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Re: [RFC] Curious REG_EQUAL note for multiplication


Kaz Kojima wrote:
> Dave Korn <dave.korn.cygwin@googlemail.com> wrote:

>>   Tagging the correct note onto a nop-move sequence was suggested at the time
>> as a possible solution.  I think I tried it and it didn't work first time and
>> I never had a chance to track it any further at the time.
> 
> I've tried to add a (set DIreg DIreg) insn at expand_mult_const
> associated with the note, but it can't survive to the CSE phase.

  Urgh.  No real surprise I suppose.  If you wanted to try an experiment, you
might get it to be preserved by marking it volatile, but it wouldn't be a good
production solution to place a scheduling barrier at the end of every
multi-word register manipulation sequence!

    cheers,
      DaveK


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