JDK-8348568 : [lworld] Update Valhalla with UseCompactObjectHeaders for oop->klass load/stores
  • Type: Bug
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: repo-valhalla
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2025-01-24
  • Updated: 2025-02-25
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Other
repo-valhallaUnresolved
Related Reports
Relates :  
JDK-8348970 - [lworld] Runtime: Update Valhalla with UseCompactObjectHeaders for oop->klass load/stores
Relates :  
JDK-8305895 - Implement JEP 450: Compact Object Headers (Experimental)
Relates :  
JDK-8350630 - [lworld] ObjBufferAllocator::initialize fails with assert(has_klass_gap()) failed: precondition
Relates :  
JDK-8348972 - [lworld] C1/C2: Update Valhalla with UseCompactObjectHeaders for oop->klass load/stores
Sub Tasks
JDK-8348970 :  
[lworld] Runtime: Update Valhalla with UseCompactObjectHeaders for oop->klass load/stores - Open
JDK-8348972 :  
[lworld] C1/C2: Update Valhalla with UseCompactObjectHeaders for oop->klass load/stores - Open
Description
Repro: java -XX:+EnableValhalla -XX:+UnlockExperimentalVMOptions -XX:+UseCompactObjectHeaders -version

show certain Valhalla changes need updating to correctly load/store the object klass, e.g.

MacroAssembler::store_inline_type_fields_to_buf() calls to MacroAssembler::store_klass_gap need be conditional on UseCompactObjectHeaders
Comments
Reenable COH in make/autoconf/jdk-options.m4 "BUILD_CDS_ARCHIVE_COH" default to "auto" (was set "false" in jdk-24+24 merge commit), ie undo: https://github.com/openjdk/valhalla/pull/1337/commits/5c25d10152ab149b6c385f7aec8481c7c21db5b8 and ProblemList with this bug number (8348568)
29-01-2025