39 files changed, 309 insertions, 380 deletions
diff --git a/XSUB.h b/XSUB.h
index f84788636f..22805a02b0 100644
--- a/XSUB.h
+++ b/XSUB.h
@@ -40,6 +40,7 @@
 #define XST_mIV(i,v)  (ST(i) = sv_2mortal(newSViv(v))  )
 #define XST_mNV(i,v)  (ST(i) = sv_2mortal(newSVnv(v))  )
 #define XST_mPV(i,v)  (ST(i) = sv_2mortal(newSVpv(v,0)))
+#define XST_mPVN(i,v,n)  (ST(i) = sv_2mortal(newSVpvn(v,n)))
 #define XST_mNO(i)    (ST(i) = &PL_sv_no   )
 #define XST_mYES(i)   (ST(i) = &PL_sv_yes  )
 #define XST_mUNDEF(i) (ST(i) = &PL_sv_undef)
@@ -47,6 +48,7 @@
 #define XSRETURN_IV(v) STMT_START { XST_mIV(0,v);  XSRETURN(1); } STMT_END
 #define XSRETURN_NV(v) STMT_START { XST_mNV(0,v);  XSRETURN(1); } STMT_END
 #define XSRETURN_PV(v) STMT_START { XST_mPV(0,v);  XSRETURN(1); } STMT_END
+#define XSRETURN_PVN(v) STMT_START { XST_mPVN(0,v,n);  XSRETURN(1); } STMT_END
 #define XSRETURN_NO    STMT_START { XST_mNO(0);    XSRETURN(1); } STMT_END
 #define XSRETURN_YES   STMT_START { XST_mYES(0);   XSRETURN(1); } STMT_END
 #define XSRETURN_UNDEF STMT_START { XST_mUNDEF(0); XSRETURN(1); } STMT_END
diff --git a/cv.h b/cv.h
index 9605135ffc..cf5a7509d0 100644
--- a/cv.h
+++ b/cv.h
@@ -75,9 +75,11 @@ struct xpvcv {
 #define CvANON_on(cv)		(CvFLAGS(cv) |= CVf_ANON)
 #define CvANON_off(cv)		(CvFLAGS(cv) &= ~CVf_ANON)
 
+#ifdef PERL_XSUB_OLDSTYLE
 #define CvOLDSTYLE(cv)		(CvFLAGS(cv) & CVf_OLDSTYLE)
 #define CvOLDSTYLE_on(cv)	(CvFLAGS(cv) |= CVf_OLDSTYLE)
 #define CvOLDSTYLE_off(cv)	(CvFLAGS(cv) &= ~CVf_OLDSTYLE)
+#endif
 
 #define CvUNIQUE(cv)		(CvFLAGS(cv) & CVf_UNIQUE)
 #define CvUNIQUE_on(cv)		(CvFLAGS(cv) |= CVf_UNIQUE)
diff --git a/doio.c b/doio.c
index fda993e7e9..c0667ef235 100644
--- a/doio.c
+++ b/doio.c
@@ -1615,12 +1615,6 @@ do_msgrcv(SV **mark, SV **sp)
     msize = SvIVx(*++mark);
     mtype = (long)SvIVx(*++mark);
     flags = SvIVx(*++mark);
-    if (SvTHINKFIRST(mstr)) {
-	if (SvREADONLY(mstr))
-	    croak("Can't msgrcv to readonly var");
-	if (SvROK(mstr))
-	    sv_unref(mstr);
-    }
     SvPV_force(mstr, len);
     mbuf = SvGROW(mstr, sizeof(long)+msize+1);
     
diff --git a/dump.c b/dump.c
index 34d0eb7fd5..cce9830e5d 100644
--- a/dump.c
+++ b/dump.c
@@ -267,7 +267,7 @@ sv_peek(SV *sv)
 	if (!SvPVX(sv))
 	    sv_catpv(t, "(null)");
 	else {
-	    SV *tmp = newSVpv("", 0);
+	    SV *tmp = newSVpvn("", 0);
 	    sv_catpv(t, "(");
 	    if (SvOOK(sv))
 		sv_catpvf(t, "[%s]", pv_display(tmp, SvPVX(sv)-SvIVX(sv), SvIVX(sv), 0, 127));
@@ -318,7 +318,7 @@ do_pmop_dump(I32 level, PerlIO *file, PMOP *pm)
 	op_dump(pm->op_pmreplroot);
     }
     if (pm->op_pmflags || (pm->op_pmregexp && pm->op_pmregexp->check_substr)) {
-	SV *tmpsv = newSVpv("", 0);
+	SV *tmpsv = newSVpvn("", 0);
 	if (pm->op_pmdynflags & PMdf_USED)
 	    sv_catpv(tmpsv, ",USED");
 	if (pm->op_pmdynflags & PMdf_TAINTED)
@@ -388,7 +388,7 @@ do_op_dump(I32 level, PerlIO *file, OP *o)
     dump_indent(level, file, "ADDR = 0x%lx => 0x%lx\n",o, o->op_next);
 #endif
     if (o->op_flags) {
-	SV *tmpsv = newSVpv("", 0);
+	SV *tmpsv = newSVpvn("", 0);
 	switch (o->op_flags & OPf_WANT) {
 	case OPf_WANT_VOID:
 	    sv_catpv(tmpsv, ",VOID");
@@ -419,7 +419,7 @@ do_op_dump(I32 level, PerlIO *file, OP *o)
 	SvREFCNT_dec(tmpsv);
     }
     if (o->op_private) {
-	SV *tmpsv = newSVpv("", 0);
+	SV *tmpsv = newSVpvn("", 0);
 	if (o->op_type == OP_AASSIGN) {
 	    if (o->op_private & OPpASSIGN_COMMON)
 		sv_catpv(tmpsv, ",COMMON");
@@ -671,7 +671,7 @@ do_magic_dump(I32 level, PerlIO *file, MAGIC *mg, I32 nest, I32 maxnest, bool du
         if (mg->mg_ptr) {
 	    dump_indent(level, file, "    MG_PTR = 0x%lx", (long)mg->mg_ptr);
 	    if (mg->mg_len >= 0) {
-		SV *sv = newSVpv("", 0);
+		SV *sv = newSVpvn("", 0);
                 PerlIO_printf(file, " %s", pv_display(sv, mg->mg_ptr, mg->mg_len, 0, pvlim));
 		SvREFCNT_dec(sv);
             }
diff --git a/embed.h b/embed.h
index d21cc3b832..fed0530627 100644
--- a/embed.h
+++ b/embed.h
@@ -868,6 +868,7 @@
 #define sv_derived_from		Perl_sv_derived_from
 #define sv_dump			Perl_sv_dump
 #define sv_eq			Perl_sv_eq
+#define sv_force_normal		Perl_sv_force_normal
 #define sv_free			Perl_sv_free
 #define sv_free_arenas		Perl_sv_free_arenas
 #define sv_gets			Perl_sv_gets
@@ -930,6 +931,7 @@
 #define swash_init		Perl_swash_init
 #define taint_env		Perl_taint_env
 #define taint_proper		Perl_taint_proper
+#define tmps_grow		Perl_tmps_grow
 #define to_uni_lower		Perl_to_uni_lower
 #define to_uni_lower_lc		Perl_to_uni_lower_lc
 #define to_uni_title		Perl_to_uni_title
@@ -2013,7 +2015,6 @@
 #define sv_catpvn_mg		CPerlObj::Perl_sv_catpvn_mg
 #define sv_catsv		CPerlObj::Perl_sv_catsv
 #define sv_catsv_mg		CPerlObj::Perl_sv_catsv_mg
-#define sv_check_thinkfirst	CPerlObj::Perl_sv_check_thinkfirst
 #define sv_chop			CPerlObj::Perl_sv_chop
 #define sv_clean_all		CPerlObj::Perl_sv_clean_all
 #define sv_clean_objs		CPerlObj::Perl_sv_clean_objs
@@ -2026,6 +2027,7 @@
 #define sv_derived_from		CPerlObj::Perl_sv_derived_from
 #define sv_dump			CPerlObj::Perl_sv_dump
 #define sv_eq			CPerlObj::Perl_sv_eq
+#define sv_force_normal		CPerlObj::Perl_sv_force_normal
 #define sv_free			CPerlObj::Perl_sv_free
 #define sv_free_arenas		CPerlObj::Perl_sv_free_arenas
 #define sv_gets			CPerlObj::Perl_sv_gets
@@ -2040,7 +2042,6 @@
 #define sv_len_utf8		CPerlObj::Perl_sv_len_utf8
 #define sv_magic		CPerlObj::Perl_sv_magic
 #define sv_mortalcopy		CPerlObj::Perl_sv_mortalcopy
-#define sv_mortalgrow		CPerlObj::Perl_sv_mortalgrow
 #define sv_ncmp			CPerlObj::Perl_sv_ncmp
 #define sv_newmortal		CPerlObj::Perl_sv_newmortal
 #define sv_newref		CPerlObj::Perl_sv_newref
@@ -2092,6 +2093,7 @@
 #define swash_init		CPerlObj::Perl_swash_init
 #define taint_env		CPerlObj::Perl_taint_env
 #define taint_proper		CPerlObj::Perl_taint_proper
+#define tmps_grow		CPerlObj::Perl_tmps_grow
 #define to_uni_lower		CPerlObj::Perl_to_uni_lower
 #define to_uni_lower_lc		CPerlObj::Perl_to_uni_lower_lc
 #define to_uni_title		CPerlObj::Perl_to_uni_title
diff --git a/embed.pl b/embed.pl
index 89e15066ae..248792ccd1 100755
--- a/embed.pl
+++ b/embed.pl
@@ -225,9 +225,7 @@ my @staticfuncs = qw(
     del_xnv
     del_xpv
     del_xrv
-    sv_mortalgrow
     sv_unglob
-    sv_check_thinkfirst
     avhv_index_sv
     do_report_used
     do_clean_objs
diff --git a/ext/B/B.xs b/ext/B/B.xs
index a2ee8141c3..ccac053da9 100644
--- a/ext/B/B.xs
+++ b/ext/B/B.xs
@@ -221,7 +221,7 @@ make_mg_object(SV *arg, MAGIC *mg)
 static SV *
 cstring(SV *sv)
 {
-    SV *sstr = newSVpv("", 0);
+    SV *sstr = newSVpvn("", 0);
     STRLEN len;
     char *s;
 
@@ -274,7 +274,7 @@ cstring(SV *sv)
 static SV *
 cchar(SV *sv)
 {
-    SV *sstr = newSVpv("'", 0);
+    SV *sstr = newSVpvn("'", 1);
     STRLEN n_a;
     char *s = SvPV(sv, n_a);
 
@@ -600,7 +600,7 @@ threadsv_names()
 
 	EXTEND(sp, len);
 	for (i = 0; i < len; i++)
-	    PUSHs(sv_2mortal(newSVpv(&PL_threadsv_names[i], 1)));
+	    PUSHs(sv_2mortal(newSVpvn(&PL_threadsv_names[i], 1)));
 #endif
 
 
@@ -879,10 +879,10 @@ packiv(sv)
 	     */
 	    wp[0] = htonl(((U32)iv) >> (sizeof(IV)*4));
 	    wp[1] = htonl(iv & 0xffffffff);
-	    ST(0) = sv_2mortal(newSVpv((char *)wp, 8));
+	    ST(0) = sv_2mortal(newSVpvn((char *)wp, 8));
 	} else {
 	    U32 w = htonl((U32)SvIVX(sv));
-	    ST(0) = sv_2mortal(newSVpv((char *)&w, 4));
+	    ST(0) = sv_2mortal(newSVpvn((char *)&w, 4));
 	}
 
 MODULE = B	PACKAGE = B::NV		PREFIX = Sv
@@ -1013,7 +1013,7 @@ BmTABLE(sv)
     CODE:
 	str = SvPV(sv, len);
 	/* Boyer-Moore table is just after string and its safety-margin \0 */
-	ST(0) = sv_2mortal(newSVpv(str + len + 1, 256));
+	ST(0) = sv_2mortal(newSVpvn(str + len + 1, 256));
 
