Initial public snapshot

With code from Bill. Thanks Bill!

1 files changed, 3368 insertions, 0 deletions

diff --git a/src/3p/chibicc/parse.c b/src/3p/chibicc/parse.c
new file mode 100644
index 0000000..6acaeb8
--- /dev/null
+++ b/src/3p/chibicc/parse.c
@@ -0,0 +1,3368 @@
+// This file contains a recursive descent parser for C.
+//
+// Most functions in this file are named after the symbols they are
+// supposed to read from an input token list. For example, stmt() is
+// responsible for reading a statement from a token list. The function
+// then construct an AST node representing a statement.
+//
+// Each function conceptually returns two values, an AST node and
+// remaining part of the input tokens. Since C doesn't support
+// multiple return values, the remaining tokens are returned to the
+// caller via a pointer argument.
+//
+// Input tokens are represented by a linked list. Unlike many recursive
+// descent parsers, we don't have the notion of the "input token stream".
+// Most parsing functions don't change the global state of the parser.
+// So it is very easy to lookahead arbitrary number of tokens in this
+// parser.
+
+#include "chibicc.h"
+
+// Scope for local variables, global variables, typedefs
+// or enum constants
+typedef struct {
+  Obj *var;
+  Type *type_def;
+  Type *enum_ty;
+  int enum_val;
+} VarScope;
+
+// Represents a block scope.
+typedef struct Scope Scope;
+struct Scope {
+  Scope *next;
+
+  // C has two block scopes; one is for variables/typedefs and
+  // the other is for struct/union/enum tags.
+  HashMap vars;
+  HashMap tags;
+};
+
+// Variable attributes such as typedef or extern.
+typedef struct {
+  bool is_typedef;
+  bool is_static;
+  bool is_extern;
+  bool is_inline;
+  bool is_tls;
+  int align;
+} VarAttr;
+
+// This struct represents a variable initializer. Since initializers
+// can be nested (e.g. `int x[2][2] = {{1, 2}, {3, 4}}`), this struct
+// is a tree data structure.
+typedef struct Initializer Initializer;
+struct Initializer {
+  Initializer *next;
+  Type *ty;
+  Token *tok;
+  bool is_flexible;
+
+  // If it's not an aggregate type and has an initializer,
+  // `expr` has an initialization expression.
+  Node *expr;
+
+  // If it's an initializer for an aggregate type (e.g. array or struct),
+  // `children` has initializers for its children.
+  Initializer **children;
+
+  // Only one member can be initialized for a union.
+  // `mem` is used to clarify which member is initialized.
+  Member *mem;
+};
+
+// For local variable initializer.
+typedef struct InitDesg InitDesg;
+struct InitDesg {
+  InitDesg *next;
+  int idx;
+  Member *member;
+  Obj *var;
+};
+
+// All local variable instances created during parsing are
+// accumulated to this list.
+static Obj *locals;
+
+// Likewise, global variables are accumulated to this list.
+static Obj *globals;
+
+static Scope *scope = &(Scope){};
+
+// Points to the function object the parser is currently parsing.
+static Obj *current_fn;
+
+// Lists of all goto statements and labels in the curent function.
+static Node *gotos;
+static Node *labels;
+
+// Current "goto" and "continue" jump targets.
+static char *brk_label;
+static char *cont_label;
+
+// Points to a node representing a switch if we are parsing
+// a switch statement. Otherwise, NULL.
+static Node *current_switch;
+
+static Obj *builtin_alloca;
+
+static bool is_typename(Token *tok);
+static Type *declspec(Token **rest, Token *tok, VarAttr *attr);
+static Type *typename(Token **rest, Token *tok);
+static Type *enum_specifier(Token **rest, Token *tok);
+static Type *typeof_specifier(Token **rest, Token *tok);
+static Type *type_suffix(Token **rest, Token *tok, Type *ty);
+static Type *declarator(Token **rest, Token *tok, Type *ty);
+static Node *declaration(Token **rest, Token *tok, Type *basety, VarAttr *attr);
+static void array_initializer2(Token **rest, Token *tok, Initializer *init, int i);
+static void struct_initializer2(Token **rest, Token *tok, Initializer *init, Member *mem);
+static void initializer2(Token **rest, Token *tok, Initializer *init);
+static Initializer *initializer(Token **rest, Token *tok, Type *ty, Type **new_ty);
+static Node *lvar_initializer(Token **rest, Token *tok, Obj *var);
+static void gvar_initializer(Token **rest, Token *tok, Obj *var);
+static Node *compound_stmt(Token **rest, Token *tok);
+static Node *stmt(Token **rest, Token *tok);
+static Node *expr_stmt(Token **rest, Token *tok);
+static Node *expr(Token **rest, Token *tok);
+static int64_t eval(Node *node);
+static int64_t eval2(Node *node, char ***label);
+static int64_t eval_rval(Node *node, char ***label);
+static bool is_const_expr(Node *node);
+static Node *assign(Token **rest, Token *tok);
+static Node *logor(Token **rest, Token *tok);
+static double eval_double(Node *node);
+static Node *conditional(Token **rest, Token *tok);
+static Node *logand(Token **rest, Token *tok);
+static Node *bitor(Token **rest, Token *tok);
+static Node *bitxor(Token **rest, Token *tok);
+static Node *bitand(Token **rest, Token *tok);
+static Node *equality(Token **rest, Token *tok);
+static Node *relational(Token **rest, Token *tok);
+static Node *shift(Token **rest, Token *tok);
+static Node *add(Token **rest, Token *tok);
+static Node *new_add(Node *lhs, Node *rhs, Token *tok);
+static Node *new_sub(Node *lhs, Node *rhs, Token *tok);
+static Node *mul(Token **rest, Token *tok);
+static Node *cast(Token **rest, Token *tok);
+static Member *get_struct_member(Type *ty, Token *tok);
+static Type *struct_decl(Token **rest, Token *tok);
+static Type *union_decl(Token **rest, Token *tok);
+static Node *postfix(Token **rest, Token *tok);
+static Node *funcall(Token **rest, Token *tok, Node *node);
+static Node *unary(Token **rest, Token *tok);
+static Node *primary(Token **rest, Token *tok);
+static Token *parse_typedef(Token *tok, Type *basety);
+static bool is_function(Token *tok);
+static Token *function(Token *tok, Type *basety, VarAttr *attr);
+static Token *global_variable(Token *tok, Type *basety, VarAttr *attr);
+
+static int align_down(int n, int align) {
+  return align_to(n - align + 1, align);
+}
+
+static void enter_scope(void) {
+  Scope *sc = calloc(1, sizeof(Scope));
+  sc->next = scope;
+  scope = sc;
+}
+
+static void leave_scope(void) {
+  scope = scope->next;
+}
+
+// Find a variable by name.
+static VarScope *find_var(Token *tok) {
+  for (Scope *sc = scope; sc; sc = sc->next) {
+    VarScope *sc2 = hashmap_get2(&sc->vars, tok->loc, tok->len);
+    if (sc2)
+      return sc2;
+  }
+  return NULL;
+}
+
+static Type *find_tag(Token *tok) {
+  for (Scope *sc = scope; sc; sc = sc->next) {
+    Type *ty = hashmap_get2(&sc->tags, tok->loc, tok->len);
+    if (ty)
+      return ty;
+  }
+  return NULL;
+}
+
+static Node *new_node(NodeKind kind, Token *tok) {
+  Node *node = calloc(1, sizeof(Node));
+  node->kind = kind;
+  node->tok = tok;
+  return node;
+}
+
+static Node *new_binary(NodeKind kind, Node *lhs, Node *rhs, Token *tok) {
+  Node *node = new_node(kind, tok);
+  node->lhs = lhs;
+  node->rhs = rhs;
+  return node;
+}
+
+static Node *new_unary(NodeKind kind, Node *expr, Token *tok) {
+  Node *node = new_node(kind, tok);
+  node->lhs = expr;
+  return node;
+}
+
+static Node *new_num(int64_t val, Token *tok) {
+  Node *node = new_node(ND_NUM, tok);
+  node->val = val;
+  return node;
+}
+
+static Node *new_long(int64_t val, Token *tok) {
+  Node *node = new_node(ND_NUM, tok);
+  node->val = val;
+  node->ty = ty_long;
+  return node;
+}
+
+static Node *new_ulong(long val, Token *tok) {
+  Node *node = new_node(ND_NUM, tok);
+  node->val = val;
+  node->ty = ty_ulong;
+  return node;
+}
+
+static Node *new_var_node(Obj *var, Token *tok) {
+  Node *node = new_node(ND_VAR, tok);
+  node->var = var;
+  return node;
+}
+
+static Node *new_vla_ptr(Obj *var, Token *tok) {
+  Node *node = new_node(ND_VLA_PTR, tok);
+  node->var = var;
+  return node;
+}
+
+Node *new_cast(Node *expr, Type *ty) {
+  add_type(expr);
+
+  Node *node = calloc(1, sizeof(Node));
+  node->kind = ND_CAST;
+  node->tok = expr->tok;
+  node->lhs = expr;
+  node->ty = copy_type(ty);
+  return node;
+}
+
+static VarScope *push_scope(char *name) {
+  VarScope *sc = calloc(1, sizeof(VarScope));
+  hashmap_put(&scope->vars, name, sc);
+  return sc;
+}
+
+static Initializer *new_initializer(Type *ty, bool is_flexible) {
+  Initializer *init = calloc(1, sizeof(Initializer));
+  init->ty = ty;
+
+  if (ty->kind == TY_ARRAY) {
+    if (is_flexible && ty->size < 0) {
+      init->is_flexible = true;
+      return init;
+    }
+
+    init->children = calloc(ty->array_len, sizeof(Initializer *));
+    for (int i = 0; i < ty->array_len; i++)
+      init->children[i] = new_initializer(ty->base, false);
+    return init;
+  }
+
+  if (ty->kind == TY_STRUCT || ty->kind == TY_UNION) {
+    // Count the number of struct members.
+    int len = 0;
+    for (Member *mem = ty->members; mem; mem = mem->next)
+      len++;
+
+    init->children = calloc(len, sizeof(Initializer *));
+
+    for (Member *mem = ty->members; mem; mem = mem->next) {
+      if (is_flexible && ty->is_flexible && !mem->next) {
+        Initializer *child = calloc(1, sizeof(Initializer));
+        child->ty = mem->ty;
+        child->is_flexible = true;
+        init->children[mem->idx] = child;
+      } else {
+        init->children[mem->idx] = new_initializer(mem->ty, false);
+      }
+    }
+    return init;
+  }
+
+  return init;
+}
+
+static Obj *new_var(char *name, Type *ty) {
+  Obj *var = calloc(1, sizeof(Obj));
+  var->name = name;
+  var->ty = ty;
+  var->align = ty->align;
+  push_scope(name)->var = var;
+  return var;
+}
+
+static Obj *new_lvar(char *name, Type *ty) {
+  Obj *var = new_var(name, ty);
+  var->is_local = true;
+  var->next = locals;
+  locals = var;
+  return var;
+}
+
+static Obj *new_gvar(char *name, Type *ty) {
+  Obj *var = new_var(name, ty);
+  var->next = globals;
+  var->is_static = true;
+  var->is_definition = true;
+  globals = var;
+  return var;
+}
+
+static char *new_unique_name(void) {
+  static int id = 0;
+  return format(".L..%d", id++);
+}
+
+static Obj *new_anon_gvar(Type *ty) {
+  return new_gvar(new_unique_name(), ty);
+}
+
+static Obj *new_string_literal(char *p, Type *ty) {
+  Obj *var = new_anon_gvar(ty);
+  var->init_data = p;
+  return var;
+}
+
+static char *get_ident(Token *tok) {
+  if (tok->kind != TK_IDENT)
+    error_tok(tok, "expected an identifier");
+  return strndup(tok->loc, tok->len);
+}
+
+static Type *find_typedef(Token *tok) {
+  if (tok->kind == TK_IDENT) {
+    VarScope *sc = find_var(tok);
+    if (sc)
+      return sc->type_def;
+  }
+  return NULL;
+}
+
+static void push_tag_scope(Token *tok, Type *ty) {
+  hashmap_put2(&scope->tags, tok->loc, tok->len, ty);
+}
+
+// declspec = ("void" | "_Bool" | "char" | "short" | "int" | "long"
+//             | "typedef" | "static" | "extern" | "inline"
+//             | "_Thread_local" | "__thread"
+//             | "signed" | "unsigned"
+//             | struct-decl | union-decl | typedef-name
+//             | enum-specifier | typeof-specifier
+//             | "const" | "volatile" | "auto" | "register" | "restrict"
+//             | "__restrict" | "__restrict__" | "_Noreturn")+
+//
+// The order of typenames in a type-specifier doesn't matter. For
+// example, `int long static` means the same as `static long int`.
+// That can also be written as `static long` because you can omit
+// `int` if `long` or `short` are specified. However, something like
+// `char int` is not a valid type specifier. We have to accept only a
+// limited combinations of the typenames.
+//
+// In this function, we count the number of occurrences of each typename
+// while keeping the "current" type object that the typenames up
+// until that point represent. When we reach a non-typename token,
+// we returns the current type object.
+static Type *declspec(Token **rest, Token *tok, VarAttr *attr) {
+  // We use a single integer as counters for all typenames.
+  // For example, bits 0 and 1 represents how many times we saw the
+  // keyword "void" so far. With this, we can use a switch statement
+  // as you can see below.
+  enum {
+    VOID     = 1 << 0,
+    BOOL     = 1 << 2,
+    CHAR     = 1 << 4,
+    SHORT    = 1 << 6,
+    INT      = 1 << 8,
+    LONG     = 1 << 10,
+    FLOAT    = 1 << 12,
+    DOUBLE   = 1 << 14,
+    OTHER    = 1 << 16,
+    SIGNED   = 1 << 17,
+    UNSIGNED = 1 << 18,
+  };
+
+  Type *ty = ty_int;
+  int counter = 0;
+  bool is_atomic = false;
+
+  while (is_typename(tok)) {
+    // Handle storage class specifiers.
