Update upstream source from tag 'upstream/6.9.6'

Update to upstream version '6.9.6'
with Debian dir 111ba939e0875272a460014bdcf030d413ce8f3f

29 files changed, 1106 insertions, 535 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 36c2222..44a4167 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -11,10 +11,15 @@ posix_headers = onigposix.h
 if ENABLE_POSIX_API
 posix_sources = regposix.c regposerr.c
 include_HEADERS += $(posix_headers)
+AM_CFLAGS += -DUSE_POSIX_API
 else
 posix_sources =
 endif
 
+if ENABLE_BINARY_COMPATIBLE_POSIX_API
+AM_CFLAGS += -DUSE_BINARY_COMPATIBLE_POSIX_API
+endif
+
 
 lib_LTLIBRARIES = $(libname)
 
@@ -45,13 +50,29 @@ libonig_la_SOURCES = regint.h regparse.h regenc.h st.h \
 	gb18030.c koi8_r.c cp1251.c \
 	onig_init.c
 
-libonig_la_LDFLAGS = -version-info $(LTVERSION)
-
 EXTRA_DIST = koi8.c mktable.c \
 	unicode_fold_data.c unicode_property_data.c \
 	unicode_property_data_posix.c \
 	unicode_egcb_data.c unicode_wb_data.c
 
+
+libonig_la_LDFLAGS = $(EXTRA_LIBONIG_LDFLAGS) -version-info $(LTVERSION)
+
+if USE_LIBONIG_DEF_FILE
+
+libonig_la_LDFLAGS +=  -Wl,--output-def,$(LIBONIG_DEF_FILE)
+
+install-data-hook:
+	echo "$(LIBTOOL) $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=install $(INSTALL_DATA) $(LIBONIG_DEF_FILE) $(DESTDIR)$(libdir)"; \
+	$(LIBTOOL) $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=install $(INSTALL_DATA) $(LIBONIG_DEF_FILE) $(DESTDIR)$(libdir) || exit 1
+
+uninstall-hook:
+	echo " $(LIBTOOL) $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=uninstall rm -f '$(DESTDIR)$(libdir)/$(LIBONIG_DEF_FILE)'"; \
+	$(LIBTOOL) $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=uninstall rm -f "$(DESTDIR)$(libdir)/$(LIBONIG_DEF_FILE)"
+
+endif
+
+
 dll:
 	$(CXX) -shared -Wl,--output-def,libonig.def -o libonig.dll *.o \
 	$(LIBS)
diff --git a/src/Makefile.windows b/src/Makefile.windows
index 90ebf28..11d6fd8 100644
--- a/src/Makefile.windows
+++ b/src/Makefile.windows
@@ -18,7 +18,7 @@ LINKFLAGS = -link -incremental:no -pdb:none
 INSTALL = install -c
 CP      = copy
 CC = cl
-DEFS = -DHAVE_CONFIG_H
+DEFS = -DHAVE_CONFIG_H -DUSE_POSIX_API -DUSE_BINARY_COMPATIBLE_POSIX_API
 
 subdirs =
 
diff --git a/src/big5.c b/src/big5.c
index 79ae1e3..faff845 100644
--- a/src/big5.c
+++ b/src/big5.c
@@ -2,7 +2,7 @@
   big5.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -58,8 +58,15 @@ static int
 big5_code_to_mbclen(OnigCodePoint code)
 {
   if ((code & (~0xffff)) != 0) return ONIGERR_INVALID_CODE_POINT_VALUE;
-  if ((code &    0xff00) != 0) return 2;
-  if (EncLen_BIG5[(int )(code & 0xff)] == 1) return 1;
+
+  if ((code & 0xff00) != 0) {
+    if (EncLen_BIG5[(int )(code >> 8) & 0xff] == 2)
+      return 2;
+  }
+  else {
+    if (EncLen_BIG5[(int )(code & 0xff)] == 1)
+      return 1;
+  }
 
   return ONIGERR_INVALID_CODE_POINT_VALUE;
 }
diff --git a/src/config.h.cmake.in b/src/config.h.cmake.in
index 60db86c..c213a09 100644
--- a/src/config.h.cmake.in
+++ b/src/config.h.cmake.in
@@ -43,6 +43,12 @@
 /* The size of `long', as computed by sizeof. */
 #cmakedefine SIZEOF_LONG  ${SIZEOF_LONG}
 
+/* The size of `long long', as computed by sizeof. */
+#cmakedefine SIZEOF_LONG_LONG  ${SIZEOF_LONG_LONG}
+
+/* The size of `void*', as computed by sizeof. */
+#cmakedefine SIZEOF_VOIDP  ${SIZEOF_VOIDP}
+
 /* Define if enable CR+NL as line terminator */
 #cmakedefine USE_CRNL_AS_LINE_TERMINATOR  ${USE_CRNL_AS_LINE_TERMINATOR}
 
diff --git a/src/euc_jp.c b/src/euc_jp.c
index 640b3e3..bfe91bf 100644
--- a/src/euc_jp.c
+++ b/src/euc_jp.c
@@ -2,7 +2,7 @@
   euc_jp.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -114,10 +114,20 @@ static int
 code_to_mbclen(OnigCodePoint code)
 {
   if (ONIGENC_IS_CODE_ASCII(code)) return 1;
-  else if ((code & 0xff0000) != 0) return 3;
-  else if ((code &   0xff00) != 0) return 2;
-  else
-    return ONIGERR_INVALID_CODE_POINT_VALUE;
+  else if ((code & 0xff0000) != 0) {
+    if (EncLen_EUCJP[(int )(code >> 16) & 0xff] == 3)
+      return 3;
+  }
+  else if ((code & 0xff00) != 0) {
+    if (EncLen_EUCJP[(int )(code >> 8) & 0xff] == 2)
+      return 2;
+  }
+  else if (code < 256) {
+    if (EncLen_EUCJP[(int )(code & 0xff)] == 1)
+      return 1;
+  }
+
+  return ONIGERR_INVALID_CODE_POINT_VALUE;
 }
 
 static int
@@ -125,8 +135,13 @@ code_to_mbc(OnigCodePoint code, UChar *buf)
 {
   UChar *p = buf;
 
-  if ((code & 0xff0000) != 0) *p++ = (UChar )(((code >> 16) & 0xff));
-  if ((code &   0xff00) != 0) *p++ = (UChar )(((code >>  8) & 0xff));
+  if ((code & 0xff0000) != 0) {
+    *p++ = (UChar )(((code >> 16) & 0xff));
+    *p++ = (UChar )(((code >>  8) & 0xff));
+  }
+  else if ((code & 0xff00) != 0)
+    *p++ = (UChar )(((code >>  8) & 0xff));
+
   *p++ = (UChar )(code & 0xff);
 
 #if 1
diff --git a/src/euc_kr.c b/src/euc_kr.c
index 7fa50af..b0e9fbf 100644
--- a/src/euc_kr.c
+++ b/src/euc_kr.c
@@ -2,7 +2,7 @@
   euc_kr.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -58,8 +58,15 @@ static int
 euckr_code_to_mbclen(OnigCodePoint code)
 {
   if ((code & (~0xffff)) != 0) return ONIGERR_INVALID_CODE_POINT_VALUE;
-  if ((code &    0xff00) != 0) return 2;
-  if (EncLen_EUCKR[(int )(code & 0xff)] == 1) return 1;
+
+  if ((code & 0xff00) != 0) {
+    if (EncLen_EUCKR[(int )(code >> 8) & 0xff] == 2)
+      return 2;
+  }
+  else {
+    if (EncLen_EUCKR[(int )(code & 0xff)] == 1)
+      return 1;
+  }
 
   return ONIGERR_INVALID_CODE_POINT_VALUE;
 }
diff --git a/src/euc_tw.c b/src/euc_tw.c
index 8e72b97..99dc5ec 100644
--- a/src/euc_tw.c
+++ b/src/euc_tw.c
@@ -2,7 +2,7 @@
   euc_tw.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -57,15 +57,22 @@ euctw_mbc_enc_len(const UChar* p)
 static int
 euctw_code_to_mbclen(OnigCodePoint code)
 {
-       if ((code & 0xff000000) != 0) return 4;
-  else if ((code &   0xff0000) != 0) return ONIGERR_INVALID_CODE_POINT_VALUE;
-  else if ((code &     0xff00) != 0) return 2;
+  if ((code & 0xff000000) != 0) {
+    if (EncLen_EUCTW[(int )(code >> 24) & 0xff] == 4)
+      return 4;
+  }
+  else if ((code & 0xff0000) != 0)
+    return ONIGERR_INVALID_CODE_POINT_VALUE;
+  else if ((code & 0xff00) != 0) {
+    if (EncLen_EUCTW[(int )(code >> 8) & 0xff] == 2)
+      return 2;
+  }
   else {
     if (EncLen_EUCTW[(int )(code & 0xff)] == 1)
       return 1;
-
-    return ONIGERR_INVALID_CODE_POINT_VALUE;
   }
+
+  return ONIGERR_INVALID_CODE_POINT_VALUE;
 }
 
 static int
diff --git a/src/gb18030.c b/src/gb18030.c
index 1385a7f..7409d3e 100644
--- a/src/gb18030.c
+++ b/src/gb18030.c
@@ -89,15 +89,25 @@ gb18030_mbc_enc_len(const UChar* p)
 static int
 gb18030_code_to_mbclen(OnigCodePoint code)
 {
-       if ((code & 0xff000000) != 0) return 4;
-  else if ((code &   0xff0000) != 0) return ONIGERR_INVALID_CODE_POINT_VALUE;
-  else if ((code &     0xff00) != 0) return 2;
+  if ((code & 0xff000000) != 0) {
+    if (GB18030_MAP[(int )(code >> 24) & 0xff] == CM)
+      if (GB18030_MAP[(int )(code >> 16) & 0xff] == C4)
+        return 4;
+  }
+  else if ((code & 0xff0000) != 0) return ONIGERR_INVALID_CODE_POINT_VALUE;
+  else if ((code & 0xff00) != 0) {
+    if (GB18030_MAP[(int )(code >> 8) & 0xff] == CM) {
+      char c = GB18030_MAP[(int )code & 0xff];
+      if (c == CM || c == C2)
+        return 2;
+    }
+  }
   else {
-    if (GB18030_MAP[(int )(code & 0xff)] == CM)
-      return ONIGERR_INVALID_CODE_POINT_VALUE;
-
-    return 1;
+    if (GB18030_MAP[(int )(code & 0xff)] != CM)
+      return 1;
   }
+
+  return ONIGERR_INVALID_CODE_POINT_VALUE;
 }
 
 static int
diff --git a/src/make_property.sh b/src/make_property.sh
index e5f1244..1c5e0f5 100755
--- a/src/make_property.sh
+++ b/src/make_property.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 GPERF=gperf
-SED=gsed
+SED=sed
 
 TMP1=gperf1.tmp
 TMP2=gperf2.tmp
diff --git a/src/make_unicode_property.sh b/src/make_unicode_property.sh
index 5129376..ff7dc62 100755
--- a/src/make_unicode_property.sh
+++ b/src/make_unicode_property.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 GPERF=gperf
-SED=gsed
+SED=sed
 
 NAME=unicode_property_data
 TMP1=gperf1.tmp
diff --git a/src/make_unicode_property_data.py b/src/make_unicode_property_data.py
index 285c462..d1b3377 100755
--- a/src/make_unicode_property_data.py
+++ b/src/make_unicode_property_data.py
@@ -1,7 +1,7 @@
 #!/usr/bin/python
 # -*- coding: utf-8 -*-
 # make_unicode_property_data.py
-# Copyright (c) 2016-2019  K.Kosako
+# Copyright (c) 2016-2020  K.Kosako
 
 import sys
 import re
@@ -405,7 +405,7 @@ def set_max_prop_name(name):
 def entry_prop_name(name, index):
   set_max_prop_name(name)
   if OUTPUT_LIST_MODE and index >= len(POSIX_LIST):
-    print >> UPF, "%3d: %s" % (index, name)
+    print >> UPF, "%s" % (name)
 
 def entry_and_print_prop_and_index(name, index):
   entry_prop_name(name, index)
diff --git a/src/onigposix.h b/src/onigposix.h
index 37e09ea..3514f80 100644
--- a/src/onigposix.h
+++ b/src/onigposix.h
@@ -74,19 +74,19 @@ extern "C" {
 #define REG_POSIX_ENCODING_UTF16_LE  5
 
 
-typedef int regoff_t;
+typedef int onig_posix_regoff_t;
 
 typedef struct {
-  regoff_t  rm_so;
-  regoff_t  rm_eo;
-} regmatch_t;
+  onig_posix_regoff_t  rm_so;
+  onig_posix_regoff_t  rm_eo;
+} onig_posix_regmatch_t;
 
 /* POSIX regex_t */
 typedef struct {
   void*   onig;          /* Oniguruma regex_t*  */
   size_t  re_nsub;
   int     comp_options;
-} regex_t;
+} onig_posix_regex_t;
 
 
 #ifndef P_
@@ -160,16 +160,31 @@ ONIG_EXTERN int onig_end P_((void));
 #endif /* ONIGURUMA_H */
 
 
-ONIG_EXTERN int    regcomp P_((regex_t* reg, const char* pat, int options));
-ONIG_EXTERN int    regexec P_((regex_t* reg, const char* str, size_t nmatch, regmatch_t* matches, int options));
-ONIG_EXTERN void   regfree P_((regex_t* reg));
-ONIG_EXTERN size_t regerror P_((int code, const regex_t* reg, char* buf, size_t size));
+ONIG_EXTERN int    onig_posix_regcomp P_((onig_posix_regex_t* reg, const char* pat, int options));
+ONIG_EXTERN int    onig_posix_regexec P_((onig_posix_regex_t* reg, const char* str, size_t nmatch, onig_posix_regmatch_t* matches, int options));
+ONIG_EXTERN void   onig_posix_regfree P_((onig_posix_regex_t* reg));
+ONIG_EXTERN size_t onig_posix_regerror P_((int code, const onig_posix_regex_t* reg, char* buf, size_t size));
 
 /* extended API */
-ONIG_EXTERN void reg_set_encoding P_((int enc));
-ONIG_EXTERN int  reg_name_to_group_numbers P_((regex_t* reg, const unsigned char* name, const unsigned char* name_end, int** nums));
-ONIG_EXTERN int  reg_foreach_name P_((regex_t* reg, int (*func)(const unsigned char*, const unsigned char*,int,int*,regex_t*,void*), void* arg));
-ONIG_EXTERN int  reg_number_of_names P_((regex_t* reg));
+ONIG_EXTERN void onig_posix_reg_set_encoding P_((int enc));
+ONIG_EXTERN int  onig_posix_reg_name_to_group_numbers P_((onig_posix_regex_t* reg, const unsigned char* name, const unsigned char* name_end, int** nums));
+ONIG_EXTERN int  onig_posix_reg_foreach_name P_((onig_posix_regex_t* reg, int (*func)(const unsigned char*, const unsigned char*,int,int*,onig_posix_regex_t*,void*), void* arg));
+ONIG_EXTERN int  onig_posix_reg_number_of_names P_((onig_posix_regex_t* reg));
+
+
+/* aliases */
+#define regex_t    onig_posix_regex_t
+#define regmatch_t onig_posix_regmatch_t
+#define regoff_t   onig_posix_regoff_t
+
+#define regcomp  onig_posix_regcomp
+#define regexec  onig_posix_regexec
+#define regfree  onig_posix_regfree
+#define regerror onig_posix_regerror
+#define reg_set_encoding          onig_posix_reg_set_encoding
+#define reg_name_to_group_numbers onig_posix_reg_name_to_group_numbers
+#define reg_foreach_name          onig_posix_reg_foreach_name
+#define reg_number_of_names       onig_posix_reg_number_of_names
 
 #ifdef __cplusplus
 }
diff --git a/src/oniguruma.h b/src/oniguruma.h
index 15f6ef0..d983fc9 100644
--- a/src/oniguruma.h
+++ b/src/oniguruma.h
@@ -36,9 +36,9 @@ extern "C" {
 #define ONIGURUMA
 #define ONIGURUMA_VERSION_MAJOR   6
 #define ONIGURUMA_VERSION_MINOR   9
-#define ONIGURUMA_VERSION_TEENY   5
+#define ONIGURUMA_VERSION_TEENY   6
 
-#define ONIGURUMA_VERSION_INT     60905
+#define ONIGURUMA_VERSION_INT     60906
 
 #ifndef P_
 #if defined(__STDC__) || defined(_WIN32)
@@ -395,8 +395,12 @@ typedef unsigned int        OnigOptionType;
 #define ONIG_OPTION_POSIX_IS_ASCII       (ONIG_OPTION_SPACE_IS_ASCII << 1)
 #define ONIG_OPTION_TEXT_SEGMENT_EXTENDED_GRAPHEME_CLUSTER  (ONIG_OPTION_POSIX_IS_ASCII << 1)
 #define ONIG_OPTION_TEXT_SEGMENT_WORD    (ONIG_OPTION_TEXT_SEGMENT_EXTENDED_GRAPHEME_CLUSTER << 1)
+/* options (search time) */
+#define ONIG_OPTION_NOT_BEGIN_STRING     (ONIG_OPTION_TEXT_SEGMENT_WORD << 1)
+#define ONIG_OPTION_NOT_END_STRING       (ONIG_OPTION_NOT_BEGIN_STRING << 1)
+#define ONIG_OPTION_NOT_BEGIN_POSITION   (ONIG_OPTION_NOT_END_STRING << 1)
 
-#define ONIG_OPTION_MAXBIT               ONIG_OPTION_TEXT_SEGMENT_WORD  /* limit */
+#define ONIG_OPTION_MAXBIT               ONIG_OPTION_NOT_BEGIN_POSITION
 
 #define ONIG_OPTION_ON(options,regopt)      ((options) |= (regopt))
 #define ONIG_OPTION_OFF(options,regopt)     ((options) &= ~(regopt))
@@ -561,6 +565,7 @@ ONIG_EXTERN OnigSyntaxType*   OnigDefaultSyntax;
 #define ONIGERR_PARSE_DEPTH_LIMIT_OVER                        -16
 #define ONIGERR_RETRY_LIMIT_IN_MATCH_OVER                     -17
 #define ONIGERR_RETRY_LIMIT_IN_SEARCH_OVER                    -18
+#define ONIGERR_SUBEXP_CALL_LIMIT_IN_SEARCH_OVER              -19
 #define ONIGERR_DEFAULT_ENCODING_IS_NOT_SETTED                -21
 #define ONIGERR_SPECIFIED_ENCODING_CANT_CONVERT_TO_WIDE_CHAR  -22
 #define ONIGERR_FAIL_TO_INITIALIZE                            -23
@@ -919,6 +924,10 @@ int onig_set_capture_num_limit P_((int num));
 ONIG_EXTERN
 int onig_set_parse_depth_limit P_((unsigned int depth));
 ONIG_EXTERN
+unsigned long onig_get_subexp_call_limit_in_search P_((void));
+ONIG_EXTERN
+int onig_set_subexp_call_limit_in_search P_((unsigned long n));
+ONIG_EXTERN
 int onig_get_subexp_call_max_nest_level P_((void));
 ONIG_EXTERN
 int onig_set_subexp_call_max_nest_level P_((int level));
diff --git a/src/regcomp.c b/src/regcomp.c
index 4d5b78f..dd2b328 100644
--- a/src/regcomp.c
+++ b/src/regcomp.c
@@ -133,6 +133,7 @@ ops_init(regex_t* reg, int init_alloc_size)
     size = sizeof(Operation) * init_alloc_size;
     p = (Operation* )xrealloc(reg->ops, size);
     CHECK_NULL_RETURN_MEMERR(p);
+    reg->ops = p;
 #ifdef USE_DIRECT_THREADED_CODE
     {
       enum OpCode* cp;
@@ -144,13 +145,12 @@ ops_init(regex_t* reg, int init_alloc_size)
 #endif
   }
   else {
-    p  = (Operation* )0;
+    reg->ops = (Operation* )0;
 #ifdef USE_DIRECT_THREADED_CODE
     reg->ocs = (enum OpCode* )0;
 #endif
   }
 
-  reg->ops = p;
   reg->ops_curr  = 0; /* !!! not yet done ops_new() */
   reg->ops_alloc = init_alloc_size;
   reg->ops_used  = 0;
@@ -176,6 +176,7 @@ ops_expand(regex_t* reg, int n)
   size = sizeof(Operation) * n;
   p = (Operation* )xrealloc(reg->ops, size);
   CHECK_NULL_RETURN_MEMERR(p);
+  reg->ops = p;
 
 #ifdef USE_DIRECT_THREADED_CODE
   size = sizeof(enum OpCode) * n;
@@ -184,7 +185,6 @@ ops_expand(regex_t* reg, int n)
   reg->ocs = cp;
 #endif
 
-  reg->ops = p;
   reg->ops_alloc = n;
   if (reg->ops_used == 0)
     reg->ops_curr = 0;
@@ -265,10 +265,12 @@ ops_free(regex_t* reg)
     case OP_BACKREF1: case OP_BACKREF2: case OP_BACKREF_N: case OP_BACKREF_N_IC:
       break;
     case OP_BACKREF_MULTI:      case OP_BACKREF_MULTI_IC:
+    case OP_BACKREF_CHECK:
+#ifdef USE_BACKREF_WITH_LEVEL
     case OP_BACKREF_WITH_LEVEL:
     case OP_BACKREF_WITH_LEVEL_IC:
-    case OP_BACKREF_CHECK:
     case OP_BACKREF_CHECK_WITH_LEVEL:
+#endif
       if (op->backref_general.num != 1)
         xfree(op->backref_general.ns);
       break;
@@ -631,7 +633,7 @@ mmcl_add(MinMaxCharLen* to, MinMaxCharLen* add)
   to->min = distance_add(to->min, add->min);
   to->max = distance_add(to->max, add->max);
 
