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Re: peephole2: dead regs not marked as dead

On 10/29/2010 05:08 PM, Georg Lay wrote: 
As far as I understand the internals, peephole2 matches due to predicates and
condition, it does not care for constraints (except for optional match_scratch)

Yes, I was referring as "using constraints in the define_insn". But you're dong that as far as I see.

Maybe it's better to write it as a split1 that works prior to
reload instead of split2 that works after reload.

Yes, a split1 sounds much better. It will give much more freedom to reload and the register allocation to do exactly the liveness-based kind of optimization that you're doing with a peephole.

I don't know. match_scratch has the disadvantage that the input
pattern will become a PARALLEL and is no more a single_set.

I don't understand why you mentioned match_scratch :) anyway note that a parallel of SET and CLOBBERs is a single_set.

Paolo

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