cmd/compile: remove OFORUNTIL

Not used any more.

Fixes #53860

Change-Id: Id0b1c3ed30b576d6c5f08f064d1262de337262b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/418374
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/compile/internal/escape/stmt.go

@@ -78,7 +78,7 @@ func (e *escape) stmt(n ir.Node) {
 		n := n.(*ir.UnaryExpr)
 		e.discard(n.X)
 
-	case ir.OFOR, ir.OFORUNTIL:
+	case ir.OFOR:
 		n := n.(*ir.ForStmt)
 		e.loopDepth++
 		e.discard(n.Cond)

src/cmd/compile/internal/ir/fmt.go

@@ -50,7 +50,6 @@ var OpNames = []string{
 	OEQ:          "==",
 	OFALL:        "fallthrough",
 	OFOR:         "for",
-	OFORUNTIL:    "foruntil", // not actual syntax; used to avoid off-end pointer live on backedge.892
 	OGE:          ">=",
 	OGOTO:        "goto",
 	OGT:          ">",
@@ -274,7 +273,6 @@ var OpPrec = []int{
 	ODEFER:      -1,
 	OFALL:       -1,
 	OFOR:        -1,
-	OFORUNTIL:   -1,
 	OGOTO:       -1,
 	OIF:         -1,
 	OLABEL:      -1,
@@ -290,7 +288,7 @@ var OpPrec = []int{
 // StmtWithInit reports whether op is a statement with an explicit init list.
 func StmtWithInit(op Op) bool {
 	switch op {
-	case OIF, OFOR, OFORUNTIL, OSWITCH:
+	case OIF, OFOR, OSWITCH:
 		return true
 	}
 	return false
@@ -401,18 +399,14 @@ func stmtFmt(n Node, s fmt.State) {
 			fmt.Fprintf(s, " else { %v }", n.Else)
 		}
 
-	case OFOR, OFORUNTIL:
+	case OFOR:
 		n := n.(*ForStmt)
-		opname := "for"
-		if n.Op() == OFORUNTIL {
-			opname = "foruntil"
-		}
 		if !exportFormat { // TODO maybe only if FmtShort, same below
-			fmt.Fprintf(s, "%s loop", opname)
+			fmt.Fprintf(s, "for loop")
 			break
 		}
 
-		fmt.Fprint(s, opname)
+		fmt.Fprint(s, "for")
 		if simpleinit {
 			fmt.Fprintf(s, " %v;", n.Init()[0])
 		} else if n.Post != nil {
@@ -429,10 +423,6 @@ func stmtFmt(n Node, s fmt.State) {
 			fmt.Fprint(s, ";")
 		}
 
-		if n.Op() == OFORUNTIL && len(n.Late) != 0 {
-			fmt.Fprintf(s, "; %v", n.Late)
-		}
-
 		fmt.Fprintf(s, " { %v }", n.Body)
 
 	case ORANGE:

src/cmd/compile/internal/ir/node.go

@@ -263,24 +263,14 @@ const (
 	ODEFER    // defer Call
 	OFALL     // fallthrough
 	OFOR      // for Init; Cond; Post { Body }
-	// OFORUNTIL is like OFOR, but the test (Cond) is applied after the body:
+	OGOTO     // goto Label
-	// 	Init
+	OIF       // if Init; Cond { Then } else { Else }
-	// 	top: { Body }   // Execute the body at least once
+	OLABEL    // Label:
-	// 	cont: Post
+	OGO       // go Call
-	// 	if Cond {        // And then test the loop condition
+	ORANGE    // for Key, Value = range X { Body }
-	// 		List     // Before looping to top, execute List
+	ORETURN   // return Results
-	// 		goto top
+	OSELECT   // select { Cases }
-	// 	}
+	OSWITCH   // switch Init; Expr { Cases }
-	// OFORUNTIL is created by walk. There's no way to write this in Go code.
-	OFORUNTIL
-	OGOTO   // goto Label
-	OIF     // if Init; Cond { Then } else { Else }
-	OLABEL  // Label:
-	OGO     // go Call
-	ORANGE  // for Key, Value = range X { Body }
-	ORETURN // return Results
-	OSELECT // select { Cases }
-	OSWITCH // switch Init; Expr { Cases }
 	// OTYPESW:  X := Y.(type) (appears as .Tag of OSWITCH)
 	//   X is nil if there is no type-switch variable
 	OTYPESW

