re PR tree-optimization/19431 (missed optimization with ifs and deferencing)

re PR tree-optimization/19431 (missed optimization with ifs and deferencing)

2007-04-18  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/19431
	PR tree-optimization/21463
	* tree-pass.h (pass_phiprop): Declare.
	* passes.c (init_optimization_passes): New phiprop pass.
	* tree-ssa-forwprop.c (struct phiprop_d): New structure.
	(phivn_valid_p): New helper function.
	(phiprop_insert_phi): Likewise.
	(propagate_with_phi): Likewise.
	(tree_ssa_phiprop): New propagator propagating loads
	through phi nodes if profitable.

	* gcc.c-torture/execute/20070212-1.c: New testcase.
	* gcc.c-torture/execute/20070212-2.c: Likewise.
	* gcc.c-torture/execute/20070212-3.c: Likewise.
	* gcc.dg/tree-ssa/pr19431.c: Likewise.
	* gcc.dg/tree-ssa/pr21463.c: Likewise.
	* g++.dg/tree-ssa/pr21463.C: Likewise.
	* g++.dg/tree-ssa/pr30738.C: Likewise.

From-SVN: r123946