diff --git a/MANIFEST b/MANIFEST
index d276691d8b21..0ab0da637873 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -5551,6 +5551,7 @@ scope.h				Scope entry and exit header
 SECURITY.md			Add Security Policy for GitHub
 sv.c				Scalar value code
 sv.h				Scalar value header
+sv_inline.h			Perl_newSV_type and required defs
 t/base/cond.t			See if conditionals work
 t/base/if.t			See if if works
 t/base/lex.t			See if lexical items work
diff --git a/av.c b/av.c
index d2f0e0db45d3..335121a951d6 100644
--- a/av.c
+++ b/av.c
@@ -267,8 +267,7 @@ Perl_av_fetch(pTHX_ AV *av, SSize_t key, I32 lval)
                         return NULL;
             }
 
-            sv = sv_newmortal();
-            sv_upgrade(sv, SVt_PVLV);
+            sv = newSV_type_mortal(SVt_PVLV);
             mg_copy(MUTABLE_SV(av), sv, 0, key);
             if (!tied_magic) /* for regdata, force leavesub to make copies */
                 SvTEMP_off(sv);
@@ -292,7 +291,7 @@ Perl_av_fetch(pTHX_ AV *av, SSize_t key, I32 lval)
 
     if (!AvARRAY(av)[key]) {
       emptyness:
-        return lval ? av_store(av,key,newSV(0)) : NULL;
+        return lval ? av_store(av,key,newSV_type(SVt_NULL)) : NULL;
     }
 
     return &AvARRAY(av)[key];
@@ -473,7 +472,7 @@ Perl_av_make(pTHX_ SSize_t size, SV **strp)
 
             SvGETMAGIC(*strp); /* before newSV, in case it dies */
             AvFILLp(av)++;
-            ary[i] = newSV(0);
+            ary[i] = newSV_type(SVt_NULL);
             sv_setsv_flags(ary[i], *strp,
                            SV_DO_COW_SVSETSV|SV_NOSTEAL);
             strp++;
@@ -1124,7 +1123,7 @@ Perl_av_iter_p(pTHX_ AV *av) {
 
 SV *
 Perl_av_nonelem(pTHX_ AV *av, SSize_t ix) {
-    SV * const sv = newSV(0);
+    SV * const sv = newSV_type(SVt_NULL);
     PERL_ARGS_ASSERT_AV_NONELEM;
     if (!av_store(av,ix,sv))
         return sv_2mortal(sv); /* has tie magic */
diff --git a/doop.c b/doop.c
index 5a9c0d8f467f..ede537723ce2 100644
--- a/doop.c
+++ b/doop.c
@@ -1176,7 +1176,7 @@ Perl_do_kv(pTHX)
 
     if (gimme == G_SCALAR) {
         if (PL_op->op_flags & OPf_MOD || LVRET) {	/* lvalue */
-            SV * const ret = sv_2mortal(newSV_type(SVt_PVLV));  /* Not TARG RT#67838 */
+            SV * const ret = newSV_type_mortal(SVt_PVLV);  /* Not TARG RT#67838 */
             sv_magic(ret, NULL, PERL_MAGIC_nkeys, NULL, 0);
             LvTYPE(ret) = 'k';
             LvTARG(ret) = SvREFCNT_inc_simple(keys);
diff --git a/dump.c b/dump.c
index b2c6a075fd99..d48f58238135 100644
--- a/dump.c
+++ b/dump.c
@@ -2674,7 +2674,7 @@ S_append_gv_name(pTHX_ GV *gv, SV *out)
         sv_catpvs_nomg(out, "<NULLGV>");
         return;
     }
-    sv = newSV(0);
+    sv = newSV_type(SVt_NULL);
     gv_fullname4(sv, gv, NULL, FALSE);
     Perl_sv_catpvf(aTHX_ out, "$%" SVf, SVfARG(sv));
     SvREFCNT_dec_NN(sv);
diff --git a/embed.fnc b/embed.fnc
index 45c6fd2b2648..32ca60e26d24 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -1519,7 +1519,8 @@ Apd	|SV*	|newSVrv	|NN SV *const rv|NULLOK const char *const classname
 ApMbdR	|SV*	|newSVsv	|NULLOK SV *const old
 AmdR	|SV*	|newSVsv_nomg	|NULLOK SV *const old
 AdpR	|SV*	|newSVsv_flags	|NULLOK SV *const old|I32 flags
-ApdR	|SV*	|newSV_type	|const svtype type
+ApdiR	|SV*	|newSV_type	|const svtype type
+ApdIR	|SV*    |newSV_type_mortal|const svtype type
 ApdR	|OP*	|newUNOP	|I32 type|I32 flags|NULLOK OP* first
 ApdR	|OP*	|newUNOP_AUX	|I32 type|I32 flags|NULLOK OP* first \
 				|NULLOK UNOP_AUX_item *aux
@@ -3165,7 +3166,7 @@ S	|STRLEN	|sv_pos_b2u_midway|NN const U8 *const s|NN const U8 *const target \
 S	|void	|assert_uft8_cache_coherent|NN const char *const func \
 		|STRLEN from_cache|STRLEN real|NN SV *const sv
 ST	|char *	|F0convert	|NV nv|NN char *const endbuf|NN STRLEN *const len
-S	|SV *	|more_sv
+Cp	|SV *	|more_sv
 S	|bool	|sv_2iuv_common	|NN SV *const sv
 S	|void	|glob_assign_glob|NN SV *const dsv|NN SV *const ssv \
 		|const int dtype
@@ -3174,7 +3175,7 @@ S	|void	|anonymise_cv_maybe	|NN GV *gv|NN CV *cv
 #endif
 
 : Used in sv.c and hv.c
-po	|void *	|more_bodies	|const svtype sv_type|const size_t body_size \
+Cpo	|void *	|more_bodies	|const svtype sv_type|const size_t body_size \
 				|const size_t arena_size
 EXpR	|SV*	|get_and_check_backslash_N_name|NN const char* s	\
 				|NN const char* e			\
diff --git a/embed.h b/embed.h
index c08806128c94..60dfd52b8218 100644
--- a/embed.h
+++ b/embed.h
@@ -386,6 +386,7 @@
 #define newSVOP(a,b,c)		Perl_newSVOP(aTHX_ a,b,c)
 #define newSVREF(a)		Perl_newSVREF(aTHX_ a)
 #define newSV_type(a)		Perl_newSV_type(aTHX_ a)
+#define newSV_type_mortal(a)	Perl_newSV_type_mortal(aTHX_ a)
 #define newSVhek(a)		Perl_newSVhek(aTHX_ a)
 #define newSViv(a)		Perl_newSViv(aTHX_ a)
 #define newSVnv(a)		Perl_newSVnv(aTHX_ a)
@@ -880,6 +881,9 @@
 #define dump_mstats(a)		Perl_dump_mstats(aTHX_ a)
 #define get_mstats(a,b,c)	Perl_get_mstats(aTHX_ a,b,c)
 #endif
+#if defined(PERL_IN_SV_C)
+#define more_sv()		Perl_more_sv(aTHX)
+#endif
 #if defined(PERL_USE_3ARG_SIGHANDLER)
 #define csighandler		Perl_csighandler
 #endif
@@ -1929,7 +1933,6 @@
 #define find_uninit_var(a,b,c,d)	S_find_uninit_var(aTHX_ a,b,c,d)
 #define glob_2number(a)		S_glob_2number(aTHX_ a)
 #define glob_assign_glob(a,b,c)	S_glob_assign_glob(aTHX_ a,b,c)
-#define more_sv()		S_more_sv(aTHX)
 #define not_a_number(a)		S_not_a_number(aTHX_ a)
 #define not_incrementable(a)	S_not_incrementable(aTHX_ a)
 #define ptr_table_find		S_ptr_table_find
diff --git a/gv.c b/gv.c
index 1f06833e1a9b..6792a0f69fda 100644
--- a/gv.c
+++ b/gv.c
@@ -202,7 +202,7 @@ Perl_newGP(pTHX_ GV *const gv)
     Newxz(gp, 1, GP);
     gp->gp_egv = gv; /* allow compiler to reuse gv after this */
 #ifndef PERL_DONT_CREATE_GVSV
-    gp->gp_sv = newSV(0);
+    gp->gp_sv = newSV_type(SVt_NULL);
 #endif
 
     /* PL_curcop may be null here.  E.g.,
@@ -294,7 +294,7 @@ Perl_cvgv_from_hek(pTHX_ CV *cv)
     if (!CvSTASH(cv)) return NULL;
     ASSUME(CvNAME_HEK(cv));
     svp = hv_fetchhek(CvSTASH(cv), CvNAME_HEK(cv), 0);
-    gv = MUTABLE_GV(svp && *svp ? *svp : newSV(0));
+    gv = MUTABLE_GV(svp && *svp ? *svp : newSV_type(SVt_NULL));
     if (!isGV(gv))
         gv_init_pvn(gv, CvSTASH(cv), HEK_KEY(CvNAME_HEK(cv)),
                 HEK_LEN(CvNAME_HEK(cv)),
@@ -580,7 +580,7 @@ S_maybe_add_coresub(pTHX_ HV * const stash, GV *gv,
         ampable = FALSE;
     }
     if (!gv) {
-        gv = (GV *)newSV(0);
+        gv = (GV *)newSV_type(SVt_NULL);
         gv_init(gv, stash, name, len, TRUE);
     }
     GvMULTI_on(gv);
@@ -1359,7 +1359,7 @@ Perl_gv_autoload_pvn(pTHX_ HV *stash, const char *name, STRLEN len, U32 flags)
     if (!isGV(vargv)) {
         gv_init_pvn(vargv, varstash, S_autoload, S_autolen, 0);
 #ifdef PERL_DONT_CREATE_GVSV
-        GvSV(vargv) = newSV(0);
+        GvSV(vargv) = newSV_type(SVt_NULL);
 #endif
     }
     LEAVE;
@@ -2516,7 +2516,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
     /* By this point we should have a stash and a name */
     gvp = (GV**)hv_fetch(stash,name,is_utf8 ? -(I32)len : (I32)len,add);
     if (!gvp || *gvp == (const GV *)&PL_sv_undef) {
-        if (addmg) gv = (GV *)newSV(0);     /* tentatively */
+        if (addmg) gv = (GV *)newSV_type(SVt_NULL);     /* tentatively */
         else return NULL;
     }
     else gv = *gvp, addmg = 0;
@@ -3801,7 +3801,7 @@ Perl_amagic_call(pTHX_ SV *left, SV *right, int method, int flags)
             break;
         case G_LIST:
             if (flags & AMGf_want_list) {
-                res = sv_2mortal((SV *)newAV());
+                res = newSV_type_mortal(SVt_PVAV);
                 av_extend((AV *)res, nret);
                 while (nret--)
                     av_store((AV *)res, nret, POPs);
diff --git a/hv.c b/hv.c
index 34b722809d2c..ab17badbf235 100644
--- a/hv.c
+++ b/hv.c
@@ -200,12 +200,12 @@ static void
 S_hv_notallowed(pTHX_ int flags, const char *key, I32 klen,
                 const char *msg)
 {
-    SV * const sv = sv_newmortal();
+   /* Straight to SVt_PVN here, as needed by sv_setpvn_fresh and
+    * sv_usepvn would otherwise call it */
+    SV * const sv = newSV_type_mortal(SVt_PV);
 
     PERL_ARGS_ASSERT_HV_NOTALLOWED;
 
