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Re: PATCH: PR target/44588: Very inefficient 8bit mod/div

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.

Paolo

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