+    if (equal(tok, "typedef") || equal(tok, "static") || equal(tok, "extern") ||
+        equal(tok, "inline") || equal(tok, "_Thread_local") || equal(tok, "__thread")) {
+      if (!attr)
+        error_tok(tok, "storage class specifier is not allowed in this context");
+
+      if (equal(tok, "typedef"))
+        attr->is_typedef = true;
+      else if (equal(tok, "static"))
+        attr->is_static = true;
+      else if (equal(tok, "extern"))
+        attr->is_extern = true;
+      else if (equal(tok, "inline"))
+        attr->is_inline = true;
+      else
+        attr->is_tls = true;
+
+      if (attr->is_typedef &&
+          attr->is_static + attr->is_extern + attr->is_inline + attr->is_tls > 1)
+        error_tok(tok, "typedef may not be used together with static,"
+                  " extern, inline, __thread or _Thread_local");
+      tok = tok->next;
+      continue;
+    }
+
+    // These keywords are recognized but ignored.
+    if (consume(&tok, tok, "const") || consume(&tok, tok, "volatile") ||
+        consume(&tok, tok, "auto") || consume(&tok, tok, "register") ||
+        consume(&tok, tok, "restrict") || consume(&tok, tok, "__restrict") ||
+        consume(&tok, tok, "__restrict__") || consume(&tok, tok, "_Noreturn"))
+      continue;
+
+    if (equal(tok, "_Atomic")) {
+      tok = tok->next;
+      if (equal(tok , "(")) {
+        ty = typename(&tok, tok->next);
+        tok = skip(tok, ")");
+      }
+      is_atomic = true;
+      continue;
+    }
+
+    if (equal(tok, "_Alignas")) {
+      if (!attr)
+        error_tok(tok, "_Alignas is not allowed in this context");
+      tok = skip(tok->next, "(");
+
+      if (is_typename(tok))
+        attr->align = typename(&tok, tok)->align;
+      else
+        attr->align = const_expr(&tok, tok);
+      tok = skip(tok, ")");
+      continue;
+    }
+
+    // Handle user-defined types.
+    Type *ty2 = find_typedef(tok);
+    if (equal(tok, "struct") || equal(tok, "union") || equal(tok, "enum") ||
+        equal(tok, "typeof") || ty2) {
+      if (counter)
+        break;
+
+      if (equal(tok, "struct")) {
+        ty = struct_decl(&tok, tok->next);
+      } else if (equal(tok, "union")) {
+        ty = union_decl(&tok, tok->next);
+      } else if (equal(tok, "enum")) {
+        ty = enum_specifier(&tok, tok->next);
+      } else if (equal(tok, "typeof")) {
+        ty = typeof_specifier(&tok, tok->next);
+      } else {
+        ty = ty2;
+        tok = tok->next;
+      }
+
+      counter += OTHER;
+      continue;
+    }
+
+    // Handle built-in types.
+    if (equal(tok, "void"))
+      counter += VOID;
+    else if (equal(tok, "_Bool"))
+      counter += BOOL;
+    else if (equal(tok, "char"))
+      counter += CHAR;
+    else if (equal(tok, "short"))
+      counter += SHORT;
+    else if (equal(tok, "int"))
+      counter += INT;
+    else if (equal(tok, "long"))
+      counter += LONG;
+    else if (equal(tok, "float"))
+      counter += FLOAT;
+    else if (equal(tok, "double"))
+      counter += DOUBLE;
+    else if (equal(tok, "signed"))
+      counter |= SIGNED;
+    else if (equal(tok, "unsigned"))
+      counter |= UNSIGNED;
+    else
+      unreachable();
+
+    switch (counter) {
+    case VOID:
+      ty = ty_void;
+      break;
+    case BOOL:
+      ty = ty_bool;
+      break;
+    case CHAR:
+    case SIGNED + CHAR:
+      ty = ty_char;
+      break;
+    case UNSIGNED + CHAR:
+      ty = ty_uchar;
+      break;
+    case SHORT:
+    case SHORT + INT:
+    case SIGNED + SHORT:
+    case SIGNED + SHORT + INT:
+      ty = ty_short;
+      break;
+    case UNSIGNED + SHORT:
+    case UNSIGNED + SHORT + INT:
+      ty = ty_ushort;
+      break;
+    case INT:
+    case SIGNED:
+    case SIGNED + INT:
+      ty = ty_int;
+      break;
+    case UNSIGNED:
+    case UNSIGNED + INT:
+      ty = ty_uint;
+      break;
+    case LONG:
+    case LONG + INT:
+    case LONG + LONG:
+    case LONG + LONG + INT:
+    case SIGNED + LONG:
+    case SIGNED + LONG + INT:
+    case SIGNED + LONG + LONG:
+    case SIGNED + LONG + LONG + INT:
+      ty = ty_long;
+      break;
+    case UNSIGNED + LONG:
+    case UNSIGNED + LONG + INT:
+    case UNSIGNED + LONG + LONG:
+    case UNSIGNED + LONG + LONG + INT:
+      ty = ty_ulong;
+      break;
+    case FLOAT:
+      ty = ty_float;
+      break;
+    case DOUBLE:
+      ty = ty_double;
+      break;
+    case LONG + DOUBLE:
+      ty = ty_ldouble;
+      break;
+    default:
+      error_tok(tok, "invalid type");
+    }
+
+    tok = tok->next;
+  }
+
+  if (is_atomic) {
+    ty = copy_type(ty);
+    ty->is_atomic = true;
+  }
+
+  *rest = tok;
+  return ty;
+}
+
+// func-params = ("void" | param ("," param)* ("," "...")?)? ")"
+// param       = declspec declarator
+static Type *func_params(Token **rest, Token *tok, Type *ty) {
+  if (equal(tok, "void") && equal(tok->next, ")")) {
+    *rest = tok->next->next;
+    return func_type(ty);
+  }
+
+  Type head = {};
+  Type *cur = &head;
+  bool is_variadic = false;
+
+  while (!equal(tok, ")")) {
+    if (cur != &head)
+      tok = skip(tok, ",");
+
+    if (equal(tok, "...")) {
+      is_variadic = true;
+      tok = tok->next;
+      skip(tok, ")");
+      break;
+    }
+
+    Type *ty2 = declspec(&tok, tok, NULL);
+    ty2 = declarator(&tok, tok, ty2);
+
+    Token *name = ty2->name;
+
+    if (ty2->kind == TY_ARRAY) {
+      // "array of T" is converted to "pointer to T" only in the parameter
+      // context. For example, *argv[] is converted to **argv by this.
+      ty2 = pointer_to(ty2->base);
+      ty2->name = name;
+    } else if (ty2->kind == TY_FUNC) {
+      // Likewise, a function is converted to a pointer to a function
+      // only in the parameter context.
+      ty2 = pointer_to(ty2);
+      ty2->name = name;
+    }
+
+    cur = cur->next = copy_type(ty2);
+  }
+
+  if (cur == &head)
+    is_variadic = true;
+
+  ty = func_type(ty);
+  ty->params = head.next;
+  ty->is_variadic = is_variadic;
+  *rest = tok->next;
+  return ty;
+}
+
+// array-dimensions = ("static" | "restrict")* const-expr? "]" type-suffix
+static Type *array_dimensions(Token **rest, Token *tok, Type *ty) {
+  while (equal(tok, "static") || equal(tok, "restrict"))
+    tok = tok->next;
+
+  if (equal(tok, "]")) {
+    ty = type_suffix(rest, tok->next, ty);
+    return array_of(ty, -1);
+  }
+
+  Node *expr = conditional(&tok, tok);
+  tok = skip(tok, "]");
+  ty = type_suffix(rest, tok, ty);
+
+  if (ty->kind == TY_VLA || !is_const_expr(expr))
+    return vla_of(ty, expr);
+  return array_of(ty, eval(expr));
+}
+
+// type-suffix = "(" func-params
+//             | "[" array-dimensions
+//             | ε
+static Type *type_suffix(Token **rest, Token *tok, Type *ty) {
+  if (equal(tok, "("))
+    return func_params(rest, tok->next, ty);
+
+  if (equal(tok, "["))
+    return array_dimensions(rest, tok->next, ty);
+
+  *rest = tok;
+  return ty;
+}
+
+// pointers = ("*" ("const" | "volatile" | "restrict")*)*
+static Type *pointers(Token **rest, Token *tok, Type *ty) {
+  while (consume(&tok, tok, "*")) {
+    ty = pointer_to(ty);
+    while (equal(tok, "const") || equal(tok, "volatile") || equal(tok, "restrict") ||
+           equal(tok, "__restrict") || equal(tok, "__restrict__"))
+      tok = tok->next;
+  }
+  *rest = tok;
+  return ty;
+}
+
+// declarator = pointers ("(" ident ")" | "(" declarator ")" | ident) type-suffix
+static Type *declarator(Token **rest, Token *tok, Type *ty) {
+  ty = pointers(&tok, tok, ty);
+
+  if (equal(tok, "(")) {
+    Token *start = tok;
+    Type dummy = {};
+    declarator(&tok, start->next, &dummy);
+    tok = skip(tok, ")");
+    ty = type_suffix(rest, tok, ty);
+    return declarator(&tok, start->next, ty);
+  }
+
+  Token *name = NULL;
+  Token *name_pos = tok;
+
+  if (tok->kind == TK_IDENT) {
+    name = tok;
+    tok = tok->next;
+  }
+
+  ty = type_suffix(rest, tok, ty);
+  ty->name = name;
+  ty->name_pos = name_pos;
+  return ty;
+}
+
+// abstract-declarator = pointers ("(" abstract-declarator ")")? type-suffix
+static Type *abstract_declarator(Token **rest, Token *tok, Type *ty) {
+  ty = pointers(&tok, tok, ty);
+
+  if (equal(tok, "(")) {
+    Token *start = tok;
+    Type dummy = {};
+    abstract_declarator(&tok, start->next, &dummy);
+    tok = skip(tok, ")");
+    ty = type_suffix(rest, tok, ty);
+    return abstract_declarator(&tok, start->next, ty);
+  }
+
+  return type_suffix(rest, tok, ty);
+}
+
+// type-name = declspec abstract-declarator
+static Type *typename(Token **rest, Token *tok) {
+  Type *ty = declspec(&tok, tok, NULL);
+  return abstract_declarator(rest, tok, ty);
+}
+
+static bool is_end(Token *tok) {
+  return equal(tok, "}") || (equal(tok, ",") && equal(tok->next, "}"));
+}
+
+static bool consume_end(Token **rest, Token *tok) {
+  if (equal(tok, "}")) {
+    *rest = tok->next;
+    return true;
+  }
+
+  if (equal(tok, ",") && equal(tok->next, "}")) {
+    *rest = tok->next->next;
+    return true;
+  }
+
+  return false;
+}
+
+// enum-specifier = ident? "{" enum-list? "}"
+//                | ident ("{" enum-list? "}")?
+//
+// enum-list      = ident ("=" num)? ("," ident ("=" num)?)* ","?
+static Type *enum_specifier(Token **rest, Token *tok) {
+  Type *ty = enum_type();
+
+  // Read a struct tag.
+  Token *tag = NULL;
+  if (tok->kind == TK_IDENT) {
+    tag = tok;
+    tok = tok->next;
+  }
+
+  if (tag && !equal(tok, "{")) {
+    Type *ty = find_tag(tag);
+    if (!ty)
+      error_tok(tag, "unknown enum type");
+    if (ty->kind != TY_ENUM)
+      error_tok(tag, "not an enum tag");
+    *rest = tok;
+    return ty;
+  }
+
+  tok = skip(tok, "{");
+
+  // Read an enum-list.
+  int i = 0;
+  int val = 0;
+  while (!consume_end(rest, tok)) {
+    if (i++ > 0)
+      tok = skip(tok, ",");
+
+    char *name = get_ident(tok);
+    tok = tok->next;
+
+    if (equal(tok, "="))
+      val = const_expr(&tok, tok->next);
+
+    VarScope *sc = push_scope(name);
+    sc->enum_ty = ty;
+    sc->enum_val = val++;
+  }
+
+  if (tag)
+    push_tag_scope(tag, ty);
+  return ty;
+}
+
+// typeof-specifier = "(" (expr | typename) ")"
+static Type *typeof_specifier(Token **rest, Token *tok) {
+  tok = skip(tok, "(");
+
+  Type *ty;
+  if (is_typename(tok)) {
+    ty = typename(&tok, tok);
+  } else {
+    Node *node = expr(&tok, tok);
+    add_type(node);
+    ty = node->ty;
+  }
+  *rest = skip(tok, ")");
+  return ty;
+}
+
+// Generate code for computing a VLA size.
