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From: "qinzhao at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/102276] -ftrivial-auto-var-init fails to initialize
 a variable, causes a spurious warning
Date: Mon, 14 Feb 2022 17:02:07 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102276

--- Comment #8 from qinzhao at gcc dot gnu.org ---
(In reply to Jakub Jelinek from comment #7)
> If we just want to avoid the warning in cases like that (there is nothing
> wrong in the testcases themselves, the warning just warns about an
> implementation detail that a normally uninitialized variable will be real=
ly
> uninitialized even despite the -ftrivial-auto-var-init=3D option), then
> maybe_warn_switch_unreachable
> already has:
>       if (gimple_code (stmt) =3D=3D GIMPLE_GOTO
>           && TREE_CODE (gimple_goto_dest (stmt)) =3D=3D LABEL_DECL
>           && DECL_ARTIFICIAL (gimple_goto_dest (stmt)))
>         /* Don't warn for compiler-generated gotos.  These occur
>            in Duff's devices, for example.  */;
> and so for flag_auto_var_init > AUTO_INIT_UNINITIALIZED perhaps we could =
also
> avoid warnings on:
> 1) call to .DEFERRED_INIT
> 2) call to __builtin_clear_padding if the second argument is present and
> non-zero
> 3) I guess we would need not to warn on a gimple assign store right after
> the .DEFERRED_INIT call that has the lhs of .DEFERRED_INIT as rhs
> anything else?
Yes, I think the above 3 should include all the cases.=