X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=hv.c;h=a5884e52e2550ebdb6e96da9f0a37cb0d152a6a6;hb=f052c252aae9b0ee4c2e0248b24590df50414a11;hp=eebf585ad565fdf3e62f05cc0bbc670ab65de8f5;hpb=b72a56350cdb03ab2b46275dcc73756786a8dc8b;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/hv.c b/hv.c
index eebf585..a5884e5 100644
--- a/hv.c
+++ b/hv.c
@@ -15,14 +15,13 @@
 #define PERL_IN_HV_C
 #include "perl.h"
 
-
 STATIC HE*
 S_new_he(pTHX)
 {
     HE* he;
     LOCK_SV_MUTEX;
     if (!PL_he_root)
-        more_he();
+	more_he();
     he = PL_he_root;
     PL_he_root = HeNEXT(he);
     UNLOCK_SV_MUTEX;
@@ -52,8 +51,8 @@ S_more_he(pTHX)
     heend = &he[1008 / sizeof(HE) - 1];
     PL_he_root = ++he;
     while (he < heend) {
-        HeNEXT(he) = (HE*)(he + 1);
-        he++;
+	HeNEXT(he) = (HE*)(he + 1);
+	he++;
     }
     HeNEXT(he) = 0;
 }
@@ -100,7 +99,7 @@ Perl_unshare_hek(pTHX_ HEK *hek)
 
 #if defined(USE_ITHREADS)
 HE *
-Perl_he_dup(pTHX_ HE *e, bool shared)
+Perl_he_dup(pTHX_ HE *e, bool shared, CLONE_PARAMS* param)
 {
     HE *ret;
 
@@ -115,18 +114,37 @@ Perl_he_dup(pTHX_ HE *e, bool shared)
     ret = new_HE();
     ptr_table_store(PL_ptr_table, e, ret);
 
-    HeNEXT(ret) = he_dup(HeNEXT(e),shared);
+    HeNEXT(ret) = he_dup(HeNEXT(e),shared, param);
     if (HeKLEN(e) == HEf_SVKEY)
-	HeKEY_sv(ret) = SvREFCNT_inc(sv_dup(HeKEY_sv(e)));
+	HeKEY_sv(ret) = SvREFCNT_inc(sv_dup(HeKEY_sv(e), param));
     else if (shared)
 	HeKEY_hek(ret) = share_hek(HeKEY(e), HeKLEN_UTF8(e), HeHASH(e));
     else
 	HeKEY_hek(ret) = save_hek(HeKEY(e), HeKLEN_UTF8(e), HeHASH(e));
-    HeVAL(ret) = SvREFCNT_inc(sv_dup(HeVAL(e)));
+    HeVAL(ret) = SvREFCNT_inc(sv_dup(HeVAL(e), param));
     return ret;
 }
 #endif	/* USE_ITHREADS */
 
+static void
+Perl_hv_notallowed(pTHX_ bool is_utf8, const char *key, I32 klen,
+		   const char *keysave)
+{
+    SV *sv = sv_newmortal();
+    if (key == keysave) {
+	sv_setpvn(sv, key, klen);
+    }
+    else {
+	/* Need to free saved eventually assign to mortal SV */
+	SV *sv = sv_newmortal();
+	sv_usepvn(sv, (char *) key, klen);
+    }
+    if (is_utf8) {
+	SvUTF8_on(sv);
+    }
+    Perl_croak(aTHX_ "Attempt to access to key '%_' in fixed hash",sv);
+}
+
 /* (klen == HEf_SVKEY) is special for MAGICAL hv entries, meaning key slot
  * contains an SV* */
 
@@ -136,7 +154,7 @@ Perl_he_dup(pTHX_ HE *e, bool shared)
 Returns the SV which corresponds to the specified key in the hash.  The
 C<klen> is the length of the key.  If C<lval> is set then the fetch will be
 part of a store.  Check that the return value is non-null before
-dereferencing it to a C<SV*>.
+dereferencing it to an C<SV*>.
 
 See L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for more
 information on how to use this function on tied hashes.
@@ -147,6 +165,7 @@ information on how to use this function on tied hashes.
 SV**
 Perl_hv_fetch(pTHX_ HV *hv, const char *key, I32 klen, I32 lval)
 {
+    register XPVHV* xhv;
     register U32 hash;
     register HE *entry;
     SV *sv;
@@ -183,19 +202,23 @@ Perl_hv_fetch(pTHX_ HV *hv, const char *key, I32 klen, I32 lval)
 #endif
     }
 
-    if (!HvARRAY(hv)) {
+    /* We use xhv->xhv_foo fields directly instead of HvFOO(hv) to
+       avoid unnecessary pointer dereferencing. */
+    xhv = (XPVHV*)SvANY(hv);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */) {
 	if (lval
 #ifdef DYNAMIC_ENV_FETCH  /* if it's an %ENV lookup, we may get it on the fly */
-	         || mg_find((SV*)hv, PERL_MAGIC_env)
+		 || (SvRMAGICAL((SV*)hv) && mg_find((SV*)hv, PERL_MAGIC_env))
 #endif
-	                                                          )
-	    Newz(503, HvARRAY(hv),
-		 PERL_HV_ARRAY_ALLOC_BYTES(HvMAX(hv) + 1), HE*);
+								  )
+	    Newz(503, xhv->xhv_array /* HvARRAY(hv) */,
+		 PERL_HV_ARRAY_ALLOC_BYTES(xhv->xhv_max+1 /* HvMAX(hv)+1 */),
+		 char);
 	else
 	    return 0;
     }
 
-    if (is_utf8 && !(PL_hints & HINT_UTF8_DISTINCT)) {
+    if (is_utf8) {
 	STRLEN tmplen = klen;
 	/* Just casting the &klen to (STRLEN) won't work well
 	 * if STRLEN and I32 are of different widths. --jhi */
@@ -205,7 +228,8 @@ Perl_hv_fetch(pTHX_ HV *hv, const char *key, I32 klen, I32 lval)
 
     PERL_HASH(hash, key, klen);
 
-    entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    entry = ((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     for (; entry; entry = HeNEXT(entry)) {
 	if (HeHASH(entry) != hash)		/* strings can't be equal */
 	    continue;
@@ -217,10 +241,14 @@ Perl_hv_fetch(pTHX_ HV *hv, const char *key, I32 klen, I32 lval)
 	    continue;
 	if (key != keysave)
 	    Safefree(key);
+	/* if we find a placeholder, we pretend we haven't found anything */
+	if (HeVAL(entry) == &PL_sv_undef)
+	    break;
 	return &HeVAL(entry);
+
     }
 #ifdef DYNAMIC_ENV_FETCH  /* %ENV lookup?  If so, try to fetch the value now */
-    if (mg_find((SV*)hv, PERL_MAGIC_env)) {
+    if (SvRMAGICAL((SV*)hv) && mg_find((SV*)hv, PERL_MAGIC_env)) {
 	unsigned long len;
 	char *env = PerlEnv_ENVgetenv_len(key,&len);
 	if (env) {
@@ -232,6 +260,9 @@ Perl_hv_fetch(pTHX_ HV *hv, const char *key, I32 klen, I32 lval)
 	}
     }
 #endif
+    if (!entry && SvREADONLY(hv)) {
+	Perl_hv_notallowed(aTHX_ is_utf8, key, klen, keysave);
+    }
     if (lval) {		/* gonna assign to this, so it better be there */
 	sv = NEWSV(61,0);
 	if (key != keysave) { /* must be is_utf8 == 0 */
@@ -247,7 +278,7 @@ Perl_hv_fetch(pTHX_ HV *hv, const char *key, I32 klen, I32 lval)
     return 0;
 }
 
