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compiler.go
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compiler.go
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package goja
import (
"fmt"
"github.com/dop251/goja/token"
"sort"
"github.com/dop251/goja/ast"
"github.com/dop251/goja/file"
"github.com/dop251/goja/unistring"
)
type blockType int
const (
blockLoop blockType = iota
blockLoopEnum
blockTry
blockLabel
blockSwitch
blockWith
blockScope
blockIterScope
blockOptChain
)
const (
maskConst = 1 << 31
maskVar = 1 << 30
maskDeletable = 1 << 29
maskStrict = maskDeletable
maskTyp = maskConst | maskVar | maskDeletable
)
type varType byte
const (
varTypeVar varType = iota
varTypeLet
varTypeStrictConst
varTypeConst
)
const thisBindingName = " this" // must not be a valid identifier
type CompilerError struct {
Message string
File *file.File
Offset int
}
type CompilerSyntaxError struct {
CompilerError
}
type CompilerReferenceError struct {
CompilerError
}
type srcMapItem struct {
pc int
srcPos int
}
type Program struct {
code []instruction
values []Value
funcName unistring.String
src *file.File
srcMap []srcMapItem
}
type compiler struct {
p *Program
scope *scope
block *block
classScope *classScope
enumGetExpr compiledEnumGetExpr
evalVM *vm // VM used to evaluate constant expressions
ctxVM *vm // VM in which an eval() code is compiled
codeScratchpad []instruction
}
type binding struct {
scope *scope
name unistring.String
accessPoints map[*scope]*[]int
isConst bool
isStrict bool
isArg bool
isVar bool
inStash bool
}
func (b *binding) getAccessPointsForScope(s *scope) *[]int {
m := b.accessPoints[s]
if m == nil {
a := make([]int, 0, 1)
m = &a
if b.accessPoints == nil {
b.accessPoints = make(map[*scope]*[]int)
}
b.accessPoints[s] = m
}
return m
}
func (b *binding) markAccessPointAt(pos int) {
scope := b.scope.c.scope
m := b.getAccessPointsForScope(scope)
*m = append(*m, pos-scope.base)
}
func (b *binding) markAccessPointAtScope(scope *scope, pos int) {
m := b.getAccessPointsForScope(scope)
*m = append(*m, pos-scope.base)
}
func (b *binding) markAccessPoint() {
scope := b.scope.c.scope
m := b.getAccessPointsForScope(scope)
*m = append(*m, len(scope.prg.code)-scope.base)
}
func (b *binding) emitGet() {
b.markAccessPoint()
if b.isVar && !b.isArg {
b.scope.c.emit(loadStack(0))
} else {
b.scope.c.emit(loadStackLex(0))
}
}
func (b *binding) emitGetAt(pos int) {
b.markAccessPointAt(pos)
if b.isVar && !b.isArg {
b.scope.c.p.code[pos] = loadStack(0)
} else {
b.scope.c.p.code[pos] = loadStackLex(0)
}
}
func (b *binding) emitGetP() {
if b.isVar && !b.isArg {
// no-op
} else {
// make sure TDZ is checked
b.markAccessPoint()
b.scope.c.emit(loadStackLex(0), pop)
}
}
func (b *binding) emitSet() {
if b.isConst {
if b.isStrict || b.scope.c.scope.strict {
b.scope.c.emit(throwAssignToConst)
}
return
}
b.markAccessPoint()
if b.isVar && !b.isArg {
b.scope.c.emit(storeStack(0))
} else {
b.scope.c.emit(storeStackLex(0))
}
}
func (b *binding) emitSetP() {
if b.isConst {
if b.isStrict || b.scope.c.scope.strict {
b.scope.c.emit(throwAssignToConst)
}
return
}
b.markAccessPoint()
if b.isVar && !b.isArg {
b.scope.c.emit(storeStackP(0))
} else {
b.scope.c.emit(storeStackLexP(0))
}
}
func (b *binding) emitInitP() {
if !b.isVar && b.scope.outer == nil {
b.scope.c.emit(initGlobalP(b.name))
} else {
b.markAccessPoint()
b.scope.c.emit(initStackP(0))
