summaryrefslogtreecommitdiffhomepage
path: root/src/3p/chibicc/parse.c
diff options
context:
space:
mode:
authorMichael Smith <mikesmiffy128@gmail.com>2021-11-20 03:10:50 +0000
committerMichael Smith <mikesmiffy128@gmail.com>2021-11-20 03:18:08 +0000
commitda6f343032cb01597dc7866e66f091adf3243a62 (patch)
tree870f8cb8e82bb42202ab92bea03fc6ab35ada7ca /src/3p/chibicc/parse.c
Initial public snapshot
With code from Bill. Thanks Bill!
Diffstat (limited to 'src/3p/chibicc/parse.c')
-rw-r--r--src/3p/chibicc/parse.c3368
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;
+}