}

		for _, v := range b.Values {
			// Check to make sure argument count makes sense (argLen of -1 indicates
			// variable length args)
			nArgs := opcodeTable[v.Op].argLen
			if nArgs != -1 && int32(len(v.Args)) != nArgs {
				f.Fatalf("value %s has %d args, expected %d", v.LongString(),
					len(v.Args), nArgs)
			}

			// Check to make sure aux values make sense.

			v := b.Values[j]
			if v.Op == OpInvalid {
				continue
			}
			b.Values[i] = v
			i++
		}
		b.truncateValues(i)
	}
}

func (v *Value) clobbersFlags() bool {
	if opcodeTable[v.Op].clobberFlags {
		return true
	}
	if v.Type.IsTuple() && (v.Type.FieldType(0).IsFlags() || v.Type.FieldType(1).IsFlags()) {
		// This case handles the possibility where a flag value is generated but never used.

// There may be false positives.
func isEmpty(b *Block) bool {
	for _, v := range b.Values {
		if v.Uses > 0 || v.Op.IsCall() || v.Op.HasSideEffects() || v.Type.IsVoid() || opcodeTable[v.Op].nilCheck {
			return false
		}
	}
	return true
}

// fuseBlockPlain handles a run of blocks with length >= 2,
// whose interior has single predecessors and successors,

		// partition can grow in the loop. By not using a range loop here,
		// we process new additions as they arrive, avoiding O(n^2) behavior.
		for i := 0; i < len(partition); i++ {
			e := partition[i]

			if opcodeTable[e[0].Op].commutative {
				// Order the first two args before comparison.
				for _, v := range e {
					if valueEqClass[v.Args[0].ID] > valueEqClass[v.Args[1].ID] {
						v.Args[0], v.Args[1] = v.Args[1], v.Args[0]

			c.useSSE = false
		}
	}

	if ctxt.Flag_shared {
		// LoweredWB is secretly a CALL and CALLs on 386 in
		// shared mode get rewritten by obj6.go to go through
		// the GOT, which clobbers BX.
		opcodeTable[Op386LoweredWB].reg.clobbers |= 1 << 3 // BX
	}

	// Create the GC register map index.
	// TODO: This is only used for debug printing. Maybe export config.registers?
	gcRegMapSize := int16(0)

	// or anything else with side-effects
	for _, v := range b.Values {
		if v.Op == OpPhi || isDivMod(v.Op) || isPtrArithmetic(v.Op) || v.Type.IsMemory() ||
			v.MemoryArg() != nil || opcodeTable[v.Op].hasSideEffects {
			return false
		}
	}
	return true
}

func isDivMod(op Op) bool {
	switch op {
	case OpDiv8, OpDiv8u, OpDiv16, OpDiv16u,

		state.currentState.slots[slot] = loc
	}

	// Handle any register clobbering. Call operations, for example,
	// clobber all registers even though they don't explicitly write to
	// them.
	clobbers := uint64(opcodeTable[v.Op].reg.clobbers)
	for {
		if clobbers == 0 {
			break
		}
		reg := uint8(bits.TrailingZeros64(clobbers))
		clobbers &^= 1 << reg

		for _, slot := range locs.registers[reg] {

		return false
	}
	baseAndOffset := func(ptr *Value) (base *Value, offset int64) {
		base, offset = ptr, 0
		for base.Op == OpOffPtr {
			offset += base.AuxInt
			base = base.Args[0]
		}
		if opcodeTable[base.Op].nilCheck {
			base = base.Args[0]
		}
		return base, offset
	}
	p1, off1 := baseAndOffset(p1)
	p2, off2 := baseAndOffset(p2)
	if isSamePtr(p1, p2) {
		return !overlap(off1, n1, off2, n2)
	}

func (o Op) Asm() obj.As          { return opcodeTable[o].asm }
func (o Op) Scale() int16         { return int16(opcodeTable[o].scale) }
func (o Op) String() string       { return opcodeTable[o].name }
func (o Op) SymEffect() SymEffect { return opcodeTable[o].symEffect }
func (o Op) IsCall() bool         { return opcodeTable[o].call }
func (o Op) IsTailCall() bool     { return opcodeTable[o].tailCall }