Yes, thanks. But that doesn't get you very far.

c:\test\perl-5.14.0-RC1>findstr SvLOCK *.?
pp.c:    SvLOCK(sv);
sv.h:=for apidoc Am|void|SvLOCK|SV* sv
sv.h:#define SvLOCK(sv) PL_lockhook(aTHX_ sv)

c:\test\perl-5.14.0-RC1>findstr PL_lockhook *.?
embedvar.h:#define PL_lockhook          (vTHX->Ilockhook)
embedvar.h:#define PL_Ilockhook         PL_lockhook
sv.c:    PL_lockhook            = proto_perl->Ilockhook;
sv.h:#define SvLOCK(sv) PL_lockhook(aTHX_ sv)

c:\test\perl-5.14.0-RC1>findstr Ilockhook *.?
embedvar.h:#define PL_lockhook          (vTHX->Ilockhook)
embedvar.h:#define PL_Ilockhook         PL_lockhook
intrpvar.h:PERLVARI(Ilockhook,  share_proc_t,   Perl_sv_nosharing)
sv.c:    PL_lockhook            = proto_perl->Ilockhook;
[download]

The whole 'lock locks the variable if threading is enable but is a silent noop otherwise', is the single most pointless piece of logic ever. (After the over-elaborate feature mechanism that is.)