re PR tree-optimization/34244 (VRP/SCEV miscompiles Firefox)

2008-05-31  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/34244
	* fold-const.c (tree_expr_nonnegative_warnv_p): Do not ask VRP.
	(tree_expr_nonzero_warnv_p): Likewise.
	* tree-vrp.c (vrp_expr_computes_nonnegative): Call
	ssa_name_nonnegative_p.
	(vrp_expr_computes_nonzero): Call ssa_name_nonzero_p.
	(extract_range_from_unary_expr): Use vrp_expr_computes_nonzero,
	not tree_expr_nonzero_warnv_p.

	PR tree-optimization/36262
	Revert
	2007-11-29  Zdenek Dvorak  <ook@ucw.cz>

        PR tree-optimization/34244
        * tree-vrp.c (adjust_range_with_scev): Clear scev cache.
        (record_numbers_of_iterations): New function.
        (execute_vrp): Cache the numbers of iterations of loops.
        * tree-scalar-evolution.c (scev_reset_except_niters):
        New function.
        (scev_reset): Use scev_reset_except_niters.
        * tree-scalar-evolution.h (scev_reset_except_niters): Declare.

From-SVN: r136237