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From: "thiago at kde dot org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/69549] Named Address Spaces does not compile in C++
Date: Mon, 22 Mar 2021 17:43:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D69549

--- Comment #5 from Thiago Macieira <thiago at kde dot org> ---
BTW, Clang solved this by making __seg_fs, __seg_gs macros that resolve to
__attribute__:

$ clang -dM -E -xc /dev/null | grep __seg_.s
#define __seg_fs __attribute__((address_space(257)))
#define __seg_gs __attribute__((address_space(256)))

That way, they don't need to be deduced as qualifiers in C, like const,
volatile and _Atomic.

So this compiles with Clang in C++:

void *tid() { auto tib =3D (void * __seg_fs*)(0); return *tid; }

_Z3tibv:                                # @_Z3tibv
        movq    %fs:0, %rax
        retq=