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

Eliot Miranda eliot.miranda at gmail.com
Fri Apr 29 17:19:43 UTC 2011 

On Fri, Apr 29, 2011 at 4:31 AM, Luc Fabresse <luc.fabresse at gmail.com>wrote:

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

If you want to find out what there is to document then at the external level
do this:

Cog.app/Contents/MacOS/Croquet -?
unknown option: -?
Usage: Fast.app/Contents/MacOS/Croquet [<option>...] [<imageName>
[<argument>...]]
       Fast.app/Contents/MacOS/Croquet [<option>...] -- [<argument>...]

Common <option>s:
  -help                 print this help message, then exit
  -memory <size>[mk]    use fixed heap size (added to image size)
  -eden <size>[mk]      set eden memory to bytes
  -stackpages num       use n stack pages
  -breaksel selector    set breakpoint on send of selector
  -codesize <size>[mk]  set machine code memory to bytes
  -sendtrace[=num]      enable send tracing (optionally to a specific value)
  -tracestores          enable store tracing (assert check stores)
  -cogmaxlits <n>       set max number of literals for methods compiled to
machine code
  -cogminjumps <n>      set min number of backward jumps for interpreted
methods to be considered for compilation to machine code
  -pathenc <enc>        set encoding for pathnames (default: macintosh)
  -headless             run in headless (no window) mode (default: false)

Notes:
  <imageName> defaults to `Squeak.image'.
  If `-memory' is not specified then the heap will grow dynamically.
  <argument>s are ignored, but are processed by the Squeak image.
  The first <argument> normally names a Squeak `script' to execute.
  Precede <arguments> by `--' to use default image.

In particular "-breaksel selector", "-sendtrace[=num]" & "-tracestores" are
interesting for debugging.

Inside the system you would need to document all the various facilities for
debugging; the print methods in the interpreters, the break-pointing
facilities in the CogVMSimulator et al.  There's a lot there.  I can of
courser help and I have workspaces with various versions of it.  But this
isn't going to be easy to document fully, not least because it changes as
needs require.

best
Eliot


> #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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