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neoneo-go/pkg/compiler/codegen.go
Evgenii Stratonikov cbf26f315c compiler: save both VM and smartcontract types 
VM types are used in debugger, while smartcontract ones are used in
manifest. We can't save only one of them, because conversion in either
side is lossy:
1. VM has `Array` and `Struct` but smartcontract only has `Array`.
2. Smartcontract has `Hash160` etc, which are all `ByteString` or
`Buffer` in VM.

And to spice things a bit more, return type in debugger can be `Void`,
which corresponds to no real stackitem type (as it must exist).
2020-12-09 22:35:22 +03:00

2145 lines
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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/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/loader"
)
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
// A mapping of func identifiers with their scope.
funcs map[string]*funcScope
// A mapping of lambda functions into their scope.
lambda map[string]*funcScope
// Current funcScope being converted.
scope *funcScope
globals map[string]int
// 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
// 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 mapping from 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 current package being processed.
currPkg *types.Package
// mainPkg is a main package metadata.
mainPkg *loader.PackageInfo
// packages contains packages in the order they were loaded.
packages []string
// exceptionIndex is the index of static slot where exception is stored.
exceptionIndex int
// documents contains paths to all files used by the program.
documents []string
// docIndex maps file path to an index in documents array.
docIndex map[string]int
// emittedEvents contains all events emitted by contract.
emittedEvents map[string][][]string
// Label table for recording jump destinations.
l []int
}
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 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 a 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 corresponding slot,
// according to current scope.
func (c *codegen) getVarIndex(pkg string, name string) (varType, int) {
if pkg == "" {
if c.scope != nil {
vt, val := c.scope.vars.getVarIndex(name)
if val >= 0 {
return vt, val
}
}
}
if i, ok := c.globals[c.getIdentName(pkg, name)]; ok {
return varGlobal, i
}
return varLocal, c.scope.newVariable(varLocal, 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 specified variable to the evaluation stack.
func (c *codegen) emitLoadVar(pkg string, name string) {
t, i := c.getVarIndex(pkg, name)
c.emitLoadByIndex(t, i)
}
// emitLoadByIndex loads 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
}
t, i := c.getVarIndex(pkg, name)
c.emitStoreByIndex(t, i)
}
// 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()
emit.Int(c.prog.BinWriter, int64(num))
emit.Opcodes(c.prog.BinWriter, opcode.NEWSTRUCT)
for i := 0; i < num; i++ {
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
emit.Int(c.prog.BinWriter, int64(i))
c.emitDefault(t.Field(i).Type())
emit.Opcodes(c.prog.BinWriter, opcode.SETITEM)
}
default:
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
}
}
// convertGlobals traverses the AST and only converts global declarations.
// If we call this in convertFuncDecl then it will load all global variables
// into the scope of the function.
func (c *codegen) convertGlobals(f *ast.File, _ *types.Package) {
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) clearSlots(n int) {
for i := 0; i < n; i++ {
emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
c.emitStoreByIndex(varLocal, i)
}
}
func (c *codegen) convertInitFuncs(f *ast.File, pkg *types.Package, seenBefore bool) bool {
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.FuncDecl:
if isInitFunc(n) {
if seenBefore {
cnt, _ := countLocals(n)
c.clearSlots(cnt)
seenBefore = true
}
c.convertFuncDecl(f, n, pkg)
}
case *ast.GenDecl:
return false
}
return true
})
return seenBefore
}
func isDeployFunc(decl *ast.FuncDecl) bool {
if decl.Name.Name != "_deploy" || decl.Recv != nil ||
decl.Type.Params.NumFields() != 1 ||
decl.Type.Results.NumFields() != 0 {
return false
}
typ, ok := decl.Type.Params.List[0].Type.(*ast.Ident)
return ok && typ.Name == "bool"
}
func (c *codegen) convertDeployFuncs() {
seenBefore := false
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 seenBefore {
cnt, _ := countLocals(n)
c.clearSlots(cnt)
}
c.convertFuncDecl(f, n, pkg)
seenBefore = true
}
case *ast.GenDecl:
return false
}
return true
})
})
}
func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl, pkg *types.Package) {
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
}
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 {
sizeLoc := f.countLocals()
if sizeLoc > 255 {
c.prog.Err = errors.New("maximum of 255 local variables is allowed")
}
sizeArg := f.countArgs()
if sizeArg > 255 {
c.prog.Err = errors.New("maximum of 255 local variables is allowed")
}
if sizeLoc != 0 || sizeArg != 0 {
emit.Instruction(c.prog.BinWriter, opcode.INITSLOT, []byte{byte(sizeLoc), 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 first argument.
