[Bug tree-optimization/67109] New: ICE at -O3 on x86_64-linux-gnu in vect_analyze_slp_instance, at tree-vect-slp.c:1793
su at cs dot ucdavis.edu
gcc-bugzilla@gcc.gnu.org
Tue Aug 4 06:33:00 GMT 2015
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67109
Bug ID: 67109
Summary: ICE at -O3 on x86_64-linux-gnu in
vect_analyze_slp_instance, at tree-vect-slp.c:1793
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 following code causes an ICE when compiled with the current gcc trunk at
-O3 on x86_64-linux-gnu in the 64-bit mode (but not in the 32-bit mode).
It is a regression from 5.1.x (I didn't check 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 20150803 (experimental) [trunk revision 226526] (GCC)
$
$ gcc-trunk -m64 -O2 -c small.c
small.c: In function ‘fn1’:
small.c:12:9: warning: iteration 1u invokes undefined behavior
[-Waggressive-loop-optimizations]
b[a] ^= 1;
^
small.c:10:7: note: containing loop
for (; c < 5; c++)
^
$ gcc-trunk -m32 -O3 -c small.c
small.c: In function ‘fn1’:
small.c:12:9: warning: iteration 1u invokes undefined behavior
[-Waggressive-loop-optimizations]
b[a] ^= 1;
^
small.c:10:7: note: containing loop
for (; c < 5; c++)
^
$
$ gcc-5.1 -m64 -O3 -c small.c
small.c: In function ‘fn1’:
small.c:12:9: warning: iteration 1u invokes undefined behavior
[-Waggressive-loop-optimizations]
b[a] ^= 1;
^
small.c:10:7: note: containing loop
for (; c < 5; c++)
^
$
$ gcc-trunk -m64 -O3 -c small.c
small.c: In function ‘fn1’:
small.c:12:9: warning: iteration 1u invokes undefined behavior
[-Waggressive-loop-optimizations]
b[a] ^= 1;
^
small.c:10:7: note: containing loop
for (; c < 5; c++)
^
small.c:5:1: internal compiler error: in vect_analyze_slp_instance, at
tree-vect-slp.c:1793
fn1 ()
^
0xcf91c5 vect_analyze_slp_instance
../../gcc-trunk/gcc/tree-vect-slp.c:1793
0xcf9ab7 vect_analyze_slp(_loop_vec_info*, _bb_vec_info*, unsigned int)
../../gcc-trunk/gcc/tree-vect-slp.c:1879
0xcf9eee vect_slp_analyze_bb_1
../../gcc-trunk/gcc/tree-vect-slp.c:2426
0xcf9eee vect_slp_analyze_bb(basic_block_def*)
../../gcc-trunk/gcc/tree-vect-slp.c:2552
0xcfce22 execute
../../gcc-trunk/gcc/tree-vectorizer.c:702
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$
---------------------------
unsigned int a;
int b[1], c, d;
void
fn1 ()
{
for (; d;)
{
a = c = 0;
for (; c < 5; c++)
{
b[a] ^= 1;
a--;
}
}
}
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