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From: "alvinhochun at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/104862] extern thread_local (emutls) code crashes with
 ASLR on Windows
Date: Thu, 12 May 2022 14:12:46 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104862

Alvin Wong <alvinhochun at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ebotcazou at gcc dot gnu.o=
rg

--- Comment #1 from Alvin Wong <alvinhochun at gmail dot com> ---
I found from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D64697#c25 that =
there
was a change that seems related to the issue observed in this report. Can
anyone check?

> The master branch has been updated by Eric Botcazou <ebotcazou@gcc.gnu.or=
g>:
>=20
> https://gcc.gnu.org/g:021ad8e5cf9ab66e1a0a41dce3a54586facb86e0
>=20
> commit r12-4036-g021ad8e5cf9ab66e1a0a41dce3a54586facb86e0
> Author: Eric Botcazou <ebotcazou@adacore.com>
> Date:   Fri Oct 1 10:49:34 2021 +0200
>=20
>     Fix PR c++/64697 at -O1 or above
>=20=20=20=20=20
>     The BFD fix eliminates the link failure and working code is generated=
 at
>     -O0, but _not_ when optimization is enabled because the optimizer
> changes:
>=20=20=20=20=20
>             movq    .refptr._ZTH1s(%rip), %rax
>             testq   %rax, %rax
>             je      .L2
>             call    _ZTH1s
>=20=20=20=20=20
>     into:
>=20=20=20=20=20
>             leaq    _ZTH1s(%rip), %rax
>             testq   %rax, %rax
>             je      .L2
>             call    _ZTH1s
>=20=20=20=20=20
>     and the leaq now also gets the relocation overflow.  So the fix is to
>     teach legitimate_pic_address_disp_p to reject the transformation when
>     the symbol is an external weak function, which yields:
>=20=20=20=20=20
>             cmpq    $0, .refptr._ZTH1s(%rip)
>             je      .L2
>             call    _ZTH1s
>=20=20=20=20=20
>     and the cmpq keeps a relocation that does not overflow.
>=20=20=20=20=20
>     gcc/
>             PR c++/64697
>             * config/i386/i386.c (legitimate_pic_address_disp_p): For
> PE-COFF do
>             not return true for external weak function symbols in medium
> model.=