* configure.in: check function attirbute const and pure,

  and define CONSTFUNC and PUREFUNC if available.
  Note that I don't add those options as default because
  it still shows many false-positive (it seems not to consider
  longjmp).

* vm_eval.c (stack_check): get rb_thread_t* as an argument
  to avoid duplicate call of GET_THREAD().

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54952 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

19 files changed, 99 insertions, 80 deletions

diff --git a/ChangeLog b/ChangeLog
index 054eed0298..17948762ae 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+Mon May  9 02:39:16 2016  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* configure.in: check function attirbute const and pure,
+	  and define CONSTFUNC and PUREFUNC if available.
+	  Note that I don't add those options as default because
+	  it still shows many false-positive (it seems not to consider
+	  longjmp).
+
+	* vm_eval.c (stack_check): get rb_thread_t* as an argument
+	  to avoid duplicate call of GET_THREAD().
+
 Sun May  8 21:01:14 2016  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/openssl/extconf.rb: assume it doesn't have SSLv2 related
diff --git a/configure.in b/configure.in
index 48ee91c323..8fb0643312 100644
--- a/configure.in
+++ b/configure.in
@@ -1800,6 +1800,8 @@ AC_DEFUN([RUBY_TYPE_ATTRIBUTE], [dnl
 ])
 ])
 
+RUBY_FUNC_ATTRIBUTE(const, CONSTFUNC)
+RUBY_FUNC_ATTRIBUTE(pure, PUREFUNC)
 RUBY_FUNC_ATTRIBUTE(noreturn, NORETURN)
 RUBY_FUNC_ATTRIBUTE(deprecated, DEPRECATED)
 RUBY_FUNC_ATTRIBUTE(deprecated("by "@%:@n), DEPRECATED_BY(n,x), rb_cv_func_deprecated_by)
diff --git a/eval_intern.h b/eval_intern.h
index 78861b32fb..8da66c9017 100644
--- a/eval_intern.h
+++ b/eval_intern.h
@@ -278,7 +278,6 @@ rb_cref_t *rb_vm_cref_replace_with_duplicated_cref(void);
 VALUE rb_vm_call_cfunc(VALUE recv, VALUE (*func)(VALUE), VALUE arg, const rb_block_t *blockptr, VALUE filename);
 void rb_vm_set_progname(VALUE filename);
 void rb_thread_terminate_all(void);
-VALUE rb_vm_top_self();
 VALUE rb_vm_cbase(void);
 
 #ifndef CharNext		/* defined as CharNext[AW] on Windows. */
diff --git a/gc.c b/gc.c
index 6923ccdfee..92885754a4 100644
--- a/gc.c
+++ b/gc.c
@@ -2033,6 +2033,7 @@ rb_objspace_data_type_name(VALUE obj)
     }
 }
 
+PUREFUNC(static inline int is_pointer_to_heap(rb_objspace_t *objspace, void *ptr);)
 static inline int
 is_pointer_to_heap(rb_objspace_t *objspace, void *ptr)
 {
@@ -2900,6 +2901,7 @@ rb_objspace_call_finalizer(rb_objspace_t *objspace)
     ATOMIC_SET(finalizing, 0);
 }
 
+PUREFUNC(static inline int is_id_value(rb_objspace_t *objspace, VALUE ptr));
 static inline int
 is_id_value(rb_objspace_t *objspace, VALUE ptr)
 {
diff --git a/include/ruby/encoding.h b/include/ruby/encoding.h
index ceedf0db65..4e10b77f7a 100644
--- a/include/ruby/encoding.h
+++ b/include/ruby/encoding.h
@@ -113,8 +113,8 @@ int rb_char_to_option_kcode(int c, int *option, int *kcode);
 
 int rb_enc_replicate(const char *, rb_encoding *);
 int rb_define_dummy_encoding(const char *);
-int rb_enc_dummy_p(rb_encoding *enc);
-int rb_enc_to_index(rb_encoding *enc);
+PUREFUNC(int rb_enc_dummy_p(rb_encoding *enc));
+PUREFUNC(int rb_enc_to_index(rb_encoding *enc));
 int rb_enc_get_index(VALUE obj);
 void rb_enc_set_index(VALUE obj, int encindex);
 int rb_enc_find_index(const char *name);
@@ -240,8 +240,8 @@ rb_enc_asciicompat_inline(rb_encoding *enc)
 #define rb_enc_asciicompat(enc) rb_enc_asciicompat_inline(enc)
 