}
}
func (b *binding) emitInit() {
if !b.isVar && b.scope.outer == nil {
b.scope.c.emit(initGlobal(b.name))
} else {
b.markAccessPoint()
b.scope.c.emit(initStack(0))
}
}
func (b *binding) emitInitAt(pos int) {
if !b.isVar && b.scope.outer == nil {
b.scope.c.p.code[pos] = initGlobal(b.name)
} else {
b.markAccessPointAt(pos)
b.scope.c.p.code[pos] = initStack(0)
}
}
func (b *binding) emitInitAtScope(scope *scope, pos int) {
if !b.isVar && scope.outer == nil {
scope.c.p.code[pos] = initGlobal(b.name)
} else {
b.markAccessPointAtScope(scope, pos)
scope.c.p.code[pos] = initStack(0)
}
}
func (b *binding) emitInitPAtScope(scope *scope, pos int) {
if !b.isVar && scope.outer == nil {
scope.c.p.code[pos] = initGlobalP(b.name)
} else {
b.markAccessPointAtScope(scope, pos)
scope.c.p.code[pos] = initStackP(0)
}
}
func (b *binding) emitGetVar(callee bool) {
b.markAccessPoint()
if b.isVar && !b.isArg {
b.scope.c.emit(&loadMixed{name: b.name, callee: callee})
} else {
b.scope.c.emit(&loadMixedLex{name: b.name, callee: callee})
}
}
func (b *binding) emitResolveVar(strict bool) {
b.markAccessPoint()
if b.isVar && !b.isArg {
b.scope.c.emit(&resolveMixed{name: b.name, strict: strict, typ: varTypeVar})
} else {
var typ varType
if b.isConst {
if b.isStrict {
typ = varTypeStrictConst
} else {
typ = varTypeConst
}
} else {
typ = varTypeLet
}
b.scope.c.emit(&resolveMixed{name: b.name, strict: strict, typ: typ})
}
}
func (b *binding) moveToStash() {
if b.isArg && !b.scope.argsInStash {
b.scope.moveArgsToStash()
} else {
b.inStash = true
b.scope.needStash = true
}
}
func (b *binding) useCount() (count int) {
for _, a := range b.accessPoints {
count += len(*a)
}
return
}
type scope struct {
c *compiler
prg *Program
outer *scope
nested []*scope
boundNames map[unistring.String]*binding
bindings []*binding
base int
numArgs int
// function type. If not funcNone, this is a function or a top-level lexical environment
funcType funcType
// in strict mode
strict bool
// eval top-level scope
eval bool
// at least one inner scope has direct eval() which can lookup names dynamically (by name)
dynLookup bool
// at least one binding has been marked for placement in stash
needStash bool
// is a variable environment, i.e. the target for dynamically created var bindings
variable bool
// a function scope that has at least one direct eval() and non-strict, so the variables can be added dynamically
dynamic bool
// arguments have been marked for placement in stash (functions only)
argsInStash bool
// need 'arguments' object (functions only)
argsNeeded bool
}
type block struct {
typ blockType
label unistring.String
cont int
breaks []int
conts []int
outer *block
breaking *block // set when the 'finally' block is an empty break statement sequence
needResult bool
}
func (c *compiler) leaveScopeBlock(enter *enterBlock) {
c.updateEnterBlock(enter)
leave := &leaveBlock{
stackSize: enter.stackSize,
popStash: enter.stashSize > 0,
}
c.emit(leave)
for _, pc := range c.block.breaks {
c.p.code[pc] = leave
}
c.block.breaks = nil
c.leaveBlock()
}
func (c *compiler) leaveBlock() {
lbl := len(c.p.code)
for _, item := range c.block.breaks {
c.p.code[item] = jump(lbl - item)
}
if t := c.block.typ; t == blockLoop || t == blockLoopEnum {
for _, item := range c.block.conts {
c.p.code[item] = jump(c.block.cont - item)
}
}
c.block = c.block.outer
}
