peephole2: dead regs not marked as dead

[Paolo Bonzini]

On 11/02/2010 11:39 AM, Georg Lay wrote:
> Paolo Bonzini schrieb:
>> On 11/02/2010 10:41 AM, Georg Lay wrote:
>>> What I do not understand is*why*  this works.
>>> The internals "16.16 How to Split Instructions" mention two flavours
>>> of insn
>>> splitting: One after reload for the scheduler and one during combine
>>> stage, the
>>> latter just doing single_set -->   2 * single_set splits for insns that
>>> do*not*
>>> match during combine stage.
>>
>> I think this is extremely out-of-date, I am sorry.  I read something
>> from Ian Lance Taylor on the mailing list recently about the history of
>> splits.  I cannot find it now, but basically the original purpose (help
>> combine to find matches for "big" patterns representing more than one
>> instruction) is now almost obsolete with define_insn_and_split, and the
>> split passes before and after reload have the biggest role in splitting.
>
> You mean this?
>
> http://gcc.gnu.org/ml/gcc/2010-10/msg00444.html

Yes, that and the follow up.

Paolo