Welcome to part 4 of the "Implementing a language with LLVM" tutorial.
In order to generate LLVM IR, we want some simple setup to get started. First, we define virtual codegen methods in each AST class:
/// ExprAST - Base class for all expression nodes.
class ExprAST {
public:
virtual ~ExprAST() {}
virtual Value *Codegen() = 0;
};
/// NumberExprAST - Expression class for numeric literals like "1.0".
class NumberExprAST : public ExprAST {
double Val;
public:
explicit NumberExprAST(double val) : Val(val) {}
virtual Value *Codegen();
};
...