Re: [rvm-research] Using VM.SysWriteln()

Hi,

I add just one more point to what Mike said: assuming that your
printValue() method is as above, calling o.hashCode() causes a
NullPointerException if o is null, which may cause other
NullPointerExceptions recursively.

Thanks,
Meisam

On Mon, Apr 22, 2013 at 5:44 PM, Michael Bond
<[email protected]> wrote:
> Hi Pushparaj,
>
> I see two issues:
>
> First, it looks like recursive instrumentation is happening: printValue() is
> calling methods that are getting instrumented with calls to printValue(). To
> restrict instrumentation to only non-VM methods at compile time:
>
> if (method.getDeclaringClass().getDescriptor().isBootstrapClassDescriptor())
>
> or
>
> if (method.getDeclaringClass().getDescriptor().isRVMClassDescriptor())
>
> depending on whether or not you want to instrument the Java libraries.
>
> Second, printValue() needs to be @Uninterruptible since the place where
> printValue() is getting inserted probably isn't a GC-safe point. You can add
> the @Uninterruptible annotation to the class or method.
>
> That'll cause a compiler error because uninterruptible methods can only call
> other @Uninterruptible methods, and Object.hashCode() is an interruptible
> method. I suggest calling
>
> RuntimeEntrypoints.getObjectHashCode(o);
>
> or simply
>
> ObjectReference.fromObject(o).toAddress()
>
> depending on what exactly you want to print.
>
> Cheers,
> Mike
>
>
> On 04/22/2013 03:00 PM, Pushparaj Motamari wrote:
>
> Dear All,
>
> I have created a New Class for instrumenting
>
> public class MyPrinter {
>
>      @Entrypoint
>     public static void printValue(Object o){
>          VM.sysWriteln("MyPrinter prints the value as = ", o.hashCode());
>     }
> }
>
> and I call it using
>            asm.emitPUSH_Reg(T0);//Checking the Object Value, by printing it.
>           genParameterRegisterLoad(asm, 1); // pass 1 parameter
>          // asm.comment("Calling the printValueMethod");
>
> asm.emitCALL_Abs(Magic.getTocPointer().plus(Entrypoints.printValueMethod.getOffset()));
>
> and I have added it in EntryPoints.java.
>
> The build getting successful, but when execute I get following exception
>
> Exception in the primordial thread "Jikes_RBoot_Thread" while booting:
> JikesRVM: internal error: recursive use of hardware exception registe    rs
> (exiting)
>   2 -- Stack --
>   3 (0x5807a698 13214)   at [0x5807a698, 0x5b1e3ebd]
> Lorg/jikesrvm/scheduler/RVMThread; terminate()V at line 2661
>   4 (0x5807a6bc 13264)   at [0x5807a6bc, 0x5b344a74]
> Lorg/jikesrvm/scheduler/RVMThread;
> handleUncaughtException(Ljava/lang/Throwable;)V at line     4663
>   5 (0x5807a6e0 8747)   at [0x5807a6e0, 0x5b344d0f]
> Lorg/jikesrvm/runtime/RuntimeEntrypoints;
> handleUncaughtException(Ljava/lang/Throwable;)V at     line 1071
>   6 (0x5807a730 8746)   at [0x5807a730, 0x5b345b39]
> Lorg/jikesrvm/runtime/RuntimeEntrypoints;
> deliverException(Ljava/lang/Throwable;Lorg/jikesrv
> m/ArchitectureSpecific$Registers;)V at line 1066
>   7 (0x5807a774 8734)   at [0x5807a774, 0x5b0162eb]
> Lorg/jikesrvm/runtime/RuntimeEntrypoints; deliverHardwareException(II)V at
> line 796
>   8 (0x5807a790 1)   at [0x5807a790, 0x5b0162eb] <hardware trap>
>   9 (0x5807a924 10587)   at [0x5807a924, 0x5b016847]
> Lorg/jikesrvm/classloader/Atom; toUnicodeStringInternal()Ljava/lang/String;
