Strings generation (#56 from wesuRage/main)

Strings generation

include/backend/generator/expressions/generate_string.hpp

@@ -0,0 +1,13 @@
+#ifndef GENERATE_STRING_LITERAL_H
+#define GENERATE_STRING_LITERAL_H
+
+extern "C" {
+  #include "frontend/ast/definitions.h"
+}
+#include <llvm/IR/LLVMContext.h>
+#include <llvm/IR/IRBuilder.h>
+#include "llvm/IR/Module.h"
+
+llvm::Value *generate_string_literal(StringNode *string_node, llvm::LLVMContext &Context, llvm::IRBuilder<> &Builder, llvm::Module &Module);
+
+#endif // GENERATE_STRING_LITERAL_H

src/backend/generator/expressions/generate_expr.cpp

@@ -9,11 +9,16 @@
 #include "backend/generator/expressions/generate_pre_decrement.hpp"
 #include "backend/generator/expressions/generate_assignment_expr.hpp"
 #include "backend/generator/expressions/generate_call.hpp"
+#include "backend/generator/expressions/generate_string.hpp"
 
 llvm::Value *generate_expr(AstNode *node, llvm::LLVMContext &Context, llvm::IRBuilder<> &Builder, llvm::Module &Module) {
     // Checks the node kind, casts the node data into
     // the perspective node type and then generates it.
     switch (node->kind) {
+        case NODE_STRING: {
+            StringNode *string_node = (StringNode *)node->data;
+            return generate_string_literal(string_node, Context, Builder, Module);
+        }
         case NODE_NUMERIC_LITERAL: {
             NumericLiteralNode *num_node = (NumericLiteralNode *)node->data;
             return generate_numeric_literal(num_node, Context);

src/backend/generator/expressions/generate_string.cpp

@@ -0,0 +1,33 @@
+#include "backend/generator/expressions/generate_string.hpp"
+
+llvm::Value *generate_string_literal(StringNode *string_node, llvm::LLVMContext &Context, llvm::IRBuilder<> &Builder, llvm::Module &Module) {
+    // Ensure that the StringNode and the string data are valid
+    if (!string_node || !string_node->string) {
+        throw std::runtime_error("Invalid string node: missing string value.");
+    }
+
+    // This represents the string as a constant array of characters in LLVM
+    llvm::Constant *string_constant = llvm::ConstantDataArray::getString(Context, string_node->string, true);
+
+    // This global variable will hold the constant array
+    llvm::GlobalVariable *global_string = new llvm::GlobalVariable(
+        Module, // The module to which this global variable belongs
+        string_constant->getType(), // The type of the string constant (constant array of chars)
+        true, // Whether the variable is constant
+        llvm::GlobalValue::PrivateLinkage, // The linkage type (private to the module)
+        string_constant, // The actual constant value of the string
+        ".str" // The name of the global variable (used for debugging and identification)
+    );
+
+    // We use `getGetElementPtr` to get a pointer to the start of the array (the first character)
+    llvm::Constant *zero = llvm::ConstantInt::get(llvm::Type::getInt32Ty(Context), 0); // The index for the first element of the array
+    llvm::Constant *indices[] = {zero, zero}; // Indices for the GetElementPtr operation
+    llvm::Constant *string_ptr = llvm::ConstantExpr::getGetElementPtr(
+        string_constant->getType(), // The type of the string constant (constant array)
+        global_string, // The global variable holding the string
+        indices // The indices to access the first character
+    );
+
+    // This pointer can now be used wherever a pointer to the string is needed in the generated IR
+    return string_ptr;
+}