Dynamic Loop Unrolling

Benchmark created by Mario Klingemann on

Description

A potential use case for dynamically unrolling loops at runtime. If you know ahead of time how many iterations you will have this can speed up execution considerably.

Setup

var outerLoops = 100;
    var innerLoops = 16;
    
    var c = ["var plus = function(a, b) {return a + b;};var sum = 0;for (var i = 0; i < " + outerLoops + "; i++) {"];
    for (var i = 1; i <= innerLoops; i++) {
      c[i] = "sum=plus(sum,i);"
    }
    c.push("};return sum;")
    
    var once = Function(c.join(""));
    
    
    var c = ["var plus = function(a, b) {return a + b;};var sum = 0;for (var i = 0; i < " + outerLoops + "; i++) {"];
    for (var i = 1; i <= innerLoops; i++) {
      c[i] = "sum=sum+i;"
    }
    c.push("};return sum;")
    
    var once2 = Function(c.join(""));
    
    var plus = function(a, b) {
      return a + b;
    }

Test runner

Ready to run.

Testing in
TestOps/sec
Loop In Loop
var sum = 0;
for (var i = 0; i < outerLoops; i++) {
  for (var j = 0; j < innerLoops; j++) {
    sum = plus(sum, i);
  }
};
ready
Dynamically Unrolled Loop (Function recreated every test)
var c = ["var plus = function(a, b) {return a + b;};var sum = 0;for (var i = 0; i < " + outerLoops + "; i++) {"];
for (var i = 1; i <= innerLoops; i++) {
  c[i] = "sum=plus(sum,i);"
}
c.push("};return sum;")

var sum = Function(c.join(""))();
ready
Dynamically Unrolled Loop (Function created once)
var sum = once();
ready
Dynamically Unrolled Loop (Function body extracted)
var sum = once2();
ready

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.

  • Revision 1: published by Mario Klingemann on