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From: "yangyujie at loongson dot cn" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/113233] LoongArch: target options from LTO objects not
 respected during linking
Date: Fri, 05 Jan 2024 01:31:16 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113233

--- Comment #6 from Yang Yujie <yangyujie at loongson dot cn> ---
(In reply to Xi Ruoyao from comment #4)
> (In reply to Jan Hubicka from comment #3)
> > > Confirm.  But option save/restore has been always implemented:
> > >=20
> > >     .section    .gnu.lto_.opts,"",@progbits
> > >     .ascii  "'-fno-openmp' '-fno-openacc' '-fno-pie' '-fcf-protection"
> > >     .ascii  "=3Dnone' '-mabi=3Dlp64d' '-march=3Dloongarch64' '-mfpu=
=3D64' '-m"
> > >     .ascii  "simd=3Dlasx' '-mcmodel=3Dnormal' '-mtune=3Dloongarch64' =
'-flto"
> > >     .ascii  "'\000"
> > >=20
> > > So -msimd=3Dlasx is correctly recorded.  Not sure why it does not wor=
k.
> >=20
> > With LTO we need to mix code compiled with different sets of options.
> > For this reason we imply for every function defition and optimization
> > and target attribute which record the flags.  So it seems target
> > attribute is likely broken for this flag.
>=20
> Target attribute is not implemented for LoongArch.  And I don't think it'=
s a
> good idea to implement it in stage 3.

Yes, target attribute may have to wait.  But save/restore can be implemented
without target attributes of functions.  By marking options as "Save" in .o=
pt
or implementing custom TARGET_OPTION_{SAVE,RESTORE} hooks, we can stream the
target configuration (which may come from the command line / the target
attributes / #pragma GCC target) into the per-function LTO bytecode, so that
lto1 can pick up and use them later when generating code for each function.=