 MODULE = B	PACKAGE = B::GV		PREFIX = Gv
 
@@ -1021,7 +1021,7 @@ void
 GvNAME(gv)
 	B::GV	gv
     CODE:
-	ST(0) = sv_2mortal(newSVpv(GvNAME(gv), GvNAMELEN(gv)));
+	ST(0) = sv_2mortal(newSVpvn(GvNAME(gv), GvNAMELEN(gv)));
 
 B::HV
 GvSTASH(gv)
@@ -1257,7 +1257,7 @@ HvARRAY(hv)
 	    (void)hv_iterinit(hv);
 	    EXTEND(sp, HvKEYS(hv) * 2);
 	    while (sv = hv_iternextsv(hv, &key, &len)) {
-		PUSHs(newSVpv(key, len));
+		PUSHs(newSVpvn(key, len));
 		PUSHs(make_sv_object(sv_newmortal(), sv));
 	    }
 	}
diff --git a/ext/B/defsubs.h.PL b/ext/B/defsubs.h.PL
index c24eb94170..94ca5b3538 100644
--- a/ext/B/defsubs.h.PL
+++ b/ext/B/defsubs.h.PL
@@ -29,6 +29,6 @@ sub doconst
  my $l = length($sym);
  print OUT <<"END";
  newCONSTSUB(stash,"$sym",newSViv($sym)); 
- av_push(export_ok,newSVpv("$sym",$l));
+ av_push(export_ok,newSVpvn("$sym",$l));
 END
 }
diff --git a/ext/DB_File/DB_File.xs b/ext/DB_File/DB_File.xs
index 94113eb4e2..3f6c094395 100644
--- a/ext/DB_File/DB_File.xs
+++ b/ext/DB_File/DB_File.xs
@@ -382,7 +382,7 @@ const DBT * key2 ;
     
     data1 = key1->data ;
     data2 = key2->data ;
-
+#if 0
     /* As newSVpv will assume that the data pointer is a null terminated C 
        string if the size parameter is 0, make sure that data points to an 
        empty string if the length is 0
@@ -391,14 +391,14 @@ const DBT * key2 ;
         data1 = "" ; 
     if (key2->size == 0)
         data2 = "" ;
-
+#endif
     ENTER ;
     SAVETMPS;
 
     PUSHMARK(SP) ;
     EXTEND(SP,2) ;
-    PUSHs(sv_2mortal(newSVpv(data1,key1->size)));
-    PUSHs(sv_2mortal(newSVpv(data2,key2->size)));
+    PUSHs(sv_2mortal(newSVpvn(data1,key1->size)));
+    PUSHs(sv_2mortal(newSVpvn(data2,key2->size)));
     PUTBACK ;
 
     count = perl_call_sv(CurrentDB->compare, G_SCALAR); 
@@ -429,7 +429,7 @@ const DBT * key2 ;
     
     data1 = key1->data ;
     data2 = key2->data ;
-
+#if 0
     /* As newSVpv will assume that the data pointer is a null terminated C 
        string if the size parameter is 0, make sure that data points to an 
        empty string if the length is 0
@@ -438,14 +438,14 @@ const DBT * key2 ;
         data1 = "" ;
     if (key2->size == 0)
         data2 = "" ;
-
+#endif
     ENTER ;
     SAVETMPS;
 
     PUSHMARK(SP) ;
     EXTEND(SP,2) ;
-    PUSHs(sv_2mortal(newSVpv(data1,key1->size)));
-    PUSHs(sv_2mortal(newSVpv(data2,key2->size)));
+    PUSHs(sv_2mortal(newSVpvn(data1,key1->size)));
+    PUSHs(sv_2mortal(newSVpvn(data2,key2->size)));
     PUTBACK ;
 
     count = perl_call_sv(CurrentDB->prefix, G_SCALAR); 
@@ -472,17 +472,17 @@ size_t size ;
     dSP ;
     int retval ;
     int count ;
-
+#if 0
     if (size == 0)
         data = "" ;
-
+#endif
      /* DGH - Next two lines added to fix corrupted stack problem */
     ENTER ;
     SAVETMPS;
 
     PUSHMARK(SP) ;
 
-    XPUSHs(sv_2mortal(newSVpv((char*)data,size)));
+    XPUSHs(sv_2mortal(newSVpvn((char*)data,size)));
     PUTBACK ;
 
     count = perl_call_sv(CurrentDB->hash, G_SCALAR); 
diff --git a/ext/DynaLoader/dl_vms.xs b/ext/DynaLoader/dl_vms.xs
index 08fd2f3f46..2a9ba3cb0f 100644
--- a/ext/DynaLoader/dl_vms.xs
+++ b/ext/DynaLoader/dl_vms.xs
@@ -216,7 +216,7 @@ dl_expandspec(filespec)
           ST(0) = &PL_sv_undef;
         }
         else {
-          ST(0) = sv_2mortal(newSVpv(dlnam.nam$l_rsa,dlnam.nam$b_rsl));
+          ST(0) = sv_2mortal(newSVpvn(dlnam.nam$l_rsa,dlnam.nam$b_rsl));
           DLDEBUG(1,PerlIO_printf(PerlIO_stderr(), "\tresult = \\%.*s\\\n",
                             dlnam.nam$b_rsl,dlnam.nam$l_rsa));
         }
diff --git a/ext/IPC/SysV/SysV.xs b/ext/IPC/SysV/SysV.xs
index 0aaf0527a1..dbed151a71 100644
--- a/ext/IPC/SysV/SysV.xs
+++ b/ext/IPC/SysV/SysV.xs
@@ -69,7 +69,7 @@ PPCODE:
     sv = *av_fetch(list,1,TRUE); ds.msg_perm.gid = SvIV(sv);
     sv = *av_fetch(list,4,TRUE); ds.msg_perm.mode = SvIV(sv);
     sv = *av_fetch(list,6,TRUE); ds.msg_qbytes = SvIV(sv);
-    ST(0) = sv_2mortal(newSVpv((char *)&ds,sizeof(ds)));
+    ST(0) = sv_2mortal(newSVpvn((char *)&ds,sizeof(ds)));
     XSRETURN(1);
 #else
     croak("System V msgxxx is not implemented on this machine");
@@ -185,7 +185,7 @@ PPCODE:
 	ds.sem_otime = SvIV(*sv_ptr);
     if((sv_ptr = av_fetch(list,7,TRUE)) && (sv = *sv_ptr))
 	ds.sem_nsems = SvIV(*sv_ptr);
-    ST(0) = sv_2mortal(newSVpv((char *)&ds,sizeof(ds)));
+    ST(0) = sv_2mortal(newSVpvn((char *)&ds,sizeof(ds)));
     XSRETURN(1);
 #else
     croak("System V semxxx is not implemented on this machine");
diff --git a/ext/Opcode/Opcode.xs b/ext/Opcode/Opcode.xs
index e93b90046a..648ee91330 100644
--- a/ext/Opcode/Opcode.xs
+++ b/ext/Opcode/Opcode.xs
@@ -388,7 +388,7 @@ PPCODE:
     char **op_desc = get_op_descs(); 
     /* copy args to a scratch area since we may push output values onto	*/
     /* the stack faster than we read values off it if masks are used.	*/
-    args = (SV**)SvPVX(sv_2mortal(newSVpv((char*)&ST(0), items*sizeof(SV*))));
+    args = (SV**)SvPVX(sv_2mortal(newSVpvn((char*)&ST(0), items*sizeof(SV*))));
     for (i = 0; i < items; i++) {
 	char *opname = SvPV(args[i], len);
 	SV *bitspec = get_op_bitspec(opname, len, 1);
diff --git a/ext/POSIX/POSIX.xs b/ext/POSIX/POSIX.xs
index bd5cb7202d..59e937ecf4 100644
--- a/ext/POSIX/POSIX.xs
+++ b/ext/POSIX/POSIX.xs
@@ -3662,10 +3662,10 @@ strftime(fmt, sec, min, hour, mday, mon, year, wday = -1, yday = -1, isdst = -1)
 		    Renew(buf, bufsize, char);
 		}
 		if ( buf ) {
-		    ST(0) = sv_2mortal(newSVpv(buf, buflen));
+		    ST(0) = sv_2mortal(newSVpvn(buf, buflen));
 		    Safefree(buf);
 		} else {
-		    ST(0) = sv_2mortal(newSVpv(tmpbuf, len));
+		    ST(0) = sv_2mortal(newSVpvn(tmpbuf, len));
 		}
 	    }
 	}
@@ -3677,8 +3677,8 @@ void
 tzname()
     PPCODE:
 	EXTEND(SP,2);
-	PUSHs(sv_2mortal(newSVpv(tzname[0],strlen(tzname[0]))));
-	PUSHs(sv_2mortal(newSVpv(tzname[1],strlen(tzname[1]))));
+	PUSHs(sv_2mortal(newSVpvn(tzname[0],strlen(tzname[0]))));
+	PUSHs(sv_2mortal(newSVpvn(tzname[1],strlen(tzname[1]))));
 
 SysRet
 access(filename, mode)
diff --git a/ext/Socket/Socket.xs b/ext/Socket/Socket.xs
index 30499483d0..4a8d8765c9 100644
--- a/ext/Socket/Socket.xs
+++ b/ext/Socket/Socket.xs
@@ -879,7 +879,7 @@ inet_ntoa(ip_address_sv)
 	Copy( ip_address, &addr, sizeof addr, char );
 	addr_str = inet_ntoa(addr);
 
-	ST(0) = sv_2mortal(newSVpv(addr_str, strlen(addr_str)));
+	ST(0) = sv_2mortal(newSVpvn(addr_str, strlen(addr_str)));
 	}
 
 void
@@ -896,7 +896,7 @@ pack_sockaddr_un(pathname)
 	if (len > sizeof(sun_ad.sun_path))
 	    len = sizeof(sun_ad.sun_path);
 	Copy( pathname, sun_ad.sun_path, len, char );
-	ST(0) = sv_2mortal(newSVpv((char *)&sun_ad, sizeof sun_ad));
+	ST(0) = sv_2mortal(newSVpvn((char *)&sun_ad, sizeof sun_ad));
 #else
 	ST(0) = (SV *) not_here("pack_sockaddr_un");
 #endif
@@ -931,7 +931,7 @@ unpack_sockaddr_un(sun_sv)
 	e = addr.sun_path;
 	while (*e && e < addr.sun_path + sizeof addr.sun_path)
 	    ++e;
-	ST(0) = sv_2mortal(newSVpv(addr.sun_path, e - addr.sun_path));
+	ST(0) = sv_2mortal(newSVpvn(addr.sun_path, e - addr.sun_path));
 #else
 	ST(0) = (SV *) not_here("unpack_sockaddr_un");
 #endif
@@ -950,7 +950,7 @@ pack_sockaddr_in(port,ip_address)
 	sin.sin_port = htons(port);
 	Copy( ip_address, &sin.sin_addr, sizeof sin.sin_addr, char );
 
-	ST(0) = sv_2mortal(newSVpv((char *)&sin, sizeof sin));
+	ST(0) = sv_2mortal(newSVpvn((char *)&sin, sizeof sin));
 	}
 
 void
@@ -980,7 +980,7 @@ unpack_sockaddr_in(sin_sv)
 
