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bug#41357: 28.0.50; GC may miss to mark calle safe register content
From: |
Andrea Corallo |
Subject: |
bug#41357: 28.0.50; GC may miss to mark calle safe register content |
Date: |
Sun, 17 May 2020 17:45:28 +0000 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) |
Eli Zaretskii <eliz@gnu.org> writes:
>> From: Andrea Corallo <akrl@sdf.org>
>> Cc: bug-gnu-emacs@gnu.org, eggert@cs.ucla.edu
>> Date: Sun, 17 May 2020 17:13:26 +0000
>>
>> If a C function caller of 'flush_stack_call_func' allocates a
>> Lisp_Object in a temp variable and the compiler decide to keep this in a
>> callee saved reg while 'flush_stack_call_func' is called this will be
>> garbage collected unexpectedly.
>
> Can you show me an example of this (as skeleton C code)?
>
> Thanks.
Sure, something like
=====
Lisp_Object
foo (void)
{
/* 'res' goes in a callee saved reg */
Lisp_Object res = build_string ("bar");
[...]
/* LTO inline the following as "flush_stack_call_func (mark_threads_callback,
NULL);" */
mark_threads ();
[...]
gc_sweep ();
/* The string pointed by 'res' was garbage collected. */
return res;
}
=====
I'm not sure this is the only possible scenarion tho.
Andrea
--
akrl@sdf.org
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, (continued)
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Andrea Corallo, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Paul Eggert, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Eli Zaretskii, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Andrea Corallo, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Eli Zaretskii, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Paul Eggert, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Andrea Corallo, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Eli Zaretskii, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Andrea Corallo, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Eli Zaretskii, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content,
Andrea Corallo <=
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Eli Zaretskii, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Andrea Corallo, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Paul Eggert, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Eli Zaretskii, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Paul Eggert, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Eli Zaretskii, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Andrea Corallo, 2020/05/17
- bug#41357: 28.0.50; GC may miss to mark calle safe register content, Paul Eggert, 2020/05/17
bug#41357: 28.0.50; GC may miss to mark calle safe register content, Tom Tromey, 2020/05/24