RFR: 8017234: Hotspot should stop using mapfiles

[Julian Waters]

On Thu, 22 Feb 2024 09:29:25 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> src/hotspot/share/oops/accessBackend.cpp line 36:
>> 
>>> 34: 
>>> 35: #if defined(TARGET_COMPILER_gcc)
>>> 36: #define HIDDEN __attribute__ ((visibility ("hidden")))
>> 
>> Couldn't this use [[gnu::visibility("hidden")]] instead, since HotSpot now allows C++14 Attributes? But this doesn't look like a very nice solution regardless
>
> We're currently using __attribute__ ((visibility ("X"))) elsewhere, so I think I should stick with that.
> 
> And, as I said in my long explanation, this is definitely a hack. The reason it is here is that I want to make sure the symbol table is 100% identical before and after this patch. 
> 
> Why this is needed, I don't know. I believe it is a bug in GCC, since we compile with -fvisibility=hidden. But I don't really know. Maybe there is something in the C++ standard that makes these functions behave differently. Perhaps they are even slightly incorrectly defined?

Ah, I should have clarified that I did read the explaination, just that it slipped my mind at the time. I can't remember if C++14 or C++17 is the version for compilers ignoring unknown attributes though

Also, you can escape the underscores with \ to avoid GitHub formatting. GitHub can get annoying with its formatting sometimes

Is there a chance this can be fixed in a followup somehow? I could help with that, given I have access to WSL2 for Linux

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PR Review Comment: https://git.openjdk.org/jdk/pull/17955#discussion_r1498972139