From: Richard Biener <richard.guenther@gmail.com>
To: Eric Botcazou <botcazou@adacore.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] Fix recent thinko in operand_equal_p
Date: Fri, 4 Nov 2022 10:40:35 +0100 [thread overview]
Message-ID: <2F00FAAA-AA2A-428D-AC5D-52CCF0FEE86B@gmail.com> (raw)
In-Reply-To: <7447720.EvYhyI6sBW@fomalhaut>
> Am 04.11.2022 um 10:29 schrieb Eric Botcazou via Gcc-patches <gcc-patches@gcc.gnu.org>:
>
> Hi,
>
> there is a thinko in the recent improvement by Jan:
>
> 2020-11-19 Jan Hubicka <jh@suse.cz>
>
> * fold-const.c (operand_compare::operand_equal_p): Fix thinko in
> COMPONENT_REF handling and guard types_same_for_odr by
> virtual_method_call_p.
> (operand_compare::hash_operand): Likewise.
>
> where the code just looks at operand 2 of COMPONENT_REF, if it is present, to
> compare addresses. That's wrong because operand 2 contains the number of
> DECL_OFFSET_ALIGN-bit-sized words so, when DECL_OFFSET_ALIGN > 8, not all the
> bytes are included and some of them are in DECL_FIELD_BIT_OFFSET instead, see
> get_inner_reference for the model computation.
>
> In other words, you would need to compare operand 2 and DECL_OFFSET_ALIGN and
> DECL_FIELD_BIT_OFFSET in this situation, but I'm not sure this is worth the
> hassle in practice so the attached fix just removes this alternate handling.
> Tested on x86-64/Linux, OK for mainline, 12 and 11 branches?
Ok.
Thanks,
Richard
>
> 2022-11-04 Eric Botcazou <ebotcazou@adacore.com>
>
> * fold-const.cc (operand_compare::operand_equal_p) <COMPONENT_REF>:
> Do not take into account operand 2.
> (operand_compare::hash_operand) <COMPONENT_REF>: Likewise.
>
>
> 2022-11-04 Eric Botcazou <ebotcazou@adacore.com>
>
> * gnat.dg/opt99.adb: New test.
> * gnat.dg/opt99_pkg1.ads, gnat.dg/opt99_pkg1.adb: New helper.
> * gnat.dg/opt99_pkg2.ads: Likewise.
>
> --
> Eric Botcazou
> <p.diff>
> <opt99.adb>
> <opt99_pkg1.adb>
> <opt99_pkg2.ads>
> <opt99_pkg1.ads>
prev parent reply other threads:[~2022-11-04 9:40 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-04 9:27 Eric Botcazou
2022-11-04 9:40 ` Richard Biener [this message]
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