Re: Code optimization only in loops

[Paolo Bonzini <paolo dot bonzini at gmail dot com>]

Jean Christophe Beyler wrote:
> I've gone back to this problem (since I've solved another one ;-)).
> And I've moved forward a bit:
>
> It seems that if I consider an array of characters, there are no
> longer any shifts and therefore I do get my two loads with the use of
> an offset:

The reason there are shifts instead of multiplies is that 
multiplications are canonicalized to shifts whenever possible outside 
addresses, because a shift instruction should be more efficient.

The interesting dump should be fwprop which is where the address 
generation happens.

From your dumps, however, the problem seems to be that you do not have 
a shift-by-immediate instruction.  You may consider adding it even 
though it does not apply to your assembly, either with 
define_insn_and_split or by loosening the predicate and keeping a "r" 
constraint (or whatever you're using now).

Paolo