[tree-ssa] Removing redundant loads

[Daniel Berlin]

On Thursday, May 29, 2003, at 05:21  PM, Diego Novillo wrote:

> On Thu, 2003-05-29 at 17:13, Daniel Berlin wrote:
>> On Thursday, May 29, 2003, at 04:38  PM, law@redhat.com wrote:
>>
>>>
>>> I mentioned at the GCC summit, I had a nice one line patch which
>>> allowed
>>> tree-ssa to remove redundant loads at basically no cost.
>>
>>
>> And this patch rapes the ability of load PRE to work.
>> Sigh.
>>
> Well, as with anything done in the renaming pass, these tricks will 
> only
> catch total redundancies.  So, yes, it may hinder PRE.
It's not just PRE it'll hinder, of course.
It will hinder any load placement optimization.

>  But don't
> despair, nothing is written in stone here.
>
> What we should do is make these transformations conditional as any 
> other
> transformation.  Later on, when PRE is finished, we can start playing
> the flags game with SPEC or what-have-you.

PRE is of course, waiting on live range out-of-ssa stuff.