Crash Dump Analysis Patterns (Part 70b)

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In addition to inline function optimization of unmanaged and native code we can see similar approach to JIT-compiled code:

public class ClassMain
{
    public bool time2stop = false;

   
    public static void Main(string[] args)
    {
        new ClassMain().Main();
    }

    public void Main()
    {
        while (!time2stop)
        {
            DoWork();
        }
 
    }

    volatile int inSensor, outSensor;

    void DoWork()
    {
        outSensor ^= inSensor;
    }
}

0:000> kL
ChildEBP RetAddr 
WARNING: Frame IP not in any known module. Following frames may be wrong.
001fefa0 79e7c6cc 0×3200a4
001ff020 79e7c8e1 mscorwks!CallDescrWorkerWithHandler+0xa3
001ff160 79e7c783 mscorwks!MethodDesc::CallDescr+0×19c
001ff17c 79e7c90d mscorwks!MethodDesc::CallTargetWorker+0×1f
001ff190 79eefb9e mscorwks!MethodDescCallSite::Call_RetArgSlot+0×18
001ff2f4 79eef830 mscorwks!ClassLoader::RunMain+0×263
001ff55c 79ef01da mscorwks!Assembly::ExecuteMainMethod+0xa6
001ffa2c 79fb9793 mscorwks!SystemDomain::ExecuteMainMethod+0×43f
001ffa7c 79fb96df mscorwks!ExecuteEXE+0×59
001ffac4 736455ab mscorwks!_CorExeMain+0×15c
001ffad0 73747f16 mscoreei!_CorExeMain+0×38
001ffae0 73744de3 mscoree!ShellShim__CorExeMain+0×99
001ffae8 76573833 mscoree!_CorExeMain_Exported+0×8
001ffaf4 77c1a9bd kernel32!BaseThreadInitThunk+0xe
001ffb34 00000000 ntdll!_RtlUserThreadStart+0×23

0:000> r
eax=00000000 ebx=001fefbc ecx=015316e0 edx=0037a238 esi=0037a238 edi=00000000
eip=003200a4 esp=001fef90 ebp=001fefa0 iopl=0  nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000      efl=00000246
003200a4 80790c00   cmp     byte ptr [ecx+0Ch],0   ds:0023:015316ec=00

0:000> !IP2MD 003200a4
MethodDesc: 000d3048
Method Name: ClassMain.Main()
Class: 000d1180
MethodTable: 000d3060
mdToken: 06000002
Module: 000d2c3c
IsJitted: yes
m_CodeOrIL: 00320098

0:000> .asm no_code_bytes
Assembly options: no_code_bytes

0:000> !U 003200a4
Normal JIT generated code
ClassMain.Main()
Begin 00320098, size 13
00320098 cmp     byte ptr [ecx+0Ch],0
0032009c jne     003200aa

0032009e mov     eax,dword ptr [ecx+4]
003200a1 xor     dword ptr [ecx+8],eax

>>> 003200a4 cmp     byte ptr [ecx+0Ch],0
003200a8 je      0032009e

003200aa ret

We see that DoWork code was inlined into Main function code.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

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