// We check if this declaration has a receiver and load it into 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 {
// only create an argument here, it will be stored via INITSLOT
c.scope.newVariable(varArgument, arg.Names[0].Name)
}
}
// 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) {
c.saveSequencePoint(decl.Body)
emit.Opcodes(c.prog.BinWriter, opcode.RET)
}
f.rng.End = uint16(c.prog.Len() - 1)
if !isLambda {
for _, f := range c.lambda {
c.convertFuncDecl(file, f.decl, pkg)
}
c.lambda = make(map[string]*funcScope)
}
}
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 {
info := c.buildInfo.program.Package(c.currPkg.Path())
obj := info.Defs[vs.Names[i]]
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:
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)
}
c.registerDebugVariable(id.Name, t.Type)
}
}
for i := range t.Names {
if len(t.Values) != 0 {
ast.Walk(c, t.Values[i])
} else {
c.emitDefault(c.typeOf(t.Type))
}
c.emitStoreVar("", t.Names[i].Name)
}
}
}
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 typ == nil {
// 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.(*ast.Ident)).Underlying()) {
c.prog.Err = errors.New("subslices are supported only for []byte")
return nil
}
name := n.X.(*ast.Ident).Name
c.emitLoadVar("", name)
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
for i := range c.labelList {
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)
emit.Opcodes(c.prog.BinWriter, opcode.RET)
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:
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:
switch typ := c.typeOf(n).Underlying().(type) {
case *types.Struct:
c.convertStruct(n, false)
case *types.Map:
c.convertMap(n)
default:
ln := len(n.Elts)
// ByteArrays needs a different approach than normal arrays.
if isByteSlice(typ) {
c.convertByteArray(n)
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.funcs[c.getIdentName("", fun.Name)]
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
}
case *ast.SelectorExpr:
// If this is a method call we need to walk the AST to load the struct locally.
// Otherwise this is a function call from a imported package and we can call it
// directly.
name, isMethod := c.getFuncNameFromSelector(fun)
if isMethod {
ast.Walk(c, fun.X)
// Dont forget to add 1 extra argument when its a method.
numArgs++
}
f, ok = c.funcs[name]
// @FIXME this could cause runtime errors.
f.selector = fun.X.(*ast.Ident)
if !ok {
c.prog.Err = fmt.Errorf("could not resolve function %s", fun.Sel.Name)
return nil
}
isBuiltin = isCustomBuiltin(f)
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.FuncLit:
isLiteral = true
}
c.saveSequencePoint(n)
args := transformArgs(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.PUSH0, opcode.PICKITEM)
}
}
// Do not swap for builtin functions.
if !isBuiltin {
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 := len(n.Args) - typ.Params().Len() + 1
c.emitReverse(varSize)
emit.Int(c.prog.BinWriter, int64(varSize))
emit.Opcodes(c.prog.BinWriter, opcode.PACK)
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 is can be only an invocation of 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):
if f.pkg.Name() == "runtime" && f.name == "Notify" {
tv := c.typeAndValueOf(n.Args[0])
params := make([]string, 0, len(n.Args[1:]))
for _, p := range n.Args[1:] {
st, _ := c.scAndVMTypeFromExpr(p)
params = append(params, st.String())
}
// Sometimes event name is stored in a var.
// Skip in this case.
if tv.Value != nil {
name := constant.StringVal(tv.Value)
c.emittedEvents[name] = append(c.emittedEvents[name], params)
}
}
c.convertSyscall(n, f.pkg.Name(), f.name)
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)
c.scope.deferStack = append(c.scope.deferStack, deferInfo{
catchLabel: catch,
finallyLabel: finally,
expr: n.Call,
})
return nil
case *ast.SelectorExpr:
typ := c.typeOf(n.X)
if typ == nil {
// 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 index from 0 to len-1, storing array, len and index on stack.
