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neoneo-go/pkg/compiler/codegen.go
Anna Shaleva 800321db06 compiler: rename named unused global vars to "_" 
So that (*codegen).Visit is able to omit code generation for these
unused global vars. The most tricky part is to detect unused global
variables, it is done in several steps:
1. Collect the set of named used/unused global vars.
2. Collect the set of globally declared expressions that contain
function calls.
3. Pick up global vars from the set made at step 2.
4. Traverse used functions and puck up those global vars that are used
from these functions.
5. Rename all globals that are presented in the set made at step 1
but are not presented in the set made on step 3 or step 4.
2022-09-01 13:39:19 +03:00

2498 lines
68 KiB
Go
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package compiler
import (
"encoding/binary"
"errors"
"fmt"
"go/ast"
"go/constant"
"go/token"
"go/types"
"math"
"sort"
"strings"
"github.com/nspcc-dev/neo-go/pkg/encoding/address"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/smartcontract"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/nef"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/util/bitfield"
"github.com/nspcc-dev/neo-go/pkg/vm"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
"golang.org/x/tools/go/packages"
)
type codegen struct {
// Information about the program with all its dependencies.
buildInfo *buildInfo
// prog holds the output buffer.
prog *io.BufBinWriter
// Type information.
typeInfo *types.Info
// pkgInfoInline is a stack of type information for packages containing inline functions.
pkgInfoInline []*packages.Package
// A mapping of func identifiers with their scope.
funcs map[string]*funcScope
// A mapping of lambda functions into their scope.
lambda map[string]*funcScope
// reverseOffsetMap maps function offsets to a local variable count.
reverseOffsetMap map[int]nameWithLocals
// Current funcScope being converted.
scope *funcScope
globals map[string]int
// staticVariables contains global (static in NDX-DN11) variable names and types.
staticVariables []string
// initVariables contains variables local to `_initialize` method.
initVariables []string
// deployVariables contains variables local to `_initialize` method.
deployVariables []string
// A mapping from label's names to their ids.
labels map[labelWithType]uint16
// A list of nested label names together with evaluation stack depth.
labelList []labelWithStackSize
// inlineContext contains info about inlined function calls.
inlineContext []inlineContextSingle
// globalInlineCount contains the amount of auxiliary variables introduced by
// function inlining during global variables initialization.
globalInlineCount int
// A label for the for-loop being currently visited.
currentFor string
// A label for the switch statement being visited.
currentSwitch string
// A label to be used in the next statement.
nextLabel string
// sequencePoints is a mapping from the method name to a slice
// containing info about mapping from opcode's offset
// to a text span in the source file.
sequencePoints map[string][]DebugSeqPoint
// initEndOffset specifies the end of the initialization method.
initEndOffset int
// deployEndOffset specifies the end of the deployment method.
deployEndOffset int
// importMap contains mapping from package aliases to full package names for the current file.
importMap map[string]string
// constMap contains constants from foreign packages.
constMap map[string]types.TypeAndValue
// currPkg is the current package being processed.
currPkg *packages.Package
// mainPkg is the main package metadata.
mainPkg *packages.Package
// packages contains packages in the order they were loaded.
packages []string
packageCache map[string]*packages.Package
// exceptionIndex is the index of the static slot where the exception is stored.
exceptionIndex int
// documents contains paths to all files used by the program.
documents []string
// docIndex maps the file path to the index in the documents array.
docIndex map[string]int
// emittedEvents contains all events emitted by the contract.
emittedEvents map[string][][]string
// invokedContracts contains invoked methods of other contracts.
invokedContracts map[util.Uint160][]string
// Label table for recording jump destinations.
l []int
// Tokens for CALLT instruction
callTokens []nef.MethodToken
}
type labelOffsetType byte
const (
labelStart labelOffsetType = iota // labelStart is a default label type
labelEnd // labelEnd is a type for labels that are targets for break
labelPost // labelPost is a type for labels that are targets for continue
)
type labelWithType struct {
name string
typ labelOffsetType
}
type labelWithStackSize struct {
name string
sz int
}
type nameWithLocals struct {
name string
count int
}
type inlineContextSingle struct {
// labelOffset contains size of labelList at the start of inline call processing.
// For such calls, we need to drop only the newly created part of stack.
labelOffset int
// returnLabel contains label ID pointing to the first instruction right after the call.
returnLabel uint16
}
type varType int
const (
varGlobal varType = iota
varLocal
varArgument
)
// newLabel creates a new label to jump to.
func (c *codegen) newLabel() (l uint16) {
li := len(c.l)
if li > math.MaxUint16 {
c.prog.Err = errors.New("label number is too big")
return
}
l = uint16(li)
c.l = append(c.l, -1)
return
}
// newNamedLabel creates a new label with the specified name.
func (c *codegen) newNamedLabel(typ labelOffsetType, name string) (l uint16) {
l = c.newLabel()
lt := labelWithType{name: name, typ: typ}
c.labels[lt] = l
return
}
func (c *codegen) setLabel(l uint16) {
c.l[l] = c.pc() + 1
}
// pc returns the program offset off the last instruction.
func (c *codegen) pc() int {
return c.prog.Len() - 1
}
func (c *codegen) emitLoadConst(t types.TypeAndValue) {
if c.prog.Err != nil {
return
}
typ, ok := t.Type.Underlying().(*types.Basic)
if !ok {
c.prog.Err = fmt.Errorf("compiler doesn't know how to convert this constant: %v", t)
return
}
switch typ.Kind() {
case types.Int, types.UntypedInt, types.Uint,
types.Int8, types.Uint8,
types.Int16, types.Uint16,
types.Int32, types.Uint32, types.Int64, types.Uint64:
val, _ := constant.Int64Val(t.Value)
emit.Int(c.prog.BinWriter, val)
case types.String, types.UntypedString:
val := constant.StringVal(t.Value)
emit.String(c.prog.BinWriter, val)
case types.Bool, types.UntypedBool:
val := constant.BoolVal(t.Value)
emit.Bool(c.prog.BinWriter, val)
default:
c.prog.Err = fmt.Errorf("compiler doesn't know how to convert this basic type: %v", t)
return
}
}
func (c *codegen) emitLoadField(i int) {
emit.Int(c.prog.BinWriter, int64(i))
emit.Opcodes(c.prog.BinWriter, opcode.PICKITEM)
}
func (c *codegen) emitStoreStructField(i int) {
emit.Int(c.prog.BinWriter, int64(i))
emit.Opcodes(c.prog.BinWriter, opcode.ROT, opcode.SETITEM)
}
// getVarIndex returns variable type and position in the corresponding slot,
// according to the current scope.
func (c *codegen) getVarIndex(pkg string, name string) *varInfo {
if pkg == "" {
if c.scope != nil {
vi := c.scope.vars.getVarInfo(name)
if vi != nil {
return vi
}
}
}
if i, ok := c.globals[c.getIdentName(pkg, name)]; ok {
return &varInfo{refType: varGlobal, index: i}
}
c.scope.newVariable(varLocal, name)
return c.scope.vars.getVarInfo(name)
}
func getBaseOpcode(t varType) (opcode.Opcode, opcode.Opcode) {
switch t {
case varGlobal:
return opcode.LDSFLD0, opcode.STSFLD0
case varLocal:
return opcode.LDLOC0, opcode.STLOC0
case varArgument:
return opcode.LDARG0, opcode.STARG0
default:
panic("invalid type")
}
}
// emitLoadVar loads the specified variable to the evaluation stack.
func (c *codegen) emitLoadVar(pkg string, name string) {
vi := c.getVarIndex(pkg, name)
if vi.ctx != nil && c.typeAndValueOf(vi.ctx.expr).Value != nil {
c.emitLoadConst(c.typeAndValueOf(vi.ctx.expr))
return
} else if vi.ctx != nil {
var oldScope []map[string]varInfo
oldMap := c.importMap
c.importMap = vi.ctx.importMap
if c.scope != nil {
oldScope = c.scope.vars.locals
c.scope.vars.locals = vi.ctx.scope
}
ast.Walk(c, vi.ctx.expr)
if c.scope != nil {
c.scope.vars.locals = oldScope
}
c.importMap = oldMap
return
} else if vi.index == unspecifiedVarIndex {
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
return
}
c.emitLoadByIndex(vi.refType, vi.index)
}
// emitLoadByIndex loads the specified variable type with index i.
func (c *codegen) emitLoadByIndex(t varType, i int) {
base, _ := getBaseOpcode(t)
if i < 7 {
emit.Opcodes(c.prog.BinWriter, base+opcode.Opcode(i))
} else {
emit.Instruction(c.prog.BinWriter, base+7, []byte{byte(i)})
}
}
// emitStoreVar stores top value from the evaluation stack in the specified variable.
func (c *codegen) emitStoreVar(pkg string, name string) {
if name == "_" {
emit.Opcodes(c.prog.BinWriter, opcode.DROP)
return
}
vi := c.getVarIndex(pkg, name)
c.emitStoreByIndex(vi.refType, vi.index)
}
// emitLoadByIndex stores top value in the specified variable type with index i.
func (c *codegen) emitStoreByIndex(t varType, i int) {
_, base := getBaseOpcode(t)
if i < 7 {
emit.Opcodes(c.prog.BinWriter, base+opcode.Opcode(i))
} else {
emit.Instruction(c.prog.BinWriter, base+7, []byte{byte(i)})
}
}
func (c *codegen) emitDefault(t types.Type) {
switch t := t.Underlying().(type) {
case *types.Basic:
info := t.Info()
switch {
case info&types.IsInteger != 0:
emit.Int(c.prog.BinWriter, 0)
case info&types.IsString != 0:
emit.Bytes(c.prog.BinWriter, []byte{})
case info&types.IsBoolean != 0:
emit.Bool(c.prog.BinWriter, false)
default:
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
}
case *types.Struct:
num := t.NumFields()
for i := num - 1; i >= 0; i-- {
c.emitDefault(t.Field(i).Type())
}
emit.Int(c.prog.BinWriter, int64(num))
emit.Opcodes(c.prog.BinWriter, opcode.PACKSTRUCT)
default:
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
}
}
// convertGlobals traverses the AST and only converts global declarations.