-    sv_upgrade(sv, SVt_PV); /* Needed by sv_setpvn_fresh and
-                             * sv_usepvn would otherwise call it */
     if (!(flags & HVhek_FREEKEY)) {
         sv_setpvn_fresh(sv, key, klen);
     }
@@ -480,7 +480,7 @@ Perl_hv_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
                                                HV_FETCH_ISSTORE
                                                | HV_DISABLE_UVAR_XKEY
                                                | return_svp,
-                                               newSV(0), hash);
+                                               newSV_type(SVt_NULL), hash);
                         } else {
                             if (flags & HVhek_FREEKEY)
                                 Safefree(key);
@@ -739,7 +739,7 @@ Perl_hv_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
                         break;
                     }
                     /* LVAL fetch which actually needs a store.  */
-                    val = newSV(0);
+                    val = newSV_type(SVt_NULL);
                     HvPLACEHOLDERS(hv)--;
                 } else {
                     /* store */
@@ -793,7 +793,7 @@ Perl_hv_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
         return NULL;
     }
     if (action & HV_FETCH_LVALUE) {
-        val = action & HV_FETCH_EMPTY_HE ? NULL : newSV(0);
+        val = action & HV_FETCH_EMPTY_HE ? NULL : newSV_type(SVt_NULL);
         if (SvMAGICAL(hv)) {
             /* At this point the old hv_fetch code would call to hv_store,
                which in turn might do some tied magic. So we need to make that
@@ -968,6 +968,7 @@ SV *
 Perl_hv_scalar(pTHX_ HV *hv)
 {
     SV *sv;
+    UV u;
 
     PERL_ARGS_ASSERT_HV_SCALAR;
 
@@ -977,8 +978,21 @@ Perl_hv_scalar(pTHX_ HV *hv)
             return magic_scalarpack(hv, mg);
     }
 
-    sv = sv_newmortal();
-    sv_setuv(sv, HvUSEDKEYS(hv));
+    sv = newSV_type_mortal(SVt_IV);
+
+    /* Inlined sv_setuv(sv, HvUSEDKEYS(hv)) follows:*/
+    u = HvUSEDKEYS(hv);
+
+    if (u <= (UV)IV_MAX) {
+        SvIV_set(sv, (IV)u);
+        (void)SvIOK_only(sv);
+        SvTAINT(sv);
+    } else {
+        SvIV_set(sv, 0);
+        SvUV_set(sv, u);
+        (void)SvIOK_only_UV(sv);
+        SvTAINT(sv);
+    }
 
     return sv;
 }
@@ -3247,7 +3261,7 @@ S_refcounted_he_value(pTHX_ const struct refcounted_he *he)
 
     switch(he->refcounted_he_data[0] & HVrhek_typemask) {
     case HVrhek_undef:
-        value = newSV(0);
+        value = newSV_type(SVt_NULL);
         break;
     case HVrhek_delete:
         value = &PL_sv_placeholder;
diff --git a/inline.h b/inline.h
index 7ff7d799a23a..e664d25f6d52 100644
--- a/inline.h
+++ b/inline.h
@@ -134,7 +134,7 @@ Perl_av_fetch_simple(pTHX_ AV *av, SSize_t key, I32 lval)
     assert(key > -1);
 
     if ( (key > AvFILLp(av)) || !AvARRAY(av)[key]) {
-        return lval ? av_store_simple(av,key,newSV(0)) : NULL;
+        return lval ? av_store_simple(av,key,newSV_type(SVt_NULL)) : NULL;
     } else {
         return &AvARRAY(av)[key];
     }
diff --git a/mg.c b/mg.c
index 10813a73165c..83b7581a4c9a 100644
--- a/mg.c
+++ b/mg.c
@@ -877,7 +877,7 @@ Perl_sv_string_from_errnum(pTHX_ int errnum, SV *tgtsv)
 {
     char const *errstr;
     if(!tgtsv)
-        tgtsv = sv_newmortal();
+        tgtsv = newSV_type_mortal(SVt_PV);
     errstr = my_strerror(errnum);
     if(errstr) {
         sv_setpv(tgtsv, errstr);
diff --git a/mro_core.c b/mro_core.c
index 947326eb0f43..85c40db2b5e1 100644
--- a/mro_core.c
+++ b/mro_core.c
@@ -255,7 +255,7 @@ S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
 
     /* not in cache, make a new one */
 
-    retval = MUTABLE_AV(sv_2mortal(MUTABLE_SV(newAV())));
+    retval = MUTABLE_AV(newSV_type_mortal(SVt_PVAV));
     /* We use this later in this function, but don't need a reference to it
        beyond the end of this function, so reference count is fine.  */
     our_name = newSVhek(stashhek);
@@ -347,7 +347,7 @@ S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
                 } else {
                     /* They have no stash.  So create ourselves an ->isa cache
                        as if we'd copied it from what theirs should be.  */
-                    stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
+                    stored = MUTABLE_HV(newSV_type_mortal(SVt_PVHV));
                     (void) hv_stores(stored, "UNIVERSAL", &PL_sv_undef);
                     av_push(retval,
                             newSVhek(HeKEY_hek(hv_store_ent(stored, sv,
@@ -357,7 +357,7 @@ S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
         }
     } else {
         /* We have no parents.  */
-        stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
+        stored = MUTABLE_HV(newSV_type_mortal(SVt_PVHV));
         (void) hv_stores(stored, "UNIVERSAL", &PL_sv_undef);
     }
 
@@ -428,7 +428,7 @@ Perl_mro_get_linear_isa(pTHX_ HV *stash)
             SV **svp;
             SV **ovp = AvARRAY(old);
             SV * const * const oend = ovp + AvFILLp(old) + 1;
-            isa = (AV *)sv_2mortal((SV *)newAV());
+            isa = (AV *)newSV_type_mortal(SVt_PVAV);
             av_extend(isa, AvFILLp(isa) = AvFILLp(old)+1);
             *AvARRAY(isa) = namesv;
             svp = AvARRAY(isa)+1;
@@ -570,7 +570,7 @@ Perl_mro_isa_changed_in(pTHX_ HV* stash)
         if(hv_iterinit(isarev)) {
             /* Only create the hash if we need it; i.e., if isarev has
                any elements. */
-            isa_hashes = (HV *)sv_2mortal((SV *)newHV());
+            isa_hashes = (HV *)newSV_type_mortal(SVt_PVHV);
         }
         while((iter = hv_iternext(isarev))) {
             HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
@@ -817,7 +817,7 @@ Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
     }
     else {
         SV *aname;
-        namesv = sv_2mortal((SV *)newAV());
+        namesv = newSV_type_mortal(SVt_PVAV);
         while (name_count--) {
             if(memEQs(HEK_KEY(*namep), HEK_LEN(*namep), "main")){
                 aname = GvNAMELEN(gv) == 1
@@ -854,9 +854,9 @@ Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
        wrong name. The names must be set on *all* affected stashes before
        we do anything else. (And linearisations must be cleared, too.)
      */
-    stashes = (HV *) sv_2mortal((SV *)newHV());
+    stashes = (HV *) newSV_type_mortal(SVt_PVHV);
     mro_gather_and_rename(
-     stashes, (HV *) sv_2mortal((SV *)newHV()),
+     stashes, (HV *) newSV_type_mortal(SVt_PVHV),
      stash, oldstash, namesv
     );
 
@@ -1119,7 +1119,7 @@ S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
     /* Skip the entire loop if the hash is empty.   */
     if(oldstash && HvTOTALKEYS(oldstash)) {
         xhv = (XPVHV*)SvANY(oldstash);
-        seen = (HV *) sv_2mortal((SV *)newHV());
+        seen = (HV *) newSV_type_mortal(SVt_PVHV);
 
         /* Iterate through entries in the oldstash, adding them to the
            list, meanwhile doing the equivalent of $seen{$key} = 1.
@@ -1164,7 +1164,7 @@ S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
                             SV *aname;
                             items = AvFILLp((AV *)namesv) + 1;
                             svp = AvARRAY((AV *)namesv);
-                            subname = sv_2mortal((SV *)newAV());
+                            subname = newSV_type_mortal(SVt_PVAV);
                             while (items--) {
                                 aname = newSVsv(*svp++);
                                 if (len == 1)
@@ -1247,7 +1247,7 @@ S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
                             SV *aname;
                             items = AvFILLp((AV *)namesv) + 1;
                             svp = AvARRAY((AV *)namesv);
-                            subname = sv_2mortal((SV *)newAV());
+                            subname = newSV_type_mortal(SVt_PVAV);
                             while (items--) {
                                 aname = newSVsv(*svp++);
                                 if (len == 1)
diff --git a/op.c b/op.c
index 6b7bb5b87d32..bb543b3611bf 100644
--- a/op.c
+++ b/op.c
@@ -10964,7 +10964,7 @@ S_op_const_sv(pTHX_ const OP *o, CV *cv, bool allow_lex)
         if (type == OP_CONST && cSVOPo->op_sv)
             sv = cSVOPo->op_sv;
         else if (type == OP_UNDEF && !o->op_private) {
-            sv = newSV(0);
+            sv = newSV_type(SVt_NULL);
             SAVEFREESV(sv);
         }
         else if (allow_lex && type == OP_PADSV) {
@@ -13623,7 +13623,7 @@ Perl_ck_glob(pTHX_ OP *o)
         LEAVE;
     }
 #endif /* !PERL_EXTERNAL_GLOB */
-    gv = (GV *)newSV(0);
+    gv = (GV *)newSV_type(SVt_NULL);
     gv_init(gv, 0, "", 0, 0);
     gv_IOadd(gv);
     op_append_elem(OP_GLOB, o, newGVOP(OP_GV, 0, gv));
@@ -13689,7 +13689,7 @@ Perl_ck_index(pTHX_ OP *o)
             if (   (!SvPOK(sv) || SvNIOKp(sv) || isREGEXP(sv))
                 && SvOK(sv) && !SvROK(sv))
             {
-                sv = newSV(0);
+                sv = newSV_type(SVt_NULL);
                 sv_copypv(sv, kSVOP->op_sv);
                 SvREFCNT_dec_NN(kSVOP->op_sv);
                 kSVOP->op_sv = sv;
diff --git a/pad.c b/pad.c
index bc41a475bb48..b1ea097ebd83 100644
--- a/pad.c
+++ b/pad.c
@@ -719,7 +719,7 @@ Perl_pad_alloc(pTHX_ I32 optype, U32 tmptype)
         pad_reset();
     if (tmptype == SVs_PADMY) { /* Not & because this ‘flag’ is 0.  */
         /* For a my, simply push a null SV onto the end of PL_comppad. */
-        sv = *av_store_simple(PL_comppad, AvFILLp(PL_comppad) + 1, newSV(0));
+        sv = *av_store_simple(PL_comppad, AvFILLp(PL_comppad) + 1, newSV_type(SVt_NULL));
         retval = (PADOFFSET)AvFILLp(PL_comppad);
     }
     else {
@@ -1252,13 +1252,13 @@ S_pad_findlex(pTHX_ const char *namepv, STRLEN namelen, U32 flags, const CV* cv,
                 }
                 if (!*out_capture) {
                     if (namelen != 0 && *namepv == '@')
-                        *out_capture = sv_2mortal(MUTABLE_SV(newAV()));
+                        *out_capture = newSV_type_mortal(SVt_PVAV);
                     else if (namelen != 0 && *namepv == '%')
-                        *out_capture = sv_2mortal(MUTABLE_SV(newHV()));
+                        *out_capture = newSV_type_mortal(SVt_PVHV);
                     else if (namelen != 0 && *namepv == '&')
-                        *out_capture = sv_2mortal(newSV_type(SVt_PVCV));
+                        *out_capture = newSV_type_mortal(SVt_PVCV);
                     else
-                        *out_capture = sv_newmortal();
+                        *out_capture = newSV_type_mortal(SVt_NULL);
                 }
             }
 
