* rtlanal.c (rtx_unstable_p): The pic register is stable

	* rtlanal.c (rtx_unstable_p): The pic register is stable
	(within one function) and the actual rtx should be used
	when checking the registers.
	(rtx_addr_can_trap_p): Pic memory addresses can't trap.

	* alias.c (true_dependence, write_dependence_p): Fix
	bug in previous patch.

	* i386.c (ix86_GOT_alias_set): New.
	(legitimize_pic_address): Use it.

	* rtlanal.c (rtx_unstable_p): An unchanging MEM is
	only stable if its address is stable.
	(rtx_varies_p): An unchanging MEM can't vary if
	its address doesn't vary.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@35900 138bc75d-0d04-0410-961f-82ee72b054a4