// If we call this in convertFuncDecl, it will load all global variables
// into the scope of the function.
func (c *codegen) convertGlobals(f *ast.File) {
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.FuncDecl:
return false
case *ast.GenDecl:
ast.Walk(c, n)
}
return true
})
}
func isInitFunc(decl *ast.FuncDecl) bool {
return decl.Name.Name == "init" && decl.Recv == nil &&
decl.Type.Params.NumFields() == 0 &&
decl.Type.Results.NumFields() == 0
}
func (c *codegen) isVerifyFunc(decl *ast.FuncDecl) bool {
return decl.Name.Name == "Verify" && decl.Recv == nil &&
decl.Type.Results.NumFields() == 1 &&
isBool(c.typeOf(decl.Type.Results.List[0].Type))
}
func (c *codegen) clearSlots(n int) {
for i := 0; i < n; i++ {
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
c.emitStoreByIndex(varLocal, i)
}
}
// convertInitFuncs converts `init()` functions in file f and returns
// the number of locals in the last processed definition as well as maximum locals number encountered.
func (c *codegen) convertInitFuncs(f *ast.File, pkg *types.Package, lastCount int) (int, int) {
maxCount := -1
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.FuncDecl:
if isInitFunc(n) {
if lastCount != -1 {
c.clearSlots(lastCount)
}
f := c.convertFuncDecl(f, n, pkg)
lastCount = f.vars.localsCnt
if lastCount > maxCount {
maxCount = lastCount
}
}
case *ast.GenDecl:
return false
}
return true
})
return lastCount, maxCount
}
func isDeployFunc(decl *ast.FuncDecl) bool {
if decl.Name.Name != "_deploy" || decl.Recv != nil ||
decl.Type.Params.NumFields() != 2 ||
decl.Type.Results.NumFields() != 0 {
return false
}
typ, ok := decl.Type.Params.List[1].Type.(*ast.Ident)
return ok && typ.Name == "bool"
}
func (c *codegen) convertDeployFuncs() int {
maxCount, lastCount := 0, -1
c.ForEachFile(func(f *ast.File, pkg *types.Package) {
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.FuncDecl:
if isDeployFunc(n) {
if lastCount != -1 {
c.clearSlots(lastCount)
}
f := c.convertFuncDecl(f, n, pkg)
lastCount = f.vars.localsCnt
if lastCount > maxCount {
maxCount = lastCount
}
}
case *ast.GenDecl:
return false
}
return true
})
})
return maxCount
}
func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl, pkg *types.Package) *funcScope {
var (
f *funcScope
ok, isLambda bool
)
isInit := isInitFunc(decl)
isDeploy := isDeployFunc(decl)
if isInit || isDeploy {
f = c.newFuncScope(decl, c.newLabel())
} else {
f, ok = c.funcs[c.getFuncNameFromDecl("", decl)]
if ok {
// If this function is a syscall or builtin we will not convert it to bytecode.
if isSyscall(f) || isCustomBuiltin(f) {
return f
}
c.setLabel(f.label)
} else if f, ok = c.lambda[c.getIdentName("", decl.Name.Name)]; ok {
isLambda = ok
c.setLabel(f.label)
} else {
f = c.newFunc(decl)
}
}
f.rng.Start = uint16(c.prog.Len())
c.scope = f
ast.Inspect(decl, c.scope.analyzeVoidCalls) // @OPTIMIZE
// All globals copied into the scope of the function need to be added
// to the stack size of the function.
if !isInit && !isDeploy {
sizeArg := f.countArgs()
if sizeArg > 255 {
c.prog.Err = errors.New("maximum of 255 local variables is allowed")
}
emit.Instruction(c.prog.BinWriter, opcode.INITSLOT, []byte{byte(0), byte(sizeArg)})
}
f.vars.newScope()
defer f.vars.dropScope()
// We need to handle methods, which in Go, is just syntactic sugar.
// The method receiver will be passed in as the first argument.
// We check if this declaration has a receiver and load it into the scope.
//
// FIXME: For now, we will hard cast this to a struct. We can later fine tune this
// to support other types.
if decl.Recv != nil {
for _, arg := range decl.Recv.List {
// Use underscore instead of unnamed receiver name, e.g.:
// func (MyCustomStruct) DoSmth(arg1 int) {...}
// Unnamed receiver will never be referenced, thus we can use the same approach as for multiple unnamed parameters handling, see #2204.
recvName := "_"
if len(arg.Names) != 0 {
recvName = arg.Names[0].Name
}
// only create an argument here, it will be stored via INITSLOT
c.scope.newVariable(varArgument, recvName)
}
}
// Load the arguments in scope.
for _, arg := range decl.Type.Params.List {
for _, id := range arg.Names {
// only create an argument here, it will be stored via INITSLOT
c.scope.newVariable(varArgument, id.Name)
}
}
ast.Walk(c, decl.Body)
// If we have reached the end of the function without encountering `return` statement,
// we should clean alt.stack manually.
// This can be the case with void and named-return functions.
if !isInit && !isDeploy && !lastStmtIsReturn(decl.Body) {
c.processDefers()
c.saveSequencePoint(decl.Body)
emit.Opcodes(c.prog.BinWriter, opcode.RET)
}
if isInit {
c.initVariables = append(c.initVariables, f.variables...)
} else if isDeploy {
c.deployVariables = append(c.deployVariables, f.variables...)
}
f.rng.End = uint16(c.prog.Len() - 1)
if !isLambda {
for _, f := range c.lambda {
if _, ok := c.lambda[c.getIdentName("", f.decl.Name.Name)]; !ok {
panic("ICE: lambda name doesn't match map key")
}
c.convertFuncDecl(file, f.decl, pkg)
}
c.lambda = make(map[string]*funcScope)
}
if !isInit && !isDeploy {
c.reverseOffsetMap[int(f.rng.Start)] = nameWithLocals{
name: f.name,
count: f.vars.localsCnt,
}
}
return f
}
func (c *codegen) Visit(node ast.Node) ast.Visitor {
if c.prog.Err != nil {
return nil
}
switch n := node.(type) {
// General declarations.
// var (
// x = 2
// )
case *ast.GenDecl:
if n.Tok == token.VAR || n.Tok == token.CONST {
c.saveSequencePoint(n)
}
if n.Tok == token.CONST {
for _, spec := range n.Specs {
vs := spec.(*ast.ValueSpec)
for i := range vs.Names {
obj := c.currPkg.Types.Scope().Lookup(vs.Names[i].Name)
if obj != nil { // can be nil if unused
c.constMap[c.getIdentName("", vs.Names[i].Name)] = types.TypeAndValue{
Type: obj.Type(),
Value: obj.(*types.Const).Val(),
}
}
}
}
return nil
}
for _, spec := range n.Specs {
switch t := spec.(type) {
case *ast.ValueSpec:
multiRet := n.Tok == token.VAR && len(t.Values) != 0 && len(t.Names) != len(t.Values)
for _, id := range t.Names {
if id.Name != "_" {
if c.scope == nil {
// it is a global declaration
c.newGlobal("", id.Name)
} else {
c.scope.newLocal(id.Name)
}
if !multiRet {
c.registerDebugVariable(id.Name, t.Type)
}
}
}
for i, id := range t.Names {
if id.Name != "_" {
if len(t.Values) != 0 {
if i == 0 || !multiRet {
ast.Walk(c, t.Values[i])
}
} else {
c.emitDefault(c.typeOf(t.Type))
}
c.emitStoreVar("", t.Names[i].Name)
continue
}
// If var decl contains call then the code should be emitted for it, otherwise - do not evaluate.
if len(t.Values) == 0 {
continue
}
var hasCall bool
if i == 0 || !multiRet {
hasCall = containsCall(t.Values[i])
}
if hasCall {
ast.Walk(c, t.Values[i])
}
if hasCall || i != 0 && multiRet {
c.emitStoreVar("", "_") // drop unused after walk
}
}
}
}
return nil
case *ast.AssignStmt:
multiRet := len(n.Rhs) != len(n.Lhs)
c.saveSequencePoint(n)
// Assign operations are grouped https://github.com/golang/go/blob/master/src/go/types/stmt.go#L160
isAssignOp := token.ADD_ASSIGN <= n.Tok && n.Tok <= token.AND_NOT_ASSIGN
if isAssignOp {
// RHS can contain exactly one expression, thus there is no need to iterate.
ast.Walk(c, n.Lhs[0])
ast.Walk(c, n.Rhs[0])
c.emitToken(n.Tok, c.typeOf(n.Rhs[0]))
}
for i := 0; i < len(n.Lhs); i++ {
switch t := n.Lhs[i].(type) {
case *ast.Ident:
if n.Tok == token.DEFINE {
if !multiRet {
c.registerDebugVariable(t.Name, n.Rhs[i])
}
if t.Name != "_" {
c.scope.newLocal(t.Name)
}
}
if !isAssignOp && (i == 0 || !multiRet) {
ast.Walk(c, n.Rhs[i])
}
c.emitStoreVar("", t.Name)
case *ast.SelectorExpr:
if !isAssignOp {
ast.Walk(c, n.Rhs[i])
}
typ := c.typeOf(t.X)
if c.isInvalidType(typ) {
// Store to other package global variable.
c.emitStoreVar(t.X.(*ast.Ident).Name, t.Sel.Name)
return nil
}
strct, ok := c.getStruct(typ)
if !ok {
c.prog.Err = fmt.Errorf("nested selector assigns not supported yet")
return nil
}
ast.Walk(c, t.X) // load the struct
i := indexOfStruct(strct, t.Sel.Name) // get the index of the field
c.emitStoreStructField(i) // store the field
// Assignments to index expressions.
