github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/alpha/ev6/nails/README (about)

     1  Copyright 2002, 2005 Free Software Foundation, Inc.
     2  
     3  This file is part of the GNU MP Library.
     4  
     5  The GNU MP Library is free software; you can redistribute it and/or modify
     6  it under the terms of either:
     7  
     8    * the GNU Lesser General Public License as published by the Free
     9      Software Foundation; either version 3 of the License, or (at your
    10      option) any later version.
    11  
    12  or
    13  
    14    * the GNU General Public License as published by the Free Software
    15      Foundation; either version 2 of the License, or (at your option) any
    16      later version.
    17  
    18  or both in parallel, as here.
    19  
    20  The GNU MP Library is distributed in the hope that it will be useful, but
    21  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    22  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    23  for more details.
    24  
    25  You should have received copies of the GNU General Public License and the
    26  GNU Lesser General Public License along with the GNU MP Library.  If not,
    27  see https://www.gnu.org/licenses/.
    28  
    29  
    30  
    31  
    32  
    33  This directory contains assembly code for nails-enabled 21264.  The code is not
    34  very well optimized.
    35  
    36  For addmul_N, as N grows larger, we could make multiple loads together, then do
    37  about 3.3 i/c.  10 cycles after the last load, we can increase to 4 i/c.  This
    38  would surely allow addmul_4 to run at 2 c/l, but the same should be possible
    39  also for addmul_3 and perhaps even addmul_2.
    40  
    41  
    42  		current		fair		best
    43  Routine		c/l  unroll	c/l  unroll	c/l  i/c
    44  mul_1		3.25		2.75		2.75 3.273
    45  addmul_1	4.0	4	3.5	4 14	3.25 3.385
    46  addmul_2	4.0	1	2.5	2 10	2.25 3.333
    47  addmul_3	3.0	1	2.33	2 14	2    3.333
    48  addmul_4	2.5	1	2.125	2 17	2    3.135
    49  
    50  addmul_5			2	1 10
    51  addmul_6			2	1 12
    52  addmul_7			2	1 14
    53  
    54  (The "best" column doesn't account for bookkeeping instructions and
    55  thereby assumes infinite unrolling.)
    56  
    57  Basecase usages:
    58  
    59  1	 addmul_1
    60  2	 addmul_2
    61  3	 addmul_3
    62  4	 addmul_4
    63  5	 addmul_3 + addmul_2	2.3998
    64  6	 addmul_4 + addmul_2
    65  7	 addmul_4 + addmul_3