Re: copy propagation?

Hi,


  It's seem simple may be I'm wrong.


if you have got something like:


a0=a1
...
    =a0


you can replace every occurrence of a0 by a1.
e.g.
a0=a1 // now deadcode (if no side effects on the a0 variable)
suppress this instruction
...
      =a1


if you obtain for some phi node all the same right-hand parameters do
the same transformation for this phi node
e.g.
a0=a1 ...
        \ /
        a2=phi(a0,a1)
        ...
            = a2
becomes to
a0=a1 ... // now dead code (a0-a1)
        \ /
        a2=phi(a1,a1) // now dead code
        ...
            = a1


Theses things can be done during sparse representation building. And the
dead code is never introduced (immediately removed).






Pariah Sarathi Panda wrote:


> How can copy propagation be done using sparse data-flow information
> and without doing register renaming?


What's the signification of "without register renaming". There is
always renaming in copy propagation.


--
Anthony PIRON - Researcher
Universite Libre de Bruxelles, Department of Computer Science
CP 212 - Boulevard du Triomphe, B-1050 Bruxelles, Belgium
Tel. +32 2 650 50 55, Fax +32 2 650 56 09, GSM +32 478 530 022
Email: apiron@ulb.ac.be Web: http://www.ulb.ac.be/di/ssd/apiron

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