- if ( top -> link == 0 ) {
- top -> link = ++tos[0].link;
- if ( top -> link >= tolimit )
- goto overflow;
- top = &tos[ top -> link ];
- top -> selfpc = selfpc;
- top -> count = 1;
- top -> link = 0;
- goto done;
+ top = &tos[toindex];
+ if (top->selfpc == selfpc) {
+ /*
+ * arc at front of chain; usual case.
+ */
+ top->count++;
+ goto done;
+ }
+ /*
+ * have to go looking down chain for it.
+ * top points to what we are looking at,
+ * prevtop points to previous top.
+ * we know it is not at the head of the chain.
+ */
+ for (; /* goto done */; ) {
+ if (top->link == 0) {
+ /*
+ * top is end of the chain and none of the chain
+ * had top->selfpc == selfpc.
+ * so we allocate a new tostruct
+ * and link it to the head of the chain.
+ */
+ toindex = ++tos[0].link;
+ if (toindex >= tolimit) {
+ goto overflow;
+ }
+ top = &tos[toindex];
+ top->selfpc = selfpc;
+ top->count = 1;
+ top->link = *frompcindex;
+ *frompcindex = toindex;
+ goto done;
+ }
+ /*
+ * otherwise, check the next arc on the chain.
+ */
+ prevtop = top;
+ top = &tos[top->link];
+ if (top->selfpc == selfpc) {
+ /*
+ * there it is.
+ * increment its count
+ * move it to the head of the chain.
+ */
+ top->count++;
+ toindex = prevtop->link;
+ prevtop->link = top->link;
+ top->link = *frompcindex;
+ *frompcindex = toindex;
+ goto done;
+ }
+