* gcse.c (struct expr:max_distance): New field.
(doing_code_hoisting_p): New static variable.
(want_to_gcse_p): Change signature. Allow constrained hoisting of
simple expressions, don't change behavior for PRE. Set max_distance.
(insert_expr_in_table): Set new max_distance field.
(hash_scan_set): Update.
(hoist_expr_reaches_here_p): Stop search after max_distance
instructions.
(find_occr_in_bb): New static function. Use it in ...
(hoist_code): Calculate sizes of basic block before any changes are
done. Pass max_distance to hoist_expr_reaches_here_p.
(one_code_hoisting_pass): Set doing_code_hoisting_p.
* params.def (PARAM_GCSE_COST_DISTANCE_RATIO,)
(PARAM_GCSE_UNRESTRICTED_COST): New parameters.
* params.h (GCSE_COST_DISTANCE_RATIO, GCSE_UNRESTRICTED_COST): New
macros.
* doc/invoke.texi (gcse-cost-distance-ratio, gcse-unrestricted-cost):
Document.
From-SVN: r162589