+static Node *compute_vla_size(Type *ty, Token *tok) {
+  Node *node = new_node(ND_NULL_EXPR, tok);
+  if (ty->base)
+    node = new_binary(ND_COMMA, node, compute_vla_size(ty->base, tok), tok);
+
+  if (ty->kind != TY_VLA)
+    return node;
+
+  Node *base_sz;
+  if (ty->base->kind == TY_VLA)
+    base_sz = new_var_node(ty->base->vla_size, tok);
+  else
+    base_sz = new_num(ty->base->size, tok);
+
+  ty->vla_size = new_lvar("", ty_ulong);
+  Node *expr = new_binary(ND_ASSIGN, new_var_node(ty->vla_size, tok),
+                          new_binary(ND_MUL, ty->vla_len, base_sz, tok),
+                          tok);
+  return new_binary(ND_COMMA, node, expr, tok);
+}
+
+static Node *new_alloca(Node *sz) {
+  Node *node = new_unary(ND_FUNCALL, new_var_node(builtin_alloca, sz->tok), sz->tok);
+  node->func_ty = builtin_alloca->ty;
+  node->ty = builtin_alloca->ty->return_ty;
+  node->args = sz;
+  add_type(sz);
+  return node;
+}
+
+// declaration = declspec (declarator ("=" expr)? ("," declarator ("=" expr)?)*)? ";"
+static Node *declaration(Token **rest, Token *tok, Type *basety, VarAttr *attr) {
+  Node head = {};
+  Node *cur = &head;
+  int i = 0;
+
+  while (!equal(tok, ";")) {
+    if (i++ > 0)
+      tok = skip(tok, ",");
+
+    Type *ty = declarator(&tok, tok, basety);
+    if (ty->kind == TY_VOID)
+      error_tok(tok, "variable declared void");
+    if (!ty->name)
+      error_tok(ty->name_pos, "variable name omitted");
+
+    if (attr && attr->is_static) {
+      // static local variable
+      Obj *var = new_anon_gvar(ty);
+      push_scope(get_ident(ty->name))->var = var;
+      if (equal(tok, "="))
+        gvar_initializer(&tok, tok->next, var);
+      continue;
+    }
+
+    // Generate code for computing a VLA size. We need to do this
+    // even if ty is not VLA because ty may be a pointer to VLA
+    // (e.g. int (*foo)[n][m] where n and m are variables.)
+    cur = cur->next = new_unary(ND_EXPR_STMT, compute_vla_size(ty, tok), tok);
+
+    if (ty->kind == TY_VLA) {
+      if (equal(tok, "="))
+        error_tok(tok, "variable-sized object may not be initialized");
+
+      // Variable length arrays (VLAs) are translated to alloca() calls.
+      // For example, `int x[n+2]` is translated to `tmp = n + 2,
+      // x = alloca(tmp)`.
+      Obj *var = new_lvar(get_ident(ty->name), ty);
+      Token *tok = ty->name;
+      Node *expr = new_binary(ND_ASSIGN, new_vla_ptr(var, tok),
+                              new_alloca(new_var_node(ty->vla_size, tok)),
+                              tok);
+
+      cur = cur->next = new_unary(ND_EXPR_STMT, expr, tok);
+      continue;
+    }
+
+    Obj *var = new_lvar(get_ident(ty->name), ty);
+    if (attr && attr->align)
+      var->align = attr->align;
+
+    if (equal(tok, "=")) {
+      Node *expr = lvar_initializer(&tok, tok->next, var);
+      cur = cur->next = new_unary(ND_EXPR_STMT, expr, tok);
+    }
+
+    if (var->ty->size < 0)
+      error_tok(ty->name, "variable has incomplete type");
+    if (var->ty->kind == TY_VOID)
+      error_tok(ty->name, "variable declared void");
+  }
+
+  Node *node = new_node(ND_BLOCK, tok);
+  node->body = head.next;
+  *rest = tok->next;
+  return node;
+}
+
+static Token *skip_excess_element(Token *tok) {
+  if (equal(tok, "{")) {
+    tok = skip_excess_element(tok->next);
+    return skip(tok, "}");
+  }
+
+  assign(&tok, tok);
+  return tok;
+}
+
+// string-initializer = string-literal
+static void string_initializer(Token **rest, Token *tok, Initializer *init) {
+  if (init->is_flexible)
+    *init = *new_initializer(array_of(init->ty->base, tok->ty->array_len), false);
+
+  int len = MIN(init->ty->array_len, tok->ty->array_len);
+
+  switch (init->ty->base->size) {
+  case 1: {
+    char *str = tok->str;
+    for (int i = 0; i < len; i++)
+      init->children[i]->expr = new_num(str[i], tok);
+    break;
+  }
+  case 2: {
+    uint16_t *str = (uint16_t *)tok->str;
+    for (int i = 0; i < len; i++)
+      init->children[i]->expr = new_num(str[i], tok);
+    break;
+  }
+  case 4: {
+    uint32_t *str = (uint32_t *)tok->str;
+    for (int i = 0; i < len; i++)
+      init->children[i]->expr = new_num(str[i], tok);
+    break;
+  }
+  default:
+    unreachable();
+  }
+
+  *rest = tok->next;
+}
+
+// array-designator = "[" const-expr "]"
+//
+// C99 added the designated initializer to the language, which allows
+// programmers to move the "cursor" of an initializer to any element.
+// The syntax looks like this:
+//
+//   int x[10] = { 1, 2, [5]=3, 4, 5, 6, 7 };
+//
+// `[5]` moves the cursor to the 5th element, so the 5th element of x
+// is set to 3. Initialization then continues forward in order, so
+// 6th, 7th, 8th and 9th elements are initialized with 4, 5, 6 and 7,
+// respectively. Unspecified elements (in this case, 3rd and 4th
+// elements) are initialized with zero.
+//
+// Nesting is allowed, so the following initializer is valid:
+//
+//   int x[5][10] = { [5][8]=1, 2, 3 };
+//
+// It sets x[5][8], x[5][9] and x[6][0] to 1, 2 and 3, respectively.
+//
+// Use `.fieldname` to move the cursor for a struct initializer. E.g.
+//
+//   struct { int a, b, c; } x = { .c=5 };
+//
+// The above initializer sets x.c to 5.
+static void array_designator(Token **rest, Token *tok, Type *ty, int *begin, int *end) {
+  *begin = const_expr(&tok, tok->next);
+  if (*begin >= ty->array_len)
+    error_tok(tok, "array designator index exceeds array bounds");
+
+  if (equal(tok, "...")) {
+    *end = const_expr(&tok, tok->next);
+    if (*end >= ty->array_len)
+      error_tok(tok, "array designator index exceeds array bounds");
+    if (*end < *begin)
+      error_tok(tok, "array designator range [%d, %d] is empty", *begin, *end);
+  } else {
+    *end = *begin;
+  }
+
+  *rest = skip(tok, "]");
+}
+
+// struct-designator = "." ident
+static Member *struct_designator(Token **rest, Token *tok, Type *ty) {
+  Token *start = tok;
+  tok = skip(tok, ".");
+  if (tok->kind != TK_IDENT)
+    error_tok(tok, "expected a field designator");
+
+  for (Member *mem = ty->members; mem; mem = mem->next) {
+    // Anonymous struct member
+    if (mem->ty->kind == TY_STRUCT && !mem->name) {
+      if (get_struct_member(mem->ty, tok)) {
+        *rest = start;
+        return mem;
+      }
+      continue;
+    }
+
+    // Regular struct member
+    if (mem->name->len == tok->len && !strncmp(mem->name->loc, tok->loc, tok->len)) {
+      *rest = tok->next;
+      return mem;
+    }
+  }
+
+  error_tok(tok, "struct has no such member");
+}
+
+// designation = ("[" const-expr "]" | "." ident)* "="? initializer
+static void designation(Token **rest, Token *tok, Initializer *init) {
+  if (equal(tok, "[")) {
+    if (init->ty->kind != TY_ARRAY)
+      error_tok(tok, "array index in non-array initializer");
+
+    int begin, end;
+    array_designator(&tok, tok, init->ty, &begin, &end);
+
+    Token *tok2;
+    for (int i = begin; i <= end; i++)
+      designation(&tok2, tok, init->children[i]);
+    array_initializer2(rest, tok2, init, begin + 1);
+    return;
+  }
+
+  if (equal(tok, ".") && init->ty->kind == TY_STRUCT) {
+    Member *mem = struct_designator(&tok, tok, init->ty);
+    designation(&tok, tok, init->children[mem->idx]);
+    init->expr = NULL;
+    struct_initializer2(rest, tok, init, mem->next);
+    return;
+  }
+
+  if (equal(tok, ".") && init->ty->kind == TY_UNION) {
+    Member *mem = struct_designator(&tok, tok, init->ty);
+    init->mem = mem;
+    designation(rest, tok, init->children[mem->idx]);
+    return;
+  }
+
+  if (equal(tok, "."))
+    error_tok(tok, "field name not in struct or union initializer");
+
+  if (equal(tok, "="))
+    tok = tok->next;
+  initializer2(rest, tok, init);
+}
+
+// An array length can be omitted if an array has an initializer
+// (e.g. `int x[] = {1,2,3}`). If it's omitted, count the number
+// of initializer elements.
+static int count_array_init_elements(Token *tok, Type *ty) {
+  bool first = true;
+  Initializer *dummy = new_initializer(ty->base, true);
+
+  int i = 0, max = 0;
+
+  while (!consume_end(&tok, tok)) {
+    if (!first)
+      tok = skip(tok, ",");
+    first = false;
+
+    if (equal(tok, "[")) {
+      i = const_expr(&tok, tok->next);
+      if (equal(tok, "..."))
+        i = const_expr(&tok, tok->next);
+      tok = skip(tok, "]");
+      designation(&tok, tok, dummy);
+    } else {
+      initializer2(&tok, tok, dummy);
+    }
+
+    i++;
+    max = MAX(max, i);
+  }
+  return max;
+}
+
+// array-initializer1 = "{" initializer ("," initializer)* ","? "}"
+static void array_initializer1(Token **rest, Token *tok, Initializer *init) {
+  tok = skip(tok, "{");
+
+  if (init->is_flexible) {
+    int len = count_array_init_elements(tok, init->ty);
+    *init = *new_initializer(array_of(init->ty->base, len), false);
+  }
+
+  bool first = true;
+
+  if (init->is_flexible) {
+    int len = count_array_init_elements(tok, init->ty);
+    *init = *new_initializer(array_of(init->ty->base, len), false);
+  }
+
+  for (int i = 0; !consume_end(rest, tok); i++) {
+    if (!first)
+      tok = skip(tok, ",");
+    first = false;
+
+    if (equal(tok, "[")) {
+      int begin, end;
+      array_designator(&tok, tok, init->ty, &begin, &end);
+
+      Token *tok2;
+      for (int j = begin; j <= end; j++)
+        designation(&tok2, tok, init->children[j]);
+      tok = tok2;
+      i = end;
+      continue;
+    }
+
+    if (i < init->ty->array_len)
+      initializer2(&tok, tok, init->children[i]);
+    else
+      tok = skip_excess_element(tok);
+  }
+}
+
+// array-initializer2 = initializer ("," initializer)*
+static void array_initializer2(Token **rest, Token *tok, Initializer *init, int i) {
+  if (init->is_flexible) {
+    int len = count_array_init_elements(tok, init->ty);
+    *init = *new_initializer(array_of(init->ty->base, len), false);
+  }
+
+  for (; i < init->ty->array_len && !is_end(tok); i++) {
+    Token *start = tok;
+    if (i > 0)
+      tok = skip(tok, ",");
+
+    if (equal(tok, "[") || equal(tok, ".")) {
+      *rest = start;
+      return;
+    }
+
+    initializer2(&tok, tok, init->children[i]);
+  }
+  *rest = tok;
+}
+
+// struct-initializer1 = "{" initializer ("," initializer)* ","? "}"
+static void struct_initializer1(Token **rest, Token *tok, Initializer *init) {
+  tok = skip(tok, "{");
+
+  Member *mem = init->ty->members;
+  bool first = true;
+
+  while (!consume_end(rest, tok)) {
+    if (!first)
+      tok = skip(tok, ",");
+    first = false;
+
+    if (equal(tok, ".")) {
+      mem = struct_designator(&tok, tok, init->ty);
+      designation(&tok, tok, init->children[mem->idx]);
+      mem = mem->next;
+      continue;
+    }
+
+    if (mem) {
+      initializer2(&tok, tok, init->children[mem->idx]);
+      mem = mem->next;
+    } else {
+      tok = skip_excess_element(tok);
+    }
+  }
+}
+
+// struct-initializer2 = initializer ("," initializer)*
+static void struct_initializer2(Token **rest, Token *tok, Initializer *init, Member *mem) {
+  bool first = true;
+
+  for (; mem && !is_end(tok); mem = mem->next) {
+    Token *start = tok;
+
+    if (!first)
+      tok = skip(tok, ",");
+    first = false;
+
+    if (equal(tok, "[") || equal(tok, ".")) {
+      *rest = start;
+      return;
+    }
+
+    initializer2(&tok, tok, init->children[mem->idx]);
+  }
+  *rest = tok;
+}
+
+static void union_initializer(Token **rest, Token *tok, Initializer *init) {
+  // Unlike structs, union initializers take only one initializer,
+  // and that initializes the first union member by default.
+  // You can initialize other member using a designated initializer.
+  if (equal(tok, "{") && equal(tok->next, ".")) {
+    Member *mem = struct_designator(&tok, tok->next, init->ty);
+    init->mem = mem;
+    designation(&tok, tok, init->children[mem->idx]);
+    *rest = skip(tok, "}");
+    return;
+  }
+
+  init->mem = init->ty->members;
+
+  if (equal(tok, "{")) {
+    initializer2(&tok, tok->next, init->children[0]);
+    consume(&tok, tok, ",");
+    *rest = skip(tok, "}");
+  } else {
+    initializer2(rest, tok, init->children[0]);
+  }
+}
+
+// initializer = string-initializer | array-initializer
+//             | struct-initializer | union-initializer
+//             | assign
+static void initializer2(Token **rest, Token *tok, Initializer *init) {
+  if (init->ty->kind == TY_ARRAY && tok->kind == TK_STR) {
+    string_initializer(rest, tok, init);
+    return;
+  }
+
+  if (init->ty->kind == TY_ARRAY) {
+    if (equal(tok, "{"))
+      array_initializer1(rest, tok, init);
+    else
+      array_initializer2(rest, tok, init, 0);
+    return;
+  }
+
+  if (init->ty->kind == TY_STRUCT) {
+    if (equal(tok, "{")) {
+      struct_initializer1(rest, tok, init);
+      return;
+    }
+
+    // A struct can be initialized with another struct. E.g.
+    // `struct T x = y;` where y is a variable of type `struct T`.
+    // Handle that case first.
