HLoadNamedField for Smis optimized for x64

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 23dbbd289c6c5d5a9e07697368e9fba6ab05e22d..4dd24fd871552456a10bb77ab8f6a0e4b4b25138 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -6216,7 +6216,11 @@ class HLoadNamedField V8_FINAL : public HTemplateInstruction<1> {
       set_representation(Representation::Integer32());
     } else if (representation.IsSmi()) {
       set_type(HType::Smi());
-      set_representation(representation);
+      if (SmiValuesAre32Bits()) {
+        set_representation(Representation::Integer32());
+      } else {
+        set_representation(representation);
+      }
     } else if (representation.IsDouble() ||
                representation.IsExternal() ||
                representation.IsInteger32()) {