// For maps we iterate index 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 dont 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
// not the assertion type.
case *ast.TypeAssertExpr:
ast.Walk(c, n.X)
typ := toNeoType(c.typeOf(n.Type))
emit.Instruction(c.prog.BinWriter, opcode.CONVERT, []byte{byte(typ)})
return nil
}
return c
}
// processDefers emits code for `defer` statements.
// TRY-related opcodes handle exception as follows:
// 1. CATCH block is executed only if exception has occured.
// 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 occured.
// 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 is set to true.
// 2. CATCH and FINALLY blocks are the same, and both contain the same CALLs.
// 3. In CATCH block we set Y to true and emit default return values if it is the last defer.
// 4. 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()
emit.Jmp(c.prog.BinWriter, opcode.ENDTRYL, after)
c.setLabel(stmt.catchLabel)
c.emitStoreByIndex(varGlobal, c.exceptionIndex)
emit.Int(c.prog.BinWriter, 1)
c.emitStoreByIndex(varLocal, c.scope.finallyProcessedIndex)
ast.Walk(c, stmt.expr)
if i == 0 {
// After panic, default values must be returns, except for named returns,
// which we don't support here for now.
for i := len(c.scope.decl.Type.Results.List) - 1; i >= 0; i-- {
c.emitDefault(c.typeOf(c.scope.decl.Type.Results.List[i].Type))
}
}
emit.Jmp(c.prog.BinWriter, opcode.ENDTRYL, after)
c.setLabel(stmt.finallyLabel)
before := c.newLabel()
c.emitLoadByIndex(varLocal, c.scope.finallyProcessedIndex)
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, c.scope.finallyProcessedIndex)
emit.Opcodes(c.prog.BinWriter, opcode.ENDFINALLY)
c.setLabel(after)
}
}
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
}
// getByteArray returns byte array value from constant expr.
// Only literals are supported.
func (c *codegen) getByteArray(expr ast.Expr) []byte {
switch t := expr.(type) {
case *ast.CompositeLit:
if !isByteSlice(c.typeOf(t.Type)) {
return nil
}
buf := make([]byte, len(t.Elts))
for i := 0; i < len(t.Elts); i++ {
t := c.typeAndValueOf(t.Elts[i])
val, _ := constant.Int64Val(t.Value)
buf[i] = byte(val)
}
return buf
case *ast.CallExpr:
if tv := c.typeAndValueOf(t.Args[0]); tv.Value != nil {
val := constant.StringVal(tv.Value)
return []byte(val)
}
return nil
default:
return nil
}
}
func (c *codegen) convertSyscall(expr *ast.CallExpr, api, name string) {
syscall, ok := syscalls[api][name]
if !ok {
c.prog.Err = fmt.Errorf("unknown VM syscall api: %s.%s", api, name)
return
}
emit.Syscall(c.prog.BinWriter, syscall)
// This NOP instruction is basically not needed, but if we do, we have a
// one to one matching avm file with neo-python which is very nice for debugging.
emit.Opcodes(c.prog.BinWriter, opcode.NOP)
}
// 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
c.emitReverse(len(expr.Args))
emit.Opcodes(c.prog.BinWriter, opcode.DUP, opcode.ISNULL)
emit.Instruction(c.prog.BinWriter, opcode.JMPIFNOT, []byte{2 + 3})
if isByteSlice(typ) {
emit.Opcodes(c.prog.BinWriter, opcode.DROP, opcode.PUSH0, opcode.NEWBUFFER)
} else {
emit.Opcodes(c.prog.BinWriter, opcode.DROP, opcode.NEWARRAY0, opcode.NOP)
}
// Jump target.
