Golang ast.SwitchStmt类代码示例

func (v *visitor) wrapSwitch(_switch *ast.SwitchStmt, identList []*ast.Ident) (block *ast.BlockStmt) {
	block = astPrintf(`
		{
			godebug.Line(ctx, %s, %s)
			%s
			scope := %s.EnteringNewChildScope()
			_ = scope // placeholder
			_ = scope // placeholder
		}`, v.scopeVar, pos2lineString(_switch.Pos()), _switch.Init, v.scopeVar)[0].(*ast.BlockStmt)
	block.List[3] = newDeclareCall(idents.scope, identList)
	_switch.Init = nil
	block.List[4] = _switch
	return block
}

func (s *Sonar) Visit(n ast.Node) ast.Visitor {
	// TODO: detect "x&mask==0", emit sonar(x, x&^mask)
	switch nn := n.(type) {
	case *ast.BinaryExpr:
		break

	case *ast.GenDecl:
		if nn.Tok != token.VAR {
			return nil // constants and types are not interesting
		}
		return s

	case *ast.SelectorExpr:
		return nil

	case *ast.SwitchStmt:
		if nn.Tag == nil || nn.Body == nil {
			return s // recurse
		}
		// Replace:
		//	switch a := foo(); bar(a) {
		//	case x: ...
		//	case y: ...
		//	}
		// with:
		//	switch {
		//	default:
		//		a := foo()
		//		__tmp := bar(a)
		//		switch {
		//		case __tmp == x: ...
		//		case __tmp == y: ...
		//		}
		//	}
		// The == comparisons will be instrumented later when we recurse.
		sw := new(ast.SwitchStmt)
		*sw = *nn
		var stmts []ast.Stmt
		if sw.Init != nil {
			stmts = append(stmts, sw.Init)
			sw.Init = nil
		}
		const tmpvar = "__go_fuzz_tmp"
		tmp := &ast.Ident{Name: tmpvar}
		typ := s.info.Types[sw.Tag]
		s.info.Types[tmp] = typ
		stmts = append(stmts, &ast.AssignStmt{Lhs: []ast.Expr{tmp}, Tok: token.DEFINE, Rhs: []ast.Expr{sw.Tag}})
		stmts = append(stmts, &ast.AssignStmt{Lhs: []ast.Expr{&ast.Ident{Name: "_"}}, Tok: token.ASSIGN, Rhs: []ast.Expr{tmp}})
		sw.Tag = nil
		stmts = append(stmts, sw)
		for _, cas1 := range sw.Body.List {
			cas := cas1.(*ast.CaseClause)
			for i, expr := range cas.List {
				tmp := &ast.Ident{Name: tmpvar, NamePos: expr.Pos()}
				s.info.Types[tmp] = typ
				cas.List[i] = &ast.BinaryExpr{X: tmp, Op: token.EQL, Y: expr}
			}
		}
		nn.Tag = nil
		nn.Init = nil
		nn.Body = &ast.BlockStmt{List: []ast.Stmt{&ast.CaseClause{Body: stmts}}}
		return s // recurse

	case *ast.ForStmt:
		// For condition is usually uninteresting, but produces lots of samples.
		// So we skip it if it looks boring.
		if nn.Init != nil {
			ast.Walk(s, nn.Init)
		}
		if nn.Post != nil {
			ast.Walk(s, nn.Post)
		}
		ast.Walk(s, nn.Body)
		if nn.Cond != nil {
			// Look for the following pattern:
			//	for foo := ...; foo ? ...; ... { ... }
			boring := false
			if nn.Init != nil {
				if init, ok1 := nn.Init.(*ast.AssignStmt); ok1 && init.Tok == token.DEFINE && len(init.Lhs) == 1 {
					if id, ok2 := init.Lhs[0].(*ast.Ident); ok2 {
						if bex, ok3 := nn.Cond.(*ast.BinaryExpr); ok3 {
							if x, ok4 := bex.X.(*ast.Ident); ok4 && x.Name == id.Name {
								boring = true
							}
							if x, ok4 := bex.Y.(*ast.Ident); ok4 && x.Name == id.Name {
								boring = true
							}
						}
					}
				}
			}
			if !boring {
				ast.Walk(s, nn.Cond)
			}
		}
		return nil

	default:
		return s // recurse
	}
//.........这里部分代码省略.........

func (a *stmtCompiler) compileSwitchStmt(s *ast.SwitchStmt) {
	// Create implicit scope around switch
	bc := a.enterChild()
	defer bc.exit()

	// Compile init statement, if any
	if s.Init != nil {
		bc.compileStmt(s.Init)
	}

	// Compile condition, if any, and extract its effects
	var cond *expr
	condbc := bc.enterChild()
	if s.Tag != nil {
		e := condbc.compileExpr(condbc.block, false, s.Tag)
		if e != nil {
			var effect func(*Thread)
			effect, cond = e.extractEffect(condbc.block, "switch")
			a.push(effect)
		}
	}

	// Count cases
	ncases := 0
	hasDefault := false
	for _, c := range s.Body.List {
		clause, ok := c.(*ast.CaseClause)
		if !ok {
			a.diagAt(clause.Pos(), "switch statement must contain case clauses")
			continue
		}
		if clause.List == nil {
			if hasDefault {
				a.diagAt(clause.Pos(), "switch statement contains more than one default case")
			}
			hasDefault = true
		} else {
			ncases += len(clause.List)
		}
	}

