Guard against self-assignment in the DominatorTreeBase move assignment operator.

[tahonermann]

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.

[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Tom Honermann (tahonermann)

Changes

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.

---

Full diff: https://github.com/llvm/llvm-project/pull/116464.diff

1 Files Affected:

• (modified) llvm/include/llvm/Support/GenericDomTree.h (+2)

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);