Allow bound check elimination to eliminate checks when both array length and index boundaries are e…

runtime/vm/intermediate_language.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 1589 matching lines @@
 
   static RangeBoundary OverflowedMaxSmi() {
     return FromConstant(Smi::kMaxValue + 1);
   }
 
   static RangeBoundary Min(RangeBoundary a, RangeBoundary b);
 
   static RangeBoundary Max(RangeBoundary a, RangeBoundary b);
 
   bool Overflowed() const {
-    return !Smi::IsValid(value());
+    return IsConstant() && !Smi::IsValid(value());
   }
 
   RangeBoundary Clamp() const {
     if (IsConstant()) {
       if (value() < Smi::kMinValue) return MinSmi();
       if (value() > Smi::kMaxValue) return MaxSmi();
     }
     return *this;
   }
 
@@ skipping 739 matching lines @@
 class StaticCallInstr : public TemplateDefinition<0> {
  public:
   StaticCallInstr(intptr_t token_pos,
                   const Function& function,
                   const Array& argument_names,
                   ZoneGrowableArray<PushArgumentInstr*>* arguments)
       : token_pos_(token_pos),
         function_(function),
         argument_names_(argument_names),
         arguments_(arguments),
-        result_cid_(kDynamicCid) {
+        result_cid_(kDynamicCid),
+        is_known_constructor_(false) {
     ASSERT(function.IsZoneHandle());
     ASSERT(argument_names.IsZoneHandle());
   }
 
   DECLARE_INSTRUCTION(StaticCall)
   virtual RawAbstractType* CompileType() const;
 
   // Accessors forwarded to the AST node.
   const Function& function() const { return function_; }
   const Array& argument_names() const { return argument_names_; }
   intptr_t token_pos() const { return token_pos_; }
 
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
   PushArgumentInstr* ArgumentAt(intptr_t index) const {
     return (*arguments_)[index];
   }
 
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
   virtual bool CanDeoptimize() const { return true; }
 
   virtual bool HasSideEffect() const { return true; }
 
   virtual intptr_t ResultCid() const { return result_cid_; }
   void set_result_cid(intptr_t value) { result_cid_ = value; }
 
+  bool is_known_constructor() const { return is_known_constructor_; }
+  void set_is_known_constructor(bool is_known_constructor) {
+    is_known_constructor_ = is_known_constructor;
+  }
+
  private:
   const intptr_t token_pos_;
   const Function& function_;
   const Array& argument_names_;
   ZoneGrowableArray<PushArgumentInstr*>* arguments_;
   intptr_t result_cid_;  // For some library functions we know the result.
 
+  // Some library constructors have known semantics.
+  bool is_known_constructor_;
+
+
   DISALLOW_COPY_AND_ASSIGN(StaticCallInstr);
 };
 
 
 class LoadLocalInstr : public TemplateDefinition<0> {
  public:
   LoadLocalInstr(const LocalVariable& local, intptr_t context_level)
       : local_(local),
         context_level_(context_level) { }
 
@@ skipping 1535 matching lines @@
 
   virtual bool AttributesEqual(Instruction* other) const;
 
   virtual bool AffectedBySideEffect() const { return false; }
 
   Value* array() const { return inputs_[0]; }
   Value* index() const { return inputs_[1]; }
 
   intptr_t array_type() const { return array_type_; }
 
-  bool IsRedundant();
+  bool IsRedundant(RangeBoundary length);
 
  private:
   intptr_t array_type_;
 
   DISALLOW_COPY_AND_ASSIGN(CheckArrayBoundInstr);
 };
 
 
 #undef DECLARE_INSTRUCTION
 
@@ skipping 202 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_