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* [Bug threads/27886] New: static thread_local on aarch64 are broken in gdb
@ 2021-05-18 14:36 avi@cloudius-systems.com
2021-09-19 2:41 ` [Bug threads/27886] " pinskia at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: avi@cloudius-systems.com @ 2021-05-18 14:36 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=27886
Bug ID: 27886
Summary: static thread_local on aarch64 are broken in gdb
Product: gdb
Version: 10.1
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: threads
Assignee: unassigned at sourceware dot org
Reporter: avi@cloudius-systems.com
Target Milestone: ---
Consider this small C++ program:
=== begin ===
struct kk {
kk() = default;
int x = 1, y = 2, z = 3;
~kk() {}
};
namespace a {
static thread_local kk v1;
thread_local kk v2;
void f(int x) {
v1.x = v2.y = x;
}
int g() {
return v1.x + v2.y;
}
}
int main() {
return 0;
}
=== end ===
Compiling and linking it with -pthread -O3 -g, gcc and clang, I can examine
both a::v1 and a::v2 on x86_64 with these commands:
(gdb) start
(gdb) p a::v1
(gdb) p a::v2
However, on aarch64, I get
(gdb) p a::v1
$1 = <optimized out>
(gdb) p a::v2
$2 = {x = 1, y = 2, z = 3}
a::v1 is not optimized out, and the problem remains when I add a function that
returns a reference to a::v1 (thus forcing the compiler to retain the structure
in memory).
In a more complicated project, I get a different error for static thread-locals
- the type is lost though the address is still visible to gdb.
Since both g++ and clang++ yield the same result, I assume the problem is with
gdb.
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* [Bug threads/27886] static thread_local on aarch64 are broken in gdb
2021-05-18 14:36 [Bug threads/27886] New: static thread_local on aarch64 are broken in gdb avi@cloudius-systems.com
@ 2021-09-19 2:41 ` pinskia at gcc dot gnu.org
2024-02-29 5:38 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-09-19 2:41 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=27886
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=97344,
| |https://sourceware.org/bugz
| |illa/show_bug.cgi?id=28351
CC| |pinskia at gcc dot gnu.org
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I suspect this due to GCC bug 97344 (which in turn needs binutils support PR
28351).
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* [Bug threads/27886] static thread_local on aarch64 are broken in gdb
2021-05-18 14:36 [Bug threads/27886] New: static thread_local on aarch64 are broken in gdb avi@cloudius-systems.com
2021-09-19 2:41 ` [Bug threads/27886] " pinskia at gcc dot gnu.org
@ 2024-02-29 5:38 ` pinskia at gcc dot gnu.org
2024-02-29 18:03 ` tromey at sourceware dot org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-02-29 5:38 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=27886
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2024-02-29
Status|UNCONFIRMED |NEW
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
.
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* [Bug threads/27886] static thread_local on aarch64 are broken in gdb
2021-05-18 14:36 [Bug threads/27886] New: static thread_local on aarch64 are broken in gdb avi@cloudius-systems.com
2021-09-19 2:41 ` [Bug threads/27886] " pinskia at gcc dot gnu.org
2024-02-29 5:38 ` pinskia at gcc dot gnu.org
@ 2024-02-29 18:03 ` tromey at sourceware dot org
2024-02-29 19:07 ` pinskia at gcc dot gnu.org
2024-02-29 19:14 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: tromey at sourceware dot org @ 2024-02-29 18:03 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=27886
Tom Tromey <tromey at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |tromey at sourceware dot org
--- Comment #3 from Tom Tromey <tromey at sourceware dot org> ---
It would be interesting to see the DWARF DIE for 'v1'.
Normally these end up with DW_OP_form_tls_address -- which
on Linux ends up just calling into libthread_db.
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* [Bug threads/27886] static thread_local on aarch64 are broken in gdb
2021-05-18 14:36 [Bug threads/27886] New: static thread_local on aarch64 are broken in gdb avi@cloudius-systems.com
` (2 preceding siblings ...)
2024-02-29 18:03 ` tromey at sourceware dot org
@ 2024-02-29 19:07 ` pinskia at gcc dot gnu.org
2024-02-29 19:14 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-02-29 19:07 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=27886
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #3)
> It would be interesting to see the DWARF DIE for 'v1'.
> Normally these end up with DW_OP_form_tls_address -- which
> on Linux ends up just calling into libthread_db.
Right and DW_OP_form_tls_address requires dtprel relocation support which is
not currently there for aarch64, see bug 28351 for the binutils support and
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97344 for the GCC side support.
it looks like clang/LLVM will need similar support added too.
The ABI does define a dtprel relocation even.
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* [Bug threads/27886] static thread_local on aarch64 are broken in gdb
2021-05-18 14:36 [Bug threads/27886] New: static thread_local on aarch64 are broken in gdb avi@cloudius-systems.com
` (3 preceding siblings ...)
2024-02-29 19:07 ` pinskia at gcc dot gnu.org
@ 2024-02-29 19:14 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-02-29 19:14 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=27886
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://github.com/llvm/llv
| |m-project/issues/83466
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end of thread, other threads:[~2024-02-29 19:14 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2021-05-18 14:36 [Bug threads/27886] New: static thread_local on aarch64 are broken in gdb avi@cloudius-systems.com
2021-09-19 2:41 ` [Bug threads/27886] " pinskia at gcc dot gnu.org
2024-02-29 5:38 ` pinskia at gcc dot gnu.org
2024-02-29 18:03 ` tromey at sourceware dot org
2024-02-29 19:07 ` pinskia at gcc dot gnu.org
2024-02-29 19:14 ` pinskia at gcc dot gnu.org
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