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From: "zeccav at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/61158] New: negative shift at fold-const.c:12095
Date: Mon, 12 May 2014 18:03:00 -0000 [thread overview]
Message-ID: <bug-61158-4@http.gcc.gnu.org/bugzilla/> (raw)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61158
Bug ID: 61158
Summary: negative shift at fold-const.c:12095
Product: gcc
Version: 4.9.1
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: zeccav at gmail dot com
Compilation of the following forces a negative shift, result undefined in my
opinion
/* gcc -S negative shift at fold-const.c:12095
* x86_64
* "zerobits <<= prec - shiftc;"
* because prec - shiftc = -8
* result is undefined
* compiling Linux Fedora 20 source code kernel/trace/blktrace.c
* checked with "gcc_assert(prec >= shiftc && prec-shiftc <
HOST_BITS_PER_WIDE_INT);" immediately before
*/
typedef unsigned long long __u64;
void blk_add_trace_unplug(unsigned int depth)
{
((__u64)(depth) & (__u64)0x00ff000000000000ULL) >> 40;
}
next reply other threads:[~2014-05-12 18:03 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-12 18:03 zeccav at gmail dot com [this message]
2014-05-13 18:10 ` [Bug middle-end/61158] " mpolacek at gcc dot gnu.org
2014-05-14 5:19 ` zeccav at gmail dot com
2014-05-14 10:08 ` mpolacek at gcc dot gnu.org
2014-05-14 10:40 ` jakub at gcc dot gnu.org
2014-05-15 10:01 ` jakub at gcc dot gnu.org
2014-05-15 10:08 ` jakub at gcc dot gnu.org
2014-05-15 10:08 ` jakub at gcc dot gnu.org
2014-09-06 17:13 ` danglin at gcc dot gnu.org
2014-09-06 18:01 ` danglin at gcc dot gnu.org
2021-02-21 7:51 ` zeccav at gmail dot com
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