RFR: 8359120: Improve warning message when fail to load hsdis library [v2]
Taizo Kurashige
tkurashige at openjdk.org
Mon Jun 23 08:56:12 UTC 2025
> 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...
Taizo Kurashige has updated the pull request incrementally with one additional commit since the last revision:
Fix message and revert lines for Xlog
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/25726/files
- new: https://git.openjdk.org/jdk/pull/25726/files/45584ba7..6ff4f9b5
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=25726&range=01
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=25726&range=00-01
Stats: 6 lines in 3 files changed: 3 ins; 0 del; 3 mod
Patch: https://git.openjdk.org/jdk/pull/25726.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/25726/head:pull/25726
PR: https://git.openjdk.org/jdk/pull/25726
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