RFR: JDK-8214063: OpenJDK will not build on AIX while using the xlc 13.1 compiler

Wed Nov 21 12:46:31 UTC 2018

Hi Volker,

The NativeImageBuffer.cpp changes are best explained by the full text of 
the referenced GitHub Pull Request, copied here for simplicity:

-----------------------------------------
Define JNIEXPORT and JNIIMPORT for xlc version 13.1 or newer. Without 
this, 
almost no symbols are exported from shared libraries due to use of 
-qvisibility=hidden as specified in make/lib/LibCommon.gmk. The symptoms 
are reported in eclipse/openj9#2468.

Unfortunately, this encounters a bug in xlc: it fails to parse what seems 
to be reasonable code. A workaround is required in just one place: 
src/java.base/share/native/libjimage/NativeImageBuffer.cpp.
-----------------------------------------

Best Regards

Adam Farley 
IBM Runtimes

Volker Simonis <volker.simonis at gmail.com> wrote on 20/11/2018 17:50:41:

> From: Volker Simonis <volker.simonis at gmail.com>
> To: "Stuefe, Thomas" <thomas.stuefe at gmail.com>
> Cc: adam.farley at uk.ibm.com, Java Core Libs 
<core-libs-dev at openjdk.java.net>
> Date: 20/11/2018 17:59
> Subject: Re: RFR: JDK-8214063: OpenJDK will not build on AIX while 
> using the xlc 13.1 compiler
> 
> On Tue, Nov 20, 2018 at 6:15 PM Thomas Stüfe <thomas.stuefe at gmail.com> 
wrote:
> >
> > On Tue, Nov 20, 2018 at 6:12 PM Adam Farley8 <adam.farley at uk.ibm.com> 
wrote:
> > >
> > > Heya Tom,
> > >
> > > "In JDK11 and JDK12, source files are compiled with 
-qvisibility=hidden
> > > when using xlc version other than 12.1. That doesn't seem to play 
well
> > > with link option -bexpall. "
> > >
> > > Found that buried in one of the associated Git issues. It appears 
that
> > > it's OpenJDK's use of that option that's causing the problem, though
> > > I couldn't speculate as to why it was added in the first place.
> > >
> > > I see this has also been noted in https://
> urldefense.proofpoint.com/v2/url?
> 
u=https-3A__bugs.openjdk.java.net_browse_JDK-2D8204541&d=DwIFaQ&c=jf_iaSHvJObTbx-
> siA1ZOg&r=P5m8KWUXJf-
> 
CeVJc0hDGD9AQ2LkcXDC0PMV9ntVw5Ho&m=SD6UdjysISJRBlWUm8pEzF5lRZ5opfbrKzEh_jrOras&s=5qDEdIfg8qZ-
> vCglsZ9qNDTEPMnCkj-mVPVah6eEDLE&e=
> > >
> > > Does that answer your question?
> > >
> >
> > Yes, Thank you. Odd. Will have to do archeology on that one.
> >
> 
> No I begin to understand the problem as well :)
> 
> It was actually change "8202322: AIX: symbol visibility flags not
> support on xlc 12.1" [1] which introduced "-qvisibility=hidden" for
> XLC version not equal to 12.1. That's kind of a weak check and I
> suppose nobody has ever tested this change with an XLC version other
> than 12.1 (until you came along :). Maybe that check should be a more
> precisly check for >= 13.1 (but I know such version checks are hard to
> do in Makefile syntax)?
> 
> The thing I don't understand about your patch (the changes in
> "jni_md.h" look good although I haven't tested them) is why you need
> the extra changes in NativeImageBuffer.cpp?
> "jdk_internal_jimage_NativeImageBuffer.h" is a plain, generated JNI
> header file. If XLC 13 has problems to parse it, there should be much
