]> Cypherpunks repositories - gostls13.git/commitdiff
cmd/compile: redo mknode.go
authorKeith Randall <khr@golang.org>
Tue, 19 Jul 2022 18:09:01 +0000 (11:09 -0700)
committerKeith Randall <khr@golang.org>
Wed, 31 Aug 2022 22:09:44 +0000 (22:09 +0000)
The current mknode has a few problems:
1) It tends not to run successfully if the tree is in a broken state.
2) It requires that it be run by the go tool in the tree (somewhat related to 1)
3) It requires setting GOROOT
4) It imports code outside the tree (x/packages)

This makes mknode.go very fragile. In particular, I've spent lots of
time fighting mknode when adding or removing code, related to 1.

Rewrite to just use go/ast and friends. No typechecking, no importing,
etc. It can run with any go version, it doesn't need to be the one
corresponding to the code in which it is run. (e.g. you can use go
1.16 to run mknode). It will work as long as the ir package is parseable.

When run, it generates identical output to the old mknode.

Fixes #53959

Change-Id: I5ce0b55572ebcd2fcd11af57a5f29bbf9fa4ed33
Reviewed-on: https://go-review.googlesource.com/c/go/+/418375
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
src/cmd/compile/internal/ir/mini.go
src/cmd/compile/internal/ir/mknode.go

index 48f5eccf34f988e53092a558e8f66699476ba7bd..52c622df2306e6f29f46bdf650fc98f25abf8fe5 100644 (file)
@@ -2,8 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:generate go run -mod=mod mknode.go
-// Note: see comment at top of mknode.go
+//go:generate go run mknode.go
 
 package ir
 
index af8869d1225a1105a33b40f7d8915f4a375d533b..be529a7e5cd98a655fc7c26e849d75d63cce2029 100644 (file)
-// Copyright 2020 The Go Authors. All rights reserved.
+// Copyright 2022 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 //go:build ignore
 // +build ignore
 
-// Note: this program must be run with the GOROOT
-// environment variable set to the root of this tree.
-//   GOROOT=...
-//   cd $GOROOT/src/cmd/compile/internal/ir
-//   ../../../../../bin/go run -mod=mod mknode.go
+// Note: this program must be run in this directory.
+//   go run mknode.go
 
 package main
 
 import (
        "bytes"
        "fmt"
+       "go/ast"
        "go/format"
-       "go/types"
+       "go/parser"
+       "go/token"
+       "io/fs"
        "io/ioutil"
        "log"
-       "reflect"
        "sort"
        "strings"
-
-       "golang.org/x/tools/go/packages"
 )
 
-var irPkg *types.Package
+var fset = token.NewFileSet()
+
 var buf bytes.Buffer
 
-func main() {
-       cfg := &packages.Config{
-               Mode: packages.NeedSyntax | packages.NeedTypes,
+// concreteNodes contains all concrete types in the package that implement Node
+// (except for the mini* types).
+var concreteNodes []*ast.TypeSpec
+
+// interfaceNodes contains all interface types in the package that implement Node.
+var interfaceNodes []*ast.TypeSpec
+
+// mini contains the embeddable mini types (miniNode, miniExpr, and miniStmt).
+var mini = map[string]*ast.TypeSpec{}
+
+// implementsNode reports whether the type t is one which represents a Node
+// in the AST.
+func implementsNode(t ast.Expr) bool {
+       id, ok := t.(*ast.Ident)
+       if !ok {
+               return false // only named types
        }
-       pkgs, err := packages.Load(cfg, "cmd/compile/internal/ir")
-       if err != nil {
-               log.Fatal(err)
+       for _, ts := range interfaceNodes {
+               if ts.Name.Name == id.Name {
+                       return true
+               }
+       }
+       for _, ts := range concreteNodes {
+               if ts.Name.Name == id.Name {
+                       return true
+               }
+       }
+       return false
+}
+
+func isMini(t ast.Expr) bool {
+       id, ok := t.(*ast.Ident)
+       return ok && mini[id.Name] != nil
+}
+
+func isNamedType(t ast.Expr, name string) bool {
+       if id, ok := t.(*ast.Ident); ok {
+               if id.Name == name {
+                       return true
+               }
        }
-       irPkg = pkgs[0].Types
+       return false
+}
 
