RFR: JDK-8200358 Remove mapfiles for JDK executables

Erik Joelsson erik.joelsson at oracle.com
Thu Apr 5 13:47:32 UTC 2018

This looks good, hopefully for the last time. :)

Thanks for hanging in there!


On 2018-04-05 02:16, Magnus Ihse Bursie wrote:
> On 2018-04-04 17:25, Erik Joelsson wrote:
>> On 2018-04-04 00:42, Magnus Ihse Bursie wrote:
>>> On 2018-04-03 23:16, Erik Joelsson wrote:
>>>> Looks good to me at least. Exporting symbols from executables seems 
>>>> wrong so applying hidden as default seems good to me.
>>> Unfortunately, it was not this easy. :-(
>>> Out of paranoia, I also started a test run on Windows, even though 
>>> it should not have been affected. Well, "should not". The added 
>>> JNIEXPORT turns into a __declspec(dllexport) on Windows, which 
>>> causes the Microsoft linker to behave like when linking a dll, so it 
>>> creates a .lib and .exp for each binary, in the bin directory.
>>> *sigh*
>>> I see two ways out of this.
>>> 1) Make the JNIEXPORT conditional on OS. Either by #ifdef before the 
>>> main function, or by declaring something like EXEC_EXPORT instead, 
>>> and let it be empty on Windows.
>>> 2) Let the part of SetupNativeCompilation that handles executables 
>>> behave more like the one for shared libraries, and setting -implib, 
>>> etc. I'm not sure what happens if you pass in -implib when linking 
>>> an executable which does *not* have any dllexport decorations. If it 
>>> breaks, then this does not really seem like a way forward. 
>>> Otherwise, it's probably the safest choice, since it will make sure 
>>> we never leak any *.lib or *.exp for a potential future executable.
>>> What do you think?
>> I really don't know which I would prefer. Would be good to find out 
>> what happens in 2.
> Turns out that -implib is just ignored if not needed, so 2 is clearly 
> the way to go.
> This also meant that there was much overlap between the linking of 
> shared libraries and executables in SetupNativeCompilation, so I 
> (finally) took the time to unify them.
> Updated webrev: 
> http://cr.openjdk.java.net/~ihse/JDK-8200358-remove-launcher-mapfiles/webrev.03
> (Only changes NativeCompilation.gmk)
> /Magnus
>> /Erik

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