Implement global load elimination based on flow engine.

test/mjsunit/compiler/load-elimination-global.js

Index: test/mjsunit/compiler/load-elimination-global.js
diff --git a/test/mjsunit/compiler/load-elimination.js b/test/mjsunit/compiler/load-elimination-global.js
similarity index 62%
copy from test/mjsunit/compiler/load-elimination.js
copy to test/mjsunit/compiler/load-elimination-global.js
index e019508c65ebdc9eb08e03979f81b70633f55319..9caaa9f71874b9c8b8f48b3d60bb4bcf2c1bbf75 100644
--- a/test/mjsunit/compiler/load-elimination.js
+++ b/test/mjsunit/compiler/load-elimination-global.js
@@ -27,7 +27,12 @@
 
 // Flags: --allow-natives-syntax --load-elimination
 
-// Test local load elimination of redundant loads and stores.
+// Test global load elimination of redundant loads and stores.
+
+var X = true;  // For forcing branches.
+X = false;
+X = true;
+X = false;
 
 function B(x, y) {
   this.x = x;
@@ -37,33 +42,92 @@ function B(x, y) {
 
 function test_load() {
   var a = new B(1, 2);
-  return a.x + a.x + a.x + a.x;
+  var f = a.x + a.x;
+  if (false) ;
+  return f + a.x + a.x;
+}
+
+function test_load2() {
+  var a = new B(1, 2);
+  var f = a.x + a.x;
+  if (true) ;
+  return f + a.x + a.x;
 }
 
 function test_store_load() {
   var a = new B(1, 2);
   a.x = 4;
-  var f = a.x;
-  a.x = 5;
-  var g = a.x;
-  a.x = 6;
-  var h = a.x;
-  a.x = 7;
-  return f + g + h + a.x;
+  var b = X ? a.x : a.x;
+  return b + a.x;
+}
+
+function test_store_load2() {
+  var a = new B(1, 2);
+  var c = 6;
+  if (X) a.x = c;
+  else a.x = c;
+  return a.x + a.x;
 }
 
 function test_nonaliasing_store1() {
   var a = new B(2, 3), b = new B(3, 4);
+  if (X) ;
   b.x = 4;
+  if (X) ;
   var f = a.x;
+  if (X) ;
   b.x = 5;
+  if (X) ;
   var g = a.x;
+  if (X) ;
   b.x = 6;
+  if (X) ;
   var h = a.x;
+  if (X) ;
   b.x = 7;
+  if (X) ;
   return f + g + h + a.x;
 }
 
+function test_loop(x) {
+  var a = new B(2, 3);
+  var v = a.x;
+  var total = v;
+  var i = 0;
+  while (i++ < 10) {
+    total = a.x;
+    a.y = 4;
+  }
+  return total;
+}
+
+function test_loop2(x) {
+  var a = new B(2, 3);
+  var v = a.x;
+  var total = v;
+  var i = 0;
+  while (i++ < 10) {
+    total = a.x;  // a.x not affected by loop
+    a.y = 4;
+
+    var j = 0;
+    while (j++ < 10) {
+      total = a.x;  // a.x not affected by loop
+      a.y = 5;
+    }
+
+    total = a.x;
+    a.y = 6;
+
+    j = 0;
+    while (j++ < 10) {
+      total = a.x;  // a.x not affected by loop
+      a.y = 7;
+    }
+  }
+  return total;
+}
+
 function killall() {
   try { } catch(e) { }
 }
@@ -72,35 +136,61 @@ function killall() {
 
 function test_store_load_kill() {
   var a = new B(1, 2);
+  if (X) ;
   a.x = 4;
+  if (X) ;
   var f = a.x;
+  if (X) ;
   a.x = 5;
+  if (X) ;
   var g = a.x;
+  if (X) ;
   killall();
+  if (X) ;
   a.x = 6;
+  if (X) ;
   var h = a.x;
+  if (X) ;
   a.x = 7;
+  if (X) ;
   return f + g + h + a.x;
 }
 
 function test_store_store() {
   var a = new B(6, 7);
+  if (X) ;
   a.x = 7;
+  if (X) ;
   a.x = 7;
+  if (X) ;
   a.x = 7;
+  if (X) ;
   a.x = 7;
+  if (X) ;
   return a.x;
 }
 
 function test(x, f) {
+  X = true;
+  assertEquals(x, f());
+  assertEquals(x, f());
+  X = false;
   assertEquals(x, f());
   assertEquals(x, f());
+  X = true;
   %OptimizeFunctionOnNextCall(f);
   assertEquals(x, f());
+  assertEquals(x, f());
+  X = false;
+  assertEquals(x, f());
+  assertEquals(x, f());
 }
 
 test(4, test_load);
-test(22, test_store_load);
+test(8, test_store_load);
+test(12, test_store_load2);
 test(8, test_nonaliasing_store1);
 test(22, test_store_load_kill);
 test(7, test_store_store);
+test(2, test_loop);
+test(2, test_loop2);