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Re: query regarding ivopts.
- From: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- To: Ramana Radhakrishnan <ramana dot radhakrishnan at celunite dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Wed, 19 Jul 2006 17:09:49 +0200
- Subject: Re: query regarding ivopts.
Hello,
> I am upgrading a port from 3.4.5 to 4.1.x .In course of this I see some
> regressions in terms of performance in memcpy . I have narrowed down the test
> case to the function below.
>
> ivopts generates ivtmps for each of the address calculations as shown in the
> attached log instead of coalescing them into accesses off a single base .
>
> I have constant offset based indexed addressing available. 3.4.x works just fine
> and transforms these into accesses off a single base.
>
> >From the little I understand of the way ivopts works- I assume this has to do
> with costs from my backend. I tweaked TARGET_ADDRESS_COST to return 0 always as
> well as specifically for POST_INC, POST_DEC and friends , but this did not help .
>
> Any suggestions would be great ! Thanks for your time .
this is a bug in ivopts, the costs have nothing to do with it. It
appears to be fixed in 4.2 (I cannot reproduce it with your example
there).
Zdenek