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[Bug tree-optimization/69376] 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: Wed, 20 Jan 2016 04:32:37 +0000
- Subject: [Bug tree-optimization/69376] 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=69376
Bug ID: 69376
Summary: wrong code at -Os and above on x86_64-linux-gnu
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
Target Milestone: ---
The current gcc trunk miscompiles the following code on x86_64-linux-gnu at -Os
and above in both 32-bit and 64-bit modes.
This is a regression from 5.3.x.
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-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 6.0.0 20160119 (experimental) [trunk revision 232571] (GCC)
$
$ gcc-trunk -O1 small.c; ./a.out
$ gcc-5.3 -Os small.c; ./a.out
$
$ gcc-trunk -Os small.c
$ ./a.out
Segmentation fault (core dumped)
$
-----------------------------------------
int printf (const char *, ...);
unsigned a, c, *d, f;
char b, e;
short g;
void
fn1 ()
{
unsigned h = 4294967290;
if (b >= 0)
{
h = b;
c = b / 290;
f = ~(c - (8 || h));
if (f)
printf ("%d\n", 1);
if (f)
printf ("%d\n", f);
g = ~f;
if (c < 3)
{
int i = -h < ~c;
unsigned j;
if (i)
j = h;
h = -j * g;
}
c = h;
}
unsigned k = ~h;
char l = e || g;
if (l < 1 || k < 7)
*d = a;
}
int
main ()
{
fn1 ();
return 0;
}