+func main() {
        fmt.Fprintln(&buf, "// Code generated by mknode.go. DO NOT EDIT.")
        fmt.Fprintln(&buf)
        fmt.Fprintln(&buf, "package ir")
        fmt.Fprintln(&buf)
        fmt.Fprintln(&buf, `import "fmt"`)
 
-       scope := irPkg.Scope()
-       for _, name := range scope.Names() {
-               if strings.HasPrefix(name, "mini") {
-                       continue
-               }
-
-               obj, ok := scope.Lookup(name).(*types.TypeName)
-               if !ok {
-                       continue
-               }
-               typ := obj.Type().(*types.Named)
-               if !implementsNode(types.NewPointer(typ)) {
-                       continue
+       filter := func(file fs.FileInfo) bool {
+               return !strings.HasPrefix(file.Name(), "mknode")
+       }
+       pkgs, err := parser.ParseDir(fset, ".", filter, 0)
+       if err != nil {
+               panic(err)
+       }
+       pkg := pkgs["ir"]
+
+       // Find all the mini types. These let us determine which
+       // concrete types implement Node, so we need to find them first.
+       for _, f := range pkg.Files {
+               for _, d := range f.Decls {
+                       g, ok := d.(*ast.GenDecl)
+                       if !ok {
+                               continue
+                       }
+                       for _, s := range g.Specs {
+                               t, ok := s.(*ast.TypeSpec)
+                               if !ok {
+                                       continue
+                               }
+                               if strings.HasPrefix(t.Name.Name, "mini") {
+                                       mini[t.Name.Name] = t
+                                       // Double-check that it is or embeds miniNode.
+                                       if t.Name.Name != "miniNode" {
+                                               s := t.Type.(*ast.StructType)
+                                               if !isNamedType(s.Fields.List[0].Type, "miniNode") {
+                                                       panic(fmt.Sprintf("can't find miniNode in %s", t.Name.Name))
+                                               }
+                                       }
+                               }
+                       }
                }
+       }
 
-               fmt.Fprintf(&buf, "\n")
-               fmt.Fprintf(&buf, "func (n *%s) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }\n", name)
-
-               switch name {
-               case "Name", "Func":
-                       // Too specialized to automate.
-                       continue
+       // Find all the declarations of concrete types that implement Node.
+       for _, f := range pkg.Files {
+               for _, d := range f.Decls {
+                       g, ok := d.(*ast.GenDecl)
+                       if !ok {
+                               continue
+                       }
+                       for _, s := range g.Specs {
+                               t, ok := s.(*ast.TypeSpec)
+                               if !ok {
+                                       continue
+                               }
+                               if strings.HasPrefix(t.Name.Name, "mini") {
+                                       // We don't treat the mini types as
+                                       // concrete implementations of Node
+                                       // (even though they are) because
+                                       // we only use them by embedding them.
+                                       continue
+                               }
+                               if isConcreteNode(t) {
+                                       concreteNodes = append(concreteNodes, t)
+                               }
+                               if isInterfaceNode(t) {
+                                       interfaceNodes = append(interfaceNodes, t)
+                               }
+                       }
                }
-
-               forNodeFields(typ,
-                       "func (n *%[1]s) copy() Node { c := *n\n",
-                       "",
-                       "c.%[1]s = copy%[2]s(c.%[1]s)",
-                       "return &c }\n")
-
-               forNodeFields(typ,
-                       "func (n *%[1]s) doChildren(do func(Node) bool) bool {\n",
-                       "if n.%[1]s != nil && do(n.%[1]s) { return true }",
-                       "if do%[2]s(n.%[1]s, do) { return true }",
-                       "return false }\n")
-
-               forNodeFields(typ,
-                       "func (n *%[1]s) editChildren(edit func(Node) Node) {\n",
-                       "if n.%[1]s != nil { n.%[1]s = edit(n.%[1]s).(%[2]s) }",
-                       "edit%[2]s(n.%[1]s, edit)",
-                       "}\n")
        }
+       // Sort for deterministic output.
+       sort.Slice(concreteNodes, func(i, j int) bool {
+               return concreteNodes[i].Name.Name < concreteNodes[j].Name.Name
+       })
+       // Generate code for each concrete type.
+       for _, t := range concreteNodes {
+               processType(t)
+       }
+       // Add some helpers.
+       generateHelpers()
 
