[Bug tree-optimization/70203] New: ICE at -O1 and above in copy_reference_ops_from_ref, at tree-ssa-sccvn.c:958

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70203

            Bug ID: 70203
           Summary: ICE at -O1 and above in copy_reference_ops_from_ref,
                    at tree-ssa-sccvn.c:958
           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 on
x86_64-linux-gnu at -O1 and above in both 32-bit and 64-bit modes.

This is a regression from 4.9.x. 


$ g++-trunk -v
Using built-in specs.
COLLECT_GCC=g++-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-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 6.0.0 20160311 (experimental) [trunk revision 234134] (GCC) 
$ 
$ g++-trunk -O0 -c small.cpp
$ g++-4.9 -O1 -c small.cpp
$ 
$ g++-trunk -O1 -c small.cpp
small.cpp: In function ‘void foo()’:
small.cpp:6:1: internal compiler error: in copy_reference_ops_from_ref, at
tree-ssa-sccvn.c:880
 }
 ^
0xf07fe3 copy_reference_ops_from_ref
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:880
0xf09135 valueize_shared_reference_ops_from_ref
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:1501
0xf0a7e5 vn_reference_lookup(tree_node*, tree_node*, vn_lookup_kind,
vn_reference_s**, bool)
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:2250
0xf0e224 visit_reference_op_load
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:3356
0xf0e224 visit_use
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:3748
0xf10375 process_scc
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:3968
0xf10375 extract_and_process_scc_for_name
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:4055
0xf10375 DFS
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:4107
0xf10af7 sccvn_dom_walker::before_dom_children(basic_block_def*)
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:4574
0x1409826 dom_walker::walk(basic_block_def*)
        ../../gcc-source-trunk/gcc/domwalk.c:265
0xf11ff2 run_scc_vn(vn_lookup_kind)
        ../../gcc-source-trunk/gcc/tree-ssa-sccvn.c:4685
0xee28e2 execute
        ../../gcc-source-trunk/gcc/tree-ssa-pre.c:4895
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.

$


-----------------------------------


void
foo () 
{
  if (__builtin_constant_p (foo))
    ;
}