[tree-ssa] Handle if (var) for jump threading

[law@redhat.com]

In message <20040116070329.GC22397@redhat.com>, Richard Henderson writes:
 >On Thu, Jan 15, 2004 at 11:12:08PM -0700, law@redhat.com wrote:
 >> ! 	      set_value_for (var, boolean_true_node, const_and_copies);
 >
 >Really?  Without checking to see that var is in fact boolean typed,
 >I'd expect this to go in nonzero_vars.
We shouldn't be getting non-booleans in conditionals.  If we do, then 
something bad has happened.

 >I do agree that we shouldn't be omitting the relational for
 >non-boolean variables, but I wouldn't feel comfortable assuming
 >that without a check in verify_stmt.
Then let's get the check in. :-)

Jeff