Profiling Method Arguments; CORDBG_E_IL_VAR_NOT

Profiling Method Arguments; CORDBG_E_IL_VAR_NOT_AVAILABLE

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Wolfinger Reinhard - 16 Oct 2003 09:29 GMT

My CLR Profiler watches Function Entry
and Exit with COR_PRF_MONITOR_ENTERLEAVE
and logs Method Arguments with
ICorDebugILFrame::GetArgument API.

What works:
* in, out, ref Arguments on
FunctionEntry (for void functions)

Doesn`t work:
* Any arguments for non-void functions
* Any arguments on FunctionLeave
* Return Value

Question:
(1) Why does Error
CORDBG_E_IL_VAR_NOT_AVAILABLE occur?
(2) When exactly does mscorwks.dll call
my Enter/Leave-Stubs? Are arguments and
return value already accessible then?
(3) Why the difference in behaviour for
void and non-void functions?

My test methods in a C#-Program:
* static void InParam(int param)
* static int ReturnValue(int param)

Output from CLR Profiler (shortened):
FuncEnter TestSimple.TestSimple:InParam
arg0=333
FuncLeave TestSimple.TestSimple:InParam
arg0=CORDBG_E_IL_VAR_NOT_AVAILABLE
FuncEnter TestSimple.TestSimple:ReturnValue
arg0=CORDBG_E_IL_VAR_NOT_AVAILABLE
FuncLeave TestSimple.TestSimple:ReturnValue
arg0=CORDBG_E_IL_VAR_NOT_AVAILABLE

Help anybody? MSFT?

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Per Larsen - 17 Oct 2003 11:37 GMT

> My CLR Profiler watches Function Entry
> and Exit with COR_PRF_MONITOR_ENTERLEAVE
> and logs Method Arguments with
> ICorDebugILFrame::GetArgument API.

Sounds very interesting. I've written a couple of profilers a while back. I
wanted to try this aspect also but haven't gotten to it yet, so I can't
really offer any authoritative help - just a few pointers.

> What works:
> * in, out, ref Arguments on
> FunctionEntry (for void functions)
>
> Doesn`t work:
> * Any arguments for non-void functions

In what way does it fail, do you get a non-zero HResult, or is the returned
ICorDebugValue interface NULL, or what?

Have you tried using EnumerateArguments instead?

> * Any arguments on FunctionLeave
> * Return Value

It's possible that the arguments are no longer present/viewed as such after
the entry code has executed. What do you get with
GetLocalVariable/EnumerateLocalVariables?

> (2) When exactly does mscorwks.dll call
> my Enter/Leave-Stubs? Are arguments and
> return value already accessible then?

They should be. Actually, it's not mscorwks.dll calling your profiler - it's
the raw JIT'ed code. Here's an excerpt from a profiled routine

// set up stack frame for parameter and locals
push ebp
mov ebp, esp
sub esp, 028h ; '('
push edi
push esi
push ebx
push 036184B0h // <- method cookie
call 0AABDB7Ch // <- enter stub call
// actual code body starts here
mov esi, ecx
lea edi, [ebp-028h]
.....
mov ecx, [ebx+0F4h]
cmp [ecx], ecx
call [03613584h]
// actual code body ends here
push 036184B0h // <- method cookie
call 0AABDBA8h // <- exit stub call
// remove stack frame & return to caller
pop ebx
pop esi
pop edi
mov esp, ebp
pop ebp
ret 04h

My profiler DLL happens to have a preferred load address of 0xAAA00000 as
you can see from the stub call addresses.

- Per

Reply to this Message

Wolfinger Reinhard - 17 Oct 2003 12:18 GMT

> In what way does it fail, do you get a non-zero HResult, or is the returned
> ICorDebugValue interface NULL, or what?

GetArgument returns CORDBG_E_IL_VAR_NOT_AVAILABLE.

> Have you tried using EnumerateArguments instead?

Yes I have tried both. EnumerateArguments returns the Enum with the correct
number of arguments. But when I try to access the enum with ->Next() it
returns CORDBG_E_IL_VAR_NOT_AVAILABLE. Same thing.

> It's possible that the arguments are no longer present/viewed as such after
> the entry code has executed. What do you get with
> GetLocalVariable/EnumerateLocalVariables?

I used both APIs to access the return value which for C# is a local variable
with a generated name prefixed CS$. When Arguments cannot be accessed,
GetLocalVariable/EnumerateLocalVariable also fails. Same HRESULT.

Reinhard

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K_Lee - 19 Oct 2003 16:37 GMT

Check this links to the sscli code and see if it helps.

http://www.slink-software.com/W/SrcDoc_Top/sscli/sscli.sdoc/N_41

sscli.sdoc
Source Code Roadmap:
App Domain
Profiler
ProfToEEInterface - proftoeeinterfaceimpl.h:34
COR_PRF_MONITOR_ENTERLEAVE - profilepriv.h:134
CORDBG_E_IL_VAR_NOT_AVAILABLE - common.cpp:394
CorProfInfo - profile.h:64
ICorProfilerInfo - corprof.h:1889

> > My CLR Profiler watches Function Entry
> > and Exit with COR_PRF_MONITOR_ENTERLEAVE
[quoted text clipped - 62 lines]
>
> - Per

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Profiling Method Arguments; CORDBG_E_IL_VAR_NOT_AVAILABLE

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