X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/a0288114f9bfa2566e353eba77114ea63b616631..1a5b3db469280dd5cf664d996d7209b0219449ef:/gv.c?ds=sidebyside

diff --git a/gv.c b/gv.c
index f1fe784..555260f 100644
--- a/gv.c
+++ b/gv.c
@@ -1,7 +1,7 @@
 /*    gv.c
  *
  *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
- *    2000, 2001, 2002, 2003, 2004, 2005, by Larry Wall and others
+ *    2000, 2001, 2002, 2003, 2004, 2005, 2006, 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.
@@ -37,6 +37,19 @@ Perl stores its global variables.
 static const char S_autoload[] = "AUTOLOAD";
 static const STRLEN S_autolen = sizeof(S_autoload)-1;
 
+
+#ifdef PERL_DONT_CREATE_GVSV
+GV *
+Perl_gv_SVadd(pTHX_ GV *gv)
+{
+    if (!gv || SvTYPE((SV*)gv) != SVt_PVGV)
+	Perl_croak(aTHX_ "Bad symbol for scalar");
+    if (!GvSV(gv))
+	GvSV(gv) = newSV(0);
+    return gv;
+}
+#endif
+
 GV *
 Perl_gv_AVadd(pTHX_ register GV *gv)
 {
@@ -60,8 +73,22 @@ Perl_gv_HVadd(pTHX_ register GV *gv)
 GV *
 Perl_gv_IOadd(pTHX_ register GV *gv)
 {
-    if (!gv || SvTYPE((SV*)gv) != SVt_PVGV)
-	Perl_croak(aTHX_ "Bad symbol for filehandle");
+    dVAR;
+    if (!gv || SvTYPE((SV*)gv) != SVt_PVGV) {
+
+        /*
+         * if it walks like a dirhandle, then let's assume that
+         * this is a dirhandle.
+         */
+        const char *fh = PL_op->op_type == OP_READDIR ||
+                         PL_op->op_type ==  OP_TELLDIR ||
+                         PL_op->op_type ==  OP_SEEKDIR ||
+                         PL_op->op_type ==  OP_REWINDDIR ||
+                         PL_op->op_type ==  OP_CLOSEDIR ?
+                         "dirhandle" : "filehandle";
+        Perl_croak(aTHX_ "Bad symbol for %s", fh);
+    }
+
     if (!GvIOp(gv)) {
 #ifdef GV_UNIQUE_CHECK
         if (GvUNIQUE(gv)) {
@@ -76,35 +103,59 @@ Perl_gv_IOadd(pTHX_ register GV *gv)
 GV *
 Perl_gv_fetchfile(pTHX_ const char *name)
 {
+    dVAR;
     char smallbuf[256];
     char *tmpbuf;
     STRLEN tmplen;
     GV *gv;
 
     if (!PL_defstash)
-	return Nullgv;
+	return NULL;
 
     tmplen = strlen(name) + 2;
     if (tmplen < sizeof smallbuf)
 	tmpbuf = smallbuf;
     else
-	New(603, tmpbuf, tmplen + 1, char);
+	Newx(tmpbuf, tmplen + 1, char);
     /* This is where the debugger's %{"::_<$filename"} hash is created */
     tmpbuf[0] = '_';
     tmpbuf[1] = '<';
-    strcpy(tmpbuf + 2, name);
+    memcpy(tmpbuf + 2, name, tmplen - 1);
     gv = *(GV**)hv_fetch(PL_defstash, tmpbuf, tmplen, TRUE);
     if (!isGV(gv)) {
 	gv_init(gv, PL_defstash, tmpbuf, tmplen, FALSE);
-	sv_setpv(GvSV(gv), name);
+#ifdef PERL_DONT_CREATE_GVSV
+	GvSV(gv) = newSVpvn(name, tmplen - 2);
+#else
+	sv_setpvn(GvSV(gv), name, tmplen - 2);
+#endif
 	if (PERLDB_LINE)
-	    hv_magic(GvHVn(gv_AVadd(gv)), Nullgv, PERL_MAGIC_dbfile);
+	    hv_magic(GvHVn(gv_AVadd(gv)), NULL, PERL_MAGIC_dbfile);
     }
     if (tmpbuf != smallbuf)
 	Safefree(tmpbuf);
     return gv;
 }
 
+/*
+=for apidoc gv_const_sv
+
+If C<gv> is a typeglob whose subroutine entry is a constant sub eligible for
+inlining, or C<gv> is a placeholder reference that would be promoted to such
+a typeglob, then returns the value returned by the sub.  Otherwise, returns
+NULL.
+
+=cut
+*/
+
+SV *
+Perl_gv_const_sv(pTHX_ GV *gv)
+{
+    if (SvTYPE(gv) == SVt_PVGV)
+	return cv_const_sv(GvCVu(gv));
+    return SvROK(gv) ? SvRV(gv) : NULL;
+}
+
 void
 Perl_gv_init(pTHX_ GV *gv, HV *stash, const char *name, STRLEN len, int multi)
 {
@@ -112,6 +163,24 @@ Perl_gv_init(pTHX_ GV *gv, HV *stash, const char *name, STRLEN len, int multi)
     register GP *gp;
     const bool doproto = SvTYPE(gv) > SVt_NULL;
     const char * const proto = (doproto && SvPOK(gv)) ? SvPVX_const(gv) : NULL;
+    SV *const has_constant = doproto && SvROK(gv) ? SvRV(gv) : NULL;
+
+    assert (!(proto && has_constant));
+
+    if (has_constant) {
+	/* The constant has to be a simple scalar type.  */
+	switch (SvTYPE(has_constant)) {
+	case SVt_PVAV:
+	case SVt_PVHV:
+	case SVt_PVCV:
+	case SVt_PVFM:
+	case SVt_PVIO:
+            Perl_croak(aTHX_ "Cannot convert a reference to %s to typeglob",
+		       sv_reftype(has_constant, 0));
+	}
+	SvRV_set(gv, NULL);
+	SvROK_off(gv);
+    }
 
