[Bug middle-end/32327] [4.2 Regression] Incorrect stack sharing causing removal of live code

["dougkwan at google dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #6 from dougkwan at google dot com  2007-06-13 21:50 -------
Subject: Re:  [4.2 Regression] Incorrect stack sharing causing removal of live
code

Fixing alias analysis in 4.2.0 will make this problem go away but it
does not change the underlying issue in the stack local sharing code.

13 Jun 2007 21:42:01 -0000, pinskia at gcc dot gnu dot org
<gcc-bugzilla@gcc.gnu.org>:
>
>
> ------- Comment #5 from pinskia at gcc dot gnu dot org  2007-06-13 21:42 -------
> (In reply to comment #2)
> > The address of dest has been passed to memcpy() and the alias analysis
> > considers the varaible to escape. So potentially foo() can see the value of
> > dest if memcpy() stash the pointer somewhere. This is impossible but the
> > compiler cannot prove this so it has to be conservative and treat foo() as a
> > potential reader of dest.
> We remove the call to memcpy (in 4.2) in .064t.fab and then alias5 should have
> changed it (dest) to be non ADDRESSABLE but it is not for some reason.
>
> I think may_alias is messed up in 4.2.0.  Also sink maybe should not be sinking
> stores.
>
>
> --
>
> pinskia at gcc dot gnu dot org changed:
>
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>       Known to work|4.3.0                       |4.3.0 4.1.1
>             Summary|Incorrect stack sharing     |[4.2 Regression] Incorrect
>                    |causing removal of live code|stack sharing causing
>                    |                            |removal of live code
>    Target Milestone|---                         |4.2.1
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32327
>
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32327