From: Marek Polacek <polacek@redhat.com>
To: Florian Weimer <fw@deneb.enyo.de>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,
Richard Sandiford <richard.sandiford@arm.com>,
Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Subject: Re: PATCH to add more FALLTHRU markers
Date: Tue, 27 Sep 2016 19:39:00 -0000 [thread overview]
Message-ID: <20160927193337.GK3223@redhat.com> (raw)
In-Reply-To: <874m51xhtl.fsf@mid.deneb.enyo.de>
On Tue, Sep 27, 2016 at 09:29:10PM +0200, Florian Weimer wrote:
> * Marek Polacek:
>
> > On Tue, Sep 27, 2016 at 08:58:59PM +0200, Florian Weimer wrote:
> >> * Marek Polacek:
> >>
> >> > @@ -11498,21 +11508,23 @@
> >> > case V64QImode:
> >> > case V32HImode:
> >> > if (TARGET_AVX512F)
> >> > - {
> >> > - tmp = "p<logic>";
> >> > - ssesuffix = "q";
> >> > - break;
> >> > - }
> >> > + {
> >> > + tmp = "p<logic>";
> >> > + ssesuffix = "q";
> >> > + break;
> >> > + }
> >> > + /* FALLTHRU */
> >> > case V32QImode:
> >> > case V16HImode:
> >> > case V16QImode:
> >> > case V8HImode:
> >> > if (TARGET_AVX512VL || TARGET_AVX2 || TARGET_SSE2)
> >> > - {
> >> > - tmp = "p<logic>";
> >> > - ssesuffix = TARGET_AVX512VL ? "q" : "";
> >> > - break;
> >> > - }
> >> > + {
> >> > + tmp = "p<logic>";
> >> > + ssesuffix = TARGET_AVX512VL ? "q" : "";
> >> > + break;
> >> > + }
> >> > + /* FALLTHRU */
> >> > default:
> >> > gcc_unreachable ();
> >> > }
> >>
> >> Why isn't this a bug? Wouldn't we want to reach gcc_unreachable ()
> >> if, for example !TARGET_AVX512F and TARGET_SSE2?
> >
> > ?? In that case the FALLTHRU should be there if it's intentional that
> > we may fall through to default. Otherwise not sure what you mean.
>
> Not sure if I read this code correctly, but if we fall through from
> V32HImode, and we have TARGET_SSE2 set, we execute this code:
>
> tmp = "p<logic>";
> ssesuffix = TARGET_AVX512VL ? "q" : "";
>
> And not gcc_unreachable (), as is probably intended.
Kyrill, can you please decide? Thanks.
Marek
next prev parent reply other threads:[~2016-09-27 19:33 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 16:55 Marek Polacek
2016-09-27 19:00 ` Richard Sandiford
2016-09-29 17:22 ` Marek Polacek
2016-09-27 19:08 ` Florian Weimer
2016-09-27 19:22 ` Marek Polacek
2016-09-27 19:33 ` Florian Weimer
2016-09-27 19:39 ` Marek Polacek [this message]
2016-09-27 20:13 ` Jakub Jelinek
2016-09-29 17:17 ` Marek Polacek
2016-09-29 20:21 ` Jakub Jelinek
2016-09-30 21:31 ` [PATCH] FALLTHRU markers for sse.md and some cleanups Jakub Jelinek
2016-10-01 8:31 ` Uros Bizjak
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