Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpn / alpha / ev6 / nails / README

diff --git a/gmp/mpn/alpha/ev6/nails/README b/gmp/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 3 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.  If not, see http://www.gnu.org/licenses/.
+
+
+
+
+
+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