Hi guys,

So I found out the exact method that is causing the VM crash. If I compile the method with Opal, it crashes the VM when I execute the code that use that method. If I compile it with old compiler, the code does work correctly.��

I tried comparing both compiled methods compiled from both Compilers and I cannot see real differences. They both seem to have similar (same?) bytecodes, literals, decompiled string, etc. The only difference I see is in #frameSize (old compiler one is 16 while Opal one is 56).��
Any idea what else can I check/compare?��

I also tried in Pharo 5.0 but same results.��

Thanks in advance,��


On Mon, Nov 16, 2015 at 2:48 PM, Mariano Martinez Peck <marianopeck@gmail.com> wrote:


On Mon, Nov 16, 2015 at 2:48 PM, Mariano Martinez Peck <marianopeck@gmail.com> wrote:


On Mon, Nov 16, 2015 at 1:07 PM, Nicolai Hess <nicolaihess@gmail.com> wrote:
��
Hi Mariano, if you know the method that may cause this crash can you check
if it works if you recompile this method with the old compiler,
maybe this issue is responsible - wrong stack frame size :
13854 frameSize calculated wrongly for #lineSegmentsDo:


Hi Nicolai,

Thanks for the pointer. I tried with your fix and I still get the same results (even after recompiling).
However...if I swap back to old Compiler rather than OpalCompiler and I recompile everything, then I do not have anymore the crash.��
So it's definitively something related to Opal compilation, and probably, related to closures compilation.��
I will see if I find other opal issues opened in 4.0.

Thanks!
��


2015-11-16 17:00 GMT+01:00 Mariano Martinez Peck <marianopeck@gmail.com>:
��
Hi guys,

I am debugging a Pharo VM crash I am having and I cannot figure out what it is exactly. I suspect it might be related to block closures compilation but I am not sure. I have a reproducible crash test under Pharo 4.0 and OSX.��

I built a VM in debug mode and I run it via gdb. This is the kind of info I am able to see:

Program received signal SIGSEGV, Segmentation fault.
0x000ab66b in updatePointersInRangeFromto (memStart=924623948, memEnd=928201420) at /Users/mariano/Pharo/git/pharo-vm/src/vm/gcc3x-cointerp.c:40444
40444 && (((longAt(fieldOop)) & MarkBit) != 0)) {
(gdb) call printAllStacks()
Process 0x30e228c4 priority 40
0xbffb2e10 M FaAction class>block: 0x20ebb104: a(n) FaAction class
0xbffb2e30 M BlockClosure(FaMemoryStoreSession)>register: 0x371d0968: a(n) BlockClosure
0xbffb2e4c M INVALID RECEIVER>register: 0x371cfd54: a(n) bad class

(callerContextOrNil == (nilObject())) || (isContext(callerContextOrNil)) 48626
0x3721e1f0 is not a context
0x371c34b4 is not a context

And another crash:

Program received signal SIGSEGV, Segmentation fault.
0x000ab66b in updatePointersInRangeFromto (memStart=924677864, memEnd=928262300) at /Users/mariano/Pharo/git/pharo-vm/src/vm/gcc3x-cointerp.c:40444
40444 && (((longAt(fieldOop)) & MarkBit) != 0)) {
(gdb) call printAllStacks()
Process 0x30e228c4 priority 40
0xbffb2de0 M INVALID RECEIVER>initialize 0x3722b9a0: a(n) bad class
0xbffb2df8 M FaAction class(Behavior)>new 0x20ebb104: a(n) FaAction class
0xbffb2e10 M FaAction class>block: 0x20ebb104: a(n) FaAction class
0xbffb2e30 M INVALID RECEIVER>register: 0x371ddee0: a(n) bad class
0xbffb2e4c M INVALID RECEIVER>register: 0x371dd328 is in old space

(callerContextOrNil == (nilObject())) || (isContext(callerContextOrNil)) 48626
0x3722b750 is not a context
[New Thread 0x1b43 of process 5886]
[New Thread 0x1d2f of process 5886]
[New Thread 0x1f07 of process 5886]
[New Thread 0x1e07 of process 5886]

From what I can see in #printActivationNameFor: aMethod receiver: anObject isBlock: isBlock firstTemporary: maybeMessage
It looks like if the memory address is not an OOP, nor forwarding pointer nor...

It also seems like the above stack I can get is not the real cause but a side effect that makes GC to crash (#updatePointersInRangeFromto)

As said, I have a way to reproduce the crash, and I already have the VM compiled in debug and gdb running. I can also attach the full output of the gdb stack.��

BTW.... in the output of the gdb I see lots of printings like:

(numStack + ReceiverIndex) < (lengthOf(theContext)) 45421
(ReceiverIndex + contextSize) < (lengthOfbaseHeaderformat(oop, header2, fmt)) 40416


Any pointer is appreciated.

Thanks!

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Mariano
http://marianopeck.wordpress.com