Finding LoadInsts that are not affected by external values.

Hi, all.
I am currently trying to find LoadInst, which are not dependent external values (e.g., arguments or Global variable).

int f(int x) {
for (int i = 0; i < 1000; i++) {
x += x * i;
}
return x;
}

For example, in the above code, x is from argument, and i is not.

define i32 @f(i32 %x) #0 {
entry:
%x.addr = alloca i32, align 4
%i = alloca i32, align 4
store i32 %x, i32* %x.addr, align 4
store i32 0, i32* %i, align 4
br label %for.cond

for.cond: ; preds = %for.inc, %entry
%0 = load i32, i32* %i, align 4
%cmp = icmp slt i32 %0, 1000
br i1 %cmp, label %for.body, label %for.end

for.body: ; preds = %for.cond
%1 = load i32, i32* %x.addr, align 4
%2 = load i32, i32* %i, align 4
%mul = mul nsw i32 %1, %2
%3 = load i32, i32* %x.addr, align 4
%add = add nsw i32 %3, %mul
store i32 %add, i32* %x.addr, align 4
br label %for.inc

for.inc: ; preds = %for.body
%4 = load i32, i32* %i, align 4
%inc = add nsw i32 %4, 1
store i32 %inc, i32* %i, align 4
br label %for.cond

for.end: ; preds = %for.cond
%5 = load i32, i32* %x.addr, align 4
ret i32 %5
}

As I can see above, it needs to handle store and load.
I think I can do simple dataflow analysis to do that.
But I wonder whether there is a standard, mature way in LLVM.

// -fsanitize=dataflow
store i16 %21, i16* %2
store i32 %inc, i32* %i, align 4

I thought that this analysis should be implemented in DataFlowSanitizer.
But, it still propagates taint symbol to i.

Is there any standard way to do this?
Thank you.

Best,
Insu Yun.