Do not emit static inline functions if referenced by no one

chibicc.h

@@ -146,6 +146,11 @@ struct Obj {
   Obj *locals;
   Obj *va_area;
   int stack_size;
+
+  // Static inline function
+  bool is_live;
+  bool is_root;
+  StringArray refs;
 };
 
 // Global variable can be initialized either by a constant expression

codegen.c

@@ -1199,6 +1199,11 @@ static void emit_text(Obj *prog) {
     if (!fn->is_function || !fn->is_definition)
       continue;
 
+    // No code is emitted for "static inline" functions
+    // if no one is referencing them.
+    if (!fn->is_live)
+      continue;
+
     if (fn->is_static)
       println("  .local %s", fn->name);
     else

parse.c

@@ -2766,6 +2766,14 @@ static Node *primary(Token **rest, Token *tok) {
     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);
@@ -2847,6 +2855,29 @@ static void resolve_goto_labels(void) {
   gotos = labels = NULL;
 }
 
+static Obj *find_func(char *name) {
+  Scope *sc = scope;
+  while (sc->next)
+    sc = sc->next;
+
+  for (VarScope *sc2 = sc->vars; sc2; sc2 = sc2->next)
+    if (!strcmp(sc2->name, name) && 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)
@@ -2857,6 +2888,7 @@ static Token *function(Token *tok, Type *basety, VarAttr *attr) {
   fn->is_definition = !consume(&tok, 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 (!fn->is_definition)
     return tok;
@@ -2953,5 +2985,10 @@ Obj *parse(Token *tok) {
     // Global variable
     tok = global_variable(tok, basety, &attr);
   }
+
+  for (Obj *var = globals; var; var = var->next)
+    if (var->is_root)
+      mark_live(var);
+
   return globals;
 }

test/driver.sh

@@ -125,4 +125,40 @@ echo 'int foo(); int main() { foo(); }' > $tmp/inline2.c
 $chibicc -o /dev/null $tmp/inline1.c $tmp/inline2.c
 check inline
 
+echo 'static inline void f1() {}' | $chibicc -o- -S - | grep -v -q f1:
+check inline
+
+echo 'static inline void f1() {} void foo() { f1(); }' | $chibicc -o- -S - | grep -q f1:
+check inline
+
+echo 'static inline void f1() {} static inline void f2() { f1(); } void foo() { f1(); }' | $chibicc -o- -S - | grep -q f1:
+check inline
+
+echo 'static inline void f1() {} static inline void f2() { f1(); } void foo() { f1(); }' | $chibicc -o- -S - | grep -v -q f2:
+check inline
+
+echo 'static inline void f1() {} static inline void f2() { f1(); } void foo() { f2(); }' | $chibicc -o- -S - | grep -q f1:
+check inline
+
+echo 'static inline void f1() {} static inline void f2() { f1(); } void foo() { f2(); }' | $chibicc -o- -S - | grep -q f2:
+check inline
+
+echo 'static inline void f2(); static inline void f1() { f2(); } static inline void f2() { f1(); } void foo() {}' | $chibicc -o- -S - | grep -v -q f1:
+check inline
+
+echo 'static inline void f2(); static inline void f1() { f2(); } static inline void f2() { f1(); } void foo() {}' | $chibicc -o- -S - | grep -v -q f2:
+check inline
+
+echo 'static inline void f2(); static inline void f1() { f2(); } static inline void f2() { f1(); } void foo() { f1(); }' | $chibicc -o- -S - | grep -q f1:
+check inline
+
+echo 'static inline void f2(); static inline void f1() { f2(); } static inline void f2() { f1(); } void foo() { f1(); }' | $chibicc -o- -S - | grep -q f2:
+check inline
+
+echo 'static inline void f2(); static inline void f1() { f2(); } static inline void f2() { f1(); } void foo() { f2(); }' | $chibicc -o- -S - | grep -q f1:
+check inline
+
+echo 'static inline void f2(); static inline void f1() { f2(); } static inline void f2() { f1(); } void foo() { f2(); }' | $chibicc -o- -S - | grep -q f2:
+check inline
+
 echo OK