diff --git a/src/cmd/compile/internal/gc/escape.go b/src/cmd/compile/internal/gc/escape.go index c03e50628d..d2e096d0f0 100644 --- a/src/cmd/compile/internal/gc/escape.go +++ b/src/cmd/compile/internal/gc/escape.go @@ -201,7 +201,7 @@ func (e *Escape) walkFunc(fn *Node) { e.curfn = fn e.loopDepth = 1 - e.stmts(fn.Nbody) + e.block(fn.Nbody) } // Below we implement the methods for walking the AST and recording @@ -284,14 +284,14 @@ func (e *Escape) stmt(n *Node) { case OIF: e.discard(n.Left) - e.stmts(n.Nbody) - e.stmts(n.Rlist) + e.block(n.Nbody) + e.block(n.Rlist) case OFOR, OFORUNTIL: e.loopDepth++ e.discard(n.Left) e.stmt(n.Right) - e.stmts(n.Nbody) + e.block(n.Nbody) e.loopDepth-- case ORANGE: @@ -311,7 +311,7 @@ func (e *Escape) stmt(n *Node) { } } - e.stmts(n.Nbody) + e.block(n.Nbody) e.loopDepth-- case OSWITCH: @@ -340,13 +340,13 @@ func (e *Escape) stmt(n *Node) { } e.discards(cas.List) - e.stmts(cas.Nbody) + e.block(cas.Nbody) } case OSELECT: for _, cas := range n.List.Slice() { e.stmt(cas.Left) - e.stmts(cas.Nbody) + e.block(cas.Nbody) } case OSELRECV: e.assign(n.Left, n.Right, "selrecv", n) @@ -398,12 +398,18 @@ func (e *Escape) stmt(n *Node) { } func (e *Escape) stmts(l Nodes) { - // TODO(mdempsky): Preserve and restore e.loopDepth? See also #22438. for _, n := range l.Slice() { e.stmt(n) } } +// block is like stmts, but preserves loopDepth. +func (e *Escape) block(l Nodes) { + old := e.loopDepth + e.stmts(l) + e.loopDepth = old +} + // expr models evaluating an expression n and flowing the result into // hole k. func (e *Escape) expr(k EscHole, n *Node) { diff --git a/test/escape_goto.go b/test/escape_goto.go new file mode 100644 index 0000000000..f024a9afe3 --- /dev/null +++ b/test/escape_goto.go @@ -0,0 +1,44 @@ +// errorcheck -0 -m -l + +// Copyright 2019 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Test escape analysis for goto statements. + +package escape + +var x bool + +func _() { + var p *int +loop: + if x { + goto loop + } + // BAD: We should be able to recognize that there + // aren't any more "goto loop" after here. + p = new(int) // ERROR "escapes to heap" + _ = p +} + +func _() { + var p *int + if x { + loop: + goto loop + } else { + p = new(int) // ERROR "does not escape" + } + _ = p +} + +func _() { + var p *int + if x { + loop: + goto loop + } + p = new(int) // ERROR "does not escape" + _ = p +}