	// Compile case expressions
	cases := make([]func(*Thread) bool, ncases)
	i := 0
	for _, c := range s.Body.List {
		clause, ok := c.(*ast.CaseClause)
		if !ok {
			continue
		}
		for _, v := range clause.List {
			e := condbc.compileExpr(condbc.block, false, v)
			switch {
			case e == nil:
				// Error reported by compileExpr
			case cond == nil && !e.t.isBoolean():
				a.diagAt(v.Pos(), "'case' condition must be boolean")
			case cond == nil:
				cases[i] = e.asBool()
			case cond != nil:
				// Create comparison
				// TOOD(austin) This produces bad error messages
				compare := e.compileBinaryExpr(token.EQL, cond, e)
				if compare != nil {
					cases[i] = compare.asBool()
				}
			}
			i++
		}
	}

	// Emit condition
	casePCs := make([]*uint, ncases+1)
	endPC := badPC

	a.flow.put(false, false, casePCs)
	a.push(func(t *Thread) {
		for i, c := range cases {
			if c(t) {
				t.pc = *casePCs[i]
				return
			}
		}
		t.pc = *casePCs[ncases]
	})
	condbc.exit()

	// Compile cases
	i = 0
	for _, c := range s.Body.List {
		clause, ok := c.(*ast.CaseClause)
		if !ok {
			continue
		}

		// Save jump PC's
		pc := a.nextPC()
		if clause.List != nil {
			for _ = range clause.List {
				casePCs[i] = &pc
				i++
//.........这里部分代码省略.........

func (s *Sonar) Visit(n ast.Node) ast.Visitor {
	// TODO: detect "x&mask==0", emit sonar(x, x&^mask)
	switch nn := n.(type) {
	case *ast.BinaryExpr:
		break
	case *ast.GenDecl:
		if nn.Tok != token.VAR {
			return nil // constants and types are not interesting
		}
		return s

	case *ast.FuncDecl:
		if s.pkg == "math" && (nn.Name.Name == "Y0" || nn.Name.Name == "Y1" || nn.Name.Name == "Yn" ||
			nn.Name.Name == "J0" || nn.Name.Name == "J1" || nn.Name.Name == "Jn" ||
			nn.Name.Name == "Pow") {
			// Can't handle code there:
			// math/j0.go:93: constant 680564733841876926926749214863536422912 overflows int
			return nil
		}
		return s // recurse

	case *ast.SwitchStmt:
		if nn.Tag == nil || nn.Body == nil {
			return s // recurse
		}
		// Replace:
		//	switch a := foo(); bar(a) {
		//	case x: ...
		//	case y: ...
		//	}
		// with:
		//	switch {
		//	default:
		//		a := foo()
		//		__tmp := bar(a)
		//		switch {
		//		case __tmp == x: ...
		//		case __tmp == y: ...
		//		}
		//	}
		// The == comparisons will be instrumented later when we recurse.
		sw := new(ast.SwitchStmt)
		*sw = *nn
		var stmts []ast.Stmt
		if sw.Init != nil {
			stmts = append(stmts, sw.Init)
			sw.Init = nil
		}
		stmts = append(stmts, &ast.AssignStmt{Lhs: []ast.Expr{&ast.Ident{Name: "__go_fuzz_tmp"}}, Tok: token.DEFINE, Rhs: []ast.Expr{sw.Tag}})
		sw.Tag = nil
		stmts = append(stmts, sw)
		for _, cas1 := range sw.Body.List {
			cas := cas1.(*ast.CaseClause)
			for i, expr := range cas.List {
				cas.List[i] = &ast.BinaryExpr{X: &ast.Ident{Name: "__go_fuzz_tmp", NamePos: expr.Pos()}, Op: token.EQL, Y: expr}
			}
		}
		nn.Tag = nil
		nn.Init = nil
		nn.Body = &ast.BlockStmt{List: []ast.Stmt{&ast.CaseClause{Body: stmts}}}
		return s // recurse

	case *ast.ForStmt:
		// For condition is usually uninteresting, but produces lots of samples.
		// So we skip it if it looks boring.
		if nn.Init != nil {
			ast.Walk(s, nn.Init)
		}
		if nn.Post != nil {
			ast.Walk(s, nn.Post)
		}
		ast.Walk(s, nn.Body)
		if nn.Cond != nil {
			// Look for the following pattern:
			//	for foo := ...; foo ? ...; ... { ... }
			boring := false
			if nn.Init != nil {
				if init, ok1 := nn.Init.(*ast.AssignStmt); ok1 && init.Tok == token.DEFINE && len(init.Lhs) == 1 {
					if id, ok2 := init.Lhs[0].(*ast.Ident); ok2 {
						if bex, ok3 := nn.Cond.(*ast.BinaryExpr); ok3 {
							if x, ok4 := bex.X.(*ast.Ident); ok4 && x.Name == id.Name {
								boring = true
							}
							if x, ok4 := bex.Y.(*ast.Ident); ok4 && x.Name == id.Name {
								boring = true
							}
						}
					}
				}
			}
			if !boring {
				ast.Walk(s, nn.Cond)
			}
		}
		return nil

	default:
		return s // recurse
	}

//.........这里部分代码省略.........