 int rb_enc_casefold(char *to, const char *p, const char *e, rb_encoding *enc);
-int rb_enc_toupper(int c, rb_encoding *enc);
-int rb_enc_tolower(int c, rb_encoding *enc);
+CONSTFUNC(int rb_enc_toupper(int c, rb_encoding *enc));
+CONSTFUNC(int rb_enc_tolower(int c, rb_encoding *enc));
 ID rb_intern3(const char*, long, rb_encoding*);
 ID rb_interned_id_p(const char *, long, rb_encoding *);
 int rb_enc_symname_p(const char*, rb_encoding*);
@@ -251,7 +251,7 @@ long rb_str_coderange_scan_restartable(const char*, const char*, rb_encoding*, i
 int rb_enc_str_asciionly_p(VALUE);
 #define rb_enc_str_asciicompat_p(str) rb_enc_asciicompat(rb_enc_get(str))
 VALUE rb_enc_from_encoding(rb_encoding *enc);
-int rb_enc_unicode_p(rb_encoding *enc);
+PUREFUNC(int rb_enc_unicode_p(rb_encoding *enc));
 rb_encoding *rb_ascii8bit_encoding(void);
 rb_encoding *rb_utf8_encoding(void);
 rb_encoding *rb_usascii_encoding(void);
@@ -260,13 +260,13 @@ rb_encoding *rb_filesystem_encoding(void);
 rb_encoding *rb_default_external_encoding(void);
 rb_encoding *rb_default_internal_encoding(void);
 #ifndef rb_ascii8bit_encindex
-int rb_ascii8bit_encindex(void);
+CONSTFUNC(int rb_ascii8bit_encindex(void));
 #endif
 #ifndef rb_utf8_encindex
-int rb_utf8_encindex(void);
+CONSTFUNC(int rb_utf8_encindex(void));
 #endif
 #ifndef rb_usascii_encindex
-int rb_usascii_encindex(void);
+CONSTFUNC(int rb_usascii_encindex(void));
 #endif
 int rb_locale_encindex(void);
 int rb_filesystem_encindex(void);
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index 7edfccbbf7..a33f7cc407 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -254,9 +254,9 @@ NORETURN(DEPRECATED(PRINTF_ARGS(void rb_compile_error_with_enc(const char*, int,
 NORETURN(DEPRECATED(PRINTF_ARGS(void rb_compile_error_append(const char*, ...), 1, 2)));
 NORETURN(void rb_error_frozen(const char*));
 NORETURN(void rb_error_frozen_object(VALUE));
-void rb_error_untrusted(VALUE);
+CONSTFUNC(void rb_error_untrusted(VALUE));
 void rb_check_frozen(VALUE);
-void rb_check_trusted(VALUE);
+CONSTFUNC(void rb_check_trusted(VALUE));
 #define rb_check_frozen_internal(obj) do { \
 	VALUE frozen_obj = (obj); \
 	if (OBJ_FROZEN(frozen_obj)) { \
@@ -293,7 +293,6 @@ const char *rb_sourcefile(void);
 VALUE rb_check_funcall(VALUE, ID, int, const VALUE*);
 
 NORETURN(void rb_error_arity(int, int, int));
-#define rb_check_arity rb_check_arity /* for ifdef */
 static inline int
 rb_check_arity(int argc, int min, int max)
 {
@@ -301,6 +300,7 @@ rb_check_arity(int argc, int min, int max)
 	rb_error_arity(argc, min, max);
     return argc;
 }
+#define rb_check_arity rb_check_arity /* for ifdef */
 