 	EXTEND(SP, 2);
 	PUSHs(sv_2mortal(newSViv((IV) port)));
-	PUSHs(sv_2mortal(newSVpv((char *)&ip_address,sizeof ip_address)));
+	PUSHs(sv_2mortal(newSVpvn((char *)&ip_address,sizeof ip_address)));
 	}
 
 void
@@ -989,7 +989,7 @@ INADDR_ANY()
 	{
 	struct in_addr	ip_address;
 	ip_address.s_addr = htonl(INADDR_ANY);
-	ST(0) = sv_2mortal(newSVpv((char *)&ip_address,sizeof ip_address ));
+	ST(0) = sv_2mortal(newSVpvn((char *)&ip_address,sizeof ip_address ));
 	}
 
 void
@@ -998,7 +998,7 @@ INADDR_LOOPBACK()
 	{
 	struct in_addr	ip_address;
 	ip_address.s_addr = htonl(INADDR_LOOPBACK);
-	ST(0) = sv_2mortal(newSVpv((char *)&ip_address,sizeof ip_address));
+	ST(0) = sv_2mortal(newSVpvn((char *)&ip_address,sizeof ip_address));
 	}
 
 void
@@ -1007,7 +1007,7 @@ INADDR_NONE()
 	{
 	struct in_addr	ip_address;
 	ip_address.s_addr = htonl(INADDR_NONE);
-	ST(0) = sv_2mortal(newSVpv((char *)&ip_address,sizeof ip_address));
+	ST(0) = sv_2mortal(newSVpvn((char *)&ip_address,sizeof ip_address));
 	}
 
 void
@@ -1016,5 +1016,5 @@ INADDR_BROADCAST()
 	{
 	struct in_addr	ip_address;
 	ip_address.s_addr = htonl(INADDR_BROADCAST);
-	ST(0) = sv_2mortal(newSVpv((char *)&ip_address,sizeof ip_address));
+	ST(0) = sv_2mortal(newSVpvn((char *)&ip_address,sizeof ip_address));
 	}
diff --git a/ext/attrs/attrs.xs b/ext/attrs/attrs.xs
index 7f7970d207..4e0afb08ed 100644
--- a/ext/attrs/attrs.xs
+++ b/ext/attrs/attrs.xs
@@ -55,7 +55,7 @@ SV *	sub
 	if (!sub)
 	    croak("invalid subroutine reference or name");
 	if (CvFLAGS(sub) & CVf_METHOD)
-	    XPUSHs(sv_2mortal(newSVpv("method", 0)));
+	    XPUSHs(sv_2mortal(newSVpvn("method", 6)));
 	if (CvFLAGS(sub) & CVf_LOCKED)
-	    XPUSHs(sv_2mortal(newSVpv("locked", 0)));
+	    XPUSHs(sv_2mortal(newSVpvn("locked", 6)));
 
diff --git a/global.sym b/global.sym
index 89199578f6..e7d1e365e4 100644
--- a/global.sym
+++ b/global.sym
@@ -515,6 +515,7 @@ sv_dec
 sv_derived_from
 sv_dump
 sv_eq
+sv_force_normal
 sv_free
 sv_free_arenas
 sv_gets
@@ -577,6 +578,7 @@ swash_fetch
 swash_init
 taint_env
 taint_proper
+tmps_grow
 to_uni_lower
 to_uni_lower_lc
 to_uni_title
diff --git a/gv.c b/gv.c
index 9dc883e513..b2941c3a1f 100644
--- a/gv.c
+++ b/gv.c
@@ -635,15 +635,15 @@ gv_fetchpv(const char *nambeg, I32 add, I32 sv_type)
 		&& AvFILLp(av) == -1)
 	    {
 		char *pname;
-		av_push(av, newSVpv(pname = "NDBM_File",0));
+		av_push(av, newSVpvn(pname = "NDBM_File",9));
 		gv_stashpvn(pname, 9, TRUE);
-		av_push(av, newSVpv(pname = "DB_File",0));
+		av_push(av, newSVpvn(pname = "DB_File",7));
 		gv_stashpvn(pname, 7, TRUE);
-		av_push(av, newSVpv(pname = "GDBM_File",0));
+		av_push(av, newSVpvn(pname = "GDBM_File",9));
 		gv_stashpvn(pname, 9, TRUE);
-		av_push(av, newSVpv(pname = "SDBM_File",0));
+		av_push(av, newSVpvn(pname = "SDBM_File",9));
 		gv_stashpvn(pname, 9, TRUE);
-		av_push(av, newSVpv(pname = "ODBM_File",0));
+		av_push(av, newSVpvn(pname = "ODBM_File",9));
 		gv_stashpvn(pname, 9, TRUE);
 	    }
 	}
diff --git a/hv.c b/hv.c
index 3fd0fd7dac..5a42d2fd8d 100644
--- a/hv.c
+++ b/hv.c
@@ -114,7 +114,7 @@ hv_fetch(HV *hv, const char *key, U32 klen, I32 lval)
 	    U32 i;
 	    for (i = 0; i < klen; ++i)
 		if (isLOWER(key[i])) {
-		    char *nkey = strupr(SvPVX(sv_2mortal(newSVpv(key,klen))));
+		    char *nkey = strupr(SvPVX(sv_2mortal(newSVpvn(key,klen))));
 		    SV **ret = hv_fetch(hv, nkey, klen, 0);
 		    if (!ret && lval)
 			ret = hv_store(hv, key, klen, NEWSV(61,0), 0);
@@ -153,7 +153,7 @@ hv_fetch(HV *hv, const char *key, U32 klen, I32 lval)
       char *gotenv;
 
       if ((gotenv = PerlEnv_getenv(key)) != Nullch) {
-        sv = newSVpv(gotenv,strlen(gotenv));
+        sv = newSVpvn(gotenv,strlen(gotenv));
         SvTAINTED_on(sv);
         return hv_store(hv,key,klen,sv,hash);
       }
@@ -201,7 +201,7 @@ hv_fetch_ent(HV *hv, SV *keysv, I32 lval, register U32 hash)
 	    key = SvPV(keysv, klen);
 	    for (i = 0; i < klen; ++i)
 		if (isLOWER(key[i])) {
-		    SV *nkeysv = sv_2mortal(newSVpv(key,klen));
+		    SV *nkeysv = sv_2mortal(newSVpvn(key,klen));
 		    (void)strupr(SvPVX(nkeysv));
 		    entry = hv_fetch_ent(hv, nkeysv, 0, 0);
 		    if (!entry && lval)
@@ -244,7 +244,7 @@ hv_fetch_ent(HV *hv, SV *keysv, I32 lval, register U32 hash)
       char *gotenv;
 
       if ((gotenv = PerlEnv_getenv(key)) != Nullch) {
-        sv = newSVpv(gotenv,strlen(gotenv));
+        sv = newSVpvn(gotenv,strlen(gotenv));
         SvTAINTED_on(sv);
         return hv_store_ent(hv,keysv,sv,hash);
       }
@@ -298,7 +298,7 @@ hv_store(HV *hv, const char *key, U32 klen, SV *val, register U32 hash)
 		return 0;
 #ifdef ENV_IS_CASELESS
 	    else if (mg_find((SV*)hv,'E')) {
-		SV *sv = sv_2mortal(newSVpv(key,klen));
+		SV *sv = sv_2mortal(newSVpvn(key,klen));
 		key = strupr(SvPVX(sv));
 		hash = 0;
 	    }
@@ -376,7 +376,7 @@ hv_store_ent(HV *hv, SV *keysv, SV *val, register U32 hash)
 #ifdef ENV_IS_CASELESS
 	    else if (mg_find((SV*)hv,'E')) {
 		key = SvPV(keysv, klen);
-		keysv = sv_2mortal(newSVpv(key,klen));
+		keysv = sv_2mortal(newSVpvn(key,klen));
 		(void)strupr(SvPVX(keysv));
 		hash = 0;
 	    }
@@ -456,7 +456,7 @@ hv_delete(HV *hv, const char *key, U32 klen, I32 flags)
 	    }
 #ifdef ENV_IS_CASELESS
 	    else if (mg_find((SV*)hv,'E')) {
-		sv = sv_2mortal(newSVpv(key,klen));
+		sv = sv_2mortal(newSVpvn(key,klen));
 		key = strupr(SvPVX(sv));
 	    }
 #endif
@@ -526,7 +526,7 @@ hv_delete_ent(HV *hv, SV *keysv, I32 flags, U32 hash)
 #ifdef ENV_IS_CASELESS
 	    else if (mg_find((SV*)hv,'E')) {
 		key = SvPV(keysv, klen);
-		keysv = sv_2mortal(newSVpv(key,klen));
+		keysv = sv_2mortal(newSVpvn(key,klen));
 		(void)strupr(SvPVX(keysv));
 		hash = 0; 
 	    }
@@ -590,7 +590,7 @@ hv_exists(HV *hv, const char *key, U32 klen)
 	}
 #ifdef ENV_IS_CASELESS
 	else if (mg_find((SV*)hv,'E')) {
-	    sv = sv_2mortal(newSVpv(key,klen));
+	    sv = sv_2mortal(newSVpvn(key,klen));
 	    key = strupr(SvPVX(sv));
 	}
 #endif
@@ -640,7 +640,7 @@ hv_exists_ent(HV *hv, SV *keysv, U32 hash)
 #ifdef ENV_IS_CASELESS
 	else if (mg_find((SV*)hv,'E')) {
 	    key = SvPV(keysv, klen);
-	    keysv = sv_2mortal(newSVpv(key,klen));
+	    keysv = sv_2mortal(newSVpvn(key,klen));
 	    (void)strupr(SvPVX(keysv));
 	    hash = 0; 
 	}
@@ -1091,7 +1091,7 @@ hv_iterkeysv(register HE *entry)
     if (HeKLEN(entry) == HEf_SVKEY)
 	return sv_mortalcopy(HeKEY_sv(entry));
     else
-	return sv_2mortal(newSVpv((HeKLEN(entry) ? HeKEY(entry) : ""),
+	return sv_2mortal(newSVpvn((HeKLEN(entry) ? HeKEY(entry) : ""),
 				  HeKLEN(entry)));
 }
 
