manuranga / ir-gen-uom

Take-home task for the compiler lecture

Task

You are writing a compiler for a new programming language. Assume frontend is already implemented and provides you following records as input to your backend. Your task is to produce the given IR.

Hardcoded version of codeGen function is provided in the main.bal file. Modify the codeGen function to generate the IR form the input.

Spec

Input (source, not important for the task, but for your understanding):

def fib(n):
    if n < 2:
        return n
    else:
        return fib(n - 1) + fib(n - 2)

Input (form frontend):

{ name: "fib",
  params: ["%n"],
  stmts: [ { kind: "if",
             cond: { kind: "lessThan", ops: ["%n", 2] },
             thenStmts: [{ kind: "return", ops: ["%n"] }],
             elseStmts: [{ kind: "return", ops: [
                         { kind: "add", ops: [
                             { kind: "call", name: "fib", ops: [{ kind: "subtract", ops: ["%n", 1] }] },
                             { kind: "call", name: "fib", ops: [{ kind: "subtract", ops: ["%n", 2] }] } ] } ] }] }

Expected Output:

{ name: "fib",
  params: ["%n"],
  vars: ["%lessThan2", "%nSub1", "%nSub2", "%fib1", "%fib2", "%result"],
  blocks: { "entry": {
                insns: [
                    { kind: "lessThan", op: ["%n", 2], result: "%lessThan2" },
                    { kind: "jumpIf", op:["%lessThan2"], ifTrue: "ifCase", ifFalse: "elseCase" } ] },
            "ifCase": {
                insns: [
                    { kind: "return", op: ["%n"] } ] },
            "elseCase": {
                insns: [
                    { kind: "subtract", op: ["%n", 1], result: "%nSub1" },
                    { kind: "subtract", op: ["%n", 2], result: "%nSub2" },
                    { kind: "call", name:"fib", op: ["%nSub1"], result: "%fib1" },
                    { kind: "call", name:"fib", op: ["%nSub2"], result: "%fib2" },
                    { kind: "add", op: ["%fib1", "%fib2"], result: "%result" },
                    { kind: "return", op: ["%result"] } ] } } }

Test

Run bal test to test

Bonus

Write a test case for Euclid's algorithm and make it pass