@@ -1565,7 +1565,7 @@ Perl_pad_swipe(pTHX_ PADOFFSET po, bool refadjust)
     /* if pad tmps aren't shared between ops, then there's no need to
      * create a new tmp when an existing op is freed */
 #ifdef USE_PAD_RESET
-    PL_curpad[po] = newSV(0);
+    PL_curpad[po] = newSV_type(SVt_NULL);
     SvPADTMP_on(PL_curpad[po]);
 #else
     PL_curpad[po] = NULL;
@@ -2030,7 +2030,7 @@ S_cv_clone_pad(pTHX_ CV *proto, CV *cv, CV *outside, HV *cloned,
                 else if (sigil == '%')
                     sv = MUTABLE_SV(newHV());
                 else
-                    sv = newSV(0);
+                    sv = newSV_type(SVt_NULL);
                 /* reset the 'assign only once' flag on each state var */
                 if (sigil != '&' && SvPAD_STATE(namesv))
                     SvPADSTALE_on(sv);
@@ -2041,7 +2041,7 @@ S_cv_clone_pad(pTHX_ CV *proto, CV *cv, CV *outside, HV *cloned,
             sv = SvREFCNT_inc_NN(ppad[ix]);
         }
         else {
-            sv = newSV(0);
+            sv = newSV_type(SVt_NULL);
             SvPADTMP_on(sv);
         }
         PL_curpad[ix] = sv;
@@ -2063,7 +2063,7 @@ S_cv_clone_pad(pTHX_ CV *proto, CV *cv, CV *outside, HV *cloned,
              */
             bool cloned_in_this_pass;
             if (!cloned)
-                cloned = (HV *)sv_2mortal((SV *)newHV());
+                cloned = (HV *)newSV_type_mortal(SVt_PVHV);
             do {
                 cloned_in_this_pass = FALSE;
                 for (ix = fpad; ix > 0; ix--) {
@@ -2435,7 +2435,7 @@ Perl_pad_push(pTHX_ PADLIST *padlist, int depth)
                     else if (sigil == '%')
                         sv = MUTABLE_SV(newHV());
                     else
-                        sv = newSV(0);
+                        sv = newSV_type(SVt_NULL);
                 }
             }
             else if (PadnamePV(names[ix])) {
@@ -2443,7 +2443,7 @@ Perl_pad_push(pTHX_ PADLIST *padlist, int depth)
             }
             else {
                 /* save temporaries on recursion? */
-                sv = newSV(0);
+                sv = newSV_type(SVt_NULL);
                 SvPADTMP_on(sv);
             }
             AvARRAY(newpad)[ix] = sv;
@@ -2543,7 +2543,7 @@ Perl_padlist_dup(pTHX_ PADLIST *srcpad, CLONE_PARAMS *param)
                             else if (sigil == '%')
                                 sv = MUTABLE_SV(newHV());
                             else
-                                sv = newSV(0);
+                                sv = newSV_type(SVt_NULL);
                             pad1a[ix] = sv;
                         }
                     }
@@ -2554,7 +2554,7 @@ Perl_padlist_dup(pTHX_ PADLIST *srcpad, CLONE_PARAMS *param)
                 }
                 else {
                     /* save temporaries on recursion? */
-                    SV * const sv = newSV(0);
+                    SV * const sv = newSV_type(SVt_NULL);
                     pad1a[ix] = sv;
 
                     /* SvREFCNT(oldpad[ix]) != 1 for some code in threads.xs
diff --git a/perl.h b/perl.h
index d05cc2928c1e..32c7afa5cd84 100644
--- a/perl.h
+++ b/perl.h
@@ -1252,12 +1252,6 @@ Use L</UV> to declare variables of the maximum usable size on this platform.
           (((U64)(x) & UINT64_C(0xff00000000000000)) >> 56) ))
 # endif
 
-/* The old value was hard coded at 1008. (4096-16) seems to be a bit faster,
-   at least on FreeBSD.  YMMV, so experiment.  */
-#ifndef PERL_ARENA_SIZE
-#define PERL_ARENA_SIZE 4080
-#endif
-
 /* Maximum level of recursion */
 #ifndef PERL_SUB_DEPTH_WARN
 #define PERL_SUB_DEPTH_WARN 100
@@ -7160,6 +7154,7 @@ cannot have changed since the precalculation.
 START_EXTERN_C
 
 #  include "inline.h"
+#  include "sv_inline.h"
 
 END_EXTERN_C
 
diff --git a/pp.c b/pp.c
index b53fd8796832..b0c6e42031c0 100644
--- a/pp.c
+++ b/pp.c
@@ -130,7 +130,7 @@ S_rv2gv(pTHX_ SV *sv, const bool vivify_sv, const bool strict,
                     HV *stash;
                     if (SvREADONLY(sv))
                         Perl_croak_no_modify();
-                    gv = MUTABLE_GV(newSV(0));
+                    gv = MUTABLE_GV(newSV_type(SVt_NULL));
                     stash = CopSTASH(PL_curcop);
                     if (SvTYPE(stash) != SVt_PVHV) stash = NULL;
                     if (cUNOP->op_targ) {
@@ -313,7 +313,7 @@ PP(pp_pos)
     dSP; dTOPss;
 
     if (PL_op->op_flags & OPf_MOD || LVRET) {
-        SV * const ret = sv_2mortal(newSV_type(SVt_PVLV));/* Not TARG RT#67838 */
+        SV * const ret = newSV_type_mortal(SVt_PVLV);/* Not TARG RT#67838 */
         sv_magic(ret, NULL, PERL_MAGIC_pos, NULL, 0);
         LvTYPE(ret) = '.';
         LvTARG(ret) = SvREFCNT_inc_simple(sv);
@@ -467,7 +467,7 @@ S_refto(pTHX_ SV *sv)
         SvTEMP_off(sv);
         SvREFCNT_inc_void_NN(sv);
     }
-    rv = sv_newmortal();
+    rv = newSV_type_mortal(SVt_IV);
     sv_setrv_noinc(rv, sv);
     return rv;
 }
@@ -938,7 +938,7 @@ PP(pp_undef)
             Newxz(gp, 1, GP);
             GvGP_set(sv, gp_ref(gp));
 #ifndef PERL_DONT_CREATE_GVSV
-            GvSV(sv) = newSV(0);
+            GvSV(sv) = newSV_type(SVt_NULL);
 #endif
             GvLINE(sv) = CopLINE(PL_curcop);
             GvEGV(sv) = MUTABLE_GV(sv);
@@ -3300,7 +3300,7 @@ PP(pp_substr)
     }
     if (lvalue && !repl_sv) {
         SV * ret;
-        ret = sv_2mortal(newSV_type(SVt_PVLV));  /* Not TARG RT#67838 */
+        ret = newSV_type_mortal(SVt_PVLV);  /* Not TARG RT#67838 */
         sv_magic(ret, NULL, PERL_MAGIC_substr, NULL, 0);
         LvTYPE(ret) = 'x';
         LvTARG(ret) = SvREFCNT_inc_simple(sv);
@@ -3432,7 +3432,7 @@ PP(pp_vec)
     retuv = errflags ? 0 : do_vecget(src, offset, size);
 
     if (lvalue) {			/* it's an lvalue! */
-        ret = sv_2mortal(newSV_type(SVt_PVLV));  /* Not TARG RT#67838 */
+        ret = newSV_type_mortal(SVt_PVLV);  /* Not TARG RT#67838 */
         sv_magic(ret, NULL, PERL_MAGIC_vec, NULL, 0);
         LvTYPE(ret) = 'v';
         LvTARG(ret) = SvREFCNT_inc_simple(src);
@@ -3499,7 +3499,7 @@ PP(pp_index)
 
             /* At this point, pv is a malloc()ed string. So donate it to temp
                to ensure it will get free()d  */
-            little = temp = newSV(0);
+            little = temp = newSV_type(SVt_NULL);
             sv_usepvn(temp, pv, llen);
             little_p = SvPVX(little);
         } else {
@@ -5534,13 +5534,13 @@ PP(pp_anonhash)
         {
             MARK++;
             SvGETMAGIC(*MARK);
-            val = newSV(0);
+            val = newSV_type(SVt_NULL);
             sv_setsv_nomg(val, *MARK);
         }
         else
         {
             Perl_ck_warner(aTHX_ packWARN(WARN_MISC), "Odd number of elements in anonymous hash");
-            val = newSV(0);
+            val = newSV_type(SVt_NULL);
         }
         (void)hv_store_ent(hv,key,val,0);
     }
@@ -5791,7 +5791,7 @@ PP(pp_push)
         for (++MARK; MARK <= SP; MARK++) {
             SV *sv;
             if (*MARK) SvGETMAGIC(*MARK);
-            sv = newSV(0);
+            sv = newSV_type(SVt_NULL);
             if (*MARK)
                 sv_setsv_nomg(sv, *MARK);
             av_store(ary, AvFILLp(ary)+1, sv);
@@ -6830,7 +6830,7 @@ PP(pp_refassign)
 PP(pp_lvref)
 {
     dSP;
-    SV * const ret = sv_2mortal(newSV_type(SVt_PVMG));
+    SV * const ret = newSV_type_mortal(SVt_PVMG);
     SV * const elem = PL_op->op_private & OPpLVREF_ELEM ? POPs : NULL;
     SV * const arg = PL_op->op_flags & OPf_STACKED ? POPs : NULL;
     MAGIC * const mg = sv_magicext(ret, arg, PERL_MAGIC_lvref,
@@ -6898,7 +6898,7 @@ PP(pp_lvrefslice)
             else
                 S_localise_helem_lval(aTHX_ (HV *)av, elemsv, can_preserve);
         }
-        *MARK = sv_2mortal(newSV_type(SVt_PVMG));
+        *MARK = newSV_type_mortal(SVt_PVMG);
         sv_magic(*MARK,(SV *)av,PERL_MAGIC_lvref,(char *)elemsv,HEf_SVKEY);
     }
     RETURN;
@@ -7026,7 +7026,7 @@ PP(pp_argelem)
             SV *tmpsv;
             SV **svp = av_fetch(defav, ix + i, FALSE);
             SV *val = svp ? *svp : &PL_sv_undef;
-            tmpsv = newSV(0);
+            tmpsv = newSV_type(SVt_NULL);
             sv_setsv(tmpsv, val);
             av_store((AV*)targ, i++, tmpsv);
             TAINT_NOT;
@@ -7042,7 +7042,7 @@ PP(pp_argelem)
             /* see "target should usually be empty" comment above */
             for (i = 0; i < argc; i++) {
                 SV **svp = av_fetch(defav, ix + i, FALSE);
-                SV *newsv = newSV(0);
+                SV *newsv = newSV_type(SVt_NULL);
                 sv_setsv_flags(newsv,
                                 svp ? *svp : &PL_sv_undef,
                                 (SV_DO_COW_SVSETSV|SV_NOSTEAL));
@@ -7071,7 +7071,7 @@ PP(pp_argelem)
             argc -= 2;
             if (UNLIKELY(SvGMAGICAL(key)))
                 key = sv_mortalcopy(key);
-            tmpsv = newSV(0);
+            tmpsv = newSV_type(SVt_NULL);
             sv_setsv(tmpsv, val);
             hv_store_ent((HV*)targ, key, tmpsv, 0);
             TAINT_NOT;
diff --git a/pp_ctl.c b/pp_ctl.c
index 44289bbd689d..c28fe258415a 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -4386,7 +4386,7 @@ S_require_file(pTHX_ SV *sv)
            than hanging another SV from it. In turn, filter_add() optionally
            takes the SV to use as the filter (or creates a new SV if passed
            NULL), so simply pass in whatever value filter_cache has.  */
-        SV * const fc = filter_cache ? newSV(0) : NULL;
+        SV * const fc = filter_cache ? newSV_type(SVt_NULL) : NULL;
         SV *datasv;
         if (fc) sv_copypv(fc, filter_cache);
         datasv = filter_add(S_run_user_filter, fc);
@@ -5169,12 +5169,10 @@ S_do_smartmatch(pTHX_ HV *seen_this, HV *seen_other, const bool copied)
                 const Size_t other_len = av_count(other_av);
 
