* c-tree.h (C_DECL_REGISTER): New.
	* c-aux-info.c (gen_decl), c-decl.c (objc_mark_locals_volatile,
	finish_decl, grokdeclarator, get_parm_info), c-typeck.c
	(build_array_ref, c_mark_addressable): Set and use it.
	* c-decl.c (grokdeclarator), c-typeck.c (c_mark_addressable):
	Allow structures with volatile fields to be declared register.
	Don't check TREE_ADDRESSABLE before warning about taking address
	of register.
	* c-decl.c (finish_decl): Don't allow structures with volatile
	fields to be placed in named register.
	* doc/trouble.texi: Remove reference to structures with volatile
	fields in registers.

testsuite:
	* gcc.dg/940409-1.c: Remove XFAIL.
	* gcc.dg/reg-vol-struct-1.c: New test.

From-SVN: r80037