package compiler import ( "encoding/binary" "errors" "fmt" "go/ast" "go/constant" "go/token" "go/types" "math" "sort" "strconv" "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" "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 // Current funcScope being converted. scope *funcScope // 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 } // 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 } switch typ := t.Type.Underlying().(type) { case *types.Basic: c.convertBasicType(t, typ) default: c.prog.Err = fmt.Errorf("compiler doesn't know how to convert this constant: %v", t) return } } func (c *codegen) convertBasicType(t types.TypeAndValue, typ *types.Basic) { switch typ.Kind() { case types.Int, types.UntypedInt, types.Uint: 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) case types.Byte: val, _ := constant.Int64Val(t.Value) b := byte(val) emit.Bytes(c.prog.BinWriter, []byte{b}) default: c.prog.Err = fmt.Errorf("compiler doesn't know how to convert this basic type: %v", t) return } } func (c *codegen) emitLoadLocal(name string) { pos := c.scope.loadLocal(name) if pos < 0 { c.prog.Err = fmt.Errorf("cannot load local variable with position: %d", pos) return } c.emitLoadLocalPos(pos) } func (c *codegen) emitLoadLocalPos(pos int) { emit.Opcode(c.prog.BinWriter, opcode.DUPFROMALTSTACK) emit.Int(c.prog.BinWriter, int64(pos)) emit.Opcode(c.prog.BinWriter, opcode.PICKITEM) } func (c *codegen) emitStoreLocal(pos int) { emit.Opcode(c.prog.BinWriter, opcode.DUPFROMALTSTACK) if pos < 0 { c.prog.Err = fmt.Errorf("invalid position to store local: %d", pos) return } emit.Int(c.prog.BinWriter, int64(pos)) emit.Opcode(c.prog.BinWriter, opcode.ROT) emit.Opcode(c.prog.BinWriter, opcode.SETITEM) } 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) } // 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) { var ( f *funcScope ok bool ) f, ok = c.funcs[decl.Name.Name] if ok { // If this function is a syscall we will not convert it to bytecode. if isSyscall(f) { return } 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. emit.Int(c.prog.BinWriter, f.stackSize()+countGlobals(file)) emit.Opcode(c.prog.BinWriter, opcode.NEWARRAY) emit.Opcode(c.prog.BinWriter, opcode.TOALTSTACK) // 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 { ident := arg.Names[0] // Currently only method receives for struct types is supported. _, ok := c.typeInfo.Defs[ident].Type().Underlying().(*types.Struct) if !ok { c.prog.Err = fmt.Errorf("method receives for non-struct types is not yet supported") return } l := c.scope.newLocal(ident.Name) c.emitStoreLocal(l) } } // Load the arguments in scope. for _, arg := range decl.Type.Params.List { for _, id := range arg.Names { l := c.scope.newLocal(id.Name) c.emitStoreLocal(l) } } // Load in all the global variables in to the scope of the function. // This is not necessary for syscalls. if !isSyscall(f) { c.convertGlobals(file) } 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.FROMALTSTACK) emit.Opcode(c.prog.BinWriter, opcode.DROP) emit.Opcode(c.prog.BinWriter, opcode.RET) } f.rng.End = uint16(c.prog.Len() - 1) } 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 { c.scope.newLocal(id.Name) c.registerDebugVariable(id.Name, t.Type) } if len(t.Values) != 0 { for i, val := range t.Values { ast.Walk(c, val) l := c.scope.loadLocal(t.Names[i].Name) c.emitStoreLocal(l) } } else if c.isCompoundArrayType(t.Type) { emit.Opcode(c.prog.BinWriter, opcode.PUSH0) emit.Opcode(c.prog.BinWriter, opcode.NEWARRAY) l := c.scope.loadLocal(t.Names[0].Name) c.emitStoreLocal(l) } else if n, ok := c.isStructType(t.Type); ok { emit.Int(c.prog.BinWriter, int64(n)) emit.Opcode(c.prog.BinWriter, opcode.NEWSTRUCT) l := c.scope.loadLocal(t.Names[0].Name) c.emitStoreLocal(l) } } } 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 && !multiRet { c.registerDebugVariable(t.Name, n.Rhs[i]) } if !isAssignOp && (i == 0 || !multiRet) { ast.Walk(c, n.Rhs[i]) } if t.Name == "_" { emit.Opcode(c.prog.BinWriter, opcode.DROP) } else { l := c.scope.loadLocal(t.Name) c.emitStoreLocal(l) } case *ast.SelectorExpr: switch expr := t.X.