Core Language

This section describes the core Bril instructions. Any self-respecting Bril tool must support all of these operations; other extensions are more optional.


Core Bril defines two primitive types:

  • int: 64-bit, two’s complement, signed integers.
  • bool: True or false.


These instructions are the obvious binary integer arithmetic operations. They all take two arguments, which must be names of variables of type int, and produce a result of type int:

  • add: x + y.
  • mul: x × y.
  • sub: x - y.
  • div: x ÷ y.

In each case, overflow follows two’s complement rules. It is an error to div by zero.


These instructions compare integers. They all take two arguments of type int and produce a result of type bool:

  • eq: Equal.
  • lt: Less than.
  • gt: Greater than.
  • le: Less than or equal to.
  • ge: Greater than or equal to.


These are the basic Boolean logic operators. They take arguments of type bool and produce a result of type bool:

  • not (1 argument)
  • and (2 arguments)
  • or (2 arguments)


These are the control flow operations. Unlike the value operations above, they take labels and functions in addition to normal arguments.

  • jmp: Unconditional jump. One label: the label to jump to.
  • br: Conditional branch. One argument: a variable of type bool. Two labels: a true label and a false label. Transfer control to one of the two labels depending on the value of the variable.
  • call: Function invocation. Takes the name of the function to call and, as its arguments, the function parameters. The call instruction can be a Value Operation or an Effect Operation, depending on whether the function returns a value.
  • ret: Function return. Stop executing the current activation record and return to the parent (or exit the program if this is the top-level main activation record). It has one optional argument: the return value for the function.

Only call may (optionally) produce a result; the rest appear only as Effect Operations.


  • id: A type-insensitive identity. Takes one argument, which is a variable of any type, and produces the same value (which must have the same type, obvi).
  • print: Output values to the console (with a newline). Takes any number of arguments of any type and does not produce a result.
  • nop: Do nothing. Takes no arguments and produces no result.