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[Bug rtl-optimization/68721] 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: Sat, 05 Dec 2015 17:09:49 +0000
- Subject: [Bug rtl-optimization/68721] 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=68721
Bug ID: 68721
Summary: wrong code at -Os 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 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 20151204 (experimental) [trunk revision 231299] (GCC)
$
$ gcc-trunk -O1 small.c; ./a.out
$ gcc-5.3 -Os small.c; ./a.out
$
$ gcc-trunk -Os small.c
$ ./a.out
Aborted (core dumped)
$
---------------------------------
int a, b, c, *d, **e = &d;
int *
fn1 ()
{
for (;;)
{
for (; a;)
if (b)
__builtin_abort ();
break;
}
for (; c;)
;
return &a;
}
int
main ()
{
*e = fn1 ();
if (!d)
__builtin_abort ();
return 0;
}