re PR target/39137 (-mpreferred-stack-boundary=2 causes lots of dynamic realign)

re PR target/39137 (-mpreferred-stack-boundary=2 causes lots of dynamic realign)

	PR target/39137
	* cfgexpand.c (get_decl_align_unit): Use LOCAL_DECL_ALIGNMENT
	macro.
	* defaults.h (LOCAL_DECL_ALIGNMENT): Define if not yet defined.
	* config/i386/i386.h (LOCAL_DECL_ALIGNMENT): Define.
	* config/i386/i386.c (ix86_local_alignment): For
	-m32 -mpreferred-stack-boundary=2 use 32-bit alignment for
	long long variables on the stack to avoid dynamic realignment.
	Allow the first argument to be a decl rather than type.
	* doc/tm.texi (LOCAL_DECL_ALIGNMENT): Document.

	* gcc.target/i386/stackalign/longlong-1.c: New test.
	* gcc.target/i386/stackalign/longlong-2.c: New test.

From-SVN: r144792