                 if (NULL == seen_this) {
-                    seen_this = newHV();
-                    (void) sv_2mortal(MUTABLE_SV(seen_this));
+                    seen_this = (HV*)newSV_type_mortal(SVt_PVHV);
                 }
                 if (NULL == seen_other) {
-                    seen_other = newHV();
-                    (void) sv_2mortal(MUTABLE_SV(seen_other));
+                    seen_other = (HV*)newSV_type_mortal(SVt_PVHV);
                 }
                 for(i = 0; i < other_len; ++i) {
                     SV * const * const this_elem = av_fetch(MUTABLE_AV(SvRV(e)), i, FALSE);
@@ -5882,7 +5880,7 @@ S_run_user_filter(pTHX_ int idx, SV *buf_sv, int maxlen)
        don't want to pass it in a second time.
        I'm going to use a mortal in case the upstream filter croaks.  */
     upstream = ((SvOK(buf_sv) && sv_len(buf_sv)) || SvGMAGICAL(buf_sv))
-        ? sv_newmortal() : buf_sv;
+        ? newSV_type_mortal(SVt_PV) : buf_sv;
     SvUPGRADE(upstream, SVt_PV);
         
     if (filter_has_file) {
diff --git a/pp_hot.c b/pp_hot.c
index 477cdd48b841..67b255e2e760 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -991,7 +991,7 @@ PP(pp_multiconcat)
                    )
             )
             {
-                SV *tmp = sv_newmortal();
+                SV *tmp = newSV_type_mortal(SVt_PV);
                 sv_copypv(tmp, left);
                 SvSETMAGIC(tmp);
                 left = tmp;
@@ -2868,7 +2868,7 @@ PP(pp_qr)
     REGEXP * rx = PM_GETRE(pm);
     regexp *prog = ReANY(rx);
     SV * const pkg = RXp_ENGINE(prog)->qr_package(aTHX_ (rx));
-    SV * const rv = sv_newmortal();
+    SV * const rv = newSV_type_mortal(SVt_IV);
     CV **cvp;
     CV *cv;
 
@@ -3406,8 +3406,7 @@ PP(pp_helem)
             if (!defer) {
                 DIE(aTHX_ PL_no_helem_sv, SVfARG(keysv));
             }
-            lv = sv_newmortal();
-            sv_upgrade(lv, SVt_PVLV);
+            lv = newSV_type_mortal(SVt_PVLV);
             LvTYPE(lv) = 'y';
             sv_magic(lv, key2 = newSVsv(keysv), PERL_MAGIC_defelem, NULL, 0);
             SvREFCNT_dec_NN(key2);	/* sv_magic() increments refcount */
@@ -3846,8 +3845,7 @@ PP(pp_multideref)
                             SV* key2;
                             if (!defer)
                                 DIE(aTHX_ PL_no_helem_sv, SVfARG(keysv));
-                            lv = sv_newmortal();
-                            sv_upgrade(lv, SVt_PVLV);
+                            lv = newSV_type_mortal(SVt_PVLV);
                             LvTYPE(lv) = 'y';
                             sv_magic(lv, key2 = newSVsv(keysv),
                                                 PERL_MAGIC_defelem, NULL, 0);
@@ -4895,7 +4893,7 @@ Perl_leave_adjust_stacks(pTHX_ SV **from_sp, SV **to_sp, U8 gimme, int pass)
                  *    ++PL_tmps_ix, moving the previous occupant there
                  *    instead.
                  */
-                SV *newsv = newSV(0);
+                SV *newsv = newSV_type(SVt_NULL);
 
                 PL_tmps_stack[++PL_tmps_ix] = *tmps_basep;
                 /* put it on the tmps stack early so it gets freed if we die */
@@ -5510,7 +5508,7 @@ Perl_vivify_ref(pTHX_ SV *sv, U32 to_what)
         prepare_SV_for_RV(sv);
         switch (to_what) {
         case OPpDEREF_SV:
-            SvRV_set(sv, newSV(0));
+            SvRV_set(sv, newSV_type(SVt_NULL));
             break;
         case OPpDEREF_AV:
             SvRV_set(sv, MUTABLE_SV(newAV()));
diff --git a/proto.h b/proto.h
index 2df7f0a30fc5..4bd0d4e39f89 100644
--- a/proto.h
+++ b/proto.h
@@ -2482,9 +2482,18 @@ PERL_CALLCONV OP*	Perl_newSVREF(pTHX_ OP* o)
 #define PERL_ARGS_ASSERT_NEWSVREF	\
 	assert(o)
 
-PERL_CALLCONV SV*	Perl_newSV_type(pTHX_ const svtype type)
+#ifndef PERL_NO_INLINE_FUNCTIONS
+PERL_STATIC_INLINE SV*	Perl_newSV_type(pTHX_ const svtype type)
 			__attribute__warn_unused_result__;
 #define PERL_ARGS_ASSERT_NEWSV_TYPE
+#endif
+
+#ifndef PERL_NO_INLINE_FUNCTIONS
+PERL_STATIC_FORCE_INLINE SV*	Perl_newSV_type_mortal(pTHX_ const svtype type)
+			__attribute__warn_unused_result__
+			__attribute__always_inline__;
+#define PERL_ARGS_ASSERT_NEWSV_TYPE_MORTAL
+#endif
 
 PERL_CALLCONV SV*	Perl_newSVavdefelem(pTHX_ AV *av, SSize_t ix, bool extendible)
 			__attribute__warn_unused_result__;
@@ -6452,7 +6461,7 @@ STATIC bool	S_glob_2number(pTHX_ GV* const gv);
 STATIC void	S_glob_assign_glob(pTHX_ SV *const dsv, SV *const ssv, const int dtype);
 #define PERL_ARGS_ASSERT_GLOB_ASSIGN_GLOB	\
 	assert(dsv); assert(ssv)
-STATIC SV *	S_more_sv(pTHX);
+PERL_CALLCONV SV *	Perl_more_sv(pTHX);
 #define PERL_ARGS_ASSERT_MORE_SV
 STATIC void	S_not_a_number(pTHX_ SV *const sv);
 #define PERL_ARGS_ASSERT_NOT_A_NUMBER	\
diff --git a/regcomp.c b/regcomp.c
index cec3194efb7b..9990c074d94f 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -16673,8 +16673,8 @@ S_handle_regex_sets(pTHX_ RExC_state_t *pRExC_state, SV** return_invlist,
      * so that everything gets evaluated down to a single operand, which is the
      * result */
 
-    sv_2mortal((SV *)(stack = newAV()));
-    sv_2mortal((SV *)(fence_stack = newAV()));
+    stack = (AV*)newSV_type_mortal(SVt_PVAV);
+    fence_stack = (AV*)newSV_type_mortal(SVt_PVAV);
 
     while (RExC_parse < RExC_end) {
         I32 top_index;              /* Index of top-most element in 'stack' */
diff --git a/regexec.c b/regexec.c
index 47a038580c81..8f9ad6f3ac7c 100644
--- a/regexec.c
+++ b/regexec.c
@@ -3712,7 +3712,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
            magic belonging to this SV.
            Not newSVsv, either, as it does not COW.
         */
-        reginfo->sv = newSV(0);
+        reginfo->sv = newSV_type(SVt_NULL);
         SvSetSV_nosteal(reginfo->sv, sv);
         SAVEFREESV(reginfo->sv);
     }
diff --git a/scope.c b/scope.c
index 5294e0aa044f..62801c419ad5 100644
--- a/scope.c
+++ b/scope.c
@@ -232,7 +232,7 @@ S_save_scalar_at(pTHX_ SV **sptr, const U32 flags)
     if (flags & SAVEf_KEEPOLDELEM)
         sv = osv;
     else {
-        sv  = (*sptr = newSV(0));
+        sv  = (*sptr = newSV_type(SVt_NULL));
         if (SvTYPE(osv) >= SVt_PVMG && SvMAGIC(osv))
             mg_localize(osv, sv, cBOOL(flags & SAVEf_SETMAGIC));
     }
@@ -1264,7 +1264,7 @@ Perl_leave_scope(pTHX_ I32 base)
                         CvLEXICAL_on(*svp);
                         break;
                     }
-                    default:	*svp = newSV(0);		break;
+                    default:	*svp = newSV_type(SVt_NULL);		break;
                     }
                     SvREFCNT_dec_NN(sv); /* Cast current value to the winds. */
                     /* preserve pad nature, but also mark as not live
diff --git a/sv.c b/sv.c
index 0c8958789a7c..0624c49075cb 100644
--- a/sv.c
+++ b/sv.c
@@ -230,16 +230,6 @@ Public API:
  * "A time to plant, and a time to uproot what was planted..."
  */
 
-#ifdef PERL_MEM_LOG
-#  define MEM_LOG_NEW_SV(sv, file, line, func)	\
-            Perl_mem_log_new_sv(sv, file, line, func)
-#  define MEM_LOG_DEL_SV(sv, file, line, func)	\
-            Perl_mem_log_del_sv(sv, file, line, func)
-#else
-#  define MEM_LOG_NEW_SV(sv, file, line, func)	NOOP
-#  define MEM_LOG_DEL_SV(sv, file, line, func)	NOOP
-#endif
-
 #ifdef DEBUG_LEAKING_SCALARS
 #  define FREE_SV_DEBUG_FILE(sv) STMT_START { \
         if ((sv)->sv_debug_file) PerlMemShared_free((sv)->sv_debug_file); \
@@ -252,21 +242,6 @@ Public API:
 #  define DEBUG_SV_SERIAL(sv)	NOOP
 #endif
 
-#ifdef PERL_POISON
-#  define SvARENA_CHAIN(sv)	((sv)->sv_u.svu_rv)
-#  define SvARENA_CHAIN_SET(sv,val)	(sv)->sv_u.svu_rv = MUTABLE_SV((val))
-/* Whilst I'd love to do this, it seems that things like to check on
-   unreferenced scalars
-#  define POISON_SV_HEAD(sv)	PoisonNew(sv, 1, struct STRUCT_SV)
-*/
-#  define POISON_SV_HEAD(sv)	PoisonNew(&SvANY(sv), 1, void *), \
-                                PoisonNew(&SvREFCNT(sv), 1, U32)
-#else
-#  define SvARENA_CHAIN(sv)	SvANY(sv)
-#  define SvARENA_CHAIN_SET(sv,val)	SvANY(sv) = (void *)(val)
-#  define POISON_SV_HEAD(sv)
-#endif
-
 /* Mark an SV head as unused, and add to free list.
  *
  * If SVf_BREAK is set, skip adding it to the free list, as this SV had
@@ -289,18 +264,11 @@ Public API:
         --PL_sv_count;					\
     } STMT_END
 