 #if defined(NFDBITS) && defined(HAVE_RB_FD_INIT)
 typedef struct {
@@ -482,7 +482,7 @@ VALUE rb_str_encode_ospath(VALUE);
 int rb_is_absolute_path(const char *);
 /* gc.c */
 NORETURN(void rb_memerror(void));
-int rb_during_gc(void);
+PUREFUNC(int rb_during_gc(void););
 void rb_gc_mark_locations(const VALUE*, const VALUE*);
 void rb_mark_tbl(struct st_table*);
 void rb_mark_set(struct st_table*);
@@ -580,7 +580,7 @@ VALUE rb_num_coerce_relop(VALUE, VALUE, ID);
 VALUE rb_num_coerce_bit(VALUE, VALUE, ID);
 VALUE rb_num2fix(VALUE);
 VALUE rb_fix2str(VALUE, int);
-VALUE rb_dbl_cmp(double, double);
+CONSTFUNC(VALUE rb_dbl_cmp(double, double));
 /* object.c */
 int rb_eql(VALUE, VALUE);
 VALUE rb_any_to_s(VALUE);
@@ -592,17 +592,17 @@ VALUE rb_obj_clone(VALUE);
 VALUE rb_obj_dup(VALUE);
 VALUE rb_obj_init_copy(VALUE,VALUE);
 VALUE rb_obj_taint(VALUE);
-VALUE rb_obj_tainted(VALUE);
+PUREFUNC(VALUE rb_obj_tainted(VALUE));
 VALUE rb_obj_untaint(VALUE);
 VALUE rb_obj_untrust(VALUE);
-VALUE rb_obj_untrusted(VALUE);
+PUREFUNC(VALUE rb_obj_untrusted(VALUE));
 VALUE rb_obj_trust(VALUE);
 VALUE rb_obj_freeze(VALUE);
-VALUE rb_obj_frozen_p(VALUE);
+PUREFUNC(VALUE rb_obj_frozen_p(VALUE));
 VALUE rb_obj_id(VALUE);
 VALUE rb_obj_class(VALUE);
-VALUE rb_class_real(VALUE);
-VALUE rb_class_inherited_p(VALUE, VALUE);
+PUREFUNC(VALUE rb_class_real(VALUE));
+PUREFUNC(VALUE rb_class_inherited_p(VALUE, VALUE));
 VALUE rb_class_superclass(VALUE);
 VALUE rb_class_get_superclass(VALUE);
 VALUE rb_convert_type(VALUE,int,const char*,const char*);
@@ -621,13 +621,13 @@ double rb_cstr_to_dbl(const char*, int);
 double rb_str_to_dbl(VALUE, int);
 /* parse.y */
 ID rb_id_attrset(ID);
-int rb_is_const_id(ID);
-int rb_is_global_id(ID);
-int rb_is_instance_id(ID);
-int rb_is_attrset_id(ID);
-int rb_is_class_id(ID);
-int rb_is_local_id(ID);
-int rb_is_junk_id(ID);
+CONSTFUNC(int rb_is_const_id(ID));
+CONSTFUNC(int rb_is_global_id(ID));
+CONSTFUNC(int rb_is_instance_id(ID));
+CONSTFUNC(int rb_is_attrset_id(ID));
+CONSTFUNC(int rb_is_class_id(ID));
+CONSTFUNC(int rb_is_local_id(ID));
+CONSTFUNC(int rb_is_junk_id(ID));
 int rb_symname_p(const char*);
 int rb_sym_interned_p(VALUE);
 VALUE rb_backref_get(void);
@@ -784,7 +784,7 @@ VALUE rb_sym_to_s(VALUE);
 long rb_str_strlen(VALUE);
 VALUE rb_str_length(VALUE);
 long rb_str_offset(VALUE, long);
-size_t rb_str_capacity(VALUE);
+PUREFUNC(size_t rb_str_capacity(VALUE););
 VALUE rb_str_ellipsize(VALUE, long);
 VALUE rb_str_scrub(VALUE, VALUE);
 /* symbol.c */
diff --git a/include/ruby/io.h b/include/ruby/io.h
index a15795252b..60d6f6d32e 100644
--- a/include/ruby/io.h
+++ b/include/ruby/io.h
@@ -130,7 +130,7 @@ FILE *rb_io_stdio_file(rb_io_t *fptr);
 FILE *rb_fdopen(int, const char*);
 int rb_io_modestr_fmode(const char *modestr);
 int rb_io_modestr_oflags(const char *modestr);
-int rb_io_oflags_fmode(int oflags);
+CONSTFUNC(int rb_io_oflags_fmode(int oflags));
 void rb_io_check_writable(rb_io_t*);
 void rb_io_check_readable(rb_io_t*);
 void rb_io_check_char_readable(rb_io_t *fptr);
diff --git a/include/ruby/oniguruma.h b/include/ruby/oniguruma.h
index defa3917e5..b45072f48d 100644
--- a/include/ruby/oniguruma.h
+++ b/include/ruby/oniguruma.h
@@ -342,10 +342,8 @@ ONIG_EXTERN
 int onigenc_init P_((void));
 ONIG_EXTERN
 int onigenc_set_default_encoding P_((OnigEncoding enc));
-ONIG_EXTERN
-OnigEncoding onigenc_get_default_encoding P_((void));
-ONIG_EXTERN
-void  onigenc_set_default_caseconv_table P_((const OnigUChar* table));
+PUREFUNC(ONIG_EXTERN OnigEncoding onigenc_get_default_encoding P_((void)));
+PUREFUNC(ONIG_EXTERN void  onigenc_set_default_caseconv_table P_((const OnigUChar* table)));
 ONIG_EXTERN
 OnigUChar* onigenc_get_right_adjust_char_head_with_prev P_((OnigEncoding enc, const OnigUChar* start, const OnigUChar* s, const OnigUChar* end, const OnigUChar** prev));
 ONIG_EXTERN
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 9fc7c68e63..0283d7b721 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -624,7 +624,7 @@ int rb_safe_level(void);
 void rb_set_safe_level(int);
 #if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4))
 int ruby_safe_level_2_error(void) __attribute__((error("$SAFE=2 to 4 are obsolete")));
-int ruby_safe_level_2_warning(void) __attribute__((warning("$SAFE=2 to 4 are obsolete")));
+int ruby_safe_level_2_warning(void) __attribute__((const,warning("$SAFE=2 to 4 are obsolete")));
 # ifdef RUBY_EXPORT
 #   define ruby_safe_level_2_warning() ruby_safe_level_2_error()
 # endif
@@ -650,7 +650,7 @@ int ruby_safe_level_2_warning(void) __attribute__((warning("$SAFE=2 to 4 are obs
 #define rb_set_safe_level(level) rb_set_safe_level(RUBY_SAFE_LEVEL_CHECK(level, error))
 #endif
 void rb_set_safe_level_force(int);
-void rb_secure_update(VALUE);
+CONSTFUNC(void rb_secure_update(VALUE));
 NORETURN(void rb_insecure_operation(void));
 
