From: Jakub Jelinek <jakub@redhat.com>
To: Jan Hubicka <hubicka@ucw.cz>
Cc: Jason Merrill <jason@redhat.com>,
Richard Biener <rguenther@suse.de>,
Patrick Palka <ppalka@redhat.com>,
gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] c++: Retry the aliasing of base/complete cdtor optimization at import_export_decl time [PR113208]
Date: Wed, 17 Apr 2024 16:39:52 +0200 [thread overview]
Message-ID: <Zh/fODC8+JqgLOpT@tucnak> (raw)
In-Reply-To: <Zh_d337WnMdc0XwB@kam.mff.cuni.cz>
On Wed, Apr 17, 2024 at 04:34:07PM +0200, Jan Hubicka wrote:
> I think for most scenarios this is OK, but I am not sure about
> incremental linking (both LTO and non-LTO). What seems wrong is that we
> produce C5 comdat that is not exporting what it should and thus breaking
> the invariant that in valid code all comdats of same name are
> semantically equivalent.
Yeah, exactly. That is what I'm worried about too.
> Perhaps it makes no difference since this
> scenario is pretty special and we know that the functions are
> semantically equivalent and their addresses are never compared for
> equality (at least I failed to produce some useful testcase).
Yes, I think one can't take address of a constructor/destructor and compare
that for equality; I guess the destructor address can be stored in vtables,
but code manually reading stuff from vtables and assuming pointer equality
is almost certainly not valid.
Jakub
next prev parent reply other threads:[~2024-04-17 14:40 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-17 7:42 Jakub Jelinek
2024-04-17 9:04 ` Jan Hubicka
2024-04-17 12:32 ` Jakub Jelinek
2024-04-17 13:26 ` Jan Hubicka
2024-04-17 14:07 ` Jakub Jelinek
2024-04-17 14:34 ` Jan Hubicka
2024-04-17 14:39 ` Jakub Jelinek [this message]
2024-04-22 15:42 ` [PATCH] c++, v2: " Jakub Jelinek
2024-04-23 3:14 ` Jason Merrill
2024-04-23 16:04 ` Jakub Jelinek
2024-04-24 9:16 ` Jonathan Wakely
2024-04-24 16:16 ` [PATCH] c++, v3: " Jakub Jelinek
2024-04-24 22:39 ` Jason Merrill
2024-04-24 22:47 ` Jakub Jelinek
2024-04-25 0:43 ` Jason Merrill
2024-04-25 12:02 ` [PATCH] c++, v4: " Jakub Jelinek
2024-04-25 14:22 ` Jakub Jelinek
2024-04-25 15:30 ` Jason Merrill
2024-04-25 18:42 ` [PATCH] c++, v5: " Jakub Jelinek
2024-05-09 18:20 ` [PATCH] c++: Optimize in maybe_clone_body aliases even when not at_eof [PR113208] Jakub Jelinek
2024-05-09 18:58 ` Marek Polacek
2024-05-09 19:05 ` Jakub Jelinek
2024-05-10 19:59 ` Jason Merrill
2024-05-13 10:19 ` Jakub Jelinek
2024-05-14 22:20 ` Jason Merrill
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