1;! HP-PA-1.1 __mpn_mul_1 -- Multiply a limb vector with a limb and store
2;! the result in a second limb vector.
3
4;! Copyright (C) 1992-2024 Free Software Foundation, Inc.
5
6;! This file is part of the GNU MP Library.
7
8;! The GNU MP Library is free software; you can redistribute it and/or modify
9;! it under the terms of the GNU Lesser General Public License as published by
10;! the Free Software Foundation; either version 2.1 of the License, or (at your
11;! option) any later version.
12
13;! The GNU MP Library is distributed in the hope that it will be useful, but
14;! WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15;! or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
16;! License for more details.
17
18;! You should have received a copy of the GNU Lesser General Public License
19;! along with the GNU MP Library. If not, see
20;! <https://www.gnu.org/licenses/>.
21
22
23;! INPUT PARAMETERS
24;! res_ptr r26
25;! s1_ptr r25
26;! size r24
27;! s2_limb r23
28
29;! This runs at 9 cycles/limb on a PA7000. With the used instructions, it can
30;! not become faster due to data cache contention after a store. On the
31;! PA7100 it runs at 7 cycles/limb, and that can not be improved either, since
32;! only the xmpyu does not need the integer pipeline, so the only dual-issue
33;! we will get are addc+xmpyu. Unrolling would not help either CPU.
34
35;! We could use fldds to read two limbs at a time from the S1 array, and that
36;! could bring down the times to 8.5 and 6.5 cycles/limb for the PA7000 and
37;! PA7100, respectively. We don't do that since it does not seem worth the
38;! (alignment) troubles...
39
40;! At least the PA7100 is rumored to be able to deal with cache-misses
41;! without stalling instruction issue. If this is true, and the cache is
42;! actually also lockup-free, we should use a deeper software pipeline, and
43;! load from S1 very early; (The loads and stores to -12(sp) will surely be
44;! in the cache.)
45
46 .text
47 .export __mpn_mul_1
48__mpn_mul_1:
49 .proc
50 .callinfo frame=64,no_calls
51 .entry
52
53 ldo 64(%r30),%r30
54 fldws,ma 4(%r25),%fr5
55 stw %r23,-16(%r30) ;! move s2_limb ...
56 addib,= -1,%r24,L$just_one_limb
57 fldws -16(%r30),%fr4 ;! ... into fr4
58 add %r0,%r0,%r0 ;! clear carry
59 xmpyu %fr4,%fr5,%fr6
60 fldws,ma 4(%r25),%fr7
61 fstds %fr6,-16(%r30)
62 xmpyu %fr4,%fr7,%fr8
63 ldw -12(%r30),%r20 ;! least significant limb in product
64 ldw -16(%r30),%r28
65
66 fstds %fr8,-16(%r30)
67 addib,= -1,%r24,L$end
68 ldw -12(%r30),%r1
69
70;! Main loop
71L$loop:
72 fldws,ma 4(%r25),%fr5
73 stws,ma %r20,4(%r26)
74 addc %r28,%r1,%r20
75 xmpyu %fr4,%fr5,%fr6
76 ldw -16(%r30),%r28
77 fstds %fr6,-16(%r30)
78 addib,<> -1,%r24,L$loop
79 ldw -12(%r30),%r1
80
81L$end:
82 stws,ma %r20,4(%r26)
83 addc %r28,%r1,%r20
84 ldw -16(%r30),%r28
85 stws,ma %r20,4(%r26)
86 addc %r0,%r28,%r28
87 bv 0(%r2)
88 ldo -64(%r30),%r30
89
90L$just_one_limb:
91 xmpyu %fr4,%fr5,%fr6
92 fstds %fr6,-16(%r30)
93 ldw -16(%r30),%r28
94 ldo -64(%r30),%r30
95 bv 0(%r2)
96 fstws %fr6R,0(%r26)
97
98 .exit
99 .procend
100

source code of glibc/sysdeps/hppa/hppa1.1/mul_1.S