[PATCH] Optimize 32-bit sparc T1 multiply routines.

David Miller davem at davemloft.net
Wed Jan 9 04:43:40 CET 2013


From: Torbjorn Granlund <tg at gmplib.org>
Date: Sun, 06 Jan 2013 13:48:42 +0100

> Unfortunately, its submul_1 method will not work.  I cannot see
> how we can avoid an extra instruction for every limb.

BTW I noticed the following while researching and working on this
T4 stuff:

http://download.intel.com/embedded/processor/whitepaper/327831.pdf

Note that there are no subtract equivalents being added of these new
add-with-carry instructions.

I have also meanwhile spoken to some sparc chip folks and they made it
clear that they consider having not added subxccc a mistake and a bug
just like we do, and they will rectify this in a future cpu.

Anyways, just FYI...


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