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songlh at cs.wisc.edu

2011-Jan-26 21:00 UTC

[LLVMdev] [LLVMDEV]How could I get function name in this situation?

> On 1/26/11 2:40 PM, songlh at cs.wisc.edu wrote:
>> thanks!
>>
>> After I check the ll file, I find this:
>>
>> %1 = load %struct.nsAString** %aBuf_addr, align 4, !dbg !2048
>> %2 = getelementptr inbounds %struct.nsAString* %1, i32 0, i32 0, !dbg
>> !2048
>> %3 = getelementptr inbounds %struct.nsISupports* %2, i32 0, i32 0, !dbg
>> !2048
>> %4 = load i32 (...)*** %3, align 4, !dbg !2048
>> %5 = getelementptr inbounds i32 (...)** %4, i32 10, !dbg !2048
>> %6 = load i32 (...)** %5, align 1, !dbg !2048
>> %7 = bitcast i32 (...)* %6 to void (%struct.nsAString*, i32)*, !dbg
>> !2048
>> %8 = load %struct.nsAString** %aBuf_addr, align 4, !dbg !2048
>> call void %7(%struct.nsAString* %8, i32 0) nounwind, !dbg !2048
>>
>> The last line is the CallInst I find.
>>
>> I feel it is using memory address to get the function. Is there someway
>> I
>> can do this in my c++ code??
>
> Yes, the code is loading a pointer to a function from memory and calling
> it.
>
> I don't understand your question, though.
>
> -- John T.
>
I mean how do I realize this in a c++ pass code?

thanks a lot!

           Linhai
>> thanks a lot!
>>
>>> On 1/26/11 2:07 PM, songlh at cs.wisc.edu wrote:
>>>> Hi:
>>>>
>>>>     My llvm code is:
>>>>
>>>>     for( BasicBlock::iterator i = b->begin() , ie =
b->end();
>>>>          b != be ; b ++ ){
>>>>          if( CallInst * pCall = dyn_cast<CallInst>(i)){
>>>>
>>>>             pCall->dump(); //
>>>>             Function * pFunction =
pCall->getCalledFunction();
>>>>             if( !pFunction ){
>>>>
>>>>             }
>>>>             std::string fname = pFunction->getName();
>>>>          }
>>>>     }
>>>>
>>>>     The dump result of the function call I want to find is :
>>>>
>>>>     call void %7(%struct.nsAString* %8, i32 0) nounwind, !dbg
!1565
>>> This is a call using a function pointer.  There is no function name
to
>>> retrieve.  You can check the called value
(pcall->getCalledValue()) and
>>> see if it's something like a cast instruction that casts a
constant
>>> function value, but that case is probably unlikely.
>>>
>>> -- John T.
>>>
>>>>     it returns null from pCall->getCalledFunction(), and I
cannot get
>>>> the
>>>> function name.
>>>>
>>>>     How could I get the function name in this situation?
>>>>
>>>>     thanks a lot!
>>>>
>>>>                                           Linhai
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>
>
>

John Criswell

2011-Jan-26 21:03 UTC

head link

[LLVMdev] [LLVMDEV]How could I get function name in this situation?

On 1/26/11 3:00 PM, songlh at cs.wisc.edu wrote:>> On 1/26/11 2:40 PM, songlh at cs.wisc.edu wrote:
>>> thanks!
>>>
>>> After I check the ll file, I find this:
>>>
>>> %1 = load %struct.nsAString** %aBuf_addr, align 4, !dbg !2048
>>> %2 = getelementptr inbounds %struct.nsAString* %1, i32 0, i32 0,
!dbg
>>> !2048
>>> %3 = getelementptr inbounds %struct.nsISupports* %2, i32 0, i32 0,
!dbg
>>> !2048
>>> %4 = load i32 (...)*** %3, align 4, !dbg !2048
>>> %5 = getelementptr inbounds i32 (...)** %4, i32 10, !dbg !2048
>>> %6 = load i32 (...)** %5, align 1, !dbg !2048
>>> %7 = bitcast i32 (...)* %6 to void (%struct.nsAString*, i32)*, !dbg
>>> !2048
>>> %8 = load %struct.nsAString** %aBuf_addr, align 4, !dbg !2048
>>> call void %7(%struct.nsAString* %8, i32 0) nounwind, !dbg !2048
>>>
>>> The last line is the CallInst I find.
>>>
>>> I feel it is using memory address to get the function. Is there
someway
>>> I
>>> can do this in my c++ code??
>> Yes, the code is loading a pointer to a function from memory and
calling
>> it.
>>
>> I don't understand your question, though.
>>
>> -- John T.
>>
> I mean how do I realize this in a c++ pass code?
You're still not making sense.  Are you asking what sort of C++ code 
will generate the use of a function pointer when compiled into LLVM IR, 
or are you asking how to determine, within an LLVM pass, what the 
possible target(s) of an indirect function call might be?

