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Re: ARM patch: Reduce code duplication for Thumb2 move patterns


On Sat, 2010-07-31 at 15:50 +0200, Bernd Schmidt wrote:
> On 07/31/2010 03:16 PM, Richard Earnshaw wrote:
> > On Thu, 2010-07-08 at 01:08 +0100, Bernd Schmidt wrote:
> >> There are many patterns in thumb2.md which are duplicated with only
> >> minor changes from their ARM equivalents.  This patch removes some of
> >> this duplication.
> >>
> >> There's one functional change: the ARM movdi pattern disallows the
> >> mem->mem move case while the Thumb2 one does not; I assumed that the
> >> ARM
> >> version was more desirable.
> 
> > This is OK.  
> 
> Thanks!
> 
> > We need to watch out, when merging patterns in this way that we don't
> > increase the length calculations too much (ideally not at all).  It's
> > safe, but in the long run is likely to lead to sub-optimal branch and
> > literal pool generation.
> 
> I think I checked all the patterns - did you see one where the lengths
> were different?

Not in this patch, but the implication of your message was that there
might be more patches like this one to come.  I'm happy to see the
merging, but just wanted to point out that keeping the size information
accurate was important.

R.


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