diff --git a/hv.h b/hv.h
index 5f56c1e238..e9772d4440 100644
--- a/hv.h
+++ b/hv.h
@@ -104,7 +104,7 @@ struct xpvhv {
 #define HeSVKEY_force(he)	(HeKEY(he) ?				\
 				 ((HeKLEN(he) == HEf_SVKEY) ?		\
 				  HeKEY_sv(he) :			\
-				  sv_2mortal(newSVpv(HeKEY(he),		\
+				  sv_2mortal(newSVpvn(HeKEY(he),	\
 						     HeKLEN(he)))) :	\
 				 &PL_sv_undef)
 #define HeSVKEY_set(he,sv)	((HeKLEN(he) = HEf_SVKEY), (HeKEY_sv(he) = sv))
diff --git a/jpl/JNI/JNI.xs b/jpl/JNI/JNI.xs
index 080e10f60c..97416db760 100644
--- a/jpl/JNI/JNI.xs
+++ b/jpl/JNI/JNI.xs
@@ -2518,7 +2518,7 @@ GetBooleanArrayElements(array)
 	    }
 	    else {
 		if (RETVAL_len_) {
-		    PUSHs(sv_2mortal(newSVpv((char*)RETVAL,
+		    PUSHs(sv_2mortal(newSVpvn((char*)RETVAL,
 			(STRLEN)RETVAL_len_ * sizeof(jboolean))));
 		}
 		else
@@ -2548,7 +2548,7 @@ GetByteArrayElements(array)
 	    }
 	    else {
 		if (RETVAL_len_) {
-		    PUSHs(sv_2mortal(newSVpv((char*)RETVAL,
+		    PUSHs(sv_2mortal(newSVpvn((char*)RETVAL,
 			(STRLEN)RETVAL_len_ * sizeof(jbyte))));
 		}
 		else
@@ -2578,7 +2578,7 @@ GetCharArrayElements(array)
 	    }
 	    else {
 		if (RETVAL_len_) {
-		    PUSHs(sv_2mortal(newSVpv((char*)RETVAL,
+		    PUSHs(sv_2mortal(newSVpvn((char*)RETVAL,
 			(STRLEN)RETVAL_len_ * sizeof(jchar))));
 		}
 		else
@@ -2608,7 +2608,7 @@ GetShortArrayElements(array)
 	    }
 	    else {
 		if (RETVAL_len_) {
-		    PUSHs(sv_2mortal(newSVpv((char*)RETVAL,
+		    PUSHs(sv_2mortal(newSVpvn((char*)RETVAL,
 			(STRLEN)RETVAL_len_ * sizeof(jshort))));
 		}
 		else
@@ -2638,7 +2638,7 @@ GetIntArrayElements(array)
 	    }
 	    else {
 		if (RETVAL_len_) {
-		    PUSHs(sv_2mortal(newSVpv((char*)RETVAL,
+		    PUSHs(sv_2mortal(newSVpvn((char*)RETVAL,
 			(STRLEN)RETVAL_len_ * sizeof(jint))));
 		}
 		else
@@ -2668,7 +2668,7 @@ GetLongArrayElements(array)
 	    }
 	    else {
 		if (RETVAL_len_) {
-		    PUSHs(sv_2mortal(newSVpv((char*)RETVAL,
+		    PUSHs(sv_2mortal(newSVpvn((char*)RETVAL,
 			(STRLEN)RETVAL_len_ * sizeof(jlong))));
 		}
 		else
@@ -2698,7 +2698,7 @@ GetFloatArrayElements(array)
 	    }
 	    else {
 		if (RETVAL_len_) {
-		    PUSHs(sv_2mortal(newSVpv((char*)RETVAL,
+		    PUSHs(sv_2mortal(newSVpvn((char*)RETVAL,
 			(STRLEN)RETVAL_len_ * sizeof(jfloat))));
 		}
 		else
@@ -2728,7 +2728,7 @@ GetDoubleArrayElements(array)
 	    }
 	    else {
 		if (RETVAL_len_) {
-		    PUSHs(sv_2mortal(newSVpv((char*)RETVAL,
+		    PUSHs(sv_2mortal(newSVpvn((char*)RETVAL,
 			(STRLEN)RETVAL_len_ * sizeof(jdouble))));
 		}
 		else
diff --git a/mg.c b/mg.c
index a9c137bf9e..3584dbc92d 100644
--- a/mg.c
+++ b/mg.c
@@ -1093,7 +1093,7 @@ magic_methcall(SV *sv, MAGIC *mg, char *meth, I32 flags, int n, SV *val)
     if (n > 1) { 
 	if (mg->mg_ptr) {
 	    if (mg->mg_len >= 0)
-		PUSHs(sv_2mortal(newSVpv(mg->mg_ptr, mg->mg_len)));
+		PUSHs(sv_2mortal(newSVpvn(mg->mg_ptr, mg->mg_len)));
 	    else if (mg->mg_len == HEf_SVKEY)
 		PUSHs((SV*)mg->mg_ptr);
 	}
diff --git a/objXSUB.h b/objXSUB.h
index 033430edb2..59856fde35 100644
--- a/objXSUB.h
+++ b/objXSUB.h
@@ -2893,8 +2893,6 @@
 #define sv_catsv		pPerl->Perl_sv_catsv
 #undef  sv_catsv_mg
 #define sv_catsv_mg		pPerl->Perl_sv_catsv_mg
-#undef  sv_check_thinkfirst
-#define sv_check_thinkfirst	pPerl->Perl_sv_check_thinkfirst
 #undef  sv_chop
 #define sv_chop			pPerl->Perl_sv_chop
 #undef  sv_clean_all
@@ -2919,6 +2917,8 @@
 #define sv_dump			pPerl->Perl_sv_dump
 #undef  sv_eq
 #define sv_eq			pPerl->Perl_sv_eq
+#undef  sv_force_normal
+#define sv_force_normal		pPerl->Perl_sv_force_normal
 #undef  sv_free
 #define sv_free			pPerl->Perl_sv_free
 #undef  sv_free_arenas
@@ -2947,8 +2947,6 @@
 #define sv_magic		pPerl->Perl_sv_magic
 #undef  sv_mortalcopy
 #define sv_mortalcopy		pPerl->Perl_sv_mortalcopy
-#undef  sv_mortalgrow
-#define sv_mortalgrow		pPerl->Perl_sv_mortalgrow
 #undef  sv_ncmp
 #define sv_ncmp			pPerl->Perl_sv_ncmp
 #undef  sv_newmortal
@@ -3051,6 +3049,8 @@
 #define taint_env		pPerl->Perl_taint_env
 #undef  taint_proper
 #define taint_proper		pPerl->Perl_taint_proper
+#undef  tmps_grow
+#define tmps_grow		pPerl->Perl_tmps_grow
 #undef  to_uni_lower
 #define to_uni_lower		pPerl->Perl_to_uni_lower
 #undef  to_uni_lower_lc
diff --git a/op.c b/op.c
index d5af3c90a8..635a04aad4 100644
--- a/op.c
+++ b/op.c
@@ -2189,7 +2189,7 @@ pmtrans(OP *o, OP *expr, OP *repl)
     squash	= o->op_private & OPpTRANS_SQUASH;
 
     if (o->op_private & (OPpTRANS_FROM_UTF|OPpTRANS_TO_UTF)) {
-	SV* listsv = newSVpv("# comment\n",0);
+	SV* listsv = newSVpvn("# comment\n",10);
 	SV* transv = 0;
 	U8* tend = t + tlen;
 	U8* rend = r + rlen;
@@ -2217,7 +2217,7 @@ pmtrans(OP *o, OP *expr, OP *repl)
 	    UV nextmin = 0;
 	    New(1109, cp, tlen, U8*);
 	    i = 0;
-	    transv = newSVpv("",0);
+	    transv = newSVpvn("",0);
 	    while (t < tend) {
 		cp[i++] = t;
 		t += UTF8SKIP(t);
@@ -2706,7 +2706,7 @@ utilize(int aver, I32 floor, OP *version, OP *id, OP *arg)
 	    pack = newSVOP(OP_CONST, 0, newSVsv(((SVOP*)id)->op_sv));
 
 	    /* Fake up a method call to VERSION */
-	    meth = newSVOP(OP_CONST, 0, newSVpv("VERSION", 7));
+	    meth = newSVOP(OP_CONST, 0, newSVpvn("VERSION", 7));
 	    veop = convert(OP_ENTERSUB, OPf_STACKED|OPf_SPECIAL,
 			    append_elem(OP_LIST,
 			    prepend_elem(OP_LIST, pack, list(version)),
@@ -2725,8 +2725,8 @@ utilize(int aver, I32 floor, OP *version, OP *id, OP *arg)
 	pack = newSVOP(OP_CONST, 0, newSVsv(((SVOP*)id)->op_sv));
 	meth = newSVOP(OP_CONST, 0,
 	    aver
-		? newSVpv("import", 6)
-		: newSVpv("unimport", 8)
+		? newSVpvn("import", 6)
+		: newSVpvn("unimport", 8)
 	    );
 	imop = convert(OP_ENTERSUB, OPf_STACKED|OPf_SPECIAL,
 		    append_elem(OP_LIST,
@@ -2752,7 +2752,7 @@ utilize(int aver, I32 floor, OP *version, OP *id, OP *arg)
 
     /* Fake up the BEGIN {}, which does its thing immediately. */
     newSUB(floor,
-	newSVOP(OP_CONST, 0, newSVpv("BEGIN", 5)),
+	newSVOP(OP_CONST, 0, newSVpvn("BEGIN", 5)),
 	Nullop,
 	append_elem(OP_LINESEQ,
 	    append_elem(OP_LINESEQ,
@@ -5235,7 +5235,7 @@ ck_split(OP *o)
     op_free(cLISTOPo->op_first);
     cLISTOPo->op_first = kid;
     if (!kid) {
-	cLISTOPo->op_first = kid = newSVOP(OP_CONST, 0, newSVpv(" ", 1));
+	cLISTOPo->op_first = kid = newSVOP(OP_CONST, 0, newSVpvn(" ", 1));
 	cLISTOPo->op_last = kid; /* There was only one element previously */
     }
 
diff --git a/perl.c b/perl.c
index e7bfe7e858..5321efff3c 100644
--- a/perl.c
+++ b/perl.c
@@ -187,7 +187,7 @@ perl_construct(register PerlInterpreter *sv_interp)
 #endif
     }
 
-    PL_nrs = newSVpv("\n", 1);
+    PL_nrs = newSVpvn("\n", 1);
     PL_rs = SvREFCNT_inc(PL_nrs);
 
     init_stacks(ARGS);
@@ -716,7 +716,7 @@ setuid perl scripts securely.\n");
     }
 
     sv_setpvn(PL_linestr,"",0);
-    sv = newSVpv("",0);		/* first used for -I flags */
+    sv = newSVpvn("",0);		/* first used for -I flags */
     SAVEFREESV(sv);
     init_main_stash();
 
@@ -769,7 +769,7 @@ setuid perl scripts securely.\n");
 	    if (PL_euid != PL_uid || PL_egid != PL_gid)
 		croak("No -e allowed in setuid scripts");
 	    if (!PL_e_script) {
-		PL_e_script = newSVpv("",0);
+		PL_e_script = newSVpvn("",0);
 		filter_add(read_e_script, NULL);
 	    }
 	    if (*++s)
@@ -953,7 +953,7 @@ print \"  \\@INC:\\n    @INC\\n\";");
     PL_min_intro_pending = 0;
     PL_padix = 0;
 #ifdef USE_THREADS
-    av_store(PL_comppad_name, 0, newSVpv("@_", 2));
+    av_store(PL_comppad_name, 0, newSVpvn("@_", 2));
     PL_curpad[0] = (SV*)newAV();
     SvPADMY_on(PL_curpad[0]);	/* XXX Needed? */
     CvOWNER(PL_compcv) = 0;
@@ -1555,10 +1555,10 @@ moreswitches(char *s)
 	if (rschar & ~((U8)~0))
 	    PL_nrs = &PL_sv_undef;
 	else if (!rschar && numlen >= 2)
-	    PL_nrs = newSVpv("", 0);
+	    PL_nrs = newSVpvn("", 0);
 	else {
 	    char ch = rschar;
-	    PL_nrs = newSVpv(&ch, 1);
+	    PL_nrs = newSVpvn(&ch, 1);
 	}
 	return s + numlen;
     }
@@ -1942,7 +1942,7 @@ init_main_stash(void)
     hv_ksplit(PL_strtab, 512);
     
     PL_curstash = PL_defstash = newHV();
-    PL_curstname = newSVpv("main",4);
+    PL_curstname = newSVpvn("main",4);
     gv = gv_fetchpv("main::",TRUE, SVt_PVHV);
     SvREFCNT_dec(GvHV(gv));
     GvHV(gv) = (HV*)SvREFCNT_inc(PL_defstash);
@@ -2008,7 +2008,7 @@ open_script(char *scriptname, bool dosearch, SV *sv, int *fdscript)
     }
     else if (PL_preprocess) {
 	char *cpp_cfg = CPPSTDIN;
-	SV *cpp = newSVpv("",0);
+	SV *cpp = newSVpvn("",0);
 	SV *cmd = NEWSV(0,0);
 
 	if (strEQ(cpp_cfg, "cppstdin"))
@@ -2596,7 +2596,7 @@ init_lexer(void)
     PL_rsfp = Nullfp;
     lex_start(PL_linestr);
     PL_rsfp = tmpfp;
-    PL_subname = newSVpv("main",4);
+    PL_subname = newSVpvn("main",4);
 }
 
 STATIC void
@@ -2825,7 +2825,7 @@ incpush(char *p, int addsubdirs)
 	/* skip any consecutive separators */
 	while ( *p == PERLLIB_SEP ) {
 	    /* Uncomment the next line for PATH semantics */
-	    /* av_push(GvAVn(PL_incgv), newSVpv(".", 1)); */
+	    /* av_push(GvAVn(PL_incgv), newSVpvn(".", 1)); */
 	    p++;
 	}
 
@@ -2865,7 +2865,7 @@ incpush(char *p, int addsubdirs)
 	    if (PerlLIO_stat(SvPVX(subdir), &tmpstatbuf) >= 0 &&
 		  S_ISDIR(tmpstatbuf.st_mode))
 		av_push(GvAVn(PL_incgv),
-			newSVpv(SvPVX(subdir), SvCUR(subdir) - sizeof "auto"));
+			newSVpvn(SvPVX(subdir), SvCUR(subdir) - sizeof "auto"));
 
 	    /* .../archname if -d .../archname/auto */
 	    sv_insert(subdir, SvCUR(libdir) + sizeof(ARCHNAME),
@@ -2873,7 +2873,7 @@ incpush(char *p, int addsubdirs)
 	    if (PerlLIO_stat(SvPVX(subdir), &tmpstatbuf) >= 0 &&
 		  S_ISDIR(tmpstatbuf.st_mode))
 		av_push(GvAVn(PL_incgv),
-			newSVpv(SvPVX(subdir), SvCUR(subdir) - sizeof "auto"));
+			newSVpvn(SvPVX(subdir), SvCUR(subdir) - sizeof "auto"));
 	}
 
 	/* finally push this lib directory on the end of @INC */
@@ -2940,7 +2940,7 @@ init_main_thread()
     sv_upgrade(PL_bodytarget, SVt_PVFM);
     sv_setpvn(PL_bodytarget, "", 0);
     PL_formtarget = PL_bodytarget;
-    thr->errsv = newSVpv("", 0);
+    thr->errsv = newSVpvn("", 0);
     (void) find_threadsv("@");	/* Ensure $@ is initialised early */
 
     PL_maxscream = -1;
diff --git a/pod/perlguts.pod b/pod/perlguts.pod
index c5289a1d86..b71337c137 100644
--- a/pod/perlguts.pod
+++ b/pod/perlguts.pod
@@ -2286,7 +2286,8 @@ SV is set to 1.
 =item newSVpv
 
 Creates a new SV and copies a string into it.  The reference count for the
-SV is set to 1.  If C<len> is zero then Perl will compute the length.
+SV is set to 1.  If C<len> is zero, Perl will compute the length using
+strlen().  For efficiency, consider using C<newSVpvn> instead.
 
