Recognize pattern (a << b) & c with c being a positive Smi and allow left shift to truncate the res…

runtime/vm/flow_graph_optimizer.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_FLOW_GRAPH_OPTIMIZER_H_
 #define VM_FLOW_GRAPH_OPTIMIZER_H_
 
 #include "vm/intermediate_language.h"
 #include "vm/flow_graph.h"
 
@@ skipping 11 matching lines @@
   virtual ~FlowGraphOptimizer() {}
 
   FlowGraph* flow_graph() const { return flow_graph_; }
 
   // Use ICData to optimize, replace or eliminate instructions.
   void ApplyICData();
 
   // Use propagated class ids to optimize, replace or eliminate instructions.
   void ApplyClassIds();
 
+  // Optimize (a << b) & c pattern: if c is a positive Smi or zero, then the
+  // shift can be a truncating Smi shift-left and result is always Smi.
+  void TryOptimizeLeftShiftWithBitAndPattern();
+
   void Canonicalize();
 
   void EliminateDeadPhis();
 
   void SelectRepresentations();
 
   void PropagateSminess();
 
   void InferSmiRanges();
 
@@ skipping 48 matching lines @@
   // Insert a check of 'to_check' determined by 'unary_checks'.  If the
   // check fails it will deoptimize to 'deopt_id' using the deoptimization
   // environment 'deopt_environment'.  The check is inserted immediately
   // before 'insert_before'.
   void AddCheckClass(Definition* to_check,
                      const ICData& unary_checks,
                      intptr_t deopt_id,
                      Environment* deopt_environment,
                      Instruction* insert_before);
 
+  // Insert a Smi check if needed.
+  void AddCheckSmi(Definition* to_check,
+                   intptr_t deopt_id,
+                   Environment* deopt_environment,
+                   Instruction* insert_before);
+
   // Add a class check for a call's first argument immediately before the
   // call, using the call's IC data to determine the check, and the call's
   // deopt ID and deoptimization environment if the check fails.
   void AddReceiverCheck(InstanceCallInstr* call);
 
   void ReplaceCall(Definition* call, Definition* replacement);
 
   void InsertConversionsFor(Definition* def);
 
   void InsertConversion(Representation from,
@@ skipping 21 matching lines @@
                                 MethodRecognizer::Kind recognized_kind);
 
   void HandleRelationalOp(RelationalOpInstr* comp);
 
   // Visit an equality compare.  The current instruction can be the
   // comparison itself or a branch on the comparison.
   template <typename T>
   void HandleEqualityCompare(EqualityCompareInstr* comp,
                              T current_instruction);
 
+  void OptimizeLeftShiftBitAndSmiOp(Definition* bit_and_instr,
+                                    Definition* left_instr,
+                                    Definition* right_instr);
+
   FlowGraph* flow_graph_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphOptimizer);
 };
 
 
 class ParsedFunction;
 
 
 // Loop invariant code motion.
@@ skipping 85 matching lines @@
 
   // Worklists of blocks and definitions.
   GrowableArray<BlockEntryInstr*> block_worklist_;
   GrowableArray<Definition*> definition_worklist_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_OPTIMIZER_H_