     sv_upgrade((SV*)gv, SVt_PVGV);
     if (SvLEN(gv)) {
@@ -120,19 +189,25 @@ Perl_gv_init(pTHX_ GV *gv, HV *stash, const char *name, STRLEN len, int multi)
 	    SvLEN_set(gv, 0);
 	    SvPOK_off(gv);
 	} else
-	    Safefree(SvPVX_const(gv));
+	    Safefree(SvPVX_mutable(gv));
     }
-    Newz(602, gp, 1, GP);
+    Newxz(gp, 1, GP);
     GvGP(gv) = gp_ref(gp);
-    GvSV(gv) = NEWSV(72,0);
+#ifdef PERL_DONT_CREATE_GVSV
+    GvSV(gv) = NULL;
+#else
+    GvSV(gv) = newSV(0);
+#endif
     GvLINE(gv) = CopLINE(PL_curcop);
     /* XXX Ideally this cast would be replaced with a change to const char*
        in the struct.  */
     GvFILE(gv) = CopFILE(PL_curcop) ? CopFILE(PL_curcop) : (char *) "";
     GvCVGEN(gv) = 0;
     GvEGV(gv) = gv;
-    sv_magic((SV*)gv, (SV*)gv, PERL_MAGIC_glob, Nullch, 0);
-    GvSTASH(gv) = (HV*)SvREFCNT_inc(stash);
+    sv_magic((SV*)gv, (SV*)gv, PERL_MAGIC_glob, NULL, 0);
+    GvSTASH(gv) = stash;
+    if (stash)
+	Perl_sv_add_backref(aTHX_ (SV*)stash, (SV*)gv);
     GvNAME(gv) = savepvn(name, len);
     GvNAMELEN(gv) = len;
     if (multi || doproto)              /* doproto means it _was_ mentioned */
@@ -140,9 +215,14 @@ Perl_gv_init(pTHX_ GV *gv, HV *stash, const char *name, STRLEN len, int multi)
     if (doproto) {			/* Replicate part of newSUB here. */
 	SvIOK_off(gv);
 	ENTER;
-	/* XXX unsafe for threads if eval_owner isn't held */
-	start_subparse(0,0);		/* Create CV in compcv. */
-	GvCV(gv) = PL_compcv;
+	if (has_constant) {
+	    /* newCONSTSUB takes ownership of the reference from us.  */
+	    GvCV(gv) = newCONSTSUB(stash, name, has_constant);
+	} else {
+	    /* XXX unsafe for threads if eval_owner isn't held */
+	    (void) start_subparse(0,0);	/* Create empty CV in compcv. */
+	    GvCV(gv) = PL_compcv;
+	}
 	LEAVE;
 
 	PL_sub_generation++;
@@ -169,6 +249,15 @@ S_gv_init_sv(pTHX_ GV *gv, I32 sv_type)
     case SVt_PVHV:
 	(void)GvHVn(gv);
 	break;
+#ifdef PERL_DONT_CREATE_GVSV
+    case SVt_NULL:
+    case SVt_PVCV:
+    case SVt_PVFM:
+    case SVt_PVGV:
+	break;
+    default:
+	(void)GvSVn(gv);
+#endif
     }
 }
 
@@ -196,6 +285,7 @@ obtained from the GV with the C<GvCV> macro.
 GV *
 Perl_gv_fetchmeth(pTHX_ HV *stash, const char *name, STRLEN len, I32 level)
 {
+    dVAR;
     AV* av;
     GV* topgv;
     GV* gv;
@@ -206,7 +296,7 @@ Perl_gv_fetchmeth(pTHX_ HV *stash, const char *name, STRLEN len, I32 level)
     /* UNIVERSAL methods should be callable without a stash */
     if (!stash) {
 	level = -1;  /* probably appropriate */
-	if(!(stash = gv_stashpvn("UNIVERSAL", 9, FALSE)))
+	if(!(stash = gv_stashpvs("UNIVERSAL", FALSE)))
 	    return 0;
     }
 
@@ -223,7 +313,7 @@ Perl_gv_fetchmeth(pTHX_ HV *stash, const char *name, STRLEN len, I32 level)
 
     gvp = (GV**)hv_fetch(stash, name, len, (level >= 0));
     if (!gvp)
-	topgv = Nullgv;
+	topgv = NULL;
     else {
 	topgv = *gvp;
 	if (SvTYPE(topgv) != SVt_PVGV)
@@ -234,15 +324,15 @@ Perl_gv_fetchmeth(pTHX_ HV *stash, const char *name, STRLEN len, I32 level)
 		return topgv;
 	    /* Stale cached entry: junk it */
 	    SvREFCNT_dec(cv);
-	    GvCV(topgv) = cv = Nullcv;
+	    GvCV(topgv) = cv = NULL;
 	    GvCVGEN(topgv) = 0;
 	}
 	else if (GvCVGEN(topgv) == PL_sub_generation)
 	    return 0;  /* cache indicates sub doesn't exist */
     }
 
-    gvp = (GV**)hv_fetch(stash, "ISA", 3, FALSE);
-    av = (gvp && (gv = *gvp) && gv != (GV*)&PL_sv_undef) ? GvAV(gv) : Nullav;
+    gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
+    av = (gvp && (gv = *gvp) && gv != (GV*)&PL_sv_undef) ? GvAV(gv) : NULL;
 
     /* create and re-create @.*::SUPER::ISA on demand */
     if (!av || !SvMAGIC(av)) {
@@ -253,9 +343,9 @@ Perl_gv_fetchmeth(pTHX_ HV *stash, const char *name, STRLEN len, I32 level)
 
 	    packlen -= 7;
 	    basestash = gv_stashpvn(hvname, packlen, TRUE);
-	    gvp = (GV**)hv_fetch(basestash, "ISA", 3, FALSE);
+	    gvp = (GV**)hv_fetchs(basestash, "ISA", FALSE);
 	    if (gvp && (gv = *gvp) != (GV*)&PL_sv_undef && (av = GvAV(gv))) {
-		gvp = (GV**)hv_fetch(stash, "ISA", 3, TRUE);
+		gvp = (GV**)hv_fetchs(stash, "ISA", TRUE);
 		if (!gvp || !(gv = *gvp))
 		    Perl_croak(aTHX_ "Cannot create %s::ISA", hvname);
 		if (SvTYPE(gv) != SVt_PVGV)
@@ -271,8 +361,8 @@ Perl_gv_fetchmeth(pTHX_ HV *stash, const char *name, STRLEN len, I32 level)
 	/* NOTE: No support for tied ISA */
 	I32 items = AvFILLp(av) + 1;
 	while (items--) {
-	    SV* sv = *svp++;
-	    HV* basestash = gv_stashsv(sv, FALSE);
+	    SV* const sv = *svp++;
+	    HV* const basestash = gv_stashsv(sv, FALSE);
 	    if (!basestash) {
 		if (ckWARN(WARN_MISC))
 		    Perl_warner(aTHX_ packWARN(WARN_MISC), "Can't locate package %"SVf" for @%s::ISA",
@@ -289,9 +379,9 @@ Perl_gv_fetchmeth(pTHX_ HV *stash, const char *name, STRLEN len, I32 level)
     /* if at top level, try UNIVERSAL */
 
     if (level == 0 || level == -1) {
-	HV* lastchance;
+	HV* const lastchance = gv_stashpvs("UNIVERSAL", FALSE);
 