-/* returns a HE * structure with the all fields set */
+/* returns an HE * structure with the all fields set */
 /* note that hent_val will be a mortal sv for MAGICAL hashes */
 /*
 =for apidoc hv_fetch_ent
@@ -269,6 +300,7 @@ information on how to use this function on tied hashes.
 HE *
 Perl_hv_fetch_ent(pTHX_ HV *hv, SV *keysv, I32 lval, register U32 hash)
 {
+    register XPVHV* xhv;
     register char *key;
     STRLEN klen;
     register HE *entry;
@@ -310,14 +342,16 @@ Perl_hv_fetch_ent(pTHX_ HV *hv, SV *keysv, I32 lval, register U32 hash)
 #endif
     }
 
-    if (!HvARRAY(hv)) {
+    xhv = (XPVHV*)SvANY(hv);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */) {
 	if (lval
 #ifdef DYNAMIC_ENV_FETCH  /* if it's an %ENV lookup, we may get it on the fly */
-	         || mg_find((SV*)hv, PERL_MAGIC_env)
+		 || (SvRMAGICAL((SV*)hv) && mg_find((SV*)hv, PERL_MAGIC_env))
 #endif
-	                                                          )
-	    Newz(503, HvARRAY(hv),
-		 PERL_HV_ARRAY_ALLOC_BYTES(HvMAX(hv) + 1), HE*);
+								  )
+	    Newz(503, xhv->xhv_array /* HvARRAY(hv) */,
+		 PERL_HV_ARRAY_ALLOC_BYTES(xhv->xhv_max+1 /* HvMAX(hv)+1 */),
+		 char);
 	else
 	    return 0;
     }
@@ -325,13 +359,14 @@ Perl_hv_fetch_ent(pTHX_ HV *hv, SV *keysv, I32 lval, register U32 hash)
     keysave = key = SvPV(keysv, klen);
     is_utf8 = (SvUTF8(keysv)!=0);
 
-    if (is_utf8 && !(PL_hints & HINT_UTF8_DISTINCT))
+    if (is_utf8)
 	key = (char*)bytes_from_utf8((U8*)key, &klen, &is_utf8);
 
     if (!hash)
 	PERL_HASH(hash, key, klen);
 
-    entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    entry = ((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     for (; entry; entry = HeNEXT(entry)) {
 	if (HeHASH(entry) != hash)		/* strings can't be equal */
 	    continue;
@@ -343,10 +378,13 @@ Perl_hv_fetch_ent(pTHX_ HV *hv, SV *keysv, I32 lval, register U32 hash)
 	    continue;
 	if (key != keysave)
 	    Safefree(key);
+	/* if we find a placeholder, we pretend we haven't found anything */
+	if (HeVAL(entry) == &PL_sv_undef)
+	    break;
 	return entry;
     }
 #ifdef DYNAMIC_ENV_FETCH  /* %ENV lookup?  If so, try to fetch the value now */
-    if (mg_find((SV*)hv, PERL_MAGIC_env)) {
+    if (SvRMAGICAL((SV*)hv) && mg_find((SV*)hv, PERL_MAGIC_env)) {
 	unsigned long len;
 	char *env = PerlEnv_ENVgetenv_len(key,&len);
 	if (env) {
@@ -356,6 +394,9 @@ Perl_hv_fetch_ent(pTHX_ HV *hv, SV *keysv, I32 lval, register U32 hash)
 	}
     }
 #endif
+    if (!entry && SvREADONLY(hv)) {
+	Perl_hv_notallowed(aTHX_ is_utf8, key, klen, keysave);
+    }
     if (key != keysave)
 	Safefree(key);
     if (lval) {		/* gonna assign to this, so it better be there */
@@ -405,6 +446,7 @@ information on how to use this function on tied hashes.
 SV**
 Perl_hv_store(pTHX_ HV *hv, const char *key, I32 klen, SV *val, register U32 hash)
 {
+    register XPVHV* xhv;
     register I32 i;
     register HE *entry;
     register HE **oentry;
@@ -419,24 +461,25 @@ Perl_hv_store(pTHX_ HV *hv, const char *key, I32 klen, SV *val, register U32 has
       is_utf8 = TRUE;
     }
 
+    xhv = (XPVHV*)SvANY(hv);
     if (SvMAGICAL(hv)) {
 	bool needs_copy;
 	bool needs_store;
 	hv_magic_check (hv, &needs_copy, &needs_store);
 	if (needs_copy) {
 	    mg_copy((SV*)hv, val, key, klen);
-	    if (!HvARRAY(hv) && !needs_store)
+	    if (!xhv->xhv_array /* !HvARRAY */ && !needs_store)
 		return 0;
 #ifdef ENV_IS_CASELESS
 	    else if (mg_find((SV*)hv, PERL_MAGIC_env)) {
-                key = savepvn(key,klen);
-		key = strupr(key);
+		key = savepvn(key,klen);
+		key = (const char*)strupr((char*)key);
 		hash = 0;
 	    }
 #endif
 	}
     }
-    if (is_utf8 && !(PL_hints & HINT_UTF8_DISTINCT)) {
+    if (is_utf8) {
 	STRLEN tmplen = klen;
 	/* See the note in hv_fetch(). --jhi */
 	key = (char*)bytes_from_utf8((U8*)key, &tmplen, &is_utf8);
@@ -446,11 +489,13 @@ Perl_hv_store(pTHX_ HV *hv, const char *key, I32 klen, SV *val, register U32 has
     if (!hash)
 	PERL_HASH(hash, key, klen);
 
-    if (!HvARRAY(hv))
-	Newz(505, HvARRAY(hv),
-	     PERL_HV_ARRAY_ALLOC_BYTES(HvMAX(hv) + 1), HE*);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */)
+	Newz(505, xhv->xhv_array /* HvARRAY(hv) */,
+	     PERL_HV_ARRAY_ALLOC_BYTES(xhv->xhv_max+1 /* HvMAX(hv)+1 */),
+	     char);
 
-    oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    oentry = &((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     i = 1;
 
     for (entry = *oentry; entry; i=0, entry = HeNEXT(entry)) {
@@ -462,13 +507,20 @@ Perl_hv_store(pTHX_ HV *hv, const char *key, I32 klen, SV *val, register U32 has
 	    continue;
 	if (HeKUTF8(entry) != (char)is_utf8)
 	    continue;
-	SvREFCNT_dec(HeVAL(entry));
+	if (HeVAL(entry) == &PL_sv_undef)
+	    xhv->xhv_placeholders--; /* yes, can store into placeholder slot */
+	else
+	    SvREFCNT_dec(HeVAL(entry));
 	HeVAL(entry) = val;
 	if (key != keysave)
 	    Safefree(key);
 	return &HeVAL(entry);
     }
 
+    if (SvREADONLY(hv)) {
+	Perl_hv_notallowed(aTHX_ is_utf8, key, klen, keysave);
+    }
+
     entry = new_HE();
     if (HvSHAREKEYS(hv))
 	HeKEY_hek(entry) = share_hek(key, is_utf8?-klen:klen, hash);
@@ -480,10 +532,10 @@ Perl_hv_store(pTHX_ HV *hv, const char *key, I32 klen, SV *val, register U32 has
     HeNEXT(entry) = *oentry;
     *oentry = entry;
 
