cmd/compile, cmd/asm: remove Link.Plists

Link.Plists never contained more than one Plist, and sometimes none.
Passing around the Plist being worked on is straightforward and makes
the data flow easier to follow.

Change-Id: I79cb30cb2bd3d319fdbb1dfa5d35b27fcb748e5c
Reviewed-on: https://go-review.googlesource.com/37169
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/asm/internal/asm/endtoend_test.go

@@ -30,7 +30,7 @@ func testEndToEnd(t *testing.T, goarch, file string) {
 	architecture, ctxt := setArch(goarch)
 	lexer := lex.NewLexer(input)
 	parser := NewParser(ctxt, architecture, lexer)
-	pList := obj.Linknewplist(ctxt)
+	pList := new(obj.Plist)
 	var ok bool
 	testOut = new(bytes.Buffer) // The assembler writes test output to this buffer.
 	ctxt.Bso = bufio.NewWriter(os.Stdout)
@@ -179,7 +179,7 @@ Diff:
 		t.Errorf(format, args...)
 		ok = false
 	}
-	obj.FlushplistNoFree(ctxt)
+	obj.FlushplistNoFree(ctxt, pList)
 
 	for p := top; p != nil; p = p.Link {
 		if p.As == obj.ATEXT {
@@ -267,7 +267,7 @@ func testErrors(t *testing.T, goarch, file string) {
 	architecture, ctxt := setArch(goarch)
 	lexer := lex.NewLexer(input)
 	parser := NewParser(ctxt, architecture, lexer)
-	pList := obj.Linknewplist(ctxt)
+	pList := new(obj.Plist)
 	var ok bool
 	testOut = new(bytes.Buffer) // The assembler writes test output to this buffer.
 	ctxt.Bso = bufio.NewWriter(os.Stdout)
@@ -283,7 +283,7 @@ func testErrors(t *testing.T, goarch, file string) {
 		errBuf.WriteString(s)
 	}
 	pList.Firstpc, ok = parser.Parse()
-	obj.Flushplist(ctxt)
+	obj.Flushplist(ctxt, pList)
 	if ok && !failed {
 		t.Errorf("asm: %s had no errors", goarch)
 	}

src/cmd/asm/main.go

@@ -62,16 +62,17 @@ func main() {
 			diag = true
 			log.Printf(format, args...)
 		}
-		pList := obj.Linknewplist(ctxt)
+		pList := new(obj.Plist)
 		pList.Firstpc, ok = parser.Parse()
 		if !ok {
 			failedFile = f
 			break
 		}
+		// reports errors to parser.Errorf
+		obj.Flushplist(ctxt, pList)
 	}
 	if ok {
-		// reports errors to parser.Errorf
-		obj.Writeobjdirect(ctxt, buf)
+		obj.WriteObjFile(ctxt, buf)
 	}
 	if !ok || diag {
 		if failedFile != "" {

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

@@ -5,7 +5,6 @@
 package gc
 
 import (
-	"cmd/internal/obj"
 	"cmd/internal/src"
 	"fmt"
 	"sort"
@@ -1228,11 +1227,6 @@ func funccompile(n *Node) {
 	pc = nil
 	funcdepth = 0
 	dclcontext = PEXTERN
-	if nerrors != 0 {
-		// If we have compile errors, ignore any assembler/linker errors.
-		Ctxt.DiagFunc = func(string, ...interface{}) {}
-	}
-	obj.Flushplist(Ctxt) // convert from Prog list to machine code
 }
 
 func funcsym(s *Sym) *Sym {

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

@@ -161,16 +161,6 @@ func Addrconst(a *obj.Addr, v int64) {
 	a.Offset = v
 }
 
-func newplist() *obj.Plist {
-	pl := obj.Linknewplist(Ctxt)
-
-	pc = Ctxt.NewProg()
-	Clearp(pc)
-	pl.Firstpc = pc
-
-	return pl
-}
-
 // nodarg returns a Node for the function argument denoted by t,
 // which is either the entire function argument or result struct (t is a  struct *Type)
 // or a specific argument (t is a *Field within a struct *Type).

