Integrated: 8284115: [IR Framework] Compilation is not found due to rare safepoint while dumping PrintIdeal/PrintOptoAssembly

[Christian Hagedorn]

On Fri, 13 May 2022 07:45:18 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

> This is yet another manifestation of the safepointing problem while printing a `PrintIdeal/PrintOptoAssembly` block.
> 
> In this case here, a safepoint is done and the `` message is emitted while dumping a `PrintIdeal` block of `retainDenominator()` inside the `hotspot_pid` file. During this interruption, another test class method is enqueued for compilation which is logged to the `hotspot_pid` file before the printing of the `PrintIdeal` block resumes:
> 
> 
> # PrintIdeal output of retainDenominator()
>  3 Start === 3 0 [[ 3 5 6 7 8 9 13 11 ]] #{0:control, 1:abIO, 2:memory, 3:rawptr:BotPTR, 4:return_address, 5:compiler/c2/irTests/DivLNodeIdealizationTests:NotNull *, 6:long, 7:half, 8:long, 9:half}
>  36 CallStaticJava === 34 6 7 8 9 ( 35 1 1 1 1 1 26 1 27 1 ) [[ 37 ]] # Static uncommon_trap(reason='div0_check' action='maybe_recompile' debug_id='0') void ( int ) C=0.000100 DivLNodeIdealizationTests::retainDenominator @ bci:4 (line 130) !jvms: DivLNodeIdealizationTests::retainDenominator
> 
> # Safepoint interruption
> <writer thread='40451'/>
> 
> # Enqueuing of another test class method identityThird()
> <task_queued compile_id='205' method='compiler.c2.irTests.DivLNodeIdealizationTests identityThird (JJ)J' bytes='6' count='6000' iicount='6000' blocking='1' stamp='1.046' comment='whitebox' hot_count='6000'/>
> <writer thread='23811'/>
>  @ bci:4 (line 130)
> 
> # Continue to dump PrintIdeal of retainDenominator()
>  41 DivL === 33 26 13 [[ 42 ]] !jvms: DivLNodeIdealizationTests::retainDenominator @ bci:4 (line 130)
>  9 Parm === 3 [[ 42 36 ]] ReturnAdr !jvms: DivLNodeIdealizationTests::retainDenominator @ bci:-1 (line 130)
> 
> 
> The `HotSpotPidFileParser` looks for these enqueue messages containing the method name in order to find and correctly map the corresponding `PrintIdeal` and `PrintOptoAssembly` outputs. However, the `HotSpotPidFileParser` does not expect such an enqueuing message to be found inside a `PrintIdeal/PrintOptoAssembly` block and thus ignores it. As a result, we later do not parse the `PrintIdeal` and `PrintOptoAssembly` output of the enqueued method during the safepoint and fail with the assertion that we did not find any compilation output for the method.
> 
> In the example above, the assertion says that we did not find the compilation output of `identityThird()` whose enqueue message was ignored inside the `PrintIdeal` block of `retainDominator()`.
> 
> The proposed fix is to make `HotSpotPidFileParser` aware of the possibility of a safepoint while reading the `PrintIdeal` or `PrintOptoAssembly` output and therefore add a check if there was a method enqueued for compilation while reading inside `BlockOutputReader::readBlock()`.
> 
> Thanks,
> Christian

This pull request has now been integrated.

Changeset: 39842538
Author:    Christian Hagedorn <chagedorn at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/39842538004c5fca57701070484c78cacf95ed64
Stats:     160 lines in 6 files changed: 109 ins; 40 del; 11 mod

8284115: [IR Framework] Compilation is not found due to rare safepoint while dumping PrintIdeal/PrintOptoAssembly

Reviewed-by: kvn, thartmann

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PR: https://git.openjdk.java.net/jdk/pull/8692