// slice[0] = 10
case *ast.IndexExpr:
if !isAssignOp {
ast.Walk(c, n.Rhs[i])
}
ast.Walk(c, t.X)
ast.Walk(c, t.Index)
emit.Opcodes(c.prog.BinWriter, opcode.ROT, opcode.SETITEM)
}
}
return nil
case *ast.SliceExpr:
if isCompoundSlice(c.typeOf(n.X).Underlying()) {
c.prog.Err = errors.New("subslices are supported only for []byte")
return nil
}
ast.Walk(c, n.X)
if n.Low != nil {
ast.Walk(c, n.Low)
} else {
emit.Opcodes(c.prog.BinWriter, opcode.PUSH0)
}
if n.High != nil {
ast.Walk(c, n.High)
} else {
emit.Opcodes(c.prog.BinWriter, opcode.OVER, opcode.SIZE)
}
emit.Opcodes(c.prog.BinWriter, opcode.OVER, opcode.SUB, opcode.SUBSTR)
return nil
case *ast.ReturnStmt:
l := c.newLabel()
c.setLabel(l)
cnt := 0
start := 0
if len(c.inlineContext) > 0 {
start = c.inlineContext[len(c.inlineContext)-1].labelOffset
}
for i := start; i < len(c.labelList); i++ {
cnt += c.labelList[i].sz
}
c.dropItems(cnt)
if len(n.Results) == 0 {
results := c.scope.decl.Type.Results
if results.NumFields() != 0 {
// function with named returns
for i := len(results.List) - 1; i >= 0; i-- {
names := results.List[i].Names
for j := len(names) - 1; j >= 0; j-- {
c.emitLoadVar("", names[j].Name)
}
}
}
} else {
// first result should be on top of the stack
for i := len(n.Results) - 1; i >= 0; i-- {
ast.Walk(c, n.Results[i])
}
}
c.processDefers()
c.saveSequencePoint(n)
if len(c.pkgInfoInline) == 0 {
emit.Opcodes(c.prog.BinWriter, opcode.RET)
} else {
emit.Jmp(c.prog.BinWriter, opcode.JMPL, c.inlineContext[len(c.inlineContext)-1].returnLabel)
}
return nil
case *ast.IfStmt:
c.scope.vars.newScope()
defer c.scope.vars.dropScope()
lIf := c.newLabel()
lElse := c.newLabel()
lElseEnd := c.newLabel()
if n.Init != nil {
ast.Walk(c, n.Init)
}
if n.Cond != nil {
c.emitBoolExpr(n.Cond, true, false, lElse)
}
c.setLabel(lIf)
ast.Walk(c, n.Body)
if n.Else != nil {
emit.Jmp(c.prog.BinWriter, opcode.JMPL, lElseEnd)
}
c.setLabel(lElse)
if n.Else != nil {
ast.Walk(c, n.Else)
}
c.setLabel(lElseEnd)
return nil
case *ast.SwitchStmt:
eqOpcode := opcode.EQUAL
if n.Tag != nil {
ast.Walk(c, n.Tag)
eqOpcode, _ = convertToken(token.EQL, c.typeOf(n.Tag))
} else {
emit.Bool(c.prog.BinWriter, true)
}
switchEnd, label := c.generateLabel(labelEnd)
lastSwitch := c.currentSwitch
c.currentSwitch = label
c.pushStackLabel(label, 1)
startLabels := make([]uint16, len(n.Body.List))
for i := range startLabels {
startLabels[i] = c.newLabel()
}
for i := range n.Body.List {
lEnd := c.newLabel()
lStart := startLabels[i]
cc := n.Body.List[i].(*ast.CaseClause)
if l := len(cc.List); l != 0 { // if not `default`
for j := range cc.List {
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
ast.Walk(c, cc.List[j])
emit.Opcodes(c.prog.BinWriter, eqOpcode)
if j == l-1 {
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOTL, lEnd)
} else {
emit.Jmp(c.prog.BinWriter, opcode.JMPIFL, lStart)
}
}
}
c.scope.vars.newScope()
c.setLabel(lStart)
last := len(cc.Body) - 1
for j, stmt := range cc.Body {
if j == last && isFallthroughStmt(stmt) {
emit.Jmp(c.prog.BinWriter, opcode.JMPL, startLabels[i+1])
break
}
ast.Walk(c, stmt)
}
emit.Jmp(c.prog.BinWriter, opcode.JMPL, switchEnd)
c.setLabel(lEnd)
c.scope.vars.dropScope()
}
c.setLabel(switchEnd)
c.dropStackLabel()
c.currentSwitch = lastSwitch
return nil
case *ast.FuncLit:
var found bool
var l uint16
for _, fs := range c.lambda {
if fs.decl.Body == n.Body {
found = true
l = fs.label
break
}
}
if !found {
l = c.newLabel()
c.newLambda(l, n)
}
buf := make([]byte, 4)
binary.LittleEndian.PutUint16(buf, l)
emit.Instruction(c.prog.BinWriter, opcode.PUSHA, buf)
return nil
case *ast.BasicLit:
c.emitLoadConst(c.typeAndValueOf(n))
return nil
case *ast.StarExpr:
_, ok := c.getStruct(c.typeOf(n.X))
if !ok {
c.prog.Err = errors.New("dereferencing is only supported on structs")
return nil
}
ast.Walk(c, n.X)
c.emitConvert(stackitem.StructT)
return nil
case *ast.Ident:
if tv := c.typeAndValueOf(n); tv.Value != nil {
c.emitLoadConst(tv)
} else if n.Name == "nil" {
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
} else {
c.emitLoadVar("", n.Name)
}
return nil
case *ast.CompositeLit:
t := c.typeOf(n)
switch typ := t.Underlying().(type) {
case *types.Struct:
c.convertStruct(n, false)
case *types.Map:
c.convertMap(n)
default:
if tn, ok := t.(*types.Named); ok && isInteropPath(tn.String()) {
st, _, _ := scAndVMInteropTypeFromExpr(tn, false)
expectedLen := -1
switch st {
case smartcontract.Hash160Type:
expectedLen = 20
case smartcontract.Hash256Type:
expectedLen = 32
}
if expectedLen != -1 && expectedLen != len(n.Elts) {
c.prog.Err = fmt.Errorf("%s type must have size %d", tn.Obj().Name(), expectedLen)
return nil
}
}
ln := len(n.Elts)
// ByteArrays needs a different approach than normal arrays.
if isByteSlice(typ) {
c.convertByteArray(n.Elts)
return nil
}
for i := ln - 1; i >= 0; i-- {
ast.Walk(c, n.Elts[i])
}
emit.Int(c.prog.BinWriter, int64(ln))
emit.Opcodes(c.prog.BinWriter, opcode.PACK)
}
return nil
case *ast.BinaryExpr:
c.emitBinaryExpr(n, false, false, 0)
return nil
case *ast.CallExpr:
var (
f *funcScope
ok bool
name string
numArgs = len(n.Args)
isBuiltin bool
isFunc bool
isLiteral bool
)
switch fun := n.Fun.(type) {
case *ast.Ident:
f, ok = c.getFuncFromIdent(fun)
isBuiltin = isGoBuiltin(fun.Name)
if !ok && !isBuiltin {
name = fun.Name
}
// distinguish lambda invocations from type conversions
if fun.Obj != nil && fun.Obj.Kind == ast.Var {
isFunc = true
}
if ok && canInline(f.pkg.Path(), f.decl.Name.Name) {
c.inlineCall(f, n)
return nil
}
case *ast.SelectorExpr:
name, isMethod := c.getFuncNameFromSelector(fun)
f, ok = c.funcs[name]
if ok {
f.selector = fun.X
isBuiltin = isCustomBuiltin(f)
if canInline(f.pkg.Path(), f.decl.Name.Name) {
c.inlineCall(f, n)
return nil
}
} else {
typ := c.typeOf(fun)
ast.Walk(c, n.Args[0])
c.emitExplicitConvert(c.typeOf(n.Args[0]), typ)
return nil
}
if isMethod {
// If this is a method call we need to walk the AST to load the struct locally.
// Otherwise, this is a function call from an imported package and we can call it
// directly.
ast.Walk(c, fun.X)
// Don't forget to add 1 extra argument when it's a method.
numArgs++
}
case *ast.ArrayType:
// For now we will assume that there are only byte slice conversions.
// E.g. []byte("foobar") or []byte(scriptHash).
ast.Walk(c, n.Args[0])
c.emitConvert(stackitem.BufferT)
return nil
case *ast.InterfaceType:
// It's a type conversion into some interface. Programmer is responsible
// for the conversion to be appropriate, just load the arg.
ast.Walk(c, n.Args[0])
return nil
case *ast.FuncLit:
isLiteral = true
}
c.saveSequencePoint(n)
args := transformArgs(f, n.Fun, n.Args)
// Handle the arguments
for _, arg := range args {
ast.Walk(c, arg)
typ := c.typeOf(arg)
_, ok := typ.Underlying().(*types.Struct)
if ok && !isInteropPath(typ.String()) {
// To clone struct fields we create a new array and append struct to it.
// This way even non-pointer struct fields will be copied.
emit.Opcodes(c.prog.BinWriter, opcode.NEWARRAY0,
opcode.DUP, opcode.ROT, opcode.APPEND,
opcode.POPITEM)
}
}
// Do not swap for builtin functions.
if !isBuiltin && (f != nil && !isSyscall(f)) {
typ, ok := c.typeOf(n.Fun).(*types.Signature)
if ok && typ.Variadic() && !n.Ellipsis.IsValid() {
// pack variadic args into an array only if last argument is not of form `...`
varSize := c.packVarArgs(n, typ)
numArgs -= varSize - 1
}
c.emitReverse(numArgs)
}
// Check builtin first to avoid nil pointer on funcScope!
switch {
case isBuiltin:
// Use the ident to check, builtins are not in func scopes.
// We can be sure builtins are of type *ast.Ident.
c.convertBuiltin(n)
case name != "":
// Function was not found, thus it can only be an invocation of a func-typed variable or type conversion.
// We care only about string conversions because all others are effectively no-op in NeoVM.
// E.g. one cannot write `bool(int(a))`, only `int32(int(a))`.
if isString(c.typeOf(n.Fun)) {
c.emitConvert(stackitem.ByteArrayT)
} else if isFunc {
c.emitLoadVar("", name)
emit.Opcodes(c.prog.BinWriter, opcode.CALLA)
}
case isLiteral:
ast.Walk(c, n.Fun)
emit.Opcodes(c.prog.BinWriter, opcode.CALLA)
case isSyscall(f):
c.convertSyscall(f, n)
default:
emit.Call(c.prog.BinWriter, opcode.CALLL, f.label)
}
if c.scope != nil && c.scope.voidCalls[n] {
var sz int
if f != nil {
sz = f.decl.Type.Results.NumFields()
} else if !isBuiltin {
// lambda invocation
f := c.typeOf(n.Fun).Underlying().(*types.Signature)
sz = f.Results().Len()
}
for i := 0; i < sz; i++ {
emit.Opcodes(c.prog.BinWriter, opcode.DROP)
}
}
return nil
case *ast.DeferStmt:
catch := c.newLabel()
finally := c.newLabel()
param := make([]byte, 8)
binary.LittleEndian.PutUint16(param[0:], catch)
binary.LittleEndian.PutUint16(param[4:], finally)
emit.Instruction(c.prog.BinWriter, opcode.TRYL, param)
index := c.scope.newLocal(fmt.Sprintf("defer@%d", n.Call.Pos()))
emit.Opcodes(c.prog.BinWriter, opcode.PUSH1)
c.emitStoreByIndex(varLocal, index)
c.scope.deferStack = append(c.scope.deferStack, deferInfo{
catchLabel: catch,
finallyLabel: finally,
expr: n.Call,
localIndex: index,
})
return nil
case *ast.SelectorExpr:
typ := c.typeOf(n.X)
if c.isInvalidType(typ) {
// This is a global variable from a package.
pkgAlias := n.X.(*ast.Ident).Name
name := c.getIdentName(pkgAlias, n.Sel.Name)
if tv, ok := c.constMap[name]; ok {
c.emitLoadConst(tv)
} else {
c.emitLoadVar(pkgAlias, n.Sel.Name)
}
return nil
}
strct, ok := c.getStruct(typ)
if !ok {
c.prog.Err = fmt.Errorf("selectors are supported only on structs")
return nil
}
ast.Walk(c, n.X) // load the struct
i := indexOfStruct(strct, n.Sel.Name)
c.emitLoadField(i) // load the field
return nil
case *ast.UnaryExpr:
if n.Op == token.AND {
// We support only taking address from struct literals.
// For identifiers we can't support "taking address" in a general way
// because both struct and array are reference types.
lit, ok := n.X.(*ast.CompositeLit)
if ok {
c.convertStruct(lit, true)
return nil
}
c.prog.Err = fmt.Errorf("'&' can be used only with struct literals")
return nil
}
ast.Walk(c, n.X)
// From https://golang.org/ref/spec#Operators
// there can be only following unary operators
// "+" | "-" | "!" | "^" | "*" | "&" | "<-" .
// of which last three are not used in SC
switch n.Op {
case token.ADD:
// +10 == 10, no need to do anything in this case
case token.SUB:
emit.Opcodes(c.prog.BinWriter, opcode.NEGATE)
case token.NOT:
emit.Opcodes(c.prog.BinWriter, opcode.NOT)
case token.XOR:
emit.Opcodes(c.prog.BinWriter, opcode.INVERT)
default:
c.prog.Err = fmt.Errorf("invalid unary operator: %s", n.Op)
return nil
}
return nil
case *ast.IncDecStmt:
ast.Walk(c, n.X)
c.emitToken(n.Tok, c.typeOf(n.X))
// For now, only identifiers are supported for (post) for stmts.
// for i := 0; i < 10; i++ {}
// Where the post stmt is ( i++ )
if ident, ok := n.X.(*ast.Ident); ok {
c.emitStoreVar("", ident.Name)
}
return nil
case *ast.IndexExpr:
// Walk the expression, this could be either an Ident or SelectorExpr.
// This will load local whatever X is.
ast.Walk(c, n.X)
ast.Walk(c, n.Index)
emit.Opcodes(c.prog.BinWriter, opcode.PICKITEM) // just pickitem here
return nil
case *ast.BranchStmt:
var label string
if n.Label != nil {
label = n.Label.Name
} else if n.Tok == token.BREAK {
label = c.currentSwitch
} else if n.Tok == token.CONTINUE {
label = c.currentFor
}
cnt := 0
for i := len(c.labelList) - 1; i >= 0 && c.labelList[i].name != label; i-- {
cnt += c.labelList[i].sz
}
c.dropItems(cnt)
switch n.Tok {
case token.BREAK:
end := c.getLabelOffset(labelEnd, label)
emit.Jmp(c.prog.BinWriter, opcode.JMPL, end)
case token.CONTINUE:
post := c.getLabelOffset(labelPost, label)
emit.Jmp(c.prog.BinWriter, opcode.JMPL, post)
}
return nil
case *ast.LabeledStmt:
c.nextLabel = n.Label.Name
ast.Walk(c, n.Stmt)
return nil
case *ast.BlockStmt:
c.scope.vars.newScope()
defer c.scope.vars.dropScope()
for i := range n.List {
ast.Walk(c, n.List[i])
}
return nil
case *ast.ForStmt:
c.scope.vars.newScope()
defer c.scope.vars.dropScope()
fstart, label := c.generateLabel(labelStart)
fend := c.newNamedLabel(labelEnd, label)
fpost := c.newNamedLabel(labelPost, label)
lastLabel := c.currentFor
lastSwitch := c.currentSwitch
c.currentFor = label
c.currentSwitch = label
// Walk the initializer and condition.
if n.Init != nil {
ast.Walk(c, n.Init)
}
// Set label and walk the condition.
c.pushStackLabel(label, 0)
c.setLabel(fstart)
if n.Cond != nil {
ast.Walk(c, n.Cond)
// Jump if the condition is false
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOTL, fend)
}
// Walk body followed by the iterator (post stmt).
ast.Walk(c, n.Body)
c.setLabel(fpost)
if n.Post != nil {
ast.Walk(c, n.Post)
}
// Jump back to condition.
emit.Jmp(c.prog.BinWriter, opcode.JMPL, fstart)
c.setLabel(fend)
c.dropStackLabel()
c.currentFor = lastLabel
c.currentSwitch = lastSwitch
return nil
case *ast.RangeStmt:
c.scope.vars.newScope()
defer c.scope.vars.dropScope()
start, label := c.generateLabel(labelStart)
end := c.newNamedLabel(labelEnd, label)
post := c.newNamedLabel(labelPost, label)
lastFor := c.currentFor
lastSwitch := c.currentSwitch
c.currentFor = label
c.currentSwitch = label
ast.Walk(c, n.X)
// Implementation is a bit different for slices and maps:
// For slices, we iterate through indices from 0 to len-1, storing array, len and index on stack.
// For maps, we iterate through indices from 0 to len-1, storing map, keyarray, size and index on stack.
_, isMap := c.typeOf(n.X).Underlying().(*types.Map)
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
if isMap {
emit.Opcodes(c.prog.BinWriter, opcode.KEYS, opcode.DUP)
}
emit.Opcodes(c.prog.BinWriter, opcode.SIZE, opcode.PUSH0)
stackSize := 3 // slice, len(slice), index
if isMap {
stackSize++ // map, keys, len(keys), index in keys
}
c.pushStackLabel(label, stackSize)
c.setLabel(start)
emit.Opcodes(c.prog.BinWriter, opcode.OVER, opcode.OVER)
emit.Jmp(c.prog.BinWriter, opcode.JMPLEL, end)
var keyLoaded bool
needValue := n.Value != nil && n.Value.(*ast.Ident).Name != "_"
if n.Key != nil && n.Key.(*ast.Ident).Name != "_" {
if isMap {
c.rangeLoadKey()
if needValue {
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
keyLoaded = true
}
} else {
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
}
c.emitStoreVar("", n.Key.(*ast.Ident).Name)
}
if needValue {
if !isMap || !keyLoaded {
c.rangeLoadKey()
}
if isMap {
// we have loaded only key from key array, now load value
emit.Int(c.prog.BinWriter, 4)
emit.Opcodes(c.prog.BinWriter,
opcode.PICK, // load map itself (+1 because key was pushed)
opcode.SWAP, // key should be on top
opcode.PICKITEM)
}
c.emitStoreVar("", n.Value.(*ast.Ident).Name)
}
ast.Walk(c, n.Body)
c.setLabel(post)
emit.Opcodes(c.prog.BinWriter, opcode.INC)
emit.Jmp(c.prog.BinWriter, opcode.JMPL, start)
c.setLabel(end)
c.dropStackLabel()
c.currentFor = lastFor
c.currentSwitch = lastSwitch
return nil
// We don't really care about assertions for the core logic.
// The only thing we need is to please the compiler type checking.
// For this to work properly, we only need to walk the expression
// which is not the assertion type.
case *ast.TypeAssertExpr:
ast.Walk(c, n.X)
if c.isCallExprSyscall(n.X) {
return nil
}
goTyp := c.typeOf(n.Type)
if canConvert(goTyp.String()) {
typ := toNeoType(goTyp)
c.emitConvert(typ)
}
return nil
}
return c
}
// packVarArgs packs variadic arguments into an array
// and returns the amount of arguments packed.
func (c *codegen) packVarArgs(n *ast.CallExpr, typ *types.Signature) int {
varSize := len(n.Args) - typ.Params().Len() + 1
c.emitReverse(varSize)
emit.Int(c.prog.BinWriter, int64(varSize))
emit.Opcodes(c.prog.BinWriter, opcode.PACK)
return varSize
}
func (c *codegen) isCallExprSyscall(e ast.Expr) bool {
ce, ok := e.(*ast.CallExpr)
if !ok {
return false
}
sel, ok := ce.Fun.(*ast.SelectorExpr)
if !ok {
return false
}
name, _ := c.getFuncNameFromSelector(sel)
f, ok := c.funcs[name]
return ok && isSyscall(f)
}
// processDefers emits code for `defer` statements.
