+#ifdef PERL_DEBUG_COW
+#define SvIVX(sv) (0 + ((XPVIV*) SvANY(sv))->xiv_iv)
+#define SvUVX(sv) (0 + ((XPVUV*) SvANY(sv))->xuv_uv)
+#define SvNVX(sv) (0 + ((XPVNV*) SvANY(sv))->xnv_nv)
+/* Don't test the core XS code yet. */
+#if defined (PERL_CORE) && PERL_DEBUG_COW > 1
+#define SvPVX(sv) (0 + (assert(!SvREADONLY(sv)), (sv)->sv_u.svu_pv))
+#else
+#define SvPVX(sv) SvPVX_mutable(sv)
+#endif
+#define SvPVX_mutable(sv) (0 + (sv)->sv_u.svu_pv)
+#define SvPVX_const(sv) ((const char*)(0 + (sv)->sv_u.svu_pv))
+#define SvCUR(sv) (0 + ((XPV*) SvANY(sv))->xpv_cur)
+#define SvLEN(sv) (0 + ((XPV*) SvANY(sv))->xpv_len)
+#define SvEND(sv) ((sv)->sv_u.svu_pv + ((XPV*)SvANY(sv))->xpv_cur)
+
+#ifdef DEBUGGING
+# ifdef PERL_IN_SV_C
+/* Can't make this RVALUE because of Perl_sv_unmagic. */
+# define SvMAGIC(sv) (*(assert(SvTYPE(sv) >= SVt_PVMG), &((XPVMG*) SvANY(sv))->xmg_magic))
+# else
+# define SvMAGIC(sv) (0 + *(assert(SvTYPE(sv) >= SVt_PVMG), &((XPVMG*) SvANY(sv))->xmg_magic))
+# endif
+#define SvSTASH(sv) (0 + *(assert(SvTYPE(sv) >= SVt_PVMG), &((XPVMG*) SvANY(sv))->xmg_stash))
+#else
+# ifdef PERL_IN_SV_C
+# define SvMAGIC(sv) ((XPVMG*) SvANY(sv))->xmg_magic
+# else
+# define SvMAGIC(sv) (0 + ((XPVMG*) SvANY(sv))->xmg_magic)
+# endif
+#define SvSTASH(sv) (0 + ((XPVMG*) SvANY(sv))->xmg_stash)
+#endif
+#else
+#define SvIVX(sv) ((XPVIV*) SvANY(sv))->xiv_iv
+#define SvUVX(sv) ((XPVUV*) SvANY(sv))->xuv_uv
+#define SvNVX(sv) ((XPVNV*) SvANY(sv))->xnv_nv
+#define SvPVX(sv) ((sv)->sv_u.svu_pv)
+#define SvPVX_mutable(sv) SvPVX(sv)
+#define SvPVX_const(sv) ((const char*)SvPVX(sv))
+#define SvCUR(sv) ((XPV*) SvANY(sv))->xpv_cur
+#define SvLEN(sv) ((XPV*) SvANY(sv))->xpv_len
+#define SvEND(sv) ((sv)->sv_u.svu_pv + ((XPV*)SvANY(sv))->xpv_cur)
+
+#ifdef DEBUGGING
+#define SvMAGIC(sv) (*(assert(SvTYPE(sv) >= SVt_PVMG), &((XPVMG*) SvANY(sv))->xmg_magic))
+#define SvSTASH(sv) (*(assert(SvTYPE(sv) >= SVt_PVMG), &((XPVMG*) SvANY(sv))->xmg_stash))
+#else
+#define SvMAGIC(sv) ((XPVMG*) SvANY(sv))->xmg_magic
+#define SvSTASH(sv) ((XPVMG*) SvANY(sv))->xmg_stash
+#endif
+
+#endif
+