From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeffrey A Law <law@cygnus.com>
To: Marcio de Oliveira Buss <ra990898@ic.unicamp.br>
Cc: gcc@gcc.gnu.org
Subject: Re: CFG 
Date: Wed, 28 Jun 2000 14:15:00 -0000
Message-id: <5057.962226136@upchuck>
References: <Pine.GSO.4.10.10006281746080.16817-100000@xingu.dcc.unicamp.br>
X-SW-Source: 2000-06/msg00734.html

  In message < Pine.GSO.4.10.10006281746080.16817-100000@xingu.dcc.unicamp.br >yo
u write:
  > 
  > 
  > 	Good Morning (afternoon) to all...
  >         Could you please help me? I want to know if the CFG constructed
  >  in the dataflow analysis is updated at each step subsequent steps of
  >  the compilation, and, in turn, remains until the Final phase of the
  >  compilation process. I want to transform the CFG into another structure
  >  but only after all the optimizations have been made over it. I know
  >  that the almost all optimizations are made over the RTL expressions,
  >  but I don't know if some optimization touchs the CFG. 
  >         In other words, I would like to know if the CFG is destructed      
  >   
  >  after the dataflow analysis, i.e., after the informations provided
  >  by the CFG are recorded for futures uses, or if the CFG remains        
  >  untouchable.
Most of the time we [re]build the cfg when we need it (ie, we don't assume
it's valid, except in a few special cases).  Most of the optimizers are
not using the cfg right now and do not keep it accurate.
jeff