Similiarly Perl_newHV() can become a mathom by making newHV() a

wrapper around newSV_type() and tweaking Perl_sv_upgrade().

p4raw-id: //depot/perl@32676

embed.fnc

@@ -573,7 +573,7 @@ Apa	|OP*	|newGVOP	|I32 type|I32 flags|NN GV* gv
 Apa	|GV*	|newGVgen	|NN const char* pack
 Apa	|OP*	|newGVREF	|I32 type|NULLOK OP* o
 ApaR	|OP*	|newHVREF	|NN OP* o
-ApdaR	|HV*	|newHV
+AmdbaR	|HV*	|newHV
 ApaR	|HV*	|newHVhv	|NULLOK HV* hv
 Apa	|IO*	|newIO
 Apa	|OP*	|newLISTOP	|I32 type|I32 flags|NULLOK OP* first|NULLOK OP* last

hv.c

@@ -1305,30 +1305,6 @@ Perl_hv_ksplit(pTHX_ HV *hv, IV newmax)
     }
 }
 
-/*
-=for apidoc newHV
-
-Creates a new HV.  The reference count is set to 1.
-
-=cut
-*/
-
-HV *
-Perl_newHV(pTHX)
-{
-    register XPVHV* xhv;
-    HV * const hv = (HV*)newSV_type(SVt_PVHV);
-    xhv = (XPVHV*)SvANY(hv);
-    assert(!SvOK(hv));
-#ifndef NODEFAULT_SHAREKEYS
-    HvSHAREKEYS_on(hv);         /* key-sharing on by default */
-#endif
-
-    xhv->xhv_max    = 7;	/* HvMAX(hv) = 7 (start with 8 buckets) */
-    xhv->xhv_fill   = 0;	/* HvFILL(hv) = 0 */
-    return hv;
-}
-
 HV *
 Perl_newHVhv(pTHX_ HV *ohv)
 {

hv.h

@@ -527,6 +527,16 @@ struct refcounted_he {
 #define HV_FETCH_JUST_SV	0x20
 #define HV_DELETE		0x40
 
+/*
+=for apidoc newHV
+
+Creates a new HV.  The reference count is set to 1.
+
+=cut
+*/
+
+#define newHV()	((HV*)newSV_type(SVt_PVHV))
+
 /*
  * Local variables:
  * c-indentation-style: bsd

mathoms.c

@@ -67,6 +67,7 @@ PERL_CALLCONV int Perl_fprintf_nocontext(PerlIO *stream, const char *format, ...
 PERL_CALLCONV int Perl_printf_nocontext(const char *format, ...);
 PERL_CALLCONV int Perl_magic_setglob(pTHX_ SV* sv, MAGIC* mg);
 PERL_CALLCONV AV * Perl_newAV(pTHX);
+PERL_CALLCONV HV * Perl_newHV(pTHX);
 
 /* ref() is now a macro using Perl_doref;
  * this version provided for binary compatibility only.
@@ -1338,6 +1339,15 @@ Perl_newAV(pTHX)
     AvMAX(av) = AvFILLp(av) = -1; */
 }
 
+HV *
+Perl_newHV(pTHX)
+{
+    HV * const hv = (HV*)newSV_type(SVt_PVHV);
+    assert(!SvOK(hv));
+
+    return hv;
+}
+
 #endif /* NO_MATHOMS */
 
 /*

proto.h

@@ -1544,9 +1544,9 @@ PERL_CALLCONV OP*	Perl_newHVREF(pTHX_ OP* o)
 			__attribute__warn_unused_result__
 			__attribute__nonnull__(pTHX_1);
 
-PERL_CALLCONV HV*	Perl_newHV(pTHX)
+/* PERL_CALLCONV HV*	Perl_newHV(pTHX)
 			__attribute__malloc__
-			__attribute__warn_unused_result__;
+			__attribute__warn_unused_result__; */
 
 PERL_CALLCONV HV*	Perl_newHVhv(pTHX_ HV* hv)
 			__attribute__malloc__

sv.c

@@ -1260,6 +1260,20 @@ Perl_sv_upgrade(pTHX_ register SV *sv, svtype new_type)
 		   Lets not write to it, in case it confuses a write-back
 		   cache.  */
 	    }
+	} else {
+	    assert(!SvOK(sv));
+	    SvOK_off(sv);
+#ifndef NODEFAULT_SHAREKEYS
+	    HvSHAREKEYS_on(sv);         /* key-sharing on by default */
+#endif
+	    HvMAX(sv) = 7; /* (start with 8 buckets) */
+	    if (old_type >= SVt_RV) {
+		HvFILL(sv) = 0;
+	    } else {
+		/* It will have been zeroed when the new body was allocated.
+		   Lets not write to it, in case it confuses a write-back
+		   cache.  */
+	    }
 	}
 
 	/* SVt_NULL isn't the only thing upgraded to AV or HV.