[PATCH 1/6] dlls/msvcrt*: ensure variable sse2_cw is set for all code paths in _control87 (GCC11)

[Eric Pouech]

Le 30/09/2021 à 19:39, Zebediah Figura a écrit :
> On 9/30/21 12:14 PM, Eric Pouech wrote:
>>
>>>>
>>>> which still gives me the warnings, when compiling the 32bit part of a
>>>> wow64 conf
>>>>
>>>> (but not on a pure 32bit conf)
>>>>
>>>> your solution doesn't generate warnings on neither of the two
>>>>
>>>> so will need further investigation on:
>>>>
>>>> - discrepency wrt wow
>>>>
>>>> - why the difference between the two patches
>>>
>>> I don't get warnings with that diff either. What version of GCC do you
>>> have?
>>
>> well, o well....
>>
>> retesting today, and couldn't get any warnings with the patch I posted
>> yesterday...<grrr>
>>
>>
>> moreover, in this patch, if I change the if (_control... by if
>> (!control... (inverting the test), I get no warnings either which makes
>> absolutely no sense
>>
>>
>> I'm starting to wonder if the  -Wmaybe-uninitialized warning could be a
>> little fragile at this point
>>
>>
>> there are a couple of bugs reports on gcc bugzilla reguarding this 
>> warning
>>
>> potentially bugs report like may link to the same type of issues
>>
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102381
>>
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101768
>>
>>
>> I may wait a bit to let things settle down before taking any action on
>> this fix in msvcrt
>
> I mean, -Wmaybe-uninitialized has always been at least somewhat 
> heuristic, throughout the entire history of gcc, and there have been 
> false positives and false negatives. But I've found that it tends to 
> behave nicely for idiomatically structured code. I've found very few 
> cases where "just initialize the variable to zero" seems like the best 
> solution to me.

I'm not suggesting at this point to disable -Wmaybe-unitialized

I'm just facing instability in tests results here:

- either because of me

- hw instability (i've seen some abnormal crashes)

- heisenbug in gcc

(listed in decreasing probability)

A+
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