[Bug target/80881] [7/8 Regression] null pointer access in libgomp.h

["lh_mouse at 126 dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80881

--- Comment #8 from Liu Hao <lh_mouse at 126 dot com> ---
I cannot reproduce this problem on either i686-w64-mingw32 or
x86_64-w64-mingw32 with --enable-tls.


On line 677 in libgomp.h there is a call to `gomp_thread()` which is supposed
to return a pointer to a __thread object. However, from your first post, it is
weird that for i686 GCC generates code referring the GS segment register, since
GS is unused by x86 Windows.

On x86 Windows, TLS is indirected from the FS register. It is Microsoft's
rocket science, hence GCC still relies on the emutls solution. The GS register
is known to be utilized by x64 Windows and Linux AFAICT.

I presume that your GCC generated Linux code for Windows targets. If you are
cross-compiling for example it may becaused by GCC scripts mistaking the host
for the build. This still requires investigation.

Reference: <https://en.wikipedia.org/wiki/Win32_Thread_Information_Block>