From: Jeff Law <jeffreyalaw@gmail.com>
To: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] Avoid depending on destructor order
Date: Sun, 25 Sep 2022 09:29:44 -0600 [thread overview]
Message-ID: <81a56a51-6f1b-2150-a7bd-1d7d07095b24@gmail.com> (raw)
In-Reply-To: <AC98369A-33EE-4BB5-A25A-B828DA2D59BA@sandoe.co.uk>
On 9/25/22 00:29, Iain Sandoe wrote:
>
>> On 23 Sep 2022, at 15:30, David Edelsohn via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
>>
>> On Fri, Sep 23, 2022 at 10:12 AM Thomas Neumann <neumann@in.tum.de> wrote:
>>
>>>> +static const bool in_shutdown = false;
>>>>
>>>> I'll let Jason or others decide if this is the right solution. It seems
>>>> that in_shutdown also could be declared outside the #ifdef and
>>>> initialized as "false".
>>> sure, either is fine. Moving it outside the #ifdef wastes one byte in
>>> the executable (while the compiler can eliminate the const), but it does
>>> not really matter.
>>>
>>> I have verified that the patch below fixes builds for both fast-path and
>>> non-fast-path builds. But if you prefer I will move the in_shutdown
>>> definition instead.
>>>
>>> Best
>>>
>>> Thomas
>>>
>>> PS: in_shutdown is an int here instead of a bool because non-fast-path
>>> builds do not include stdbool. Not a good reason, of course, but I
>>> wanted to keep the patch minimal and it makes no difference in practice.
>>>
>>>
>>> When using the atomic fast path deregistering can fail during
>>> program shutdown if the lookup structures are already destroyed.
>>> The assert in __deregister_frame_info_bases takes that into
>>> account. In the non-fast-path case however is not aware of
>>> program shutdown, which caused a compiler error on such platforms.
>>> We fix that by introducing a constant for in_shutdown in
>>> non-fast-path builds.
>>>
>>> libgcc/ChangeLog:
>>> * unwind-dw2-fde.c: Introduce a constant for in_shutdown
>>> for the non-fast-path case.
>>>
>>> diff --git a/libgcc/unwind-dw2-fde.c b/libgcc/unwind-dw2-fde.c
>>> index d237179f4ea..0bcd5061d76 100644
>>> --- a/libgcc/unwind-dw2-fde.c
>>> +++ b/libgcc/unwind-dw2-fde.c
>>> @@ -67,6 +67,8 @@ static void
>>> init_object (struct object *ob);
>>>
>>> #else
>>> +/* Without fast path frame deregistration must always succeed. */
>>> +static const int in_shutdown = 0;
>>>
>>> /* The unseen_objects list contains objects that have been registered
>>> but not yet categorized in any way. The seen_objects list has had
>>>
>> Thanks for the patch. I'll let you and Jason decide which style solution
>> is preferred.
> This also breaks bootstrap on Darwin at least, so an early solution would be
> welcome (the fix here allows bootstrap to continue, testing on-going).
> thanks,
I'm using it in the automated tester as well -- without all the *-elf
targets would fail to build libgcc.
jeff
next prev parent reply other threads:[~2022-09-25 15:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-23 13:25 David Edelsohn
2022-09-23 13:38 ` Thomas Neumann
2022-09-23 14:01 ` David Edelsohn
2022-09-23 14:12 ` Thomas Neumann
2022-09-23 14:30 ` David Edelsohn
2022-09-25 6:29 ` Iain Sandoe
2022-09-25 15:29 ` Jeff Law [this message]
2022-09-26 7:55 ` Rainer Orth
2022-09-27 0:17 ` Jason Merrill
2022-09-23 14:11 ` David Edelsohn
-- strict thread matches above, loose matches on Subject: below --
2022-09-19 16:20 Thomas Neumann
2022-09-22 22:22 ` Jason Merrill
2022-09-26 11:46 ` Claudiu Zissulescu Ianculescu
2022-09-26 11:49 ` Thomas Neumann
2022-09-26 11:50 ` Claudiu Zissulescu Ianculescu
2022-09-26 12:53 ` Iain Sandoe
2022-09-26 13:14 ` Thomas Neumann
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