Don't create superfluous parm in expand_omp_taskreg

Don't create superfluous parm in expand_omp_taskreg

2015-08-23  Tom de Vries  <tom@codesourcery.com>

	* omp-low.c (expand_omp_taskreg): If in ssa, set rhs of parcopy stmt to
	parm_decl, rather than generating a dummy default def in cfun.
	* tree-cfg.c (replace_ssa_name): Assume no default defs.  Make sure
	ssa_name from cfun and child_fn do not share a stmt as def stmt.
	(move_stmt_op): Handle PARM_DECl.
	(gather_ssa_name_hash_map_from): New function.
	(move_sese_region_to_fn): Add default defs for function params, and add
	them to vars_map.  Release copied ssa names.
	* tree-cfg.h (gather_ssa_name_hash_map_from): Declare.

From-SVN: r227103