package compiler import ( "errors" "fmt" "go/ast" "go/token" "go/types" "strings" "github.com/nspcc-dev/neo-go/pkg/vm/emit" "github.com/nspcc-dev/neo-go/pkg/vm/opcode" "golang.org/x/tools/go/packages" ) // Various exported functions usage errors. var ( // ErrMissingExportedParamName is returned when exported contract method has unnamed parameter. ErrMissingExportedParamName = errors.New("exported method is not allowed to have unnamed parameter") // ErrInvalidExportedRetCount is returned when exported contract method has invalid return values count. ErrInvalidExportedRetCount = errors.New("exported method is not allowed to have more than one return value") ) var ( // Go language builtin functions. goBuiltins = []string{"len", "append", "panic", "make", "copy", "recover", "delete"} // Custom builtin utility functions that contain some meaningful code inside and // require code generation using standard rules, but sometimes (depending on // the expression usage condition) may be optimized at compile time. potentialCustomBuiltins = map[string]func(f ast.Expr) bool{ "ToHash160": func(f ast.Expr) bool { c, ok := f.(*ast.CallExpr) if !ok { return false } if len(c.Args) != 1 { return false } switch c.Args[0].(type) { case *ast.BasicLit: return true default: return false } }, } ) // newGlobal creates a new global variable. func (c *codegen) newGlobal(pkg string, name string) { name = c.getIdentName(pkg, name) c.globals[name] = len(c.globals) } // getIdentName returns a fully-qualified name for a variable. func (c *codegen) getIdentName(pkg string, name string) string { if fullName, ok := c.importMap[pkg]; ok { pkg = fullName } return pkg + "." + name } // traverseGlobals visits and initializes global variables. // It returns `true` if contract has `_deploy` function. func (c *codegen) traverseGlobals() bool { var hasDefer bool var n, nConst int var hasUnusedCall bool var hasDeploy bool c.ForEachFile(func(f *ast.File, pkg *types.Package) { nv, nc, huc := countGlobals(f, !hasUnusedCall) n += nv nConst += nc if huc { hasUnusedCall = true } if !hasDeploy || !hasDefer { ast.Inspect(f, func(node ast.Node) bool { switch n := node.(type) { case *ast.FuncDecl: hasDeploy = hasDeploy || isDeployFunc(n) case *ast.DeferStmt: hasDefer = true return false } return true }) } }) if hasDefer { n++ } if n > 255 { c.prog.BinWriter.Err = errors.New("too many global variables") return hasDeploy } if n != 0 { emit.Instruction(c.prog.BinWriter, opcode.INITSSLOT, []byte{byte(n)}) } initOffset := c.prog.Len() emit.Instruction(c.prog.BinWriter, opcode.INITSLOT, []byte{0, 0}) lastCnt, maxCnt := -1, -1 c.ForEachPackage(func(pkg *packages.Package) { if n+nConst > 0 || hasUnusedCall { for _, f := range pkg.Syntax { c.fillImportMap(f, pkg) c.convertGlobals(f) } } for _, f := range pkg.Syntax { c.fillImportMap(f, pkg) var currMax int lastCnt, currMax = c.convertInitFuncs(f, pkg.Types, lastCnt) if currMax > maxCnt { maxCnt = currMax } } // because we reuse `convertFuncDecl` for init funcs, // we need to clear scope, so that global variables // encountered after will be recognized as globals. c.scope = nil }) if c.globalInlineCount > maxCnt { maxCnt = c.globalInlineCount } // Here we remove `INITSLOT` if no code was emitted for `init` function. // Note that the `INITSSLOT` must stay in place. hasNoInit := initOffset+3 == c.prog.Len() if hasNoInit { buf := c.prog.Bytes() c.prog.Reset() c.prog.WriteBytes(buf[:initOffset]) } if initOffset != 0 || !hasNoInit { // if there are some globals or `init()`. c.initEndOffset = c.prog.Len() emit.Opcodes(c.prog.BinWriter, opcode.RET) if maxCnt >= 0 { c.reverseOffsetMap[initOffset] = nameWithLocals{ name: "init", count: maxCnt, } } } // store auxiliary variables after all others. if hasDefer { c.exceptionIndex = len(c.globals) c.globals[exceptionVarName] = c.exceptionIndex } return hasDeploy } // countGlobals counts the global variables in the program to add // them with the stack size of the function. // Second returned argument contains the amount of global constants. // If checkUnusedCalls set to true then unnamed global variables containing call // will be searched for and their presence is returned as the last argument. func countGlobals(f ast.Node, checkUnusedCalls bool) (int, int, bool) { var numVar, numConst int var hasUnusedCall bool ast.Inspect(f, func(node ast.Node) bool { switch n := node.