-  to->min_is_sure = add->min_is_sure != 0 && to->min_is_sure != 0;
+  to->min_is_sure = add->min_is_sure != FALSE && to->min_is_sure != FALSE;
 }
 
 static void
@@ -656,8 +658,11 @@ static void
 mmcl_alt_merge(MinMaxCharLen* to, MinMaxCharLen* alt)
 {
   if (to->min > alt->min) {
-    to->min = alt->min;
-    if (alt->min_is_sure != 0)
+    to->min         = alt->min;
+    to->min_is_sure = alt->min_is_sure;
+  }
+  else if (to->min == alt->min) {
+    if (alt->min_is_sure != FALSE)
       to->min_is_sure = TRUE;
   }
 
@@ -840,7 +845,7 @@ node_char_len1(Node* node, regex_t* reg, MinMaxCharLen* ci, ScanEnv* env,
             en->min_char_len = ci->min;
             en->max_char_len = ci->max;
             NODE_STATUS_ADD(node, FIXED_CLEN);
-            if (ci->min_is_sure != 0)
+            if (ci->min_is_sure != FALSE)
               NODE_STATUS_ADD(node, FIXED_CLEN_MIN_SURE);
           }
         }
@@ -882,15 +887,15 @@ node_char_len1(Node* node, regex_t* reg, MinMaxCharLen* ci, ScanEnv* env,
     }
     break;
 
-  case NODE_ANCHOR:
+  case NODE_GIMMICK:
     mmcl_set(ci, 0);
-    /* can't optimize look-behind if anchor exists. */
-    ci->min_is_sure = FALSE;
     break;
 
-  case NODE_GIMMICK:
+  case NODE_ANCHOR:
   zero:
     mmcl_set(ci, 0);
+    /* can't optimize look-behind if anchor exists. */
+    ci->min_is_sure = FALSE;
     break;
 
   case NODE_BACKREF:
@@ -1082,6 +1087,9 @@ compile_call(CallNode* node, regex_t* reg, ScanEnv* env)
   if (r != 0) return r;
 
   COP(reg)->call.addr = 0; /* dummy addr. */
+#ifdef ONIG_DEBUG_MATCH_COUNTER
+  COP(reg)->call.called_mem = node->called_gnum;
+#endif
 
   offset = COP_CURR_OFFSET_BYTES(reg, call.addr);
   r = unset_addr_list_add(env->unset_addr_list, offset, NODE_CALL_BODY(node));
@@ -1822,7 +1830,6 @@ compile_bag_memory_node(BagNode* node, regex_t* reg, ScanEnv* env)
   COP(reg)->memory_end.num = node->m.regnum;
 
   if (NODE_IS_CALLED(node)) {
-    if (r != 0) return r;
     r = add_op(reg, OP_RETURN);
   }
 #else
@@ -2764,7 +2771,7 @@ compile_tree(Node* node, regex_t* reg, ScanEnv* env)
 static int
 make_named_capture_number_map(Node** plink, GroupNumMap* map, int* counter)
 {
-  int r = 0;
+  int r;
   Node* node = *plink;
 
   switch (NODE_TYPE(node)) {
@@ -2772,17 +2779,17 @@ make_named_capture_number_map(Node** plink, GroupNumMap* map, int* counter)
   case NODE_ALT:
     do {
       r = make_named_capture_number_map(&(NODE_CAR(node)), map, counter);
-    } while (r == 0 && IS_NOT_NULL(node = NODE_CDR(node)));
+    } while (r >= 0 && IS_NOT_NULL(node = NODE_CDR(node)));
+    if (r < 0) return r;
     break;
 
   case NODE_QUANT:
     {
       Node** ptarget = &(NODE_BODY(node));
-      Node*  old = *ptarget;
       r = make_named_capture_number_map(ptarget, map, counter);
-      if (r != 0) return r;
-      if (*ptarget != old && NODE_TYPE(*ptarget) == NODE_QUANT) {
-        r = onig_reduce_nested_quantifier(node);
+      if (r < 0) return r;
+      if (r == 1 && NODE_TYPE(*ptarget) == NODE_QUANT) {
+        return onig_reduce_nested_quantifier(node);
       }
     }
     break;
@@ -2796,41 +2803,48 @@ make_named_capture_number_map(Node** plink, GroupNumMap* map, int* counter)
           map[en->m.regnum].new_val = *counter;
           en->m.regnum = *counter;
           r = make_named_capture_number_map(&(NODE_BODY(node)), map, counter);
+          if (r < 0) return r;
         }
         else {
           *plink = NODE_BODY(node);
           NODE_BODY(node) = NULL_NODE;
           onig_node_free(node);
           r = make_named_capture_number_map(plink, map, counter);
+          if (r < 0) return r;
+          return 1;
         }
       }
       else if (en->type == BAG_IF_ELSE) {
         r = make_named_capture_number_map(&(NODE_BAG_BODY(en)), map, counter);
-        if (r != 0) return r;
+        if (r < 0) return r;
         if (IS_NOT_NULL(en->te.Then)) {
           r = make_named_capture_number_map(&(en->te.Then), map, counter);
-          if (r != 0) return r;
+          if (r < 0) return r;
         }
         if (IS_NOT_NULL(en->te.Else)) {
           r = make_named_capture_number_map(&(en->te.Else), map, counter);
-          if (r != 0) return r;
+          if (r < 0) return r;
         }
       }
-      else
+      else {
         r = make_named_capture_number_map(&(NODE_BODY(node)), map, counter);
+        if (r < 0) return r;
+      }
     }
     break;
 
   case NODE_ANCHOR:
-    if (IS_NOT_NULL(NODE_BODY(node)))
+    if (IS_NOT_NULL(NODE_BODY(node))) {
       r = make_named_capture_number_map(&(NODE_BODY(node)), map, counter);
+      if (r < 0) return r;
+    }
     break;
 
   default:
     break;
   }
 
-  return r;
+  return 0;
 }
 
 static int
@@ -2982,7 +2996,7 @@ disable_noname_group_capture(Node** root, regex_t* reg, ScanEnv* env)
   }
   counter = 0;
   r = make_named_capture_number_map(root, map, &counter);
-  if (r != 0) return r;
+  if (r < 0) return r;
 
   r = renumber_backref_traverse(*root, map);
   if (r != 0) return r;
@@ -3546,7 +3560,9 @@ check_node_in_look_behind(Node* node, int not, int* used)
       if (r != 0) break;
 
       if (en->type == BAG_MEMORY) {
-        if (NODE_IS_BACKREF(node) || NODE_IS_CALLED(node)) *used = TRUE;
+        if (NODE_IS_BACKREF(node) || NODE_IS_CALLED(node)
+         || NODE_IS_REFERENCED(node))
+          *used = TRUE;
       }
       else if (en->type == BAG_IF_ELSE) {
         if (IS_NOT_NULL(en->te.Then)) {
@@ -3978,6 +3994,7 @@ set_empty_repeat_node_trav(Node* node, Node* empty, ScanEnv* env)
     {
       BagNode* en = BAG_(node);
 
+      r = 0;
       if (en->type == BAG_MEMORY) {
         if (NODE_IS_BACKREF(node)) {
           if (IS_NOT_NULL(empty))
@@ -4484,7 +4501,7 @@ remove_from_list(Node* prev, Node* a)
 }
 
 static int
-reduce_string_list(Node* node)
+reduce_string_list(Node* node, OnigEncoding enc)
 {
   int r = 0;
 
@@ -4515,43 +4532,70 @@ reduce_string_list(Node* node)
           }
         }
         else {
-          prev = NULL_NODE;
+          if (IS_NOT_NULL(prev)) {
+#ifdef USE_CHECK_VALIDITY_OF_STRING_IN_TREE
+            StrNode* sn = STR_(prev);
+            if (! ONIGENC_IS_VALID_MBC_STRING(enc, sn->s, sn->end))
+              return ONIGERR_INVALID_WIDE_CHAR_VALUE;
+#endif
+            prev = NULL_NODE;
+          }
+          r = reduce_string_list(curr, enc);
+          if (r != 0) return r;
           prev_node = node;
         }
 
         node = next_node;
       } while (r == 0 && IS_NOT_NULL(node));
+
+#ifdef USE_CHECK_VALIDITY_OF_STRING_IN_TREE
+      if (IS_NOT_NULL(prev)) {
+        StrNode* sn = STR_(prev);
+        if (! ONIGENC_IS_VALID_MBC_STRING(enc, sn->s, sn->end))
+          return ONIGERR_INVALID_WIDE_CHAR_VALUE;
+      }
+#endif
     }
     break;
 
   case NODE_ALT:
     do {
-      r = reduce_string_list(NODE_CAR(node));
+      r = reduce_string_list(NODE_CAR(node), enc);
     } while (r == 0 && IS_NOT_NULL(node = NODE_CDR(node)));
     break;
 
+#ifdef USE_CHECK_VALIDITY_OF_STRING_IN_TREE
+  case NODE_STRING:
+    {
+      StrNode* sn = STR_(node);
+      if (! ONIGENC_IS_VALID_MBC_STRING(enc, sn->s, sn->end))
+        return ONIGERR_INVALID_WIDE_CHAR_VALUE;
+    }
+    break;
+#endif
+
   case NODE_ANCHOR:
     if (IS_NULL(NODE_BODY(node)))
       break;
     /* fall */
   case NODE_QUANT:
-    r = reduce_string_list(NODE_BODY(node));
+    r = reduce_string_list(NODE_BODY(node), enc);
     break;
 
   case NODE_BAG:
     {
       BagNode* en = BAG_(node);
 
-      r = reduce_string_list(NODE_BODY(node));
+      r = reduce_string_list(NODE_BODY(node), enc);
       if (r != 0) return r;
 
       if (en->type == BAG_IF_ELSE) {
         if (IS_NOT_NULL(en->te.Then)) {
-          r = reduce_string_list(en->te.Then);
+          r = reduce_string_list(en->te.Then, enc);
           if (r != 0) return r;
         }
         if (IS_NOT_NULL(en->te.Else)) {
-          r = reduce_string_list(en->te.Else);
+          r = reduce_string_list(en->te.Else, enc);
           if (r != 0) return r;
         }
       }
@@ -4723,7 +4767,7 @@ tune_look_behind(Node* node, regex_t* reg, int state, ScanEnv* env)
       return ONIGERR_INVALID_LOOK_BEHIND_PATTERN;
     }
 
-    if (ci.min == 0 && ci.min_is_sure != 0 && used == FALSE) {
+    if (ci.min == 0 && ci.min_is_sure != FALSE && used == FALSE) {
       if (an->type == ANCR_LOOK_BEHIND_NOT)
         r = onig_node_reset_fail(node);
       else
@@ -4779,18 +4823,23 @@ tune_look_behind(Node* node, regex_t* reg, int state, ScanEnv* env)
 static int
 tune_next(Node* node, Node* next_node, regex_t* reg)
 {
+  int called;
   NodeType type;
 
+  called = FALSE;
+
  retry:
   type = NODE_TYPE(node);
   if (type == NODE_QUANT) {
     QuantNode* qn = QUANT_(node);
     if (qn->greedy && IS_INFINITE_REPEAT(qn->upper)) {
 #ifdef USE_QUANT_PEEK_NEXT
-      Node* n = get_tree_head_literal(next_node, 1, reg);
-      /* '\0': for UTF-16BE etc... */
-      if (IS_NOT_NULL(n) && STR_(n)->s[0] != '\0') {
-        qn->next_head_exact = n;
+      if (called == FALSE) {
+        Node* n = get_tree_head_literal(next_node, 1, reg);
+        /* '\0': for UTF-16BE etc... */
+        if (IS_NOT_NULL(n) && STR_(n)->s[0] != '\0') {
+          qn->next_head_exact = n;
+        }
       }
 #endif
       /* automatic posseivation a*b ==> (?>a*)b */
@@ -4815,6 +4864,8 @@ tune_next(Node* node, Node* next_node, regex_t* reg)
   else if (type == NODE_BAG) {
     BagNode* en = BAG_(node);
     if (en->type == BAG_MEMORY) {
+      if (NODE_IS_CALLED(node))
+        called = TRUE;
       node = NODE_BODY(node);
       goto retry;
     }
@@ -4999,17 +5050,18 @@ unravel_cf_look_behind_add(Node** rlist, Node** rsn,
 {
   int r, i, found;
 
-  found = 0;
+  found = FALSE;
   for (i = 0; i < n; i++) {
     OnigCaseFoldCodeItem* item = items + i;
     if (item->byte_len == one_len) {
       if (item->code_len == 1) {
-        found = 1;
+        found = TRUE;
+        break;
       }
     }
   }
 
-  if (found == 0) {
+  if (found == FALSE) {
     r = unravel_cf_string_add(rlist, rsn, s, s + one_len, 0 /* flag */);
   }
   else {
@@ -5073,6 +5125,7 @@ unravel_case_fold_string(Node* node, regex_t* reg, int state)
     one_len = (OnigLen )enclen(enc, p);
     if (n == 0) {
       q = p + one_len;
+      if (q > end) q = end;
       r = unravel_cf_string_add(&list, &sn, p, q, 0 /* flag */);
       if (r != 0) goto err;
     }
@@ -5221,12 +5274,12 @@ quantifiers_memory_node_info(Node* node)
 __inline
 #endif
 static int
-tune_call_node_call(CallNode* cn, ScanEnv* env, int state)
+check_call_reference(CallNode* cn, ScanEnv* env, int state)
 {
   MemEnv* mem_env = SCANENV_MEMENV(env);
 
   if (cn->by_number != 0) {
-    int gnum = cn->group_num;
+    int gnum = cn->called_gnum;
 
     if (env->num_named > 0 &&
         IS_SYNTAX_BV(env->syntax, ONIG_SYN_CAPTURE_ONLY_NAMED_GROUP) &&
@@ -5241,12 +5294,14 @@ tune_call_node_call(CallNode* cn, ScanEnv* env, int state)
     }
 
   set_call_attr:
-    NODE_CALL_BODY(cn) = mem_env[cn->group_num].mem_node;
+    NODE_CALL_BODY(cn) = mem_env[cn->called_gnum].mem_node;
     if (IS_NULL(NODE_CALL_BODY(cn))) {
       onig_scan_env_set_error_string(env, ONIGERR_UNDEFINED_NAME_REFERENCE,
                                      cn->name, cn->name_end);
       return ONIGERR_UNDEFINED_NAME_REFERENCE;
     }
+
+    NODE_STATUS_ADD(NODE_CALL_BODY(cn), REFERENCED);
   }
   else {
     int *refs;
@@ -5263,7 +5318,7 @@ tune_call_node_call(CallNode* cn, ScanEnv* env, int state)
       return ONIGERR_MULTIPLEX_DEFINITION_NAME_CALL;
     }
     else {
-      cn->group_num = refs[0];
+      cn->called_gnum = refs[0];
       goto set_call_attr;
     }
   }
@@ -5396,7 +5451,7 @@ tune_call(Node* node, ScanEnv* env, int state)
       CALL_(node)->entry_count--;
     }
 
-    r = tune_call_node_call(CALL_(node), env, state);
+    r = check_call_reference(CALL_(node), env, state);
     break;
 
   default:
@@ -6187,8 +6242,10 @@ concat_opt_exact(OptStr* to, OptStr* add, OnigEncoding enc)
       r = 1; /* 1:full */
       break;
     }
-    for (j = 0; j < len && p < end; j++)
+    for (j = 0; j < len && p < end; j++) {
+      /* coverity[overrun-local] */
       to->s[i++] = *p++;
+    }
   }
 
   to->len = i;
@@ -6210,8 +6267,10 @@ concat_opt_exact_str(OptStr* to, UChar* s, UChar* end, OnigEncoding enc)
   for (i = to->len, p = s; p < end && i < OPT_EXACT_MAXLEN; ) {
     len = enclen(enc, p);
     if (i + len > OPT_EXACT_MAXLEN) break;
-    for (j = 0; j < len && p < end; j++)
+    for (j = 0; j < len && p < end; j++) {
+      /* coverity[overrun-local] */
       to->s[i++] = *p++;
+    }
   }
 
   to->len = i;
@@ -7229,19 +7288,10 @@ onig_compile(regex_t* reg, const UChar* pattern, const UChar* pattern_end,
   else
     reg->ops_used = 0;
 
-  reg->string_pool        = 0;
-  reg->string_pool_end    = 0;
-  reg->num_mem            = 0;
-  reg->num_repeat         = 0;
-  reg->num_empty_check    = 0;
-  reg->repeat_range_alloc = 0;
-  reg->repeat_range       = (RepeatRange* )NULL;
-  reg->empty_status_mem   = 0;
-
   r = onig_parse_tree(&root, pattern, pattern_end, reg, &scan_env);
   if (r != 0) goto err;
 
-  r = reduce_string_list(root);
+  r = reduce_string_list(root, reg->enc);
   if (r != 0) goto err;
 
   /* mixed use named group and no-named group */
@@ -7653,6 +7703,134 @@ onig_is_code_in_cc(OnigEncoding enc, OnigCodePoint code, CClassNode* cc)
   return onig_is_code_in_cc_len(len, code, cc);
 }
 
+typedef struct {
+  int prec_read;
+  int look_behind;
+  int backref_with_level;
+  int call;
+} SlowElementCount;
+
+static int
+node_detect_can_be_slow(Node* node, SlowElementCount* ct)
+{
+  int r;
+
+  r = 0;
+  switch (NODE_TYPE(node)) {
+  case NODE_LIST:
+  case NODE_ALT:
+    do {
+      r = node_detect_can_be_slow(NODE_CAR(node), ct);
+      if (r != 0) return r;
+    } while (IS_NOT_NULL(node = NODE_CDR(node)));
+    break;
+
+  case NODE_QUANT:
+    r = node_detect_can_be_slow(NODE_BODY(node), ct);
+    break;
+
+  case NODE_ANCHOR:
+    switch (ANCHOR_(node)->type) {
+    case ANCR_PREC_READ:
+    case ANCR_PREC_READ_NOT:
+      ct->prec_read++;
+      break;
+    case ANCR_LOOK_BEHIND:
+    case ANCR_LOOK_BEHIND_NOT:
+      ct->look_behind++;
+      break;
+    default:
+      break;
+    }
+
+    if (ANCHOR_HAS_BODY(ANCHOR_(node)))
+      r = node_detect_can_be_slow(NODE_BODY(node), ct);
+    break;
+
+  case NODE_BAG:
+    {
+      BagNode* en = BAG_(node);
+
+      r = node_detect_can_be_slow(NODE_BODY(node), ct);
+      if (r != 0) return r;
+
+      if (en->type == BAG_IF_ELSE) {
+        if (IS_NOT_NULL(en->te.Then)) {
+          r = node_detect_can_be_slow(en->te.Then, ct);
+          if (r != 0) return r;
+        }
+        if (IS_NOT_NULL(en->te.Else)) {
+          r = node_detect_can_be_slow(en->te.Else, ct);
+          if (r != 0) return r;
+        }
+      }
+    }
+    break;
+
+#ifdef USE_BACKREF_WITH_LEVEL
+  case NODE_BACKREF:
+    if (NODE_IS_NEST_LEVEL(node))
+      ct->backref_with_level++;
+    break;
+#endif
+
+#ifdef USE_CALL
+  case NODE_CALL:
+    ct->call++;
+    break;
+#endif
+
+  default:
+    break;
+  }
+
+  return r;
+}
+
+extern int
+onig_detect_can_be_slow_pattern(const UChar* pattern,
+  const UChar* pattern_end, OnigOptionType option, OnigEncoding enc,
+  OnigSyntaxType* syntax)
+{
+  int r;
+  regex_t* reg;
+  Node* root;
+  ScanEnv scan_env;
+  SlowElementCount count;
+
+  reg = (regex_t* )xmalloc(sizeof(regex_t));
+  if (IS_NULL(reg)) return ONIGERR_MEMORY;
+
+  r = onig_reg_init(reg, option, ONIGENC_CASE_FOLD_DEFAULT, enc, syntax);
+  if (r != 0) {
+    xfree(reg);
+    return r;
+  }
+
+  root = 0;
+  r = onig_parse_tree(&root, pattern, pattern_end, reg, &scan_env);
+  if (r == 0) {
+    count.prec_read          = 0;
+    count.look_behind        = 0;
+    count.backref_with_level = 0;
+    count.call               = 0;
+
+    r = node_detect_can_be_slow(root, &count);
+    if (r == 0) {
+      int n = count.prec_read + count.look_behind
+            + count.backref_with_level + count.call;
+      r = n;
+    }
+  }
+
+  if (IS_NOT_NULL(scan_env.mem_env_dynamic))
+    xfree(scan_env.mem_env_dynamic);
+
+  onig_node_free(root);
+  onig_free(reg);
+  return r;
+}
+
 
