[dev.regabi] cmd/compile: backport changes from dev.typeparams (9456804)

This CL backports a bunch of changes that landed on dev.typeparams,
but are not dependent on types2 or generics. By backporting, we reduce
the divergence between development branches, hopefully improving test
coverage and reducing risk of merge conflicts.

Updates #43866.

Change-Id: I382510855c9b5fac52b17066e44a00bd07fe86f5
Reviewed-on: https://go-review.googlesource.com/c/go/+/286172
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>

1 files changed, 82 insertions, 186 deletions

diff --git a/src/cmd/compile/internal/noder/noder.go b/src/cmd/compile/internal/noder/noder.go
index 5bb01895cc..6aab18549a 100644
--- a/src/cmd/compile/internal/noder/noder.go
+++ b/src/cmd/compile/internal/noder/noder.go
@@ -17,6 +17,7 @@ import (
 	"unicode/utf8"
 
 	"cmd/compile/internal/base"
+	"cmd/compile/internal/dwarfgen"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/syntax"
 	"cmd/compile/internal/typecheck"
@@ -27,40 +28,26 @@ import (
 
 func LoadPackage(filenames []string) {
 	base.Timer.Start("fe", "parse")
-	lines := ParseFiles(filenames)
-	base.Timer.Stop()
-	base.Timer.AddEvent(int64(lines), "lines")
 
-	// Typecheck.
-	Package()
+	mode := syntax.CheckBranches
 
-	// With all user code typechecked, it's now safe to verify unused dot imports.
-	CheckDotImports()
-	base.ExitIfErrors()
-}
-
-// ParseFiles concurrently parses files into *syntax.File structures.
-// Each declaration in every *syntax.File is converted to a syntax tree
-// and its root represented by *Node is appended to Target.Decls.
-// Returns the total count of parsed lines.
-func ParseFiles(filenames []string) uint {
-	noders := make([]*noder, 0, len(filenames))
 	// Limit the number of simultaneously open files.
 	sem := make(chan struct{}, runtime.GOMAXPROCS(0)+10)
 
-	for _, filename := range filenames {
-		p := &noder{
-			basemap:     make(map[*syntax.PosBase]*src.PosBase),
+	noders := make([]*noder, len(filenames))
+	for i, filename := range filenames {
+		p := noder{
 			err:         make(chan syntax.Error),
 			trackScopes: base.Flag.Dwarf,
 		}
-		noders = append(noders, p)
+		noders[i] = &p
 
-		go func(filename string) {
+		filename := filename
+		go func() {
 			sem <- struct{}{}
 			defer func() { <-sem }()
 			defer close(p.err)
-			base := syntax.NewFileBase(filename)
+			fbase := syntax.NewFileBase(filename)
 
 			f, err := os.Open(filename)
 			if err != nil {
@@ -69,8 +56,8 @@ func ParseFiles(filenames []string) uint {
 			}
 			defer f.Close()
 
-			p.file, _ = syntax.Parse(base, f, p.error, p.pragma, syntax.CheckBranches) // errors are tracked via p.error
-		}(filename)
+			p.file, _ = syntax.Parse(fbase, f, p.error, p.pragma, mode) // errors are tracked via p.error
+		}()
 	}
 
 	var lines uint
@@ -78,30 +65,27 @@ func ParseFiles(filenames []string) uint {
 		for e := range p.err {
 			p.errorAt(e.Pos, "%s", e.Msg)
 		}
+		lines += p.file.Lines
+	}
+	base.Timer.AddEvent(int64(lines), "lines")
 
+	for _, p := range noders {
 		p.node()
-		lines += p.file.Lines
 		p.file = nil // release memory
+	}
 
-		if base.SyntaxErrors() != 0 {
-			base.ErrorExit()
-		}
-		// Always run CheckDclstack here, even when debug_dclstack is not set, as a sanity measure.
-		types.CheckDclstack()
+	if base.SyntaxErrors() != 0 {
+		base.ErrorExit()
 	}
+	types.CheckDclstack()
 
 	for _, p := range noders {
 		p.processPragmas()
 	}
 
+	// Typecheck.
 	types.LocalPkg.Height = myheight
-
-	return lines
-}
-
-func Package() {
 	typecheck.DeclareUniverse()
-
 	typecheck.TypecheckAllowed = true
 
 	// Process top-level declarations in phases.
@@ -166,44 +150,10 @@ func Package() {
 	}
 
