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From: "segher at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug debug/99830] [11 Regression] ICE: in lra_eliminate_regs_1, at lra-eliminations.c:659 with -O2 -fno-expensive-optimizations -fno-split-wide-types -g
Date: Fri, 09 Apr 2021 17:09:54 +0000 [thread overview]
Message-ID: <bug-99830-4-a6e6Gttw5k@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-99830-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99830
--- Comment #10 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #8)
> In particular, it is combine_simplify_rtx that is called on:
> (zero_extend:SI (subreg:QI (ior:TI (and:TI (reg/v:TI 103 [ f ])
> (const_int -16711681 [0xffffffffff00ffff]))
> (ashift:TI (and:TI (clobber:TI (const_int 0 [0]))
> (const_int 255 [0xff]))
> (const_int 16 [0x10]))) 0))
> which simplifies it into
> (and:SI (subreg:SI (reg/v:TI 103 [ f ]) 0)
> (const_int 255 [0xff]))
That is very wrong. A clobber of 0 should *never* be removed. Various
parts of generic code know about that already, btw.
A clobber of 0 means "Abort! Abort!" It does not mean "well, here is
something you can optimise away more easily".
Do you want to investigate further, or shall I?
next prev parent reply other threads:[~2021-04-09 17:09 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 14:11 [Bug rtl-optimization/99830] New: " zsojka at seznam dot cz
2021-03-30 16:14 ` [Bug rtl-optimization/99830] " acoplan at gcc dot gnu.org
2021-03-31 7:53 ` rguenth at gcc dot gnu.org
2021-04-08 13:21 ` rguenth at gcc dot gnu.org
2021-04-08 13:27 ` jakub at gcc dot gnu.org
2021-04-08 14:45 ` [Bug debug/99830] " jakub at gcc dot gnu.org
2021-04-09 12:29 ` segher at gcc dot gnu.org
2021-04-09 12:36 ` jakub at gcc dot gnu.org
2021-04-09 12:38 ` segher at gcc dot gnu.org
2021-04-09 13:27 ` jakub at gcc dot gnu.org
2021-04-09 14:23 ` jakub at gcc dot gnu.org
2021-04-09 17:09 ` segher at gcc dot gnu.org [this message]
2021-04-09 17:31 ` jakub at gcc dot gnu.org
2021-04-09 18:01 ` segher at gcc dot gnu.org
2021-04-09 19:10 ` jakub at gcc dot gnu.org
2021-04-09 19:10 ` jakub at gcc dot gnu.org
2021-04-09 21:29 ` segher at gcc dot gnu.org
2021-04-12 16:20 ` jakub at gcc dot gnu.org
2021-04-12 23:01 ` cvs-commit at gcc dot gnu.org
2021-04-12 23:03 ` jakub at gcc dot gnu.org
2021-04-20 9:46 ` cvs-commit at gcc dot gnu.org
2021-04-20 23:34 ` cvs-commit at gcc dot gnu.org
2021-04-22 16:52 ` cvs-commit at gcc dot gnu.org
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