From: Peter Bergner <bergner@vnet.ibm.com>
To: Richard Biener <rguenther@suse.de>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,
Bill Schmidt <wschmidt@linux.vnet.ibm.com>,
Jakub Jelinek <jakub@redhat.com>
Subject: Re: [PATCH] Fix PR51513, switch statement with default case containing __builtin_unreachable leads to wild branch
Date: Thu, 20 Apr 2017 14:21:00 -0000 [thread overview]
Message-ID: <5bccbce6-5eb5-65a4-619f-55a04a286a5a@vnet.ibm.com> (raw)
In-Reply-To: <alpine.LSU.2.20.1704200932300.24645@zhemvz.fhfr.qr>
On 4/20/17 2:37 AM, Richard Biener wrote:
> Ok, so I think we should ensure that we remove the regular cases
> with unreachable destination, like in
>
> switch (i)
> {
> case 0:
> __builtin_unreachable ();
> default:;
> }
>
> and handle default with __builtin_unreachable () from switch
> expansion by omitting the range check for the jump table
> indexing (and choose a non-default case label for gaps).
Ok, I'll modify optimize_unreachable() to remove the unreachable
case statements, and leave the unreachable default case statement
for switch expansion so we can eliminate the range check. Thanks.
Peter
next prev parent reply other threads:[~2017-04-20 13:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 0:29 Peter Bergner
2017-04-13 8:14 ` Richard Biener
2017-04-13 11:07 ` Jakub Jelinek
2017-04-13 20:06 ` Peter Bergner
2017-04-20 8:08 ` Richard Biener
2017-04-20 14:21 ` Peter Bergner [this message]
2017-04-27 5:08 ` [PATCH, v3] " Peter Bergner
2017-04-27 12:46 ` Bernhard Reutner-Fischer
2017-04-27 15:16 ` Peter Bergner
2017-05-03 13:43 ` Richard Biener
2017-05-08 16:51 ` Peter Bergner
2017-05-08 17:57 ` Richard Biener
2017-05-08 18:26 ` Peter Bergner
2017-05-08 20:55 ` Peter Bergner
2017-05-09 7:57 ` Richard Biener
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