s.interfere = s.interfere[:n]
	} else {
		s.interfere = make([][]ID, n)
	}
	live := f.newSparseSet(f.NumValues())
	defer f.retSparseSet(live)
	for _, b := range f.Blocks {
		// Propagate liveness backwards to the start of the block.
		// Two values interfere if one is defined while the other is live.
		live.clear()
		live.addAll(s.live[b.ID])
		for i := len(b.Values) - 1; i >= 0; i-- {
			v := b.Values[i]

// candidate variable), by making a
// backwards sweep and invoking the Live/Kill methods to note the
// starts and end of a given lifetime. For the example above, we would
// expect to see this sequence of calls to Live/Kill:
//
//    abc:  Live(9), Kill(8), Live(6), Kill(0)
//    xyz:  Live(8), Kill(2)

import (
	"fmt"
	"os"
	"strings"
)

const debugtrace = false

			// Check to make sure only input variables are live.
			for i, n := range lv.vars {
				if !liveout.Get(int32(i)) {
					continue
				}
				if n.Class == ir.PPARAM {
					continue // ok
				}
				base.FatalfAt(n.Pos(), "bad live variable at entry of %v: %L", lv.fn.Nname, n)
			}

			// Record live variables.
			live := &lv.livevars[index]
			live.Or(*live, liveout)
		}

		if lv.doClobber {

				f.Fatalf("memory is first in a tuple: %s\n", v.LongString())
			}
		}
	}

	// Single live memory checks.
	// These checks only work if there are no memory copies.
	// (Memory copies introduce ambiguity about which mem value is really live.
	// probably fixable, but it's easier to avoid the problem.)
	// For the same reason, disable this check if some memory ops are unused.

	if len(lines) == 1 && lines[0] == "" {
		lines = nil
	}
	return lines
}

func testDump(t *testing.T, s state) {
	// Run the dumper on the two dirs we generated.
	dargs := []string{"-pkg=" + mainPkgPath, "-live", "-i=" + s.outdirs[0] + "," + s.outdirs[1]}
	lines := runToolOp(t, s, "debugdump", dargs)

	// Sift through the output to make sure it has some key elements.
	testpoints := []struct {
		tag string

func makeDumpOp(cmd string) covOperation {
	if cmd == textfmtMode || cmd == percentMode {
		textfmtoutflag = flag.String("o", "", "Output text format to file")
	}
	if cmd == debugDumpMode {
		liveflag = flag.Bool("live", false, "Select only live (executed) functions for dump output.")
	}
	d := &dstate{
		cmd: cmd,
		cm:  &cmerge.Merger{},
	}
	// For these modes (percent, pkglist, func, etc), use a relaxed

		// or the other of hp and hu as the loop proceeds.
		//
		// hp is live during most of the body of the loop. But it isn't live
		// at the very top of the loop, when we haven't checked i<n yet, and
		// it could point off the end of the backing store.
		// hu is live only at the very top and very bottom of the loop.
		// In particular, only when it cannot possibly be live across a call.
		//
		// So we do

	// reusable priority queue
	priq := new(ValHeap)

	// "priority" for a value
	score := f.Cache.allocInt8Slice(f.NumValues())
	defer f.Cache.freeInt8Slice(score)

	// maps mem values to the next live memory value
	nextMem := f.Cache.allocValueSlice(f.NumValues())
	defer f.Cache.freeValueSlice(nextMem)

	// inBlockUses records whether a value is used in the block

		v := s.fwdrefs[len(s.fwdrefs)-1]
		s.fwdrefs = s.fwdrefs[:len(s.fwdrefs)-1]
		b := v.Block
		var_ := v.Aux.(fwdRefAux).N
		if b == s.f.Entry {
			// No variable should be live at entry.
			s.s.Fatalf("value %v (%v) incorrectly live at entry", var_, v)
		}
		if !s.reachable[b.ID] {
			// This block is dead.
			// It doesn't matter what we use here as long as it is well-formed.
			v.Op = ssa.OpUnknown
			v.Aux = nil

	ic := &calls.Calls[slot]
	if ic.InlIndex == -2 {
		return true
	}
	live := false
	for _, k := range ic.Children {
		if !isEmptyInlinedCall(k, calls) {
			live = true
		}
	}
	if len(ic.Ranges) > 0 {
		live = true
	}
	if !live {
		ic.InlIndex = -2
	}
	return !live
}

// Slot -1:    return top-level inlines.
// Slot >= 0:  return children of that slot.