-    HvKEYS(hv)++;
+    xhv->xhv_keys++; /* HvKEYS(hv)++ */
     if (i) {				/* initial entry? */
-	HvFILL(hv)++;
-	if (HvKEYS(hv) > HvMAX(hv))
+	xhv->xhv_fill++; /* HvFILL(hv)++ */
+	if (xhv->xhv_keys > xhv->xhv_max /* HvKEYS(hv) > HvMAX(hv) */)
 	    hsplit(hv);
     }
 
@@ -512,6 +564,7 @@ information on how to use this function on tied hashes.
 HE *
 Perl_hv_store_ent(pTHX_ HV *hv, SV *keysv, SV *val, register U32 hash)
 {
+    register XPVHV* xhv;
     register char *key;
     STRLEN klen;
     register I32 i;
@@ -523,19 +576,20 @@ Perl_hv_store_ent(pTHX_ HV *hv, SV *keysv, SV *val, register U32 hash)
     if (!hv)
 	return 0;
 
+    xhv = (XPVHV*)SvANY(hv);
     if (SvMAGICAL(hv)) {
- 	bool needs_copy;
- 	bool needs_store;
- 	hv_magic_check (hv, &needs_copy, &needs_store);
- 	if (needs_copy) {
- 	    bool save_taint = PL_tainted;
- 	    if (PL_tainting)
- 		PL_tainted = SvTAINTED(keysv);
- 	    keysv = sv_2mortal(newSVsv(keysv));
- 	    mg_copy((SV*)hv, val, (char*)keysv, HEf_SVKEY);
- 	    TAINT_IF(save_taint);
- 	    if (!HvARRAY(hv) && !needs_store)
- 		return Nullhe;
+	bool needs_copy;
+	bool needs_store;
+	hv_magic_check (hv, &needs_copy, &needs_store);
+	if (needs_copy) {
+	    bool save_taint = PL_tainted;
+	    if (PL_tainting)
+		PL_tainted = SvTAINTED(keysv);
+	    keysv = sv_2mortal(newSVsv(keysv));
+	    mg_copy((SV*)hv, val, (char*)keysv, HEf_SVKEY);
+	    TAINT_IF(save_taint);
+	    if (!xhv->xhv_array /* !HvARRAY(hv) */ && !needs_store)
+		return Nullhe;
 #ifdef ENV_IS_CASELESS
 	    else if (mg_find((SV*)hv, PERL_MAGIC_env)) {
 		key = SvPV(keysv, klen);
@@ -550,17 +604,19 @@ Perl_hv_store_ent(pTHX_ HV *hv, SV *keysv, SV *val, register U32 hash)
     keysave = key = SvPV(keysv, klen);
     is_utf8 = (SvUTF8(keysv) != 0);
 
-    if (is_utf8 && !(PL_hints & HINT_UTF8_DISTINCT))
+    if (is_utf8)
 	key = (char*)bytes_from_utf8((U8*)key, &klen, &is_utf8);
 
     if (!hash)
 	PERL_HASH(hash, key, klen);
 
-    if (!HvARRAY(hv))
-	Newz(505, HvARRAY(hv),
-	     PERL_HV_ARRAY_ALLOC_BYTES(HvMAX(hv) + 1), HE*);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */)
+	Newz(505, xhv->xhv_array /* HvARRAY(hv) */,
+	     PERL_HV_ARRAY_ALLOC_BYTES(xhv->xhv_max+1 /* HvMAX(hv)+1 */),
+	     char);
 
-    oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    oentry = &((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     i = 1;
 
     for (entry = *oentry; entry; i=0, entry = HeNEXT(entry)) {
@@ -572,28 +628,35 @@ Perl_hv_store_ent(pTHX_ HV *hv, SV *keysv, SV *val, register U32 hash)
 	    continue;
 	if (HeKUTF8(entry) != (char)is_utf8)
 	    continue;
-	SvREFCNT_dec(HeVAL(entry));
+	if (HeVAL(entry) == &PL_sv_undef)
+	    xhv->xhv_placeholders--; /* yes, can store into placeholder slot */
+	else
+	    SvREFCNT_dec(HeVAL(entry));
 	HeVAL(entry) = val;
 	if (key != keysave)
 	    Safefree(key);
 	return entry;
     }
 
+    if (SvREADONLY(hv)) {
+	Perl_hv_notallowed(aTHX_ is_utf8, key, klen, keysave);
+    }
+
     entry = new_HE();
     if (HvSHAREKEYS(hv))
-	HeKEY_hek(entry) = share_hek(key, is_utf8?-klen:klen, hash);
+	HeKEY_hek(entry) = share_hek(key, is_utf8?-(I32)klen:klen, hash);
     else                                       /* gotta do the real thing */
-	HeKEY_hek(entry) = save_hek(key, is_utf8?-klen:klen, hash);
+	HeKEY_hek(entry) = save_hek(key, is_utf8?-(I32)klen:klen, hash);
     if (key != keysave)
 	Safefree(key);
     HeVAL(entry) = val;
     HeNEXT(entry) = *oentry;
     *oentry = entry;
 
-    HvKEYS(hv)++;
+    xhv->xhv_keys++; /* HvKEYS(hv)++ */
     if (i) {				/* initial entry? */
-	HvFILL(hv)++;
-	if (HvKEYS(hv) > HvMAX(hv))
+	xhv->xhv_fill++; /* HvFILL(hv)++ */
+	if (xhv->xhv_keys > xhv->xhv_max /* HvKEYS(hv) > HvMAX(hv) */)
 	    hsplit(hv);
     }
 
@@ -614,6 +677,7 @@ will be returned.
 SV *
 Perl_hv_delete(pTHX_ HV *hv, const char *key, I32 klen, I32 flags)
 {
+    register XPVHV* xhv;
     register I32 i;
     register U32 hash;
     register HE *entry;
@@ -651,12 +715,13 @@ Perl_hv_delete(pTHX_ HV *hv, const char *key, I32 klen, I32 flags)
 		key = strupr(SvPVX(sv));
 	    }
 #endif
-        }
+	}
     }
-    if (!HvARRAY(hv))
+    xhv = (XPVHV*)SvANY(hv);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */)
 	return Nullsv;
 
-    if (is_utf8 && !(PL_hints & HINT_UTF8_DISTINCT)) {
+    if (is_utf8) {
 	STRLEN tmplen = klen;
 	/* See the note in hv_fetch(). --jhi */
 	key = (char*)bytes_from_utf8((U8*)key, &tmplen, &is_utf8);
@@ -665,7 +730,8 @@ Perl_hv_delete(pTHX_ HV *hv, const char *key, I32 klen, I32 flags)
 
     PERL_HASH(hash, key, klen);
 