 	// Phase 5: With all user code type-checked, it's now safe to verify map keys.
+	// With all user code typechecked, it's now safe to verify unused dot imports.
 	typecheck.CheckMapKeys()
-
-}
-
-// makeSrcPosBase translates from a *syntax.PosBase to a *src.PosBase.
-func (p *noder) makeSrcPosBase(b0 *syntax.PosBase) *src.PosBase {
-	// fast path: most likely PosBase hasn't changed
-	if p.basecache.last == b0 {
-		return p.basecache.base
-	}
-
-	b1, ok := p.basemap[b0]
-	if !ok {
-		fn := b0.Filename()
-		if b0.IsFileBase() {
-			b1 = src.NewFileBase(fn, absFilename(fn))
-		} else {
-			// line directive base
-			p0 := b0.Pos()
-			p0b := p0.Base()
-			if p0b == b0 {
-				panic("infinite recursion in makeSrcPosBase")
-			}
-			p1 := src.MakePos(p.makeSrcPosBase(p0b), p0.Line(), p0.Col())
-			b1 = src.NewLinePragmaBase(p1, fn, fileh(fn), b0.Line(), b0.Col())
-		}
-		p.basemap[b0] = b1
-	}
-
-	// update cache
-	p.basecache.last = b0
-	p.basecache.base = b1
-
-	return b1
-}
-
-func (p *noder) makeXPos(pos syntax.Pos) (_ src.XPos) {
-	return base.Ctxt.PosTable.XPos(src.MakePos(p.makeSrcPosBase(pos.Base()), pos.Line(), pos.Col()))
+	CheckDotImports()
+	base.ExitIfErrors()
 }
 
 func (p *noder) errorAt(pos syntax.Pos, format string, args ...interface{}) {
@@ -221,31 +171,33 @@ func absFilename(name string) string {
 
 // noder transforms package syntax's AST into a Node tree.
 type noder struct {
-	basemap   map[*syntax.PosBase]*src.PosBase
-	basecache struct {
-		last *syntax.PosBase
-		base *src.PosBase
-	}
+	posMap
 
 	file           *syntax.File
 	linknames      []linkname
 	pragcgobuf     [][]string
 	err            chan syntax.Error
-	scope          ir.ScopeID
 	importedUnsafe bool
 	importedEmbed  bool
+	trackScopes    bool
 
-	// scopeVars is a stack tracking the number of variables declared in the
-	// current function at the moment each open scope was opened.
-	trackScopes bool
-	scopeVars   []int
+	funcState *funcState
+}
+
+// funcState tracks all per-function state to make handling nested
+// functions easier.
+type funcState struct {
+	// scopeVars is a stack tracking the number of variables declared in
+	// the current function at the moment each open scope was opened.
+	scopeVars []int
+	marker    dwarfgen.ScopeMarker
 
 	lastCloseScopePos syntax.Pos
 }
 
 func (p *noder) funcBody(fn *ir.Func, block *syntax.BlockStmt) {
-	oldScope := p.scope
-	p.scope = 0
+	outerFuncState := p.funcState
+	p.funcState = new(funcState)
 	typecheck.StartFuncBody(fn)
 
 	if block != nil {
@@ -260,62 +212,34 @@ func (p *noder) funcBody(fn *ir.Func, block *syntax.BlockStmt) {
 	}
 
 	typecheck.FinishFuncBody()
-	p.scope = oldScope
+	p.funcState.marker.WriteTo(fn)
+	p.funcState = outerFuncState
 }
 
 func (p *noder) openScope(pos syntax.Pos) {
+	fs := p.funcState
 	types.Markdcl()
 
 	if p.trackScopes {
-		ir.CurFunc.Parents = append(ir.CurFunc.Parents, p.scope)
-		p.scopeVars = append(p.scopeVars, len(ir.CurFunc.Dcl))
-		p.scope = ir.ScopeID(len(ir.CurFunc.Parents))
-
-		p.markScope(pos)
+		fs.scopeVars = append(fs.scopeVars, len(ir.CurFunc.Dcl))
+		fs.marker.Push(p.makeXPos(pos))
 	}
 }
 
 func (p *noder) closeScope(pos syntax.Pos) {
-	p.lastCloseScopePos = pos
+	fs := p.funcState
+	fs.lastCloseScopePos = pos
 	types.Popdcl()
 
