PR target/38686

	PR target/38686
	PR target/38708
	* config/i386/i386.c (override_options): Reject
	-mstringop-strategy=rep_8byte with -m32.
	(ix86_expand_movmem): For size_needed == 1 set epilogue_size_needed
	to 1.  Do count comparison against epilogue_size_needed at compile
	time even when count_exp was constant forced into register.  For
	size_needed don't jump to epilogue, instead just avoid aligning
	and invoke the body algorithm.  If need_zero_guard, add zero guard
	even if count is non-zero, but smaller than size_needed + number of
	bytes that could be stored for alignment.
	(ix86_expand_setmem): For size_needed == 1 set epilogue_size_needed
	to 1.  If need_zero_guard, add zero guard even if count is non-zero,
	but smaller than size_needed + number of bytes that could be stored
	for alignment.  Compare size_needed with epilogue_size_needed instead
	of desired_align - align, don't adjust size_needed, pass
	epilogue_size_needed to the epilogue expanders.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@143211 138bc75d-0d04-0410-961f-82ee72b054a4