Pointer type can be deduced through:
Value* v= i->getOperand(0);
.......
if(PointerType* pt=dyn_cast<PointerType>(v->getType())){
pt->getElementType()->getTypeID();
How can I read the value that this pointer points to?
I is a CallInst.
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ConsistentProgrammer
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You read the content of memory with a `load` instruction, but I have a feeling that's not the answer you're looking for. Could you clarify what exactly are you trying to achieve? – Oak May 12 '14 at 06:59
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@Oak: I have a function that takes two input paramerters. I want to read the values that I pass to this function: e.g. Foo(int i, int j). Void main(){foo(6,7)}... I want to read 6 and 7.... Thanks!! – ConsistentProgrammer May 12 '14 at 08:40
1 Answers
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Given a CallInst, you can get an argument via getArgOperand() or iterate over all of them with arg_operands(). The arguments you get this way are just Values, and you can do anything you can do with other Values on them.
In particular, if those Values are constants, you can get the actual values used in the compiler - see this related stackoverflow question: LLVM get constant integer back from Value*
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The problem i'm facing is how to read from value that is pointed by a pointer value. Thanks :) – ConsistentProgrammer May 12 '14 at 17:03
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@ConsistentProgrammer then isn't this really unrelated to the fact that you're dealing with a `CallInst`? Shouldn't the question just be "how to get a value from a pointer?" – Oak May 12 '14 at 17:05
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I thought there is a way to extract it from a call instruction. – ConsistentProgrammer May 12 '14 at 17:29
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I guess, I'll have to extract it from a store instruction. – ConsistentProgrammer May 12 '14 at 17:37