Improve smi support in crankshaft

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index d4938e5c3848d9509b7d0603ae19c2cf253a4373..b276cb20c77ba9e8595ebdd5c85fad7eb28ac9c7 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -3565,6 +3565,7 @@ void HPhi::InferRepresentation(HInferRepresentation* h_infer) {
 
 
 Representation HPhi::RepresentationFromInputs() {
+  bool tagged_smi_occurred = false;

[Jakob Kummerow, 2013/05/31 16:39:40]

I don't think we should treat tagged_smi differently from just smi.

Also, as discussed offline, rewriting this method based on
Representation::generalize() sounds good.

   bool double_occurred = false;
   bool int32_occurred = false;
   bool smi_occurred = false;
@@ -3574,10 +3575,18 @@ Representation HPhi::RepresentationFromInputs() {
       HPhi* hint_value = HUnknownOSRValue::cast(value)->incoming_value();
       if (hint_value != NULL) {
         Representation hint = hint_value->representation();
-        if (hint.IsTagged()) return hint;
-        if (hint.IsDouble()) double_occurred = true;
-        if (hint.IsInteger32()) int32_occurred = true;
-        if (hint.IsSmi()) smi_occurred = true;
+        if (hint.IsTagged()) {
+          if (!hint_value->type().IsSmi()) return hint;
+          if (double_occurred) return hint;
+          if (int32_occurred) return hint;
+          tagged_smi_occurred = true;
+        } else if (tagged_smi_occurred) {
+          if (!hint.IsSmi()) return Representation::Tagged();
+        } else {
+          if (hint.IsDouble()) double_occurred = true;
+          if (hint.IsInteger32()) int32_occurred = true;
+          if (hint.IsSmi()) smi_occurred = true;
+        }
       }
       continue;
     }
@@ -3587,7 +3596,9 @@ Representation HPhi::RepresentationFromInputs() {
     if (value->representation().IsTagged()) {
       if (value->IsConstant()) {
         HConstant* constant = HConstant::cast(value);
-        if (constant->IsConvertibleToInteger()) {
+        if (constant->HasSmiValue()) {
+          smi_occurred = true;
+        } else if (constant->IsConvertibleToInteger()) {
           int32_occurred = true;
         } else if (constant->HasNumberValue()) {
           double_occurred = true;
@@ -3596,12 +3607,16 @@ Representation HPhi::RepresentationFromInputs() {
         }
       } else {
         if (value->IsPhi() && !IsConvertibleToInteger()) {
-          return Representation::Tagged();
+          if (!value->type().IsSmi()) return Representation::Tagged();
+          if (double_occurred) return Representation::Tagged();
+          if (int32_occurred) return Representation::Tagged();
+          tagged_smi_occurred = true;
         }
       }
     }
   }
 
+  if (tagged_smi_occurred) return Representation::Smi();
   if (double_occurred) return Representation::Double();
   if (int32_occurred) return Representation::Integer32();
   if (smi_occurred) return Representation::Smi();