neoneo-go/pkg/compiler/codegen.go
Anna Shaleva a1f98f92fe compiler: add ConvertResultToStruct flag
Part of #1055.

There'll be a lot of interops which result with a struct on stack instead
of interop interface, and sometimes their names are the same, so it's
unrelyable to take into account interop name only and don't pay
attention to it's API (package).

Also sort syscalls by package and name.
2020-07-17 08:19:43 +03:00

1552 lines
40 KiB
Go

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"
)
// The identifier of the entry function. Default set to Main.
const mainIdent = "Main"
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
// 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.Opcode(c.prog.BinWriter, opcode.PICKITEM)
}
func (c *codegen) emitStoreStructField(i int) {
emit.Int(c.prog.BinWriter, int64(i))
emit.Opcode(c.prog.BinWriter, opcode.ROT)
emit.Opcode(c.prog.BinWriter, opcode.SETITEM)
}
// getVarIndex returns variable type and position in corresponding slot,
// according to current scope.
func (c *codegen) getVarIndex(name string) (varType, int) {
if c.scope != nil {
vt, val := c.scope.vars.getVarIndex(name)
if val >= 0 {
return vt, val
}
}
if i, ok := c.globals[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(name string) {
t, i := c.getVarIndex(name)
base, _ := getBaseOpcode(t)
if i < 7 {
emit.Opcode(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(name string) {
if name == "_" {
emit.Opcode(c.prog.BinWriter, opcode.DROP)
return
}
t, i := c.getVarIndex(name)
_, base := getBaseOpcode(t)
if i < 7 {
emit.Opcode(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.Opcode(c.prog.BinWriter, opcode.PUSHNULL)
}
case *types.Struct:
num := t.NumFields()
emit.Int(c.prog.BinWriter, int64(num))
emit.Opcode(c.prog.BinWriter, opcode.NEWSTRUCT)
for i := 0; i < num; i++ {
emit.Opcode(c.prog.BinWriter, opcode.DUP)
emit.Int(c.prog.BinWriter, int64(i))
c.emitDefault(t.Field(i).Type())
emit.Opcode(c.prog.BinWriter, opcode.SETITEM)
}
default:
emit.Opcode(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.Node) {
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.FuncDecl:
return false
case *ast.GenDecl:
// constants are loaded directly so there is no need
// to store them as a local variables
if n.Tok != token.CONST {
ast.Walk(c, n)
}
}
return true
})
}
func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl, pkg *types.Package) {
var (
f *funcScope
ok, isLambda bool
)
f, ok = c.funcs[decl.Name.Name]
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[decl.Name.Name]; ok {
isLambda = ok
c.setLabel(f.label)
} else {
f = c.newFunc(decl)
f.pkg = pkg
}
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.
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 !lastStmtIsReturn(decl) {
c.saveSequencePoint(decl.Body)
emit.Opcode(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:
for _, spec := range n.Specs {
switch t := spec.(type) {
case *ast.ValueSpec:
for _, id := range t.Names {
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.convertToken(n.Tok)
}
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])
}
strct, ok := c.typeOf(t.X).Underlying().(*types.Struct)
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.Opcode(c.prog.BinWriter, opcode.ROT)
