* PR rtl-optimization/39077
	* doc/invoke.texi (max-gcse-insertion-ratio): Document.
	* params.h (MAX_GCSE_INSERTION_RATIO): Define.
	* params.def (PARAM_MAX_GCSE_INSERTION_RATIO): Define.
	* lcm.c (pre_edge_lcm): Properly initialize output sbitmaps.
	* gcse.c (prune_insertions_deletions): New function.
	(compute_pre_data): Use it.

From-SVN: r168747