JDK-8347489 : RISC-V: Misaligned memory access with COH
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 25
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • OS: linux
  • CPU: riscv
  • Submitted: 2025-01-12
  • Updated: 2025-03-12
  • Resolved: 2025-02-04
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JDK 25
25 b09Fixed
Related Reports
Causes :  
JDK-8351839 - RISC-V: Fix base offset calculation introduced in JDK-8347489
Causes :  
JDK-8349428 - RISC-V: "bad alignment" with -XX:-AvoidUnalignedAccesses after JDK-8347489
Relates :  
JDK-8305895 - Implement JEP 450: Compact Object Headers (Experimental)
Relates :  
JDK-8328404 - RISC-V: Fix potential crash in C2_MacroAssembler::arrays_equals
Relates :  
JDK-8291550 - RISC-V: jdk uses misaligned memory access when AvoidUnalignedAccess enabled
Relates :  
JDK-8310268 - RISC-V: misaligned memory access in String.Compare intrinsic
Description
We have different base_offset (4 bytes instead of 8 bytes) with COH. This causes misaligned memory accesses for several instrinsics like String.Compare.
The reason is that we process 8 bytes starting at the first array element for each iteration in the main loop. As a result, we have performance regressions
on platform with slow misaligned memory accesses like Unmatched and Premier P550 SBCs.
Comments
Changeset: e91a6ec4 Branch: master Author: Fei Yang <fyang@openjdk.org> Date: 2025-02-04 14:03:07 +0000 URL: https://git.openjdk.org/jdk/commit/e91a6ec49c80ea53bb6f1eb43c924f188803de7e
04-02-2025
A pull request was submitted for review. Branch: master URL: https://git.openjdk.org/jdk/pull/23053 Date: 2025-01-12 03:45:45 +0000
14-01-2025