cmd/internal/obj: move dwarf.Var generation into compiler

Passes toolstash -cmp.

Change-Id: I4bd60f7ebba5457e7b3ece688fee2351bfeeb59a
Reviewed-on: https://go-review.googlesource.com/37874
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alessandro Arzilli <alessandro.arzilli@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>

src/cmd/compile/fmt_test.go

@@ -592,6 +592,7 @@ var knownFormats = map[string]string{
 	"*cmd/compile/internal/ssa.Value %v":              "",
 	"*cmd/compile/internal/ssa.sparseTreeMapEntry %v": "",
 	"*cmd/internal/obj.Addr %v":                       "",
+	"*cmd/internal/obj.LSym %v":                       "",
 	"*cmd/internal/obj.Prog %p":                       "",
 	"*cmd/internal/obj.Prog %s":                       "",
 	"*cmd/internal/obj.Prog %v":                       "",

src/cmd/compile/internal/gc/main.go

@@ -113,6 +113,7 @@ func Main() {
 	defer hidePanic()
 
 	Ctxt = obj.Linknew(Thearch.LinkArch)
+	Ctxt.DebugInfo = debuginfo
 	Ctxt.DiagFunc = yyerror
 	Ctxt.Bso = bufio.NewWriter(os.Stdout)
 

src/cmd/compile/internal/gc/pgen.go

@@ -6,6 +6,7 @@ package gc
 
 import (
 	"cmd/compile/internal/ssa"
+	"cmd/internal/dwarf"
 	"cmd/internal/obj"
 	"cmd/internal/src"
 	"cmd/internal/sys"
@@ -420,8 +421,6 @@ func compile(fn *Node) {
 	gcargs := makefuncdatasym("gcargs·", obj.FUNCDATA_ArgsPointerMaps)
 	gclocals := makefuncdatasym("gclocals·", obj.FUNCDATA_LocalsPointerMaps)
 
-	gendebug(fnsym, fn.Func.Dcl)
-
 	genssa(ssafn, ptxt, gcargs, gclocals)
 	ssafn.Free()
 
@@ -431,42 +430,67 @@ func compile(fn *Node) {
 	fieldtrack(fnsym, fn.Func.FieldTrack)
 }
 
-func gendebug(fnsym *obj.LSym, decls []*Node) {
-	if fnsym == nil {
-		return
+func debuginfo(fnsym *obj.LSym) []*dwarf.Var {
+	if expect := Linksym(Curfn.Func.Nname.Sym); fnsym != expect {
+		Fatalf("unexpected fnsym: %v != %v", fnsym, expect)
 	}
 
-	if fnsym.FuncInfo == nil {
-		fnsym.FuncInfo = new(obj.FuncInfo)
-	}
-
-	for _, n := range decls {
+	var vars []*dwarf.Var
+	for _, n := range Curfn.Func.Dcl {
 		if n.Op != ONAME { // might be OTYPE or OLITERAL
 			continue
 		}
 
 		var name obj.AddrName
+		var abbrev int
+		offs := n.Xoffset
+
 		switch n.Class {
 		case PAUTO:
 			if !n.Used() {
 				continue
 			}
 			name = obj.NAME_AUTO
+
+			abbrev = dwarf.DW_ABRV_AUTO
+			if Ctxt.FixedFrameSize() == 0 {
+				offs -= int64(Widthptr)
+			}
+			if obj.Framepointer_enabled(obj.GOOS, obj.GOARCH) {
+				offs -= int64(Widthptr)
+			}
+
 		case PPARAM, PPARAMOUT:
 			name = obj.NAME_PARAM
+
+			abbrev = dwarf.DW_ABRV_PARAM
+			offs += Ctxt.FixedFrameSize()
+
 		default:
 			continue
 		}
 
-		a := &obj.Auto{
+		gotype := Linksym(ngotype(n))
+		fnsym.Autom = append(fnsym.Autom, &obj.Auto{
 			Asym:    obj.Linklookup(Ctxt, n.Sym.Name, 0),
 			Aoffset: int32(n.Xoffset),
 			Name:    name,
-			Gotype:  Linksym(ngotype(n)),
+			Gotype:  gotype,
+		})
+
+		typename := dwarf.InfoPrefix + gotype.Name[len("type."):]
+		vars = append(vars, &dwarf.Var{
+			Name:   n.Sym.Name,
+			Abbrev: abbrev,
+			Offset: int32(offs),
+			Type:   obj.Linklookup(Ctxt, typename, 0),
+		})
 	}
 
