JDK-8340093 : C2 SuperWord: implement cost model
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 24
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2024-09-13
  • Updated: 2025-05-23
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Other
tbdUnresolved
Related Reports
Blocks :  
JDK-8349139 - C2: Div looses dependency on condition that guarantees divisor not zero in counted loop
Blocks :  
JDK-8347116 - C2 SuperWord: If-Conversion
Relates :  
JDK-8336000 - C2 SuperWord: report that 2-element reductions do not vectorize
Relates :  
JDK-8357530 - C2 SuperWord: Diagnostic flag AutoVectorizationOverrideProfitability
Relates :  
JDK-8307516 - C2 SuperWord: reconsider Reduction heuristic for UnorderedReduction
Sub Tasks
JDK-8346993 :  
C2 SuperWord: refactor to make more vector nodes available in VectorNode::make - Resolved
Description
This will improve the profitability of vectorizing reductions, and adding shuffle/pack/unpack operations.
Because vectorization is not always profitable, especially if we add more operations to the loop.

There may also be extra cost to subword conversion, see:
https://github.com/openjdk/jdk/pull/23413