Re: "Mini" tags to reduce the number of op codes

Liste des GroupesRevenir à c arch 
Sujet : Re: "Mini" tags to reduce the number of op codes
De : mitchalsup (at) *nospam* aol.com (MitchAlsup1)
Groupes : comp.arch
Date : 15. Apr 2024, 00:25:52
Autres entêtes
Organisation : Rocksolid Light
Message-ID : <86d1dd03deee83e339afa725524ab259@www.novabbs.org>
References : 1 2
User-Agent : Rocksolid Light
Anton Ertl wrote:

I have a similar problem for the carry and overflow bits in
< http://www.complang.tuwien.ac.at/anton/tmp/carry.pdf >, and chose to
let those bits not survive across calls; if there was a cheap solution
for the problem, it would eliminate this drawback of my idea.
My 66000 ISA can encode the mpn_add_n() inner loop in 5-instructions
whereas RISC-V encodes the inner loop in 11 instructions.
Source code:
void mpn_add_n( uint64_t sum, uint64_t a, unit64_t b, int n )
{
     uint64_t c = 0;
     for( int i = 0; i < n; i++ )
     {
          {c, sum[i]} = a[i] + b[i] + c;
     }
     return
}
Assembly code::
     .global mpn_add_n
mpn_add_n:
     MOV   R5,#0     // c
     MOV   R6,#0     // i
     VEC   R7,{}
     LDD   R8,[R2,Ri<<3]
     LDD   R9,[R3,Ri<<3]
     CARRY R5,{{IO}}
     ADD   R10,R8,R9
     STD   R10,[R1,Ri<<3]
     LOOP  LT,R6,#1,R4
     RET
So, adding a few "bells and whistles" to RISC-V does give you a
performance gain (1.38×); using a well designed ISA gives you a
performance gain of 2.00× !! {{moral: don't stop too early}}
Note that all the register bookkeeping has disappeared !! because
of the indexed memory reference form.
As I count executing instructions, VEC does not execute, nor does
CARRY--CARRY causes the subsequent ADD to take C input as carry and
the carry produced by ADD goes back in C. Loop performs the ADD-CMP-
BC sequence in a single instruction and in a single clock.

