[llvm] 3d75c7c - [CodeLayout] Fixing initialization of empty ranges (#68917)

[via llvm-commits]

Author: spupyrev
Date: 2023-10-13T09:35:56-07:00
New Revision: 3d75c7c11b5a9ccb66e16df65a37f981ae6f0083

URL: https://github.com/llvm/llvm-project/commit/3d75c7c11b5a9ccb66e16df65a37f981ae6f0083
DIFF: https://github.com/llvm/llvm-project/commit/3d75c7c11b5a9ccb66e16df65a37f981ae6f0083.diff

LOG: [CodeLayout] Fixing initialization of empty ranges (#68917)

Fixing libc++'s consistency checks, by eliminating ranges of singular
iterators.

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/CodeLayout.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Utils/CodeLayout.cpp b/llvm/lib/Transforms/Utils/CodeLayout.cpp
index dea91dcac21ae14..620b52b69c31d57 100644
--- a/llvm/lib/Transforms/Utils/CodeLayout.cpp
+++ b/llvm/lib/Transforms/Utils/CodeLayout.cpp
@@ -476,13 +476,16 @@ void ChainT::mergeEdges(ChainT *Other) {
 }
 
 using NodeIter = std::vector<NodeT *>::const_iterator;
+static std::vector<NodeT *> EmptyList;
 
 /// A wrapper around three concatenated vectors (chains) of nodes; it is used
 /// to avoid extra instantiation of the vectors.
 struct MergedNodesT {
-  MergedNodesT(NodeIter Begin1, NodeIter End1, NodeIter Begin2 = NodeIter(),
-               NodeIter End2 = NodeIter(), NodeIter Begin3 = NodeIter(),
-               NodeIter End3 = NodeIter())
+  MergedNodesT(NodeIter Begin1, NodeIter End1,
+               NodeIter Begin2 = EmptyList.begin(),
+               NodeIter End2 = EmptyList.end(),
+               NodeIter Begin3 = EmptyList.begin(),
+               NodeIter End3 = EmptyList.end())
       : Begin1(Begin1), End1(End1), Begin2(Begin2), End2(End2), Begin3(Begin3),
         End3(End3) {}