cmd/compile/internal/gc: remove dead code

Found with https://github.com/remyoudompheng/go-misc/deadcode:

deadcode: walk.go:2228:1: applywritebarrier_bv is unused
deadcode: subr.go:355:1: gethunk is unused
deadcode: subr.go:1991:1: localexpr is unused
deadcode: dcl.go:82:1: poptodcl is unused
deadcode: swt.go:810:1: dumpcase is unused
deadcode: esc.go:251:1: satAdd8 is unused
deadcode: esc.go:387:1: outputsPerTag is unused
deadcode: obj.go:190:1: duint64 is unused
deadcode: obj.go:287:1: dstringptr is unused
deadcode: plive.go:95:1: xmalloc is unused
deadcode: plive.go:119:1: freeblock is unused

followed by

deadcode: go.go:633:1: hunk is unused
deadcode: go.go:635:1: nhunk is unused
deadcode: go.go:637:1: thunk is unused

after 'gethunk' was removed.

Some dead code in bv.go, mparith3.go, and dcl.go was left as is.

Passes go build -a -toolexec 'toolstash -cmp' std cmd.

Change-Id: Ia63519adedc8650d7095572ddd454fd923d3204d
Reviewed-on: https://go-review.googlesource.com/14610Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -79,16 +79,6 @@ func popdcl() {
 	block = d.Block
 }
 
-func poptodcl() {
-	// pop the old marker and push a new one
-	// (cannot reuse the existing one)
-	// because we use the markers to identify blocks
-	// for the goto restriction checks.
-	popdcl()
-
-	markdcl()
-}
-
 func markdcl() {
 	d := push()
 	d.Name = "" // used as a mark in fifo

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

@@ -248,17 +248,6 @@ func satInc8(x int8) int8 {
 	return x + 1
 }
 
-func satAdd8(x, y int8) int8 {
-	z := x + y
-	if x^y < 0 || x^z >= 0 {
-		return z
-	}
-	if x < 0 {
-		return -128
-	}
-	return 127
-}
-
 func min8(a, b int8) int8 {
 	if a < b {
 		return a
@@ -385,10 +374,9 @@ func escMax(e, etype uint16) uint16 {
 // something whose address is returned -- but that implies stored into the heap,
 // hence EscHeap, which means that the details are not currently relevant. )
 const (
-	bitsPerOutputInTag = 3                                         // For each output, the number of bits for a tag
-	bitsMaskForTag     = uint16(1<<bitsPerOutputInTag) - 1         // The bit mask to extract a single tag.
-	outputsPerTag      = (16 - EscReturnBits) / bitsPerOutputInTag // The number of outputs that can be tagged.
-	maxEncodedLevel    = int(bitsMaskForTag - 1)                   // The largest level that can be stored in a tag.
+	bitsPerOutputInTag = 3                                 // For each output, the number of bits for a tag
+	bitsMaskForTag     = uint16(1<<bitsPerOutputInTag) - 1 // The bit mask to extract a single tag.
+	maxEncodedLevel    = int(bitsMaskForTag - 1)           // The largest level that can be stored in a tag.
 )
 
 type EscState struct {

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

@@ -630,12 +630,6 @@ var typesw *Node
 
 var nblank *Node
 
-var hunk string
-
-var nhunk int32
-
-var thunk int32
-
 var Funcdepth int32
 
 var typecheckok bool

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

@@ -187,10 +187,6 @@ func duint32(s *Sym, off int, v uint32) int {
 	return duintxx(s, off, uint64(v), 4)
 }
 
-func duint64(s *Sym, off int, v uint64) int {
-	return duintxx(s, off, v, 8)
-}
-
 func duintptr(s *Sym, off int, v uint64) int {
 	return duintxx(s, off, v, Widthptr)
 }
@@ -284,25 +280,6 @@ func slicebytes(nam *Node, s string, len int) {
 	duintxx(nam.Sym, off, uint64(len), Widthint)
 }
 
-func dstringptr(s *Sym, off int, str string) int {
-	off = int(Rnd(int64(off), int64(Widthptr)))
-	p := Thearch.Gins(obj.ADATA, nil, nil)
-	p.From.Type = obj.TYPE_MEM
-	p.From.Name = obj.NAME_EXTERN
-	p.From.Sym = Linksym(s)
-	p.From.Offset = int64(off)
-	p.From3 = new(obj.Addr)
-	p.From3.Type = obj.TYPE_CONST
-	p.From3.Offset = int64(Widthptr)
-
-	Datastring(str+"\x00", &p.To) // TODO(rsc): Remove NUL
-	p.To.Type = obj.TYPE_ADDR
-	p.To.Etype = Simtype[TINT]
-	off += Widthptr
-
-	return off
-}
-
 func Datastring(s string, a *obj.Addr) {
 	_, symdata := stringsym(s)
 	a.Type = obj.TYPE_MEM

