[LLVMdev] VmKit - Error in j3/precompiler after a big surgery to MMTk part

[Yi Lin]

Hi,

I replaced the MMTk code with a C-version MMTk code (I have been working 
on such AOT compiler for a while). The compiler should deal with most of 
the MMTk code base correctly - at least I get marksweep running with a 
tiny client). So I am trying to put the C version MMTk back with VmKit. 
I tried not to change much existing code except where necessary, such as 
name mangling and MMTkObject layout.

I am having the following error during building VmKit:

    [vmkit ./tools/trainer]: Pre-compiling bootstrap code
    Thread 0x110000000 received a SIGSEGV: either the VM code or an external
    native method is bogus. Aborting...
    Aborted
    make[1]: ***
    [/home/yilin/vmkit/vmkit/tools/trainer/Release+Asserts/Precompiled.bc]
    Error 134
    [vmkit .]: abort with error in ./tools/trainer
    make: *** [all] Error 1

The stacktrace from gdb is:

    Program received signal SIGSEGV, Segmentation fault.
    [Switching to Thread 0x1100ff700 (LWP 21670)]
    0x000000000107b180 in llvm::BumpPtrAllocator::Allocate(unsigned
    long, unsigned long) ()
    (gdb) bt
    #0  0x000000000107b180 in llvm::BumpPtrAllocator::Allocate(unsigned
    long, unsigned long) ()
    #1  0x00000000005ae35d in
    j3::JavaMethod::marshalArguments(vmkit::ThreadAllocator&,
    __va_list_tag*) ()
    #2  0x00000000005b04e4 in j3::JavaObject*
    j3::JavaMethod::invokeStaticAP<j3::JavaObject*, j3::JavaObject*
    (*)(j3::JavaConstantPool*, void*, void*)>(j3::Jnjvm*, j3::Class*,
    __va_list_tag*) ()
    #3  0x00000000005af054 in
    j3::JavaMethod::invokeJavaObjectStatic(j3::Jnjvm*, j3::Class*, ...) ()
    #4  0x00000000005cb662 in j3::Jnjvm::asciizToStr(char const*) ()
    #5  0x00000000005cbde4 in j3::Jnjvm::CreateArithmeticException() ()
    #6  0x00007ffff7f6316d in ?? ()
    #7  0x0000000000000000 in ?? ()

The main thread was waiting in "vmkit::VirtualMachine::waitForExit() 
()", so the application (HelloWorld) should have been started.

1. To me, the stack trace seems not showing where the original error 
happened. It seems an arithmetic error happened somewhere, VM was trying 
to throw an exception, but met another error. Is this correct? And how 
can I track where that actual error happened?

2. What does the precompiler do? I dont quite understand why it is 
needed here.

Any information would be very helpful. Thanks very much.

Regards,
Yi
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