emit.Opcode(c.prog.BinWriter, opcode.SETITEM)
}
}
return nil
case *ast.SliceExpr:
name := n.X.(*ast.Ident).Name
c.emitLoadVar(name)
if n.Low != nil {
ast.Walk(c, n.Low)
} else {
emit.Opcode(c.prog.BinWriter, opcode.PUSH0)
}
if n.High != nil {
ast.Walk(c, n.High)
} else {
emit.Opcode(c.prog.BinWriter, opcode.OVER)
emit.Opcode(c.prog.BinWriter, opcode.SIZE)
}
emit.Opcode(c.prog.BinWriter, opcode.OVER)
emit.Opcode(c.prog.BinWriter, opcode.SUB)
emit.Opcode(c.prog.BinWriter, 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.saveSequencePoint(n)
emit.Opcode(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.Cond != nil {
ast.Walk(c, n.Cond)
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOTL, 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:
ast.Walk(c, n.Tag)
eqOpcode := c.getEqualityOpcode(n.Tag)
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.Opcode(c.prog.BinWriter, opcode.DUP)
ast.Walk(c, cc.List[j])
emit.Opcode(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.Ident:
if tv := c.typeAndValueOf(n); tv.Value != nil {
c.emitLoadConst(tv)
} else if n.Name == "nil" {
emit.Opcode(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)
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.Opcode(c.prog.BinWriter, opcode.PACK)
}
return nil
case *ast.BinaryExpr:
switch n.Op {
case token.LAND:
next := c.newLabel()
end := c.newLabel()
ast.Walk(c, n.X)
emit.Jmp(c.prog.BinWriter, opcode.JMPIFL, next)
emit.Opcode(c.prog.BinWriter, opcode.PUSHF)
emit.Jmp(c.prog.BinWriter, opcode.JMPL, end)
c.setLabel(next)
ast.Walk(c, n.Y)
c.setLabel(end)
return nil
case token.LOR:
next := c.newLabel()
end := c.newLabel()
ast.Walk(c, n.X)
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOTL, next)
emit.Opcode(c.prog.BinWriter, opcode.PUSHT)
emit.Jmp(c.prog.BinWriter, opcode.JMPL, end)
c.setLabel(next)
ast.Walk(c, n.Y)
c.setLabel(end)
return nil
default:
// 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)
return nil
}
var checkForNull bool
if isExprNil(n.X) {
checkForNull = true
} else {
ast.Walk(c, n.X)
}
if isExprNil(n.Y) {
checkForNull = true
} else {
ast.Walk(c, n.Y)
}
if checkForNull {
emit.Opcode(c.prog.BinWriter, opcode.ISNULL)
if n.Op == token.NEQ {
emit.Opcode(c.prog.BinWriter, opcode.NOT)
}
return nil
}
switch {
case n.Op == token.ADD:
// VM has separate opcodes for number and string concatenation
if isString(tinfo.Type) {
emit.Opcode(c.prog.BinWriter, opcode.CAT)
} else {
emit.Opcode(c.prog.BinWriter, opcode.ADD)
}
case n.Op == token.EQL:
// VM has separate opcodes for number and string equality
op := c.getEqualityOpcode(n.X)
emit.Opcode(c.prog.BinWriter, op)
case n.Op == token.NEQ:
// VM has separate opcodes for number and string equality
if isString(c.typeOf(n.X)) {
emit.Opcode(c.prog.BinWriter, opcode.NOTEQUAL)
} else {
emit.Opcode(c.prog.BinWriter, opcode.NUMNOTEQUAL)
}
default:
c.convertToken(n.Op)
}
return nil
}
case *ast.CallExpr:
var (
f *funcScope
ok bool
name string
numArgs = len(n.Args)
isBuiltin bool
isFunc bool
)
switch fun := n.Fun.(type) {
case *ast.Ident:
f, ok = c.funcs[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.
if c.typeInfo.Selections[fun] != nil {
ast.Walk(c, fun.X)
// Dont forget to add 1 extra argument when its a method.
