feat: impl define function with no args

.vscode/settings.json

@@ -0,0 +1,9 @@
+{
+    "files.associations": {
+        "cstdlib": "c",
+        "mutex": "c",
+        "compare": "c",
+        "functional": "c",
+        "type_traits": "c"
+    }
+}

50cc.h

@@ -68,7 +68,8 @@ typedef enum {
   ND_FOR_LEFT,
   ND_FOR_RIGHT,
   ND_BLOCK,
-  ND_FUNC
+  ND_FUNC_CALL,
+  ND_FUNC_DEF,
 } NodeKind;
 
 typedef struct Node Node;
@@ -87,6 +88,7 @@ struct Node {
 extern Node *code[];
 
 void program();
+Node *func();
 Node *stmt();
 Node *assign();
 Node *expr();

codegen.c

@@ -9,12 +9,12 @@ void gen_lval(Node *node) {
 
 int genId = 0;
 char *argRegs[] = {"rdi", "rsi", "rdx", "rcx", "r8", "r9"};
-char name[100] = {0};
 
 void gen(Node *node) {
   if (!node) return;
   genId += 1;
   int id = genId;
+  int argCount = 0;
   switch (node->kind) {
     case ND_NUM:
       printf("  push %d\n", node->val);
@@ -88,9 +88,7 @@ void gen(Node *node) {
         printf("  pop rax\n");
       }
       return;
-    case ND_FUNC:
-      memcpy(name, node->funcname, node->len);
-      int argCount = 0;
+    case ND_FUNC_CALL:
       for (int i = 0; node->block[i]; i++) {
         gen(node->block[i]);
         argCount++;
@@ -102,14 +100,25 @@ void gen(Node *node) {
       printf("  and rax, 15\n");
       printf("  jnz .L.call.%d\n", id);
       printf("  mov rax, 0\n");
-      printf("  call %s\n", name);
+      printf("  call %s\n", node->funcname);
       printf("  jmp .L.end.%d\n", id);
       printf(".L.call.%d:\n", id);
       printf("  sub rsp, 8\n");
       printf("mov rax, 0\n");
-      printf("  call %s\n", name);
+      printf("  call %s\n", node->funcname);
       printf("  add rsp, 8\n");
       printf(".L.end.%d:\n", id);
+      printf("  push rax\n");
+      return;
+    case ND_FUNC_DEF:
+      printf("%s:\n", node->funcname);
+      printf("  push rbp\n");
+      printf("  mov rbp, rsp\n");
+      printf("  sub rsp, 208\n");
+      gen(node->lhs);
+      printf("  mov rsp, rbp\n");
+      printf("  pop rbp\n");
+      printf("  ret\n");
       return;
   }
 

main.c

@@ -37,19 +37,10 @@ int main(int argc, char **argv) {
 
   printf(".intel_syntax noprefix\n");
   printf(".global main\n");
-  printf("main:\n");
-
-  printf("  push rbp\n");
-  printf("  mov rbp, rsp\n");
-  printf("  sub rsp, 208\n");
 
   for (int i = 0; code[i]; i++) {
     gen(code[i]);
-    printf("  pop rax\n");
   }
 
-  printf("  mov rsp, rbp\n");
-  printf("  pop rbp\n");
-  printf("  ret\n");
   return 0;
 }

parser.c

@@ -91,12 +91,30 @@ LVar *find_lvar(Token *tok) {
   return NULL;
 }
 
+// program = func*
 void program() {
   int i = 0;
-  while (!at_eof()) code[i++] = stmt();
+  while (!at_eof()) code[i++] = func();
   code[i] = NULL;
 }
 
+// func = ident "(" ")" stmt
+Node *func() {
+  Node *node;
+  Token *tok = consume_ident();
+  if (tok == NULL) {
+    error("invalid function");
+  }
+  node = calloc(1, sizeof(Node));
+  node->kind = ND_FUNC_DEF;
+  node->funcname = calloc(100, sizeof(char));
+  memcpy(node->funcname, tok->str, tok->len);
+  expect("(");
+  expect(")");
+  node->lhs = stmt();
+  return node;
+}
+
 Node *stmt() {
   Node *node;
   if (consume("{")) {
@@ -259,9 +277,9 @@ Node *primary() {
   if (tok) {
     if (consume("(")) {
       Node *node = calloc(1, sizeof(Node));
-      node->kind = ND_FUNC;
-      node->funcname = tok->str;
-      node->len = tok->len;
+      node->kind = ND_FUNC_CALL;
+      node->funcname = calloc(100, sizeof(char));
+      memcpy(node->funcname, tok->str, tok->len);
       node->block = calloc(10, sizeof(Node));
       for (int i = 0; !consume(")"); i++) {
         node->block[i] = expr();

test.sh

@@ -20,7 +20,7 @@ assert(){
     fi
 }
 
-# assert "0" "0;"
+assert 2 "main () { return 2;}"
 # assert 42 "42;"
 # assert 21 "5+20-4;"
 # assert 2 " 5 - 3; "
@@ -85,8 +85,8 @@ assert(){
 
 # assert 10 "foo();"
 
-assert 0 "fooo(4, 1);"
-assert 0 "foooo(1, 1, 1);"
+# assert 0 "fooo(4, 1);"
+# assert 0 "foooo(1, 1, 1);"
 
 
 echo OK