-- John T.
> thanks a lot!
>
>             Linhai
>
>>> thanks a lot!
>>>
>>>> On 1/26/11 2:07 PM, songlh at cs.wisc.edu wrote:
>>>>> Hi:
>>>>>
>>>>>      My llvm code is:
>>>>>
>>>>>      for( BasicBlock::iterator i = b->begin() , ie =
b->end();
>>>>>           b != be ; b ++ ){
>>>>>           if( CallInst * pCall =
dyn_cast<CallInst>(i)){
>>>>>
>>>>>              pCall->dump(); //
>>>>>              Function * pFunction =
pCall->getCalledFunction();
>>>>>              if( !pFunction ){
>>>>>
>>>>>              }
>>>>>              std::string fname = pFunction->getName();
>>>>>           }
>>>>>      }
>>>>>
>>>>>      The dump result of the function call I want to find is
:
>>>>>
>>>>>      call void %7(%struct.nsAString* %8, i32 0) nounwind,
!dbg !1565
>>>> This is a call using a function pointer.  There is no function
name to
>>>> retrieve.  You can check the called value
(pcall->getCalledValue()) and
>>>> see if it's something like a cast instruction that casts a
constant
>>>> function value, but that case is probably unlikely.
>>>>
>>>> -- John T.
>>>>
>>>>>      it returns null from pCall->getCalledFunction(),
and I cannot get
>>>>> the
>>>>> function name.
>>>>>
>>>>>      How could I get the function name in this situation?
>>>>>
>>>>>      thanks a lot!
>>>>>
>>>>>                                            Linhai
>>>>>
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>

songlh at cs.wisc.edu

2011-Jan-26 21:06 UTC

head link

[LLVMdev] [LLVMDEV]How could I get function name in this situation?

> On 1/26/11 3:00 PM, songlh at cs.wisc.edu wrote:
>>> On 1/26/11 2:40 PM, songlh at cs.wisc.edu wrote:
>>>> thanks!
>>>>
>>>> After I check the ll file, I find this:
>>>>
>>>> %1 = load %struct.nsAString** %aBuf_addr, align 4, !dbg !2048
>>>> %2 = getelementptr inbounds %struct.nsAString* %1, i32 0, i32
0, !dbg
>>>> !2048
>>>> %3 = getelementptr inbounds %struct.nsISupports* %2, i32 0, i32
0,
>>>> !dbg
>>>> !2048
>>>> %4 = load i32 (...)*** %3, align 4, !dbg !2048
>>>> %5 = getelementptr inbounds i32 (...)** %4, i32 10, !dbg !2048
>>>> %6 = load i32 (...)** %5, align 1, !dbg !2048
>>>> %7 = bitcast i32 (...)* %6 to void (%struct.nsAString*, i32)*,
!dbg
>>>> !2048
>>>> %8 = load %struct.nsAString** %aBuf_addr, align 4, !dbg !2048
>>>> call void %7(%struct.nsAString* %8, i32 0) nounwind, !dbg !2048
>>>>
>>>> The last line is the CallInst I find.
>>>>
>>>> I feel it is using memory address to get the function. Is there
>>>> someway
>>>> I
>>>> can do this in my c++ code??
>>> Yes, the code is loading a pointer to a function from memory and
>>> calling
>>> it.
>>>
>>> I don't understand your question, though.
>>>
>>> -- John T.
>>>
>> I mean how do I realize this in a c++ pass code?
>
> You're still not making sense.  Are you asking what sort of C++ code
> will generate the use of a function pointer when compiled into LLVM IR,
> or are you asking how to determine, within an LLVM pass, what the
> possible target(s) of an indirect function call might be?
>
> -- John T.
Sorry, I am asking the second question.
"
how to determine, within an LLVM pass, what the
possible target(s) of an indirect function call might be?
"

thanks a lot!

Linhai>
>> thanks a lot!
>>
>>             Linhai
>>
>>>> thanks a lot!
>>>>
>>>>> On 1/26/11 2:07 PM, songlh at cs.wisc.edu wrote:
>>>>>> Hi:
>>>>>>
>>>>>>      My llvm code is:
>>>>>>
>>>>>>      for( BasicBlock::iterator i = b->begin() , ie =
b->end();
>>>>>>           b != be ; b ++ ){
>>>>>>           if( CallInst * pCall =
dyn_cast<CallInst>(i)){
>>>>>>
>>>>>>              pCall->dump(); //
>>>>>>              Function * pFunction =
pCall->getCalledFunction();
>>>>>>              if( !pFunction ){
>>>>>>
>>>>>>              }
>>>>>>              std::string fname =
pFunction->getName();
>>>>>>           }
>>>>>>      }
>>>>>>
>>>>>>      The dump result of the function call I want to
find is :
>>>>>>
>>>>>>      call void %7(%struct.nsAString* %8, i32 0)
nounwind, !dbg !1565
>>>>> This is a call using a function pointer.  There is no
function name
>>>>> to
>>>>> retrieve.  You can check the called value
(pcall->getCalledValue())
>>>>> and
>>>>> see if it's something like a cast instruction that
casts a constant
>>>>> function value, but that case is probably unlikely.
>>>>>
>>>>> -- John T.
>>>>>
>>>>>>      it returns null from
pCall->getCalledFunction(), and I cannot
>>>>>> get
>>>>>> the
>>>>>> function name.
>>>>>>
>>>>>>      How could I get the function name in this
situation?
>>>>>>
>>>>>>      thanks a lot!
>>>>>>
>>>>>>                                            Linhai
>>>>>>
>>>>>> _______________________________________________
>>>>>> LLVM Developers mailing list
>>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>
>
>

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