}
})
- // Perform a garbage collection of hidden closures functions that
- // are no longer reachable from top-level functions following
- // inlining. See #59404 and #59638 for more context.
- garbageCollectUnreferencedHiddenClosures()
-
- if p != nil {
- pgoInlineEpilogue(p, decls)
- }
-}
-
-// garbageCollectUnreferencedHiddenClosures makes a pass over all the
-// top-level (non-hidden-closure) functions looking for nested closure
-// functions that are reachable, then sweeps through the Target.Decls
-// list and marks any non-reachable hidden closure function as dead.
-// See issues #59404 and #59638 for more context.
-func garbageCollectUnreferencedHiddenClosures() {
-
- liveFuncs := make(map[*ir.Func]bool)
-
- var markLiveFuncs func(fn *ir.Func)
- markLiveFuncs = func(fn *ir.Func) {
- liveFuncs[fn] = true
- var vis func(node ir.Node)
- vis = func(node ir.Node) {
- if clo, ok := node.(*ir.ClosureExpr); ok {
- if !liveFuncs[clo.Func] {
- liveFuncs[clo.Func] = true
- markLiveFuncs(clo.Func)
+ // Rewalk post-inlining functions to check for closures that are
+ // still visible but were (over-agressively) marked as dead, and
+ // undo that marking here. See #59404 for more context.
+ ir.VisitFuncsBottomUp(decls, func(list []*ir.Func, recursive bool) {
+ for _, n := range list {
+ ir.Visit(n, func(node ir.Node) {
+ if clo, ok := node.(*ir.ClosureExpr); ok && clo.Func.IsHiddenClosure() {
+ clo.Func.SetIsDeadcodeClosure(false)
}
- }
+ })
}
- ir.Visit(fn, vis)
- }
-
- for i := 0; i < len(typecheck.Target.Decls); i++ {
- if fn, ok := typecheck.Target.Decls[i].(*ir.Func); ok {
- if fn.IsHiddenClosure() {
- continue
- }
- markLiveFuncs(fn)
- }
- }
+ })
- for i := 0; i < len(typecheck.Target.Decls); i++ {
- if fn, ok := typecheck.Target.Decls[i].(*ir.Func); ok {
- if !fn.IsHiddenClosure() {
- continue
- }
- if fn.IsDeadcodeClosure() {
- continue
- }
- if liveFuncs[fn] {
- continue
- }
- fn.SetIsDeadcodeClosure(true)
- if base.Flag.LowerM > 2 {
- fmt.Printf("%v: unreferenced closure %v marked as dead\n", ir.Line(fn), fn)
- }
- if fn.Inl != nil && fn.LSym == nil {
- ir.InitLSym(fn, true)
- }
- }
+ if p != nil {
+ pgoInlineEpilogue(p, decls)
}
}
}
if fn := inlCallee(call.X, profile); fn != nil && typecheck.HaveInlineBody(fn) {
n = mkinlcall(call, fn, bigCaller, inlCalls, edit)
+ if fn.IsHiddenClosure() {
+ // Visit function to pick out any contained hidden
+ // closures to mark them as dead, since they will no
+ // longer be reachable (if we leave them live, they
+ // will get skipped during escape analysis, which
+ // could mean that go/defer statements don't get
+ // desugared, causing later problems in walk). See
+ // #59404 for more context. Note also that the code
+ // below can sometimes be too aggressive (marking a closure
+ // dead even though it was captured by a local var).
+ // In this case we'll undo the dead marking in a cleanup
+ // pass that happens at the end of InlineDecls.
+ var vis func(node ir.Node)
+ vis = func(node ir.Node) {
+ if clo, ok := node.(*ir.ClosureExpr); ok && clo.Func.IsHiddenClosure() && !clo.Func.IsDeadcodeClosure() {
+ if base.Flag.LowerM > 2 {
+ fmt.Printf("%v: closure %v marked as dead\n", ir.Line(clo.Func), clo.Func)
+ }
+ clo.Func.SetIsDeadcodeClosure(true)
+ ir.Visit(clo.Func, vis)
+ }
+ }
+ ir.Visit(fn, vis)
+ }
}
}