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114 lines
3.8 KiB
ArmAsm
114 lines
3.8 KiB
ArmAsm
// Copyright ©2016 The Gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//
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// Some of the loop unrolling code is copied from:
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// http://golang.org/src/math/big/arith_amd64.s
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// which is distributed under these terms:
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//
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// Copyright (c) 2012 The Go Authors. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//+build !noasm,!appengine,!safe
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#include "textflag.h"
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#define X_PTR SI
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#define LEN CX
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#define TAIL BX
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#define INC_X R8
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#define INCx3_X R9
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#define ALPHA X0
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#define ALPHA_2 X1
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// func ScalInc(alpha float64, x []float64, n, incX uintptr)
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TEXT ·ScalInc(SB), NOSPLIT, $0
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MOVSD alpha+0(FP), ALPHA // ALPHA = alpha
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MOVQ x_base+8(FP), X_PTR // X_PTR = &x
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MOVQ incX+40(FP), INC_X // INC_X = incX
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SHLQ $3, INC_X // INC_X *= sizeof(float64)
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MOVQ n+32(FP), LEN // LEN = n
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CMPQ LEN, $0
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JE end // if LEN == 0 { return }
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MOVQ LEN, TAIL
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ANDQ $3, TAIL // TAIL = LEN % 4
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SHRQ $2, LEN // LEN = floor( LEN / 4 )
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JZ tail_start // if LEN == 0 { goto tail_start }
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MOVUPS ALPHA, ALPHA_2 // ALPHA_2 = ALPHA for pipelining
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LEAQ (INC_X)(INC_X*2), INCx3_X // INCx3_X = INC_X * 3
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loop: // do { // x[i] *= alpha unrolled 4x.
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MOVSD (X_PTR), X2 // X_i = x[i]
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MOVSD (X_PTR)(INC_X*1), X3
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MOVSD (X_PTR)(INC_X*2), X4
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MOVSD (X_PTR)(INCx3_X*1), X5
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MULSD ALPHA, X2 // X_i *= a
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MULSD ALPHA_2, X3
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MULSD ALPHA, X4
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MULSD ALPHA_2, X5
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MOVSD X2, (X_PTR) // x[i] = X_i
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MOVSD X3, (X_PTR)(INC_X*1)
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MOVSD X4, (X_PTR)(INC_X*2)
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MOVSD X5, (X_PTR)(INCx3_X*1)
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LEAQ (X_PTR)(INC_X*4), X_PTR // X_PTR = &(X_PTR[incX*4])
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DECQ LEN
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JNZ loop // } while --LEN > 0
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CMPQ TAIL, $0
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JE end // if TAIL == 0 { return }
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tail_start: // Reset loop registers
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MOVQ TAIL, LEN // Loop counter: LEN = TAIL
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SHRQ $1, LEN // LEN = floor( LEN / 2 )
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JZ tail_one
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tail_two: // do {
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MOVSD (X_PTR), X2 // X_i = x[i]
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MOVSD (X_PTR)(INC_X*1), X3
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MULSD ALPHA, X2 // X_i *= a
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MULSD ALPHA, X3
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MOVSD X2, (X_PTR) // x[i] = X_i
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MOVSD X3, (X_PTR)(INC_X*1)
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LEAQ (X_PTR)(INC_X*2), X_PTR // X_PTR = &(X_PTR[incX*2])
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ANDQ $1, TAIL
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JZ end
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tail_one:
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MOVSD (X_PTR), X2 // X_i = x[i]
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MULSD ALPHA, X2 // X_i *= ALPHA
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MOVSD X2, (X_PTR) // x[i] = X_i
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end:
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RET
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