RFR: 8017234: Hotspot should stop using mapfiles

[Daniel Jeliński]

On Thu, 22 Feb 2024 09:41:45 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> src/hotspot/share/utilities/debug.cpp line 71:
>> 
>>> 69: 
>>> 70: #if defined(TARGET_COMPILER_gcc)
>>> 71: #undef JNIEXPORT
>> 
>> This partially reverts [JDK-8264593](https://bugs.openjdk.org/browse/JDK-8264593); @kevinjwalls will this work for you?
>
> No, it doesn't. Even after [JDK-8264593](https://bugs.openjdk.org/browse/JDK-8264593) the symbols from debug.cpp were not exported on Linux, since they were not mentioned in `make/data/hotspot-symbols`, and thus were made local.
> 
> The reason I put this in was to keep parity with the symbol table before and after the patch.
> 
> My guess is that it was only on Windows it was necessary that the functions where JNIEXPORTed, otherwise someone would have complained after JDK-8264593. But for platform consistency, it might make sense to export these even on gcc as well. After this PR is integrated, this is easy to do -- just remove the above hack.

they were absent from .dynsym but available in .symtab as bind: local, visibility: default. Now they are completely gone.

The symbols were supposed to be used from gdb. I'm not sure if gdb can access local symbols, so it's possible that they didn't work even before this change.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17955#discussion_r1498964087