v8/test/mjsunit/compiler/dead-loops-neg.js

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// Flags: --allow-natives-syntax

// Presents negative opportunities for dead loop removal.

function loop1() {
  while (true) return;
}

function loop2() {
  var i = 0;
  while (i++ < 10) ;
  return i;  // value of {i} escapes.
  // can only remove the loop with induction variable analysis.
}

function loop3() {
  var i = 0;
  for (; i < 10; i++) ;
  return i;  // value of {i} escapes.
  // can only remove the loop with induction variable analysis.
}

function loop4() {
  var a = 0;
  for (var i = 0; i < 10; i++) a++;
  return a;  // value of {a} escapes.
  // can only remove the loop with induction variable analysis.
}

function loop5() {
  var a = new Int32Array(4), sum = 0;
  for (var i = 0; i < a.length; i++) {
    sum += a[i];
  }
  return sum;  // {sum} escapes.
  // can only remove the loop by figuring out that all elements of {a} are 0.
}

function loop6(a) {
  for (var i = 0; i < a; i++) ;  // implicit a.valueOf().
  // can only remove the loop by guarding on the type of a.
}

function loop7(a) {
  for (var i = 0; i < 10; i++) a.toString();  // unknown side-effect on a.
  // can only remove the loop by guarding on the type of a.
}

function loop8(a) {
  for (var i = 0; i < 10; i++) a.valueOf();  // unknown side-effect on a.
  // can only remove the loop by guarding on the type of a.
}

var no_params_loops = [loop1, loop2, loop3, loop4, loop5, loop6];
var params_loops = [loop6, loop7, loop8];

for (var i = 0; i < no_params_loops.length; i++) {
  var f = no_params_loops[i];
  %PrepareFunctionForOptimization(f);
  f();
  f();
  f();
  %OptimizeFunctionOnNextCall(f);
  f();
}

for (var i = 0; i < params_loops.length; i++) {
  var f = params_loops[i];
  %PrepareFunctionForOptimization(f);
  f(3);
  f(7);
  f(11);
  %OptimizeFunctionOnNextCall(f);
  f(9);
}