Support Smi in CompareIDAndBranch

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 2435 matching lines @@
   right()->PrintNameTo(stream);
   HControlInstruction::PrintDataTo(stream);
 }
 
 
 void HGoto::PrintDataTo(StringStream* stream) {
   stream->Add("B%d", SuccessorAt(0)->block_id());
 }
 
 
 void HCompareIDAndBranch::InferRepresentation(HInferRepresentation* h_infer) {

[Jakob Kummerow, 2013/05/28 09:00:54]

As discussed offline, please rewrite this method to make it clear that what it
computes is the most general representation out of the set
{observed_input_representation(0), observed_input_representation(1), left_rep,
right_rep}, ignoring any inputs that are Tagged.

Then, if the computed |rep| is Double, set the flag kDeoptimizeOnUndefined if
necessary.

   Representation rep = Representation::None();
   Representation left_rep = left()->representation();
   Representation right_rep = right()->representation();
   bool observed_integers =
       observed_input_representation(0).IsInteger32() &&
       observed_input_representation(1).IsInteger32();
-  bool inputs_are_not_doubles =
-      !left_rep.IsDouble() && !right_rep.IsDouble();
+  bool inputs_are_not_doubles = !left_rep.IsDouble() && !right_rep.IsDouble();
+
   if (observed_integers && inputs_are_not_doubles) {
-    rep = Representation::Integer32();
+    rep = Representation::Smi();
+    if (left_rep.is_more_general_than(rep) && !left_rep.IsTagged()) {
+      rep = Representation::Integer32();
+    }
+    if (right_rep.is_more_general_than(rep) && !right_rep.IsTagged()) {
+      rep = Representation::Integer32();
+    }
   } else {
     rep = Representation::Double();
     // According to the ES5 spec (11.9.3, 11.8.5), Equality comparisons (==, ===
     // and !=) have special handling of undefined, e.g. undefined == undefined
     // is 'true'. Relational comparisons have a different semantic, first
     // calling ToPrimitive() on their arguments.  The standard Crankshaft
     // tagged-to-double conversion to ensure the HCompareIDAndBranch's inputs
     // are doubles caused 'undefined' to be converted to NaN. That's compatible
     // out-of-the box with ordered relational comparisons (<, >, <=,
     // >=). However, for equality comparisons (and for 'in' and 'instanceof'),
@@ skipping 1318 matching lines @@
     case kBackingStore:
       if (!name_.is_null()) stream->Add(*String::cast(*name_)->ToCString());
       stream->Add("[backing-store]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal