From: Jeff Law <jeffreyalaw@gmail.com>
To: Alexandre Oliva <oliva@adacore.com>, gcc-patches@gcc.gnu.org
Cc: cnsun@uwaterloo.ca
Subject: Re: [PR100843] store by mult pieces: punt on max_len < min_len
Date: Fri, 10 Dec 2021 15:33:27 -0700 [thread overview]
Message-ID: <00e83976-f1f2-9080-6d97-2703ed1dc7a4@gmail.com> (raw)
In-Reply-To: <orh7bh77ao.fsf@lxoliva.fsfla.org>
On 12/9/2021 3:16 PM, Alexandre Oliva via Gcc-patches wrote:
> The testcase confuses the code that detects min and max len for the
> memset, so max_len ends up less than min_len. That shouldn't be
> possible, but the testcase requires us to handle this case.
>
> The store-by-mult-pieces algorithm actually relies on min and max
> lengths, so if we find them to be inconsistent, the best we can do is
> punting.
>
> Regstrapped on x86_64-linux-gnu. Ok to install?
>
>
> for gcc/ChangeLog
>
> PR middle-end/100843
> * builtins.c (try_store_by_multiple_pieces): Fail if min_len
> is greater than max_len.
>
> for gcc/testsuite/ChangeLog
>
> PR middle-end/100843
> * gcc.dg/pr100843.c: New.
The patch is clearly safe. My question is should we have caught this
earlier in the call chain? If so, I'd prefer to fix it there and leave
the gcc_unreachable in place to catch other bogus cases that may get
into try_store_by_multiple_pieces.
Jeff
next prev parent reply other threads:[~2021-12-10 22:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-09 22:16 Alexandre Oliva
2021-12-10 22:33 ` Jeff Law [this message]
2021-12-11 5:18 ` Alexandre Oliva
2021-12-14 21:58 ` Jeff Law
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