>  10 (0x5807a948 10582)   at [0x5807a948, 0x5b33e6b9]
> Lorg/jikesrvm/classloader/Atom; hashCode()I at line 887
>  11 (0x5807a96c 3686)   at [0x5807a96c, 0x5b016388]
> Lorg/jikesrvm/objectmodel/MyPrinter; printValue(Ljava/lang/Object;)V at line
> 11
>  12 (0x5807a994 10587)   at [0x5807a994, 0x5b016847]
> Lorg/jikesrvm/classloader/Atom; toUnicodeStringInternal()Ljava/lang/String;
> at line 277
>  13 (0x5807a9b8 10582)   at [0x5807a9b8, 0x5b33e6b9]
> Lorg/jikesrvm/classloader/Atom; hashCode()I at line 887
>  14 (0x5807a9dc 3686)   at [0x5807a9dc, 0x5b016388]
> Lorg/jikesrvm/objectmodel/MyPrinter; printValue(Ljava/lang/Object;)V at line
> 11
>  15 (0x5807aa04 10587)   at [0x5807aa04, 0x5b016847]
> Lorg/jikesrvm/classloader/Atom; toUnicodeStringInternal()Ljava/lang/String;
> at line 277
>  16 (0x5807aa28 10582)   at [0x5807aa28, 0x5b33e6b9]
> Lorg/jikesrvm/classloader/Atom; hashCode()I at line 887
>  17 (0x5807aa4c 3686)   at [0x5807aa4c, 0x5b016388]
> Lorg/jikesrvm/objectmodel/MyPrinter; printValue(Ljava/lang/Object;)V at line
> 11
>  18 (0x5807aa74 10587)   at [0x5807aa74, 0x5b016847]
> Lorg/jikesrvm/classloader/Atom; toUnicodeStringInternal()Ljava/lang/String;
> at line 277
>  19 (0x5807aa98 10582)   at [0x5807aa98, 0x5b33e6b9]
> Lorg/jikesrvm/classloader/Atom; hashCode()I at line 887
>  20 (0x5807aabc 3686)   at [0x5807aabc, 0x5b016388]
> Lorg/jikesrvm/objectmodel/MyPrinter; printValue(Ljava/lang/Object;)V at line
> 11
>  21 (0x5807aae4 10587)   at [0x5807aae4, 0x5b016847]
> Lorg/jikesrvm/classloader/Atom; toUnicodeStringInternal()Ljava/lang/String;
> at line 277
>  22 (0x5807ab08 10582)   at [0x5807ab08, 0x5b33e6b9]
> Lorg/jikesrvm/classloader/Atom; hashCode()I at line 887
>
> Please explain the reason for the above behaviour.
>
> Thanks & Regards
> Pushparaj
>
>
> On Mon, Apr 22, 2013 at 4:46 AM,
> <[email protected]> wrote:
>>
>> Send Jikesrvm-researchers mailing list submissions to
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>>
>>
>> Today's Topics:
>>
>>    1. Re: Potential issues with longjmp in bootImageRunner (Carl Ritson)
>>    2. Doubts Regarding Jikes Stack Layout for BaseLine  Compiler
>>       (Pushparaj Motamari)
>>    3. Re: Doubts Regarding Jikes Stack Layout for BaseLine Compiler
>>       (Michael Bond)
>>    4. Trying to learn garbage collection (Thai, Richard P)
>>    5. Error building the MMTk test harness (Dallas Treder)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Mon, 15 Apr 2013 18:22:35 +0100
>> From: Carl Ritson <[email protected]>
>> Subject: Re: [rvm-research] Potential issues with longjmp in
>>         bootImageRunner
>> To: "General discussion of Jikes RVM design, implementation, issues,
>>         and plans" <[email protected]>
>> Message-ID:
>>
>> <CAKDym5PTd0tjO2RA3G22vFpoVNRsAhu77ZUiT-keEJeKwwPOpA@mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> >>> There are a number of approaches to dealing with this:
>> >>>  1. assume allocation will always be top-down and ignore,
>> >>>  2. explicitly allocate thread stacks (these can be passed to
>> >>> pthread_create),
>> >>>  3. replace use of setjmp/longjmp with savecontext/swapcontext
>> >>> (although these are deprecated in POSIX),
>> >>>  4. implement a local version of longjmp without a check,
>> >>>  5. bypass the __longjmp_chk by using glibc's internal
>> >>> __libc_longjmp().
