From: Jakub Jelinek <jakub@redhat.com>
To: Jason Merrill <jason@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] c++: Drop TREE_READONLY on vars (possibly) initialized by tls wrapper [PR109164]
Date: Sat, 18 Mar 2023 13:54:58 +0100 [thread overview]
Message-ID: <ZBW0on5FLHxYP9kO@tucnak> (raw)
In-Reply-To: <d949596f-293c-60d7-18d3-7cf308926e58@redhat.com>
On Sat, Mar 18, 2023 at 08:39:45AM -0400, Jason Merrill wrote:
> On 3/17/23 13:51, Jakub Jelinek wrote:
> > The following two testcases are miscompiled, because we keep TREE_READONLY
> > on the vars even when they are (possibly) dynamically initialized by a TLS
> > wrapper function. Normally cp_finish_decl drops TREE_READONLY from vars
> > which need dynamic initialization, but for TLS we do this kind of
> > initialization upon every access to those variables.
>
> Why not handle this case in cp_finish_decl, too? That is, add
> DECL_THREAD_LOCAL_P to the TREE_STATIC check in
The patch is mostly about DECL_EXTERNAL cases, the others are supposedly
handled by the var_definition_p code there (or at least I assumed;
testcases certainly test only DECL_EXTERNAL).
I guess it could be done in cp_finish_decl, maybe better next to the
/* A reference will be modified here, as it is initialized. */
if (! DECL_EXTERNAL (decl)
&& TREE_READONLY (decl)
&& TYPE_REF_P (type))
{
was_readonly = 1;
TREE_READONLY (decl) = 0;
}
spot, but we'd need to export the decl2.cc helpers for it,
because not all DECL_THREAD_LOCAL_P vars need to be treated that way.
if (VAR_P (decl)
&& CP_DECL_THREAD_LOCAL_P (decl)
&& var_needs_tls_wrapper (decl)
&& (!DECL_EXTERNAL (decl) || flag_extern_tls_init))
TREE_READONLY (decl) = 0;
where var_needs_tls_wrapper would need to be exported from decl2.cc.
Though, var_needs_tls_wrapper -> var_defined_without_dynamic_init
needs
DECL_NONTRIVIALLY_INITIALIZED_P/DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P,
so perhaps that is accurate only closer to the end of cp_finish_decl?
Jakub
next prev parent reply other threads:[~2023-03-18 12:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-17 17:51 Jakub Jelinek
2023-03-18 12:39 ` Jason Merrill
2023-03-18 12:54 ` Jakub Jelinek [this message]
2023-03-18 15:09 ` [PATCH] c++, v2: " Jakub Jelinek
2023-03-20 15:45 ` Jakub Jelinek
2023-03-20 19:15 ` Jason Merrill
2023-03-20 19:26 ` Jakub Jelinek
2023-03-20 19:28 ` Jason Merrill
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