Add { ... }

chibicc.h

@@ -72,6 +72,7 @@ typedef enum {
   ND_LE,        // <=
   ND_ASSIGN,    // =
   ND_RETURN,    // "return"
+  ND_BLOCK,     // { ... }
   ND_EXPR_STMT, // Expression statement
   ND_VAR,       // Variable
   ND_NUM,       // Integer
@@ -83,6 +84,10 @@ struct Node {
   Node *next;    // Next node
   Node *lhs;     // Left-hand side
   Node *rhs;     // Right-hand side
+
+  // Block
+  Node *body;
+
   Obj *var;      // Used if kind == ND_VAR
   int val;       // Used if kind == ND_NUM
 };

codegen.c

@@ -95,6 +95,10 @@ static void gen_expr(Node *node) {
 
 static void gen_stmt(Node *node) {
   switch (node->kind) {
+  case ND_BLOCK:
+    for (Node *n = node->body; n; n = n->next)
+      gen_stmt(n);
+    return;
   case ND_RETURN:
     gen_expr(node->lhs);
     printf("  jmp .L.return\n");
@@ -128,10 +132,8 @@ void codegen(Function *prog) {
   printf("  mov %%rsp, %%rbp\n");
   printf("  sub $%d, %%rsp\n", prog->stack_size);
 
-  for (Node *n = prog->body; n; n = n->next) {
-    gen_stmt(n);
-    assert(depth == 0);
-  }
+  gen_stmt(prog->body);
+  assert(depth == 0);
 
   printf(".L.return:\n");
   printf("  mov %%rbp, %%rsp\n");

parse.c

@@ -4,6 +4,7 @@
 // accumulated to this list.
 Obj *locals;
 
+static Node *compound_stmt(Token **rest, Token *tok);
 static Node *expr(Token **rest, Token *tok);
 static Node *expr_stmt(Token **rest, Token *tok);
 static Node *assign(Token **rest, Token *tok);
@@ -62,6 +63,7 @@ static Obj *new_lvar(char *name) {
 }
 
 // stmt = "return" expr ";"
+//      | "{" compound-stmt
 //      | expr-stmt
 static Node *stmt(Token **rest, Token *tok) {
   if (equal(tok, "return")) {
@@ -70,9 +72,25 @@ static Node *stmt(Token **rest, Token *tok) {
     return node;
   }
 
+  if (equal(tok, "{"))
+    return compound_stmt(rest, tok->next);
+
   return expr_stmt(rest, tok);
 }
 
+// compound-stmt = stmt* "}"
+static Node *compound_stmt(Token **rest, Token *tok) {
+  Node head = {};
+  Node *cur = &head;
+  while (!equal(tok, "}"))
+    cur = cur->next = stmt(&tok, tok);
+
+  Node *node = new_node(ND_BLOCK);
+  node->body = head.next;
+  *rest = tok->next;
+  return node;
+}
+
 // expr-stmt = expr ";"
 static Node *expr_stmt(Token **rest, Token *tok) {
   Node *node = new_unary(ND_EXPR_STMT, expr(&tok, tok));
@@ -223,14 +241,10 @@ static Node *primary(Token **rest, Token *tok) {
 
 // program = stmt*
 Function *parse(Token *tok) {
-  Node head = {};
-  Node *cur = &head;
-
-  while (tok->kind != TK_EOF)
-    cur = cur->next = stmt(&tok, tok);
+  tok = skip(tok, "{");
 
   Function *prog = calloc(1, sizeof(Function));
-  prog->body = head.next;
+  prog->body = compound_stmt(&tok, tok);
   prog->locals = locals;
   return prog;
 }

test.sh

@@ -16,47 +16,49 @@ assert() {
   fi
 }
 
-assert 0 'return 0;'
-assert 42 'return 42;'
-assert 21 'return 5+20-4;'
-assert 41 'return  12 + 34 - 5 ;'
-assert 47 'return 5+6*7;'
-assert 15 'return 5*(9-6);'
-assert 4 'return (3+5)/2;'
-assert 10 'return -10+20;'
-assert 10 'return - -10;'
-assert 10 'return - - +10;'
+assert 0 '{ return 0; }'
+assert 42 '{ return 42; }'
+assert 21 '{ return 5+20-4; }'
+assert 41 '{ return  12 + 34 - 5 ; }'
+assert 47 '{ return 5+6*7; }'
+assert 15 '{ return 5*(9-6); }'
+assert 4 '{ return (3+5)/2; }'
+assert 10 '{ return -10+20; }'
+assert 10 '{ return - -10; }'
+assert 10 '{ return - - +10; }'
 
-assert 0 'return 0==1;'
-assert 1 'return 42==42;'
-assert 1 'return 0!=1;'
-assert 0 'return 42!=42;'
+assert 0 '{ return 0==1; }'
+assert 1 '{ return 42==42; }'
+assert 1 '{ return 0!=1; }'
+assert 0 '{ return 42!=42; }'
 
-assert 1 'return 0<1;'
-assert 0 'return 1<1;'
-assert 0 'return 2<1;'
-assert 1 'return 0<=1;'
-assert 1 'return 1<=1;'
-assert 0 'return 2<=1;'
+assert 1 '{ return 0<1; }'
+assert 0 '{ return 1<1; }'
+assert 0 '{ return 2<1; }'
+assert 1 '{ return 0<=1; }'
+assert 1 '{ return 1<=1; }'
+assert 0 '{ return 2<=1; }'
 
-assert 1 'return 1>0;'
-assert 0 'return 1>1;'
-assert 0 'return 1>2;'
-assert 1 'return 1>=0;'
-assert 1 'return 1>=1;'
-assert 0 'return 1>=2;'
+assert 1 '{ return 1>0; }'
+assert 0 '{ return 1>1; }'
+assert 0 '{ return 1>2; }'
+assert 1 '{ return 1>=0; }'
+assert 1 '{ return 1>=1; }'
+assert 0 '{ return 1>=2; }'
 
-assert 3 'a=3; return a;'
-assert 8 'a=3; z=5; return a+z;'
+assert 3 '{ a=3; return a; }'
+assert 8 '{ a=3; z=5; return a+z; }'
 
-assert 3 'a=3; return a;'
-assert 8 'a=3; z=5; return a+z;'
-assert 6 'a=b=3; return a+b;'
-assert 3 'foo=3; return foo;'
-assert 8 'foo123=3; bar=5; return foo123+bar;'
+assert 3 '{ a=3; return a; }'
+assert 8 '{ a=3; z=5; return a+z; }'
+assert 6 '{ a=b=3; return a+b; }'
+assert 3 '{ foo=3; return foo; }'
+assert 8 '{ foo123=3; bar=5; return foo123+bar; }'
 
-assert 1 'return 1; 2; 3;'
-assert 2 '1; return 2; 3;'
-assert 3 '1; 2; return 3;'
+assert 1 '{ return 1; 2; 3; }'
+assert 2 '{ 1; return 2; 3; }'
+assert 3 '{ 1; 2; return 3; }'
+
+assert 3 '{ {1; {2;} return 3;} }'
 
 echo OK