// TRY-related opcodes handle exception as follows:
// 1. CATCH block is executed only if exception has occurred.
// 2. FINALLY block is always executed, but after catch block.
//
// Go `defer` statements are a bit different:
// 1. `defer` is always executed irregardless of whether an exception has occurred.
// 2. `recover` can or can not handle a possible exception.
//
// Thus, we use the following approach:
// 1. Throwed exception is saved in a static field X, static fields Y and it is set to true.
// 2. For each defer local there is a dedicated local variable which is set to 1 if `defer` statement
// is encountered during an actual execution.
// 3. CATCH and FINALLY blocks are the same, and both contain the same CALLs.
// 4. Right before the CATCH block, check a variable from (2). If it is null, jump to the end of CATCH+FINALLY block.
// 5. In CATCH block we set Y to true and emit default return values if it is the last defer.
// 6. Execute FINALLY block only if Y is false.
func (c *codegen) processDefers() {
for i := len(c.scope.deferStack) - 1; i >= 0; i-- {
stmt := c.scope.deferStack[i]
after := c.newLabel()
c.emitLoadByIndex(varLocal, c.scope.deferStack[i].localIndex)
emit.Opcodes(c.prog.BinWriter, opcode.ISNULL)
emit.Jmp(c.prog.BinWriter, opcode.JMPIFL, after)
emit.Jmp(c.prog.BinWriter, opcode.ENDTRYL, after)
c.setLabel(stmt.catchLabel)
c.emitStoreByIndex(varGlobal, c.exceptionIndex)
emit.Int(c.prog.BinWriter, 1)
finalIndex := c.getVarIndex("", finallyVarName).index
c.emitStoreByIndex(varLocal, finalIndex)
ast.Walk(c, stmt.expr)
if i == 0 {
results := c.scope.decl.Type.Results
if results.NumFields() != 0 {
// After panic, default values must be returns, except for named returns,
// which we don't support here for now.
for i := len(results.List) - 1; i >= 0; i-- {
c.emitDefault(c.typeOf(results.List[i].Type))
}
}
}
emit.Jmp(c.prog.BinWriter, opcode.ENDTRYL, after)
c.setLabel(stmt.finallyLabel)
before := c.newLabel()
c.emitLoadByIndex(varLocal, finalIndex)
emit.Jmp(c.prog.BinWriter, opcode.JMPIFL, before)
ast.Walk(c, stmt.expr)
c.setLabel(before)
emit.Int(c.prog.BinWriter, 0)
c.emitStoreByIndex(varLocal, finalIndex)
emit.Opcodes(c.prog.BinWriter, opcode.ENDFINALLY)
c.setLabel(after)
}
}
// emitExplicitConvert handles `someType(someValue)` conversions between string/[]byte.
// Rules for conversion:
// 1. interop.* types are converted to ByteArray if not already.
// 2. Otherwise, convert between ByteArray/Buffer.
// 3. Rules for types which are not string/[]byte should already
// be enforced by go parser.
func (c *codegen) emitExplicitConvert(from, to types.Type) {
if isInteropPath(to.String()) {
if isByteSlice(from) && !isString(from) {
c.emitConvert(stackitem.ByteArrayT)
}
} else if isByteSlice(to) && !isByteSlice(from) {
c.emitConvert(stackitem.BufferT)
} else if isString(to) && !isString(from) {
c.emitConvert(stackitem.ByteArrayT)
}
}
func (c *codegen) isInvalidType(typ types.Type) bool {
tb, ok := typ.(*types.Basic)
return typ == nil || ok && tb.Kind() == types.Invalid
}
func (c *codegen) rangeLoadKey() {
emit.Int(c.prog.BinWriter, 2)
emit.Opcodes(c.prog.BinWriter,
opcode.PICK, // load keys
opcode.OVER, // load index in key array
opcode.PICKITEM)
}
func isFallthroughStmt(c ast.Node) bool {
s, ok := c.(*ast.BranchStmt)
return ok && s.Tok == token.FALLTHROUGH
}
func (c *codegen) getCompareWithNilArg(n *ast.BinaryExpr) ast.Expr {
if isExprNil(n.X) {
return n.Y
} else if isExprNil(n.Y) {
return n.X
}
return nil
}
func (c *codegen) emitJumpOnCondition(cond bool, jmpLabel uint16) {
if cond {
emit.Jmp(c.prog.BinWriter, opcode.JMPIFL, jmpLabel)
} else {
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOTL, jmpLabel)
}
}
// emitBoolExpr emits boolean expression. If needJump is true and expression evaluates to `cond`,
// jump to jmpLabel is performed and no item is left on stack.
func (c *codegen) emitBoolExpr(n ast.Expr, needJump bool, cond bool, jmpLabel uint16) {
if be, ok := n.(*ast.BinaryExpr); ok {
c.emitBinaryExpr(be, needJump, cond, jmpLabel)
} else {
ast.Walk(c, n)
if needJump {
c.emitJumpOnCondition(cond, jmpLabel)
}
}
}
// emitBinaryExpr emits binary expression. If needJump is true and expression evaluates to `cond`,
// jump to jmpLabel is performed and no item is left on stack.
func (c *codegen) emitBinaryExpr(n *ast.BinaryExpr, needJump bool, cond bool, jmpLabel uint16) {
// The AST package will try to resolve all basic literals for us.
// If the typeinfo.Value is not nil we know that the expr is resolved
// and needs no further action. e.g. x := 2 + 2 + 2 will be resolved to 6.
// NOTE: Constants will also be automatically resolved be the AST parser.
// example:
// const x = 10
// x + 2 will results into 12
tinfo := c.typeAndValueOf(n)
if tinfo.Value != nil {
c.emitLoadConst(tinfo)
if needJump && isBool(tinfo.Type) {
c.emitJumpOnCondition(cond, jmpLabel)
}
return
} else if arg := c.getCompareWithNilArg(n); arg != nil {
ast.Walk(c, arg)
emit.Opcodes(c.prog.BinWriter, opcode.ISNULL)
if needJump {
c.emitJumpOnCondition(cond == (n.Op == token.EQL), jmpLabel)
} else if n.Op == token.NEQ {
emit.Opcodes(c.prog.BinWriter, opcode.NOT)
}
return
}
switch n.Op {
case token.LAND, token.LOR:
end := c.newLabel()
// true || .. == true, false && .. == false
condShort := n.Op == token.LOR
if needJump {
l := end
if cond == condShort {
l = jmpLabel
}
c.emitBoolExpr(n.X, true, condShort, l)
c.emitBoolExpr(n.Y, true, cond, jmpLabel)
} else {
push := c.newLabel()
c.emitBoolExpr(n.X, true, condShort, push)
c.emitBoolExpr(n.Y, false, false, 0)
emit.Jmp(c.prog.BinWriter, opcode.JMPL, end)
c.setLabel(push)
emit.Bool(c.prog.BinWriter, condShort)
}
c.setLabel(end)
default:
ast.Walk(c, n.X)
ast.Walk(c, n.Y)
typ := c.typeOf(n.X)
if !needJump {
c.emitToken(n.Op, typ)
return
}
op, ok := getJumpForToken(n.Op, typ)
if !ok {
c.emitToken(n.Op, typ)
c.emitJumpOnCondition(cond, jmpLabel)
return
}
if !cond {
op = negateJmp(op)
}
emit.Jmp(c.prog.BinWriter, op, jmpLabel)
}
}
func (c *codegen) pushStackLabel(name string, size int) {
c.labelList = append(c.labelList, labelWithStackSize{
name: name,
sz: size,
})
}
func (c *codegen) dropStackLabel() {
last := len(c.labelList) - 1
c.dropItems(c.labelList[last].sz)
c.labelList = c.labelList[:last]
}
func (c *codegen) dropItems(n int) {
if n < 4 {
for i := 0; i < n; i++ {
emit.Opcodes(c.prog.BinWriter, opcode.DROP)
}
return
}
emit.Int(c.prog.BinWriter, int64(n))
emit.Opcodes(c.prog.BinWriter, opcode.PACK, opcode.DROP)
}
// emitReverse reverses top num items of the stack.
func (c *codegen) emitReverse(num int) {
switch num {
case 0, 1:
case 2:
emit.Opcodes(c.prog.BinWriter, opcode.SWAP)
case 3:
emit.Opcodes(c.prog.BinWriter, opcode.REVERSE3)
case 4:
emit.Opcodes(c.prog.BinWriter, opcode.REVERSE4)
default:
emit.Int(c.prog.BinWriter, int64(num))
emit.Opcodes(c.prog.BinWriter, opcode.REVERSEN)
}
}
// generateLabel returns a new label.
func (c *codegen) generateLabel(typ labelOffsetType) (uint16, string) {
name := c.nextLabel
if name == "" {
name = fmt.Sprintf("@%d", len(c.l))
}
c.nextLabel = ""
return c.newNamedLabel(typ, name), name
}
func (c *codegen) getLabelOffset(typ labelOffsetType, name string) uint16 {
return c.labels[labelWithType{name: name, typ: typ}]
}
// For `&&` and `||` it return an opcode which jumps only if result is known:
// false && .. == false, true || .. = true.
