+ OPSLAB *slab;
+ OPSLAB *slab2;
+ OPSLOT *slot;
+ OP *o;
+ size_t opsz, space;
+
+ if (!PL_compcv || CvROOT(PL_compcv)
+ || (CvSTART(PL_compcv) && !CvSLABBED(PL_compcv)))
+ return PerlMemShared_calloc(1, sz);
+
+ if (!CvSTART(PL_compcv)) { /* sneak it in here */
+ CvSTART(PL_compcv) =
+ (OP *)(slab = S_new_slab(aTHX_ PERL_SLAB_SIZE));
+ CvSLABBED_on(PL_compcv);
+ slab->opslab_refcnt = 2; /* one for the CV; one for the new OP */
+ }
+ else ++(slab = (OPSLAB *)CvSTART(PL_compcv))->opslab_refcnt;
+
+ opsz = SIZE_TO_PSIZE(sz);
+ sz = opsz + OPSLOT_HEADER_P;
+
+ if (slab->opslab_freed) {
+ OP **too = &slab->opslab_freed;
+ o = *too;
+ DEBUG_S_warn((aTHX_ "found free op at %p, slab %p", o, slab));
+ while (o && DIFF(OpSLOT(o), OpSLOT(o)->opslot_next) < sz) {
+ DEBUG_S_warn((aTHX_ "Alas! too small"));
+ o = *(too = &o->op_next);
+ if (o) { DEBUG_S_warn((aTHX_ "found another free op at %p", o)); }
+ }
+ if (o) {
+ *too = o->op_next;
+ Zero(o, opsz, I32 *);
+ o->op_slabbed = 1;
+ return (void *)o;
+ }
+ }
+
+#define INIT_OPSLOT \
+ slot->opslot_slab = slab; \
+ slot->opslot_next = slab2->opslab_first; \
+ slab2->opslab_first = slot; \
+ o = &slot->opslot_op; \
+ o->op_slabbed = 1
+
+ /* The partially-filled slab is next in the chain. */
+ slab2 = slab->opslab_next ? slab->opslab_next : slab;
+ if ((space = DIFF(&slab2->opslab_slots, slab2->opslab_first)) < sz) {
+ /* Remaining space is too small. */
+
+ /* If we can fit a BASEOP, add it to the free chain, so as not
+ to waste it. */
+ if (space >= SIZE_TO_PSIZE(sizeof(OP)) + OPSLOT_HEADER_P) {
+ slot = &slab2->opslab_slots;
+ INIT_OPSLOT;
+ o->op_type = OP_FREED;
+ o->op_next = slab->opslab_freed;
+ slab->opslab_freed = o;
+ }
+
+ /* Create a new slab. Make this one twice as big. */
+ slot = slab2->opslab_first;
+ while (slot->opslot_next) slot = slot->opslot_next;
+ slab2 = S_new_slab(aTHX_
+ (DIFF(slab2, slot)+1)*2 > PERL_MAX_SLAB_SIZE
+ ? PERL_MAX_SLAB_SIZE
+ : (DIFF(slab2, slot)+1)*2);
+ slab2->opslab_next = slab->opslab_next;
+ slab->opslab_next = slab2;
+ }
+ assert(DIFF(&slab2->opslab_slots, slab2->opslab_first) >= sz);
+
+ /* Create a new op slot */
+ slot = (OPSLOT *)((I32 **)slab2->opslab_first - sz);
+ assert(slot >= &slab2->opslab_slots);
+ if (DIFF(&slab2->opslab_slots, slot)
+ < SIZE_TO_PSIZE(sizeof(OP)) + OPSLOT_HEADER_P)
+ slot = &slab2->opslab_slots;
+ INIT_OPSLOT;
+ DEBUG_S_warn((aTHX_ "allocating op at %p, slab %p", o, slab));
+ return (void *)o;
+}
+
+#undef INIT_OPSLOT
+