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From: "uwe at netbsd dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/101469] wrong code with "-O2 -fPIE" for SH
Date: Sun, 18 Jul 2021 17:04:57 +0000 [thread overview]
Message-ID: <bug-101469-4-HHfZFCPMYM@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-101469-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101469
--- Comment #2 from Valeriy E. Ushakov <uwe at netbsd dot org> ---
I don't have the latest gcc handy, but I see this bug already in an old netbsd
tree from about an year ago with gcc 8.4.0
As hgutch@n.o pointed out, this seems to be a problem with this peephole2:
;; mov r12,r0
;; add #-48,r0 -> add #-48,r12
;; mov.l r0,@(4,r10) mov.l r12,@(4,r10)
;; (r12 dead)
(define_peephole2
[(set (match_operand:SI 0 "arith_reg_dest")
(match_operand:SI 1 "arith_reg_dest"))
(set (match_dup 0) (plus:SI (match_dup 0)
(match_operand:SI 2 "const_int_operand")))
(set (match_operand:SI 3 "general_movdst_operand") (match_dup 0))]
as far as I can tell, it optimizes
r0 = r2
r0 += 64
*(r0+4) = r0
to
r2 += 64
*(r0+4) = r2
failing to notice that the the destination uses r0 too.
Then in the cprop-registers step that r0 is replaced with r12 b/c of r0 = r12
done a bit earlier.
next prev parent reply other threads:[~2021-07-18 17:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-16 9:48 [Bug c/101469] New: " rin at NetBSD dot org
2021-07-18 4:18 ` [Bug target/101469] " rin at NetBSD dot org
2021-07-18 17:04 ` uwe at netbsd dot org [this message]
2021-07-19 5:23 ` rin at NetBSD dot org
2021-07-19 5:55 ` olegendo at gcc dot gnu.org
2021-07-19 6:13 ` rin at NetBSD dot org
2021-07-21 16:40 ` rin at NetBSD dot org
2023-07-07 10:25 ` olegendo at gcc dot gnu.org
2023-07-07 10:28 ` olegendo at gcc dot gnu.org
2023-07-10 2:39 ` rin at NetBSD dot org
2023-07-10 2:45 ` olegendo at gcc dot gnu.org
2023-07-10 3:36 ` rin at NetBSD dot org
2023-07-14 1:40 ` cvs-commit at gcc dot gnu.org
2023-07-14 1:45 ` cvs-commit at gcc dot gnu.org
2023-07-14 1:51 ` cvs-commit at gcc dot gnu.org
2023-07-14 2:03 ` cvs-commit at gcc dot gnu.org
2023-07-14 2:10 ` olegendo at gcc dot gnu.org
2023-07-18 3:57 ` rin at NetBSD dot org
2023-07-18 4:05 ` olegendo at gcc dot gnu.org
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