numArgs++
}
f, ok = c.funcs[fun.Sel.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
}
c.saveSequencePoint(n)
args := transformArgs(n.Fun, n.Args)
// Handle the arguments
for _, arg := range args {
ast.Walk(c, arg)
}
// 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.Opcode(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.Opcode(c.prog.BinWriter, opcode.CALLA)
}
case isSyscall(f):
c.convertSyscall(n, f.selector.Name, f.name)
default:
emit.Call(c.prog.BinWriter, opcode.CALLL, f.label)
}
return nil
case *ast.SelectorExpr:
strct, ok := c.typeOf(n.X).Underlying().(*types.Struct)
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:
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.Opcode(c.prog.BinWriter, opcode.NEGATE)
case token.NOT:
emit.Opcode(c.prog.BinWriter, opcode.NOT)
case token.XOR:
emit.Opcode(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.convertToken(n.Tok)
// 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.Opcode(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.Opcode(c.prog.BinWriter, opcode.DUP)
if isMap {
emit.Opcode(c.prog.BinWriter, opcode.KEYS)
emit.Opcode(c.prog.BinWriter, opcode.DUP)
}
emit.Opcode(c.prog.BinWriter, opcode.SIZE)
emit.Opcode(c.prog.BinWriter, 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.Opcode(c.prog.BinWriter, opcode.OVER)
emit.Opcode(c.prog.BinWriter, 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.Opcode(c.prog.BinWriter, opcode.DUP)
keyLoaded = true
}
} else {
emit.Opcode(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.Opcode(c.prog.BinWriter, opcode.PICK) // load map itself (+1 because key was pushed)
emit.Opcode(c.prog.BinWriter, opcode.SWAP) // key should be on top
emit.Opcode(c.prog.BinWriter, opcode.PICKITEM)
}
c.emitStoreVar(n.Value.(*ast.Ident).Name)
}
ast.Walk(c, n.Body)
c.setLabel(post)
emit.Opcode(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
}
func (c *codegen) rangeLoadKey() {
emit.Int(c.prog.BinWriter, 2)
emit.Opcode(c.prog.BinWriter, opcode.PICK) // load keys
emit.Opcode(c.prog.BinWriter, opcode.OVER) // load index in key array
emit.Opcode(c.prog.BinWriter, opcode.PICKITEM)
}
func isFallthroughStmt(c ast.Node) bool {
s, ok := c.(*ast.BranchStmt)
return ok && s.Tok == token.FALLTHROUGH
}
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.Opcode(c.prog.BinWriter, opcode.DROP)
}
return
}
emit.Int(c.prog.BinWriter, int64(n))
emit.Opcode(c.prog.BinWriter, opcode.PACK)
emit.Opcode(c.prog.BinWriter, opcode.DROP)
}
// emitReverse reverses top num items of the stack.
func (c *codegen) emitReverse(num int) {
switch num {
case 0, 1:
case 2:
emit.Opcode(c.prog.BinWriter, opcode.SWAP)
case 3:
emit.Opcode(c.prog.BinWriter, opcode.REVERSE3)
case 4:
emit.Opcode(c.prog.BinWriter, opcode.REVERSE4)
default:
emit.Int(c.prog.BinWriter, int64(num))
emit.Opcode(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}]
}
func (c *codegen) getEqualityOpcode(expr ast.Expr) opcode.Opcode {
t, ok := c.typeOf(expr).Underlying().(*types.Basic)
if ok && t.Info()&types.IsNumeric != 0 {
return opcode.NUMEQUAL
}
return opcode.EQUAL
}
// 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.API)
if syscall.ConvertResultToStruct {
c.emitConvert(stackitem.StructT)
}
// 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.Opcode(c.prog.BinWriter, opcode.NOP)
}
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 "len":
emit.Opcode(c.prog.BinWriter, opcode.DUP)
emit.Opcode(c.prog.BinWriter, opcode.ISNULL)
emit.Instruction(c.prog.BinWriter, opcode.JMPIF, []byte{2 + 1 + 2})
emit.Opcode(c.prog.BinWriter, opcode.SIZE)
emit.Instruction(c.prog.BinWriter, opcode.JMP, []byte{2 + 1 + 1})
emit.Opcode(c.prog.BinWriter, opcode.DROP)
emit.Opcode(c.prog.BinWriter, opcode.PUSH0)
case "append":
arg := expr.Args[0]
typ := c.typeInfo.Types[arg].Type
c.emitReverse(len(expr.Args))
emit.Opcode(c.prog.BinWriter, opcode.DUP)
emit.Opcode(c.prog.BinWriter, opcode.ISNULL)
emit.Instruction(c.prog.BinWriter, opcode.JMPIFNOT, []byte{2 + 3})
if isByteSlice(typ) {
emit.Opcode(c.prog.BinWriter, opcode.DROP)
emit.Opcode(c.prog.BinWriter, opcode.PUSH0)
emit.Opcode(c.prog.BinWriter, opcode.NEWBUFFER)
} else {
emit.Opcode(c.prog.BinWriter, opcode.DROP)
emit.Opcode(c.prog.BinWriter, opcode.NEWARRAY0)
emit.Opcode(c.prog.BinWriter, opcode.NOP)
}
// Jump target.
