data hazard

datahazard.js

const STAGES = { IF: 1, ID: 2, EX: 3, MEM: 4, WB: 5 };

const removeParentheses = (str) => str.replace(/.*\(|\)/g, "");
const printRed = (text) => process.stdout.write(`\x1b[31m${text}\x1b[0m`);

function detectDataHazards(instructions) {
  let destStage;  
  process.stdout.write("\n\n---------------------TEST----------------------\n");
  const hazards = instructions.map(() => Array(3).fill(null));

  instructions.forEach((curr, i) => {
    const [_, currDest, currSrc1, currSrc2] = curr;

    instructions.slice(0, i).forEach((prev, j) => {
      // const [__, prevDest] = prev;
      const [prevOp, prevDest, prevSrc1, prevSrc2] = prev;

      [currSrc1, currSrc2]
        .filter((src) => src)
        .forEach((src, k) => {
          // is src is immediate value
          if (src[0] === "#") return;

          src = removeParentheses(src);
          if (prevOp === "lw") {
            destStage = STAGES.MEM;
          } else if (["add", "sub", "addi", "or", "and"].includes(prevOp)) {
            destStage = STAGES.WB;
          }

          if (src === prevDest && j + destStage >= i + STAGES.ID) {
            hazards[i][k + 1] = hazards[j][0] = true;
            printRed(
              `\n${src} is read in CC ${
                i + STAGES.ID
              } (in ins:${i}), but written in CC ${j + destStage} (in ins:${j})`
            );
          }
        });
    });
  });

  // Print instructions with hazards
  instructions.forEach((inst, i) => {
    process.stdout.write(`\n${i}: ${inst[0]}`);
    inst.slice(1).forEach((val, j) => {
      if (val === null) return;
      hazards[i][j] ? printRed(` ${val}`) : process.stdout.write(` ${val}`);
    });
  });
}

// Test cases
const tests = [
  [
    ["add", "$s0", "$t1", "$t2"],
    ["sub", "$t2", "$s0", "$t3"],
  ],
  [
    ["lw", "$s0", "20($t1)", null],
    ["sub", "$t2", "$s0", "$t3"],
  ],
  [
    ["lw", "$t1", "0($t0)", null],
    ["lw", "$t2", "4($t0)", null],
    ["add", "$t3", "$t1", "$t2"],
    ["sw", "$t3", "12($t0)", null],
    ["lw", "$t4", "8($t0)", null],
    ["add", "$t5", "$t1", "$t4"],
    ["sw", "$t5", "16($t0)", null],
  ],
  [
    ["lw", "$t1", "0($t0)", null],
    ["lw", "$t2", "4($t0)", null],
    ["lw", "$t4", "8($t0)", null],
    ["add", "$t3", "$t1", "$t2"],
    ["sw", "$t3", "12($t0)", null],
    ["add", "$t5", "$t1", "$t4"],
    ["sw", "$t5", "16($t0)", null],
  ],
  [
    ["add", "$t1", "$t0", "$t0"],
    ["addi", "$t2", "$t0", "#5"],
    ["addi", "$t4", "$t1", "#5"],
  ],
  [
    ["sub", "$2", "$1", "$3"],
    ["and", "$12", "$2", "$5"],
    ["or", "$13", "$6", "$2"],
    ["add", "$14", "$2", "$2"],
    ["sw", "$14", "100($2)", null],
  ],
];

tests.forEach(detectDataHazards);