Gets the expression that denotes the buffer, along with a textual label for it and an access type.
accessType:
- 1 = buffer range [0, getSize) is accessed entirely.
- 2 = buffer range [0, getSize) may be accessed partially or entirely.
- 3 = buffer is accessed at offset getSize - 1.
- 4 = buffer is accessed with null terminator read protections (does not read past null terminator, regardless of access size)