[Vm-dev] [COG] primitiveClosureValue assert is failing with StackVM (possible BUG in bytecodes!!)

Eliot Miranda eliot.miranda at gmail.com
Wed Dec 22 21:34:14 UTC 2010


Hi Mariano,

    indeed it's a bug.  Your fix (objectMemory is: rcvr instanceOf: (self
splObj: ClassBlockClosure) compactClassIndex: ClassBlockClosureCompactIndex)
is the correct one.  There are a few other places where this needs to be
done also.  I'll roll out new code soon.

best
Eliot

On Wed, Dec 22, 2010 at 12:03 PM, Mariano Martinez Peck <
marianopeck at gmail.com> wrote:

>
> Hi Eliot. If I compile a StackVM, and I just press the left arrow in a code
> pane of a OB windows, in a pharo image, I get an asser that fails:
> (oop & 1) 19202
>
> Sorry I bother with these asserts, but I am trying to solve the crashes I
> have and I think starting for the asserts is a good idea.
>
> The assert that fails is in primitiveClosureValue()  the part:
>
> blockClosure = longAt(GIV(stackPointer) + (GIV(argumentCount) *
> BytesPerWord));
>     /* begin quickFetchInteger:ofObject: */
>     oop = longAt((blockClosure + BaseHeaderSize) + (ClosureNumArgsIndex <<
> ShiftForWord));
>     assert((oop & 1));
>     numArgs = (oop >> 1);
>     if (!(GIV(argumentCount) == numArgs)) {
>         /* begin primitiveFail */
>         if (GIV(primFailCode) == 0) {
>             GIV(primFailCode) = 1;
>         }
>         return;
>     }
>
>
> numArgs results to be a large number (using #printNum:   was 718613205),
> and if I try to do a #printOop:  I got a " 0x55aa55aa0x55aa55aa is not on
> the heap"
>
> Now, of course, the "if (!(GIV(argumentCount) == numArgs)) " fails.
>
> What it is funny is that I did a #printOop: of blockClosure instVar, and
> this is what I get:  0x1f59b578: a(n) Association
>
> Association? WTF ?   so...I guess something weird is happening. I continue
> debugging it..and I noticed that:
>
> - Several classes were called in addition to Association,like Character.
> These seems to be compact classes and implement #value and #value:   ;)
> - Both, #bytecodePrimValue and #bytecodePrimValueWithArg  were not calling
> #primitiveClosureValue. So, "isBlock" was false...
>
> I tried modifying #bytecodePrimValueWithArg and #bytecodePrimValue  this
> line:
>
> isBlock := objectMemory is: rcvr instanceOf: ClassBlockClosurecompactClassIndex: ClassBlockClosureCompactIndex.
>
> to this one:
>
> isBlock := objectMemory is: rcvr instanceOf: (self splObj:
> ClassBlockClosure) compactClassIndex: ClassBlockClosureCompactIndex.
>
> WIth this change, at least, the assert doesn't fail anymore. I made
> progress (maybe). But still, for normal closures, "isBlock" seems to be
> false. So.....all block values are being managed as a normal send ????
>
> Now, I don't understand why ClassBlockClosureCompactIndex  is 0. I think
> this may be the problem. Why it is not 12? (in Pharo  Smalltalk
> compactClassesArray at: 12 ->>> BlockClosure.)
> I notice that ObjectMemory >> initializeCompactClassIndices  does:
>
>     ClassBlockClosureCompactIndex := 0 "12". "Prospective.  Currently
> TranslatedMethod class"
>
>
> Notice that this ZERO changes the sematic of #is: oop instanceOf: classOop
> compactClassIndex: compactClassIndex
> called from the #bytecodePrimValue and bytecodePrimValueWithArg
>
> Finally, I changed the mentioned line to this:
>
> isBlock := objectMemory is: rcvr instanceOf: (self splObj:
> ClassBlockClosure) compactClassIndex: 12.
>
> and finally, with block closures, it is calling the primitive, and for
> Association it doesn't fail the assert.  ahh and the image doesn't crash ;)
>
> I don't know if this is a bug, if my solution was ok, nor it impact. Please
> let me know.
>
> Cheers
>
> Mariano
>
>
>
>
>
>
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