Re: Is (set (subreg:SI (reg:HI) 0) (const_int)) valid rtx?

[qinfeng dot zhang at philips dot com]

whether the rtx is valid depends on the target machine, and the phase that the rtx located in compiling progress.



                                                                                                                                                                                                               
                                                                                                                                                                                                               
                                                   To:   gcc@gcc.gnu.org                                                                                                                                       
                                                   cc:   (bcc: Qinfeng Zhang/SHA/RESEARCH/PHILIPS)                                                                                                             
                                                   Subject:    Is (set (subreg:SI (reg:HI) 0) (const_int)) valid rtx?                                                                                          
                                                                                                                                                                                                               
               Kazu Hirata                         Classification:                                                                                                                                             
               <kazu@cs.umass.edu>                                                                                                                                                                             
                                                                                                                                                                                                               
               Sent by:                                                                                                                                                                                        
               gcc-owner@gcc.gnu.org                                                                                                                                                                           
                                                                                                                                                                                                               
               2003-06-02 19:53                                                                                                                                                                                
                                                                                                                                                                                                               
                                                                                                                                                                                                               




Hi,

Is the following valid rtx?

  (set (subreg:SI (reg:HI ...) 0)
       (const_int ...))

Here (reg:HI ...) is a pseudo register.  If this is valid, is the
register allocator supposed to allocate an SImode hard register for
(subreg:SI (reg:HI) 0)?  Or should this be canonicalized to the
following?

  (set (reg:HI ...)
       (const_int ...))

Thanks,

Kazu Hirata