Exploiting dual mode operation

[Leehod Baruch]

Hello,

Thank you for your message.

We see redundant sign extension removal as a partial 
redundancy problem. This will give us not only the redundant 
sign extensions, but also better placement for the 
remaining ones. As a result sign extension instructions 
may be moved and instructions that uses the highpart
may be replaced with others that doesn't use it.

This is not equivalent with live information for the highest 
part of the registers. 

Our approach will not require changes in the description file 
(which in our opinion is a major problem with your code) and will 
limit the changes to much fewer files.

Leehod and Mircea 






Joern Rennecke <joern.rennecke@superh.com>
21/04/2004 09:26 PM
 
        To:     Mircea Namolaru/Haifa/IBM@IBMIL
        cc:     gcc@gcc.gnu.org, Leehod Baruch/Haifa/IBM@IBMIL
        Subject:        Re: Exploiting dual mode operation


> We are working on an optimization for eliminating redundant sign 
extension
> instructions by making use of this duality. Currently this is done only 
in 
> very 
> simple cases.

I have already submitted a patch for this:
http://gcc.gnu.org/ml/gcc-patches/2004-01/msg03259.html

It is still waiting for review.