[Bug tree-optimization/67689] New: wrong code at -O1, -O2 and -O3 on x86_64-linux-gnu
su at cs dot ucdavis.edu
gcc-bugzilla@gcc.gnu.org
Wed Sep 23 01:28:00 GMT 2015
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67689
Bug ID: 67689
Summary: wrong code at -O1, -O2 and -O3 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
-O1, -O2 and -O3 in both 32-bit and 64-bit modes.
This is a regression from 5.2.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 20150922 (experimental) [trunk revision 228013] (GCC)
$
$ gcc-trunk -O0 small.c; ./a.out
$ gcc-5.2 -O1 small.c; ./a.out
$
$ gcc-trunk -O1 small.c
$ ./a.out
Aborted
$
----------------------------------
int a, b, c = 1, d, e;
void
fn1 ()
{
e = c >> b ? c : c << 1;
for (b = 0; b < 1; b++)
d = a ? 0 : e ^ 1;
d = 0;
}
int
main ()
{
fn1 ();
if (e != 1)
__builtin_abort ();
return 0;
}
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