8348261: assert(n->is_Mem()) failed: memory node required #23938

vnkozlov · 2025-03-07T00:44:44Z

Add missing check for StrInflatedCopy intrinsic in C2 Escape Analysis.

Very rare case since we not usually use Latin1.inflate(). In failing case we inline both paths in String.getBytes() and eliminate `TreeMap$EntryIterator allocation:

        # java.lang.String::getBytes @ bci:40 (line 4812) L[0]=rsp + #64 L[1]=rsp + #132 L[2]=rsp + #120 L[3]=rsp + #124 STK[0]=rsp + #128 STK[1]=#0 STK[2]=rsp + #132 STK[3]=rsp + #120 STK[4]=rsp + #164
        # java.lang.AbstractStringBuilder::putStringAt @ bci:15 (line 1754) L[0]=rsp + #0 L[1]=rsp + #120 L[2]=rsp + #64
        # java.lang.AbstractStringBuilder::append @ bci:30 (line 592) L[0]=rsp + #0 L[1]=rsp + #64 L[2]=rsp + #28
        # java.lang.StringBuilder::append @ bci:2 (line 179) L[0]=rsp + #0 L[1]=rsp + #64
        # java.lang.StringBuilder::append @ bci:5 (line 173) L[0]=rsp + #0 L[1]=rsp + #32
        # sun.util.locale.LocaleExtensions::toID @ bci:100 (line 206) L[0]=RBP L[1]=rsp + #0 L[2]=rsp + #8 L[3]=#ScObj0 L[4]=rsp + #16 L[5]=rsp + #24 L[6]=rsp + #32
        # ScObj0 java/util/TreeMap$EntryIterator={ [expectedModCount :0]=rsp + #140, [next :1]=rsp + #176, [lastReturned :2]=rsp + #16, [this$0 :3]=rsp + #168 }

Unfortunately I was not able to create standalone test - it seems requires very particular frequencies of executed paths and used features/flags. The fix was verified with compilation replay file from the bug report.

I am running testing and will let you know results.

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Issue

JDK-8348261: assert(n->is_Mem()) failed: memory node required (Bug - P3)

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Christian Hagedorn (@chhagedorn - Reviewer)
Emanuel Peter (@eme64 - Reviewer)

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bridgekeeper · 2025-03-07T00:45:09Z

👋 Welcome back kvn! 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 · 2025-03-07T00:45:15Z

@vnkozlov 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:

8348261: assert(n->is_Mem()) failed: memory node required

Reviewed-by: chagedorn, epeter

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At the time when this comment was updated there had been 2 new commits pushed to the master branch:

4066f33: 8350565: NMT: remaining memory flag/type to be replaced with memory tag
7314efc: 8351377: Fix the ProblemList for com/sun/management/OperatingSystemMXBean cpuLoad tests on AIX

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openjdk · 2025-03-07T00:45:45Z

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

hotspot-compiler

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

mlbridge · 2025-03-07T00:49:30Z

Webrevs

00: Full (7b83d5d0)

chhagedorn

Looks good to me!

eme64

Looks reasonable.

Is there maybe some kind of stress-flag we could develop? Because you are saying the reproduction depends on some specific probabilities.

eme64 · 2025-03-07T09:13:33Z

src/hotspot/share/opto/escape.cpp

    } else if (n->Opcode() == Op_StrCompressedCopy ||
               n->Opcode() == Op_EncodeISOArray) {
      // get the memory projection
      n = n->find_out_with(Op_SCMemProj);
      assert(n != nullptr && n->Opcode() == Op_SCMemProj, "memory projection required");
    } else {
+#ifdef ASSERT
+      if (!n->is_Mem()) {


Would it make sense to turn this into a product check? Could we bail-out gracefully at this point?

For first question - may be but we hit it first time since JDK 9. I think we should balance what is really needs to be checked in product and what can be done in debug VM. For this case I think checking in debug is fine.
For second question - not from EA but we can from compilation. We are in split_unique_types() where we start modifying graph already.

vnkozlov · 2025-03-07T18:48:14Z

Thank you, Christian and Emanuel for reviews

vnkozlov · 2025-03-07T19:13:44Z

Looks reasonable.

Is there maybe some kind of stress-flag we could develop? Because you are saying the reproduction depends on some specific probabilities.

I think stressing flag -XX:+StressUnstableIfTraps added by Tobias may help here.

vnkozlov · 2025-03-07T19:17:52Z

My testing tier1-5, xcomp and stress passed without new failures.

vnkozlov · 2025-03-07T19:17:59Z

/integrate

openjdk · 2025-03-07T19:19:04Z

Going to push as commit f6a8db2.
Since your change was applied there have been 6 commits pushed to the master branch:

5cd4fe6: 8348309: MultiNST tests need more debugging and timing
7c22b81: 8350811: [JMH] test foreign.StrLenTest failed with StringIndexOutOfBoundsException for size=451
54fe643: 8347433: Deprecate XML interchange in java.management/javax/management/modelmbean/DescriptorSupport for removal
155697f: 8349623: [ASAN] Gtest os_linux.glibc_mallinfo_wrapper_vm fails
4066f33: 8350565: NMT: remaining memory flag/type to be replaced with memory tag
7314efc: 8351377: Fix the ProblemList for com/sun/management/OperatingSystemMXBean cpuLoad tests on AIX

Your commit was automatically rebased without conflicts.

openjdk · 2025-03-07T19:19:11Z

@vnkozlov Pushed as commit f6a8db2.

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

assert(n->is_Mem()) failed: memory node required

7b83d5d

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vnkozlov deleted the 8348261 branch March 7, 2025 19:19

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