Backport from mainline

	Backport from mainline
	2011-03-17  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/48141
	* params.def (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES): New.
	* dse.c: Include params.h.
	(active_local_stores_len): New variable.
	(add_wild_read, dse_step1): Clear it when setting active_local_stores
	to NULL.
	(record_store, check_mem_read_rtx): Decrease it when removing
	from the chain.
	(scan_insn): Likewise.  Increase it when adding to chain, if it
	reaches PARAM_MAX_DSE_ACTIVE_LOCAL_STORES limit, set to 1 and
	set active_local_stores to NULL before the addition.
	* Makefile.in (dse.o): Depend on $(PARAMS_H).

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_6-branch@171546 138bc75d-0d04-0410-961f-82ee72b054a4