From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Sat, 19 Jun 1999 12:52:43 +0100
From: forsyth@caldo.demon.co.uk forsyth@caldo.demon.co.uk
Subject: [9fans] TAS
Topicbox-Message-UUID: 9872cfcc-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19990619115243.56T-kLz-57R7A6yTflmAlQvNotzyZYdAjXHW4T3hjKg@z>

>>architecture for example, it seems TAS maps onto a `swap' instruction,
>> ...
>>Why implement tas() as a function, rather than do what it does inline.

it needs to use an instruction that guarantees interlock (on a multiprocessor)
and i assume `swap' does that on the sparc.  the instruction needed will be
peculiar to an architecture, hence it's found in a platform-dependent
function separate from the portable code.  the linkers are in a position to
inline things if need be (and do actually do some code shuffling as it is,
though not perhaps in this case -- i haven't looked).