------- Comment #5 from Joey dot ye at intel dot com 2009-02-12 01:45 -------
Stack realign is finalized by
stack_realign = (incoming_stack_boundary
< (current_function_is_leaf
? crtl->max_used_stack_slot_alignment
: crtl->stack_alignment_needed));
since bar is leaf function, it checks max_used_stack_slot_alignment.
According to it's definition, max_used_stack_slot_alignment is /* The largest
alignment of slot allocated on the stack. */. Parameter x isn't allocated on
local stack, so max_used_stack_slot_alignment shouldn't be set to 256 bits.
In locate_and_pad_parm,
if (crtl->max_used_stack_slot_alignment < crtl->stack_alignment_needed)
crtl->max_used_stack_slot_alignment = crtl->stack_alignment_needed;
sets max_used_stack_slot_alignment to 256 bits, which seems shouldn't happen
all the time.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39146
