chore: go mod vendor / tidy

vendor/github.com/mmcloughlin/avo/pass/alloc.go

@@ -0,0 +1,213 @@
+package pass
+
+import (
+	"errors"
+	"math"
+	"sort"
+
+	"github.com/mmcloughlin/avo/reg"
+)
+
+// edge is an edge of the interference graph, indicating that registers X and Y
+// must be in non-conflicting registers.
+type edge struct {
+	X, Y reg.ID
+}
+
+// Allocator is a graph-coloring register allocator.
+type Allocator struct {
+	registers  []reg.ID
+	priority   map[reg.ID]int
+	allocation reg.Allocation
+	edges      []*edge
+	possible   map[reg.ID][]reg.ID
+}
+
+// NewAllocator builds an allocator for the given physical registers.
+func NewAllocator(rs []reg.Physical) (*Allocator, error) {
+	// Set of IDs, excluding restricted registers.
+	idset := map[reg.ID]bool{}
+	for _, r := range rs {
+		if (r.Info() & reg.Restricted) != 0 {
+			continue
+		}
+		idset[r.ID()] = true
+	}
+
+	if len(idset) == 0 {
+		return nil, errors.New("no allocatable registers")
+	}
+
+	// Produce slice of unique register IDs.
+	var ids []reg.ID
+	for id := range idset {
+		ids = append(ids, id)
+	}
+
+	a := &Allocator{
+		registers:  ids,
+		priority:   map[reg.ID]int{},
+		allocation: reg.NewEmptyAllocation(),
+		possible:   map[reg.ID][]reg.ID{},
+	}
+	a.sortregisters()
+
+	return a, nil
+}
+
+// NewAllocatorForKind builds an allocator for the given kind of registers.
+func NewAllocatorForKind(k reg.Kind) (*Allocator, error) {
+	f := reg.FamilyOfKind(k)
+	if f == nil {
+		return nil, errors.New("unknown register family")
+	}
+	return NewAllocator(f.Registers())
+}
+
+// SetPriority sets the priority of the given regiser to p. Higher priority
+// registers are preferred in allocations. By default all registers have 0
+// priority. Priority will only apply to subsequent Add() calls, therefore
+// typically all SetPriority calls should happen at allocator initialization.
+func (a *Allocator) SetPriority(id reg.ID, p int) {
+	a.priority[id] = p
+	a.sortregisters()
+}
+
+// sortregisters sorts the list of available registers: higher priority first,
+// falling back to sorting by ID.
+func (a *Allocator) sortregisters() {
+	sort.Slice(a.registers, func(i, j int) bool {
+		ri, rj := a.registers[i], a.registers[j]
+		pi, pj := a.priority[ri], a.priority[rj]
+		return (pi > pj) || (pi == pj && ri < rj)
+	})
+}
+
+// AddInterferenceSet records that r interferes with every register in s. Convenience wrapper around AddInterference.
+func (a *Allocator) AddInterferenceSet(r reg.Register, s reg.MaskSet) {
+	for id, mask := range s {
+		if (r.Mask() & mask) != 0 {
+			a.AddInterference(r.ID(), id)
+		}
+	}
+}
+
+// AddInterference records that x and y must be assigned to non-conflicting physical registers.
+func (a *Allocator) AddInterference(x, y reg.ID) {
+	a.Add(x)
+	a.Add(y)
+	a.edges = append(a.edges, &edge{X: x, Y: y})
+}
+
+// Add adds a register to be allocated. Does nothing if the register has already been added.
+func (a *Allocator) Add(v reg.ID) {
+	if !v.IsVirtual() {
+		return
+	}
+	if _, found := a.possible[v]; found {
+		return
+	}
+	a.possible[v] = a.possibleregisters(v)
+}
+
+// Allocate allocates physical registers.
+func (a *Allocator) Allocate() (reg.Allocation, error) {
+	for {
+		if err := a.update(); err != nil {
+			return nil, err
+		}
+
+		if a.remaining() == 0 {
+			break
+		}
+
+		v := a.mostrestricted()
+		if err := a.alloc(v); err != nil {
+			return nil, err
+		}
+	}
+	return a.allocation, nil
+}
+
+// update possible allocations based on edges.
+func (a *Allocator) update() error {
+	var rem []*edge
+	for _, e := range a.edges {
+		x := a.allocation.LookupDefault(e.X)
+		y := a.allocation.LookupDefault(e.Y)
+		switch {
+		case x.IsVirtual() && y.IsVirtual():
+			rem = append(rem, e)
+			continue
+		case x.IsPhysical() && y.IsPhysical():
+			if x == y {
+				return errors.New("impossible register allocation")
+			}
+		case x.IsPhysical() && y.IsVirtual():
+			a.discardconflicting(y, x)
+		case x.IsVirtual() && y.IsPhysical():
+			a.discardconflicting(x, y)
+		default:
+			panic("unreachable")
+		}
+	}
+	a.edges = rem
+
+	return nil
+}
+
+// mostrestricted returns the virtual register with the least possibilities.
+func (a *Allocator) mostrestricted() reg.ID {
+	n := int(math.MaxInt32)
+	var v reg.ID
+	for w, p := range a.possible {
+		// On a tie, choose the smallest ID in numeric order. This avoids
+		// non-deterministic allocations due to map iteration order.
+		if len(p) < n || (len(p) == n && w < v) {
+			n = len(p)
+			v = w
+		}
+	}
+	return v
+}
+
+// discardconflicting removes registers from vs possible list that conflict with p.
+func (a *Allocator) discardconflicting(v, p reg.ID) {
+	a.possible[v] = filterregisters(a.possible[v], func(r reg.ID) bool {
+		return r != p
+	})
+}
+
+// alloc attempts to allocate a register to v.
+func (a *Allocator) alloc(v reg.ID) error {
+	ps := a.possible[v]
+	if len(ps) == 0 {
+		return errors.New("failed to allocate registers")
+	}
+	p := ps[0]
+	a.allocation[v] = p
+	delete(a.possible, v)
+	return nil
+}
+
+// remaining returns the number of unallocated registers.
+func (a *Allocator) remaining() int {
+	return len(a.possible)
+}
+
+// possibleregisters returns all allocate-able registers for the given virtual.
+func (a *Allocator) possibleregisters(v reg.ID) []reg.ID {
+	return filterregisters(a.registers, func(r reg.ID) bool {
+		return v.Kind() == r.Kind()
+	})
+}
+
+func filterregisters(in []reg.ID, predicate func(reg.ID) bool) []reg.ID {
+	var rs []reg.ID
+	for _, r := range in {
+		if predicate(r) {
+			rs = append(rs, r)
+		}
+	}
+	return rs
+}