-    oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    oentry = &((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     entry = *oentry;
     i = 1;
     for (; entry; i=0, oentry = &HeNEXT(entry), entry = *oentry) {
@@ -679,22 +745,63 @@ Perl_hv_delete(pTHX_ HV *hv, const char *key, I32 klen, I32 flags)
 	    continue;
 	if (key != keysave)
 	    Safefree(key);
-	*oentry = HeNEXT(entry);
-	if (i && !*oentry)
-	    HvFILL(hv)--;
+	/* if placeholder is here, it's already been deleted.... */
+	if (HeVAL(entry) == &PL_sv_undef)
+	{
+	    if (SvREADONLY(hv))
+		return Nullsv;  /* if still SvREADONLY, leave it deleted. */
+	    else {
+		/* okay, really delete the placeholder... */
+		*oentry = HeNEXT(entry);
+		if (i && !*oentry)
+		    xhv->xhv_fill--; /* HvFILL(hv)-- */
+		if (entry == xhv->xhv_eiter /* HvEITER(hv) */)
+		    HvLAZYDEL_on(hv);
+		else
+		    hv_free_ent(hv, entry);
+		xhv->xhv_keys--; /* HvKEYS(hv)-- */
+		xhv->xhv_placeholders--;
+		return Nullsv;
+	    }
+	}
+	else if (SvREADONLY(hv) && HeVAL(entry) && SvREADONLY(HeVAL(entry))) {
+	    Perl_hv_notallowed(aTHX_ is_utf8, key, klen, keysave);
+	}
+
 	if (flags & G_DISCARD)
 	    sv = Nullsv;
 	else {
 	    sv = sv_2mortal(HeVAL(entry));
 	    HeVAL(entry) = &PL_sv_undef;
 	}
-	if (entry == HvEITER(hv))
-	    HvLAZYDEL_on(hv);
-	else
-	    hv_free_ent(hv, entry);
-	HvKEYS(hv)--;
+
+	/*
+	 * If a restricted hash, rather than really deleting the entry, put
+	 * a placeholder there. This marks the key as being "approved", so
+	 * we can still access via not-really-existing key without raising
+	 * an error.
+	 */
+	if (SvREADONLY(hv)) {
+	    HeVAL(entry) = &PL_sv_undef;
+	    /* We'll be saving this slot, so the number of allocated keys
+	     * doesn't go down, but the number placeholders goes up */
+	    xhv->xhv_placeholders++; /* HvPLACEHOLDERS(hv)++ */
+	} else {
+	    *oentry = HeNEXT(entry);
+	    if (i && !*oentry)
+		xhv->xhv_fill--; /* HvFILL(hv)-- */
+	    if (entry == xhv->xhv_eiter /* HvEITER(hv) */)
+		HvLAZYDEL_on(hv);
+	    else
+		hv_free_ent(hv, entry);
+	    xhv->xhv_keys--; /* HvKEYS(hv)-- */
+	}
 	return sv;
     }
+    if (SvREADONLY(hv)) {
+	Perl_hv_notallowed(aTHX_ is_utf8, key, klen, keysave);
+    }
+
     if (key != keysave)
 	Safefree(key);
     return Nullsv;
@@ -714,6 +821,7 @@ precomputed hash value, or 0 to ask for it to be computed.
 SV *
 Perl_hv_delete_ent(pTHX_ HV *hv, SV *keysv, I32 flags, U32 hash)
 {
+    register XPVHV* xhv;
     register I32 i;
     register char *key;
     STRLEN klen;
@@ -751,19 +859,21 @@ Perl_hv_delete_ent(pTHX_ HV *hv, SV *keysv, I32 flags, U32 hash)
 #endif
 	}
     }
-    if (!HvARRAY(hv))
+    xhv = (XPVHV*)SvANY(hv);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */)
 	return Nullsv;
 
     keysave = key = SvPV(keysv, klen);
     is_utf8 = (SvUTF8(keysv) != 0);
 
-    if (is_utf8 && !(PL_hints & HINT_UTF8_DISTINCT))
+    if (is_utf8)
 	key = (char*)bytes_from_utf8((U8*)key, &klen, &is_utf8);
 
     if (!hash)
 	PERL_HASH(hash, key, klen);
 
-    oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    oentry = &((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     entry = *oentry;
     i = 1;
     for (; entry; i=0, oentry = &HeNEXT(entry), entry = *oentry) {
@@ -777,22 +887,63 @@ Perl_hv_delete_ent(pTHX_ HV *hv, SV *keysv, I32 flags, U32 hash)
 	    continue;
 	if (key != keysave)
 	    Safefree(key);
-	*oentry = HeNEXT(entry);
-	if (i && !*oentry)
-	    HvFILL(hv)--;
+
+	/* if placeholder is here, it's already been deleted.... */
+	if (HeVAL(entry) == &PL_sv_undef)
+	{
+	    if (SvREADONLY(hv))
+		return Nullsv; /* if still SvREADONLY, leave it deleted. */
+
+           /* okay, really delete the placeholder. */
+           *oentry = HeNEXT(entry);
+           if (i && !*oentry)
+               xhv->xhv_fill--; /* HvFILL(hv)-- */
+           if (entry == xhv->xhv_eiter /* HvEITER(hv) */)
+               HvLAZYDEL_on(hv);
+           else
+               hv_free_ent(hv, entry);
+           xhv->xhv_keys--; /* HvKEYS(hv)-- */
+           xhv->xhv_placeholders--;
+           return Nullsv;
+	}
+	else if (SvREADONLY(hv) && HeVAL(entry) && SvREADONLY(HeVAL(entry))) {
+	    Perl_hv_notallowed(aTHX_ is_utf8, key, klen, keysave);
+	}
+
 	if (flags & G_DISCARD)
 	    sv = Nullsv;
 	else {
 	    sv = sv_2mortal(HeVAL(entry));
 	    HeVAL(entry) = &PL_sv_undef;
 	}
-	if (entry == HvEITER(hv))
-	    HvLAZYDEL_on(hv);
-	else
-	    hv_free_ent(hv, entry);
-	HvKEYS(hv)--;
+
+	/*
+	 * If a restricted hash, rather than really deleting the entry, put
+	 * a placeholder there. This marks the key as being "approved", so
+	 * we can still access via not-really-existing key without raising
+	 * an error.
+	 */
+	if (SvREADONLY(hv)) {
+	    HeVAL(entry) = &PL_sv_undef;
+	    /* We'll be saving this slot, so the number of allocated keys
+	     * doesn't go down, but the number placeholders goes up */
+	    xhv->xhv_placeholders++; /* HvPLACEHOLDERS(hv)++ */
+	} else {
+	    *oentry = HeNEXT(entry);
+	    if (i && !*oentry)
+		xhv->xhv_fill--; /* HvFILL(hv)-- */
+	    if (entry == xhv->xhv_eiter /* HvEITER(hv) */)
+		HvLAZYDEL_on(hv);
+	    else
+		hv_free_ent(hv, entry);
+	    xhv->xhv_keys--; /* HvKEYS(hv)-- */
+	}
 	return sv;
     }
+    if (SvREADONLY(hv)) {
+	Perl_hv_notallowed(aTHX_ is_utf8, key, klen, keysave);
+    }
+
     if (key != keysave)
 	Safefree(key);
     return Nullsv;
@@ -810,6 +961,7 @@ C<klen> is the length of the key.
 bool
 Perl_hv_exists(pTHX_ HV *hv, const char *key, I32 klen)
 {
+    register XPVHV* xhv;
     register U32 hash;
     register HE *entry;
     SV *sv;
@@ -839,12 +991,13 @@ Perl_hv_exists(pTHX_ HV *hv, const char *key, I32 klen)
 #endif
     }
 
+    xhv = (XPVHV*)SvANY(hv);
 #ifndef DYNAMIC_ENV_FETCH
-    if (!HvARRAY(hv))
+    if (!xhv->xhv_array /* !HvARRAY(hv) */)
 	return 0;
 #endif
 
-    if (is_utf8 && !(PL_hints & HINT_UTF8_DISTINCT)) {
+    if (is_utf8) {
 	STRLEN tmplen = klen;
 	/* See the note in hv_fetch(). --jhi */
 	key = (char*)bytes_from_utf8((U8*)key, &tmplen, &is_utf8);
@@ -854,10 +1007,11 @@ Perl_hv_exists(pTHX_ HV *hv, const char *key, I32 klen)
     PERL_HASH(hash, key, klen);
 