func (e *CompilerSyntaxError) Error() string {
if e.File != nil {
return fmt.Sprintf("SyntaxError: %s at %s", e.Message, e.File.Position(e.Offset))
}
return fmt.Sprintf("SyntaxError: %s", e.Message)
}
func (e *CompilerReferenceError) Error() string {
return fmt.Sprintf("ReferenceError: %s", e.Message)
}
func (c *compiler) newScope() {
strict := false
if c.scope != nil {
strict = c.scope.strict
}
c.scope = &scope{
c: c,
prg: c.p,
outer: c.scope,
strict: strict,
}
}
func (c *compiler) newBlockScope() {
c.newScope()
if outer := c.scope.outer; outer != nil {
outer.nested = append(outer.nested, c.scope)
}
c.scope.base = len(c.p.code)
}
func (c *compiler) popScope() {
c.scope = c.scope.outer
}
func newCompiler() *compiler {
c := &compiler{
p: &Program{},
}
c.enumGetExpr.init(c, file.Idx(0))
return c
}
func (p *Program) defineLiteralValue(val Value) uint32 {
for idx, v := range p.values {
if v.SameAs(val) {
return uint32(idx)
}
}
idx := uint32(len(p.values))
p.values = append(p.values, val)
return idx
}
func (p *Program) dumpCode(logger func(format string, args ...interface{})) {
p._dumpCode("", logger)
}
func (p *Program) _dumpCode(indent string, logger func(format string, args ...interface{})) {
logger("values: %+v", p.values)
dumpInitFields := func(initFields *Program) {
i := indent + ">"
logger("%s ---- init_fields:", i)
initFields._dumpCode(i, logger)
logger("%s ----", i)
}
for pc, ins := range p.code {
logger("%s %d: %T(%v)", indent, pc, ins, ins)
var prg *Program
switch f := ins.(type) {
case *newFunc:
prg = f.prg
case *newAsyncFunc:
prg = f.prg
case *newArrowFunc:
prg = f.prg
case *newAsyncArrowFunc:
prg = f.prg
case *newMethod:
prg = f.prg
case *newAsyncMethod:
prg = f.prg
case *newDerivedClass:
if f.initFields != nil {
dumpInitFields(f.initFields)
}
prg = f.ctor
case *newClass:
if f.initFields != nil {
dumpInitFields(f.initFields)
}
prg = f.ctor
case *newStaticFieldInit:
if f.initFields != nil {
dumpInitFields(f.initFields)
}
}
if prg != nil {
prg._dumpCode(indent+">", logger)
}
}
}
func (p *Program) sourceOffset(pc int) int {
i := sort.Search(len(p.srcMap), func(idx int) bool {
return p.srcMap[idx].pc > pc
}) - 1
if i >= 0 {
return p.srcMap[i].srcPos
}
return 0
}
func (p *Program) addSrcMap(srcPos int) {
if len(p.srcMap) > 0 && p.srcMap[len(p.srcMap)-1].srcPos == srcPos {
return
}
p.srcMap = append(p.srcMap, srcMapItem{pc: len(p.code), srcPos: srcPos})
}
func (s *scope) lookupName(name unistring.String) (binding *binding, noDynamics bool) {
noDynamics = true
toStash := false
for curScope := s; ; curScope = curScope.outer {
if curScope.outer != nil {
if b, exists := curScope.boundNames[name]; exists {
if toStash && !b.inStash {
b.moveToStash()
}
binding = b
return
}
} else {
noDynamics = false
return
}
if curScope.dynamic {
noDynamics = false
}
if name == "arguments" && curScope.funcType != funcNone && curScope.funcType != funcArrow {
if curScope.funcType == funcClsInit {
s.c.throwSyntaxError(0, "'arguments' is not allowed in class field initializer or static initialization block")
}
curScope.argsNeeded = true
binding, _ = curScope.bindName(name)
return
}
if curScope.isFunction() {
toStash = true
}
}
}
func (s *scope) lookupThis() (*binding, bool) {
toStash := false
for curScope := s; curScope != nil; curScope = curScope.outer {
if curScope.outer == nil {
if curScope.eval {
return nil, true
}
}