vendor/github.com/mmcloughlin/avo/pass/cfg.go

@@ -0,0 +1,81 @@
+package pass
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/mmcloughlin/avo/ir"
+)
+
+// LabelTarget populates the LabelTarget of the given function. This maps from
+// label name to the following instruction.
+func LabelTarget(fn *ir.Function) error {
+	target := map[ir.Label]*ir.Instruction{}
+	var pending []ir.Label
+	for _, node := range fn.Nodes {
+		switch n := node.(type) {
+		case ir.Label:
+			if _, found := target[n]; found {
+				return fmt.Errorf("duplicate label \"%s\"", n)
+			}
+			pending = append(pending, n)
+		case *ir.Instruction:
+			for _, label := range pending {
+				target[label] = n
+			}
+			pending = nil
+		}
+	}
+	if len(pending) != 0 {
+		return errors.New("function ends with label")
+	}
+	fn.LabelTarget = target
+	return nil
+}
+
+// CFG constructs the call-flow-graph for the function.
+func CFG(fn *ir.Function) error {
+	is := fn.Instructions()
+	n := len(is)
+
+	// Populate successors.
+	for i := 0; i < n; i++ {
+		cur := is[i]
+		var nxt *ir.Instruction
+		if i+1 < n {
+			nxt = is[i+1]
+		}
+
+		// If it's a branch, locate the target.
+		if cur.IsBranch {
+			lbl := cur.TargetLabel()
+			if lbl == nil {
+				return errors.New("no label for branch instruction")
+			}
+			target, found := fn.LabelTarget[*lbl]
+			if !found {
+				return fmt.Errorf("unknown label %q", *lbl)
+			}
+			cur.Succ = append(cur.Succ, target)
+		}
+
+		// Otherwise, could continue to the following instruction.
+		switch {
+		case cur.IsTerminal:
+		case cur.IsUnconditionalBranch():
+		default:
+			cur.Succ = append(cur.Succ, nxt)
+		}
+	}
+
+	// Populate predecessors.
+	for _, i := range is {
+		for _, s := range i.Succ {
+			if s != nil {
+				s.Pred = append(s.Pred, i)
+			}
+		}
+	}
+
+	return nil
+}