-	if ((lastchance = gv_stashpvn("UNIVERSAL", 9, FALSE))) {
+	if (lastchance) {
 	    if ((gv = gv_fetchmeth(lastchance, name, len,
 				  (level >= 0) ? level + 1 : level - 1)))
 	    {
@@ -346,40 +436,26 @@ Perl_gv_fetchmeth_autoload(pTHX_ HV *stash, const char *name, STRLEN len, I32 le
 	GV **gvp;
 
 	if (!stash)
-	    return Nullgv;	/* UNIVERSAL::AUTOLOAD could cause trouble */
+	    return NULL;	/* UNIVERSAL::AUTOLOAD could cause trouble */
 	if (len == S_autolen && strnEQ(name, S_autoload, S_autolen))
-	    return Nullgv;
+	    return NULL;
 	if (!(gv = gv_fetchmeth(stash, S_autoload, S_autolen, FALSE)))
-	    return Nullgv;
+	    return NULL;
 	cv = GvCV(gv);
 	if (!(CvROOT(cv) || CvXSUB(cv)))
-	    return Nullgv;
+	    return NULL;
 	/* Have an autoload */
 	if (level < 0)	/* Cannot do without a stub */
 	    gv_fetchmeth(stash, name, len, 0);
 	gvp = (GV**)hv_fetch(stash, name, len, (level >= 0));
 	if (!gvp)
-	    return Nullgv;
+	    return NULL;
 	return *gvp;
     }
     return gv;
 }
 
 /*
-=for apidoc gv_fetchmethod
-
-See L<gv_fetchmethod_autoload>.
-
-=cut
-*/
-
-GV *
-Perl_gv_fetchmethod(pTHX_ HV *stash, const char *name)
-{
-    return gv_fetchmethod_autoload(stash, name, TRUE);
-}
-
-/*
 =for apidoc gv_fetchmethod_autoload
 
 Returns the glob which contains the subroutine to call to invoke the method
@@ -410,13 +486,14 @@ C<call_sv> apply equally to these functions.
 GV *
 Perl_gv_fetchmethod_autoload(pTHX_ HV *stash, const char *name, I32 autoload)
 {
+    dVAR;
     register const char *nend;
-    const char *nsplit = 0;
+    const char *nsplit = NULL;
     GV* gv;
     HV* ostash = stash;
 
     if (stash && SvTYPE(stash) < SVt_PVHV)
-	stash = Nullhv;
+	stash = NULL;
 
     for (nend = name; *nend; nend++) {
 	if (*nend == '\'')
@@ -425,7 +502,7 @@ Perl_gv_fetchmethod_autoload(pTHX_ HV *stash, const char *name, I32 autoload)
 	    nsplit = ++nend;
     }
     if (nsplit) {
-	const char *origname = name;
+	const char * const origname = name;
 	name = nsplit + 1;
 	if (*nsplit == ':')
 	    --nsplit;
@@ -460,7 +537,7 @@ Perl_gv_fetchmethod_autoload(pTHX_ HV *stash, const char *name, I32 autoload)
 	    gv = gv_autoload4(ostash, name, nend - name, TRUE);
     }
     else if (autoload) {
-	CV* cv = GvCV(gv);
+	CV* const cv = GvCV(gv);
 	if (!CvROOT(cv) && !CvXSUB(cv)) {
 	    GV* stubgv;
 	    GV* autogv;
@@ -495,11 +572,11 @@ Perl_gv_autoload4(pTHX_ HV *stash, const char *name, STRLEN len, I32 method)
     STRLEN packname_len;
 
     if (len == S_autolen && strnEQ(name, S_autoload, S_autolen))
-	return Nullgv;
+	return NULL;
     if (stash) {
 	if (SvTYPE(stash) < SVt_PVHV) {
-	    packname = SvPV((SV*)stash, packname_len);
-	    stash = Nullhv;
+	    packname = SvPV_const((SV*)stash, packname_len);
+	    stash = NULL;
 	}
 	else {
 	    packname = HvNAME_get(stash);
@@ -507,17 +584,18 @@ Perl_gv_autoload4(pTHX_ HV *stash, const char *name, STRLEN len, I32 method)
 	}
     }
     if (!(gv = gv_fetchmeth(stash, S_autoload, S_autolen, FALSE)))
-	return Nullgv;
+	return NULL;
     cv = GvCV(gv);
 
     if (!(CvROOT(cv) || CvXSUB(cv)))
-	return Nullgv;
+	return NULL;
 
     /*
      * Inheriting AUTOLOAD for non-methods works ... for now.
      */
-    if (ckWARN2(WARN_DEPRECATED, WARN_SYNTAX) && !method &&
-	(GvCVGEN(gv) || GvSTASH(gv) != stash))
+    if (!method && (GvCVGEN(gv) || GvSTASH(gv) != stash)
+	&& ckWARN2(WARN_DEPRECATED, WARN_SYNTAX)
+    )
 	Perl_warner(aTHX_ packWARN2(WARN_DEPRECATED, WARN_SYNTAX),
 	  "Use of inherited AUTOLOAD for non-method %s::%.*s() is deprecated",
 	     packname, (int)len, name);
@@ -544,12 +622,16 @@ Perl_gv_autoload4(pTHX_ HV *stash, const char *name, STRLEN len, I32 method)
     vargv = *(GV**)hv_fetch(varstash, S_autoload, S_autolen, TRUE);
     ENTER;
 
-    if (!isGV(vargv))
+    if (!isGV(vargv)) {
 	gv_init(vargv, varstash, S_autoload, S_autolen, FALSE);
+#ifdef PERL_DONT_CREATE_GVSV
+	GvSV(vargv) = newSV(0);
+#endif
+    }
     LEAVE;
-    varsv = GvSV(vargv);
+    varsv = GvSVn(vargv);
     sv_setpvn(varsv, packname, packname_len);
-    sv_catpvn(varsv, "::", 2);
+    sv_catpvs(varsv, "::");
     sv_catpvn(varsv, name, len);
     SvTAINTED_off(varsv);
     return gv;
@@ -562,7 +644,7 @@ STATIC void
 S_require_errno(pTHX_ GV *gv)
 {
     dVAR;
-    HV* stash = gv_stashpvn("Errno",5,FALSE);
+    HV* stash = gv_stashpvs("Errno", FALSE);
 