src/cmd/compile/internal/ir/node_gen.go

@@ -483,7 +483,6 @@ func (n *ForStmt) Format(s fmt.State, verb rune) { fmtNode(n, s, verb) }
 func (n *ForStmt) copy() Node {
 	c := *n
 	c.init = copyNodes(c.init)
-	c.Late = copyNodes(c.Late)
 	c.Body = copyNodes(c.Body)
 	return &c
 }
@@ -494,9 +493,6 @@ func (n *ForStmt) doChildren(do func(Node) bool) bool {
 	if n.Cond != nil && do(n.Cond) {
 		return true
 	}
-	if doNodes(n.Late, do) {
-		return true
-	}
 	if n.Post != nil && do(n.Post) {
 		return true
 	}
@@ -510,7 +506,6 @@ func (n *ForStmt) editChildren(edit func(Node) Node) {
 	if n.Cond != nil {
 		n.Cond = edit(n.Cond).(Node)
 	}
-	editNodes(n.Late, edit)
 	if n.Post != nil {
 		n.Post = edit(n.Post).(Node)
 	}

src/cmd/compile/internal/ir/op_string.go

@@ -129,44 +129,43 @@ func _() {
 	_ = x[ODEFER-118]
 	_ = x[OFALL-119]
 	_ = x[OFOR-120]
-	_ = x[OFORUNTIL-121]
+	_ = x[OGOTO-121]
-	_ = x[OGOTO-122]
+	_ = x[OIF-122]
-	_ = x[OIF-123]
+	_ = x[OLABEL-123]
-	_ = x[OLABEL-124]
+	_ = x[OGO-124]
-	_ = x[OGO-125]
+	_ = x[ORANGE-125]
-	_ = x[ORANGE-126]
+	_ = x[ORETURN-126]
-	_ = x[ORETURN-127]
+	_ = x[OSELECT-127]
-	_ = x[OSELECT-128]
+	_ = x[OSWITCH-128]
-	_ = x[OSWITCH-129]
+	_ = x[OTYPESW-129]
-	_ = x[OTYPESW-130]
+	_ = x[OFUNCINST-130]
-	_ = x[OFUNCINST-131]
+	_ = x[OINLCALL-131]
-	_ = x[OINLCALL-132]
+	_ = x[OEFACE-132]
-	_ = x[OEFACE-133]
+	_ = x[OITAB-133]
-	_ = x[OITAB-134]
+	_ = x[OIDATA-134]
-	_ = x[OIDATA-135]
+	_ = x[OSPTR-135]
-	_ = x[OSPTR-136]
+	_ = x[OCFUNC-136]
-	_ = x[OCFUNC-137]
+	_ = x[OCHECKNIL-137]
-	_ = x[OCHECKNIL-138]
+	_ = x[OVARDEF-138]
-	_ = x[OVARDEF-139]
+	_ = x[OVARKILL-139]
-	_ = x[OVARKILL-140]
+	_ = x[OVARLIVE-140]
-	_ = x[OVARLIVE-141]
+	_ = x[ORESULT-141]
-	_ = x[ORESULT-142]
+	_ = x[OINLMARK-142]
-	_ = x[OINLMARK-143]
+	_ = x[OLINKSYMOFFSET-143]
-	_ = x[OLINKSYMOFFSET-144]
+	_ = x[OJUMPTABLE-144]
-	_ = x[OJUMPTABLE-145]
+	_ = x[ODYNAMICDOTTYPE-145]
-	_ = x[ODYNAMICDOTTYPE-146]
+	_ = x[ODYNAMICDOTTYPE2-146]
-	_ = x[ODYNAMICDOTTYPE2-147]
+	_ = x[ODYNAMICTYPE-147]
-	_ = x[ODYNAMICTYPE-148]
+	_ = x[OTAILCALL-148]
-	_ = x[OTAILCALL-149]
+	_ = x[OGETG-149]
-	_ = x[OGETG-150]
+	_ = x[OGETCALLERPC-150]
-	_ = x[OGETCALLERPC-151]
+	_ = x[OGETCALLERSP-151]
-	_ = x[OGETCALLERSP-152]
+	_ = x[OEND-152]
-	_ = x[OEND-153]
 }
 
-const _Op_name = "XXXNAMENONAMETYPELITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESSLICE2ARRPTRASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVIDATACONVNOPCOPYDCLDCLFUNCDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECOVERFPRECVRUNESTRSELRECV2REALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFUNSAFEADDUNSAFESLICEMETHEXPRMETHVALUEBLOCKBREAKCASECONTINUEDEFERFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWFUNCINSTINLCALLEFACEITABIDATASPTRCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKLINKSYMOFFSETJUMPTABLEDYNAMICDOTTYPEDYNAMICDOTTYPE2DYNAMICTYPETAILCALLGETGGETCALLERPCGETCALLERSPEND"
+const _Op_name = "XXXNAMENONAMETYPELITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESSLICE2ARRPTRASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVIDATACONVNOPCOPYDCLDCLFUNCDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECOVERFPRECVRUNESTRSELRECV2REALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFUNSAFEADDUNSAFESLICEMETHEXPRMETHVALUEBLOCKBREAKCASECONTINUEDEFERFALLFORGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWFUNCINSTINLCALLEFACEITABIDATASPTRCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKLINKSYMOFFSETJUMPTABLEDYNAMICDOTTYPEDYNAMICDOTTYPE2DYNAMICTYPETAILCALLGETGGETCALLERPCGETCALLERSPEND"
 
-var _Op_index = [...]uint16{0, 3, 7, 13, 17, 24, 27, 30, 33, 35, 38, 44, 48, 54, 60, 69, 81, 90, 99, 111, 120, 132, 134, 137, 147, 154, 161, 168, 172, 176, 184, 192, 201, 204, 209, 216, 223, 229, 238, 246, 254, 260, 264, 273, 282, 289, 293, 296, 303, 311, 318, 324, 327, 333, 340, 348, 352, 359, 367, 369, 371, 373, 375, 377, 379, 384, 389, 397, 400, 409, 412, 416, 424, 431, 440, 453, 456, 459, 462, 465, 468, 471, 477, 480, 483, 489, 493, 496, 500, 505, 510, 516, 521, 525, 530, 538, 546, 552, 561, 572, 579, 588, 592, 599, 607, 611, 615, 622, 629, 637, 643, 652, 663, 671, 680, 685, 690, 694, 702, 707, 711, 714, 722, 726, 728, 733, 735, 740, 746, 752, 758, 764, 772, 779, 784, 788, 793, 797, 802, 810, 816, 823, 830, 836, 843, 856, 865, 879, 894, 905, 913, 917, 928, 939, 942}
+var _Op_index = [...]uint16{0, 3, 7, 13, 17, 24, 27, 30, 33, 35, 38, 44, 48, 54, 60, 69, 81, 90, 99, 111, 120, 132, 134, 137, 147, 154, 161, 168, 172, 176, 184, 192, 201, 204, 209, 216, 223, 229, 238, 246, 254, 260, 264, 273, 282, 289, 293, 296, 303, 311, 318, 324, 327, 333, 340, 348, 352, 359, 367, 369, 371, 373, 375, 377, 379, 384, 389, 397, 400, 409, 412, 416, 424, 431, 440, 453, 456, 459, 462, 465, 468, 471, 477, 480, 483, 489, 493, 496, 500, 505, 510, 516, 521, 525, 530, 538, 546, 552, 561, 572, 579, 588, 592, 599, 607, 611, 615, 622, 629, 637, 643, 652, 663, 671, 680, 685, 690, 694, 702, 707, 711, 714, 718, 720, 725, 727, 732, 738, 744, 750, 756, 764, 771, 776, 780, 785, 789, 794, 802, 808, 815, 822, 828, 835, 848, 857, 871, 886, 897, 905, 909, 920, 931, 934}
 
 func (i Op) String() string {
 	if i >= Op(len(_Op_index)-1) {

src/cmd/compile/internal/ir/stmt.go

@@ -205,12 +205,10 @@ func NewCommStmt(pos src.XPos, comm Node, body []Node) *CommClause {
 }
 
