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Re: muldi3, divdi3 and remdi3 patterns
- To: Mark Klein <mklein at dis dot com>
- Subject: Re: muldi3, divdi3 and remdi3 patterns
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Thu, 12 Aug 1999 02:54:56 -0600
- cc: gcc at gcc dot gnu dot org
- Reply-To: law at cygnus dot com
In message <4.1.19990811073640.00ce36f0@garfield.dis.com>you write:
> case UDIV:
> case MOD:
> case UMOD:
> return COSTS_N_INSNS (60);
>
> Did you base the costs on anything concrete such as number of cycles
> or instructions per operation, or are these arbitrary values that
> simply indicate the relative costs? What does the "60" represent?
I don't remember. It's been many many years since I even looked at those
cost macros.
Basically they're supposed to provide rough estimates of the number of
instructions/cycles necessary to implement each operation (on average).
Whether or not the PA mul/div stuff follows that convention I'm not sure
(again, it's been a very very long time).
jeff