Adding Smi support to Add, Sub, Mul, and Bitwise

src/hydrogen-representation-changes.cc

 // Copyright 2013 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 27 matching lines @@
   if (use_value->IsPhi()) {
     next = use_value->block()->predecessors()->at(use_index)->end();
   } else {
     next = HInstruction::cast(use_value);
   }
   // For constants we try to make the representation change at compile
   // time. When a representation change is not possible without loss of
   // information we treat constants like normal instructions and insert the
   // change instructions for them.
   HInstruction* new_value = NULL;
-  bool is_truncating = use_value->CheckFlag(HValue::kTruncatingToInt32);
+  bool is_truncating_to_smi = use_value->CheckFlag(HValue::kTruncatingToSmi);
+  bool is_truncating_to_int = use_value->CheckFlag(HValue::kTruncatingToInt32);
   bool allow_undefined_as_nan =
       use_value->CheckFlag(HValue::kAllowUndefinedAsNaN);
   if (value->IsConstant()) {
     HConstant* constant = HConstant::cast(value);
     // Try to create a new copy of the constant with the new representation.
-    if (is_truncating && to.IsInteger32()) {
+    if (is_truncating_to_int && to.IsInteger32()) {
       Maybe<HConstant*> res = constant->CopyToTruncatedInt32(graph()->zone());
       if (res.has_value) new_value = res.value;
     } else {
       new_value = constant->CopyToRepresentation(to, graph()->zone());
     }
   }
 
   if (new_value == NULL) {
     new_value = new(graph()->zone()) HChange(value, to,
-                                             is_truncating,
+                                             is_truncating_to_smi,
+                                             is_truncating_to_int,
                                              allow_undefined_as_nan);
   }
 
   new_value->InsertBefore(next);
   use_value->SetOperandAt(use_index, new_value);
 }
 
 
 void HRepresentationChangesPhase::InsertRepresentationChangesForValue(
     HValue* value) {
@@ skipping 26 matching lines @@
   // int32-phis allow truncation and iteratively remove the ones that
   // are used in an operation that does not allow a truncating
   // conversion.
   ZoneList<HPhi*> worklist(8, zone());
 
   const ZoneList<HPhi*>* phi_list(graph()->phi_list());
   for (int i = 0; i < phi_list->length(); i++) {
     HPhi* phi = phi_list->at(i);
     if (phi->representation().IsInteger32()) {
       phi->SetFlag(HValue::kTruncatingToInt32);
+    } else if (phi->representation().IsSmi()) {
+      phi->SetFlag(HValue::kTruncatingToSmi);
     }
   }
 
   for (int i = 0; i < phi_list->length(); i++) {
     HPhi* phi = phi_list->at(i);
     for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) {
       // If a Phi is used as a non-truncating int32 or as a double,
       // clear its "truncating" flag.
       HValue* use = it.value();
       Representation input_representation =
           use->RequiredInputRepresentation(it.index());
-      if (!input_representation.IsInteger32() ||
-          !use->CheckFlag(HValue::kTruncatingToInt32)) {
+      if ((phi->representation().IsInteger32() &&
+           !(input_representation.IsInteger32() &&
+             use->CheckFlag(HValue::kTruncatingToInt32))) ||
+          (phi->representation().IsSmi() &&
+           !(input_representation.IsSmi() ||
+             use->CheckFlag(HValue::kTruncatingToSmi)))) {
         if (FLAG_trace_representation) {
           PrintF("#%d Phi is not truncating because of #%d %s\n",
                  phi->id(), it.value()->id(), it.value()->Mnemonic());
         }
         phi->ClearFlag(HValue::kTruncatingToInt32);
+        phi->ClearFlag(HValue::kTruncatingToSmi);
         worklist.Add(phi, zone());
         break;
       }
     }
   }
 
   while (!worklist.is_empty()) {
     HPhi* current = worklist.RemoveLast();
     for (int i = 0; i < current->OperandCount(); ++i) {
       HValue* input = current->OperandAt(i);
       if (input->IsPhi() &&
-          input->representation().IsInteger32() &&
-          input->CheckFlag(HValue::kTruncatingToInt32)) {
+          ((input->representation().IsInteger32() &&
+            input->CheckFlag(HValue::kTruncatingToInt32)) ||
+           (input->representation().IsSmi() &&
+            input->CheckFlag(HValue::kTruncatingToSmi)))) {
         if (FLAG_trace_representation) {
           PrintF("#%d Phi is not truncating because of #%d %s\n",
                  input->id(), current->id(), current->Mnemonic());
         }
         input->ClearFlag(HValue::kTruncatingToInt32);
+        input->ClearFlag(HValue::kTruncatingToSmi);
         worklist.Add(HPhi::cast(input), zone());
       }
     }
   }
 
   const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
   for (int i = 0; i < blocks->length(); ++i) {
     // Process phi instructions first.
     const HBasicBlock* block(blocks->at(i));
     const ZoneList<HPhi*>* phis = block->phis();
     for (int j = 0; j < phis->length(); j++) {
       InsertRepresentationChangesForValue(phis->at(j));
     }
 
     // Process normal instructions.
     for (HInstruction* current = block->first(); current != NULL; ) {
       HInstruction* next = current->next();
       InsertRepresentationChangesForValue(current);
       current = next;
     }
   }
 }
 
 } }  // namespace v8::internal