What is aliasing and how does it affect performance?

Question

At the GoingNative event, during the Interactive Panel on Day2 at the 9 minute mark, Chandler Carruth says:

Pointers create aliasing problems. They slow d

Answer 1

a pointer is a value that represents a memory address sometimes 2 pointers can represent the same memory address thats what aliasing is

int * p;
*p = 5;

int * alias;
alias = p;

the variable alias is an alias of p and *alias is equal to 5 if you change *alias then *p changes along with it