(type) { case *ast.Ident: if !isAssignOp { ast.Walk(c, n.Rhs[i]) } typ := c.typeInfo.ObjectOf(expr).Type().Underlying() if strct, ok := typ.(*types.Struct); ok { c.emitLoadLocal(expr.Name) // load the struct i := indexOfStruct(strct, t.Sel.Name) // get the index of the field c.emitStoreStructField(i) // store the field } default: c.prog.Err = fmt.Errorf("nested selector assigns not supported yet") return nil } // Assignments to index expressions. // slice[0] = 10 case *ast.IndexExpr: if !isAssignOp { ast.Walk(c, n.Rhs[i]) } name := t.X.(*ast.Ident).Name c.emitLoadLocal(name) switch ind := t.Index.(type) { case *ast.BasicLit: indexStr := ind.Value index, err := strconv.Atoi(indexStr) if err != nil { c.prog.Err = fmt.Errorf("failed to convert slice index to integer") return nil } c.emitStoreStructField(index) case *ast.Ident: c.emitLoadLocal(ind.Name) emit.Opcode(c.prog.BinWriter, opcode.ROT) emit.Opcode(c.prog.BinWriter, opcode.SETITEM) default: c.prog.Err = fmt.Errorf("unsupported index expression") return nil } } } return nil case *ast.SliceExpr: name := n.X.(*ast.Ident).Name c.emitLoadLocal(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.ARRAYSIZE) } 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.emitLoadLocal(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.FROMALTSTACK) emit.Opcode(c.prog.BinWriter, opcode.DROP) // Cleanup the stack. emit.Opcode(c.prog.BinWriter, opcode.RET) return nil case *ast.IfStmt: lIf := c.newLabel() lElse := c.newLabel() lElseEnd := c.newLabel() if n.Cond != nil { ast.Walk(c, n.Cond) emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, lElse) } c.setLabel(lIf) ast.Walk(c, n.Body) if n.Else != nil { emit.Jmp(c.prog.BinWriter, opcode.JMP, 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.JMPIFNOT, lEnd) } else { emit.Jmp(c.prog.BinWriter, opcode.JMPIF, lStart) } } } 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.JMP, startLabels[i+1]) break } ast.Walk(c, stmt) } emit.Jmp(c.prog.BinWriter, opcode.JMP, switchEnd) c.setLabel(lEnd) } c.setLabel(switchEnd) c.dropStackLabel() c.currentSwitch = lastSwitch return nil case *ast.BasicLit: c.emitLoadConst(c.typeInfo.Types[n]) return nil case *ast.Ident: if isIdentBool(n) { value, err := makeBoolFromIdent(n, c.typeInfo) if err != nil { c.prog.Err = err return nil } c.emitLoadConst(value) } else if tv := c.typeInfo.Types[n]; tv.Value != nil { c.emitLoadConst(tv) } else { c.emitLoadLocal(n.Name) } return nil case *ast.CompositeLit: var typ types.Type switch t := n.Type.(type) { case *ast.Ident: typ = c.typeInfo.ObjectOf(t).Type().Underlying() case *ast.SelectorExpr: typ = c.typeInfo.ObjectOf(t.Sel).Type().Underlying() case *ast.MapType: typ = c.typeInfo.TypeOf(t) default: ln := len(n.Elts) // ByteArrays needs a different approach than normal arrays. if isByteArray(n, c.typeInfo) { 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 } switch typ.(type) { case *types.Struct: c.convertStruct(n) case *types.Map: c.convertMap(n) } 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.JMPIF, next) emit.Opcode(c.prog.BinWriter, opcode.PUSHF) emit.Jmp(c.prog.BinWriter, opcode.JMP, 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.JMPIFNOT, next) emit.Opcode(c.prog.BinWriter, opcode.PUSHT) emit.Jmp(c.prog.BinWriter, opcode.JMP, 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.typeInfo.Types[n] if tinfo.Value != nil { c.emitLoadConst(tinfo) return nil } ast.Walk(c, n.X) ast.Walk(c, n.Y) switch { case n.Op == token.ADD: // VM has separate opcodes for number and string concatenation if isStringType(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 isStringType(c.typeInfo.Types[n.X].Type) { emit.Opcode(c.prog.BinWriter, opcode.EQUAL) emit.Opcode(c.prog.BinWriter, opcode.NOT) } else { emit.Opcode(c.prog.BinWriter, opcode.NUMNOTEQUAL) } default: c.convertToken(n.Op) } return nil } case *ast.CallExpr: var ( f *funcScope ok bool numArgs = len(n.Args) isBuiltin = isBuiltin(n.Fun) ) switch fun := n.Fun.