[turbofan] Simplify representations selection for phi.

test/cctest/compiler/test-simplified-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // TODO(jochen): Remove this after the setting is turned on globally.
 #define V8_IMMINENT_DEPRECATION_WARNINGS
 
 #include <limits>
 
 #include "src/compiler/access-builder.h"
@@ skipping 1976 matching lines @@
     MachineTypeUnion expected;
   };
 
   TestData test_data[] = {
       {Type::Signed32(), Type::Unsigned32(), kMachInt32,
        kRepWord32 | kTypeNumber},
       {Type::Signed32(), Type::Unsigned32(), kMachUint32,
        kRepWord32 | kTypeNumber},
       {Type::Signed32(), Type::Signed32(), kMachInt32, kMachInt32},
       {Type::Unsigned32(), Type::Unsigned32(), kMachInt32, kMachUint32},
-      {Type::Number(), Type::Signed32(), kMachInt32, kMachFloat64},
-      {Type::Signed32(), Type::String(), kMachInt32, kMachAnyTagged}};
+      {Type::Number(), Type::Signed32(), kMachInt32, kRepWord32 | kTypeNumber}};
 
   for (auto const d : test_data) {
     TestingGraph t(d.arg1, d.arg2, Type::Boolean());
 
     Node* br = t.graph()->NewNode(t.common()->Branch(), t.p2, t.start);
     Node* tb = t.graph()->NewNode(t.common()->IfTrue(), br);
     Node* fb = t.graph()->NewNode(t.common()->IfFalse(), br);
     Node* m = t.graph()->NewNode(t.common()->Merge(2), tb, fb);
 
     Node* phi =
         t.graph()->NewNode(t.common()->Phi(kMachAnyTagged, 2), t.p0, t.p1, m);
 
     Type* phi_type = Type::Union(d.arg1, d.arg2, z);
     NodeProperties::SetType(phi, phi_type);
 
     Node* use = t.Use(phi, d.use);
     t.Return(use);
     t.Lower();
 
     CHECK_EQ(d.expected, OpParameter<MachineType>(phi));
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8