-#define uproot_SV(p) \
-    STMT_START {					\
-        (p) = PL_sv_root;				\
-        PL_sv_root = MUTABLE_SV(SvARENA_CHAIN(p));		\
-        ++PL_sv_count;					\
-    } STMT_END
-
 
 /* make some more SVs by adding another arena */
 
-STATIC SV*
-S_more_sv(pTHX)
+SV*
+Perl_more_sv(pTHX)
 {
     SV* sv;
     char *chunk;                /* must use New here to match call to */
@@ -310,58 +278,6 @@ S_more_sv(pTHX)
     return sv;
 }
 
-/* new_SV(): return a new, empty SV head */
-
-#ifdef DEBUG_LEAKING_SCALARS
-/* provide a real function for a debugger to play with */
-STATIC SV*
-S_new_SV(pTHX_ const char *file, int line, const char *func)
-{
-    SV* sv;
-
-    if (PL_sv_root)
-        uproot_SV(sv);
-    else
-        sv = S_more_sv(aTHX);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
-    sv->sv_debug_optype = PL_op ? PL_op->op_type : 0;
-    sv->sv_debug_line = (U16) (PL_parser && PL_parser->copline != NOLINE
-                ? PL_parser->copline
-                :  PL_curcop
-                    ? CopLINE(PL_curcop)
-                    : 0
-            );
-    sv->sv_debug_inpad = 0;
-    sv->sv_debug_parent = NULL;
-    sv->sv_debug_file = PL_curcop ? savesharedpv(CopFILE(PL_curcop)): NULL;
-
-    sv->sv_debug_serial = PL_sv_serial++;
-
-    MEM_LOG_NEW_SV(sv, file, line, func);
-    DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%" UVxf ": (%05ld) new_SV (from %s:%d [%s])\n",
-            PTR2UV(sv), (long)sv->sv_debug_serial, file, line, func));
-
-    return sv;
-}
-#  define new_SV(p) (p)=S_new_SV(aTHX_ __FILE__, __LINE__, FUNCTION__)
-
-#else
-#  define new_SV(p) \
-    STMT_START {					\
-        if (PL_sv_root)					\
-            uproot_SV(p);				\
-        else						\
-            (p) = S_more_sv(aTHX);			\
-        SvANY(p) = 0;					\
-        SvREFCNT(p) = 1;				\
-        SvFLAGS(p) = 0;					\
-        MEM_LOG_NEW_SV(p, __FILE__, __LINE__, FUNCTION__);  \
-    } STMT_END
-#endif
-
-
 /* del_SV(): return an empty SV head to the free list */
 
 #ifdef DEBUGGING
@@ -768,8 +684,12 @@ Perl_sv_free_arenas(pTHX)
 }
 
 /*
-  Here are mid-level routines that manage the allocation of bodies out
-  of the various arenas.  There are 4 kinds of arenas:
+  Historically, here were mid-level routines that manage the
+  allocation of bodies out of the various arenas. Some of these
+  routines and related definitions remain here, but otherse were
+  moved into sv_inline.h to facilitate inlining of newSV_type().
+
+  There are 4 kinds of arenas:
 
   1. SV-head arenas, which are discussed and handled above
   2. regular body arenas
@@ -871,173 +791,6 @@ available in hv.c. Similarly SVt_IV is re-used for HVAUX_ARENA_ROOT_IX.
 
 */
 
-typedef struct xpvhv_with_aux XPVHV_WITH_AUX;
-
-struct body_details {
-    U8 body_size;	/* Size to allocate  */
-    U8 copy;		/* Size of structure to copy (may be shorter)  */
-    U8 offset;		/* Size of unalloced ghost fields to first alloced field*/
-    PERL_BITFIELD8 type : 4;        /* We have space for a sanity check. */
-    PERL_BITFIELD8 cant_upgrade : 1;/* Cannot upgrade this type */
-    PERL_BITFIELD8 zero_nv : 1;     /* zero the NV when upgrading from this */
-    PERL_BITFIELD8 arena : 1;       /* Allocated from an arena */
-    U32 arena_size;                 /* Size of arena to allocate */
-};
-
-#define ALIGNED_TYPE_NAME(name) name##_aligned
-#define ALIGNED_TYPE(name) 		\
-    typedef union { 	\
-        name align_me;				\
-        NV nv;				\
-        IV iv;				\
-    } ALIGNED_TYPE_NAME(name)
-
-ALIGNED_TYPE(regexp);
-ALIGNED_TYPE(XPVGV);
-ALIGNED_TYPE(XPVLV);
-ALIGNED_TYPE(XPVAV);
-ALIGNED_TYPE(XPVHV);
-ALIGNED_TYPE(XPVHV_WITH_AUX);
-ALIGNED_TYPE(XPVCV);
-ALIGNED_TYPE(XPVFM);
-ALIGNED_TYPE(XPVIO);
-
-#define HADNV FALSE
-#define NONV TRUE
-
-
-#ifdef PURIFY
-/* With -DPURFIY we allocate everything directly, and don't use arenas.
-   This seems a rather elegant way to simplify some of the code below.  */
-#define HASARENA FALSE
-#else
-#define HASARENA TRUE
-#endif
-#define NOARENA FALSE
-
-/* Size the arenas to exactly fit a given number of bodies.  A count
-   of 0 fits the max number bodies into a PERL_ARENA_SIZE.block,
-   simplifying the default.  If count > 0, the arena is sized to fit
-   only that many bodies, allowing arenas to be used for large, rare
-   bodies (XPVFM, XPVIO) without undue waste.  The arena size is
-   limited by PERL_ARENA_SIZE, so we can safely oversize the
-   declarations.
- */
-#define FIT_ARENA0(body_size)				\
-    ((size_t)(PERL_ARENA_SIZE / body_size) * body_size)
-#define FIT_ARENAn(count,body_size)			\
-    ( count * body_size <= PERL_ARENA_SIZE)		\
-    ? count * body_size					\
-    : FIT_ARENA0 (body_size)
-#define FIT_ARENA(count,body_size)			\
-   (U32)(count 						\
-    ? FIT_ARENAn (count, body_size)			\
-    : FIT_ARENA0 (body_size))
-
-/* Calculate the length to copy. Specifically work out the length less any
-   final padding the compiler needed to add.  See the comment in sv_upgrade
-   for why copying the padding proved to be a bug.  */
-
-#define copy_length(type, last_member) \
-        STRUCT_OFFSET(type, last_member) \
-        + sizeof (((type*)SvANY((const SV *)0))->last_member)
-
-static const struct body_details bodies_by_type[] = {
-    /* HEs use this offset for their arena.  */
-    { 0, 0, 0, SVt_NULL, FALSE, NONV, NOARENA, 0 },
-
-    /* IVs are in the head, so the allocation size is 0.  */
-    { 0,
-      sizeof(IV), /* This is used to copy out the IV body.  */
-      STRUCT_OFFSET(XPVIV, xiv_iv), SVt_IV, FALSE, NONV,
-      NOARENA /* IVS don't need an arena  */, 0
-    },
-
-#if NVSIZE <= IVSIZE
-    { 0, sizeof(NV),
-      STRUCT_OFFSET(XPVNV, xnv_u),
-      SVt_NV, FALSE, HADNV, NOARENA, 0 },
-#else
-    { sizeof(NV), sizeof(NV),
-      STRUCT_OFFSET(XPVNV, xnv_u),
-      SVt_NV, FALSE, HADNV, HASARENA, FIT_ARENA(0, sizeof(NV)) },
-#endif
-
-    { sizeof(XPV) - STRUCT_OFFSET(XPV, xpv_cur),
-      copy_length(XPV, xpv_len) - STRUCT_OFFSET(XPV, xpv_cur),
-      + STRUCT_OFFSET(XPV, xpv_cur),
-      SVt_PV, FALSE, NONV, HASARENA,
-      FIT_ARENA(0, sizeof(XPV) - STRUCT_OFFSET(XPV, xpv_cur)) },
-
-    { sizeof(XINVLIST) - STRUCT_OFFSET(XPV, xpv_cur),
-      copy_length(XINVLIST, is_offset) - STRUCT_OFFSET(XPV, xpv_cur),
-      + STRUCT_OFFSET(XPV, xpv_cur),
-      SVt_INVLIST, TRUE, NONV, HASARENA,
-      FIT_ARENA(0, sizeof(XINVLIST) - STRUCT_OFFSET(XPV, xpv_cur)) },
-
-    { sizeof(XPVIV) - STRUCT_OFFSET(XPV, xpv_cur),
-      copy_length(XPVIV, xiv_u) - STRUCT_OFFSET(XPV, xpv_cur),
-      + STRUCT_OFFSET(XPV, xpv_cur),
-      SVt_PVIV, FALSE, NONV, HASARENA,
-      FIT_ARENA(0, sizeof(XPVIV) - STRUCT_OFFSET(XPV, xpv_cur)) },
-
-    { sizeof(XPVNV) - STRUCT_OFFSET(XPV, xpv_cur),
-      copy_length(XPVNV, xnv_u) - STRUCT_OFFSET(XPV, xpv_cur),
-      + STRUCT_OFFSET(XPV, xpv_cur),
-      SVt_PVNV, FALSE, HADNV, HASARENA,
-      FIT_ARENA(0, sizeof(XPVNV) - STRUCT_OFFSET(XPV, xpv_cur)) },
-
-    { sizeof(XPVMG), copy_length(XPVMG, xnv_u), 0, SVt_PVMG, FALSE, HADNV,
-      HASARENA, FIT_ARENA(0, sizeof(XPVMG)) },
-
-    { sizeof(ALIGNED_TYPE_NAME(regexp)),
-      sizeof(regexp),
-      0,
-      SVt_REGEXP, TRUE, NONV, HASARENA,
-      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(regexp)))
-    },
-
-    { sizeof(ALIGNED_TYPE_NAME(XPVGV)), sizeof(XPVGV), 0, SVt_PVGV, TRUE, HADNV,
-      HASARENA, FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVGV))) },
-
-    { sizeof(ALIGNED_TYPE_NAME(XPVLV)), sizeof(XPVLV), 0, SVt_PVLV, TRUE, HADNV,
-      HASARENA, FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVLV))) },
-
-    { sizeof(ALIGNED_TYPE_NAME(XPVAV)),
-      copy_length(XPVAV, xav_alloc),
-      0,
-      SVt_PVAV, TRUE, NONV, HASARENA,
-      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVAV))) },
-
-    { sizeof(ALIGNED_TYPE_NAME(XPVHV)),
-      copy_length(XPVHV, xhv_max),
-      0,
-      SVt_PVHV, TRUE, NONV, HASARENA,
-      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVHV))) },
-
-    { sizeof(ALIGNED_TYPE_NAME(XPVCV)),
-      sizeof(XPVCV),
-      0,
-      SVt_PVCV, TRUE, NONV, HASARENA,
-      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVCV))) },
-
-    { sizeof(ALIGNED_TYPE_NAME(XPVFM)),
-      sizeof(XPVFM),
-      0,
-      SVt_PVFM, TRUE, NONV, NOARENA,
-      FIT_ARENA(20, sizeof(ALIGNED_TYPE_NAME(XPVFM))) },
-
-    { sizeof(ALIGNED_TYPE_NAME(XPVIO)),
-      sizeof(XPVIO),
-      0,
-      SVt_PVIO, TRUE, NONV, HASARENA,
-      FIT_ARENA(24, sizeof(ALIGNED_TYPE_NAME(XPVIO))) },
-};
-
-#define new_body_allocated(sv_type)		\
-    (void *)((char *)S_new_body(aTHX_ sv_type)	\
-             - bodies_by_type[sv_type].offset)
-
 /* return a thing to the free list */
 
