neo-go/pkg/compiler/analysis.go

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package compiler
import (
"errors"
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"fmt"
"go/ast"
"go/constant"
"go/types"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
"golang.org/x/tools/go/loader"
)
var (
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// Go language builtin functions and custom builtin utility functions.
builtinFuncs = []string{
"len", "append", "SHA256",
"AppCall",
"FromAddress", "Equals",
"panic",
"ToBool", "ToByteArray", "ToInteger",
}
)
// typeAndValueForField returns a zero initialized typeAndValue for the given type.Var.
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func typeAndValueForField(fld *types.Var) (types.TypeAndValue, error) {
switch t := fld.Type().(type) {
case *types.Basic:
switch t.Kind() {
case types.Int:
return types.TypeAndValue{
Type: t,
Value: constant.MakeInt64(0),
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}, nil
case types.String:
return types.TypeAndValue{
Type: t,
Value: constant.MakeString(""),
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}, nil
case types.Bool, types.UntypedBool:
return types.TypeAndValue{
Type: t,
Value: constant.MakeBool(false),
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}, nil
default:
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return types.TypeAndValue{}, fmt.Errorf("could not initialize struct field %s to zero, type: %s", fld.Name(), t)
}
}
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return types.TypeAndValue{}, nil
}
// newGlobal creates new global variable.
func (c *codegen) newGlobal(name string) {
c.globals[name] = len(c.globals)
}
// traverseGlobals visits and initializes global variables.
func (c *codegen) traverseGlobals(f ast.Node) {
n := countGlobals(f)
if n != 0 {
if n > 255 {
c.prog.BinWriter.Err = errors.New("too many global variables")
return
}
emit.Instruction(c.prog.BinWriter, opcode.INITSSLOT, []byte{byte(n)})
}
c.convertGlobals(f)
}
// countGlobals counts the global variables in the program to add
// them with the stack size of the function.
func countGlobals(f ast.Node) (i int) {
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
// Skip all function declarations.
case *ast.FuncDecl:
return false
// After skipping all funcDecls we are sure that each value spec
// is a global declared variable or constant.
case *ast.ValueSpec:
i += len(n.Names)
}
return true
})
return
}
// 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"
}
// resolveEntryPoint returns the function declaration of the entrypoint and the corresponding file.
func resolveEntryPoint(entry string, pkg *loader.PackageInfo) (*ast.FuncDecl, *ast.File) {
var (
main *ast.FuncDecl
file *ast.File
)
for _, f := range pkg.Files {
ast.Inspect(f, func(n ast.Node) bool {
switch t := n.(type) {
case *ast.FuncDecl:
if t.Name.Name == entry {
main = t
file = f
return false
}
}
return true
})
}
return main, file
}
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// 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 last statement of the declaration was return statement..
func lastStmtIsReturn(decl *ast.FuncDecl) (b bool) {
if l := len(decl.Body.List); l != 0 {
_, ok := decl.Body.List[l-1].(*ast.ReturnStmt)
return ok
}
return false
}
func analyzeFuncUsage(pkgs map[*types.Package]*loader.PackageInfo) funcUsage {
usage := funcUsage{}
for _, pkg := range pkgs {
for _, f := range pkg.Files {
ast.Inspect(f, func(node ast.Node) bool {
switch n := node.(type) {
case *ast.CallExpr:
switch t := n.Fun.(type) {
case *ast.Ident:
usage[t.Name] = true
case *ast.SelectorExpr:
usage[t.Sel.Name] = true
}
}
return true
})
}
}
return usage
}
func isBuiltin(expr ast.Expr) bool {
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var name string
switch t := expr.(type) {
case *ast.Ident:
name = t.Name
case *ast.SelectorExpr:
name = t.Sel.Name
default:
return false
}
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for _, n := range builtinFuncs {
if name == n {
return true
}
}
return false
}
func isSyscall(fun *funcScope) bool {
if fun.selector == nil {
return false
}
_, ok := syscalls[fun.selector.Name][fun.name]
return ok
}