v8/test/mjsunit/optimized-reduce.js

// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Flags: --allow-natives-syntax --expose-gc --turbo-inline-array-builtins
// Flags: --opt --no-always-opt

// Unknown field access leads to eager-deopt unrelated to reduce, should still
// lead to correct result.
(() => {
  const a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
  // For this particular eager deopt point to work, we need to dodge
  // TurboFan's soft-deopts through a non-inlined and non-optimized function
  // call to foo().
  function foo(o, deopt) { if (deopt) { o.abc = 3; }}
  %NeverOptimizeFunction(foo);
  function eagerDeoptInCalled(deopt) {
    return a.reduce((r, v, i, o) => {
      if (i === 7) {
        foo(a, deopt);
      }
      return r + "S";
    }, "H");
  }
  %PrepareFunctionForOptimization(eagerDeoptInCalled);
  eagerDeoptInCalled();
  eagerDeoptInCalled();
  %OptimizeFunctionOnNextCall(eagerDeoptInCalled);
  eagerDeoptInCalled();
  assertEquals("HSSSSSSSSSS", eagerDeoptInCalled(true));
})();

// Make sure we gracefully handle the case of an empty array in
// optimized code.
(function() {
  var nothingThere = function(only_holes) {
    var a = [1,2,,3];  // holey smi array.
    if (only_holes) {
      a = [,,,];  // also a holey smi array.
    }
    return a.reduce((r,v,i,o)=>r+v);
  };
  %PrepareFunctionForOptimization(nothingThere);
  nothingThere();
  nothingThere();
  %OptimizeFunctionOnNextCall(nothingThere);
  assertThrows(() => nothingThere(true));
})();

// An error generated inside the callback includes reduce in it's
// stack trace.
(function() {
  var re = /Array\.reduce/;
  var alwaysThrows = function() {
    var b = [,,,];
    var result = 0;
    var callback = function(r,v,i,o) {
      return r + v;
    };
    b.reduce(callback);
  }
  try {
    alwaysThrows();
  } catch (e) {
    assertTrue(re.exec(e.stack) !== null);
  }
  %PrepareFunctionForOptimization(alwaysThrows);
  try { alwaysThrows(); } catch (e) {}
  try { alwaysThrows(); } catch (e) {}
  %OptimizeFunctionOnNextCall(alwaysThrows);
  try {
    alwaysThrows();
  } catch (e) {
    assertTrue(re.exec(e.stack) !== null);
  }
})();