[Bug tree-optimization/33434] [4.3 Regression] inlining miscompilation

[rguenther at suse dot de]

------- Comment #13 from rguenther at suse dot de  2007-10-29 13:12 -------
Subject: Re:  [4.3 Regression] inlining
 miscompilation

On Mon, 29 Oct 2007, razya at il dot ibm dot com wrote:

> > ------- Comment #11 from rguenther at suse dot de  2007-10-29 12:14 
> -------
> > Subject: Re:  [4.3 Regression] inlining
> >  miscompilation
> > 
> > On Mon, 29 Oct 2007, razya at il dot ibm dot com wrote:
> > 
> > > ------- Comment #10 from razya at il dot ibm dot com  2007-10-29 
> > 12:08 -------
> > > (In reply to comment #6)
> > > > Hmm, I have a question about IPA CP, should it call cfgcleanup 
> > also?  It does
> > > > not fix the problem here but it seems like a good idea.  I can 
> > test a patch
> > > > which adds the cfgcleanup if it is a good idea.
> > > 
> > > Hi Andrew
> > > IPA CP iterates the whole callgraph, so do you mean cfgcleanup for 
> each
> > > function?
> > 
> > Only for the clones it propagated constants into.
> > 
> > Richard.
> > 
> 
> IPA CP basically replaces the uses of the (always consatnt)parameter
> with the constant.
> This can be further folded by the ssa-cp pass on the cloned method. 
> So I'm not sure how necessary it is to have a control flow cleanup
> at this stage, but maybe I'm wrong...

Just because propagating the constants might result in

  if (0)
    ...

which cfg_cleanup is able to remove (or if (1)).

Richard.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33434