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Annotation of OpenXM_contrib/gmp/mpn/alpha/rshift.s, Revision 1.1

1.1     ! maekawa     1:  # Alpha 21064 __mpn_rshift --
        !             2:
        !             3:  # Copyright (C) 1994, 1995 Free Software Foundation, Inc.
        !             4:
        !             5:  # This file is part of the GNU MP Library.
        !             6:
        !             7:  # The GNU MP Library is free software; you can redistribute it and/or modify
        !             8:  # it under the terms of the GNU Library General Public License as published by
        !             9:  # the Free Software Foundation; either version 2 of the License, or (at your
        !            10:  # option) any later version.
        !            11:
        !            12:  # The GNU MP Library is distributed in the hope that it will be useful, but
        !            13:  # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            14:  # or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
        !            15:  # License for more details.
        !            16:
        !            17:  # You should have received a copy of the GNU Library General Public License
        !            18:  # along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
        !            19:  # the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            20:  # MA 02111-1307, USA.
        !            21:
        !            22:
        !            23:  # INPUT PARAMETERS
        !            24:  # res_ptr     r16
        !            25:  # s1_ptr      r17
        !            26:  # size                r18
        !            27:  # cnt         r19
        !            28:
        !            29:  # This code runs at 4.8 cycles/limb on the 21064.  With infinite unrolling,
        !            30:  # it would take 4 cycles/limb.  It should be possible to get down to 3
        !            31:  # cycles/limb since both ldq and stq can be paired with the other used
        !            32:  # instructions.  But there are many restrictions in the 21064 pipeline that
        !            33:  # makes it hard, if not impossible, to get down to 3 cycles/limb:
        !            34:
        !            35:  # 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay.
        !            36:  # 2. Only aligned instruction pairs can be paired.
        !            37:  # 3. The store buffer or silo might not be able to deal with the bandwidth.
        !            38:
        !            39:        .set    noreorder
        !            40:        .set    noat
        !            41: .text
        !            42:        .align  3
        !            43:        .globl  __mpn_rshift
        !            44:        .ent    __mpn_rshift
        !            45: __mpn_rshift:
        !            46:        .frame  $30,0,$26,0
        !            47:
        !            48:        ldq     $4,0($17)       # load first limb
        !            49:        addq    $17,8,$17
        !            50:        subq    $31,$19,$7
        !            51:        subq    $18,1,$18
        !            52:        and     $18,4-1,$20     # number of limbs in first loop
        !            53:        sll     $4,$7,$0        # compute function result
        !            54:
        !            55:        beq     $20,.L0
        !            56:        subq    $18,$20,$18
        !            57:
        !            58:        .align  3
        !            59: .Loop0:
        !            60:        ldq     $3,0($17)
        !            61:        addq    $16,8,$16
        !            62:        addq    $17,8,$17
        !            63:        subq    $20,1,$20
        !            64:        srl     $4,$19,$5
        !            65:        sll     $3,$7,$6
        !            66:        bis     $3,$3,$4
        !            67:        bis     $5,$6,$8
        !            68:        stq     $8,-8($16)
        !            69:        bne     $20,.Loop0
        !            70:
        !            71: .L0:   beq     $18,.Lend
        !            72:
        !            73:        .align  3
        !            74: .Loop: ldq     $3,0($17)
        !            75:        addq    $16,32,$16
        !            76:        subq    $18,4,$18
        !            77:        srl     $4,$19,$5
        !            78:        sll     $3,$7,$6
        !            79:
        !            80:        ldq     $4,8($17)
        !            81:        srl     $3,$19,$1
        !            82:        bis     $5,$6,$8
        !            83:        stq     $8,-32($16)
        !            84:        sll     $4,$7,$2
        !            85:
        !            86:        ldq     $3,16($17)
        !            87:        srl     $4,$19,$5
        !            88:        bis     $1,$2,$8
        !            89:        stq     $8,-24($16)
        !            90:        sll     $3,$7,$6
        !            91:
        !            92:        ldq     $4,24($17)
        !            93:        srl     $3,$19,$1
        !            94:        bis     $5,$6,$8
        !            95:        stq     $8,-16($16)
        !            96:        sll     $4,$7,$2
        !            97:
        !            98:        addq    $17,32,$17
        !            99:        bis     $1,$2,$8
        !           100:        stq     $8,-8($16)
        !           101:
        !           102:        bgt     $18,.Loop
        !           103:
        !           104: .Lend: srl     $4,$19,$8
        !           105:        stq     $8,0($16)
        !           106:        ret     $31,($26),1
        !           107:        .end    __mpn_rshift