* gimple.c (canonicalize_cond_expr_cond): Handle cast from
	boolean-type.
	(ssa_forward_propagate_and_combine): Interprete result of
	forward_propagate_comparison.
	* gcc/gimple-fold.c (fold_gimple_assign): Add canonicalization for
	boolean-typed operands for comparisons.

	* gcc.dg/tree-ssa/forwprop-15.c: New testcase.

From-SVN: r177170