Reland of "Steps towards unification of number bitset and range types."

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 4b3a8830a0fff9cbed6694b9588742225d262814..871a3ff9ad36d14a14649beca625e1c66024fef7 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -891,12 +891,12 @@ Type* Typer::Visitor::JSBitwiseXorTyper(Type* lhs, Type* rhs, Typer* t) {
   double rmax = rhs->Max();
   if ((lmin >= 0 && rmin >= 0) || (lmax < 0 && rmax < 0)) {
     // Xor-ing negative or non-negative values results in a non-negative value.
-    return Type::NonNegativeSigned32();
+    return Type::Unsigned31();
   }
   if ((lmax < 0 && rmin >= 0) || (lmin >= 0 && rmax < 0)) {
     // Xor-ing a negative and a non-negative value results in a negative value.
     // TODO(jarin) Use a range here.
-    return Type::NegativeSigned32();
+    return Type::Negative32();
   }
   return Type::Signed32();
 }
@@ -1261,43 +1261,54 @@ Bounds Typer::Visitor::TypeJSLoadNamed(Node* node) {
 // in the graph. In the current implementation, we are
 // increasing the limits to the closest power of two.
 Type* Typer::Visitor::Weaken(Type* current_type, Type* previous_type) {
-  Type::RangeType* previous = previous_type->GetRange();
-  Type::RangeType* current = current_type->GetRange();
-  if (previous != NULL && current != NULL) {
-    double current_min = current->Min()->Number();
-    Handle<Object> new_min = current->Min();
-
-    // Find the closest lower entry in the list of allowed
-    // minima (or negative infinity if there is no such entry).
-    if (current_min != previous->Min()->Number()) {
-      new_min = typer_->integer->AsRange()->Min();
-      for (const auto val : typer_->weaken_min_limits_) {
-        if (val->Number() <= current_min) {
-          new_min = val;
-          break;
-        }
+  // If the types have nothing to do with integers, return the types.
+  if (!current_type->Maybe(typer_->integer) ||
+      !previous_type->Maybe(typer_->integer)) {
+    return current_type;
+  }
+
+  Type* previous_number =
+      Type::Intersect(previous_type, typer_->integer, zone());
+  Type* current_number = Type::Intersect(current_type, typer_->integer, zone());
+  if (!current_number->IsRange() || !previous_number->IsRange()) {
+    return current_type;
+  }
+
+  Type::RangeType* previous = previous_number->AsRange();
+  Type::RangeType* current = current_number->AsRange();
+
+  double current_min = current->Min()->Number();
+  Handle<Object> new_min = current->Min();
+
+  // Find the closest lower entry in the list of allowed
+  // minima (or negative infinity if there is no such entry).
+  if (current_min != previous->Min()->Number()) {
+    new_min = typer_->integer->AsRange()->Min();
+    for (const auto val : typer_->weaken_min_limits_) {
+      if (val->Number() <= current_min) {
+        new_min = val;
+        break;
       }
     }
+  }
 
-    double current_max = current->Max()->Number();
-    Handle<Object> new_max = current->Max();
-    // Find the closest greater entry in the list of allowed
-    // maxima (or infinity if there is no such entry).
-    if (current_max != previous->Max()->Number()) {
-      new_max = typer_->integer->AsRange()->Max();
-      for (const auto val : typer_->weaken_max_limits_) {
-        if (val->Number() >= current_max) {
-          new_max = val;
-          break;
-        }
+  double current_max = current->Max()->Number();
+  Handle<Object> new_max = current->Max();
+  // Find the closest greater entry in the list of allowed
+  // maxima (or infinity if there is no such entry).
+  if (current_max != previous->Max()->Number()) {
+    new_max = typer_->integer->AsRange()->Max();
+    for (const auto val : typer_->weaken_max_limits_) {
+      if (val->Number() >= current_max) {
+        new_max = val;
+        break;
       }
     }
-
-    return Type::Union(current_type,
-                       Type::Range(new_min, new_max, typer_->zone()),
-                       typer_->zone());
   }
-  return current_type;
+
+  return Type::Union(current_type,
+                     Type::Range(new_min, new_max, typer_->zone()),
+                     typer_->zone());
 }