 // A ForStmt is a non-range for loop: for Init; Cond; Post { Body }
-// Op can be OFOR or OFORUNTIL (!Cond).
 type ForStmt struct {
 	miniStmt
 	Label    *types.Sym
 	Cond     Node
-	Late     Nodes
 	Post     Node
 	Body     Nodes
 	HasBreak bool
@@ -227,13 +225,6 @@ func NewForStmt(pos src.XPos, init Node, cond, post Node, body []Node) *ForStmt
 	return n
 }
 
-func (n *ForStmt) SetOp(op Op) {
-	if op != OFOR && op != OFORUNTIL {
-		panic(n.no("SetOp " + op.String()))
-	}
-	n.op = op
-}
-
 // A GoDeferStmt is a go or defer statement: go Call / defer Call.
 //
 // The two opcodes use a single syntax because the implementations

src/cmd/compile/internal/ssa/prove.go

@@ -1099,8 +1099,7 @@ func addRestrictions(parent *Block, ft *factsTable, t domain, v, w *Value, r rel
 // addLocalInductiveFacts adds inductive facts when visiting b, where
 // b is a join point in a loop. In contrast with findIndVar, this
 // depends on facts established for b, which is why it happens when
-// visiting b. addLocalInductiveFacts specifically targets the pattern
+// visiting b.
-// created by OFORUNTIL, which isn't detected by findIndVar.
 //
 // TODO: It would be nice to combine this with findIndVar.
 func addLocalInductiveFacts(ft *factsTable, b *Block) {

src/cmd/compile/internal/ssagen/ssa.go

@@ -1738,12 +1738,9 @@ func (s *state) stmt(n ir.Node) {
 		b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
 		b.AddEdgeTo(to)
 
-	case ir.OFOR, ir.OFORUNTIL:
+	case ir.OFOR:
 		// OFOR: for Ninit; Left; Right { Nbody }
 		// cond (Left); body (Nbody); incr (Right)
-		//
-		// OFORUNTIL: for Ninit; Left; Right; List { Nbody }
-		// => body: { Nbody }; incr: Right; if Left { lateincr: List; goto body }; end:
 		n := n.(*ir.ForStmt)
 		bCond := s.f.NewBlock(ssa.BlockPlain)
 		bBody := s.f.NewBlock(ssa.BlockPlain)
@@ -1753,21 +1750,17 @@ func (s *state) stmt(n ir.Node) {
 		// ensure empty for loops have correct position; issue #30167
 		bBody.Pos = n.Pos()
 
-		// first, jump to condition test (OFOR) or body (OFORUNTIL)
+		// first, jump to condition test
 		b := s.endBlock()
-		if n.Op() == ir.OFOR {
+		b.AddEdgeTo(bCond)
-			b.AddEdgeTo(bCond)
-			// generate code to test condition
-			s.startBlock(bCond)
-			if n.Cond != nil {
-				s.condBranch(n.Cond, bBody, bEnd, 1)
-			} else {
-				b := s.endBlock()
-				b.Kind = ssa.BlockPlain
-				b.AddEdgeTo(bBody)
-			}
 
+		// generate code to test condition
+		s.startBlock(bCond)
+		if n.Cond != nil {
+			s.condBranch(n.Cond, bBody, bEnd, 1)
 		} else {
+			b := s.endBlock()
+			b.Kind = ssa.BlockPlain
 			b.AddEdgeTo(bBody)
 		}
 
@@ -1801,29 +1794,18 @@ func (s *state) stmt(n ir.Node) {
 			b.AddEdgeTo(bIncr)
 		}
 
