Re: [PATCH] ppc32 use simplified mmenonics

Vincent Hanquez
2004-08-22T09:43:30Z

On Sat, Aug 21, 2004 at 08:45:26PM -0400, Albert Cahalan wrote:
> I'd rather you went the other way, replacing these
> barely-documented instructions with ones that are
> easy to look up. Motorola has about a zillion of
> these "simplified" instructions. I guess Motorola
> and IBM were jealous of Intel's CISC instructions.
>
> The big problem is this:
> THESE ARE NOT IN THE INDEX!!!!!!
>
> So, if I forget what one of these many instructions
> does, I'll have quite the time paging through the
> manual trying to find it.
>
> If it's not in the index, please avoid it.

Well,

let's analyse 'mr R1,R2'. Which is simplified instruction for moving register,
which represent the following instruction 'or R2,0,R1'

when you read 'mr' you obviously know what the source want to do.
However seeing 'or', for my part, I see logicial or operation.
In spite of the fact, there's some case when 'or' could simply move a
register, I guess that's not as obvious as 'mr' instruction.

I guess that's the same for multiple other simplified instruction

bne target = bc 4,2,target

When I see first form, I know exactly what the program do, whereas on
the second form : What the hell is 4,2 ?

So I'ld rather go with simplified instruction, even if that index
doesn't contain them (which I agree with you, is very bad).
There are still in Appendix F of my pdf and you can search with the find
utility include in your reader (xpdf does)

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