 #define del_body(thing, root)				\
@@ -1047,35 +800,6 @@ static const struct body_details bodies_by_type[] = {
         *root = (void*)thing_copy;			\
     } STMT_END
 
-#ifdef PURIFY
-#if !(NVSIZE <= IVSIZE)
-#  define new_XNV()	safemalloc(sizeof(XPVNV))
-#endif
-#define new_XPVNV()	safemalloc(sizeof(XPVNV))
-#define new_XPVMG()	safemalloc(sizeof(XPVMG))
-
-#define del_body_by_type(p, type)       safefree(p)
-
-#else /* !PURIFY */
-
-#if !(NVSIZE <= IVSIZE)
-#  define new_XNV()	new_body_allocated(SVt_NV)
-#endif
-#define new_XPVNV()	new_body_allocated(SVt_PVNV)
-#define new_XPVMG()	new_body_allocated(SVt_PVMG)
-
-#define del_body_by_type(p, type)                               \
-    del_body(p + bodies_by_type[(type)].offset,                 \
-             &PL_body_roots[(type)])
-
-#endif /* PURIFY */
-
-/* no arena for you! */
-
-#define new_NOARENA(details) \
-        safemalloc((details)->body_size + (details)->offset)
-#define new_NOARENAZ(details) \
-        safecalloc((details)->body_size + (details)->offset, 1)
 
 void *
 Perl_more_bodies (pTHX_ const svtype sv_type, const size_t body_size,
@@ -1165,40 +889,6 @@ Perl_more_bodies (pTHX_ const svtype sv_type, const size_t body_size,
     }
 }
 
-#ifndef PURIFY
-
-/* grab a new thing from the arena's free list, allocating more if necessary. */
-#define new_body_from_arena(xpv, root_index, type_meta) \
-    STMT_START { \
-        void ** const r3wt = &PL_body_roots[root_index]; \
-        xpv = (PTR_TBL_ENT_t*) (*((void **)(r3wt))      \
-          ? *((void **)(r3wt)) : Perl_more_bodies(aTHX_ root_index, \
-                                             type_meta.body_size,\
-                                             type_meta.arena_size)); \
-        *(r3wt) = *(void**)(xpv); \
-    } STMT_END
-
-PERL_STATIC_INLINE void *
-S_new_body(pTHX_ const svtype sv_type)
-{
-    void *xpv;
-    new_body_from_arena(xpv, sv_type, bodies_by_type[sv_type]);
-    return xpv;
-}
-
-#endif
-
-static const struct body_details fake_rv =
-    { 0, 0, 0, SVt_IV, FALSE, NONV, NOARENA, 0 };
-
-static const struct body_details fake_hv_with_aux =
-    /* The SVt_IV arena is used for (larger) PVHV bodies.  */
-    { sizeof(ALIGNED_TYPE_NAME(XPVHV_WITH_AUX)),
-      copy_length(XPVHV, xhv_max),
-      0,
-      SVt_PVHV, TRUE, NONV, HASARENA,
-      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVHV_WITH_AUX))) };
-
 /*
 =for apidoc sv_upgrade
 
@@ -5868,9 +5558,10 @@ Perl_newSV(pTHX_ const STRLEN len)
 {
     SV *sv;
 
-    new_SV(sv);
-    if (len) {
-        sv_upgrade(sv, SVt_PV);
+    if (!len)
+        new_SV(sv);
+    else {
+        sv = newSV_type(SVt_PV);
         sv_grow_fresh(sv, len + 1);
     }
     return sv;
@@ -8674,7 +8365,7 @@ Perl_sv_collxfrm_flags(pTHX_ SV *const sv, STRLEN *const nxp, const I32 flags)
 static char *
 S_sv_gets_append_to_utf8(pTHX_ SV *const sv, PerlIO *const fp, I32 append)
 {
-    SV * const tsv = newSV(0);
+    SV * const tsv = newSV_type(SVt_NULL);
     ENTER;
     SAVEFREESV(tsv);
     sv_gets(tsv, fp, 0);
@@ -9681,8 +9372,7 @@ Perl_newSVpvn_flags(pTHX_ const char *const s, const STRLEN len, const U32 flags
     /* All the flags we don't support must be zero.
        And we're new code so I'm going to assert this from the start.  */
     assert(!(flags & ~(SVf_UTF8|SVs_TEMP)));
-    new_SV(sv);
-    sv_upgrade(sv, SVt_PV);
+    sv = newSV_type(SVt_PV);
     sv_setpvn_fresh(sv,s,len);
 
     /* This code used to do a sv_2mortal(), however we now unroll the call to
@@ -9750,10 +9440,7 @@ to call C<strlen> use C<newSVpvn> instead (calling C<strlen> yourself).
 SV *
 Perl_newSVpv(pTHX_ const char *const s, const STRLEN len)
 {
-    SV *sv;
-
-    new_SV(sv);
-    sv_upgrade(sv, SVt_PV);
+    SV *sv = newSV_type(SVt_PV);
     sv_setpvn_fresh(sv, s, len || s == NULL ? len : strlen(s));
     return sv;
 }
@@ -9774,9 +9461,7 @@ undefined.
 SV *
 Perl_newSVpvn(pTHX_ const char *const buffer, const STRLEN len)
 {
-    SV *sv;
-    new_SV(sv);
-    sv_upgrade(sv, SVt_PV);
+    SV *sv = newSV_type(SVt_PV);
     sv_setpvn_fresh(sv,buffer,len);
     return sv;
 }
@@ -9830,10 +9515,8 @@ Perl_newSVhek(pTHX_ const HEK *const hek)
         {
             /* Inline most of newSVpvn_share(), because share_hek_hek() is far
                more efficient than sharepvn().  */
-            SV *sv;
+            SV *sv = newSV_type(SVt_PV);
 
-            new_SV(sv);
-            sv_upgrade(sv, SVt_PV);
             SvPV_set(sv, (char *)HEK_KEY(share_hek_hek(hek)));
             SvCUR_set(sv, HEK_LEN(hek));
             SvLEN_set(sv, 0);
@@ -9878,10 +9561,9 @@ Perl_newSVpvn_share(pTHX_ const char *src, I32 len, U32 hash)
     }
     if (!hash)
         PERL_HASH(hash, src, len);
-    new_SV(sv);
+    sv = newSV_type(SVt_PV);
     /* The logic for this is inlined in S_mro_get_linear_isa_dfs(), so if it
        changes here, update it there too.  */
-    sv_upgrade(sv, SVt_PV);
     SvPV_set(sv, sharepvn(src, is_utf8?-len:len, hash));
     SvCUR_set(sv, len);
     SvLEN_set(sv, 0);
@@ -10070,27 +9752,6 @@ Perl_newSVuv(pTHX_ const UV u)
     return sv;
 }
 
-/*
-=for apidoc newSV_type
-
-Creates a new SV, of the type specified.  The reference count for the new SV
-is set to 1.
-
-=cut
-*/
-
-SV *
-Perl_newSV_type(pTHX_ const svtype type)
-{
-    SV *sv;
-
-    new_SV(sv);
-    ASSUME(SvTYPE(sv) == SVt_FIRST);
-    if(type != SVt_FIRST)
-        sv_upgrade(sv, type);
-    return sv;
-}
-
 /*
 =for apidoc newRV_noinc
 
@@ -16651,7 +16312,7 @@ Perl_varname(pTHX_ const GV *const gv, const char gvtype, PADOFFSET targ,
     }
 
     if (subscript_type == FUV_SUBSCRIPT_HASH) {
-        SV * const sv = newSV(0);
+        SV * const sv = newSV_type(SVt_NULL);
         STRLEN len;
         const char * const pv = SvPV_nomg_const((SV*)keyname, len);
 
diff --git a/sv.h b/sv.h
index b426354d85c7..a16e25407b7c 100644
--- a/sv.h
+++ b/sv.h
@@ -176,6 +176,7 @@ typedef enum {
 /* The array of arena roots for SV bodies is indexed by SvTYPE. SVt_NULL doesn't
  * use a body, so that arena root is re-used for HEs. SVt_IV also doesn't, so
  * that arena root is used for HVs with struct xpvhv_aux. */
+
 #if defined(PERL_IN_HV_C) || defined(PERL_IN_XS_APITEST)
 #  define HE_ARENA_ROOT_IX      SVt_NULL
 #endif
@@ -2581,7 +2582,6 @@ Evaluates C<sv> more than once.  Sets C<len> to 0 if C<SvOOK(sv)> is false.
 /* The following two macros compute the necessary offsets for the above
  * trick and store them in SvANY for SvIV() (and friends) to use. */
 
-#ifdef PERL_CORE
 #  define SET_SVANY_FOR_BODYLESS_IV(sv) \
         SvANY(sv) =   (XPVIV*)((char*)&(sv->sv_u.svu_iv) \
                     - STRUCT_OFFSET(XPVIV, xiv_iv))
@@ -2589,7 +2589,6 @@ Evaluates C<sv> more than once.  Sets C<len> to 0 if C<SvOOK(sv)> is false.
 #  define SET_SVANY_FOR_BODYLESS_NV(sv) \
         SvANY(sv) =   (XPVNV*)((char*)&(sv->sv_u.svu_nv) \
                     - STRUCT_OFFSET(XPVNV, xnv_u.xnv_nv))
-#endif
 