 VALUE rb_errinfo(void);
@@ -952,7 +952,7 @@ enum {
     RMODULE_ENUM_END
 };
 
-double rb_float_value(VALUE);
+PUREFUNC(double rb_float_value(VALUE));
 VALUE rb_float_new(double);
 VALUE rb_float_new_in_heap(double);
 
diff --git a/include/ruby/st.h b/include/ruby/st.h
index 190bad2a35..de5aaaebec 100644
--- a/include/ruby/st.h
+++ b/include/ruby/st.h
@@ -131,18 +131,18 @@ void st_free_table(st_table *);
 void st_cleanup_safe(st_table *, st_data_t);
 void st_clear(st_table *);
 st_table *st_copy(st_table *);
-int st_numcmp(st_data_t, st_data_t);
-st_index_t st_numhash(st_data_t);
-int st_locale_insensitive_strcasecmp(const char *s1, const char *s2);
-int st_locale_insensitive_strncasecmp(const char *s1, const char *s2, size_t n);
+CONSTFUNC(int st_numcmp(st_data_t, st_data_t));
+CONSTFUNC(st_index_t st_numhash(st_data_t));
+PUREFUNC(int st_locale_insensitive_strcasecmp(const char *s1, const char *s2));
+PUREFUNC(int st_locale_insensitive_strncasecmp(const char *s1, const char *s2, size_t n));
 #define st_strcasecmp st_locale_insensitive_strcasecmp
 #define st_strncasecmp st_locale_insensitive_strncasecmp
-size_t st_memsize(const st_table *);
-st_index_t st_hash(const void *ptr, size_t len, st_index_t h);
-st_index_t st_hash_uint32(st_index_t h, uint32_t i);
-st_index_t st_hash_uint(st_index_t h, st_index_t i);
-st_index_t st_hash_end(st_index_t h);
-st_index_t st_hash_start(st_index_t h);
+PUREFUNC(size_t st_memsize(const st_table *));
+PUREFUNC(st_index_t st_hash(const void *ptr, size_t len, st_index_t h));
+CONSTFUNC(st_index_t st_hash_uint32(st_index_t h, uint32_t i));
+CONSTFUNC(st_index_t st_hash_uint(st_index_t h, st_index_t i));
+CONSTFUNC(st_index_t st_hash_end(st_index_t h));
+CONSTFUNC(st_index_t st_hash_start(st_index_t h));
 #define st_hash_start(h) ((st_index_t)(h))
 
