JDK-8242449 : AArch64: r27 can be allocated in CompressedOops mode
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 8,11,14,15
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • OS: linux
  • CPU: arm
  • Submitted: 2020-04-09
  • Updated: 2024-02-06
  • Resolved: 2020-04-20
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JDK 15
15 b20Fixed
Related Reports
Relates :  
JDK-8249781 - AArch64: AOT compiled code crashes if C2 allocates r27
Relates :  
JDK-8233743 - AArch64: Make r27 conditionally allocatable
Description
It's based on https://bugs.openjdk.java.net/browse/JDK-8233743 , jvm can allocate r27 in compressed oops mode if heap base is zero.
Comments
Sorry, not suitable for 11u. Fairly high risk, marginal gain.
26-10-2021
Fix Request (11u): This optimization saves an aarch64 register in compressed oops mode. It requires JDK-8233743 as a prerequisite and JDK-8249781 as a follow-up. Original patch has been adjusted to use Universe::narrow_ptrs_base() instead of CompressedOops::ptrs_base() (no JDK-8223136) and for slightly different context (no JDK-8235385). PR: https://github.com/openjdk/jdk11u-dev/pull/137 Testing: tier1, tier2 (aarch64).
25-10-2021
URL: https://hg.openjdk.java.net/jdk/jdk/rev/aedc9bf21743 User: pli Date: 2020-04-20 09:51:03 +0000
20-04-2020
patch http://cr.openjdk.java.net/~wzhuo/8242449/webrev.01/ review thread https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2020-April/037846.html
20-04-2020
patch http://cr.openjdk.java.net/~wzhuo/8242449/webrev.00/
09-04-2020