[LLVMdev] Dereferencing NULL pointer in IndVarSimplify.cpp? (original) (raw)

Liang Wang netcasper at gmail.com
Fri Oct 17 17:21:12 PDT 2014

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Hi,

Here is the code in IndVarSimplify.cpp.

SmallVector<WeakVH, 16> DeadInsts;

while (!DeadInsts.empty()) if (Instruction *Inst = dyn_cast_or_null(&*DeadInsts.pop_back_val())) RecursivelyDeleteTriviallyDeadInstructions(Inst, TLI);

Since DeadInsts.pop_back_val() is WeakVH which could hold a NULL pointer, the expression, &*DeadInsts.pop_back_val(), could be &*NULL. Then NULL pointer is dereferenced here.

I wrote a small test case and it works just fine. But is this a well-defined behavior in the standard?

Thanks, Liang

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