JDK-8340010 : Fix vectorization tests with compact headers
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 24
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • OS: generic
  • CPU: generic
  • Submitted: 2024-09-12
  • Updated: 2024-09-27
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tbdUnresolved
Related Reports
Blocks :  
JDK-8305895 - Implement JEP 450: Compact Object Headers (Experimental)
Description
In JDK-8305895, the following tests have some disabled sub-tests:

test/hotspot/jtreg/compiler/loopopts/superword/TestAlignVector.java
test/hotspot/jtreg/compiler/loopopts/superword/TestMulAddS2I.java

I think the issue with all of them is that vectorization in those scenarios only works when the operations inside the loop start at an array index that addresses an element at 8-byte-aligned offset.

We could either improve the tests to run with different loop indices, or -  even better - improve vectorization, if this is possible.
Comments
Other tests with disabled sub-tests in JDK-8305895: - test/hotspot/jtreg/compiler/loopopts/superword/TestSplitPacks.java
27-09-2024
ILW = Test failures due to missed vectorization opportunity/possible performance regression, two tests/multiple cases after JDK-8305895, no workaround = MLH = P4
13-09-2024