> more places which need fixing. I think that part of your change needs
> a closer evaluation.
> 
> Thank you and best regards,
> Volker
> 
> [1] INVALID URI REMOVED
> 
u=https-3A__bugs.openjdk.java.net_browse_JDK-2D8202322&d=DwIFaQ&c=jf_iaSHvJObTbx-
> siA1ZOg&r=P5m8KWUXJf-
> 
CeVJc0hDGD9AQ2LkcXDC0PMV9ntVw5Ho&m=SD6UdjysISJRBlWUm8pEzF5lRZ5opfbrKzEh_jrOras&s=JAEK6rePGMPinZzOquHBzj5oc7vA3kaFt9x0WIIUzvk&e=
> 
> > ..Thomas
> >
> > > Best Regards
> > >
> > > Adam Farley
> > > IBM Runtimes
> > >
> > >
> > > "Thomas Stüfe" <thomas.stuefe at gmail.com> wrote on 20/11/2018 
16:44:07:
> > >
> > > > From: "Thomas Stüfe" <thomas.stuefe at gmail.com>
> > > > To: Adam Farley8 <adam.farley at uk.ibm.com>
> > > > Cc: Java Core Libs <core-libs-dev at openjdk.java.net>
> > > > Date: 20/11/2018 16:48
> > > > Subject: Re: RFR: JDK-8214063: OpenJDK will not build on AIX while
> > > > using the xlc 13.1 compiler
> > > >
> > > > Hi Adam,
> > > >
> > > > On Tue, Nov 20, 2018 at 5:12 PM Adam Farley8 
> <adam.farley at uk.ibm.com> wrote:
> > > > >
> > > > > Hi Tom,
> > > > >
> > > > > Sounds reasonable. I've added a webex to the bug, and here's a
> > > > link to the bug.
> > > > >
> > > > > INVALID URI REMOVED
> > > > 
> 
u=https-3A__bugs.openjdk.java.net_browse_JDK-2D8214063&d=DwIFaQ&c=jf_iaSHvJObTbx-
> > > > siA1ZOg&r=P5m8KWUXJf-
> > > > 
> 
CeVJc0hDGD9AQ2LkcXDC0PMV9ntVw5Ho&m=z8YYwBXEfN7UtX1suPjpp9CZSHf8v0GrIMK3XGIC9VY&s=81TP9mIjhYD2Hmt8g7p2EHWRZXgiep21hxKLYRU7zIQ&e=
> > > > >
> > > > > This patch is required because otherwise, when building on AIX
> > > > using xlc 3.1,
> > > > > the build fails with this error:
> > > > >
> > > > > "Visibility is not allowed on a reference to an imported 
symbol."
> > > > >
> > > > > We believe this is caused by JNIEXPORT and JNIIMPORT not being
> > > > defined. Without
> > > > > this, almost no symbols are exported from shared libraries 
> due to use of
> > > > > -qvisibility=hidden as specified in make/lib/LibCommon.gmk.
> > > >
> > > > Yes but what I try to understand is why does this happen now with
> > > > xlc13? Did xlc change the rules for -qvisibility from v12 to v13 ?
> > > > That would be quite a break in backward compatibility.
> > > >
> > > > >
> > > > > For convenience, here's a summary of the diffs:
> > > > >
> > > > > --------------------------------------
> > > > > File 1 of 2) src/java.base/share/native/libjimage/
> NativeImageBuffer.cpp
> > > > >
> > > > >  #include "osSupport.hpp"
> > > > >
> > > > > +#if defined(__xlC__) && (__xlC__ >= 0x0d01)
> > > > > +/*
> > > > > + * Version 13.1.3 of xlc seems to have trouble parsing the 
> `__attribute__`
> > > > > + * annotation in the generated header file we're about to
> > > > include. Repeating
> > > > > + * the forward declaration (without the braces) here avoids
> the diagnostic:
> > > > > + *   1540-0040 (S) The text "void" is unexpected.  "visibility"
> > > > may be undeclared or ambiguous.
> > > > > + */
> > > > > +extern "C" JNIEXPORT jobject JNICALL
> > > > Java_jdk_internal_jimage_NativeImageBuffer_getNativeMap(JNIEnv *,
> > > > jclass, jstring);
