Our website uses cookies to enhance your browsing experience.
Alias analysis is a method of static analysis used to determine whether two or more references (pointers, variable names, array elements) can access the same memory location (object).
Knowledge of this fact allows a static analyzer to detect complex errors, such as unsafe parallel access to shared data (race conditions), incorrect type casting operations, or modification of an object through one reference while it is simultaneously used through another.
The approach to analysis drastically changes depending on the programming language and its memory model.
For example, in C/C++ and unsafe code in C#, a programmer works directly with pointers, while in Java or C# (without unsafe), references are managed by the runtime environment.
One of the key challenges in analysis when working with pointers directly is that aliases can be represented by pointers of different types and refer to the same memory location. This requires the analyzer to track type casting operations.
In this C++ example, an integer variable x is created. A pointer p of int* type stores its address, which is then cast to float* type and assigned to q pointer. Now p and q are aliases for the same memory location but interpret its contents differently.
int x = 10;
int* p = &x;
float* q = reinterpret_cast<float*>(p);In Java, the memory model is different, yet the concept of aliases is still present. In this example, an array x is created in memory, and variables p and q become references to it, making them aliases. Therefore, any modification of the array through one variable will be obvious through the other.
int[] x = { 1, 2, 3 };
int[] p = x;
p[0] = 4;This is another key challenge when working with aliases: tracking changes requires a memory model capable of accounting for accesses to array elements and objects.
0
0
0