Re: modifications at gimple(SSA) level

[ranjith kumar <ranjit_kumar_b4u at yahoo dot co dot uk>]

Hi,
Below is a c program.
Gcc-4.1.2 is unable to produce vector code for it
because the induction varible(int i) decreases.
But if the (for)loop is modified  as
for(i=0;i<n;i++){...................}
gcc will produce vector code.

During the  autovectorization pass, the program will
be in SSA form.
My question is how to do the above transformation on
SSA form of a program??
Can anyone help me?
Thanks in advance.

******************************************************
 1 #include<stdio.h>
  2 int main()
  3 {
  4 int i,k;
  5 int a[100],b[100],n=80;
  6
  7
  8 for(i=n;i>0;i--)
  9 {
 10 a[i+1]=b[i+12]-3;
 11 b[i+1]=a[i+7]*5;
 12 }
 13
 14 printf("\n %d ",a[22]);
 15 }


*****************************************************






--- Anitha Boyapati <anithab@sankhya.com> wrote:

> 
> Hi,
> 
> 
> > Is it possible to modify the code at SSA level of
> a
> > program.
> 
>   Which code ? Being a little more precise can save
> lot of trouble
>   to others in repeatedly asking where/why/what/how
> or might even consider 
>   giving it a thought before throwing it away :)
> 
> > Modifications are like introducing a new variable
> and
> > assigning some value to it ......so on.
> > 
> > If so, in which file those functions are availble?
> > Thanks in advance.
> > 
> > 
> > 		
> >
>
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> 
> -- 
> Regards,
> Anitha B
> @S A N K H Y A
> 
> 



		
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