vendor/github.com/mmcloughlin/avo/pass/cleanup.go

@@ -0,0 +1,123 @@
+package pass
+
+import (
+	"github.com/mmcloughlin/avo/ir"
+	"github.com/mmcloughlin/avo/operand"
+)
+
+// PruneJumpToFollowingLabel removes jump instructions that target an
+// immediately following label.
+func PruneJumpToFollowingLabel(fn *ir.Function) error {
+	for i := 0; i+1 < len(fn.Nodes); i++ {
+		node := fn.Nodes[i]
+		next := fn.Nodes[i+1]
+
+		// This node is an unconditional jump.
+		inst, ok := node.(*ir.Instruction)
+		if !ok || !inst.IsBranch || inst.IsConditional {
+			continue
+		}
+
+		target := inst.TargetLabel()
+		if target == nil {
+			continue
+		}
+
+		// And the jump target is the immediately following node.
+		lbl, ok := next.(ir.Label)
+		if !ok || lbl != *target {
+			continue
+		}
+
+		// Then the jump is unnecessary and can be removed.
+		fn.Nodes = deletenode(fn.Nodes, i)
+		i--
+	}
+
+	return nil
+}
+
+// PruneDanglingLabels removes labels that are not referenced by any branches.
+func PruneDanglingLabels(fn *ir.Function) error {
+	// Count label references.
+	count := map[ir.Label]int{}
+	for _, n := range fn.Nodes {
+		i, ok := n.(*ir.Instruction)
+		if !ok || !i.IsBranch {
+			continue
+		}
+
+		target := i.TargetLabel()
+		if target == nil {
+			continue
+		}
+
+		count[*target]++
+	}
+
+	// Look for labels with no references.
+	for i := 0; i < len(fn.Nodes); i++ {
+		node := fn.Nodes[i]
+		lbl, ok := node.(ir.Label)
+		if !ok {
+			continue
+		}
+
+		if count[lbl] == 0 {
+			fn.Nodes = deletenode(fn.Nodes, i)
+			i--
+		}
+	}
+
+	return nil
+}
+
+// PruneSelfMoves removes move instructions from one register to itself.
+func PruneSelfMoves(fn *ir.Function) error {
+	return removeinstructions(fn, func(i *ir.Instruction) bool {
+		switch i.Opcode {
+		case "MOVB", "MOVW", "MOVL", "MOVQ":
+		default:
+			return false
+		}
+
+		return operand.IsRegister(i.Operands[0]) && operand.IsRegister(i.Operands[1]) && i.Operands[0] == i.Operands[1]
+	})
+}
+
+// removeinstructions deletes instructions from the given function which match predicate.
+func removeinstructions(fn *ir.Function, predicate func(*ir.Instruction) bool) error {
+	// Removal of instructions has the potential to invalidate CFG structures.
+	// Clear them to prevent accidental use of stale structures after this pass.
+	invalidatecfg(fn)
+
+	for i := 0; i < len(fn.Nodes); i++ {
+		n := fn.Nodes[i]
+
+		inst, ok := n.(*ir.Instruction)
+		if !ok || !predicate(inst) {
+			continue
+		}
+
+		fn.Nodes = deletenode(fn.Nodes, i)
+	}
+
+	return nil
+}
+
+// deletenode deletes node i from nodes and returns the resulting slice.
+func deletenode(nodes []ir.Node, i int) []ir.Node {
+	n := len(nodes)
+	copy(nodes[i:], nodes[i+1:])
+	nodes[n-1] = nil
+	return nodes[:n-1]
+}
+
+// invalidatecfg clears CFG structures.
+func invalidatecfg(fn *ir.Function) {
+	fn.LabelTarget = nil
+	for _, i := range fn.Instructions() {
+		i.Pred = nil
+		i.Succ = nil
+	}
+}

vendor/github.com/mmcloughlin/avo/pass/isa.go

@@ -0,0 +1,31 @@
+package pass
+
+import (
+	"sort"
+
+	"github.com/mmcloughlin/avo/ir"
+)
+
+// RequiredISAExtensions determines ISA extensions required for the given
+// function. Populates the ISA field.
+func RequiredISAExtensions(fn *ir.Function) error {
+	// Collect ISA set.
+	set := map[string]bool{}
+	for _, i := range fn.Instructions() {
+		for _, isa := range i.ISA {
+			set[isa] = true
+		}
+	}
+
+	if len(set) == 0 {
+		return nil
+	}
+
+	// Populate the function's ISA field with the unique sorted list.
+	for isa := range set {
+		fn.ISA = append(fn.ISA, isa)
+	}
+	sort.Strings(fn.ISA)
+
+	return nil
+}

