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From: "krebbel at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/94613] New: combine: Wrong code due to splitting a simplified IF_THEN_ELSE
Date: Thu, 16 Apr 2020 07:01:53 +0000 [thread overview]
Message-ID: <bug-94613-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94613
Bug ID: 94613
Summary: combine: Wrong code due to splitting a simplified
IF_THEN_ELSE
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: krebbel at gcc dot gnu.org
Target Milestone: ---
Created attachment 48284
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48284&action=edit
autoreduced testcase
When compiling the attached testcase for IBM Z GCC optimizes an OR operation
away during combine leading to wrong code being generated:
cc1plus -O3 -march=z14 t.ii -quiet -o t.s
try_combine is invoked for the following 3 insns:
i1: 28: r111 = r110 | r158
i2: 31: r115 = r111 - r94
i3: 36: r122 = (r110 == 0 ? r115 : r177)
i3 becomes the following after inserting i1 and i2
36: r122 = (r110 == 0 ? r110 | r158 - r94 : r177)
simplification omits ORing r110 since it is 0 anyway:
36: r122 = (r110 == 0 ? r158 - r94 : r177)
after not being able to recognize the insn it gets split into parts again:
28: deleted
31: r115 = r158 - r94
36: r122 = (r110 == 0 ? r115 : r177)
next reply other threads:[~2020-04-16 7:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 7:01 krebbel at gcc dot gnu.org [this message]
2020-04-16 7:02 ` [Bug rtl-optimization/94613] " krebbel at gcc dot gnu.org
2020-04-16 7:05 ` krebbel at gcc dot gnu.org
2020-04-16 7:05 ` krebbel at gcc dot gnu.org
2020-04-16 7:09 ` krebbel at gcc dot gnu.org
2020-04-16 7:10 ` rguenth at gcc dot gnu.org
2020-04-16 7:15 ` rguenth at gcc dot gnu.org
2020-04-16 7:37 ` krebbel at gcc dot gnu.org
2020-04-16 8:21 ` [Bug target/94613] Wrong code generated for vec_sel builtin krebbel at gcc dot gnu.org
2020-04-16 8:28 ` [Bug target/94613] S/390: " krebbel at gcc dot gnu.org
2020-04-16 21:18 ` segher at gcc dot gnu.org
2020-04-20 17:39 ` [Bug target/94613] S/390, powerpc: " cvs-commit at gcc dot gnu.org
2020-05-04 8:39 ` cvs-commit at gcc dot gnu.org
2020-05-04 8:43 ` cvs-commit at gcc dot gnu.org
2020-05-07 11:56 ` jakub at gcc dot gnu.org
2020-07-23 6:52 ` rguenth at gcc dot gnu.org
2021-04-08 12:02 ` rguenth at gcc dot gnu.org
2021-05-04 12:32 ` rguenth at gcc dot gnu.org
2021-05-27 0:57 ` luoxhu at gcc dot gnu.org
2021-10-28 3:18 ` cvs-commit at gcc dot gnu.org
2021-10-28 3:18 ` cvs-commit at gcc dot gnu.org
2021-10-28 6:04 ` luoxhu at gcc dot gnu.org
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