libgcc/config/arc/ieee-754/muldf3.S

   1 /* Copyright (C) 2008-2019 Free Software Foundation, Inc.
   2    Contributor: Joern Rennecke <joern.rennecke@embecosm.com>
   3                 on behalf of Synopsys Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 /* XMAC schedule: directly back-to-back multiplies stall; the third
  27    instruction after a multiply stalls unless it is also a multiply.  */
  28 #include "arc-ieee-754.h"
  29
  30 #if 0 /* DEBUG */
  31         .global __muldf3
  32         .balign 4
  33 __muldf3:
  34         push_s blink
  35         push_s r2
  36         push_s r3
  37         push_s r0
  38         bl.d __muldf3_c
  39         push_s r1
  40         ld_s r2,[sp,12]
  41         ld_s r3,[sp,8]
  42         st_s r0,[sp,12]
  43         st_s r1,[sp,8]
  44         pop_s r1
  45         bl.d __muldf3_asm
  46         pop_s r0
  47         pop_s r3
  48         pop_s r2
  49         pop_s blink
  50         cmp r0,r2
  51         cmp.eq r1,r3
  52         jeq_s [blink]
  53         b abort
  54 #define __muldf3 __muldf3_asm
  55 #endif /* DEBUG */
  56 /* N.B. This is optimized for ARC700.
  57   ARC600 has very different scheduling / instruction selection criteria.  */
  58 /* For the standard multiplier, instead of mpyu rx,DBL0L,DBL1L; tst rx,rx  ,
  59    we can do:
  60    sub rx,DBL0L,1; bic rx,DBL0L,rx; lsr rx,rx; norm rx,rx; asl.f 0,DBL1L,rx  */
  61
  62 __muldf3_support: /* This label makes debugger output saner.  */
  63 /* If one number is denormal, subtract some from the exponent of the other
  64    one (if the other exponent is too small, return 0), and normalize the
  65    denormal.  Then re-run the computation.  */
  66         .balign 4
  67         FUNC(__muldf3)
  68 .Ldenorm_dbl0:
  69         mov_s r12,DBL0L
  70         mov_s DBL0L,DBL1L
  71         mov_s DBL1L,r12
  72         mov_s r12,DBL0H
  73         mov_s DBL0H,DBL1H
  74         mov_s DBL1H,r12
  75         and r11,DBL0H,r9
  76 .Ldenorm_dbl1:
  77         brhs r11,r9,.Linf_nan
  78         brhs 0x3ca00001,r11,.Lret0
  79         sub_s DBL0H,DBL0H,DBL1H
  80         bmsk_s DBL1H,DBL1H,30
  81         add_s DBL0H,DBL0H,DBL1H
  82         breq_s DBL1H,0,.Ldenorm_2
  83         norm r12,DBL1H
  84
  85         sub_s r12,r12,10
  86         asl r5,r12,20
  87         asl_s DBL1H,DBL1H,r12
  88         sub DBL0H,DBL0H,r5
  89         neg r5,r12
  90         lsr r6,DBL1L,r5
  91         asl_s DBL1L,DBL1L,r12
  92         b.d __muldf3
  93         add_s DBL1H,DBL1H,r6
  94
  95         .balign 4
  96 .Linf_nan:
  97         bclr r12,DBL1H,31
  98         xor_s DBL1H,DBL1H,DBL0H
  99         bclr_s DBL0H,DBL0H,31
 100         max r8,DBL0H,r12 ; either NaN -> NaN ; otherwise inf
 101         or.f 0,DBL0H,DBL0L
 102         mov_s DBL0L,0
 103         or.ne.f DBL1L,DBL1L,r12
 104         not_s DBL0H,DBL0L ; inf * 0 -> NaN
 105         mov.ne DBL0H,r8
 106         tst_s DBL1H,DBL1H
 107         j_s.d [blink]
 108         bset.mi DBL0H,DBL0H,31
 109
 110 .Lret0: xor_s DBL0H,DBL0H,DBL1H
 111         bclr DBL1H,DBL0H,31
 112         xor_s DBL0H,DBL0H,DBL1H
 113         j_s.d [blink]
 114         mov_l DBL0L,0
 115
 116         .balign 4
 117 .Ldenorm_2:
 118         breq_s DBL1L,0,.Lret0 ; 0 input -> 0 output
 119         norm.f r12,DBL1L
 120
 121         mov.mi r12,21
 122         add.pl r12,r12,22
 123         neg r11,r12
 124         asl_s r12,r12,20
 125         lsr.f DBL1H,DBL1L,r11
 126         ror DBL1L,DBL1L,r11
