[gnu.gcc] 80?86 [ix]bts instructions--worth the pain?

ado@elsie.UUCP (Arthur David Olson) (06/07/89)

First off, apologies for introducing a technical (rather than political)
question into gnu.gcc (to which this article is cross-posted).

My boss has a Sun386i on which XV11R3 is running.  I'm wondering if changing
the "Purdue speedups" to make use of the 80386's "ibts" and "xbts" instructions
(by way of gcc's "asm" mechanism) is worthwhile--that is, whether the complex
instructions in question are just denser than the sequences of simpler
instructions they'd replace, or whether they're faster as well.  
Finding out beforehand seems wise, since making the whole business work will
require either getting the Sun or GNU assembler to recognize the "ibts" and
"xbts" instructions (and, in the case of a GNU-assembler-based solution, also
doing some fancy footwork to deal with the 386i's COFF-format libraries).

If you have any light to shed on the matter, I'd appreciate hearing from you
by electronic mail.
-- 
	Arthur David Olson    ado@ncifcrf.gov    ADO is a trademark of Ampex.