RFR (L, tedious again, sorry) 8189610: Reconcile jvm.h and all jvm_md.h between java.base and hotspot

Magnus Ihse Bursie magnus.ihse.bursie at oracle.com
Thu Oct 26 09:57:15 UTC 2017


Thank you for addressing this!

On 2017-10-25 18:49, coleen.phillimore at oracle.com wrote:
> Summary: removed hotspot version of jvm*h and jni*h files
> Mostly used sed to remove prims/jvm.h and move #include "jvm.h" after 
> precompiled.h, so if you have repetitive stress wrist issues don't 
> click on most of these files.
> There were more issues to resolve, however.  The JDK windows jni_md.h 
> file defined jint as long and the hotspot windows jni_x86.h as int.  I 
> had to choose the jdk version since it's the public version, so there 
> are changes to the hotspot files for this. Generally I changed the 
> code to use 'int' rather than 'jint' where the surrounding API didn't 
> insist on consistently using java types. We should mostly be using C++ 
> types within hotspot except in interfaces to native/JNI code.  There 
> are a couple of hacks in places where adding multiple jint casts was 
> too painful.
> Tested with JPRT and tier2-4 (in progress).
> open webrev at http://cr.openjdk.java.net/~coleenp/8189610.01/webrev

Looks great!

Just a few comments:

* src/java.base/unix/native/include/jni_md.h:

I don't think the externally_visible attribute should be there for arm. 
I know this was the case for the corresponding hotspot file for arm, but 
that was techically incorrect. The proper dependency here is that 
externally_visible should be in all JNIEXPORT if and only if we're 
building with JVM feature "link-time-opt". Traditionally, that feature 
been enabled when building arm32 builds, and only then, so there's been 
a (coincidentally) connection here. Nowadays, Oracle does not care about 
the arm32 builds, and I'm not sure if anyone else is building them with 
link-time-opt enabled.

It does seem wrong to me to export this behavior in the public jni_md.h 
file, though. I think the correct way to solve this, if we should 
continue supporting link-time-opt is to make sure this attribute is set 
for exported hotspot functions. If it's still needed, that is. A quick 
googling seems to indicate that visibility("default") might be enough in 
modern gcc's.

A third option is to remove the support for link-time-opt entirely, if 
it's not really used.

* src/java.base/unix/native/include/jvm_md.h and 

These files define a public API, and contain non-trivial changes. I 
suspect you should file a CSR request. (Even though I realize you're 
only matching the header file with the reality.)


> bug link https://bugs.openjdk.java.net/browse/JDK-8189610
> I have a script to update copyright files on commit.
> Thanks to Magnus and ErikJ for the makefile changes.
> Thanks,
> Coleen

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