+    Node *expr = assign(rest, tok);
+    add_type(expr);
+    if (expr->ty->kind == TY_STRUCT) {
+      init->expr = expr;
+      return;
+    }
+
+    struct_initializer2(rest, tok, init, init->ty->members);
+    return;
+  }
+
+  if (init->ty->kind == TY_UNION) {
+    union_initializer(rest, tok, init);
+    return;
+  }
+
+  if (equal(tok, "{")) {
+    // An initializer for a scalar variable can be surrounded by
+    // braces. E.g. `int x = {3};`. Handle that case.
+    initializer2(&tok, tok->next, init);
+    *rest = skip(tok, "}");
+    return;
+  }
+
+  init->expr = assign(rest, tok);
+}
+
+static Type *copy_struct_type(Type *ty) {
+  ty = copy_type(ty);
+
+  Member head = {};
+  Member *cur = &head;
+  for (Member *mem = ty->members; mem; mem = mem->next) {
+    Member *m = calloc(1, sizeof(Member));
+    *m = *mem;
+    cur = cur->next = m;
+  }
+
+  ty->members = head.next;
+  return ty;
+}
+
+static Initializer *initializer(Token **rest, Token *tok, Type *ty, Type **new_ty) {
+  Initializer *init = new_initializer(ty, true);
+  initializer2(rest, tok, init);
+
+  if ((ty->kind == TY_STRUCT || ty->kind == TY_UNION) && ty->is_flexible) {
+    ty = copy_struct_type(ty);
+
+    Member *mem = ty->members;
+    while (mem->next)
+      mem = mem->next;
+    mem->ty = init->children[mem->idx]->ty;
+    ty->size += mem->ty->size;
+
+    *new_ty = ty;
+    return init;
+  }
+
+  *new_ty = init->ty;
+  return init;
+}
+
+static Node *init_desg_expr(InitDesg *desg, Token *tok) {
+  if (desg->var)
+    return new_var_node(desg->var, tok);
+
+  if (desg->member) {
+    Node *node = new_unary(ND_MEMBER, init_desg_expr(desg->next, tok), tok);
+    node->member = desg->member;
+    return node;
+  }
+
+  Node *lhs = init_desg_expr(desg->next, tok);
+  Node *rhs = new_num(desg->idx, tok);
+  return new_unary(ND_DEREF, new_add(lhs, rhs, tok), tok);
+}
+
+static Node *create_lvar_init(Initializer *init, Type *ty, InitDesg *desg, Token *tok) {
+  if (ty->kind == TY_ARRAY) {
+    Node *node = new_node(ND_NULL_EXPR, tok);
+    for (int i = 0; i < ty->array_len; i++) {
+      InitDesg desg2 = {desg, i};
+      Node *rhs = create_lvar_init(init->children[i], ty->base, &desg2, tok);
+      node = new_binary(ND_COMMA, node, rhs, tok);
+    }
+    return node;
+  }
+
+  if (ty->kind == TY_STRUCT && !init->expr) {
+    Node *node = new_node(ND_NULL_EXPR, tok);
+
+    for (Member *mem = ty->members; mem; mem = mem->next) {
+      InitDesg desg2 = {desg, 0, mem};
+      Node *rhs = create_lvar_init(init->children[mem->idx], mem->ty, &desg2, tok);
+      node = new_binary(ND_COMMA, node, rhs, tok);
+    }
+    return node;
+  }
+
+  if (ty->kind == TY_UNION) {
+    Member *mem = init->mem ? init->mem : ty->members;
+    InitDesg desg2 = {desg, 0, mem};
+    return create_lvar_init(init->children[mem->idx], mem->ty, &desg2, tok);
+  }
+
+  if (!init->expr)
+    return new_node(ND_NULL_EXPR, tok);
+
+  Node *lhs = init_desg_expr(desg, tok);
+  return new_binary(ND_ASSIGN, lhs, init->expr, tok);
+}
+
+// A variable definition with an initializer is a shorthand notation
+// for a variable definition followed by assignments. This function
+// generates assignment expressions for an initializer. For example,
+// `int x[2][2] = {{6, 7}, {8, 9}}` is converted to the following
+// expressions:
+//
+//   x[0][0] = 6;
+//   x[0][1] = 7;
+//   x[1][0] = 8;
+//   x[1][1] = 9;
+static Node *lvar_initializer(Token **rest, Token *tok, Obj *var) {
+  Initializer *init = initializer(rest, tok, var->ty, &var->ty);
+  InitDesg desg = {NULL, 0, NULL, var};
+
+  // If a partial initializer list is given, the standard requires
+  // that unspecified elements are set to 0. Here, we simply
+  // zero-initialize the entire memory region of a variable before
+  // initializing it with user-supplied values.
+  Node *lhs = new_node(ND_MEMZERO, tok);
+  lhs->var = var;
+
+  Node *rhs = create_lvar_init(init, var->ty, &desg, tok);
+  return new_binary(ND_COMMA, lhs, rhs, tok);
+}
+
+static uint64_t read_buf(char *buf, int sz) {
+  if (sz == 1)
+    return *buf;
+  if (sz == 2)
+    return *(uint16_t *)buf;
+  if (sz == 4)
+    return *(uint32_t *)buf;
+  if (sz == 8)
+    return *(uint64_t *)buf;
+  unreachable();
+}
+
+static void write_buf(char *buf, uint64_t val, int sz) {
+  if (sz == 1)
+    *buf = val;
+  else if (sz == 2)
+    *(uint16_t *)buf = val;
+  else if (sz == 4)
+    *(uint32_t *)buf = val;
+  else if (sz == 8)
+    *(uint64_t *)buf = val;
+  else
+    unreachable();
+}
+
+static Relocation *
+write_gvar_data(Relocation *cur, Initializer *init, Type *ty, char *buf, int offset) {
+  if (ty->kind == TY_ARRAY) {
+    int sz = ty->base->size;
+    for (int i = 0; i < ty->array_len; i++)
+      cur = write_gvar_data(cur, init->children[i], ty->base, buf, offset + sz * i);
+    return cur;
+  }
+
+  if (ty->kind == TY_STRUCT) {
+    for (Member *mem = ty->members; mem; mem = mem->next) {
+      if (mem->is_bitfield) {
+        Node *expr = init->children[mem->idx]->expr;
+        if (!expr)
+          break;
+
+        char *loc = buf + offset + mem->offset;
+        uint64_t oldval = read_buf(loc, mem->ty->size);
+        uint64_t newval = eval(expr);
+        uint64_t mask = (1L << mem->bit_width) - 1;
+        uint64_t combined = oldval | ((newval & mask) << mem->bit_offset);
+        write_buf(loc, combined, mem->ty->size);
+      } else {
+        cur = write_gvar_data(cur, init->children[mem->idx], mem->ty, buf,
+                              offset + mem->offset);
+      }
+    }
+    return cur;
+  }
+
+  if (ty->kind == TY_UNION) {
+    if (!init->mem)
+      return cur;
+    return write_gvar_data(cur, init->children[init->mem->idx],
+                           init->mem->ty, buf, offset);
+  }
+
+  if (!init->expr)
+    return cur;
+
+  if (ty->kind == TY_FLOAT) {
+    *(float *)(buf + offset) = eval_double(init->expr);
+    return cur;
+  }
+
+  if (ty->kind == TY_DOUBLE) {
+    *(double *)(buf + offset) = eval_double(init->expr);
+    return cur;
+  }
+
+  char **label = NULL;
+  uint64_t val = eval2(init->expr, &label);
+
+  if (!label) {
+    write_buf(buf + offset, val, ty->size);
+    return cur;
+  }
+
+  Relocation *rel = calloc(1, sizeof(Relocation));
+  rel->offset = offset;
+  rel->label = label;
+  rel->addend = val;
+  cur->next = rel;
+  return cur->next;
+}
+
+// Initializers for global variables are evaluated at compile-time and
+// embedded to .data section. This function serializes Initializer
+// objects to a flat byte array. It is a compile error if an
+// initializer list contains a non-constant expression.
+static void gvar_initializer(Token **rest, Token *tok, Obj *var) {
+  Initializer *init = initializer(rest, tok, var->ty, &var->ty);
+
+  Relocation head = {};
+  char *buf = calloc(1, var->ty->size);
+  write_gvar_data(&head, init, var->ty, buf, 0);
+  var->init_data = buf;
+  var->rel = head.next;
+}
+
+// Returns true if a given token represents a type.
+static bool is_typename(Token *tok) {
+  static HashMap map;
+
+  if (map.capacity == 0) {
+    static char *kw[] = {
+      "void", "_Bool", "char", "short", "int", "long", "struct", "union",
+      "typedef", "enum", "static", "extern", "_Alignas", "signed", "unsigned",
+      "const", "volatile", "auto", "register", "restrict", "__restrict",
+      "__restrict__", "_Noreturn", "float", "double", "typeof", "inline",
+      "_Thread_local", "__thread", "_Atomic",
+    };
+
+    for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++)
+      hashmap_put(&map, kw[i], (void *)1);
+  }
+
+  return hashmap_get2(&map, tok->loc, tok->len) || 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
+//      | "case" const-expr ("..." const-expr)? ":" stmt
+//      | "default" ":" stmt
+//      | "for" "(" expr-stmt expr? ";" expr? ")" stmt
+//      | "while" "(" expr ")" stmt
+//      | "do" stmt "while" "(" expr ")" ";"
+//      | "asm" asm-stmt
+//      | "goto" (ident | "*" expr) ";"
+//      | "break" ";"
+//      | "continue" ";"
+//      | ident ":" stmt
+//      | "{" compound-stmt
+//      | expr-stmt
+static Node *stmt(Token **rest, Token *tok) {
+  if (equal(tok, "return")) {
+    Node *node = new_node(ND_RETURN, tok);
+    if (consume(rest, tok->next, ";"))
+      return node;
+
+    Node *exp = expr(&tok, tok->next);
+    *rest = skip(tok, ";");
+
+    add_type(exp);
+    Type *ty = current_fn->ty->return_ty;
+    if (ty->kind != TY_STRUCT && ty->kind != TY_UNION)
+      exp = new_cast(exp, current_fn->ty->return_ty);
+
+    node->lhs = exp;
+    return node;
+  }
+
+  if (equal(tok, "if")) {
+    Node *node = new_node(ND_IF, tok);
+    tok = skip(tok->next, "(");
+    node->cond = expr(&tok, tok);
+    tok = skip(tok, ")");
+    node->then = stmt(&tok, tok);
+    if (equal(tok, "else"))
+      node->els = stmt(&tok, tok->next);
+    *rest = tok;
+    return node;
+  }
+
+  if (equal(tok, "switch")) {
+    Node *node = new_node(ND_SWITCH, tok);
+    tok = skip(tok->next, "(");
+    node->cond = expr(&tok, tok);
+    tok = skip(tok, ")");
+
+    Node *sw = current_switch;
+    current_switch = node;
+
+    char *brk = brk_label;
+    brk_label = node->brk_label = new_unique_name();
+
+    node->then = stmt(rest, tok);
+
+    current_switch = sw;
+    brk_label = brk;
+    return node;
+  }
+
+  if (equal(tok, "case")) {
+    if (!current_switch)
+      error_tok(tok, "stray case");
+
+    Node *node = new_node(ND_CASE, tok);
+    int begin = const_expr(&tok, tok->next);
+    int end;
+
+    if (equal(tok, "...")) {
+      // [GNU] Case ranges, e.g. "case 1 ... 5:"
+      end = const_expr(&tok, tok->next);
+      if (end < begin)
+        error_tok(tok, "empty case range specified");
+    } else {
+      end = begin;
+    }
+
+    tok = skip(tok, ":");
+    node->label = new_unique_name();
+    node->lhs = stmt(rest, tok);
+    node->begin = begin;
+    node->end = end;
+    node->case_next = current_switch->case_next;
+    current_switch->case_next = node;
+    return node;
+  }
+
+  if (equal(tok, "default")) {
+    if (!current_switch)
+      error_tok(tok, "stray default");
+
+    Node *node = new_node(ND_CASE, tok);
+    tok = skip(tok->next, ":");
+    node->label = new_unique_name();
+    node->lhs = stmt(rest, tok);
+    current_switch->default_case = node;
+    return node;
+  }
+
+  if (equal(tok, "for")) {
+    Node *node = new_node(ND_FOR, tok);
+    tok = skip(tok->next, "(");
+
+    enter_scope();
+
+    char *brk = brk_label;
+    char *cont = cont_label;
+    brk_label = node->brk_label = new_unique_name();
+    cont_label = node->cont_label = new_unique_name();
+
+    if (is_typename(tok)) {
+      Type *basety = declspec(&tok, tok, NULL);
+      node->init = declaration(&tok, tok, basety, NULL);
+    } else {
+      node->init = expr_stmt(&tok, tok);
+    }
+
+    if (!equal(tok, ";"))
+      node->cond = expr(&tok, tok);
+    tok = skip(tok, ";");
+
+    if (!equal(tok, ")"))
+      node->inc = expr(&tok, tok);
+    tok = skip(tok, ")");
+
+    node->then = stmt(rest, tok);
+
+    leave_scope();
+    brk_label = brk;
+    cont_label = cont;
+    return node;
+  }
+
+  if (equal(tok, "while")) {
+    Node *node = new_node(ND_FOR, tok);
+    tok = skip(tok->next, "(");
+    node->cond = expr(&tok, tok);
+    tok = skip(tok, ")");
+
+    char *brk = brk_label;
+    char *cont = cont_label;
+    brk_label = node->brk_label = new_unique_name();
+    cont_label = node->cont_label = new_unique_name();
+
+    node->then = stmt(rest, tok);
+
+    brk_label = brk;
+    cont_label = cont;
+    return node;
+  }
+
+  if (equal(tok, "do")) {
+    Node *node = new_node(ND_DO, tok);
+
+    char *brk = brk_label;
+    char *cont = cont_label;
+    brk_label = node->brk_label = new_unique_name();
+    cont_label = node->cont_label = new_unique_name();
+
+    node->then = stmt(&tok, tok->next);
+
+    brk_label = brk;
+    cont_label = cont;
+
+    tok = skip(tok, "while");
+    tok = skip(tok, "(");
+    node->cond = expr(&tok, tok);
+    tok = skip(tok, ")");
+    *rest = skip(tok, ";");
+    return node;
+  }
+
+  if (equal(tok, "asm"))
+    return asm_stmt(rest, tok);
+
+  if (equal(tok, "goto")) {
+    if (equal(tok->next, "*")) {
+      // [GNU] `goto *ptr` jumps to the address specified by `ptr`.