(type) { // Skip all function declarations if we have already encountered `defer`. case *ast.FuncDecl: return false // After skipping all funcDecls, we are sure that each value spec // is a globally declared variable or constant. case *ast.GenDecl: isVar := n.Tok == token.VAR if isVar || n.Tok == token.CONST { for _, s := range n.Specs { valueSpec := s.(*ast.ValueSpec) multiRet := len(valueSpec.Values) != 0 && len(valueSpec.Names) != len(valueSpec.Values) // e.g. var A, B = f() where func f() (int, int) for j, id := range valueSpec.Names { if id.Name != "_" { // If variable has name, then it's treated as used - that's countGlobals' caller responsibility to guarantee that. if isVar { numVar++ } else { numConst++ } } else if isVar && len(valueSpec.Values) != 0 && checkUnusedCalls && !hasUnusedCall { indexToCheck := j if multiRet { indexToCheck = 0 } hasUnusedCall = containsCall(valueSpec.Values[indexToCheck]) } } } } return false } return true }) return numVar, numConst, hasUnusedCall } // containsCall traverses node and looks if it contains a function or method call. func containsCall(n ast.Node) bool { var hasCall bool ast.Inspect(n, func(node ast.Node) bool { switch node.(type) { case *ast.CallExpr: hasCall = true case *ast.Ident: // Can safely skip idents immediately, we're interested at function calls only. return false } return !hasCall }) return hasCall } // isExprNil looks if the given expression is a `nil`. func isExprNil(e ast.Expr) bool { v, ok := e.(*ast.Ident) return ok && v.Name == "nil" } // indexOfStruct returns the index of the given field inside that struct. // If the struct does not contain that field, it will return -1. func indexOfStruct(strct *types.Struct, fldName string) int { for i := 0; i < strct.NumFields(); i++ { if strct.Field(i).Name() == fldName { return i } } return -1 } type funcUsage map[string]bool func (f funcUsage) funcUsed(name string) bool { _, ok := f[name] return ok } // lastStmtIsReturn checks if the last statement of the declaration was return statement. func lastStmtIsReturn(body *ast.BlockStmt) (b bool) { if l := len(body.List); l != 0 { switch inner := body.List[l-1].(type) { case *ast.BlockStmt: return lastStmtIsReturn(inner) case *ast.ReturnStmt: return true default: return false } } return false } // analyzePkgOrder sets the order in which packages should be processed. // From Go spec: // // A package with no imports is initialized by assigning initial values to all its package-level variables // followed by calling all init functions in the order they appear in the source, possibly in multiple files, // as presented to the compiler. If a package has imports, the imported packages are initialized before // initializing the package itself. If multiple packages import a package, the imported package // will be initialized only once. The importing of packages, by construction, guarantees // that there can be no cyclic initialization dependencies. func (c *codegen) analyzePkgOrder() { seen := make(map[string]bool) info := c.buildInfo.program[0] c.visitPkg(info, seen) } func (c *codegen) visitPkg(pkg *packages.Package, seen map[string]bool) { if seen[pkg.PkgPath] { return } for _, imp := range pkg.Types.Imports() { c.visitPkg(pkg.Imports[imp.Path()], seen) } seen[pkg.PkgPath] = true c.packages = append(c.packages, pkg.PkgPath) c.packageCache[pkg.PkgPath] = pkg } func (c *codegen) fillDocumentInfo() { fset := c.buildInfo.config.Fset fset.Iterate(func(f *token.File) bool { filePath := f.Position(f.Pos(0)).Filename c.docIndex[filePath] = len(c.documents) c.documents = append(c.documents, filePath) return true }) } // analyzeFuncAndGlobalVarUsage traverses all code and returns a map with functions // which should be present in the emitted code. // This is done using BFS starting from exported functions or // the function