JDK-8371385 : compiler/escapeAnalysis/TestRematerializeObjects.java fails in case of -XX:-UseUnalignedAccesses
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 26
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2025-11-06
  • Updated: 2025-12-17
  • Resolved: 2025-11-07
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JDK 25 JDK 26
25.0.3Fixed 26 b24Fixed
Related Reports
Causes :  
JDK-8370405 - C2: mismatched store from MergeStores wrongly scalarized in allocation elimination
Description
Execute on platforms where UseUnalignedAccesses is false:

$ make test TEST="compiler/escapeAnalysis/TestRematerializeObjects.java"

Two IR rules failed under -XX:-EliminateAllocations on platforms with -XX:-UseUnalignedAccesses.
These are expecting MergeStores to emit StoreL or StoreI. But the enablement of MergeStores depends
on flag UseUnalignedAccesses [1]. So we need to add that condition to applyIf of the two IR rules.

[1] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/memnode.cpp#L3455
Comments
A pull request was submitted for review. Branch: master URL: https://git.openjdk.org/jdk25u-dev/pull/82 Date: 2025-12-15 00:34:48 +0000
15-12-2025
[jdk25u-fix-request] Approval Request from Fei Yang Same issue is there after JDK-8370405 is backported to jdk25u-dev repo and could always be reproduced by running this jtreg test with fastdebug build on linux-riscv64 platform. Risk is low as this is a test-only change. Verified with the same test fastdebug build on linux-riscv64 platform.
15-12-2025
Changeset: 59d23095 Branch: master Author: Fei Yang <fyang@openjdk.org> Date: 2025-11-07 10:10:14 +0000 URL: https://git.openjdk.org/jdk/commit/59d23095789bbb6d4e466bcbeb82089b17d78eae
07-11-2025
ILW = IR test failure with unaligned accesses, only machines that have this set to false, no workaround other than enforcing alignment = MLH = P4
06-11-2025
A pull request was submitted for review. Branch: master URL: https://git.openjdk.org/jdk/pull/28171 Date: 2025-11-06 03:11:14 +0000
06-11-2025