JDK-8350468 : x86: Improve implementation of vectorized numberOfLeadingZeros for int and long
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 25
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2025-02-21
  • Updated: 2025-02-21
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tbdUnresolved
Related Reports
Relates :  
JDK-8349637 - Integer.numberOfLeadingZeros outputs incorrectly in certain cases
Description
Currently, the vectorized assembly for Long.numberOfLeadingZeros does not use the same floating point exponent trick that the integer variant uses, which emits fewer vector operations. Furthermore, the implementation of Integer.numberOfLeadingZeros could be improved to use fewer vector operations, as discussed here: https://github.com/openjdk/jdk/pull/23579#issuecomment-2661332497