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Re: [PATCH, i386] PR63211 broken type-punning in avx* tests.
- From: Uros Bizjak <ubizjak at gmail dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Kirill Yukhin <kirill dot yukhin at gmail dot com>, Ilya Tocar <tocarip dot intel at gmail dot com>, Mike Stump <mikestump at comcast dot net>, Rainer Orth <ro at cebitec dot uni-bielefeld dot de>
- Date: Sat, 4 Apr 2015 10:08:27 +0200
- Subject: Re: [PATCH, i386] PR63211 broken type-punning in avx* tests.
- Authentication-results: sourceware.org; auth=none
- References: <20150403110229 dot GB23405 at msticlxl7 dot ims dot intel dot com> <CAFULd4Zeq2UKXqCPO4r6mNci5CFzWarN=YaXWULUFf2PPZew9g at mail dot gmail dot com> <20150403145207 dot GC23405 at msticlxl7 dot ims dot intel dot com>
On Fri, Apr 3, 2015 at 4:52 PM, Ilya Tocar <firstname.lastname@example.org> wrote:
> On 03 Apr 13:39, Uros Bizjak wrote:
>> On Fri, Apr 3, 2015 at 1:02 PM, Ilya Tocar <email@example.com> wrote:
>> > I've looked into avx* tests and many of them (even those that don't fail
>> > in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63211) use invalid type
>> > punning. Properly fixing them looks like a lot of work, so I propose
>> > just adding -fno-strict-aliasing to them.
>> > This patch was obtained by running
>> > sed -i "s/-O2/-O2 -fno-strict-aliasing/g" ../gcc/testsuite/gcc.target/i386/avx*-2.c
>> > Ok for stage1?
>> I don't like this approach. If the testcase is broken, then it should
>> be fixed, not worked around.
> IMHO those tests don't need to be alias conformant.
> There are plenty of tests for aliasing rules,
> and avx tests verify intrinsics implementaion. There are plenty of real
> programs braking alias rules, so why can't we have non-conformant tests?
I don't agree with the above. Tests have to be conformant, no matter
what they test. Recent c11 cleanup is an example, where all
non-conformant tests were fixed to be c11 conformant (in contrast to
only slapping -std=c89 into their flags).
The deviation from the above rule has to be approved from the
testsuite maintainers. It represents possible maintenance issue in the