[turbofan] Introduces the BitcastWordToTaggedSigned and BitcastTaggedToWord opcodes.

test/unittests/interpreter/interpreter-assembler-unittest.cc

 // Copyright 2015 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 "test/unittests/interpreter/interpreter-assembler-unittest.h"
 
 #include "src/code-factory.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/node.h"
 #include "src/interface-descriptors.h"
@@ skipping 523 matching lines @@
   }
 }
 
 TARGET_TEST_F(InterpreterAssemblerTest, SmiTag) {
   TRACED_FOREACH(interpreter::Bytecode, bytecode, kBytecodes) {
     InterpreterAssemblerForTest m(this, bytecode);
     Node* value = m.Int32Constant(44);
     EXPECT_THAT(m.SmiTag(value),
                 IsIntPtrConstant(static_cast<intptr_t>(44)
                                  << (kSmiShiftSize + kSmiTagSize)));
-    EXPECT_THAT(
-        m.SmiUntag(value),
-        IsWordSar(value, IsIntPtrConstant(kSmiShiftSize + kSmiTagSize)));
+    EXPECT_THAT(m.SmiUntag(value),
+                IsWordSar(IsBitcastTaggedToWord(value),
+                          IsIntPtrConstant(kSmiShiftSize + kSmiTagSize)));
   }
 }
 
 TARGET_TEST_F(InterpreterAssemblerTest, IntPtrAdd) {
   TRACED_FOREACH(interpreter::Bytecode, bytecode, kBytecodes) {
     InterpreterAssemblerForTest m(this, bytecode);
     Node* a = m.Int32Constant(0);
     Node* b = m.Int32Constant(1);
     Node* add = m.IntPtrAdd(a, b);
     EXPECT_THAT(add, IsIntPtrAdd(a, b));
@@ skipping 160 matching lines @@
     EXPECT_THAT(feedback_vector,
                 m.IsLoad(MachineType::AnyTagged(), load_literals_matcher,
                          IsIntPtrConstant(LiteralsArray::kFeedbackVectorOffset -
                                           kHeapObjectTag)));
   }
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8