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

@@ -151,7 +151,7 @@ func dumpobj1(outfile string, mode int) {
 		ggloblsym(zero, int32(zerosize), obj.DUPOK|obj.RODATA)
 	}
 
-	obj.Writeobjdirect(Ctxt, bout.Writer)
+	obj.WriteObjFile(Ctxt, bout.Writer)
 
 	if writearchive {
 		bout.Flush()

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

@@ -368,7 +368,10 @@ func compile(fn *Node) {
 		return
 	}
 
-	newplist()
+	plist := new(obj.Plist)
+	pc = Ctxt.NewProg()
+	Clearp(pc)
+	plist.Firstpc = pc
 
 	setlineno(Curfn)
 
@@ -430,6 +433,7 @@ func compile(fn *Node) {
 
 	genssa(ssafn, ptxt, gcargs, gclocals)
 	ssafn.Free()
+	obj.Flushplist(Ctxt, plist) // convert from Prog list to machine code
 }
 
 func gendebug(fn *obj.LSym, decls []*Node) {

src/cmd/internal/obj/link.go

@@ -729,7 +729,6 @@ type Link struct {
 	Hash          map[SymVer]*LSym
 	PosTable      src.PosTable
 	Imports       []string
-	Plists        []*Plist
 	Sym_div       *LSym
 	Sym_divu      *LSym
 	Sym_mod       *LSym

src/cmd/internal/obj/objfile.go

@@ -119,14 +119,6 @@ import (
 	"sort"
 )
 
-// The Go and C compilers, and the assembler, call writeobj to write
-// out a Go object file. The linker does not call this; the linker
-// does not write out object files.
-func Writeobjdirect(ctxt *Link, b *bufio.Writer) {
-	Flushplist(ctxt)
-	WriteObjFile(ctxt, b)
-}
-
 // objWriter writes Go object files.
 type objWriter struct {
 	wr   *bufio.Writer

src/cmd/internal/obj/plist.go

@@ -14,96 +14,83 @@ type Plist struct {
 	Firstpc *Prog
 }
 
-/*
- * start a new Prog list.
- */
-func Linknewplist(ctxt *Link) *Plist {
-	pl := new(Plist)
-	ctxt.Plists = append(ctxt.Plists, pl)
-	return pl
+func Flushplist(ctxt *Link, plist *Plist) {
+	flushplist(ctxt, plist, ctxt.Debugasm == 0)
 }
-
-func Flushplist(ctxt *Link) {
-	flushplist(ctxt, ctxt.Debugasm == 0)
-}
-func FlushplistNoFree(ctxt *Link) {
-	flushplist(ctxt, false)
+func FlushplistNoFree(ctxt *Link, plist *Plist) {
+	flushplist(ctxt, plist, false)
 }
-func flushplist(ctxt *Link, freeProgs bool) {
+func flushplist(ctxt *Link, plist *Plist, freeProgs bool) {
 	// Build list of symbols, and assign instructions to lists.
-	// Ignore ctxt->plist boundaries. There are no guarantees there,
-	// and the assemblers just use one big list.
 	var curtext *LSym
 	var etext *Prog
 	var text []*LSym
 
-	for _, pl := range ctxt.Plists {
-		var plink *Prog
-		for p := pl.Firstpc; p != nil; p = plink {
-			if ctxt.Debugasm != 0 && ctxt.Debugvlog != 0 {
-				fmt.Printf("obj: %v\n", p)
-			}
-			plink = p.Link
-			p.Link = nil
-
-			switch p.As {
-			case AEND:
-				continue
+	var plink *Prog
+	for p := plist.Firstpc; p != nil; p = plink {
+		if ctxt.Debugasm != 0 && ctxt.Debugvlog != 0 {
+			fmt.Printf("obj: %v\n", p)
+		}
+		plink = p.Link
+		p.Link = nil
 
