[Vm-dev] Cog and #commonSend are getting me crazy :(

Fri Apr 29 11:31:15 UTC 2011

yes clearly.
some doc on tools and hints for VM debugging.
It is particularly hard and interesting ;-)

#Luc

2011/4/29 stephane ducasse <stephane.ducasse at gmail.com>

>
> Mariano can you document that somewhere :)
>
> On Apr 28, 2011, at 11:59 PM, Mariano Martinez Peck wrote:
>
> > Hi Eliot. Thanks for answering. Your answer was EXTREMELY useful. Not
> only because it helped me to solve the problem I was having, but also
> because I discovered a wonderful tool.
> >
> > You are smart :)  I like the solution. So, if I understood correctly, I
> can put a breakpoint in the function warning() with "break warning". With
> the -breaksel  parameter you set an instVar with the selector name and size.
> Then after, anywhere I can send  #compilationBreak: selectorOop point:
> selectorLength   and that will magically check whether the selectorOop is
> the one I passes with -breaksel and if true, it will call warning, who has a
> breakpoint, hence, I can debug :)   AWESOME!!!!   Now with CMake I can even
> generate a xcode project and debug it :)  (I don't know why attaching gdb
> from Xcode crash the vm).
> >
> > One little comment....I have an error using Cocoa VM builds because
> sqMacUnixCommandLineInterface.c  is only for /platforms/MacOS   and not for
> /platforms/IOS/
> > I am not sure how this should be integrated in Cocoa branch.
> >
> > Thanks Eliot, I like having a kind of #haltIf: in the vm :)
> >
> > Mariano
> >
> >
> > On Thu, Apr 28, 2011 at 7:00 PM, Eliot Miranda <eliot.miranda at gmail.com>
> wrote:
> >
> > Mariano,
> >
> >     here's a hint.  Look at the command-line argument breaksel and see
> where it is used.  This will call warning whenever a specific message is
> sent.  e.g.
> >
> > McStalker.macbuild$ gdb Debug.app/
> > GNU gdb 6.3.50-20050815 (Apple version gdb-1515) (Sat Jan 15 08:33:48 UTC
> 2011)
> > Copyright 2004 Free Software Foundation, Inc.
> > GDB is free software, covered by the GNU General Public License, and you
> are
> > welcome to change it and/or distribute copies of it under certain
> conditions.
> > Type "show copying" to see the conditions.
> > There is absolutely no warranty for GDB.  Type "show warranty" for
> details.
> > This GDB was configured as "x86_64-apple-darwin"...Reading symbols for
> shared libraries ................ done
> >
> > (gdb) break warning
> > Breakpoint 1 at 0x105e2b: file
> /Users/eliot/Cog/oscogvm/macbuild/../src/vm/gcc3x-cointerp.c, line 39.
> > (gdb) run -breaksel initialize ~/Squeak/Squeak4.2/trunk4.2.image
> > Starting program:
> /Users/eliot/Cog/oscogvm/macbuild/Debug.app/Contents/MacOS/Croquet -breaksel
> initialize ~/Squeak/Squeak4.2/trunk4.2.image
> > Reading symbols for shared libraries
> .+++++++++++++++.....................................................................................
> done
> > Reading symbols for shared libraries . done
> >
> > Breakpoint 1, warning (s=0x16487c "send breakpoint (heartbeat
> suppressed)") at
> /Users/eliot/Cog/oscogvm/macbuild/../src/vm/gcc3x-cointerp.c:39
> > 39              printf("\n%s\n", s);
> > (gdb) where 5
> > #0  warning (s=0x16487c "send breakpoint (heartbeat suppressed)") at
> /Users/eliot/Cog/oscogvm/macbuild/../src/vm/gcc3x-cointerp.c:39
> > #1  0x0010b490 in interpret () at
> /Users/eliot/Cog/oscogvm/macbuild/../src/vm/gcc3x-cointerp.c:4747
> > #2  0x0011d521 in enterSmalltalkExecutiveImplementation () at
> /Users/eliot/Cog/oscogvm/macbuild/../src/vm/gcc3x-cointerp.c:14103
> > #3  0x00124bc7 in initStackPagesAndInterpret () at
> /Users/eliot/Cog/oscogvm/macbuild/../src/vm/gcc3x-cointerp.c:17731
> > #4  0x00105ec9 in interpret () at
> /Users/eliot/Cog/oscogvm/macbuild/../src/vm/gcc3x-cointerp.c:1933
> > (More stack frames follow...)
> >
> > On Thu, Apr 28, 2011 at 5:26 AM, Mariano Martinez Peck <
> marianopeck at gmail.com> wrote:
> >
> > Hi Eliot. I am fighting since several hours with something in Cog and I
> cannot realize it. I am blind.
> >
> > I need to intercept all messages sent to an object. I have already done
> this for Interpreter VM and for StackVM. Now,  I am trying latest CogMTVM,
> and there is something I am not sying...I have this test:
> >
> > testBlah
> >
> >     ClassWith1Var new fooLong.
> >     ClassWith1Var new fooLong.
> >     ClassWith1Var new fooLong.
> >
> >
> > ClassWith1Var >> fooLong
> >     | aaa |
> >     Object new.
> >     self foo.
> >
> >
> > Now, I modified
> >
> > CoInterpreter >> commonSend
> >     "Send a message, starting lookup with the receiver's class."
> >     "Assume: messageSelector and argumentCount have been set, and that
> >     the receiver and arguments have been pushed onto the stack,"
> >     "Note: This method is inlined into the interpreter dispatch loop."
> >     <sharedCodeNamed: 'commonSend' inCase: 131>
> >     self sendBreak: messageSelector + BaseHeaderSize
> >         point: (objectMemory lengthOf: messageSelector)
> >         receiver: (self internalStackValue: argumentCount).
> >     cogit recordSendTrace ifTrue:
> >         [self recordTrace: lkupClass thing: messageSelector source:
> TraceIsFromInterpreter].
> >     self internalFindNewMethod.
> >     self print: 'called: '; printStringOf: messageSelector; cr.
> >     self internalExecuteNewMethod.
> >     self fetchNextBytecode
> >
> >
> > And when running the VM from gdb, 'called: fooLong'  doesn't appear at
> all!!!  why ?
> > In addition, it appears 'called: foo' which is correct because #fooLong
> sends #foo
> > but it appears only ONCE.
> >
> > #fooLong as I can see is not a quick return method but instead it goes by
> #sendLiteralSelector0ArgsBytecode. But the same happens if I put the print
> in that method... (which makes sense).
> > I tried with a StackVM and the same....so it seems that #fooLong is going
> by another place than #commonSend.
> >
> > As far as I understand, there is nothing related with PIC or Jitt. In any
> of those cases, as what I can see, the #commonSend is called anyways.
> >
> > So...I am completly lost.
> >
> > Thanks in advance for any help.
> >
> > --
> > Mariano
> > http://marianopeck.wordpress.com
> >
> >
> >
> >
> >
> >
> >
> > --
> > Mariano
> > http://marianopeck.wordpress.com
> >
>
>
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