Merge Function with Var

No functional change

chibicc.h

@@ -44,22 +44,22 @@ Token *tokenize(char *input);
 // parse.c
 //
 
-// Local variable
+// Variable or function
 typedef struct Var Var;
 struct Var {
   Var *next;
-  char *name; // Variable name
-  Type *ty;   // Type
-  int offset; // Offset from RBP
-};
+  char *name;    // Variable name
+  Type *ty;      // Type
+  bool is_local; // local or global/function
 
-// Function
-typedef struct Function Function;
-struct Function {
-  Function *next;
-  char *name;
+  // Local variable
+  int offset;
+
+  // Global variable or function
+  bool is_function;
+
+  // Function
   Var *params;
-
   Node *body;
   Var *locals;
   int stack_size;
@@ -116,7 +116,7 @@ struct Node {
   int val;       // Used if kind == ND_NUM
 };
 
-Function *parse(Token *tok);
+Var *parse(Token *tok);
 
 //
 // type.c
@@ -168,4 +168,4 @@ void add_type(Node *node);
 // codegen.c
 //
 
-void codegen(Function *prog);
+void codegen(Var *prog);

codegen.c

@@ -2,7 +2,7 @@
 
 static int depth;
 static char *argreg[] = {"%rdi", "%rsi", "%rdx", "%rcx", "%r8", "%r9"};
-static Function *current_fn;
+static Var *current_fn;
 
 static void gen_expr(Node *node);
 
@@ -193,8 +193,11 @@ static void gen_stmt(Node *node) {
 }
 
 // Assign offsets to local variables.
-static void assign_lvar_offsets(Function *prog) {
-  for (Function *fn = prog; fn; fn = fn->next) {
+static void assign_lvar_offsets(Var *prog) {
+  for (Var *fn = prog; fn; fn = fn->next) {
+    if (!fn->is_function)
+      continue;
+
     int offset = 0;
     for (Var *var = fn->locals; var; var = var->next) {
       offset += var->ty->size;
@@ -204,11 +207,15 @@ static void assign_lvar_offsets(Function *prog) {
   }
 }
 
-void codegen(Function *prog) {
+void codegen(Var *prog) {
   assign_lvar_offsets(prog);
 
-  for (Function *fn = prog; fn; fn = fn->next) {
+  for (Var *fn = prog; fn; fn = fn->next) {
+    if (!fn->is_function)
+      continue;
+
     printf("  .globl %s\n", fn->name);
+    printf("  .text\n");
     printf("%s:\n", fn->name);
     current_fn = fn;
 

main.c

@@ -4,8 +4,9 @@ int main(int argc, char **argv) {
   if (argc != 2)
     error("%s: invalid number of arguments", argv[0]);
 
+  // Tokenize and parse.
   Token *tok = tokenize(argv[1]);
-  Function *prog = parse(tok);
+  Var *prog = parse(tok);
 
   // Traverse the AST to emit assembly.
   codegen(prog);

parse.c

@@ -20,7 +20,8 @@
 
 // All local variable instances created during parsing are
 // accumulated to this list.
-Var *locals;
+static Var *locals;
+static Var *globals;
 
 static Type *typespec(Token **rest, Token *tok);
 static Type *declarator(Token **rest, Token *tok, Type *ty);
@@ -78,15 +79,28 @@ static Node *new_var_node(Var *var, Token *tok) {
   return node;
 }
 
-static Var *new_lvar(char *name, Type *ty) {
+static Var *new_var(char *name, Type *ty) {
   Var *var = calloc(1, sizeof(Var));
   var->name = name;
   var->ty = ty;
+  return var;
+}
+
+static Var *new_lvar(char *name, Type *ty) {
+  Var *var = new_var(name, ty);
+  var->is_local = true;
   var->next = locals;
   locals = var;
   return var;
 }
 
+static Var *new_gvar(char *name, Type *ty) {
+  Var *var = new_var(name, ty);
+  var->next = globals;
+  globals = var;
+  return var;
+}
+
 static char *get_ident(Token *tok) {
   if (tok->kind != TK_IDENT)
     error_tok(tok, "expected an identifier");
@@ -544,29 +558,29 @@ static void create_param_lvars(Type *param) {
   }
 }
 
-static Function *function(Token **rest, Token *tok) {
-  Type *ty = typespec(&tok, tok);
-  ty = declarator(&tok, tok, ty);
+static Token *function(Token *tok, Type *basety) {
+  Type *ty = declarator(&tok, tok, basety);
+
+  Var *fn = new_gvar(get_ident(ty->name), ty);
+  fn->is_function = true;
 
   locals = NULL;
-
-  Function *fn = calloc(1, sizeof(Function));
-  fn->name = get_ident(ty->name);
   create_param_lvars(ty->params);
   fn->params = locals;
 
   tok = skip(tok, "{");
-  fn->body = compound_stmt(rest, tok);
+  fn->body = compound_stmt(&tok, tok);
   fn->locals = locals;
-  return fn;
+  return tok;
 }
 
-// program = function-definition*
-Function *parse(Token *tok) {
-  Function head = {};
-  Function *cur = &head;
+// program = (function-definition | global-variable)*
+Var *parse(Token *tok) {
+  globals = NULL;
 
-  while (tok->kind != TK_EOF)
-    cur = cur->next = function(&tok, tok);
-  return head.next;
+  while (tok->kind != TK_EOF) {
+    Type *basety = typespec(&tok, tok);
+    tok = function(tok, basety);
+  }
+  return globals;
 }