-       makeHelpers()
-
+       // Format and write output.
        out, err := format.Source(buf.Bytes())
        if err != nil {
                // write out mangled source so we can see the bug.
                out = buf.Bytes()
        }
-
        err = ioutil.WriteFile("node_gen.go", out, 0666)
        if err != nil {
                log.Fatal(err)
        }
 }
 
-// needHelper maps needed slice helpers from their base name to their
-// respective slice-element type.
-var needHelper = map[string]string{}
-
-func makeHelpers() {
-       var names []string
-       for name := range needHelper {
-               names = append(names, name)
+// isConcreteNode reports whether the type t is a concrete type
+// implementing Node.
+func isConcreteNode(t *ast.TypeSpec) bool {
+       s, ok := t.Type.(*ast.StructType)
+       if !ok {
+               return false
        }
-       sort.Strings(names)
-
-       for _, name := range names {
-               fmt.Fprintf(&buf, sliceHelperTmpl, name, needHelper[name])
+       for _, f := range s.Fields.List {
+               if isMini(f.Type) {
+                       return true
+               }
        }
+       return false
 }
 
-const sliceHelperTmpl = `
-func copy%[1]s(list []%[2]s) []%[2]s {
-       if list == nil {
-               return nil
+// isInterfaceNode reports whether the type t is an interface type
+// implementing Node (including Node itself).
+func isInterfaceNode(t *ast.TypeSpec) bool {
+       s, ok := t.Type.(*ast.InterfaceType)
+       if !ok {
+               return false
        }
-       c := make([]%[2]s, len(list))
-       copy(c, list)
-       return c
-}
-func do%[1]s(list []%[2]s, do func(Node) bool) bool {
-       for _, x := range list {
-               if x != nil && do(x) {
+       if t.Name.Name == "Node" {
+               return true
+       }
+       if t.Name.Name == "OrigNode" || t.Name.Name == "InitNode" {
+               // These we exempt from consideration (fields of
+               // this type don't need to be walked or copied).
+               return false
+       }
+
+       // Look for embedded Node type.
+       // Note that this doesn't handle multi-level embedding, but
+       // we have none of that at the moment.
+       for _, f := range s.Methods.List {
+               if len(f.Names) != 0 {
+                       continue
+               }
+               if isNamedType(f.Type, "Node") {
                        return true
                }
        }
        return false
 }
-func edit%[1]s(list []%[2]s, edit func(Node) Node) {
-       for i, x := range list {
-               if x != nil {
-                       list[i] = edit(x).(%[2]s)
-               }
-       }
-}
-`
 
-func forNodeFields(named *types.Named, prologue, singleTmpl, sliceTmpl, epilogue string) {
-       fmt.Fprintf(&buf, prologue, named.Obj().Name())
+func processType(t *ast.TypeSpec) {
+       name := t.Name.Name
+       fmt.Fprintf(&buf, "\n")
+       fmt.Fprintf(&buf, "func (n *%s) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }\n", name)
 
-       anyField(named.Underlying().(*types.Struct), func(f *types.Var) bool {
-               if f.Embedded() {
-                       return false
-               }
-               name, typ := f.Name(), f.Type()
+       switch name {
+       case "Name", "Func":
+               // Too specialized to automate.
+               return
+       }
 
-               slice, _ := typ.Underlying().(*types.Slice)
-               if slice != nil {
-                       typ = slice.Elem()
-               }
+       s := t.Type.(*ast.StructType)
+       fields := s.Fields.List
 
