math: remove asm version of sincos everywhere, except 386

We have dedicated asm implementation of sincos only on 386 and amd64,
on everything else we are just jumping to generic version.
However amd64 version is actually slower than generic one:

Sincos-6               34.4ns ± 0%   24.8ns ± 0%  -27.79%  (p=0.000 n=8+10)

So remove all sincos*.s and keep only generic and 386.

Updates #19819

Change-Id: I7eefab35743729578264f52f6d23ee2c227c92a5
Reviewed-on: https://go-review.googlesource.com/41200
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/math/sincos.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !386
+
 package math
 
 // Coefficients _sin[] and _cos[] are found in pkg/math/sin.go.
@@ -12,9 +14,7 @@ package math
 //	Sincos(±0) = ±0, 1
 //	Sincos(±Inf) = NaN, NaN
 //	Sincos(NaN) = NaN, NaN
-func Sincos(x float64) (sin, cos float64)
-
-func sincos(x float64) (sin, cos float64) {
+func Sincos(x float64) (sin, cos float64) {
 	const (
 		PI4A = 7.85398125648498535156E-1                             // 0x3fe921fb40000000, Pi/4 split into three parts
 		PI4B = 3.77489470793079817668E-8                             // 0x3e64442d00000000,

src/math/sincos_arm.s → src/math/sincos_386.go

-// Copyright 2011 The Go Authors. All rights reserved.
+// Copyright 2017 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.
 
-#include "textflag.h"
+package math
 
-TEXT ·Sincos(SB),NOSPLIT,$0
-	B ·sincos(SB)
+// Sincos returns Sin(x), Cos(x).
+//
+// Special cases are:
+//	Sincos(±0) = ±0, 1
+//	Sincos(±Inf) = NaN, NaN
+//	Sincos(NaN) = NaN, NaN
+func Sincos(x float64) (sin, cos float64)

src/math/sincos_amd64.s

-// Copyright 2010 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.
-
-#include "textflag.h"
-
-// The method is based on a paper by Naoki Shibata: "Efficient evaluation
-// methods of elementary functions suitable for SIMD computation", Proc.
-// of International Supercomputing Conference 2010 (ISC'10), pp. 25 -- 32
-// (May 2010). The paper is available at
-// http://www.springerlink.com/content/340228x165742104/
-//
-// The original code and the constants below are from the author's
-// implementation available at http://freshmeat.net/projects/sleef.
-// The README file says, "The software is in public domain.
-// You can use the software without any obligation."
-//
-// This code is a simplified version of the original.
-
-#define PosOne 0x3FF0000000000000
-#define PosInf 0x7FF0000000000000
-#define NaN    0x7FF8000000000001
-#define PI4A 0.7853981554508209228515625 // pi/4 split into three parts
-#define PI4B 0.794662735614792836713604629039764404296875e-8
-#define PI4C 0.306161699786838294306516483068750264552437361480769e-16
-#define M4PI 1.273239544735162542821171882678754627704620361328125 // 4/pi
-#define T0 1.0
-#define T1 -8.33333333333333333333333e-02 // (-1.0/12)
-#define T2 2.77777777777777777777778e-03 // (+1.0/360)
-#define T3 -4.96031746031746031746032e-05 // (-1.0/20160)
-#define T4 5.51146384479717813051146e-07 // (+1.0/1814400)
-
-// func Sincos(d float64) (sin, cos float64)
-TEXT ·Sincos(SB),NOSPLIT,$0
-	// test for special cases
-	MOVQ    $~(1<<63), DX // sign bit mask
-	MOVQ    x+0(FP), BX
-	ANDQ    BX, DX
-	JEQ     isZero
-	MOVQ    $PosInf, AX
-	CMPQ    AX, DX
-	JLE     isInfOrNaN
-	// Reduce argument
-	MOVQ    BX, X7 // x7= d
-	MOVQ    DX, X0 // x0= |d|
-	MOVSD   $M4PI, X2
-	MULSD   X0, X2
-	CVTTSD2SQ X2, BX // bx= q
-	MOVQ    $1, AX
-	ANDQ    BX, AX
-	ADDQ    BX, AX
-	CVTSQ2SD AX, X2
-	MOVSD   $PI4A, X3
-	MULSD   X2, X3
-	SUBSD   X3, X0
-	MOVSD   $PI4B, X3
-	MULSD   X2, X3
-	SUBSD   X3, X0
-	MOVSD   $PI4C, X3
-	MULSD   X2, X3
-	SUBSD   X3, X0
-	MULSD   $0.125, X0 // x0= x, x7= d, bx= q
-	// Evaluate Taylor series
-	MULSD   X0, X0
-	MOVSD   $T4, X2
-	MULSD   X0, X2
-	ADDSD   $T3, X2
-	MULSD   X0, X2
-	ADDSD   $T2, X2
-	MULSD   X0, X2
-	ADDSD   $T1, X2
-	MULSD   X0, X2
-	ADDSD   $T0, X2
-	MULSD   X2, X0 // x0= x, x7= d, bx= q
-	// Apply double angle formula
-	MOVSD   $4.0, X2
-	SUBSD   X0, X2
-	MULSD   X2, X0
-	MOVSD   $4.0, X2
-	SUBSD   X0, X2
-	MULSD   X2, X0
-	MOVSD   $4.0, X2
-	SUBSD   X0, X2
-	MULSD   X2, X0
-	MULSD   $0.5, X0 // x0= x, x7= d, bx= q
-	// sin = sqrt((2 - x) * x)
-	MOVSD   $2.0, X2
-	SUBSD   X0, X2
-	MULSD   X0, X2
-	SQRTSD  X2, X2 // x0= x, x2= z, x7= d, bx= q
-	// cos = 1 - x
-	MOVSD   $1.0, X1
-	SUBSD   X0, X1 // x1= x, x2= z, x7= d, bx= q
-	// if ((q + 1) & 2) != 0 { sin, cos = cos, sin }
-	MOVQ    $1, DX
-	ADDQ    BX, DX
-	ANDQ    $2, DX
-	SHRQ    $1, DX
-	SUBQ	$1, DX
-	MOVQ    DX, X3
-	// sin = (y & z) | (^y & x)
-	MOVAPD  X2, X0
-	ANDPD   X3, X0 // x0= sin
-	MOVAPD  X3, X4
-	ANDNPD  X1, X4
-	ORPD    X4, X0 // x0= sin, x1= x, x2= z, x3= y, x7= d, bx= q
-	// cos = (y & x) | (^y & z)
-	ANDPD   X3, X1 // x1= cos
-	ANDNPD  X2, X3
-	ORPD    X3, X1 // x0= sin, x1= cos, x7= d, bx= q
-	// if ((q & 4) != 0) != (d < 0) { sin = -sin }
-	MOVQ    BX, AX
-	MOVQ    $61, CX
-	SHLQ    CX, AX
-	MOVQ    AX, X3
-	XORPD   X7, X3
-	MOVQ    $(1<<63), AX
-	MOVQ    AX, X2 // x2= -0.0
-	ANDPD   X2, X3
-	ORPD    X3, X0 // x0= sin, x1= cos, x2= -0.0, bx= q
-	// if ((q + 2) & 4) != 0 { cos = -cos }
-	MOVQ    $2, AX
-	ADDQ    AX, BX
-	MOVQ    $61, CX
-	SHLQ    CX, BX
-	MOVQ    BX, X3
-	ANDPD   X2, X3
-	ORPD    X3, X1 // x0= sin, x1= cos
-	// return (sin, cos)
-	MOVSD   X0, sin+8(FP)
-	MOVSD   X1, cos+16(FP)
-	RET
-isZero: // return (±0.0, 1.0)
-	MOVQ    BX, sin+8(FP)
-	MOVQ    $PosOne, AX
-	MOVQ    AX, cos+16(FP)
-	RET
-isInfOrNaN: // return (NaN, NaN)
-	MOVQ    $NaN, AX
-	MOVQ    AX, sin+8(FP)
-	MOVQ    AX, cos+16(FP)
-	RET

