rtlanal.c (rtx_unstable_p): The pic register is stable (within one function) and the actual rtx should be...

	* 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.

From-SVN: r35900