github.com/gopherd/gonum@v0.0.4/internal/asm/f64/scalunitaryto_amd64.s (about)

     1  // Copyright ©2016 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  //
     5  // Some of the loop unrolling code is copied from:
     6  // http://golang.org/src/math/big/arith_amd64.s
     7  // which is distributed under these terms:
     8  //
     9  // Copyright (c) 2012 The Go Authors. All rights reserved.
    10  //
    11  // Redistribution and use in source and binary forms, with or without
    12  // modification, are permitted provided that the following conditions are
    13  // met:
    14  //
    15  //    * Redistributions of source code must retain the above copyright
    16  // notice, this list of conditions and the following disclaimer.
    17  //    * Redistributions in binary form must reproduce the above
    18  // copyright notice, this list of conditions and the following disclaimer
    19  // in the documentation and/or other materials provided with the
    20  // distribution.
    21  //    * Neither the name of Google Inc. nor the names of its
    22  // contributors may be used to endorse or promote products derived from
    23  // this software without specific prior written permission.
    24  //
    25  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    26  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    27  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    28  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    29  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    30  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    31  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    32  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    33  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    34  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    35  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    36  
    37  // +build !noasm,!gccgo,!safe
    38  
    39  #include "textflag.h"
    40  
    41  #define MOVDDUP_ALPHA    LONG $0x44120FF2; WORD $0x2024 // @ MOVDDUP 32(SP), X0  /*XMM0, 32[RSP]*/
    42  
    43  #define X_PTR SI
    44  #define DST_PTR DI
    45  #define IDX AX
    46  #define LEN CX
    47  #define TAIL BX
    48  #define ALPHA X0
    49  #define ALPHA_2 X1
    50  
    51  // func ScalUnitaryTo(dst []float64, alpha float64, x []float64)
    52  // This function assumes len(dst) >= len(x).
    53  TEXT ·ScalUnitaryTo(SB), NOSPLIT, $0
    54  	MOVQ x_base+32(FP), X_PTR    // X_PTR = &x
    55  	MOVQ dst_base+0(FP), DST_PTR // DST_PTR = &dst
    56  	MOVDDUP_ALPHA                // ALPHA = { alpha, alpha }
    57  	MOVQ x_len+40(FP), LEN       // LEN = len(x)
    58  	CMPQ LEN, $0
    59  	JE   end                     // if LEN == 0 { return }
    60  
    61  	XORQ IDX, IDX   // IDX = 0
    62  	MOVQ LEN, TAIL
    63  	ANDQ $7, TAIL   // TAIL = LEN % 8
    64  	SHRQ $3, LEN    // LEN = floor( LEN / 8 )
    65  	JZ   tail_start // if LEN == 0 { goto tail_start }
    66  
    67  	MOVUPS ALPHA, ALPHA_2 // ALPHA_2 = ALPHA for pipelining
    68  
    69  loop:  // do { // dst[i] = alpha * x[i] unrolled 8x.
    70  	MOVUPS (X_PTR)(IDX*8), X2   // X_i = x[i]
    71  	MOVUPS 16(X_PTR)(IDX*8), X3
    72  	MOVUPS 32(X_PTR)(IDX*8), X4
    73  	MOVUPS 48(X_PTR)(IDX*8), X5
    74  
    75  	MULPD ALPHA, X2   // X_i *= ALPHA
    76  	MULPD ALPHA_2, X3
    77  	MULPD ALPHA, X4
    78  	MULPD ALPHA_2, X5
    79  
    80  	MOVUPS X2, (DST_PTR)(IDX*8)   // dst[i] = X_i
    81  	MOVUPS X3, 16(DST_PTR)(IDX*8)
    82  	MOVUPS X4, 32(DST_PTR)(IDX*8)
    83  	MOVUPS X5, 48(DST_PTR)(IDX*8)
    84  
    85  	ADDQ $8, IDX  // i += 8
    86  	DECQ LEN
    87  	JNZ  loop     // while --LEN > 0
    88  	CMPQ TAIL, $0
    89  	JE   end      // if TAIL == 0 { return }
    90  
    91  tail_start: // Reset loop counters
    92  	MOVQ TAIL, LEN // Loop counter: LEN = TAIL
    93  	SHRQ $1, LEN   // LEN = floor( TAIL / 2 )
    94  	JZ   tail_one  // if LEN == 0 { goto tail_one }
    95  
    96  tail_two: // do {
    97  	MOVUPS (X_PTR)(IDX*8), X2   // X_i = x[i]
    98  	MULPD  ALPHA, X2            // X_i *= ALPHA
    99  	MOVUPS X2, (DST_PTR)(IDX*8) // dst[i] = X_i
   100  	ADDQ   $2, IDX              // i += 2
   101  	DECQ   LEN
   102  	JNZ    tail_two             // while --LEN > 0
   103  
   104  	ANDQ $1, TAIL
   105  	JZ   end      // if TAIL == 0 { return }
   106  
   107  tail_one:
   108  	MOVSD (X_PTR)(IDX*8), X2   // X_i = x[i]
   109  	MULSD ALPHA, X2            // X_i *= ALPHA
   110  	MOVSD X2, (DST_PTR)(IDX*8) // dst[i] = X_i
   111  
   112  end:
   113  	RET