RFR : 8202322: AIX: symbol visibility flags not support on xlc 12.1

Ichiroh Takiguchi takiguc at linux.vnet.ibm.com
Tue Jun 5 06:59:01 UTC 2018 

Hello Matthias and Christoph.
Thank you for your explanations.

I did not have enough knowledge about "visibility".

I created following patches.

================================
diff -r 02934b0d661b 
src/java.base/share/native/libjimage/NativeImageBuffer.cpp
--- a/src/java.base/share/native/libjimage/NativeImageBuffer.cpp	Wed May 
30 14:46:28 2018 +0200
+++ b/src/java.base/share/native/libjimage/NativeImageBuffer.cpp	Tue Jun 
05 12:10:41 2018 +0900
@@ -39,7 +39,9 @@
  #include "imageFile.hpp"
  #include "inttypes.hpp"
  #include "jimage.hpp"
+#if !defined(_AIX)
  #include "osSupport.hpp"
+#endif

  #include "jdk_internal_jimage_NativeImageBuffer.h"

diff -r 02934b0d661b src/java.base/unix/native/include/jni_md.h
--- a/src/java.base/unix/native/include/jni_md.h	Wed May 30 14:46:28 
2018 +0200
+++ b/src/java.base/unix/native/include/jni_md.h	Tue Jun 05 12:10:41 
2018 +0900
@@ -29,7 +29,8 @@
  #ifndef __has_attribute
    #define __has_attribute(x) 0
  #endif
-#if (defined(__GNUC__) && ((__GNUC__ > 4) || (__GNUC__ == 4) && 
(__GNUC_MINOR__ > 2))) || __has_attribute(visibility)
+#if (defined(__GNUC__) && ((__GNUC__ > 4) || (__GNUC__ == 4) && 
(__GNUC_MINOR__ > 2))) || __has_attribute(visibility) \
+    || (defined(_AIX) && (defined(__xlC__) && (__xlC__ >= 0xD01)))
    #ifdef ARM
      #define JNIEXPORT     
__attribute__((externally_visible,visibility("default")))
      #define JNIIMPORT     
__attribute__((externally_visible,visibility("default")))
================================

If "osSupport.hpp" was included, XLC++ compiler complained.
I could not understand, which part was invalid...
I'm not sure, "osSupport.hpp" is really required on 
NativeImageBuffer.cpp or not...

I added __xlC__ macro to determine XLC/C++'s version# into jni_md.h. [1]
0xD01 means 13.1 by hexadecimal.

I checked symbol table by "dump -Tv -X64". [2]
It seemed it was fine, some symbols were hidden.

Does someone review my code?

[1] 
https://www.ibm.com/support/knowledgecenter/en/SSGH2K_13.1.3/com.ibm.xlc1313.aix.doc/compiler_ref/xlmacros.html
[2] 
https://www.ibm.com/developerworks/aix/library/au-aix-symbol-visibility/index.html

