[turbofan] Take type into account when determining Word32 phi representation.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index b3050719883c0467bf97f8d0610e494a3142c014..6f3d835ff6e9906a7cc5930a7f26840721a5bb84 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -324,7 +324,8 @@ class RepresentationSelector {
       } else if (upper->Is(Type::Signed32()) || upper->Is(Type::Unsigned32())) {
         // multiple uses, but we are within 32 bits range => pick kRepWord32.
         return kRepWord32;
-      } else if ((use & kRepMask) == kRepWord32 ||
+      } else if (((use & kRepMask) == kRepWord32 &&
+                  !CanObserveNonWord32(use)) ||
                  (use & kTypeMask) == kTypeInt32 ||
                  (use & kTypeMask) == kTypeUint32) {
         // We only use 32 bits or we use the result consistently.
@@ -451,6 +452,10 @@ class RepresentationSelector {
            !CanObserveNonUint32(use);
   }
 
+  bool CanObserveNonWord32(MachineTypeUnion use) {
+    return (use & ~(kTypeUint32 | kTypeInt32)) != 0;
+  }
+
   bool CanObserveNonInt32(MachineTypeUnion use) {
     return (use & (kTypeUint32 | kTypeNumber | kTypeAny)) != 0;
   }