>> >>>
>> >>> Disregarding (1), (5) is the smallest change set.
>> >>
>> >> I'd also disregard (1). (3) and (4) don't seem attractive to me; we
>> >> ought to rely on non-deprecated methods from the system libraries as
>> >> much as possible.
>> >
>> > My opinion is (3) the best option as (2) requires the bootImageRunner
>> > to allocate memory at a specific place in memory and manage it
>> > (because thread heap will need to be freed).  Instead of
>> > reimplementing setjmp/longjmp completely, bootThread already has to be
>> > implemented in machine specific assembly to pivot the stack when
>> > entering the VM, the existing code should hence be extended to allow
>> > for pivoting back onto the thread stack.  In effect bootThread should
>> > return when sysThreadTerminate is called.
>>
>> It has been pointed out to me that where I said (3), I meant (4).  I
>> agree that the use of deprecated APIs is not a good option.  An
>> possible extension to (2) is to use the explicitly allocated stacks
>> from inside the VM and entirely bypass the allocated of thread stacks
>> in C/C++.  Although issues regarding the primordial thread would still
>> need to be addressed.
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Fri, 19 Apr 2013 23:48:44 +0530
>> From: Pushparaj Motamari <[email protected]>
>> Subject: [rvm-research] Doubts Regarding Jikes Stack Layout for
>>         BaseLine        Compiler
>> To: [email protected]
>> Message-ID:
>>
>> <CAKO14CXwKhX-ksvBwLB__ooq9Za4kjJziDuMC56=nvNDduWTHQ@mail.gmail.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Dear all,
>>
>> I would like to know how to print the current value of a register . Like
>> asm.comment("Text");
>> when I try to print asm.comment(SP) ,it is just printing as ESP ..
>> when I execute the command ..rvm -X:base:mc=true
>>
>> Thank You
>>
>> Pushparaj Motamari
>> Instituto Superior Technico -Portugal
>> -------------- next part --------------
>> An HTML attachment was scrubbed...
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Sun, 21 Apr 2013 13:00:41 -0400
>> From: Michael Bond <[email protected]>
>> Subject: Re: [rvm-research] Doubts Regarding Jikes Stack Layout for
>>         BaseLine Compiler
>> To: [email protected]
>> Message-ID: <[email protected]>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Hi Pushparaj,
>>
>> asm.comment(...) performs *compile-time* printing. It can't know the
>> run-time value of SP.
>>
>> To print the run-time value of SP, you can do something like the
>> following:
>>
>> (1) Create an "instrumentation" method in some class (like
>> RuntimeEntrypoints) that will get called from the compiled code:
>>
>>    @Entrypoint
>>    static void myInstrumentation(Address value) {
>>      VM.sysWriteln("Run-time value = ", value);
>>    }
>>
>> (2) Add a field to Entrypoints that's a handle to the above
>> instrumentation method.
>>
>> (3) Wherever you're currently modifying the baseline compiler to try to
>> print SP, do something like this:
>>
>>      asm.emitPUSH_Reg(SP);
>>      genParameterRegisterLoad(asm, 1);
>>
>> asm.emitCALL_Abs(Magic.getTocPointer().plus(Entrypoints.myInstrumentationMethod.getOffset()));
>>
>> That'll generate code that calls your instrumentation method at run
>> time, with one parameter: the run-time value of SP.
>>
>> Cheers,
>> Mike
>>
>> On 04/19/2013 02:18 PM, Pushparaj Motamari wrote:
>> > Dear all,
>> >
>> > I would like to know how to print the current value of a register . Like
>> > asm.comment("Text");
>> > when I try to print asm.comment(SP) ,it is just printing as ESP ..
>> > when I execute the command ..rvm -X:base:mc=true
>> >
>> > Thank You
>> >
>> > Pushparaj Motamari
>> > Instituto Superior Technico -Portugal
>> >
>> >
>> >
>> > ------------------------------------------------------------------------------
>> > Precog is a next-generation analytics platform capable of advanced
>> > analytics on semi-structured data. The platform includes APIs for
>> > building
>> > apps and a phenomenal toolset for data science. Developers can use
>> > our toolset for easy data analysis & visualization. Get a free account!
