From: "Edward Jaffe" <[email protected]>
Sent: Saturday, 9 October 2010 2:09 AM
On 10/8/2010 7:51 AM, Blaicher, Chris wrote:
Yes, I use MVCL, TRT, CLCL and the rest of the millicoded instructions, I just
use them where appropriate.
The irony here is that IBM uses sampling of real workloads to determine which
instructions are used most. That knowledge helps them decide which instructions
should be given preferential performance treatment and which should not. So, if
an instruction isn't often used because it's slow, it will never get any
faster...
When an instruction like TRT or TR is not used, and
instead an explicit loop with CLI / IC, BCT etc are used,
such a philosophy will favor instructions like CLI / IC / BCT etc
because they appear to be used more often (esp. as those
instructions will almost certainly appear elsewhere in the program).
