[Bug tree-optimization/38458] copy-propagation doesn't handle cycles

[dnovillo at google dot com]

------- Comment #1 from dnovillo at google dot com  2008-12-09 20:22 -------
Subject: Re:  New: copy-propagation doesn't 
        handle cycles

On Tue, Dec 9, 2008 at 14:53, rguenth at gcc dot gnu dot org
<gcc-bugzilla@gcc.gnu.org> wrote:
>        {
> -         phi_val.value = arg;
> +         phi_val.value = arg_val->value;
>          continue;
>        }

This looks OK.

> -  rhs_val = get_copy_of_val (rhs);
> +  rhs_val = get_last_copy_of (rhs);

We don't want to propagate using get_last_copy_of here.  The reason
now escapes me, but it should be documented in the code.  It was
related to phi-cycles, but it's been a long time.


Diego.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38458