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[Bug tree-optimization/58570] New: wrong code at -Os and above on x86_64-linux-gnu (both 32-bit and 64-bit modes)
- 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: Sat, 28 Sep 2013 20:53:39 +0000
- Subject: [Bug tree-optimization/58570] New: wrong code at -Os and above on x86_64-linux-gnu (both 32-bit and 64-bit modes)
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58570
Bug ID: 58570
Summary: wrong code at -Os and above on x86_64-linux-gnu (both
32-bit and 64-bit modes)
Product: gcc
Version: 4.9.0
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 mis-compiles the following code on x86_64-linux at -Os
and above in both 32-bit and 64-bit modes.
This is a regression from 4.8.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/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure
--enable-languages=c,c++,objc,obj-c++,fortran,lto --disable-werror
--enable-checking=release --with-gmp=/usr/local/gcc-trunk
--with-mpfr=/usr/local/gcc-trunk --with-mpc=/usr/local/gcc-trunk
--with-cloog=/usr/local/gcc-trunk --prefix=/usr/local/gcc-trunk
Thread model: posix
gcc version 4.9.0 20130928 (experimental) [trunk revision 203003] (GCC)
$
$ gcc-trunk -O1 small.c
$ a.out
1
$ gcc-4.8 -O3 small.c
$ a.out
1
$ gcc-trunk -O3 small.c
$ a.out
0
$ gcc-trunk -O2 small.c
$ a.out
0
$ gcc-trunk -Os small.c
$ a.out
0
$
------------------------------------
int printf (const char *, ...);
#pragma pack(1)
struct S
{
int f0:15;
int f1:29;
};
int a, b, c, e = 1, g;
static struct S d[6];
long long f;
static short
foo (int p)
{
for (b = 0; b < 1; b++)
{
g |= 1;
for (; a < 1; a++)
{
int i;
if (p < c - 1)
return 4;
if (p)
for (i = 0; i < 6; i++)
{
struct S j = {1, 1};
d[i] = j;
}
continue;
}
}
return 0;
}
int
main ()
{
if (e)
foo (!f);
printf ("%d\n", d[0].f1);
return 0;
}