llvm dev - Dec 2008 - [LLVMdev] Getting the start and end address of JITted code

Here's my problem, which I raised on IRC:

JIT::getPointerToFunction gets the address of the start of a function.
But how do I find out where the end of the function is?  I need this
to register the function for profiling.

varth said: aph, you need to intercept the "endFunctionBody" call on
the memory manager, it will tell you the start pointer and the end
pointer

But how can I do this?  The obvious way would be for me to inherit
from DefaultMemoryManager and pass an instance of my class to
ExecutionEngine::createJIT.  But DefaultMemoryManager isn't public so
I can't inherit from it.  It's not at all obvious to me how I'm
supposed to intercept endFunctionBody.

Thanks,
Andrew.

Nicolas Geoffray wrote:
> Hi Andrew,
> 
> Andrew Haley wrote:
>> Here's my problem, which I raised on IRC:
>>
>> JIT::getPointerToFunction gets the address of the start of a function.
>> But how do I find out where the end of the function is?  I need this
>> to register the function for profiling.
>>
>> varth said: aph, you need to intercept the "endFunctionBody"
call on
>> the memory manager, it will tell you the start pointer and the end
>> pointer
>>   
> 
> Yep, that's what I said :)
> 
>> But how can I do this?  The obvious way would be for me to inherit
>> from DefaultMemoryManager and pass an instance of my class to
>> ExecutionEngine::createJIT.  
> 
> Correct.
> 
>> But DefaultMemoryManager isn't public so
>> I can't inherit from it.  
> 
> You should inherit from JITMemoryManager.
>> It's not at all obvious to me how I'm
>> supposed to intercept endFunctionBody.
> 
> Here's how vmkit does it:
> 
> class MvmMemoryManager : public JITMemoryManager {
>  
>   /// realMemoryManager - The real allocator
>   JITMemoryManager* realMemoryManager;
> 
> public:
>  
>   MvmMemoryManager() : JITMemoryManager() {
>     realMemoryManager = JITMemoryManager::CreateDefaultMemManager();
>   }
> 
> 
> And MvmMemoryManager redefines all the virtual functions to call the 
> real memory manager. For endFunctionBody, it inserts in a map the start 
> and end pointers.
So I have to define *all* the virtual functions and wrap the memory manager
just in order to intercept endFunctionBody?  !!  Sheesh.

Thanks,
Andrew.