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

[Arthur Eubanks via llvm-commits]

================
@@ -7,19 +7,117 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/SandboxIR/SandboxIR.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/Support/Debug.h"
 #include <sstream>
 
 using namespace llvm::sandboxir;
 
+Value *Use::get() const { return Ctx->getValue(LLVMUse->get()); }
+
+unsigned Use::getOperandNo() const { return User->getUseOperandNo(*this); }
+
+#ifndef NDEBUG
+void Use::dump(raw_ostream &OS) const {
+  Value *Def = nullptr;
+  if (LLVMUse == nullptr)
+    OS << "<null> LLVM Use! ";
+  else
+    Def = Ctx->getValue(LLVMUse->get());
+  OS << "Def:  ";
+  if (Def == nullptr)
+    OS << "NULL";
+  else
+    OS << *Def;
+  OS << "\n";
+
+  OS << "User: ";
+  if (User == nullptr)
+    OS << "NULL";
+  else
+    OS << *User;
+  OS << "\n";
+
+  OS << "OperandNo: ";
+  if (User == nullptr)
+    OS << "N/A";
+  else
+    OS << getOperandNo();
+  OS << "\n";
+}
+
+void Use::dump() const { dump(dbgs()); }
+#endif // NDEBUG
+
+Use OperandUseIterator::operator*() const { return Use; }
+
+OperandUseIterator &OperandUseIterator::operator++() {
+  assert(Use.LLVMUse != nullptr && "Already at end!");
+  User *User = Use.getUser();
+  Use = User->getOperandUseInternal(Use.getOperandNo() + 1, /*Verify=*/false);
+  return *this;
+}
+
+UserUseIterator &UserUseIterator::operator++() {
+  llvm::Use *&LLVMUse = Use.LLVMUse;
+  assert(LLVMUse != nullptr && "Already at end!");
+  LLVMUse = LLVMUse->getNext();
+  if (LLVMUse == nullptr) {
+    Use.User = nullptr;
+    return *this;
+  }
+  auto *Ctx = Use.Ctx;
+  auto *LLVMUser = LLVMUse->getUser();
+  Use.User = cast_or_null<sandboxir::User>(Ctx->getValue(LLVMUser));
+  return *this;
+}
+
 Value::Value(ClassID SubclassID, llvm::Value *Val, Context &Ctx)
     : SubclassID(SubclassID), Val(Val), Ctx(Ctx) {
 #ifndef NDEBUG
   UID = Ctx.getNumValues();
 #endif
 }
 
+Value::use_iterator Value::use_begin() {
+  llvm::Use *LLVMUse = nullptr;
+  if (Val->use_begin() != Val->use_end())
+    LLVMUse = &*Val->use_begin();
+  User *User = LLVMUse != nullptr ? cast_or_null<sandboxir::User>(Ctx.getValue(
+                                        Val->use_begin()->getUser()))
+                                  : nullptr;
+  return use_iterator(Use(LLVMUse, User, Ctx));
+}
+
+Value::user_iterator Value::user_begin() {
+  auto UseBegin = Val->use_begin();
+  auto UseEnd = Val->use_end();
+  bool AtEnd = UseBegin == UseEnd;
+  llvm::Use *LLVMUse = AtEnd ? nullptr : &*UseBegin;
+  User *User =
+      AtEnd ? nullptr
+            : cast_or_null<sandboxir::User>(Ctx.getValue(&*LLVMUse->getUser()));
+  return user_iterator(Use(LLVMUse, User, Ctx), UseToUser());
+}
+
+unsigned Value::getNumUsers() const {
----------------
aeubanks wrote:

how are num users/num uses used? is this mostly for scheduling?

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