used in variable declarations (graph edge corresponds to // the function being called in declaration). It also analyzes global variables // usage preserving the same traversal strategy and rules. Unused global variables // are renamed to "_" in the end. Global variable is treated as "used" iff: // 1. It belongs either to main or to exported package AND is used directly from the exported (or _init\_deploy) method of the main package. // 2. It belongs either to main or to exported package AND is used non-directly from the exported (or _init\_deploy) method of the main package // (e.g. via series of function calls or in some expression that is "used"). // 3. It belongs either to main or to exported package AND contains function call inside its value definition. func (c *codegen) analyzeFuncAndGlobalVarUsage() funcUsage { type declPair struct { decl *ast.FuncDecl importMap map[string]string path string } // globalVar represents a global variable declaration node with the corresponding package context. type globalVar struct { decl *ast.GenDecl // decl contains global variables declaration node (there can be multiple declarations in a single node). specIdx int // specIdx is the index of variable specification in the list of GenDecl specifications. varIdx int // varIdx is the index of variable name in the specification names. ident *ast.Ident // ident is a named global variable identifier got from the specified node. importMap map[string]string path string } // nodeCache contains top-level function declarations. nodeCache := make(map[string]declPair) // globalVarsCache contains both used and unused declared named global vars. globalVarsCache := make(map[string]globalVar) // diff contains used functions that are not yet marked as "used" and those definition // requires traversal in the subsequent stages. diff := funcUsage{} // globalVarsDiff contains used named global variables that are not yet marked as "used" // and those declaration requires traversal in the subsequent stages. globalVarsDiff := funcUsage{} // usedExpressions contains a set of ast.Nodes that are used in the program and need to be evaluated // (either they are used from the used functions OR belong to global variable declaration and surrounded by a function call) var usedExpressions []nodeContext c.ForEachFile(func(f *ast.File, pkg *types.Package) { var pkgPath string isMain := pkg == c.mainPkg.Types if !isMain { pkgPath = pkg.Path() } ast.Inspect(f, func(node ast.Node) bool { switch n := node.(type) { case *ast.CallExpr: // functions invoked in variable declarations in imported packages // are marked as used. var name string switch t := n.Fun.(type) { case *ast.Ident: name = c.getIdentName(pkgPath, t.Name) case *ast.SelectorExpr: name, _ = c.getFuncNameFromSelector(t) default: return true } diff[name] = true case *ast.FuncDecl: name := c.getFuncNameFromDecl(pkgPath, n) // exported functions and methods are always assumed to be used if isMain && n.Name.IsExported() || isInitFunc(n) || isDeployFunc(n) { diff[name] = true } // exported functions are not allowed to have unnamed parameters or multiple return values if isMain && n.Name.IsExported() && n.Recv == nil { if n.Type.Params.List != nil { for i, param := range n.Type.Params.List { if param.Names == nil { c.prog.Err = fmt.Errorf("%w: %s", ErrMissingExportedParamName, n.Name) return false // Program is invalid. } for _, name := range param.Names { if name == nil || name.Name == "_" { c.prog.Err = fmt.Errorf("%w: %s/%d", ErrMissingExportedParamName, n.Name, i) return false // Program is invalid. } } } } if retCnt := n.Type.Results.NumFields(); retCnt > 1 { c.prog.Err = fmt.Errorf("%w: %s/%d return values", ErrInvalidExportedRetCount, n.Name, retCnt) } } nodeCache[name] = declPair{n, c.importMap, pkgPath} return false // will be processed in the next stage case *ast.GenDecl: // After skipping all funcDecls, we are sure that each value spec // is a globally declared variable or constant. We need to gather global // vars from both main and imported packages. if n.Tok == token.VAR { for i, s := range n.Specs { valSpec := s.