commit 170ecdf6b2eab8aac2b8c852fa95d3c36d6bf604
author Cherry Zhang <cherryyz@google.com> Wed Jul 10 10:53:21 2019 -0400
committer Ian Lance Taylor <iant@golang.org> Wed Jul 10 17:56:10 2019 +0000
tree b5348e1deac7124bdcb8ccc94340c5387b1ed2fb
parent 7a8e10be0ddb8909ce25a264d03b24cee4df60cc

compiler: add break label in 1,2-case select statement lowering

CL 184998 added optimizations for one- and two-case select
statements. But it didn't handle break statement in the select
case correctly. Specifically, it didn't add the label definition,
so it could result in a dangling goto. This CL fixes this, by
adding the label definition.

A test case is CL 185520.

Change-Id: I98d30f599f1c4c71b91724ac394b8761d1b70b7d
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/185519
Reviewed-by: Ian Lance Taylor <iant@golang.org>

go/statements.cc

diff --git a/go/statements.cc b/go/statements.cc
index 1e88fab..b0b576f 100644
--- a/go/statements.cc
+++ b/go/statements.cc
@@ -5855,6 +5855,10 @@
     Statement::make_block_statement(scase.statements(), scase.location());
   b->add_statement(bs);
 
+  Statement* label =
+    Statement::make_unnamed_label_statement(this->break_label());
+  b->add_statement(label);
+
   this->is_lowered_ = true;
   return Statement::make_block_statement(b, loc);
 }
@@ -5958,6 +5962,10 @@
     Statement::make_if_statement(call, bchan, defcase.statements(), loc);
   b->add_statement(ifs);
 
+  Statement* label =
+    Statement::make_unnamed_label_statement(this->break_label());
+  b->add_statement(label);
+
   this->is_lowered_ = true;
   return Statement::make_block_statement(b, loc);
 }