+      Node *node = new_node(ND_GOTO_EXPR, tok);
+      node->lhs = expr(&tok, tok->next->next);
+      *rest = skip(tok, ";");
+      return node;
+    }
+
+    Node *node = new_node(ND_GOTO, tok);
+    node->label = get_ident(tok->next);
+    node->goto_next = gotos;
+    gotos = node;
+    *rest = skip(tok->next->next, ";");
+    return node;
+  }
+
+  if (equal(tok, "break")) {
+    if (!brk_label)
+      error_tok(tok, "stray break");
+    Node *node = new_node(ND_GOTO, tok);
+    node->unique_label = brk_label;
+    *rest = skip(tok->next, ";");
+    return node;
+  }
+
+  if (equal(tok, "continue")) {
+    if (!cont_label)
+      error_tok(tok, "stray continue");
+    Node *node = new_node(ND_GOTO, tok);
+    node->unique_label = cont_label;
+    *rest = skip(tok->next, ";");
+    return node;
+  }
+
+  if (tok->kind == TK_IDENT && equal(tok->next, ":")) {
+    Node *node = new_node(ND_LABEL, tok);
+    node->label = strndup(tok->loc, tok->len);
+    node->unique_label = new_unique_name();
+    node->lhs = stmt(rest, tok->next->next);
+    node->goto_next = labels;
+    labels = node;
+    return node;
+  }
+
+  if (equal(tok, "{"))
+    return compound_stmt(rest, tok->next);
+
+  return expr_stmt(rest, tok);
+}
+
+// compound-stmt = (typedef | declaration | stmt)* "}"
+static Node *compound_stmt(Token **rest, Token *tok) {
+  Node *node = new_node(ND_BLOCK, tok);
+  Node head = {};
+  Node *cur = &head;
+
+  enter_scope();
+
+  while (!equal(tok, "}")) {
+    if (is_typename(tok) && !equal(tok->next, ":")) {
+      VarAttr attr = {};
+      Type *basety = declspec(&tok, tok, &attr);
+
+      if (attr.is_typedef) {
+        tok = parse_typedef(tok, basety);
+        continue;
+      }
+
+      if (is_function(tok)) {
+        tok = function(tok, basety, &attr);
+        continue;
+      }
+
+      if (attr.is_extern) {
+        tok = global_variable(tok, basety, &attr);
+        continue;
+      }
+
+      cur = cur->next = declaration(&tok, tok, basety, &attr);
+    } else {
+      cur = cur->next = stmt(&tok, tok);
+    }
+    add_type(cur);
+  }
+
+  leave_scope();
+
+  node->body = head.next;
+  *rest = tok->next;
+  return node;
+}
+
+// expr-stmt = expr? ";"
+static Node *expr_stmt(Token **rest, Token *tok) {
+  if (equal(tok, ";")) {
+    *rest = tok->next;
+    return new_node(ND_BLOCK, tok);
+  }
+
+  Node *node = new_node(ND_EXPR_STMT, tok);
+  node->lhs = expr(&tok, tok);
+  *rest = skip(tok, ";");
+  return node;
+}
+
+// expr = assign ("," expr)?
+static Node *expr(Token **rest, Token *tok) {
+  Node *node = assign(&tok, tok);
+
+  if (equal(tok, ","))
+    return new_binary(ND_COMMA, node, expr(rest, tok->next), tok);
+
+  *rest = tok;
+  return node;
+}
+
+static int64_t eval(Node *node) {
+  return eval2(node, NULL);
+}
+
+// Evaluate a given node as a constant expression.
+//
+// A constant expression is either just a number or ptr+n where ptr
+// is a pointer to a global variable and n is a postiive/negative
+// number. The latter form is accepted only as an initialization
+// expression for a global variable.
+static int64_t eval2(Node *node, char ***label) {
+  add_type(node);
+
+  if (is_flonum(node->ty))
+    return eval_double(node);
+
+  switch (node->kind) {
+  case ND_ADD:
+    return eval2(node->lhs, label) + eval(node->rhs);
+  case ND_SUB:
+    return eval2(node->lhs, label) - eval(node->rhs);
+  case ND_MUL:
+    return eval(node->lhs) * eval(node->rhs);
+  case ND_DIV:
+    if (node->ty->is_unsigned)
+      return (uint64_t)eval(node->lhs) / eval(node->rhs);
+    return eval(node->lhs) / eval(node->rhs);
+  case ND_NEG:
+    return -eval(node->lhs);
+  case ND_MOD:
+    if (node->ty->is_unsigned)
+      return (uint64_t)eval(node->lhs) % eval(node->rhs);
+    return eval(node->lhs) % eval(node->rhs);
+  case ND_BITAND:
+    return eval(node->lhs) & eval(node->rhs);
+  case ND_BITOR:
+    return eval(node->lhs) | eval(node->rhs);
+  case ND_BITXOR:
+    return eval(node->lhs) ^ eval(node->rhs);
+  case ND_SHL:
+    return eval(node->lhs) << eval(node->rhs);
+  case ND_SHR:
+    if (node->ty->is_unsigned && node->ty->size == 8)
+      return (uint64_t)eval(node->lhs) >> eval(node->rhs);
+    return eval(node->lhs) >> eval(node->rhs);
+  case ND_EQ:
+    return eval(node->lhs) == eval(node->rhs);
+  case ND_NE:
+    return eval(node->lhs) != eval(node->rhs);
+  case ND_LT:
+    if (node->lhs->ty->is_unsigned)
+      return (uint64_t)eval(node->lhs) < eval(node->rhs);
+    return eval(node->lhs) < eval(node->rhs);
+  case ND_LE:
+    if (node->lhs->ty->is_unsigned)
+      return (uint64_t)eval(node->lhs) <= eval(node->rhs);
+    return eval(node->lhs) <= eval(node->rhs);
+  case ND_COND:
+    return eval(node->cond) ? eval2(node->then, label) : eval2(node->els, label);
+  case ND_COMMA:
+    return eval2(node->rhs, label);
+  case ND_NOT:
+    return !eval(node->lhs);
+  case ND_BITNOT:
+    return ~eval(node->lhs);
+  case ND_LOGAND:
+    return eval(node->lhs) && eval(node->rhs);
+  case ND_LOGOR:
+    return eval(node->lhs) || eval(node->rhs);
+  case ND_CAST: {
+    int64_t val = eval2(node->lhs, label);
+    if (is_integer(node->ty)) {
+      switch (node->ty->size) {
+      case 1: return node->ty->is_unsigned ? (uint8_t)val : (int8_t)val;
+      case 2: return node->ty->is_unsigned ? (uint16_t)val : (int16_t)val;
+      case 4: return node->ty->is_unsigned ? (uint32_t)val : (int32_t)val;
+      }
+    }
+    return val;
+  }
+  case ND_ADDR:
+    return eval_rval(node->lhs, label);
+  case ND_LABEL_VAL:
+    *label = &node->unique_label;
+    return 0;
+  case ND_MEMBER:
+    if (!label)
+      error_tok(node->tok, "not a compile-time constant");
+    if (node->ty->kind != TY_ARRAY)
+      error_tok(node->tok, "invalid initializer");
+    return eval_rval(node->lhs, label) + node->member->offset;
+  case ND_VAR:
+    if (!label)
+      error_tok(node->tok, "not a compile-time constant");
+    if (node->var->ty->kind != TY_ARRAY && node->var->ty->kind != TY_FUNC)
+      error_tok(node->tok, "invalid initializer");
+    *label = &node->var->name;
+    return 0;
+  case ND_NUM:
+    return node->val;
+  }
+
+  error_tok(node->tok, "not a compile-time constant");
+}
+
+static int64_t eval_rval(Node *node, char ***label) {
+  switch (node->kind) {
+  case ND_VAR:
+    if (node->var->is_local)
+      error_tok(node->tok, "not a compile-time constant");
+    *label = &node->var->name;
+    return 0;
+  case ND_DEREF:
+    return eval2(node->lhs, label);
+  case ND_MEMBER:
+    return eval_rval(node->lhs, label) + node->member->offset;
+  }
+
+  error_tok(node->tok, "invalid initializer");
+}
+
+static bool is_const_expr(Node *node) {
+  add_type(node);
+
+  switch (node->kind) {
+  case ND_ADD:
+  case ND_SUB:
+  case ND_MUL:
+  case ND_DIV:
+  case ND_BITAND:
+  case ND_BITOR:
+  case ND_BITXOR:
+  case ND_SHL:
+  case ND_SHR:
+  case ND_EQ:
+  case ND_NE:
+  case ND_LT:
+  case ND_LE:
+  case ND_LOGAND:
+  case ND_LOGOR:
+    return is_const_expr(node->lhs) && is_const_expr(node->rhs);
+  case ND_COND:
+    if (!is_const_expr(node->cond))
+      return false;
+    return is_const_expr(eval(node->cond) ? node->then : node->els);
+  case ND_COMMA:
+    return is_const_expr(node->rhs);
+  case ND_NEG:
+  case ND_NOT:
+  case ND_BITNOT:
+  case ND_CAST:
+    return is_const_expr(node->lhs);
+  case ND_NUM:
+    return true;
+  }
+
+  return false;
+}
+
+int64_t const_expr(Token **rest, Token *tok) {
+  Node *node = conditional(rest, tok);
+  return eval(node);
+}
+
+static double eval_double(Node *node) {
+  add_type(node);
+
+  if (is_integer(node->ty)) {
+    if (node->ty->is_unsigned)
+      return (unsigned long)eval(node);
+    return eval(node);
+  }
+
+  switch (node->kind) {
+  case ND_ADD:
+    return eval_double(node->lhs) + eval_double(node->rhs);
+  case ND_SUB:
+    return eval_double(node->lhs) - eval_double(node->rhs);
+  case ND_MUL:
+    return eval_double(node->lhs) * eval_double(node->rhs);
+  case ND_DIV:
+    return eval_double(node->lhs) / eval_double(node->rhs);
+  case ND_NEG:
+    return -eval_double(node->lhs);
+  case ND_COND:
+    return eval_double(node->cond) ? eval_double(node->then) : eval_double(node->els);
+  case ND_COMMA:
+    return eval_double(node->rhs);
+  case ND_CAST:
+    if (is_flonum(node->lhs->ty))
+      return eval_double(node->lhs);
+    return eval(node->lhs);
+  case ND_NUM:
+    return node->fval;
+  }
+
+  error_tok(node->tok, "not a compile-time constant");
+}
+
+// Convert op= operators to expressions containing an assignment.
+//
+// In general, `A op= C` is converted to ``tmp = &A, *tmp = *tmp op B`.
+// However, if a given expression is of form `A.x op= C`, the input is
+// converted to `tmp = &A, (*tmp).x = (*tmp).x op C` to handle assignments
+// to bitfields.
+static Node *to_assign(Node *binary) {
+  add_type(binary->lhs);
+  add_type(binary->rhs);
+  Token *tok = binary->tok;
+
+  // Convert `A.x op= C` to `tmp = &A, (*tmp).x = (*tmp).x op C`.
+  if (binary->lhs->kind == ND_MEMBER) {
+    Obj *var = new_lvar("", pointer_to(binary->lhs->lhs->ty));
+
+    Node *expr1 = new_binary(ND_ASSIGN, new_var_node(var, tok),
+                             new_unary(ND_ADDR, binary->lhs->lhs, tok), tok);
+
+    Node *expr2 = new_unary(ND_MEMBER,
+                            new_unary(ND_DEREF, new_var_node(var, tok), tok),
+                            tok);
+    expr2->member = binary->lhs->member;
+
+    Node *expr3 = new_unary(ND_MEMBER,
+                            new_unary(ND_DEREF, new_var_node(var, tok), tok),
+                            tok);
+    expr3->member = binary->lhs->member;
+
+    Node *expr4 = new_binary(ND_ASSIGN, expr2,
+                             new_binary(binary->kind, expr3, binary->rhs, tok),
+                             tok);
+
+    return new_binary(ND_COMMA, expr1, expr4, tok);
+  }
+
+  // If A is an atomic type, Convert `A op= B` to
+  //
+  // ({
+  //   T1 *addr = &A; T2 val = (B); T1 old = *addr; T1 new;
+  //   do {
+  //    new = old op val;
+  //   } while (!atomic_compare_exchange_strong(addr, &old, new));
+  //   new;
+  // })
+  if (binary->lhs->ty->is_atomic) {
+    Node head = {};
+    Node *cur = &head;
+
+    Obj *addr = new_lvar("", pointer_to(binary->lhs->ty));
+    Obj *val = new_lvar("", binary->rhs->ty);
+    Obj *old = new_lvar("", binary->lhs->ty);
+    Obj *new = new_lvar("", binary->lhs->ty);
+
+    cur = cur->next =
+      new_unary(ND_EXPR_STMT,
+                new_binary(ND_ASSIGN, new_var_node(addr, tok),
+                           new_unary(ND_ADDR, binary->lhs, tok), tok),
+                tok);
+
+    cur = cur->next =
+      new_unary(ND_EXPR_STMT,
+                new_binary(ND_ASSIGN, new_var_node(val, tok), binary->rhs, tok),
+                tok);
+
+    cur = cur->next =
+      new_unary(ND_EXPR_STMT,
+                new_binary(ND_ASSIGN, new_var_node(old, tok),
+                           new_unary(ND_DEREF, new_var_node(addr, tok), tok), tok),
+                tok);
+
+    Node *loop = new_node(ND_DO, tok);
+    loop->brk_label = new_unique_name();
+    loop->cont_label = new_unique_name();
+
+    Node *body = new_binary(ND_ASSIGN,
+                            new_var_node(new, tok),
+                            new_binary(binary->kind, new_var_node(old, tok),
+                                       new_var_node(val, tok), tok),
+                            tok);
+
+    loop->then = new_node(ND_BLOCK, tok);
+    loop->then->body = new_unary(ND_EXPR_STMT, body, tok);
+
+    Node *cas = new_node(ND_CAS, tok);
+    cas->cas_addr = new_var_node(addr, tok);
+    cas->cas_old = new_unary(ND_ADDR, new_var_node(old, tok), tok);
+    cas->cas_new = new_var_node(new, tok);
+    loop->cond = new_unary(ND_NOT, cas, tok);
+
+    cur = cur->next = loop;
+    cur = cur->next = new_unary(ND_EXPR_STMT, new_var_node(new, tok), tok);
+
+    Node *node = new_node(ND_STMT_EXPR, tok);
+    node->body = head.next;
+    return node;
+  }
+
+  // Convert `A op= B` to ``tmp = &A, *tmp = *tmp op B`.
