Support function call with up to 6 arguments

chibicc.h

@@ -108,6 +108,7 @@ struct Node {
 
   // Function call
   char *funcname;
+  Node *args;
 
   Obj *var;      // Used if kind == ND_VAR
   int val;       // Used if kind == ND_NUM

codegen.c

 #include "chibicc.h"
 
 static int depth;
+static char *argreg[] = {"%rdi", "%rsi", "%rdx", "%rcx", "%r8", "%r9"};
 
 static void gen_expr(Node *node);
 
@@ -68,11 +69,22 @@ static void gen_expr(Node *node) {
     pop("%rdi");
     printf("  mov %%rax, (%%rdi)\n");
     return;
-  case ND_FUNCALL:
+  case ND_FUNCALL: {
+    int nargs = 0;
+    for (Node *arg = node->args; arg; arg = arg->next) {
+      gen_expr(arg);
+      push();
+      nargs++;
+    }
+
+    for (int i = nargs - 1; i >= 0; i--)
+      pop(argreg[i]);
+
     printf("  mov $0, %%rax\n");
     printf("  call %s\n", node->funcname);
     return;
   }
+  }
 
   gen_expr(node->rhs);
   push();

parse.c

@@ -418,8 +418,29 @@ static Node *unary(Token **rest, Token *tok) {
   return primary(rest, tok);
 }
 
-// primary = "(" expr ")" | ident args? | num
-// args = "(" ")"
+// funcall = ident "(" (assign ("," assign)*)? ")"
+static Node *funcall(Token **rest, Token *tok) {
+  Token *start = tok;
+  tok = tok->next->next;
+
+  Node head = {};
+  Node *cur = &head;
+
+  while (!equal(tok, ")")) {
+    if (cur != &head)
+      tok = skip(tok, ",");
+    cur = cur->next = assign(&tok, tok);
+  }
+
+  *rest = skip(tok, ")");
+
+  Node *node = new_node(ND_FUNCALL, start);
+  node->funcname = strndup(start->loc, start->len);
+  node->args = head.next;
+  return node;
+}
+
+// primary = "(" expr ")" | ident func-args? | num
 static Node *primary(Token **rest, Token *tok) {
   if (equal(tok, "(")) {
     Node *node = expr(&tok, tok->next);
@@ -429,12 +450,8 @@ static Node *primary(Token **rest, Token *tok) {
 
   if (tok->kind == TK_IDENT) {
     // Function call
-    if (equal(tok->next, "(")) {
-      Node *node = new_node(ND_FUNCALL, tok);
-      node->funcname = strndup(tok->loc, tok->len);
-      *rest = skip(tok->next->next, ")");
-      return node;
-    }
+    if (equal(tok->next, "("))
+      return funcall(rest, tok);
 
     // Variable
     Obj *var = find_var(tok);

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() {
@@ -99,5 +105,10 @@ assert 8 '{ int x=3, y=5; return x+y; }'
 
 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); }'
+assert 66 '{ return add6(1,2,add6(3,4,5,6,7,8),9,10,11); }'
+assert 136 '{ return add6(1,2,add6(3,add6(4,5,6,7,8,9),10,11,12,13),14,15,16); }'
 
 echo OK