Supporting an instruction in the back-end - II

Supporting an instruction in the back-end - II

[Mohamed Shafi]

Hello all,

Will it be possible to write a pattern in the md file to support
setting/clearing a bit of a particular register?
The instructions are as follows:

clrb Rx, bitNo
setb Rx, bitNo

Could you point me to the back-ends that has support for this kind of
instructions?

Thanks for your time.

Regards,
Shafi.

RE: Supporting an instruction in the back-end - II

[Dave Korn]

Mohamed Shafi wrote on 14 May 2008 05:49:

> Hello all,
> 
> Will it be possible to write a pattern in the md file to support
> setting/clearing a bit of a particular register?
> The instructions are as follows:
> 
> clrb Rx, bitNo
> setb Rx, bitNo
> 
> Could you point me to the back-ends that has support for this kind of
> instructions?

  m68k has that kind of insn, you could take a look there.  It's probably
represented by some canonical rtl form for the full expression such as

(set (dest) 
     (andMM3 (dest) 
             (not (lshift (const_int 1) 
                          (bitNo)))))


and likewise for setb.
  


    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....

Re: Supporting an instruction in the back-end - II

[Michael Meissner]

On Wed, May 14, 2008 at 10:18:56AM +0530, Mohamed Shafi wrote:
> Hello all,
> 
> Will it be possible to write a pattern in the md file to support
> setting/clearing a bit of a particular register?
> The instructions are as follows:
> 
> clrb Rx, bitNo
> setb Rx, bitNo
> 
> Could you point me to the back-ends that has support for this kind of
> instructions?

The standard name to extract a bit field is 'extv' (for sign extended
extraction), and 'extzv' (for zero extended extraction).  The standard to set a
bit field is 'insv'.  There are 18 different ports that support 'extv' or
'extzv' in some fashion, and 20 different ports that support 'insv'.

-- 
Michael Meissner, AMD
90 Central Street, MS 83-29, Boxborough, MA, 01719, USA
michael.meissner@amd.com