 #ifdef DYNAMIC_ENV_FETCH
-    if (!HvARRAY(hv)) entry = Null(HE*);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */) entry = Null(HE*);
     else
 #endif
-    entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    entry = ((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     for (; entry; entry = HeNEXT(entry)) {
 	if (HeHASH(entry) != hash)		/* strings can't be equal */
 	    continue;
@@ -869,10 +1023,14 @@ Perl_hv_exists(pTHX_ HV *hv, const char *key, I32 klen)
 	    continue;
 	if (key != keysave)
 	    Safefree(key);
+	/* If we find the key, but the value is a placeholder, return false. */
+	if (HeVAL(entry) == &PL_sv_undef)
+	    return FALSE;
+
 	return TRUE;
     }
 #ifdef DYNAMIC_ENV_FETCH  /* is it out there? */
-    if (mg_find((SV*)hv, PERL_MAGIC_env)) {
+    if (SvRMAGICAL((SV*)hv) && mg_find((SV*)hv, PERL_MAGIC_env)) {
 	unsigned long len;
 	char *env = PerlEnv_ENVgetenv_len(key,&len);
 	if (env) {
@@ -902,6 +1060,7 @@ computed.
 bool
 Perl_hv_exists_ent(pTHX_ HV *hv, SV *keysv, U32 hash)
 {
+    register XPVHV* xhv;
     register char *key;
     STRLEN klen;
     register HE *entry;
@@ -914,12 +1073,12 @@ Perl_hv_exists_ent(pTHX_ HV *hv, SV *keysv, U32 hash)
 
     if (SvRMAGICAL(hv)) {
 	if (mg_find((SV*)hv, PERL_MAGIC_tied) || SvGMAGICAL((SV*)hv)) {
-           SV* svret = sv_newmortal();
+	   SV* svret = sv_newmortal();
 	    sv = sv_newmortal();
 	    keysv = sv_2mortal(newSVsv(keysv));
 	    mg_copy((SV*)hv, sv, (char*)keysv, HEf_SVKEY);
-           magic_existspack(svret, mg_find(sv, PERL_MAGIC_tiedelem));
-           return SvTRUE(svret);
+	   magic_existspack(svret, mg_find(sv, PERL_MAGIC_tiedelem));
+	   return SvTRUE(svret);
 	}
 #ifdef ENV_IS_CASELESS
 	else if (mg_find((SV*)hv, PERL_MAGIC_env)) {
@@ -931,23 +1090,25 @@ Perl_hv_exists_ent(pTHX_ HV *hv, SV *keysv, U32 hash)
 #endif
     }
 
+    xhv = (XPVHV*)SvANY(hv);
 #ifndef DYNAMIC_ENV_FETCH
-    if (!HvARRAY(hv))
+    if (!xhv->xhv_array /* !HvARRAY(hv) */)
 	return 0;
 #endif
 
     keysave = key = SvPV(keysv, klen);
     is_utf8 = (SvUTF8(keysv) != 0);
-    if (is_utf8 && !(PL_hints & HINT_UTF8_DISTINCT))
+    if (is_utf8)
 	key = (char*)bytes_from_utf8((U8*)key, &klen, &is_utf8);
     if (!hash)
 	PERL_HASH(hash, key, klen);
 
 #ifdef DYNAMIC_ENV_FETCH
-    if (!HvARRAY(hv)) entry = Null(HE*);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */) entry = Null(HE*);
     else
 #endif
-    entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* entry = (HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    entry = ((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     for (; entry; entry = HeNEXT(entry)) {
 	if (HeHASH(entry) != hash)		/* strings can't be equal */
 	    continue;
@@ -959,10 +1120,13 @@ Perl_hv_exists_ent(pTHX_ HV *hv, SV *keysv, U32 hash)
 	    continue;
 	if (key != keysave)
 	    Safefree(key);
+	/* If we find the key, but the value is a placeholder, return false. */
+	if (HeVAL(entry) == &PL_sv_undef)
+	    return FALSE;
 	return TRUE;
     }
 #ifdef DYNAMIC_ENV_FETCH  /* is it out there? */
-    if (mg_find((SV*)hv, PERL_MAGIC_env)) {
+    if (SvRMAGICAL((SV*)hv) && mg_find((SV*)hv, PERL_MAGIC_env)) {
 	unsigned long len;
 	char *env = PerlEnv_ENVgetenv_len(key,&len);
 	if (env) {
@@ -981,10 +1145,11 @@ Perl_hv_exists_ent(pTHX_ HV *hv, SV *keysv, U32 hash)
 STATIC void
 S_hsplit(pTHX_ HV *hv)
 {
-    I32 oldsize = (I32) HvMAX(hv) + 1; /* sic(k) */
+    register XPVHV* xhv = (XPVHV*)SvANY(hv);
+    I32 oldsize = (I32) xhv->xhv_max+1; /* HvMAX(hv)+1 (sick) */
     register I32 newsize = oldsize * 2;
     register I32 i;
-    register char *a = (char *)HvARRAY(hv);
+    register char *a = xhv->xhv_array; /* HvARRAY(hv) */
     register HE **aep;
     register HE **bep;
     register HE *entry;
@@ -1003,18 +1168,19 @@ S_hsplit(pTHX_ HV *hv)
       PL_nomemok = FALSE;
       return;
     }
-    Copy(HvARRAY(hv), a, oldsize * sizeof(HE*), char);
+    Copy(xhv->xhv_array /* HvARRAY(hv) */, a, oldsize * sizeof(HE*), char);
     if (oldsize >= 64) {
-	offer_nice_chunk(HvARRAY(hv), PERL_HV_ARRAY_ALLOC_BYTES(oldsize));
+	offer_nice_chunk(xhv->xhv_array /* HvARRAY(hv) */,
+			PERL_HV_ARRAY_ALLOC_BYTES(oldsize));
     }
     else
-	Safefree(HvARRAY(hv));
+	Safefree(xhv->xhv_array /* HvARRAY(hv) */);
 #endif
 
     PL_nomemok = FALSE;
     Zero(&a[oldsize * sizeof(HE*)], (newsize-oldsize) * sizeof(HE*), char);	/* zero 2nd half*/
-    HvMAX(hv) = --newsize;
-    HvARRAY(hv) = (HE**)a;
+    xhv->xhv_max = --newsize;	/* HvMAX(hv) = --newsize */
+    xhv->xhv_array = a;		/* HvARRAY(hv) = a */
     aep = (HE**)a;
 
     for (i=0; i<oldsize; i++,aep++) {
@@ -1026,7 +1192,7 @@ S_hsplit(pTHX_ HV *hv)
 		*oentry = HeNEXT(entry);
 		HeNEXT(entry) = *bep;
 		if (!*bep)
-		    HvFILL(hv)++;
+		    xhv->xhv_fill++; /* HvFILL(hv)++ */
 		*bep = entry;
 		continue;
 	    }
@@ -1034,14 +1200,15 @@ S_hsplit(pTHX_ HV *hv)
 		oentry = &HeNEXT(entry);
 	}
 	if (!*aep)				/* everything moved */
-	    HvFILL(hv)--;
+	    xhv->xhv_fill--; /* HvFILL(hv)-- */
     }
 }
 
 void
 Perl_hv_ksplit(pTHX_ HV *hv, IV newmax)
 {
-    I32 oldsize = (I32) HvMAX(hv) + 1; /* sic(k) */
+    register XPVHV* xhv = (XPVHV*)SvANY(hv);
+    I32 oldsize = (I32) xhv->xhv_max+1; /* HvMAX(hv)+1 (sick) */
     register I32 newsize;
     register I32 i;
     register I32 j;
@@ -1061,27 +1228,28 @@ Perl_hv_ksplit(pTHX_ HV *hv, IV newmax)
     if (newsize < newmax)
 	return;					/* overflow detection */
 
