gdb error in terminal when debugging translators

[chunhualiao]

freecc@node1:rose-ast$ gdb dotGenerator -c func1.c

GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
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Reading symbols from dotGenerator...done.
"/home/freecc/rose-ast/func1.c" is not a core dump: File format not recognized
(gdb) r
Starting program: /home/freecc/install/rose_install/bin/dotGenerator
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Installing openjdk unwinder
Traceback (most recent call last):
  File "/usr/share/gdb/auto-load/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/server/libjvm.so-gdb.py", line 52, in <module>
    class Types(object):
  File "/usr/share/gdb/auto-load/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/server/libjvm.so-gdb.py", line 66, in Types
    nmethodp_t = gdb.lookup_type('nmethod').pointer()
gdb.error: No type named nmethod.
[Inferior 1 (process 464) exited normally]

[chunhualiao]

A relevant web link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=867314

[chunhualiao]

@ouankou Can we have a docker image with debug build of ROSE?
We would like to add a few tutorials about how to debug later on, using text from https://en.wikibooks.org/wiki/ROSE_Compiler_Framework/How-tos#How_to_debug_a_translator

[ouankou]

OK, I created a specific docker image for previous loop stride bug.
https://github.com/freeCompilerCamp/play-with-compiler/blob/master/dockerfiles/dind/Dockerfile.rose_bug

I'll create a similar one for debug build of ROSE and address this issue.

[ouankou]

@chunhualiao I've uploaded a new docker image of ROSE debug build. freeCompilerCamp/play-with-compiler@96bf3fa

docker pull freecompilercamp/pwc:rose-debug

A related tutorial has been set to use this specific image as example. http://freecompilercamp.org/rose-ast-traversal/

About this issue, I tried several different configurations of JDK and OS. It seems like an upstream bug of JDK8 debug extension of GDB. When GDB loads the JDK 8 debugger plugin openjdk unwinder, it can't find the correct location of JDK libraries.
With OpenJDK8, I tried to use GDB to debug any JAR file and it will throw the same error.

Installing openjdk unwinder
Traceback (most recent call last):
  File "/usr/share/gdb/auto-load/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/server/libjvm.so-gdb.py", line 52, in <module>
    class Types(object):
  File "/usr/share/gdb/auto-load/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/server/libjvm.so-gdb.py", line 66, in Types
    nmethodp_t = gdb.lookup_type('nmethod').pointer()
gdb.error: No type named nmethod.

If I switch to OpenJDK 11, debugging the same JAR file is fine. It's not an issue of ROSE. Any program that involves JDK 8 will trigger this bug in GDB.

I used the same method from this link to test, however, its solution doesn't work.
https://debian-bugs-dist.debian.narkive.com/Ap0ST04C/bug-867314-openjdk-8-jre-headless-openjdk-unwinder-for-gdb-crashes

This page has a long discussion about this issue. In their case, OpenJDK 9 works while OpenJDK 8 has the same issue as ours.
https://savannah.gnu.org/bugs/?53733

I think the possible solutions could be:

1. Remove the OpenJDK 8 plugin in GDB by renaming or removing the py file /usr/share/gdb/auto-load/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/server/libjvm.so-gdb.py.
2. dig the GDB source code and find out how does it locate the JDK library.
3. update ROSE to support JDK higher than 8, ideally JDK 11, the LTS version. Currently, ROSE only support JDK 8 because it requires javah, a tool removed since JDK 9.

Solution 1 is just a workaround. Solution 3 may be better in the long term. ROSE will eventually use some more recent version of OpenJDK anyway. Later I'll check whether Oracle JDK 8 has the same issue or not.