[Bug tree-optimization/16225] [3.5 regression] ICE: verify_ssa failed.

[dnovillo at redhat dot com]

------- Additional Comments From dnovillo at redhat dot com  2004-08-12 18:35 -------
Subject: Re:  [3.5 regression] ICE: verify_ssa
	failed.

On Sun, 2004-08-01 at 17:33, giovannibajo at libero dot it wrote:
> ------- Additional Comments From giovannibajo at libero dot it  2004-08-01 21:33 -------
> Diego, can you have a quick look at these patches? At least, if you can comment 
> on the patch to verify_flow_insensitive_alias_info, Jie would know whether it 
> should work on making it bootstrap fixing the problems it exposes.
>
Well, call-clobberedness and aliasing are not necessarily related.

foo (int i)
{
   int *p, a, b;

   if (i > 10)
     p = &b;
   bar (&a);
   return *p;
}

Suppose that for some reason we couldn't use points-to information and
end up with alias(*p) = { a, b }.  You don't really want the call to
'bar()' to clobber 'b', so marking 'b' call-clobbered is too
pessimistic.

I'm testing a patch to only mark call-clobbered variables whose address
escape.  add_may_alias should not be setting call-clobbered bits.


Diego.



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16225