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 <[email protected]> Reviewed-by: Keith Randall <[email protected]> Reviewed-by: David Chase <[email protected]> Run-TryBot: Keith Randall <[email protected]> TryBot-Result: Gopher Robot <[email protected]>
cloudflare · Aug 18, 2022 · a5370d0 · a5370d0
1 parent 6dc7b06
commit a5370d0
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Showing 12 changed files with 69 additions and 142 deletions.
diff --git a/src/cmd/compile/internal/escape/stmt.go b/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)

diff --git a/src/cmd/compile/internal/ir/fmt.go b/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:

diff --git a/src/cmd/compile/internal/ir/node.go b/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:
- // Init
- // top: { Body } // Execute the body at least once
- // cont: Post
- // if Cond { // And then test the loop condition
- // List // Before looping to top, execute List
- // goto top
- // }
- // 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 }
+ 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

diff --git a/src/cmd/compile/internal/ir/node_gen.go b/src/cmd/compile/internal/ir/node_gen.go
diff --git a/src/cmd/compile/internal/ir/op_string.go b/src/cmd/compile/internal/ir/op_string.go
diff --git a/src/cmd/compile/internal/ir/stmt.go b/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

diff --git a/src/cmd/compile/internal/ssa/prove.go b/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
-// created by OFORUNTIL, which isn't detected by findIndVar.
+// visiting b.
 //
 // TODO: It would be nice to combine this with findIndVar.
 func addLocalInductiveFacts(ft *factsTable, b *Block) {

diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/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)
- // 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)
- }
+ 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)
  }
 
@@ -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 {
- b.AddEdgeTo(bCond)
- // It can happen that bIncr ends in a block containing only VARKILL,
- // and that muddles the debugging experience.
- if b.Pos == src.NoXPos {
- b.Pos = bCond.Pos
- }
+ if b := s.endBlock(); b != nil {
+ b.AddEdgeTo(bCond)
+ // It can happen that bIncr ends in a block containing only VARKILL,
+ // and that muddles the debugging experience.
+ if b.Pos == src.NoXPos {
+ 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)

diff --git a/src/cmd/compile/internal/typecheck/stmt.go b/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
 }

diff --git a/src/cmd/compile/internal/typecheck/typecheck.go b/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

diff --git a/src/cmd/compile/internal/walk/range.go b/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() {