154 lines
3.3 KiB
Plaintext
154 lines
3.3 KiB
Plaintext
|
Copyright 1996, 1999, 2001, 2002, 2004 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 mpn functions for various HP PA-RISC chips. Code
|
||
|
|
that runs faster on the PA7100 and later implementations, is in the pa7100
|
||
|
|
directory.
|
||
|
|
|
||
|
|
RELEVANT OPTIMIZATION ISSUES
|
||
|
|
|
||
|
|
Load and Store timing
|
||
|
|
|
||
|
|
On the PA7000 no memory instructions can issue the two cycles after a store.
|
||
|
|
For the PA7100, this is reduced to one cycle.
|
||
|
|
|
||
|
|
The PA7100 has a lookup-free cache, so it helps to schedule loads and the
|
||
|
|
dependent instruction really far from each other.
|
||
|
|
|
||
|
|
STATUS
|
||
|
|
|
||
|
|
1. mpn_mul_1 could be improved to 6.5 cycles/limb on the PA7100, using the
|
||
|
|
instructions below (but some sw pipelining is needed to avoid the
|
||
|
|
xmpyu-fstds delay):
|
||
|
|
|
||
|
|
fldds s1_ptr
|
||
|
|
|
||
|
|
xmpyu
|
||
|
|
fstds N(%r30)
|
||
|
|
xmpyu
|
||
|
|
fstds N(%r30)
|
||
|
|
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
|
||
|
|
addc
|
||
|
|
stws res_ptr
|
||
|
|
addc
|
||
|
|
stws res_ptr
|
||
|
|
|
||
|
|
addib Loop
|
||
|
|
|
||
|
|
2. mpn_addmul_1 could be improved from the current 10 to 7.5 cycles/limb
|
||
|
|
(asymptotically) on the PA7100, using the instructions below. With proper
|
||
|
|
sw pipelining and the unrolling level below, the speed becomes 8
|
||
|
|
cycles/limb.
|
||
|
|
|
||
|
|
fldds s1_ptr
|
||
|
|
fldds s1_ptr
|
||
|
|
|
||
|
|
xmpyu
|
||
|
|
fstds N(%r30)
|
||
|
|
xmpyu
|
||
|
|
fstds N(%r30)
|
||
|
|
xmpyu
|
||
|
|
fstds N(%r30)
|
||
|
|
xmpyu
|
||
|
|
fstds N(%r30)
|
||
|
|
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
ldws N(%r30)
|
||
|
|
addc
|
||
|
|
addc
|
||
|
|
addc
|
||
|
|
addc
|
||
|
|
addc %r0,%r0,cy-limb
|
||
|
|
|
||
|
|
ldws res_ptr
|
||
|
|
ldws res_ptr
|
||
|
|
ldws res_ptr
|
||
|
|
ldws res_ptr
|
||
|
|
add
|
||
|
|
stws res_ptr
|
||
|
|
addc
|
||
|
|
stws res_ptr
|
||
|
|
addc
|
||
|
|
stws res_ptr
|
||
|
|
addc
|
||
|
|
stws res_ptr
|
||
|
|
|
||
|
|
addib
|
||
|
|
|
||
|
|
3. For the PA8000 we have to stick to using 32-bit limbs before compiler
|
||
|
|
support emerges. But we want to use 64-bit operations whenever possible,
|
||
|
|
in particular for loads and stores. It is possible to handle mpn_add_n
|
||
|
|
efficiently by rotating (when s1/s2 are aligned), masking+bit field
|
||
|
|
inserting when (they are not). The speed should double compared to the
|
||
|
|
code used today.
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
LABEL SYNTAX
|
||
|
|
|
||
|
|
The HP-UX assembler takes labels starting in column 0 with no colon,
|
||
|
|
|
||
|
|
L$loop ldws,mb -4(0,%r25),%r22
|
||
|
|
|
||
|
|
Gas on hppa GNU/Linux however requires a colon,
|
||
|
|
|
||
|
|
L$loop: ldws,mb -4(0,%r25),%r22
|
||
|
|
|
||
|
|
This is covered by using LDEF() from asm-defs.m4. An alternative would be
|
||
|
|
to use ".label" which is accepted by both,
|
||
|
|
|
||
|
|
.label L$loop
|
||
|
|
ldws,mb -4(0,%r25),%r22
|
||
|
|
|
||
|
|
but that's not as nice to look at, not if you're used to assembler code
|
||
|
|
having labels in column 0.
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
REFERENCES
|
||
|
|
|
||
|
|
Hewlett Packard, "HP Assembler Reference Manual", 9th edition, June 1998,
|
||
|
|
part number 92432-90012.
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
----------------
|
||
|
|
Local variables:
|
||
|
|
mode: text
|
||
|
|
fill-column: 76
|
||
|
|
End:
|