[LLVMdev] Remove function from module

Михаил neonomaly.x at gmail.com
Mon Apr 23 01:49:36 PDT 2012 

Thanks.


I try to delete function like this (rta_IsFunctionVisited.find - set of good functions) :

		// delete dead functions
		for (Module::iterator Fx = M->begin(), FE = M->end(); Fx!=FE; Fx++) {
			if (rta_IsFunctionVisited.find(Fx)==rta_IsFunctionVisited.end()) {
				Fx->replaceAllUsesWith(UndefValue::get(Fx->getType()));
			}
		}

		for (CallGraph::iterator CGN = CG.begin(); CGN!=CG.end(); CGN++) {
			if (rta_IsFunctionVisited.find(CGN->second->getFunction())==rta_IsFunctionVisited.end()) {
				CGN->second->removeAllCalledFunctions();
			}
		}

		for (Module::iterator Fx = M->begin(), FE = M->end(); Fx!=FE;) {
			if (rta_IsFunctionVisited.find(Fx)==rta_IsFunctionVisited.end()) {
				CallGraphNode *CGN = CG.getOrInsertFunction(Fx);
				CG.removeFunctionFromModule(Fx);
				wasChanged=true;
				Fx=M->begin();
			} else Fx++;
		}

		return true;

But I still have a bug:

opt(63981) malloc: *** error for object 0x7ff1394050a0: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
0  libLLVM-3.0.dylib 0x00000001082d7605 _ZL15PrintStackTracePv + 53
1  libLLVM-3.0.dylib 0x00000001082d7c6c _ZL13SignalHandleri + 364
2  libsystem_c.dylib 0x00007fff9152dcfa _sigtramp + 26
3  libsystem_c.dylib 0x00007fff66d6a878 _sigtramp + 18446744072996768664
4  libsystem_c.dylib 0x00007fff9152b84c free + 389
5  libLLVM-3.0.dylib 0x00000001083536b0 __gnu_cxx::new_allocator<std::pair<llvm::WeakVH, llvm::CallGraphNode*> >::deallocate(std::pair<llvm::WeakVH, llvm::CallGraphNode*>*, unsigned long) + 32
6  libLLVM-3.0.dylib 0x000000010835360e std::_Vector_base<std::pair<llvm::WeakVH, llvm::CallGraphNode*>, std::allocator<std::pair<llvm::WeakVH, llvm::CallGraphNode*> > >::_M_deallocate(std::pair<llvm::WeakVH, llvm::CallGraphNode*>*, unsigned long) + 62
7  libLLVM-3.0.dylib 0x00000001083535bd std::_Vector_base<std::pair<llvm::WeakVH, llvm::CallGraphNode*>, std::allocator<std::pair<llvm::WeakVH, llvm::CallGraphNode*> > >::~_Vector_base() + 45
8  libLLVM-3.0.dylib 0x0000000108353509 std::vector<std::pair<llvm::WeakVH, llvm::CallGraphNode*>, std::allocator<std::pair<llvm::WeakVH, llvm::CallGraphNode*> > >::~vector() + 105
9  libLLVM-3.0.dylib 0x0000000108353495 std::vector<std::pair<llvm::WeakVH, llvm::CallGraphNode*>, std::allocator<std::pair<llvm::WeakVH, llvm::CallGraphNode*> > >::~vector() + 21
10 libLLVM-3.0.dylib 0x000000010852be3e llvm::CallGraphNode::~CallGraphNode() + 110
11 libLLVM-3.0.dylib 0x0000000108529d55 llvm::CallGraphNode::~CallGraphNode() + 21
12 libLLVM-3.0.dylib 0x0000000108528468 llvm::CallGraph::destroy() + 264
13 libLLVM-3.0.dylib 0x00000001085295f8 (anonymous namespace)::BasicCallGraph::destroy() + 120
14 libLLVM-3.0.dylib 0x0000000108529379 (anonymous namespace)::BasicCallGraph::releaseMemory() + 25
15 libLLVM-3.0.dylib 0x0000000107bf5d93 llvm::PMDataManager::freePass(llvm::Pass*, llvm::StringRef, llvm::PassDebuggingString) + 179
16 libLLVM-3.0.dylib 0x0000000107bf5c89 llvm::PMDataManager::removeDeadPasses(llvm::Pass*, llvm::StringRef, llvm::PassDebuggingString) + 505
17 libLLVM-3.0.dylib 0x0000000107bf8ee8 llvm::MPPassManager::runOnModule(llvm::Module&) + 1016
18 libLLVM-3.0.dylib 0x0000000107bf949c llvm::PassManagerImpl::run(llvm::Module&) + 172
19 libLLVM-3.0.dylib 0x0000000107bf997d llvm::PassManager::run(llvm::Module&) + 29
20 opt               0x000000010717f057 main + 6903
21 opt               0x000000010716d7b4 start + 52
22 opt               0x0000000000000007 start + 18446744069295646855