-               tmpl, what := singleTmpl, types.TypeString(typ, types.RelativeTo(irPkg))
-               if what == "go/constant.Value" {
-                       return false
+       // Expand any embedded fields.
+       for i := 0; i < len(fields); i++ {
+               f := fields[i]
+               if len(f.Names) != 0 {
+                       continue // not embedded
                }
-               if implementsNode(typ) {
-                       if slice != nil {
-                               helper := strings.TrimPrefix(what, "*") + "s"
-                               needHelper[helper] = what
-                               tmpl, what = sliceTmpl, helper
-                       }
-               } else if what == "*Field" {
-                       // Special case for *Field.
-                       tmpl = sliceTmpl
-                       if slice != nil {
-                               what = "Fields"
-                       } else {
-                               what = "Field"
-                       }
+               if isMini(f.Type) {
+                       // Insert the fields of the embedded type into the main type.
+                       // (It would be easier just to append, but inserting in place
+                       // matches the old mknode behavior.)
+                       ss := mini[f.Type.(*ast.Ident).Name].Type.(*ast.StructType)
+                       var f2 []*ast.Field
+                       f2 = append(f2, fields[:i]...)
+                       f2 = append(f2, ss.Fields.List...)
+                       f2 = append(f2, fields[i+1:]...)
+                       fields = f2
+                       i--
+                       continue
+               } else if isNamedType(f.Type, "origNode") {
+                       // Ignore this field
+                       copy(fields[i:], fields[i+1:])
+                       fields = fields[:len(fields)-1]
+                       i--
+                       continue
                } else {
-                       return false
-               }
-
-               if tmpl == "" {
-                       return false
-               }
-
-               // Allow template to not use all arguments without
-               // upsetting fmt.Printf.
-               s := fmt.Sprintf(tmpl+"\x00 %[1]s %[2]s", name, what)
-               fmt.Fprintln(&buf, s[:strings.LastIndex(s, "\x00")])
-               return false
-       })
-
-       fmt.Fprintf(&buf, epilogue)
-}
-
-func implementsNode(typ types.Type) bool {
-       if _, ok := typ.Underlying().(*types.Interface); ok {
-               // TODO(mdempsky): Check the interface implements Node.
-               // Worst case, node_gen.go will fail to compile if we're wrong.
-               return true
-       }
-
-       if ptr, ok := typ.(*types.Pointer); ok {
-               if str, ok := ptr.Elem().Underlying().(*types.Struct); ok {
-                       return anyField(str, func(f *types.Var) bool {
-                               return f.Embedded() && f.Name() == "miniNode"
-                       })
+                       panic("unknown embedded field " + fmt.Sprintf("%v", f.Type))
                }
        }
-
-       return false
-}
-
-func anyField(typ *types.Struct, pred func(f *types.Var) bool) bool {
-       for i, n := 0, typ.NumFields(); i < n; i++ {
-               if value, ok := reflect.StructTag(typ.Tag(i)).Lookup("mknode"); ok {
-                       if value != "-" {
-                               panic(fmt.Sprintf("unexpected tag value: %q", value))
+       // Process fields.
+       var copyBody bytes.Buffer
+       var doChildrenBody bytes.Buffer
+       var editChildrenBody bytes.Buffer
+       for _, f := range fields {
+               if f.Tag != nil {
+                       tag := f.Tag.Value[1 : len(f.Tag.Value)-1]
+                       if strings.HasPrefix(tag, "mknode:") {
+                               if tag[7:] == "\"-\"" {
+                                       continue
+                               }
+                               panic(fmt.Sprintf("unexpected tag value: %s", tag))
                        }
-                       continue
                }
-
