Integrated: 8359120: Improve warning message when fail to load hsdis library

[Taizo Kurashige]

On Tue, 10 Jun 2025 13:38:03 GMT, Taizo Kurashige <tkurashige at openjdk.org> wrote:

> This PR is improvement of warning message when fail to load hsdis library.
> 
> [JDK-8287001](https://bugs.openjdk.org/browse/JDK-8287001) introduced a warning on hsdis library load failure. This is useful when the user executes -XX:+PrintAssembly, etc.
> 
> However, I think that when hs_err occurs, users might be confused by this warning printed by Xlog. Because users are not likely to know that hsdis is loaded for the [MachCode] section of the hs_err report, they may wonder, for example, "Why do I get warnings about hsdis load errors when -XX:+PrintAssembly is not specified?."
> 
> To clear up this confusion, I suggest printing a warning just before [MachCode].
> 
> <details>
> 
> <summary>sample output</summary>
> 
> If hs_err occurs and hsdis load fails without the option to specify where the hs_err report should be output, the following is output to the hs_err_pir log file:
> 
> .
> .
> native method entry point (kind = native)  [0x000001ae8753cec0, 0x000001ae8753dac0]  3072 bytes
> 
> Loading hsdis library failed, so undisassembled code is printed in the below [MachCode] section
> [MachCode]
>   0x000001ae8753cec0: 488b 4b08 | 0fb7 492e | 584c 8d74 | ccf8 6800 | 0000 0068 | 0000 0000 | 5055 488b | ec41 5548
>   0x000001ae8753cee0: 8b43 084c | 8d68 3848 | 8b40 0868 | 0000 0000 | 5348 8b50 | 18
> .
> .
> 
> 
> If -XX:+PrintAssembly is specified and hsdis load fails, the following is output to the stdout
> 
> $ java -XX:+UnlockDiagnosticVMOptions -XX:+PrintAssembly -version
> OpenJDK 64-Bit Server VM warning: PrintAssembly is enabled; turning on DebugNonSafepoints to gain additional output
> 
> ============================= C1-compiled nmethod ==============================
> ----------------------------------- Assembly -----------------------------------
> 
> Compiled method (c1) 57    2       3       java.lang.Object::<init> (1 bytes)
>  total in heap  [0x0000024a08a00008,0x0000024a08a00208] = 512
> .
> .
> 
> [Constant Pool (empty)]
> 
> 
> Loading hsdis library failed, so undisassembled code is printed in the below [MachCode] section
> [MachCode]
> [Instructions begin]
>   0x0000024a08a00100: 6666 660f | 1f84 0000 | 0000 0066 | 6666 9066 | 6690 448b | 5208 443b
> .
> .
> [Constant Pool (empty)]
> 
> 
> Loading hsdis library failed, so undisassembled code is printed in the below [MachCode] section
> [MachCode]
> [Verified Entry Point]
>   # {method} {0x00000000251a1898} 'toUnsignedInt' '(B)I' in 'java/lang/Byte
> .
> .
> 
> 
> </details>
> 
> Since the warning added in this fix cover the role of warning introduced in [JDK-8287001](https://bugs.openjdk.org/browse/JDK-828...

This pull request has now been integrated.

Changeset: ce998699
Author:    Taizo Kurashige <tkurashige at openjdk.org>
Committer: Manuel Hässig <mhaessig at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/ce9986991d60e116ac6680a1b6a4b3ee5384d105
Stats:     9 lines in 2 files changed: 9 ins; 0 del; 0 mod

8359120: Improve warning message when fail to load hsdis library

Reviewed-by: mhaessig, thartmann

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PR: https://git.openjdk.org/jdk/pull/25726