Improve code for !identical(a, b):

runtime/vm/flow_graph_optimizer.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/flow_graph_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/hash_map.h"
 #include "vm/il_printer.h"
 #include "vm/intermediate_language.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/resolver.h"
 #include "vm/scopes.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
-DECLARE_FLAG(bool, eliminate_type_checks);
-DECLARE_FLAG(bool, enable_type_checks);
-DEFINE_FLAG(bool, trace_optimization, false, "Print optimization details.");
-DECLARE_FLAG(bool, trace_type_check_elimination);
-DEFINE_FLAG(bool, use_cha, true, "Use class hierarchy analysis.");
-DEFINE_FLAG(bool, load_cse, true, "Use redundant load elimination.");
-DEFINE_FLAG(bool, trace_range_analysis, false, "Trace range analysis progress");
-DEFINE_FLAG(bool, trace_constant_propagation, false,
-    "Print constant propagation and useless code elimination.");
 DEFINE_FLAG(bool, array_bounds_check_elimination, true,
     "Eliminate redundant bounds checks.");
+DEFINE_FLAG(bool, load_cse, true, "Use redundant load elimination.");
 DEFINE_FLAG(int, max_polymorphic_checks, 4,
     "Maximum number of polymorphic check, otherwise it is megamorphic.");
 DEFINE_FLAG(bool, remove_redundant_phis, true, "Remove redundant phis.");
+DEFINE_FLAG(bool, trace_constant_propagation, false,
+    "Print constant propagation and useless code elimination.");
+DEFINE_FLAG(bool, trace_optimization, false, "Print optimization details.");
+DEFINE_FLAG(bool, trace_range_analysis, false, "Trace range analysis progress");
 DEFINE_FLAG(bool, truncating_left_shift, true,
     "Optimize left shift to truncate if possible");
+DEFINE_FLAG(bool, use_cha, true, "Use class hierarchy analysis.");
+DECLARE_FLAG(bool, eliminate_type_checks);
+DECLARE_FLAG(bool, enable_type_checks);
+DECLARE_FLAG(bool, trace_type_check_elimination);
+
 
 
 void FlowGraphOptimizer::ApplyICData() {
   VisitBlocks();
 }
 
 
 // Attempts to convert an instance call (IC call) using propagated class-ids,
 // e.g., receiver class id.
 void FlowGraphOptimizer::ApplyClassIds() {
@@ skipping 2292 matching lines @@
     case Token::kLT: return Token::kGT;
     case Token::kGT: return Token::kLT;
     case Token::kLTE: return Token::kGTE;
     case Token::kGTE: return Token::kLTE;
     default:
       UNREACHABLE();
       return Token::kILLEGAL;
   }
 }
 
-// For a comparison operation return an operation for the negated comparison:
-// !(a (op) b) === a (op') b
-static Token::Kind NegateComparison(Token::Kind op) {
-  switch (op) {
-    case Token::kEQ: return Token::kNE;
-    case Token::kNE: return Token::kEQ;
-    case Token::kLT: return Token::kGTE;
-    case Token::kGT: return Token::kLTE;
-    case Token::kLTE: return Token::kGT;
-    case Token::kGTE: return Token::kLT;
-    default:
-      UNREACHABLE();
-      return Token::kILLEGAL;
-  }
-}
-
 
 // Given a boundary (right operand) and a comparison operation return
 // a symbolic range constraint for the left operand of the comparison assuming
 // that it evaluated to true.
 // For example for the comparison a < b symbol a is constrained with range
 // [Smi::kMinValue, b - 1].
 static Range* ConstraintRange(Token::Kind op, Definition* boundary) {
   switch (op) {
     case Token::kEQ:
       return new Range(RangeBoundary::FromDefinition(boundary),
@@ skipping 59 matching lines @@
                             ConstraintRange(op_kind, boundary),
                             branch->true_successor());
     // Mark true_constraint an artificial use of boundary. This ensures
     // that constraint's range is recalculated if boundary's range changes.
     if (true_constraint != NULL) true_constraint->AddDependency(boundary);
 
     // Constrain definition with a negated condition at the false successor.
     ConstraintInstr* false_constraint =
         InsertConstraintFor(
             defn,
-            ConstraintRange(NegateComparison(op_kind), boundary),
+            ConstraintRange(Token::NegateComparison(op_kind), boundary),
             branch->false_successor());
     // Mark false_constraint an artificial use of boundary. This ensures
     // that constraint's range is recalculated if boundary's range changes.
     if (false_constraint != NULL) false_constraint->AddDependency(boundary);
   }
 }
 
 void RangeAnalysis::InsertConstraintsFor(Definition* defn) {
   for (Value* use = defn->input_use_list();
        use != NULL;
@@ skipping 2173 matching lines @@
   if (changed) {
     // We may have changed the block order and the dominator tree.
     flow_graph->DiscoverBlocks();
     GrowableArray<BitVector*> dominance_frontier;
     flow_graph->ComputeDominators(&dominance_frontier);
   }
 }
 
 
 }  // namespace dart