 #ifdef ONIG_DEBUG_PARSE
 
@@ -7734,14 +7912,18 @@ print_indent_tree(FILE* f, Node* node, int indent)
     break;
 
   case NODE_CCLASS:
+#define CCLASS_MBUF_MAX_OUTPUT_NUM   10
+
     fprintf(f, "<cclass:%p>", node);
     if (IS_NCCLASS_NOT(CCLASS_(node))) fputs(" not", f);
     if (CCLASS_(node)->mbuf) {
       BBuf* bbuf = CCLASS_(node)->mbuf;
-      for (i = 0; i < bbuf->used; i++) {
+      fprintf(f, " mbuf(%u) ", bbuf->used);
+      for (i = 0; i < bbuf->used && i < CCLASS_MBUF_MAX_OUTPUT_NUM; i++) {
         if (i > 0) fprintf(f, ",");
         fprintf(f, "%0x", bbuf->p[i]);
       }
+      if (i < bbuf->used) fprintf(f, "...");
     }
     break;
 
@@ -7822,6 +8004,11 @@ print_indent_tree(FILE* f, Node* node, int indent)
         if (i > 0) fputs(", ", f);
         fprintf(f, "%d", p[i]);
       }
+#ifdef USE_BACKREF_WITH_LEVEL
+      if (NODE_IS_NEST_LEVEL(node)) {
+        fprintf(f, ", level: %d", br->nest_level);
+      }
+#endif
     }
     break;
 
@@ -7830,6 +8017,7 @@ print_indent_tree(FILE* f, Node* node, int indent)
     {
       CallNode* cn = CALL_(node);
       fprintf(f, "<call:%p>", node);
+      fprintf(f, " num: %d, name", cn->called_gnum);
       p_string(f, cn->name_end - cn->name, cn->name);
     }
     break;
@@ -7881,6 +8069,8 @@ print_indent_tree(FILE* f, Node* node, int indent)
       fprintf(f, "memory:%d", BAG_(node)->m.regnum);
       if (NODE_IS_CALLED(node))
         fprintf(f, ", called");
+      else if (NODE_IS_REFERENCED(node))
+        fprintf(f, ", referenced");
       if (NODE_IS_FIXED_ADDR(node))
         fprintf(f, ", fixed-addr");
       break;
diff --git a/src/regenc.c b/src/regenc.c
index dbfbc89..27e4549 100644
--- a/src/regenc.c
+++ b/src/regenc.c
@@ -263,12 +263,12 @@ onigenc_strlen_null(OnigEncoding enc, const UChar* s)
 extern int
 onigenc_str_bytelen_null(OnigEncoding enc, const UChar* s)
 {
-  UChar* start = (UChar* )s;
-  UChar* p = (UChar* )s;
+  const UChar* start = s;
+  const UChar* p = s;
 
   while (1) {
     if (*p == '\0') {
-      UChar* q;
+      const UChar* q;
       int len = ONIGENC_MBC_MINLEN(enc);
 
       if (len == 1) return (int )(p - start);
diff --git a/src/regerror.c b/src/regerror.c
index 58bc7fd..dc1c8b6 100644
--- a/src/regerror.c
+++ b/src/regerror.c
@@ -56,6 +56,8 @@ onig_error_code_to_format(int code)
     p = "retry-limit-in-match over"; break;
   case ONIGERR_RETRY_LIMIT_IN_SEARCH_OVER:
     p = "retry-limit-in-search over"; break;
+  case ONIGERR_SUBEXP_CALL_LIMIT_IN_SEARCH_OVER:
+    p = "subexp-call-limit-in-search over"; break;
   case ONIGERR_TYPE_BUG:
     p = "undefined type (bug)"; break;
   case ONIGERR_PARSER_BUG:
diff --git a/src/regexec.c b/src/regexec.c
index 1b6895d..bb6b474 100644
--- a/src/regexec.c
+++ b/src/regexec.c
@@ -46,15 +46,15 @@
 
 #define CHECK_INTERRUPT_IN_MATCH
 
-#define STACK_MEM_START(reg, i) \
-  (MEM_STATUS_AT((reg)->push_mem_start, (i)) != 0 ? \
-   STACK_AT(mem_start_stk[i])->u.mem.pstr : (UChar* )((void* )(mem_start_stk[i])))
+#define STACK_MEM_START(reg, idx) \
+  (MEM_STATUS_AT((reg)->push_mem_start, (idx)) != 0 ? \
+   STACK_AT(mem_start_stk[idx].i)->u.mem.pstr : mem_start_stk[idx].s)
 
-#define STACK_MEM_END(reg, i) \
-  (MEM_STATUS_AT((reg)->push_mem_end, (i)) != 0 ? \
-   STACK_AT(mem_end_stk[i])->u.mem.pstr : (UChar* )((void* )(mem_end_stk[i])))
+#define STACK_MEM_END(reg, idx) \
+  (MEM_STATUS_AT((reg)->push_mem_end, (idx)) != 0 ? \
+   STACK_AT(mem_end_stk[idx].i)->u.mem.pstr : mem_end_stk[idx].s)
 
-static int forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start, UChar* range, UChar** low, UChar** high, UChar** low_prev);
+static int forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start, UChar* range, UChar** low, UChar** high);
 
 static int
 search_in_range(regex_t* reg, const UChar* str, const UChar* end, const UChar* start, const UChar* range, /* match range */ const UChar* data_range, /* subject string range */ OnigRegion* region, OnigOptionType option, OnigMatchParam* mp);
@@ -170,6 +170,9 @@ typedef struct {
   int    best_len;      /* for ONIG_OPTION_FIND_LONGEST */
   UChar* best_s;
 #endif
+#ifdef USE_CALL
+  unsigned long  subexp_call_in_search_counter;
+#endif
 } MatchArg;
 
 
@@ -1057,8 +1060,6 @@ onig_region_copy(OnigRegion* to, OnigRegion* from)
 
 
 /** stack **/
-#define INVALID_STACK_INDEX   -1
-
 #define STK_ALT_FLAG               0x0001
 
 /* stack type */
@@ -1099,7 +1100,15 @@ onig_region_copy(OnigRegion* to, OnigRegion* from)
 #define STK_MASK_TO_VOID_TARGET    0x100e
 #define STK_MASK_MEM_END_OR_MARK   0x8000  /* MEM_END or MEM_END_MARK */
 
-typedef intptr_t StackIndex;
+typedef ptrdiff_t StackIndex;
+
+#define INVALID_STACK_INDEX   ((StackIndex )-1)
+
+typedef union {
+  StackIndex i;
+  UChar*     s;
+} StkPtrType;
+
 
 typedef struct _StackType {
   unsigned int type;
@@ -1108,7 +1117,6 @@ typedef struct _StackType {
     struct {
       Operation* pcode;     /* byte code position */
       UChar*     pstr;      /* string position */
-      UChar*     pstr_prev; /* previous char position of pstr */
     } state;
     struct {
       int        count;
@@ -1119,8 +1127,8 @@ typedef struct _StackType {
     struct {
       UChar *pstr;       /* start/end position */
       /* Following information is set, if this stack type is MEM-START */
-      StackIndex prev_start;  /* prev. info (for backtrack  "(...)*" ) */
-      StackIndex prev_end;    /* prev. info (for backtrack  "(...)*" ) */
+      StkPtrType prev_start;  /* prev. info (for backtrack  "(...)*" ) */
+      StkPtrType prev_end;    /* prev. info (for backtrack  "(...)*" ) */
     } mem;
     struct {
       UChar *pstr;            /* start position */
@@ -1166,8 +1174,8 @@ struct OnigCalloutArgsStruct {
   MatchArg*   msa;
   StackType*  stk_base;
   StackType*  stk;
-  StackIndex* mem_start_stk;
-  StackIndex* mem_end_stk;
+  StkPtrType* mem_start_stk;
+  StkPtrType* mem_end_stk;
 };
 
 #endif
@@ -1178,7 +1186,7 @@ struct OnigCalloutArgsStruct {
 #define UPDATE_FOR_STACK_REALLOC do{\
   repeat_stk      = (StackIndex* )alloc_base;\
   empty_check_stk = (StackIndex* )(repeat_stk + reg->num_repeat);\
-  mem_start_stk   = (StackIndex* )(empty_check_stk + reg->num_empty_check);\
+  mem_start_stk   = (StkPtrType* )(empty_check_stk + reg->num_empty_check);\
   mem_end_stk     = mem_start_stk + num_mem + 1;\
 } while(0)
 
@@ -1194,7 +1202,7 @@ struct OnigCalloutArgsStruct {
 
 #define PTR_NUM_SIZE(reg)  (((reg)->num_mem + 1) * 2)
 #define UPDATE_FOR_STACK_REALLOC do{\
-  mem_start_stk = (StackIndex* )alloc_base;\
+  mem_start_stk = (StkPtrType* )alloc_base;\
   mem_end_stk   = mem_start_stk + num_mem + 1;\
 } while(0)
 
@@ -1218,8 +1226,12 @@ struct OnigCalloutArgsStruct {
 #endif
 
 #if defined(USE_CALL)
+#define SUBEXP_CALL_IN_MATCH_ARG_INIT(msa,mpv) \
+  (msa).subexp_call_in_search_counter = 0;
+
 #define POP_CALL  else if (stk->type == STK_RETURN) {subexp_call_nest_counter++;} else if (stk->type == STK_CALL_FRAME) {subexp_call_nest_counter--;}
 #else
+#define SUBEXP_CALL_IN_MATCH_ARG_INIT(msa,mpv)
 #define POP_CALL
 #endif
 
@@ -1231,6 +1243,7 @@ struct OnigCalloutArgsStruct {
   (msa).start    = (arg_start);\
   (msa).match_stack_limit  = (mpv)->match_stack_limit;\
   RETRY_IN_MATCH_ARG_INIT(msa,mpv)\
+  SUBEXP_CALL_IN_MATCH_ARG_INIT(msa,mpv)\
   (msa).mp = mpv;\
   (msa).best_len = ONIG_MISMATCH;\
   (msa).ptr_num  = PTR_NUM_SIZE(reg);\
@@ -1243,6 +1256,7 @@ struct OnigCalloutArgsStruct {
   (msa).start    = (arg_start);\
   (msa).match_stack_limit  = (mpv)->match_stack_limit;\
   RETRY_IN_MATCH_ARG_INIT(msa,mpv)\
+  SUBEXP_CALL_IN_MATCH_ARG_INIT(msa,mpv)\
   (msa).mp = mpv;\
   (msa).ptr_num  = PTR_NUM_SIZE(reg);\
 } while(0)
@@ -1258,27 +1272,27 @@ struct OnigCalloutArgsStruct {
     is_alloca  = 0;\
     alloc_base = msa->stack_p;\
     stk_base   = (StackType* )(alloc_base\
-                 + (sizeof(StackIndex) * msa->ptr_num));\
+                 + (sizeof(StkPtrType) * msa->ptr_num));\
     stk        = stk_base;\
     stk_end    = stk_base + msa->stack_n;\
   }\
   else if (msa->ptr_num > ALLOCA_PTR_NUM_LIMIT) {\
     is_alloca  = 0;\
-    alloc_base = (char* )xmalloc(sizeof(StackIndex) * msa->ptr_num\
+    alloc_base = (char* )xmalloc(sizeof(StkPtrType) * msa->ptr_num\
                   + sizeof(StackType) * (stack_num));\
     CHECK_NULL_RETURN_MEMERR(alloc_base);\
     stk_base   = (StackType* )(alloc_base\
-                 + (sizeof(StackIndex) * msa->ptr_num));\
+                 + (sizeof(StkPtrType) * msa->ptr_num));\
     stk        = stk_base;\
     stk_end    = stk_base + (stack_num);\
   }\
   else {\
     is_alloca  = 1;\
-    alloc_base = (char* )xalloca(sizeof(StackIndex) * msa->ptr_num\
+    alloc_base = (char* )xalloca(sizeof(StkPtrType) * msa->ptr_num\
                  + sizeof(StackType) * (stack_num));\
     CHECK_NULL_RETURN_MEMERR(alloc_base);\
     stk_base   = (StackType* )(alloc_base\
-                 + (sizeof(StackIndex) * msa->ptr_num));\
+                 + (sizeof(StkPtrType) * msa->ptr_num));\
     stk        = stk_base;\
     stk_end    = stk_base + (stack_num);\
   }\
@@ -1288,7 +1302,7 @@ struct OnigCalloutArgsStruct {
 #define STACK_SAVE(msa,is_alloca,alloc_base) do{\
   (msa)->stack_n = (int )(stk_end - stk_base);\
   if ((is_alloca) != 0) {\
-    size_t size = sizeof(StackIndex) * (msa)->ptr_num\
+    size_t size = sizeof(StkPtrType) * (msa)->ptr_num\
                 + sizeof(StackType) * (msa)->stack_n;\
     (msa)->stack_p = xmalloc(size);\
     CHECK_NULL_RETURN_MEMERR((msa)->stack_p);\
@@ -1373,6 +1387,24 @@ onig_set_retry_limit_in_search(unsigned long n)
 #endif
 }
 
+#ifdef USE_CALL
+static unsigned long SubexpCallLimitInSearch = DEFAULT_SUBEXP_CALL_LIMIT_IN_SEARCH;
+
+extern unsigned long
+onig_get_subexp_call_limit_in_search(void)
+{
+  return SubexpCallLimitInSearch;
+}
+
+extern int
+onig_set_subexp_call_limit_in_search(unsigned long n)
+{
+  SubexpCallLimitInSearch = n;
+  return 0;
+}
+
+#endif
+
 #ifdef USE_CALLOUT
 static OnigCalloutFunc DefaultProgressCallout;
 static OnigCalloutFunc DefaultRetractionCallout;
@@ -1637,9 +1669,9 @@ stack_double(int* is_alloca, char** arg_alloc_base,
   stk      = *arg_stk;
 
   n = (unsigned int )(stk_end - stk_base);
-  size = sizeof(StackIndex) * msa->ptr_num + sizeof(StackType) * n;
+  size = sizeof(StkPtrType) * msa->ptr_num + sizeof(StackType) * n;
   n *= 2;
-  new_size = sizeof(StackIndex) * msa->ptr_num + sizeof(StackType) * n;
+  new_size = sizeof(StkPtrType) * msa->ptr_num + sizeof(StackType) * n;
   if (*is_alloca != 0) {
     new_alloc_base = (char* )xmalloc(new_size);
     if (IS_NULL(new_alloc_base)) {
@@ -1669,7 +1701,7 @@ stack_double(int* is_alloca, char** arg_alloc_base,
   used = (int )(stk - stk_base);
   *arg_alloc_base = alloc_base;
   *arg_stk_base   = (StackType* )(alloc_base
-                                  + (sizeof(StackIndex) * msa->ptr_num));
+                                  + (sizeof(StkPtrType) * msa->ptr_num));
   *arg_stk      = *arg_stk_base + used;
   *arg_stk_end  = *arg_stk_base + n;
   return 0;
@@ -1694,22 +1726,20 @@ stack_double(int* is_alloca, char** arg_alloc_base,
 
 #define IS_TO_VOID_TARGET(stk) (((stk)->type & STK_MASK_TO_VOID_TARGET) != 0)
 
-#define STACK_PUSH(stack_type,pat,s,sprev) do {\
+#define STACK_PUSH(stack_type,pat,s) do {\
   STACK_ENSURE(1);\
   stk->type = (stack_type);\
   stk->u.state.pcode     = (pat);\
   stk->u.state.pstr      = (s);\
-  stk->u.state.pstr_prev = (sprev);\
   STACK_INC;\
 } while(0)
 
-#define STACK_PUSH_WITH_ZID(stack_type,pat,s,sprev,id) do {\
+#define STACK_PUSH_WITH_ZID(stack_type,pat,s,id) do {\
   STACK_ENSURE(1);\
   stk->type = (stack_type);\
   stk->zid  = (int )(id);\
   stk->u.state.pcode     = (pat);\
   stk->u.state.pstr      = (s);\
-  stk->u.state.pstr_prev = (sprev);\
   STACK_INC;\
 } while(0)
 
@@ -1724,7 +1754,6 @@ stack_double(int* is_alloca, char** arg_alloc_base,
   stk->type = (stack_type);\
   stk->u.state.pcode = (pat);\
   stk->u.state.pstr      = s;\
-  stk->u.state.pstr_prev = sprev;\
   STACK_INC;\
 } while (0)
 #else
@@ -1735,10 +1764,9 @@ stack_double(int* is_alloca, char** arg_alloc_base,
 } while (0)
 #endif
 
-#define STACK_PUSH_ALT(pat,s,sprev)       STACK_PUSH(STK_ALT,pat,s,sprev)
-#define STACK_PUSH_SUPER_ALT(pat,s,sprev) STACK_PUSH(STK_SUPER_ALT,pat,s,sprev)
-#define STACK_PUSH_ALT_WITH_ZID(pat,s,sprev,id) \
-  STACK_PUSH_WITH_ZID(STK_ALT,pat,s,sprev,id)
+#define STACK_PUSH_ALT(pat,s)       STACK_PUSH(STK_ALT,pat,s)
+#define STACK_PUSH_SUPER_ALT(pat,s) STACK_PUSH(STK_SUPER_ALT,pat,s)
+#define STACK_PUSH_ALT_WITH_ZID(pat,s,id) STACK_PUSH_WITH_ZID(STK_ALT,pat,s,id)
 
 #if 0
 #define STACK_PUSH_REPEAT(sid, pat) do {\
@@ -1767,8 +1795,8 @@ stack_double(int* is_alloca, char** arg_alloc_base,
   stk->u.mem.pstr       = (s);\
   stk->u.mem.prev_start = mem_start_stk[mnum];\
   stk->u.mem.prev_end   = mem_end_stk[mnum];\
-  mem_start_stk[mnum]   = GET_STACK_INDEX(stk);\
-  mem_end_stk[mnum]     = INVALID_STACK_INDEX;\
+  mem_start_stk[mnum].i = GET_STACK_INDEX(stk);\
+  mem_end_stk[mnum].i   = INVALID_STACK_INDEX;\
   STACK_INC;\
 } while(0)
 
@@ -1779,7 +1807,7 @@ stack_double(int* is_alloca, char** arg_alloc_base,
   stk->u.mem.pstr       = (s);\
   stk->u.mem.prev_start = mem_start_stk[mnum];\
   stk->u.mem.prev_end   = mem_end_stk[mnum];\
-  mem_end_stk[mnum] = GET_STACK_INDEX(stk);\
+  mem_end_stk[mnum].i   = GET_STACK_INDEX(stk);\
   STACK_INC;\
 } while(0)
 
@@ -1861,12 +1889,11 @@ stack_double(int* is_alloca, char** arg_alloc_base,
   STACK_INC;\
 } while(0)
 
-#define STACK_PUSH_MARK_WITH_POS(sid, s, sprev) do {\
+#define STACK_PUSH_MARK_WITH_POS(sid, s) do {\
   STACK_ENSURE(1);\
   stk->type = STK_MARK;\
   stk->zid  = (sid);\
   stk->u.val.v  = (UChar* )(s);\
-  stk->u.val.v2 = (sprev);\
   STACK_INC;\
 } while(0)
 
@@ -1885,7 +1912,6 @@ stack_double(int* is_alloca, char** arg_alloc_base,
   stk->zid  = (sid);\
   stk->u.val.type = (stype);\
   stk->u.val.v    = (UChar* )(sval);\
-  stk->u.val.v2   = sprev;\
   STACK_INC;\
 } while(0)
 
@@ -1932,7 +1958,6 @@ stack_double(int* is_alloca, char** arg_alloc_base,
         && k->zid == (sid)) {\
       if (level == 0) {\
         (sval) = k->u.val.v;\
-        sprev  = k->u.val.v2;\
         break;\
       }\
     }\
@@ -2135,14 +2160,14 @@ stack_double(int* is_alloca, char** arg_alloc_base,
 } while(0)
 
 #define STACK_MEM_START_GET_PREV_END_ADDR(k /* STK_MEM_START*/, reg, addr) do {\
-  if (k->u.mem.prev_end == INVALID_STACK_INDEX) {\
+  if (k->u.mem.prev_end.i == INVALID_STACK_INDEX) {\
     (addr) = 0;\
   }\
   else {\
     if (MEM_STATUS_AT((reg)->push_mem_end, k->zid))\
-      (addr) = STACK_AT(k->u.mem.prev_end)->u.mem.pstr;\
+      (addr) = STACK_AT(k->u.mem.prev_end.i)->u.mem.pstr;\
     else\
-      (addr) = (UChar* )k->u.mem.prev_end;\
+      (addr) = k->u.mem.prev_end.s;\
   }\
 } while (0)
 
@@ -2163,7 +2188,7 @@ stack_double(int* is_alloca, char** arg_alloc_base,
         if (endp == 0) {\
           (isnull) = 0; break;\
         }\
-        else if (STACK_AT(k->u.mem.prev_start)->u.mem.pstr != endp) {\
+        else if (STACK_AT(k->u.mem.prev_start.i)->u.mem.pstr != endp) {\
           (isnull) = 0; break;\
         }\
         else if (endp != s) {\
@@ -2199,7 +2224,7 @@ stack_double(int* is_alloca, char** arg_alloc_base,
                   if (endp == 0) {\
                     (isnull) = 0; break;\
                   }\
-                  else if (STACK_AT(k->u.mem.prev_start)->u.mem.pstr != endp) { \
+                  else if (STACK_AT(k->u.mem.prev_start.i)->u.mem.pstr != endp) { \
                     (isnull) = 0; break;\
                   }\
                   else if (endp != s) {\
@@ -2362,6 +2387,10 @@ static int string_cmp_ic(OnigEncoding enc, int case_fold_flag,
       p1++;
       p2++;
     }
+    if (s2 >= end2) {
+      if (s1 < end1) return 0;
+      else           break;
+    }
   }
 
   *ps2 = s2;
@@ -2390,7 +2419,7 @@ static int string_cmp_ic(OnigEncoding enc, int case_fold_flag,
 #define ON_STR_END(s)          ((s) == end)
 #define DATA_ENSURE_CHECK1     (s < right_range)
 #define DATA_ENSURE_CHECK(n)   (s + (n) <= right_range)
-#define DATA_ENSURE(n)         if (s + (n) > right_range) goto fail
+#define DATA_ENSURE(n)         if (right_range - s < (n)) goto fail
 
 #define INIT_RIGHT_RANGE    right_range = (UChar* )in_right_range
 
@@ -2632,9 +2661,9 @@ typedef struct {
 
 #define BYTECODE_INTERPRETER_START      GOTO_OP;
 #define BYTECODE_INTERPRETER_END
-#define CASE_OP(x)   L_##x: SOP_IN(OP_##x); sbegin = s; MATCH_DEBUG_OUT(0)
+#define CASE_OP(x)   L_##x: SOP_IN(OP_##x); MATCH_DEBUG_OUT(0)
 #define DEFAULT_OP   /* L_DEFAULT: */
-#define NEXT_OP      sprev = sbegin; JUMP_OP
+#define NEXT_OP      JUMP_OP
 #define JUMP_OP      GOTO_OP
 #ifdef USE_DIRECT_THREADED_CODE
 #define GOTO_OP      goto *(p->opaddr)
@@ -2648,9 +2677,8 @@ typedef struct {
 #define BYTECODE_INTERPRETER_START \
   while (1) {\
   MATCH_DEBUG_OUT(0)\
-  sbegin = s;\
   switch (p->opcode) {
-#define BYTECODE_INTERPRETER_END  } sprev = sbegin; }
+#define BYTECODE_INTERPRETER_END  } }
 #define CASE_OP(x)   case OP_##x: SOP_IN(OP_##x);
 #define DEFAULT_OP   default:
 #define NEXT_OP      break
@@ -2718,12 +2746,22 @@ typedef struct {
   best_len = err_code; goto match_at_end;\
 } while(0)
 
+#define MATCH_COUNTER_OUT(title) do {\
+  int i;\
+  fprintf(DBGFP, "%s (%ld): retry limit: %8lu, subexp_call: %8lu\n", (title), (sstart - str), retry_in_match_counter, msa->subexp_call_in_search_counter); \
+  fprintf(DBGFP, "      ");\
+  for (i = 0; i < MAX_SUBEXP_CALL_COUNTERS; i++) {\
+    fprintf(DBGFP, " %6lu", subexp_call_counters[i]);\
+  }\
+  fprintf(DBGFP, "\n");\
+  fflush(DBGFP);\
+} while (0)
+
 
 /* match data(str - end) from position (sstart). */
-/* if sstart == str then set sprev to NULL. */
 static int
 match_at(regex_t* reg, const UChar* str, const UChar* end,
-         const UChar* in_right_range, const UChar* sstart, UChar* sprev,
+         const UChar* in_right_range, const UChar* sstart,
          MatchArg* msa)
 {
 
@@ -2782,10 +2820,14 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   &&L_BACKREF_N_IC,
   &&L_BACKREF_MULTI,
   &&L_BACKREF_MULTI_IC,
+#ifdef USE_BACKREF_WITH_LEVEL
   &&L_BACKREF_WITH_LEVEL,
   &&L_BACKREF_WITH_LEVEL_IC,
+#endif
   &&L_BACKREF_CHECK,
+#ifdef USE_BACKREF_WITH_LEVEL
   &&L_BACKREF_CHECK_WITH_LEVEL,
+#endif
   &&L_MEM_START,
   &&L_MEM_START_PUSH,
   &&L_MEM_END_PUSH,
@@ -2838,13 +2880,13 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   LengthType tlen, tlen2;
   MemNumType mem;
   RelAddrType addr;
-  UChar *s, *ps, *sbegin;
+  UChar *s, *ps;
   UChar *right_range;
   int is_alloca;
   char *alloc_base;
   StackType *stk_base, *stk, *stk_end;
   StackType *stkp; /* used as any purpose. */
-  StackIndex *mem_start_stk, *mem_end_stk;
+  StkPtrType *mem_start_stk, *mem_end_stk;
   UChar* keep;
 
 #ifdef USE_REPEAT_AND_EMPTY_CHECK_LOCAL_VAR
@@ -2858,6 +2900,10 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 #ifdef USE_CALLOUT
   int of;
 #endif
+#ifdef ONIG_DEBUG_MATCH_COUNTER
+#define MAX_SUBEXP_CALL_COUNTERS  9
+  unsigned long subexp_call_counters[MAX_SUBEXP_CALL_COUNTERS];
+#endif
 
   Operation* p = reg->ops;
   OnigOptionType option = reg->options;
@@ -2872,6 +2918,12 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   static unsigned int counter = 1;
 #endif
 
+#ifdef ONIG_DEBUG_MATCH_COUNTER
+  for (i = 0; i < MAX_SUBEXP_CALL_COUNTERS; i++) {
+    subexp_call_counters[i] = 0;
+  }
+#endif
+
 #ifdef USE_DIRECT_THREADED_CODE
   if (IS_NULL(msa)) {
     for (i = 0; i < reg->ops_used; i++) {
@@ -2903,12 +2955,11 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   STACK_INIT(INIT_MATCH_STACK_SIZE);
   UPDATE_FOR_STACK_REALLOC;
   for (i = 1; i <= num_mem; i++) {
-    mem_start_stk[i] = mem_end_stk[i] = INVALID_STACK_INDEX;
+    mem_start_stk[i].i = mem_end_stk[i].i = INVALID_STACK_INDEX;
   }
 
 #ifdef ONIG_DEBUG_MATCH
-  fprintf(DBGFP, "match_at: str: %p, end: %p, start: %p, sprev: %p\n",
-          str, end, sstart, sprev);
+  fprintf(DBGFP, "match_at: str: %p, end: %p, start: %p\n", str, end, sstart);
   fprintf(DBGFP, "size: %d, start offset: %d\n",
           (int )(end - str), (int )(sstart - str));
 #endif
@@ -2932,24 +2983,27 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
           if (n > msa->best_len) {
             msa->best_len = n;
             msa->best_s   = (UChar* )sstart;
+            goto set_region;
           }
           else
             goto end_best_len;
         }
 #endif
         best_len = n;
+
+      set_region:
         region = msa->region;
         if (region) {
           if (keep > s) keep = s;
 
-#ifdef USE_POSIX_API_REGION_OPTION
+#ifdef USE_POSIX_API
           if (OPTON_POSIX_REGION(msa->options)) {
             posix_regmatch_t* rmt = (posix_regmatch_t* )region;
 
             rmt[0].rm_so = (regoff_t )(keep - str);
             rmt[0].rm_eo = (regoff_t )(s    - str);
             for (i = 1; i <= num_mem; i++) {
-              if (mem_end_stk[i] != INVALID_STACK_INDEX) {
+              if (mem_end_stk[i].i != INVALID_STACK_INDEX) {
                 rmt[i].rm_so = (regoff_t )(STACK_MEM_START(reg, i) - str);
                 rmt[i].rm_eo = (regoff_t )(STACK_MEM_END(reg, i)   - str);
               }
@@ -2959,11 +3013,11 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
             }
           }
           else {
-#endif /* USE_POSIX_API_REGION_OPTION */
+#endif /* USE_POSIX_API */
             region->beg[0] = (int )(keep - str);
             region->end[0] = (int )(s    - str);
             for (i = 1; i <= num_mem; i++) {
-              if (mem_end_stk[i] != INVALID_STACK_INDEX) {
+              if (mem_end_stk[i].i != INVALID_STACK_INDEX) {
                 region->beg[i] = (int )(STACK_MEM_START(reg, i) - str);
                 region->end[i] = (int )(STACK_MEM_END(reg, i)   - str);
               }
@@ -2996,7 +3050,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
               if (r < 0) MATCH_AT_ERROR_RETURN(r);
             }
 #endif /* USE_CAPTURE_HISTORY */
-#ifdef USE_POSIX_API_REGION_OPTION
+#ifdef USE_POSIX_API
           } /* else OPTON_POSIX_REGION() */
 #endif
         } /* if (region) */
@@ -3012,8 +3066,11 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
           best_len = ONIG_MISMATCH;
           goto fail; /* for retry */
         }
-        if (OPTON_FIND_LONGEST(option) && DATA_ENSURE_CHECK1) {
-          goto fail; /* for retry */
+        if (OPTON_FIND_LONGEST(option)) {
+          if (s >= in_right_range && msa->best_s == sstart)
+            best_len = msa->best_len;
+          else
+            goto fail; /* for retry */
         }
       }
 
@@ -3034,7 +3091,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       if (*ps != *s) goto fail;
       ps++; s++;
       if (*ps != *s) goto fail;
-      sprev = s;
       s++;
       INC_OP;
       JUMP_OUT;
@@ -3047,7 +3103,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       if (*ps != *s) goto fail;
       ps++; s++;
       if (*ps != *s) goto fail;
-      sprev = s;
       s++;
       INC_OP;
       JUMP_OUT;
@@ -3062,7 +3117,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       if (*ps != *s) goto fail;
       ps++; s++;
       if (*ps != *s) goto fail;
-      sprev = s;
       s++;
       INC_OP;
       JUMP_OUT;
@@ -3079,7 +3133,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       if (*ps != *s) goto fail;
       ps++; s++;
       if (*ps != *s) goto fail;
-      sprev = s;
       s++;
       INC_OP;
       JUMP_OUT;
@@ -3091,7 +3144,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       while (tlen-- > 0) {
         if (*ps++ != *s++) goto fail;
       }
-      sprev = s - 1;
       INC_OP;
       JUMP_OUT;
 
@@ -3112,7 +3164,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       ps++; s++;
       if (*ps != *s) goto fail;
       ps++; s++;
-      sprev = s;
       if (*ps != *s) goto fail;
       ps++; s++;
       if (*ps != *s) goto fail;
@@ -3131,7 +3182,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       ps++; s++;
       if (*ps != *s) goto fail;
       ps++; s++;
-      sprev = s;
       if (*ps != *s) goto fail;
       ps++; s++;
       if (*ps != *s) goto fail;
@@ -3149,7 +3199,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         if (*ps != *s) goto fail;
         ps++; s++;
       }
-      sprev = s - 2;
       INC_OP;
       JUMP_OUT;
 
@@ -3165,7 +3214,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         if (*ps != *s) goto fail;
         ps++; s++;
       }
-      sprev = s - 3;
       INC_OP;
       JUMP_OUT;
 
@@ -3179,7 +3227,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         if (*ps != *s) goto fail;
         ps++; s++;
       }
-      sprev = s - tlen;
       INC_OP;
       JUMP_OUT;
 
@@ -3295,11 +3342,10 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE_OP(ANYCHAR_STAR)
       INC_OP;
       while (DATA_ENSURE_CHECK1) {
-        STACK_PUSH_ALT(p, s, sprev);
+        STACK_PUSH_ALT(p, s);
         n = enclen(encode, s);
         DATA_ENSURE(n);
         if (ONIGENC_IS_MBC_NEWLINE(encode, s, end))  goto fail;
-        sprev = s;
         s += n;
       }
       JUMP_OUT;
@@ -3307,15 +3353,13 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE_OP(ANYCHAR_ML_STAR)
       INC_OP;
       while (DATA_ENSURE_CHECK1) {
-        STACK_PUSH_ALT(p, s, sprev);
+        STACK_PUSH_ALT(p, s);
         n = enclen(encode, s);
         if (n > 1) {
           DATA_ENSURE(n);
-          sprev = s;
           s += n;
         }
         else {
-          sprev = s;
           s++;
         }
       }
@@ -3329,12 +3373,11 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         INC_OP;
         while (DATA_ENSURE_CHECK1) {
           if (c == *s) {
-            STACK_PUSH_ALT(p, s, sprev);
+            STACK_PUSH_ALT(p, s);
           }
           n = enclen(encode, s);
           DATA_ENSURE(n);
           if (ONIGENC_IS_MBC_NEWLINE(encode, s, end))  goto fail;
-          sprev = s;
           s += n;
         }
       }
@@ -3348,16 +3391,14 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         INC_OP;
         while (DATA_ENSURE_CHECK1) {
           if (c == *s) {
-            STACK_PUSH_ALT(p, s, sprev);
+            STACK_PUSH_ALT(p, s);
           }
           n = enclen(encode, s);
           if (n > 1) {
             DATA_ENSURE(n);
-            sprev = s;
             s += n;
           }
           else {
-            sprev = s;
             s++;
           }
         }
@@ -3410,14 +3451,17 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
           if (! IS_MBC_WORD_ASCII_MODE(encode, s, end, mode))
             goto fail;
         }
-        else if (ON_STR_END(s)) {
-          if (! IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode))
-            goto fail;
-        }
         else {
-          if (IS_MBC_WORD_ASCII_MODE(encode, s, end, mode)
-              == IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode))
-            goto fail;
+          UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
+          if (ON_STR_END(s)) {
+            if (! IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode))
+              goto fail;
+          }
+          else {
+            if (IS_MBC_WORD_ASCII_MODE(encode, s, end, mode)
+                == IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode))
+              goto fail;
+          }
         }
       }
       INC_OP;
@@ -3432,14 +3476,17 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
           if (DATA_ENSURE_CHECK1 && IS_MBC_WORD_ASCII_MODE(encode, s, end, mode))
             goto fail;
         }
-        else if (ON_STR_END(s)) {
-          if (IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode))
-            goto fail;
-        }
         else {
-          if (IS_MBC_WORD_ASCII_MODE(encode, s, end, mode)
-              != IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode))
-            goto fail;
+          UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
+          if (ON_STR_END(s)) {
+            if (IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode))
+              goto fail;
+          }
+          else {
+            if (IS_MBC_WORD_ASCII_MODE(encode, s, end, mode)
+                != IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode))
+              goto fail;
+          }
         }
       }
       INC_OP;
@@ -3452,7 +3499,13 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
         mode = p->word_boundary.mode;
         if (DATA_ENSURE_CHECK1 && IS_MBC_WORD_ASCII_MODE(encode, s, end, mode)) {
-          if (ON_STR_BEGIN(s) || !IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode)) {
+          UChar* sprev;
+          if (ON_STR_BEGIN(s)) {
+            INC_OP;
+            JUMP_OUT;
+          }
+          sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
+          if (! IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode)) {
             INC_OP;
             JUMP_OUT;
           }
@@ -3465,10 +3518,13 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         ModeType mode;
 
         mode = p->word_boundary.mode;
-        if (!ON_STR_BEGIN(s) && IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode)) {
-          if (ON_STR_END(s) || ! IS_MBC_WORD_ASCII_MODE(encode, s, end, mode)) {
-            INC_OP;
-            JUMP_OUT;
+        if (! ON_STR_BEGIN(s)) {
+          UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
+          if (IS_MBC_WORD_ASCII_MODE(encode, sprev, end, mode)) {
+            if (ON_STR_END(s) || ! IS_MBC_WORD_ASCII_MODE(encode, s, end, mode)) {
+              INC_OP;
+              JUMP_OUT;
+            }
           }
         }
       }
@@ -3478,6 +3534,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE_OP(TEXT_SEGMENT_BOUNDARY)
       {
         int is_break;
+        UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
 
         switch (p->text_segment_boundary.type) {
         case EXTENDED_GRAPHEME_CLUSTER_BOUNDARY:
@@ -3507,12 +3564,16 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE_OP(BEGIN_BUF)
       if (! ON_STR_BEGIN(s)) goto fail;
+      if (OPTON_NOTBOL(msa->options)) goto fail;
+      if (OPTON_NOT_BEGIN_STRING(msa->options)) goto fail;
 
       INC_OP;
       JUMP_OUT;
 
     CASE_OP(END_BUF)
       if (! ON_STR_END(s)) goto fail;
+      if (OPTON_NOTEOL(msa->options)) goto fail;
+      if (OPTON_NOT_END_STRING(msa->options)) goto fail;
 
       INC_OP;
       JUMP_OUT;
@@ -3523,15 +3584,19 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         INC_OP;
         JUMP_OUT;
       }
-      else if (ONIGENC_IS_MBC_NEWLINE(encode, sprev, end) && !ON_STR_END(s)) {
-        INC_OP;
-        JUMP_OUT;
+      else if (! ON_STR_END(s)) {
+        UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
+        if (ONIGENC_IS_MBC_NEWLINE(encode, sprev, end)) {
+          INC_OP;
+          JUMP_OUT;
+        }
       }
       goto fail;
 
     CASE_OP(END_LINE)
       if (ON_STR_END(s)) {
 #ifndef USE_NEWLINE_AT_END_OF_STRING_HAS_EMPTY_LINE
+        UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
         if (IS_EMPTY_STR || !ONIGENC_IS_MBC_NEWLINE(encode, sprev, end)) {
 #endif
           if (OPTON_NOTEOL(msa->options)) goto fail;
@@ -3556,9 +3621,11 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE_OP(SEMI_END_BUF)
       if (ON_STR_END(s)) {
 #ifndef USE_NEWLINE_AT_END_OF_STRING_HAS_EMPTY_LINE
+        UChar* sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
         if (IS_EMPTY_STR || !ONIGENC_IS_MBC_NEWLINE(encode, sprev, end)) {
 #endif
           if (OPTON_NOTEOL(msa->options)) goto fail;
+          if (OPTON_NOT_END_STRING(msa->options)) goto fail;
           INC_OP;
           JUMP_OUT;
 #ifndef USE_NEWLINE_AT_END_OF_STRING_HAS_EMPTY_LINE
@@ -3567,6 +3634,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       }
       else if (ONIGENC_IS_MBC_NEWLINE(encode, s, end) &&
                ON_STR_END(s + enclen(encode, s))) {
+        if (OPTON_NOTEOL(msa->options)) goto fail;
+        if (OPTON_NOT_END_STRING(msa->options)) goto fail;
         INC_OP;
         JUMP_OUT;
       }
@@ -3575,6 +3644,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         UChar* ss = s + enclen(encode, s);
         ss += enclen(encode, ss);
         if (ON_STR_END(ss)) {
+          if (OPTON_NOTEOL(msa->options)) goto fail;
+          if (OPTON_NOT_END_STRING(msa->options)) goto fail;
           INC_OP;
           JUMP_OUT;
         }
@@ -3586,6 +3657,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       switch (p->check_position.type) {
       case CHECK_POSITION_SEARCH_START:
         if (s != msa->start) goto fail;
+        if (OPTON_NOT_BEGIN_POSITION(msa->options)) goto fail;
         break;
       case CHECK_POSITION_CURRENT_RIGHT_RANGE:
         if (s != right_range) goto fail;
@@ -3604,7 +3676,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE_OP(MEM_START)
       mem = p->memory_start.num;
-      mem_start_stk[mem] = (StackIndex )((void* )s);
+      mem_start_stk[mem].s = s;
       INC_OP;
       JUMP_OUT;
 
@@ -3616,7 +3688,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE_OP(MEM_END)
       mem = p->memory_end.num;
-      mem_end_stk[mem] = (StackIndex )((void* )s);
+      mem_end_stk[mem].s = s;
       INC_OP;
       JUMP_OUT;
 
@@ -3629,20 +3701,20 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         STACK_GET_MEM_START(mem, stkp); /* should be before push mem-end. */
         si = GET_STACK_INDEX(stkp);
         STACK_PUSH_MEM_END(mem, s);
-        mem_start_stk[mem] = si;
+        mem_start_stk[mem].i = si;
         INC_OP;
         JUMP_OUT;
       }
 
     CASE_OP(MEM_END_REC)
       mem = p->memory_end.num;
-      mem_end_stk[mem] = (StackIndex )((void* )s);
+      mem_end_stk[mem].s = s;
       STACK_GET_MEM_START(mem, stkp);
 
       if (MEM_STATUS_AT(reg->push_mem_start, mem))
-        mem_start_stk[mem] = GET_STACK_INDEX(stkp);
+        mem_start_stk[mem].i = GET_STACK_INDEX(stkp);
       else
-        mem_start_stk[mem] = (StackIndex )((void* )stkp->u.mem.pstr);
+        mem_start_stk[mem].s = stkp->u.mem.pstr;
 
       STACK_PUSH_MEM_END_MARK(mem);
       INC_OP;
@@ -3661,21 +3733,17 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       mem = p->backref_n.n1;
     backref:
       {
-        int len;
         UChar *pstart, *pend;
 
-        if (mem_end_stk[mem]   == INVALID_STACK_INDEX) goto fail;
-        if (mem_start_stk[mem] == INVALID_STACK_INDEX) goto fail;
+        if (mem_end_stk[mem].i   == INVALID_STACK_INDEX) goto fail;
+        if (mem_start_stk[mem].i == INVALID_STACK_INDEX) goto fail;
 
         pstart = STACK_MEM_START(reg, mem);
         pend   = STACK_MEM_END(reg, mem);
         n = (int )(pend - pstart);
         if (n != 0) {
           DATA_ENSURE(n);
-          sprev = s;
           STRING_CMP(s, pstart, n);
-          while (sprev + (len = enclen(encode, sprev)) < s)
-            sprev += len;
         }
       }
       INC_OP;
@@ -3684,21 +3752,17 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE_OP(BACKREF_N_IC)
       mem = p->backref_n.n1;
       {
-        int len;
         UChar *pstart, *pend;
 
-        if (mem_end_stk[mem]   == INVALID_STACK_INDEX) goto fail;
-        if (mem_start_stk[mem] == INVALID_STACK_INDEX) goto fail;
+        if (mem_end_stk[mem].i   == INVALID_STACK_INDEX) goto fail;
+        if (mem_start_stk[mem].i == INVALID_STACK_INDEX) goto fail;
 
         pstart = STACK_MEM_START(reg, mem);
         pend   = STACK_MEM_END(reg, mem);
         n = (int )(pend - pstart);
         if (n != 0) {
           DATA_ENSURE(n);
-          sprev = s;
           STRING_CMP_IC(case_fold_flag, pstart, &s, n);
-          while (sprev + (len = enclen(encode, sprev)) < s)
-            sprev += len;
         }
       }
       INC_OP;
@@ -3706,28 +3770,25 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE_OP(BACKREF_MULTI)
       {
-        int len, is_fail;
+        int is_fail;
         UChar *pstart, *pend, *swork;
 
         tlen = p->backref_general.num;
         for (i = 0; i < tlen; i++) {
           mem = tlen == 1 ? p->backref_general.n1 : p->backref_general.ns[i];
 
-          if (mem_end_stk[mem]   == INVALID_STACK_INDEX) continue;
-          if (mem_start_stk[mem] == INVALID_STACK_INDEX) continue;
+          if (mem_end_stk[mem].i   == INVALID_STACK_INDEX) continue;
+          if (mem_start_stk[mem].i == INVALID_STACK_INDEX) continue;
 
           pstart = STACK_MEM_START(reg, mem);
           pend   = STACK_MEM_END(reg, mem);
           n = (int )(pend - pstart);
           if (n != 0) {
             DATA_ENSURE(n);
-            sprev = s;
             swork = s;
             STRING_CMP_VALUE(swork, pstart, n, is_fail);
             if (is_fail) continue;
             s = swork;
-            while (sprev + (len = enclen(encode, sprev)) < s)
-              sprev += len;
           }
           break; /* success */
         }
@@ -3738,28 +3799,25 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE_OP(BACKREF_MULTI_IC)
       {
-        int len, is_fail;
+        int is_fail;
         UChar *pstart, *pend, *swork;
 
         tlen = p->backref_general.num;
         for (i = 0; i < tlen; i++) {
           mem = tlen == 1 ? p->backref_general.n1 : p->backref_general.ns[i];
 
-          if (mem_end_stk[mem]   == INVALID_STACK_INDEX) continue;
-          if (mem_start_stk[mem] == INVALID_STACK_INDEX) continue;
+          if (mem_end_stk[mem].i   == INVALID_STACK_INDEX) continue;
+          if (mem_start_stk[mem].i == INVALID_STACK_INDEX) continue;
 
           pstart = STACK_MEM_START(reg, mem);
           pend   = STACK_MEM_END(reg, mem);
           n = (int )(pend - pstart);
           if (n != 0) {
             DATA_ENSURE(n);
-            sprev = s;
             swork = s;
             STRING_CMP_VALUE_IC(case_fold_flag, pstart, &swork, n, is_fail);
             if (is_fail) continue;
             s = swork;
-            while (sprev + (len = enclen(encode, sprev)) < s)
-              sprev += len;
           }
           break; /* success */
         }
@@ -3774,10 +3832,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       goto backref_with_level;
     CASE_OP(BACKREF_WITH_LEVEL)
       {
-        int len;
         int level;
         MemNumType* mems;
-        UChar* ssave;
 
         n = 0;
       backref_with_level:
@@ -3785,17 +3841,10 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         tlen  = p->backref_general.num;
         mems = tlen == 1 ? &(p->backref_general.n1) : p->backref_general.ns;
 
-        ssave = s;
-        if (backref_match_at_nested_level(reg, stk, stk_base, n,
-                    case_fold_flag, level, (int )tlen, mems, &s, end)) {
-          if (ssave != s) {
-            sprev = ssave;
-            while (sprev + (len = enclen(encode, sprev)) < s)
-              sprev += len;
-          }
-        }
-        else
+        if (! backref_match_at_nested_level(reg, stk, stk_base, n,
+                      case_fold_flag, level, (int )tlen, mems, &s, end)) {
           goto fail;
+        }
       }
       INC_OP;
       JUMP_OUT;
@@ -3810,8 +3859,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
         for (i = 0; i < tlen; i++) {
           mem = mems[i];
-          if (mem_end_stk[mem]   == INVALID_STACK_INDEX) continue;
-          if (mem_start_stk[mem] == INVALID_STACK_INDEX) continue;
+          if (mem_end_stk[mem].i   == INVALID_STACK_INDEX) continue;
+          if (mem_start_stk[mem].i == INVALID_STACK_INDEX) continue;
           break; /* success */
         }
         if (i == tlen) goto fail;
@@ -3928,13 +3977,13 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE_OP(PUSH)
       addr = p->push.addr;
-      STACK_PUSH_ALT(p + addr, s, sprev);
+      STACK_PUSH_ALT(p + addr, s);
       INC_OP;
       JUMP_OUT;
 
     CASE_OP(PUSH_SUPER)
       addr = p->push.addr;
-      STACK_PUSH_SUPER_ALT(p + addr, s, sprev);
+      STACK_PUSH_SUPER_ALT(p + addr, s);
       INC_OP;
       JUMP_OUT;
 
@@ -3956,7 +4005,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         addr = p->push_or_jump_exact1.addr;
         c    = p->push_or_jump_exact1.c;
         if (DATA_ENSURE_CHECK1 && c == *s) {
-          STACK_PUSH_ALT(p + addr, s, sprev);
+          STACK_PUSH_ALT(p + addr, s);
           INC_OP;
           JUMP_OUT;
         }
@@ -3972,9 +4021,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         addr = p->push_if_peek_next.addr;
         c    = p->push_if_peek_next.c;
         if (DATA_ENSURE_CHECK1 && c == *s) {
-          STACK_PUSH_ALT(p + addr, s, sprev);
-          INC_OP;
-          JUMP_OUT;
+          STACK_PUSH_ALT(p + addr, s);
         }
       }
       INC_OP;
@@ -3986,7 +4033,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
       STACK_PUSH_REPEAT_INC(mem, 0);
       if (reg->repeat_range[mem].lower == 0) {
-        STACK_PUSH_ALT(p + addr, s, sprev);
+        STACK_PUSH_ALT(p + addr, s);
       }
       INC_OP;
       JUMP_OUT;
@@ -3997,7 +4044,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
       STACK_PUSH_REPEAT_INC(mem, 0);
       if (reg->repeat_range[mem].lower == 0) {
-        STACK_PUSH_ALT(p + 1, s, sprev);
+        STACK_PUSH_ALT(p + 1, s);
         p += addr;
       }
       else
@@ -4014,7 +4061,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       }
       else if (n >= reg->repeat_range[mem].lower) {
         INC_OP;
-        STACK_PUSH_ALT(p, s, sprev);
+        STACK_PUSH_ALT(p, s);
         p = reg->repeat_range[mem].u.pcode;
       }
       else {
@@ -4033,7 +4080,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       }
       else {
         if (n >= reg->repeat_range[mem].lower) {
-          STACK_PUSH_ALT(reg->repeat_range[mem].u.pcode, s, sprev);
+          STACK_PUSH_ALT(reg->repeat_range[mem].u.pcode, s);
           INC_OP;
         }
         else {
@@ -4047,6 +4094,21 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       if (subexp_call_nest_counter == SubexpCallMaxNestLevel)
         goto fail;
       subexp_call_nest_counter++;
+
+      if (SubexpCallLimitInSearch != 0) {
+        msa->subexp_call_in_search_counter++;
+#ifdef ONIG_DEBUG_MATCH_COUNTER
+        if (p->call.called_mem < MAX_SUBEXP_CALL_COUNTERS)
+          subexp_call_counters[p->call.called_mem]++;
+        if (msa->subexp_call_in_search_counter % 1000 == 0)
+          MATCH_COUNTER_OUT("CALL");
+#endif
+        if (msa->subexp_call_in_search_counter >
+            SubexpCallLimitInSearch) {
+          MATCH_AT_ERROR_RETURN(ONIGERR_SUBEXP_CALL_LIMIT_IN_SEARCH_OVER);
+        }
+      }
+
       addr = p->call.addr;
       INC_OP; STACK_PUSH_CALL_FRAME(p);
       p = reg->ops + addr;
@@ -4070,7 +4132,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
         for (tlen = p->move.n; tlen > 0; tlen--) {
           len = enclen(encode, s);
-          sprev = s;
           s += len;
           if (s > end) goto fail;
           if (s == end) {
@@ -4079,7 +4140,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
           }
         }
       }
-      sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
       INC_OP;
       JUMP_OUT;
 
@@ -4088,10 +4148,9 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       if (tlen != 0) {
         s = (UChar* )ONIGENC_STEP_BACK(encode, str, s, (int )tlen);
         if (IS_NULL(s)) goto fail;
-        sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
       }
       if (p->step_back_start.remaining != 0) {
-        STACK_PUSH_ALT_WITH_ZID(p + 1, s, sprev, p->step_back_start.remaining);
+        STACK_PUSH_ALT_WITH_ZID(p + 1, s, p->step_back_start.remaining);
         p += p->step_back_start.addr;
       }
       else
@@ -4103,9 +4162,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       if (tlen != INFINITE_LEN) tlen--;
       s = (UChar* )ONIGENC_STEP_BACK(encode, str, s, 1);
       if (IS_NULL(s)) goto fail;
-      sprev = (UChar* )onigenc_get_prev_char_head(encode, str, s);
       if (tlen != 0) {
-        STACK_PUSH_ALT_WITH_ZID(p, s, sprev, (int )tlen);
+        STACK_PUSH_ALT_WITH_ZID(p, s, (int )tlen);
       }
       INC_OP;
       JUMP_OUT;
@@ -4114,8 +4172,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       mem  = p->cut_to_mark.id; /* mem: mark id */
       STACK_TO_VOID_TO_MARK(stkp, mem);
       if (p->cut_to_mark.restore_pos != 0) {
-        s     = stkp->u.val.v;
-        sprev = stkp->u.val.v2;
+        s = stkp->u.val.v;
       }
       INC_OP;
       JUMP_OUT;
@@ -4123,7 +4180,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE_OP(MARK)
       mem  = p->mark.id; /* mem: mark id */
       if (p->mark.save_pos != 0)
-        STACK_PUSH_MARK_WITH_POS(mem, s, sprev);
+        STACK_PUSH_MARK_WITH_POS(mem, s);
       else
         STACK_PUSH_MARK(mem);
 
@@ -4275,9 +4332,8 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     fail:
 #endif
       STACK_POP;
-      p     = stk->u.state.pcode;
-      s     = stk->u.state.pstr;
-      sprev = stk->u.state.pstr_prev;
+      p = stk->u.state.pcode;
+      s = stk->u.state.pstr;
       CHECK_RETRY_LIMIT_IN_MATCH;
       JUMP_OUT;
 
@@ -4290,6 +4346,11 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   if (msa->retry_limit_in_search != 0) {
     msa->retry_limit_in_search_counter += retry_in_match_counter;
   }
+
+#ifdef ONIG_DEBUG_MATCH_COUNTER
+  MATCH_COUNTER_OUT("END");
+#endif
+
   STACK_SAVE(msa, is_alloca, alloc_base);
   return best_len;
 }
@@ -4324,12 +4385,11 @@ typedef struct {
   int    state;  /* value of enum SearchRangeStatus */
   UChar* low;
   UChar* high;
-  UChar* low_prev;
   UChar* sch_range;
 } SearchRange;
 
 #define REGSET_MATCH_AND_RETURN_CHECK(upper_range) \
-  r = match_at(reg, str, end, (upper_range), s, prev, msas + i); \
+  r = match_at(reg, str, end, (upper_range), s, msas + i); \
   if (r != ONIG_MISMATCH) {\
     if (r >= 0) {\
       goto match;\
@@ -4345,8 +4405,8 @@ regset_search_body_position_lead(OnigRegSet* set,
            OnigOptionType option, MatchArg* msas, int* rmatch_pos)
 {
   int r, n, i;
-  UChar *s, *prev;
-  UChar *low, *high, *low_prev;
+  UChar *s;
+  UChar *low, *high;
   UChar* sch_range;
   regex_t* reg;
   OnigEncoding enc;
@@ -4354,12 +4414,7 @@ regset_search_body_position_lead(OnigRegSet* set,
 
   n   = set->n;
   enc = set->enc;
-
   s = (UChar* )start;
-  if (s > str)
-    prev = onigenc_get_prev_char_head(enc, str, s);
-  else
-    prev = (UChar* )NULL;
 
   sr = (SearchRange* )xmalloc(sizeof(*sr) * n);
   CHECK_NULL_RETURN_MEMERR(sr);
@@ -4375,18 +4430,16 @@ regset_search_body_position_lead(OnigRegSet* set,
         else
           sch_range = (UChar* )end;
 
-        if (forward_search(reg, str, end, s, sch_range, &low, &high, &low_prev)) {
+        if (forward_search(reg, str, end, s, sch_range, &low, &high)) {
           sr[i].state = SRS_LOW_HIGH;
           sr[i].low  = low;
           sr[i].high = high;
-          sr[i].low_prev = low_prev;
           sr[i].sch_range = sch_range;
         }
       }
       else {
         sch_range = (UChar* )end;
-        if (forward_search(reg, str, end, s, sch_range,
-                           &low, &high, (UChar** )NULL)) {
+        if (forward_search(reg, str, end, s, sch_range, &low, &high)) {
           goto total_active;
         }
       }
@@ -4396,7 +4449,6 @@ regset_search_body_position_lead(OnigRegSet* set,
       sr[i].state    = SRS_ALL_RANGE;
       sr[i].low      = s;
       sr[i].high     = (UChar* )range;
-      sr[i].low_prev = prev;
     }
   }
 
@@ -4412,10 +4464,9 @@ regset_search_body_position_lead(OnigRegSet* set,
         if (s <  sr[i].low) continue;
         if (s >= sr[i].high) {
           if (forward_search(set->rs[i].reg, str, end, s, sr[i].sch_range,
-                             &low, &high, &low_prev) != 0) {
+                             &low, &high) != 0) {
             sr[i].low      = low;
             sr[i].high     = high;
-            sr[i].low_prev = low_prev;
             if (s < low) continue;
           }
           else {
@@ -4436,16 +4487,13 @@ regset_search_body_position_lead(OnigRegSet* set,
         for (i = 0; i < n; i++) {
           if (sr[i].state == SRS_LOW_HIGH && low > sr[i].low) {
             low = sr[i].low;
-            low_prev = sr[i].low_prev;
           }
         }
         if (low == range) break;
 
         s = low;
-        prev = low_prev;
       }
       else {
-        prev = s;
         s += enclen(enc, s);
       }
     } while (1);
@@ -4459,10 +4507,9 @@ regset_search_body_position_lead(OnigRegSet* set,
           if (s <  sr[i].low) continue;
           if (s >= sr[i].high) {
             if (forward_search(set->rs[i].reg, str, end, s, sr[i].sch_range,
-                               &low, &high, &low_prev) != 0) {
+                               &low, &high) != 0) {
               sr[i].low      = low;
               sr[i].high     = high;
-              /* sr[i].low_prev = low_prev; */
               if (s < low) continue;
             }
             else {
@@ -4483,7 +4530,6 @@ regset_search_body_position_lead(OnigRegSet* set,
       if (set->anychar_inf != 0)
         prev_is_newline = ONIGENC_IS_MBC_NEWLINE(set->enc, s, end);
 
-      prev = s;
       s += enclen(enc, s);
     } while (1);
   }
@@ -4552,7 +4598,7 @@ onig_regset_search_with_param(OnigRegSet* set,
 {
   int r;
   int i;
-  UChar *s, *prev;
+  UChar *s;
   regex_t* reg;
   OnigEncoding enc;
   OnigRegion* region;
@@ -4654,7 +4700,6 @@ onig_regset_search_with_param(OnigRegSet* set,
   else if (str == end) { /* empty string */
     start = end = str;
     s = (UChar* )start;
-    prev = (UChar* )NULL;
 
     msas = (MatchArg* )xmalloc(sizeof(*msas) * set->n);
     CHECK_NULL_RETURN_MEMERR(msas);
@@ -4669,7 +4714,7 @@ onig_regset_search_with_param(OnigRegSet* set,
         /* Can't use REGSET_MATCH_AND_RETURN_CHECK()
            because r must be set regex index (i)
         */
-        r = match_at(reg, str, end, end, s, prev, msas + i);
+        r = match_at(reg, str, end, end, s, msas + i);
         if (r != ONIG_MISMATCH) {
           if (r >= 0) {
             r = i;
@@ -4814,7 +4859,7 @@ slow_search_backward(OnigEncoding enc, UChar* target, UChar* target_end,
   else
     s = ONIGENC_LEFT_ADJUST_CHAR_HEAD(enc, adjust_text, s);
 
-  while (s >= text) {
+  while (PTR_GE(s, text)) {
     if (*s == *target) {
       p = s + 1;
       t = target + 1;
@@ -4855,7 +4900,7 @@ sunday_quick_search_step_forward(regex_t* reg,
   tail = target_end - 1;
   tlen1 = (int )(tail - target);
   end = text_range;
-  if (end + tlen1 > text_end)
+  if (tlen1 > text_end - end)
     end = text_end - tlen1;
 
   map_offset = reg->map_offset;
@@ -4893,15 +4938,38 @@ sunday_quick_search(regex_t* reg, const UChar* target, const UChar* target_end,
   const UChar *s, *t, *p, *end;
   const UChar *tail;
   int map_offset;
-
-  end = text_range + (target_end - target);
-  if (end > text_end)
-    end = text_end;
+  ptrdiff_t target_len;
 
   map_offset = reg->map_offset;
   tail = target_end - 1;
-  s = text + (tail - target);
+  target_len = target_end - target;
 
+  if (target_len > text_end - text_range) {
+    end = text_end;
+    if (target_len > text_end - text)
+      return (UChar* )NULL;
+  }
+  else {
+    end = text_range + target_len;
+  }
+
+  s = text + target_len - 1;
+
+#ifdef USE_STRICT_POINTER_ADDRESS
+  if (s < end) {
+    while (TRUE) {
+      p = s;
+      t = tail;
+      while (*p == *t) {
+        if (t == target) return (UChar* )p;
+        p--; t--;
+      }
+      if (text_end - s <= map_offset) break;
+      if (reg->map[*(s + map_offset)] >= end - s) break;
+      s += reg->map[*(s + map_offset)];
+    }
+  }
+#else
   while (s < end) {
     p = s;
     t = tail;
@@ -4909,9 +4977,10 @@ sunday_quick_search(regex_t* reg, const UChar* target, const UChar* target_end,
       if (t == target) return (UChar* )p;
       p--; t--;
     }
-    if (s + map_offset >= text_end) break;
+    if (text_end - s <= map_offset) break;
     s += reg->map[*(s + map_offset)];
   }
+#endif
 
   return (UChar* )NULL;
 }
@@ -4937,7 +5006,7 @@ map_search_backward(OnigEncoding enc, UChar map[],
 {
   const UChar *s = text_start;
 
-  while (s >= text) {
+  while (PTR_GE(s, text)) {
     if (map[*s]) return (UChar* )s;
 
     s = onigenc_get_prev_char_head(enc, adjust_text, s);
@@ -4963,13 +5032,16 @@ onig_match_with_param(regex_t* reg, const UChar* str, const UChar* end,
                       OnigMatchParam* mp)
 {
   int r;
-  UChar *prev;
   MatchArg msa;
 
+#ifndef USE_POSIX_API
+  if (OPTON_POSIX_REGION(option)) return ONIGERR_INVALID_ARGUMENT;
+#endif
+
   ADJUST_MATCH_PARAM(reg, mp);
   MATCH_ARG_INIT(msa, reg, option, region, at, mp);
   if (region
-#ifdef USE_POSIX_API_REGION_OPTION
+#ifdef USE_POSIX_API
       && !OPTON_POSIX_REGION(option)
 #endif
       ) {
@@ -4986,8 +5058,14 @@ onig_match_with_param(regex_t* reg, const UChar* str, const UChar* end,
       }
     }
 
-    prev = (UChar* )onigenc_get_prev_char_head(reg->enc, str, at);
-    r = match_at(reg, str, end, end, at, prev, &msa);
+    r = match_at(reg, str, end, end, at, &msa);
+#ifdef USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
+    if (OPTON_FIND_LONGEST(option) && r == ONIG_MISMATCH) {
+      if (msa.best_len >= 0) {
+        r = msa.best_len;
+      }
+    }
+#endif
   }
 
  end:
@@ -4997,7 +5075,7 @@ onig_match_with_param(regex_t* reg, const UChar* str, const UChar* end,
 
 static int
 forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start,
-               UChar* range, UChar** low, UChar** high, UChar** low_prev)
+               UChar* range, UChar** low, UChar** high)
 {
   UChar *p, *pprev = (UChar* )NULL;
 
@@ -5081,33 +5159,18 @@ forward_search(regex_t* reg, const UChar* str, const UChar* end, UChar* start,
     }
 
     if (reg->dist_max == 0) {
-      *low = p;
-      if (low_prev) {
-        if (*low > start)
-          *low_prev = onigenc_get_prev_char_head(reg->enc, start, p);
-        else
-          *low_prev = onigenc_get_prev_char_head(reg->enc,
-                                                 (pprev ? pprev : str), p);
-      }
+      *low  = p;
       *high = p;
     }
     else {
       if (reg->dist_max != INFINITE_LEN) {
         if (p - str < reg->dist_max) {
           *low = (UChar* )str;
-          if (low_prev)
-            *low_prev = onigenc_get_prev_char_head(reg->enc, str, *low);
         }
         else {
           *low = p - reg->dist_max;
           if (*low > start) {
-            *low = onigenc_get_right_adjust_char_head_with_prev(reg->enc, start,
-                                                 *low, (const UChar** )low_prev);
-          }
-          else {
-            if (low_prev)
-              *low_prev = onigenc_get_prev_char_head(reg->enc,
-                                                     (pprev ? pprev : str), *low);
+            *low = onigenc_get_right_adjust_char_head(reg->enc, start, *low);
           }
         }
       }
@@ -5263,7 +5326,7 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
                 OnigOptionType option, OnigMatchParam* mp)
 {
   int r;
-  UChar *s, *prev;
+  UChar *s;
   MatchArg msa;
   const UChar *orig_start = start;
 
@@ -5275,8 +5338,15 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
 
   ADJUST_MATCH_PARAM(reg, mp);
 
+#ifndef USE_POSIX_API
+  if (OPTON_POSIX_REGION(option)) {
+    r = ONIGERR_INVALID_ARGUMENT;
+    goto finish_no_msa;
+  }
+#endif
+
   if (region
-#ifdef USE_POSIX_API_REGION_OPTION
+#ifdef USE_POSIX_API
       && ! OPTON_POSIX_REGION(option)
 #endif
       ) {
@@ -5294,27 +5364,14 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
   }
 
 
-#ifdef USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
 #define MATCH_AND_RETURN_CHECK(upper_range) \
-  r = match_at(reg, str, end, (upper_range), s, prev, &msa); \
-  if (r != ONIG_MISMATCH) {\
-    if (r >= 0) {\
-      if (! OPTON_FIND_LONGEST(reg->options)) {\
-        goto match;\
-      }\
-    }\
-    else goto finish; /* error */ \
-  }
-#else
-#define MATCH_AND_RETURN_CHECK(upper_range) \
-  r = match_at(reg, str, end, (upper_range), s, prev, &msa); \
+  r = match_at(reg, str, end, (upper_range), s, &msa);\
   if (r != ONIG_MISMATCH) {\
     if (r >= 0) {\
       goto match;\
     }\
     else goto finish; /* error */ \
   }
-#endif /* USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE */
 
 
   /* anchor optimize: resume search range */
@@ -5422,7 +5479,6 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
     if (reg->threshold_len == 0) {
       start = end = str = address_for_empty_string;
       s = (UChar* )start;
-      prev = (UChar* )NULL;
 
       MATCH_ARG_INIT(msa, reg, option, region, start, mp);
       MATCH_AND_RETURN_CHECK(end);
@@ -5440,13 +5496,8 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
 
   s = (UChar* )start;
   if (range > start) {   /* forward search */
-    if (s > str)
-      prev = onigenc_get_prev_char_head(reg->enc, str, s);
-    else
-      prev = (UChar* )NULL;
-
     if (reg->optimize != OPTIMIZE_NONE) {
-      UChar *sch_range, *low, *high, *low_prev;
+      UChar *sch_range, *low, *high;
 
       if (reg->dist_max != 0) {
         if (reg->dist_max == INFINITE_LEN)
@@ -5467,27 +5518,27 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
 
       if (reg->dist_max != INFINITE_LEN) {
         do {
-          if (! forward_search(reg, str, end, s, sch_range, &low, &high,
-                               &low_prev)) goto mismatch;
+          if (! forward_search(reg, str, end, s, sch_range, &low, &high))
+            goto mismatch;
           if (s < low) {
             s    = low;
-            prev = low_prev;
           }
           while (s <= high) {
             MATCH_AND_RETURN_CHECK(data_range);
-            prev = s;
             s += enclen(reg->enc, s);
           }
         } while (s < range);
         goto mismatch;
       }
       else { /* check only. */
-        if (! forward_search(reg, str, end, s, sch_range, &low, &high,
-                             (UChar** )NULL)) goto mismatch;
+        if (! forward_search(reg, str, end, s, sch_range, &low, &high))
+          goto mismatch;
 
         if ((reg->anchor & ANCR_ANYCHAR_INF) != 0 &&
             (reg->anchor & (ANCR_LOOK_BEHIND | ANCR_PREC_READ_NOT)) == 0) {
           do {
+            UChar* prev;
+
             MATCH_AND_RETURN_CHECK(data_range);
             prev = s;
             s += enclen(reg->enc, s);
@@ -5504,7 +5555,6 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
 
     do {
       MATCH_AND_RETURN_CHECK(data_range);
-      prev = s;
       s += enclen(reg->enc, s);
     } while (s < range);
 
@@ -5549,12 +5599,11 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
           if (s > high)
             s = high;
 
-          while (s >= low) {
-            prev = onigenc_get_prev_char_head(reg->enc, str, s);
+          while (PTR_GE(s, low)) {
             MATCH_AND_RETURN_CHECK(orig_start);
-            s = prev;
+            s = onigenc_get_prev_char_head(reg->enc, str, s);
           }
-        } while (s >= range);
+        } while (PTR_GE(s, range));
         goto mismatch;
       }
       else { /* check only. */
@@ -5566,10 +5615,9 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
     }
 
     do {
-      prev = onigenc_get_prev_char_head(reg->enc, str, s);
       MATCH_AND_RETURN_CHECK(orig_start);
-      s = prev;
-    } while (s >= range);
+      s = onigenc_get_prev_char_head(reg->enc, str, s);
+    } while (PTR_GE(s, range));
   }
 
  mismatch:
@@ -5589,7 +5637,7 @@ search_in_range(regex_t* reg, const UChar* str, const UChar* end,
   /* If result is mismatch and no FIND_NOT_EMPTY option,
      then the region is not set in match_at(). */
   if (OPTON_FIND_NOT_EMPTY(reg->options) && region
-#ifdef USE_POSIX_API_REGION_OPTION
+#ifdef USE_POSIX_API
       && !OPTON_POSIX_REGION(option)
 #endif
       ) {
@@ -5952,7 +6000,7 @@ extern int
 onig_init_for_match_at(regex_t* reg)
 {
   return match_at(reg, (const UChar* )NULL, (const UChar* )NULL,
-                  (const UChar* )NULL, (const UChar* )NULL, (UChar* )NULL,
+                  (const UChar* )NULL, (const UChar* )NULL,
                   (MatchArg* )NULL);
 }
 #endif
@@ -6139,8 +6187,8 @@ onig_get_capture_range_in_callout(OnigCalloutArgs* a, int mem_num, int* begin, i
   const UChar* str;
   StackType*   stk_base;
   int i;
-  StackIndex* mem_start_stk;
-  StackIndex* mem_end_stk;
+  StkPtrType* mem_start_stk;
+  StkPtrType* mem_end_stk;
 
   i = mem_num;
   reg = a->regex;
@@ -6150,7 +6198,7 @@ onig_get_capture_range_in_callout(OnigCalloutArgs* a, int mem_num, int* begin, i
   mem_end_stk   = a->mem_end_stk;
 
   if (i > 0) {
-    if (a->mem_end_stk[i] != INVALID_STACK_INDEX) {
+    if (a->mem_end_stk[i].i != INVALID_STACK_INDEX) {
       *begin = (int )(STACK_MEM_START(reg, i) - str);
       *end   = (int )(STACK_MEM_END(reg, i)   - str);
     }
diff --git a/src/regint.h b/src/regint.h
index 04ebe0a..74a5c61 100644
--- a/src/regint.h
+++ b/src/regint.h
@@ -34,6 +34,7 @@
 /* #define ONIG_DEBUG_COMPILE */
 /* #define ONIG_DEBUG_SEARCH */
 /* #define ONIG_DEBUG_MATCH */
+/* #define ONIG_DEBUG_MATCH_COUNTER */
 /* #define ONIG_DONT_OPTIMIZE */
 
 /* for byte-code statistical data. */
@@ -41,7 +42,7 @@
 
 #if defined(ONIG_DEBUG_PARSE) || defined(ONIG_DEBUG_MATCH) || \
     defined(ONIG_DEBUG_SEARCH) || defined(ONIG_DEBUG_COMPILE) || \
-    defined(ONIG_DEBUG_STATISTICS)
+    defined(ONIG_DEBUG_MATCH_COUNTER) || defined(ONIG_DEBUG_STATISTICS)
 #ifndef ONIG_DEBUG
 #define ONIG_DEBUG
 #define DBGFP   stderr
@@ -70,23 +71,29 @@
 #endif
 
 /* internal config */
+#define USE_CHECK_VALIDITY_OF_STRING_IN_TREE
 #define USE_OP_PUSH_OR_JUMP_EXACT
 #define USE_QUANT_PEEK_NEXT
 #define USE_ST_LIBRARY
 #define USE_TIMEOFDAY
+#define USE_STRICT_POINTER_ADDRESS
+#define USE_STRICT_POINTER_COMPARISON
 
 #define USE_WORD_BEGIN_END   /* "\<", "\>" */
 #define USE_CAPTURE_HISTORY
 #define USE_VARIABLE_META_CHARS
-#define USE_POSIX_API_REGION_OPTION
 #define USE_FIND_LONGEST_SEARCH_ALL_OF_RANGE
 /* #define USE_REPEAT_AND_EMPTY_CHECK_LOCAL_VAR */
 
+/* enabled by configure --enable-posix-api=yes */
+/* #define USE_POSIX_API */
+
+#define DEFAULT_PARSE_DEPTH_LIMIT           4096
 #define INIT_MATCH_STACK_SIZE                160
 #define DEFAULT_MATCH_STACK_LIMIT_SIZE         0 /* unlimited */
 #define DEFAULT_RETRY_LIMIT_IN_MATCH    10000000
 #define DEFAULT_RETRY_LIMIT_IN_SEARCH          0 /* unlimited */
-#define DEFAULT_PARSE_DEPTH_LIMIT           4096
+#define DEFAULT_SUBEXP_CALL_LIMIT_IN_SEARCH    0 /* unlimited */
 #define DEFAULT_SUBEXP_CALL_MAX_NEST_LEVEL    20
 
 
@@ -181,6 +188,12 @@
 #define CHECK_NULL_RETURN_MEMERR(p)   if (IS_NULL(p)) return ONIGERR_MEMORY
 #define NULL_UCHARP                   ((UChar* )0)
 
+#ifdef USE_STRICT_POINTER_COMPARISON
+#define PTR_GE(p,q)   ((p) != NULL && (p) >= (q))
+#else
+#define PTR_GE(p,q)   (p) >= (q)
+#endif
+
 #ifndef ONIG_INT_MAX
 #define ONIG_INT_MAX    INT_MAX
 #endif
@@ -255,11 +268,22 @@
 
 
 #ifdef _WIN32
-#if defined(_MSC_VER) && (_MSC_VER < 1300)
+#ifdef _MSC_VER
+
+#if _MSC_VER < 1300
 typedef int           intptr_t;
 typedef unsigned int  uintptr_t;
 #endif
+
+#if _MSC_VER < 1600
+typedef __int32 int32_t;
+typedef unsigned __int32 uint32_t;
+typedef __int64 int64_t;
+typedef unsigned __int64 uint64_t;
+#endif
+
 #endif
+#endif /* _WIN32 */
 
 #if SIZEOF_VOIDP == SIZEOF_LONG
 typedef unsigned long hash_data_type;
@@ -378,6 +402,9 @@ typedef unsigned int  MemStatusType;
 #define OPTON_POSIX_REGION(option)   ((option) & ONIG_OPTION_POSIX_REGION)
 #define OPTON_CHECK_VALIDITY_OF_STRING(option)  ((option) & \
                                       ONIG_OPTION_CHECK_VALIDITY_OF_STRING)
+#define OPTON_NOT_BEGIN_STRING(option)    ((option) & ONIG_OPTION_NOT_BEGIN_STRING)
+#define OPTON_NOT_END_STRING(option)      ((option) & ONIG_OPTION_NOT_END_STRING)
+#define OPTON_NOT_BEGIN_POSITION(option)  ((option) & ONIG_OPTION_NOT_BEGIN_POSITION)
 
 #define DISABLE_CASE_FOLD_MULTI_CHAR(case_fold_flag) \
   ((case_fold_flag) & ~INTERNAL_ONIGENC_CASE_FOLD_MULTI_CHAR)
@@ -562,10 +589,14 @@ enum OpCode {
   OP_BACKREF_N_IC,
   OP_BACKREF_MULTI,
   OP_BACKREF_MULTI_IC,
+#ifdef USE_BACKREF_WITH_LEVEL
   OP_BACKREF_WITH_LEVEL,        /* \k<xxx+n>, \k<xxx-n> */
   OP_BACKREF_WITH_LEVEL_IC,     /* \k<xxx+n>, \k<xxx-n> */
+#endif
   OP_BACKREF_CHECK,             /* (?(n)), (?('name')) */
+#ifdef USE_BACKREF_WITH_LEVEL
   OP_BACKREF_CHECK_WITH_LEVEL,  /* (?(n-level)), (?('name-level')) */
+#endif
   OP_MEM_START,
   OP_MEM_START_PUSH,     /* push back-tracker to stack */
   OP_MEM_END_PUSH,       /* push back-tracker to stack */
@@ -891,6 +922,9 @@ typedef struct {
     } update_var;
     struct {
       AbsAddrType addr;
+#ifdef ONIG_DEBUG_MATCH_COUNTER
+      MemNumType called_mem;
+#endif
     } call;
 #ifdef USE_CALLOUT
     struct {
diff --git a/src/regparse.c b/src/regparse.c
index cc015a7..dd2824b 100644
--- a/src/regparse.c
+++ b/src/regparse.c
@@ -290,7 +290,7 @@ bbuf_clone(BBuf** rto, BBuf* from)
   CHECK_NULL_RETURN_MEMERR(to);
   r = BB_INIT(to, from->alloc);
   if (r != 0) {
-    xfree(to->p);
+    bbuf_free(to);
     *rto = 0;
     return r;
   }
@@ -303,6 +303,8 @@ static int
 backref_rel_to_abs(int rel_no, ScanEnv* env)
 {
   if (rel_no > 0) {
+    if (rel_no > ONIG_INT_MAX - env->num_mem)
+      return ONIGERR_INVALID_BACKREF;
     return env->num_mem + rel_no;
   }
   else {
@@ -437,6 +439,7 @@ strcat_capa(UChar* dest, UChar* dest_end, const UChar* src, const UChar* src_end
             int capa)
 {
   UChar* r;
+  ptrdiff_t dest_delta = dest_end - dest;
 
   if (dest)
     r = (UChar* )xrealloc(dest, capa + 1);
@@ -444,7 +447,7 @@ strcat_capa(UChar* dest, UChar* dest_end, const UChar* src, const UChar* src_end
     r = (UChar* )xmalloc(capa + 1);
 
   CHECK_NULL_RETURN(r);
-  onig_strcpy(r + (dest_end - dest), src, src_end);
+  onig_strcpy(r + dest_delta, src, src_end);
   return r;
 }
 
@@ -1294,7 +1297,9 @@ static int
 i_free_callout_name_entry(st_callout_name_key* key, CalloutNameEntry* e,
                           void* arg ARG_UNUSED)
 {
-  xfree(e->name);
+  if (IS_NOT_NULL(e)) {
+    xfree(e->name);
+  }
   /*xfree(key->s); */ /* is same as e->name */
   xfree(key);
   xfree(e);
@@ -2502,7 +2507,7 @@ node_new_call(UChar* name, UChar* name_end, int gnum, int by_number)
   CALL_(node)->by_number   = by_number;
   CALL_(node)->name        = name;
   CALL_(node)->name_end    = name_end;
-  CALL_(node)->group_num   = gnum;
+  CALL_(node)->called_gnum = gnum;
   CALL_(node)->entry_count = 1;
   return node;
 }
@@ -3135,7 +3140,6 @@ make_absent_tree_for_simple_one_char_repeat(Node** node, Node* absent, Node* qua
 
   lower = QUANT_(quant)->lower;
   upper = QUANT_(quant)->upper;
-  onig_node_free(quant);
 
   r = node_new_save_gimmick(&ns[0], SAVE_RIGHT_RANGE, env);
   if (r != 0) goto err;
@@ -3202,9 +3206,9 @@ make_absent_tree(Node** node, Node* absent, Node* expr, int is_range_cutter,
       simple:
         r = make_absent_tree_for_simple_one_char_repeat(node, absent, quant,
                                                         body, possessive, env);
+        onig_node_free(quant);
         if (r != 0) {
           ns[4] = NULL_NODE;
-          onig_node_free(quant);
           onig_node_free(body);
           goto err;
         }
@@ -3708,21 +3712,24 @@ get_next_code_point(UChar** src, UChar* end, int base, OnigEncoding enc, int in_
 
   while (! PEND) {
     PFETCH(c);
-    if (! IS_CODE_POINT_DIVIDE(c)) break;
-  }
-  if (IS_CODE_POINT_DIVIDE(c))
-    return ONIGERR_INVALID_CODE_POINT_VALUE;
-
-  if (c == '}') {
-    *src = p;
-    return 1; /* end of sequence */
-  }
-  else if (c == '-' && in_cc == TRUE) {
-    *src = p;
-    return 2; /* range */
+    if (! IS_CODE_POINT_DIVIDE(c)) {
+      if (c == '}') {
+        *src = p;
+        return 1; /* end of sequence */
+      }
+      else if (c == '-' && in_cc == TRUE) {
+        *src = p;
+        return 2; /* range */
+      }
+      PUNFETCH;
+      break;
+    }
+    else {
+      if (PEND)
+        return ONIGERR_INVALID_CODE_POINT_VALUE;
+    }
   }
 
-  PUNFETCH;
   r = scan_number_of_base(&p, end, 1, enc, rcode, base);
   if (r != 0) return r;
 
@@ -3873,13 +3880,17 @@ not_code_range_buf(OnigEncoding enc, BBuf* bbuf, BBuf** pbuf)
     to   = data[i*2+1];
     if (pre <= from - 1) {
       r = add_code_range_to_buf(pbuf, pre, from - 1);
-      if (r != 0) return r;
+      if (r != 0) {
+        bbuf_free(*pbuf);
+        return r;
+      }
     }
     if (to == ~((OnigCodePoint )0)) break;
     pre = to + 1;
   }
   if (to < ~((OnigCodePoint )0)) {
     r = add_code_range_to_buf(pbuf, to + 1, ~((OnigCodePoint )0));
+    if (r != 0) bbuf_free(*pbuf);
   }
   return r;
 }
@@ -4564,7 +4575,7 @@ fetch_interval(UChar** src, UChar* end, PToken* tok, ScanEnv* env)
 
 /* \M-, \C-, \c, or \... */
 static int
-fetch_escaped_value(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
+fetch_escaped_value_raw(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
 {
   int v;
   OnigCodePoint c;
@@ -4583,7 +4594,7 @@ fetch_escaped_value(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
       if (PEND) return ONIGERR_END_PATTERN_AT_META;
       PFETCH_S(c);
       if (c == MC_ESC(env->syntax)) {
-        v = fetch_escaped_value(&p, end, env, &c);
+        v = fetch_escaped_value_raw(&p, end, env, &c);
         if (v < 0) return v;
       }
       c = ((c & 0xff) | 0x80);
@@ -4612,7 +4623,7 @@ fetch_escaped_value(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
       }
       else {
         if (c == MC_ESC(env->syntax)) {
-          v = fetch_escaped_value(&p, end, env, &c);
+          v = fetch_escaped_value_raw(&p, end, env, &c);
           if (v < 0) return v;
         }
         c &= 0x9f;
@@ -4634,6 +4645,21 @@ fetch_escaped_value(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
   return 0;
 }
 
+static int
+fetch_escaped_value(UChar** src, UChar* end, ScanEnv* env, OnigCodePoint* val)
+{
+  int r;
+  int len;
+
+  r = fetch_escaped_value_raw(src, end, env, val);
+  if (r != 0) return r;
+
+  len = ONIGENC_CODE_TO_MBCLEN(env->enc, *val);
+  if (len < 0) return len;
+
+  return 0;
+}
+
 static int fetch_token(PToken* tok, UChar** src, UChar* end, ScanEnv* env);
 
 static OnigCodePoint
@@ -5192,7 +5218,7 @@ fetch_token_cc(PToken* tok, UChar** src, UChar* end, ScanEnv* env, int state)
           else {
             int curr_state;
 
-	    curr_state = (state == CS_RANGE) ? CPS_EMPTY : CPS_START;
+            curr_state = (state == CS_RANGE) ? CPS_EMPTY : CPS_START;
             r = check_code_point_sequence_cc(p, end, tok->base_num, enc,
                                              curr_state);
             if (r < 0) return r;
@@ -6372,7 +6398,7 @@ add_ctype_to_cc(CClassNode* cc, int ctype, int not, ScanEnv* env)
 }
 
 static int
-parse_posix_bracket(CClassNode* cc, UChar** src, UChar* end, ScanEnv* env)
+prs_posix_bracket(CClassNode* cc, UChar** src, UChar* end, ScanEnv* env)
 {
 #define POSIX_BRACKET_CHECK_LIMIT_LENGTH  20
 #define POSIX_BRACKET_NAME_MIN_LEN         4
@@ -6481,7 +6507,7 @@ fetch_char_property_to_ctype(UChar** src, UChar* end, ScanEnv* env)
 }
 
 static int
-parse_char_property(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
+prs_char_property(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
 {
   int r, ctype;
   CClassNode* cc;
@@ -6617,7 +6643,7 @@ code_exist_check(OnigCodePoint c, UChar* from, UChar* end, int ignore_escaped,
 }
 
 static int
-parse_cc(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
+prs_cc(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
 {
   int r, neg, len, fetched, and_start;
   OnigCodePoint in_code, curr_code;
@@ -6715,6 +6741,7 @@ parse_cc(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
           p = psave;
           for (i = 1; i < len; i++) {
             r = fetch_token_cc(tok, &p, end, env, CS_COMPLETE);
+            if (r < 0) goto err;
           }
           fetched = 0;
         }
@@ -6759,7 +6786,7 @@ parse_cc(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
       break;
 
     case TK_CC_POSIX_BRACKET_OPEN:
-      r = parse_posix_bracket(cc, &p, end, env);
+      r = prs_posix_bracket(cc, &p, end, env);
       if (r < 0) goto err;
       if (r == 1) {  /* is not POSIX bracket */
         CC_ESC_WARN(env, (UChar* )"[");
@@ -6869,7 +6896,7 @@ parse_cc(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
         }
         state = CS_COMPLETE;
 
-        r = parse_cc(&anode, tok, &p, end, env);
+        r = prs_cc(&anode, tok, &p, end, env);
         if (r != 0) {
           onig_node_free(anode);
           goto cc_open_err;
@@ -6967,14 +6994,14 @@ parse_cc(Node** np, PToken* tok, UChar** src, UChar* end, ScanEnv* env)
   return r;
 }
 
-static int parse_alts(Node** top, PToken* tok, int term,
-                      UChar** src, UChar* end, ScanEnv* env, int group_head);
+static int prs_alts(Node** top, PToken* tok, int term,
+                    UChar** src, UChar* end, ScanEnv* env, int group_head);
 
 #ifdef USE_CALLOUT
 
 /* (?{...}[tag][+-]) (?{{...}}[tag][+-]) */
 static int
-parse_callout_of_contents(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* env)
+prs_callout_of_contents(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* env)
 {
   int r;
   int i;
@@ -7078,18 +7105,18 @@ parse_callout_of_contents(Node** np, int cterm, UChar** src, UChar* end, ScanEnv
   contents = onigenc_strdup(enc, code_start, code_end);
   CHECK_NULL_RETURN_MEMERR(contents);
 
-  r = node_new_callout(np, ONIG_CALLOUT_OF_CONTENTS, num, ONIG_NON_NAME_ID, env);
-  if (r != 0) {
-    xfree(contents);
-    return r;
-  }
-
   e = onig_reg_callout_list_at(env->reg, num);
   if (IS_NULL(e)) {
     xfree(contents);
     return ONIGERR_MEMORY;
   }
 
+  r = node_new_callout(np, ONIG_CALLOUT_OF_CONTENTS, num, ONIG_NON_NAME_ID, env);
+  if (r != 0) {
+    xfree(contents);
+    return r;
+  }
+
   e->of      = ONIG_CALLOUT_OF_CONTENTS;
   e->in      = in;
   e->name_id = ONIG_NON_NAME_ID;
@@ -7101,7 +7128,7 @@ parse_callout_of_contents(Node** np, int cterm, UChar** src, UChar* end, ScanEnv
 }
 
 static long
-parse_long(OnigEncoding enc, UChar* s, UChar* end, int sign_on, long max, long* rl)
+prs_long(OnigEncoding enc, UChar* s, UChar* end, int sign_on, long max, long* rl)
 {
   long v;
   long d;
@@ -7137,10 +7164,27 @@ parse_long(OnigEncoding enc, UChar* s, UChar* end, int sign_on, long max, long*
   return ONIG_NORMAL;
 }
 
+static void
+clear_callout_args(int n, unsigned int types[], OnigValue vals[])
+{
+  int i;
+
+  for (i = 0; i < n; i++) {
+    switch (types[i]) {
+    case ONIG_TYPE_STRING:
+      if (IS_NOT_NULL(vals[i].s.start))
+        xfree(vals[i].s.start);
+      break;
+    default:
+      break;
+    }
+  }
+}
+
 static int
-parse_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
-                   int max_arg_num, unsigned int types[], OnigValue vals[],
-                   ScanEnv* env)
+prs_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
+                 int max_arg_num, unsigned int types[], OnigValue vals[],
+                 ScanEnv* env)
 {
 #define MAX_CALLOUT_ARG_BYTE_LENGTH   128
 
@@ -7168,7 +7212,10 @@ parse_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
     bufend = buf;
     s = e = p;
     while (1) {
-      if (PEND) return ONIGERR_INVALID_CALLOUT_PATTERN;
+      if (PEND) {
+        r = ONIGERR_INVALID_CALLOUT_PATTERN;
+        goto err_clear;
+      }
 
       e = p;
       PFETCH_S(c);
@@ -7196,8 +7243,10 @@ parse_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
         add_char:
           if (skip_mode == FALSE) {
             clen = p - e;
-            if (bufend + clen > buf + MAX_CALLOUT_ARG_BYTE_LENGTH)
-              return ONIGERR_INVALID_CALLOUT_ARG; /* too long argument */
+            if (bufend + clen > buf + MAX_CALLOUT_ARG_BYTE_LENGTH) {
+              r = ONIGERR_INVALID_CALLOUT_ARG; /* too long argument */
+              goto err_clear;
+            }
 
             xmemcpy(bufend, e, clen);
             bufend += clen;
@@ -7208,15 +7257,17 @@ parse_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
     }
 
     if (cn != 0) {
-      if (max_arg_num >= 0 && n >= max_arg_num)
-        return ONIGERR_INVALID_CALLOUT_ARG;
+      if (max_arg_num >= 0 && n >= max_arg_num) {
+        r = ONIGERR_INVALID_CALLOUT_ARG;
+        goto err_clear;
+      }
 
       if (skip_mode == FALSE) {
         if ((types[n] & ONIG_TYPE_LONG) != 0) {
           int fixed = 0;
           if (cn > 0) {
             long rl;
-            r = parse_long(enc, buf, bufend, 1, LONG_MAX, &rl);
+            r = prs_long(enc, buf, bufend, 1, LONG_MAX, &rl);
             if (r == ONIG_NORMAL) {
               vals[n].l = rl;
               fixed = 1;
@@ -7226,8 +7277,10 @@ parse_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
 
           if (fixed == 0) {
             types[n] = (types[n] & ~ONIG_TYPE_LONG);
-            if (types[n] == ONIG_TYPE_VOID)
-              return ONIGERR_INVALID_CALLOUT_ARG;
+            if (types[n] == ONIG_TYPE_VOID) {
+              r = ONIGERR_INVALID_CALLOUT_ARG;
+              goto err_clear;
+            }
           }
         }
 
@@ -7236,22 +7289,29 @@ parse_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
           break;
 
         case ONIG_TYPE_CHAR:
-          if (cn != 1) return ONIGERR_INVALID_CALLOUT_ARG;
+          if (cn != 1) {
+            r = ONIGERR_INVALID_CALLOUT_ARG;
+            goto err_clear;
+          }
           vals[n].c = ONIGENC_MBC_TO_CODE(enc, buf, bufend);
           break;
 
         case ONIG_TYPE_STRING:
           {
             UChar* rs = onigenc_strdup(enc, buf, bufend);
-            CHECK_NULL_RETURN_MEMERR(rs);
+            if (IS_NULL(rs)) {
+              r = ONIGERR_MEMORY; goto err_clear;
+            }
             vals[n].s.start = rs;
             vals[n].s.end   = rs + (e - s);
           }
           break;
 
         case ONIG_TYPE_TAG:
-          if (eesc != 0 || ! is_allowed_callout_tag_name(enc, s, e))
-            return ONIGERR_INVALID_CALLOUT_TAG_NAME;
+          if (eesc != 0 || ! is_allowed_callout_tag_name(enc, s, e)) {
+            r = ONIGERR_INVALID_CALLOUT_TAG_NAME;
+            goto err_clear;
+          }
 
           vals[n].s.start = s;
           vals[n].s.end   = e;
@@ -7259,7 +7319,8 @@ parse_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
 
         case ONIG_TYPE_VOID:
         case ONIG_TYPE_POINTER:
-          return ONIGERR_PARSER_BUG;
+          r = ONIGERR_PARSER_BUG;
+          goto err_clear;
           break;
         }
       }
@@ -7270,15 +7331,23 @@ parse_callout_args(int skip_mode, int cterm, UChar** src, UChar* end,
     if (c == cterm) break;
   }
 
-  if (c != cterm) return ONIGERR_INVALID_CALLOUT_PATTERN;
+  if (c != cterm) {
+    r = ONIGERR_INVALID_CALLOUT_PATTERN;
+    goto err_clear;
+  }
 
   *src = p;
   return n;
+
+ err_clear:
+  if (skip_mode == FALSE)
+    clear_callout_args(n, types, vals);
+  return r;
 }
 
 /* (*name[TAG]) (*name[TAG]{a,b,..}) */
 static int
-parse_callout_of_name(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* env)
+prs_callout_of_name(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* env)
 {
   int r;
   int i;
@@ -7343,7 +7412,7 @@ parse_callout_of_name(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* en
 
     /* read for single check only */
     save = p;
-    arg_num = parse_callout_args(TRUE, '}', &p, end, -1, NULL, NULL, env);
+    arg_num = prs_callout_args(TRUE, '}', &p, end, -1, NULL, NULL, env);
     if (arg_num < 0) return arg_num;
 
     is_not_single = PPEEK_IS(cterm) ?  0 : 1;
@@ -7357,10 +7426,13 @@ parse_callout_of_name(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* en
       types[i] = get_callout_arg_type_by_name_id(name_id, i);
     }
 
-    arg_num = parse_callout_args(FALSE, '}', &p, end, max_arg_num, types, vals, env);
+    arg_num = prs_callout_args(FALSE, '}', &p, end, max_arg_num, types, vals, env);
     if (arg_num < 0) return arg_num;
 
-    if (PEND) return ONIGERR_END_PATTERN_IN_GROUP;
+    if (PEND) {
+      r = ONIGERR_END_PATTERN_IN_GROUP;
+      goto err_clear;
+    }
     PFETCH_S(c);
   }
   else {
@@ -7379,32 +7451,40 @@ parse_callout_of_name(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* en
 
   in = onig_get_callout_in_by_name_id(name_id);
   opt_arg_num = get_callout_opt_arg_num_by_name_id(name_id);
-  if (arg_num > max_arg_num || arg_num < (max_arg_num - opt_arg_num))
-    return ONIGERR_INVALID_CALLOUT_ARG;
+  if (arg_num > max_arg_num || arg_num < (max_arg_num - opt_arg_num)) {
+    r = ONIGERR_INVALID_CALLOUT_ARG;
+    goto err_clear;
+  }
 
-  if (c != cterm)
-    return ONIGERR_INVALID_CALLOUT_PATTERN;
+  if (c != cterm) {
+    r = ONIGERR_INVALID_CALLOUT_PATTERN;
+    goto err_clear;
+  }
 
   r = reg_callout_list_entry(env, &num);
-  if (r != 0) return r;
+  if (r != 0) goto err_clear;
 
   ext = onig_get_regex_ext(env->reg);
-  CHECK_NULL_RETURN_MEMERR(ext);
+  if (IS_NULL(ext)) {
+    r = ONIGERR_MEMORY; goto err_clear;
+  }
   if (IS_NULL(ext->pattern)) {
     r = onig_ext_set_pattern(env->reg, env->pattern, env->pattern_end);
-    if (r != ONIG_NORMAL) return r;
+    if (r != ONIG_NORMAL) goto err_clear;
   }
 
   if (tag_start != tag_end) {
     r = callout_tag_entry(env, env->reg, tag_start, tag_end, num);
-    if (r != ONIG_NORMAL) return r;
+    if (r != ONIG_NORMAL) goto err_clear;
   }
 
-  r = node_new_callout(&node, ONIG_CALLOUT_OF_NAME, num, name_id, env);
-  if (r != ONIG_NORMAL) return r;
-
   e = onig_reg_callout_list_at(env->reg, num);
-  CHECK_NULL_RETURN_MEMERR(e);
+  if (IS_NULL(e)) {
+    r = ONIGERR_MEMORY; goto err_clear;
+  }
+
+  r = node_new_callout(&node, ONIG_CALLOUT_OF_NAME, num, name_id, env);
+  if (r != ONIG_NORMAL) goto err_clear;
 
   e->of         = ONIG_CALLOUT_OF_NAME;
   e->in         = in;
@@ -7425,12 +7505,16 @@ parse_callout_of_name(Node** np, int cterm, UChar** src, UChar* end, ScanEnv* en
   *np = node;
   *src = p;
   return 0;
+
+ err_clear:
+  clear_callout_args(arg_num, types, vals);
+  return r;
 }
 #endif
 
 static int
-parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
-          ScanEnv* env)
+prs_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
+        ScanEnv* env)
 {
   int r, num;
   Node *target;
@@ -7457,7 +7541,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
     group:
       r = fetch_token(tok, &p, end, env);
       if (r < 0) return r;
-      r = parse_alts(np, tok, term, &p, end, env, FALSE);
+      r = prs_alts(np, tok, term, &p, end, env, FALSE);
       if (r < 0) return r;
       *src = p;
       return 1; /* group */
@@ -7554,7 +7638,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
 
         r = fetch_token(tok, &p, end, env);
         if (r < 0) return r;
-        r = parse_alts(&absent, tok, term, &p, end, env, TRUE);
+        r = prs_alts(&absent, tok, term, &p, end, env, TRUE);
         if (r < 0) {
           onig_node_free(absent);
           return r;
@@ -7600,7 +7684,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
       if (! IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_QMARK_BRACE_CALLOUT_CONTENTS))
         return ONIGERR_UNDEFINED_GROUP_OPTION;
 
-      r = parse_callout_of_contents(np, ')', &p, end, env);
+      r = prs_callout_of_contents(np, ')', &p, end, env);
       if (r != 0) return r;
 
       goto end;
@@ -7620,10 +7704,12 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
 
         if (IS_CODE_DIGIT_ASCII(enc, c)
             || c == '-' || c == '+' || c == '<' || c == '\'') {
-          UChar* name_end;
-          int back_num;
+#ifdef USE_BACKREF_WITH_LEVEL
           int exist_level;
           int level;
+#endif
+          UChar* name_end;
+          int back_num;
           enum REF_NUM num_type;
           int is_enclosed;
 
@@ -7631,8 +7717,8 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
           if (! is_enclosed)
             PUNFETCH;
           prev = p;
-          exist_level = 0;
 #ifdef USE_BACKREF_WITH_LEVEL
+          exist_level = 0;
           name_end = NULL_UCHARP; /* no need. escape gcc warning. */
           r = fetch_name_with_level(
                     (OnigCodePoint )(is_enclosed != 0 ? c : '('),
@@ -7709,7 +7795,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
               /* condition part is callouts of contents: (?(?{...})THEN|ELSE) */
               condition_is_checker = 0;
               PFETCH(c);
-              r = parse_callout_of_contents(&condition, ')', &p, end, env);
+              r = prs_callout_of_contents(&condition, ')', &p, end, env);
               if (r != 0) return r;
               goto end_condition;
             }
@@ -7719,7 +7805,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
         else if (c == '*' &&
                  IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_ASTERISK_CALLOUT_NAME)) {
           condition_is_checker = 0;
-          r = parse_callout_of_name(&condition, ')', &p, end, env);
+          r = prs_callout_of_name(&condition, ')', &p, end, env);
           if (r != 0) return r;
           goto end_condition;
         }
@@ -7730,7 +7816,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
           condition_is_checker = 0;
           r = fetch_token(tok, &p, end, env);
           if (r < 0) return r;
-          r = parse_alts(&condition, tok, term, &p, end, env, FALSE);
+          r = prs_alts(&condition, tok, term, &p, end, env, FALSE);
           if (r < 0) {
             onig_node_free(condition);
             return r;
@@ -7773,7 +7859,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
             onig_node_free(condition);
             return r;
           }
-          r = parse_alts(&target, tok, term, &p, end, env, TRUE);
+          r = prs_alts(&target, tok, term, &p, end, env, TRUE);
           if (r < 0) {
             onig_node_free(condition);
             onig_node_free(target);
@@ -7949,7 +8035,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
             env->options = option;
             r = fetch_token(tok, &p, end, env);
             if (r < 0) return r;
-            r = parse_alts(&target, tok, term, &p, end, env, FALSE);
+            r = prs_alts(&target, tok, term, &p, end, env, FALSE);
             env->options = prev;
             if (r < 0) {
               onig_node_free(target);
@@ -7976,7 +8062,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
   else if (c == '*' &&
            IS_SYNTAX_OP2(env->syntax, ONIG_SYN_OP2_ASTERISK_CALLOUT_NAME)) {
     PINC;
-    r = parse_callout_of_name(np, ')', &p, end, env);
+    r = prs_callout_of_name(np, ')', &p, end, env);
     if (r != 0) return r;
 
     goto end;
@@ -7996,7 +8082,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
   CHECK_NULL_RETURN_MEMERR(*np);
   r = fetch_token(tok, &p, end, env);
   if (r < 0) return r;
-  r = parse_alts(&target, tok, term, &p, end, env, FALSE);
+  r = prs_alts(&target, tok, term, &p, end, env, FALSE);
   if (r < 0) {
     onig_node_free(target);
     return r;
@@ -8006,7 +8092,7 @@ parse_bag(Node** np, PToken* tok, int term, UChar** src, UChar* end,
 
   if (NODE_TYPE(*np) == NODE_BAG) {
     if (BAG_(*np)->type == BAG_MEMORY) {
-      /* Don't move this to previous of parse_alts() */
+      /* Don't move this to previous of prs_alts() */
       r = scan_env_set_mem_node(env, BAG_(*np)->m.regnum, *np);
       if (r != 0) return r;
     }
@@ -8285,8 +8371,8 @@ i_apply_case_fold(OnigCodePoint from, OnigCodePoint to[], int to_len, void* arg)
 }
 
 static int
-parse_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
-          ScanEnv* env, int group_head)
+prs_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
+        ScanEnv* env, int group_head)
 {
   int r, len, group;
   Node* qn;
@@ -8311,7 +8397,7 @@ parse_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
   break;
 
   case TK_SUBEXP_OPEN:
-    r = parse_bag(np, tok, TK_SUBEXP_CLOSE, src, end, env);
+    r = prs_bag(np, tok, TK_SUBEXP_CLOSE, src, end, env);
     if (r < 0) return r;
     if (r == 1) { /* group */
       if (group_head == 0)
@@ -8341,7 +8427,7 @@ parse_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
         env->options = BAG_(*np)->o.options;
         r = fetch_token(tok, src, end, env);
         if (r < 0) return r;
-        r = parse_alts(&target, tok, term, src, end, env, FALSE);
+        r = prs_alts(&target, tok, term, src, end, env, FALSE);
         env->options = prev;
         if (r < 0) {
           onig_node_free(target);
@@ -8419,8 +8505,9 @@ parse_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
   case TK_CODE_POINT:
     {
       UChar buf[ONIGENC_CODE_TO_MBC_MAXLEN];
-      len = ONIGENC_CODE_TO_MBC(env->enc, tok->u.code, buf);
+      len = ONIGENC_CODE_TO_MBCLEN(env->enc, tok->u.code);
       if (len < 0) return len;
+      len = ONIGENC_CODE_TO_MBC(env->enc, tok->u.code, buf);
 #ifdef NUMBERED_CHAR_IS_NOT_CASE_AMBIG
       *np = node_new_str_crude(buf, buf + len, env->options);
 #else
@@ -8465,7 +8552,12 @@ parse_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
           *np = node_new_cclass();
           CHECK_NULL_RETURN_MEMERR(*np);
           cc = CCLASS_(*np);
-          add_ctype_to_cc(cc, tok->u.prop.ctype, FALSE, env);
+          r = add_ctype_to_cc(cc, tok->u.prop.ctype, FALSE, env);
+          if (r != 0) {
+            onig_node_free(*np);
+            *np = NULL_NODE;
+            return r;
+          }
           if (tok->u.prop.not != 0) NCCLASS_SET_NOT(cc);
         }
         break;
@@ -8478,7 +8570,7 @@ parse_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
     break;
 
   case TK_CHAR_PROPERTY:
-    r = parse_char_property(np, tok, src, end, env);
+    r = prs_char_property(np, tok, src, end, env);
     if (r != 0) return r;
     break;
 
@@ -8486,7 +8578,7 @@ parse_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
     {
       CClassNode* cc;
 