vendor/github.com/mmcloughlin/avo/pass/pass.go

@@ -0,0 +1,101 @@
+// Package pass implements processing passes on avo Files.
+package pass
+
+import (
+	"io"
+
+	"github.com/mmcloughlin/avo/ir"
+	"github.com/mmcloughlin/avo/printer"
+)
+
+// Compile pass compiles an avo file. Upon successful completion the avo file
+// may be printed to Go assembly.
+var Compile = Concat(
+	Verify,
+	FunctionPass(PruneJumpToFollowingLabel),
+	FunctionPass(PruneDanglingLabels),
+	FunctionPass(LabelTarget),
+	FunctionPass(CFG),
+	InstructionPass(ZeroExtend32BitOutputs),
+	FunctionPass(Liveness),
+	FunctionPass(AllocateRegisters),
+	FunctionPass(BindRegisters),
+	FunctionPass(VerifyAllocation),
+	FunctionPass(EnsureBasePointerCalleeSaved),
+	Func(IncludeTextFlagHeader),
+	FunctionPass(PruneSelfMoves),
+	FunctionPass(RequiredISAExtensions),
+)
+
+// Interface for a processing pass.
+type Interface interface {
+	Execute(*ir.File) error
+}
+
+// Func adapts a function to the pass Interface.
+type Func func(*ir.File) error
+
+// Execute calls p.
+func (p Func) Execute(f *ir.File) error {
+	return p(f)
+}
+
+// FunctionPass is a convenience for implementing a full file pass with a
+// function that operates on each avo Function independently.
+type FunctionPass func(*ir.Function) error
+
+// Execute calls p on every function in the file. Exits on the first error.
+func (p FunctionPass) Execute(f *ir.File) error {
+	for _, fn := range f.Functions() {
+		if err := p(fn); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// InstructionPass is a convenience for implementing a full file pass with a
+// function that operates on each Instruction independently.
+type InstructionPass func(*ir.Instruction) error
+
+// Execute calls p on every instruction in the file. Exits on the first error.
+func (p InstructionPass) Execute(f *ir.File) error {
+	for _, fn := range f.Functions() {
+		for _, i := range fn.Instructions() {
+			if err := p(i); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// Concat returns a pass that executes the given passes in order, stopping on the first error.
+func Concat(passes ...Interface) Interface {
+	return Func(func(f *ir.File) error {
+		for _, p := range passes {
+			if err := p.Execute(f); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+}
+
+// Output pass prints a file.
+type Output struct {
+	Writer  io.WriteCloser
+	Printer printer.Printer
+}
+
+// Execute prints f with the configured Printer and writes output to Writer.
+func (o *Output) Execute(f *ir.File) error {
+	b, err := o.Printer.Print(f)
+	if err != nil {
+		return err
+	}
+	if _, err = o.Writer.Write(b); err != nil {
+		return err
+	}
+	return o.Writer.Close()
+}

