A question about integer promotion in GCC

[Joseph S. Myers]

On Mon, 6 Sep 2004, Nathan Sidwell wrote:

> Ah, I see we're actually sort of in agreement.  I'd prefer not to see the
> stepping-stone pre-gimple stage you propose -- mainly as a driver to force
> the other optimizations to be written.  Perhaps the simplest way to do this

Not doing X in order to force Y to be done, or in the expectation that Y 
will be done and make X unnecessary, tends to lead to regressions.  This 
has happened several times with temporary fixes for particular bugs going 
on a release branch, but not on mainline in the expectation there will be 
a better fix going on mainline later - the better fix sometimes doesn't 
materialise and we're left with a regression to deal with again for the 
next release.  So I prefer just keeping mainline regression-free, even if 
that means that sometimes there is something temporary there we want to 
supersede.

Exactly how fold is kept in operation until all its optimisations are 
implemented on GIMPLE is something I don't think matters that much.

Determining which bits of folding should be done at -O0 (at present most 
but not all of it is) to get the quickest compile times will need 
experimentation once it is operating on GIMPLE.

-- 
Joseph S. Myers               http://www.srcf.ucam.org/~jsm28/gcc/
  http://www.srcf.ucam.org/~jsm28/gcc/#c90status - status of C90 for GCC 3.5
    jsm@polyomino.org.uk (personal mail)
    jsm28@gcc.gnu.org (Bugzilla assignments and CCs)