From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joe Buck <jbuck@synopsys.com>
To: law@cygnus.com
Cc: toon@moene.indiv.nluug.nl, egcs@cygnus.com
Subject: Re: (really Fortran patches)
Date: Thu, 23 Oct 1997 12:18:00 -0000
Message-id: <199710231918.MAA22569@atrus.synopsys.com>
References: <8774.877629991@hurl.cygnus.com>
X-SW-Source: 1997-10/msg00989.html

> The USE variant didn't use fmpysub because it couldn't find an independent 
> fmpy and fsub to issue together -- fmpyadd/fmpysub was a poor man's
> way to increase FP performance back in 1991.  It's still useful on
> most PAs, except the PA8000 based machines.

Well, in digital logic you can convert a multiplier into a multiply-add or
multiply-subtract unit almost for free (almost no timing or area penalty),
and they are common operations, so it does make sense even in a RISC view
of the world.  It's common for very small DSP cores to have such
instruction for this reason.