(*ast.ValueSpec) for j, id := range valSpec.Names { if id.Name != "_" { name := c.getIdentName(pkgPath, id.Name) globalVarsCache[name] = globalVar{ decl: n, specIdx: i, varIdx: j, ident: id, importMap: c.importMap, path: pkgPath, } } // Traverse both named/unnamed global variables, check whether function/method call // is present inside variable value and if so, mark all its children as "used" for // further traversal and evaluation. if len(valSpec.Values) == 0 { continue } multiRet := len(valSpec.Values) != len(valSpec.Names) if (j == 0 || !multiRet) && containsCall(valSpec.Values[j]) { usedExpressions = append(usedExpressions, nodeContext{ node: valSpec.Values[j], path: pkgPath, importMap: c.importMap, typeInfo: c.typeInfo, currPkg: c.currPkg, }) } } } } } return true }) }) if c.prog.Err != nil { return nil } // Handle nodes that contain (or surrounded by) function calls and are a part // of global variable declaration. c.pickVarsFromNodes(usedExpressions, func(name string) { if _, gOK := globalVarsCache[name]; gOK { globalVarsDiff[name] = true } }) // Traverse the set of upper-layered used functions and construct the functions' usage map. // At the same time, go through the whole set of used functions and mark global vars used // from these functions as "used". Also mark the global variables from the previous step // and their children as "used". usage := funcUsage{} globalVarsUsage := funcUsage{} for len(diff) != 0 || len(globalVarsDiff) != 0 { nextDiff := funcUsage{} nextGlobalVarsDiff := funcUsage{} usedExpressions = usedExpressions[:0] for name := range diff { fd, ok := nodeCache[name] if !ok || usage[name] { continue } usage[name] = true pkg := c.mainPkg if fd.path != "" { pkg = c.packageCache[fd.path] } c.typeInfo = pkg.TypesInfo c.currPkg = pkg c.importMap = fd.importMap ast.Inspect(fd.decl, func(node ast.Node) bool { switch n := node.(type) { case *ast.CallExpr: switch t := n.Fun.(type) { case *ast.Ident: nextDiff[c.getIdentName(fd.path, t.Name)] = true case *ast.SelectorExpr: name, _ := c.getFuncNameFromSelector(t) nextDiff[name] = true } } return true }) usedExpressions = append(usedExpressions, nodeContext{ node: fd.decl.Body, path: fd.path, importMap: c.importMap, typeInfo: c.typeInfo, currPkg: c.currPkg, }) } // Traverse used global vars in a separate cycle so that we're sure there's no other unrelated vars. // Mark their children as "used". for name := range globalVarsDiff { fd, ok := globalVarsCache[name] if !ok || globalVarsUsage[name] { continue } globalVarsUsage[name] = true pkg := c.mainPkg if fd.path != "" { pkg = c.packageCache[fd.path] } valSpec := fd.decl.Specs[fd.specIdx].(*ast.ValueSpec) if len(valSpec.Values) == 0 { continue } multiRet := len(valSpec.Values) != len(valSpec.Names) if fd.varIdx == 0 || !multiRet { usedExpressions = append(usedExpressions, nodeContext{ node: valSpec.Values[fd.varIdx], path: fd.path, importMap: fd.importMap, typeInfo: pkg.TypesInfo, currPkg: pkg, }) } } c.pickVarsFromNodes(usedExpressions, func(name string) { if _, gOK := globalVarsCache[name]; gOK { nextGlobalVarsDiff[name] = true } }) diff = nextDiff globalVarsDiff = nextGlobalVarsDiff } // Tiny hack: rename all remaining unused global vars. After that these unused // vars will be handled as any other unnamed unused variables, i.e. // c.traverseGlobals() won't take them into account during static slot creation // and the code won't be emitted for them. for name, node := range globalVarsCache { if _, ok := globalVarsUsage[name]; !ok { node.ident.Name = "_" } } return usage } // nodeContext contains ast node with the corresponding import map, type info and package information // required to retrieve fully qualified node name (if so). type nodeContext struct { node ast.Node path string importMap map[string]string typeInfo *types.Info currPkg *packages.Package } // derive returns provided node with the parent's context. func (c nodeContext) derive(n ast.Node) nodeContext { return nodeContext{ node: n, path: c.path, importMap: c.importMap, typeInfo: c.typeInfo, currPkg: c.currPkg, } } // pickVarsFromNodes searches for variables used in the given set of nodes // calling markAsUsed for each variable. Be careful while using codegen after // pickVarsFromNodes, it changes importMap, currPkg and typeInfo. func (c *codegen) pickVarsFromNodes(nodes []nodeContext, markAsUsed func(name string)) { for len(nodes) != 0 { var nextExprToCheck []nodeContext for _, val := range nodes { // Set variable context for proper name extraction. c.importMap = val.importMap c.currPkg = val.currPkg c.typeInfo = val.typeInfo ast.Inspect(val.node, func(node ast.Node) bool { switch n := node.