-    a = (char *)HvARRAY(hv);
+    a = xhv->xhv_array; /* HvARRAY(hv) */
     if (a) {
 	PL_nomemok = TRUE;
 #if defined(STRANGE_MALLOC) || defined(MYMALLOC)
 	Renew(a, PERL_HV_ARRAY_ALLOC_BYTES(newsize), char);
-        if (!a) {
+	if (!a) {
 	  PL_nomemok = FALSE;
 	  return;
 	}
 #else
 	New(2, a, PERL_HV_ARRAY_ALLOC_BYTES(newsize), char);
-        if (!a) {
+	if (!a) {
 	  PL_nomemok = FALSE;
 	  return;
 	}
-	Copy(HvARRAY(hv), a, oldsize * sizeof(HE*), char);
+	Copy(xhv->xhv_array /* HvARRAY(hv) */, a, oldsize * sizeof(HE*), char);
 	if (oldsize >= 64) {
-	    offer_nice_chunk(HvARRAY(hv), PERL_HV_ARRAY_ALLOC_BYTES(oldsize));
+	    offer_nice_chunk(xhv->xhv_array /* HvARRAY(hv) */,
+			    PERL_HV_ARRAY_ALLOC_BYTES(oldsize));
 	}
 	else
-	    Safefree(HvARRAY(hv));
+	    Safefree(xhv->xhv_array /* HvARRAY(hv) */);
 #endif
 	PL_nomemok = FALSE;
 	Zero(&a[oldsize * sizeof(HE*)], (newsize-oldsize) * sizeof(HE*), char); /* zero 2nd half*/
@@ -1089,9 +1257,9 @@ Perl_hv_ksplit(pTHX_ HV *hv, IV newmax)
     else {
 	Newz(0, a, PERL_HV_ARRAY_ALLOC_BYTES(newsize), char);
     }
-    HvMAX(hv) = --newsize;
-    HvARRAY(hv) = (HE**)a;
-    if (!HvFILL(hv))				/* skip rest if no entries */
+    xhv->xhv_max = --newsize; 	/* HvMAX(hv) = --newsize */
+    xhv->xhv_array = a; 	/* HvARRAY(hv) = a */
+    if (!xhv->xhv_fill /* !HvFILL(hv) */)	/* skip rest if no entries */
 	return;
 
     aep = (HE**)a;
@@ -1103,7 +1271,7 @@ Perl_hv_ksplit(pTHX_ HV *hv, IV newmax)
 		j -= i;
 		*oentry = HeNEXT(entry);
 		if (!(HeNEXT(entry) = aep[j]))
-		    HvFILL(hv)++;
+		    xhv->xhv_fill++; /* HvFILL(hv)++ */
 		aep[j] = entry;
 		continue;
 	    }
@@ -1111,7 +1279,7 @@ Perl_hv_ksplit(pTHX_ HV *hv, IV newmax)
 		oentry = &HeNEXT(entry);
 	}
 	if (!*aep)				/* everything moved */
-	    HvFILL(hv)--;
+	    xhv->xhv_fill--; /* HvFILL(hv)-- */
     }
 }
 
@@ -1127,17 +1295,19 @@ HV *
 Perl_newHV(pTHX)
 {
     register HV *hv;
+    register XPVHV* xhv;
 
     hv = (HV*)NEWSV(502,0);
     sv_upgrade((SV *)hv, SVt_PVHV);
+    xhv = (XPVHV*)SvANY(hv);
     SvPOK_off(hv);
     SvNOK_off(hv);
 #ifndef NODEFAULT_SHAREKEYS
     HvSHAREKEYS_on(hv);         /* key-sharing on by default */
 #endif
-    HvMAX(hv) = 7;		/* start with 8 buckets */
-    HvFILL(hv) = 0;
-    HvPMROOT(hv) = 0;
+    xhv->xhv_max    = 7;	/* HvMAX(hv) = 7 (start with 8 buckets) */
+    xhv->xhv_fill   = 0;	/* HvFILL(hv) = 0 */
+    xhv->xhv_pmroot = 0;	/* HvPMROOT(hv) = 0 */
     (void)hv_iterinit(hv);	/* so each() will start off right */
     return hv;
 }
@@ -1145,36 +1315,72 @@ Perl_newHV(pTHX)
 HV *
 Perl_newHVhv(pTHX_ HV *ohv)
 {
-    register HV *hv;
-    STRLEN hv_max = ohv ? HvMAX(ohv) : 0;
-    STRLEN hv_fill = ohv ? HvFILL(ohv) : 0;
-
-    hv = newHV();
-    while (hv_max && hv_max + 1 >= hv_fill * 2)
-	hv_max = hv_max / 2;	/* Is always 2^n-1 */
-    HvMAX(hv) = hv_max;
-    if (!hv_fill)
+    HV *hv = newHV();
+    STRLEN hv_max, hv_fill;
+
+    if (!ohv || (hv_fill = HvFILL(ohv)) == 0)
 	return hv;
+    hv_max = HvMAX(ohv);
+
+    if (!SvMAGICAL((SV *)ohv)) {
+	/* It's an ordinary hash, so copy it fast. AMS 20010804 */
+	int i, shared = !!HvSHAREKEYS(ohv);
+	HE **ents, **oents = (HE **)HvARRAY(ohv);
+	char *a;
+	New(0, a, PERL_HV_ARRAY_ALLOC_BYTES(hv_max+1), char);
+	ents = (HE**)a;
+
+	/* In each bucket... */
+	for (i = 0; i <= hv_max; i++) {
+	    HE *prev = NULL, *ent = NULL, *oent = oents[i];
+
+	    if (!oent) {
+		ents[i] = NULL;
+		continue;
+	    }
 
-#if 0
-    if (! SvTIED_mg((SV*)ohv, PERL_MAGIC_tied)) {
-	/* Quick way ???*/
+	    /* Copy the linked list of entries. */
+	    for (oent = oents[i]; oent; oent = HeNEXT(oent)) {
+		U32 hash   = HeHASH(oent);
+		char *key  = HeKEY(oent);
+		STRLEN len = HeKLEN_UTF8(oent);
+
+		ent = new_HE();
+		HeVAL(ent)     = newSVsv(HeVAL(oent));
+		HeKEY_hek(ent) = shared ? share_hek(key, len, hash)
+					:  save_hek(key, len, hash);
+		if (prev)
+		    HeNEXT(prev) = ent;
+		else
+		    ents[i] = ent;
+		prev = ent;
+		HeNEXT(ent) = NULL;
+	    }
+	}
+
+	HvMAX(hv)   = hv_max;
+	HvFILL(hv)  = hv_fill;
+	HvTOTALKEYS(hv)  = HvTOTALKEYS(ohv);
+	HvARRAY(hv) = ents;
     }
-    else
-#endif
-    {
+    else {
+	/* Iterate over ohv, copying keys and values one at a time. */
 	HE *entry;
-	I32 hv_riter = HvRITER(ohv);	/* current root of iterator */
-	HE *hv_eiter = HvEITER(ohv);	/* current entry of iterator */
-	
-	/* Slow way */
+	I32 riter = HvRITER(ohv);
+	HE *eiter = HvEITER(ohv);
+
+	/* Can we use fewer buckets? (hv_max is always 2^n-1) */
+	while (hv_max && hv_max + 1 >= hv_fill * 2)
+	    hv_max = hv_max / 2;
+	HvMAX(hv) = hv_max;
+
 	hv_iterinit(ohv);
 	while ((entry = hv_iternext(ohv))) {
 	    hv_store(hv, HeKEY(entry), HeKLEN_UTF8(entry),
 		     newSVsv(HeVAL(entry)), HeHASH(entry));
 	}
-	HvRITER(ohv) = hv_riter;
-	HvEITER(ohv) = hv_eiter;
+	HvRITER(ohv) = riter;
+	HvEITER(ohv) = eiter;
     }
 
