re PR tree-optimization/41783 (r151561 (PRE fix) regresses zeusmp)

re PR tree-optimization/41783 (r151561 (PRE fix) regresses zeusmp)

	PR tree-optimization/41783
	* tree-data-ref.c (toplevel): Include flags.h.
	(dump_data_dependence_relation):  Also dump the inputs if the
	result will be unknown.
	(split_constant_offset_1): Look through some conversions.
	* tree-predcom.c (determine_roots_comp): Restart a new chain if
	the offset from last element is too large.
	(ref_at_iteration): Deal also with MISALIGNED_INDIRECT_REF.
	(reassociate_to_the_same_stmt): Handle vector registers.
	* tree-vect-data-refs.c (vect_equal_offsets): Handle unary operations
	(e.g. conversions).
	* tree-vect-loop-manip.c (vect_gen_niters_for_prolog_loop): Add
	wide_prolog_niters argument, emit widening instructions.
	(vect_do_peeling_for_alignment): Adjust caller, use widened
	variant of the iteration cound.
	* Makefile.in (tree-data-ref.o): Add $(FLAGS_H).

testsuite/
	* gfortran.dg/vect/fast-math-mgrid-resid.f: New.

From-SVN: r156043