http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58418
Bug ID: 58418
Summary: wrong code at -O2 and -O3 on x86_64-linux-gnu (in
32-bit mode)
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
The current gcc trunk produces wrong code for the attached testcase on
x86_64-linux-gnu when compiled at -O2 and -O3 in 32-bit mode.
It appears to be 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
--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 20130913 (experimental) [trunk revision 202556] (GCC)
$
$ gcc-trunk -m32 -O1 small.c
$ a.out
0
$ gcc-4.8 -m32 -O2 small.c
$ a.out
0
$ gcc-trunk -m64 -O2 small.c
$ a.out
0
$ gcc-trunk -m32 -O2 small.c
$ a.out
1
$
------------------------------------------
int printf (const char *, ...);
int a, b, *c = &b, d = -1, e, f, *g, *h = &f, **i = &g, j;
unsigned int
foo (unsigned int p)
{
return p == 0 ? 0 : 1 / p;
}
static int *
bar ()
{
*c = *h = foo (d) & (-9 < d);
for (e = 0; e; e++)
;
return 0;
}
int
main ()
{
for (; j; j++)
for (;; a--)
;
*i = bar ();
printf ("%d\n", f);
return 0;
}