Support function call with up to 6 arguments

chibicc.h

@@ -96,6 +96,7 @@ struct Node {
 
   // Function call
   char *funcname;
+  Node *args;
 
   Var *var;      // Used if kind == ND_VAR
   int val;       // Used if kind == ND_NUM

codegen.c

@@ -1,6 +1,7 @@
 #include "chibicc.h"
 
 int labelseq = 0;
+char *argreg[] = {"rdi", "rsi", "rdx", "rcx", "r8", "r9"};
 
 // Pushes the given node's address to the stack.
 void gen_addr(Node *node) {
@@ -101,10 +102,20 @@ void gen(Node *node) {
     for (Node *n = node->body; n; n = n->next)
       gen(n);
     return;
-  case ND_FUNCALL:
+  case ND_FUNCALL: {
+    int nargs = 0;
+    for (Node *arg = node->args; arg; arg = arg->next) {
+      gen(arg);
+      nargs++;
+    }
+
+    for (int i = nargs - 1; i >= 0; i--)
+      printf("  pop %s\n", argreg[i]);
+
     printf("  call %s\n", node->funcname);
     printf("  push rax\n");
     return;
+  }
   case ND_RETURN:
     gen(node->lhs);
     printf("  pop rax\n");

parse.c

@@ -237,8 +237,22 @@ Node *unary() {
   return primary();
 }
 
-// primary = "(" expr ")" | ident args? | num
-// args = "(" ")"
+// func-args = "(" (assign ("," assign)*)? ")"
+Node *func_args() {
+  if (consume(")"))
+    return NULL;
+
+  Node *head = assign();
+  Node *cur = head;
+  while (consume(",")) {
+    cur->next = assign();
+    cur = cur->next;
+  }
+  expect(")");
+  return head;
+}
+
+// primary = "(" expr ")" | ident func-args? | num
 Node *primary() {
   if (consume("(")) {
     Node *node = expr();
@@ -249,9 +263,9 @@ Node *primary() {
   Token *tok = consume_ident();
   if (tok) {
     if (consume("(")) {
-      expect(")");
       Node *node = new_node(ND_FUNCALL);
       node->funcname = strndup(tok->str, tok->len);
+      node->args = func_args();
       return node;
     }
 

test.sh

@@ -2,6 +2,12 @@
 cat <<EOF | gcc -xc -c -o tmp2.o -
 int ret3() { return 3; }
 int ret5() { return 5; }
+int add(int x, int y) { return x+y; }
+int sub(int x, int y) { return x-y; }
+
+int add6(int a, int b, int c, int d, int e, int f) {
+  return a+b+c+d+e+f;
+}
 EOF
 
 assert() {
@@ -76,5 +82,8 @@ assert 3 'for (;;) return 3; return 5;'
 
 assert 3 'return ret3();'
 assert 5 'return ret5();'
+assert 8 'return add(3, 5);'
+assert 2 'return sub(5, 3);'
+assert 21 'return add6(1,2,3,4,5,6);'
 
 echo OK

tokenize.c

@@ -1,5 +1,9 @@
 #include "chibicc.h"
 
+//
+// Tokenizer
+//
+
 char *user_input;
 Token *token;
 
@@ -138,7 +142,7 @@ Token *tokenize() {
     }
 
     // Single-letter punctuator
-    if (strchr("+-*/()<>;={}", *p)) {
+    if (strchr("+-*/()<>;={},", *p)) {
       cur = new_token(TK_RESERVED, cur, p++, 1);
       continue;
     }