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math: amd64 versions of Ceil, Floor and Trunc

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Ceil  to 4.81 from 20.6 ns/op
Floor to 4.37 from 13.5 ns/op
Trunc to 3.97 from 14.3 ns/op
Also changed three MOVSDs to MOVAPDs in log_amd64.s

R=rsc, golang-dev
CC=golang-dev
https://golang.org/cl/6262048
This commit is contained in:
Charles L. Dorian 2012-06-02 13:06:12 -04:00 committed by Russ Cox
parent 2b57a87678
commit 322057cbfc
2 changed files with 69 additions and 7 deletions
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70
src/pkg/math/floor_amd64.s
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@ -1,12 +1,74 @@
// Copyright 2011 The Go Authors. All rights reserved.
// Copyright 2012 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.
#define Big 0x4330000000000000 // 2**52
// func Floor(x float64) float64
TEXT ·Floor(SB),7,$0
JMP ·floor(SB)
MOVQ x+0(FP), AX
MOVQ $~(1<<63), DX // sign bit mask
ANDQ AX,DX // DX = |x|
SUBQ $1,DX
MOVQ $(Big - 1), CX // if |x| >= 2**52-1 or IsNaN(x) or |x| == 0, return x
CMPQ DX,CX
JAE isBig_floor
MOVQ AX, X0 // X0 = x
CVTTSD2SQ X0, AX
CVTSQ2SD AX, X1 // X1 = float(int(x))
CMPSD X1, X0, 1 // compare LT; X0 = 0xffffffffffffffff or 0
MOVSD $(-1.0), X2
ANDPD X2, X0 // if x < float(int(x)) {X0 = -1} else {X0 = 0}
ADDSD X1, X0
MOVSD X0, r+8(FP)
RET
isBig_floor:
MOVQ AX, r+8(FP) // return x
RET
// func Ceil(x float64) float64
TEXT ·Ceil(SB),7,$0
JMP ·ceil(SB)
MOVQ x+0(FP), AX
MOVQ $~(1<<63), DX // sign bit mask
MOVQ AX, BX // BX = copy of x
ANDQ DX, BX // BX = |x|
MOVQ $Big, CX // if |x| >= 2**52 or IsNaN(x), return x
CMPQ BX, CX
JAE isBig_ceil
MOVQ AX, X0 // X0 = x
MOVQ DX, X2 // X2 = sign bit mask
CVTTSD2SQ X0, AX
ANDNPD X0, X2 // X2 = sign
CVTSQ2SD AX, X1 // X1 = float(int(x))
CMPSD X1, X0, 2 // compare LE; X0 = 0xffffffffffffffff or 0
ORPD X2, X1 // if X1 = 0.0, incorporate sign
MOVSD $1.0, X3
ANDNPD X3, X0
ORPD X2, X0 // if float(int(x)) <= x {X0 = 1} else {X0 = -0}
ADDSD X1, X0
MOVSD X0, r+8(FP)
RET
isBig_ceil:
MOVQ AX, r+8(FP)
RET
// func Trunc(x float64) float64
TEXT ·Trunc(SB),7,$0
JMP ·trunc(SB)
MOVQ x+0(FP), AX
MOVQ $~(1<<63), DX // sign bit mask
MOVQ AX, BX // BX = copy of x
ANDQ DX, BX // BX = |x|
MOVQ $Big, CX // if |x| >= 2**52 or IsNaN(x), return x
CMPQ BX, CX
JAE isBig_trunc
MOVQ AX, X0
MOVQ DX, X2 // X2 = sign bit mask
CVTTSD2SQ X0, AX
ANDNPD X0, X2 // X2 = sign
CVTSQ2SD AX, X0 // X0 = float(int(x))
ORPD X2, X0 // if X0 = 0.0, incorporate sign
MOVSD X0, r+8(FP)
RET
isBig_trunc:
MOVQ AX, r+8(FP) // return x
RET

6
src/pkg/math/log_amd64.s
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@ -54,13 +54,13 @@ TEXT ·Log(SB),7,$0
// s := f / (2 + f)
MOVSD $2.0, X0
ADDSD X2, X0
MOVSD X2, X3
MOVAPD X2, X3
DIVSD X0, X3 // x1=k, x2= f, x3= s
// s2 := s * s
MOVSD X3, X4 // x1= k, x2= f, x3= s
MOVAPD X3, X4 // x1= k, x2= f, x3= s
MULSD X4, X4 // x1= k, x2= f, x3= s, x4= s2
// s4 := s2 * s2
MOVSD X4, X5 // x1= k, x2= f, x3= s, x4= s2
MOVAPD X4, X5 // x1= k, x2= f, x3= s, x4= s2
MULSD X5, X5 // x1= k, x2= f, x3= s, x4= s2, x5= s4
// t1 := s2 * (L1 + s4*(L3+s4*(L5+s4*L7)))
MOVSD $L7, X6