Adding var declaration and set statement handling

compiler/CodeGenVisitor.cpp

@@ -3,45 +3,98 @@
 #include "generated/ifccParser.h"
 
 antlrcpp::Any CodeGenVisitor::visitStmt(ifccParser::StmtContext *ctx) {
+    std::cout << "    ;" << ctx->getText() << "\n";
     return this->visitChildren(ctx);
 }
+
+// Declare a new variable: reserve a slot on the stack, mark as uninitialized.
 antlrcpp::Any CodeGenVisitor::visitDecl_stmt(ifccParser::Decl_stmtContext *ctx) {
-    return 0;
+    std::string name = ctx->VAR_NAME()->getText();
-}
+    if (symbolTable.find(name) != symbolTable.end()) {
-antlrcpp::Any CodeGenVisitor::visitSet_stmt(ifccParser::Set_stmtContext *ctx) {
+        std::cerr << "error: variable '" << name << "' already declared\n";
-    return 0;
+        return 1;
-}
+    }
-antlrcpp::Any CodeGenVisitor::visitVal(ifccParser::ValContext *ctx) {
+    symbolTable[name] = {nextOffset, false};
-    // TODO: return either the const or the variable value from the symbol table
+    nextOffset += 4;
     return 0;
 }
 
-antlrcpp::Any CodeGenVisitor::visitProg(ifccParser::ProgContext *ctx)
+// Assign a value to a variable: evaluate val, store on stack, mark as initialized.
-{
+antlrcpp::Any CodeGenVisitor::visitSet_stmt(ifccParser::Set_stmtContext *ctx) {
-    #ifdef __APPLE__
+    std::string name = ctx->VAR_NAME()->getText();
-    std::cout << ".globl _main\n" ;
+    if (symbolTable.find(name) == symbolTable.end()) {
-    std::cout << " _main: \n" ;
+        std::cerr << "error: variable '" << name << "' undeclared\n";
-    #else
+        return 1;
-    std::cout << ".globl main\n" ;
+    }
-    std::cout << " main: \n" ;
+    int offset = symbolTable[name].offset;
-    #endif
+
+    this->visit(ctx->val());
+
+#ifdef __APPLE__
+    std::cout << "    str w0, [sp, #" << offset << "]\n";
+#else
+    std::cout << "    movl %eax, " << offset << "(%rsp)\n";
+#endif
+
+    symbolTable[name].initialized = true;
+    return 0;
+}
+
+// Load a constant or variable into the accumulator register
+antlrcpp::Any CodeGenVisitor::visitVal(ifccParser::ValContext *ctx) {
+    if (ctx->CONST()) {
+        int val = stoi(ctx->CONST()->getText());
+#ifdef __APPLE__
+        std::cout << "    mov w0, #" << val << "\n";
+#else
+        std::cout << "    movl $" << val << ", %eax\n";
+#endif
+        return val;
+    }
+    std::string name = ctx->VAR_NAME()->getText();
+    if (symbolTable.find(name) == symbolTable.end()) {
+        std::cerr << "error: variable '" << name << "' undeclared\n";
+        return 1;
+    }
+    if (!symbolTable[name].initialized) {
+        std::cerr << "warning: variable '" << name << "' used before initialization\n";
+    }
+    int offset = symbolTable[name].offset;
+#ifdef __APPLE__
+    std::cout << "    ldr w0, [sp, #" << offset << "]\n";
+#else
+    std::cout << "    movl " << offset << "(%rsp), %eax\n";
+#endif
+    return offset;
+}
+
+antlrcpp::Any CodeGenVisitor::visitProg(ifccParser::ProgContext *ctx) {
+#ifdef __APPLE__
+    std::cout << ".globl _main\n";
+    std::cout << "_main:\n";
+    // Prologue: reserve space for local variables
+    std::cout << "    sub sp, sp, #16\n";
+#else
+    std::cout << ".globl main\n";
+    std::cout << "main:\n";
+    // Prologue: reserve space for local variables
+    std::cout << "    subq $16, %rsp\n";
+#endif
 
     this->visitChildren(ctx);
 
+    // Epilogue
+#ifdef __APPLE__
+    std::cout << "    add sp, sp, #16\n";
+#else
+    std::cout << "    addq $16, %rsp\n";
+#endif
     std::cout << "    ret\n";
     return 0;
 }
 
-
+antlrcpp::Any CodeGenVisitor::visitReturn_stmt(ifccParser::Return_stmtContext *ctx) {
-antlrcpp::Any CodeGenVisitor::visitReturn_stmt(ifccParser::Return_stmtContext *ctx)
+    // Evaluate the return value into the accumulator register
-{
+    this->visit(ctx->val());
-    int retval = stoi(ctx->val()->getText());
-
-    #ifdef __APPLE__
-        std::cout << "    mov w0, #" << retval << "\n" ;
-    #else
-        std::cout << "    movl $" << retval << ", %eax\n" ;
-    #endif
-
     return 0;
 }

compiler/CodeGenVisitor.h

@@ -1,23 +1,31 @@
 #pragma once
 
-
+#include <map>
+#include <string>
 #include "antlr4-runtime.h"
 #include "generated/ifccBaseVisitor.h"
 
 
 class  CodeGenVisitor : public ifccBaseVisitor {
+
+	struct VarInfo {
+		int offset;          // stack offset relative to sp
+		bool initialized;    // true after a set_stmt assigns a value
+	};
+
+	// Symbol table: variable name -> VarInfo
+	std::map<std::string, VarInfo> symbolTable;
+	int nextOffset = 0; // first variable at [sp, #0], next at [sp, #4], etc.
+
 	public:
+		std::any visitProg(ifccParser::ProgContext *ctx) override ;
+		std::any visitStmt(ifccParser::StmtContext *ctx) override ;
+		std::any visitReturn_stmt(ifccParser::Return_stmtContext *ctx) override ;
+		std::any visitDecl_stmt(ifccParser::Decl_stmtContext *ctx) override ;
+		std::any visitSet_stmt(ifccParser::Set_stmtContext *ctx) override ;
+		std::any visitVal(ifccParser::ValContext *ctx) override ;
 
-	std::any visitProg(ifccParser::ProgContext *ctx) override ;
-
-	std::any visitStmt(ifccParser::StmtContext *ctx) override ;
-
-	std::any visitReturn_stmt(ifccParser::Return_stmtContext *ctx) override ;
-
-	std::any visitDecl_stmt(ifccParser::Decl_stmtContext *ctx) override ;
-
-	std::any visitSet_stmt(ifccParser::Set_stmtContext *ctx) override ;
-
-	std::any visitVal(ifccParser::ValContext *ctx) override ;
 };
 
+
+

prog/main.c

@@ -1,5 +1,10 @@
 int main() {
+    int z;
     int x;
-    x=42;
+    x = 56;
-    return x;
+    int y;
+    x = y;
+    y = 10;
+    z = x;
+    return z;
 }

testfiles/4_multiple_var.c

@@ -0,0 +1,10 @@
+int main() {
+    int z;
+    int x;
+    x = 56;
+    int y;
+    y = 10;
+    x = y;
+    z = x;
+    return z;
+}