 /*
  * ex: set ts=8 sts=4 sw=4 et:
diff --git a/sv_inline.h b/sv_inline.h
new file mode 100644
index 000000000000..7288797d4181
--- /dev/null
+++ b/sv_inline.h
@@ -0,0 +1,532 @@
+/*    sv_inline.h
+ *
+ *    Copyright (C) 2022 by Larry Wall and others
+ *
+ *    You may distribute under the terms of either the GNU General Public
+ *    License or the Artistic License, as specified in the README file.
+ *
+ */
+
+/* This file contains the newSV_type and newSV_type_mortal functions, as well as
+ * the various struct and macro definitions they require. In the main, these
+ * definitions were moved from sv.c, where many of them continue to also be used.
+ * (In Perl_more_bodies, Perl_sv_upgrade and Perl_sv_clear, for example.) Code
+ * comments associated with definitions and functions were also copied across
+ * verbatim.
+ *
+ * The rationale for having these as inline functions, rather than in sv.c, is
+ * that the target type is very often known at compile time, and therefore
+ * optimum code can be emitted by the compiler, rather than having all calls
+ * traverse the many branches of Perl_sv_upgrade at runtime.
+ */
+
+/* This definition came from perl.h*/
+
+/* The old value was hard coded at 1008. (4096-16) seems to be a bit faster,
+   at least on FreeBSD.  YMMV, so experiment.  */
+#ifndef PERL_ARENA_SIZE
+#define PERL_ARENA_SIZE 4080
+#endif
+
+/* All other pre-existing definitions and functions that were moved into this
+ * file originally came from sv.c. */
+
+#ifdef PERL_POISON
+#  define SvARENA_CHAIN(sv)     ((sv)->sv_u.svu_rv)
+#  define SvARENA_CHAIN_SET(sv,val)     (sv)->sv_u.svu_rv = MUTABLE_SV((val))
+/* Whilst I'd love to do this, it seems that things like to check on
+   unreferenced scalars
+#  define POISON_SV_HEAD(sv)    PoisonNew(sv, 1, struct STRUCT_SV)
+*/
+#  define POISON_SV_HEAD(sv)    PoisonNew(&SvANY(sv), 1, void *), \
+                                PoisonNew(&SvREFCNT(sv), 1, U32)
+#else
+#  define SvARENA_CHAIN(sv)     SvANY(sv)
+#  define SvARENA_CHAIN_SET(sv,val)     SvANY(sv) = (void *)(val)
+#  define POISON_SV_HEAD(sv)
+#endif
+
+#ifdef PERL_MEM_LOG
+#  define MEM_LOG_NEW_SV(sv, file, line, func)  \
+            Perl_mem_log_new_sv(sv, file, line, func)
+#  define MEM_LOG_DEL_SV(sv, file, line, func)  \
+            Perl_mem_log_del_sv(sv, file, line, func)
+#else
+#  define MEM_LOG_NEW_SV(sv, file, line, func)  NOOP
+#  define MEM_LOG_DEL_SV(sv, file, line, func)  NOOP
+#endif
+
+#define uproot_SV(p) \
+    STMT_START {                                        \
+        (p) = PL_sv_root;                               \
+        PL_sv_root = MUTABLE_SV(SvARENA_CHAIN(p));              \
+        ++PL_sv_count;                                  \
+    } STMT_END
+
+/* Perl_more_sv lives in sv.c, we don't want to inline it.
+ * but the function declaration seems to be needed. */
+SV* Perl_more_sv(pTHX);
+
+/* new_SV(): return a new, empty SV head */
+
+#ifdef DEBUG_LEAKING_SCALARS
+/* provide a real function for a debugger to play with */
+STATIC SV*
+S_new_SV(pTHX_ const char *file, int line, const char *func)
+{
+    SV* sv;
+
+    if (PL_sv_root)
+        uproot_SV(sv);
+    else
+        sv = Perl_more_sv(aTHX);
+    SvANY(sv) = 0;
+    SvREFCNT(sv) = 1;
+    SvFLAGS(sv) = 0;
+    sv->sv_debug_optype = PL_op ? PL_op->op_type : 0;
+    sv->sv_debug_line = (U16) (PL_parser && PL_parser->copline != NOLINE
+                ? PL_parser->copline
+                :  PL_curcop
+                    ? CopLINE(PL_curcop)
+                    : 0
+            );
+    sv->sv_debug_inpad = 0;
+    sv->sv_debug_parent = NULL;
+    sv->sv_debug_file = PL_curcop ? savesharedpv(CopFILE(PL_curcop)): NULL;
+
+    sv->sv_debug_serial = PL_sv_serial++;
+
+    MEM_LOG_NEW_SV(sv, file, line, func);
+    DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%" UVxf ": (%05ld) new_SV (from %s:%d [%s])\n",
+            PTR2UV(sv), (long)sv->sv_debug_serial, file, line, func));
+
+    return sv;
+}
+#  define new_SV(p) (p)=S_new_SV(aTHX_ __FILE__, __LINE__, FUNCTION__)
+
+#else
+#  define new_SV(p) \
+    STMT_START {                                       \
+        if (PL_sv_root)                                        \
+            uproot_SV(p);                              \
+        else                                           \
+            (p) = Perl_more_sv(aTHX);                     \
+        SvANY(p) = 0;                                  \
+        SvREFCNT(p) = 1;                               \
+        SvFLAGS(p) = 0;                                        \
+        MEM_LOG_NEW_SV(p, __FILE__, __LINE__, FUNCTION__);  \
+    } STMT_END
+#endif
+
+
+typedef struct xpvhv_with_aux XPVHV_WITH_AUX;
+
+struct body_details {
+    U8 body_size;      /* Size to allocate  */
+    U8 copy;           /* Size of structure to copy (may be shorter)  */
+    U8 offset;         /* Size of unalloced ghost fields to first alloced field*/
+    PERL_BITFIELD8 type : 4;        /* We have space for a sanity check. */
+    PERL_BITFIELD8 cant_upgrade : 1;/* Cannot upgrade this type */
+    PERL_BITFIELD8 zero_nv : 1;     /* zero the NV when upgrading from this */
+    PERL_BITFIELD8 arena : 1;       /* Allocated from an arena */
+    U32 arena_size;                 /* Size of arena to allocate */
+};
+
+#define ALIGNED_TYPE_NAME(name) name##_aligned
+#define ALIGNED_TYPE(name)             \
+    typedef union {    \
+        name align_me;                         \
+        NV nv;                         \
+        IV iv;                         \
+    } ALIGNED_TYPE_NAME(name)
+
+ALIGNED_TYPE(regexp);
+ALIGNED_TYPE(XPVGV);
+ALIGNED_TYPE(XPVLV);
+ALIGNED_TYPE(XPVAV);
+ALIGNED_TYPE(XPVHV);
+ALIGNED_TYPE(XPVHV_WITH_AUX);
+ALIGNED_TYPE(XPVCV);
+ALIGNED_TYPE(XPVFM);
+ALIGNED_TYPE(XPVIO);
+
+#define HADNV FALSE
+#define NONV TRUE
+
+
+#ifdef PURIFY
+/* With -DPURFIY we allocate everything directly, and don't use arenas.
+   This seems a rather elegant way to simplify some of the code below.  */
+#define HASARENA FALSE
+#else
+#define HASARENA TRUE
+#endif
+#define NOARENA FALSE
+
+/* Size the arenas to exactly fit a given number of bodies.  A count
+   of 0 fits the max number bodies into a PERL_ARENA_SIZE.block,
+   simplifying the default.  If count > 0, the arena is sized to fit
+   only that many bodies, allowing arenas to be used for large, rare
+   bodies (XPVFM, XPVIO) without undue waste.  The arena size is
+   limited by PERL_ARENA_SIZE, so we can safely oversize the
+   declarations.
+ */
+#define FIT_ARENA0(body_size)                          \
+    ((size_t)(PERL_ARENA_SIZE / body_size) * body_size)
+#define FIT_ARENAn(count,body_size)                    \
+    ( count * body_size <= PERL_ARENA_SIZE)            \
+    ? count * body_size                                        \
+    : FIT_ARENA0 (body_size)
+#define FIT_ARENA(count,body_size)                     \
+   (U32)(count                                                 \
+    ? FIT_ARENAn (count, body_size)                    \
+    : FIT_ARENA0 (body_size))
+
+/* Calculate the length to copy. Specifically work out the length less any
+   final padding the compiler needed to add.  See the comment in sv_upgrade
+   for why copying the padding proved to be a bug.  */
+
+#define copy_length(type, last_member) \
+        STRUCT_OFFSET(type, last_member) \
+        + sizeof (((type*)SvANY((const SV *)0))->last_member)
+
+static const struct body_details bodies_by_type[] = {
+    /* HEs use this offset for their arena.  */
+    { 0, 0, 0, SVt_NULL, FALSE, NONV, NOARENA, 0 },
+
+    /* IVs are in the head, so the allocation size is 0.  */
+    { 0,
+      sizeof(IV), /* This is used to copy out the IV body.  */
+      STRUCT_OFFSET(XPVIV, xiv_iv), SVt_IV, FALSE, NONV,
+      NOARENA /* IVS don't need an arena  */, 0
+    },
+
+#if NVSIZE <= IVSIZE
+    { 0, sizeof(NV),
+      STRUCT_OFFSET(XPVNV, xnv_u),
+      SVt_NV, FALSE, HADNV, NOARENA, 0 },
+#else
+    { sizeof(NV), sizeof(NV),
+      STRUCT_OFFSET(XPVNV, xnv_u),
+      SVt_NV, FALSE, HADNV, HASARENA, FIT_ARENA(0, sizeof(NV)) },
+#endif
+
+    { sizeof(XPV) - STRUCT_OFFSET(XPV, xpv_cur),
+      copy_length(XPV, xpv_len) - STRUCT_OFFSET(XPV, xpv_cur),
+      + STRUCT_OFFSET(XPV, xpv_cur),
+      SVt_PV, FALSE, NONV, HASARENA,
+      FIT_ARENA(0, sizeof(XPV) - STRUCT_OFFSET(XPV, xpv_cur)) },
+
+    { sizeof(XINVLIST) - STRUCT_OFFSET(XPV, xpv_cur),
+      copy_length(XINVLIST, is_offset) - STRUCT_OFFSET(XPV, xpv_cur),
+      + STRUCT_OFFSET(XPV, xpv_cur),
+      SVt_INVLIST, TRUE, NONV, HASARENA,
+      FIT_ARENA(0, sizeof(XINVLIST) - STRUCT_OFFSET(XPV, xpv_cur)) },
+
+    { sizeof(XPVIV) - STRUCT_OFFSET(XPV, xpv_cur),
+      copy_length(XPVIV, xiv_u) - STRUCT_OFFSET(XPV, xpv_cur),
+      + STRUCT_OFFSET(XPV, xpv_cur),
+      SVt_PVIV, FALSE, NONV, HASARENA,
+      FIT_ARENA(0, sizeof(XPVIV) - STRUCT_OFFSET(XPV, xpv_cur)) },
+
+    { sizeof(XPVNV) - STRUCT_OFFSET(XPV, xpv_cur),
+      copy_length(XPVNV, xnv_u) - STRUCT_OFFSET(XPV, xpv_cur),
+      + STRUCT_OFFSET(XPV, xpv_cur),
+      SVt_PVNV, FALSE, HADNV, HASARENA,
+      FIT_ARENA(0, sizeof(XPVNV) - STRUCT_OFFSET(XPV, xpv_cur)) },
+
+    { sizeof(XPVMG), copy_length(XPVMG, xnv_u), 0, SVt_PVMG, FALSE, HADNV,
+      HASARENA, FIT_ARENA(0, sizeof(XPVMG)) },
+
+    { sizeof(ALIGNED_TYPE_NAME(regexp)),
+      sizeof(regexp),
+      0,
+      SVt_REGEXP, TRUE, NONV, HASARENA,
+      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(regexp)))
+    },
+
+    { sizeof(ALIGNED_TYPE_NAME(XPVGV)), sizeof(XPVGV), 0, SVt_PVGV, TRUE, HADNV,
+      HASARENA, FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVGV))) },
+
+    { sizeof(ALIGNED_TYPE_NAME(XPVLV)), sizeof(XPVLV), 0, SVt_PVLV, TRUE, HADNV,
+      HASARENA, FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVLV))) },
+
+    { sizeof(ALIGNED_TYPE_NAME(XPVAV)),
+      copy_length(XPVAV, xav_alloc),
+      0,
+      SVt_PVAV, TRUE, NONV, HASARENA,
+      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVAV))) },
+
+    { sizeof(ALIGNED_TYPE_NAME(XPVHV)),
+      copy_length(XPVHV, xhv_max),
+      0,
+      SVt_PVHV, TRUE, NONV, HASARENA,
+      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVHV))) },
+
+    { sizeof(ALIGNED_TYPE_NAME(XPVCV)),
+      sizeof(XPVCV),
+      0,
+      SVt_PVCV, TRUE, NONV, HASARENA,
+      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVCV))) },
+
+    { sizeof(ALIGNED_TYPE_NAME(XPVFM)),
+      sizeof(XPVFM),
+      0,
+      SVt_PVFM, TRUE, NONV, NOARENA,
+      FIT_ARENA(20, sizeof(ALIGNED_TYPE_NAME(XPVFM))) },
+
+    { sizeof(ALIGNED_TYPE_NAME(XPVIO)),
+      sizeof(XPVIO),
+      0,
+      SVt_PVIO, TRUE, NONV, HASARENA,
+      FIT_ARENA(24, sizeof(ALIGNED_TYPE_NAME(XPVIO))) },
+};
+
+#define new_body_allocated(sv_type)            \
+    (void *)((char *)S_new_body(aTHX_ sv_type) \
+             - bodies_by_type[sv_type].offset)
+
+#ifdef PURIFY
+#if !(NVSIZE <= IVSIZE)
+#  define new_XNV()    safemalloc(sizeof(XPVNV))
+#endif
+#define new_XPVNV()    safemalloc(sizeof(XPVNV))
+#define new_XPVMG()    safemalloc(sizeof(XPVMG))
+
+#define del_body_by_type(p, type)       safefree(p)
+
+#else /* !PURIFY */
+
+#if !(NVSIZE <= IVSIZE)
+#  define new_XNV()    new_body_allocated(SVt_NV)
+#endif
+#define new_XPVNV()    new_body_allocated(SVt_PVNV)
+#define new_XPVMG()    new_body_allocated(SVt_PVMG)
+
+#define del_body_by_type(p, type)                               \
+    del_body(p + bodies_by_type[(type)].offset,                 \
+             &PL_body_roots[(type)])
+
+#endif /* PURIFY */
+
+/* no arena for you! */
+
+#define new_NOARENA(details) \
+        safemalloc((details)->body_size + (details)->offset)
+#define new_NOARENAZ(details) \
+        safecalloc((details)->body_size + (details)->offset, 1)
+
+#ifndef PURIFY
+
+/* grab a new thing from the arena's free list, allocating more if necessary. */
+#define new_body_from_arena(xpv, root_index, type_meta) \
+    STMT_START { \
+        void ** const r3wt = &PL_body_roots[root_index]; \
+        xpv = (PTR_TBL_ENT_t*) (*((void **)(r3wt))      \
+          ? *((void **)(r3wt)) : Perl_more_bodies(aTHX_ root_index, \
+                                             type_meta.body_size,\
+                                             type_meta.arena_size)); \
+        *(r3wt) = *(void**)(xpv); \
+    } STMT_END
+
+PERL_STATIC_INLINE void *
+S_new_body(pTHX_ const svtype sv_type)
+{
+    void *xpv;
+    new_body_from_arena(xpv, sv_type, bodies_by_type[sv_type]);
+    return xpv;
+}
+
+#endif
+
+static const struct body_details fake_rv =
+    { 0, 0, 0, SVt_IV, FALSE, NONV, NOARENA, 0 };
+
+static const struct body_details fake_hv_with_aux =
+    /* The SVt_IV arena is used for (larger) PVHV bodies.  */
+    { sizeof(ALIGNED_TYPE_NAME(XPVHV_WITH_AUX)),
+      copy_length(XPVHV, xhv_max),
+      0,
+      SVt_PVHV, TRUE, NONV, HASARENA,
+      FIT_ARENA(0, sizeof(ALIGNED_TYPE_NAME(XPVHV_WITH_AUX))) };
+
+/*
+=for apidoc newSV_type
+
+Creates a new SV, of the type specified.  The reference count for the new SV
+is set to 1.
+
+=cut
+*/
+
+PERL_STATIC_INLINE SV *
+Perl_newSV_type(pTHX_ const svtype type)
+{
+    SV *sv;
+    void*      new_body;
+    const struct body_details *type_details;
+
+    new_SV(sv);
+
+    type_details = bodies_by_type + type;
+
+    SvFLAGS(sv) &= ~SVTYPEMASK;
+    SvFLAGS(sv) |= type;
+
+    switch (type) {
+    case SVt_NULL:
+        break;
+    case SVt_IV:
+        SET_SVANY_FOR_BODYLESS_IV(sv);
+        SvIV_set(sv, 0);
+        break;
+    case SVt_NV:
+#if NVSIZE <= IVSIZE
+        SET_SVANY_FOR_BODYLESS_NV(sv);
+#else
+        SvANY(sv) = new_XNV();
+#endif
+        SvNV_set(sv, 0);
+        break;
+    case SVt_PVHV:
+    case SVt_PVAV:
+        assert(type_details->body_size);
+
+#ifndef PURIFY
+        assert(type_details->arena);
+        assert(type_details->arena_size);
+        /* This points to the start of the allocated area.  */
+        new_body = S_new_body(aTHX_ type);
+        /* xpvav and xpvhv have no offset, so no need to adjust new_body */
+        assert(!(type_details->offset));
+#else
+        /* We always allocated the full length item with PURIFY. To do this
+           we fake things so that arena is false for all 16 types..  */
+        new_body = new_NOARENAZ(type_details);
+#endif
+        SvANY(sv) = new_body;
+
+        SvSTASH_set(sv, NULL);
+        SvMAGIC_set(sv, NULL);
+
+        if (type == SVt_PVAV) {
+            AvFILLp(sv) = -1;
+            AvMAX(sv) = -1;
+            AvALLOC(sv) = NULL;
+
+            AvREAL_only(sv);
+        } else {
+            HvTOTALKEYS(sv) = 0;
+            /* start with PERL_HASH_DEFAULT_HvMAX+1 buckets: */
+            HvMAX(sv) = PERL_HASH_DEFAULT_HvMAX;
+
+            assert(!SvOK(sv));
+            SvOK_off(sv);
+#ifndef NODEFAULT_SHAREKEYS
+            HvSHAREKEYS_on(sv);         /* key-sharing on by default */
+#endif
+            /* start with PERL_HASH_DEFAULT_HvMAX+1 buckets: */
+            HvMAX(sv) = PERL_HASH_DEFAULT_HvMAX;
+        }
+
+        sv->sv_u.svu_array = NULL; /* or svu_hash  */
+        break;
+
+    case SVt_PVIV:
+    case SVt_PVIO:
+    case SVt_PVGV:
+    case SVt_PVCV:
+    case SVt_PVLV:
+    case SVt_INVLIST:
+    case SVt_REGEXP:
+    case SVt_PVMG:
+    case SVt_PVNV:
+    case SVt_PV:
+        /* For a type known at compile time, it should be possible for the
+         * compiler to deduce the value of (type_details->arena), resolve
+         * that branch below, and inline the relevant values from
+         * bodies_by_type. Except, at least for gcc, it seems not to do that.
+         * We help it out here with two deviations from sv_upgrade:
+         * (1) Minor rearrangement here, so that PVFM - the only type at this
+         *     point not to be allocated from an array appears last, not PV.
+         * (2) The ASSUME() statement here for everything that isn't PVFM.
+         * Obviously this all only holds as long as it's a true reflection of
+         * the bodies_by_type lookup table. */
+#ifndef PURIFY
+         ASSUME(type_details->arena);
+#endif
+         /* FALLTHROUGH */
+    case SVt_PVFM:
+
+        assert(type_details->body_size);
+        /* We always allocated the full length item with PURIFY. To do this
+           we fake things so that arena is false for all 16 types..  */
+#ifndef PURIFY
+        if(type_details->arena) {
+            /* This points to the start of the allocated area.  */
+            new_body = S_new_body(aTHX_ type);
+            Zero(new_body, type_details->body_size, char);
+            new_body = ((char *)new_body) - type_details->offset;
+        } else
+#endif
+        {
+            new_body = new_NOARENAZ(type_details);
+        }
+        SvANY(sv) = new_body;
+
+        if (UNLIKELY(type == SVt_PVIO)) {
+            IO * const io = MUTABLE_IO(sv);
+            GV *iogv = gv_fetchpvs("IO::File::", GV_ADD, SVt_PVHV);
+
+            SvOBJECT_on(io);
+            /* Clear the stashcache because a new IO could overrule a package
+               name */
+            DEBUG_o(Perl_deb(aTHX_ "sv_upgrade clearing PL_stashcache\n"));
+            hv_clear(PL_stashcache);
+
+            SvSTASH_set(io, MUTABLE_HV(SvREFCNT_inc(GvHV(iogv))));
+            IoPAGE_LEN(sv) = 60;
+        }
+
+        sv->sv_u.svu_rv = NULL;
+        break;
+    default:
+        Perl_croak(aTHX_ "panic: sv_upgrade to unknown type %lu",
+                   (unsigned long)type);
+    }
+
+    return sv;
+}
+
+/*
+=for apidoc newSV_type_mortal
+
+Creates a new mortal SV, of the type specified.  The reference count for the
+new SV is set to 1.
+
+This is equivalent to
+    SV* sv = sv_2mortal(newSV_type(<some type>))
+and
+    SV* sv = sv_newmortal();
+    sv_upgrade(sv, <some_type>)
+but should be more efficient than both of them. (Unless sv_2mortal is inlined
+at some point in the future.)
+
+=cut
+*/
+
+PERL_STATIC_INLINE SV *
+Perl_newSV_type_mortal(pTHX_ const svtype type)
+{
+    SV *sv = newSV_type(type);
+    SSize_t ix = ++PL_tmps_ix;
+    if (UNLIKELY(ix >= PL_tmps_max))
+        ix = Perl_tmps_grow_p(aTHX_ ix);
+    PL_tmps_stack[ix] = (sv);
+    SvTEMP_on(sv);
+    return sv;
+}
+
+/*
+ * ex: set ts=8 sts=4 sw=4 et:
+ */
diff --git a/toke.c b/toke.c
index 18e23e2c8577..c68a1b0ce118 100644
--- a/toke.c
+++ b/toke.c
@@ -2382,7 +2382,7 @@ S_force_strict_version(pTHX_ char *s)
         s++;
 
