JDK-8247307 : C2: Loop array fill stub routines are not called
- Type: Enhancement
- Component: hotspot
- Sub-Component: compiler
- Affected Version: 11,14,15
- Priority: P3
- Status: Resolved
- Resolution: Fixed
- OS: generic
- CPU: generic
- Submitted: 2020-06-10
- Updated: 2024-11-13
- Resolved: 2020-06-28
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| JDK 16 |
|---|
16 b04Fixed  |
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Description
C2 has a loop optimization phase called intrinsify_fill [1]. It recognizes the code pattern of Java array initialization in a loop and generates calls to some array fill stub routines for better performance and smaller code size. But in latest jdk master (14/15), the calls to array fill stubs are not generated. Generated code shows the array initialization loops are automatically unrolled and vectorized. If this phase works, methods of java.util.Arrays.fill() should be optimized as well. We should check why this doen't work and try to fix it if this phase. [1] http://hg.openjdk.java.net/jdk/jdk/file/f1f88e6fad02/src/hotspot/share/opto/loopTransform.cpp#l3421
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