 	if p.trackScopes {
-		scopeVars := p.scopeVars[len(p.scopeVars)-1]
-		p.scopeVars = p.scopeVars[:len(p.scopeVars)-1]
+		scopeVars := fs.scopeVars[len(fs.scopeVars)-1]
+		fs.scopeVars = fs.scopeVars[:len(fs.scopeVars)-1]
 		if scopeVars == len(ir.CurFunc.Dcl) {
 			// no variables were declared in this scope, so we can retract it.
-
-			if int(p.scope) != len(ir.CurFunc.Parents) {
-				base.Fatalf("scope tracking inconsistency, no variables declared but scopes were not retracted")
-			}
-
-			p.scope = ir.CurFunc.Parents[p.scope-1]
-			ir.CurFunc.Parents = ir.CurFunc.Parents[:len(ir.CurFunc.Parents)-1]
-
-			nmarks := len(ir.CurFunc.Marks)
-			ir.CurFunc.Marks[nmarks-1].Scope = p.scope
-			prevScope := ir.ScopeID(0)
-			if nmarks >= 2 {
-				prevScope = ir.CurFunc.Marks[nmarks-2].Scope
-			}
-			if ir.CurFunc.Marks[nmarks-1].Scope == prevScope {
-				ir.CurFunc.Marks = ir.CurFunc.Marks[:nmarks-1]
-			}
-			return
+			fs.marker.Unpush()
+		} else {
+			fs.marker.Pop(p.makeXPos(pos))
 		}
-
-		p.scope = ir.CurFunc.Parents[p.scope-1]
-
-		p.markScope(pos)
-	}
-}
-
-func (p *noder) markScope(pos syntax.Pos) {
-	xpos := p.makeXPos(pos)
-	if i := len(ir.CurFunc.Marks); i > 0 && ir.CurFunc.Marks[i-1].Pos == xpos {
-		ir.CurFunc.Marks[i-1].Scope = p.scope
-	} else {
-		ir.CurFunc.Marks = append(ir.CurFunc.Marks, ir.Mark{Pos: xpos, Scope: p.scope})
 	}
 }
 
@@ -324,7 +248,7 @@ func (p *noder) markScope(pos syntax.Pos) {
 // "if" statements, as their implicit blocks always end at the same
 // position as an explicit block.
 func (p *noder) closeAnotherScope() {
-	p.closeScope(p.lastCloseScopePos)
+	p.closeScope(p.funcState.lastCloseScopePos)
 }
 
 // linkname records a //go:linkname directive.
@@ -335,7 +259,6 @@ type linkname struct {
 }
 
 func (p *noder) node() {
-	types.Block = 1
 	p.importedUnsafe = false
 	p.importedEmbed = false
 
@@ -404,7 +327,7 @@ func (p *noder) decls(decls []syntax.Decl) (l []ir.Node) {
 }
 
 func (p *noder) importDecl(imp *syntax.ImportDecl) {
-	if imp.Path.Bad {
+	if imp.Path == nil || imp.Path.Bad {
 		return // avoid follow-on errors if there was a syntax error
 	}
 
@@ -412,7 +335,7 @@ func (p *noder) importDecl(imp *syntax.ImportDecl) {
 		p.checkUnused(pragma)
 	}
 
-	ipkg := importfile(p.basicLit(imp.Path))
+	ipkg := importfile(imp)
 	if ipkg == nil {
 		if base.Errors() == 0 {
 			base.Fatalf("phase error in import")
@@ -427,11 +350,6 @@ func (p *noder) importDecl(imp *syntax.ImportDecl) {
 		p.importedEmbed = true
 	}
 
-	if !ipkg.Direct {
-		typecheck.Target.Imports = append(typecheck.Target.Imports, ipkg)
-	}
-	ipkg.Direct = true
-
 	var my *types.Sym
 	if imp.LocalPkgName != nil {
 		my = p.name(imp.LocalPkgName)
@@ -465,20 +383,7 @@ func (p *noder) varDecl(decl *syntax.VarDecl) []ir.Node {
 	exprs := p.exprList(decl.Values)
 
 	if pragma, ok := decl.Pragma.(*pragmas); ok {
-		if len(pragma.Embeds) > 0 {
-			if !p.importedEmbed {
-				// This check can't be done when building the list pragma.Embeds
-				// because that list is created before the noder starts walking over the file,
-				// so at that point it hasn't seen the imports.
-				// We're left to check now, just before applying the //go:embed lines.
-				for _, e := range pragma.Embeds {
-					p.errorAt(e.Pos, "//go:embed only allowed in Go files that import \"embed\"")
-				}
-			} else {
-				varEmbed(p, names, typ, exprs, pragma.Embeds)
-			}
-			pragma.Embeds = nil
-		}
+		varEmbed(p.makeXPos, names[0], decl, pragma, p.importedEmbed)
 		p.checkUnused(pragma)
 	}
 