-               f := typ.Field(i)
-               if pred(f) {
-                       return true
+               names := f.Names
+               ft := f.Type
+               if isNamedType(ft, "Nodes") {
+                       // Nodes == []Node
+                       ft = &ast.ArrayType{Elt: &ast.Ident{Name: "Node"}}
+               }
+               isSlice := false
+               if a, ok := ft.(*ast.ArrayType); ok && a.Len == nil {
+                       isSlice = true
+                       ft = a.Elt
+               }
+               isPtr := false
+               if p, ok := ft.(*ast.StarExpr); ok {
+                       isPtr = true
+                       ft = p.X
                }
-               if f.Embedded() {
-                       if typ, ok := f.Type().Underlying().(*types.Struct); ok {
-                               if anyField(typ, pred) {
-                                       return true
+               if !implementsNode(ft) {
+                       continue
+               }
+               for _, name := range names {
+                       if isSlice {
+                               fmt.Fprintf(&copyBody, "c.%s = copy%ss(c.%s)\n", name, ft, name)
+                               fmt.Fprintf(&doChildrenBody,
+                                       "if do%ss(n.%s, do) {\nreturn true\n}\n", ft, name)
+                               fmt.Fprintf(&editChildrenBody,
+                                       "edit%ss(n.%s, edit)\n", ft, name)
+                       } else {
+                               fmt.Fprintf(&doChildrenBody,
+                                       "if n.%s != nil && do(n.%s) {\nreturn true\n}\n", name, name)
+                               ptr := ""
+                               if isPtr {
+                                       ptr = "*"
                                }
+                               fmt.Fprintf(&editChildrenBody,
+                                       "if n.%s != nil {\nn.%s = edit(n.%s).(%s%s)\n}\n", name, name, name, ptr, ft)
                        }
                }
        }
-       return false
+       fmt.Fprintf(&buf, "func (n *%s) copy() Node {\nc := *n\n", name)
+       buf.WriteString(copyBody.String())
+       fmt.Fprintf(&buf, "return &c\n}\n")
+       fmt.Fprintf(&buf, "func (n *%s) doChildren(do func(Node) bool) bool {\n", name)
+       buf.WriteString(doChildrenBody.String())
+       fmt.Fprintf(&buf, "return false\n}\n")
+       fmt.Fprintf(&buf, "func (n *%s) editChildren(edit func(Node) Node) {\n", name)
+       buf.WriteString(editChildrenBody.String())
+       fmt.Fprintf(&buf, "}\n")
+}
+
+func generateHelpers() {
+       for _, typ := range []string{"CaseClause", "CommClause", "Name", "Node", "Ntype"} {
+               ptr := "*"
+               if typ == "Node" || typ == "Ntype" {
+                       ptr = "" // interfaces don't need *
+               }
+               fmt.Fprintf(&buf, "\n")
+               fmt.Fprintf(&buf, "func copy%ss(list []%s%s) []%s%s {\n", typ, ptr, typ, ptr, typ)
+               fmt.Fprintf(&buf, "if list == nil { return nil }\n")
+               fmt.Fprintf(&buf, "c := make([]%s%s, len(list))\n", ptr, typ)
+               fmt.Fprintf(&buf, "copy(c, list)\n")
+               fmt.Fprintf(&buf, "return c\n")
+               fmt.Fprintf(&buf, "}\n")
+               fmt.Fprintf(&buf, "func do%ss(list []%s%s, do func(Node) bool) bool {\n", typ, ptr, typ)
+               fmt.Fprintf(&buf, "for _, x := range list {\n")
+               fmt.Fprintf(&buf, "if x != nil && do(x) {\n")
+               fmt.Fprintf(&buf, "return true\n")
+               fmt.Fprintf(&buf, "}\n")
+               fmt.Fprintf(&buf, "}\n")
+               fmt.Fprintf(&buf, "return false\n")
+               fmt.Fprintf(&buf, "}\n")
+               fmt.Fprintf(&buf, "func edit%ss(list []%s%s, edit func(Node) Node) {\n", typ, ptr, typ)
+               fmt.Fprintf(&buf, "for i, x := range list {\n")
+               fmt.Fprintf(&buf, "if x != nil {\n")
+               fmt.Fprintf(&buf, "list[i] = edit(x).(%s%s)\n", ptr, typ)
+               fmt.Fprintf(&buf, "}\n")
+               fmt.Fprintf(&buf, "}\n")
+               fmt.Fprintf(&buf, "}\n")
+       }
 }