     return hv;
@@ -1193,7 +1399,7 @@ Perl_hv_free_ent(pTHX_ HV *hv, register HE *entry)
     SvREFCNT_dec(val);
     if (HeKLEN(entry) == HEf_SVKEY) {
 	SvREFCNT_dec(HeKEY_sv(entry));
-        Safefree(HeKEY_hek(entry));
+	Safefree(HeKEY_hek(entry));
     }
     else if (HvSHAREKEYS(hv))
 	unshare_hek(HeKEY_hek(entry));
@@ -1232,13 +1438,17 @@ Clears a hash, making it empty.
 void
 Perl_hv_clear(pTHX_ HV *hv)
 {
+    register XPVHV* xhv;
     if (!hv)
 	return;
+    xhv = (XPVHV*)SvANY(hv);
     hfreeentries(hv);
-    HvFILL(hv) = 0;
-    HvKEYS(hv) = 0;
-    if (HvARRAY(hv))
-	(void)memzero(HvARRAY(hv), (HvMAX(hv) + 1) * sizeof(HE*));
+    xhv->xhv_fill = 0; /* HvFILL(hv) = 0 */
+    xhv->xhv_keys = 0; /* HvKEYS(hv) = 0 */
+    xhv->xhv_placeholders = 0; /* HvPLACEHOLDERS(hv) = 0 */
+    if (xhv->xhv_array /* HvARRAY(hv) */)
+	(void)memzero(xhv->xhv_array /* HvARRAY(hv) */,
+		      (xhv->xhv_max+1 /* HvMAX(hv)+1 */) * sizeof(HE*));
 
     if (SvRMAGICAL(hv))
 	mg_clear((SV*)hv);
@@ -1288,18 +1498,21 @@ Undefines the hash.
 void
 Perl_hv_undef(pTHX_ HV *hv)
 {
+    register XPVHV* xhv;
     if (!hv)
 	return;
+    xhv = (XPVHV*)SvANY(hv);
     hfreeentries(hv);
-    Safefree(HvARRAY(hv));
+    Safefree(xhv->xhv_array /* HvARRAY(hv) */);
     if (HvNAME(hv)) {
 	Safefree(HvNAME(hv));
 	HvNAME(hv) = 0;
     }
-    HvARRAY(hv) = 0;
-    HvMAX(hv)   = 7;		/* it's a normal hash */
-    HvFILL(hv)  = 0;
-    HvKEYS(hv)  = 0;
+    xhv->xhv_max   = 7;	/* HvMAX(hv) = 7 (it's a normal hash) */
+    xhv->xhv_array = 0;	/* HvARRAY(hv) = 0 */
+    xhv->xhv_fill  = 0;	/* HvFILL(hv) = 0 */
+    xhv->xhv_keys  = 0;	/* HvKEYS(hv) = 0 */
+    xhv->xhv_placeholders = 0; /* HvPLACEHOLDERS(hv) = 0 */
 
     if (SvRMAGICAL(hv))
 	mg_clear((SV*)hv);
@@ -1322,18 +1535,21 @@ value, you can get it through the macro C<HvFILL(tb)>.
 I32
 Perl_hv_iterinit(pTHX_ HV *hv)
 {
+    register XPVHV* xhv;
     HE *entry;
 
     if (!hv)
 	Perl_croak(aTHX_ "Bad hash");
-    entry = HvEITER(hv);
+    xhv = (XPVHV*)SvANY(hv);
+    entry = xhv->xhv_eiter; /* HvEITER(hv) */
     if (entry && HvLAZYDEL(hv)) {	/* was deleted earlier? */
 	HvLAZYDEL_off(hv);
 	hv_free_ent(hv, entry);
     }
-    HvRITER(hv) = -1;
-    HvEITER(hv) = Null(HE*);
-    return HvKEYS(hv);		/* used to be xhv->xhv_fill before 5.004_65 */
+    xhv->xhv_riter = -1; 	/* HvRITER(hv) = -1 */
+    xhv->xhv_eiter = Null(HE*); /* HvEITER(hv) = Null(HE*) */
+    /* used to be xhv->xhv_fill before 5.004_65 */
+    return XHvTOTALKEYS(xhv);
 }
 
 /*
@@ -1347,13 +1563,15 @@ Returns entries from a hash iterator.  See C<hv_iterinit>.
 HE *
 Perl_hv_iternext(pTHX_ HV *hv)
 {
+    register XPVHV* xhv;
     register HE *entry;
     HE *oldentry;
     MAGIC* mg;
 
     if (!hv)
 	Perl_croak(aTHX_ "Bad hash");
-    oldentry = entry = HvEITER(hv);
+    xhv = (XPVHV*)SvANY(hv);
+    oldentry = entry = xhv->xhv_eiter; /* HvEITER(hv) */
 
     if ((mg = SvTIED_mg((SV*)hv, PERL_MAGIC_tied))) {
 	SV *key = sv_newmortal();
@@ -1365,7 +1583,8 @@ Perl_hv_iternext(pTHX_ HV *hv)
 	    char *k;
 	    HEK *hek;
 
-	    HvEITER(hv) = entry = new_HE();  /* one HE per MAGICAL hash */
+	    /* one HE per MAGICAL hash */
+	    xhv->xhv_eiter = entry = new_HE(); /* HvEITER(hv) = new_HE() */
 	    Zero(entry, 1, HE);
 	    Newz(54, k, HEK_BASESIZE + sizeof(SV*), char);
 	    hek = (HEK*)k;
@@ -1373,35 +1592,51 @@ Perl_hv_iternext(pTHX_ HV *hv)
 	    HeKLEN(entry) = HEf_SVKEY;
 	}
 	magic_nextpack((SV*) hv,mg,key);
-        if (SvOK(key)) {
+	if (SvOK(key)) {
 	    /* force key to stay around until next time */
 	    HeSVKEY_set(entry, SvREFCNT_inc(key));
 	    return entry;		/* beware, hent_val is not set */
-        }
+	}
 	if (HeVAL(entry))
 	    SvREFCNT_dec(HeVAL(entry));
 	Safefree(HeKEY_hek(entry));
 	del_HE(entry);
-	HvEITER(hv) = Null(HE*);
+	xhv->xhv_eiter = Null(HE*); /* HvEITER(hv) = Null(HE*) */
 	return Null(HE*);
     }
 #ifdef DYNAMIC_ENV_FETCH  /* set up %ENV for iteration */
-    if (!entry && mg_find((SV*)hv, PERL_MAGIC_env))
+    if (!entry && SvRMAGICAL((SV*)hv) && mg_find((SV*)hv, PERL_MAGIC_env))
 	prime_env_iter();
 #endif
 