Date Sujet#  Auteur
3 Apr 24 * "Mini" tags to reduce the number of op codes81Stephen Fuld
3 Apr 24 +* Re: "Mini" tags to reduce the number of op codes8Anton Ertl
15 Apr 24 i+* Re: "Mini" tags to reduce the number of op codes6MitchAlsup1
15 Apr 24 ii`* Re: "Mini" tags to reduce the number of op codes5Terje Mathisen
15 Apr 24 ii +- Re: "Mini" tags to reduce the number of op codes1Terje Mathisen
15 Apr 24 ii `* Re: "Mini" tags to reduce the number of op codes3MitchAlsup1
16 Apr 24 ii  `* Re: "Mini" tags to reduce the number of op codes2Terje Mathisen
16 Apr 24 ii   `- Re: "Mini" tags to reduce the number of op codes1MitchAlsup1
17 Apr 24 i`- Re: "Mini" tags to reduce the number of op codes1Stephen Fuld
3 Apr 24 +* Re: "Mini" tags to reduce the number of op codes3Thomas Koenig
17 Apr 24 i`* Re: "Mini" tags to reduce the number of op codes2Stephen Fuld
17 Apr 24 i `- Re: "Mini" tags to reduce the number of op codes1BGB-Alt
3 Apr 24 +* Re: "Mini" tags to reduce the number of op codes12BGB-Alt
3 Apr 24 i+* Re: "Mini" tags to reduce the number of op codes9MitchAlsup1
4 Apr 24 ii+* Re: "Mini" tags to reduce the number of op codes7Terje Mathisen
4 Apr 24 iii+* Re: "Mini" tags to reduce the number of op codes3Michael S
4 Apr 24 iiii`* Re: "Mini" tags to reduce the number of op codes2Terje Mathisen
4 Apr 24 iiii `- Re: "Mini" tags to reduce the number of op codes1Michael S
5 Apr 24 iii`* Re: "Mini" tags to reduce the number of op codes3BGB-Alt
5 Apr 24 iii `* Re: "Mini" tags to reduce the number of op codes2MitchAlsup1
5 Apr 24 iii  `- Re: "Mini" tags to reduce the number of op codes1BGB
17 Apr 24 ii`- Re: "Mini" tags to reduce the number of op codes1Stephen Fuld
3 Apr 24 i`* Re: "Mini" tags to reduce the number of op codes2MitchAlsup1
4 Apr 24 i `- Re: "Mini" tags to reduce the number of op codes1BGB
5 Apr 24 +* Re: "Mini" tags to reduce the number of op codes54John Savard
5 Apr 24 i+- Re: "Mini" tags to reduce the number of op codes1BGB-Alt
5 Apr 24 i`* Re: "Mini" tags to reduce the number of op codes52MitchAlsup1
7 Apr 24 i `* Re: "Mini" tags to reduce the number of op codes51John Savard
7 Apr 24 i  +* Re: "Mini" tags to reduce the number of op codes6MitchAlsup1
8 Apr 24 i  i`* Re: "Mini" tags to reduce the number of op codes5John Savard
8 Apr 24 i  i +* Re: "Mini" tags to reduce the number of op codes2Thomas Koenig
17 Apr 24 i  i i`- Re: "Mini" tags to reduce the number of op codes1John Savard
8 Apr 24 i  i `* Re: "Mini" tags to reduce the number of op codes2MitchAlsup1
17 Apr 24 i  i  `- Re: "Mini" tags to reduce the number of op codes1John Savard
7 Apr 24 i  `* Re: "Mini" tags to reduce the number of op codes44Thomas Koenig
7 Apr 24 i   `* Re: "Mini" tags to reduce the number of op codes43MitchAlsup1
8 Apr 24 i    `* Re: "Mini" tags to reduce the number of op codes42Thomas Koenig
8 Apr 24 i     +- Re: "Mini" tags to reduce the number of op codes1Anton Ertl
9 Apr 24 i     `* Re: "Mini" tags to reduce the number of op codes40Thomas Koenig
9 Apr 24 i      +* Re: "Mini" tags to reduce the number of op codes38BGB
9 Apr 24 i      i`* Re: "Mini" tags to reduce the number of op codes37MitchAlsup1
10 Apr 24 i      i `* Re: "Mini" tags to reduce the number of op codes36BGB-Alt
10 Apr 24 i      i  +* Re: "Mini" tags to reduce the number of op codes31MitchAlsup1
10 Apr 24 i      i  i+* Re: "Mini" tags to reduce the number of op codes23BGB
10 Apr 24 i      i  ii`* Re: "Mini" tags to reduce the number of op codes22MitchAlsup1
10 Apr 24 i      i  ii +* Re: "Mini" tags to reduce the number of op codes3BGB-Alt
10 Apr 24 i      i  ii i`* Re: "Mini" tags to reduce the number of op codes2MitchAlsup1
11 Apr 24 i      i  ii i `- Re: "Mini" tags to reduce the number of op codes1BGB
10 Apr 24 i      i  ii +- Re: "Mini" tags to reduce the number of op codes1BGB-Alt
11 Apr 24 i      i  ii +* Re: "Mini" tags to reduce the number of op codes16MitchAlsup1
11 Apr 24 i      i  ii i`* Re: "Mini" tags to reduce the number of op codes15Michael S
11 Apr 24 i      i  ii i `* Re: "Mini" tags to reduce the number of op codes14BGB
11 Apr 24 i      i  ii i  `* Re: "Mini" tags to reduce the number of op codes13MitchAlsup1
11 Apr 24 i      i  ii i   +* Re: "Mini" tags to reduce the number of op codes9BGB-Alt
12 Apr 24 i      i  ii i   i`* Re: "Mini" tags to reduce the number of op codes8MitchAlsup1
12 Apr 24 i      i  ii i   i `* Re: "Mini" tags to reduce the number of op codes7BGB
12 Apr 24 i      i  ii i   i  `* Re: "Mini" tags to reduce the number of op codes6MitchAlsup1
12 Apr 24 i      i  ii i   i   `* Re: "Mini" tags to reduce the number of op codes5BGB
13 Apr 24 i      i  ii i   i    +- Re: "Mini" tags to reduce the number of op codes1MitchAlsup1
13 Apr 24 i      i  ii i   i    `* Re: "Mini" tags to reduce the number of op codes3MitchAlsup1
13 Apr 24 i      i  ii i   i     +- Re: "Mini" tags to reduce the number of op codes1BGB
15 Apr 24 i      i  ii i   i     `- Re: "Mini" tags to reduce the number of op codes1BGB-Alt
12 Apr 24 i      i  ii i   `* Re: "Mini" tags to reduce the number of op codes3Michael S
12 Apr 24 i      i  ii i    +- Re: "Mini" tags to reduce the number of op codes1Michael S
15 Apr 24 i      i  ii i    `- Re: "Mini" tags to reduce the number of op codes1MitchAlsup1
11 Apr 24 i      i  ii `- Re: "Mini" tags to reduce the number of op codes1Terje Mathisen
11 Apr 24 i      i  i`* Re: "Mini" tags to reduce the number of op codes7Paul A. Clayton
11 Apr 24 i      i  i +- Re: "Mini" tags to reduce the number of op codes1BGB
11 Apr 24 i      i  i +* Re: "Mini" tags to reduce the number of op codes2BGB-Alt
12 Apr 24 i      i  i i`- Re: "Mini" tags to reduce the number of op codes1MitchAlsup1
12 Apr 24 i      i  i +* Re: "Mini" tags to reduce the number of op codes2MitchAlsup1
21 Apr 24 i      i  i i`- Re: "Mini" tags to reduce the number of op codes1Paul A. Clayton
21 Apr 24 i      i  i `- Re: "Mini" tags to reduce the number of op codes1Paul A. Clayton
10 Apr 24 i      i  `* Re: "Mini" tags to reduce the number of op codes4Chris M. Thomasson
10 Apr 24 i      i   `* Re: "Mini" tags to reduce the number of op codes3BGB
10 Apr 24 i      i    `* Re: "Mini" tags to reduce the number of op codes2Chris M. Thomasson
10 Apr 24 i      i     `- Re: "Mini" tags to reduce the number of op codes1BGB-Alt
13 Apr 24 i      `- Re: "Mini" tags to reduce the number of op codes1Brian G. Lucas
15 Apr 24 +- Re: "Mini" tags to reduce the number of op codes1MitchAlsup1
17 Apr 24 `* Re: "Mini" tags to reduce the number of op codes2Stephen Fuld
17 Apr 24  `- Re: "Mini" tags to reduce the number of op codes1MitchAlsup1

Haut de la page

Les messages affichés proviennent d'usenet.

NewsPortal