     if (!stash || !(gv_fetchmethod(stash, "TIEHASH"))) {
 	dSP;
@@ -570,10 +652,10 @@ S_require_errno(pTHX_ GV *gv)
 	ENTER;
 	save_scalar(gv); /* keep the value of $! */
         Perl_load_module(aTHX_ PERL_LOADMOD_NOIMPORT,
-                         newSVpvn("Errno",5), Nullsv);
+                         newSVpvs("Errno"), NULL);
 	LEAVE;
 	SPAGAIN;
-	stash = gv_stashpvn("Errno",5,FALSE);
+	stash = gv_stashpvs("Errno", FALSE);
 	if (!stash || !(gv_fetchmethod(stash, "TIEHASH")))
 	    Perl_croak(aTHX_ "Can't use %%! because Errno.pm is not available");
     }
@@ -611,7 +693,7 @@ package does not exist then NULL is returned.
 HV*
 Perl_gv_stashpvn(pTHX_ const char *name, U32 namelen, I32 create)
 {
-    char smallbuf[256];
+    char smallbuf[128];
     char *tmpbuf;
     HV *stash;
     GV *tmpgv;
@@ -619,12 +701,12 @@ Perl_gv_stashpvn(pTHX_ const char *name, U32 namelen, I32 create)
     if (namelen + 3 < sizeof smallbuf)
 	tmpbuf = smallbuf;
     else
-	New(606, tmpbuf, namelen + 3, char);
+	Newx(tmpbuf, namelen + 3, char);
     Copy(name,tmpbuf,namelen,char);
     tmpbuf[namelen++] = ':';
     tmpbuf[namelen++] = ':';
     tmpbuf[namelen] = '\0';
-    tmpgv = gv_fetchpv(tmpbuf, create, SVt_PVHV);
+    tmpgv = gv_fetchpvn_flags(tmpbuf, namelen, create, SVt_PVHV);
     if (tmpbuf != smallbuf)
 	Safefree(tmpbuf);
     if (!tmpgv)
@@ -633,7 +715,7 @@ Perl_gv_stashpvn(pTHX_ const char *name, U32 namelen, I32 create)
 	GvHV(tmpgv) = newHV();
     stash = GvHV(tmpgv);
     if (!HvNAME_get(stash))
-	Perl_hv_name_set(aTHX_ stash, name, namelen, 0);
+	hv_name_set(stash, name, namelen, 0);
     return stash;
 }
 
@@ -650,7 +732,7 @@ HV*
 Perl_gv_stashsv(pTHX_ SV *sv, I32 create)
 {
     STRLEN len;
-    const char *ptr = SvPV(sv,len);
+    const char * const ptr = SvPV_const(sv,len);
     return gv_stashpvn(ptr, len, create);
 }
 
@@ -663,7 +745,7 @@ Perl_gv_fetchpv(pTHX_ const char *nambeg, I32 add, I32 sv_type) {
 GV *
 Perl_gv_fetchsv(pTHX_ SV *name, I32 flags, I32 sv_type) {
     STRLEN len;
-    const char *nambeg = SvPV(name, len);
+    const char * const nambeg = SvPV_const(name, len);
     return gv_fetchpvn_flags(nambeg, len, flags | SvUTF8(name), sv_type);
 }
 
@@ -671,42 +753,56 @@ GV *
 Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 		       I32 sv_type)
 {
+    dVAR;
     register const char *name = nambeg;
-    register GV *gv = 0;
+    register GV *gv = NULL;
     GV**gvp;
     I32 len;
-    register const char *namend;
-    HV *stash = 0;
-    const I32 add = flags & ~SVf_UTF8;
-    (void)full_len;
+    register const char *name_cursor;
+    HV *stash = NULL;
+    const I32 no_init = flags & (GV_NOADD_NOINIT | GV_NOINIT);
+    const I32 no_expand = flags & GV_NOEXPAND;
+    const I32 add =
+	flags & ~SVf_UTF8 & ~GV_NOADD_NOINIT & ~GV_NOEXPAND & ~GV_NOTQUAL;
+    const char *const name_end = nambeg + full_len;
+    const char *const name_em1 = name_end - 1;
+
+    if (flags & GV_NOTQUAL) {
+	/* Caller promised that there is no stash, so we can skip the check. */
+	len = full_len;
+	goto no_stash;
+    }
 
-    if (*name == '*' && isALPHA(name[1])) /* accidental stringify on a GV? */
+    if (full_len > 2 && *name == '*' && isALPHA(name[1])) {
+	/* accidental stringify on a GV? */
 	name++;
+    }
 
-    for (namend = name; *namend; namend++) {
-	if ((*namend == ':' && namend[1] == ':')
-	    || (*namend == '\'' && namend[1]))
+    for (name_cursor = name; name_cursor < name_end; name_cursor++) {
+	if ((*name_cursor == ':' && name_cursor < name_em1
+	     && name_cursor[1] == ':')
+	    || (*name_cursor == '\'' && name_cursor[1]))
 	{
 	    if (!stash)
 		stash = PL_defstash;
 	    if (!stash || !SvREFCNT(stash)) /* symbol table under destruction */
-		return Nullgv;
+		return NULL;
 
-	    len = namend - name;
+	    len = name_cursor - name;
 	    if (len > 0) {
-		char smallbuf[256];
+		char smallbuf[128];
 		char *tmpbuf;
 
 		if (len + 3 < sizeof (smallbuf))
 		    tmpbuf = smallbuf;
 		else
-		    New(601, tmpbuf, len+3, char);
+		    Newx(tmpbuf, len+3, char);
 		Copy(name, tmpbuf, len, char);
 		tmpbuf[len++] = ':';
 		tmpbuf[len++] = ':';
 		tmpbuf[len] = '\0';
 		gvp = (GV**)hv_fetch(stash,tmpbuf,len,add);
-		gv = gvp ? *gvp : Nullgv;
+		gv = gvp ? *gvp : NULL;
 		if (gv && gv != (GV*)&PL_sv_undef) {
 		    if (SvTYPE(gv) != SVt_PVGV)
 			gv_init(gv, stash, tmpbuf, len, (add & GV_ADDMULTI));
@@ -716,53 +812,63 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 		if (tmpbuf != smallbuf)
 		    Safefree(tmpbuf);
 		if (!gv || gv == (GV*)&PL_sv_undef)
-		    return Nullgv;
+		    return NULL;
 
 		if (!(stash = GvHV(gv)))
 		    stash = GvHV(gv) = newHV();
 
 		if (!HvNAME_get(stash))
-		    Perl_hv_name_set(aTHX_ stash, nambeg, namend - nambeg, 0);
+		    hv_name_set(stash, nambeg, name_cursor - nambeg, 0);
 	    }
 
-	    if (*namend == ':')
-		namend++;
-	    namend++;
-	    name = namend;
-	    if (!*name)
-		return gv ? gv : (GV*)*hv_fetch(PL_defstash, "main::", 6, TRUE);
+	    if (*name_cursor == ':')
+		name_cursor++;
+	    name_cursor++;
+	    name = name_cursor;
+	    if (name == name_end)
+		return gv ? gv : (GV*)*hv_fetchs(PL_defstash, "main::", TRUE);
 	}
     }
-    len = namend - name;
+    len = name_cursor - name;
 
     /* No stash in name, so see how we can default */
 
     if (!stash) {
-	if (isIDFIRST_lazy(name)) {
+    no_stash:
+	if (len && isIDFIRST_lazy(name)) {
 	    bool global = FALSE;
 
