Try this on your hardware and post the results. Uncomment/Comment where
applicable.
BENCH CSECT
BENCH AMODE 31
SAVE (14,12)
LR R12,R15
USING BENCH,R12
L R4,=A(1*1000*1000*1000)
LTR R4,R4
J LOOP
*
LOOP DS 0D .LOOP START
* B NEXT .UNCONDICTIONAL
BE NEXT .CONDITIONAL
NEXT JCT R4,LOOP
RETURN (14,12)
YREGS ,
END
On 29/04/2016 9:35 PM, Windt, W.K.F. van der (Fred) wrote:
Here's the code.
I wrote a simple program - it tight loops 1 billion times
L R4,=A(1*1000*1000*1000)
LTR R4,R4
J LOOP
*
LOOP DS 0D .LOOP START
B NEXT
NEXT JCT R4,LOOP
The loop starts with a branch ... I tested it twice - when the CC is matched
(branch happens) and when it is not matched (falls through)
1. When the CC is matched and branching happens, CPU TIME=2.94 seconds
2. When the CC is not matched the code falls through, CPU TIME=1.69
seconds - a reduction of 42%
Uhm... I don't see any conditional branch at the start of the loop that
branches or falls through?
Fred!
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