if b, exists := curScope.boundNames[thisBindingName]; exists {
if toStash && !b.inStash {
b.moveToStash()
}
return b, false
}
if curScope.isFunction() {
toStash = true
}
}
return nil, false
}
func (s *scope) ensureBoundNamesCreated() {
if s.boundNames == nil {
s.boundNames = make(map[unistring.String]*binding)
}
}
func (s *scope) addBinding(offset int) *binding {
if len(s.bindings) >= (1<<24)-1 {
s.c.throwSyntaxError(offset, "Too many variables")
}
b := &binding{
scope: s,
}
s.bindings = append(s.bindings, b)
return b
}
func (s *scope) bindNameLexical(name unistring.String, unique bool, offset int) (*binding, bool) {
if b := s.boundNames[name]; b != nil {
if unique {
s.c.throwSyntaxError(offset, "Identifier '%s' has already been declared", name)
}
return b, false
}
b := s.addBinding(offset)
b.name = name
s.ensureBoundNamesCreated()
s.boundNames[name] = b
return b, true
}
func (s *scope) createThisBinding() *binding {
thisBinding, _ := s.bindNameLexical(thisBindingName, false, 0)
thisBinding.isVar = true // don't check on load
return thisBinding
}
func (s *scope) bindName(name unistring.String) (*binding, bool) {
if !s.isFunction() && !s.variable && s.outer != nil {
return s.outer.bindName(name)
}
b, created := s.bindNameLexical(name, false, 0)
if created {
b.isVar = true
}
return b, created
}
func (s *scope) bindNameShadow(name unistring.String) (*binding, bool) {
if !s.isFunction() && s.outer != nil {
return s.outer.bindNameShadow(name)
}
_, exists := s.boundNames[name]
b := &binding{
scope: s,
name: name,
}
s.bindings = append(s.bindings, b)
s.ensureBoundNamesCreated()
s.boundNames[name] = b
return b, !exists
}
func (s *scope) nearestFunction() *scope {
for sc := s; sc != nil; sc = sc.outer {
if sc.isFunction() {
return sc
}
}
return nil
}
func (s *scope) nearestThis() *scope {
for sc := s; sc != nil; sc = sc.outer {
if sc.eval || sc.isFunction() && sc.funcType != funcArrow {
return sc
}
}
return nil
}
func (s *scope) finaliseVarAlloc(stackOffset int) (stashSize, stackSize int) {
argsInStash := false
if f := s.nearestFunction(); f != nil {
argsInStash = f.argsInStash
}
stackIdx, stashIdx := 0, 0
allInStash := s.isDynamic()
var derivedCtor bool
if fs := s.nearestThis(); fs != nil && fs.funcType == funcDerivedCtor {
derivedCtor = true
}
for i, b := range s.bindings {
var this bool
if b.name == thisBindingName {
this = true
}
if allInStash || b.inStash {
for scope, aps := range b.accessPoints {
var level uint32
for sc := scope; sc != nil && sc != s; sc = sc.outer {
if sc.needStash || sc.isDynamic() {
level++
}
}
if level > 255 {
s.c.throwSyntaxError(0, "Maximum nesting level (256) exceeded")
}
idx := (level << 24) | uint32(stashIdx)
base := scope.base
code := scope.prg.code
if this {
if derivedCtor {
for _, pc := range *aps {
ap := &code[base+pc]
switch (*ap).(type) {
case loadStack:
*ap = loadThisStash(idx)
case initStack:
*ap = initStash(idx)
case resolveThisStack:
*ap = resolveThisStash(idx)
case _ret:
*ap = cret(idx)
default:
s.c.assert(false, s.c.p.sourceOffset(pc), "Unsupported instruction for 'this'")
}
}
} else {
for _, pc := range *aps {
ap := &code[base+pc]
switch (*ap).(type) {
case loadStack:
*ap = loadStash(idx)
case initStack:
*ap = initStash(idx)
default:
s.c.assert(false, s.c.p.sourceOffset(pc), "Unsupported instruction for 'this'")
}
}
}
} else {
for _, pc := range *aps {
ap := &code[base+pc]
switch i := (*ap).(type) {
