[Bug tree-optimization/71483] New: g++ ICE at -O3 on valid code on x86_64-linux-gnu with âFloating point exceptionâ

["helloqirun at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71483

            Bug ID: 71483
           Summary: g++ ICE at -O3 on valid code on x86_64-linux-gnu with
                    âFloating point exceptionâ
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: helloqirun at gmail dot com
  Target Milestone: ---

The following valid code causes an ICE when compiled with the current g++ trunk
at only -O3 on x86_64-linux-gnu in 32- and 64-bit modes. 

gcc at -O3 works fine.

It started with r237064. I am not sure if it is a dup of pr71416 or pr71407.

$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/home/absozero/trunk/root-gcc/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/home/absozero/trunk/root-gcc
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 7.0.0 20160608 (experimental) [trunk revision 237212] (GCC) 


$ gcc-trunk -O3 -c abc.c
$
$ g++-trunk -O3 -c abc.c
abc.c: In function âvoid fn1()â:
abc.c:3:6: internal compiler error: Floating point exception
 void fn1() {
      ^~~
0xd3d9cf crash_signal
        ../../gcc/gcc/toplev.c:335
0xf833cc vectorizable_live_operation(gimple*, gimple_stmt_iterator*,
_slp_tree*, int, gimple**)
        ../../gcc/gcc/tree-vect-loop.c:6377
0xf7fdb6 vect_transform_stmt(gimple*, gimple_stmt_iterator*, bool*, _slp_tree*,
_slp_instance*)
        ../../gcc/gcc/tree-vect-stmts.c:8327
0xf9da2b vect_schedule_slp_instance
        ../../gcc/gcc/tree-vect-slp.c:3641
0xf9d7f4 vect_schedule_slp_instance
        ../../gcc/gcc/tree-vect-slp.c:3519
0xf9d7f4 vect_schedule_slp_instance
        ../../gcc/gcc/tree-vect-slp.c:3519
0xf9e2a6 vect_schedule_slp(vec_info*)
        ../../gcc/gcc/tree-vect-slp.c:3713
0xf8729d vect_transform_loop(_loop_vec_info*)
        ../../gcc/gcc/tree-vect-loop.c:6865
0xfa3c85 vectorize_loops()
        ../../gcc/gcc/tree-vectorizer.c:554
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.




$ cat abc.c
int b, c, d;
short *e;
void fn1() {
  for (; b; b--) {
    d = *e >> 2;
    *e++ = d;
    c = *e;
    *e++ = d;
  }
}