[turbofan] Introduces the BitcastWordToTaggedSigned and BitcastTaggedToWord opcodes.

src/compiler/instruction-selector.cc

Index: src/compiler/instruction-selector.cc
diff --git a/src/compiler/instruction-selector.cc b/src/compiler/instruction-selector.cc
index f233cae5b5ac89e324c159daaf7fd71c54127ee1..e4faca5a6692b572875374ad51a63bfc8957fc65 100644
--- a/src/compiler/instruction-selector.cc
+++ b/src/compiler/instruction-selector.cc
@@ -1104,8 +1104,14 @@ void InstructionSelector::VisitNode(Node* node) {
       return VisitUint64LessThanOrEqual(node);
     case IrOpcode::kUint64Mod:
       return MarkAsWord64(node), VisitUint64Mod(node);
+    case IrOpcode::kBitcastTaggedToWord:
+      return MarkAsRepresentation(MachineType::PointerRepresentation(), node),
+             VisitBitcastTaggedToWord(node);
     case IrOpcode::kBitcastWordToTagged:
       return MarkAsReference(node), VisitBitcastWordToTagged(node);
+    case IrOpcode::kBitcastWordToTaggedSigned:
+      return MarkAsRepresentation(MachineRepresentation::kTaggedSigned, node),
+             EmitIdentity(node);
     case IrOpcode::kChangeFloat32ToFloat64:
       return MarkAsFloat64(node), VisitChangeFloat32ToFloat64(node);
     case IrOpcode::kChangeInt32ToFloat64:
@@ -1501,6 +1507,11 @@ void InstructionSelector::VisitStackSlot(Node* node) {
        sequence()->AddImmediate(Constant(slot)), 0, nullptr);
 }
 
+void InstructionSelector::VisitBitcastTaggedToWord(Node* node) {
+  OperandGenerator g(this);
+  Emit(kArchNop, g.DefineSameAsFirst(node), g.Use(node->InputAt(0)));
+}
+
 void InstructionSelector::VisitBitcastWordToTagged(Node* node) {
   OperandGenerator g(this);
   Emit(kArchNop, g.DefineSameAsFirst(node), g.Use(node->InputAt(0)));