 RUBY_SYMBOL_EXPORT_END
diff --git a/insns.def b/insns.def
index 65410e1451..d34a66342c 100644
--- a/insns.def
+++ b/insns.def
@@ -2088,8 +2088,6 @@ opt_not
 (VALUE recv)
 (VALUE val)
 {
-    extern VALUE rb_obj_not(VALUE obj);
-
     vm_search_method(ci, cc, recv);
 
     if (check_cfunc(cc->me, rb_obj_not)) {
diff --git a/internal.h b/internal.h
index 8b04dbd112..c53b8eab95 100644
--- a/internal.h
+++ b/internal.h
@@ -892,7 +892,7 @@ VALUE rb_invcmp(VALUE, VALUE);
 struct rb_block_struct;
 int rb_dvar_defined(ID, const struct rb_block_struct *);
 int rb_local_defined(ID, const struct rb_block_struct *);
-const char * rb_insns_name(int i);
+CONSTFUNC(const char * rb_insns_name(int i));
 VALUE rb_insns_name_array(void);
 
 /* complex.c */
@@ -913,7 +913,7 @@ void Init_ext(void);
 
 /* encoding.c */
 ID rb_id_encoding(void);
-void rb_gc_mark_encodings(void);
+CONSTFUNC(void rb_gc_mark_encodings(void));
 rb_encoding *rb_enc_get_from_index(int index);
 rb_encoding *rb_enc_check_str(VALUE str1, VALUE str2);
 int rb_encdb_replicate(const char *alias, const char *orig);
@@ -923,7 +923,7 @@ void rb_encdb_declare(const char *name);
 void rb_enc_set_base(const char *name, const char *orig);
 int rb_enc_set_dummy(int index);
 void rb_encdb_set_unicode(int index);
-int rb_data_is_encoding(VALUE obj);
+PUREFUNC(int rb_data_is_encoding(VALUE obj));
 
 /* enum.c */
 VALUE rb_f_send(int argc, VALUE *argv, VALUE recv);
@@ -1180,7 +1180,8 @@ rb_float_new_inline(double d)
 
 /* object.c */
 void rb_obj_copy_ivar(VALUE dest, VALUE obj);
-VALUE rb_obj_equal(VALUE obj1, VALUE obj2);
+CONSTFUNC(VALUE rb_obj_equal(VALUE obj1, VALUE obj2));
+CONSTFUNC(VALUE rb_obj_not(VALUE obj));
 VALUE rb_class_search_ancestor(VALUE klass, VALUE super);
 NORETURN(void rb_undefined_alloc(VALUE klass));
 double rb_num_to_dbl(VALUE val);
@@ -1214,14 +1215,14 @@ int rb_is_attrset_name(VALUE name);
 int rb_is_local_name(VALUE name);
 int rb_is_method_name(VALUE name);
 int rb_is_junk_name(VALUE name);
-int rb_is_const_sym(VALUE sym);
-int rb_is_class_sym(VALUE sym);
-int rb_is_global_sym(VALUE sym);
-int rb_is_instance_sym(VALUE sym);
-int rb_is_attrset_sym(VALUE sym);
-int rb_is_local_sym(VALUE sym);
-int rb_is_method_sym(VALUE sym);
-int rb_is_junk_sym(VALUE sym);
+PUREFUNC(int rb_is_const_sym(VALUE sym));
+PUREFUNC(int rb_is_class_sym(VALUE sym));
+PUREFUNC(int rb_is_global_sym(VALUE sym));
+PUREFUNC(int rb_is_instance_sym(VALUE sym));
+PUREFUNC(int rb_is_attrset_sym(VALUE sym));
+PUREFUNC(int rb_is_local_sym(VALUE sym));
+PUREFUNC(int rb_is_method_sym(VALUE sym));
+PUREFUNC(int rb_is_junk_sym(VALUE sym));
 ID rb_make_internal_id(void);
 void rb_gc_free_dsymbol(VALUE);
 ID rb_id_attrget(ID id);
@@ -1451,7 +1452,7 @@ VALUE rb_obj_is_thread(VALUE obj);
 void rb_vm_mark(void *ptr);
 void Init_BareVM(void);
 void Init_vm_objects(void);
-VALUE rb_vm_top_self(void);
+PUREFUNC(VALUE rb_vm_top_self(void););
 void rb_thread_recycle_stack_release(VALUE *);
 void rb_vm_change_state(void);
 void rb_vm_inc_const_missing_count(void);
@@ -1465,6 +1466,8 @@ int rb_vm_add_root_module(ID id, VALUE module);
 void rb_vm_check_redefinition_by_prepend(VALUE klass);
 VALUE rb_yield_refine_block(VALUE refinement, VALUE refinements);
 VALUE ruby_vm_sysstack_error_copy(void);
+PUREFUNC(st_table *rb_vm_fstring_table(void));
+
 
