Implement global load elimination based on flow engine.

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

Index: test/mjsunit/compiler/load-elimination-osr.js
diff --git a/test/mjsunit/regress/regress-crbug-260345.js b/test/mjsunit/compiler/load-elimination-osr.js
similarity index 66%
copy from test/mjsunit/regress/regress-crbug-260345.js
copy to test/mjsunit/compiler/load-elimination-osr.js
index 75832ab4beb9e004dda914ffc2e23647f57ef979..a57fe173ee7be04313ca7ea2c18229e23fa16375 100644
--- a/test/mjsunit/regress/regress-crbug-260345.js
+++ b/test/mjsunit/compiler/load-elimination-osr.js
@@ -25,35 +25,41 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-var steps = 100000;
-var undefined_values = [undefined, "go on"];
-var null_values = [null, "go on"];
+// Flags: --allow-natives-syntax --load-elimination
 
-function get_undefined_object(i) {
-  return undefined_values[(i / steps) | 0];
-}
+// Test global load elimination in the presence of OSR compilation.
+
+function It(x, y) { }
 
-function test_undefined() {
-  var objects = 0;
-  for (var i = 0; i < 2 * steps; i++) {
-    undefined == get_undefined_object(i) && objects++;
+function foo_osr(x, limit) {
+  var o = new It();
+  o.x = x;
+  o.y = x;
+  for (var i = 0; i < limit; i++) {
+    o.y += o.x;  // Load of x cannot be hoisted due to OSR.
   }
-  return objects;
-}
 
-assertEquals(steps, test_undefined());
+  return o.y;
+}
 
+assertEquals(22, foo_osr(11, 1));
+assertEquals(24, foo_osr(12, 1));
+assertEquals(1300013, foo_osr(13, 100000));
 
-function get_null_object(i) {
-  return null_values[(i / steps) | 0];
-}
 
-function test_null() {
-  var objects = 0;
-  for (var i = 0; i < 2 * steps; i++) {
-    null == get_null_object(i) && objects++;
+function foo_hot(x, limit) {
+  var o = new It();
+  o.x = x;
+  o.y = x;
+  for (var i = 0; i < limit; i++) {
+    o.y += o.x;  // Load of x can be hoisted without OSR.
   }
-  return objects;
+
+  return o.y;
 }
 
-assertEquals(steps, test_null());
+assertEquals(22, foo_hot(11, 1));
+assertEquals(24, foo_hot(12, 1));
+%OptimizeFunctionOnNextCall(foo_hot);
+assertEquals(32, foo_hot(16, 1));
+assertEquals(1300013, foo_hot(13, 100000));