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About

Investigation of the 538.imagick benchmark from spec2017 shows that uses ceil/floor routines heavily.  While the Zfa extension can be used to optimize these calls into simple FP conversion instructions, it is believed that an alternate implementation based on just the F/D conversions can be implemented which will significantly improve performance on designs that do not implement Zfa.


LLVM already has this optimization in place.




Stakeholders/Partners

RISE:

Ventana: Jivan Hakobyan (under contract via RAU) – lead developer

Ventana: Jeff Law – general oversight

Rivos: ADLR – provided initial hint & data showing the extent of this problem


External:



Dependencies


Status

Development

COMPLETE


Development TimelineNA
Upstreaming

NOT STARTED


Upstream Version





Contacts

Jeff Law (Ventana)


Dependencies

None



Updates

 

  • An implementation borrowing heavily from LLVM is under evaluation.  This implementation implements more efficient versions of ceil, round, nearbyint, rint, etc
  • In addition to using existing conversions to implement those functions, the implementation also includes sign extension removal for cases where the ultimate result is a GPR
  • Expecting this to save 300-400 billion instructions for imagick benchmark.  Enough that we expect to see a measurable (perhaps double digit) improvement in the benchmark's overall performanc

  

  • Project reported as a priority for 1H2024


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