I just read an article on LWN.net about the usage of self-modifying code
for selecting the optimum code for a given operation at run time. This
is probably not a highly portable technique, but Linux has definitions
for i386 and the amd64 archs, so that would cover the most common
scenarios.
This could be useful to provide different TAS implementations depending
on the actual system the code is running on.
The article is here:
http://lwn.net/SubscriberLink/164121/d88fddbb5606a938/
The i386 code is here:
http://lxr.linux.no/source/include/asm-i386/system.h#L288
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.