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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/112758] [13/14 Regression] Inconsistent Bitwise AND Operation Result between int and long long int
Date: Sat, 09 Dec 2023 09:11:51 +0000 [thread overview]
Message-ID: <bug-112758-4-yeD1XRAs7T@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-112758-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112758
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Eric Botcazou from comment #7)
> > I must say I have no idea what WORD_REGISTER_OPERATION says about the upper
> > bits of a paradoxical SUBREG if it is a MEM and load_extend_op (inner_mode)
> > is ZERO_EXTEND (zeros then?
>
> Yes.
>
> > Then this optimization is ok), or something else? And what it says on REGs.
>
> That it contains the result of the operation that was applied to the SUBREG
> as if it was applied to the entire REG, provided that
> word_register_operation_p is true. Otherwise, it's undefined.
But if we see a REG in there, we don't really know what operation it was.
Sure, if the operation is visible, we know it, but say PLUS can be extended
either way.
Which means punt on this optimization for WORD_REGISTER_OPERATIONS if the outer
mode is word_mode, except when sub is a MEM and load_extend_op (inner_mode) ==
ZERO_EXTEND?
next prev parent reply other threads:[~2023-12-09 9:11 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-29 6:05 [Bug c/112758] New: Inconsistent Bitwise AND Operation Result between int and long long int on Different Optimization Levels in GCC Trunk guminb at ajou dot ac.kr
2023-11-29 18:18 ` [Bug rtl-optimization/112758] [13/14 Regression] Inconsistent Bitwise AND Operation Result between int and long long int pinskia at gcc dot gnu.org
2023-12-08 2:57 ` guminb at ajou dot ac.kr
2023-12-08 17:01 ` jakub at gcc dot gnu.org
2023-12-08 17:37 ` segher at gcc dot gnu.org
2023-12-08 19:33 ` jakub at gcc dot gnu.org
2023-12-08 19:36 ` jakub at gcc dot gnu.org
2023-12-09 8:51 ` ebotcazou at gcc dot gnu.org
2023-12-09 9:11 ` jakub at gcc dot gnu.org [this message]
2023-12-09 11:00 ` ebotcazou at gcc dot gnu.org
2023-12-09 19:25 ` segher at gcc dot gnu.org
2023-12-09 22:06 ` ebotcazou at gcc dot gnu.org
2023-12-10 12:16 ` segher at gcc dot gnu.org
2023-12-13 22:06 ` pinskia at gcc dot gnu.org
2023-12-16 18:43 ` gkm at rivosinc dot com
2023-12-21 20:04 ` gkm at rivosinc dot com
2023-12-21 20:06 ` jakub at gcc dot gnu.org
2023-12-22 11:30 ` cvs-commit at gcc dot gnu.org
2024-03-02 0:37 ` cvs-commit at gcc dot gnu.org
2024-03-04 1:09 ` law at gcc dot gnu.org
2024-03-04 12:07 ` [Bug rtl-optimization/112758] [13 " jakub at gcc dot gnu.org
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