[llvm-dev] Using isConfused() method for LLVM Dependence Analysis

[Bodhisatwa via llvm-dev]

Hi,

I am trying to find out instances of confused dependencies in my 
program. According to LLVM's doxygen page, 'confused dependencies' are 
detected by function isConfused() - Returns true if this dependence is 
confused (the compiler understands nothing and makes worst-case 
assumptions) 
(http://llvm.org/doxygen/classllvm_1_1Dependence.html#a5c65e22ef4b0368ab040d1bd4ead382d)


For the following code snippet:

   for (int i = 0; i < 10; i++)
    {
        a = 1;
        for (int j = 0; j < 9; j++)
           {
              b = 2;
              for (int k = 0; k < 8; k++)
                 {
                      c = 3;
                 }
           }
    }
We are constructing dependencies between the corresponding IR of the 
above code and checking whether it is confused or not:

   store i32 1, i32* @a, align 4
   store i32 2, i32* @b, align 4
Confused Dependence or Not: 1

Since the variables 'a' and 'b' are in different memory locations, why 
is LLVM's isConfused method gives us True?
-- 
Bodhisatwa