 	SV*	newSVpv (const char* s, STRLEN len)
 
@@ -2295,13 +2296,14 @@ SV is set to 1.  If C<len> is zero then Perl will compute the length.
 Creates a new SV an initialize it with the string formatted like
 C<sprintf>.
 
-	SV*     newSVpvf(const char* pat, ...);
+	SV*     newSVpvf(const char* pat, ...)
 
 =item newSVpvn
 
 Creates a new SV and copies a string into it.  The reference count for the
-SV is set to 1.  If C<len> is zero then Perl will create a zero length 
-string.
+SV is set to 1.  Note that if C<len> is zero, Perl will create a zero length 
+string.  You are responsible for ensuring that the source string is at least
+C<len> bytes long.
 
 	SV*	newSVpvn (const char* s, STRLEN len)
 
diff --git a/pp.c b/pp.c
index b03acf3f9d..d837d4b9d1 100644
--- a/pp.c
+++ b/pp.c
@@ -448,7 +448,7 @@ PP(pp_prototype)
 		    oa = oa >> 4;
 		}
 		str[n++] = '\0';
-		ret = sv_2mortal(newSVpv(str, n - 1));
+		ret = sv_2mortal(newSVpvn(str, n - 1));
 	    }
 	    else if (code)		/* Non-Overridable */
 		goto set;
@@ -460,7 +460,7 @@ PP(pp_prototype)
     }
     cv = sv_2cv(TOPs, &stash, &gv, FALSE);
     if (cv && SvPOK(cv))
-	ret = sv_2mortal(newSVpv(SvPVX(cv), SvCUR(cv)));
+	ret = sv_2mortal(newSVpvn(SvPVX(cv), SvCUR(cv)));
   set:
     SETs(ret);
     RETURN;
@@ -609,7 +609,7 @@ PP(pp_gelem)
 	break;
     case 'N':
 	if (strEQ(elem, "NAME"))
-	    sv = newSVpv(GvNAME(gv), GvNAMELEN(gv));
+	    sv = newSVpvn(GvNAME(gv), GvNAMELEN(gv));
 	break;
     case 'P':
 	if (strEQ(elem, "PACKAGE"))
@@ -792,15 +792,8 @@ PP(pp_undef)
     if (!sv)
 	RETPUSHUNDEF;
 
-    if (SvTHINKFIRST(sv)) {
-	if (SvREADONLY(sv)) {
-	    dTHR;
-	    if (PL_curcop != &PL_compiling)
-		croak(PL_no_modify);
-	}
-	if (SvROK(sv))
-	    sv_unref(sv);
-    }
+    if (SvTHINKFIRST(sv))
+	sv_force_normal(sv);
 
     switch (SvTYPE(sv)) {
     case SVt_NULL:
@@ -817,9 +810,12 @@ PP(pp_undef)
 		 CvANON((CV*)sv) ? "(anonymous)" : GvENAME(CvGV((CV*)sv)));
 	/* FALL THROUGH */
     case SVt_PVFM:
-	{ GV* gv = (GV*)SvREFCNT_inc(CvGV((CV*)sv));
-	  cv_undef((CV*)sv);
-	  CvGV((CV*)sv) = gv; }   /* let user-undef'd sub keep its identity */
+	{
+	    /* let user-undef'd sub keep its identity */
+	    GV* gv = (GV*)SvREFCNT_inc(CvGV((CV*)sv));
+	    cv_undef((CV*)sv);
+	    CvGV((CV*)sv) = gv;
+	}
 	break;
     case SVt_PVGV:
 	if (SvFAKE(sv))
@@ -1037,12 +1033,6 @@ PP(pp_repeat)
 	STRLEN len;
 
 	tmpstr = POPs;
-	if (TARG == tmpstr && SvTHINKFIRST(tmpstr)) {
-	    if (SvREADONLY(tmpstr) && PL_curcop != &PL_compiling)
-		DIE("Can't x= to readonly value");
-	    if (SvROK(tmpstr))
-		sv_unref(tmpstr);
-	}
 	SvSetSV(TARG, tmpstr);
 	SvPV_force(TARG, len);
 	if (count != 1) {
@@ -3181,7 +3171,7 @@ mul128(SV *sv, U8 m)
   U32             i = 0;
 
   if (!strnEQ(s, "0000", 4)) {  /* need to grow sv */
-    SV             *tmpNew = newSVpv("0000000000", 10);
+    SV             *tmpNew = newSVpvn("0000000000", 10);
 
     sv_catsv(tmpNew, sv);
     SvREFCNT_dec(sv);		/* free old sv */
@@ -4171,11 +4161,11 @@ doencodes(register SV *sv, register char *s, register I32 len)
     sv_catpvn(sv, "\n", 1);
 }
 
-STATIC SV      *
+STATIC SV *
 is_an_int(char *s, STRLEN l)
 {
   STRLEN	 n_a;
-  SV             *result = newSVpv("", l);
+  SV             *result = newSVpvn(s, l);
   char           *result_c = SvPV(result, n_a);	/* convenience */
   char           *out = result_c;
   bool            skip = 1;
diff --git a/pp.h b/pp.h
index 7aeee707bb..2b8f233e6a 100644
--- a/pp.h
+++ b/pp.h
@@ -155,18 +155,18 @@
 
 #define SWITCHSTACK(f,t) \
     STMT_START {							\
-	AvFILLp(f) = sp - PL_stack_base;					\
+	AvFILLp(f) = sp - PL_stack_base;				\
 	PL_stack_base = AvARRAY(t);					\
-	PL_stack_max = PL_stack_base + AvMAX(t);				\
+	PL_stack_max = PL_stack_base + AvMAX(t);			\
 	sp = PL_stack_sp = PL_stack_base + AvFILLp(t);			\
-	PL_curstack = t;							\
+	PL_curstack = t;						\
     } STMT_END
 
 #define EXTEND_MORTAL(n) \
-	STMT_START { \
-	    if (PL_tmps_ix + (n) >= PL_tmps_max) \
-		Renew(PL_tmps_stack, PL_tmps_max = PL_tmps_ix + (n) + 1, SV*); \
-	} STMT_END
+    STMT_START {							\
+	if (PL_tmps_ix + (n) >= PL_tmps_max)				\
+	    tmps_grow(n);						\
+    } STMT_END
 
 #define AMGf_noright	1
 #define AMGf_noleft	2
diff --git a/pp_ctl.c b/pp_ctl.c
index 9d22e64e58..e29ff19997 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -1489,7 +1489,8 @@ PP(pp_caller)
 	PUSHs(&PL_sv_undef);
     else
 	PUSHs(sv_2mortal(newSVpv(HvNAME(hv), 0)));
-    PUSHs(sv_2mortal(newSVpv(SvPVX(GvSV(cx->blk_oldcop->cop_filegv)), 0)));
+    PUSHs(sv_2mortal(newSVpvn(SvPVX(GvSV(cx->blk_oldcop->cop_filegv)),
+			      SvCUR(GvSV(cx->blk_oldcop->cop_filegv)))));
     PUSHs(sv_2mortal(newSViv((I32)cx->blk_oldcop->cop_line)));
     if (!MAXARG)
 	RETURN;
@@ -1500,7 +1501,7 @@ PP(pp_caller)
 	PUSHs(sv_2mortal(newSViv((I32)cx->blk_sub.hasargs)));
     }
     else {
-	PUSHs(sv_2mortal(newSVpv("(eval)",0)));
+	PUSHs(sv_2mortal(newSVpvn("(eval)",6)));
 	PUSHs(sv_2mortal(newSViv(0)));
     }
     gimme = (I32)cx->blk_gimme;
@@ -2120,6 +2121,7 @@ PP(pp_goto)
 	    /* Now do some callish stuff. */
 	    SAVETMPS;
 	    if (CvXSUB(cv)) {
+#ifdef PERL_XSUB_OLDSTYLE
 		if (CvOLDSTYLE(cv)) {
 		    I32 (*fp3)_((int,int,int));
 		    while (SP > mark) {
@@ -2132,7 +2134,9 @@ PP(pp_goto)
 				   items);
 		    SP = PL_stack_base + items;
 		}
-		else {
+		else
+#endif /* PERL_XSUB_OLDSTYLE */
+		{
 		    SV **newsp;
 		    I32 gimme;
 
@@ -2634,7 +2638,7 @@ doeval(int gimme, OP** startop)
     PL_min_intro_pending = 0;
     PL_padix = 0;
 #ifdef USE_THREADS
-    av_store(PL_comppad_name, 0, newSVpv("@_", 2));
+    av_store(PL_comppad_name, 0, newSVpvn("@_", 2));
     PL_curpad[0] = (SV*)newAV();
     SvPADMY_on(PL_curpad[0]);	/* XXX Needed? */
 #endif /* USE_THREADS */
@@ -2668,7 +2672,7 @@ doeval(int gimme, OP** startop)
     PL_curcop = &PL_compiling;
     PL_curcop->cop_arybase = 0;
     SvREFCNT_dec(PL_rs);
-    PL_rs = newSVpv("\n", 1);
+    PL_rs = newSVpvn("\n", 1);
     if (saveop && saveop->op_flags & OPf_SPECIAL)
 	PL_in_eval |= 4;
     else
@@ -2876,7 +2880,7 @@ PP(pp_require)
 
     ENTER;
     SAVETMPS;
-    lex_start(sv_2mortal(newSVpv("",0)));
+    lex_start(sv_2mortal(newSVpvn("",0)));
     SAVEGENERICSV(PL_rsfp_filters);
     PL_rsfp_filters = Nullav;
 
diff --git a/pp_hot.c b/pp_hot.c
index 0785f5ff71..f48e98f8dc 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -733,16 +733,10 @@ PP(pp_aassign)
 	    }
 	    break;
 	default:
-	    if (SvTHINKFIRST(sv)) {
-		if (SvREADONLY(sv) && PL_curcop != &PL_compiling) {
-		    if (!SvIMMORTAL(sv))
-			DIE(PL_no_modify);
-		    if (relem <= lastrelem)
-			relem++;
-		    break;
-		}
-		if (SvROK(sv))
-		    sv_unref(sv);
+	    if (SvIMMORTAL(sv)) {
+		if (relem <= lastrelem)
+		    relem++;
+		break;
 	    }
 	    if (relem <= lastrelem) {
 		sv_setsv(sv, *relem);
@@ -2099,16 +2093,15 @@ PP(pp_entersub)
     case SVt_PVGV:
 	if (!(cv = GvCVu((GV*)sv)))
 	    cv = sv_2cv(sv, &stash, &gv, TRUE);
-	break;
+	if (cv)
+	    break;
+	DIE("Not a CODE reference");
     }
 
