dart2js cps: Global value numbering and loop-invariant code motion.

pkg/compiler/lib/src/cps_ir/type_mask_system.dart

Index: pkg/compiler/lib/src/cps_ir/type_mask_system.dart
diff --git a/pkg/compiler/lib/src/cps_ir/type_mask_system.dart b/pkg/compiler/lib/src/cps_ir/type_mask_system.dart
index a36f2843e8bd3d1f7a768a7acc0c4073e15a5509..4c1eb432c23f80161c7da0abd1f4116e4d9b30a0 100644
--- a/pkg/compiler/lib/src/cps_ir/type_mask_system.dart
+++ b/pkg/compiler/lib/src/cps_ir/type_mask_system.dart
@@ -162,15 +162,16 @@ class TypeMaskSystem {
   }
 
   TypeMask getParameterType(ParameterElement parameter) {
-    return inferrer.getGuaranteedTypeOfElement(parameter);
+    return inferrer.getGuaranteedTypeOfElement(parameter) ?? dynamicType;

[sra1, 2015/11/17 05:41:15]

Why are these functions returning null?

[asgerf, 2015/11/17 12:43:43]

I can't reproduce it anymore so I've reverted the null checks.

   }
 
   TypeMask getReturnType(FunctionElement function) {
-    return inferrer.getGuaranteedReturnTypeOfElement(function);
+    return inferrer.getGuaranteedReturnTypeOfElement(function) ?? dynamicType;
   }
 
   TypeMask getInvokeReturnType(Selector selector, TypeMask mask) {
     TypeMask result = inferrer.getGuaranteedTypeOfSelector(selector, mask);
+    if (result == null) return dynamicType;
     // Tearing off .call from a function returns the function itself.
     if (selector.isGetter &&
         selector.name == Identifiers.call &&
@@ -181,7 +182,7 @@ class TypeMaskSystem {
   }
 
   TypeMask getFieldType(FieldElement field) {
-    return inferrer.getGuaranteedTypeOfElement(field);
+    return inferrer.getGuaranteedTypeOfElement(field) ?? dynamicType;
   }
 
   TypeMask join(TypeMask a, TypeMask b) {
@@ -195,7 +196,7 @@ class TypeMaskSystem {
   }
 
   TypeMask getTypeOf(ConstantValue constant) {
-    return computeTypeMask(inferrer.compiler, constant);
+    return computeTypeMask(inferrer.compiler, constant) ?? dynamicType;
   }
 
   // Returns the constant value if a TypeMask represents a single value.
@@ -347,8 +348,12 @@ class TypeMaskSystem {
   }
 
   bool areDisjoint(TypeMask leftType, TypeMask rightType) {
-    TypeMask intersection = leftType.intersection(rightType, classWorld);
-    return intersection.isEmpty && !intersection.isNullable;
+    TypeMask intersected = intersection(leftType, rightType);
+    return intersected.isEmpty && !intersected.isNullable;
+  }
+
+  bool isMorePreciseOrEqual(TypeMask t1, TypeMask t2) {
+    return t2.containsMask(t1, classWorld);
   }
 
   AbstractBool isSubtypeOf(TypeMask value,