[llvm] 3f6a1d1 - Guard against self-assignment in the DominatorTreeBase move assignment operator. (#116464)

[via llvm-commits]

Author: Tom Honermann
Date: 2024-11-16T16:39:30-05:00
New Revision: 3f6a1d179305f266835242ac7d1e55249c50c074

URL: https://github.com/llvm/llvm-project/commit/3f6a1d179305f266835242ac7d1e55249c50c074
DIFF: https://github.com/llvm/llvm-project/commit/3f6a1d179305f266835242ac7d1e55249c50c074.diff

LOG: Guard against self-assignment in the DominatorTreeBase move assignment operator. (#116464)

The `DominatorTreeBase` move assignment operator was not self-assignment
safe because the last thing it does before returning is to release all
resources held by the source object. This issue was reported by a static
analysis tool; no self-assignment is known to occur in practice.

Added: 
    

Modified: 
    llvm/include/llvm/Support/GenericDomTree.h

Removed: 
    


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diff  --git a/llvm/include/llvm/Support/GenericDomTree.h b/llvm/include/llvm/Support/GenericDomTree.h
index 45ef38b965b752..d0eec2070b4d7e 100644
--- a/llvm/include/llvm/Support/GenericDomTree.h
+++ b/llvm/include/llvm/Support/GenericDomTree.h
@@ -287,6 +287,8 @@ class DominatorTreeBase {
   }
 
   DominatorTreeBase &operator=(DominatorTreeBase &&RHS) {
+    if (this == &RHS)
+      return *this;
     Roots = std::move(RHS.Roots);
     DomTreeNodes = std::move(RHS.DomTreeNodes);
     NodeNumberMap = std::move(RHS.NodeNumberMap);