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[Bug tree-optimization/61517] New: wrong code at -Os and above on x86_64-linux-gnu
- From: "su at cs dot ucdavis.edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 16 Jun 2014 03:11:36 +0000
- Subject: [Bug tree-optimization/61517] New: wrong code at -Os and above on x86_64-linux-gnu
- Auto-submitted: auto-generated
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61517
Bug ID: 61517
Summary: wrong code at -Os and above on x86_64-linux-gnu
Product: gcc
Version: 4.10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
The current gcc trunk miscompiles the following code on x86_64-linux at -Os and
above in both 32-bit and 64-bit modes.
This is a regression from 4.9.x.
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.10.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 4.10.0 20140615 (experimental) [trunk revision 211685] (GCC)
$
$ gcc-trunk -O1 small.c; a.out
$ gcc-4.9.0 -Os small.c; a.out
$
$ gcc-trunk -Os small.c
$ a.out
Aborted (core dumped)
$
--------------------------
int a, b, *c = &a;
unsigned short d;
int
main ()
{
unsigned int e = a;
*c = 1;
if (!b)
{
d = e;
*c = d | e;
}
if (a != 0)
__builtin_abort ();
return 0;
}