vendor/github.com/mmcloughlin/avo/pass/reg.go

@@ -0,0 +1,223 @@
+package pass
+
+import (
+	"errors"
+
+	"github.com/mmcloughlin/avo/gotypes"
+	"github.com/mmcloughlin/avo/ir"
+	"github.com/mmcloughlin/avo/operand"
+	"github.com/mmcloughlin/avo/reg"
+)
+
+// ZeroExtend32BitOutputs applies the rule that "32-bit operands generate a
+// 32-bit result, zero-extended to a 64-bit result in the destination
+// general-purpose register" (Intel Software Developer’s Manual, Volume 1,
+// 3.4.1.1).
+func ZeroExtend32BitOutputs(i *ir.Instruction) error {
+	for j, op := range i.Outputs {
+		if !operand.IsR32(op) {
+			continue
+		}
+		r, ok := op.(reg.GP)
+		if !ok {
+			panic("r32 operand should satisfy reg.GP")
+		}
+		i.Outputs[j] = r.As64()
+	}
+	return nil
+}
+
+// Liveness computes register liveness.
+func Liveness(fn *ir.Function) error {
+	// Note this implementation is initially naive so as to be "obviously correct".
+	// There are a well-known optimizations we can apply if necessary.
+
+	is := fn.Instructions()
+
+	// Process instructions in reverse: poor approximation to topological sort.
+	// TODO(mbm): process instructions in topological sort order
+	for l, r := 0, len(is)-1; l < r; l, r = l+1, r-1 {
+		is[l], is[r] = is[r], is[l]
+	}
+
+	// Initialize.
+	for _, i := range is {
+		i.LiveIn = reg.NewMaskSetFromRegisters(i.InputRegisters())
+		i.LiveOut = reg.NewEmptyMaskSet()
+	}
+
+	// Iterative dataflow analysis.
+	for {
+		changes := false
+
+		for _, i := range is {
+			// out[n] = UNION[s IN succ[n]] in[s]
+			for _, s := range i.Succ {
+				if s == nil {
+					continue
+				}
+				changes = i.LiveOut.Update(s.LiveIn) || changes
+			}
+
+			// in[n] = use[n] UNION (out[n] - def[n])
+			def := reg.NewMaskSetFromRegisters(i.OutputRegisters())
+			changes = i.LiveIn.Update(i.LiveOut.Difference(def)) || changes
+		}
+
+		if !changes {
+			break
+		}
+	}
+
+	return nil
+}
+
+// AllocateRegisters performs register allocation.
+func AllocateRegisters(fn *ir.Function) error {
+	// Initialize one allocator per kind.
+	as := map[reg.Kind]*Allocator{}
+	for _, i := range fn.Instructions() {
+		for _, r := range i.Registers() {
+			k := r.Kind()
+			if _, found := as[k]; !found {
+				a, err := NewAllocatorForKind(k)
+				if err != nil {
+					return err
+				}
+				as[k] = a
+			}
+		}
+	}
+
+	// De-prioritize the base pointer register. This can be used as a general
+	// purpose register, but it's callee-save so needs to be saved/restored if
+	// it is clobbered. For this reason we prefer to avoid using it unless
+	// forced to by register pressure.
+	for k, a := range as {
+		f := reg.FamilyOfKind(k)
+		for _, r := range f.Registers() {
+			if (r.Info() & reg.BasePointer) != 0 {
+				// Negative priority penalizes this register relative to all
+				// others (having default zero priority).
+				a.SetPriority(r.ID(), -1)
+			}
+		}
+	}
+
+	// Populate registers to be allocated.
+	for _, i := range fn.Instructions() {
+		for _, r := range i.Registers() {
+			as[r.Kind()].Add(r.ID())
+		}
+	}
+
+	// Record register interferences.
+	for _, i := range fn.Instructions() {
+		for _, d := range i.OutputRegisters() {
+			k := d.Kind()
+			out := i.LiveOut.OfKind(k)
+			out.DiscardRegister(d)
+			as[k].AddInterferenceSet(d, out)
+		}
+	}
+
+	// Execute register allocation.
+	fn.Allocation = reg.NewEmptyAllocation()
+	for _, a := range as {
+		al, err := a.Allocate()
+		if err != nil {
+			return err
+		}
+		if err := fn.Allocation.Merge(al); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// BindRegisters applies the result of register allocation, replacing all virtual registers with their assigned physical registers.
+func BindRegisters(fn *ir.Function) error {
+	for _, i := range fn.Instructions() {
+		for idx := range i.Operands {
+			i.Operands[idx] = operand.ApplyAllocation(i.Operands[idx], fn.Allocation)
+		}
+		for idx := range i.Inputs {
+			i.Inputs[idx] = operand.ApplyAllocation(i.Inputs[idx], fn.Allocation)
+		}
+		for idx := range i.Outputs {
+			i.Outputs[idx] = operand.ApplyAllocation(i.Outputs[idx], fn.Allocation)
+		}
+	}
+	return nil
+}
+
+// VerifyAllocation performs sanity checks following register allocation.
+func VerifyAllocation(fn *ir.Function) error {
+	// All registers should be physical.
+	for _, i := range fn.Instructions() {
+		for _, r := range i.Registers() {
+			if reg.ToPhysical(r) == nil {
+				return errors.New("non physical register found")
+			}
+		}
+	}
+
+	return nil
+}
+
+// EnsureBasePointerCalleeSaved ensures that the base pointer register will be
+// saved and restored if it has been clobbered by the function.
+func EnsureBasePointerCalleeSaved(fn *ir.Function) error {
+	// Check to see if the base pointer is written to.
+	clobbered := false
+	for _, i := range fn.Instructions() {
+		for _, r := range i.OutputRegisters() {
+			if p := reg.ToPhysical(r); p != nil && (p.Info()&reg.BasePointer) != 0 {
+				clobbered = true
+			}
+		}
+	}
+
+	if !clobbered {
+		return nil
+	}
+
+	// This function clobbers the base pointer register so we need to ensure it
+	// will be saved and restored. The Go assembler will do this automatically,
+	// with a few exceptions detailed below. In summary, we can usually ensure
+	// this happens by ensuring the function is not frameless (apart from
+	// NOFRAME functions).
+	//
+	// Reference: https://github.com/golang/go/blob/3f4977bd5800beca059defb5de4dc64cd758cbb9/src/cmd/internal/obj/x86/obj6.go#L591-L609
+	//
+	//		var bpsize int
+	//		if ctxt.Arch.Family == sys.AMD64 &&
+	//			!p.From.Sym.NoFrame() && // (1) below
+	//			!(autoffset == 0 && p.From.Sym.NoSplit()) && // (2) below
+	//			!(autoffset == 0 && !hasCall) { // (3) below
+	//			// Make room to save a base pointer.
+	//			// There are 2 cases we must avoid:
+	//			// 1) If noframe is set (which we do for functions which tail call).
+	//			// 2) Scary runtime internals which would be all messed up by frame pointers.
+	//			//    We detect these using a heuristic: frameless nosplit functions.
+	//			//    TODO: Maybe someday we label them all with NOFRAME and get rid of this heuristic.
+	//			// For performance, we also want to avoid:
+	//			// 3) Frameless leaf functions
+	//			bpsize = ctxt.Arch.PtrSize
+	//			autoffset += int32(bpsize)
+	//			p.To.Offset += int64(bpsize)
+	//		} else {
+	//			bpsize = 0
+	//		}
+	//
+	if fn.Attributes.NOFRAME() {
+		return errors.New("NOFRAME function clobbers base pointer register")
+	}
+
+	if fn.LocalSize == 0 {
+		fn.AllocLocal(int(gotypes.PointerSize))
+	}
+
+	return nil
+}

