SDAGBuilder: Don't create an invalid iterator when there is only one switch case.
Found by libstdc++'s debug mode.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157522 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 0d37c62..f8cbcaa 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1984,10 +1984,10 @@
}
}
}
-
// Rearrange the case blocks so that the last one falls through if possible.
Case &BackCase = *(CR.Range.second-1);
- if (NextBlock && Default != NextBlock && BackCase.BB != NextBlock) {
+ if (Size > 1 &&
+ NextBlock && Default != NextBlock && BackCase.BB != NextBlock) {
// The last case block won't fall through into 'NextBlock' if we emit the
// branches in this order. See if rearranging a case value would help.
// We start at the bottom as it's the case with the least weight.