padrange: handle @_ directly

In a construct like
    my ($x,$y) = @_
the pushmark/padsv/padsv is already optimised into a single padrange
op. This commit makes the OPf_SPECIAL flag on the padrange op indicate
that in addition, @_ should be pushed onto the stack, skipping an
additional pushmark/gv[*_]/rv2sv combination.

So in total (including the earlier padrange work), the above construct
goes from being

    3  <0> pushmark s
    4  <$> gv(*_) s
    5  <1> rv2av[t3] lK/1
    6  <0> pushmark sRM*/128
    7  <0> padsv[$x:1,2] lRM*/LVINTRO
    8  <0> padsv[$y:1,2] lRM*/LVINTRO
    9  <2> aassign[t4] vKS

to

    3  <0> padrange[$x:1,2; $y:1,2] l*/LVINTRO,2 ->4
    4  <2> aassign[t4] vKS

1 files changed, 40 insertions, 17 deletions

diff --git a/pp_hot.c b/pp_hot.c
index 0ef64f313b..b5551bf2de 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -306,6 +306,35 @@ PP(pp_concat)
   }
 }
 
+/* push the elements of av onto the stack.
+ * XXX Note that padav has similar code but without the mg_get().
+ * I suspect that the mg_get is no longer needed, but while padav
+ * differs, it can't share this function */
+
+void
+S_pushav(pTHX_ AV* const av)
+{
+    dSP;
+    const I32 maxarg = AvFILL(av) + 1;
+    EXTEND(SP, maxarg);
+    if (SvRMAGICAL(av)) {
+        U32 i;
+        for (i=0; i < (U32)maxarg; i++) {
+            SV ** const svp = av_fetch(av, i, FALSE);
+            /* See note in pp_helem, and bug id #27839 */
+            SP[i+1] = svp
+                ? SvGMAGICAL(*svp) ? (mg_get(*svp), *svp) : *svp
+                : &PL_sv_undef;
+        }
+    }
+    else {
+        Copy(AvARRAY(av), SP+1, maxarg, SV*);
+    }
+    SP += maxarg;
+    PUTBACK;
+}
+
+
 /* ($lex1,@lex2,...)   or my ($lex1,@lex2,...)  */
 
 PP(pp_padrange)
@@ -314,6 +343,13 @@ PP(pp_padrange)
     PADOFFSET base = PL_op->op_targ;
     int count = (int)(PL_op->op_private) & OPpPADRANGE_COUNTMASK;
     int i;
+    if (PL_op->op_flags & OPf_SPECIAL) {
+        /* fake the RHS of my ($x,$y,..) = @_ */
+        PUSHMARK(SP);
+        S_pushav(aTHX_ GvAVn(PL_defgv));
+        SPAGAIN;
+    }
+
     /* note, this is only skipped for compile-time-known void cxt */
     if ((PL_op->op_flags & OPf_WANT) != OPf_WANT_VOID) {
         EXTEND(SP, count);
@@ -850,23 +886,10 @@ PP(pp_rv2av)
 	   (until such time as we get tools that can do blame annotation across
 	   whitespace changes.  */
 	if (gimme == G_ARRAY) {
-	    const I32 maxarg = AvFILL(av) + 1;
-	    (void)POPs;			/* XXXX May be optimized away? */
-	    EXTEND(SP, maxarg);
-	    if (SvRMAGICAL(av)) {
-		U32 i;
-		for (i=0; i < (U32)maxarg; i++) {
-		    SV ** const svp = av_fetch(av, i, FALSE);
-		    /* See note in pp_helem, and bug id #27839 */
-		    SP[i+1] = svp
-			? SvGMAGICAL(*svp) ? (mg_get(*svp), *svp) : *svp
-			: &PL_sv_undef;
-		}
-	    }
-	    else {
-		Copy(AvARRAY(av), SP+1, maxarg, SV*);
-	    }
-	    SP += maxarg;
+            SP--;
+            PUTBACK;
+            S_pushav(aTHX_ av);
+            SPAGAIN;
 	}
 	else if (gimme == G_SCALAR) {
 	    dTARGET;