     if (is_STRICT_VERSION(s,&errstr)) {
-        SV *ver = newSV(0);
+        SV *ver = newSV_type(SVt_NULL);
         s = (char *)scan_version(s, ver, 0);
         version = newSVOP(OP_CONST, 0, ver);
     }
diff --git a/universal.c b/universal.c
index 955850431732..9c7be3199e68 100644
--- a/universal.c
+++ b/universal.c
@@ -304,12 +304,11 @@ Perl_sv_does_sv(pTHX_ SV *sv, SV *namesv, U32 flags)
 
     /* create a PV with value "isa", but with a special address
      * so that perl knows we're really doing "DOES" instead */
-    methodname = newSV_type(SVt_PV);
+    methodname = newSV_type_mortal(SVt_PV);
     SvLEN_set(methodname, 0);
     SvCUR_set(methodname, strlen(PL_isa_DOES));
     SvPVX(methodname) = (char *)PL_isa_DOES; /* discard 'const' qualifier */
     SvPOK_on(methodname);
-    sv_2mortal(methodname);
     call_sv(methodname, G_SCALAR | G_METHOD);
     SPAGAIN;
 
@@ -1126,7 +1125,7 @@ XS(XS_NamedCapture_TIEHASH)
                 flag = SvTRUE(mark[1]) ? RXapif_ALL : RXapif_ONE;
             mark += 2;
         }
-        ST(0) = sv_2mortal(newSV_type(SVt_IV));
+        ST(0) = newSV_type_mortal(SVt_IV);
         sv_setuv(newSVrv(ST(0), package), flag);
     }
     XSRETURN(1);