policy   ModeMergePolicy
	overflow bool
}

func (cm *Merger) SetModeMergePolicy(policy ModeMergePolicy) {
	cm.policy = policy
}

// MergeCounters takes the counter values in 'src' and merges them
// into 'dst' according to the correct counter mode.
func (m *Merger) MergeCounters(dst, src []uint32) (error, bool) {
	if len(src) != len(dst) {
		return fmt.Errorf("merging counters: len(dst)=%d len(src)=%d", len(dst), len(src)), false
	}

		err = m.SetModeAndGranularity(mdf, scenario.cmode, scenario.cgran)
		if err != nil {
			t.Fatalf("case %d SetModeAndGranularity failed: %v", k, err)
		}
		for i := 0; i < scenario.iters; i++ {
			err, ovf = m.MergeCounters(scenario.dst, scenario.src)
			if ovf != scenario.overflow {
				t.Fatalf("case %d overflow mismatch: got %v want %v", k, ovf, scenario.overflow)
			}
			if !scenario.merr && err != nil {

	}
	if len(val.Counters) < len(data.Counters) {
		t := val.Counters
		val.Counters = mm.AllocateCounters(len(data.Counters))
		copy(val.Counters, t)
	}
	err, overflow := mm.MergeCounters(val.Counters, data.Counters)
	if err != nil {
		fatal("%v", err)
	}
	if overflow {
		warn("uint32 overflow during counter merge")
	}
	mm.pod.pmm[key] = val
}

			}

			// NB: sanity check on pkg and func IDs?
			key := pkfunc{pk: data.PkgIdx, fcn: data.FuncIdx}
			if prev, found := pmm[key]; found {
				// Note: no overflow reporting here.
				if err, _ := ts.cm.MergeCounters(data.Counters, prev); err != nil {
					return fmt.Errorf("processing counter data file %s: %v", cdf, err)
				}
			}
			c := ts.AllocateCounters(len(data.Counters))
			copy(c, data.Counters)
			pmm[key] = c

	if len(val.Counters) < len(data.Counters) {
		t := val.Counters
		val.Counters = d.AllocateCounters(len(data.Counters))
		copy(val.Counters, t)
	}
	err, overflow := d.cm.MergeCounters(val.Counters, data.Counters)
	if err != nil {
		fatal("%v", err)
	}
	if overflow {
		warn("uint32 overflow during counter merge")
	}
	d.mm[key] = val
}

func (d *dstate) EndCounters() {
}