From a89a14ef5da44684a16b204e7a70460cc8c4922a Mon Sep 17 00:00:00 2001 From: Thomas Voss <mail@thomasvoss.com> Date: Fri, 21 Jun 2024 23:36:36 +0200 Subject: Basic constant folding implementation --- vendor/gmp-6.3.0/mpn/pa32/README | 162 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 162 insertions(+) create mode 100644 vendor/gmp-6.3.0/mpn/pa32/README (limited to 'vendor/gmp-6.3.0/mpn/pa32/README') diff --git a/vendor/gmp-6.3.0/mpn/pa32/README b/vendor/gmp-6.3.0/mpn/pa32/README new file mode 100644 index 0000000..4323390 --- /dev/null +++ b/vendor/gmp-6.3.0/mpn/pa32/README @@ -0,0 +1,162 @@ +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 either: + + * 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. + +or + + * the GNU General Public License as published by the Free Software + Foundation; either version 2 of the License, or (at your option) any + later version. + +or both in parallel, as here. + +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 General Public License +for more details. + +You should have received copies of the GNU General Public License and the +GNU Lesser General Public License along with the GNU MP Library. If not, +see https://www.gnu.org/licenses/. + + + + + + +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: -- cgit v1.2.3