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Re: speeding up parts of gcc by using ffs

From: Richard Henderson <rth at redhat dot com>
To: Andrew Pinski <pinskia at physics dot uc dot edu>
Cc: gcc-patches at gcc dot gnu dot org, gcc at gcc dot gnu dot org, apinski at apple dot com
Date: Wed, 8 Jan 2003 14:46:02 -0800
Subject: Re: speeding up parts of gcc by using ffs
References: <87ptraf9sp.fsf@egil.codesourcery.com> <11CFA879-22DE-11D7-8833-000393A6D2F2@physics.uc.edu>

On Tue, Jan 07, 2003 at 11:52:00PM -0800, Andrew Pinski wrote:
> +  if(temp1.ints.hi!=0)
> +    word = temp.ints.low;

This doesn't implement ffs.  You want

	if (temp1.ints.lo)
	  word = temp1.ints.lo;

And, really, I suspect that you don't want a union
at all.  Using a >> 32 should be good enough and it
won't punish 64-bit hosts.

r~

References:
- Re: speeding up parts of gcc by using ffs
  - From: Zack Weinberg
- Re: speeding up parts of gcc by using ffs
  - From: Andrew Pinski

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