func getJumpForToken(tok token.Token, typ types.Type) (opcode.Opcode, bool) {
switch tok {
case token.GTR:
return opcode.JMPGTL, true
case token.GEQ:
return opcode.JMPGEL, true
case token.LSS:
return opcode.JMPLTL, true
case token.LEQ:
return opcode.JMPLEL, true
case token.EQL, token.NEQ:
if isNumber(typ) {
if tok == token.EQL {
return opcode.JMPEQL, true
}
return opcode.JMPNEL, true
}
}
return 0, false
}
func (c *codegen) getCallToken(hash util.Uint160, method string, pcount int, hasReturn bool, flag callflag.CallFlag) (uint16, error) {
needed := nef.MethodToken{
Hash: hash,
Method: method,
ParamCount: uint16(pcount),
HasReturn: hasReturn,
CallFlag: flag,
}
for i := range c.callTokens {
if c.callTokens[i] == needed {
return uint16(i), nil
}
}
if len(c.callTokens) == math.MaxUint16 {
return 0, errors.New("call token overflow")
}
c.callTokens = append(c.callTokens, needed)
return uint16(len(c.callTokens) - 1), nil
}
func (c *codegen) convertSyscall(f *funcScope, expr *ast.CallExpr) {
var callArgs = expr.Args[1:]
if strings.HasPrefix(f.name, "CallWithToken") {
callArgs = expr.Args[3:]
}
for _, arg := range callArgs {
ast.Walk(c, arg)
}
tv := c.typeAndValueOf(expr.Args[0])
if tv.Value == nil || !isString(tv.Type) {
c.prog.Err = fmt.Errorf("bad intrinsic argument")
return
}
arg0Str := constant.StringVal(tv.Value)
if strings.HasPrefix(f.name, "Syscall") {
c.emitReverse(len(callArgs))
emit.Syscall(c.prog.BinWriter, arg0Str)
} else if strings.HasPrefix(f.name, "CallWithToken") {
var hasRet = !strings.HasSuffix(f.name, "NoRet")
c.emitReverse(len(callArgs))
hash, err := util.Uint160DecodeBytesBE([]byte(arg0Str))
if err != nil {
c.prog.Err = fmt.Errorf("bad callt hash: %w", err)
return
}
tv = c.typeAndValueOf(expr.Args[1])
if tv.Value == nil || !isString(tv.Type) {
c.prog.Err = errors.New("bad callt method")
return
}
method := constant.StringVal(tv.Value)
tv = c.typeAndValueOf(expr.Args[2])
if tv.Value == nil || !isNumber(tv.Type) {
c.prog.Err = errors.New("bad callt call flags")
return
}
flag, ok := constant.Uint64Val(tv.Value)
if !ok || flag > 255 {
c.prog.Err = errors.New("invalid callt flag")
return
}
c.appendInvokedContract(hash, method, flag)
tokNum, err := c.getCallToken(hash, method, len(callArgs), hasRet, callflag.CallFlag(flag))
if err != nil {
c.prog.Err = err
return
}
tokBuf := make([]byte, 2)
binary.LittleEndian.PutUint16(tokBuf, tokNum)
emit.Instruction(c.prog.BinWriter, opcode.CALLT, tokBuf)
} else {
op, err := opcode.FromString(arg0Str)
if err != nil {
c.prog.Err = fmt.Errorf("invalid opcode: %s", op)
return
}
emit.Opcodes(c.prog.BinWriter, op)
}
}
// emitSliceHelper emits 3 items on stack: slice, its first index, and its size.
func (c *codegen) emitSliceHelper(e ast.Expr) {
if !isByteSlice(c.typeOf(e)) {
c.prog.Err = fmt.Errorf("copy is supported only for byte-slices")
return
}
var hasLowIndex bool
switch src := e.(type) {
case *ast.SliceExpr:
ast.Walk(c, src.X)
if src.High != nil {
ast.Walk(c, src.High)
} else {
emit.Opcodes(c.prog.BinWriter, opcode.DUP, opcode.SIZE)
}
if src.Low != nil {
ast.Walk(c, src.Low)
hasLowIndex = true
} else {
emit.Int(c.prog.BinWriter, 0)
}
default:
ast.Walk(c, src)
emit.Opcodes(c.prog.BinWriter, opcode.DUP, opcode.SIZE)
emit.Int(c.prog.BinWriter, 0)
}
if !hasLowIndex {
emit.Opcodes(c.prog.BinWriter, opcode.SWAP)
} else {
emit.Opcodes(c.prog.BinWriter, opcode.DUP, opcode.ROT, opcode.SWAP, opcode.SUB)
}
}
func (c *codegen) convertBuiltin(expr *ast.CallExpr) {
var name string
switch t := expr.Fun.(type) {
case *ast.Ident:
name = t.Name
case *ast.SelectorExpr:
name = t.Sel.Name
}
switch name {
case "copy":
// stack for MEMCPY is: dst, dst_index, src, src_index, count
c.emitSliceHelper(expr.Args[0])
c.emitSliceHelper(expr.Args[1])
emit.Int(c.prog.BinWriter, 3)
emit.Opcodes(c.prog.BinWriter, opcode.ROLL, opcode.MIN)
if !c.scope.voidCalls[expr] {
// insert top item to the bottom of MEMCPY args, so that it is left on stack
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
emit.Int(c.prog.BinWriter, 6)
emit.Opcodes(c.prog.BinWriter, opcode.REVERSEN)
emit.Int(c.prog.BinWriter, 5)
emit.Opcodes(c.prog.BinWriter, opcode.REVERSEN)
}
emit.Opcodes(c.prog.BinWriter, opcode.MEMCPY)
case "make":
typ := c.typeOf(expr.Args[0])
switch {
case isMap(typ):
emit.Opcodes(c.prog.BinWriter, opcode.NEWMAP)
default:
if len(expr.Args) == 3 {
c.prog.Err = fmt.Errorf("`make()` with a capacity argument is not supported")
return
}
ast.Walk(c, expr.Args[1])
if isByteSlice(typ) {
emit.Opcodes(c.prog.BinWriter, opcode.NEWBUFFER)
} else {
neoT := toNeoType(typ.(*types.Slice).Elem())
emit.Instruction(c.prog.BinWriter, opcode.NEWARRAYT, []byte{byte(neoT)})
}
}
case "len":
emit.Opcodes(c.prog.BinWriter, opcode.DUP, opcode.ISNULL)
emit.Instruction(c.prog.BinWriter, opcode.JMPIF, []byte{2 + 1 + 2})
emit.Opcodes(c.prog.BinWriter, opcode.SIZE)
emit.Instruction(c.prog.BinWriter, opcode.JMP, []byte{2 + 1 + 1})
emit.Opcodes(c.prog.BinWriter, opcode.DROP, opcode.PUSH0)
case "append":
arg := expr.Args[0]
typ := c.typeInfo.Types[arg].Type
ast.Walk(c, arg)
emit.Opcodes(c.prog.BinWriter, opcode.DUP, opcode.ISNULL)
if isByteSlice(typ) {
emit.Instruction(c.prog.BinWriter, opcode.JMPIFNOT, []byte{2 + 3})
emit.Opcodes(c.prog.BinWriter, opcode.DROP, opcode.PUSHDATA1, 0)
if expr.Ellipsis.IsValid() {
ast.Walk(c, expr.Args[1])
} else {
c.convertByteArray(expr.Args[1:])
}
emit.Opcodes(c.prog.BinWriter, opcode.CAT)
} else {
emit.Instruction(c.prog.BinWriter, opcode.JMPIFNOT, []byte{2 + 2})
emit.Opcodes(c.prog.BinWriter, opcode.DROP, opcode.NEWARRAY0)
if expr.Ellipsis.IsValid() {
ast.Walk(c, expr.Args[1]) // x y
emit.Opcodes(c.prog.BinWriter, opcode.PUSH0) // x y cnt=0
start := c.newLabel()
c.setLabel(start)
emit.Opcodes(c.prog.BinWriter, opcode.PUSH2, opcode.PICK) // x y cnt x
emit.Opcodes(c.prog.BinWriter, opcode.PUSH2, opcode.PICK) // x y cnt x y
emit.Opcodes(c.prog.BinWriter, opcode.DUP, opcode.SIZE) // x y cnt x y len(y)
emit.Opcodes(c.prog.BinWriter, opcode.PUSH3, opcode.PICK) // x y cnt x y len(y) cnt
after := c.newLabel()
emit.Jmp(c.prog.BinWriter, opcode.JMPEQL, after) // x y cnt x y
emit.Opcodes(c.prog.BinWriter, opcode.PUSH2, opcode.PICK, // x y cnt x y cnt
opcode.PICKITEM, // x y cnt x y[cnt]
opcode.APPEND, // x=append(x, y[cnt]) y cnt
opcode.INC) // x y cnt+1
emit.Jmp(c.prog.BinWriter, opcode.JMPL, start)
c.setLabel(after)
for i := 0; i < 4; i++ { // leave x on stack
emit.Opcodes(c.prog.BinWriter, opcode.DROP)
}
} else {
for _, e := range expr.Args[1:] {
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
ast.Walk(c, e)
emit.Opcodes(c.prog.BinWriter, opcode.APPEND)
}
}
}
case "panic":
emit.Opcodes(c.prog.BinWriter, opcode.THROW)
case "recover":
if !c.scope.voidCalls[expr] {
c.emitLoadByIndex(varGlobal, c.exceptionIndex)
}
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
c.emitStoreByIndex(varGlobal, c.exceptionIndex)
case "delete":
emit.Opcodes(c.prog.BinWriter, opcode.REMOVE)
case "FromAddress":
// We can be sure that this is a ast.BasicLit just containing a simple
// address string. Note that the string returned from calling Value will
// contain double quotes that need to be stripped.
addressStr := expr.Args[0].(*ast.BasicLit).Value
addressStr = strings.Replace(addressStr, "\"", "", 2)
uint160, err := address.StringToUint160(addressStr)
if err != nil {
c.prog.Err = err
return
}
bytes := uint160.BytesBE()
emit.Bytes(c.prog.BinWriter, bytes)
c.emitConvert(stackitem.BufferT)
}
}
// transformArgs returns a list of function arguments
// which should be put on stack.
