HLoadKeyed 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 4dd24fd871552456a10bb77ab8f6a0e4b4b25138..f0ffb67cdab642296c1971826c33b204fdd29cdc 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -6420,7 +6420,11 @@ class HLoadKeyed V8_FINAL
             (!IsHoleyElementsKind(elements_kind) ||
              mode == NEVER_RETURN_HOLE)) {
           set_type(HType::Smi());
-          set_representation(Representation::Smi());
+          if (SmiValuesAre32Bits() && !RequiresHoleCheck()) {
+            set_representation(Representation::Integer32());
+          } else {
+            set_representation(Representation::Smi());
+          }
         } else {
           set_representation(Representation::Tagged());
         }