From: Jeff Law <jeffreyalaw@gmail.com>
To: Martin Sebor <msebor@gmail.com>, gcc-patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH v2] fix PR 103143
Date: Mon, 6 Dec 2021 13:14:35 -0700 [thread overview]
Message-ID: <ca3f20c0-edb0-4e8c-78b4-9b5009bebe89@gmail.com> (raw)
In-Reply-To: <b592eea8-9699-e706-196b-36f40d5d53b5@gmail.com>
On 12/6/2021 10:31 AM, Martin Sebor wrote:
> I have broken up the patch into a series of six. Attached is
> part (1), the fix for the typo that causes PR 103143.
>
> On 12/3/21 5:00 PM, Jeff Law wrote:
>>
>>
>> On 11/8/2021 7:34 PM, Martin Sebor via Gcc-patches wrote:
>>> The pointer-query code that implements compute_objsize() that's
>>> in turn used by most middle end access warnings now has a few
>>> warts in it and (at least) one bug. With the exception of
>>> the bug the warts aren't behind any user-visible bugs that
>>> I know of but they do cause problems in new code I've been
>>> implementing on top of it. Besides fixing the one bug (just
>>> a typo) the attached patch cleans up these latent issues:
>>>
>>> 1) It moves the bndrng member from the access_ref class to
>>> access_data. As a FIXME in the code notes, the member never
>>> did belong in the former and only takes up space in the cache.
>>>
>>> 2) The compute_objsize_r() function is big, unwieldy, and tedious
>>> to step through because of all the if statements that are better
>>> coded as one switch statement. This change factors out more
>>> of its code into smaller handler functions as has been suggested
>>> and done a few times before.
>>>
>>> 3) (2) exposed a few places where I fail to pass the current
>>> GIMPLE statement down to ranger. This leads to worse quality
>>> range info, including possible false positives and negatives.
>>> I just spotted these problems in code review but I haven't
>>> taken the time to come up with test cases. This change fixes
>>> these oversights as well.
>>>
>>> 4) The handling of PHI statements is also in one big, hard-to-
>>> follow function. This change moves the handling of each PHI
>>> argument into its own handler which merges it into the previous
>>> argument. This makes the code easier to work with and opens it
>>> to reuse also for MIN_EXPR and MAX_EXPR. (This is primarily
>>> used to print informational notes after warnings.)
>>>
>>> 5) Finally, the patch factors code to dump each access_ref
>>> cached by the pointer_query cache out of pointer_query::dump
>>> and into access_ref::dump. This helps with debugging.
>>>
>>> These changes should have no user-visible effect and other than
>>> a regression test for the typo (PR 103143) come with no tests.
>>> They've been tested on x86_64-linux.
>> Sigh. You've identified 6 distinct changes above. The 5 you've
>> enumerated plus a typo fix somewhere. There's no reason why they
>> need to be a single patch and many reasons why they should be a
>> series of independent patches. Combining them into a single patch
>> isn't how we do things and it hides the actual bugfix in here.
>>
>> Please send a fix for the typo first since that should be able to
>> trivially go forward. Then a patch for item #1. That should be
>> trivial to review when it's pulled out from teh rest of the patch.
>> Beyond that, your choice on ordering, but you need to break this down.
>>
>>
>>
>>
>> Jeff
>>
>
>
> gcc-103413.diff
>
> commit 9a5bb7a2b0cdb8654061d9cba543c1408fa7adc9
> Author: Martin Sebor<msebor@redhat.com>
> Date: Sat Dec 4 16:22:07 2021 -0700
>
> Use the recursive form of compute_objsize [PR 103143].
>
> gcc/ChangeLog:
>
> PR middle-end/103143
> * pointer-query.cc (gimple_call_return_array): Call compute_objsize_r.
>
> gcc/testsuite/ChangeLog:
> PR middle-end/103143
> * gcc.dg/Wstringop-overflow-83.c: New test.
Thanks. Presumably by going through the public API, qry->depth got
reset to 0 and/or we'd get a re-initialized snlim at each call, leading
to the infinite recursion?
OK for the trunk. Thanks for breaking this out.
jeff
next prev parent reply other threads:[~2021-12-06 20:14 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-09 2:34 [PATCH] fix up compute_objsize (including PR 103143) Martin Sebor
2021-11-15 16:49 ` PING " Martin Sebor
2021-11-22 16:41 ` PING 2 " Martin Sebor
2021-11-29 15:49 ` PING 3 " Martin Sebor
2021-12-04 0:00 ` Jeff Law
2021-12-06 17:31 ` [PATCH v2] fix PR 103143 Martin Sebor
2021-12-06 20:14 ` Jeff Law [this message]
2021-12-06 21:44 ` Martin Sebor
2021-12-06 17:31 ` [PATCH v2 1/5] fix up compute_objsize: move bndrng into access_data Martin Sebor
2021-12-08 18:47 ` Jeff Law
2021-12-06 17:31 ` [PATCH v2 2/5] fix up compute_objsize: pass GIMPLE statement to it Martin Sebor
2021-12-08 18:48 ` Jeff Law
2021-12-06 17:32 ` [PATCH v2 3/5] fix up compute_objsize: factor out PHI handling Martin Sebor
2021-12-08 20:08 ` Jeff Law
2021-12-09 16:57 ` Martin Sebor
2021-12-06 17:32 ` [PATCH v2 4/5] fix up compute_objsize: refactor it into helpers Martin Sebor
2021-12-08 19:12 ` Jeff Law
2021-12-06 17:32 ` [PATCH v2 5/5] fix up compute_objsize: add a dump function Martin Sebor
2021-12-08 19:15 ` Jeff Law
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