// There are special cases for builtins:
// 1. With FromAddress, parameter conversion is happening at compile-time
// so there is no need to push parameters on stack and perform an actual call
// 2. With panic, the generated code depends on the fact if an argument was nil or a string;
// so, it should be handled accordingly.
func transformArgs(fs *funcScope, fun ast.Expr, args []ast.Expr) []ast.Expr {
switch f := fun.(type) {
case *ast.SelectorExpr:
if f.Sel.Name == "FromAddress" {
return args[1:]
}
if fs != nil && isSyscall(fs) {
return nil
}
case *ast.Ident:
switch f.Name {
case "make", "copy", "append":
return nil
}
}
return args
}
// emitConvert converts the top stack item to the specified type.
func (c *codegen) emitConvert(typ stackitem.Type) {
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
emit.Instruction(c.prog.BinWriter, opcode.ISTYPE, []byte{byte(typ)})
emit.Instruction(c.prog.BinWriter, opcode.JMPIF, []byte{2 + 2}) // After CONVERT.
emit.Instruction(c.prog.BinWriter, opcode.CONVERT, []byte{byte(typ)})
}
func (c *codegen) convertByteArray(elems []ast.Expr) {
buf := make([]byte, len(elems))
varIndices := []int{}
for i := 0; i < len(elems); i++ {
t := c.typeAndValueOf(elems[i])
if t.Value != nil {
val, _ := constant.Int64Val(t.Value)
buf[i] = byte(val)
} else {
varIndices = append(varIndices, i)
}
}
emit.Bytes(c.prog.BinWriter, buf)
c.emitConvert(stackitem.BufferT)
for _, i := range varIndices {
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
emit.Int(c.prog.BinWriter, int64(i))
ast.Walk(c, elems[i])
emit.Opcodes(c.prog.BinWriter, opcode.SETITEM)
}
}
func (c *codegen) convertMap(lit *ast.CompositeLit) {
l := len(lit.Elts)
for i := l - 1; i >= 0; i-- {
elem := lit.Elts[i].(*ast.KeyValueExpr)
ast.Walk(c, elem.Value)
ast.Walk(c, elem.Key)
}
emit.Int(c.prog.BinWriter, int64(l))
emit.Opcodes(c.prog.BinWriter, opcode.PACKMAP)
}
func (c *codegen) getStruct(typ types.Type) (*types.Struct, bool) {
switch t := typ.Underlying().(type) {
case *types.Struct:
return t, true
case *types.Pointer:
strct, ok := t.Elem().Underlying().(*types.Struct)
return strct, ok
default:
return nil, false
}
}
func (c *codegen) convertStruct(lit *ast.CompositeLit, ptr bool) {
// Create a new structScope to initialize and store
// the positions of its variables.
strct, ok := c.typeOf(lit).Underlying().(*types.Struct)
if !ok {
c.prog.Err = fmt.Errorf("the given literal is not of type struct: %v", lit)
return
}
keyedLit := len(lit.Elts) > 0
if keyedLit {
_, ok := lit.Elts[0].(*ast.KeyValueExpr)
keyedLit = keyedLit && ok
}
// We need to locally store all the fields, even if they are not initialized.
// We will initialize all fields to their "zero" value.
for i := strct.NumFields() - 1; i >= 0; i-- {
sField := strct.Field(i)
var initialized bool
if !keyedLit {
if len(lit.Elts) > i {
ast.Walk(c, lit.Elts[i])
initialized = true
}
} else {
// Fields initialized by the program.
for _, field := range lit.Elts {
f := field.(*ast.KeyValueExpr)
fieldName := f.Key.(*ast.Ident).Name
if sField.Name() == fieldName {
ast.Walk(c, f.Value)
initialized = true
break
}
}
}
if !initialized {
c.emitDefault(sField.Type())
}
}
emit.Int(c.prog.BinWriter, int64(strct.NumFields()))
if ptr {
emit.Opcodes(c.prog.BinWriter, opcode.PACK)
} else {
emit.Opcodes(c.prog.BinWriter, opcode.PACKSTRUCT)
}
}
func (c *codegen) emitToken(tok token.Token, typ types.Type) {
op, err := convertToken(tok, typ)
if err != nil {
c.prog.Err = err
return
}
emit.Opcodes(c.prog.BinWriter, op)
}
func convertToken(tok token.Token, typ types.Type) (opcode.Opcode, error) {
switch tok {
case token.ADD_ASSIGN, token.ADD:
// VM has separate opcodes for number and string concatenation
if isString(typ) {
return opcode.CAT, nil
}
return opcode.ADD, nil
case token.SUB_ASSIGN:
return opcode.SUB, nil
case token.MUL_ASSIGN:
return opcode.MUL, nil
case token.QUO_ASSIGN:
return opcode.DIV, nil
case token.REM_ASSIGN:
return opcode.MOD, nil
case token.SUB:
return opcode.SUB, nil
case token.MUL:
return opcode.MUL, nil
case token.QUO:
return opcode.DIV, nil
case token.REM:
return opcode.MOD, nil
case token.LSS:
return opcode.LT, nil
case token.LEQ:
return opcode.LE, nil
case token.GTR:
return opcode.GT, nil
case token.GEQ:
return opcode.GE, nil
case token.EQL:
// VM has separate opcodes for number and string equality
if isNumber(typ) {
return opcode.NUMEQUAL, nil
}
return opcode.EQUAL, nil
case token.NEQ:
// VM has separate opcodes for number and string equality
if isNumber(typ) {
return opcode.NUMNOTEQUAL, nil
}
return opcode.NOTEQUAL, nil
case token.DEC:
return opcode.DEC, nil
case token.INC:
return opcode.INC, nil
case token.NOT:
return opcode.NOT, nil
case token.AND:
return opcode.AND, nil
case token.OR:
return opcode.OR, nil
case token.SHL:
return opcode.SHL, nil
case token.SHR:
return opcode.SHR, nil
case token.XOR:
return opcode.XOR, nil
default:
return 0, fmt.Errorf("compiler could not convert token: %s", tok)
}
}
func (c *codegen) newFunc(decl *ast.FuncDecl) *funcScope {
f := c.newFuncScope(decl, c.newLabel())
c.funcs[c.getFuncNameFromDecl("", decl)] = f
return f
}
func (c *codegen) getFuncFromIdent(fun *ast.Ident) (*funcScope, bool) {
var pkgName string
if len(c.pkgInfoInline) != 0 {
pkgName = c.pkgInfoInline[len(c.pkgInfoInline)-1].PkgPath
}
f, ok := c.funcs[c.getIdentName(pkgName, fun.Name)]
return f, ok
}
// getFuncNameFromSelector returns fully-qualified function name from the selector expression.
// Second return value is true iff this was a method call, not foreign package call.
func (c *codegen) getFuncNameFromSelector(e *ast.SelectorExpr) (string, bool) {
if c.typeInfo.Selections[e] != nil {
typ := c.typeInfo.Types[e.X].Type.String()
name := c.getIdentName(typ, e.Sel.Name)
if name[0] == '*' {
name = name[1:]
}
return name, true
}
ident := e.X.(*ast.Ident)
return c.getIdentName(ident.Name, e.Sel.Name), false
}
func (c *codegen) newLambda(u uint16, lit *ast.FuncLit) {
name := fmt.Sprintf("lambda@%d", u)
f := c.newFuncScope(&ast.FuncDecl{
Name: ast.NewIdent(name),
Type: lit.Type,
Body: lit.Body,
}, u)
c.lambda[c.getFuncNameFromDecl("", f.decl)] = f
}
func (c *codegen) compile(info *buildInfo, pkg *packages.Package) error {
c.mainPkg = pkg
c.analyzePkgOrder()
c.fillDocumentInfo()
funUsage := c.analyzeFuncAndGlobalVarUsage()
if c.prog.Err != nil {
return c.prog.Err
}
// Bring all imported functions into scope.
c.ForEachFile(c.resolveFuncDecls)
hasDeploy := c.traverseGlobals()
if hasDeploy {
deployOffset := c.prog.Len()
emit.Instruction(c.prog.BinWriter, opcode.INITSLOT, []byte{0, 2})
locCount := c.convertDeployFuncs()
c.reverseOffsetMap[deployOffset] = nameWithLocals{
name: "_deploy",
count: locCount,
}
c.deployEndOffset = c.prog.Len()
emit.Opcodes(c.prog.BinWriter, opcode.RET)
}
// sort map keys to generate code deterministically.
keys := make([]*types.Package, 0, len(info.program))
for _, p := range info.program {
keys = append(keys, p.Types)
}
sort.Slice(keys, func(i, j int) bool { return keys[i].Path() < keys[j].Path() })
// Generate the code for the program.
c.ForEachFile(func(f *ast.File, pkg *types.Package) {
for _, decl := range f.Decls {
switch n := decl.(type) {
case *ast.FuncDecl:
// Don't convert the function if it's not used. This will save a lot
// of bytecode space.
pkgPath := ""
if pkg != c.mainPkg.Types { // not a main package
pkgPath = pkg.Path()
}
name := c.getFuncNameFromDecl(pkgPath, n)
if !isInitFunc(n) && !isDeployFunc(n) && funUsage.funcUsed(name) &&
(!isInteropPath(pkg.Path()) && !canInline(pkg.Path(), n.Name.Name)) {
c.convertFuncDecl(f, n, pkg)
}
}
}
})
return c.prog.Err
}
func newCodegen(info *buildInfo, pkg *packages.Package) *codegen {
return &codegen{
buildInfo: info,
prog: io.NewBufBinWriter(),
l: []int{},
funcs: map[string]*funcScope{},
lambda: map[string]*funcScope{},
reverseOffsetMap: map[int]nameWithLocals{},
globals: map[string]int{},
labels: map[labelWithType]uint16{},
typeInfo: pkg.TypesInfo,
constMap: map[string]types.TypeAndValue{},
docIndex: map[string]int{},
packageCache: map[string]*packages.Package{},
initEndOffset: -1,
deployEndOffset: -1,
emittedEvents: make(map[string][][]string),
invokedContracts: make(map[util.Uint160][]string),
sequencePoints: make(map[string][]DebugSeqPoint),
}
}
// codeGen compiles the program to bytecode.