>> > http://www2.precog.com/precogplatform/slashdotnewsletter
>> >
>> >
>> > _______________________________________________
>> > Jikesrvm-researchers mailing list
>> > [email protected]
>> > https://lists.sourceforge.net/lists/listinfo/jikesrvm-researchers
>>
>> -------------- next part --------------
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>> ------------------------------
>>
>> Message: 4
>> Date: Sun, 21 Apr 2013 23:05:20 +0000
>> From: "Thai, Richard P" <[email protected]>
>> Subject: [rvm-research] Trying to learn garbage collection
>> To: "[email protected]"
>>         <[email protected]>
>> Cc: csse402 <[email protected]>
>> Message-ID:
>>
>> <D87E325A4A461248B6BB5AF8CC7F6282B03D3201@exchmb-tel-1.rose-hulman.edu>
>>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> I'm currently trying my hand at making a garbage collector in MMTk and
>> I've followed the tutorial on adding a new GC
>> (http://jikesrvm.org/Adding+a+New+GC). I've also peppered logs throughout
>> the classes and methods of the new GC I've created, but I don't think I can
>> really follow what's happening after running the tests.
>>
>> For one, I've set the properties file to utilize bitmap marking
>> (config.mmtk.headerMarkBit=true) in the BaseBaseMarkSweepTuned.properties
>> file and it doesn't seem to achieve anything.
>>
>> Another thing, the log files outputted are incredibly large. There's no
>> discernible pattern among the methods that are called. I notice a lot of the
>> alloc/postAlloc calls in the mutator, getPagesUsed, etc, but the file is too
>> large for me to clearly understand it all.
>>
>> Would anyone have any advice as to a better way towards understanding how
>> GC's operate in this system? At least well enough so that I can reasonably
>> affect the files when creating my own. In addition, would anyone know how to
>> enable bitmap marking with the built-in MarkSweep collector?
>>
>> Best Regards,
>> Richard
>> -------------- next part --------------
>> An HTML attachment was scrubbed...
>>
>> ------------------------------
>>
>> Message: 5
>> Date: Sun, 21 Apr 2013 19:16:46 -0400
>> From: Dallas Treder <[email protected]>
>> Subject: [rvm-research] Error building the MMTk test harness
>> To: jikesrvm-researchers <[email protected]>
>> Message-ID:
>>
>> <CAFVMK+qnkbsKw_V7Aqqgi-vaqAVFzHktUxCgrEvhKVgU8Vb4JQ@mail.gmail.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> I am following the guides located in the
>> http://jikesrvm.org/Care+and+Feeding section of the website, and have
>> gotten the RVM configured and built, but when I got to the
>> http://jikesrvm.org/The+MMTk+Test+Harness guide, and ran the ant
>> mmtk-harness command, I got the following error:
>>
>> Buildfile: /home/csse/trash-man/jikesrvm/build.xml
>>
>> compile-vmmagic-stub:
>>
>> compile-options:
>>     [mkdir] Created dir:
>> /home/csse/trash-man/jikesrvm/target/options/classes
>>     [javac] Compiling 10 source files to
>> /home/csse/trash-man/jikesrvm/target/options/classes
>>
>> compile-mmtk:
>>
>> ensure-javacc:
>>
>> prepare-ant-tasks:
>>     [mkdir] Created dir:
>> /home/csse/trash-man/jikesrvm/target/tasks/classes
>>     [javac] Compiling 16 source files to
>> /home/csse/trash-man/jikesrvm/target/tasks/classes
>>     [javac] Note:
>>
>> /home/csse/trash-man/jikesrvm/tools/ant-tasks/src/org/jikesrvm/tools/template/GenerateFromTemplate.java
>> uses unchecked or unsafe operations.
>>     [javac] Note: Recompile with -Xlint:unchecked for details.
>> Trying to override old definition of task truncate
>>
>> ensure:
>>      [echo] javacc does not exist or is of the wrong version.