@@ -1126,9 +1031,16 @@ func (p *noder) stmtFall(stmt syntax.Stmt, fallOK bool) ir.Node {
 	case *syntax.DeclStmt:
 		return ir.NewBlockStmt(src.NoXPos, p.decls(stmt.DeclList))
 	case *syntax.AssignStmt:
+		if stmt.Rhs == syntax.ImplicitOne {
+			one := constant.MakeInt64(1)
+			pos := p.pos(stmt)
+			n := ir.NewAssignOpStmt(pos, p.binOp(stmt.Op), p.expr(stmt.Lhs), ir.NewBasicLit(pos, one))
+			n.IncDec = true
+			return n
+		}
+
 		if stmt.Op != 0 && stmt.Op != syntax.Def {
 			n := ir.NewAssignOpStmt(p.pos(stmt), p.binOp(stmt.Op), p.expr(stmt.Lhs), p.expr(stmt.Rhs))
-			n.IncDec = stmt.Rhs == syntax.ImplicitOne
 			return n
 		}
 
@@ -1588,15 +1500,6 @@ func (p *noder) wrapname(n syntax.Node, x ir.Node) ir.Node {
 	return x
 }
 
-func (p *noder) pos(n syntax.Node) src.XPos {
-	// TODO(gri): orig.Pos() should always be known - fix package syntax
-	xpos := base.Pos
-	if pos := n.Pos(); pos.IsKnown() {
-		xpos = p.makeXPos(pos)
-	}
-	return xpos
-}
-
 func (p *noder) setlineno(n syntax.Node) {
 	if n != nil {
 		base.Pos = p.pos(n)
@@ -1923,48 +1826,41 @@ func oldname(s *types.Sym) ir.Node {
 	return n
 }
 
-func varEmbed(p *noder, names []*ir.Name, typ ir.Ntype, exprs []ir.Node, embeds []pragmaEmbed) {
-	haveEmbed := false
-	for _, decl := range p.file.DeclList {
-		imp, ok := decl.(*syntax.ImportDecl)
-		if !ok {
-			// imports always come first
-			break
-		}
-		path, _ := strconv.Unquote(imp.Path.Value)
-		if path == "embed" {
-			haveEmbed = true
-			break
-		}
+func varEmbed(makeXPos func(syntax.Pos) src.XPos, name *ir.Name, decl *syntax.VarDecl, pragma *pragmas, haveEmbed bool) {
+	if pragma.Embeds == nil {
+		return
 	}
 
-	pos := embeds[0].Pos
+	pragmaEmbeds := pragma.Embeds
+	pragma.Embeds = nil
+	pos := makeXPos(pragmaEmbeds[0].Pos)
+
 	if !haveEmbed {
-		p.errorAt(pos, "invalid go:embed: missing import \"embed\"")
+		base.ErrorfAt(pos, "go:embed only allowed in Go files that import \"embed\"")
 		return
 	}
-	if len(names) > 1 {
-		p.errorAt(pos, "go:embed cannot apply to multiple vars")
+	if len(decl.NameList) > 1 {
+		base.ErrorfAt(pos, "go:embed cannot apply to multiple vars")
 		return
 	}
-	if len(exprs) > 0 {
-		p.errorAt(pos, "go:embed cannot apply to var with initializer")
+	if decl.Values != nil {
+		base.ErrorfAt(pos, "go:embed cannot apply to var with initializer")
 		return
 	}
-	if typ == nil {
-		// Should not happen, since len(exprs) == 0 now.
-		p.errorAt(pos, "go:embed cannot apply to var without type")
+	if decl.Type == nil {
+		// Should not happen, since Values == nil now.
+		base.ErrorfAt(pos, "go:embed cannot apply to var without type")
 		return
 	}
 	if typecheck.DeclContext != ir.PEXTERN {
-		p.errorAt(pos, "go:embed cannot apply to var inside func")
+		base.ErrorfAt(pos, "go:embed cannot apply to var inside func")
 		return
 	}
 
-	v := names[0]
-	typecheck.Target.Embeds = append(typecheck.Target.Embeds, v)
-	v.Embed = new([]ir.Embed)
-	for _, e := range embeds {
-		*v.Embed = append(*v.Embed, ir.Embed{Pos: p.makeXPos(e.Pos), Patterns: e.Patterns})
+	var embeds []ir.Embed
+	for _, e := range pragmaEmbeds {
+		embeds = append(embeds, ir.Embed{Pos: makeXPos(e.Pos), Patterns: e.Patterns})
 	}
+	typecheck.Target.Embeds = append(typecheck.Target.Embeds, name)
+	name.Embed = &embeds
 }