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From: "wschmidt at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/65787] New: [5.1 regression] Miscompile due to bad vector swap optimization for little endian
Date: Thu, 16 Apr 2015 19:49:00 -0000 [thread overview]
Message-ID: <bug-65787-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65787
Bug ID: 65787
Summary: [5.1 regression] Miscompile due to bad vector swap
optimization for little endian
Product: gcc
Version: 5.1.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: target
Assignee: wschmidt at gcc dot gnu.org
Reporter: wschmidt at gcc dot gnu.org
CC: bergner at gcc dot gnu.org, dje.gcc at gmail dot com,
jakub at gcc dot gnu.org, rguenth at gcc dot gnu.org
Host: powerpc64le-linux-gnu
Target: powerpc64le-linux-gnu
Build: powerpc64le-linux-gnu
Created attachment 35337
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35337&action=edit
Preprocessed source
GCC 5.1 miscompiles the attached file. The POWER-specific vector swap
optimization doesn't recognize a vector extract pattern because it's hidden
inside a parallel with a clobber. As a result it doesn't adjust the lane to be
extracted. I'm working on a patch to detect this case and fix it up.
This is probably miscompiled by the latest 4.8 and 4.9 base code as well, since
the swap optimization was backported recently. I have not yet verified this,
though. It could be that this pattern is not created for those releases.
next reply other threads:[~2015-04-16 19:49 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-16 19:49 wschmidt at gcc dot gnu.org [this message]
2015-04-16 19:50 ` [Bug target/65787] " wschmidt at gcc dot gnu.org
2015-04-16 20:06 ` wschmidt at gcc dot gnu.org
2015-04-16 20:08 ` [Bug target/65787] [5 Regression] " jakub at gcc dot gnu.org
2015-04-16 21:51 ` jakub at gcc dot gnu.org
2015-04-16 21:58 ` jakub at gcc dot gnu.org
2015-04-17 4:46 ` wschmidt at gcc dot gnu.org
2015-04-17 13:28 ` wschmidt at gcc dot gnu.org
2015-04-17 14:51 ` wschmidt at gcc dot gnu.org
2015-04-17 15:09 ` wschmidt at gcc dot gnu.org
2015-04-17 20:36 ` wschmidt at gcc dot gnu.org
2015-04-17 22:05 ` wschmidt at gcc dot gnu.org
2015-04-19 16:51 ` wschmidt at gcc dot gnu.org
2015-04-19 16:53 ` wschmidt at gcc dot gnu.org
2015-04-19 16:55 ` wschmidt at gcc dot gnu.org
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