RFR: 8239001: Hotspot build broken on linux-sparc after 8238281

[Magnus Ihse Bursie]

I searched the code base for mentions of old gcc workarounds, and tried to remedy them now that they were not needed. 

If it turns out that they still were needed, by all means, revert that part of the patch. 

/Magnus

13 feb. 2020 kl. 20:35 skrev Kim Barrett <kim.barrett at oracle.com>:

>> On Feb 13, 2020, at 7:26 AM, John Paul Adrian Glaubitz <glaubitz at physik.fu-berlin.de> wrote:
>> 
>> Hello!
>> 
>> Hotspot fails to build on linux-sparc after 8238281 due to the redefinition
>> of offset_of() in src/hotspot/share/prims/jvm.cpp [1]:
>> 
>> /home/glaubitz/jdk/src/hotspot/cpu/sparc/macroAssembler_sparc.hpp: In static member function 'static int RegistersForDebugging::i_offset(int)':
>> /home/glaubitz/jdk/src/hotspot/cpu/sparc/macroAssembler_sparc.hpp:488:74: error: 'j' cannot appear in a constant-expression
>> 488 | static int i_offset(int j) { return offset_of(RegistersForDebugging, i[j]); }
>>     | ^ 
>> 
>> Since offsetof() can only be used with constant expressions, I have reused
>> the old definition of offset_of() in src/hotspot/cpu/sparc/macroAssembler_sparc.hpp
>> to fix the issue.
>> 
>> I couldn't come up with a more elegant solution, but I'm open for suggestions.
>> 
>> Please review my change in [2].
>> 
>> Thanks,
>> Adrian
>> 
>>> [1] https://bugs.openjdk.java.net/browse/JDK-8239001
>>> [2] http://cr.openjdk.java.net/~glaubitz/8239001/webrev.00/
> 
> I don't think this is the right way to address this problem.
> 
> I think the JDK-8238281 change to offset_of and the associated
> addition of -Wno-invalid-offsetof to the build configuration was a
> mistake, and should be reverted.  Those changes seem unrelated to the
> purpose of JDK-8238281, which was to raise the minimum acceptable gcc
> version.
>