LEA-splitting improvement patch.

[Yuri Rumyantsev]

Hi Uros,

I send you new patch with fixed space/tab alignments.

About your comment.

It is more optimal to put adding of constant before adding of the
register only for case when 3 instructions must be generated to split
lea. In all other cases it does not matter and I left code
unchangeable.

Best regards.
Yuri.

2012/8/14 Uros Bizjak <ubizjak@gmail.com>:
> On Tue, Aug 14, 2012 at 3:35 PM, Yuri Rumyantsev <ysrumyan@gmail.com> wrote:
>> Uros,
>>
>> Let me try to explain you why I used such code duplication:
>>
>> Here we have a common case of LEA with 3 different registers - r0
>> (target), r1(base), r2(index) and possible offset.
>> To get the better scheduling we first try to determine what register
>> is prefirable for inititial setting - r1 or r2 through
>> find_nearest_reg_def. And then we generate the following sequence of
>> instructions:
>>        r0 = r_best;
>>        r0 = $const, r0
>>        r0 = r_worse, r0
>> that can save 2 cycles for Atom since first 2 instructions can be hoisted up.
>> I could not find better way for coding it.
>
> If it is important to put adding of const before adding of the
> register, then you can emit similar sequence for other cases, too.
> Something like following:
>
> --cut here--
> ...
>         {
>           if (regno0 == regno1)
>             tmp = parts.index;
>           else if (regno0 == regno2)
>             tmp = parts.base;
>           else
>             {
>               rtx tmp1;
>
>               /* regno1: base, regno2: index  */
>               if (find_nearest_reg_def (insn, regno1, regno2))
>                 tmp1 = parts.index, tmp = parts.base;
>               else
>                 tmp1 = parts.base, tmp = parts.index;
>
>               emit_insn (gen_rtx_SET (VOIDmode, target, tmp1));
>             }
>
>           if (parts.disp && parts.disp != const0_rtx)
>             ix86_emit_binop (PLUS, mode, target, parts.disp);
>           ix86_emit_binop (PLUS, mode, target, tmp);
>           return;
>         }
> --cut here--
>
>>>> I prepared new patch and ChangeLog. Testing of x32 is in progress.
>
> You didn't fix vertical spaces and tab issues in new patch.
>
> Uros.
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