Even if there's no actual performance difference for these instructions,
wouldn't the "not setting the CC" possibly improve the pipeline, since
the hardware knows the next conditional branch does not have to wait for
this instruction to be evaluated for affecting the CC?
Gary
Gary Weinhold
Senior Application Architect
DATAKINETICS | Data Performance & Optimization
Phone +1.613.523.5500 x216
Email: [email protected]
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On 2016-04-02 12:43, Steve Smith wrote:
Very much interesting! Thank-you!
Maybe this will settle the question of whether XR, SR, SLR, LHI, or LA
is the fastest way to clear a register. Spoiler alert:
All the same (and they're all optimized), except the latter two don't
set the CC, and there's a subtle hint that might be a hundredth of a
picosecond* better.
*Don't know the fractional prefixes beyond pico... besides I just made
that up.
sas
On 3/30/2016 15:40, Jim Mulder wrote:
This may be of interest to some of you:
https://www.ibm.com/developerworks/community/forums/html/topic?id=5cf34211-c8e6-4747-a8c2-f8ff7379150b
Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY
