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[Bug rtl-optimization/68376] New: wrong code at -O1 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 Nov 2015 19:19:09 +0000
- Subject: [Bug rtl-optimization/68376] New: wrong code at -O1 and above on x86_64-linux-gnu
- Auto-submitted: auto-generated
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68376
Bug ID: 68376
Summary: wrong code at -O1 and above on x86_64-linux-gnu
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
Target Milestone: ---
The current gcc trunk mis-compiles the following code on x86_64-linux-gnu at
-O1 and above in both 32-bit and 64-bit modes.
It also seems to affect all earlier GCC releases since as early as 4.6.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 20151115 (experimental) [trunk revision 230395] (GCC)
$
$ gcc-trunk -O0 small.c; ./a.out
$
$ gcc-trunk -O1 small.c; ./a.out
Aborted (core dumped)
$ gcc-4.6 -O1 small.c; ./a.out
Aborted (core dumped)
$
--------------------------------
int a, b, c = 1;
char d;
int
main ( )
{
for ( ; a < 1; a++ )
for ( ; b < 1; b++ )
{
char e = ~d;
if ( d < 1 )
e = d;
d = e;
if ( !c )
__builtin_abort ();
}
if ( d != 0 )
__builtin_abort ();
return 0;
}