src/math/sincos_amd64p32.s

-// Copyright 2013 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.
-
-#include "sincos_amd64.s"

src/math/stubs_arm64.s

@@ -57,9 +57,6 @@ TEXT ·Mod(SB),NOSPLIT,$0
 TEXT ·Remainder(SB),NOSPLIT,$0
 	B ·remainder(SB)
 
-TEXT ·Sincos(SB),NOSPLIT,$0
-	B ·sincos(SB)
-
 TEXT ·Sin(SB),NOSPLIT,$0
 	B ·sin(SB)
 

src/math/stubs_mips64x.s

@@ -75,9 +75,6 @@ TEXT ·Mod(SB),NOSPLIT,$0
 TEXT ·Remainder(SB),NOSPLIT,$0
 	JMP ·remainder(SB)
 
-TEXT ·Sincos(SB),NOSPLIT,$0
-	JMP ·sincos(SB)
-
 TEXT ·Sin(SB),NOSPLIT,$0
 	JMP ·sin(SB)
 

src/math/stubs_mipsx.s

@@ -75,9 +75,6 @@ TEXT ·Mod(SB),NOSPLIT,$0
 TEXT ·Remainder(SB),NOSPLIT,$0
 	JMP	·remainder(SB)
 
-TEXT ·Sincos(SB),NOSPLIT,$0
-	JMP	·sincos(SB)
-
 TEXT ·Sin(SB),NOSPLIT,$0
 	JMP	·sin(SB)
 

src/math/stubs_ppc64x.s

@@ -66,9 +66,6 @@ TEXT ·Mod(SB),NOSPLIT,$0
 TEXT ·Remainder(SB),NOSPLIT,$0
 	BR ·remainder(SB)
 
-TEXT ·Sincos(SB),NOSPLIT,$0
-	BR ·sincos(SB)
-
 TEXT ·Sin(SB),NOSPLIT,$0
 	BR ·sin(SB)
 

src/math/stubs_s390x.s

@@ -52,9 +52,6 @@ TEXT ·Mod(SB),NOSPLIT,$0
 TEXT ·Remainder(SB),NOSPLIT,$0
 	BR ·remainder(SB)
 
-TEXT ·Sincos(SB),NOSPLIT,$0
-	BR ·sincos(SB)
-
 TEXT ·Tan(SB),NOSPLIT,$0
 	BR ·tan(SB)