What refcount is kept greater than 1?

This is what happens to scalar lexicals on scope exit: 

848: ptr = (void*)&PL_curpad[SSPOPLONG];
849: sv = *(SV**)ptr;
850: 
858: /* Can clear pad variable in place? */
859: if (SvREFCNT(sv) <= 1 && !SvOBJECT(sv)) {
860:     /*
861:      * if a my variable that was made readonly is going out of
862:      * scope, we want to remove the readonlyness so that it can
863:      * go out of scope quietly
864:      */
865:     if (SvPADMY(sv) && !SvFAKE(sv))
866:         SvREADONLY_off(sv);
867: 
868:     if (SvTHINKFIRST(sv))
869:         sv_force_normal_flags(sv, SV_IMMEDIATE_UNREF);
870:     if (SvMAGICAL(sv))
871:         mg_free(sv);
872: 
885:    SvOK_off(sv);
888:     SvPADSTALE_on(sv); /* mark as no longer live */
889: }
890: else {    /* Someone has a claim on this, so abandon it. */
891:     const U32 padflags = SvFLAGS(sv) & (SVs_PADMY|SVs_PADTMP);
895:     *(SV**)ptr = newSV(0);
897:     SvREFCNT_dec(sv);    /* Cast current value to the winds. */
898:     /* preserve pad nature, but also mark as not live
899:      * for any closure capturing */
900:     SvFLAGS(*(SV**)ptr) |= padflags | SVs_PADSTALE;
901: }

[download]

(Lifted from Perl_leave_scope in scope.c in perl.git.)

Note line 895. It allocates a new value for $x. Lexicals are allocated on scope exit, not on scope entry. That means $x's refcount at scope exit is what's meaningful. Its refcount is not checked on scope entry or when my is executed.

And $x's refcount at scope exit is 2. It is referenced by both the f's pad and the reference. 

>perl -MDevel::Peek -le"sub f{ my $rv = \my $x; Dump($x); $rv } print 
+f() for 1..5"
SV = NULL(0x0) at 0x235fcc
  REFCNT = 2
  FLAGS = (PADBUSY,PADMY)
SCALAR(0x235fcc)
SV = NULL(0x0) at 0x236038
  REFCNT = 2
  FLAGS = (PADBUSY,PADMY)
SCALAR(0x236038)
SV = NULL(0x0) at 0x235fcc
  REFCNT = 2
  FLAGS = (PADBUSY,PADMY)
SCALAR(0x235fcc)
SV = NULL(0x0) at 0x236038
  REFCNT = 2
  FLAGS = (PADBUSY,PADMY)
SCALAR(0x236038)
SV = NULL(0x0) at 0x235fcc
  REFCNT = 2
  FLAGS = (PADBUSY,PADMY)
SCALAR(0x235fcc)

[download]

Your bless doesn't prove anything since the presence of an object forces a reallocation. See line 859.

Update: Added code from scope.c

In reply to Re^6: Reference of constants and literals by ikegami
in thread Reference of constants and literals by LanX

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