2016-11-02  Richard Biener  <rguenther@suse.de>

	* gimple-ssa-store-merging.c: Include gimplify-me.h.
	(imm_store_chain_info::output_merged_stores): Force base_addr
	to be proper GIMPLE for a MEM_REF address.
	(pass_store_merging::execute): Restrict negative bitpos
	handling to non-MEM_REF bases.  Remove TREE_THIS_VOLATILE
	check.  Take into account non-NULL_TREE offset if the base
	is already addressable.

	* gcc.dg/store_merging_8.c: New testcase.

From-SVN: r241796