[turbofan] Optimize tagged conversion based on type.

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.
 
 #include <limits>
 
 #include "src/ast/scopes.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/change-lowering.h"
 #include "src/compiler/control-builders.h"
@@ skipping 890 matching lines @@
 
 TEST(LowerBooleanToNumber_bit_tagged) {
   // BooleanToNumber(x: kRepBit) used as MachineType::AnyTagged()
   TestingGraph t(Type::Boolean());
   Node* b = t.ExampleWithOutput(MachineType::Bool());
   Node* cnv = t.graph()->NewNode(t.simplified()->BooleanToNumber(), b);
   Node* use = t.Use(cnv, MachineType::AnyTagged());
   t.Return(use);
   t.Lower();
   CHECK_EQ(b, use->InputAt(0)->InputAt(0));
-  CHECK_EQ(IrOpcode::kChangeUint32ToTagged, use->InputAt(0)->opcode());
+  CHECK_EQ(IrOpcode::kChangeInt31ToTagged, use->InputAt(0)->opcode());
 }
 
 
 TEST(LowerBooleanToNumber_tagged_tagged) {
   // BooleanToNumber(x: kRepTagged) used as MachineType::AnyTagged()
   TestingGraph t(Type::Boolean());
   Node* b = t.p0;
   Node* cnv = t.graph()->NewNode(t.simplified()->BooleanToNumber(), b);
   Node* use = t.Use(cnv, MachineType::AnyTagged());
   t.Return(use);
   t.Lower();
   CHECK_EQ(cnv, use->InputAt(0)->InputAt(0));
-  CHECK_EQ(IrOpcode::kChangeUint32ToTagged, use->InputAt(0)->opcode());
+  CHECK_EQ(IrOpcode::kChangeInt31ToTagged, use->InputAt(0)->opcode());
   CHECK_EQ(t.machine()->WordEqual()->opcode(), cnv->opcode());
   CHECK(b == cnv->InputAt(0) || b == cnv->InputAt(1));
   Node* c = t.jsgraph.TrueConstant();
   CHECK(c == cnv->InputAt(0) || c == cnv->InputAt(1));
 }
 
 static Type* test_types[] = {Type::Signed32(), Type::Unsigned32(),
                              Type::Number()};
 
 TEST(LowerNumberCmp_to_int32) {
@@ skipping 1007 matching lines @@
     t.Return(use);
     t.Lower();
 
     CHECK_EQ(d.expected, PhiRepresentationOf(phi->op()));
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8