func codeGen(info *buildInfo) (*nef.File, *DebugInfo, error) {
if len(info.program) == 0 {
return nil, nil, errors.New("empty package")
}
pkg := info.program[0]
c := newCodegen(info, pkg)
if err := c.compile(info, pkg); err != nil {
return nil, nil, err
}
buf, err := c.writeJumps(c.prog.Bytes())
if err != nil {
return nil, nil, err
}
methods := bitfield.New(len(buf))
di := c.emitDebugInfo(buf)
for i := range di.Methods {
methods.Set(int(di.Methods[i].Range.Start))
}
f, err := nef.NewFile(buf)
if err != nil {
return nil, nil, fmt.Errorf("error while trying to create .nef file: %w", err)
}
if c.callTokens != nil {
f.Tokens = c.callTokens
}
f.Checksum = f.CalculateChecksum()
return f, di, vm.IsScriptCorrect(buf, methods)
}
func (c *codegen) resolveFuncDecls(f *ast.File, pkg *types.Package) {
for _, decl := range f.Decls {
switch n := decl.(type) {
case *ast.FuncDecl:
fs := c.newFunc(n)
fs.file = f
}
}
}
func (c *codegen) writeJumps(b []byte) ([]byte, error) {
ctx := vm.NewContext(b)
var nopOffsets []int
for op, param, err := ctx.Next(); err == nil && ctx.IP() < len(b); op, param, err = ctx.Next() {
switch op {
case opcode.JMP, opcode.JMPIFNOT, opcode.JMPIF, opcode.CALL,
opcode.JMPEQ, opcode.JMPNE,
opcode.JMPGT, opcode.JMPGE, opcode.JMPLE, opcode.JMPLT:
case opcode.TRYL:
_, err := c.replaceLabelWithOffset(ctx.IP(), param)
if err != nil {
return nil, err
}
_, err = c.replaceLabelWithOffset(ctx.IP(), param[4:])
if err != nil {
return nil, err
}
case opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL,
opcode.JMPEQL, opcode.JMPNEL,
opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLEL, opcode.JMPLTL,
opcode.CALLL, opcode.PUSHA, opcode.ENDTRYL:
offset, err := c.replaceLabelWithOffset(ctx.IP(), param)
if err != nil {
return nil, err
}
if op != opcode.PUSHA && math.MinInt8 <= offset && offset <= math.MaxInt8 {
if op == opcode.JMPL && offset == 5 {
copy(b[ctx.IP():], []byte{byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP)})
nopOffsets = append(nopOffsets, ctx.IP(), ctx.IP()+1, ctx.IP()+2, ctx.IP()+3, ctx.IP()+4)
} else {
copy(b[ctx.IP():], []byte{byte(toShortForm(op)), byte(offset), byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP)})
nopOffsets = append(nopOffsets, ctx.IP()+2, ctx.IP()+3, ctx.IP()+4)
}
}
case opcode.INITSLOT:
nextIP := ctx.NextIP()
info := c.reverseOffsetMap[ctx.IP()]
if argCount := b[nextIP-1]; info.count == 0 && argCount == 0 {
copy(b[ctx.IP():], []byte{byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP)})
nopOffsets = append(nopOffsets, ctx.IP(), ctx.IP()+1, ctx.IP()+2)
continue
}
if info.count > 255 {
return nil, fmt.Errorf("func '%s' has %d local variables (maximum is 255)", info.name, info.count)
}
b[nextIP-2] = byte(info.count)
}
}
if c.deployEndOffset >= 0 {
_, end := correctRange(uint16(c.initEndOffset+1), uint16(c.deployEndOffset), nopOffsets)
c.deployEndOffset = int(end)
}
if c.initEndOffset > 0 {
_, end := correctRange(0, uint16(c.initEndOffset), nopOffsets)
c.initEndOffset = int(end)
}
// Correct function ip range.
// Note: indices are sorted in increasing order.
for _, f := range c.funcs {
f.rng.Start, f.rng.End = correctRange(f.rng.Start, f.rng.End, nopOffsets)
}
return removeNOPs(b, nopOffsets), nil
}
func correctRange(start, end uint16, offsets []int) (uint16, uint16) {
newStart, newEnd := start, end
loop:
for _, ind := range offsets {
switch {
case ind > int(end):
break loop
case ind < int(start):
newStart--
newEnd--
case ind >= int(start):
newEnd--
}
}
return newStart, newEnd
}
func (c *codegen) replaceLabelWithOffset(ip int, arg []byte) (int, error) {
index := binary.LittleEndian.Uint16(arg)
if int(index) > len(c.l) {
return 0, fmt.Errorf("unexpected label number: %d (max %d)", index, len(c.l))
}
if c.l[index] < 0 {
return 0, fmt.Errorf("invalid label target: %d at %d", c.l[index], ip)
}
offset := c.l[index] - ip
if offset > math.MaxInt32 || offset < math.MinInt32 {
return 0, fmt.Errorf("label offset is too big at the instruction %d: %d (max %d, min %d)",
ip, offset, math.MaxInt32, math.MinInt32)
}
binary.LittleEndian.PutUint32(arg, uint32(offset))
return offset, nil
}
// removeNOPs converts b to a program where all long JMP*/CALL* specified by absolute offsets
// are replaced with their corresponding short counterparts. It panics if either b or offsets are invalid.
// This is done in 2 passes:
// 1. Alter jump offsets taking into account parts to be removed.
// 2. Perform actual removal of jump targets.
// Note: after jump offsets altering, there can appear new candidates for conversion.
// These are ignored for now.
func removeNOPs(b []byte, nopOffsets []int) []byte {
if len(nopOffsets) == 0 {
return b
}
for i := range nopOffsets {
if b[nopOffsets[i]] != byte(opcode.NOP) {
panic("NOP offset is invalid")
}
}
// 1. Alter existing jump offsets.
ctx := vm.NewContext(b)
for op, _, err := ctx.Next(); err == nil && ctx.IP() < len(b); op, _, err = ctx.Next() {
// we can't use arg returned by ctx.Next() because it is copied
nextIP := ctx.NextIP()
ip := ctx.IP()
switch op {
case opcode.JMP, opcode.JMPIFNOT, opcode.JMPIF, opcode.CALL,
opcode.JMPEQ, opcode.JMPNE,
opcode.JMPGT, opcode.JMPGE, opcode.JMPLE, opcode.JMPLT, opcode.ENDTRY:
offset := int(int8(b[nextIP-1]))
offset += calcOffsetCorrection(ip, ip+offset, nopOffsets)
b[nextIP-1] = byte(offset)
case opcode.TRY:
catchOffset := int(int8(b[nextIP-2]))
catchOffset += calcOffsetCorrection(ip, ip+catchOffset, nopOffsets)
b[nextIP-1] = byte(catchOffset)
finallyOffset := int(int8(b[nextIP-1]))
finallyOffset += calcOffsetCorrection(ip, ip+finallyOffset, nopOffsets)
b[nextIP-1] = byte(finallyOffset)
case opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL,
opcode.JMPEQL, opcode.JMPNEL,
opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLEL, opcode.JMPLTL,
opcode.CALLL, opcode.PUSHA, opcode.ENDTRYL:
arg := b[nextIP-4:]
offset := int(int32(binary.LittleEndian.Uint32(arg)))
offset += calcOffsetCorrection(ip, ip+offset, nopOffsets)
binary.LittleEndian.PutUint32(arg, uint32(offset))
case opcode.TRYL:
arg := b[nextIP-8:]
catchOffset := int(int32(binary.LittleEndian.Uint32(arg)))
catchOffset += calcOffsetCorrection(ip, ip+catchOffset, nopOffsets)
binary.LittleEndian.PutUint32(arg, uint32(catchOffset))
arg = b[nextIP-4:]
finallyOffset := int(int32(binary.LittleEndian.Uint32(arg)))
finallyOffset += calcOffsetCorrection(ip, ip+finallyOffset, nopOffsets)
binary.LittleEndian.PutUint32(arg, uint32(finallyOffset))
}
}
// 2. Convert instructions.
copyOffset := 0
l := len(nopOffsets)
for i := 0; i < l; i++ {
start := nopOffsets[i]
end := len(b)
if i != l-1 {
end = nopOffsets[i+1]
}
copy(b[start-copyOffset:], b[start+1:end])
copyOffset++
}
return b[:len(b)-copyOffset]
}
func calcOffsetCorrection(ip, target int, offsets []int) int {
cnt := 0
start := sort.Search(len(offsets), func(i int) bool {
return offsets[i] >= ip || offsets[i] >= target
})
for i := start; i < len(offsets) && (offsets[i] < target || offsets[i] <= ip); i++ {
ind := offsets[i]
if ip <= ind && ind < target || target <= ind && ind < ip {
cnt++
}
}
if ip < target {
return -cnt
}
return cnt
}
func negateJmp(op opcode.Opcode) opcode.Opcode {
switch op {
case opcode.JMPIFL:
return opcode.JMPIFNOTL
case opcode.JMPIFNOTL:
return opcode.JMPIFL
case opcode.JMPEQL:
return opcode.JMPNEL
case opcode.JMPNEL:
return opcode.JMPEQL
case opcode.JMPGTL:
return opcode.JMPLEL
case opcode.JMPGEL:
return opcode.JMPLTL
case opcode.JMPLEL:
return opcode.JMPGTL
case opcode.JMPLTL:
return opcode.JMPGEL
default:
panic(fmt.Errorf("invalid opcode in negateJmp: %s", op))
}
}
func toShortForm(op opcode.Opcode) opcode.Opcode {
switch op {
case opcode.JMPL:
return opcode.JMP
case opcode.JMPIFL:
return opcode.JMPIF
case opcode.JMPIFNOTL:
return opcode.JMPIFNOT
case opcode.JMPEQL:
return opcode.JMPEQ
case opcode.JMPNEL:
return opcode.JMPNE
case opcode.JMPGTL:
return opcode.JMPGT
case opcode.JMPGEL:
return opcode.JMPGE
case opcode.JMPLEL:
return opcode.JMPLE
case opcode.JMPLTL:
return opcode.JMPLT
case opcode.CALLL:
return opcode.CALL
case opcode.ENDTRYL:
return opcode.ENDTRY
default:
panic(fmt.Errorf("invalid opcode: %s", op))
}
}
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