+  Obj *var = new_lvar("", pointer_to(binary->lhs->ty));
+
+  Node *expr1 = new_binary(ND_ASSIGN, new_var_node(var, tok),
+                           new_unary(ND_ADDR, binary->lhs, tok), tok);
+
+  Node *expr2 =
+    new_binary(ND_ASSIGN,
+               new_unary(ND_DEREF, new_var_node(var, tok), tok),
+               new_binary(binary->kind,
+                          new_unary(ND_DEREF, new_var_node(var, tok), tok),
+                          binary->rhs,
+                          tok),
+               tok);
+
+  return new_binary(ND_COMMA, expr1, expr2, tok);
+}
+
+// assign    = conditional (assign-op assign)?
+// assign-op = "=" | "+=" | "-=" | "*=" | "/=" | "%=" | "&=" | "|=" | "^="
+//           | "<<=" | ">>="
+static Node *assign(Token **rest, Token *tok) {
+  Node *node = conditional(&tok, tok);
+
+  if (equal(tok, "="))
+    return new_binary(ND_ASSIGN, node, assign(rest, tok->next), tok);
+
+  if (equal(tok, "+="))
+    return to_assign(new_add(node, assign(rest, tok->next), tok));
+
+  if (equal(tok, "-="))
+    return to_assign(new_sub(node, assign(rest, tok->next), tok));
+
+  if (equal(tok, "*="))
+    return to_assign(new_binary(ND_MUL, node, assign(rest, tok->next), tok));
+
+  if (equal(tok, "/="))
+    return to_assign(new_binary(ND_DIV, node, assign(rest, tok->next), tok));
+
+  if (equal(tok, "%="))
+    return to_assign(new_binary(ND_MOD, node, assign(rest, tok->next), tok));
+
+  if (equal(tok, "&="))
+    return to_assign(new_binary(ND_BITAND, node, assign(rest, tok->next), tok));
+
+  if (equal(tok, "|="))
+    return to_assign(new_binary(ND_BITOR, node, assign(rest, tok->next), tok));
+
+  if (equal(tok, "^="))
+    return to_assign(new_binary(ND_BITXOR, node, assign(rest, tok->next), tok));
+
+  if (equal(tok, "<<="))
+    return to_assign(new_binary(ND_SHL, node, assign(rest, tok->next), tok));
+
+  if (equal(tok, ">>="))
+    return to_assign(new_binary(ND_SHR, node, assign(rest, tok->next), tok));
+
+  *rest = tok;
+  return node;
+}
+
+// conditional = logor ("?" expr? ":" conditional)?
+static Node *conditional(Token **rest, Token *tok) {
+  Node *cond = logor(&tok, tok);
+
+  if (!equal(tok, "?")) {
+    *rest = tok;
+    return cond;
+  }
+
+  if (equal(tok->next, ":")) {
+    // [GNU] Compile `a ?: b` as `tmp = a, tmp ? tmp : b`.
+    add_type(cond);
+    Obj *var = new_lvar("", cond->ty);
+    Node *lhs = new_binary(ND_ASSIGN, new_var_node(var, tok), cond, tok);
+    Node *rhs = new_node(ND_COND, tok);
+    rhs->cond = new_var_node(var, tok);
+    rhs->then = new_var_node(var, tok);
+    rhs->els = conditional(rest, tok->next->next);
+    return new_binary(ND_COMMA, lhs, rhs, tok);
+  }
+
+  Node *node = new_node(ND_COND, tok);
+  node->cond = cond;
+  node->then = expr(&tok, tok->next);
+  tok = skip(tok, ":");
+  node->els = conditional(rest, tok);
+  return node;
+}
+
+// logor = logand ("||" logand)*
+static Node *logor(Token **rest, Token *tok) {
+  Node *node = logand(&tok, tok);
+  while (equal(tok, "||")) {
+    Token *start = tok;
+    node = new_binary(ND_LOGOR, node, logand(&tok, tok->next), start);
+  }
+  *rest = tok;
+  return node;
+}
+
+// logand = bitor ("&&" bitor)*
+static Node *logand(Token **rest, Token *tok) {
+  Node *node = bitor(&tok, tok);
+  while (equal(tok, "&&")) {
+    Token *start = tok;
+    node = new_binary(ND_LOGAND, node, bitor(&tok, tok->next), start);
+  }
+  *rest = tok;
+  return node;
+}
+
+// bitor = bitxor ("|" bitxor)*
+static Node *bitor(Token **rest, Token *tok) {
+  Node *node = bitxor(&tok, tok);
+  while (equal(tok, "|")) {
+    Token *start = tok;
+    node = new_binary(ND_BITOR, node, bitxor(&tok, tok->next), start);
+  }
+  *rest = tok;
+  return node;
+}
+
+// bitxor = bitand ("^" bitand)*
+static Node *bitxor(Token **rest, Token *tok) {
+  Node *node = bitand(&tok, tok);
+  while (equal(tok, "^")) {
+    Token *start = tok;
+    node = new_binary(ND_BITXOR, node, bitand(&tok, tok->next), start);
+  }
+  *rest = tok;
+  return node;
+}
+
+// bitand = equality ("&" equality)*
+static Node *bitand(Token **rest, Token *tok) {
+  Node *node = equality(&tok, tok);
+  while (equal(tok, "&")) {
+    Token *start = tok;
+    node = new_binary(ND_BITAND, node, equality(&tok, tok->next), start);
+  }
+  *rest = tok;
+  return node;
+}
+
+// equality = relational ("==" relational | "!=" relational)*
+static Node *equality(Token **rest, Token *tok) {
+  Node *node = relational(&tok, tok);
+
+  for (;;) {
+    Token *start = tok;
+
+    if (equal(tok, "==")) {
+      node = new_binary(ND_EQ, node, relational(&tok, tok->next), start);
+      continue;
+    }
+
+    if (equal(tok, "!=")) {
+      node = new_binary(ND_NE, node, relational(&tok, tok->next), start);
+      continue;
+    }
+
+    *rest = tok;
+    return node;
+  }
+}
+
+// relational = shift ("<" shift | "<=" shift | ">" shift | ">=" shift)*
+static Node *relational(Token **rest, Token *tok) {
+  Node *node = shift(&tok, tok);
+
+  for (;;) {
+    Token *start = tok;
+
+    if (equal(tok, "<")) {
+      node = new_binary(ND_LT, node, shift(&tok, tok->next), start);
+      continue;
+    }
+
+    if (equal(tok, "<=")) {
+      node = new_binary(ND_LE, node, shift(&tok, tok->next), start);
+      continue;
+    }
+
+    if (equal(tok, ">")) {
+      node = new_binary(ND_LT, shift(&tok, tok->next), node, start);
+      continue;
+    }
+
+    if (equal(tok, ">=")) {
+      node = new_binary(ND_LE, shift(&tok, tok->next), node, start);
+      continue;
+    }
+
+    *rest = tok;
+    return node;
+  }
+}
+
+// shift = add ("<<" add | ">>" add)*
+static Node *shift(Token **rest, Token *tok) {
+  Node *node = add(&tok, tok);
+
+  for (;;) {
+    Token *start = tok;
+
+    if (equal(tok, "<<")) {
+      node = new_binary(ND_SHL, node, add(&tok, tok->next), start);
+      continue;
+    }
+
+    if (equal(tok, ">>")) {
+      node = new_binary(ND_SHR, node, add(&tok, tok->next), start);
+      continue;
+    }
+
+    *rest = tok;
+    return node;
+  }
+}
+
+// In C, `+` operator is overloaded to perform the pointer arithmetic.
+// If p is a pointer, p+n adds not n but sizeof(*p)*n to the value of p,
+// so that p+n points to the location n elements (not bytes) ahead of p.
+// In other words, we need to scale an integer value before adding to a
+// pointer value. This function takes care of the scaling.
+static Node *new_add(Node *lhs, Node *rhs, Token *tok) {
+  add_type(lhs);
+  add_type(rhs);
+
+  // num + num
+  if (is_numeric(lhs->ty) && is_numeric(rhs->ty))
+    return new_binary(ND_ADD, lhs, rhs, tok);
+
+  if (lhs->ty->base && rhs->ty->base)
+    error_tok(tok, "invalid operands");
+
+  // Canonicalize `num + ptr` to `ptr + num`.
+  if (!lhs->ty->base && rhs->ty->base) {
+    Node *tmp = lhs;
+    lhs = rhs;
+    rhs = tmp;
+  }
+
+  // VLA + num
+  if (lhs->ty->base->kind == TY_VLA) {
+    rhs = new_binary(ND_MUL, rhs, new_var_node(lhs->ty->base->vla_size, tok), tok);
+    return new_binary(ND_ADD, lhs, rhs, tok);
+  }
+
+  // ptr + num
+  rhs = new_binary(ND_MUL, rhs, new_long(lhs->ty->base->size, tok), tok);
+  return new_binary(ND_ADD, lhs, rhs, tok);
+}
+
+// Like `+`, `-` is overloaded for the pointer type.
+static Node *new_sub(Node *lhs, Node *rhs, Token *tok) {
+  add_type(lhs);
+  add_type(rhs);
+
+  // num - num
+  if (is_numeric(lhs->ty) && is_numeric(rhs->ty))
+    return new_binary(ND_SUB, lhs, rhs, tok);
+
+  // VLA + num
+  if (lhs->ty->base->kind == TY_VLA) {
+    rhs = new_binary(ND_MUL, rhs, new_var_node(lhs->ty->base->vla_size, tok), tok);
+    add_type(rhs);
+    Node *node = new_binary(ND_SUB, lhs, rhs, tok);
+    node->ty = lhs->ty;
+    return node;
+  }
+
+  // ptr - num
+  if (lhs->ty->base && is_integer(rhs->ty)) {
+    rhs = new_binary(ND_MUL, rhs, new_long(lhs->ty->base->size, tok), tok);
+    add_type(rhs);
+    Node *node = new_binary(ND_SUB, lhs, rhs, tok);
+    node->ty = lhs->ty;
+    return node;
+  }
+
+  // ptr - ptr, which returns how many elements are between the two.
+  if (lhs->ty->base && rhs->ty->base) {
+    Node *node = new_binary(ND_SUB, lhs, rhs, tok);
+    node->ty = ty_long;
+    return new_binary(ND_DIV, node, new_num(lhs->ty->base->size, tok), tok);
+  }
+
+  error_tok(tok, "invalid operands");
+}
+
+// add = mul ("+" mul | "-" mul)*
+static Node *add(Token **rest, Token *tok) {
+  Node *node = mul(&tok, tok);
+
+  for (;;) {
+    Token *start = tok;
+
+    if (equal(tok, "+")) {
+      node = new_add(node, mul(&tok, tok->next), start);
+      continue;
+    }
+
+    if (equal(tok, "-")) {
+      node = new_sub(node, mul(&tok, tok->next), start);
+      continue;
+    }
+
+    *rest = tok;
+    return node;
+  }
+}
+
+// mul = cast ("*" cast | "/" cast | "%" cast)*
+static Node *mul(Token **rest, Token *tok) {
+  Node *node = cast(&tok, tok);
+
+  for (;;) {
+    Token *start = tok;
+
+    if (equal(tok, "*")) {
+      node = new_binary(ND_MUL, node, cast(&tok, tok->next), start);
+      continue;
+    }
+
+    if (equal(tok, "/")) {
+      node = new_binary(ND_DIV, node, cast(&tok, tok->next), start);
+      continue;
+    }
+
+    if (equal(tok, "%")) {
+      node = new_binary(ND_MOD, node, cast(&tok, tok->next), start);
+      continue;
+    }
+
+    *rest = tok;
+    return node;
+  }
+}
+
+// cast = "(" type-name ")" cast | unary
+static Node *cast(Token **rest, Token *tok) {
+  if (equal(tok, "(") && is_typename(tok->next)) {
+    Token *start = tok;
+    Type *ty = typename(&tok, tok->next);
+    tok = skip(tok, ")");
+
+    // compound literal
+    if (equal(tok, "{"))
+      return unary(rest, start);
+
+    // type cast
+    Node *node = new_cast(cast(rest, tok), ty);
+    node->tok = start;
+    return node;
+  }
+
+  return unary(rest, tok);
+}
+
+// unary = ("+" | "-" | "*" | "&" | "!" | "~") cast
+//       | ("++" | "--") unary
+//       | "&&" ident
+//       | postfix
+static Node *unary(Token **rest, Token *tok) {
+  if (equal(tok, "+"))
+    return cast(rest, tok->next);
+
+  if (equal(tok, "-"))
+    return new_unary(ND_NEG, cast(rest, tok->next), tok);
+
+  if (equal(tok, "&")) {
+    Node *lhs = cast(rest, tok->next);
+    add_type(lhs);
+    if (lhs->kind == ND_MEMBER && lhs->member->is_bitfield)
+      error_tok(tok, "cannot take address of bitfield");
+    return new_unary(ND_ADDR, lhs, tok);
+  }
+
+  if (equal(tok, "*")) {
+    // [https://www.sigbus.info/n1570#6.5.3.2p4] This is an oddity
+    // in the C spec, but dereferencing a function shouldn't do
+    // anything. If foo is a function, `*foo`, `**foo` or `*****foo`
+    // are all equivalent to just `foo`.