On 2018-06-01 21:12, Baesken, Matthias wrote:
> Hi ,  my change  8202322   just  handled  the fact   that  the
> visibility - flags   are not supported  with  xlc 12.1  ,  so  setting
> them generated a TON of compile - time  warnings .
> 
> The introduction of   the  "-qvisibility=hidden"    came with the
> mapfile removal changes :
> 
> 8200358: Remove mapfiles for JDK executables
> http://hg.openjdk.java.net/jdk/jdk/rev/210cf224b690
> 
> 8200178: Remove mapfiles for JDK native libraries
> http://hg.openjdk.java.net/jdk/jdk/rev/396ea30afbd5
> 
> I guess it  might  need further  testing+adjustments  to make  the
> "visibility hiding" work nicely   with XLC13  ,  but currently  we
> build only with XLC12 .
> 
> As a workaround  you might want to  remove  the  "-qvisibility=hidden"
>  setting for XLC 13 as well  ,  like I did  for XLC12 with  the change
>   8202322   .
> 
> 
> Best regards, Matthias
> 
> 
> 
> 
>> -----Original Message-----
>> From: Langer, Christoph
>> Sent: Freitag, 1. Juni 2018 10:57
>> To: Ichiroh Takiguchi <takiguc at linux.vnet.ibm.com>
>> Cc: Baesken, Matthias <matthias.baesken at sap.com>; 'build-
>> dev at openjdk.java.net' <build-dev at openjdk.java.net>; ppc-aix-port-
>> dev at openjdk.java.net; core-libs-dev at openjdk.java.net; Lindenmaier,
>> Goetz <goetz.lindenmaier at sap.com>
>> Subject: RE: RFR : 8202322: AIX: symbol visibility flags not support 
>> on xlc 12.1
>> 
>> Hi Ichiroh,
>> 
>> we do not use the XLC 13 compiler on AIX yet here at SAP and I believe
>> nobody of my colleagues has played with it yet. So you are on a new
>> playground here ��
>> 
>> However, I believe the idea in OpenJDK with the abolition of map files 
>> is that
>> symbols should be invisible externally unless they are declared 
>> exported,
>> e.g. JNIEXPORT. So I would think "-qvisibility=hidden" should be the 
>> correct
>> default and whatever JNIEXPORT expands to should contain the right
>> attributes to get that symbol visible.
>> 
>> Can you check if either my assumption is completely wrong, JNIEXPORT 
>> does
>> not expand to the right thing, XLC 13 has a bug or maybe just sume 
>> specific
>> required symbols are not declared correctly?
>> 
>> Best regards
>> Christoph
>> 
>> > -----Original Message-----
>> > From: Ichiroh Takiguchi [mailto:takiguc at linux.vnet.ibm.com]
>> > Sent: Donnerstag, 31. Mai 2018 09:55
>> > To: Langer, Christoph <christoph.langer at sap.com>
>> > Cc: Baesken, Matthias <matthias.baesken at sap.com>; 'build-
>> > dev at openjdk.java.net' <build-dev at openjdk.java.net>; ppc-aix-port-
>> > dev at openjdk.java.net; core-libs-dev at openjdk.java.net; Lindenmaier,
>> > Goetz <goetz.lindenmaier at sap.com>
>> > Subject: RE: RFR : 8202322: AIX: symbol visibility flags not support on xlc 12.1
>> >
>> > Hello.
>> > 8202322 was integrated into jdk-11+15.
>> > I'm using XLC 13.1.3 on AIX 7.1.4.
>> > Build was failed because of "-qvisibility=hidden" on
>> > make/lib/LibCommon.gmk.
>> > According to "XL C/C++ for AIX 13.1.3" documentation [1],
>> > "-qvisibility=hidden" cannot create shared libraries entry points.
>> > For example, libverify.so was there, but entry points were not resolved
>> > by "-lverify" option.
>> > I think it should be "-qvisibility=default" (I tried, it worked)
>> > or "-qvisibility=protected" (I had not tried) ?
>> > I'm not familiar with -qvisibility option, but I'd like to find out
>> > right way.
>> >
>> > [1]
>> >
>> https://www.ibm.com/support/knowledgecenter/SSGH3R_13.1.3/com.ibm.
>> > xlcpp1313.aix.doc/compiler_ref/opt_visibility.html
>> >
>> > On 2018-05-16 16:08, Langer, Christoph wrote:
>> > > Hi Matthias,
>> > >
>> > > yes, reviewed.
>> > >
>> > > Best regards
>> > > Christoph
>> > >
>> > > From: Baesken, Matthias
>> > > Sent: Mittwoch, 16. Mai 2018 09:06
>> > > To: Langer, Christoph <christoph.langer at sap.com>;
