From: Keith Randall <khr@golang.org>
Date: Sun, 12 Jul 2015 18:52:09 +0000 (-0700)
Subject: [dev.ssa] cmd/compile/internal/gc: handle _ label correctly
X-Git-Tag: go1.7beta1~1623^2^2~395
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=7e4c06dad065d1440fe8fcfa8e97702c88e1374e;p=gostls13.git

[dev.ssa] cmd/compile/internal/gc: handle _ label correctly

An empty label statement can just be ignored, as it cannot
be the target of any gotos.

Tests are already in test/fixedbugs/issue7538*.go

Fixes #11589
Fixes #11593

Change-Id: Iadcd639e7200ce16aa40fd7fa3eaf82522513e82
Reviewed-on: https://go-review.googlesource.com/12093
Reviewed-by: Daniel Morsing <daniel.morsing@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---

diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 2eb0402f69..d47680bf8a 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -316,6 +316,11 @@ func (s *state) stmt(n *Node) {
 		s.assign(OAS, n.Left.Name.Heapaddr, palloc)
 
 	case OLABEL, OGOTO:
+		if n.Op == OLABEL && isblanksym(n.Left.Sym) {
+			// Empty identifier is valid but useless.
+			// See issues 11589, 11593.
+			return
+		}
 		// get block at label, or make one
 		t := s.labels[n.Left.Sym.Name]
 		if t == nil {