Path: utzoo!attcan!telly!lethe!torsqnt!jarvis.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!rice!sun-spots-request
From: rwl@umree.ee.umr.edu (Wayne Little)
Newsgroups: comp.sys.sun
Subject: 68881 Floating Point Speed Increase on Sun 3/60
Keywords: Miscellaneous
Message-ID: <1560@brazos.Rice.edu>
Date: 21 Sep 89 17:09:08 GMT
Sender: root@rice.edu
Organization: Sun-Spots
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X-Sun-Spots-Digest: Volume 8, Issue 126, message 9 of 15

One of the professors here at UMR discovered that he gained a 5 times
performance increase on some of his floating point intensive code with
complex numbers by using in-line expansion.

The problem was with the *humongous* amount of stack traffic that was
being generated by the 68881 coprocessor calls.

The fix is to designate the inline expansion library for the 68881 on the
compile line - 
e.g.
f77 -c -f68881 code.c -O code /usr/lib/68881/libm.il

The problem and solution are described in detail in section G
(Assembly-Level In-line Expansion) of Sun's Floating-Point Programmer's
Guide, pp. 105-113.

I hope this will be of help to others.

-- Wayne Little      Internet: rwl@ee.umr.edu      UUCP: uunet!umree!rwl
Phone: (314) 341-4546  USPS: Univ. of Missouri-Rolla, EE Dept., Rolla, MO 65401