This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [PATCH, PR68976] Use reaching def phi arg in sese_add_exit_phis_edge
- From: Sebastian Pop <sebpop at gmail dot com>
- To: Tom de Vries <Tom_deVries at mentor dot com>
- Cc: Tobias Grosser <tobias at grosser dot es>, "gcc-patches at gnu dot org" <gcc-patches at gnu dot org>
- Date: Fri, 15 Jan 2016 13:57:52 -0600
- Subject: Re: [PATCH, PR68976] Use reaching def phi arg in sese_add_exit_phis_edge
- Authentication-results: sourceware.org; auth=none
- References: <5698FB0F dot 3090908 at mentor dot com> <CAFk3UF834TY4HTgEwrP8iPEcaoAq0k==ZyLc9n+6cX8R06xYxg at mail dot gmail dot com>
On Fri, Jan 15, 2016 at 11:19 AM, Sebastian Pop <sebpop@gmail.com> wrote:
> On Fri, Jan 15, 2016 at 7:58 AM, Tom de Vries <Tom_deVries@mentor.com> wrote:
>> During scop detection/canonicalize_loop_closed_ssa_form, an exit phi is
>> introduced in the loop for _24:
>> ...
>> <bb 21>:
>> # _58 = PHI <_24(22)>
>> ...
>> Note that _24 is not defined in the loop, but before it. AFAIU the header
>> comment of canonicalize_loop_closed_ssa_form, this phi is not needed. That
>> might be the root cause of the bug,
>
> I think that may be the problem, as it is invariant in the loops, so
> it is considered to be a parameter of the scop.
> Let me see if we could avoid adding that phi node in the first place.
I just sent out a patch that implements this.
Thanks Tom for pointing out the issue!