(type) { case *ast.Ident: f, ok = c.funcs[fun.Name] if !ok && !isBuiltin { c.prog.Err = fmt.Errorf("could not resolve function %s", fun.Name) return nil } 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 } 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]) 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 { 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 isSyscall(f): c.convertSyscall(n, f.selector.Name, f.name) default: emit.Call(c.prog.BinWriter, opcode.CALL, f.label) } return nil case *ast.SelectorExpr: switch t := n.X.(type) { case *ast.Ident: typ := c.typeInfo.ObjectOf(t).Type().Underlying() if strct, ok := typ.(*types.Struct); ok { c.emitLoadLocal(t.Name) // load the struct i := indexOfStruct(strct, n.Sel.Name) c.emitLoadField(i) // load the field } default: c.prog.Err = fmt.Errorf("nested selectors not supported yet") return nil } 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 { pos := c.scope.loadLocal(ident.Name) c.emitStoreLocal(pos) } 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) switch n.Index.(type) { case *ast.BasicLit: t := c.typeInfo.Types[n.Index] switch typ := t.Type.Underlying().(type) { case *types.Basic: c.convertBasicType(t, typ) default: c.prog.Err = fmt.Errorf("compiler can't use following type as an index: %T", typ) return nil } default: 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.JMP, end) case token.CONTINUE: post := c.getLabelOffset(labelPost, label) emit.Jmp(c.prog.BinWriter, opcode.JMP, post) } return nil case *ast.LabeledStmt: c.nextLabel = n.Label.Name ast.Walk(c, n.Stmt) return nil case *ast.ForStmt: 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.JMPIFNOT, 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.JMP, fstart) c.setLabel(fend) c.dropStackLabel() c.currentFor = lastLabel c.currentSwitch = lastSwitch return nil case *ast.RangeStmt: // currently only simple for-range loops are supported // for i := range ... if n.Value != nil { c.prog.Err = errors.New("range loops with value variable are not supported") return nil } 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) emit.Opcode(c.prog.BinWriter, opcode.ARRAYSIZE) emit.Opcode(c.prog.BinWriter, opcode.PUSH0) c.pushStackLabel(label, 2) c.setLabel(start) emit.Opcode(c.prog.BinWriter, opcode.OVER) emit.Opcode(c.prog.BinWriter, opcode.OVER) emit.Opcode(c.prog.BinWriter, opcode.LTE) // finish if len <= i emit.Jmp(c.prog.BinWriter, opcode.JMPIF, end) if n.Key != nil { emit.Opcode(c.prog.BinWriter, opcode.DUP) pos := c.scope.loadLocal(n.Key.(*ast.Ident).Name) c.emitStoreLocal(pos) } ast.Walk(c, n.Body) c.setLabel(post) emit.Opcode(c.prog.BinWriter, opcode.INC) emit.Jmp(c.prog.BinWriter, opcode.JMP, 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) return nil } return c } 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 2: emit.Opcode(c.prog.BinWriter, opcode.SWAP) case 3: emit.Int(c.prog.BinWriter, 2) emit.Opcode(c.prog.BinWriter, opcode.XSWAP) default: for i := 1; i < num; i++ { emit.Int(c.prog.BinWriter, int64(i)) emit.Opcode(c.prog.BinWriter, opcode.ROLL) } } } // 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.typeInfo.Types[expr].Type.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 !isByteArray(t, c.typeInfo) { return nil } buf := make([]byte, len(t.Elts)) for i := 0; i < len(t.Elts); i++ { t := c.typeInfo.Types[t.Elts[i]] val, _ := constant.Int64Val(t.Value) buf[i] = byte(val) } return buf case *ast.CallExpr: if tv := c.typeInfo.Types[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) { api, ok := syscalls[api][name] if !ok { c.prog.Err = fmt.Errorf("unknown VM syscall api: %s", name) return } switch name { case "Notify": numArgs := len(expr.Args) emit.Int(c.prog.BinWriter, int64(numArgs)) emit.Opcode(c.prog.BinWriter, opcode.PACK) } emit.Syscall(c.prog.BinWriter, api) // 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": arg := expr.Args[0] typ := c.typeInfo.Types[arg].Type if isStringType(typ) { emit.Opcode(c.prog.BinWriter, opcode.SIZE) } else { emit.Opcode(c.prog.BinWriter, opcode.ARRAYSIZE) } case "append": arg := expr.Args[0] typ := c.typeInfo.Types[arg].Type if isByteArrayType(typ) { emit.Opcode(c.prog.BinWriter, opcode.CAT) } else { emit.Opcode(c.prog.BinWriter, opcode.OVER) emit.Opcode(c.prog.BinWriter, opcode.SWAP) 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 isStringType(c.typeInfo.Types[arg].Type) { ast.Walk(c, arg) emit.Syscall(c.prog.BinWriter, "Neo.Runtime.Log") emit.Opcode(c.prog.BinWriter, opcode.THROW) } else { c.prog.Err = errors.New("panic should have string or nil argument") } case "delete", "Remove": arg := expr.Args[0] errNotSupported := errors.New("only maps and non-byte slices are supported in `Remove`") switch typ := c.typeInfo.Types[arg].Type.Underlying().