>> Rebuilding...
>>
>> prepare-ant-tasks:
>>
>> init-javacc-properties:
>>
>> fetch:
>>     [mkdir] Created dir:
>> /home/csse/trash-man/jikesrvm/components/javacc/4.0
>>      [echo] Downloading (no cache available)
>>       [get] Getting:
>>
>> http://java.net/projects/javacc/downloads/download/oldversions/javacc-4.0.zip
>>       [get] To:
>> /home/csse/trash-man/jikesrvm/components/javacc/4.0/javacc-4.0.zip
>>       [get]
>>
>> http://java.net/projects/javacc/downloads/download/oldversions/javacc-4.0.zip
>> moved
>> to
>>
>> https://java.net/projects/javacc/downloads/download/oldversions/javacc-4.0.zip
>>       [get]
>>
>> https://java.net/projects/javacc/downloads/download/oldversions/javacc-4.0.zip
>> moved
>> tohttp://java.net/downloads/javacc/oldversions/javacc-4.0.zip
>>
>> BUILD FAILED
>> /home/csse/trash-man/jikesrvm/build.xml:442: The following error occurred
>> while executing this line:
>> /home/csse/trash-man/jikesrvm/build/components/javacc.xml:50: The
>> following
>> error occurred while executing this line:
>> /home/csse/trash-man/jikesrvm/build/components/base.xml:70: The following
>> error occurred while executing this line:
>> /home/csse/trash-man/jikesrvm/build/components/base.xml:76: The following
>> error occurred while executing this line:
>> /home/csse/trash-man/jikesrvm/build/components/javacc.xml:40: The
>> following
>> error occurred while executing this line:
>> /home/csse/trash-man/jikesrvm/build/components/base.xml:110: The following
>> error occurred while executing this line:
>> /home/csse/trash-man/jikesrvm/build/components/base.xml:118: Redirection
>> detected from https to http. Protocol switch unsafe, not allowed.
>>
>> I am running this on a Ubuntu 12.10 x32 machine, running OpenJDK 1.6. If
>> there is any more information I can provide, please let me know.
>> -------------- next part --------------
>> An HTML attachment was scrubbed...
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>> ------------------------------
>>
>>
>> ------------------------------------------------------------------------------
>> Precog is a next-generation analytics platform capable of advanced
>> analytics on semi-structured data. The platform includes APIs for building
>> apps and a phenomenal toolset for data science. Developers can use
>> our toolset for easy data analysis & visualization. Get a free account!
>> http://www2.precog.com/precogplatform/slashdotnewsletter
>>
>> ------------------------------
>>
>> _______________________________________________
>> Jikesrvm-researchers mailing list
>> [email protected]
>> https://lists.sourceforge.net/lists/listinfo/jikesrvm-researchers
>>
>>
>> End of Jikesrvm-researchers Digest, Vol 83, Issue 13
>> ****************************************************
>
>
>
>
> ------------------------------------------------------------------------------
> Precog is a next-generation analytics platform capable of advanced
> analytics on semi-structured data. The platform includes APIs for building
> apps and a phenomenal toolset for data science. Developers can use
> our toolset for easy data analysis & visualization. Get a free account!
> http://www2.precog.com/precogplatform/slashdotnewsletter
>
>
>
> _______________________________________________
> Jikesrvm-researchers mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/jikesrvm-researchers
>
>
>
> ------------------------------------------------------------------------------
> Precog is a next-generation analytics platform capable of advanced
> analytics on semi-structured data. The platform includes APIs for building
> apps and a phenomenal toolset for data science. Developers can use
> our toolset for easy data analysis & visualization. Get a free account!
> http://www2.precog.com/precogplatform/slashdotnewsletter
> _______________________________________________
> Jikesrvm-researchers mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/jikesrvm-researchers
>

------------------------------------------------------------------------------
Precog is a next-generation analytics platform capable of advanced
analytics on semi-structured data. The platform includes APIs for building
apps and a phenomenal toolset for data science. Developers can use
our toolset for easy data analysis & visualization. Get a free account!
http://www2.precog.com/precogplatform/slashdotnewsletter