for range expr.Args[1:] {
if isByteSlice(typ) {
emit.Opcode(c.prog.BinWriter, opcode.SWAP)
emit.Opcode(c.prog.BinWriter, opcode.CAT)
} else {
emit.Opcode(c.prog.BinWriter, opcode.DUP)
emit.Opcode(c.prog.BinWriter, opcode.ROT)
emit.Opcode(c.prog.BinWriter, opcode.APPEND)
}
}
case "panic":
arg := expr.Args[0]
if isExprNil(arg) {
emit.Opcode(c.prog.BinWriter, opcode.DROP)
emit.Opcode(c.prog.BinWriter, opcode.THROW)
} else if isString(c.typeInfo.Types[arg].Type) {
ast.Walk(c, arg)
emit.Syscall(c.prog.BinWriter, "System.Runtime.Log")
emit.Opcode(c.prog.BinWriter, opcode.THROW)
} else {
c.prog.Err = errors.New("panic should have string or nil argument")
}
case "ToInteger", "ToByteArray", "ToBool":
typ := stackitem.IntegerT
switch name {
case "ToByteArray":
typ = stackitem.ByteArrayT
case "ToBool":
typ = stackitem.BooleanT
}
c.emitConvert(typ)
case "SHA256":
emit.Syscall(c.prog.BinWriter, "Neo.Crypto.SHA256")
case "AppCall":
c.emitReverse(len(expr.Args))
buf := c.getByteArray(expr.Args[0])
if buf != nil && len(buf) != 20 {
c.prog.Err = errors.New("invalid script hash")
}
emit.Syscall(c.prog.BinWriter, "System.Contract.Call")
case "Equals":
emit.Opcode(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:
if f.Name == "panic" {
return args[1:]
}
}
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))
for i := 0; i < len(lit.Elts); i++ {
t := c.typeAndValueOf(lit.Elts[i])
val, _ := constant.Int64Val(t.Value)
buf[i] = byte(val)
}
emit.Bytes(c.prog.BinWriter, buf)
c.emitConvert(stackitem.BufferT)
}
func (c *codegen) convertMap(lit *ast.CompositeLit) {
emit.Opcode(c.prog.BinWriter, opcode.NEWMAP)
for i := range lit.Elts {
elem := lit.Elts[i].(*ast.KeyValueExpr)
emit.Opcode(c.prog.BinWriter, opcode.DUP)
ast.Walk(c, elem.Key)
ast.Walk(c, elem.Value)
emit.Opcode(c.prog.BinWriter, opcode.SETITEM)
}
}
func (c *codegen) convertStruct(lit *ast.CompositeLit) {
// 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.Opcode(c.prog.BinWriter, opcode.NOP)
emit.Int(c.prog.BinWriter, int64(strct.NumFields()))
emit.Opcode(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.Opcode(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.Opcode(c.prog.BinWriter, opcode.SETITEM)
}
}
func (c *codegen) convertToken(tok token.Token) {
switch tok {
case token.ADD_ASSIGN:
emit.Opcode(c.prog.BinWriter, opcode.ADD)
case token.SUB_ASSIGN:
emit.Opcode(c.prog.BinWriter, opcode.SUB)
case token.MUL_ASSIGN:
emit.Opcode(c.prog.BinWriter, opcode.MUL)
case token.QUO_ASSIGN:
emit.Opcode(c.prog.BinWriter, opcode.DIV)
case token.REM_ASSIGN:
emit.Opcode(c.prog.BinWriter, opcode.MOD)
case token.ADD:
emit.Opcode(c.prog.BinWriter, opcode.ADD)
case token.SUB:
emit.Opcode(c.prog.BinWriter, opcode.SUB)
case token.MUL:
emit.Opcode(c.prog.BinWriter, opcode.MUL)
case token.QUO:
emit.Opcode(c.prog.BinWriter, opcode.DIV)
case token.REM:
emit.Opcode(c.prog.BinWriter, opcode.MOD)
case token.LSS:
emit.Opcode(c.prog.BinWriter, opcode.LT)
case token.LEQ:
emit.Opcode(c.prog.BinWriter, opcode.LTE)
case token.GTR:
emit.Opcode(c.prog.BinWriter, opcode.GT)
case token.GEQ:
emit.Opcode(c.prog.BinWriter, opcode.GTE)
case token.EQL:
emit.Opcode(c.prog.BinWriter, opcode.NUMEQUAL)
case token.NEQ:
emit.Opcode(c.prog.BinWriter, opcode.NUMNOTEQUAL)
