refactor pp_ref

similar to commmit b3cf48215c

-removed:
  -4/-8 pop on SP
  +4/+8 push on SP
  PUTBACK
  1 non vol register save/restore (TARG not saved across the sv_ref())

TARG is not computed if the SV isn't a reference, so the PL_sv_no branch is
slightly faster. On VC 2003 32 bit miniperl, this func dropped from 0x6D to
0x58 bytes of machine code.

1 files changed, 11 insertions, 6 deletions

diff --git a/pp.c b/pp.c
index 3751bb41ea..bc7c0dfacc 100644
--- a/pp.c
+++ b/pp.c
@@ -586,16 +586,21 @@ S_refto(pTHX_ SV *sv)
 
 PP(pp_ref)
 {
-    dSP; dTARGET;
-    SV * const sv = POPs;
+    dSP;
+    SV * const sv = TOPs;
 
     SvGETMAGIC(sv);
     if (!SvROK(sv))
-	RETPUSHNO;
+	SETs(&PL_sv_no);
+    else {
+	dTARGET;
+	SETs(TARG);
+	/* use the return value that is in a register, its the same as TARG */
+	TARG = sv_ref(TARG,SvRV(sv),TRUE);
+	SvSETMAGIC(TARG);
+    }
 
-    (void)sv_ref(TARG,SvRV(sv),TRUE);
-    PUSHTARG;
-    RETURN;
+    return NORMAL;
 }
 
 PP(pp_bless)