Abstract: Instrumenting a computer program includes examining an initial intermediate representation of the program, selecting portions of the initial intermediate representation for instrumentation, and instrumenting the portions. Selecting the portions may include choosing portions of the initial intermediate representation corresponding to pointer arithmetic operations, operations that reads memory locations, operations that change memory locations, and/or operations that causes program variables to become defined or undefined within the program. Instrumenting the portions may include adding run time code that provides a user with an indication when a run time error occurs.