vendor/github.com/mmcloughlin/avo/pass/textflag.go

@@ -0,0 +1,42 @@
+package pass
+
+import (
+	"github.com/mmcloughlin/avo/attr"
+	"github.com/mmcloughlin/avo/ir"
+)
+
+// IncludeTextFlagHeader includes textflag.h if necessary.
+func IncludeTextFlagHeader(f *ir.File) error {
+	const textflagheader = "textflag.h"
+
+	// Check if we already have it.
+	for _, path := range f.Includes {
+		if path == textflagheader {
+			return nil
+		}
+	}
+
+	// Add it if necessary.
+	if requirestextflags(f) {
+		f.Includes = append(f.Includes, textflagheader)
+	}
+
+	return nil
+}
+
+// requirestextflags returns whether the file uses flags in the textflags.h header.
+func requirestextflags(f *ir.File) bool {
+	for _, s := range f.Sections {
+		var a attr.Attribute
+		switch s := s.(type) {
+		case *ir.Function:
+			a = s.Attributes
+		case *ir.Global:
+			a = s.Attributes
+		}
+		if a.ContainsTextFlags() {
+			return true
+		}
+	}
+	return false
+}

vendor/github.com/mmcloughlin/avo/pass/verify.go

@@ -0,0 +1,32 @@
+package pass
+
+import (
+	"errors"
+
+	"github.com/mmcloughlin/avo/ir"
+	"github.com/mmcloughlin/avo/operand"
+)
+
+// Verify pass validates an avo file.
+var Verify = Concat(
+	InstructionPass(VerifyMemOperands),
+)
+
+// VerifyMemOperands checks the instruction's memory operands.
+func VerifyMemOperands(i *ir.Instruction) error {
+	for _, op := range i.Operands {
+		m, ok := op.(operand.Mem)
+		if !ok {
+			continue
+		}
+
+		if m.Base == nil {
+			return errors.New("bad memory operand: missing base register")
+		}
+
+		if m.Index != nil && m.Scale == 0 {
+			return errors.New("bad memory operand: index register with scale 0")
+		}
+	}
+	return nil
+}