Re: pre extending hash? - need speed

The patch below (which is relative to perl5.001l) implements
"keys %hash = 50_000;" (or other integer-evaluable sizes) for
pre-sizing hashes.  I've only moved the patch forward from
when I first did it.  I'm sure the code in hv_ksplit could be
improved.

diff --git a/doop.c b/doop.c
index 470ec06..0d8538c 100644 (file)
--- a/doop.c
+++ b/doop.c
@@ -629,8 +629,15 @@ dARGS
     if (op->op_type == OP_RV2HV || op->op_type == OP_PADHV) 
        dokeys = dovalues = TRUE;
 
-    if (!hv)
+    if (!hv) {
+       if (op->op_flags & OPf_MOD) {   /* lvalue */
+           dTARGET;            /* make sure to clear its target here */
+           if (SvTYPE(TARG) == SVt_PVLV)
+               LvTARG(TARG) = Nullsv;
+           PUSHs(TARG);
+       }
        RETURN;
+    }
 
     (void)hv_iterinit(hv);     /* always reset iterator regardless */
 
@@ -638,6 +645,17 @@ dARGS
        I32 i;
        dTARGET;
 
+       if (op->op_flags & OPf_MOD) {   /* lvalue */
+           if (SvTYPE(TARG) < SVt_PVLV) {
+               sv_upgrade(TARG, SVt_PVLV);
+               sv_magic(TARG, Nullsv, 'k', Nullch, 0);
+           }
+           LvTYPE(TARG) = 'k';
+           LvTARG(TARG) = (SV*)hv;
+           PUSHs(TARG);
+           RETURN;
+       }
+
        if (!SvRMAGICAL(hv) || !mg_find((SV*)hv,'P'))
            i = HvKEYS(hv);
        else {