Implement graph trimming in ControlReducer.

test/mjsunit/asm/if-reduction.js

+// Copyright 2014 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.
+
+function Module() {
+  "use asm";
+
+  function if0() {
+    var x = 0 ? 11 : 12;
+    return (x == 11) | 0;
+  }
+
+  function if1() {
+    var x = 1 ? 13 : 14;
+    return (x == 13) | 0;
+  }
+
+  function if2() {
+    var x = 0 ? 15 : 16;
+    return (x != 15) | 0;
+  }
+
+  function if3() {
+    var x = 1 ? 17 : 18;
+    return (x != 17) | 0;
+  }
+
+  function if4() {
+    var x = 0 ? 19 : 20;
+    var y = (x == 19) ? 21 : 22;
+    return y;
+  }
+
+  function if5() {
+    var x = 1 ? 23 : 24;
+    var y = (x == 23) ? 25 : 26;
+    return y;
+  }
+
+  function if6() {
+    var x = 0 ? 27 : 28;
+    var y = (x == 27) ? 29 : 30;
+    var z = (y == 29) ? 31 : 32;
+    return z;
+  }
+
+  function if7() {
+    var x = 1 ? 33 : 34;
+    var y = (x == 33) ? 35 : 36;
+    var z = (y == 35) ? 37 : 38;
+    var w = (z == 37) ? 39 : 40;
+    return w;
+  }
+
+  function if8() {
+    if (0) {
+      var x = 0 ? 43 : 44;
+      var y = (x == 43) ? 45 : 46;
+      var z = (y == 45) ? 47 : 48;
+      var w = (z == 47) ? 49 : 50;
+    } else {
+      var x = 1 ? 53 : 54;
+      var y = (x == 53) ? 55 : 56;
+      var z = (y == 55) ? 57 : 58;
+      var w = (z == 57) ? 59 : 60;
+    }
+    return w;
+  }
+
+  return {if0: if0, if1: if1, if2: if2, if3: if3, if4: if4, if5: if5, if6: if6, if7: if7, if8: if8 };
+}
+
+var m = Module();
+assertEquals(0, m.if0());
+assertEquals(1, m.if1());
+assertEquals(1, m.if2());
+assertEquals(0, m.if3());
+assertEquals(22, m.if4());
+assertEquals(25, m.if5());
+assertEquals(32, m.if6());
+assertEquals(39, m.if7());
+assertEquals(59, m.if8());
+
+
+function Spec(a,b) {
+  "use asm";
+
+  var xx = a | 0;
+  var yy = b | 0;
+
+  function f() {
+    if (xx) {
+      var x = yy ? 43 : 44;
+      var y = (x == 43) ? 45 : 46;
+      var z = (y == 45) ? 47 : 48;
+      var w = (z == 47) ? 49 : 50;
+    } else {
+      var x = yy ? 53 : 54;
+      var y = (x == 53) ? 55 : 56;
+      var z = (y == 55) ? 57 : 58;
+      var w = (z == 57) ? 59 : 60;
+    }
+    return w;
+  }
+  return {f: f};
+}
+
+assertEquals(60, Spec(0,0).f());
+assertEquals(59, Spec(0,1).f());
+assertEquals(50, Spec(1,0).f());
+assertEquals(49, Spec(1,1).f());