Add basic "asm" statement

chibicc.h

@@ -202,6 +202,7 @@ typedef enum {
   ND_NUM,       // Integer
   ND_CAST,      // Type cast
   ND_MEMZERO,   // Zero-clear a stack variable
+  ND_ASM,       // "asm"
 } NodeKind;
 
 // AST node type
@@ -246,6 +247,9 @@ struct Node {
   Node *case_next;
   Node *default_case;
 
+  // "asm" string literal
+  char *asm_str;
+
   // Variable
   Obj *var;
 

codegen.c

@@ -1046,6 +1046,9 @@ static void gen_stmt(Node *node) {
   case ND_EXPR_STMT:
     gen_expr(node->lhs);
     return;
+  case ND_ASM:
+    println("  %s", node->asm_str);
+    return;
   }
 
   error_tok(node->tok, "invalid statement");

parse.c

@@ -1410,6 +1410,22 @@ static bool is_typename(Token *tok) {
   return find_typedef(tok);
 }
 
+// asm-stmt = "asm" ("volatile" | "inline")* "(" string-literal ")"
+static Node *asm_stmt(Token **rest, Token *tok) {
+  Node *node = new_node(ND_ASM, tok);
+  tok = tok->next;
+
+  while (equal(tok, "volatile") || equal(tok, "inline"))
+    tok = tok->next;
+
+  tok = skip(tok, "(");
+  if (tok->kind != TK_STR || tok->ty->base->kind != TY_CHAR)
+    error_tok(tok, "expected string literal");
+  node->asm_str = tok->str;
+  *rest = skip(tok->next, ")");
+  return node;
+}
+
 // stmt = "return" expr? ";"
 //      | "if" "(" expr ")" stmt ("else" stmt)?
 //      | "switch" "(" expr ")" stmt
@@ -1418,6 +1434,7 @@ static bool is_typename(Token *tok) {
 //      | "for" "(" expr-stmt expr? ";" expr? ")" stmt
 //      | "while" "(" expr ")" stmt
 //      | "do" stmt "while" "(" expr ")" ";"
+//      | "asm" asm-stmt
 //      | "goto" ident ";"
 //      | "break" ";"
 //      | "continue" ";"
@@ -1573,6 +1590,9 @@ static Node *stmt(Token **rest, Token *tok) {
     return node;
   }
 
+  if (equal(tok, "asm"))
+    return asm_stmt(rest, tok);
+
   if (equal(tok, "goto")) {
     Node *node = new_node(ND_GOTO, tok);
     node->label = get_ident(tok->next);

test/asm.c

@@ -0,0 +1,23 @@
+#include "test.h"
+
+char *asm_fn1(void) {
+  asm("mov $50, %rax\n\t"
+      "mov %rbp, %rsp\n\t"
+      "pop %rbp\n\t"
+      "ret");
+}
+
+char *asm_fn2(void) {
+  asm inline volatile("mov $55, %rax\n\t"
+                      "mov %rbp, %rsp\n\t"
+                      "pop %rbp\n\t"
+                      "ret");
+}
+
+int main() {
+  ASSERT(50, asm_fn1());
+  ASSERT(55, asm_fn2());
+
+  printf("OK\n");
+  return 0;
+}

tokenize.c

@@ -163,7 +163,7 @@ static bool is_keyword(Token *tok) {
     "default", "extern", "_Alignof", "_Alignas", "do", "signed",
     "unsigned", "const", "volatile", "auto", "register", "restrict",
     "__restrict", "__restrict__", "_Noreturn", "float", "double",
-    "typeof",
+    "typeof", "asm",
   };
 
   for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++)