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thirdparty/capstone/suite/synctools/tablegen/include/llvm/IR/Use.h

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+//===- llvm/Use.h - Definition of the Use class -----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This defines the Use class.  The Use class represents the operand of an
+/// instruction or some other User instance which refers to a Value.  The Use
+/// class keeps the "use list" of the referenced value up to date.
+///
+/// Pointer tagging is used to efficiently find the User corresponding to a Use
+/// without having to store a User pointer in every Use. A User is preceded in
+/// memory by all the Uses corresponding to its operands, and the low bits of
+/// one of the fields (Prev) of the Use class are used to encode offsets to be
+/// able to find that User given a pointer to any Use. For details, see:
+///
+///   http://www.llvm.org/docs/ProgrammersManual.html#UserLayout
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_USE_H
+#define LLVM_IR_USE_H
+
+#include "llvm-c/Types.h"
+#include "llvm/Support/CBindingWrapping.h"
+#include "llvm/Support/Compiler.h"
+
+namespace llvm {
+
+template <typename> struct simplify_type;
+class User;
+class Value;
+
+/// A Use represents the edge between a Value definition and its users.
+///
+/// This is notionally a two-dimensional linked list. It supports traversing
+/// all of the uses for a particular value definition. It also supports jumping
+/// directly to the used value when we arrive from the User's operands, and
+/// jumping directly to the User when we arrive from the Value's uses.
+class Use {
+public:
+  Use(const Use &U) = delete;
+
+  /// Provide a fast substitute to std::swap<Use>
+  /// that also works with less standard-compliant compilers
+  void swap(Use &RHS);
+
+private:
+  /// Destructor - Only for zap()
+  ~Use() {
+    if (Val)
+      removeFromList();
+  }
+
+  /// Constructor
+  Use(User *Parent) : Parent(Parent) {}
+
+public:
+  friend class Value;
+  friend class User;
+
+  operator Value *() const { return Val; }
+  Value *get() const { return Val; }
+
+  /// Returns the User that contains this Use.
+  ///
+  /// For an instruction operand, for example, this will return the
+  /// instruction.
+  User *getUser() const { return Parent; };
+
+  inline void set(Value *Val);
+
+  inline Value *operator=(Value *RHS);
+  inline const Use &operator=(const Use &RHS);
+
+  Value *operator->() { return Val; }
+  const Value *operator->() const { return Val; }
+
+  Use *getNext() const { return Next; }
+
+  /// Return the operand # of this use in its User.
+  unsigned getOperandNo() const;
+
+  /// Destroys Use operands when the number of operands of
+  /// a User changes.
+  static void zap(Use *Start, const Use *Stop, bool del = false);
+
+private:
+
+  Value *Val = nullptr;
+  Use *Next = nullptr;
+  Use **Prev = nullptr;
+  User *Parent = nullptr;
+
+  void addToList(Use **List) {
+    Next = *List;
+    if (Next)
+      Next->Prev = &Next;
+    Prev = List;
+    *Prev = this;
+  }
+
+  void removeFromList() {
+    *Prev = Next;
+    if (Next)
+      Next->Prev = Prev;
+  }
+};
+
+/// Allow clients to treat uses just like values when using
+/// casting operators.
+template <> struct simplify_type<Use> {
+  using SimpleType = Value *;
+
+  static SimpleType getSimplifiedValue(Use &Val) { return Val.get(); }
+};
+template <> struct simplify_type<const Use> {
+  using SimpleType = /*const*/ Value *;
+
+  static SimpleType getSimplifiedValue(const Use &Val) { return Val.get(); }
+};
+
+// Create wrappers for C Binding types (see CBindingWrapping.h).
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(Use, LLVMUseRef)
+
+} // end namespace llvm
+
+#endif // LLVM_IR_USE_H