[llvm] [CodeGen][CodeLayout] Fix segfault on access to deleted block in MBP. (PR #142357)

[Afanasyev Ivan via llvm-commits]

https://github.com/ivafanas updated https://github.com/llvm/llvm-project/pull/142357

>From 034458b59d1df4e968dc2ce98700a1688dbc8f2a Mon Sep 17 00:00:00 2001
From: Ivan Afanasyev <ivafanas at gmail.com>
Date: Mon, 2 Jun 2025 17:15:41 +0700
Subject: [PATCH] [CodeGen][CodeLayout] Fix segfault on access to deleted block
 in MBP.

---
 llvm/lib/CodeGen/MachineBlockPlacement.cpp | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
index 08fe3d47e2ff5..6d75fdee6b567 100644
--- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp
+++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
@@ -3212,13 +3212,9 @@ bool MachineBlockPlacement::maybeTailDuplicateBlock(
     // Signal to outer function
     Removed = true;
 
-    // Conservative default.
-    bool InWorkList = true;
     // Remove from the Chain and Chain Map
     if (auto It = BlockToChain.find(RemBB); It != BlockToChain.end()) {
-      BlockChain *Chain = It->second;
-      InWorkList = Chain->UnscheduledPredecessors == 0;
-      Chain->remove(RemBB);
+      It->second->remove(RemBB);
       BlockToChain.erase(It);
     }
 
@@ -3228,11 +3224,10 @@ bool MachineBlockPlacement::maybeTailDuplicateBlock(
     }
 
     // Handle the Work Lists
-    if (InWorkList) {
-      SmallVectorImpl<MachineBasicBlock *> &RemoveList = BlockWorkList;
-      if (RemBB->isEHPad())
-        RemoveList = EHPadWorkList;
-      llvm::erase(RemoveList, RemBB);
+    if (RemBB->isEHPad()) {
+      llvm::erase(EHPadWorkList, RemBB);
+    } else {
+      llvm::erase(BlockWorkList, RemBB);
     }
 
     // Handle the filter set