Yours sincerely,
Kadysev Mikhail

22.04.2012, в 23:30, Nick Lewycky написал(а):

> Михаил wrote:
>> It is ModulePass with AnalysisUsage of CallGraph
> 
> Ah, then you'll need to update the CallGraph first. Use "CG.removeFunctionFromModule(F);" before deleting it.
> 
> Nick
> 
>> Yours sincerely,
>> Kadysev Mikhail
>> 
>> 22.04.2012, в 5:20, Nick Lewycky написал(а):
>> 
>>> Михаил wrote:
>>>> Thanks, but I replaceAllUsesWith() - works well, but I still get bug in
>>>> eraseFromParent():
>>>> 
>>>> While deleting: i32 (%class.B*, i32)* %_ZN1B1xEi
>>>> An asserting value handle still pointed to this value!
>>>> UNREACHABLE executed at
>>>> /Users/neonomaly/LLVM/LLVM/lib/VMCore/Value.cpp:561!
>>> 
>>> The replaceAllUsesWith + eraseFromParent pattern remains correct, but
>>> there's more to the story than the parts we've focused on. This error
>>> means that there's some other code that is holding a pointer to the
>>> function you tried to delete, but is using AssertingVH to do so, so as
>>> to catch errors exactly like this producing a dangling pointer.
>>> 
>>> The error message doesn't tell us who owns the AssertingVH (indeed,
>>> the asserting-vh doesn't know, much like a pointer doesn't know who
>>> owns it).
>>> 
>>> So, under what circumstance are you doing this deletion? Is it inside
>>> a FunctionPass, or another kind of Pass? Are you using AssertingVH's
>>> or calling other code that is? Such as ValueMap's, or some llvm
>>> analysis pass which stores an AssertingVH?
>>> 
>>> Nick
>>> 
>>>> 
>>>> 
>>>> Yours sincerely,
>>>> Kadysev Mikhail
>>>> 
>>>> 21.04.2012, в 23:45, Nick Lewycky написал(а):
>>>> 
>>>>> Михаил wrote:
>>>>>> How correctly remove function from module?
>>>>>> For example:
>>>>>> 
>>>>>> int f1(int x) {
>>>>>> ...
>>>>>> a = f2(smth);
>>>>>> ...
>>>>>> }
>>>>>> int f2 (int y) {
>>>>>> ...
>>>>>> b = f1(smth);
>>>>>> ...
>>>>>> }
>>>>>> 
>>>>>> I need delete from module both f1 and f2. They haven't uses in other
>>>>>> part of module, but I can't delete them with eraseFromParent, because
>>>>>> they are use each other.
>>>>> 
>>>>> Call X->replaceAllUsesWith(UndefValue::get(X->getType)) before calling
>>>>> X->eraseFromParent().
>>>>> 
>>>>> Nick
>>>> 
>>>> 
>>>> 
>>>> _______________________________________________
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>>>> LLVMdev at cs.uiuc.edu <mailto:LLVMdev at cs.uiuc.edu> http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>> 
>> 
>> 
>> 
>> _______________________________________________
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> 

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