     ENTER;
     SAVETMPS;
 
   retry:
-    if (!cv)
-	DIE("Not a CODE reference");
-
     if (!CvROOT(cv) && !CvXSUB(cv)) {
 	GV* autogv;
 	SV* sub_name;
@@ -2116,29 +2109,34 @@ PP(pp_entersub)
 	/* anonymous or undef'd function leaves us no recourse */
 	if (CvANON(cv) || !(gv = CvGV(cv)))
 	    DIE("Undefined subroutine called");
+
 	/* autoloaded stub? */
 	if (cv != GvCV(gv)) {
 	    cv = GvCV(gv);
-	    goto retry;
 	}
 	/* should call AUTOLOAD now? */
-	if ((autogv = gv_autoload4(GvSTASH(gv), GvNAME(gv), GvNAMELEN(gv),
+	else if ((autogv = gv_autoload4(GvSTASH(gv), GvNAME(gv), GvNAMELEN(gv),
 				   FALSE)))
 	{
 	    cv = GvCV(autogv);
-	    goto retry;
 	}
 	/* sorry */
-	sub_name = sv_newmortal();
-	gv_efullname3(sub_name, gv, Nullch);
-	DIE("Undefined subroutine &%s called", SvPVX(sub_name));
+	else {
+	    sub_name = sv_newmortal();
+	    gv_efullname3(sub_name, gv, Nullch);
+	    DIE("Undefined subroutine &%s called", SvPVX(sub_name));
+	}
+	if (!cv)
+	    DIE("Not a CODE reference");
+	goto retry;
     }
 
     gimme = GIMME_V;
-    if ((PL_op->op_private & OPpENTERSUB_DB) && GvCV(PL_DBsub) && !CvNODEBUG(cv))
+    if ((PL_op->op_private & OPpENTERSUB_DB) && GvCV(PL_DBsub) && !CvNODEBUG(cv)) {
 	cv = get_db_sub(&sv, cv);
-    if (!cv)
-	DIE("No DBsub routine");
+	if (!cv)
+	    DIE("No DBsub routine");
+    }
 
 #ifdef USE_THREADS
     /*
@@ -2274,6 +2272,7 @@ PP(pp_entersub)
 #endif /* USE_THREADS */
 
     if (CvXSUB(cv)) {
+#ifdef PERL_XSUB_OLDSTYLE
 	if (CvOLDSTYLE(cv)) {
 	    I32 (*fp3)_((int,int,int));
 	    dMARK;
@@ -2290,7 +2289,9 @@ PP(pp_entersub)
 			   items);
 	    PL_stack_sp = PL_stack_base + items;
 	}
-	else {
+	else
+#endif /* PERL_XSUB_OLDSTYLE */
+	{
 	    I32 markix = TOPMARK;
 
 	    PUTBACK;
@@ -2316,9 +2317,8 @@ PP(pp_entersub)
 		    PUTBACK ;		    
 		}
 	    }
-	    if (PL_curcopdb) {		/* We assume that the first
-					   XSUB in &DB::sub is the
-					   called one. */
+	    /* We assume first XSUB in &DB::sub is the called one. */
+	    if (PL_curcopdb) {
 		SAVESPTR(PL_curcop);
 		PL_curcop = PL_curcopdb;
 		PL_curcopdb = NULL;
diff --git a/pp_sys.c b/pp_sys.c
index 2ba6ecb16b..39984972ec 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -370,7 +370,7 @@ PP(pp_glob)
     PL_last_in_gv = (GV*)*PL_stack_sp--;
 
     SAVESPTR(PL_rs);		/* This is not permanent, either. */
-    PL_rs = sv_2mortal(newSVpv("", 1));
+    PL_rs = sv_2mortal(newSVpvn("\000", 1));
 #ifndef DOSISH
 #ifndef CSH
     *SvPVX(PL_rs) = '\n';
@@ -1639,7 +1639,7 @@ PP(pp_sysseek)
 	Off_t n = do_sysseek(gv, offset, whence);
 	PUSHs((n < 0) ? &PL_sv_undef
 	      : sv_2mortal(n ? newSViv((IV)n)
-			   : newSVpv(zero_but_true, ZBTLEN)));
+			   : newSVpvn(zero_but_true, ZBTLEN)));
     }
     RETURN;
 }
@@ -2332,7 +2332,7 @@ PP(pp_stat)
 #ifdef USE_STAT_RDEV
 	PUSHs(sv_2mortal(newSViv((I32)PL_statcache.st_rdev)));
 #else
-	PUSHs(sv_2mortal(newSVpv("", 0)));
+	PUSHs(sv_2mortal(newSVpvn("", 0)));
 #endif
 	PUSHs(sv_2mortal(newSViv((I32)PL_statcache.st_size)));
 #ifdef BIG_TIME
@@ -2348,8 +2348,8 @@ PP(pp_stat)
 	PUSHs(sv_2mortal(newSViv((I32)PL_statcache.st_blksize)));
 	PUSHs(sv_2mortal(newSViv((I32)PL_statcache.st_blocks)));
 #else
-	PUSHs(sv_2mortal(newSVpv("", 0)));
-	PUSHs(sv_2mortal(newSVpv("", 0)));
+	PUSHs(sv_2mortal(newSVpvn("", 0)));
+	PUSHs(sv_2mortal(newSVpvn("", 0)));
 #endif
     }
     RETURN;
@@ -3235,7 +3235,7 @@ PP(pp_readdir)
 	/*SUPPRESS 560*/
 	while (dp = (Direntry_t *)PerlDir_read(IoDIRP(io))) {
 #ifdef DIRNAMLEN
-	    sv = newSVpv(dp->d_name, dp->d_namlen);
+	    sv = newSVpvn(dp->d_name, dp->d_namlen);
 #else
 	    sv = newSVpv(dp->d_name, 0);
 #endif
@@ -3249,7 +3249,7 @@ PP(pp_readdir)
 	if (!(dp = (Direntry_t *)PerlDir_read(IoDIRP(io))))
 	    goto nope;
 #ifdef DIRNAMLEN
-	sv = newSVpv(dp->d_name, dp->d_namlen);
+	sv = newSVpvn(dp->d_name, dp->d_namlen);
 #else
 	sv = newSVpv(dp->d_name, 0);
 #endif
diff --git a/proto.h b/proto.h
index b809ea06e2..cc98104ed4 100644
--- a/proto.h
+++ b/proto.h
@@ -715,9 +715,7 @@ void del_xiv _((XPVIV* p));
 void del_xnv _((XPVNV* p));
 void del_xpv _((XPV* p));
 void del_xrv _((XRV* p));
-void sv_mortalgrow _((void));
 void sv_unglob _((SV* sv));
-void sv_check_thinkfirst _((SV *sv));
 I32 avhv_index_sv _((SV* sv));
 
 void do_report_used _((SV *sv));
@@ -967,3 +965,6 @@ VIRTUAL void magic_dump _((MAGIC *mg));
 VIRTUAL void reginitcolors _((void));
 VIRTUAL char* sv_2pv_nolen _((SV* sv));
 VIRTUAL char* sv_pv _((SV *sv));
+VIRTUAL void sv_force_normal _((SV *sv));
+VIRTUAL void tmps_grow _((I32 n));
+
diff --git a/regcomp.c b/regcomp.c
index bacf2ca440..d8a62daee4 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -616,7 +616,7 @@ study_chunk(regnode **scanp, I32 *deltap, regnode *last, scan_data_t *data, U32
 			
 			l -= old;
 			/* Get the added string: */
-			last_str = newSVpv(s  + old, l);
+			last_str = newSVpvn(s  + old, l);
 			if (deltanext == 0 && pos_before == b) {
 			    /* What was added is a constant string */
 			    if (mincount > 1) {
@@ -977,9 +977,9 @@ pregcomp(char *exp, char *xend, PMOP *pm)
 	*/
 	minlen = 0;
 
-	data.longest_fixed = newSVpv("",0);
-	data.longest_float = newSVpv("",0);
-	data.last_found = newSVpv("",0);
+	data.longest_fixed = newSVpvn("",0);
+	data.longest_float = newSVpvn("",0);
+	data.last_found = newSVpvn("",0);
 	data.longest = &(data.longest_fixed);
 	first = scan;
 	
@@ -1166,9 +1166,9 @@ reg(I32 paren, I32 *flagp)
 		    AV *av;
 		    
 		    if (PL_regcomp_parse - 1 - s) 
-			sv = newSVpv(s, PL_regcomp_parse - 1 - s);
+			sv = newSVpvn(s, PL_regcomp_parse - 1 - s);
 		    else
-			sv = newSVpv("", 0);
+			sv = newSVpvn("", 0);
 
 		    rop = sv_compile_2op(sv, &sop, "re", &av);
 
@@ -2378,7 +2378,7 @@ regclassutf8(void)
 	    flags |= ANYOF_FOLD;
 	if (LOC)
 	    flags |= ANYOF_LOCALE;
-	listsv = newSVpv("# comment\n",0);
+	listsv = newSVpvn("# comment\n",10);
     }
 
     if (*PL_regcomp_parse == ']' || *PL_regcomp_parse == '-')
diff --git a/scope.c b/scope.c
index 4a2a778605..b8d45584e2 100644
--- a/scope.c
+++ b/scope.c
@@ -135,6 +135,19 @@ savestack_grow(void)
 #undef GROW
 
 void
+tmps_grow(I32 n)
+{
+    dTHR;
+#ifndef STRESS_REALLOC
+    if (n < 128)
+	n = (PL_tmps_max < 512) ? 128 : 512;
+#endif
+    PL_tmps_max = PL_tmps_ix + n + 1;
+    Renew(PL_tmps_stack, PL_tmps_max, SV*);
+}
+
+
+void
 free_tmps(void)
 {
     dTHR;
@@ -742,12 +755,8 @@ leave_scope(I32 base)
 	    sv = *(SV**)ptr;
 	    /* Can clear pad variable in place? */
 	    if (SvREFCNT(sv) <= 1 && !SvOBJECT(sv)) {
-		if (SvTHINKFIRST(sv)) {
-		    if (SvREADONLY(sv))
-			croak("panic: leave_scope clearsv");
-		    if (SvROK(sv))
-			sv_unref(sv);
-		}
+		if (SvTHINKFIRST(sv))
+		    sv_force_normal(sv);
 		if (SvMAGICAL(sv))
 		    mg_free(sv);
 
diff --git a/sv.c b/sv.c
index 6310937cc5..218eff9aea 100644
--- a/sv.c
+++ b/sv.c
@@ -57,9 +57,7 @@ static void del_xiv _((XPVIV* p));
 static void del_xnv _((XPVNV* p));
 static void del_xpv _((XPV* p));
 static void del_xrv _((XRV* p));
-static void sv_mortalgrow _((void));
 static void sv_unglob _((SV* sv));
-static void sv_check_thinkfirst _((SV *sv));
 
 #ifndef PURIFY
 static void *my_safemalloc(MEM_SIZE size);
@@ -71,25 +69,28 @@ typedef void (*SVFUNC) _((SV*));
 
 #endif /* PERL_OBJECT */
 
-#define SV_CHECK_THINKFIRST(sv) if (SvTHINKFIRST(sv)) sv_check_thinkfirst(sv)
+#define SV_CHECK_THINKFIRST(sv) if (SvTHINKFIRST(sv)) sv_force_normal(sv)
 
