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From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/103202] [12 regression] gcc miscompiles ed-1.17 since r12-3876-g4a960d548b7d7d94
Date: Fri, 12 Nov 2021 15:23:41 +0000 [thread overview]
Message-ID: <bug-103202-4-yT0TdAhvrk@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103202-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103202
Aldy Hernandez <aldyh at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |aldyh at gcc dot gnu.org
--- Comment #8 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
The problem here is this thread:
[5] Registering jump thread: (13, 11) incoming edge; (11, 10) nocopy;
BB11 has this:
=========== BB 11 ============
Imports: n_42
Exports: n_42
Relational : (n_45 < n_42)
<bb 11> [local count: 118111614]:
# np_43 = PHI <np_19(13), &buffer_head(4)>
# n_42 = PHI <m_31(13), addr_14(D)(4)>
# m_31 = PHI <0(13), m_16(4)>
n_45 = n_42 + -1;
if (n_42 != 0)
goto <bb 12>; [89.00%]
else
goto <bb 10>; [11.00%]
Because of the ordering of the import bitmap, we solve m_31 first to 0. Then,
when we solve n_42, we think we can use the m_31 in the cache, but the ordering
is wrong.
PHIs must always be done first. We went through a similar exercise to get
relationals right and somehow missed this.
next prev parent reply other threads:[~2021-11-12 15:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-11 23:59 [Bug tree-optimization/103202] New: [12 regression] gcc miscompiles ed-1.17 slyfox at gcc dot gnu.org
2021-11-12 0:01 ` [Bug tree-optimization/103202] " pinskia at gcc dot gnu.org
2021-11-12 0:05 ` pinskia at gcc dot gnu.org
2021-11-12 1:38 ` pinskia at gcc dot gnu.org
2021-11-12 7:43 ` rguenth at gcc dot gnu.org
2021-11-12 9:15 ` slyfox at gcc dot gnu.org
2021-11-12 9:33 ` rguenth at gcc dot gnu.org
2021-11-12 9:35 ` [Bug tree-optimization/103202] [12 regression] gcc miscompiles ed-1.17 since r12-3876-g4a960d548b7d7d94 marxin at gcc dot gnu.org
2021-11-12 10:18 ` aldyh at gcc dot gnu.org
2021-11-12 10:19 ` aldyh at gcc dot gnu.org
2021-11-12 15:23 ` aldyh at gcc dot gnu.org [this message]
2021-11-12 15:24 ` aldyh at gcc dot gnu.org
2021-11-12 16:42 ` slyfox at gcc dot gnu.org
2021-11-12 19:46 ` cvs-commit at gcc dot gnu.org
2021-11-12 19:47 ` aldyh at gcc dot gnu.org
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