> > > > > +#endif
> > > > > +
> > > > > #include "jdk_internal_jimage_NativeImageBuffer.h"
> > > > > --------------------------------------
> > > > > File 2 of 2) src/java.base/unix/native/include/jni_md.h
> > > > >
> > > > >      #define JNIIMPORT __attribute__((visibility("default")))
> > > > >   #endif
> > > > > +#elif defined(__xlC__) && (__xlC__ >= 0x0d01) /* xlc version 
13.1
> > > > or better required */
> > > > > +  #define JNIEXPORT __attribute__((visibility("default")))
> > > > > +  #define JNIIMPORT __attribute__((visibility("default")))
> > > > > #else
> > > > >   #define JNIEXPORT
> > > > > --------------------------------------
> > > > >
> > > >
> > > > Thank you.
> > > >
> > > > Cheers, Thomas
> > > >
> > > > > Best Regards
> > > > >
> > > > > Adam Farley
> > > > > IBM Runtimes
> > > > >
> > > > >
> > > > > "Thomas Stüfe" <thomas.stuefe at gmail.com> wrote on 
19/11/201818:11:34:
> > > > >
> > > > > > From: "Thomas Stüfe" <thomas.stuefe at gmail.com>
> > > > > > To: Adam Farley8 <adam.farley at uk.ibm.com>
> > > > > > Cc: Java Core Libs <core-libs-dev at openjdk.java.net>
> > > > > > Date: 19/11/2018 18:12
> > > > > > Subject: Re: RFR: JDK-8214063: OpenJDK will not build on AIX 
while
> > > > > > using the xlc 13.1 compiler
> > > > > >
> > > > > > Hi Adam,
> > > > > >
> > > > > > could you please include link to the JBS issue and either 
> link to the
> > > > > > patch/webrev or link to the webrev, or at the very least the 
patch
> > > > > > verbatim?
> > > > > >
> > > > > > As for the issue itself: could you please elaborate why this
> > > > fails with xlc13?
> > > > > >
> > > > > > Also, a real patch would be helpful instead here of yet 
another link
> > > > > > to some J9 issue. We are really strapped for manpower and 
> the AIX port
> > > > > > eats up enough time as it is.
> > > > > >
> > > > > > Thanks, Thomas
> > > > > >
> > > > > > On Mon, Nov 19, 2018 at 6:28 PM Adam Farley8
> > > > <adam.farley at uk.ibm.com> wrote:
> > > > > > >
> > > > > > > Hi All
> > > > > > >
> > > > > > > Both the problem and the solution appear straight-forward 
enough.
> > > > > > >
> > > > > > > Details included in the bug description.
> > > > > > >
> > > > > > > Thoughts and opinions welcome.
> > > > > > >
> > > > > > > Best Regards
> > > > > > >
> > > > > > > Adam Farley
> > > > > > > IBM Runtimes
> > > > > > >
> > > > > > > Unless stated otherwise above:
> > > > > > > IBM United Kingdom Limited - Registered in England and 
> Wales with number
> > > > > > > 741598.
> > > > > > > Registered office: PO Box 41, North Harbour, Portsmouth,
> > > > Hampshire PO6 3AU
> > > > > >
> > > > >
> > > > > Unless stated otherwise above:
> > > > > IBM United Kingdom Limited - Registered in England and Wales 
with
> > > > number 741598.
> > > > > Registered office: PO Box 41, North Harbour, Portsmouth, 
> Hampshire PO6 3AU
> > > >
> > >
> > > Unless stated otherwise above:
> > > IBM United Kingdom Limited - Registered in England and Wales 
> with number 741598.
> > > Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire 
PO6 3AU
> 

Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU