Fix smi-based math floor.

src/hydrogen-instructions.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 1267 matching lines @@
   // A change from an integer32 can be replaced by the integer32 value.
   if (dividend->IsChange() &&
       HChange::cast(dividend)->from().IsInteger32()) {
     return HChange::cast(dividend)->value();
   }
   return NULL;
 }
 
 
 HValue* HUnaryMathOperation::Canonicalize() {
+  if (op() == kMathRound) {
+    HValue* val = value();
+    if (val->IsChange()) val = HChange::cast(val)->value();
+
+    // If the input is integer32 then we replace the round instruction
+    // with its input.
+    if (val->representation().IsSmiOrInteger32()) return val;
+  }
+
   if (op() == kMathFloor) {
     HValue* val = value();
     if (val->IsChange()) val = HChange::cast(val)->value();
 
     // If the input is integer32 then we replace the floor instruction
     // with its input.
     if (val->representation().IsSmiOrInteger32()) return val;
 
     if (val->IsDiv() && (val->UseCount() == 1)) {
       HDiv* hdiv = HDiv::cast(val);
@@ skipping 2008 matching lines @@
   if (from().IsDouble() && to().IsTagged()) return HType::HeapNumber();
   return type();
 }
 
 
 Representation HUnaryMathOperation::RepresentationFromInputs() {
   Representation rep = representation();
   // If any of the actual input representation is more general than what we
   // have so far but not Tagged, use that representation instead.
   Representation input_rep = value()->representation();
-  if (!input_rep.IsTagged()) rep = rep.generalize(input_rep);
+  if (!input_rep.IsTagged()) {
+    rep = rep.generalize(input_rep);
+  } else if (flexible_int()) {
+    rep = Representation::Integer32();
+  }
   return rep;
 }
 
 
 void HAllocate::HandleSideEffectDominator(GVNFlag side_effect,
                                           HValue* dominator) {
   ASSERT(side_effect == kChangesNewSpacePromotion);
   if (!FLAG_use_allocation_folding) return;
 
   // Try to fold allocations together with their dominating allocations.
@@ skipping 808 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal