Adding const qualifiers

Message-ID: <20050313202005.GA23535@petdance.com>

p4raw-id: //depot/perl@24037

11 files changed, 135 insertions, 147 deletions

diff --git a/av.c b/av.c
index b616a209ee..df2cf23833 100644
--- a/av.c
+++ b/av.c
@@ -193,7 +193,7 @@ Perl_av_fetch(pTHX_ register AV *av, I32 key, I32 lval)
 	return 0;
 
     if (SvRMAGICAL(av)) {
-        MAGIC *tied_magic = mg_find((SV*)av, PERL_MAGIC_tied);
+        const MAGIC * const tied_magic = mg_find((SV*)av, PERL_MAGIC_tied);
         if (tied_magic || mg_find((SV*)av, PERL_MAGIC_regdata)) {
             U32 adjust_index = 1;
 
@@ -281,7 +281,7 @@ Perl_av_store(pTHX_ register AV *av, I32 key, SV *val)
 	val = &PL_sv_undef;
 
     if (SvRMAGICAL(av)) {
-        MAGIC *tied_magic = mg_find((SV*)av, PERL_MAGIC_tied);
+        const MAGIC * const tied_magic = mg_find((SV*)av, PERL_MAGIC_tied);
         if (tied_magic) {
             /* Handle negative array indices 20020222 MJD */
             if (key < 0) {
@@ -723,7 +723,7 @@ empty.
 */
 
 I32
-Perl_av_len(pTHX_ register AV *av)
+Perl_av_len(pTHX_ const register AV *av)
 {
     return AvFILL(av);
 }
@@ -803,10 +803,10 @@ Perl_av_delete(pTHX_ AV *av, I32 key, I32 flags)
 	Perl_croak(aTHX_ PL_no_modify);
 
     if (SvRMAGICAL(av)) {
-        MAGIC *tied_magic = mg_find((SV*)av, PERL_MAGIC_tied);
-        SV **svp;
+        const MAGIC * const tied_magic = mg_find((SV*)av, PERL_MAGIC_tied);
         if ((tied_magic || mg_find((SV*)av, PERL_MAGIC_regdata))) {
             /* Handle negative array indices 20020222 MJD */
+            SV **svp;
             if (key < 0) {
                 unsigned adjust_index = 1;
                 if (tied_magic) {
@@ -887,7 +887,7 @@ Perl_av_exists(pTHX_ AV *av, I32 key)
 
 
     if (SvRMAGICAL(av)) {
-        MAGIC *tied_magic = mg_find((SV*)av, PERL_MAGIC_tied);
+        const MAGIC * const tied_magic = mg_find((SV*)av, PERL_MAGIC_tied);
         if (tied_magic || mg_find((SV*)av, PERL_MAGIC_regdata)) {
             SV *sv = sv_newmortal();
             MAGIC *mg;
diff --git a/embed.fnc b/embed.fnc
index fc400eef3a..36588814c4 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -90,7 +90,7 @@ Apd	|void	|av_extend	|AV* ar|I32 key
 p	|AV*	|av_fake	|I32 size|SV** svp
 Apd	|SV**	|av_fetch	|AV* ar|I32 key|I32 lval
 Apd	|void	|av_fill	|AV* ar|I32 fill
-Apd	|I32	|av_len		|AV* ar
+Apd	|I32	|av_len		|const AV* ar
 Apd	|AV*	|av_make	|I32 size|SV** svp
 Apd	|SV*	|av_pop		|AV* ar
 Apd	|void	|av_push	|AV* ar|SV* val
@@ -134,7 +134,7 @@ Afnp	|void	|sv_setpvf_mg_nocontext|SV* sv|const char* pat|...
 Afnp	|int	|fprintf_nocontext|PerlIO* stream|const char* fmt|...
 Afnp	|int	|printf_nocontext|const char* fmt|...
 #endif
-p	|void	|cv_ckproto	|CV* cv|GV* gv|char* p
+p	|void	|cv_ckproto	|const CV* cv|const GV* gv|const char* p
 pd	|CV*	|cv_clone	|CV* proto
 Apd	|SV*	|cv_const_sv	|CV* cv
 p	|SV*	|op_const_sv	|OP* o|CV* cv
@@ -161,7 +161,7 @@ p	|void	|deprecate	|char* s
 p	|void	|deprecate_old	|char* s
 Afp	|OP*	|die		|const char* pat|...
 p	|OP*	|vdie		|const char* pat|va_list* args
-p	|OP*	|die_where	|char* message|STRLEN msglen
+p	|OP*	|die_where	|const char* message|STRLEN msglen
 Ap	|void	|dounwind	|I32 cxix
 p	|bool	|do_aexec	|SV* really|SV** mark|SV** sp
 p	|bool	|do_aexec5	|SV* really|SV** mark|SV** sp|int fd|int flag
@@ -244,9 +244,9 @@ Ap	|GV*	|gv_IOadd	|GV* gv
 Ap	|GV*	|gv_autoload4	|HV* stash|const char* name|STRLEN len \
 				|I32 method
 Ap	|void	|gv_check	|HV* stash
-Ap	|void	|gv_efullname	|SV* sv|GV* gv
-Amb	|void	|gv_efullname3	|SV* sv|GV* gv|const char* prefix
-Ap	|void	|gv_efullname4	|SV* sv|GV* gv|const char* prefix|bool keepmain
+Ap	|void	|gv_efullname	|SV* sv|const GV* gv
+Amb	|void	|gv_efullname3	|SV* sv|const GV* gv|const char* prefix
+Ap	|void	|gv_efullname4	|SV* sv|const GV* gv|const char* prefix|bool keepmain
 Ap	|GV*	|gv_fetchfile	|const char* name
 Apd	|GV*	|gv_fetchmeth	|HV* stash|const char* name|STRLEN len \
 				|I32 level
@@ -256,9 +256,9 @@ Apd	|GV*	|gv_fetchmethod	|HV* stash|const char* name
 Apd	|GV*	|gv_fetchmethod_autoload|HV* stash|const char* name \
 				|I32 autoload
 Ap	|GV*	|gv_fetchpv	|const char* name|I32 add|I32 sv_type
-Ap	|void	|gv_fullname	|SV* sv|GV* gv
-Amb	|void	|gv_fullname3	|SV* sv|GV* gv|const char* prefix
-Ap	|void	|gv_fullname4	|SV* sv|GV* gv|const char* prefix|bool keepmain
+Ap	|void	|gv_fullname	|SV* sv|const GV* gv
+Amb	|void	|gv_fullname3	|SV* sv|const GV* gv|const char* prefix
+Ap	|void	|gv_fullname4	|SV* sv|const GV* gv|const char* prefix|bool keepmain
 Ap	|void	|gv_init	|GV* gv|HV* stash|const char* name \
 				|STRLEN len|int multi
 Apd	|HV*	|gv_stashpv	|const char* name|I32 create
@@ -439,7 +439,7 @@ p	|void	|qerror		|SV* err
 Apd     |void   |sortsv         |SV ** array|size_t num_elts|SVCOMPARE_t cmp
 Apd	|int	|mg_clear	|SV* sv
 Apd	|int	|mg_copy	|SV* sv|SV* nsv|const char* key|I32 klen
-Apd	|MAGIC*	|mg_find	|SV* sv|int type
+Apd	|MAGIC*	|mg_find	|const SV* sv|int type
 Apd	|int	|mg_free	|SV* sv
 Apd	|int	|mg_get		|SV* sv
 Apd	|U32	|mg_length	|SV* sv
@@ -637,7 +637,7 @@ Apd	|char*	|savesharedpv	|const char* pv
 Apd	|char*	|savepvn	|const char* pv|I32 len
 Ap	|void	|savestack_grow
 Ap	|void	|savestack_grow_cnt	|I32 need
-Ap	|void	|save_aelem	|AV* av|I32 idx|SV **sptr
+Ap	|void	|save_aelem	|const AV* av|I32 idx|SV **sptr
 Ap	|I32	|save_alloc	|I32 size|I32 pad
 Ap	|void	|save_aptr	|AV** aptr
 Ap	|AV*	|save_ary	|GV* gv
@@ -654,7 +654,7 @@ Ap	|void	|save_generic_pvref|char** str
 Ap	|void	|save_shared_pvref|char** str
 Ap	|void	|save_gp	|GV* gv|I32 empty
 Ap	|HV*	|save_hash	|GV* gv
-Ap	|void	|save_helem	|HV* hv|SV *key|SV **sptr
+Ap	|void	|save_helem	|const HV* hv|SV *key|SV **sptr
 Ap	|void	|save_hints
 Ap	|void	|save_hptr	|HV** hptr
 Ap	|void	|save_I16	|I16* intp
@@ -824,12 +824,12 @@ p	|void	|unshare_hek	|HEK* hek
 p	|void	|utilize	|int aver|I32 floor|OP* version|OP* idop|OP* arg
 Ap	|U8*	|utf16_to_utf8	|U8* p|U8 *d|I32 bytelen|I32 *newlen
 Ap	|U8*	|utf16_to_utf8_reversed|U8* p|U8 *d|I32 bytelen|I32 *newlen
-Adp	|STRLEN	|utf8_length	|U8* s|U8 *e
-Apd	|IV	|utf8_distance	|U8 *a|U8 *b
+Adp	|STRLEN	|utf8_length	|const U8* s|const U8 *e
+Apd	|IV	|utf8_distance	|const U8 *a|const U8 *b
 Apd	|U8*	|utf8_hop	|U8 *s|I32 off
 ApMd	|U8*	|utf8_to_bytes	|U8 *s|STRLEN *len
 ApMd	|U8*	|bytes_from_utf8|U8 *s|STRLEN *len|bool *is_utf8
-ApMd	|U8*	|bytes_to_utf8	|U8 *s|STRLEN *len
+ApMd	|U8*	|bytes_to_utf8	|const U8 *s|STRLEN *len
 Apd	|UV	|utf8_to_uvchr	|U8 *s|STRLEN* retlen
 Apd	|UV	|utf8_to_uvuni	|U8 *s|STRLEN* retlen
 Adp	|UV	|utf8n_to_uvchr	|U8 *s|STRLEN curlen|STRLEN* retlen|U32 flags
@@ -854,7 +854,7 @@ Ap	|void	|vwarn		|const char* pat|va_list* args
 Afp	|void	|warner		|U32 err|const char* pat|...
 Ap	|void	|vwarner	|U32 err|const char* pat|va_list* args
 p	|void	|watch		|char** addr
-Ap	|I32	|whichsig	|char* sig
+Ap	|I32	|whichsig	|const char* sig
 p	|void	|write_to_stderr|const char* message|int msglen
 p	|int	|yyerror	|char* s
 p	|int	|yylex
diff --git a/gv.c b/gv.c
index 83ec0eed2a..3ff41767c7 100644
--- a/gv.c
+++ b/gv.c
@@ -1102,7 +1102,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	break;
 	case '\026':	/* $^V */
 	{
-	    SV *sv = GvSV(gv);
+	    SV * const sv = GvSV(gv);
 	    GvSV(gv) = new_version(PL_patchlevel);
 	    SvREADONLY_on(GvSV(gv));
 	    SvREFCNT_dec(sv);
@@ -1114,10 +1114,10 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 }
 
 void
-Perl_gv_fullname4(pTHX_ SV *sv, GV *gv, const char *prefix, bool keepmain)
+Perl_gv_fullname4(pTHX_ SV *sv, const GV *gv, const char *prefix, bool keepmain)
 {
-    char *name;
-    HV *hv = GvSTASH(gv);
+    const char *name;
+    const HV * const hv = GvSTASH(gv);
     if (!hv) {
 	SvOK_off(sv);
 	return;
@@ -1136,36 +1136,36 @@ Perl_gv_fullname4(pTHX_ SV *sv, GV *gv, const char *prefix, bool keepmain)
 }
 
 void
-Perl_gv_fullname3(pTHX_ SV *sv, GV *gv, const char *prefix)
+Perl_gv_fullname3(pTHX_ SV *sv, const GV *gv, const char *prefix)
 {
     gv_fullname4(sv, gv, prefix, TRUE);
 }
 
 void
-Perl_gv_efullname4(pTHX_ SV *sv, GV *gv, const char *prefix, bool keepmain)
+Perl_gv_efullname4(pTHX_ SV *sv, const GV *gv, const char *prefix, bool keepmain)
 {
-    GV *egv = GvEGV(gv);
+    const GV *egv = GvEGV(gv);
     if (!egv)
 	egv = gv;
     gv_fullname4(sv, egv, prefix, keepmain);
 }
 
 void
-Perl_gv_efullname3(pTHX_ SV *sv, GV *gv, const char *prefix)
+Perl_gv_efullname3(pTHX_ SV *sv, const GV *gv, const char *prefix)
 {
     gv_efullname4(sv, gv, prefix, TRUE);
 }
 
-/* XXX compatibility with versions <= 5.003. */
+/* compatibility with versions <= 5.003. */
 void
-Perl_gv_fullname(pTHX_ SV *sv, GV *gv)
+Perl_gv_fullname(pTHX_ SV *sv, const GV *gv)
 {
-    gv_fullname3(sv, gv, sv == (SV*)gv ? "*" : "");
+    gv_fullname3(sv, gv, sv == (const SV*)gv ? "*" : "");
 }
 
-/* XXX compatibility with versions <= 5.003. */
+/* compatibility with versions <= 5.003. */
 void
-Perl_gv_efullname(pTHX_ SV *sv, GV *gv)
+Perl_gv_efullname(pTHX_ SV *sv, const GV *gv)
 {
     gv_efullname3(sv, gv, sv == (SV*)gv ? "*" : "");
 }
diff --git a/hv.c b/hv.c
index bb8cef6e0d..58fd5fc354 100644
--- a/hv.c
+++ b/hv.c
@@ -90,7 +90,7 @@ S_more_he(pTHX)
 STATIC HEK *
 S_save_hek_flags(pTHX_ const char *str, I32 len, U32 hash, int flags)
 {
-    int flags_masked = flags & HVhek_MASK;
+    const int flags_masked = flags & HVhek_MASK;
     char *k;
     register HEK *hek;
 
@@ -1999,7 +1999,7 @@ S_unshare_hek_or_pvn(pTHX_ HEK *hek, const char *str, I32 len, U32 hash)
             break;
         }
     } else {
-        int flags_masked = k_flags & HVhek_MASK;
+        const int flags_masked = k_flags & HVhek_MASK;
         for (entry = *oentry; entry; i=0, oentry = &HeNEXT(entry), entry = *oentry) {
             if (HeHASH(entry) != hash)		/* strings can't be equal */
                 continue;
@@ -2075,7 +2075,7 @@ S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags)
     register HE **oentry;
     register I32 i = 1;
     I32 found = 0;
-    int flags_masked = flags & HVhek_MASK;
+    const int flags_masked = flags & HVhek_MASK;
 
     /* what follows is the moral equivalent of:
 
diff --git a/mg.c b/mg.c
index c24bf6de73..6cd1c6fcc3 100644
--- a/mg.c
+++ b/mg.c
@@ -63,8 +63,8 @@ Signal_t Perl_csighandler(int sig);
 #  define  FAKE_DEFAULT_SIGNAL_HANDLERS
 #endif
 
-static void restore_magic(pTHX_ void *p);
-static void unwind_handler_stack(pTHX_ void *p);
+static void restore_magic(pTHX_ const void *p);
+static void unwind_handler_stack(pTHX_ const void *p);
 
 #ifdef __Lynx__
 /* Missing protos on LynxOS */
@@ -121,7 +121,7 @@ Perl_mg_magical(pTHX_ SV *sv)
 {
     MAGIC* mg;
     for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
-	MGVTBL* vtbl = mg->mg_virtual;
+	const MGVTBL* const vtbl = mg->mg_virtual;
 	if (vtbl) {
 	    if (vtbl->svt_get && !(mg->mg_flags & MGf_GSKIP))
 		SvGMAGICAL_on(sv);
@@ -144,10 +144,10 @@ Do magic after a value is retrieved from the SV.  See C<sv_magic>.
 int
 Perl_mg_get(pTHX_ SV *sv)
 {
+    const I32 mgs_ix = SSNEW(sizeof(MGS));
+    const bool was_temp = SvTEMP(sv);
     int new = 0;
     MAGIC *newmg, *head, *cur, *mg;
-    I32 mgs_ix = SSNEW(sizeof(MGS));
-    int was_temp = SvTEMP(sv);
     /* guard against sv having being freed midway by holding a private
        reference. */
 
@@ -168,7 +168,7 @@ Perl_mg_get(pTHX_ SV *sv)
 
     newmg = cur = head = mg = SvMAGIC(sv);
     while (mg) {
-	MGVTBL *vtbl = mg->mg_virtual;
+	const MGVTBL * const vtbl = mg->mg_virtual;
 
 	if (!(mg->mg_flags & MGf_GSKIP) && vtbl && vtbl->svt_get) {
 	    CALL_FPTR(vtbl->svt_get)(aTHX_ sv, mg);
@@ -224,11 +224,10 @@ Do magic after a value is assigned to the SV.  See C<sv_magic>.
 int
 Perl_mg_set(pTHX_ SV *sv)
 {
-    I32 mgs_ix;
+    const I32 mgs_ix = SSNEW(sizeof(MGS));
     MAGIC* mg;
     MAGIC* nextmg;
 
-    mgs_ix = SSNEW(sizeof(MGS));
     save_magic(mgs_ix, sv);
 
     for (mg = SvMAGIC(sv); mg; mg = nextmg) {
@@ -261,11 +260,9 @@ Perl_mg_length(pTHX_ SV *sv)
     STRLEN len;
 
     for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
-	MGVTBL* vtbl = mg->mg_virtual;
+        const MGVTBL * const vtbl = mg->mg_virtual;
 	if (vtbl && vtbl->svt_len) {
-            I32 mgs_ix;
-
-	    mgs_ix = SSNEW(sizeof(MGS));
+            const I32 mgs_ix = SSNEW(sizeof(MGS));
 	    save_magic(mgs_ix, sv);
 	    /* omit MGf_GSKIP -- not changed here */
 	    len = CALL_FPTR(vtbl->svt_len)(aTHX_ sv, mg);
@@ -274,8 +271,7 @@ Perl_mg_length(pTHX_ SV *sv)
 	}
     }
 
-    if (DO_UTF8(sv))
-    {
+    if (DO_UTF8(sv)) {
         U8 *s = (U8*)SvPV(sv, len);
         len = Perl_utf8_length(aTHX_ s, s + len);
     }
@@ -288,14 +284,12 @@ I32
 Perl_mg_size(pTHX_ SV *sv)
 {
     MAGIC* mg;
-    I32 len;
 
     for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
-	MGVTBL* vtbl = mg->mg_virtual;
+        const MGVTBL* const vtbl = mg->mg_virtual;
 	if (vtbl && vtbl->svt_len) {
-            I32 mgs_ix;
-
-	    mgs_ix = SSNEW(sizeof(MGS));
+            const I32 mgs_ix = SSNEW(sizeof(MGS));
+            I32 len;
 	    save_magic(mgs_ix, sv);
 	    /* omit MGf_GSKIP -- not changed here */
 	    len = CALL_FPTR(vtbl->svt_len)(aTHX_ sv, mg);
@@ -306,8 +300,7 @@ Perl_mg_size(pTHX_ SV *sv)
 
     switch(SvTYPE(sv)) {
 	case SVt_PVAV:
-	    len = AvFILLp((AV *) sv); /* Fallback to non-tied array */
-	    return len;
+	    return AvFILLp((AV *) sv); /* Fallback to non-tied array */
 	case SVt_PVHV:
 	    /* FIXME */
 	default:
@@ -328,14 +321,13 @@ Clear something magical that the SV represents.  See C<sv_magic>.
 int
 Perl_mg_clear(pTHX_ SV *sv)
 {
-    I32 mgs_ix;
+    const I32 mgs_ix = SSNEW(sizeof(MGS));
     MAGIC* mg;
 
-    mgs_ix = SSNEW(sizeof(MGS));
     save_magic(mgs_ix, sv);
 
     for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
-	MGVTBL* vtbl = mg->mg_virtual;
+        const MGVTBL* const vtbl = mg->mg_virtual;
 	/* omit GSKIP -- never set here */
 
 	if (vtbl && vtbl->svt_clear)
@@ -355,14 +347,14 @@ Finds the magic pointer for type matching the SV.  See C<sv_magic>.
 */
 
 MAGIC*
-Perl_mg_find(pTHX_ SV *sv, int type)
+Perl_mg_find(pTHX_ const SV *sv, int type)
 {
-    MAGIC* mg;
-    if (!sv)
-        return 0;
-    for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
-	if (mg->mg_type == type)
-	    return mg;
+    if (sv) {
+        MAGIC *mg;
+        for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
+            if (mg->mg_type == type)
+                return mg;
+        }
     }
     return 0;
 }
@@ -381,7 +373,7 @@ Perl_mg_copy(pTHX_ SV *sv, SV *nsv, const char *key, I32 klen)
     int count = 0;
     MAGIC* mg;
     for (mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic) {
-	MGVTBL* vtbl = mg->mg_virtual;
+        const MGVTBL* const vtbl = mg->mg_virtual;
 	if ((mg->mg_flags & MGf_COPY) && vtbl->svt_copy){
 	    count += CALL_FPTR(vtbl->svt_copy)(aTHX_ sv, mg, nsv, key, klen);
 	}
@@ -411,7 +403,7 @@ Perl_mg_free(pTHX_ SV *sv)
     MAGIC* mg;
     MAGIC* moremagic;
     for (mg = SvMAGIC(sv); mg; mg = moremagic) {
-	MGVTBL* vtbl = mg->mg_virtual;
+        const MGVTBL* const vtbl = mg->mg_virtual;
 	moremagic = mg->mg_moremagic;
 	if (vtbl && vtbl->svt_free)
 	    CALL_FPTR(vtbl->svt_free)(aTHX_ sv, mg);
@@ -434,7 +426,7 @@ Perl_mg_free(pTHX_ SV *sv)
 U32
 Perl_magic_regdata_cnt(pTHX_ SV *sv, MAGIC *mg)
 {
-    register REGEXP *rx;
+    register const REGEXP *rx;
 
     if (PL_curpm && (rx = PM_GETRE(PL_curpm))) {
 	if (mg->mg_obj)		/* @+ */
@@ -449,20 +441,19 @@ Perl_magic_regdata_cnt(pTHX_ SV *sv, MAGIC *mg)
 int
 Perl_magic_regdatum_get(pTHX_ SV *sv, MAGIC *mg)
 {
-    register I32 paren;
-    register I32 s;
-    register I32 i;
     register REGEXP *rx;
-    I32 t;
 
     if (PL_curpm && (rx = PM_GETRE(PL_curpm))) {
-	paren = mg->mg_len;
+        register const I32 paren = mg->mg_len;
+        register I32 s;
+        register I32 t;
 	if (paren < 0)
 	    return 0;
 	if (paren <= (I32)rx->nparens &&
 	    (s = rx->startp[paren]) != -1 &&
 	    (t = rx->endp[paren]) != -1)
 	    {
+                register I32 i;
 		if (mg->mg_obj)		/* @+ */
 		    i = t;
 		else			/* @- */
@@ -1159,10 +1150,9 @@ Perl_magic_clearsig(pTHX_ SV *sv, MAGIC *mg)
     /* XXX Some of this code was copied from Perl_magic_setsig. A little
      * refactoring might be in order.
      */
-    register char *s;
     STRLEN n_a;
     SV* to_dec;
-    s = MgPV(mg,n_a);
+    register const char *s = MgPV(mg,n_a);
     if (*s == '_') {
 	SV** svp;
 	if (strEQ(s,"__DIE__"))
@@ -1298,7 +1288,6 @@ Perl_despatch_signals(pTHX)
 int
 Perl_magic_setsig(pTHX_ SV *sv, MAGIC *mg)
 {
-    register char *s;
     I32 i;
     SV** svp = 0;
     /* Need to be careful with SvREFCNT_dec(), because that can have side
@@ -1312,7 +1301,7 @@ Perl_magic_setsig(pTHX_ SV *sv, MAGIC *mg)
     SV* save_sv;
 #endif
 
-    s = MgPV(mg,len);
+    register const char *s = MgPV(mg,len);
     if (*s == '_') {
 	if (strEQ(s,"__DIE__"))
 	    svp = &PL_diehook;
@@ -1578,7 +1567,7 @@ int
 Perl_magic_nextpack(pTHX_ SV *sv, MAGIC *mg, SV *key)
 {
     dSP;
-    const char *meth = SvOK(key) ? "NEXTKEY" : "FIRSTKEY";
+    const char * const meth = SvOK(key) ? "NEXTKEY" : "FIRSTKEY";
 
     ENTER;
     SAVETMPS;
@@ -1781,8 +1770,8 @@ int
 Perl_magic_getsubstr(pTHX_ SV *sv, MAGIC *mg)
 {
     STRLEN len;
-    SV *lsv = LvTARG(sv);
-    char *tmps = SvPV(lsv,len);
+    SV * const lsv = LvTARG(sv);
+    const char * const tmps = SvPV(lsv,len);
     I32 offs = LvTARGOFF(sv);
     I32 rem = LvTARGLEN(sv);
 
@@ -1857,7 +1846,7 @@ Perl_magic_settaint(pTHX_ SV *sv, MAGIC *mg)
 int
 Perl_magic_getvec(pTHX_ SV *sv, MAGIC *mg)
 {
-    SV *lsv = LvTARG(sv);
+    SV * const lsv = LvTARG(sv);
 
     if (!lsv) {
 	SvOK_off(sv);
@@ -2004,7 +1993,7 @@ Perl_magic_setfm(pTHX_ SV *sv, MAGIC *mg)
 int
 Perl_magic_setuvar(pTHX_ SV *sv, MAGIC *mg)
 {
-    struct ufuncs *uf = (struct ufuncs *)mg->mg_ptr;
+    const struct ufuncs * const uf = (struct ufuncs *)mg->mg_ptr;
 
     if (uf && uf->uf_set)
 	(*uf->uf_set)(aTHX_ uf->uf_index, sv);
@@ -2172,7 +2161,7 @@ Perl_magic_set(pTHX_ SV *sv, MAGIC *mg)
 		    STRLEN len, i;
 		    int accumulate = 0 ;
 		    int any_fatals = 0 ;
-		    char * ptr = (char*)SvPV(sv, len) ;
+		    const char * const ptr = (char*)SvPV(sv, len) ;
 		    for (i = 0 ; i < len ; ++i) {
 		        accumulate |= ptr[i] ;
 		        any_fatals |= (ptr[i] & 0xAA) ;
@@ -2389,7 +2378,7 @@ Perl_magic_set(pTHX_ SV *sv, MAGIC *mg)
     case ')':
 #ifdef HAS_SETGROUPS
 	{
-	    char *p = SvPV(sv, len);
+	    const char *p = SvPV(sv, len);
 	    Groups_t gary[NGROUPS];
 
 	    while (isSPACE(*p))
@@ -2503,7 +2492,7 @@ Perl_magic_set(pTHX_ SV *sv, MAGIC *mg)
 }
 
 I32
-Perl_whichsig(pTHX_ char *sig)
+Perl_whichsig(pTHX_ const char *sig)
 {
     register char **sigv;
 
@@ -2636,7 +2625,7 @@ cleanup:
 
 
 static void
-restore_magic(pTHX_ void *p)
+restore_magic(pTHX_ const void *p)
 {
     MGS* mgs = SSPTR(PTR2IV(p), MGS*);
     SV* sv = mgs->mgs_sv;
@@ -2684,9 +2673,9 @@ restore_magic(pTHX_ void *p)
 }
 
 static void
-unwind_handler_stack(pTHX_ void *p)
+unwind_handler_stack(pTHX_ const void *p)
 {
-    U32 flags = *(U32*)p;
+    const U32 flags = *(U32*)p;
 
     if (flags & 1)
 	PL_savestack_ix -= 5; /* Unprotect save in progress. */
diff --git a/op.c b/op.c
index 77a213ed5f..6631fe3c54 100644
--- a/op.c
+++ b/op.c
@@ -4031,7 +4031,7 @@ Perl_cv_undef(pTHX_ CV *cv)
 }
 
 void
-Perl_cv_ckproto(pTHX_ CV *cv, GV *gv, char *p)
+Perl_cv_ckproto(pTHX_ const CV *cv, const GV *gv, const char *p)
 {
     if (((!p != !SvPOK(cv)) || (p && strNE(p, SvPVX(cv)))) && ckWARN_d(WARN_PROTOTYPE)) {
 	SV* msg = sv_newmortal();
diff --git a/pod/perlapi.pod b/pod/perlapi.pod
index 1c33761265..bf1256f8a1 100644
--- a/pod/perlapi.pod
+++ b/pod/perlapi.pod
@@ -179,7 +179,7 @@ Found in file av.c
 Returns the highest index in the array.  Returns -1 if the array is
 empty.
 
-	I32	av_len(AV* ar)
+	I32	av_len(const AV* ar)
 
 =for hackers
 Found in file av.c
@@ -1411,7 +1411,7 @@ Found in file mg.c
 
 Finds the magic pointer for type matching the SV.  See C<sv_magic>.
 
-	MAGIC*	mg_find(SV* sv, int type)
+	MAGIC*	mg_find(const SV* sv, int type)
 
 =for hackers
 Found in file mg.c
@@ -5160,7 +5160,7 @@ Found in file sv.c
 =item bytes_from_utf8
 
 Converts a string C<s> of length C<len> from UTF-8 into byte encoding.
-Unlike <utf8_to_bytes> but like C<bytes_to_utf8>, returns a pointer to
+Unlike C<utf8_to_bytes> but like C<bytes_to_utf8>, returns a pointer to
 the newly-created string, and updates C<len> to contain the new
 length.  Returns the original string if no conversion occurs, C<len>
 is unchanged. Do nothing if C<is_utf8> points to 0. Sets C<is_utf8> to
@@ -5186,7 +5186,7 @@ see sv_recode_to_utf8().
 NOTE: this function is experimental and may change or be
 removed without notice.
 
-	U8*	bytes_to_utf8(U8 *s, STRLEN *len)
+	U8*	bytes_to_utf8(const U8 *s, STRLEN *len)
 
 =for hackers
 Found in file utf8.c
@@ -5457,7 +5457,7 @@ and C<b>.
 WARNING: use only if you *know* that the pointers point inside the
 same UTF-8 buffer.
 
-	IV	utf8_distance(U8 *a, U8 *b)
+	IV	utf8_distance(const U8 *a, const U8 *b)
 
 =for hackers
 Found in file utf8.c
@@ -5482,7 +5482,7 @@ Return the length of the UTF-8 char encoded string C<s> in characters.
 Stops at C<e> (inclusive).  If C<e E<lt> s> or if the scan would end
 up past C<e>, croaks.
 
-	STRLEN	utf8_length(U8* s, U8 *e)
+	STRLEN	utf8_length(const U8* s, const U8 *e)
 
 =for hackers
 Found in file utf8.c
diff --git a/pp_ctl.c b/pp_ctl.c
index fe03eebfbd..40c3b22b15 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -1392,13 +1392,12 @@ Perl_qerror(pTHX_ SV *err)
 }
 
 OP *
-Perl_die_where(pTHX_ char *message, STRLEN msglen)
+Perl_die_where(pTHX_ const char *message, STRLEN msglen)
 {
     STRLEN n_a;
 
     if (PL_in_eval) {
 	I32 cxix;
-	register PERL_CONTEXT *cx;
 	I32 gimme;
 	SV **newsp;
 
@@ -1439,6 +1438,7 @@ Perl_die_where(pTHX_ char *message, STRLEN msglen)
 
 	if (cxix >= 0) {
 	    I32 optype;
+	    register PERL_CONTEXT *cx;
 
 	    if (cxix < cxstack_ix)
 		dounwind(cxix);
@@ -1466,9 +1466,9 @@ Perl_die_where(pTHX_ char *message, STRLEN msglen)
 	    PL_curcop = cx->blk_oldcop;
 
 	    if (optype == OP_REQUIRE) {
-		char* msg = SvPVx(ERRSV, n_a);
-               SV *nsv = cx->blk_eval.old_namesv;
-               (void)hv_store(GvHVn(PL_incgv), SvPVX(nsv), SvCUR(nsv),
+                const char* msg = SvPVx(ERRSV, n_a);
+                SV *nsv = cx->blk_eval.old_namesv;
+                (void)hv_store(GvHVn(PL_incgv), SvPVX(nsv), SvCUR(nsv),
                                &PL_sv_undef, 0);
 		DIE(aTHX_ "%sCompilation failed in require",
 		    *msg ? msg : "Unknown error\n");
diff --git a/proto.h b/proto.h
index 8ab2155aaf..41513ad5bd 100644
--- a/proto.h
+++ b/proto.h
@@ -64,7 +64,7 @@ PERL_CALLCONV void	Perl_av_extend(pTHX_ AV* ar, I32 key);
 PERL_CALLCONV AV*	Perl_av_fake(pTHX_ I32 size, SV** svp);
 PERL_CALLCONV SV**	Perl_av_fetch(pTHX_ AV* ar, I32 key, I32 lval);
 PERL_CALLCONV void	Perl_av_fill(pTHX_ AV* ar, I32 fill);
-PERL_CALLCONV I32	Perl_av_len(pTHX_ AV* ar);
+PERL_CALLCONV I32	Perl_av_len(pTHX_ const AV* ar);
 PERL_CALLCONV AV*	Perl_av_make(pTHX_ I32 size, SV** svp);
 PERL_CALLCONV SV*	Perl_av_pop(pTHX_ AV* ar);
 PERL_CALLCONV void	Perl_av_push(pTHX_ AV* ar, SV* val);
@@ -123,7 +123,7 @@ PERL_CALLCONV int	Perl_fprintf_nocontext(PerlIO* stream, const char* fmt, ...)
 PERL_CALLCONV int	Perl_printf_nocontext(const char* fmt, ...)
 	__attribute__format__(__printf__,1,2);
 #endif
-PERL_CALLCONV void	Perl_cv_ckproto(pTHX_ CV* cv, GV* gv, char* p);
+PERL_CALLCONV void	Perl_cv_ckproto(pTHX_ const CV* cv, const GV* gv, const char* p);
 PERL_CALLCONV CV*	Perl_cv_clone(pTHX_ CV* proto);
 PERL_CALLCONV SV*	Perl_cv_const_sv(pTHX_ CV* cv);
 PERL_CALLCONV SV*	Perl_op_const_sv(pTHX_ OP* o, CV* cv);
@@ -151,7 +151,7 @@ PERL_CALLCONV void	Perl_deprecate_old(pTHX_ char* s);
 PERL_CALLCONV OP*	Perl_die(pTHX_ const char* pat, ...)
 	__attribute__format__(__printf__,pTHX_1,pTHX_2);
 PERL_CALLCONV OP*	Perl_vdie(pTHX_ const char* pat, va_list* args);
-PERL_CALLCONV OP*	Perl_die_where(pTHX_ char* message, STRLEN msglen);
+PERL_CALLCONV OP*	Perl_die_where(pTHX_ const char* message, STRLEN msglen);
 PERL_CALLCONV void	Perl_dounwind(pTHX_ I32 cxix);
 PERL_CALLCONV bool	Perl_do_aexec(pTHX_ SV* really, SV** mark, SV** sp);
 PERL_CALLCONV bool	Perl_do_aexec5(pTHX_ SV* really, SV** mark, SV** sp, int fd, int flag);
@@ -227,18 +227,18 @@ PERL_CALLCONV GV*	Perl_gv_HVadd(pTHX_ GV* gv);
 PERL_CALLCONV GV*	Perl_gv_IOadd(pTHX_ GV* gv);
 PERL_CALLCONV GV*	Perl_gv_autoload4(pTHX_ HV* stash, const char* name, STRLEN len, I32 method);
 PERL_CALLCONV void	Perl_gv_check(pTHX_ HV* stash);
-PERL_CALLCONV void	Perl_gv_efullname(pTHX_ SV* sv, GV* gv);
-/* PERL_CALLCONV void	gv_efullname3(pTHX_ SV* sv, GV* gv, const char* prefix); */
-PERL_CALLCONV void	Perl_gv_efullname4(pTHX_ SV* sv, GV* gv, const char* prefix, bool keepmain);
+PERL_CALLCONV void	Perl_gv_efullname(pTHX_ SV* sv, const GV* gv);
+/* PERL_CALLCONV void	gv_efullname3(pTHX_ SV* sv, const GV* gv, const char* prefix); */
+PERL_CALLCONV void	Perl_gv_efullname4(pTHX_ SV* sv, const GV* gv, const char* prefix, bool keepmain);
 PERL_CALLCONV GV*	Perl_gv_fetchfile(pTHX_ const char* name);
 PERL_CALLCONV GV*	Perl_gv_fetchmeth(pTHX_ HV* stash, const char* name, STRLEN len, I32 level);
 PERL_CALLCONV GV*	Perl_gv_fetchmeth_autoload(pTHX_ HV* stash, const char* name, STRLEN len, I32 level);
 PERL_CALLCONV GV*	Perl_gv_fetchmethod(pTHX_ HV* stash, const char* name);
 PERL_CALLCONV GV*	Perl_gv_fetchmethod_autoload(pTHX_ HV* stash, const char* name, I32 autoload);
 PERL_CALLCONV GV*	Perl_gv_fetchpv(pTHX_ const char* name, I32 add, I32 sv_type);
-PERL_CALLCONV void	Perl_gv_fullname(pTHX_ SV* sv, GV* gv);
-/* PERL_CALLCONV void	gv_fullname3(pTHX_ SV* sv, GV* gv, const char* prefix); */
-PERL_CALLCONV void	Perl_gv_fullname4(pTHX_ SV* sv, GV* gv, const char* prefix, bool keepmain);
+PERL_CALLCONV void	Perl_gv_fullname(pTHX_ SV* sv, const GV* gv);
+/* PERL_CALLCONV void	gv_fullname3(pTHX_ SV* sv, const GV* gv, const char* prefix); */
+PERL_CALLCONV void	Perl_gv_fullname4(pTHX_ SV* sv, const GV* gv, const char* prefix, bool keepmain);
 PERL_CALLCONV void	Perl_gv_init(pTHX_ GV* gv, HV* stash, const char* name, STRLEN len, int multi);
 PERL_CALLCONV HV*	Perl_gv_stashpv(pTHX_ const char* name, I32 create);
 PERL_CALLCONV HV*	Perl_gv_stashpvn(pTHX_ const char* name, U32 namelen, I32 create);
@@ -417,7 +417,7 @@ PERL_CALLCONV void	Perl_qerror(pTHX_ SV* err);
 PERL_CALLCONV void	Perl_sortsv(pTHX_ SV ** array, size_t num_elts, SVCOMPARE_t cmp);
 PERL_CALLCONV int	Perl_mg_clear(pTHX_ SV* sv);
 PERL_CALLCONV int	Perl_mg_copy(pTHX_ SV* sv, SV* nsv, const char* key, I32 klen);
-PERL_CALLCONV MAGIC*	Perl_mg_find(pTHX_ SV* sv, int type);
+PERL_CALLCONV MAGIC*	Perl_mg_find(pTHX_ const SV* sv, int type);
 PERL_CALLCONV int	Perl_mg_free(pTHX_ SV* sv);
 PERL_CALLCONV int	Perl_mg_get(pTHX_ SV* sv);
 PERL_CALLCONV U32	Perl_mg_length(pTHX_ SV* sv);
@@ -606,7 +606,7 @@ PERL_CALLCONV char*	Perl_savesharedpv(pTHX_ const char* pv);
 PERL_CALLCONV char*	Perl_savepvn(pTHX_ const char* pv, I32 len);
 PERL_CALLCONV void	Perl_savestack_grow(pTHX);
 PERL_CALLCONV void	Perl_savestack_grow_cnt(pTHX_ I32 need);
-PERL_CALLCONV void	Perl_save_aelem(pTHX_ AV* av, I32 idx, SV **sptr);
+PERL_CALLCONV void	Perl_save_aelem(pTHX_ const AV* av, I32 idx, SV **sptr);
 PERL_CALLCONV I32	Perl_save_alloc(pTHX_ I32 size, I32 pad);
 PERL_CALLCONV void	Perl_save_aptr(pTHX_ AV** aptr);
 PERL_CALLCONV AV*	Perl_save_ary(pTHX_ GV* gv);
@@ -623,7 +623,7 @@ PERL_CALLCONV void	Perl_save_generic_pvref(pTHX_ char** str);
 PERL_CALLCONV void	Perl_save_shared_pvref(pTHX_ char** str);
 PERL_CALLCONV void	Perl_save_gp(pTHX_ GV* gv, I32 empty);
 PERL_CALLCONV HV*	Perl_save_hash(pTHX_ GV* gv);
-PERL_CALLCONV void	Perl_save_helem(pTHX_ HV* hv, SV *key, SV **sptr);
+PERL_CALLCONV void	Perl_save_helem(pTHX_ const HV* hv, SV *key, SV **sptr);
 PERL_CALLCONV void	Perl_save_hints(pTHX);
 PERL_CALLCONV void	Perl_save_hptr(pTHX_ HV** hptr);
 PERL_CALLCONV void	Perl_save_I16(pTHX_ I16* intp);
@@ -783,12 +783,12 @@ PERL_CALLCONV void	Perl_unshare_hek(pTHX_ HEK* hek);
 PERL_CALLCONV void	Perl_utilize(pTHX_ int aver, I32 floor, OP* version, OP* idop, OP* arg);
 PERL_CALLCONV U8*	Perl_utf16_to_utf8(pTHX_ U8* p, U8 *d, I32 bytelen, I32 *newlen);
 PERL_CALLCONV U8*	Perl_utf16_to_utf8_reversed(pTHX_ U8* p, U8 *d, I32 bytelen, I32 *newlen);
-PERL_CALLCONV STRLEN	Perl_utf8_length(pTHX_ U8* s, U8 *e);
-PERL_CALLCONV IV	Perl_utf8_distance(pTHX_ U8 *a, U8 *b);
+PERL_CALLCONV STRLEN	Perl_utf8_length(pTHX_ const U8* s, const U8 *e);
+PERL_CALLCONV IV	Perl_utf8_distance(pTHX_ const U8 *a, const U8 *b);
 PERL_CALLCONV U8*	Perl_utf8_hop(pTHX_ U8 *s, I32 off);
 PERL_CALLCONV U8*	Perl_utf8_to_bytes(pTHX_ U8 *s, STRLEN *len);
 PERL_CALLCONV U8*	Perl_bytes_from_utf8(pTHX_ U8 *s, STRLEN *len, bool *is_utf8);
-PERL_CALLCONV U8*	Perl_bytes_to_utf8(pTHX_ U8 *s, STRLEN *len);
+PERL_CALLCONV U8*	Perl_bytes_to_utf8(pTHX_ const U8 *s, STRLEN *len);
 PERL_CALLCONV UV	Perl_utf8_to_uvchr(pTHX_ U8 *s, STRLEN* retlen);
 PERL_CALLCONV UV	Perl_utf8_to_uvuni(pTHX_ U8 *s, STRLEN* retlen);
 PERL_CALLCONV UV	Perl_utf8n_to_uvchr(pTHX_ U8 *s, STRLEN curlen, STRLEN* retlen, U32 flags);
@@ -814,7 +814,7 @@ PERL_CALLCONV void	Perl_warner(pTHX_ U32 err, const char* pat, ...)
 	__attribute__format__(__printf__,pTHX_2,pTHX_3);
 PERL_CALLCONV void	Perl_vwarner(pTHX_ U32 err, const char* pat, va_list* args);
 PERL_CALLCONV void	Perl_watch(pTHX_ char** addr);
-PERL_CALLCONV I32	Perl_whichsig(pTHX_ char* sig);
+PERL_CALLCONV I32	Perl_whichsig(pTHX_ const char* sig);
 PERL_CALLCONV void	Perl_write_to_stderr(pTHX_ const char* message, int msglen);
 PERL_CALLCONV int	Perl_yyerror(pTHX_ char* s);
 PERL_CALLCONV int	Perl_yylex(pTHX);
diff --git a/scope.c b/scope.c
index b2dc422899..c4edd17605 100644
--- a/scope.c
+++ b/scope.c
@@ -90,15 +90,15 @@ Perl_push_scope(pTHX)
 void
 Perl_pop_scope(pTHX)
 {
-    I32 oldsave = PL_scopestack[--PL_scopestack_ix];
+    const I32 oldsave = PL_scopestack[--PL_scopestack_ix];
     LEAVE_SCOPE(oldsave);
 }
 
 void
 Perl_markstack_grow(pTHX)
 {
-    I32 oldmax = PL_markstack_max - PL_markstack;
-    I32 newmax = GROW(oldmax);
+    const I32 oldmax = PL_markstack_max - PL_markstack;
+    const I32 newmax = GROW(oldmax);
 
     Renew(PL_markstack, newmax, I32);
     PL_markstack_ptr = PL_markstack + oldmax;
@@ -137,7 +137,7 @@ void
 Perl_free_tmps(pTHX)
 {
     /* XXX should tmps_floor live in cxstack? */
-    I32 myfloor = PL_tmps_floor;
+    const I32 myfloor = PL_tmps_floor;
     while (PL_tmps_ix > myfloor) {      /* clean up after last statement */
 	SV* sv = PL_tmps_stack[PL_tmps_ix];
 	PL_tmps_stack[PL_tmps_ix--] = Nullsv;
@@ -159,7 +159,7 @@ S_save_scalar_at(pTHX_ SV **sptr)
 	MAGIC *mg;
 	sv_upgrade(sv, SvTYPE(osv));
 	if (SvGMAGICAL(osv)) {
-	    bool oldtainted = PL_tainted;
+	    const bool oldtainted = PL_tainted;
 	    mg_get(osv);		/* note, can croak! */
 	    if (PL_tainting && PL_tainted &&
 			(mg = mg_find(osv, PERL_MAGIC_taint))) {
@@ -582,7 +582,7 @@ Perl_save_destructor_x(pTHX_ DESTRUCTORFUNC_t f, void* p)
 }
 
 void
-Perl_save_aelem(pTHX_ AV *av, I32 idx, SV **sptr)
+Perl_save_aelem(pTHX_ const AV *av, I32 idx, SV **sptr)
 {
     SV *sv;
     SSCHECK(4);
@@ -604,7 +604,7 @@ Perl_save_aelem(pTHX_ AV *av, I32 idx, SV **sptr)
 }
 
 void
-Perl_save_helem(pTHX_ HV *hv, SV *key, SV **sptr)
+Perl_save_helem(pTHX_ const HV *hv, SV *key, SV **sptr)
 {
     SV *sv;
     SSCHECK(4);
@@ -633,9 +633,9 @@ Perl_save_op(pTHX)
 I32
 Perl_save_alloc(pTHX_ I32 size, I32 pad)
 {
-    register I32 start = pad + ((char*)&PL_savestack[PL_savestack_ix]
+    register const I32 start = pad + ((char*)&PL_savestack[PL_savestack_ix]
 				- (char*)PL_savestack);
-    register I32 elems = 1 + ((size + pad - 1) / sizeof(*PL_savestack));
+    register const I32 elems = 1 + ((size + pad - 1) / sizeof(*PL_savestack));
 
     /* SSCHECK may not be good enough */
     while (PL_savestack_ix + elems + 2 > PL_savestack_max)
@@ -751,7 +751,7 @@ Perl_leave_scope(pTHX_ I32 base)
 	    av = (AV*)SSPOPPTR;
 	    gv = (GV*)SSPOPPTR;
 	    if (GvAV(gv)) {
-		AV *goner = GvAV(gv);
+		AV * const goner = GvAV(gv);
 		SvMAGIC(av) = SvMAGIC(goner);
 		SvFLAGS((SV*)av) |= SvMAGICAL(goner);
 		SvMAGICAL_off(goner);
@@ -769,7 +769,7 @@ Perl_leave_scope(pTHX_ I32 base)
 	    hv = (HV*)SSPOPPTR;
 	    gv = (GV*)SSPOPPTR;
 	    if (GvHV(gv)) {
-		HV *goner = GvHV(gv);
+		HV * const goner = GvHV(gv);
 		SvMAGIC(hv) = SvMAGIC(goner);
 		SvFLAGS(hv) |= SvMAGICAL(goner);
 		SvMAGICAL_off(goner);
@@ -908,7 +908,7 @@ Perl_leave_scope(pTHX_ I32 base)
 		SvPADSTALE_on(sv); /* mark as no longer live */
 	    }
 	    else {	/* Someone has a claim on this, so abandon it. */
-		U32 padflags = SvFLAGS(sv) & (SVs_PADMY|SVs_PADTMP);
+		const U32 padflags = SvFLAGS(sv) & (SVs_PADMY|SVs_PADTMP);
 		switch (SvTYPE(sv)) {	/* Console ourselves with a new value */
 		case SVt_PVAV:	*(SV**)ptr = (SV*)newAV();	break;
 		case SVt_PVHV:	*(SV**)ptr = (SV*)newHV();	break;
@@ -969,7 +969,7 @@ Perl_leave_scope(pTHX_ I32 base)
 	    hv = (HV*)SSPOPPTR;
 	    ptr = hv_fetch_ent(hv, sv, 1, 0);
 	    if (ptr) {
-		SV *oval = HeVAL((HE*)ptr);
+		const SV * const oval = HeVAL((HE*)ptr);
 		if (oval && oval != &PL_sv_undef) {
 		    ptr = &HeVAL((HE*)ptr);
 		    if (SvTIED_mg((SV*)hv, PERL_MAGIC_tied))
@@ -1007,7 +1007,7 @@ Perl_leave_scope(pTHX_ I32 base)
 	    break;
 	case SAVEt_PADSV:
 	    {
-		PADOFFSET off = (PADOFFSET)SSPOPLONG;
+		const PADOFFSET off = (PADOFFSET)SSPOPLONG;
 		ptr = SSPOPPTR;
 		if (ptr)
 		    AvARRAY((PAD*)ptr)[off] = (SV*)SSPOPPTR;
@@ -1024,8 +1024,8 @@ Perl_leave_scope(pTHX_ I32 base)
 	    break;
 	case SAVEt_SET_SVFLAGS:
 	    {
-		U32 val  = (U32)SSPOPINT;
-		U32 mask = (U32)SSPOPINT;
+		const U32 val  = (U32)SSPOPINT;
+		const U32 mask = (U32)SSPOPINT;
 		sv = (SV*)SSPOPPTR;
 		SvFLAGS(sv) &= ~mask;
 		SvFLAGS(sv) |= val;
diff --git a/utf8.c b/utf8.c
index b11061455f..ab49b9ea3a 100644
--- a/utf8.c
+++ b/utf8.c
@@ -581,7 +581,7 @@ Perl_utf8_to_uvuni(pTHX_ U8 *s, STRLEN *retlen)
 }
 
 /*
-=for apidoc A|STRLEN|utf8_length|U8 *s|U8 *e
+=for apidoc A|STRLEN|utf8_length|const U8 *s|const U8 *e
 
 Return the length of the UTF-8 char encoded string C<s> in characters.
 Stops at C<e> (inclusive).  If C<e E<lt> s> or if the scan would end
@@ -591,7 +591,7 @@ up past C<e>, croaks.
 */
 
 STRLEN
-Perl_utf8_length(pTHX_ U8 *s, U8 *e)
+Perl_utf8_length(pTHX_ const U8 *s, const U8 *e)
 {
     STRLEN len = 0;
 
@@ -630,7 +630,7 @@ Perl_utf8_length(pTHX_ U8 *s, U8 *e)
 }
 
 /*
-=for apidoc A|IV|utf8_distance|U8 *a|U8 *b
+=for apidoc A|IV|utf8_distance|const U8 *a|const U8 *b
 
 Returns the number of UTF-8 characters between the UTF-8 pointers C<a>
 and C<b>.
@@ -642,7 +642,7 @@ same UTF-8 buffer.
 */
 
 IV
-Perl_utf8_distance(pTHX_ U8 *a, U8 *b)
+Perl_utf8_distance(pTHX_ const U8 *a, const U8 *b)
 {
     IV off = 0;
 
@@ -652,7 +652,7 @@ Perl_utf8_distance(pTHX_ U8 *a, U8 *b)
 
     if (a < b) {
 	while (a < b) {
-	    U8 c = UTF8SKIP(a);
+	    const U8 c = UTF8SKIP(a);
 
 	    if (b - a < c) {
 	        if (ckWARN_d(WARN_UTF8)) {
@@ -769,7 +769,7 @@ Perl_utf8_to_bytes(pTHX_ U8 *s, STRLEN *len)
 =for apidoc A|U8 *|bytes_from_utf8|U8 *s|STRLEN *len|bool *is_utf8
 
 Converts a string C<s> of length C<len> from UTF-8 into byte encoding.
-Unlike <utf8_to_bytes> but like C<bytes_to_utf8>, returns a pointer to
+Unlike C<utf8_to_bytes> but like C<bytes_to_utf8>, returns a pointer to
 the newly-created string, and updates C<len> to contain the new
 length.  Returns the original string if no conversion occurs, C<len>
 is unchanged. Do nothing if C<is_utf8> points to 0. Sets C<is_utf8> to
@@ -820,7 +820,7 @@ Perl_bytes_from_utf8(pTHX_ U8 *s, STRLEN *len, bool *is_utf8)
 }
 
 /*
-=for apidoc A|U8 *|bytes_to_utf8|U8 *s|STRLEN *len
+=for apidoc A|U8 *|bytes_to_utf8|const U8 *s|STRLEN *len
 
 Converts a string C<s> of length C<len> from ASCII into UTF-8 encoding.
 Returns a pointer to the newly-created string, and sets C<len> to
@@ -833,18 +833,17 @@ see sv_recode_to_utf8().
 */
 
 U8*
-Perl_bytes_to_utf8(pTHX_ U8 *s, STRLEN *len)
+Perl_bytes_to_utf8(pTHX_ const U8 *s, STRLEN *len)
 {
-    U8 *send;
+    const U8 * const send = s + (*len);
     U8 *d;
     U8 *dst;
-    send = s + (*len);
 
     Newz(801, d, (*len) * 2 + 1, U8);
     dst = d;
 
     while (s < send) {
-        UV uv = NATIVE_TO_ASCII(*s++);
+        const UV uv = NATIVE_TO_ASCII(*s++);
         if (UNI_IS_INVARIANT(uv))
             *d++ = (U8)UTF_TO_NATIVE(uv);
         else {