[Bug tree-optimization/57400] [4.9 Regression] ICE: verify_ssa failed (definition in block n follows the use)

["d.g.gorbachev at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57400

--- Comment #2 from Dmitry Gorbachev <d.g.gorbachev at gmail dot com> ---
The following testcase causes a similar error / ICE (although I can't reproduce
the bug with the original testcase).

======================== 8< ========================
extern void bar(double);

struct S {
  int n;
};

void foo(struct S s, double a, int i, int j, int k)
{
  struct S t;
  bar(s.n * a * i * j);
  t.n = s.n * a * i * k;
}
======================== >8 ========================

$ gcc -S -g -O -ffast-math bug.c
bug.c: In function 'foo':
bug.c:7:6: error: definition in block 2 follows the use
 void foo(struct S s, double a, int i, int j, int k)
      ^
for SSA_NAME: _4 in statement:
# DEBUG D#3 => _4 * _6
bug.c:7:6: internal compiler error: verify_ssa failed
0x888c299 verify_ssa(bool)
    ../../gcc-4.9/gcc/tree-ssa.c:1046
0x85dc5ca execute_function_todo
    ../../gcc-4.9/gcc/passes.c:1970
0x85db901 do_per_function
    ../../gcc-4.9/gcc/passes.c:1707
0x85dc6df execute_todo
    ../../gcc-4.9/gcc/passes.c:2002
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GCC 4.9.0 20130630 (experimental).