From: Richard Biener <richard.guenther@gmail.com>
To: GCC <gcc@gcc.gnu.org>, Marc Glisse <marc.glisse@inria.fr>,
Andrew MacLeod <amacleod@redhat.com>
Subject: Re: bug in DSE?
Date: Sat, 13 Feb 2021 15:25:48 +0100 [thread overview]
Message-ID: <37E68E93-64E3-4690-A65C-B4FBDEB4B2EA@gmail.com> (raw)
In-Reply-To: <a036d762-2f3c-3eca-4c9-1dd9f593c111@hippo.saclay.inria.fr>
On February 13, 2021 12:20:48 AM GMT+01:00, Marc Glisse <marc.glisse@inria.fr> wrote:
>On Fri, 12 Feb 2021, Andrew MacLeod via Gcc wrote:
>
>> I dont't want to immediately open a PR, so I'll just ask about
>> testsuite/gcc.dg/pr83609.c.
>>
>> the compilation string is
>> -O2 -fno-tree-forwprop -fno-tree-ccp -fno-tree-fre -fno-tree-pre
>> -fno-code-hoisting
>>
>> Which passes as is.
>>
>> if I however add -fno-tree-vrp as well, then it looks like dead
>store
>> maybe does something wong...
>>
>> with EVRP running, we translate function foo() from
>>
>>
>> complex float foo ()
>> {
>> complex float c;
>> complex float * c.0_1;
>> complex float _4;
>>
>> <bb 2> :
>> c.0_1 = &c;
>> MEM[(long long unsigned int *)c.0_1] = 1311768467463790320;
>> _4 = c;
>
>Isn't that a clear violation of strict aliasing?
Yes. We try DWIM if we see the must-alias though. Please see what the testcase was added for and eventually consider adding -fno-strict-aliasing.
prev parent reply other threads:[~2021-02-13 14:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-12 22:15 Andrew MacLeod
2021-02-12 23:20 ` Marc Glisse
2021-02-13 14:25 ` Richard Biener [this message]
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