+    Node *node = cast(rest, tok->next);
+    add_type(node);
+    if (node->ty->kind == TY_FUNC)
+      return node;
+    return new_unary(ND_DEREF, node, tok);
+  }
+
+  if (equal(tok, "!"))
+    return new_unary(ND_NOT, cast(rest, tok->next), tok);
+
+  if (equal(tok, "~"))
+    return new_unary(ND_BITNOT, cast(rest, tok->next), tok);
+
+  // Read ++i as i+=1
+  if (equal(tok, "++"))
+    return to_assign(new_add(unary(rest, tok->next), new_num(1, tok), tok));
+
+  // Read --i as i-=1
+  if (equal(tok, "--"))
+    return to_assign(new_sub(unary(rest, tok->next), new_num(1, tok), tok));
+
+  // [GNU] labels-as-values
+  if (equal(tok, "&&")) {
+    Node *node = new_node(ND_LABEL_VAL, tok);
+    node->label = get_ident(tok->next);
+    node->goto_next = gotos;
+    gotos = node;
+    *rest = tok->next->next;
+    return node;
+  }
+
+  return postfix(rest, tok);
+}
+
+// struct-members = (declspec declarator (","  declarator)* ";")*
+static void struct_members(Token **rest, Token *tok, Type *ty) {
+  Member head = {};
+  Member *cur = &head;
+  int idx = 0;
+
+  while (!equal(tok, "}")) {
+    VarAttr attr = {};
+    Type *basety = declspec(&tok, tok, &attr);
+    bool first = true;
+
+    // Anonymous struct member
+    if ((basety->kind == TY_STRUCT || basety->kind == TY_UNION) &&
+        consume(&tok, tok, ";")) {
+      Member *mem = calloc(1, sizeof(Member));
+      mem->ty = basety;
+      mem->idx = idx++;
+      mem->align = attr.align ? attr.align : mem->ty->align;
+      cur = cur->next = mem;
+      continue;
+    }
+
+    // Regular struct members
+    while (!consume(&tok, tok, ";")) {
+      if (!first)
+        tok = skip(tok, ",");
+      first = false;
+
+      Member *mem = calloc(1, sizeof(Member));
+      mem->ty = declarator(&tok, tok, basety);
+      mem->name = mem->ty->name;
+      mem->idx = idx++;
+      mem->align = attr.align ? attr.align : mem->ty->align;
+
+      if (consume(&tok, tok, ":")) {
+        mem->is_bitfield = true;
+        mem->bit_width = const_expr(&tok, tok);
+      }
+
+      cur = cur->next = mem;
+    }
+  }
+
+  // If the last element is an array of incomplete type, it's
+  // called a "flexible array member". It should behave as if
+  // if were a zero-sized array.
+  if (cur != &head && cur->ty->kind == TY_ARRAY && cur->ty->array_len < 0) {
+    cur->ty = array_of(cur->ty->base, 0);
+    ty->is_flexible = true;
+  }
+
+  *rest = tok->next;
+  ty->members = head.next;
+}
+
+// attribute = ("__attribute__" "(" "(" "packed" ")" ")")*
+static Token *attribute_list(Token *tok, Type *ty) {
+  while (consume(&tok, tok, "__attribute__")) {
+    tok = skip(tok, "(");
+    tok = skip(tok, "(");
+
+    bool first = true;
+
+    while (!consume(&tok, tok, ")")) {
+      if (!first)
+        tok = skip(tok, ",");
+      first = false;
+
+      if (consume(&tok, tok, "packed")) {
+        ty->is_packed = true;
+        continue;
+      }
+
+      if (consume(&tok, tok, "aligned")) {
+        tok = skip(tok, "(");
+        ty->align = const_expr(&tok, tok);
+        tok = skip(tok, ")");
+        continue;
+      }
+
+      error_tok(tok, "unknown attribute");
+    }
+
+    tok = skip(tok, ")");
+  }
+
+  return tok;
+}
+
+// struct-union-decl = attribute? ident? ("{" struct-members)?
+static Type *struct_union_decl(Token **rest, Token *tok) {
+  Type *ty = struct_type();
+  tok = attribute_list(tok, ty);
+
+  // Read a tag.
+  Token *tag = NULL;
+  if (tok->kind == TK_IDENT) {
+    tag = tok;
+    tok = tok->next;
+  }
+
+  if (tag && !equal(tok, "{")) {
+    *rest = tok;
+
+    Type *ty2 = find_tag(tag);
+    if (ty2)
+      return ty2;
+
+    ty->size = -1;
+    push_tag_scope(tag, ty);
+    return ty;
+  }
+
+  tok = skip(tok, "{");
+
+  // Construct a struct object.
+  struct_members(&tok, tok, ty);
+  *rest = attribute_list(tok, ty);
+
+  if (tag) {
+    // If this is a redefinition, overwrite a previous type.
+    // Otherwise, register the struct type.
+    Type *ty2 = hashmap_get2(&scope->tags, tag->loc, tag->len);
+    if (ty2) {
+      *ty2 = *ty;
+      return ty2;
+    }
+
+    push_tag_scope(tag, ty);
+  }
+
+  return ty;
+}
+
+// struct-decl = struct-union-decl
+static Type *struct_decl(Token **rest, Token *tok) {
+  Type *ty = struct_union_decl(rest, tok);
+  ty->kind = TY_STRUCT;
+
+  if (ty->size < 0)
+    return ty;
+
+  // Assign offsets within the struct to members.
+  int bits = 0;
+
+  for (Member *mem = ty->members; mem; mem = mem->next) {
+    if (mem->is_bitfield && mem->bit_width == 0) {
+      // Zero-width anonymous bitfield has a special meaning.
+      // It affects only alignment.
+      bits = align_to(bits, mem->ty->size * 8);
+    } else if (mem->is_bitfield) {
+      int sz = mem->ty->size;
+      if (bits / (sz * 8) != (bits + mem->bit_width - 1) / (sz * 8))
+        bits = align_to(bits, sz * 8);
+
+      mem->offset = align_down(bits / 8, sz);
+      mem->bit_offset = bits % (sz * 8);
+      bits += mem->bit_width;
+    } else {
+      if (!ty->is_packed)
+        bits = align_to(bits, mem->align * 8);
+      mem->offset = bits / 8;
+      bits += mem->ty->size * 8;
+    }
+
+    if (!ty->is_packed && ty->align < mem->align)
+      ty->align = mem->align;
+  }
+
+  ty->size = align_to(bits, ty->align * 8) / 8;
+  return ty;
+}
+
+// union-decl = struct-union-decl
+static Type *union_decl(Token **rest, Token *tok) {
+  Type *ty = struct_union_decl(rest, tok);
+  ty->kind = TY_UNION;
+
+  if (ty->size < 0)
+    return ty;
+
+  // If union, we don't have to assign offsets because they
+  // are already initialized to zero. We need to compute the
+  // alignment and the size though.
+  for (Member *mem = ty->members; mem; mem = mem->next) {
+    if (ty->align < mem->align)
+      ty->align = mem->align;
+    if (ty->size < mem->ty->size)
+      ty->size = mem->ty->size;
+  }
+  ty->size = align_to(ty->size, ty->align);
+  return ty;
+}
+
+// Find a struct member by name.
+static Member *get_struct_member(Type *ty, Token *tok) {
+  for (Member *mem = ty->members; mem; mem = mem->next) {
+    // Anonymous struct member
+    if ((mem->ty->kind == TY_STRUCT || mem->ty->kind == TY_UNION) &&
+        !mem->name) {
+      if (get_struct_member(mem->ty, tok))
+        return mem;
+      continue;
+    }
+
+    // Regular struct member
+    if (mem->name->len == tok->len &&
+        !strncmp(mem->name->loc, tok->loc, tok->len))
+      return mem;
+  }
+  return NULL;
+}
+
+// Create a node representing a struct member access, such as foo.bar
+// where foo is a struct and bar is a member name.
+//
+// C has a feature called "anonymous struct" which allows a struct to
+// have another unnamed struct as a member like this:
+//
+//   struct { struct { int a; }; int b; } x;
+//
+// The members of an anonymous struct belong to the outer struct's
+// member namespace. Therefore, in the above example, you can access
+// member "a" of the anonymous struct as "x.a".
+//
+// This function takes care of anonymous structs.
+static Node *struct_ref(Node *node, Token *tok) {
+  add_type(node);
+  if (node->ty->kind != TY_STRUCT && node->ty->kind != TY_UNION)
+    error_tok(node->tok, "not a struct nor a union");
+
+  Type *ty = node->ty;
+
+  for (;;) {
+    Member *mem = get_struct_member(ty, tok);
+    if (!mem)
+      error_tok(tok, "no such member");
+    node = new_unary(ND_MEMBER, node, tok);
+    node->member = mem;
+    if (mem->name)
+      break;
+    ty = mem->ty;
+  }
+  return node;
+}
+
+// Convert A++ to `(typeof A)((A += 1) - 1)`
+static Node *new_inc_dec(Node *node, Token *tok, int addend) {
+  add_type(node);
+  return new_cast(new_add(to_assign(new_add(node, new_num(addend, tok), tok)),
+                          new_num(-addend, tok), tok),
+                  node->ty);
+}
+
+// postfix = "(" type-name ")" "{" initializer-list "}"
+//         = ident "(" func-args ")" postfix-tail*
+//         | primary postfix-tail*
+//
+// postfix-tail = "[" expr "]"
+//              | "(" func-args ")"
+//              | "." ident
+//              | "->" ident
+//              | "++"
+//              | "--"
+static Node *postfix(Token **rest, Token *tok) {
+  if (equal(tok, "(") && is_typename(tok->next)) {
+    // Compound literal
+    Token *start = tok;
+    Type *ty = typename(&tok, tok->next);
+    tok = skip(tok, ")");
+
+    if (scope->next == NULL) {
+      Obj *var = new_anon_gvar(ty);
+      gvar_initializer(rest, tok, var);
+      return new_var_node(var, start);
+    }
+
+    Obj *var = new_lvar("", ty);
+    Node *lhs = lvar_initializer(rest, tok, var);
+    Node *rhs = new_var_node(var, tok);
+    return new_binary(ND_COMMA, lhs, rhs, start);
+  }
+
+  Node *node = primary(&tok, tok);
+
+  for (;;) {
+    if (equal(tok, "(")) {
+      node = funcall(&tok, tok->next, node);
+      continue;
+    }
+
+    if (equal(tok, "[")) {
+      // x[y] is short for *(x+y)
+      Token *start = tok;
+      Node *idx = expr(&tok, tok->next);
+      tok = skip(tok, "]");
+      node = new_unary(ND_DEREF, new_add(node, idx, start), start);
+      continue;
+    }
+
+    if (equal(tok, ".")) {
+      node = struct_ref(node, tok->next);
+      tok = tok->next->next;
+      continue;
+    }
+
+    if (equal(tok, "->")) {
+      // x->y is short for (*x).y
+      node = new_unary(ND_DEREF, node, tok);
+      node = struct_ref(node, tok->next);
+      tok = tok->next->next;
+      continue;
+    }
+
+    if (equal(tok, "++")) {
+      node = new_inc_dec(node, tok, 1);
+      tok = tok->next;
+      continue;
+    }
+
+    if (equal(tok, "--")) {
+      node = new_inc_dec(node, tok, -1);
+      tok = tok->next;
+      continue;
+    }
+
+    *rest = tok;
+    return node;
+  }
+}
+
+// funcall = (assign ("," assign)*)? ")"
+static Node *funcall(Token **rest, Token *tok, Node *fn) {
+  add_type(fn);
+
+  if (fn->ty->kind != TY_FUNC &&
+      (fn->ty->kind != TY_PTR || fn->ty->base->kind != TY_FUNC))
+    error_tok(fn->tok, "not a function");
+
+  Type *ty = (fn->ty->kind == TY_FUNC) ? fn->ty : fn->ty->base;
+  Type *param_ty = ty->params;
+
+  Node head = {};
+  Node *cur = &head;
+
+  while (!equal(tok, ")")) {
+    if (cur != &head)
+      tok = skip(tok, ",");
+
+    Node *arg = assign(&tok, tok);
+    add_type(arg);
+
+    if (!param_ty && !ty->is_variadic)
+      error_tok(tok, "too many arguments");
+
+    if (param_ty) {
+      if (param_ty->kind != TY_STRUCT && param_ty->kind != TY_UNION)
+        arg = new_cast(arg, param_ty);
+      param_ty = param_ty->next;
+    } else if (arg->ty->kind == TY_FLOAT) {
+      // If parameter type is omitted (e.g. in "..."), float
+      // arguments are promoted to double.
+      arg = new_cast(arg, ty_double);
+    }
+
+    cur = cur->next = arg;
+  }
+
+  if (param_ty)
+    error_tok(tok, "too few arguments");
+
+  *rest = skip(tok, ")");
+
+  Node *node = new_unary(ND_FUNCALL, fn, tok);
+  node->func_ty = ty;
+  node->ty = ty->return_ty;
+  node->args = head.next;
+
+  // If a function returns a struct, it is caller's responsibility
+  // to allocate a space for the return value.
