go/test/fixedbugs/issue19783.go
Josh Bleecher Snyder 5272a2cdc5 cmd/compile: avoid infinite loops in dead blocks during phi insertion
Now that we no longer generate dead code,
it is possible to follow block predecessors
into infinite loops with no variable definitions,
causing an infinite loop during phi insertion.

To fix that, check explicitly whether the predecessor
is dead in lookupVarOutgoing, and if so, bail.

The loop in lookupVarOutgoing is very hot code,
so I am wary of adding anything to it.
However, a long, CPU-only benchmarking run shows no
performance impact at all.

Fixes #19783

Change-Id: I8ef8d267e0b20a29b5cb0fecd7084f76c6f98e47
Reviewed-on: https://go-review.googlesource.com/38913
Reviewed-by: David Chase <drchase@google.com>
2017-03-30 17:06:08 +00:00

18 lines
260 B
Go

// compile
// Copyright 2017 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.
package p
func Spin() {
l1:
for true {
goto l1
l2:
if true {
goto l2
}
}
}