cmd/compile: fix blank label code

When checkEnabled is forced true, the 52278 test fails. Be a bit
more careful about processing blank labels.

Update #52278

Change-Id: I48aa89e2c9e3715d8efe599bc4363b5b5879d8a2
Reviewed-on: https://go-review.googlesource.com/c/go/+/419318
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index a7778d37fb39200b00f297d8140dacb38b3b8322..2ee027092e9369ddc87342377379a011f49126a6 100644 (file)
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -1496,6 +1496,10 @@ func (s *state) stmt(n ir.Node) {
        case ir.OLABEL:
                n := n.(*ir.LabelStmt)
                sym := n.Label
+               if sym.IsBlank() {
+                       // Nothing to do because the label isn't targetable. See issue 52278.
+                       break
+               }
                lab := s.label(sym)
 
                // The label might already have a target block via a goto.

diff --git a/test/fixedbugs/issue52278.go b/test/fixedbugs/issue52278.go
index 56169e687144f08c778da825451e930394334164..147b6530373922aeacc5a700bb42663589c284cc 100644 (file)
--- a/test/fixedbugs/issue52278.go
+++ b/test/fixedbugs/issue52278.go
@@ -1,4 +1,4 @@
-// compile
+// compile -d=ssa/check/on
 
 // Copyright 2022 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style