Provide share_hek_hek, and use it for fast copying of shared string

scalars.

p4raw-id: //depot/perl@24811

diff --git a/hv.h b/hv.h
index ac4bdd3..6378a02 100644 (file)
--- a/hv.h
+++ b/hv.h
@@ -364,6 +364,13 @@ C<SV*>.
 #define Perl_sharepvn(sv, len, hash) HEK_KEY(share_hek(sv, len, hash))
 #define sharepvn(sv, len, hash)             Perl_sharepvn(sv, len, hash)
 
+#define share_hek_hek(hek)                                             \
+    (++(((struct shared_he *)(((char *)hek)                            \
+                             - STRUCT_OFFSET(struct shared_he,         \
+                                             shared_he_hek)))          \
+       ->shared_he_he.hent_val),                                       \
+     hek)
+
 /*
  * Local variables:
  * c-indentation-style: bsd

diff --git a/sv.c b/sv.c
index 2f01005..db5a2e0 100644 (file)
--- a/sv.c
+++ b/sv.c
@@ -4562,15 +4562,12 @@ Perl_sv_setsv_flags(pTHX_ SV *dstr, register SV *sstr, I32 flags)
 #endif
                {
                     /* SvIsCOW_shared_hash */
-                    UV hash = SvSHARED_HASH(sstr);
                     DEBUG_C(PerlIO_printf(Perl_debug_log,
                                           "Copy on write: Sharing hash\n"));
 
                    assert (SvTYPE(dstr) >= SVt_PV);
-                   /* FIXME - would benefit from share_hek_hek  */
                     SvPV_set(dstr,
-                             sharepvn(SvPVX_const(sstr),
-                                      (sflags & SVf_UTF8?-cur:cur), hash));
+                            HEK_KEY(share_hek_hek(SvSHARED_HEK_FROM_PV(SvPVX_const(sstr)))));
                }
                 SvLEN_set(dstr, len);
                 SvCUR_set(dstr, cur);
@@ -4708,11 +4705,9 @@ Perl_sv_setsv_cow(pTHX_ SV *dstr, SV *sstr)
 
        if (SvLEN(sstr) == 0) {
            /* source is a COW shared hash key.  */
-           UV hash = SvSHARED_HASH(sstr);
            DEBUG_C(PerlIO_printf(Perl_debug_log,
                                  "Fast copy on write: Sharing hash\n"));
-           /* FIXME - would benefit from share_hek_hek  */
-           new_pv = sharepvn(SvPVX_const(sstr), (SvUTF8(sstr)?-cur:cur), hash);
+           new_pv = HEK_KEY(share_hek_hek(SvSHARED_HEK_FROM_PV(SvPVX_const(sstr))));
            goto common_exit;
        }
        SV_COW_NEXT_SV_SET(dstr, SV_COW_NEXT_SV(sstr));