 /* vm_dump.c */
 void rb_print_backtrace(void);
diff --git a/process.c b/process.c
index 980d78fda0..1147205ebd 100644
--- a/process.c
+++ b/process.c
@@ -6921,6 +6921,7 @@ typedef long timetick_int_t;
 #define TIMETICK_INT2NUM(v) LONG2NUM(v)
 #endif
 
+CONSTFUNC(static timetick_int_t gcd_timetick_int(timetick_int_t, timetick_int_t));
 static timetick_int_t
 gcd_timetick_int(timetick_int_t a, timetick_int_t b)
 {
diff --git a/regenc.h b/regenc.h
index 273d1d3318..61138005c3 100644
--- a/regenc.h
+++ b/regenc.h
@@ -129,30 +129,30 @@ ONIG_EXTERN int onigenc_ascii_apply_all_case_fold P_((OnigCaseFoldType flag, Oni
 ONIG_EXTERN int onigenc_ascii_get_case_fold_codes_by_str P_((OnigCaseFoldType flag, const OnigUChar* p, const OnigUChar* end, OnigCaseFoldCodeItem items[], OnigEncoding enc));
 ONIG_EXTERN int onigenc_apply_all_case_fold_with_map P_((int map_size, const OnigPairCaseFoldCodes map[], int ess_tsett_flag, OnigCaseFoldType flag, OnigApplyAllCaseFoldFunc f, void* arg));
 ONIG_EXTERN int onigenc_get_case_fold_codes_by_str_with_map P_((int map_size, const OnigPairCaseFoldCodes map[], int ess_tsett_flag, OnigCaseFoldType flag, const OnigUChar* p, const OnigUChar* end, OnigCaseFoldCodeItem items[]));
-ONIG_EXTERN int onigenc_not_support_get_ctype_code_range P_((OnigCtype ctype, OnigCodePoint* sb_out, const OnigCodePoint* ranges[], OnigEncoding enc));
-ONIG_EXTERN int onigenc_is_mbc_newline_0x0a P_((const UChar* p, const UChar* end, OnigEncoding enc));
+CONSTFUNC(ONIG_EXTERN int onigenc_not_support_get_ctype_code_range P_((OnigCtype ctype, OnigCodePoint* sb_out, const OnigCodePoint* ranges[], OnigEncoding enc)));
+PUREFUNC(ONIG_EXTERN int onigenc_is_mbc_newline_0x0a P_((const UChar* p, const UChar* end, OnigEncoding enc)));
 