-	    /* name is always \0 terminated, and initial \0 wouldn't return
-	       true from isIDFIRST_lazy, so we know that name[1] is defined  */
-	    switch (name[1]) {
-	    case '\0':
+	    switch (len) {
+	    case 1:
 		if (*name == '_')
 		    global = TRUE;
 		break;
-	    case 'N':
-		if (strEQ(name, "INC") || strEQ(name, "ENV"))
+	    case 3:
+		if ((name[0] == 'I' && name[1] == 'N' && name[2] == 'C')
+		    || (name[0] == 'E' && name[1] == 'N' && name[2] == 'V')
+		    || (name[0] == 'S' && name[1] == 'I' && name[2] == 'G'))
 		    global = TRUE;
 		break;
-	    case 'I':
-		if (strEQ(name, "SIG"))
+	    case 4:
+		if (name[0] == 'A' && name[1] == 'R' && name[2] == 'G'
+		    && name[3] == 'V')
 		    global = TRUE;
 		break;
-	    case 'T':
-		if (strEQ(name, "STDIN") || strEQ(name, "STDOUT") ||
-		    strEQ(name, "STDERR"))
+	    case 5:
+		if (name[0] == 'S' && name[1] == 'T' && name[2] == 'D'
+		    && name[3] == 'I' && name[4] == 'N')
 		    global = TRUE;
 		break;
-	    case 'R':
-		if (strEQ(name, "ARGV") || strEQ(name, "ARGVOUT"))
+	    case 6:
+		if ((name[0] == 'S' && name[1] == 'T' && name[2] == 'D')
+		    &&((name[3] == 'O' && name[4] == 'U' && name[5] == 'T')
+		       ||(name[3] == 'E' && name[4] == 'R' && name[5] == 'R')))
+		    global = TRUE;
+		break;
+	    case 7:
+		if (name[0] == 'A' && name[1] == 'R' && name[2] == 'G'
+		    && name[3] == 'V' && name[4] == 'O' && name[5] == 'U'
+		    && name[6] == 'T')
 		    global = TRUE;
 		break;
 	    }
@@ -811,7 +917,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 
     if (!stash) {
 	if (add) {
-	    register SV *err = Perl_mess(aTHX_
+	    SV * const err = Perl_mess(aTHX_
 		 "Global symbol \"%s%s\" requires explicit package name",
 		 (sv_type == SVt_PV ? "$"
 		  : sv_type == SVt_PVAV ? "@"
@@ -820,18 +926,18 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	    if (USE_UTF8_IN_NAMES)
 		SvUTF8_on(err);
 	    qerror(err);
-	    stash = GvHV(gv_fetchpv("<none>::", GV_ADDMULTI, SVt_PVHV));
+	    stash = GvHV(gv_fetchpvn_flags("<none>::", 8, GV_ADDMULTI, SVt_PVHV));
 	}
 	else
-	    return Nullgv;
+	    return NULL;
     }
 
     if (!SvREFCNT(stash))	/* symbol table under destruction */
-	return Nullgv;
+	return NULL;
 
     gvp = (GV**)hv_fetch(stash,name,len,add);
     if (!gvp || *gvp == (GV*)&PL_sv_undef)
-	return Nullgv;
+	return NULL;
     gv = *gvp;
     if (SvTYPE(gv) == SVt_PVGV) {
 	if (add) {
@@ -841,7 +947,9 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 		require_errno(gv);
 	}
 	return gv;
-    } else if (add & GV_NOINIT) {
+    } else if (no_init) {
+	return gv;
+    } else if (no_expand && SvROK(gv)) {
 	return gv;
     }
 
@@ -860,6 +968,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
     if (len > 1) {
 #ifndef EBCDIC
 	if (*name > 'V' ) {
+	    /*EMPTY*/;
 	    /* Nothing else to do.
 	       The compiler will probably turn the switch statement into a
 	       branch table. Make sure we avoid even that small overhead for
@@ -867,7 +976,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	} else
 #endif
 	{
-	    const char *name2 = name + 1;
+	    const char * const name2 = name + 1;
 	    switch (*name) {
 	    case 'A':
 		if (strEQ(name2, "RGV")) {
@@ -880,9 +989,9 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 		break;
 	    case 'I':
 		if (strEQ(name2, "SA")) {
-		    AV* av = GvAVn(gv);
+		    AV* const av = GvAVn(gv);
 		    GvMULTI_on(gv);
-		    sv_magic((SV*)av, (SV*)gv, PERL_MAGIC_isa, Nullch, 0);
+		    sv_magic((SV*)av, (SV*)gv, PERL_MAGIC_isa, NULL, 0);
 		    /* NOTE: No support for tied ISA */
 		    if ((add & GV_ADDMULTI) && strEQ(nambeg,"AnyDBM_File::ISA")
 			&& AvFILLp(av) == -1)
@@ -903,9 +1012,9 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 		break;
 	    case 'O':
 		if (strEQ(name2, "VERLOAD")) {
-		    HV* hv = GvHVn(gv);
+		    HV* const hv = GvHVn(gv);
 		    GvMULTI_on(gv);
-		    hv_magic(hv, Nullgv, PERL_MAGIC_overload);
+		    hv_magic(hv, NULL, PERL_MAGIC_overload);
 		}
 		break;
 	    case 'S':
@@ -913,16 +1022,15 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 		    HV *hv;
 		    I32 i;
 		    if (!PL_psig_ptr) {
-			Newz(73, PL_psig_ptr,  SIG_SIZE, SV*);
-			Newz(73, PL_psig_name, SIG_SIZE, SV*);
-			Newz(73, PL_psig_pend, SIG_SIZE, int);
+			Newxz(PL_psig_ptr,  SIG_SIZE, SV*);
+			Newxz(PL_psig_name, SIG_SIZE, SV*);
+			Newxz(PL_psig_pend, SIG_SIZE, int);
 		    }
 		    GvMULTI_on(gv);
 		    hv = GvHVn(gv);
-		    hv_magic(hv, Nullgv, PERL_MAGIC_sig);
+		    hv_magic(hv, NULL, PERL_MAGIC_sig);
 		    for (i = 1; i < SIG_SIZE; i++) {
-			SV ** init;
-			init = hv_fetch(hv, PL_sig_name[i], strlen(PL_sig_name[i]), 1);
+			SV * const * const init = hv_fetch(hv, PL_sig_name[i], strlen(PL_sig_name[i]), 1);
 			if (init)
 			    sv_setsv(*init, &PL_sv_undef);
 			PL_psig_ptr[i] = 0;
@@ -1000,12 +1108,12 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	    goto ro_magicalize;
 
 	case ':':
-	    sv_setpv(GvSV(gv),PL_chopset);
+	    sv_setpv(GvSVn(gv),PL_chopset);
 	    goto magicalize;
 
 	case '?':
 #ifdef COMPLEX_STATUS
-	    (void)SvUPGRADE(GvSV(gv), SVt_PVLV);
+	    SvUPGRADE(GvSVn(gv), SVt_PVLV);
 #endif
 	    goto magicalize;
 
