Improve precision of range analysis by allowing it to track ranges across all int typed phis.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index 7ee32da5ebee6dbcae21f98ca4f9df6fd311b470..f5cb877e7eae6ba3bdb44dc4654fa06e16aa24d9 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -158,6 +158,13 @@ class CompileType : public ValueObject {
     return (cid_ == kIllegalCid) && (type_ == NULL);
   }
 
+  bool IsInt() {
+    return !is_nullable() &&
+      ((ToCid() == kSmiCid) ||
+       (ToCid() == kMintCid) ||
+       ((type_ != NULL) && (type_->Equals(Type::Handle(Type::IntType())))));
+  }
+
   void PrintTo(BufferFormatter* f) const;
   const char* ToCString() const;
 
@@ -4679,6 +4686,8 @@ class UnboxUint32Instr : public UnboxInteger32Instr {
         && (value()->Type()->ToCid() != kMintCid);
   }
 
+  virtual void InferRange(RangeAnalysis* analysis, Range* range);
+
   DECLARE_INSTRUCTION_NO_BACKEND(UnboxUint32)
 
  private:
@@ -7524,6 +7533,11 @@ class UnboxedIntConverterInstr : public TemplateDefinition<1, NoThrow> {
 
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
+  virtual CompileType ComputeType() const {
+    // TODO(vegorov) use range information to improve type.
+    return CompileType::Int();
+  }
+
   DECLARE_INSTRUCTION(UnboxedIntConverter);
 
  private: