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RE: about LNO

To: "'Ziang Hu'" <hu@xxxxxxxxxxxxxxxxxxx>, "pro64-support@xxxxxxxxxxx" <pro64-support@xxxxxxxxxxx>
Subject: RE: about LNO
From: Peng Tu <tu@xxxxxxxxxxxxx>
Date: Tue, 12 Sep 2000 16:29:36 -0700
Organization: Tensilica Inc
Reply-to: "tu@xxxxxxxxxxxxx" <tu@xxxxxxxxxxxxx>
Sender: owner-pro64-support@xxxxxxxxxxx
For this C program, I don't see why it is beneficial to interchange
the loop because the inner loop is already stride-1 (C is row-major).

It does need an unroll-and-jam transformation to capture the reuse
of the outer loop though.  Maybe the LNO machine model is not up-to-date
with the IA64.

A useful flag to try for C program is -OPT:alias=restrict if the array is
an input parameter.

Peng.

On Tuesday, September 12, 2000 11:07 AM, Ziang Hu [SMTP:hu@xxxxxxxxxxxxxxxxxxx] 
wrote:
> 
> Hi, 
> 
> I tried to test the effect of LNO with Pro64. The code is as follows:
> 
>      ...     
>      for (i=0; i<1000; i++)
>         for (j=0; j<1000; j++)
>             a[i][j] = a[i][j] + a[i-1][j];
>      ...
> 
> With -O3, no loop interchange happened.
> 
> How about LNO with C programs ?
> 
> Thanks
> 
> Ziang

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