case loadStack:
*ap = loadStash(idx)
case storeStack:
*ap = storeStash(idx)
case storeStackP:
*ap = storeStashP(idx)
case loadStackLex:
*ap = loadStashLex(idx)
case storeStackLex:
*ap = storeStashLex(idx)
case storeStackLexP:
*ap = storeStashLexP(idx)
case initStackP:
*ap = initStashP(idx)
case initStack:
*ap = initStash(idx)
case *loadMixed:
i.idx = idx
case *loadMixedLex:
i.idx = idx
case *resolveMixed:
i.idx = idx
default:
s.c.assert(false, s.c.p.sourceOffset(pc), "Unsupported instruction for binding: %T", i)
}
}
}
}
stashIdx++
} else {
var idx int
if !this {
if i < s.numArgs {
idx = -(i + 1)
} else {
stackIdx++
idx = stackIdx + stackOffset
}
}
for scope, aps := range b.accessPoints {
var level int
for sc := scope; sc != nil && sc != s; sc = sc.outer {
if sc.needStash || sc.isDynamic() {
level++
}
}
if level > 255 {
s.c.throwSyntaxError(0, "Maximum nesting level (256) exceeded")
}
code := scope.prg.code
base := scope.base
if this {
if derivedCtor {
for _, pc := range *aps {
ap := &code[base+pc]
switch (*ap).(type) {
case loadStack:
*ap = loadThisStack{}
case initStack:
// no-op
case resolveThisStack:
// no-op
case _ret:
// no-op, already in the right place
default:
s.c.assert(false, s.c.p.sourceOffset(pc), "Unsupported instruction for 'this'")
}
}
} /*else {
no-op
}*/
} else if argsInStash {
for _, pc := range *aps {
ap := &code[base+pc]
switch i := (*ap).(type) {
case loadStack:
*ap = loadStack1(idx)
case storeStack:
*ap = storeStack1(idx)
case storeStackP:
*ap = storeStack1P(idx)
case loadStackLex:
*ap = loadStack1Lex(idx)
case storeStackLex:
*ap = storeStack1Lex(idx)
case storeStackLexP:
*ap = storeStack1LexP(idx)
case initStackP:
*ap = initStack1P(idx)
case initStack:
*ap = initStack1(idx)
case *loadMixed:
*ap = &loadMixedStack1{name: i.name, idx: idx, level: uint8(level), callee: i.callee}
case *loadMixedLex:
*ap = &loadMixedStack1Lex{name: i.name, idx: idx, level: uint8(level), callee: i.callee}
case *resolveMixed:
*ap = &resolveMixedStack1{typ: i.typ, name: i.name, idx: idx, level: uint8(level), strict: i.strict}
default:
s.c.assert(false, s.c.p.sourceOffset(pc), "Unsupported instruction for binding: %T", i)
}
}
} else {
for _, pc := range *aps {
ap := &code[base+pc]
switch i := (*ap).(type) {
case loadStack:
*ap = loadStack(idx)
case storeStack:
*ap = storeStack(idx)
case storeStackP:
*ap = storeStackP(idx)
case loadStackLex:
*ap = loadStackLex(idx)
case storeStackLex:
*ap = storeStackLex(idx)
case storeStackLexP:
*ap = storeStackLexP(idx)
case initStack:
*ap = initStack(idx)
case initStackP:
*ap = initStackP(idx)
case *loadMixed:
*ap = &loadMixedStack{name: i.name, idx: idx, level: uint8(level), callee: i.callee}
case *loadMixedLex:
*ap = &loadMixedStackLex{name: i.name, idx: idx, level: uint8(level), callee: i.callee}
case *resolveMixed:
*ap = &resolveMixedStack{typ: i.typ, name: i.name, idx: idx, level: uint8(level), strict: i.strict}
default:
s.c.assert(false, s.c.p.sourceOffset(pc), "Unsupported instruction for binding: %T", i)
}
}
}
}
}
}
for _, nested := range s.nested {
nested.finaliseVarAlloc(stackIdx + stackOffset)
}
return stashIdx, stackIdx
}
func (s *scope) moveArgsToStash() {
for _, b := range s.bindings {
if !b.isArg {
break
}
b.inStash = true
}
s.argsInStash = true
s.needStash = true
}
func (c *compiler) trimCode(delta int) {
src := c.p.code[delta:]
newCode := make([]instruction, len(src))
