Disallow negative steps in vectorizer.

Disallow negative steps in vectorizer.

gcc/

2010-10-02  H.J. Lu  <hongjiu.lu@intel.com>

	PR tree-optimization/45720
	PR tree-optimization/45764
	* tree-vect-data-refs.c (vect_analyze_data_ref_access):
	Don't accept backwards consecutive accesses.
	(vect_create_data_ref_ptr): Disallow negative steps.

	* tree-vect-stmts.c (vectorizable_store): Allow negative steps.
	(perm_mask_for_reverse): Removed.
	(reverse_vec_elements): Likewise.
	(vectorizable_load): Don't hanle negative steps.

gcc/testsuite/

2010-10-02  H.J. Lu  <hongjiu.lu@intel.com>

	PR tree-optimization/45720
	PR tree-optimization/45764
	* g++.dg/torture/pr45764.C: New.

	* gcc.dg/vect/pr43432.c: Xfail.
	* gcc.dg/vect/vect-114.c: Likewise.
	* gcc.dg/vect/vect-15.c: Likewise.

From-SVN: r164914