feat(agent): implement @Return and @Duration in ClassFileApiBackend#843
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feat(agent): implement @Return and @Duration in ClassFileApiBackend#843jbachorik wants to merge 1 commit into
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…ackend ClassFileApiBackend (used for Java 26+ class files) previously skipped handlers with @return or @duration parameters. This change adds full support: - @return: dup/dup2 based on TypeKind.slotSize(), store to an allocated local slot, load before INVOKEDYNAMIC. Void methods are silently skipped. - @duration: System.nanoTime() captured at method entry; delta computed at each RETURN point and in a finally-block exception handler (matching the existing ASM instrumentation behavior). Bug fixes applied after chorus review: - emitProbeCall: pre-validate all handler arguments before pushing any onto the stack; an early return mid-loop would leave orphaned stack values and cause a VerifyError on class loading. - emitProbeCall: load the return-value slot using the actual store TypeKind from the ReturnInstruction, not TypeKind.fromDescriptor on the handler descriptor (which would yield REFERENCE for AnyType→Object handlers, mismatching the ISTORE/LSTORE used during capture). - atStart/accept: bind startLabel in accept() alongside entryTsSlot allocation so they are always in sync; an unpairable label in atEnd could leave an unclosed try region. - atEnd: register exceptionCatchAll after binding all three labels; replace stream pipeline with a plain for-loop. Tests cover @return (int, long, void-skip), @duration (normal exit, exception exit), and combined @return+@duration slot-collision check. Tests that require class file version 70 parsing (Java 26+) skip automatically on JDK < 26 via Assumptions.assumeTrue. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This was referenced May 18, 2026
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Summary
Fixes #837 —
ClassFileApiBackend(used for Java 26+ class files) previously skipped all handlers containing@Returnor@Durationparameters. This PR adds full support for both, matching the behavior of the existing ASM-based backend.@Return: Captures the return value viadup/dup2(based onTypeKind.slotSize()), stores it to an allocated local slot, and loads it before theINVOKEDYNAMICprobe call. Void methods are silently skipped.@Duration: CapturesSystem.nanoTime()at method entry, computes the delta at each normal return point, and also covers exceptional exits via afinally-block exception handler (matching the existing ASM instrumentation behavior).Key correctness constraints respected:
INVOKEDYNAMICdescriptor used verbatim fromom.getTargetDescriptor()— not rebuilt.CodeBuilder.allocateLocal()to avoid slot collisions.VerifyError).TypeKindpassed through to the load site soISTORE+ALOADmismatches are impossible even for@AnyType-typed handler parameters.Test plan
supportsVersionAbove69— ClassFileApiBackend selected for version 70+returnsNullWhenNoProbesMatch— no probes → nullentryProbeInjectedIntoMatchingMethod— INVOKEDYNAMIC injected at method entry (JDK 26+)entryProbeNotInjectedWhenMethodNameMismatches— null for non-matching methodreturnProbeInjectedBeforeReturn— INVOKEDYNAMIC injected before RETURN (JDK 26+)noInjectionForUnsupportedKind— Kind.CALL skippedreturnProbeInjectedWithReturnValueInt— int return value captured in descriptor (JDK 26+)returnProbeInjectedWithReturnValueLong— long (2-slot) return value captured (JDK 26+)returnProbeSkippedForVoidMethod— no INVOKEDYNAMIC + ClassLoader load asserts no VerifyError (JDK 26+)durationProbeInjectedOnNormalReturn— long duration parameter in descriptor (JDK 26+)durationProbeInjectedOnExceptionExit— 2 INVOKEDYNAMIC calls (normal + exception handler) (JDK 26+)returnAndDurationSlotsDoNotCollide— at least 2 distinct store slots (JDK 26+)Tests requiring class file version 70 (Java 26) skip automatically on JDK < 26 via
Assumptions.assumeTrue.🤖 Generated with Claude Code
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