-      r = parse_cc(np, tok, src, end, env);
+      r = prs_cc(np, tok, src, end, env);
       if (r != 0) return r;
 
       cc = CCLASS_(*np);
@@ -8685,8 +8777,8 @@ parse_exp(Node** np, PToken* tok, int term, UChar** src, UChar* end,
 }
 
 static int
-parse_branch(Node** top, PToken* tok, int term, UChar** src, UChar* end,
-             ScanEnv* env, int group_head)
+prs_branch(Node** top, PToken* tok, int term, UChar** src, UChar* end,
+           ScanEnv* env, int group_head)
 {
   int r;
   Node *node, **headp;
@@ -8694,7 +8786,7 @@ parse_branch(Node** top, PToken* tok, int term, UChar** src, UChar* end,
   *top = NULL;
   INC_PARSE_DEPTH(env->parse_depth);
 
-  r = parse_exp(&node, tok, term, src, end, env, group_head);
+  r = prs_exp(&node, tok, term, src, end, env, group_head);
   if (r < 0) {
     onig_node_free(node);
     return r;
@@ -8712,7 +8804,7 @@ parse_branch(Node** top, PToken* tok, int term, UChar** src, UChar* end,
 
     headp = &(NODE_CDR(*top));
     while (r != TK_EOT && r != term && r != TK_ALT) {
-      r = parse_exp(&node, tok, term, src, end, env, FALSE);
+      r = prs_exp(&node, tok, term, src, end, env, FALSE);
       if (r < 0) {
         onig_node_free(node);
         return r;
@@ -8736,8 +8828,8 @@ parse_branch(Node** top, PToken* tok, int term, UChar** src, UChar* end,
 
 /* term_tok: TK_EOT or TK_SUBEXP_CLOSE */
 static int
-parse_alts(Node** top, PToken* tok, int term, UChar** src, UChar* end,
-           ScanEnv* env, int group_head)
+prs_alts(Node** top, PToken* tok, int term, UChar** src, UChar* end,
+         ScanEnv* env, int group_head)
 {
   int r;
   Node *node, **headp;
@@ -8747,7 +8839,7 @@ parse_alts(Node** top, PToken* tok, int term, UChar** src, UChar* end,
   INC_PARSE_DEPTH(env->parse_depth);
   save_options = env->options;
 
-  r = parse_branch(&node, tok, term, src, end, env, group_head);
+  r = prs_branch(&node, tok, term, src, end, env, group_head);
   if (r < 0) {
     onig_node_free(node);
     return r;
@@ -8767,7 +8859,7 @@ parse_alts(Node** top, PToken* tok, int term, UChar** src, UChar* end,
     while (r == TK_ALT) {
       r = fetch_token(tok, src, end, env);
       if (r < 0) return r;
-      r = parse_branch(&node, tok, term, src, end, env, FALSE);
+      r = prs_branch(&node, tok, term, src, end, env, FALSE);
       if (r < 0) {
         onig_node_free(node);
         return r;
@@ -8800,7 +8892,7 @@ parse_alts(Node** top, PToken* tok, int term, UChar** src, UChar* end,
 }
 
 static int
-parse_regexp(Node** top, UChar** src, UChar* end, ScanEnv* env)
+prs_regexp(Node** top, UChar** src, UChar* end, ScanEnv* env)
 {
   int r;
   PToken tok;
@@ -8808,7 +8900,7 @@ parse_regexp(Node** top, UChar** src, UChar* end, ScanEnv* env)
   ptoken_init(&tok);
   r = fetch_token(&tok, src, end, env);
   if (r < 0) return r;
-  r = parse_alts(top, &tok, TK_EOT, src, end, env, FALSE);
+  r = prs_alts(top, &tok, TK_EOT, src, end, env, FALSE);
   if (r < 0) return r;
 
   return 0;
@@ -8846,6 +8938,15 @@ onig_parse_tree(Node** root, const UChar* pattern, const UChar* end,
   RegexExt* ext;
 #endif
 
+  reg->string_pool        = 0;
+  reg->string_pool_end    = 0;
+  reg->num_mem            = 0;
+  reg->num_repeat         = 0;
+  reg->num_empty_check    = 0;
+  reg->repeat_range_alloc = 0;
+  reg->repeat_range       = (RepeatRange* )NULL;
+  reg->empty_status_mem   = 0;
+
   names_clear(reg);
 
   scan_env_clear(env);
@@ -8863,7 +8964,7 @@ onig_parse_tree(Node** root, const UChar* pattern, const UChar* end,
     return ONIGERR_INVALID_WIDE_CHAR_VALUE;
 
   p = (UChar* )pattern;
-  r = parse_regexp(root, &p, (UChar* )end, env);
+  r = prs_regexp(root, &p, (UChar* )end, env);
   if (r != 0) return r;
 
 #ifdef USE_CALL
diff --git a/src/regparse.h b/src/regparse.h
index 979e982..c60a42d 100644
--- a/src/regparse.h
+++ b/src/regparse.h
@@ -163,7 +163,7 @@ typedef struct {
   struct _Node* body; /* to BagNode : BAG_MEMORY */
 
   int     by_number;
-  int     group_num;
+  int     called_gnum;
   UChar*  name;
   UChar*  name_end;
   int     entry_count;
@@ -339,6 +339,7 @@ typedef struct {
 #define NODE_ST_TEXT_SEGMENT_WORD   (1<<23)
 #define NODE_ST_ABSENT_WITH_SIDE_EFFECTS (1<<24)  /* stopper or clear */
 #define NODE_ST_FIXED_CLEN_MIN_SURE (1<<25)
+#define NODE_ST_REFERENCED          (1<<26)
 
 
 #define NODE_STATUS(node)           (((Node* )node)->u.base.status)
@@ -374,6 +375,7 @@ typedef struct {
 #define NODE_IS_TEXT_SEGMENT_WORD(node)  ((NODE_STATUS(node) & NODE_ST_TEXT_SEGMENT_WORD) != 0)
 #define NODE_IS_ABSENT_WITH_SIDE_EFFECTS(node)  ((NODE_STATUS(node) & NODE_ST_ABSENT_WITH_SIDE_EFFECTS) != 0)
 #define NODE_IS_FIXED_CLEN_MIN_SURE(node)  ((NODE_STATUS(node) & NODE_ST_FIXED_CLEN_MIN_SURE) != 0)
+#define NODE_IS_REFERENCED(node)      ((NODE_STATUS(node) & NODE_ST_REFERENCED) != 0)
 
 #define NODE_PARENT(node)         ((node)->u.base.parent)
 #define NODE_BODY(node)           ((node)->u.base.body)
diff --git a/src/regposerr.c b/src/regposerr.c
index 12d95a9..e5b7899 100644
--- a/src/regposerr.c
+++ b/src/regposerr.c
@@ -37,6 +37,18 @@
 #include "config.h"
 #include "onigposix.h"
 
+#undef regex_t
+#undef regmatch_t
+#undef regoff_t
+#undef regcomp
+#undef regexec
+#undef regfree
+#undef regerror
+#undef reg_set_encoding
+#undef reg_name_to_group_numbers
+#undef reg_foreach_name
+#undef reg_number_of_names
+
 #ifndef ONIG_NO_STANDARD_C_HEADERS
 #include <string.h>
 #include <stdio.h>
@@ -92,10 +104,9 @@ static char* ESTRING[] = {
 };
 
 
-
 extern size_t
-regerror(int posix_ecode, const regex_t* reg ARG_UNUSED, char* buf,
-         size_t size)
+onig_posix_regerror(int posix_ecode, const onig_posix_regex_t* reg ARG_UNUSED,
+                    char* buf, size_t size)
 {
   char* s;
   char tbuf[35];
@@ -121,3 +132,14 @@ regerror(int posix_ecode, const regex_t* reg ARG_UNUSED, char* buf,
   }
   return len;
 }
+
+#ifdef USE_BINARY_COMPATIBLE_POSIX_API
+
+extern size_t
+regerror(int posix_ecode, const onig_posix_regex_t* reg ARG_UNUSED,
+         char* buf, size_t size)
+{
+  return onig_posix_regerror(posix_ecode, reg, buf, size);
+}
+
+#endif
diff --git a/src/regposix.c b/src/regposix.c
index 4e523a4..497ba02 100644
--- a/src/regposix.c
+++ b/src/regposix.c
@@ -33,6 +33,18 @@
 
 #include "onigposix.h"
 
+#undef regex_t
+#undef regmatch_t
+#undef regoff_t
+#undef regcomp
+#undef regexec
+#undef regfree
+#undef regerror
+#undef reg_set_encoding
+#undef reg_name_to_group_numbers
+#undef reg_foreach_name
+#undef reg_number_of_names
+
 #define ONIG_C(reg)    ((onig_regex_t* )((reg)->onig))
 #define PONIG_C(reg)   ((onig_regex_t** )(&(reg)->onig))
 
@@ -64,6 +76,7 @@ onig2posix_error_code(int code)
     { ONIGERR_MATCH_STACK_LIMIT_OVER,                     REG_EONIG_INTERNAL },
     { ONIGERR_RETRY_LIMIT_IN_MATCH_OVER,                  REG_EONIG_INTERNAL },
     { ONIGERR_RETRY_LIMIT_IN_SEARCH_OVER,                 REG_EONIG_INTERNAL },
+    { ONIGERR_SUBEXP_CALL_LIMIT_IN_SEARCH_OVER,           REG_EONIG_INTERNAL },
     { ONIGERR_TYPE_BUG,                                   REG_EONIG_INTERNAL },
     { ONIGERR_PARSER_BUG,                                 REG_EONIG_INTERNAL },
     { ONIGERR_STACK_BUG,                                  REG_EONIG_INTERNAL },
@@ -144,7 +157,7 @@ onig2posix_error_code(int code)
 }
 
 extern int
-regcomp(regex_t* reg, const char* pattern, int posix_options)
+onig_posix_regcomp(onig_posix_regex_t* reg, const char* pattern, int posix_options)
 {
   int r, len;
   OnigSyntaxType* syntax = OnigDefaultSyntax;
@@ -178,12 +191,12 @@ regcomp(regex_t* reg, const char* pattern, int posix_options)
 }
 
 extern int
-regexec(regex_t* reg, const char* str, size_t nmatch,
-        regmatch_t pmatch[], int posix_options)
+onig_posix_regexec(onig_posix_regex_t* reg, const char* str, size_t nmatch,
+                   onig_posix_regmatch_t pmatch[], int posix_options)
 {
   int r, i, len;
   UChar* end;
-  regmatch_t* pm;
+  onig_posix_regmatch_t* pm;
   OnigOptionType options;
 
   options = ONIG_OPTION_POSIX_REGION;
@@ -191,11 +204,11 @@ regexec(regex_t* reg, const char* str, size_t nmatch,
   if ((posix_options & REG_NOTEOL) != 0) options |= ONIG_OPTION_NOTEOL;
 
   if (nmatch == 0 || (reg->comp_options & REG_NOSUB) != 0) {
-    pm = (regmatch_t* )NULL;
+    pm = (onig_posix_regmatch_t* )NULL;
     nmatch = 0;
   }
   else if ((int )nmatch < ONIG_C(reg)->num_mem + 1) {
-    pm = (regmatch_t* )xmalloc(sizeof(regmatch_t)
+    pm = (onig_posix_regmatch_t* )xmalloc(sizeof(onig_posix_regmatch_t)
                                * (ONIG_C(reg)->num_mem + 1));
     if (pm == NULL)
       return REG_ESPACE;
@@ -212,7 +225,7 @@ regexec(regex_t* reg, const char* str, size_t nmatch,
   if (r >= 0) {
     r = 0; /* Match */
     if (pm != pmatch && pm != NULL) {
-      xmemcpy(pmatch, pm, sizeof(regmatch_t) * nmatch);
+      xmemcpy(pmatch, pm, sizeof(onig_posix_regmatch_t) * nmatch);
     }
   }
   else if (r == ONIG_MISMATCH) {
@@ -236,7 +249,7 @@ regexec(regex_t* reg, const char* str, size_t nmatch,
 }
 
 extern void
-regfree(regex_t* reg)
+onig_posix_regfree(onig_posix_regex_t* reg)
 {
   onig_free(ONIG_C(reg));
   reg->onig = (void* )0;
@@ -244,7 +257,7 @@ regfree(regex_t* reg)
 
 
 extern void
-reg_set_encoding(int mb_code)
+onig_posix_reg_set_encoding(int mb_code)
 {
   OnigEncoding enc;
 
@@ -279,15 +292,15 @@ reg_set_encoding(int mb_code)
 }
 
 extern int
-reg_name_to_group_numbers(regex_t* reg,
+onig_posix_reg_name_to_group_numbers(onig_posix_regex_t* reg,
   const unsigned char* name, const unsigned char* name_end, int** nums)
 {
   return onig_name_to_group_numbers(ONIG_C(reg), name, name_end, nums);
 }
 
 typedef struct {
-  int (*func)(const unsigned char*, const unsigned char*,int,int*,regex_t*,void*);
-  regex_t* reg;
+  int (*func)(const unsigned char*, const unsigned char*,int,int*,onig_posix_regex_t*,void*);
+  onig_posix_regex_t* reg;
   void* arg;
 } i_wrap;
 
@@ -301,8 +314,8 @@ i_wrapper(const UChar* name, const UChar* name_end, int ng, int* gs,
 }
 
 extern int
-reg_foreach_name(regex_t* reg,
- int (*func)(const unsigned char*, const unsigned char*,int,int*,regex_t*,void*),
+onig_posix_reg_foreach_name(onig_posix_regex_t* reg,
+ int (*func)(const unsigned char*, const unsigned char*,int,int*,onig_posix_regex_t*,void*),
  void* arg)
 {
   i_wrap warg;
@@ -315,7 +328,58 @@ reg_foreach_name(regex_t* reg,
 }
 
 extern int
-reg_number_of_names(regex_t* reg)
+onig_posix_reg_number_of_names(onig_posix_regex_t* reg)
 {
   return onig_number_of_names(ONIG_C(reg));
 }
+
+
+#ifdef USE_BINARY_COMPATIBLE_POSIX_API
+
+extern int
+regcomp(onig_posix_regex_t* reg, const char* pattern, int posix_options)
+{
+  return onig_posix_regcomp(reg, pattern, posix_options);
+}
+
+extern int
+regexec(onig_posix_regex_t* reg, const char* str, size_t nmatch,
+        onig_posix_regmatch_t pmatch[], int posix_options)
+{
+  return onig_posix_regexec(reg, str, nmatch, pmatch, posix_options);
+}
+
+extern void
+regfree(onig_posix_regex_t* reg)
+{
+  onig_posix_regfree(reg);
+}
+
+extern void
+reg_set_encoding(int mb_code)
+{
+  onig_posix_reg_set_encoding(mb_code);
+}
+
+extern int
+reg_name_to_group_numbers(onig_posix_regex_t* reg,
+  const unsigned char* name, const unsigned char* name_end, int** nums)
+{
+  return onig_posix_reg_name_to_group_numbers(reg, name, name_end, nums);
+}
+
+extern int
+reg_foreach_name(onig_posix_regex_t* reg,
+  int (*func)(const unsigned char*, const unsigned char*,int,int*,onig_posix_regex_t*,void*),
+  void* arg)
+{
+  return onig_posix_reg_foreach_name(reg, func, arg);
+}
+
+extern int
+reg_number_of_names(onig_posix_regex_t* reg)
+{
+  return onig_posix_reg_number_of_names(reg);
+}
+
+#endif /* USE_BINARY_COMPATIBLE_POSIX_API */
diff --git a/src/sjis.c b/src/sjis.c
index 1fd92d9..10afd9d 100644
--- a/src/sjis.c
+++ b/src/sjis.c
@@ -2,7 +2,7 @@
   sjis.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -113,13 +113,15 @@ static int
 code_to_mbclen(OnigCodePoint code)
 {
   if (code < 256) {
-    return EncLen_SJIS[(int )code] == 1;
+    if (EncLen_SJIS[(int )code] == 1)
+      return 1;
   }
-  else if (code <= 0xffff) {
-    return 2;
+  else if (code < 0x10000) {
+    if (EncLen_SJIS[(int )(code >>  8) & 0xff] == 2)
+      return 2;
   }
-  else
-    return ONIGERR_INVALID_CODE_POINT_VALUE;
+
+  return ONIGERR_INVALID_CODE_POINT_VALUE;
 }
 
 static OnigCodePoint
diff --git a/src/st.c b/src/st.c
index 522f205..8ee610b 100644
--- a/src/st.c
+++ b/src/st.c
@@ -151,6 +151,7 @@ st_init_table_with_size(type, size)
 #endif
 
   size = new_size(size);	/* round up to prime number */
+  if (size <= 0) return 0;
 
   tbl = alloc(st_table);
   if (tbl == 0) return 0;
@@ -318,10 +319,13 @@ rehash(table)
      register st_table *table;
 {
   register st_table_entry *ptr, *next, **new_bins;
-  int i, old_num_bins = table->num_bins, new_num_bins;
+  int i, new_num_bins, old_num_bins;
   unsigned int hash_val;
 
-  new_num_bins = new_size(old_num_bins+1);
+  old_num_bins = table->num_bins;
+  new_num_bins = new_size(old_num_bins + 1);
+  if (new_num_bins <= 0) return ;
+
   new_bins = (st_table_entry**)Calloc(new_num_bins, sizeof(st_table_entry*));
   if (new_bins == 0) {
     return ;
diff --git a/src/unicode.c b/src/unicode.c
index 080da74..6703d4b 100644
--- a/src/unicode.c
+++ b/src/unicode.c
@@ -387,15 +387,15 @@ onigenc_unicode_get_case_fold_codes_by_str(OnigEncoding enc,
         for (i = 0; i < ncs[0]; i++) {
           for (j = 0; j < ncs[1]; j++) {
             for (k = 0; k < ncs[2]; k++) {
+              if (cs[0][i] == orig_codes[0] && cs[1][j] == orig_codes[1] &&
+                  cs[2][k] == orig_codes[2])
+                continue;
+
               items[n].byte_len = lens[2];
               items[n].code_len = 3;
               items[n].code[0]  = cs[0][i];
               items[n].code[1]  = cs[1][j];
               items[n].code[2]  = cs[2][k];
-              if (items[n].code[0] == orig_codes[0] &&
-                  items[n].code[1] == orig_codes[1] &&
-                  items[n].code[2] == orig_codes[2])
-                continue;
               n++;
             }
           }
@@ -431,13 +431,12 @@ onigenc_unicode_get_case_fold_codes_by_str(OnigEncoding enc,
 
       for (i = 0; i < ncs[0]; i++) {
         for (j = 0; j < ncs[1]; j++) {
+          if (cs[0][i] == orig_codes[0] && cs[1][j] == orig_codes[1])
+            continue;
           items[n].byte_len = lens[1];
           items[n].code_len = 2;
           items[n].code[0]  = cs[0][i];
           items[n].code[1]  = cs[1][j];
-          if (items[n].code[0] == orig_codes[0] &&
-              items[n].code[1] == orig_codes[1])
-            continue;
           n++;
         }
       }
diff --git a/src/utf16_be.c b/src/utf16_be.c
index d237b93..5014e18 100644
--- a/src/utf16_be.c
+++ b/src/utf16_be.c
@@ -2,7 +2,7 @@
   utf16_be.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
diff --git a/src/utf16_le.c b/src/utf16_le.c
index f14d263..35ceb3c 100644
--- a/src/utf16_le.c
+++ b/src/utf16_le.c
@@ -2,7 +2,7 @@
   utf16_le.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
diff --git a/src/utf32_be.c b/src/utf32_be.c
index bdd3db7..31bd98b 100644
--- a/src/utf32_be.c
+++ b/src/utf32_be.c
@@ -2,7 +2,7 @@
   utf32_be.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -67,7 +67,10 @@ utf32be_is_mbc_newline(const UChar* p, const UChar* end)
 static OnigCodePoint
 utf32be_mbc_to_code(const UChar* p, const UChar* end ARG_UNUSED)
 {
-  return (OnigCodePoint )(((p[0] * 256 + p[1]) * 256 + p[2]) * 256 + p[3]);
+  OnigCodePoint code;
+
+  code = (OnigCodePoint )((((p[0] & 0x7f) * 256 + p[1]) * 256 + p[2]) * 256 + p[3]);
+  return code;
 }
 
 static int
diff --git a/src/utf32_le.c b/src/utf32_le.c
index 473ab74..f50cab7 100644
--- a/src/utf32_le.c
+++ b/src/utf32_le.c
@@ -2,7 +2,7 @@
   utf32_le.c -  Oniguruma (regular expression library)
 **********************************************************************/
 /*-
- * Copyright (c) 2002-2019  K.Kosako
+ * Copyright (c) 2002-2020  K.Kosako
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -67,7 +67,10 @@ utf32le_is_mbc_newline(const UChar* p, const UChar* end)
 static OnigCodePoint
 utf32le_mbc_to_code(const UChar* p, const UChar* end ARG_UNUSED)
 {
-  return (OnigCodePoint )(((p[3] * 256 + p[2]) * 256 + p[1]) * 256 + p[0]);
+  OnigCodePoint code;
+
+  code = (OnigCodePoint )((((p[3] & 0x7f) * 256 + p[2]) * 256 + p[1]) * 256 + p[0]);
+  return code;
 }
 
 static int