如何使用 llvm::IRBuilder 创建 Add/Sub/Mul/Div？

Question

我正在尝试使用 llvm::IRBuilder 创建 Add/Sub/Mul/Div 操作。但是https://llvm.org/doxygen/classllvm_1_1IRBuilder.html#a4ef70bab263e38c5e0b8c1bf95a5d814里面有很多api：

Value *     CreateAdd (Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false);
Value *     CreateNSWAdd (Value *LHS, Value *RHS, const Twine &Name="");
Value *     CreateNUWAdd (Value *LHS, Value *RHS, const Twine &Name="");
Value *     CreateSub (Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false);
Value *     CreateNSWSub (Value *LHS, Value *RHS, const Twine &Name="");
Value *     CreateNUWSub (Value *LHS, Value *RHS, const Twine &Name="");
Value *     CreateMul (Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false);
Value *     CreateNSWMul (Value *LHS, Value *RHS, const Twine &Name="");
Value *     CreateNUWMul (Value *LHS, Value *RHS, const Twine &Name="");
Value *     CreateUDiv (Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false);
Value *     CreateExactUDiv (Value *LHS, Value *RHS, const Twine &Name="");
Value *     CreateSDiv (Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false);
Value *     CreateExactSDiv (Value *LHS, Value *RHS, const Twine &Name="");

当我想生成 Add/Sub/Mul/Div 操作时应该使用哪一个？

Answer 1

NSW (No Signed Wrap) 和 NUS(No Unsigned Wrap)

当运算结果超出有符号整数类型的可表示范围时，会发生有符号整数溢出。对于 say 和 Add 操作，如果您希望操作的结果环绕该整数类型的 MAX_INT （即 $(2)^(32)$ - 1 对于无符号 i32），请使用 CreateAdd，以防它超过该最大值价值。

通过环绕我们的意思是如果它的值超过 MAX_INT(overflow) 那么它被设置为 MIN_INT。 CreateNSWAdd 将允许包装无符号整数，但会为有符号整数生成毒值（未定义行为）。 CreateNUSAdd 将生成一个加法运算，允许包装有符号整数，但不允许包装它们的无符号配对。

Answer 2

using System;
namespace ConsoleApp1
{
    class Program
    {

        public static int Addition(int value1, int value2)
        {
            return value1 + value2;
        }
        public static int Subtraction(int value1, int value2)
        {
            return value1 - value2;
        }
        public static int Multiplication(int value1, int value2)
        {
            return value1 * value2;
        }
        public static double Division(double value1, double value2)
        {
            return value1 / value2;
        }

        static void Main(string[] args)
        {
            while (true)
            {
                Console.Write("\nEnter Value 1 : ");
                int a = Convert.ToInt32(Console.ReadLine());
                Console.Write("Enter Value 2 : ");
                int b = Convert.ToInt32(Console.ReadLine());

                Console.WriteLine("Please Enter action to be performed :");
                Console.WriteLine("1. Addition");
                Console.WriteLine("2. Subtraction");
                Console.WriteLine("3. Multiplication");
                Console.WriteLine("4. Division");

                int action = Convert.ToInt32(Console.ReadLine());
                string _operation = "";
                double result = 0;
                switch (action)
                {
                    case 1:
                        {
                            result = Addition(a, b);
                            _operation = "+";
                            break;
                        }
                    case 2:
                        {
                            result = Subtraction(a, b);
                            _operation = "-";
                            break;
                        }
                    case 3:
                        {
                            result = Multiplication(a, b);
                            _operation = "*";
                            break;
                        }
                    case 4:
                        {
                            result = Division(a, b);
                            _operation = "/";
                            break;
                        }
                }
                Console.WriteLine("Result A {0} B = {1}", _operation, result);

                char theKey = Console.ReadKey().KeyChar;

                if (theKey == 'y' || theKey == 'Y')
                {
                    Console.Clear();
                    continue;
                }
                else
                {
                    break;
                }
            }


        } 
    }
}