Lab4: Implement basic scalar optimizations and lower Phi nodes to assembly

src/ir/Instruction.cpp

@@ -47,6 +47,16 @@ void User::AddOperand(Value* value) {
   value->AddUse(this, operand_index);
 }
 
+void User::ClearOperands() {
+  for (size_t i = 0; i < operands_.size(); ++i) {
+    auto* old = operands_[i];
+    if (old) {
+      old->RemoveUse(this, i);
+    }
+  }
+  operands_.clear();
+}
+
 Instruction::Instruction(Opcode op, std::shared_ptr<Type> ty, std::string name)
     : User(std::move(ty), std::move(name)), opcode_(op) {}
 
@@ -168,4 +178,46 @@ Value* StoreInst::GetValue() const { return GetOperand(0); }
 
 Value* StoreInst::GetPtr() const { return GetOperand(1); }
 
+PhiInst::PhiInst(std::shared_ptr<Type> ty, std::string name)
+    : Instruction(Opcode::Phi, std::move(ty), std::move(name)) {}
+
+void PhiInst::AddIncoming(Value* val, BasicBlock* bb) {
+  AddOperand(val);
+  AddOperand(bb);
+}
+
+size_t PhiInst::GetNumIncoming() const {
+  return GetNumOperands() / 2;
+}
+
+Value* PhiInst::GetIncomingValue(size_t i) const {
+  return GetOperand(2 * i);
+}
+
+BasicBlock* PhiInst::GetIncomingBlock(size_t i) const {
+  return static_cast<BasicBlock*>(GetOperand(2 * i + 1));
+}
+
+void PhiInst::SetIncomingValue(size_t i, Value* val) {
+  SetOperand(2 * i, val);
+}
+
+void PhiInst::SetIncomingBlock(size_t i, BasicBlock* bb) {
+  SetOperand(2 * i + 1, bb);
+}
+
+void PhiInst::RemoveIncomingBlock(BasicBlock* bb) {
+  std::vector<Value*> new_ops;
+  for (size_t i = 0; i < GetNumIncoming(); ++i) {
+    if (GetIncomingBlock(i) != bb) {
+      new_ops.push_back(GetIncomingValue(i));
+      new_ops.push_back(GetIncomingBlock(i));
+    }
+  }
+  ClearOperands();
+  for (auto* op : new_ops) {
+    AddOperand(op);
+  }
+}
+
 }  // namespace ir