JEP draft: Improve performance of String and Array operations on AArch64

OwnerDmitrij Pochepko
StatusClosed / Withdrawn
Componenthotspot / compiler
Discussionhotspot dash compiler dash dev at openjdk dot java dot net
Reviewed byMikael Vidstedt, Vladimir Kozlov
Endorsed byMikael Vidstedt
Created2017/10/10 12:22
Updated2017/11/16 15:18


Improve the performance of AArch64 OpenJDK port intrinsics for operations with lots of load/store operations, such as String and Array intrinsics.



Specialized CPU architecture-specific code patterns improve the performance of user applications and benchmarks.


Intrinsics are used to leverage CPU architecture-specific assembly code which gets executed instead of generic Java code for a given method to improve performance. While most of the intrinsics are already implemented in AArch64 OpenJDK port, the current implementation of some intrinsics may not be optimal. Specifically, some intrinsics for AArch64 architectures may benefit from software prefetching instructions, memory address alignment, instructions placement for multi-piplining CPUs, replacement of certain instruction patterns with faster ones or using SIMD instructions.

This includes (but is not limited to) such typical operations as String::compareTo, String::indexOf, StringCoding::hasNegatives, Arrays::equals, StringUTF16::compress, StringLatin1::inflate and checksum calculations.

Depending on the intrinsic algorithm, most common intrinsic use case, and CPU specifics the following changes may be considered:


Risks and Assumptions