8297290: Use int indices to reference CDS archived primitive mirrors #11256

iklam · 2022-11-21T05:45:42Z

In CDS, when archived class metadata reference an object in the archive heap, it's usually done using an integer index, which can be passed to HeapShared::get_root(int) to retrieve the object. This way, we don't need to worry if the archive heap has been relocated. E.g.,

oop Klass::archived_java_mirror() {
  assert(has_archived_mirror_index(), "must have archived mirror");
  return HeapShared::get_root(_archived_mirror_index);
}

However, for the primitive mirror objects (in Universe::_mirrors[], which point to the java.lang.Class instances of the Java primitive types such as int, float, etc), we are still using a direct oop reference.

For consistency, we should change this code to use the same int indices as the rest of the system. This will also make it simpler to optimize the layout of the CDS archive heap (e.g., in JDK-8234679).

Testing: passed tiers 1-4

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JDK-8297290: Use int indices to reference CDS archived primitive mirrors

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Calvin Cheung (@calvinccheung - Reviewer)

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bridgekeeper · 2022-11-21T05:46:30Z

👋 Welcome back iklam! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2022-11-21T05:48:31Z

@iklam The following label will be automatically applied to this pull request:

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mlbridge · 2022-11-21T06:30:58Z

Webrevs

calvinccheung · 2022-11-22T00:01:58Z

src/hotspot/share/memory/universe.cpp

@@ -236,29 +234,38 @@ void Universe::metaspace_pointers_do(MetaspaceClosure* it) {
  _do_stack_walk_cache->metaspace_pointers_do(it);
 }

+#if INCLUDE_CDS_JAVA_HEAP
+void Universe::set_archived_mirror_index(BasicType t, int index) {


Is it called during dump time only?
If so, maybe add an assert?
assert(DumpSharedSpaces, "dump-time only");

Fixed as suggested.

ashu-mehra · 2022-11-22T20:30:41Z

src/hotspot/share/memory/universe.cpp

@@ -89,6 +89,9 @@ Klass* Universe::_typeArrayKlassObjs[T_LONG+1]        = { NULL /*, NULL...*/ };
 Klass* Universe::_objectArrayKlassObj                 = NULL;
 Klass* Universe::_fillerArrayKlassObj                 = NULL;
 OopHandle Universe::_mirrors[T_VOID+1];
+#if INCLUDE_CDS_JAVA_HEAP
+int Universe::_archived_mirror_indices[T_VOID+1];


a minor suggestion - I feel it would be better to name it as _archived_basic_type_mirror_indices as it only stores mirrors for primitive types. Same for the other functions accessing _archived_mirror_indices i.e. set_archived_mirror_index -> set_archived_basic_type_mirror_index and update_archived_mirrors -> update_archived_basic_type_mirrors.

I renamed the field/functions as you suggested. Now they are consistent with existing functions like Universe::initialize_basic_type_mirrors()

I think eventually they should be named to primitive_type_mirrors since we don't use them for the reference types. But there are a few functions that are unrelated to this RFE, so I'll probably do the renaming in a subsequent RFE.

ashu-mehra · 2022-11-23T15:58:29Z

lgtm, thanks for updating the field/function names.

calvinccheung

Updated changes look good.

openjdk · 2022-11-28T22:03:16Z

@iklam This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8297290: Use int indices to reference CDS archived primitive mirrors

Reviewed-by: ccheung

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At the time when this comment was updated there had been 69 new commits pushed to the master branch:

cdf9ed0: 8297528: java/io/File/TempDirDoesNotExist.java test failing on windows-x64
105d9d7: 8295351: java/lang/Float/Binary16Conversion.java fails with "Unexpected result of converting"
a80552e: 8236919: Refactor com.sun.tools.javac.main.CommandLine into a reusable module for other JDK tools
a249a52: 8296754: AutoCreateSharedArchive in JDK 20 is not compatible with JDK 19
405b188: 8297570: jdk/jfr/threading/TestDeepVirtualStackTrace.java fails with -XX:-UseTLAB
ba0a252: 8297717: Remove jdk/internal/misc/TerminatingThreadLocal/TestTerminatingThreadLocal.java from ProblemList
c05dc80: 8297660: x86: Redundant test+jump in C1 allocateArray
eff4c03: 8297343: TestStress*.java fail with "got different traces for the same seed"
6a856bc: 8297499: Parallel: Missing iteration over klass when marking objArrays/objArrayOops during Full GC
b80f5af: 8297309: Memory leak in ShenandoahFullGC
... and 59 more: https://git.openjdk.org/jdk/compare/260e4dcbfd8bdccdf332c2b6a07990cd14f6bcfb...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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iklam · 2022-11-30T05:32:32Z

Thanks @ashu-mehra and @calvinccheung for the review.
/integrate

openjdk · 2022-11-30T05:34:15Z

Going to push as commit c7a679f.
Since your change was applied there have been 101 commits pushed to the master branch:

37f613b: 8297676: DataBuffer.TYPE_SHORT/TYPE_FLOAT/TYPE_DOUBLE are not placeholders
87f00f4: 8296878: Document Filter attached to JPasswordField and setText("") is not cleared instead inserted characters replaced with unicode null characters
9ced2ea: 8297311: Improve exception message thrown by java.net.HostPortrange::toLowerCase(String s)
defe060: 8296905: Replace the native LCMS#getProfileID() method with the accessor
e10778a: 8297695: Fix typos in test/langtools files
0ce1827: 8294321: Fix typos in files under test/jdk/java, test/jdk/jdk, test/jdk/jni
e2d71c0: 8297481: Create a regression test for JDK-4424517
f4063a3: 8297210: Add a @sealedGraph tag to selected java.desktop classes
2084451: 8078471: Backspace does not work in JFileChooser with GTK L&F
7af6b4b: 8296012: jshell crashes on mismatched record pattern
... and 91 more: https://git.openjdk.org/jdk/compare/260e4dcbfd8bdccdf332c2b6a07990cd14f6bcfb...master

Your commit was automatically rebased without conflicts.

openjdk · 2022-11-30T05:34:37Z

@iklam Pushed as commit c7a679f.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

8297290: Simplify the storage for CDS archived primitive mirrors

60eb030

openjdk bot added the hotspot-runtime hotspot-runtime-dev@openjdk.org label Nov 21, 2022

fixed spaces

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openjdk bot added the rfr Pull request is ready for review label Nov 21, 2022

calvinccheung reviewed Nov 22, 2022

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iklam added 2 commits November 22, 2022 10:40

@calvinccheung comments

eb0d663

Merge branch 'master' into 8297290-simplify-cds-primitive-mirror-storage

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ashu-mehra reviewed Nov 22, 2022

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@ashu-mehra comments: rename *_mirror* to *basic_type_mirror*

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ashu-mehra approved these changes Nov 23, 2022

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calvinccheung approved these changes Nov 28, 2022

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8297290: Use int indices to reference CDS archived primitive mirrors #11256

8297290: Use int indices to reference CDS archived primitive mirrors #11256

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8297290: Use int indices to reference CDS archived primitive mirrors #11256

8297290: Use int indices to reference CDS archived primitive mirrors #11256

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