Use a HEK to store the GV's name, rather than a malloc()ed string.

Saves 1 word in each GV (no more strlen), and will also save the memory
used by the string itself, as the HEK will exist already due to the
key used by the symbol table for this GV.

p4raw-id: //depot/perl@27379

4 files changed, 25 insertions, 22 deletions

diff --git a/gv.c b/gv.c
index f6c2087ce6..8b3b099f32 100644
--- a/gv.c
+++ b/gv.c
@@ -2107,11 +2107,15 @@ void
 Perl_gv_name_set(pTHX_ GV *gv, const char *name, U32 len, U32 flags)
 {
     dVAR;
+    U32 hash;
 
     PERL_UNUSED_ARG(flags);
 
-    GvXPVGV(gv)->xgv_name = name ? savepvn(name, len) : NULL;
-    GvXPVGV(gv)->xgv_namelen = len;
+    if (len > I32_MAX)
+	Perl_croak(aTHX_ "panic: gv name too long (%"UVuf")", (UV) len);
+
+    PERL_HASH(hash, name, len);
+    GvXPVGV(gv)->xgv_namehek = name ? share_hek(name, len, hash) : 0;
 }
 
 /*
diff --git a/gv.h b/gv.h
index de8ec52dd8..c4e26c3024 100644
--- a/gv.h
+++ b/gv.h
@@ -43,26 +43,22 @@ struct gp {
 	    assert(SvTYPE(_gv) == SVt_PVGV || SvTYPE(_gv) >= SVt_PVLV);	\
 	    &(GvXPVGV(_gv)->xnv_u.xgv_stash);				\
 	 }))
-#  define GvNAME_get(gv)						\
-	({ GV * const zzzz = (GV *) (gv);				\
+#  define GvNAME_HEK(gv)						\
+	(*({ GV * const zzzz = (GV *) (gv);				\
 	   assert(isGV_with_GP(zzzz));					\
 	   assert(SvTYPE(zzzz) == SVt_PVGV || SvTYPE(zzzz) >= SVt_PVLV); \
-	   0 + (GvXPVGV(zzzz)->xgv_name);				\
-	 })
-#  define GvNAMELEN_get(gv)						\
-	({ GV * const glank = (GV *) (gv);				\
-	   assert(isGV_with_GP(glank));				\
-	   assert(SvTYPE(glank) == SVt_PVGV || SvTYPE(glank) >= SVt_PVLV); \
-	   0 + (GvXPVGV(glank)->xgv_namelen);				\
-	 })
+	   &(GvXPVGV(zzzz)->xgv_namehek);				\
+	 }))
 #else
 #  define GvGP(gv)	((gv)->sv_u.svu_gp)
 #  define GvFLAGS(gv)	(GvXPVGV(gv)->xpv_cur)
 #  define GvSTASH(gv)	(GvXPVGV(gv)->xnv_u.xgv_stash)
-#  define GvNAME_get(gv)	(0 + GvXPVGV(gv)->xgv_name)
-#  define GvNAMELEN_get(gv)	(0 + GvXPVGV(gv)->xgv_namelen)
+#  define GvNAME_HEK(gv)	(GvXPVGV(gv)->xgv_namehek)
 #endif
 
+#define GvNAME_get(gv)		(GvNAME_HEK(gv) ? HEK_KEY(GvNAME_HEK(gv)) : 0)
+#define GvNAMELEN_get(gv)	(GvNAME_HEK(gv) ? HEK_LEN(GvNAME_HEK(gv)) : 0)
+
 #define GvNAME(gv)	GvNAME_get(gv)
 #define GvNAMELEN(gv)	GvNAMELEN_get(gv)
 
diff --git a/sv.c b/sv.c
index 74e6a8bf9a..17d8cc2069 100644
--- a/sv.c
+++ b/sv.c
@@ -3216,7 +3216,7 @@ S_glob_assign_glob(pTHX_ SV *dstr, SV *sstr, const int dtype)
 	GvSTASH(dstr) = GvSTASH(sstr);
 	if (GvSTASH(dstr))
 	    Perl_sv_add_backref(aTHX_ (SV*)GvSTASH(dstr), dstr);
-	gv_name_set(dstr, name, len, 0);
+	gv_name_set((GV *)dstr, name, len, 0);
 	SvFAKE_on(dstr);	/* can coerce to non-glob */
     }
 
@@ -5111,7 +5111,9 @@ Perl_sv_clear(pTHX_ register SV *sv)
 	goto freescalar;
     case SVt_PVGV:
 	gp_free((GV*)sv);
-	Safefree(GvNAME(sv));
+	if (GvNAME_HEK(sv)) {
+	    unshare_hek(GvNAME_HEK(sv));
+	}
 	/* If we're in a stash, we don't own a reference to it. However it does
 	   have a back reference to us, which needs to be cleared.  */
 	if (GvSTASH(sv))
@@ -7715,7 +7717,9 @@ S_sv_unglob(pTHX_ SV *sv)
 	GvSTASH(sv) = NULL;
     }
     GvMULTI_off(sv);
-    Safefree(GvNAME(sv));
+    if (GvNAME_HEK(sv)) {
+	unshare_hek(GvNAME_HEK(sv));
+    }
     SvSCREAM_off(sv);
 
     /* need to keep SvANY(sv) in the right arena */
@@ -9836,7 +9840,8 @@ Perl_sv_dup(pTHX_ const SV *sstr, CLONE_PARAMS* param)
 		    LvTARG(dstr) = sv_dup_inc(LvTARG(dstr), param);
 		break;
 	    case SVt_PVGV:
-		GvXPVGV(dstr)->xgv_name	= SAVEPVN(GvNAME(dstr), GvNAMELEN(dstr));
+		if (GvNAME_HEK(dstr))
+		    GvNAME_HEK(dstr) = hek_dup(GvNAME_HEK(dstr), param);
 
 		/* Don't call sv_add_backref here as it's going to be created
 		   as part of the magic cloning of the symbol table.  */
diff --git a/sv.h b/sv.h
index 50f11e0e13..7a63afc1ed 100644
--- a/sv.h
+++ b/sv.h
@@ -487,8 +487,7 @@ struct xpvlv {
     HV*		xmg_stash;	/* class package */
 
     /* a full glob fits into this */
-    char*	xgv_name;
-    STRLEN	xgv_namelen;
+    HEK *	xgv_namehek;
 
     STRLEN	xlv_targoff;
     STRLEN	xlv_targlen;
@@ -516,8 +515,7 @@ struct xpvgv {
     } xmg_u;
     HV*		xmg_stash;	/* class package */
 
-    char*	xgv_name;
-    STRLEN	xgv_namelen;
+    HEK *	xgv_namehek;
 };
 
 struct xpvbm {