[Bug tree-optimization/71059] New: gcc ICE at -O3 on valid code on x86_64-linux-gnu in "vn_nary_op_insert_into"

[helloqirun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71059

            Bug ID: 71059
           Summary: gcc ICE at -O3 on valid code on x86_64-linux-gnu in
                    "vn_nary_op_insert_into"
           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 gcc trunk
at only -O3 on x86_64-linux-gnu in both 32-bit and 64-bit modes.

It appears to be a 7 regression.


$ 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 20160510 (experimental) [trunk revision 236075] (GCC)


$ gcc-trunk -O3 abc.c
abc.c: In function ‘fn2’:
abc.c:8:6: internal compiler error: in vn_nary_op_insert_into, at
tree-ssa-sccvn.c:2735
 void fn2() {
      ^~~
0xd564b0 vn_nary_op_insert_into
        ../../gcc/gcc/tree-ssa-sccvn.c:2735
0xd569e6 vn_nary_build_or_lookup
        ../../gcc/gcc/tree-ssa-sccvn.c:1699
0xd5942c vn_reference_lookup_3
        ../../gcc/gcc/tree-ssa-sccvn.c:1955
0xca6e46 walk_non_aliased_vuses(ao_ref*, tree_node*, void* (*)(ao_ref*,
tree_node*, unsigned int, void*), void* (*)(ao_ref*, tree_node*, void*, bool*),
tree_node* (*)(tree_node*), void*)
        ../../gcc/gcc/tree-ssa-alias.c:2734
0xd575e0 vn_reference_lookup_pieces(tree_node*, int, tree_node*,
vec<vn_reference_op_struct, va_heap, vl_ptr>, vn_reference_s**, vn_lookup_kind)
        ../../gcc/gcc/tree-ssa-sccvn.c:2305
0xd37696 phi_translate_1
        ../../gcc/gcc/tree-ssa-pre.c:1599
0xd3551d phi_translate
        ../../gcc/gcc/tree-ssa-pre.c:1740
0xd383e4 do_partial_partial_insertion
        ../../gcc/gcc/tree-ssa-pre.c:3338
0xd383e4 insert_aux
        ../../gcc/gcc/tree-ssa-pre.c:3458
0xd37d1f insert_aux
        ../../gcc/gcc/tree-ssa-pre.c:3466
0xd37d1f insert_aux
        ../../gcc/gcc/tree-ssa-pre.c:3466
0xd3a3e7 insert
        ../../gcc/gcc/tree-ssa-pre.c:3489
0xd3a3e7 execute
        ../../gcc/gcc/tree-ssa-pre.c:4788
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
short a, c;
union {
  unsigned f0;
  unsigned short f1;
} b;
volatile int d;
short fn1(short p1) { return p1 + a; }
void fn2() {
  b.f0 = 0;
  for (;; b.f0 = fn1(b.f0))
    (c && b.f1) || d;
}