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Re: wish: optimize (x > 0.) floating point comparison.
- To: yotam_medini at avanticorp dot com, rlk at tiac dot net
- Subject: Re: wish: optimize (x > 0.) floating point comparison.
- From: N8TM at aol dot com
- Date: Wed, 23 Sep 1998 23:49:02 EDT
- Cc: egcs at cygnus dot com
In a message dated 9/23/98 2:37:10 PM Pacific Daylight Time,
yotam@avanticorp.com writes:
> I wonder if there are primitive FPU compare instructions with (+/- 0.0)
> with a single operand.
There have been architectures which kept the positive and zero condition flags
automatically set in accordance with the last changed floating point register,
but this doesn't seem to be too useful now that most CPU's have multiple
register pipelined operations and out-of-order execution. Architectures which
keep a "register" which always shows as containing zero provide the ability to
compare with zero without having to find a zero variable datum.