 
 /* methods for single byte encoding */
 ONIG_EXTERN int onigenc_ascii_mbc_case_fold P_((OnigCaseFoldType flag, const UChar** p, const UChar* end, UChar* lower, OnigEncoding enc));
-ONIG_EXTERN int onigenc_single_byte_mbc_enc_len P_((const UChar* p, const UChar* e, OnigEncoding enc));
-ONIG_EXTERN OnigCodePoint onigenc_single_byte_mbc_to_code P_((const UChar* p, const UChar* end, OnigEncoding enc));
-ONIG_EXTERN int onigenc_single_byte_code_to_mbclen P_((OnigCodePoint code, OnigEncoding enc));
+CONSTFUNC(ONIG_EXTERN int onigenc_single_byte_mbc_enc_len P_((const UChar* p, const UChar* e, OnigEncoding enc)));
+PUREFUNC(ONIG_EXTERN OnigCodePoint onigenc_single_byte_mbc_to_code P_((const UChar* p, const UChar* end, OnigEncoding enc)));
+CONSTFUNC(ONIG_EXTERN int onigenc_single_byte_code_to_mbclen P_((OnigCodePoint code, OnigEncoding enc)));
 ONIG_EXTERN int onigenc_single_byte_code_to_mbc P_((OnigCodePoint code, UChar *buf, OnigEncoding enc));
-ONIG_EXTERN UChar* onigenc_single_byte_left_adjust_char_head P_((const UChar* start, const UChar* s, const OnigUChar* end, OnigEncoding enc));
-ONIG_EXTERN int onigenc_always_true_is_allowed_reverse_match P_((const UChar* s, const UChar* end, OnigEncoding enc));
-ONIG_EXTERN int onigenc_always_false_is_allowed_reverse_match P_((const UChar* s, const UChar* end, OnigEncoding enc));
-ONIG_EXTERN int onigenc_ascii_is_code_ctype P_((OnigCodePoint code, unsigned int ctype, OnigEncoding enc));
+CONSTFUNC(ONIG_EXTERN UChar* onigenc_single_byte_left_adjust_char_head P_((const UChar* start, const UChar* s, const OnigUChar* end, OnigEncoding enc)));
+CONSTFUNC(ONIG_EXTERN int onigenc_always_true_is_allowed_reverse_match P_((const UChar* s, const UChar* end, OnigEncoding enc)));
+CONSTFUNC(ONIG_EXTERN int onigenc_always_false_is_allowed_reverse_match P_((const UChar* s, const UChar* end, OnigEncoding enc)));
+CONSTFUNC(ONIG_EXTERN int onigenc_ascii_is_code_ctype P_((OnigCodePoint code, unsigned int ctype, OnigEncoding enc)));
 
 /* methods for multi byte encoding */
 ONIG_EXTERN OnigCodePoint onigenc_mbn_mbc_to_code P_((OnigEncoding enc, const UChar* p, const UChar* end));
 ONIG_EXTERN int onigenc_mbn_mbc_case_fold P_((OnigEncoding enc, OnigCaseFoldType flag, const UChar** p, const UChar* end, UChar* lower));
-ONIG_EXTERN int onigenc_mb2_code_to_mbclen P_((OnigCodePoint code, OnigEncoding enc));
+CONSTFUNC(ONIG_EXTERN int onigenc_mb2_code_to_mbclen P_((OnigCodePoint code, OnigEncoding enc)));
 ONIG_EXTERN int onigenc_mb2_code_to_mbc P_((OnigEncoding enc, OnigCodePoint code, UChar *buf));
 ONIG_EXTERN int onigenc_minimum_property_name_to_ctype P_((OnigEncoding enc, const UChar* p, const UChar* end));
 ONIG_EXTERN int onigenc_unicode_property_name_to_ctype P_((OnigEncoding enc, const UChar* p, const UChar* end));
 ONIG_EXTERN int onigenc_mb2_is_code_ctype P_((OnigEncoding enc, OnigCodePoint code, unsigned int ctype));
-ONIG_EXTERN int onigenc_mb4_code_to_mbclen P_((OnigCodePoint code, OnigEncoding enc));
+CONSTFUNC(ONIG_EXTERN int onigenc_mb4_code_to_mbclen P_((OnigCodePoint code, OnigEncoding enc)));
 ONIG_EXTERN int onigenc_mb4_code_to_mbc P_((OnigEncoding enc, OnigCodePoint code, UChar *buf));
 ONIG_EXTERN int onigenc_mb4_is_code_ctype P_((OnigEncoding enc, OnigCodePoint code, unsigned int ctype));
 
diff --git a/st.c b/st.c
index 52a672d408..07b57d906e 100644
--- a/st.c
+++ b/st.c
@@ -1683,6 +1683,7 @@ st_locale_insensitive_strncasecmp(const char *s1, const char *s2, size_t n)
     return 0;
 }
 
+PUREFUNC(static st_index_t strcasehash(st_data_t));
 static st_index_t
 strcasehash(st_data_t arg)
 {
diff --git a/string.c b/string.c
index a7502b4166..5c09465196 100644
--- a/string.c
+++ b/string.c
@@ -233,8 +233,6 @@ static int fstring_cmp(VALUE a, VALUE b);
 
 static VALUE register_fstring(VALUE str);
 
-st_table *rb_vm_fstring_table(void);
-
 const struct st_hash_type rb_fstring_hash_type = {
     fstring_cmp,
     rb_str_hash,
diff --git a/vm.c b/vm.c
index edc3f20602..907eddc774 100644
--- a/vm.c
+++ b/vm.c
@@ -25,6 +25,7 @@
 