for range expr.Args[1:] {
if isByteSlice(typ) {
emit.Opcodes(c.prog.BinWriter, opcode.SWAP, opcode.CAT)
} else {
emit.Opcodes(c.prog.BinWriter, opcode.DUP, opcode.ROT, 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 "ToInteger", "ToByteArray", "ToBool":
typ := stackitem.IntegerT
switch name {
case "ToByteArray":
typ = stackitem.ByteArrayT
case "ToBool":
typ = stackitem.BooleanT
}
c.emitConvert(typ)
case "Remove":
if !isCompoundSlice(c.typeOf(expr.Args[0])) {
c.prog.Err = errors.New("`Remove` supports only non-byte slices")
return
}
emit.Opcodes(c.prog.BinWriter, opcode.REMOVE)
case "Equals":
emit.Opcodes(c.prog.BinWriter, opcode.EQUAL)
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, generated code depends on if argument was nil or a string so
// it should be handled accordingly.
func transformArgs(fun ast.Expr, args []ast.Expr) []ast.Expr {
switch f := fun.(type) {
case *ast.SelectorExpr:
if f.Sel.Name == "FromAddress" {
return args[1:]
}
case *ast.Ident:
switch f.Name {
case "make", "copy":
return nil
}
}
return args
}
// emitConvert converts top stack item to the specified type.
func (c *codegen) emitConvert(typ stackitem.Type) {
emit.Instruction(c.prog.BinWriter, opcode.CONVERT, []byte{byte(typ)})
}
func (c *codegen) convertByteArray(lit *ast.CompositeLit) {
buf := make([]byte, len(lit.Elts))
varIndices := []int{}
for i := 0; i < len(lit.Elts); i++ {
t := c.typeAndValueOf(lit.Elts[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, lit.Elts[i])
emit.Opcodes(c.prog.BinWriter, opcode.SETITEM)
}
}
func (c *codegen) convertMap(lit *ast.CompositeLit) {
emit.Opcodes(c.prog.BinWriter, opcode.NEWMAP)
for i := range lit.Elts {
elem := lit.Elts[i].(*ast.KeyValueExpr)
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
ast.Walk(c, elem.Key)
ast.Walk(c, elem.Value)
emit.Opcodes(c.prog.BinWriter, opcode.SETITEM)
}
}
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
}
emit.Opcodes(c.prog.BinWriter, opcode.NOP)
emit.Int(c.prog.BinWriter, int64(strct.NumFields()))
if ptr {
emit.Opcodes(c.prog.BinWriter, opcode.NEWARRAY)
} else {
emit.Opcodes(c.prog.BinWriter, opcode.NEWSTRUCT)
}
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 := 0; i < strct.NumFields(); i++ {
sField := strct.Field(i)
var initialized bool
emit.Opcodes(c.prog.BinWriter, opcode.DUP)
emit.Int(c.prog.BinWriter, int64(i))
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.Opcodes(c.prog.BinWriter, opcode.SETITEM)
}
}
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.LTE, nil
case token.GTR:
return opcode.GT, nil
case token.GEQ:
return opcode.GTE, 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
}
// 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) {
ident := e.X.(*ast.Ident)
if c.typeInfo.Selections[e] != nil {
typ := c.typeInfo.Types[ident].Type.String()
return c.getIdentName(typ, e.Sel.Name), true
}
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 *loader.PackageInfo) error {
c.mainPkg = pkg
c.analyzePkgOrder()
c.fillDocumentInfo()
funUsage := c.analyzeFuncUsage()
// Bring all imported functions into scope.
c.ForEachFile(c.resolveFuncDecls)
n, initLocals, deployLocals := c.traverseGlobals()
hasInit := initLocals > -1
if n > 0 || hasInit {
c.initEndOffset = c.prog.Len()
emit.Opcodes(c.prog.BinWriter, opcode.RET)
}
hasDeploy := deployLocals > -1
if hasDeploy {
emit.Instruction(c.prog.BinWriter, opcode.INITSLOT, []byte{byte(deployLocals), 1})
c.convertDeployFuncs()
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.AllPackages))
for p := range info.program.AllPackages {
keys = append(keys, p)
}
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.
