x86: Properly find the maximum stack slot alignment

x86: Properly find the maximum stack slot alignment

Don't assume that stack slots can only be accessed by stack or frame
registers.  We first find all registers defined by stack or frame
registers.  Then check memory accesses by such registers, including
stack and frame registers.

gcc/

	PR target/109780
	PR target/109093
	* config/i386/i386.cc (ix86_update_stack_alignment): New.
	(ix86_find_all_reg_use_1): Likewise.
	(ix86_find_all_reg_use): Likewise.
	(ix86_find_max_used_stack_alignment): Also check memory accesses
	from registers defined by stack or frame registers.

gcc/testsuite/

	PR target/109780
	PR target/109093
	* g++.target/i386/pr109780-1.C: New test.
	* gcc.target/i386/pr109093-1.c: Likewise.
	* gcc.target/i386/pr109780-1.c: Likewise.
	* gcc.target/i386/pr109780-2.c: Likewise.
	* gcc.target/i386/pr109780-3.c: Likewise.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>