Flexible representation for BuildIncrement, but CannotBeTagged.

src/hydrogen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2935 matching lines @@
     for (int j = 0; j < phis->length(); ++j) {
       HPhi* phi = phis->at(j);
       if (phi->representation().IsNone()) {
         phi->ChangeRepresentation(Representation::Tagged());
       }
     }
     for (HInstruction* current = block->first();
          current != NULL; current = current->next()) {
       if (current->representation().IsNone() &&
           current->CheckFlag(HInstruction::kFlexibleRepresentation)) {
-        current->ChangeRepresentation(Representation::Tagged());
+        if (current->CheckFlag(HInstruction::kCannotBeTagged)) {
+          current->ChangeRepresentation(Representation::Double());
+        } else {
+          current->ChangeRepresentation(Representation::Tagged());
+        }
       }
     }
   }
 }
 
 
 void HGraph::MergeRemovableSimulates() {
   HPhase phase("H_Merge removable simulates", this);
   ZoneList<HSimulate*> mergelist(2, zone());
   for (int i = 0; i < blocks()->length(); ++i) {
@@ skipping 6208 matching lines @@
   if (join != NULL) return ast_context()->ReturnValue(Pop());
 }
 
 
 HInstruction* HOptimizedGraphBuilder::BuildIncrement(
     bool returns_original_input,
     CountOperation* expr) {
   // The input to the count operation is on top of the expression stack.
   TypeInfo info = expr->type();
   Representation rep = ToRepresentation(info);
-  if (rep.IsTagged()) {
-    rep = Representation::Integer32();
+  if (rep.IsNone() || rep.IsTagged()) {
+    rep = Representation::Smi();
   }
 
   if (returns_original_input) {
     // We need an explicit HValue representing ToNumber(input).  The
     // actual HChange instruction we need is (sometimes) added in a later
     // phase, so it is not available now to be used as an input to HAdd and
     // as the return value.
     HInstruction* number_input = new(zone()) HForceRepresentation(Pop(), rep);
+    if (!rep.IsDouble()) {
+      number_input->SetFlag(HInstruction::kFlexibleRepresentation);
+      number_input->SetFlag(HInstruction::kCannotBeTagged);
+    }
     AddInstruction(number_input);
     Push(number_input);
   }
 
   // The addition has no side effects, so we do not need
   // to simulate the expression stack after this instruction.
   // Any later failures deopt to the load of the input or earlier.
   HConstant* delta = (expr->op() == Token::INC)
       ? graph()->GetConstant1()
       : graph()->GetConstantMinus1();
   HValue* context = environment()->LookupContext();
   HInstruction* instr = HAdd::New(zone(), context, Top(), delta);
-  // We can't insert a simulate here, because it would break deoptimization,
-  // so the HAdd must not have side effects, so we must freeze its
-  // representation.
-  instr->AssumeRepresentation(rep);
+  instr->SetFlag(HInstruction::kCannotBeTagged);
   instr->ClearAllSideEffects();
   AddInstruction(instr);
   return instr;
 }
 
 
 void HOptimizedGraphBuilder::VisitCountOperation(CountOperation* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
@@ skipping 2433 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal