[PATCH 3/3] Optimize 64-bit mpn_add_N and mpn_sub_N for sparc T3 and later.

[David Miller]

From: Torbjorn Granlund <tg at gmplib.org>
Date: Tue, 05 Mar 2013 16:01:11 +0100

> They should of course ether have applied the negation to the r1 operand,
> or used an unsigned imm field.

An unsigned imm field would eliminate a very useful existing construct.

Right now you can compose any 32-bit constant sign extended into a
64-bit register using:

	sethi	%hi(...), reg
	xor	reg, ..., reg

With an unsigned immediate field, you couldn't do that because
sethi always zero extends.