[Bug tree-optimization/77362] New: [7 Regression] [graphite] ICE in sese_build_liveouts_use w/ -O2 -floop-nest-optimize

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77362

            Bug ID: 77362
           Summary: [7 Regression] [graphite] ICE in
                    sese_build_liveouts_use w/ -O2 -floop-nest-optimize
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-7.0.0-alpha20160821 and some earlier snapshots (at least back to
7.0.0-alpha20160731) ICE when compiling the following snippet w/ -O2 (-O3,
-Ofast) -floop-nest-optimize:

int mc[2];
int f2, sk;
short int hm;

void
zm (void)
{
  int k1;

  for (k1 = 0; k1 < 2; ++k1)
    {
      for (sk = 0; sk < 2; ++sk)
        mc[sk] = hm = ++f2;
      if (hm >= 0)
        ++hm;
    }
}

% gcc-7.0.0-alpha20160821 -O2 -floop-nest-optimize -c rzmadogh.c   
rzmadogh.c: In function 'zm':
rzmadogh.c:6:1: internal compiler error: Segmentation fault

Backtrace is seemingly different for different targets, nevertheless
sese_build_liveouts_use is always on top. For x86_64 I have:

#0  0x00000000012ff0b1 in sese_build_liveouts_use(sese_info_t*, bitmap_head*,
basic_block_def*, tree_node*) ()
#1  0x00000000012ff87c in sese_insert_phis_for_liveouts(sese_info_t*,
basic_block_def*, edge_def*, edge_def*) ()
#2  0x000000000126859a in graphite_regenerate_ast_isl(scop*) ()
#3  0x000000000125edac in graphite_transform_loops() ()
#4  0x000000000125f2c1 in (anonymous
namespace)::pass_graphite_transforms::execute(function*) ()
#5  0x0000000000a8e236 in execute_one_pass(opt_pass*) ()
#6  0x0000000000a8e848 in execute_pass_list_1(opt_pass*) ()
#7  0x0000000000a8e85a in execute_pass_list_1(opt_pass*) ()
#8  0x0000000000a8e85a in execute_pass_list_1(opt_pass*) ()
#9  0x0000000000a8e85a in execute_pass_list_1(opt_pass*) ()
#10 0x0000000000a8e8a5 in execute_pass_list(function*, opt_pass*) ()
#11 0x000000000076e004 in cgraph_node::expand() ()
#12 0x000000000076f9a7 in symbol_table::compile() [clone .part.47] ()
#13 0x0000000000771c78 in symbol_table::finalize_compilation_unit() ()
#14 0x0000000000b5fd9d in compile_file() ()
#15 0x00000000005ced77 in toplev::main(int, char**) ()
#16 0x00000000005d10a7 in main ()