-        // TODO(rsc): Remove manual inlining of IsNaN, IsInf
-        // when compiler does it for us
         // special cases
         switch {
-        case x != x || x < -MaxFloat64 || x > MaxFloat64: // IsNaN(x) || IsInf(x, 0):
+        case IsNaN(x) || IsInf(x, 0):
                 return NaN()
         }
 
         // make argument positive
         sign := false
         if x < 0 {
                 x = -x
         }
 
         j := int64(x * M4PI) // integer part of x/(Pi/4), as integer for tests on the phase angle
@@ skipping 34 matching lines @@
 //      Sin(NaN) = NaN
 func Sin(x float64) float64
 
 func sin(x float64) float64 {
         const (
                 PI4A = 7.85398125648498535156E-1                             // 0x3fe921fb40000000, Pi/4 split into three parts
                 PI4B = 3.77489470793079817668E-8                             // 0x3e64442d00000000,
                 PI4C = 2.69515142907905952645E-15                            // 0x3ce8469898cc5170,
                 M4PI = 1.273239544735162542821171882678754627704620361328125 // 4/pi
         )
-        // TODO(rsc): Remove manual inlining of IsNaN, IsInf
-        // when compiler does it for us
         // special cases
         switch {
-        case x == 0 || x != x: // x == 0 || IsNaN():
+        case x == 0 || IsNaN(x):
                 return x // return ±0 || NaN()
-        case x < -MaxFloat64 || x > MaxFloat64: // IsInf(x, 0):
+        case IsInf(x, 0):
                 return NaN()
         }
 
         // make argument positive but save the sign
         sign := false
         if x < 0 {
                 x = -x
                 sign = true
         }
 
@@ skipping 17 matching lines @@
         if j == 1 || j == 2 {
                 y = 1.0 - 0.5*zz + zz*zz*((((((_cos[0]*zz)+_cos[1])*zz+_cos[2])*zz+_cos[3])*zz+_cos[4])*zz+_cos[5])
         } else {
                 y = z + z*zz*((((((_sin[0]*zz)+_sin[1])*zz+_sin[2])*zz+_sin[3])*zz+_sin[4])*zz+_sin[5])
         }
         if sign {
                 y = -y
         }
         return y
 }