From accde43eb68acdf0c2aa1c1facd02ec7686bd20a Mon Sep 17 00:00:00 2001
From: Jakob Botsch Nielsen <jakob.botsch.nielsen@gmail.com>
Date: Sun, 3 Dec 2023 18:47:56 +0100
Subject: [PATCH] JIT: Check for reachable preds in RBO

Nothing guarantees that all preds are reachable, in which case the
"dominates" query does not make sense.
---
 src/coreclr/jit/redundantbranchopts.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/coreclr/jit/redundantbranchopts.cpp b/src/coreclr/jit/redundantbranchopts.cpp
index 612fa1ef1beb3f..c542c99cb52385 100644
--- a/src/coreclr/jit/redundantbranchopts.cpp
+++ b/src/coreclr/jit/redundantbranchopts.cpp
@@ -818,7 +818,7 @@ bool Compiler::optJumpThreadCheck(BasicBlock* const block, BasicBlock* const dom
     {
         for (BasicBlock* const predBlock : block->PredBlocks())
         {
-            if (!fgSsaDomTree->Dominates(domBlock, predBlock))
+            if (m_dfs->Contains(predBlock) && !fgSsaDomTree->Dominates(domBlock, predBlock))
             {
                 JITDUMP("Dom " FMT_BB " is stale (does not dominate pred " FMT_BB "); no threading\n", domBlock->bbNum,
                         predBlock->bbNum);