A prototype loop reverser for the scalarizer

[Paul Thomas]

Steven and Daniel Berlin,

Thanks for the replies:

I fold everything except the negate_expression - I'll make it so...

>> On Sunday 08 October 2006 13:31, Paul Thomas wrote:
>> > I do not seem able to make |ftree-loop-linear do loop revresal for me.
>> > Should this not effect the same transformation, or have I 
>> misunderstood
>> > something?
>>
>> IRIC, loop reversal is not yet implemented in the framework of
>> -ftree-loop-linear optimizations.  Dan Berlin knows more about that,
>> I suppose.
>>
>
> It is implemented, in terms of "if you tell it to reverse a loop, it
> will". None of the heuristics tell it to reverse a loop right now,
> however. :)

OK - I was looking at loop swapping in the scalarizer, to minimise 
temporary size, too.  Paul and Steven had left one patch of code #if 
zeroed out that should do this.  Beyond that, I was sketching out some 
ideas for some rudimentary loop optimization in ordinary, run-of 
-the-mill fortran do loops.  Is this worth contemplating, or will the 
gcc infrastructure be in place on a shortish time scale?

Regards

Paul