 VALUE rb_str_concat_literals(size_t, const VALUE*);
 
+PUREFUNC(static inline VALUE *VM_EP_LEP(VALUE *));
 static inline VALUE *
 VM_EP_LEP(VALUE *ep)
 {
@@ -60,6 +61,7 @@ rb_vm_ep_local_ep(VALUE *ep)
     return VM_EP_LEP(ep);
 }
 
+PUREFUNC(static inline VALUE *VM_CF_LEP(const rb_control_frame_t * const cfp));
 static inline VALUE *
 VM_CF_LEP(const rb_control_frame_t * const cfp)
 {
@@ -72,6 +74,7 @@ VM_CF_PREV_EP(const rb_control_frame_t * const cfp)
     return VM_EP_PREV_EP(cfp->ep);
 }
 
+PUREFUNC(static inline rb_block_t *VM_CF_BLOCK_PTR(const rb_control_frame_t * const cfp));
 static inline rb_block_t *
 VM_CF_BLOCK_PTR(const rb_control_frame_t * const cfp)
 {
diff --git a/vm_eval.c b/vm_eval.c
index 93dbfb72ca..f1ecd78a90 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -303,10 +303,8 @@ rb_current_receiver(void)
 }
 
 static inline void
-stack_check(void)
+stack_check(rb_thread_t *th)
 {
-    rb_thread_t *th = GET_THREAD();
-
     if (!rb_thread_raised_p(th, RAISED_STACKOVERFLOW) && ruby_stack_check()) {
 	rb_thread_raised_set(th, RAISED_STACKOVERFLOW);
 	rb_exc_raise(sysstack_error);
@@ -342,7 +340,7 @@ rb_call0(VALUE recv, ID mid, int argc, const VALUE *argv,
     if (call_status != MISSING_NONE) {
 	return method_missing(recv, mid, argc, argv, call_status);
     }
-    stack_check();
+    stack_check(th);
     return vm_call0(th, recv, mid, argc, argv, me);
 }
 
@@ -460,7 +458,7 @@ rb_check_funcall_default(VALUE recv, ID mid, int argc, const VALUE *argv, VALUE
 	return check_funcall_missing(th, klass, recv, mid, argc, argv,
 				     respond, def);
     }
-    stack_check();
+    stack_check(th);
     return vm_call0(th, recv, mid, argc, argv, me);
 }
 
@@ -485,7 +483,7 @@ rb_check_funcall_with_hook(VALUE recv, ID mid, int argc, const VALUE *argv,
 	(*hook)(ret != Qundef, recv, mid, argc, argv, arg);
 	return ret;
     }
-    stack_check();
+    stack_check(th);
     (*hook)(TRUE, recv, mid, argc, argv, arg);
     return vm_call0(th, recv, mid, argc, argv, me);
 }
@@ -718,7 +716,7 @@ raise_method_missing(rb_thread_t *th, int argc, const VALUE *argv, VALUE obj,
 		 rb_obj_class(argv[0]));
     }
 
-    stack_check();
+    stack_check(th);
 
     if (last_call_status & MISSING_PRIVATE) {
 	format = rb_fstring_cstr("private method `%s' called for %s%s%s");
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 9359e2726c..8655b85680 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -374,6 +374,7 @@ vm_getspecial(rb_thread_t *th, VALUE *lep, rb_num_t key, rb_num_t type)
     return val;
 }
 
+PUREFUNC(static rb_callable_method_entry_t *check_method_entry(VALUE obj, int can_be_svar));
 static rb_callable_method_entry_t *
 check_method_entry(VALUE obj, int can_be_svar)
 {
@@ -425,6 +426,9 @@ method_entry_cref(rb_callable_method_entry_t *me)
     }
 }
 
+#if VM_CHECK_MODE == 0
+PUREFUNC(static rb_cref_t *check_cref(VALUE, int));
+#endif
 static rb_cref_t *
 check_cref(VALUE obj, int can_be_svar)
 {
@@ -1925,6 +1929,7 @@ find_refinement(VALUE refinements, VALUE klass)
     return rb_hash_lookup(refinements, klass);
 }
 
+PUREFUNC(static rb_control_frame_t * current_method_entry(rb_thread_t *th, rb_control_frame_t *cfp));
 static rb_control_frame_t *
 current_method_entry(rb_thread_t *th, rb_control_frame_t *cfp)
 {