Reduce malloc&free for S_parse_gv_stash_name

atoomic · tonycoz · commit f8ac814f18bf · 2017-09-05T09:37:43.000+10:00
S_parse_gv_stash_name was using multiple malloc
and free when using ' as package separator.
We can malloc &amp; free only once the tmpbuffer as we know the size max.
This is also sligthly improving iterations when using ::
as we do not need to check if we need to free the tmp buffer.

This is also saving an extra '*gv &amp;&amp; *gv != (const GV *)&amp;PL_sv_undef' check.
diff --git a/gv.c b/gv.c
@@ -1595,6 +1595,7 @@ S_parse_gv_stash_name(pTHX_ HV **stash, GV **gv, const char **name,
                STRLEN *len, const char *nambeg, STRLEN full_len,
                const U32 is_utf8, const I32 add)
 {
+    char *tmpbuf = NULL;
     const char *name_cursor;
     const char *const name_end = nambeg + full_len;
     const char *const name_em1 = name_end - 1;
@@ -1627,26 +1628,25 @@ S_parse_gv_stash_name(pTHX_ HV **stash, GV **gv, const char **name,
                     key = *name;
                     *len += 2;
                 }
-                else {
-                    char *tmpbuf;
-                    Newx(tmpbuf, *len+2, char);
+                else { /* using ' for package separator */
+                    if (tmpbuf == NULL) /* only malloc&free once, a little more than needed */
+                        Newx(tmpbuf, full_len+2, char);
                     Copy(*name, tmpbuf, *len, char);
                     tmpbuf[(*len)++] = ':';
                     tmpbuf[(*len)++] = ':';
                     key = tmpbuf;
                 }
                 gvp = (GV**)hv_fetch(*stash, key, is_utf8 ? -((I32)*len) : (I32)*len, add);
                 *gv = gvp ? *gvp : NULL;
-                if (*gv && *gv != (const GV *)&PL_sv_undef) {
-                    if (SvTYPE(*gv) != SVt_PVGV)
-                        gv_init_pvn(*gv, *stash, key, *len, (add & GV_ADDMULTI)|is_utf8);
-                    else
-                        GvMULTI_on(*gv);
-                }
-                if (key != *name)
-                    Safefree(key);
-                if (!*gv || *gv == (const GV *)&PL_sv_undef)
+                if (!*gv || *gv == (const GV *)&PL_sv_undef) {
+                    Safefree(tmpbuf);
                     return FALSE;
+                }
+                /* here we know that *gv && *gv != &PL_sv_undef */
+                if (SvTYPE(*gv) != SVt_PVGV)
+                    gv_init_pvn(*gv, *stash, key, *len, (add & GV_ADDMULTI)|is_utf8);
+                else
+                    GvMULTI_on(*gv);
 
                 if (!(*stash = GvHV(*gv))) {
                     *stash = GvHV(*gv) = newHV();
@@ -1681,6 +1681,7 @@ S_parse_gv_stash_name(pTHX_ HV **stash, GV **gv, const char **name,
 			    MUTABLE_HV(SvREFCNT_inc_simple(PL_defstash));
 		    }
 		}
+                Safefree(tmpbuf);
                 return TRUE;
             }
         }