-			case ATEXT:
-				s := p.From.Sym
-				if s == nil {
-					// func _() { }
-					curtext = nil
+		switch p.As {
+		case AEND:
+			continue
 
-					continue
-				}
+		case ATEXT:
+			s := p.From.Sym
+			if s == nil {
+				// func _() { }
+				curtext = nil
 
-				if s.Text != nil {
-					log.Fatalf("duplicate TEXT for %s", s.Name)
-				}
-				if s.OnList() {
-					log.Fatalf("symbol %s listed multiple times", s.Name)
-				}
-				s.Set(AttrOnList, true)
-				text = append(text, s)
-				flag := int(p.From3Offset())
-				if flag&DUPOK != 0 {
-					s.Set(AttrDuplicateOK, true)
-				}
-				if flag&NOSPLIT != 0 {
-					s.Set(AttrNoSplit, true)
-				}
-				if flag&REFLECTMETHOD != 0 {
-					s.Set(AttrReflectMethod, true)
-				}
-				s.Type = STEXT
-				s.Text = p
-				etext = p
-				curtext = s
 				continue
+			}
 
-			case AFUNCDATA:
-				// Rewrite reference to go_args_stackmap(SB) to the Go-provided declaration information.
-				if curtext == nil { // func _() {}
-					continue
-				}
-				if p.To.Sym.Name == "go_args_stackmap" {
-					if p.From.Type != TYPE_CONST || p.From.Offset != FUNCDATA_ArgsPointerMaps {
-						ctxt.Diag("FUNCDATA use of go_args_stackmap(SB) without FUNCDATA_ArgsPointerMaps")
-					}
-					p.To.Sym = Linklookup(ctxt, fmt.Sprintf("%s.args_stackmap", curtext.Name), int(curtext.Version))
-				}
-
+			if s.Text != nil {
+				log.Fatalf("duplicate TEXT for %s", s.Name)
+			}
+			if s.OnList() {
+				log.Fatalf("symbol %s listed multiple times", s.Name)
+			}
+			s.Set(AttrOnList, true)
+			text = append(text, s)
+			flag := int(p.From3Offset())
+			if flag&DUPOK != 0 {
+				s.Set(AttrDuplicateOK, true)
 			}
+			if flag&NOSPLIT != 0 {
+				s.Set(AttrNoSplit, true)
+			}
+			if flag&REFLECTMETHOD != 0 {
+				s.Set(AttrReflectMethod, true)
+			}
+			s.Type = STEXT
+			s.Text = p
+			etext = p
+			curtext = s
+			continue
 
-			if curtext == nil {
-				etext = nil
+		case AFUNCDATA:
+			// Rewrite reference to go_args_stackmap(SB) to the Go-provided declaration information.
+			if curtext == nil { // func _() {}
 				continue
 			}
-			etext.Link = p
-			etext = p
+			if p.To.Sym.Name == "go_args_stackmap" {
+				if p.From.Type != TYPE_CONST || p.From.Offset != FUNCDATA_ArgsPointerMaps {
+					ctxt.Diag("FUNCDATA use of go_args_stackmap(SB) without FUNCDATA_ArgsPointerMaps")
+				}
+				p.To.Sym = Linklookup(ctxt, fmt.Sprintf("%s.args_stackmap", curtext.Name), int(curtext.Version))
+			}
+
+		}
+
+		if curtext == nil {
+			etext = nil
+			continue
 		}
+		etext.Link = p
+		etext = p
 	}
 
 	// Add reference to Go arguments for C or assembly functions without them.
@@ -147,7 +134,6 @@ func flushplist(ctxt *Link, freeProgs bool) {
 	// Add to running list in ctxt.
 	ctxt.Text = append(ctxt.Text, text...)
 	ctxt.Data = append(ctxt.Data, gendwarf(ctxt, text)...)
-	ctxt.Plists = nil
 	ctxt.Curp = nil
 	if freeProgs {
 		ctxt.freeProgs()