[Bug c/79757] New: ICE in declare_vars, at gimplify.c:634

[gerhard.steinmetz.fortran@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79757

            Bug ID: 79757
           Summary: ICE in declare_vars, at gimplify.c:634
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gerhard.steinmetz.fortran@t-online.de
  Target Milestone: ---

With invalid code on x86_64 GNU/Linux and option
-fsanitize=undefined  or  -fsanitize=integer-divide-by-zero,
down to version 4.9 (configured with --enable-checking=yes) :


$ cat z1.c
void fn1 ()
{
  unsigned __int128 x, y;
  int a() //;
  unsigned long long z = x % y;
}


$ gcc-7-20170226 -fsanitize=undefined -c z1.c
z1.c: In function 'a':
z1.c:5:3: error: parameter 'z' is initialized
   unsigned long long z = x % y;
   ^~~~~~~~
z1.c:5:3: internal compiler error: Segmentation fault
0xbf9f9f crash_signal
        ../../gcc/toplev.c:337
0x96d463 gbind* as_a<gbind*, gimple>(gimple*)
        ../../gcc/is-a.h:192
0x96d463 declare_vars(tree_node*, gimple*, bool)
        ../../gcc/gimplify.c:634
0x94999a create_tmp_var(tree_node*, char const*)
        ../../gcc/gimple-expr.c:477
0xc1bce1 ubsan_encode_value(tree_node*, bool)
        ../../gcc/ubsan.c:146
0x757fa5 ubsan_instrument_division(unsigned int, tree_node*, tree_node*)
        ../../gcc/c-family/c-ubsan.c:100
0x69aeab build_binary_op(unsigned int, tree_code, tree_node*, tree_node*, int)
        ../../gcc/c/c-typeck.c:11834
0x69e7a6 parser_build_binary_op(unsigned int, tree_code, c_expr, c_expr)
        ../../gcc/c/c-typeck.c:3637
0x6bbd8a c_parser_binary_expression
        ../../gcc/c/c-parser.c:6818
0x6bc225 c_parser_conditional_expression
        ../../gcc/c/c-parser.c:6458
0x6bc980 c_parser_expr_no_commas
        ../../gcc/c/c-parser.c:6375
0x6c371a c_parser_initializer
        ../../gcc/c/c-parser.c:4351
0x6cfe5d c_parser_declaration_or_fndef
        ../../gcc/c/c-parser.c:1919
0x6d06ee c_parser_declaration_or_fndef
        ../../gcc/c/c-parser.c:2073
0x6d4dc2 c_parser_compound_statement_nostart
        ../../gcc/c/c-parser.c:4831
0x6d53ee c_parser_compound_statement
        ../../gcc/c/c-parser.c:4740
0x6d082c c_parser_declaration_or_fndef
        ../../gcc/c/c-parser.c:2112
0x6d87fb c_parser_external_declaration
        ../../gcc/c/c-parser.c:1468
0x6d9259 c_parser_translation_unit
        ../../gcc/c/c-parser.c:1348
0x6d9259 c_parse_file()
        ../../gcc/c/c-parser.c:18173