name := c.getFuncNameFromDecl(pkg.Path(), n)
if !isInitFunc(n) && !isDeployFunc(n) && funUsage.funcUsed(name) && !isInteropPath(pkg.Path()) {
c.convertFuncDecl(f, n, pkg)
}
}
}
})
return c.prog.Err
}
func newCodegen(info *buildInfo, pkg *loader.PackageInfo) *codegen {
return &codegen{
buildInfo: info,
prog: io.NewBufBinWriter(),
l: []int{},
funcs: map[string]*funcScope{},
lambda: map[string]*funcScope{},
globals: map[string]int{},
labels: map[labelWithType]uint16{},
typeInfo: &pkg.Info,
constMap: map[string]types.TypeAndValue{},
docIndex: map[string]int{},
initEndOffset: -1,
deployEndOffset: -1,
emittedEvents: make(map[string][][]string),
sequencePoints: make(map[string][]DebugSeqPoint),
}
}
// CodeGen compiles the program to bytecode.
func CodeGen(info *buildInfo) ([]byte, *DebugInfo, error) {
pkg := info.program.Package(info.initialPackage)
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
}
return buf, c.emitDebugInfo(buf), nil
}
func (c *codegen) resolveFuncDecls(f *ast.File, pkg *types.Package) {
for _, decl := range f.Decls {
switch n := decl.(type) {
case *ast.FuncDecl:
c.newFunc(n)
}
}
}
func (c *codegen) writeJumps(b []byte) ([]byte, error) {
ctx := vm.NewContext(b)
var offsets []int
for op, _, err := ctx.Next(); err == nil && ctx.IP() < len(b); op, _, 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:
nextIP := ctx.NextIP()
catchArg := b[nextIP-8:]
_, err := c.replaceLabelWithOffset(ctx.IP(), catchArg)
if err != nil {
return nil, err
}
finallyArg := b[nextIP-4:]
_, err = c.replaceLabelWithOffset(ctx.IP(), finallyArg)
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:
// we can't use arg returned by ctx.Next() because it is copied
nextIP := ctx.NextIP()
arg := b[nextIP-4:]
offset, err := c.replaceLabelWithOffset(ctx.IP(), arg)
if err != nil {
return nil, err
}
if op != opcode.PUSHA && math.MinInt8 <= offset && offset <= math.MaxInt8 {
offsets = append(offsets, ctx.IP())
}
}
}
// Correct function ip range.
// Note: indices are sorted in increasing order.
for _, f := range c.funcs {
start, end := f.rng.Start, f.rng.End
loop:
for _, ind := range offsets {
switch {
case ind > int(f.rng.End):
break loop
case ind < int(f.rng.Start):
start -= longToShortRemoveCount
end -= longToShortRemoveCount
case ind >= int(f.rng.Start):
end -= longToShortRemoveCount
}
}
f.rng.Start = start
f.rng.End = end
}
return shortenJumps(b, offsets), nil
}
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))
}
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
}
// longToShortRemoveCount is a difference between short and long instruction sizes in bytes.
const longToShortRemoveCount = 3
// shortenJumps returns 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 shortenJumps(b []byte, offsets []int) []byte {
if len(offsets) == 0 {
return b
}
// 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, offsets)
b[nextIP-1] = byte(offset)
case opcode.TRY:
catchOffset := int(int8(b[nextIP-2]))
catchOffset += calcOffsetCorrection(ip, ip+catchOffset, offsets)
b[nextIP-1] = byte(catchOffset)
finallyOffset := int(int8(b[nextIP-1]))
finallyOffset += calcOffsetCorrection(ip, ip+finallyOffset, offsets)
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, offsets)
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, offsets)
binary.LittleEndian.PutUint32(arg, uint32(catchOffset))
arg = b[nextIP-4:]
finallyOffset := int(int32(binary.LittleEndian.Uint32(arg)))
finallyOffset += calcOffsetCorrection(ip, ip+finallyOffset, offsets)
binary.LittleEndian.PutUint32(arg, uint32(finallyOffset))
}
}
// 2. Convert instructions.
copyOffset := 0
l := len(offsets)
b[offsets[0]] = byte(toShortForm(opcode.Opcode(b[offsets[0]])))
for i := 0; i < l; i++ {
start := offsets[i] + 2
end := len(b)
if i != l-1 {
end = offsets[i+1] + 2
b[offsets[i+1]] = byte(toShortForm(opcode.Opcode(b[offsets[i+1]])))
}
copy(b[start-copyOffset:], b[start+3:end])
copyOffset += longToShortRemoveCount
}
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 ||
ind != ip && target <= ind && ind <= ip {
cnt += longToShortRemoveCount
}
}
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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