+  if (node->ty->kind == TY_STRUCT || node->ty->kind == TY_UNION)
+    node->ret_buffer = new_lvar("", node->ty);
+  return node;
+}
+
+// generic-selection = "(" assign "," generic-assoc ("," generic-assoc)* ")"
+//
+// generic-assoc = type-name ":" assign
+//               | "default" ":" assign
+static Node *generic_selection(Token **rest, Token *tok) {
+  Token *start = tok;
+  tok = skip(tok, "(");
+
+  Node *ctrl = assign(&tok, tok);
+  add_type(ctrl);
+
+  Type *t1 = ctrl->ty;
+  if (t1->kind == TY_FUNC)
+    t1 = pointer_to(t1);
+  else if (t1->kind == TY_ARRAY)
+    t1 = pointer_to(t1->base);
+
+  Node *ret = NULL;
+
+  while (!consume(rest, tok, ")")) {
+    tok = skip(tok, ",");
+
+    if (equal(tok, "default")) {
+      tok = skip(tok->next, ":");
+      Node *node = assign(&tok, tok);
+      if (!ret)
+        ret = node;
+      continue;
+    }
+
+    Type *t2 = typename(&tok, tok);
+    tok = skip(tok, ":");
+    Node *node = assign(&tok, tok);
+    if (is_compatible(t1, t2))
+      ret = node;
+  }
+
+  if (!ret)
+    error_tok(start, "controlling expression type not compatible with"
+              " any generic association type");
+  return ret;
+}
+
+// primary = "(" "{" stmt+ "}" ")"
+//         | "(" expr ")"
+//         | "sizeof" "(" type-name ")"
+//         | "sizeof" unary
+//         | "_Alignof" "(" type-name ")"
+//         | "_Alignof" unary
+//         | "_Generic" generic-selection
+//         | "__builtin_types_compatible_p" "(" type-name, type-name, ")"
+//         | "__builtin_reg_class" "(" type-name ")"
+//         | ident
+//         | str
+//         | num
+static Node *primary(Token **rest, Token *tok) {
+  Token *start = tok;
+
+  if (equal(tok, "(") && equal(tok->next, "{")) {
+    // This is a GNU statement expresssion.
+    Node *node = new_node(ND_STMT_EXPR, tok);
+    node->body = compound_stmt(&tok, tok->next->next)->body;
+    *rest = skip(tok, ")");
+    return node;
+  }
+
+  if (equal(tok, "(")) {
+    Node *node = expr(&tok, tok->next);
+    *rest = skip(tok, ")");
+    return node;
+  }
+
+  if (equal(tok, "sizeof") && equal(tok->next, "(") && is_typename(tok->next->next)) {
+    Type *ty = typename(&tok, tok->next->next);
+    *rest = skip(tok, ")");
+
+    if (ty->kind == TY_VLA) {
+      if (ty->vla_size)
+        return new_var_node(ty->vla_size, tok);
+
+      Node *lhs = compute_vla_size(ty, tok);
+      Node *rhs = new_var_node(ty->vla_size, tok);
+      return new_binary(ND_COMMA, lhs, rhs, tok);
+    }
+
+    return new_ulong(ty->size, start);
+  }
+
+  if (equal(tok, "sizeof")) {
+    Node *node = unary(rest, tok->next);
+    add_type(node);
+    if (node->ty->kind == TY_VLA)
+      return new_var_node(node->ty->vla_size, tok);
+    return new_ulong(node->ty->size, tok);
+  }
+
+  if (equal(tok, "_Alignof") && equal(tok->next, "(") && is_typename(tok->next->next)) {
+    Type *ty = typename(&tok, tok->next->next);
+    *rest = skip(tok, ")");
+    return new_ulong(ty->align, tok);
+  }
+
+  if (equal(tok, "_Alignof")) {
+    Node *node = unary(rest, tok->next);
+    add_type(node);
+    return new_ulong(node->ty->align, tok);
+  }
+
+  if (equal(tok, "_Generic"))
+    return generic_selection(rest, tok->next);
+
+  if (equal(tok, "__builtin_types_compatible_p")) {
+    tok = skip(tok->next, "(");
+    Type *t1 = typename(&tok, tok);
+    tok = skip(tok, ",");
+    Type *t2 = typename(&tok, tok);
+    *rest = skip(tok, ")");
+    return new_num(is_compatible(t1, t2), start);
+  }
+
+  if (equal(tok, "__builtin_reg_class")) {
+    tok = skip(tok->next, "(");
+    Type *ty = typename(&tok, tok);
+    *rest = skip(tok, ")");
+
+    if (is_integer(ty) || ty->kind == TY_PTR)
+      return new_num(0, start);
+    if (is_flonum(ty))
+      return new_num(1, start);
+    return new_num(2, start);
+  }
+
+  if (equal(tok, "__builtin_compare_and_swap")) {
+    Node *node = new_node(ND_CAS, tok);
+    tok = skip(tok->next, "(");
+    node->cas_addr = assign(&tok, tok);
+    tok = skip(tok, ",");
+    node->cas_old = assign(&tok, tok);
+    tok = skip(tok, ",");
+    node->cas_new = assign(&tok, tok);
+    *rest = skip(tok, ")");
+    return node;
+  }
+
+  if (equal(tok, "__builtin_atomic_exchange")) {
+    Node *node = new_node(ND_EXCH, tok);
+    tok = skip(tok->next, "(");
+    node->lhs = assign(&tok, tok);
+    tok = skip(tok, ",");
+    node->rhs = assign(&tok, tok);
+    *rest = skip(tok, ")");
+    return node;
+  }
+
+  if (tok->kind == TK_IDENT) {
+    // Variable or enum constant
+    VarScope *sc = find_var(tok);
+    *rest = tok->next;
+
+    // For "static inline" function
+    if (sc && sc->var && sc->var->is_function) {
+      if (current_fn)
+        strarray_push(&current_fn->refs, sc->var->name);
+      else
+        sc->var->is_root = true;
+    }
+
+    if (sc) {
+      if (sc->var)
+        return new_var_node(sc->var, tok);
+      if (sc->enum_ty)
+        return new_num(sc->enum_val, tok);
+    }
+
+    if (equal(tok->next, "("))
+      error_tok(tok, "implicit declaration of a function");
+    error_tok(tok, "undefined variable");
+  }
+
+  if (tok->kind == TK_STR) {
+    Obj *var = new_string_literal(tok->str, tok->ty);
+    *rest = tok->next;
+    return new_var_node(var, tok);
+  }
+
+  if (tok->kind == TK_NUM) {
+    Node *node;
+    if (is_flonum(tok->ty)) {
+      node = new_node(ND_NUM, tok);
+      node->fval = tok->fval;
+    } else {
+      node = new_num(tok->val, tok);
+    }
+
+    node->ty = tok->ty;
+    *rest = tok->next;
+    return node;
+  }
+
+  error_tok(tok, "expected an expression");
+}
+
+static Token *parse_typedef(Token *tok, Type *basety) {
+  bool first = true;
+
+  while (!consume(&tok, tok, ";")) {
+    if (!first)
+      tok = skip(tok, ",");
+    first = false;
+
+    Type *ty = declarator(&tok, tok, basety);
+    if (!ty->name)
+      error_tok(ty->name_pos, "typedef name omitted");
+    push_scope(get_ident(ty->name))->type_def = ty;
+  }
+  return tok;
+}
+
+static void create_param_lvars(Type *param) {
+  if (param) {
+    create_param_lvars(param->next);
+    if (!param->name)
+      error_tok(param->name_pos, "parameter name omitted");
+    new_lvar(get_ident(param->name), param);
+  }
+}
+
+// This function matches gotos or labels-as-values with labels.
+//
+// We cannot resolve gotos as we parse a function because gotos
+// can refer a label that appears later in the function.
+// So, we need to do this after we parse the entire function.
+static void resolve_goto_labels(void) {
+  for (Node *x = gotos; x; x = x->goto_next) {
+    for (Node *y = labels; y; y = y->goto_next) {
+      if (!strcmp(x->label, y->label)) {
+        x->unique_label = y->unique_label;
+        break;
+      }
+    }
+
+    if (x->unique_label == NULL)
+      error_tok(x->tok->next, "use of undeclared label");
+  }
+
+  gotos = labels = NULL;
+}
+
+static Obj *find_func(char *name) {
+  Scope *sc = scope;
+  while (sc->next)
+    sc = sc->next;
+
+  VarScope *sc2 = hashmap_get(&sc->vars, name);
+  if (sc2 && sc2->var && sc2->var->is_function)
+    return sc2->var;
+  return NULL;
+}
+
+static void mark_live(Obj *var) {
+  if (!var->is_function || var->is_live)
+    return;
+  var->is_live = true;
+
+  for (int i = 0; i < var->refs.len; i++) {
+    Obj *fn = find_func(var->refs.data[i]);
+    if (fn)
+      mark_live(fn);
+  }
+}
+
+static Token *function(Token *tok, Type *basety, VarAttr *attr) {
+  Type *ty = declarator(&tok, tok, basety);
+  if (!ty->name)
+    error_tok(ty->name_pos, "function name omitted");
+  char *name_str = get_ident(ty->name);
+
+  Obj *fn = find_func(name_str);
+  if (fn) {
+    // Redeclaration
+    if (!fn->is_function)
+      error_tok(tok, "redeclared as a different kind of symbol");
+    if (fn->is_definition && equal(tok, "{"))
+      error_tok(tok, "redefinition of %s", name_str);
+    if (!fn->is_static && attr->is_static)
+      error_tok(tok, "static declaration follows a non-static declaration");
+    fn->is_definition = fn->is_definition || equal(tok, "{");
+  } else {
+    fn = new_gvar(name_str, ty);
+    fn->is_function = true;
+    fn->is_definition = equal(tok, "{");
+    fn->is_static = attr->is_static || (attr->is_inline && !attr->is_extern);
+    fn->is_inline = attr->is_inline;
+  }
+
+  fn->is_root = !(fn->is_static && fn->is_inline);
+
+  if (consume(&tok, tok, ";"))
+    return tok;
+
+  current_fn = fn;
+  locals = NULL;
+  enter_scope();
+  create_param_lvars(ty->params);
+
+  // A buffer for a struct/union return value is passed
+  // as the hidden first parameter.
+  Type *rty = ty->return_ty;
+  if ((rty->kind == TY_STRUCT || rty->kind == TY_UNION) && rty->size > 16)
+    new_lvar("", pointer_to(rty));
+
+  fn->params = locals;
+
+  if (ty->is_variadic)
+    fn->va_area = new_lvar("__va_area__", array_of(ty_char, 136));
+  fn->alloca_bottom = new_lvar("__alloca_size__", pointer_to(ty_char));
+
+  tok = skip(tok, "{");
+
+  // [https://www.sigbus.info/n1570#6.4.2.2p1] "__func__" is
+  // automatically defined as a local variable containing the
+  // current function name.
+  push_scope("__func__")->var =
+    new_string_literal(fn->name, array_of(ty_char, strlen(fn->name) + 1));
+
+  // [GNU] __FUNCTION__ is yet another name of __func__.
+  push_scope("__FUNCTION__")->var =
+    new_string_literal(fn->name, array_of(ty_char, strlen(fn->name) + 1));
+
+  fn->body = compound_stmt(&tok, tok);
+  fn->locals = locals;
+  leave_scope();
+  resolve_goto_labels();
+  return tok;
+}
+
+static Token *global_variable(Token *tok, Type *basety, VarAttr *attr) {
+  bool first = true;
+
+  while (!consume(&tok, tok, ";")) {
+    if (!first)
+      tok = skip(tok, ",");
+    first = false;
+
+    Type *ty = declarator(&tok, tok, basety);
+    if (!ty->name)
+      error_tok(ty->name_pos, "variable name omitted");
+
+    Obj *var = new_gvar(get_ident(ty->name), ty);
+    var->is_definition = !attr->is_extern;
+    var->is_static = attr->is_static;
+    var->is_tls = attr->is_tls;
+    if (attr->align)
+      var->align = attr->align;
+
+    if (equal(tok, "="))
+      gvar_initializer(&tok, tok->next, var);
+    else if (!attr->is_extern && !attr->is_tls)
+      var->is_tentative = true;
+  }
+  return tok;
+}
+
+// Lookahead tokens and returns true if a given token is a start
+// of a function definition or declaration.
+static bool is_function(Token *tok) {
+  if (equal(tok, ";"))
+    return false;
+
+  Type dummy = {};
+  Type *ty = declarator(&tok, tok, &dummy);
+  return ty->kind == TY_FUNC;
+}
+
+// Remove redundant tentative definitions.
+static void scan_globals(void) {
+  Obj head;
+  Obj *cur = &head;
+
+  for (Obj *var = globals; var; var = var->next) {
+    if (!var->is_tentative) {
+      cur = cur->next = var;
+      continue;
+    }
+
+    // Find another definition of the same identifier.
+    Obj *var2 = globals;
+    for (; var2; var2 = var2->next)
+      if (var != var2 && var2->is_definition && !strcmp(var->name, var2->name))
+        break;
+
+    // If there's another definition, the tentative definition
+    // is redundant
+    if (!var2)
+      cur = cur->next = var;
+  }
+
+  cur->next = NULL;
+  globals = head.next;
+}
+
+static void declare_builtin_functions(void) {
+  Type *ty = func_type(pointer_to(ty_void));
+  ty->params = copy_type(ty_int);
+  builtin_alloca = new_gvar("alloca", ty);
+  builtin_alloca->is_definition = false;
+}
+
+// program = (typedef | function-definition | global-variable)*
+Obj *parse(Token *tok) {
+  declare_builtin_functions();
+  globals = NULL;
+
+  while (tok->kind != TK_EOF) {
+    VarAttr attr = {};
+    Type *basety = declspec(&tok, tok, &attr);
+
+    // Typedef
+    if (attr.is_typedef) {
+      tok = parse_typedef(tok, basety);
+      continue;
+    }
+
+    // Function
+    if (is_function(tok)) {
+      tok = function(tok, basety, &attr);
+      continue;
+    }
+
+    // Global variable
+    tok = global_variable(tok, basety, &attr);
+  }
+
+  for (Obj *var = globals; var; var = var->next)
+    if (var->is_root)
+      mark_live(var);
+
+  // Remove redundant tentative definitions.
+  scan_globals();
+  return globals;
+}