loop-24.c: Update dump file matching; enable -O2.

loop-24.c: Update dump file matching; enable -O2.

	* gcc.dg/tree-ssa/loop-24.c: Update dump file matching; enable -O2.
	* gcc.dg/tree-ssa/loop-25.c: Likewise.
	* gcc.dg/tree-ssa/loop-26.c: Likewise.
	* gcc.dg/tree-ssa/pr32044.c: Likewise.
	* gcc.dg/tree-ssa/loop-29.c: Likewise.
	* gcc.dg/tree-ssa/loop-10.c: Likewise.
	* gnat.dg/loop_optimization6.adb: Enable -O2.

	* ipa-pure-const.c (analyze): Update loop optimizer init.
	* tree-ssa-loop-iv-canon.c (empty_loop_p, remove_empty_loop,
	try_remove_empty_loop, remove_empty_loops): Remove.
	* tree-ssa-loop.c (tree_ssa_empty_loop, pass_empty_loop): Remove.
	* tree-ssa-dce.c (find_obviously_necessary_stmts): Use finiteness info
	to mark regular loops as neccesary.
	(degenerate_phi_p): New function.
	(propagate_necessity, remove_dead_phis): Use it.
	(forward_edge_to_pdom): Likewise.
	(eliminate_unnecessary_stmts): Take care to remove uses of results of
	virtual PHI nodes that became unreachable.
	(perform_tree_ssa_dce): Initialize/deinitialize loop optimizer.
	* tree-flow.h (remove_empty_loops): Remove.
	* passes.c (init_optimization_passes): Remove.

From-SVN: r149206