Mingjie Xing wrote:
> 2011/2/18 Fu, Chao-Ying <f...@mips.com>:
> > I think your analysis is correct. We should just delete
> mips_order_regs_for_local_alloc()
> > in mips.c and delete ADJUST_REG_ALLOC_ORDER in mips.h.
> > Then, 3 accumulators can be used in dspr2-MULT.c and
> dspr2-MULTU.c now. Thanks!
>
> /* ADJUST_REG_ALLOC_ORDER is a macro which permits reg_alloc_order
> to be rearranged based on a particular function. On the mips16, we
> want to allocate $24 (T_REG) before other registers for
> instructions for which it is possible. */
>
> #define ADJUST_REG_ALLOC_ORDER mips_order_regs_for_local_alloc ()
>
> I'm just wondering if it Is appropriate to simply remove
> ADJUST_REG_ALLOC_ORDER considering its comment.
Ok. Need to test if allocating $24 first is still better in MIPS16 under IRA.
If yes, we should update mips_order_regs_for_local_alloc() for MIPS16 only
(eg: exchange $24 and $1), as the default register order is as follows.
Ex:
/* We generally want to put call-clobbered registers ahead of
call-saved ones. (IRA expects this.) */
#define REG_ALLOC_ORDER \
{ /* Accumulator registers. When GPRs and accumulators have equal \
cost, we generally prefer to use accumulators. For example, \
a division of multiplication result is better allocated to LO, \
so that we put the MFLO at the point of use instead of at the \
point of definition. It's also needed if we're to take advantage \
of the extra accumulators available with -mdspr2. In some cases, \
it can also help to reduce register pressure. */ \
64, 65,176,177,178,179,180,181, \
/* Call-clobbered GPRs. */ \
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, \
24, 25, 31, \
...
Regards,
Chao-ying
