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Re: PATCH: PR target/44588: Very inefficient 8bit mod/div
On Wed, Jun 23, 2010 at 12:36 PM, Paolo Bonzini <bonzini@gnu.org> wrote:
> On 06/23/2010 09:35 PM, H.J. Lu wrote:
>>
>> On Wed, Jun 23, 2010 at 12:16 PM, Paolo Bonzini<bonzini@gnu.org> ?wrote:
>>>
>>> On 06/23/2010 08:24 PM, H.J. Lu wrote:
>>>>
>>>> ?[(set (match_operand:HI 0 "register_operand" "=a")
>>>> ? ? ? ? (div:HI
>>>> ? ? ? ? ? (match_operand:HI 1 "register_operand" "0")
>>>> ? ? ? ? ? (match_operand:QI 2 "nonimmediate_operand" "qm")))
>>>> ? ?(clobber (reg:CC FLAGS_REG))]
>>>
>>> Maybe this:
>>>
>>> [(set (match_operand:QI 0 "register_operand" "=a")
>>> ? (subreg:QI
>>> ? ?(div:HI
>>> ? ? (match_operand:HI 1 "register_operand" "0")
>>> ? ? (match_operand:QI 2 "nonimmediate_operand" "qm")) 0))
>>> ?(clobber (reg:CC FLAGS_REG))]
>>>
>>
>> It doesn't make a big difference since only lower 8bit
>> is set by it.
>
> For full divmod you have to shift mod and ior of course. ?I understood that
> you were talking of *<u>divqi3.
>
I can't do shift/ior on QI output from *<u>divqi3. I have
;; Divide AX by r/m8, with result stored in
;; AL <- Quotient
;; AH <- Remainder
(define_insn "*<u>divqi3"
[(set (match_operand:QI 0 "register_operand" "=a")
(any_div:QI
(match_operand:HI 1 "register_operand" "0")
(match_operand:QI 2 "nonimmediate_operand" "qm")))
(clobber (reg:CC FLAGS_REG))]
"TARGET_QIMODE_MATH"
"<sgnprefix>div{b}\t%2"
[(set_attr "type" "idiv")
(set_attr "mode" "QI")])
and use
;; Used to extract remainder from AH by 8bit divmod. Use unspec so
;; that we can extract it from AL.
(define_insn "*movqi_extzh"
[(set (match_operand:QI 0 "nonimmediate_operand" "=Qm,?R")
(unspec:QI [(match_operand 1 "register_operand" "Q,Q")]
UNSPEC_MOVQI_EXTZH))]
to extract it from AL
--
H.J.