 127         sub_s DBL0H,DBL0H,r12
 128         mov.eq DBL1H,DBL1L
 129         sub_s DBL1L,DBL1L,DBL1H
 130         /* Fall through.  */
 131         .global __muldf3
 132         .balign 4
 133 __muldf3:
 134         ld.as r9,[pcl,0x4b] ; ((.L7ff00000-.+2)/4)]
 135         MPYHU r4,DBL0L,DBL1L
 136         bmsk r6,DBL0H,19
 137         bset r6,r6,20
 138         mpyu r7,r6,DBL1L
 139         and r11,DBL0H,r9
 140         breq r11,0,.Ldenorm_dbl0
 141         MPYHU r8,r6,DBL1L
 142         bmsk r10,DBL1H,19
 143         bset r10,r10,20
 144         MPYHU r5,r10,DBL0L
 145         add.f r4,r4,r7
 146         and r12,DBL1H,r9
 147         MPYHU r7,r6,r10
 148         breq r12,0,.Ldenorm_dbl1
 149         adc.f r5,r5,r8
 150         mpyu r8,r10,DBL0L
 151         breq r11,r9,.Linf_nan
 152         breq r12,r9,.Linf_nan
 153         mpyu r6,r6,r10
 154         add.cs r7,r7,1
 155         add.f r4,r4,r8
 156         mpyu r10,DBL1L,DBL0L
 157         bclr r8,r9,30 ; 0x3ff00000
 158         adc.f r5,r5,r6
 159         ; XMAC write-back stall / std. mult stall is one cycle later
 160         bclr r6,r9,20 ; 0x7fe00000
 161         add.cs r7,r7,1 ; fraction product in r7:r5:r4
 162         tst r10,r10
 163         bset.ne r4,r4,0 ; put least significant word into sticky bit
 164         lsr.f r10,r7,9
 165         add_l r12,r12,r11 ; add exponents
 166         rsub.eq r8,r8,r9 ; 0x40000000
 167         sub r12,r12,r8 ; subtract bias + implicit 1
 168         brhs.d r12,r6,.Linf_denorm
 169         rsub r10,r10,12
 170 .Lshift_frac:
 171         neg r8,r10
 172         asl r6,r4,r10
 173         lsr DBL0L,r4,r8
 174         add.f 0,r6,r6
 175         btst.eq DBL0L,0
 176         cmp.eq r4,r4 ; round to nearest / round to even
 177         asl r4,r5,r10
 178         lsr r5,r5,r8
 179         adc.f DBL0L,DBL0L,r4
 180         xor.f 0,DBL0H,DBL1H
 181         asl r7,r7,r10
 182         add_s r12,r12,r5
 183         adc DBL0H,r12,r7
 184         j_s.d [blink]
 185         bset.mi DBL0H,DBL0H,31
 186
 187 /* We have checked for infinity / NaN input before, and transformed
 188    denormalized inputs into normalized inputs.  Thus, the worst case
 189    exponent overflows are:
 190        1 +     1 - 0x400 == 0xc02 : maximum underflow
 191    0x7fe + 0x7fe - 0x3ff == 0xbfd ; maximum overflow
 192    N.B. 0x7e and 0x7f are also values for overflow.
 193
 194    If (r12 <= -54), we have an underflow to zero.  */
 195         .balign 4
 196 .Linf_denorm:
 197         brlo r12,0xc0000000,.Linf
 198         asr r6,r12,20
 199         mov_s r12,0
 200         add.f r10,r10,r6
 201         brgt r10,0,.Lshift_frac
 202         beq_s .Lround_frac
 203         add.f r10,r10,32
 204 .Lshift32_frac:
 205         tst r4,r4
 206         mov r4,r5
 207         bset.ne r4,r4,1
 208         mov r5,r7
 209         mov r7,0
 210         brge r10,1,.Lshift_frac
 211         breq r10,0,.Lround_frac
 212         add.f r10,r10,32
 213         brgt r10,21,.Lshift32_frac
 214         b_s .Lret0
 215
 216 .Lround_frac:
 217         add.f 0,r4,r4
 218         btst.eq r5,0
 219         mov_s DBL0L,r5
 220         mov_s DBL0H,r7
 221         adc.eq.f DBL0L,DBL0L,0
 222         j_s.d [blink]
 223
 224         adc.eq DBL0H,DBL0H,0
 225
 226 .Linf:  xor.f DBL1H,DBL1H,DBL0H
 227         mov_s DBL0L,0
 228         mov_s DBL0H,r9
 229         j_s.d [blink]
 230         bset.mi DBL0H,DBL0H,31
 231         ENDFUNC(__muldf3)
 232
 233         .balign 4
 234 .L7ff00000:
 235         .long 0x7ff00000