@@ -1017,7 +1125,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	       now (rather than going to magicalize)
 	    */
 
-	    sv_magic(GvSV(gv), (SV*)gv, PERL_MAGIC_sv, name, len);
+	    sv_magic(GvSVn(gv), (SV*)gv, PERL_MAGIC_sv, name, len);
 
 	    if (sv_type == SVt_PVHV)
 		require_errno(gv);
@@ -1025,29 +1133,25 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	    break;
 	case '-':
 	{
-            AV* av = GvAVn(gv);
-            sv_magic((SV*)av, Nullsv, PERL_MAGIC_regdata, Nullch, 0);
+	    AV* const av = GvAVn(gv);
+            sv_magic((SV*)av, NULL, PERL_MAGIC_regdata, NULL, 0);
 	    SvREADONLY_on(av);
 	    goto magicalize;
 	}
 	case '*':
-	    if (sv_type == SVt_PV && ckWARN2(WARN_DEPRECATED, WARN_SYNTAX))
-		Perl_warner(aTHX_ packWARN2(WARN_DEPRECATED, WARN_SYNTAX),
-			    "$* is no longer supported");
-	    break;
 	case '#':
 	    if (sv_type == SVt_PV && ckWARN2(WARN_DEPRECATED, WARN_SYNTAX))
 		Perl_warner(aTHX_ packWARN2(WARN_DEPRECATED, WARN_SYNTAX),
-			    "Use of $# is deprecated");
-	    goto magicalize;
+			    "$%c is no longer supported", *name);
+	    break;
 	case '|':
-	    sv_setiv(GvSV(gv), (IV)(IoFLAGS(GvIOp(PL_defoutgv)) & IOf_FLUSH) != 0);
+	    sv_setiv(GvSVn(gv), (IV)(IoFLAGS(GvIOp(PL_defoutgv)) & IOf_FLUSH) != 0);
 	    goto magicalize;
 
 	case '+':
 	{
-	    AV* av = GvAVn(gv);
-            sv_magic((SV*)av, (SV*)av, PERL_MAGIC_regdata, Nullch, 0);
+	    AV* const av = GvAVn(gv);
+            sv_magic((SV*)av, (SV*)av, PERL_MAGIC_regdata, NULL, 0);
 	    SvREADONLY_on(av);
 	    /* FALL THROUGH */
 	}
@@ -1062,7 +1166,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	case '8':
 	case '9':
 	ro_magicalize:
-	    SvREADONLY_on(GvSV(gv));
+	    SvREADONLY_on(GvSVn(gv));
 	    /* FALL THROUGH */
 	case '[':
 	case '^':
@@ -1090,21 +1194,21 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	case '\024':	/* $^T */
 	case '\027':	/* $^W */
 	magicalize:
-	    sv_magic(GvSV(gv), (SV*)gv, PERL_MAGIC_sv, name, len);
+	    sv_magic(GvSVn(gv), (SV*)gv, PERL_MAGIC_sv, name, len);
 	    break;
 
 	case '\014':	/* $^L */
-	    sv_setpv(GvSV(gv),"\f");
-	    PL_formfeed = GvSV(gv);
+	    sv_setpvn(GvSVn(gv),"\f",1);
+	    PL_formfeed = GvSVn(gv);
 	    break;
 	case ';':
-	    sv_setpv(GvSV(gv),"\034");
+	    sv_setpvn(GvSVn(gv),"\034",1);
 	    break;
 	case ']':
 	{
-	    SV *sv = GvSV(gv);
+	    SV * const sv = GvSVn(gv);
 	    if (!sv_derived_from(PL_patchlevel, "version"))
-		(void *)upg_version(PL_patchlevel);
+		upg_version(PL_patchlevel);
 	    GvSV(gv) = vnumify(PL_patchlevel);
 	    SvREADONLY_on(GvSV(gv));
 	    SvREFCNT_dec(sv);
@@ -1112,7 +1216,7 @@ Perl_gv_fetchpvn_flags(pTHX_ const char *nambeg, STRLEN full_len, I32 flags,
 	break;
 	case '\026':	/* $^V */
 	{
-	    SV * const sv = GvSV(gv);
+	    SV * const sv = GvSVn(gv);
 	    GvSV(gv) = new_version(PL_patchlevel);
 	    SvREADONLY_on(GvSV(gv));
 	    SvREFCNT_dec(sv);
@@ -1145,62 +1249,37 @@ Perl_gv_fullname4(pTHX_ SV *sv, const GV *gv, const char *prefix, bool keepmain)
 
     if (keepmain || strNE(name, "main")) {
 	sv_catpvn(sv,name,namelen);
-	sv_catpvn(sv,"::", 2);
+	sv_catpvs(sv,"::");
     }
     sv_catpvn(sv,GvNAME(gv),GvNAMELEN(gv));
 }
 
 void
-Perl_gv_fullname3(pTHX_ SV *sv, const GV *gv, const char *prefix)
-{
-    gv_fullname4(sv, gv, prefix, TRUE);
-}
-
-void
 Perl_gv_efullname4(pTHX_ SV *sv, const GV *gv, const char *prefix, bool keepmain)
 {
-    const GV *egv = GvEGV(gv);
-    if (!egv)
-	egv = gv;
-    gv_fullname4(sv, egv, prefix, keepmain);
-}
-
-void
-Perl_gv_efullname3(pTHX_ SV *sv, const GV *gv, const char *prefix)
-{
-    gv_efullname4(sv, gv, prefix, TRUE);
-}
-
-/* compatibility with versions <= 5.003. */
-void
-Perl_gv_fullname(pTHX_ SV *sv, const GV *gv)
-{
-    gv_fullname3(sv, gv, sv == (const SV*)gv ? "*" : "");
-}
-
-/* compatibility with versions <= 5.003. */
-void
-Perl_gv_efullname(pTHX_ SV *sv, const GV *gv)
-{
-    gv_efullname3(sv, gv, sv == (const SV*)gv ? "*" : "");
+    const GV * const egv = GvEGV(gv);
+    gv_fullname4(sv, egv ? egv : gv, prefix, keepmain);
 }
 
