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Re: [avr-gcc-list] Register Allocation -fnew-ra

From: Rolf Ebert
Subject: Re: [avr-gcc-list] Register Allocation -fnew-ra
Date: Fri, 25 Aug 2006 20:42:13 +0200
User-agent: Opera M2/8.54 (Win32, build 7730)

Am Tue, 22 Aug 2006 20:56:55 +0200 schrieb Eric Weddington <address@hidden>:

However, hunting around the web, I came across this new option -fnew-
ra that uses a different register allocation algorithm.
I am able to successfully build my application with this option.
But it looks like this option is not supported in the newer versions
of gcc.
Is there any reason for removing -fnew-ra option or is avr-gcc 4.0
using -fnew-ra as a default option now ?

Yes. -fnew-ra never worked properly in the first place and hence was removed for good. Please do not use this option.

It never worked properly on Intel x86, it worked quite well on AVRs most of the time. It produces considerably better code than the std RA for AVR. But be careful and completely review the generatd code. I once had a case when new-ra generated wrong code! In the end, follow Eric's advice and don't use it.


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