if w != nil {
				// two witnesses, need a phi value
				v.Op = ssa.OpPhi
				v.AddArgs(args...)
				v.Aux = nil
				continue loop
			}
			w = a // save witness
		}
		if w == nil {
			s.s.Fatalf("no witness for reachable phi %s", v)
		}
		// One witness. Make v a copy of w.
		v.Op = ssa.OpCopy
		v.Aux = nil
		v.AddArg(w)
	}
}

// lookupVarOutgoing finds the variable's value at the end of block b.

			t.RegionID = Region(x.region)
		}
		return true
	}
	return false
}

// Maximize returns a new tag with missing tags filled in.
func (t Tag) Maximize() (Tag, error) {
	return addTags(t)
}

func addTags(t Tag) (Tag, error) {
	// We leave private use identifiers alone.
	if t.IsPrivateUse() {
		return t, nil
	}
	if t.ScriptID != 0 && t.RegionID != 0 {
		if t.LangID != 0 {
			// already fully specified

    new_block->addArguments(op->getOperandTypes(),
                            SmallVector<Location>(op->getNumOperands(), loc));
    for (const auto &idx_args : llvm::enumerate(new_block->getArguments())) {
      inner_op->setOperand(idx_args.index(), idx_args.value());
    }
    custom_op->setAttrs(inner_op->getAttrs());
    builder.create<YieldOp>(loc, inner_op->getResults());
    custom_op.getBody().takeBody(region);

			// this handles all other uses of v.
			argP, argQ := v.Args[cidx], v.Args[1^cidx]
			u.replaceUses(v, argQ)
			phi := t.Func.newValue(OpPhi, v.Type, t, v.Pos)
			phi.AddArg2(argQ, argP)
			t.replaceUses(v, phi)
			if v.Uses == 0 {
				return
			}
			v.moveTo(m, i)
			// The phi in m belongs to whichever pred idx corresponds to t.
			if m.Preds[0].b == t {

	}
	v.AddArg(a)

	cvt := v.Block.NewValue1(v.Pos, OpCvtBoolToUint8, v.Block.Func.Config.Types.UInt8, a)
	switch v.Type.Size() {
	case 1:
		v.reset(OpCopy)
	case 2:
		v.reset(OpZeroExt8to16)
	case 4:
		v.reset(OpZeroExt8to32)
	case 8:
		v.reset(OpZeroExt8to64)
	default:
		v.Fatalf("bad int size %d", v.Type.Size())
	}
	v.AddArg(cvt)

	f := b0.Func

		e = len(a.steps)
	} else {
		e = a.valueStart[i+1]
	}
	return a.steps[s:e]
}

// addArg extends the abiSeq with a new Go value of type t.
//
// If the value was stack-assigned, returns the single
// abiStep describing that translation, and nil otherwise.
func (a *abiSeq) addArg(t *abi.Type) *abiStep {
	// We'll always be adding a new value, so do that first.
	pStart := len(a.steps)

		if !canSpeculativelyExecute(b) {
			return false
		}

		// Logically combine the control values for p and b.
		v := b.NewValue0(bc.Pos, op, bc.Type)
		v.AddArg(pc)
		v.AddArg(bc)

		// Set the combined control value as the control value for b.
		b.SetControl(v)

		// Modify p so that it jumps directly to b.
		p.removeEdge(i)
		p.Kind = BlockPlain
		p.Likely = BranchUnknown

		if t.RegionID == 0 && t.ScriptID != 0 && t.LangID != 0 {
			base, _ := addTags(Tag{LangID: t.LangID})
			if base.ScriptID == t.ScriptID {
				return Tag{LangID: t.LangID}
			}
		}
		return t
	}
	if t.LangID != 0 {
		if t.RegionID != 0 {
			maxScript := t.ScriptID
			if maxScript == 0 {
				max, _ := addTags(t)
				maxScript = max.ScriptID
			}

			for i := range parents {

				// Fix up child to have one more predecessor.
				child.Preds = append(child.Preds, Edge{p, pk.i})
				ai := b.Succs[out].i
				for _, v := range child.Values {
					if v.Op != OpPhi {
						continue
					}
					v.AddArg(v.Args[ai])
				}
				if b.Func.pass.debug > 0 {
					b.Func.Warnl(b.Controls[0].Pos, "Redirect %s based on %s", b.Controls[0].Op, p.Controls[0].Op)
				}
				changed = true
				k--
				break
			}

		mem1 := sched.NewValue1I(bb.Pos, OpSelectN, types.TypeMem, 0, call)
		sched.AddEdgeTo(h)
		headerMemPhi.AddArg(mem1)

		bb.Succs[p.i] = Edge{test, 0}
		test.Preds = append(test.Preds, Edge{bb, p.i})

		// Must correct all the other phi functions in the header for new incoming edge.