PR rtl-optimization/40667
	* defaults.h (MINIMUM_ALIGNMENT): Define if not defined.
	* doc/tm.texi (MINIMUM_ALIGNMENT): Document it.
	* config/i386/i386.h (MINIMUM_ALIGNMENT): Define.
	* config/i386/i386.c (ix86_minimum_alignment): New function.
	* config/i386/i386-protos.h (ix86_minimum_alignment): New prototype.
	* cfgexpand.c (expand_one_var): Use MINIMIM_ALIGNMENT.
	* emit-rtl.c (gen_reg_rtx): Likewise.
	* function.c (assign_parms): Likewise.  If nominal_type needs
	bigger alignment than FUNCTION_ARG_BOUNDARY, use its alignment
	rather than passed_type's alignment.

From-SVN: r149513