[Bug tree-optimization/21982] GCC should combine adjacent stdio calls

["ghazi at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From ghazi at gcc dot gnu dot org  2005-06-09 16:49 -------
(In reply to comment #4)
> (In reply to comment #1)
> > If side effects appear in the arguments, that also would be a problem, e.g.:
> > 
> > printf("%d", i++);
> > printf("%d", i++);
> > 
> > should not be turned into:
> > 
> > printf("%d%d", i++, i++);
> > 
> There should be little danger of this.  Side-effects are explicitly exposed in
> GIMPLE.  As long as the printf() calls are adjacent, we should be able to
> combine them.
> Diego.

I'm not sure.  In my specific example above, after the combination we don't 
know which i++ gets executed first because the order is not guaranteed within 
an argument list of a single function call (right?)  So if we want to include 
combinations whose arguments have side-effects, we have to prove they don't 
interact with any other arguments.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21982