 IO *
 Perl_newIO(pTHX)
 {
+    dVAR;
     GV *iogv;
-    IO * const io = (IO*)NEWSV(0,0);
+    IO * const io = (IO*)newSV(0);
 
     sv_upgrade((SV *)io,SVt_PVIO);
-    SvREFCNT(io) = 1;
+    /* This used to read SvREFCNT(io) = 1;
+       It's not clear why the reference count needed an explicit reset. NWC
+    */
+    assert (SvREFCNT(io) == 1);
     SvOBJECT_on(io);
-    /* Clear the stashcache because a new IO could overrule a
-       package name */
+    /* Clear the stashcache because a new IO could overrule a package name */
     hv_clear(PL_stashcache);
-    iogv = gv_fetchpv("FileHandle::", FALSE, SVt_PVHV);
+    iogv = gv_fetchpvs("FileHandle::", 0, SVt_PVHV);
     /* unless exists($main::{FileHandle}) and defined(%main::FileHandle::) */
     if (!(iogv && GvHV(iogv) && HvARRAY(GvHV(iogv))))
-      iogv = gv_fetchpv("IO::Handle::", TRUE, SVt_PVHV);
+      iogv = gv_fetchpvs("IO::Handle::", GV_ADD, SVt_PVHV);
     SvSTASH_set(io, (HV*)SvREFCNT_inc(GvHV(iogv)));
     return io;
 }
@@ -1208,6 +1287,7 @@ Perl_newIO(pTHX)
 void
 Perl_gv_check(pTHX_ HV *stash)
 {
+    dVAR;
     register I32 i;
 
     if (!HvARRAY(stash))
@@ -1231,14 +1311,14 @@ Perl_gv_check(pTHX_ HV *stash)
 		file = GvFILE(gv);
 		/* performance hack: if filename is absolute and it's a standard
 		 * module, don't bother warning */
-		if (file
-		    && PERL_FILE_IS_ABSOLUTE(file)
 #ifdef MACOS_TRADITIONAL
-		    && (instr(file, ":lib:")
+#   define LIB_COMPONENT ":lib:"
 #else
-		    && (instr(file, "/lib/")
+#   define LIB_COMPONENT "/lib/"
 #endif
-		    || instr(file, ".pm")))
+		if (file
+		    && PERL_FILE_IS_ABSOLUTE(file)
+		    && (instr(file, LIB_COMPONENT) || instr(file, ".pm")))
 		{
 		    continue;
 		}
@@ -1259,6 +1339,7 @@ Perl_gv_check(pTHX_ HV *stash)
 GV *
 Perl_newGVgen(pTHX_ const char *pack)
 {
+    dVAR;
     return gv_fetchpv(Perl_form(aTHX_ "%s::_GEN_%ld", pack, (long)PL_gensym++),
 		      TRUE, SVt_PVGV);
 }
@@ -1268,6 +1349,7 @@ Perl_newGVgen(pTHX_ const char *pack)
 GP*
 Perl_gp_ref(pTHX_ GP *gp)
 {
+    dVAR;
     if (!gp)
 	return (GP*)NULL;
     gp->gp_refcnt++;
@@ -1275,7 +1357,7 @@ Perl_gp_ref(pTHX_ GP *gp)
 	if (gp->gp_cvgen) {
 	    /* multi-named GPs cannot be used for method cache */
 	    SvREFCNT_dec(gp->gp_cv);
-	    gp->gp_cv = Nullcv;
+	    gp->gp_cv = NULL;
 	    gp->gp_cvgen = 0;
 	}
 	else {
@@ -1289,6 +1371,7 @@ Perl_gp_ref(pTHX_ GP *gp)
 void
 Perl_gp_free(pTHX_ GV *gv)
 {
+    dVAR;
     GP* gp;
 
     if (!gv || !(gp = GvGP(gv)))
@@ -1332,16 +1415,16 @@ Perl_gp_free(pTHX_ GV *gv)
 int
 Perl_magic_freeovrld(pTHX_ SV *sv, MAGIC *mg)
 {
-    AMT *amtp = (AMT*)mg->mg_ptr;
-    (void)sv;
+    AMT * const amtp = (AMT*)mg->mg_ptr;
+    PERL_UNUSED_ARG(sv);
 
     if (amtp && AMT_AMAGIC(amtp)) {
 	int i;
 	for (i = 1; i < NofAMmeth; i++) {
-	    CV *cv = amtp->table[i];
-	    if (cv != Nullcv) {
+	    CV * const cv = amtp->table[i];
+	    if (cv != NULL) {
 		SvREFCNT_dec((SV *) cv);
-		amtp->table[i] = Nullcv;
+		amtp->table[i] = NULL;
 	    }
 	}
     }
@@ -1353,10 +1436,9 @@ Perl_magic_freeovrld(pTHX_ SV *sv, MAGIC *mg)
 bool
 Perl_Gv_AMupdate(pTHX_ HV *stash)
 {
-  GV* gv;
-  CV* cv;
-  MAGIC* mg=mg_find((SV*)stash, PERL_MAGIC_overload_table);
-  AMT *amtp = (mg) ? (AMT*)mg->mg_ptr: (AMT *) NULL;
+  dVAR;
+  MAGIC* const mg = mg_find((SV*)stash, PERL_MAGIC_overload_table);
+  AMT * const amtp = (mg) ? (AMT*)mg->mg_ptr: (AMT *) NULL;
   AMT amt;
 
   if (mg && amtp->was_ok_am == PL_amagic_generation
@@ -1375,28 +1457,32 @@ Perl_Gv_AMupdate(pTHX_ HV *stash)
   {
     int filled = 0, have_ovl = 0;
     int i, lim = 1;
-    SV* sv = NULL;
 
     /* Work with "fallback" key, which we assume to be first in PL_AMG_names */
 
     /* Try to find via inheritance. */
-    gv = gv_fetchmeth(stash, PL_AMG_names[0], 2, -1);
-    if (gv)
-	sv = GvSV(gv);
+    GV *gv = gv_fetchmeth(stash, PL_AMG_names[0], 2, -1);
+    SV * const sv = gv ? GvSV(gv) : NULL;
+    CV* cv;
 
     if (!gv)
 	lim = DESTROY_amg;		/* Skip overloading entries. */
+#ifdef PERL_DONT_CREATE_GVSV
+    else if (!sv) {
+	/*EMPTY*/;   /* Equivalent to !SvTRUE and !SvOK  */
+    }
+#endif
     else if (SvTRUE(sv))
 	amt.fallback=AMGfallYES;
     else if (SvOK(sv))
 	amt.fallback=AMGfallNEVER;
 
     for (i = 1; i < lim; i++)
-	amt.table[i] = Nullcv;
+	amt.table[i] = NULL;
     for (; i < NofAMmeth; i++) {
-	const char *cooky = PL_AMG_names[i];
+	const char * const cooky = PL_AMG_names[i];
 	/* Human-readable form, for debugging: */
-	const char *cp = (i >= DESTROY_amg ? cooky : AMG_id2name(i));
+	const char * const cp = (i >= DESTROY_amg ? cooky : AMG_id2name(i));
 	const STRLEN l = strlen(cooky);
 
