[Linux-ia64] IA64 software pipelining

["dai yiyang" <daiyiyang@hotmail.com>]

Hi all,

   I am trying to test the software pipelining with the following code ,
----------------------------------
int swp(int m,int *a,int *b){
        int i;
#pragma swp
        for (i=0; i<m ; i++)
        {
                    b[i]=a[i]+1;

         }
        return i;
}
------------------------------------
I expect , for better performence , the code should be compiled somewhat 
like this:
------------------------
      mov ar.lc=r32
      mov ar.ec=4
      mov pr.rot=0x1000
loop:
(p16) ld8 r35=[r9],8
(p18) add r37=r36,r0,1
(p19) st8 [r6]=r38,8
      br.ctop loop;;
-------------------------
but it seems the Intel compiler7.1 can not produce software pipelining for 
this code like what I expected .
with -opt_report_file option , I got such tip:
-----------------------------

Swp report for loop at line 6 in swp in file swp.c

         Modulo scheduling failed. Most likely, this was
         caused by loop-carried memory dependences.

         Following are the loop-carried memory dependence edges:
         Store  at line     6 --> Load   at line     6

-----------------------------
any advice ?

Regards,
Yiyang



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