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From: "skunk at iskunk dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/18665] New: -ftrapv borks up simple integer arithmetic
Date: Wed, 24 Nov 2004 22:29:00 -0000 [thread overview]
Message-ID: <20041124222749.18665.skunk@iskunk.org> (raw)
A large program was failing mysteriously on our new Opteron box. Went through it
with a fine-toothed debugger, until I came to the line
k -= i; /* <k> and <i> are ints */
Before this line: k == 2, i == 1
After this line: k == -14, i == 1
Compiling without -ftrapv makes this weirdness go away.
I will attach a tarball containing two .c files and a makefile, basically the
aforementioned big program with all irrelevant code ripped out---just enough to
reproduce the problem.
This bug first came up with 3.4.2, as shipped with Fedora Core 3 (x86-64). I
built 3.4.3 with the below configuration to confirm that the bug is still present.
Output from "gcc -v"
====================
Reading specs from
/mnt/freeport/opt/gcc-3.4.3--linux64/bin/../lib/gcc/x86_64-unknown-linux-gnu/3.4.3/specs
Configured with: /mnt/freeport/src/gcc/current/configure
--prefix=/mnt/freeport/arch/linux64 --disable-dependency-tracking
--disable-shared --disable-nls --with-libiconv-prefix=/mnt/freeport/arch/linux64
--disable-multilib --with-arch=opteron
Thread model: posix
gcc version 3.4.3
--
Summary: -ftrapv borks up simple integer arithmetic
Product: gcc
Version: 3.4.3
Status: UNCONFIRMED
Severity: critical
Priority: P2
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: skunk at iskunk dot org
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18665
next reply other threads:[~2004-11-24 22:29 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-24 22:29 skunk at iskunk dot org [this message]
2004-11-24 22:32 ` [Bug target/18665] " skunk at iskunk dot org
2004-11-24 22:42 ` pinskia at gcc dot gnu dot org
2004-11-28 0:07 ` steven at gcc dot gnu dot org
2004-11-28 0:22 ` steven at gcc dot gnu dot org
2004-11-28 0:26 ` steven at gcc dot gnu dot org
2004-11-28 0:31 ` [Bug target/18665] [4.0 Regression] " steven at gcc dot gnu dot org
2004-11-28 0:33 ` [Bug target/18665] [3.4/4.0 " pinskia at gcc dot gnu dot org
2004-11-28 0:34 ` steven at gcc dot gnu dot org
2004-11-28 13:00 ` steven at gcc dot gnu dot org
2004-12-06 18:45 ` ebotcazou at gcc dot gnu dot org
2004-12-06 18:47 ` ebotcazou at gcc dot gnu dot org
2004-12-06 20:51 ` rth at gcc dot gnu dot org
2004-12-07 6:59 ` ebotcazou at gcc dot gnu dot org
2004-12-07 14:36 ` schlie at comcast dot net
2004-12-10 7:35 ` ebotcazou at gcc dot gnu dot org
2004-12-10 9:53 ` ebotcazou at gcc dot gnu dot org
2004-12-10 10:11 ` ebotcazou at gcc dot gnu dot org
2004-12-10 18:59 ` [Bug other/18665] " rth at gcc dot gnu dot org
2004-12-10 19:24 ` ebotcazou at gcc dot gnu dot org
2004-12-10 19:40 ` rth at gcc dot gnu dot org
2004-12-10 20:04 ` ebotcazou at gcc dot gnu dot org
2004-12-10 20:17 ` rth at gcc dot gnu dot org
2004-12-11 9:39 ` ebotcazou at gcc dot gnu dot org
2004-12-11 23:12 ` rth at gcc dot gnu dot org
2004-12-12 7:19 ` ebotcazou at gcc dot gnu dot org
2004-12-13 17:11 ` pinskia at gcc dot gnu dot org
2004-12-14 14:17 ` pinskia at gcc dot gnu dot org
2004-12-14 14:36 ` ebotcazou at gcc dot gnu dot org
2004-12-15 12:31 ` cvs-commit at gcc dot gnu dot org
2004-12-15 12:35 ` cvs-commit at gcc dot gnu dot org
2004-12-15 12:39 ` ebotcazou at gcc dot gnu dot org
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