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Re: [PATCH 4/5] Don't mark targets of unconditional jumps with side effects as FALLTHRU.
- From: Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>
- To: Jeff Law <law at redhat dot com>, Marcin KoÅcielnicki <koriakin at 0x04 dot net>, gcc-patches at gcc dot gnu dot org
- Date: Fri, 22 Jan 2016 08:44:11 +0100
- Subject: Re: [PATCH 4/5] Don't mark targets of unconditional jumps with side effects as FALLTHRU.
- Authentication-results: sourceware.org; auth=none
- References: <1451762204-13364-1-git-send-email-koriakin at 0x04 dot net> <1451762204-13364-5-git-send-email-koriakin at 0x04 dot net> <56A0AD5F dot 8000702 at linux dot vnet dot ibm dot com> <56A16567 dot 5090103 at redhat dot com>
On 01/22/2016 12:10 AM, Jeff Law wrote:
> On 01/21/2016 03:05 AM, Andreas Krebbel wrote:
>> On 01/02/2016 08:16 PM, Marcin KoÅcielnicki wrote:
>>> When an unconditional jump with side effects targets an immediately
>>> following label, rtl_tidy_fallthru_edge is called. Since it has side
>>> effects, it doesn't remove the jump, but the label is still marked
>>> as fallthru. This later causes a verification error. Do nothing in this
>>> case instead.
>>>
>>> gcc/ChangeLog:
>>>
>>> * cfgrtl.c (rtl_tidy_fallthru_edge): Bail for unconditional jumps
>>> with side effects.
>>
>> The change looks ok to me (although I'm not able to approve it). Could you please run regressions
>> tests on x86_64 with that change?
>>
>> Perhaps a short comment in the code would be good.
> I think the patch is technically fine, the question is does it fix a
> visible bug? I read the series as new feature enablement so I put this
> patch into my gcc7 queue.
We need the patch for the S/390 split-stack implementation which we would like to see in GCC 6. I'm
aware that this isn't stage 3 material but people seem to have reasons to really want split stack on
S/390 asap and we would have to backport this feature anyway. Therefore I would prefer to have it in
the official release already. That's the only common code change we would need for that.
I've started a bootstrap and regression test for the patch also on Power.
Do you see a chance we can get this into GCC 6?
Bye,
-Andreas-