On Tue, 15 May 2012 20:07:52 +0000, Robert Prins wrote:

>maybe a 16-byte
>three-instruction sequence like
>
>003FC0  E310  DF10  0158  003120 | LY   r1,<a1:d7952:l4>(,r13,7952)
>003FC6  E300  1047  0015  003120 | LGH  r0,_shadow20(,r1,71)
>003FCC  4000  E064        003120 | STH  r0,_shadow20(,r14,100)
>
>is really faster than the simple 6-byte one-instruction sequence
>
>0026D4  D2 01 7 064 6 047  MVC   REPT_LINE.DATE.MONTH(2),REPT_LIST.DATE.MONTH

Not likely.

Address Generation Interlock (AGI) will cause the second instruction 
to stall until the address is available in R1.

In addition, instruction cracking will, under some circumstances, cause 
a z196 processor to execute a load and a store when a MVC instruction 
is executed.

-- 
Tom Marchant

----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN

Reply via email to