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node.jsv8

Node.js %OptimizeFunctionOnNextCall - Runtime Function Error

I am running Node v11.x.x, and receiving an error for a V8 runtime function.

let operand = 3;
function square() {
    return operand * operand;
}
square()
%OptimizeFunctionOnNextCall(square);
square()

Running with:

node --allow-natives-syntax -trace_opt -trace_deopt main.js

Recieving an error of 

ReferenceError: OptimizeFunctionOnNextCall is not defined

I thought this runtime function was still included, or am I doing something wrong.

Solution

  • It's because you're relying on automatic semicolon insertion by Javascript (which fails your intention).

    Your code without ; translates to modulo operation which is a valid JavaScript operation so it has no reason to add a ; for you after the first call square().

    square() % OptimizeFunctionOnNextCall(square);

    Written this way (as JavaScript sees), it obviously looks like modulo operation. Now it's obvious why OptimizeFunctionOnNextCall is undefined.

    Change your code to (Notice the ;):

    let operand = 3;
function square() {
  return operand * operand;
}
square(); // <-- here
%OptimizeFunctionOnNextCall(square);
square();

    Here is a nice read by T.J. Crowder (SO user) on why you should not miss ;