 	DEBUG_o( Perl_deb(aTHX_ "Checking overloading of \"%s\" in package \"%.256s\"\n",
@@ -1420,18 +1506,18 @@ Perl_Gv_AMupdate(pTHX_ HV *stash)
 		/* This is a hack to support autoloading..., while
 		   knowing *which* methods were declared as overloaded. */
 		/* GvSV contains the name of the method. */
-		GV *ngv = Nullgv;
+		GV *ngv = NULL;
+		SV *gvsv = GvSV(gv);
 
 		DEBUG_o( Perl_deb(aTHX_ "Resolving method \"%"SVf256\
 			"\" for overloaded \"%s\" in package \"%.256s\"\n",
 			     GvSV(gv), cp, hvname) );
-		if (!SvPOK(GvSV(gv))
-		    || !(ngv = gv_fetchmethod_autoload(stash, SvPVX_const(GvSV(gv)),
+		if (!gvsv || !SvPOK(gvsv)
+		    || !(ngv = gv_fetchmethod_autoload(stash, SvPVX_const(gvsv),
 						       FALSE)))
 		{
 		    /* Can be an import stub (created by "can"). */
-		    SV *gvsv = GvSV(gv);
-		    const char *name = SvPOK(gvsv) ?  SvPVX_const(gvsv) : "???";
+		    const char * const name = (gvsv && SvPOK(gvsv)) ?  SvPVX_const(gvsv) : "???";
 		    Perl_croak(aTHX_ "%s method \"%.256s\" overloading \"%s\" "\
 				"in package \"%.256s\"",
 			       (GvCVGEN(gv) ? "Stub found while resolving"
@@ -1440,8 +1526,7 @@ Perl_Gv_AMupdate(pTHX_ HV *stash)
 		}
 		cv = GvCV(gv = ngv);
 	    }
-	    DEBUG_o( Perl_deb(aTHX_ "Overloading \"%s\" in package \"%.256s\" "\
-	                            "via \"%.256s::%.256s\"\n",
+	    DEBUG_o( Perl_deb(aTHX_ "Overloading \"%s\" in package \"%.256s\" via \"%.256s::%.256s\"\n",
 			 cp, HvNAME_get(stash), HvNAME_get(GvSTASH(CvGV(cv))),
 			 GvNAME(CvGV(cv))) );
 	    filled = 1;
@@ -1474,11 +1559,12 @@ Perl_Gv_AMupdate(pTHX_ HV *stash)
 CV*
 Perl_gv_handler(pTHX_ HV *stash, I32 id)
 {
+    dVAR;
     MAGIC *mg;
     AMT *amtp;
 
     if (!stash || !HvNAME_get(stash))
-        return Nullcv;
+        return NULL;
     mg = mg_find((SV*)stash, PERL_MAGIC_overload_table);
     if (!mg) {
       do_update:
@@ -1496,7 +1582,7 @@ Perl_gv_handler(pTHX_ HV *stash, I32 id)
 	       "Inherited AUTOLOAD for a non-method deprecated", since
 	       our caller is going through a function call, not a method call.
 	       So return the CV for AUTOLOAD, setting $AUTOLOAD. */
-	    GV *gv = gv_fetchmethod(stash, PL_AMG_names[id]);
+	    GV * const gv = gv_fetchmethod(stash, PL_AMG_names[id]);
 
 	    if (gv && GvCV(gv))
 		return GvCV(gv);
@@ -1504,7 +1590,7 @@ Perl_gv_handler(pTHX_ HV *stash, I32 id)
 	return ret;
     }
 
-    return Nullcv;
+    return NULL;
 }
 
 
@@ -1516,8 +1602,10 @@ Perl_amagic_call(pTHX_ SV *left, SV *right, int method, int flags)
   CV *cv=NULL;
   CV **cvp=NULL, **ocvp=NULL;
   AMT *amtp=NULL, *oamtp=NULL;
-  int off=0, off1, lr=0, assign=AMGf_assign & flags, notfound=0;
-  int postpr = 0, force_cpy = 0, assignshift = assign ? 1 : 0;
+  int off = 0, off1, lr = 0, notfound = 0;
+  int postpr = 0, force_cpy = 0;
+  int assign = AMGf_assign & flags;
+  const int assignshift = assign ? 1 : 0;
 #ifdef DEBUGGING
   int fl=0;
 #endif
@@ -1579,13 +1667,13 @@ Perl_amagic_call(pTHX_ SV *left, SV *right, int method, int flags)
 		  * SV* ref causes confusion with the interpreter variable of
 		  * the same name
 		  */
-	     SV* tmpRef=SvRV(left);
+	     SV* const tmpRef=SvRV(left);
 	     if (!SvROK(tmpRef) && SvTYPE(tmpRef) <= SVt_PVMG) {
 		/*
 		 * Just to be extra cautious.  Maybe in some
 		 * additional cases sv_setsv is safe, too.
 		 */
-		SV* newref = newSVsv(tmpRef);
+		SV* const newref = newSVsv(tmpRef);
 		SvOBJECT_on(newref);
 		SvSTASH_set(newref, (HV*)SvREFCNT_inc(SvSTASH(tmpRef)));
 		return newref;
@@ -1595,13 +1683,13 @@ Perl_amagic_call(pTHX_ SV *left, SV *right, int method, int flags)
 	 case abs_amg:
 	   if ((cvp[off1=lt_amg] || cvp[off1=ncmp_amg])
 	       && ((cv = cvp[off=neg_amg]) || (cv = cvp[off=subtr_amg]))) {
-	     SV* nullsv=sv_2mortal(newSViv(0));
+	     SV* const nullsv=sv_2mortal(newSViv(0));
 	     if (off1==lt_amg) {
-	       SV* lessp = amagic_call(left,nullsv,
+	       SV* const lessp = amagic_call(left,nullsv,
 				       lt_amg,AMGf_noright);
 	       logic = SvTRUE(lessp);
 	     } else {
-	       SV* lessp = amagic_call(left,nullsv,
+	       SV* const lessp = amagic_call(left,nullsv,
 				       ncmp_amg,AMGf_noright);
 	       logic = (SvNV(lessp) < 0);
 	     }
@@ -1865,7 +1953,7 @@ bool
 Perl_is_gv_magical_sv(pTHX_ SV *name, U32 flags)
 {
     STRLEN len;
-    const char *temp = SvPV(name, len);
+    const char * const temp = SvPV_const(name, len);
     return is_gv_magical(temp, len, flags);
 }
 
@@ -1889,9 +1977,10 @@ pointers returned by SvPV.
 bool
 Perl_is_gv_magical(pTHX_ const char *name, STRLEN len, U32 flags)
 {
-    (void)flags;
+    PERL_UNUSED_ARG(flags);
+
     if (len > 1) {
-	const char *name1 = name + 1;
+	const char * const name1 = name + 1;
 	switch (*name) {
 	case 'I':
 	    if (len == 3 && name1[1] == 'S' && name[2] == 'A')