-#else
-#define NewOp(m, var, c, type) \
- (var = (MEM_WRAP_CHECK_(c,type) \
- (type*)PerlMemShared_calloc(c, sizeof(type))))
-#define NewOpSz(m, var, size) \
- (var = (OP*)PerlMemShared_calloc(1, size))
-#define FreeOp(p) PerlMemShared_free(p)
+
+/*
+ * The per-CV op slabs consist of a header (the opslab struct) and a bunch
+ * of space for allocating op slots, each of which consists of two pointers
+ * followed by an op. The first pointer points to the next op slot. The
+ * second points to the slab. At the end of the slab is a null pointer,
+ * so that slot->opslot_next - slot can be used to determine the size
+ * of the op.
+ *
+ * Each CV can have multiple slabs; opslab_next points to the next slab, to
+ * form a chain. All bookkeeping is done on the first slab, which is where
+ * all the op slots point.
+ *
+ * Freed ops are marked as freed and attached to the freed chain
+ * via op_next pointers.
+ *
+ * When there is more than one slab, the second slab in the slab chain is
+ * assumed to be the one with free space available. It is used when allo-
+ * cating an op if there are no freed ops available or big enough.
+ */
+
+#if !defined(PL_OP_SLAB_ALLOC) && defined(PERL_CORE)
+struct opslot {
+ /* keep opslot_next first */
+ OPSLOT * opslot_next; /* next slot */
+ OPSLAB * opslot_slab; /* owner */
+ OP opslot_op; /* the op itself */
+};
+
+struct opslab {
+ OPSLOT * opslab_first; /* first op in this slab */
+ OPSLAB * opslab_next; /* next slab */
+ OP * opslab_freed; /* chain of freed ops */
+ size_t opslab_refcnt; /* number of ops */
+ OPSLOT opslab_slots; /* slots begin here */
+};
+
+# define OPSLOT_HEADER STRUCT_OFFSET(OPSLOT, opslot_op)
+# define OPSLOT_HEADER_P (OPSLOT_HEADER/sizeof(I32 *))
+# ifdef DEBUGGING
+# define OpSLOT(o) (assert(o->op_slabbed), \
+ (OPSLOT *)(((char *)o)-OPSLOT_HEADER))
+# else
+# define OpSLOT(o) ((OPSLOT *)(((char *)o)-OPSLOT_HEADER))
+# endif
+# define OpSLAB(o) OpSLOT(o)->opslot_slab
+# define OpslabREFCNT_dec(slab) \
+ (((slab)->opslab_refcnt == 1) \
+ ? opslab_free_nopad(slab) \
+ : (void)--(slab)->opslab_refcnt)
+ /* Variant that does not null out the pads */
+# define OpslabREFCNT_dec_padok(slab) \
+ (((slab)->opslab_refcnt == 1) \
+ ? opslab_free(slab) \
+ : (void)--(slab)->opslab_refcnt)