Optimize ia64_leave_syscall() a bit better for McKinley-type cores.
The patch looks big, but that's mostly due to renaming r16/r17 to r2/r3.
Good for a 13 cycle improvement.
Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>