JDK-8149080 : AArch64: Recognize disjoint array copy in stub code
- Type: Enhancement
- Component: hotspot
- Sub-Component: compiler
- Affected Version: 9
- Priority: P4
- Status: Resolved
- Resolution: Fixed
- OS: generic
- CPU: aarch64
- Submitted: 2016-02-05
- Updated: 2021-02-01
- Resolved: 2016-02-09
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| JDK 9 | Other |
|---|---|
9 b107Fixed  |
openjdk8u292Fixed |
Related Reports
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Relates :
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Description
Arraycopy without overlap can safely perform optimizations like SIMD copy (load any values in src before writing any values in dest is legal for none-overlap array copy).
For compile time unknown array copy, stub code will check if arraycopy src and dest array overlap, if not overlap, perform faster none-overlap array copy.
In current aarch64 implementation, stub code check only if dest below src, this doesn���t cover cases dest above src but still not overlap case (as X86 did both tests).
__ cmp(d, s);
__ br(Assembler::LS, nooverlap_target);