[machine-operator-reducer] fix float truncation

test/mjsunit/math-52-mul-div.js

 // Copyright 2015 the V8 project authors. All rights reserved.

[titzer, 2015/11/11 21:04:43]

You can use the short version of the copyright header here.

[fedor.indutny, 2015/11/11 21:35:58]

Acknowledged.

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-// Flags: --max-old-space-size=60 --check-handle-count
+// Flags: --allow-natives-syntax --turbo-filter=*
 
-table = [];
+function mul(a, b) {
+  const l = a & 0x3ffffff;
+  const h = b & 0x3ffffff;
 
-for (var i = 0; i < 32; i++) {
- table[i] = String.fromCharCode(i + 0x410);
+  return (l * h) | 0;
 }
 
+function mulAndDiv(a, b) {
+  const l = a & 0x3ffffff;
+  const h = b & 0x3ffffff;
+  const m = l * h;
 
-var random = (function() {
-  var seed = 10;
-  return function() {
-    seed = (seed * 1009) % 8831;
-    return seed;
-  };
-})();
+  const rl = m & 0x3ffffff;
+  const rh = (m / 0x4000000) | 0;
 
-
-function key(length) {
-  var s = "";
-  for (var i = 0; i < length; i++) {
-    s += table[random() % 32];
-  }
-  return '"' + s + '"';
+  return rl | rh;
 }
 
+function overflowMul(a, b) {
+  const l = a | 0;
+  const h = b | 0;
 
-function value() {
-  return '[{' + '"field1" : ' + random() + ', "field2" : ' + random() + '}]';
+  return (l * h) | 0;
 }
 
+function overflowDiv(a, b) {
+  const l = a & 0x3ffffff;
+  const h = b & 0x3ffffff;
+  const m = l * h;
 
-function generate(n) {
-  var s = '{';
-  for (var i = 0; i < n; i++) {
-     if (i > 0) s += ', ';
-     s += key(random() % 10 + 7);
-     s += ':';
-     s += value();
-  }
-  s += '}';
-  return s;
+  return (m / 0x10) | 0;
 }
 
+function nonPowerOfTwoDiv(a, b) {
+  const l = a & 0x3ffffff;
+  const h = b & 0x3ffffff;
+  const m = l * h;
 
-print("generating");
+  return (m / 0x4000001) | 0;
+}
 
-var str = generate(50000);
+function test(fn, a, b) {

[titzer, 2015/11/11 21:04:43]

Can you add a few more inputs, e.g. some pseudo-randomly generated inputs with
ground truth expectations?

[fedor.indutny, 2015/11/11 21:35:58]

Acknowledged.

+  const expected = fn(a, b);
+  fn(1, 2);
+  fn(0, 0);
+  %OptimizeFunctionOnNextCall(fn);
+  const actual = fn(a, b);
 
-print("parsing "  + str.length);
-JSON.parse(str);
+  assertEquals(expected, actual);
+}
 
-print("done");
+test(mul, 0x3ffffff, 0x3ffffff);
+test(mulAndDiv, 0x3ffffff, 0x3ffffff);
+test(overflowMul, 0x4ffffff, 0x4ffffff);
+test(overflowDiv, 0x3ffffff, 0x3ffffff);
+test(nonPowerOfTwoDiv, 0x3ffffff, 0x3ffffff);