8282218: C1: Missing side effects of dynamic class loading during constant linkage #7612

iwanowww · 2022-02-24T13:51:18Z

(The problem is similar to JDK-8282194, but with class loading this time.)

C1 handles unresolved constants by performing constant resolution at runtime and then putting the constant value into the generated code by patching it. But it treats the not-yet-resolved value as a pure constant without any side effects.

It's not the case for constants which trigger class loading using custom class loaders. (All non-String constants do that.)

There are no guarantees that there are no side effects during class loading, so C1 has to be conservative.

Proposed fix kills memory after accessing not-yet-loaded constant in the context of any non-trusted class loader.

Testing: hs-tier1 - hs-tier4

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Issue

JDK-8282218: C1: Missing side effects of dynamic class loading during constant linkage

Reviewers

Tobias Hartmann (@TobiHartmann - Reviewer) ⚠️ Review applies to bf442f0f
Vladimir Kozlov (@vnkozlov - Reviewer)

Reviewing

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Checkout this PR locally:
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$ git checkout pull/7612

Update a local copy of the PR:
$ git checkout pull/7612
$ git pull https://git.openjdk.java.net/jdk pull/7612/head

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Checkout this PR locally:
$ git pr checkout 7612

View PR using the GUI difftool:
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Download this PR as a diff file:
https://git.openjdk.java.net/jdk/pull/7612.diff

…stant linkage

bridgekeeper · 2022-02-24T13:52:59Z

👋 Welcome back vlivanov! 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 · 2022-02-24T13:55:47Z

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

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mlbridge · 2022-02-24T13:59:36Z

Webrevs

01: Full - Incremental (6f2cf416)
00: Full (bf442f0f)

vnkozlov · 2022-02-24T19:52:57Z

src/hotspot/share/ci/ciStreams.hpp

+           cur_bc() == Bytecodes::_ldc2_w, "not supported: %s", Bytecodes::name(cur_bc()));
+
+    int index = get_constant_pool_index();
+    constantTag tag = get_raw_pool_tag(index);


Looks like these lines are the same as in is_dynamic_constant(). Can you move them in separate method to avoid duplication?

Ok, I introduced a no-arg get_raw_pool_tag() helper method. Does it look better?

TobiHartmann

Looks good to me.

openjdk · 2022-02-25T07:56:01Z

@iwanowww 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:

8282218: C1: Missing side effects of dynamic class loading during constant linkage

Reviewed-by: thartmann, kvn

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 55 new commits pushed to the master branch:

d8f9686: 8286342: ProblemList compiler/c2/irTests/TestEnumFinalFold.java
bb52ea6: 8286263: compiler/c1/TestPinnedIntrinsics.java failed with "RuntimeException: testCurrentTimeMillis failed with -3"
5a1d8f7: 8285295: Need better testing for IdentityHashMap
080f3c5: 8286190: Add test to verify constant folding for Enum fields
1277f5d: 8286154: Fix 3rd party notices in test files
2dd4dfd: 8286291: G1: Remove unused segment allocator printouts
b9f4370: 8286189: G1: Change "wasted" memory to "unused" memory in reporting
c6eab98: 8285378: Remove unnecessary nop for C1 exception and deopt handler
3cdedf1: 8248863: Add search landing page to API documentation
fa1ca98: 8281429: PhiNode::Value() is too conservative for tripcount of CountedLoop
... and 45 more: https://git.openjdk.java.net/jdk/compare/efcd3d3a8fd19909ef21a07cc61613aad4dbe145...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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

bridgekeeper · 2022-03-25T14:15:00Z

@iwanowww This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

TobiHartmann · 2022-04-21T12:25:06Z

Comment to keep this open.

vnkozlov

Update looks good. Thanks!

iwanowww · 2022-05-06T23:08:29Z

Thanks for the reviews, Vladimir & Tobias.

/integrate

openjdk · 2022-05-06T23:09:38Z

Going to push as commit 5212535.
Since your change was applied there have been 55 commits pushed to the master branch:

d8f9686: 8286342: ProblemList compiler/c2/irTests/TestEnumFinalFold.java
bb52ea6: 8286263: compiler/c1/TestPinnedIntrinsics.java failed with "RuntimeException: testCurrentTimeMillis failed with -3"
5a1d8f7: 8285295: Need better testing for IdentityHashMap
080f3c5: 8286190: Add test to verify constant folding for Enum fields
1277f5d: 8286154: Fix 3rd party notices in test files
2dd4dfd: 8286291: G1: Remove unused segment allocator printouts
b9f4370: 8286189: G1: Change "wasted" memory to "unused" memory in reporting
c6eab98: 8285378: Remove unnecessary nop for C1 exception and deopt handler
3cdedf1: 8248863: Add search landing page to API documentation
fa1ca98: 8281429: PhiNode::Value() is too conservative for tripcount of CountedLoop
... and 45 more: https://git.openjdk.java.net/jdk/compare/efcd3d3a8fd19909ef21a07cc61613aad4dbe145...master

Your commit was automatically rebased without conflicts.

openjdk · 2022-05-06T23:09:53Z

@iwanowww Pushed as commit 5212535.

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

8282218: C1: Missing side effects of dynamic class loading during con…

bf442f0

…stant linkage

iwanowww marked this pull request as ready for review February 24, 2022 13:51

openjdk bot added the rfr Pull request is ready for review label Feb 24, 2022

openjdk bot added the hotspot-compiler hotspot-compiler-dev@openjdk.org label Feb 24, 2022

vnkozlov reviewed Feb 24, 2022

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TobiHartmann approved these changes Feb 25, 2022

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openjdk bot added the ready Pull request is ready to be integrated label Feb 25, 2022

iwanowww added 2 commits May 6, 2022 12:32

Merge branch 'master' into 8282218.c1.class_loading

026cdf4

helper method to access constant pool tag

6f2cf41

vnkozlov approved these changes May 6, 2022

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openjdk bot added the integrated Pull request has been integrated label May 6, 2022

openjdk bot closed this May 6, 2022

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels May 6, 2022

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