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From: "aoliva at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/114803] simd conversion to [[gnu::vector_size(N)]]
 type hits invalid code in experimental/bits/simd_builtin.h
Date: Thu, 06 Jun 2024 07:50:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114803

--- Comment #16 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
That macro is used within libstdc++ to avoid relying on C99 functions when =
the
target C library is not C99-compliant.  It involves leaving out C++ standard
bits that would depend on functions that the C library doesn't offer, inclu=
ding
some of the <cmath> declarations in ::std::.

IMHO it would make sense to omit simd functions corresponding to C99/TR1 on=
es
known to be missing.  Now, it's unclear to me whether we'd be better off
omitting the entire set of C99/TR1 math functions as a block, or whether
there'd be any benefit from considering individual functions separately.=20
newlib, for example, exports a number of the C99/TR1 functions, but not all=
 of
them, so the macro is not defined.=