(fix): gate FrameType::isRawPointer on HotSpot#658
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The raw-pointer bci encoding (bit 30) only ever means "jmethodID slot replaced by a VMMethod*" on HotSpot. On OpenJ9, an unencoded, VM-supplied bci can coincidentally have bit 30 set, which was misread as our raw-pointer encoding and routed into JVMSupport::resolve(), which asserts/aborts for non-HotSpot VMs. Reproduced on Semeru 8.0.462/OpenJ9 via GetLineNumberTableLeakTest. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
TrueWhenBit30IsSet assumed isRawPointer() ignores VM kind; split into hotspot/non-hotspot cases now that it's gated on VM::isHotspot().
jbachorik
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CI Test ResultsRun: #29326785663 | Commit:
Status Overview
Legend: ✅ passed | ❌ failed | ⚪ skipped | 🚫 cancelled Summary: Total: 32 | Passed: 32 | Failed: 0 Updated: 2026-07-14 11:11:39 UTC |
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Benchmark Results (commit 552da8c)Pipeline: https://gitlab.ddbuild.io/DataDog/apm-reliability/benchmarking-platform/-/pipelines/124497089 Commit:
|
| Benchmark | JDK | Latest | Dev | Δ (dev vs latest) | Issues L/D |
|---|---|---|---|---|---|
| akka-uct | 21 | ✅ 10311 ms (21 iters) | ✅ 10141 ms (21 iters) | ≈ -1.6% (±10.3%) | — / — |
| finagle-chirper | 25 | ✅ 5418 ms (36 iters) | ✅ 5553 ms (35 iters) | ≈ +2.5% (±24.8%) | |
| fj-kmeans | 21 | ✅ 2725 ms (68 iters) | ✅ 2834 ms (66 iters) | 🔴 +4% | — / — |
| future-genetic | 21 | ✅ 2029 ms (91 iters) | ✅ 2098 ms (88 iters) | 🔴 +3.4% | — / — |
| future-genetic | 25 | ✅ 2032 ms (91 iters) | ✅ 1998 ms (93 iters) | ≈ -1.7% (±2.8%) | — / — |
| naive-bayes | 25 | ✅ 1021 ms (168 iters) | ✅ 1013 ms (168 iters) | ≈ -0.8% (±31.6%) | — / — |
| reactors | 21 | ✅ 16371 ms (15 iters) | ✅ 15634 ms (15 iters) | ≈ -4.5% (±7.1%) | — / — |
| reactors | 25 | ✅ 18447 ms (15 iters) | ✅ 18524 ms (15 iters) | ≈ +0.4% (±4.4%) | — / — |
Internal counter details (ddprof)
ddprof internal counters, latest / dev (✅ = 0, · = unavailable):
| Benchmark | JDK | Dropped rec | Dropped jvmti | Dropped trace | Skipped WC | AGCT fail | Unwind fail |
|---|---|---|---|---|---|---|---|
| akka-uct | 21 | ✅ / ✅ | ✅ / ✅ | 3 / 1 | 2110 / 1969 | ✅ / ✅ | ✅ / ✅ |
| akka-uct | 25 | ✅ / ✅ | ✅ / ✅ | 1 / ✅ | 2300 / 2239 | ✅ / ✅ | ✅ / ✅ |
| finagle-chirper | 25 | ✅ / ✅ | ✅ / ✅ | 1 / ✅ | 8440 / 8369 | ✅ / ✅ | ✅ / ✅ |
| fj-kmeans | 21 | ✅ / ✅ | ✅ / ✅ | 1 / 2 | 1270 / 1248 | ✅ / ✅ | ✅ / ✅ |
| fj-kmeans | 25 | ✅ / ✅ | ✅ / ✅ | 3 / ✅ | 1253 / ✅ | ✅ / ✅ | ✅ / ✅ |
| future-genetic | 21 | ✅ / ✅ | ✅ / ✅ | 2 / ✅ | 2949 / 3050 | ✅ / ✅ | ✅ / ✅ |
| future-genetic | 25 | ✅ / ✅ | ✅ / ✅ | 2 / 1 | 2803 / 2935 | ✅ / ✅ | ✅ / ✅ |
| naive-bayes | 25 | ✅ / ✅ | ✅ / ✅ | 4 / 5 | 3471 / 3507 | ✅ / ✅ | ✅ / ✅ |
| reactors | 21 | ✅ / ✅ | ✅ / ✅ | 2 / ✅ | 1624 / 1635 | ✅ / ✅ | ✅ / ✅ |
| reactors | 25 | ✅ / ✅ | ✅ / ✅ | ✅ / 3 | 1928 / 1862 | ✅ / ✅ | ✅ / ✅ |
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Pull request overview
This PR fixes an OpenJ9-specific misclassification by making FrameType::isRawPointer() treat bit-30 as the raw-pointer encoding only when running on HotSpot, preventing non-HotSpot BCIs with bit 30 set from being routed into HotSpot-only resolution paths.
Changes:
- Gate
FrameType::isRawPointer(int)onVM::isHotspot()inframe.h. - Update
frame_ut.cppto split the previous “bit 30 set” assertion into explicit HotSpot vs non-HotSpot tests (with a test-only accessor to toggleVM::_hotspot).
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| ddprof-lib/src/main/cpp/frame.h | Gates raw-pointer detection on VM::isHotspot() to avoid OpenJ9 false-positives. |
| ddprof-lib/src/test/cpp/frame_ut.cpp | Adjusts unit tests to validate both HotSpot and non-HotSpot behavior now that detection is VM-gated. |
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What does this PR do?:
Gates
FrameType::isRawPointer()'s bit-30 raw-pointer bci encoding to HotSpot only, and fixesframe_ut.cppto test the hotspot/non-hotspot cases separately now that the check is VM-gated.Motivation:
The raw-pointer bci encoding (bit 30) only ever means "jmethodID slot replaced by a VMMethod*" on HotSpot. On OpenJ9, an unencoded, VM-supplied bci can coincidentally have bit 30 set, which was misread as our raw-pointer encoding and routed into
JVMSupport::resolve(), which asserts/aborts for non-HotSpot VMs. Reproduced on Semeru 8.0.462/OpenJ9 viaGetLineNumberTableLeakTest.Additional Notes:
None.
How to test the change?:
frame_ut.cpp'sTrueWhenBit30IsSettest now covers both the HotSpot and non-HotSpot cases explicitly.For Datadog employees:
credentials of any kind, I've requested a security review (run the
dd:platform-security-reviewskill, or file a request via the PSEC review form).
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