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From: "gabravier at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/98438] Rather bad optimization of midpoint
 implementation for __int128 (and other types)
Date: Fri, 01 Jan 2021 00:53:25 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98438

--- Comment #5 from Gabriel Ravier <gabravier at gmail dot com> ---
If you're wondering, the `using x =3D y;` syntax is roughly equivalent to
`typedef y x;`, and the code just expects _Up to be the unsigned counterpar=
t of
_Tp, but here are the details as demanded by https://gcc.gnu.org/bugs/#need
(sorry if the preprocessed file is a bit large, I usually use a template for
examining GCC bugs):

Exact version of GCC: gcc version 11.0.0 20201230 (experimental)
(Compiler-Explorer-Build)
System type: Assuming that's the target, x86_64-linux-gnu
Options given when GCC was configured/built: ../gcc-trunk-20201231/configure
--prefix=3D/opt/compiler-explorer/gcc-build/staging --build=3Dx86_64-linux-=
gnu
--host=3Dx86_64-linux-gnu --target=3Dx86_64-linux-gnu --disable-bootstrap
--enable-multiarch --with-abi=3Dm64 --with-multilib-list=3Dm32,m64,mx32
--enable-multilib --enable-clocale=3Dgnu --enable-languages=3Dc,c++,fortran=
,ada,d
--enable-ld=3Dyes --enable-gold=3Dyes --enable-libstdcxx-debug
--enable-libstdcxx-time=3Dyes --enable-linker-build-id --enable-lto
--enable-plugins --enable-threads=3Dposix
--with-pkgversion=3DCompiler-Explorer-Build
Complete command line that triggers the bug: g++ -g -o
/tmp/compiler-explorer-compiler202101-4546-1y1nk07.gl18/output.s -masm=3Din=
tel -S
-fdiagnostics-color=3Dalways -O3 -std=3Dgnu++2a -DNDEBUG -g0
/tmp/compiler-explorer-compiler202101-4546-1y1nk07.gl18/example.cpp
Compiler output (error messages, warnings, etc.): (nothing)
Preprocessed file (*.i*) that triggers the bug: Would have been sent as an
attachment to this message but was accidentally previously sent as an
attachment to a blank message, so you can find it there.=