 #ifdef PURIFY
 
-#define new_SV(p)			\
-    do {				\
-	LOCK_SV_MUTEX;			\
-	(p) = (SV*)safemalloc(sizeof(SV)); \
-	reg_add(p);			\
-	UNLOCK_SV_MUTEX;		\
-    } while (0)
-
-#define del_SV(p)			\
-    do {				\
-	LOCK_SV_MUTEX;			\
-	reg_remove(p);			\
-        Safefree((char*)(p));		\
-	UNLOCK_SV_MUTEX;		\
-    } while (0)
+#define new_SV(p) \
+    STMT_START {					\
+	LOCK_SV_MUTEX;					\
+	(p) = (SV*)safemalloc(sizeof(SV));		\
+	reg_add(p);					\
+	UNLOCK_SV_MUTEX;				\
+	SvANY(p) = 0;					\
+	SvREFCNT(p) = 1;				\
+	SvFLAGS(p) = 0;					\
+    } STMT_END
+
+#define del_SV(p) \
+    STMT_START {					\
+	LOCK_SV_MUTEX;					\
+	reg_remove(p);					\
+        Safefree((char*)(p));				\
+	UNLOCK_SV_MUTEX;				\
+    } STMT_END
 
 static SV **registry;
 static I32 registry_size;
@@ -97,18 +98,18 @@ static I32 registry_size;
 #define REGHASH(sv,size)  ((((U32)(sv)) >> 2) % (size))
 
 #define REG_REPLACE(sv,a,b) \
-    do {				\
-	void* p = sv->sv_any;		\
-	I32 h = REGHASH(sv, registry_size);	\
-	I32 i = h;			\
-	while (registry[i] != (a)) {	\
-	    if (++i >= registry_size)	\
-		i = 0;			\
-	    if (i == h)			\
-		die("SV registry bug");	\
-	}				\
-	registry[i] = (b);		\
-    } while (0)
+    STMT_START {					\
+	void* p = sv->sv_any;				\
+	I32 h = REGHASH(sv, registry_size);		\
+	I32 i = h;					\
+	while (registry[i] != (a)) {			\
+	    if (++i >= registry_size)			\
+		i = 0;					\
+	    if (i == h)					\
+		die("SV registry bug");			\
+	}						\
+	registry[i] = (b);				\
+    } STMT_END
 
 #define REG_ADD(sv)	REG_REPLACE(sv,Nullsv,sv)
 #define REG_REMOVE(sv)	REG_REPLACE(sv,sv,Nullsv)
@@ -178,41 +179,46 @@ U32 flags;
  * "A time to plant, and a time to uproot what was planted..."
  */
 
-#define plant_SV(p)			\
-    do {				\
-	SvANY(p) = (void *)PL_sv_root;	\
-	SvFLAGS(p) = SVTYPEMASK;	\
-	PL_sv_root = (p);			\
-	--PL_sv_count;			\
-    } while (0)
+#define plant_SV(p) \
+    STMT_START {					\
+	SvANY(p) = (void *)PL_sv_root;			\
+	SvFLAGS(p) = SVTYPEMASK;			\
+	PL_sv_root = (p);				\
+	--PL_sv_count;					\
+    } STMT_END
 
 /* sv_mutex must be held while calling uproot_SV() */
-#define uproot_SV(p)			\
-    do {				\
-	(p) = PL_sv_root;			\
-	PL_sv_root = (SV*)SvANY(p);	\
-	++PL_sv_count;			\
-    } while (0)
-
-#define new_SV(p)	do {	\
-	LOCK_SV_MUTEX;		\
-	if (PL_sv_root)		\
-	    uproot_SV(p);	\
-	else			\
-	    (p) = more_sv();	\
-	UNLOCK_SV_MUTEX;	\
-    } while (0)
+#define uproot_SV(p) \
+    STMT_START {					\
+	(p) = PL_sv_root;				\
+	PL_sv_root = (SV*)SvANY(p);			\
+	++PL_sv_count;					\
+    } STMT_END
+
+#define new_SV(p) \
+    STMT_START {					\
+	LOCK_SV_MUTEX;					\
+	if (PL_sv_root)					\
+	    uproot_SV(p);				\
+	else						\
+	    (p) = more_sv();				\
+	UNLOCK_SV_MUTEX;				\
+	SvANY(p) = 0;					\
+	SvREFCNT(p) = 1;				\
+	SvFLAGS(p) = 0;					\
+    } STMT_END
 
 #ifdef DEBUGGING
 
-#define del_SV(p)	do {	\
-	LOCK_SV_MUTEX;		\
-	if (PL_debug & 32768)	\
-	    del_sv(p);		\
-	else			\
-	    plant_SV(p);	\
-	UNLOCK_SV_MUTEX;	\
-    } while (0)
+#define del_SV(p) \
+    STMT_START {					\
+	LOCK_SV_MUTEX;					\
+	if (PL_debug & 32768)				\
+	    del_sv(p);					\
+	else						\
+	    plant_SV(p);				\
+	UNLOCK_SV_MUTEX;				\
+    } STMT_END
 
 STATIC void
 del_sv(SV *p)
@@ -1002,11 +1008,6 @@ sv_setiv(register SV *sv, IV i)
 	break;
 
     case SVt_PVGV:
-	if (SvFAKE(sv)) {
-	    sv_unglob(sv);
-	    break;
-	}
-	/* FALL THROUGH */
     case SVt_PVAV:
     case SVt_PVHV:
     case SVt_PVCV:
@@ -1062,11 +1063,6 @@ sv_setnv(register SV *sv, double num)
 	break;
 
     case SVt_PVGV:
-	if (SvFAKE(sv)) {
-	    sv_unglob(sv);
-	    break;
-	}
-	/* FALL THROUGH */
     case SVt_PVAV:
     case SVt_PVHV:
     case SVt_PVCV:
@@ -1810,13 +1806,6 @@ sv_setsv(SV *dstr, register SV *sstr)
     stype = SvTYPE(sstr);
     dtype = SvTYPE(dstr);
 
-    if (dtype == SVt_PVGV && (SvFLAGS(dstr) & SVf_FAKE)) {
-        sv_unglob(dstr);     /* so fake GLOB won't perpetuate */
-	sv_setpvn(dstr, "", 0);
-        (void)SvPOK_only(dstr);
-        dtype = SvTYPE(dstr);
-    }
-
     SvAMAGIC_off(dstr);
 
     /* There's a lot of redundancy below but we're going for speed here */
@@ -1949,9 +1938,9 @@ sv_setsv(SV *dstr, register SV *sstr)
 	    }
 	}
 	if (stype == SVt_PVLV)
-	    SvUPGRADE(dstr, SVt_PVNV);
+	    (void)SvUPGRADE(dstr, SVt_PVNV);
 	else
-	    SvUPGRADE(dstr, stype);
+	    (void)SvUPGRADE(dstr, stype);
     }
 
     sflags = SvFLAGS(sstr);
@@ -2183,12 +2172,7 @@ sv_setpvn(register SV *sv, register const char *ptr, register STRLEN len)
 	(void)SvOK_off(sv);
 	return;
     }
-    if (SvTYPE(sv) >= SVt_PV) {
-	if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV)
-	    sv_unglob(sv);
-    }
-    else
-	sv_upgrade(sv, SVt_PV);
+    (void)SvUPGRADE(sv, SVt_PV);
 
     SvGROW(sv, len + 1);
     dptr = SvPVX(sv);
@@ -2217,12 +2201,7 @@ sv_setpv(register SV *sv, register const char *ptr)
 	return;
     }
     len = strlen(ptr);
-    if (SvTYPE(sv) >= SVt_PV) {
-	if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV)
-	    sv_unglob(sv);
-    }
-    else 
-	sv_upgrade(sv, SVt_PV);
+    (void)SvUPGRADE(sv, SVt_PV);
 
     SvGROW(sv, len + 1);
     Move(ptr,SvPVX(sv),len+1,char);
@@ -2266,8 +2245,8 @@ sv_usepvn_mg(register SV *sv, register char *ptr, register STRLEN len)
     SvSETMAGIC(sv);
 }
 
-STATIC void
-sv_check_thinkfirst(register SV *sv)
+void
+sv_force_normal(register SV *sv)
 {
     if (SvREADONLY(sv)) {
 	dTHR;
@@ -2276,6 +2255,8 @@ sv_check_thinkfirst(register SV *sv)
     }
     if (SvROK(sv))
 	sv_unref(sv);
+    else if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV)
+	sv_unglob(sv);
 }
     
 void
@@ -2378,9 +2359,6 @@ newSV(STRLEN len)
     register SV *sv;
     
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     if (len) {
 	sv_upgrade(sv, SVt_PV);
 	SvGROW(sv, len + 1);
@@ -3176,12 +3154,7 @@ sv_gets(register SV *sv, register PerlIO *fp, I32 append)
     I32 i;
 
     SV_CHECK_THINKFIRST(sv);
-    if (SvTYPE(sv) >= SVt_PV) {
-	if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV)
-	    sv_unglob(sv);
-    }
-    else
-	sv_upgrade(sv, SVt_PV);
+    (void)SvUPGRADE(sv, SVt_PV);
 
     SvSCREAM_off(sv);
 
@@ -3582,14 +3555,6 @@ sv_dec(register SV *sv)
  * hopefully we won't free it until it has been assigned to a
  * permanent location. */
 
-STATIC void
-sv_mortalgrow(void)
-{
-    dTHR;
-    PL_tmps_max += (PL_tmps_max < 512) ? 128 : 512;
-    Renew(PL_tmps_stack, PL_tmps_max, SV*);
-}
-
 SV *
 sv_mortalcopy(SV *oldstr)
 {
@@ -3597,13 +3562,9 @@ sv_mortalcopy(SV *oldstr)
     register SV *sv;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     sv_setsv(sv,oldstr);
-    if (++PL_tmps_ix >= PL_tmps_max)
-	sv_mortalgrow();
-    PL_tmps_stack[PL_tmps_ix] = sv;
+    EXTEND_MORTAL(1);
+    PL_tmps_stack[++PL_tmps_ix] = sv;
     SvTEMP_on(sv);
     return sv;
 }
@@ -3615,12 +3576,9 @@ sv_newmortal(void)
     register SV *sv;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
     SvFLAGS(sv) = SVs_TEMP;
-    if (++PL_tmps_ix >= PL_tmps_max)
-	sv_mortalgrow();
-    PL_tmps_stack[PL_tmps_ix] = sv;
+    EXTEND_MORTAL(1);
+    PL_tmps_stack[++PL_tmps_ix] = sv;
     return sv;
 }
 
@@ -3634,9 +3592,8 @@ sv_2mortal(register SV *sv)
 	return sv;
     if (SvREADONLY(sv) && SvIMMORTAL(sv))
 	return sv;
-    if (++PL_tmps_ix >= PL_tmps_max)
-	sv_mortalgrow();
-    PL_tmps_stack[PL_tmps_ix] = sv;
+    EXTEND_MORTAL(1);
+    PL_tmps_stack[++PL_tmps_ix] = sv;
     SvTEMP_on(sv);
     return sv;
 }
@@ -3647,9 +3604,6 @@ newSVpv(const char *s, STRLEN len)
     register SV *sv;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     if (!len)
 	len = strlen(s);
     sv_setpvn(sv,s,len);
@@ -3662,9 +3616,6 @@ newSVpvn(const char *s, STRLEN len)
     register SV *sv;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     sv_setpvn(sv,s,len);
     return sv;
 }
@@ -3676,9 +3627,6 @@ newSVpvf(const char* pat, ...)
     va_list args;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     va_start(args, pat);
     sv_vsetpvfn(sv, pat, strlen(pat), &args, Null(SV**), 0, Null(bool*));
     va_end(args);
@@ -3692,9 +3640,6 @@ newSVnv(double n)
     register SV *sv;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     sv_setnv(sv,n);
     return sv;
 }
@@ -3705,9 +3650,6 @@ newSViv(IV i)
     register SV *sv;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     sv_setiv(sv,i);
     return sv;
 }
@@ -3719,9 +3661,6 @@ newRV_noinc(SV *tmpRef)
     register SV *sv;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     sv_upgrade(sv, SVt_RV);
     SvTEMP_off(tmpRef);
     SvRV(sv) = tmpRef;
@@ -3749,9 +3688,6 @@ newSVsv(register SV *old)
 	return Nullsv;
     }
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 1;
-    SvFLAGS(sv) = 0;
     if (SvTEMP(old)) {
 	SvTEMP_off(old);
 	sv_setsv(sv,old);
@@ -4016,27 +3952,17 @@ sv_pvn_force(SV *sv, STRLEN *lp)
 {
     char *s;
 
