Re: [PATCH v2 1/5] fix up compute_objsize: move bndrng into access_data

[Jeff Law <jeffreyalaw@gmail.com>]

On 12/6/2021 10:31 AM, Martin Sebor wrote:
> Attached is the subset of the patch in part (1) below:  Move
> bndrng from access_ref to access_data.
>
> 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-pointer_query-refactor-1.diff
>
> commit 1062c1154beeeae26e86f053946ea733ffb5d136
> Author: Martin Sebor <msebor@redhat.com>
> Date:   Sat Dec 4 16:46:17 2021 -0700
>
>      Move bndrng from access_ref to access_data.
>      
>      gcc/ChangeLog:
>      
>              * gimple-ssa-warn-access.cc (check_access): Adjust to member name
>              change.
>              (pass_waccess::check_strncmp): Same.
>              * pointer-query.cc (access_ref::access_ref): Remove arguments.
>              Simpilfy.
>              (access_data::access_data): Define new ctors.
>              (access_data::set_bound): Define new member function.
>              (compute_objsize_r): Remove unnecessary code.
>              * pointer-query.h (struct access_ref): Remove ctor arguments.
>              (struct access_data): Declare ctor overloads.
>              (access_data::dst_bndrng): New member.
>              (access_data::src_bndrng): New member.
OK.  Thanks for breaking this out.

jeff