case token.DEC:
emit.Opcode(c.prog.BinWriter, opcode.DEC)
case token.INC:
emit.Opcode(c.prog.BinWriter, opcode.INC)
case token.NOT:
emit.Opcode(c.prog.BinWriter, opcode.NOT)
case token.AND:
emit.Opcode(c.prog.BinWriter, opcode.AND)
case token.OR:
emit.Opcode(c.prog.BinWriter, opcode.OR)
case token.SHL:
emit.Opcode(c.prog.BinWriter, opcode.SHL)
case token.SHR:
emit.Opcode(c.prog.BinWriter, opcode.SHR)
case token.XOR:
emit.Opcode(c.prog.BinWriter, opcode.XOR)
default:
c.prog.Err = fmt.Errorf("compiler could not convert token: %s", tok)
return
}
}
func (c *codegen) newFunc(decl *ast.FuncDecl) *funcScope {
f := newFuncScope(decl, c.newLabel())
c.funcs[f.name] = f
return f
}
func (c *codegen) newLambda(u uint16, lit *ast.FuncLit) {
name := fmt.Sprintf("lambda@%d", u)
c.lambda[name] = newFuncScope(&ast.FuncDecl{
Name: ast.NewIdent(name),
Type: lit.Type,
Body: lit.Body,
}, u)
}
func (c *codegen) compile(info *buildInfo, pkg *loader.PackageInfo) error {
// Resolve the entrypoint of the program.
main, mainFile := resolveEntryPoint(mainIdent, pkg)
if main == nil {
c.prog.Err = fmt.Errorf("could not find func main. Did you forget to declare it? ")
return c.prog.Err
}
funUsage := analyzeFuncUsage(info.program.AllPackages)
// Bring all imported functions into scope.
for _, pkg := range info.program.AllPackages {
for _, f := range pkg.Files {
c.resolveFuncDecls(f, pkg.Pkg)
}
}
c.traverseGlobals(mainFile)
// convert the entry point first.
c.convertFuncDecl(mainFile, main, pkg.Pkg)
// 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.
for _, k := range keys {
pkg := info.program.AllPackages[k]
c.typeInfo = &pkg.Info
for _, f := range pkg.Files {
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.
if n.Name.Name != mainIdent && funUsage.funcUsed(n.Name.Name) {
c.convertFuncDecl(f, n, k)
}
}
}
}
}
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,
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 := c.prog.Bytes()
if err := c.writeJumps(buf); 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:
if n.Name.Name != mainIdent {
c.newFunc(n)
c.funcs[n.Name.Name].pkg = pkg
}
}
}
}
func (c *codegen) writeJumps(b []byte) error {
ctx := vm.NewContext(b)
for op, _, err := ctx.Next(); err == nil && ctx.NextIP() < 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:
// Noop, assumed to be correct already. If you're fixing #905,
// make sure not to break "len" and "append" handling above.
case opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL,
opcode.JMPEQL, opcode.JMPNEL,
opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLEL, opcode.JMPLTL,
opcode.CALLL, opcode.PUSHA:
// we can't use arg returned by ctx.Next() because it is copied
nextIP := ctx.NextIP()
arg := b[nextIP-4:]
index := binary.LittleEndian.Uint16(arg)
if int(index) > len(c.l) {
return fmt.Errorf("unexpected label number: %d (max %d)", index, len(c.l))
}
var offset int
if op == opcode.PUSHA {
offset = c.l[index]
} else {
offset = c.l[index] - nextIP + 5
}
if offset > math.MaxInt32 || offset < math.MinInt32 {
return fmt.Errorf("label offset is too big at the instruction %d: %d (max %d, min %d)",
nextIP-5, offset, math.MaxInt32, math.MinInt32)
}
binary.LittleEndian.PutUint32(arg, uint32(offset))
}
}
return nil
}