-    if (SvREADONLY(sv)) {
-	dTHR;
-	if (PL_curcop != &PL_compiling)
-	    croak(PL_no_modify);
-    }
+    if (SvTHINKFIRST(sv) && !SvROK(sv))
+	sv_force_normal(sv);
     
     if (SvPOK(sv)) {
 	*lp = SvCUR(sv);
     }
     else {
 	if (SvTYPE(sv) > SVt_PVLV && SvTYPE(sv) != SVt_PVFM) {
-	    if (SvFAKE(sv) && SvTYPE(sv) == SVt_PVGV) {
-		sv_unglob(sv);
-		s = SvPVX(sv);
-		*lp = SvCUR(sv);
-	    }
-	    else {
-		dTHR;
-		croak("Can't coerce %s to string in %s", sv_reftype(sv,0),
-		    PL_op_name[PL_op->op_type]);
-	    }
+	    dTHR;
+	    croak("Can't coerce %s to string in %s", sv_reftype(sv,0),
+		PL_op_name[PL_op->op_type]);
 	}
 	else
 	    s = sv_2pv(sv, lp);
@@ -4130,9 +4056,6 @@ newSVrv(SV *rv, const char *classname)
     SV *sv;
 
     new_SV(sv);
-    SvANY(sv) = 0;
-    SvREFCNT(sv) = 0;
-    SvFLAGS(sv) = 0;
 
     SV_CHECK_THINKFIRST(rv);
     SvAMAGIC_off(rv);
@@ -4141,7 +4064,7 @@ newSVrv(SV *rv, const char *classname)
       sv_upgrade(rv, SVt_RV);
 
     (void)SvOK_off(rv);
-    SvRV(rv) = SvREFCNT_inc(sv);
+    SvRV(rv) = sv;
     SvROK_on(rv);
 
     if (classname) {
diff --git a/sv.h b/sv.h
index fb8990747d..92e9207e5d 100644
--- a/sv.h
+++ b/sv.h
@@ -137,7 +137,7 @@ struct io {
 #define SVf_BREAK	0x00400000	/* refcnt is artificially low */
 #define SVf_READONLY	0x00800000	/* may not be modified */
 
-#define SVf_THINKFIRST	(SVf_READONLY|SVf_ROK)
+#define SVf_THINKFIRST	(SVf_READONLY|SVf_ROK|SVf_FAKE)
 
 #define SVp_IOK		0x01000000	/* has valid non-public integer value */
 #define SVp_NOK		0x02000000	/* has valid non-public numeric value */
diff --git a/toke.c b/toke.c
index 5ad891bab8..4803bc8425 100644
--- a/toke.c
+++ b/toke.c
@@ -363,7 +363,7 @@ lex_start(SV *line)
     PL_oldoldbufptr = PL_oldbufptr = PL_bufptr = PL_linestart = SvPVX(PL_linestr);
     PL_bufend = PL_bufptr + SvCUR(PL_linestr);
     SvREFCNT_dec(PL_rs);
-    PL_rs = newSVpv("\n", 1);
+    PL_rs = newSVpvn("\n", 1);
     PL_rsfp = 0;
 }
 
@@ -683,7 +683,7 @@ tokeq(SV *sv)
 	goto finish;
     d = s;
     if ( PL_hints & HINT_NEW_STRING )
-	pv = sv_2mortal(newSVpv(SvPVX(pv), len));
+	pv = sv_2mortal(newSVpvn(SvPVX(pv), len));
     while (s < send) {
 	if (*s == '\\') {
 	    if (s + 1 < send && (s[1] == '\\'))
@@ -719,7 +719,7 @@ sublex_start(void)
 	    SV *nsv;
 
 	    p = SvPV(sv, len);
-	    nsv = newSVpv(p, len);
+	    nsv = newSVpvn(p, len);
 	    SvREFCNT_dec(sv);
 	    sv = nsv;
 	} 
@@ -801,7 +801,7 @@ sublex_done(void)
 {
     if (!PL_lex_starts++) {
 	PL_expect = XOPERATOR;
-	yylval.opval = (OP*)newSVOP(OP_CONST, 0, newSVpv("",0));
+	yylval.opval = (OP*)newSVOP(OP_CONST, 0, newSVpvn("",0));
 	return THING;
     }
 
@@ -1411,7 +1411,7 @@ intuit_method(char *start, GV *gv)
 		return 0;	/* no assumptions -- "=>" quotes bearword */
       bare_package:
 	    PL_nextval[PL_nexttoke].opval = (OP*)newSVOP(OP_CONST, 0,
-						   newSVpv(tmpbuf,0));
+						   newSVpvn(tmpbuf,len));
 	    PL_nextval[PL_nexttoke].opval->op_private = OPpCONST_BARE;
 	    PL_expect = XTERM;
 	    force_next(WORD);
@@ -3129,7 +3129,7 @@ int yylex(PERL_YYLEX_PARAM_DECL)
 		/* if we saw a global override before, get the right name */
 
 		if (gvp) {
-		    sv = newSVpv("CORE::GLOBAL::",14);
+		    sv = newSVpvn("CORE::GLOBAL::",14);
 		    sv_catpv(sv,PL_tokenbuf);
 		}
 		else
@@ -5011,7 +5011,7 @@ new_constant(char *s, STRLEN len, char *key, SV *sv, SV *pv, char *type)
     sv_2mortal(sv);			/* Parent created it permanently */
     cv = *cvp;
     if (!pv)
-	pv = sv_2mortal(newSVpv(s, len));
+	pv = sv_2mortal(newSVpvn(s, len));
     if (type)
 	typesv = sv_2mortal(newSVpv(type, 0));
     else
@@ -5356,7 +5356,7 @@ scan_subst(char *start)
 	PL_sublex_info.super_bufend = PL_bufend;
 	PL_multi_end = 0;
 	pm->op_pmflags |= PMf_EVAL;
-	repl = newSVpv("",0);
+	repl = newSVpvn("",0);
 	while (es-- > 0)
 	    sv_catpv(repl, es ? "eval " : "do ");
 	sv_catpvn(repl, "{ ", 2);
@@ -5524,9 +5524,9 @@ scan_heredoc(register char *s)
 #endif
     d = "\n";
     if (outer || !(d=ninstr(s,PL_bufend,d,d+1)))
-	herewas = newSVpv(s,PL_bufend-s);
+	herewas = newSVpvn(s,PL_bufend-s);
     else
-	s--, herewas = newSVpv(s,d-s);
+	s--, herewas = newSVpvn(s,d-s);
     s += SvCUR(herewas);
 
     tmpstr = NEWSV(87,79);
@@ -6233,7 +6233,7 @@ scan_formline(register char *s)
     dTHR;
     register char *eol;
     register char *t;
-    SV *stuff = newSVpv("",0);
+    SV *stuff = newSVpvn("",0);
     bool needargs = FALSE;
 
     while (!needargs) {
@@ -6346,7 +6346,7 @@ start_subparse(I32 is_format, U32 flags)
     PL_padix = 0;
     PL_subline = PL_curcop->cop_line;
 #ifdef USE_THREADS
-    av_store(PL_comppad_name, 0, newSVpv("@_", 2));
+    av_store(PL_comppad_name, 0, newSVpvn("@_", 2));
     PL_curpad[0] = (SV*)newAV();
     SvPADMY_on(PL_curpad[0]);	/* XXX Needed? */
 #endif /* USE_THREADS */
@@ -6415,7 +6415,7 @@ yyerror(char *s)
 	    where = "within string";
     }
     else {
-	SV *where_sv = sv_2mortal(newSVpv("next char ", 0));
+	SV *where_sv = sv_2mortal(newSVpvn("next char ", 10));
 	if (yychar < 32)
 	    sv_catpvf(where_sv, "^%c", toCTRL(yychar));
 	else if (isPRINT_LC(yychar))
diff --git a/util.c b/util.c
index f08a593b93..0b3673e049 100644
--- a/util.c
+++ b/util.c
@@ -1277,7 +1277,7 @@ die(const char* pat, ...)
 	    SV *msg;
 
 	    ENTER;
-	    if(message) {
+	    if (message) {
 		msg = newSVpv(message, 0);
 		SvREADONLY_on(msg);
 		SAVEFREESV(msg);
@@ -2840,7 +2840,7 @@ new_struct_thread(struct perl_thread *t)
     SV **svp;
     I32 i;
 
-    sv = newSVpv("", 0);
+    sv = newSVpvn("", 0);
     SvGROW(sv, sizeof(struct perl_thread) + 1);
     SvCUR_set(sv, sizeof(struct perl_thread));
     thr = (Thread) SvPVX(sv);
@@ -2864,7 +2864,7 @@ new_struct_thread(struct perl_thread *t)
     thr->cvcache = newHV();
     thr->threadsv = newAV();
     thr->specific = newAV();
-    thr->errsv = newSVpv("", 0);
+    thr->errsv = newSVpvn("", 0);
     thr->errhv = newHV();
     thr->flags = THRf_R_JOINABLE;
     MUTEX_INIT(&thr->mutex);
diff --git a/win32/dl_win32.xs b/win32/dl_win32.xs
index c650acffb7..3473520372 100644
--- a/win32/dl_win32.xs
+++ b/win32/dl_win32.xs
@@ -42,7 +42,7 @@ OS_Error_String(CPERLarg)
  DWORD err = GetLastError();
  STRLEN len;
  if (!error_sv)
-  error_sv = newSVpv("",0);
+  error_sv = newSVpvn("",0);
  win32_str_os_error(error_sv,err);
  return SvPV(error_sv,len);
 }
diff --git a/win32/win32.c b/win32/win32.c
index 5d2bdaa5f1..480dfeb987 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -2573,7 +2573,7 @@ XS(w32_LoginName)
     EXTEND(SP,1);
     if (GetUserName(name,&size)) {
 	/* size includes NULL */
-	ST(0) = sv_2mortal(newSVpv(name,size-1));
+	ST(0) = sv_2mortal(newSVpvn(name,size-1));
 	XSRETURN(1);
     }
     XSRETURN_UNDEF;
@@ -2588,7 +2588,7 @@ XS(w32_NodeName)
     EXTEND(SP,1);
     if (GetComputerName(name,&size)) {
 	/* size does NOT include NULL :-( */
-	ST(0) = sv_2mortal(newSVpv(name,size));
+	ST(0) = sv_2mortal(newSVpvn(name,size));
 	XSRETURN(1);
     }
     XSRETURN_UNDEF;
@@ -2648,7 +2648,7 @@ XS(w32_FsType)
     if (GetVolumeInformation(NULL, NULL, 0, NULL, &filecomplen,
 			 &flags, fsname, sizeof(fsname))) {
 	if (GIMME_V == G_ARRAY) {
-	    XPUSHs(sv_2mortal(newSVpv(fsname,0)));
+	    XPUSHs(sv_2mortal(newSVpvn(fsname,strlen(fsname))));
 	    XPUSHs(sv_2mortal(newSViv(flags)));
 	    XPUSHs(sv_2mortal(newSViv(filecomplen)));
 	    PUTBACK;
@@ -2668,7 +2668,7 @@ XS(w32_GetOSVersion)
 
     osver.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
     if (GetVersionEx(&osver)) {
-	XPUSHs(newSVpv(osver.szCSDVersion, 0));
+	XPUSHs(newSVpvn(osver.szCSDVersion, strlen(osver.szCSDVersion)));
 	XPUSHs(newSViv(osver.dwMajorVersion));
 	XPUSHs(newSViv(osver.dwMinorVersion));
 	XPUSHs(newSViv(osver.dwBuildNumber));