LLVM Comparing arguments of two functions - c++

Question

Suppose I have:
foo(int a, int b){
bar(a)
}
how would I check if argument a in bar is the same as argument a in foo in the llvm IR(*.ll file) I get something this:
test.ll:
18 ; Function Attrs: nounwind uwtable
19 define i32 #foo(i32 %a, i32 %b) #0 {
20 entry:
21 %a.addr = alloca i32, align 4
22 %b.addr = alloca i32, align 4
23 %f = alloca i32, align 4
24 store i32 %a, i32* %a.addr, align 4
25 store i32 %b, i32* %b.addr, align 4
26 %0 = load i32, i32* %a.addr, align 4
27 %call = call i32 #baz(i32 %0)
28 store i32 %call, i32* %f, align 4
29 %1 = load i32, i32* %f, align 4
30 ret i32 %1
31 }
32

Answer 1

I am assuming that you are only asking if the same variable is passed on to bar or not.
to check that while running on function
runOnFunction(Function &F)
{
Function::ArgumentListType &sArgs = F.getArgumentList();
Function::ArgumentListType::iterator psArg = sArgs.begin();
Function::ArgumentListType::iterator psEndArg = sArgs.end();
/* this will iterate through function arguments */
for ( ;psArg != psEndArg; ++psArg)
{
/* iterate argument uses */
Argument::user_iterator psUSe = psArg->user_begin();
Argument::user_iterator psUSeEnd = psArg->user_end();
for (;psUSe != psUSeEnd ; ++psUSe)
{
/* check if it is call to bar or not */
if (CallInst* psCall = dyn_cast<CallInst>(*psUSe))
//if (const CallInst* psInst = dyn_cast<CallInst>(*psUSe))
{
if(psCall->getCalledFunction()->getName().startswith("bar")
{ // hurray found it, do something
}
}
}
}
}
above code will check if function argument is diractly passed to another function call.