[foreign+linkToNative] RFR: Fill out missing Windows upcall stub generation

[Jorn Vernee]

Thanks, pushed.

Jorn

Sundararajan Athijegannathan schreef op 2019-02-12 14:33:
> Incremental webrev looks good to me.
> 
> -Sundar
> 
> On 12/02/19, 6:57 PM, Jorn Vernee wrote:
>> Thanks for bringing this up.
>> 
>> I remember seeing that JEP discussed on build-dev a while ago, so I 
>> thought trying out constexpr (a C++11 feature) and thought the 
>> compiler would reject it if usage was not yet allowed by the build 
>> system. e.g. through a flag like -std=c++03.
>> 
>> But, reading more into it now, it looks like such a flag is only 
>> supported since MSVC 2017, and the minimal setting is C++14 [1].
>> 
>> From the JEP it seems that use of `constexpr` is not officially 
>> allowed yet. What I added can be changed to use `const`. I was using 
>> constexpr to make sure I had a constant expression to declare the 
>> array in upcall_context, but the compiler will also throw an error if 
>> the expression is not constant, so it's not super important.
>> 
>> I have tested the following patch, which should fix the issue: 
>> http://cr.openjdk.java.net/~jvernee/panama/webrevs/constexprfix/webrev.00/
>> 
>> Jorn
>> 
>> [1] : 
>> https://docs.microsoft.com/en-us/cpp/build/reference/std-specify-language-standard-version?view=vs-2017
>> 
>> Sundararajan Athijegannathan schreef op 2019-02-12 06:36:
>>> This is in response to
>>> https://mail.openjdk.java.net/pipermail/panama-dev/2019-February/004199.html 
>>> Change in directUpcallHandler_x86.cpp uses "constexpr".
>>> 
>>>     https://openjdk.java.net/jeps/347 (a candidate JEP)
>>> 
>>> says
>>> 
>>> " With JDK 11, the code has been updated to support building with
>>> newer versions of the C++ standard, although it is not yet using any
>>> new features. This includes being able to build with recent versions
>>> of various compilers that support C++11/14 language features."
>>> 
>>> FWIW I searched for "constexpr" in current hotspot code and I didn't
>>> find any usage.
>>> 
>>> -Sundar