(type) { case *types.Map: case *types.Slice: if isByte(typ.Elem()) { c.prog.Err = errNotSupported } default: c.prog.Err = errNotSupported } emit.Opcode(c.prog.BinWriter, opcode.REMOVE) case "SHA256": emit.Opcode(c.prog.BinWriter, opcode.SHA256) case "SHA1": emit.Opcode(c.prog.BinWriter, opcode.SHA1) case "Hash256": emit.Opcode(c.prog.BinWriter, opcode.HASH256) case "Hash160": emit.Opcode(c.prog.BinWriter, opcode.HASH160) case "VerifySignature": emit.Opcode(c.prog.BinWriter, opcode.VERIFY) case "AppCall", "DynAppCall": numArgs := len(expr.Args) if name == "AppCall" { numArgs-- } c.emitReverse(numArgs) emit.Opcode(c.prog.BinWriter, opcode.APPCALL) var buf []byte if name == "AppCall" { buf = c.getByteArray(expr.Args[0]) if len(buf) != 20 { c.prog.Err = errors.New("invalid script hash") } } else { // Zeroes for DynAppCall. buf = make([]byte, 20) } c.prog.WriteBytes(buf) 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) } } // transformArgs returns a list of function arguments // which should be put on stack. // There are special cases for builtins: // 1. When using AppCall, script hash is a part of the instruction so // it should be emitted after APPCALL. // 2. With FromAddress, parameter conversion is happening at compile-time // so there is no need to push parameters on stack and perform an actual call // 3. 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 == "AppCall" || f.Sel.Name == "FromAddress" { return args[1:] } case *ast.Ident: if f.Name == "panic" { return args[1:] } } return args } func (c *codegen) convertByteArray(lit *ast.CompositeLit) { buf := make([]byte, len(lit.Elts)) for i := 0; i < len(lit.Elts); i++ { t := c.typeInfo.Types[lit.Elts[i]] val, _ := constant.Int64Val(t.Value) buf[i] = byte(val) } emit.Bytes(c.prog.BinWriter, buf) } 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.typeInfo.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) // 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) fieldAdded := false // Fields initialized by the program. for _, field := range lit.Elts { f := field.(*ast.KeyValueExpr) fieldName := f.Key.(*ast.Ident).Name if sField.Name() == fieldName { emit.Opcode(c.prog.BinWriter, opcode.DUP) pos := indexOfStruct(strct, fieldName) emit.Int(c.prog.BinWriter, int64(pos)) ast.Walk(c, f.Value) emit.Opcode(c.prog.BinWriter, opcode.SETITEM) fieldAdded = true break } } if fieldAdded { continue } typeAndVal, err := typeAndValueForField(sField) if err != nil { c.prog.Err = err return } emit.Opcode(c.prog.BinWriter, opcode.DUP) emit.Int(c.prog.BinWriter, int64(i)) c.emitLoadConst(typeAndVal) 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) 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) } } // convert the entry point first. c.convertFuncDecl(mainFile, main) // 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) } } } } } 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{}, 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(), nil } func (c *codegen) resolveFuncDecls(f *ast.File) { for _, decl := range f.Decls { switch n := decl.(type) { case *ast.FuncDecl: if n.Name.Name != mainIdent { c.newFunc(n) } } } } 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: // we can't use arg returned by ctx.Next() because it is copied nextIP := ctx.NextIP() arg := b[nextIP-2:] index := binary.LittleEndian.Uint16(arg) if int(index) > len(c.l) { return fmt.Errorf("unexpected label number: %d (max %d)", index, len(c.l)) } offset := c.l[index] - nextIP + 3 if offset > math.MaxUint16 { return fmt.Errorf("label offset is too big at the instruction %d: %d (max %d)", nextIP-3, offset, math.MaxUint16) } binary.LittleEndian.PutUint16(arg, uint16(offset)) } } return nil }