mpir/mpn/alpha/ev6/nails/README

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Copyright 2002, 2005 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
for more details.
You should have received a copy of the GNU Lesser General Public License along
with the GNU MP Library; see the file COPYING.LIB. If not, write to the Free
Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
USA.
This directory contains assembly code for nails-enabled 21264. The code is not
very well optimized.
For addmul_N, as N grows larger, we could make multiple loads together, then do
about 3.3 i/c. 10 cycles after the last load, we can increase to 4 i/c. This
would surely allow addmul_4 to run at 2 c/l, but the same should be possible
also for addmul_3 and perhaps even addmul_2.
current fair best
Routine c/l unroll c/l unroll c/l i/c
mul_1 3.25 2.75 2.75 3.273
addmul_1 4.0 4 3.5 4 14 3.25 3.385
addmul_2 4.0 1 2.5 2 10 2.25 3.333
addmul_3 3.0 1 2.33 2 14 2 3.333
addmul_4 2.5 1 2.125 2 17 2 3.135
addmul_5 2 1 10
addmul_6 2 1 12
addmul_7 2 1 14
(The "best" column doesn't account for bookkeeping instructions and
thereby assumes infinite unrolling.)
Basecase usages:
1 addmul_1
2 addmul_2
3 addmul_3
4 addmul_4
5 addmul_3 + addmul_2 2.3998
6 addmul_4 + addmul_2
7 addmul_4 + addmul_3