step 14: function call without arguments

9cc.h

@@ -72,6 +72,7 @@ enum {
   ND_WHILE,     // while
   ND_FOR,       // for
   ND_BLOCK,     // block
+  ND_CALL,      // function call
   ND_EQ,        // ==
   ND_NE,        // !=
   ND_LE,        // <=

code_gen.c

@@ -140,6 +140,15 @@ static void gen_block(Node *node) {
   }
 }
 
+static void gen_call(Node *node) {
+  // push argument count
+  printf("  mov   rax, 0\n");
+  // call
+  printf("  call  %s\n", node->name);
+  // push result to stack
+  printf("  push  rax\n");
+}
+
 static bool is_binop(Node *node) {
   return strchr("+-*/<", node->ty) || node->ty == ND_EQ ||
          node->ty == ND_NE || node->ty == ND_LE;
@@ -244,6 +253,11 @@ static void gen(Node *node) {
     return;
   }
 
+  if (node->ty == ND_CALL) {
+    gen_call(node);
+    return;
+  }
+
   if (node->ty == '=') {
     gen_lval(node->lhs);
     gen(node->rhs);

dr

@@ -1,3 +1,3 @@
 #!/bin/bash
 
-docker run -it -v $(pwd)/:/app -w /app buildpack-deps:jessie "$@"
+docker run --rm -it -v $(pwd)/:/app -w /app buildpack-deps:jessie "$@"

parse.c

@@ -8,6 +8,7 @@ const char *NODE_STRING[] = {
   STRING(ND_WHILE),
   STRING(ND_FOR),
   STRING(ND_BLOCK),
+  STRING(ND_CALL),
   STRING(ND_EQ),
   STRING(ND_NE),
   STRING(ND_LE),
@@ -102,7 +103,8 @@ static Node *new_node_cond(int ty, Node *cond) {
   add        = mul ("+" mul | "-" mul)*
   mul        = unary ("*" unary | "/" unary)*
   unary      = ("+" | "-")? term
-  term       = num | "(" expr ")"
+  term       = num | call | (" expr ")"
+  call       = ident [ "()" ]
 */
 
 Node *code[100];
@@ -122,10 +124,6 @@ static Token *current_token() {
   return (Token *)tokens->data[pos];
 }
 
-static Token *next_token() {
-  return (Token *)tokens->data[pos++];
-}
-
 void trace_parse(char *name) {
   if (debug) {
     Token *t = current_token();
@@ -355,6 +353,18 @@ static Node *mul() {
   }
 }
 
+Node *parse_num(Token *t) {
+  return new_node_num(t->val);
+}
+
+Node *parse_call(Token *t) {
+  Node *node = new_node(ND_CALL);
+  node->name = t->name;
+  expect(')');
+
+  return node;
+}
+
 static Node *term() {
   trace_parse("term");
 
@@ -371,12 +381,18 @@ static Node *term() {
 
   // number
   if (t->ty == TK_NUM) {
-    return new_node_num(next_token()->val);
+    Node *node = parse_num(t);
+    pos++;
+    return node;
   }
 
   // identifier
   if (t->ty == TK_IDENT) {
-    return new_node_ident(next_token()->name);
+    pos++;
+    if (consume('(')) {
+      return parse_call(t);
+    }
+    return new_node_ident(t->name);
   }
 
   error("term : invalid token: %s", t->input);

test.sh

@@ -3,6 +3,7 @@
 try(){
   expected="$1"
   input="$2"
+  obj="$3"
 
   echo -n "$input => "
   ./9cc -debug "$input" > tmp.s
@@ -12,7 +13,12 @@ try(){
     exit $status
   fi
 
-  gcc -o tmp tmp.s
+  if [ -n "$obj" ]; then
+    gcc -static -o tmp tmp.s "$obj"
+  else
+    gcc -o tmp tmp.s
+  fi
+
   ./tmp
   actual="$?"
 
@@ -192,5 +198,11 @@ EOF
 )
 
 try 110  "$code"
+
+# step 14 : function call
+
+echo 'int foo() { return 99; }' | gcc -xc -c -o tmp-foo.o -
+try 99 "return foo();" tmp-foo.o
+
 # end test
 echo OK