re PR tree-optimization/28888 (ICE in tree check: expected cond_expr, have label_expr in simplify_using_initial_conditions, at tree-ssa-loop-niter.c)

	PR tree-optimization/28888
	* tree-if-conv.c (combine_blocks): Rewritten.
	* tree-cfg.c (tree_verify_flow_info): Check that edges with
	EDGE_TRUE/FALSE_VALUE follow COND_EXPR.

	* gcc.dg/pr28888.c: New test.

From-SVN: r117135