>> > > 'build-dev at openjdk.java.net' <build-dev at openjdk.java.net>;
>> > > ppc-aix-port-dev at openjdk.java.net; core-libs-dev at openjdk.java.net
>> > > Cc: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>
>> > > Subject: RE: RFR : 8202322: AIX: symbol visibility flags not support on
>> > > xlc 12.1
>> > >
>> > > Hi  Christoph can I add you as second reviewer  (other reviewer was
>> > > Erik Joelsson) can push the change ?
>> > >
>> > > Best regards, Matthias
>> > >
>> > >
>> > >
>> > > From: Langer, Christoph
>> > > Sent: Donnerstag, 26. April 2018 16:38
>> > > To: Baesken, Matthias
>> > > <matthias.baesken at sap.com<mailto:matthias.baesken at sap.com>>;
>> > > 'build-dev at openjdk.java.net'
>> > > <build-dev at openjdk.java.net<mailto:build-dev at openjdk.java.net>>;
>> > > ppc-aix-port-dev at openjdk.java.net<mailto:ppc-aix-port-
>> > dev at openjdk.java.net>;
>> > > core-libs-dev at openjdk.java.net<mailto:core-libs-
>> dev at openjdk.java.net>
>> > > Cc: Simonis, Volker
>> > > <volker.simonis at sap.com<mailto:volker.simonis at sap.com>>
>> > > Subject: RE: RFR : 8202322: AIX: symbol visibility flags not support on
>> > > xlc 12.1
>> > >
>> > > Hi Matthias,
>> > >
>> > > to me the change in principal looks good.
>> > >
>> > > I'm wondering if it is possible to do a comparison like xlc < 13 (e.g.
>> > > extract major number before the first dot, then compare numerically) -
>> > > but maybe it is too complicated and the current single version compare
>> > > suits our needs ?
>> > >
>> > > Best regards
>> > > Christoph
>> > >
>> > > From: Baesken, Matthias
>> > > Sent: Donnerstag, 26. April 2018 16:14
>> > > To: 'build-dev at openjdk.java.net'
>> > > <build-dev at openjdk.java.net<mailto:build-dev at openjdk.java.net>>;
>> > > ppc-aix-port-dev at openjdk.java.net<mailto:ppc-aix-port-
>> > dev at openjdk.java.net>;
>> > > core-libs-dev at openjdk.java.net<mailto:core-libs-
>> dev at openjdk.java.net>
>> > > Cc: Langer, Christoph
>> > > <christoph.langer at sap.com<mailto:christoph.langer at sap.com>>;
>> Simonis,
>> > > Volker <volker.simonis at sap.com<mailto:volker.simonis at sap.com>>
>> > > Subject: RFR : 8202322: AIX: symbol visibility flags not support on xlc
>> > > 12.1
>> > >
>> > > Hello  ,  could you please review this small adjustment to  the symbol
>> > > visibility compilation settings on AIX ?
>> > > Currently  we use  XLC 12.1  to compile  JDK on AIX .
>> > >
>> > > However XLC 12.1   does not support  the "-qvisibility=hidden"
>> > > setting currently set on AIX.
>> > > It was introduced with  XLC 13.1 . Christoph found some info about it
>> > > here :
>> > >
>> > > https://www.ibm.com/developerworks/aix/library/au-aix-symbol-
>> > visibility-part2/index.html
>> > >
>> > > Setting it  only generates  hundreds  of warnings  in the build log ,
>> > > warnings look like this :
>> > > XlC12.1
>> > >
>> > > bash-4.4$ xlC -qversion
>> > > IBM XL C/C++ for AIX, V12.1 (5765-J02, 5725-C72)
>> > > Version: 12.01.0000.0019
>> > >
>> > > bash-4.4$ xlC -qvisibility=hidden sizeof.c -o sizeof_aixxlc
>> > > 1506-173 (W) Option visibility=hidden is not valid. Enter xlC for list
>> > > of valid options.
>> > >
>> > > Compare to XLC13.1
>> > >
>> > > bash-3.00$ xlC -qversion
>> > > IBM XL C/C++ for AIX, V13.1 (5725-C72, 5765-J07)
>> > > Version: 13.01.0000.0008
>> > > bash-3.00$ xlC -qvisibility=default sizeof.c -o sizeof_aixxlc
>> > > bash-3.00$ xlC -qvisibility=hidden sizeof.c -o sizeof_aixxlc
>> > >
>> > >
>> > > So it is better to avoid  setting these flags when using xlc12.1   .
>> > > Please review :
>> > >
>> > > Bug :
>> > >
>> > > https://bugs.openjdk.java.net/browse/JDK-8202322
>> > >
>> > > Change :
>> > >
>> > > http://cr.openjdk.java.net/~mbaesken/webrevs/8202322/
>> > >
>> > >
>> > > Best regards, Matthias

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