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Annotation of OpenXM_contrib/gmp/mpn/pa32/README, Revision 1.1

1.1     ! ohara       1: Copyright 1996, 1999, 2001 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 the GNU Lesser General Public License as published by
        !             7: the Free Software Foundation; either version 2.1 of the License, or (at your
        !             8: option) any later version.
        !             9:
        !            10: The GNU MP Library is distributed in the hope that it will be useful, but
        !            11: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            12: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
        !            13: License for more details.
        !            14:
        !            15: You should have received a copy of the GNU Lesser General Public License
        !            16: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
        !            17: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
        !            18: 02111-1307, USA.
        !            19:
        !            20:
        !            21:
        !            22:
        !            23:
        !            24:
        !            25: This directory contains mpn functions for various HP PA-RISC chips.  Code
        !            26: that runs faster on the PA7100 and later implementations, is in the pa7100
        !            27: directory.
        !            28:
        !            29: RELEVANT OPTIMIZATION ISSUES
        !            30:
        !            31:   Load and Store timing
        !            32:
        !            33: On the PA7000 no memory instructions can issue the two cycles after a store.
        !            34: For the PA7100, this is reduced to one cycle.
        !            35:
        !            36: The PA7100 has a lookup-free cache, so it helps to schedule loads and the
        !            37: dependent instruction really far from each other.
        !            38:
        !            39: STATUS
        !            40:
        !            41: 1. mpn_mul_1 could be improved to 6.5 cycles/limb on the PA7100, using the
        !            42:    instructions below (but some sw pipelining is needed to avoid the
        !            43:    xmpyu-fstds delay):
        !            44:
        !            45:        fldds   s1_ptr
        !            46:
        !            47:        xmpyu
        !            48:        fstds   N(%r30)
        !            49:        xmpyu
        !            50:        fstds   N(%r30)
        !            51:
        !            52:        ldws    N(%r30)
        !            53:        ldws    N(%r30)
        !            54:        ldws    N(%r30)
        !            55:        ldws    N(%r30)
        !            56:
        !            57:        addc
        !            58:        stws    res_ptr
        !            59:        addc
        !            60:        stws    res_ptr
        !            61:
        !            62:        addib   Loop
        !            63:
        !            64: 2. mpn_addmul_1 could be improved from the current 10 to 7.5 cycles/limb
        !            65:    (asymptotically) on the PA7100, using the instructions below.  With proper
        !            66:    sw pipelining and the unrolling level below, the speed becomes 8
        !            67:    cycles/limb.
        !            68:
        !            69:        fldds   s1_ptr
        !            70:        fldds   s1_ptr
        !            71:
        !            72:        xmpyu
        !            73:        fstds   N(%r30)
        !            74:        xmpyu
        !            75:        fstds   N(%r30)
        !            76:        xmpyu
        !            77:        fstds   N(%r30)
        !            78:        xmpyu
        !            79:        fstds   N(%r30)
        !            80:
        !            81:        ldws    N(%r30)
        !            82:        ldws    N(%r30)
        !            83:        ldws    N(%r30)
        !            84:        ldws    N(%r30)
        !            85:        ldws    N(%r30)
        !            86:        ldws    N(%r30)
        !            87:        ldws    N(%r30)
        !            88:        ldws    N(%r30)
        !            89:        addc
        !            90:        addc
        !            91:        addc
        !            92:        addc
        !            93:        addc    %r0,%r0,cy-limb
        !            94:
        !            95:        ldws    res_ptr
        !            96:        ldws    res_ptr
        !            97:        ldws    res_ptr
        !            98:        ldws    res_ptr
        !            99:        add
        !           100:        stws    res_ptr
        !           101:        addc
        !           102:        stws    res_ptr
        !           103:        addc
        !           104:        stws    res_ptr
        !           105:        addc
        !           106:        stws    res_ptr
        !           107:
        !           108:        addib
        !           109:
        !           110: 3. For the PA8000 we have to stick to using 32-bit limbs before compiler
        !           111:    support emerges.  But we want to use 64-bit operations whenever possible,
        !           112:    in particular for loads and stores.  It is possible to handle mpn_add_n
        !           113:    efficiently by rotating (when s1/s2 are aligned), masking+bit field
        !           114:    inserting when (they are not).  The speed should double compared to the
        !           115:    code used today.
        !           116:
        !           117:
        !           118:
        !           119:
        !           120: LABEL SYNTAX
        !           121:
        !           122: The HP-UX assembler takes labels starting in column 0 with no colon,
        !           123:
        !           124:        L$loop  ldws,mb -4(0,%r25),%r22
        !           125:
        !           126: Gas on hppa GNU/Linux however requires a colon,
        !           127:
        !           128:        L$loop: ldws,mb -4(0,%r25),%r22
        !           129:
        !           130: Fortunately both accept a ".label" pseudo-op,
        !           131:
        !           132:                .label  L$loop
        !           133:                ldws,mb -4(0,%r25),%r22
        !           134:
        !           135:
        !           136:
        !           137:
        !           138:
        !           139: ----------------
        !           140: Local variables:
        !           141: mode: text
        !           142: fill-column: 76
        !           143: End: