On 2023/06/01 23:20, Max Filippov wrote:
> On Wed, May 31, 2023 at 11:01 PM Takayuki 'January June' Suwa
> <jjsuwa_sys3...@yahoo.co.jp> wrote:
>> More optimized than the default RTL generation.
>>
>> gcc/ChangeLog:
>>
>> * config/xtensa/xtensa.md (adddi3, subdi3):
>> New RTL generation patterns implemented according to the instruc-
>> tion idioms described in the Xtensa ISA reference manual (p. 600).
>> ---
>> gcc/config/xtensa/xtensa.md | 52 +++++++++++++++++++++++++++++++++++++
>> 1 file changed, 52 insertions(+)
>>
>> diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
>> index eda1353894b..21afa747e89 100644
>> --- a/gcc/config/xtensa/xtensa.md
>> +++ b/gcc/config/xtensa/xtensa.md
>> @@ -190,6 +190,35 @@
>> (set_attr "mode" "SI")
>> (set_attr "length" "3")])
>>
>> +(define_expand "adddi3"
>> + [(set (match_operand:DI 0 "register_operand")
>> + (plus:DI (match_operand:DI 1 "register_operand")
>> + (match_operand:DI 2 "register_operand")))]
>> + ""
>> +{
>> + rtx lo_dest, hi_dest, lo_op0, hi_op0, lo_op1, hi_op1;
>> + rtx_code_label *label;
>> + if (rtx_equal_p (operands[0], operands[1])
>> + || rtx_equal_p (operands[0], operands[2])
>
>> + || ! REG_P (operands[1]) || ! REG_P (operands[2]))
>
> I wonder if these additional conditions are necessary, given that
> the operands have the "register_operand" predicates?
>
See register_operand() in gcc/recog.cc.
In fact, I've encountered several operands that satisfy the
register_operand predicate but result in REG_P() being false.
