On Wed, Jun 23, 2010 at 12:50 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> 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
>

Here is a different approach.  It uses UNSPEC for 8bit divmod.
The generated code is the same.


-- 
H.J.
---
gcc/

2010-06-22  H.J. Lu  <hongjiu.lu@intel.com>

	PR target/44588
	* config/i386/i386.md (UNSPEC_DIVQI): New.
	(UNSPEC_UDIVQI): Likewise.
	(extend_code): Likewise.
	(extract_code): Likewise.
	(*movqi_extzv_3): Likewise.
	(*movqi_extzv_3_rex64): Likewise.
	(<u>divmodqi4): Likewise.
	(*divqi3): Likewise.
	(*udivqi3): Likewise.
	(<u>divqi3): Remvoved.

gcc/testsuite/

2010-06-22  H.J. Lu  <hongjiu.lu@intel.com>

	PR target/44588
	* gcc.target/i386/umod-1.c: New.
	* gcc.target/i386/umod-2.c: Likewise.
	* gcc.target/i386/umod-3.c: Likewise.