copy(newCode, src)
if cap(c.codeScratchpad) < cap(c.p.code) {
c.codeScratchpad = c.p.code[:0]
}
c.p.code = newCode
}
func (s *scope) trimCode(delta int) {
s.c.trimCode(delta)
if delta != 0 {
srcMap := s.c.p.srcMap
for i := range srcMap {
srcMap[i].pc -= delta
}
s.adjustBase(-delta)
}
}
func (s *scope) adjustBase(delta int) {
s.base += delta
for _, nested := range s.nested {
nested.adjustBase(delta)
}
}
func (s *scope) makeNamesMap() map[unistring.String]uint32 {
l := len(s.bindings)
if l == 0 {
return nil
}
names := make(map[unistring.String]uint32, l)
for i, b := range s.bindings {
idx := uint32(i)
if b.isConst {
idx |= maskConst
if b.isStrict {
idx |= maskStrict
}
}
if b.isVar {
idx |= maskVar
}
names[b.name] = idx
}
return names
}
func (s *scope) isDynamic() bool {
return s.dynLookup || s.dynamic
}
func (s *scope) isFunction() bool {
return s.funcType != funcNone && !s.eval
}
func (s *scope) deleteBinding(b *binding) {
idx := 0
for i, bb := range s.bindings {
if bb == b {
idx = i
goto found
}
}
return
found:
delete(s.boundNames, b.name)
copy(s.bindings[idx:], s.bindings[idx+1:])
l := len(s.bindings) - 1
s.bindings[l] = nil
s.bindings = s.bindings[:l]
}
func (c *compiler) compile(in *ast.Program, strict, inGlobal bool, evalVm *vm) {
c.ctxVM = evalVm
eval := evalVm != nil
c.p.src = in.File
c.newScope()
scope := c.scope
scope.dynamic = true
scope.eval = eval
if !strict && len(in.Body) > 0 {
strict = c.isStrict(in.Body) != nil
}
scope.strict = strict
ownVarScope := eval && strict
ownLexScope := !inGlobal || eval
if ownVarScope {
c.newBlockScope()
scope = c.scope
scope.variable = true
}
if eval && !inGlobal {
for s := evalVm.stash; s != nil; s = s.outer {
if ft := s.funcType; ft != funcNone && ft != funcArrow {
scope.funcType = ft
break
}
}
}
funcs := c.extractFunctions(in.Body)
c.createFunctionBindings(funcs)
numFuncs := len(scope.bindings)
if inGlobal && !ownVarScope {
if numFuncs == len(funcs) {
c.compileFunctionsGlobalAllUnique(funcs)
} else {
c.compileFunctionsGlobal(funcs)
}
}
c.compileDeclList(in.DeclarationList, false)
numVars := len(scope.bindings) - numFuncs
vars := make([]unistring.String, len(scope.bindings))
for i, b := range scope.bindings {
vars[i] = b.name
}
if len(vars) > 0 && !ownVarScope && ownLexScope {
if inGlobal {
c.emit(&bindGlobal{
vars: vars[numFuncs:],
funcs: vars[:numFuncs],
deletable: eval,
})
} else {
c.emit(&bindVars{names: vars, deletable: eval})
}
}
var enter *enterBlock
if c.compileLexicalDeclarations(in.Body, ownVarScope || !ownLexScope) {
if ownLexScope {
c.block = &block{
outer: c.block,
typ: blockScope,
needResult: true,
}
enter = &enterBlock{}
c.emit(enter)
}
}
if len(scope.bindings) > 0 && !ownLexScope {
var lets, consts []unistring.String
for _, b := range c.scope.bindings[numFuncs+numVars:] {
if b.isConst {
consts = append(consts, b.name)
} else {
lets = append(lets, b.name)
}
}
c.emit(&bindGlobal{
vars: vars[numFuncs:],
funcs: vars[:numFuncs],
lets: lets,
consts: consts,
})
}
if !inGlobal || ownVarScope {
c.compileFunctions(funcs)
}
c.compileStatements(in.Body, true)
if enter != nil {
c.leaveScopeBlock(enter)
c.popScope()
}
scope.finaliseVarAlloc(0)
}
func (c *compiler) compileDeclList(v []*ast.VariableDeclaration, inFunc bool) {
for _, value := range v {
c.createVarBindings(value, inFunc)
}
}
func (c *compiler) extractLabelled(st ast.Statement) ast.Statement {