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

@@ -92,14 +92,6 @@ type Liveness struct {
 	livepointers     []Bvec
 }
 
-func xmalloc(size uint32) interface{} {
-	result := (interface{})(make([]byte, size))
-	if result == nil {
-		Fatalf("malloc failed")
-	}
-	return result
-}
-
 // Constructs a new basic block containing a single instruction.
 func newblock(prog *obj.Prog) *BasicBlock {
 	if prog == nil {
@@ -115,13 +107,6 @@ func newblock(prog *obj.Prog) *BasicBlock {
 	return result
 }
 
-// Frees a basic block and all of its leaf data structures.
-func freeblock(bb *BasicBlock) {
-	if bb == nil {
-		Fatalf("freeblock: cannot free nil")
-	}
-}
-
 // Adds an edge between two basic blocks by making from a predecessor of to and
 // to a successor of from.
 func addedge(from *BasicBlock, to *BasicBlock) {

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

@@ -347,23 +347,6 @@ func importdot(opkg *Pkg, pack *Node) {
 	}
 }
 
-func gethunk() {
-	nh := int32(NHUNK)
-	if thunk >= 10*NHUNK {
-		nh = 10 * NHUNK
-	}
-	h := string(make([]byte, nh))
-	if h == "" {
-		Flusherrors()
-		Yyerror("out of memory")
-		errorexit()
-	}
-
-	hunk = h
-	nhunk = nh
-	thunk += nh
-}
-
 func Nod(op int, nleft *Node, nright *Node) *Node {
 	n := new(Node)
 	n.Op = uint8(op)
@@ -1966,19 +1949,6 @@ func cheapexpr(n *Node, init **NodeList) *Node {
 	return copyexpr(n, n.Type, init)
 }
 
-/*
- * return n in a local variable of type t if it is not already.
- * the value is guaranteed not to change except by direct
- * assignment to it.
- */
-func localexpr(n *Node, t *Type, init **NodeList) *Node {
-	if n.Op == ONAME && (!n.Addrtaken || strings.HasPrefix(n.Sym.Name, "autotmp_")) && (n.Class == PAUTO || n.Class == PPARAM || n.Class == PPARAMOUT) && convertop(n.Type, t, nil) == OCONVNOP {
-		return n
-	}
-
-	return copyexpr(n, t, init)
-}
-
 func Setmaxarg(t *Type, extra int32) {
 	dowidth(t)
 	w := t.Argwid

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

@@ -6,7 +6,6 @@ package gc
 
 import (
 	"cmd/internal/obj"
-	"fmt"
 	"sort"
 	"strconv"
 )
@@ -806,43 +805,3 @@ func (x caseClauseByType) Less(i, j int) bool {
 	// sort by ordinal
 	return c1.ordinal < c2.ordinal
 }
-
-func dumpcase(cc []*caseClause) {
-	for _, c := range cc {
-		switch c.typ {
-		case caseKindDefault:
-			fmt.Printf("case-default\n")
-			fmt.Printf("\tord=%d\n", c.ordinal)
-
-		case caseKindExprConst:
-			fmt.Printf("case-exprconst\n")
-			fmt.Printf("\tord=%d\n", c.ordinal)
-
-		case caseKindExprVar:
-			fmt.Printf("case-exprvar\n")
-			fmt.Printf("\tord=%d\n", c.ordinal)
-			fmt.Printf("\top=%v\n", Oconv(int(c.node.Left.Op), 0))
-
-		case caseKindTypeNil:
-			fmt.Printf("case-typenil\n")
-			fmt.Printf("\tord=%d\n", c.ordinal)
-
-		case caseKindTypeConst:
-			fmt.Printf("case-typeconst\n")
-			fmt.Printf("\tord=%d\n", c.ordinal)
-			fmt.Printf("\thash=%x\n", c.hash)
-
-		case caseKindTypeVar:
-			fmt.Printf("case-typevar\n")
-			fmt.Printf("\tord=%d\n", c.ordinal)
-
-		default:
-			fmt.Printf("case-???\n")
-			fmt.Printf("\tord=%d\n", c.ordinal)
-			fmt.Printf("\top=%v\n", Oconv(int(c.node.Left.Op), 0))
-			fmt.Printf("\thash=%x\n", c.hash)
-		}
-	}
-
-	fmt.Printf("\n")
-}

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

@@ -2225,8 +2225,6 @@ func needwritebarrier(l *Node, r *Node) bool {
 
 // TODO(rsc): Perhaps componentgen should run before this.
 
-var applywritebarrier_bv Bvec
-
 func applywritebarrier(n *Node, init **NodeList) *Node {
 	if n.Left != nil && n.Right != nil && needwritebarrier(n.Left, n.Right) {
 		if Debug_wb > 1 {