[Linux-ia64] Multimedia Instructions

From: Mattox, Dave <DMattox_at_UNITECH.COM>
Date: 2000-10-21 09:16:19
Couple questions for you all if you don't mind:

1. Is there a mailing list for information on just IA-64? A majority of my
issues deal with the architecture exclusively and I don't want to pollute
this mailing list. If anyone knows of one I would appreciate a link.

2. Does anyone know if the 10 clock cycle penalty for a multimedia
instruction result used in a different instruction type is just a quirk of
the Itanium Chip or will this most likely be carried into future IA-64
Chipsets? If this penalty is likely to disappear in future versions, I don't
mind coding it for a hit now.

The penalty I am talking about is a code segment such as:
mux1 r36 = r37, @rev;;   // mm instruction
add r38 = 5, r36		// 10 clock penalty for using result in a
different instruction type

It's interesting how the following is actually faster:
mux1 r36 = r37, @rev;;
nop;;
nop;;
nop;;
nop;;
add r38 = 5, r36

Thanks,
Dave Mattox
Received on Fri Oct 20 15:16:56 2000

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