(type) { case *ast.KeyValueExpr: // var _ = f() + CustomInt{Int: Unused}.Int + 3 => mark Unused as "used". nextExprToCheck = append(nextExprToCheck, val.derive(n.Value)) return false case *ast.CallExpr: switch t := n.Fun.(type) { case *ast.Ident: // Do nothing, used functions are handled in a separate cycle. case *ast.SelectorExpr: nextExprToCheck = append(nextExprToCheck, val.derive(t)) } for _, arg := range n.Args { switch arg.(type) { case *ast.BasicLit: default: nextExprToCheck = append(nextExprToCheck, val.derive(arg)) } } return false case *ast.SelectorExpr: if c.typeInfo.Selections[n] != nil { switch t := n.X.(type) { case *ast.Ident: nextExprToCheck = append(nextExprToCheck, val.derive(t)) case *ast.CompositeLit: nextExprToCheck = append(nextExprToCheck, val.derive(t)) case *ast.SelectorExpr: // imp_pkg.Anna.GetAge() => mark Anna (exported global struct) as used. nextExprToCheck = append(nextExprToCheck, val.derive(t)) } } else { ident := n.X.(*ast.Ident) name := c.getIdentName(ident.Name, n.Sel.Name) markAsUsed(name) } return false case *ast.CompositeLit: // var _ = f(1) + []int{1, Unused, 3}[1] => mark Unused as "used". for _, e := range n.Elts { switch e.(type) { case *ast.BasicLit: default: nextExprToCheck = append(nextExprToCheck, val.derive(e)) } } return false case *ast.Ident: name := c.getIdentName(val.path, n.Name) markAsUsed(name) return false case *ast.DeferStmt: nextExprToCheck = append(nextExprToCheck, val.derive(n.Call.Fun)) return false case *ast.BasicLit: return false } return true }) } nodes = nextExprToCheck } } func isGoBuiltin(name string) bool { for i := range goBuiltins { if name == goBuiltins[i] { return true } } return false } func isPotentialCustomBuiltin(f *funcScope, expr ast.Expr) bool { if !isInteropPath(f.pkg.Path()) { return false } for name, isBuiltin := range potentialCustomBuiltins { if f.name == name && isBuiltin(expr) { return true } } return false } func isSyscall(fun *funcScope) bool { if fun.selector == nil || fun.pkg == nil || !isInteropPath(fun.pkg.Path()) { return false } return fun.pkg.Name() == "neogointernal" && (strings.HasPrefix(fun.name, "Syscall") || strings.HasPrefix(fun.name, "Opcode") || strings.HasPrefix(fun.name, "CallWithToken")) } const interopPrefix = "github.com/nspcc-dev/neo-go/pkg/interop" func isInteropPath(s string) bool { return strings.HasPrefix(s, interopPrefix) } // canConvert returns true if type doesn't need to be converted on type assertion. func canConvert(s string) bool { if len(s) != 0 && s[0] == '*' { s = s[1:] } if isInteropPath(s) { s = s[len(interopPrefix):] return s != "/iterator.Iterator" && s != "/storage.Context" && s != "/native/ledger.Block" && s != "/native/ledger.Transaction" && s != "/native/management.Contract" && s != "/native/neo.AccountState" && s != "/native/ledger.BlockSR" } return true } // canInline returns true if the function is to be inlined. // The list of functions that can be inlined is not static, it depends on the function usages. // isBuiltin denotes whether code generation for dynamic builtin function will be performed // manually. func canInline(s string, name string, isBuiltin bool) bool { if strings.HasPrefix(s, "github.com/nspcc-dev/neo-go/pkg/compiler/testdata/inline") { return true } if !isInteropPath(s) { return false } return !strings.HasPrefix(s[len(interopPrefix):], "/neogointernal") && !(strings.HasPrefix(s[len(interopPrefix):], "/util") && name == "FromAddress") && !(strings.HasPrefix(s[len(interopPrefix):], "/lib/address") && name == "ToHash160" && isBuiltin) }