-		// generate incr (and, for OFORUNTIL, condition)
+		// generate incr
 		s.startBlock(bIncr)
 		if n.Post != nil {
 			s.stmt(n.Post)
 		}
-		if n.Op() == ir.OFOR {
+		if b := s.endBlock(); b != nil {
-			if b := s.endBlock(); b != nil {
+			b.AddEdgeTo(bCond)
-				b.AddEdgeTo(bCond)
+			// It can happen that bIncr ends in a block containing only VARKILL,
-				// It can happen that bIncr ends in a block containing only VARKILL,
+			// and that muddles the debugging experience.
-				// and that muddles the debugging experience.
+			if b.Pos == src.NoXPos {
-				if b.Pos == src.NoXPos {
+				b.Pos = bCond.Pos
-					b.Pos = bCond.Pos
-				}
 			}
-		} else {
-			// bCond is unused in OFORUNTIL, so repurpose it.
-			bLateIncr := bCond
-			// test condition
-			s.condBranch(n.Cond, bLateIncr, bEnd, 1)
-			// generate late increment
-			s.startBlock(bLateIncr)
-			s.stmtList(n.Late)
-			s.endBlock().AddEdgeTo(bBody)
 		}
 
 		s.startBlock(bEnd)

src/cmd/compile/internal/typecheck/stmt.go

@@ -258,9 +258,6 @@ func tcFor(n *ir.ForStmt) ir.Node {
 		}
 	}
 	n.Post = Stmt(n.Post)
-	if n.Op() == ir.OFORUNTIL {
-		Stmts(n.Late)
-	}
 	Stmts(n.Body)
 	return n
 }

src/cmd/compile/internal/typecheck/typecheck.go

@@ -774,7 +774,7 @@ func typecheck1(n ir.Node, top int) ir.Node {
 		tcGoDefer(n)
 		return n
 
-	case ir.OFOR, ir.OFORUNTIL:
+	case ir.OFOR:
 		n := n.(*ir.ForStmt)
 		return tcFor(n)
 
@@ -1697,7 +1697,7 @@ func markBreak(fn *ir.Func) {
 				setHasBreak(labels[n.Label])
 			}
 
-		case ir.OFOR, ir.OFORUNTIL, ir.OSWITCH, ir.OSELECT, ir.ORANGE:
+		case ir.OFOR, ir.OSWITCH, ir.OSELECT, ir.ORANGE:
 			old := implicit
 			implicit = n
 			var sym *types.Sym
@@ -1773,7 +1773,7 @@ func isTermNode(n ir.Node) bool {
 	case ir.OGOTO, ir.ORETURN, ir.OTAILCALL, ir.OPANIC, ir.OFALL:
 		return true
 
-	case ir.OFOR, ir.OFORUNTIL:
+	case ir.OFOR:
 		n := n.(*ir.ForStmt)
 		if n.Cond != nil {
 			return false

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

@@ -123,19 +123,6 @@ func walkRange(nrange *ir.RangeStmt) ir.Node {
 			break
 		}
 
-		// TODO(austin): OFORUNTIL is a strange beast, but is
-		// necessary for expressing the control flow we need
-		// while also making "break" and "continue" work. It
-		// would be nice to just lower ORANGE during SSA, but
-		// racewalk needs to see many of the operations
-		// involved in ORANGE's implementation. If racewalk
-		// moves into SSA, consider moving ORANGE into SSA and
-		// eliminating OFORUNTIL.
-
-		// TODO(austin): OFORUNTIL inhibits bounds-check
-		// elimination on the index variable (see #20711).
-		// Enhance the prove pass to understand this.
-
 		// Slice to iterate over
 		var hs ir.Node
 		if t.IsSlice() {

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

@@ -124,7 +124,7 @@ func walkStmt(n ir.Node) ir.Node {
 		n := n.(*ir.GoDeferStmt)
 		return walkGoDefer(n)
 
-	case ir.OFOR, ir.OFORUNTIL:
+	case ir.OFOR:
 		n := n.(*ir.ForStmt)
 		return walkFor(n)
 
@@ -178,7 +178,7 @@ func walkStmtList(s []ir.Node) {
 	}
 }
 
-// walkFor walks an OFOR or OFORUNTIL node.
+// walkFor walks an OFOR node.
 func walkFor(n *ir.ForStmt) ir.Node {
 	if n.Cond != nil {
 		init := ir.TakeInit(n.Cond)
@@ -188,9 +188,6 @@ func walkFor(n *ir.ForStmt) ir.Node {
 	}
 
 	n.Post = walkStmt(n.Post)
-	if n.Op() == ir.OFORUNTIL {
-		walkStmtList(n.Late)
-	}
 	walkStmtList(n.Body)
 	return n
 }