(block_alloc): Generalize tying so we can tie any operand with the
output unless some operand must be in the same register as the output,
in which case only try tying that operand.
From-SVN: r3075
(optimize_reg_copy_1): Tighten up code to properly handle the case
when SRC or DEST is a multi-word hard register and only some parts of
the register are set or used. Also, avoid updating register status
for DEST if we can't do the optimization.
From-SVN: r2380
(alloc_qty_for_scratch, block_alloc): Provide alternate code in some cases
when REGISTER_CONSTRAINTS is not defined.
(requires_inout_p): Only used when REGISTER_CONSTRAINTS is defined.
From-SVN: r1899