-    if (!HvARRAY(hv))
-	Newz(506, HvARRAY(hv),
-	     PERL_HV_ARRAY_ALLOC_BYTES(HvMAX(hv) + 1), HE*);
+    if (!xhv->xhv_array /* !HvARRAY(hv) */)
+	Newz(506, xhv->xhv_array /* HvARRAY(hv) */,
+	     PERL_HV_ARRAY_ALLOC_BYTES(xhv->xhv_max+1 /* HvMAX(hv)+1 */),
+	     char);
     if (entry)
+    {
 	entry = HeNEXT(entry);
+	/*
+	 * Skip past any placeholders -- don't want to include them in
+	 * any iteration.
+	 */
+	while (entry && HeVAL(entry) == &PL_sv_undef) {
+	    entry = HeNEXT(entry);
+	}
+    }
     while (!entry) {
-	HvRITER(hv)++;
-	if (HvRITER(hv) > HvMAX(hv)) {
-	    HvRITER(hv) = -1;
+	xhv->xhv_riter++; /* HvRITER(hv)++ */
+	if (xhv->xhv_riter > xhv->xhv_max /* HvRITER(hv) > HvMAX(hv) */) {
+	    xhv->xhv_riter = -1; /* HvRITER(hv) = -1 */
 	    break;
 	}
-	entry = (HvARRAY(hv))[HvRITER(hv)];
+	/* entry = (HvARRAY(hv))[HvRITER(hv)]; */
+	entry = ((HE**)xhv->xhv_array)[xhv->xhv_riter];
+
+	/* if we have an entry, but it's a placeholder, don't count it */
+	if (entry && HeVAL(entry) == &PL_sv_undef)
+	    entry = 0;
+
     }
 
     if (oldentry && HvLAZYDEL(hv)) {		/* was deleted earlier? */
@@ -1409,7 +1644,7 @@ Perl_hv_iternext(pTHX_ HV *hv)
 	hv_free_ent(hv, oldentry);
     }
 
-    HvEITER(hv) = entry;
+    xhv->xhv_eiter = entry; /* HvEITER(hv) = entry */
     return entry;
 }
 
@@ -1515,19 +1750,23 @@ Perl_hv_magic(pTHX_ HV *hv, GV *gv, int how)
     sv_magic((SV*)hv, (SV*)gv, how, Nullch, 0);
 }
 
+#if 0 /* use the macro from hv.h instead */
+
 char*	
 Perl_sharepvn(pTHX_ const char *sv, I32 len, U32 hash)
 {
     return HEK_KEY(share_hek(sv, len, hash));
 }
 
+#endif
+
 /* possibly free a shared string if no one has access to it
  * len and hash must both be valid for str.
  */
 void
 Perl_unsharepvn(pTHX_ const char *str, I32 len, U32 hash)
 {
-    HV *hv;
+    register XPVHV* xhv;
     register HE *entry;
     register HE **oentry;
     register I32 i = 1;
@@ -1536,14 +1775,11 @@ Perl_unsharepvn(pTHX_ const char *str, I32 len, U32 hash)
     const char *save = str;
 
     if (len < 0) {
-      len = -len;
+      STRLEN tmplen = -len;
       is_utf8 = TRUE;
-      if (!(PL_hints & HINT_UTF8_DISTINCT)) {
-	  STRLEN tmplen = len;
-	  /* See the note in hv_fetch(). --jhi */
-	  str = (char*)bytes_from_utf8((U8*)str, &tmplen, &is_utf8);
-	  len = tmplen;
-      }
+      /* See the note in hv_fetch(). --jhi */
+      str = (char*)bytes_from_utf8((U8*)str, &tmplen, &is_utf8);
+      len = tmplen;
     }
 
     /* what follows is the moral equivalent of:
@@ -1551,10 +1787,11 @@ Perl_unsharepvn(pTHX_ const char *str, I32 len, U32 hash)
 	if (--*Svp == Nullsv)
 	    hv_delete(PL_strtab, str, len, G_DISCARD, hash);
     } */
+    xhv = (XPVHV*)SvANY(PL_strtab);
     /* assert(xhv_array != 0) */
-    hv = PL_strtab;
     LOCK_STRTAB_MUTEX;
-    oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    oentry = &((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     for (entry = *oentry; entry; i=0, oentry = &HeNEXT(entry), entry = *oentry) {
 	if (HeHASH(entry) != hash)		/* strings can't be equal */
 	    continue;
@@ -1568,10 +1805,10 @@ Perl_unsharepvn(pTHX_ const char *str, I32 len, U32 hash)
 	if (--HeVAL(entry) == Nullsv) {
 	    *oentry = HeNEXT(entry);
 	    if (i && !*oentry)
-		HvFILL(hv)--;
+		xhv->xhv_fill--; /* HvFILL(hv)-- */
 	    Safefree(HeKEY_hek(entry));
 	    del_HE(entry);
-	    HvKEYS(hv)--;
+	    xhv->xhv_keys--; /* HvKEYS(hv)-- */
 	}
 	break;
     }
@@ -1589,7 +1826,7 @@ Perl_unsharepvn(pTHX_ const char *str, I32 len, U32 hash)
 HEK *
 Perl_share_hek(pTHX_ const char *str, I32 len, register U32 hash)
 {
-    HV *hv;
+    register XPVHV* xhv;
     register HE *entry;
     register HE **oentry;
     register I32 i = 1;
@@ -1598,25 +1835,23 @@ Perl_share_hek(pTHX_ const char *str, I32 len, register U32 hash)
     const char *save = str;
 
     if (len < 0) {
-      len = -len;
+      STRLEN tmplen = -len;
       is_utf8 = TRUE;
-      if (!(PL_hints & HINT_UTF8_DISTINCT)) {
-	  STRLEN tmplen = len;
-	  /* See the note in hv_fetch(). --jhi */
-	  str = (char*)bytes_from_utf8((U8*)str, &tmplen, &is_utf8);
-	  len = tmplen;
-      }
+      /* See the note in hv_fetch(). --jhi */
+      str = (char*)bytes_from_utf8((U8*)str, &tmplen, &is_utf8);
+      len = tmplen;
     }
 
     /* what follows is the moral equivalent of:
 
     if (!(Svp = hv_fetch(PL_strtab, str, len, FALSE)))
-    	hv_store(PL_strtab, str, len, Nullsv, hash);
+	hv_store(PL_strtab, str, len, Nullsv, hash);
     */
+    xhv = (XPVHV*)SvANY(PL_strtab);
     /* assert(xhv_array != 0) */
-    hv = PL_strtab;
     LOCK_STRTAB_MUTEX;
-    oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)];
+    /* oentry = &(HvARRAY(hv))[hash & (I32) HvMAX(hv)]; */
+    oentry = &((HE**)xhv->xhv_array)[hash & (I32) xhv->xhv_max];
     for (entry = *oentry; entry; i=0, entry = HeNEXT(entry)) {
 	if (HeHASH(entry) != hash)		/* strings can't be equal */
 	    continue;
@@ -1635,11 +1870,11 @@ Perl_share_hek(pTHX_ const char *str, I32 len, register U32 hash)
 	HeVAL(entry) = Nullsv;
 	HeNEXT(entry) = *oentry;
 	*oentry = entry;
-	HvKEYS(hv)++;
+	xhv->xhv_keys++; /* HvKEYS(hv)++ */
 	if (i) {				/* initial entry? */
-	    HvFILL(hv)++;
-	    if (HvKEYS(hv) > HvMAX(hv))
-		hsplit(hv);
+	    xhv->xhv_fill++; /* HvFILL(hv)++ */
+	    if (xhv->xhv_keys > xhv->xhv_max /* HvKEYS(hv) > HvMAX(hv) */)
+		hsplit(PL_strtab);
 	}
     }