-		fnsym.Autom = append(fnsym.Autom, a)
-	}
+	// Stable sort so that ties are broken with declaration order.
+	sort.Stable(dwarf.VarsByOffset(vars))
+
+	return vars
 }
 
 // fieldtrack adds R_USEFIELD relocations to fnsym to record any

src/cmd/internal/obj/link.go

@@ -32,6 +32,7 @@ package obj
 
 import (
 	"bufio"
+	"cmd/internal/dwarf"
 	"cmd/internal/src"
 	"cmd/internal/sys"
 	"fmt"
@@ -752,6 +753,7 @@ type Link struct {
 	Armsize       int32
 	Pc            int64
 	DiagFunc      func(string, ...interface{})
+	DebugInfo     func(fn *LSym) []*dwarf.Var
 	Mode          int
 	Cursym        *LSym
 	Version       int

src/cmd/internal/obj/objfile.go

@@ -551,54 +551,19 @@ func (c dwCtxt) AddSectionOffset(s dwarf.Sym, size int, t interface{}, ofs int64
 	r.Type = R_DWARFREF
 }
 
-func gendwarf(ctxt *Link, text []*LSym) []*LSym {
-	dctxt := dwCtxt{ctxt}
-	var dw []*LSym
-
-	for _, s := range text {
+// makeFuncDebugEntry makes a DWARF Debugging Information Entry
+// for TEXT symbol s.
+func makeFuncDebugEntry(ctxt *Link, s *LSym) {
 	dsym := Linklookup(ctxt, dwarf.InfoPrefix+s.Name, int(s.Version))
 	if dsym.Size != 0 {
-			continue
+		return
 	}
-		dw = append(dw, dsym)
 	dsym.Type = SDWARFINFO
 	dsym.Set(AttrDuplicateOK, s.DuplicateOK())
 	var vars []*dwarf.Var
-		var abbrev int
-		var offs int32
-		for _, a := range s.Autom {
-			switch a.Name {
-			case NAME_AUTO:
-				abbrev = dwarf.DW_ABRV_AUTO
-				offs = a.Aoffset
-				if ctxt.FixedFrameSize() == 0 {
-					offs -= int32(ctxt.Arch.PtrSize)
+	if ctxt.DebugInfo != nil {
+		vars = ctxt.DebugInfo(s)
 	}
-				if Framepointer_enabled(GOOS, GOARCH) {
-					offs -= int32(ctxt.Arch.PtrSize)
-				}
-
-			case NAME_PARAM:
-				abbrev = dwarf.DW_ABRV_PARAM
-				offs = a.Aoffset + int32(ctxt.FixedFrameSize())
-
-			default:
-				continue
-			}
-
-			typename := dwarf.InfoPrefix + a.Gotype.Name[len("type."):]
-			vars = append(vars, &dwarf.Var{
-				Name:   a.Asym.Name,
-				Abbrev: abbrev,
-				Offset: offs,
-				Type:   Linklookup(ctxt, typename, 0),
-			})
-		}
-
-		// Stable sort so that ties are broken with declaration order.
-		sort.Stable(dwarf.VarsByOffset(vars))
-
-		dwarf.PutFunc(dctxt, dsym, s.Name, s.Version == 0, s, s.Size, vars)
-	}
-	return dw
+	dwarf.PutFunc(dwCtxt{ctxt}, dsym, s.Name, s.Version == 0, s, s.Size, vars)
+	ctxt.Data = append(ctxt.Data, dsym)
 }

src/cmd/internal/obj/plist.go

@@ -128,6 +128,7 @@ func flushplist(ctxt *Link, plist *Plist, freeProgs bool) {
 		ctxt.Arch.Preprocess(ctxt, s)
 		ctxt.Arch.Assemble(ctxt, s)
 		linkpcln(ctxt, s)
+		makeFuncDebugEntry(ctxt, s)
 		if freeProgs {
 			s.Text = nil
 		}
@@ -135,7 +136,6 @@ func flushplist(ctxt *Link, plist *Plist, freeProgs bool) {
 
 	// Add to running list in ctxt.
 	ctxt.Text = append(ctxt.Text, text...)
-	ctxt.Data = append(ctxt.Data, gendwarf(ctxt, text)...)
 	ctxt.Curp = nil
 	if freeProgs {
 		ctxt.freeProgs()