[llvm] [SandboxIR] sandboxir::Use operands (part 1) and uses (part 2) (PR #98251)

[Arthur Eubanks via llvm-commits]

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@@ -71,6 +71,98 @@ namespace sandboxir {
 class Function;
 class Context;
 class Instruction;
+class User;
+class Value;
+
+/// Represents a Def-use/Use-def edge in SandboxIR.
+/// NOTE: Unlike llvm::Use, this is not an integral part of the use-def chains.
+/// It is also not uniqued and is currently passed by value, so you can have
+/// more than one sandboxir::Use objects for the same use-def edge.
+class Use {
+  llvm::Use *LLVMUse;
+  User *User;
+  Context *Ctx;
+
+  /// Don't allow the user to create a sandboxir::Use directly.
+  Use(llvm::Use *LLVMUse, class User *User, Context &Ctx)
+      : LLVMUse(LLVMUse), User(User), Ctx(&Ctx) {}
+  Use() : LLVMUse(nullptr), Ctx(nullptr) {}
+
+  friend class Value;              // For constructor
+  friend class User;               // For constructor
+  friend class OperandUseIterator; // For constructor
+  friend class UserUseIterator;    // For accessing members
+
+public:
+  operator Value *() const { return get(); }
+  Value *get() const;
+  class User *getUser() const { return User; }
+  unsigned getOperandNo() const;
+  Context *getContext() const { return Ctx; }
+  bool operator==(const Use &Other) const {
+    assert(Ctx == Other.Ctx && "Contexts differ!");
+    return LLVMUse == Other.LLVMUse && User == Other.User;
+  }
+  bool operator!=(const Use &Other) const { return !(*this == Other); }
+#ifndef NDEBUG
+  void dump(raw_ostream &OS) const;
+  void dump() const;
+#endif // NDEBUG
+};
+
+/// Returns the operand edge when dereferenced.
+class OperandUseIterator {
+  Use Use;
+  /// Don't let the user create a non-empty OperandUseIterator.
+  OperandUseIterator(const class Use &Use) : Use(Use) {}
+  friend class User; // For constructor
+#define DEF_VALUE(ID, CLASS)
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aeubanks wrote:

no need for empty define

https://github.com/llvm/llvm-project/pull/98251