Merge throw blocks in fgHeadTailMerge (#122070)

Should fix the regression in
#122065


[Diffs](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1216236&view=ms.vss-build-web.run-extensions-tab)

Author: EgorBo

src/coreclr/jit/fgopt.cpp

@@ -5366,17 +5366,25 @@ PhaseStatus Compiler::fgHeadTailMerge(bool early)
         }
     };
 
-    ArrayStack<BasicBlock*> retBlocks(getAllocator(CMK_ArrayStack));
+    ArrayStack<BasicBlock*> retOrThrowBlocks(getAllocator(CMK_ArrayStack));
 
     // Visit each block
     //
     for (BasicBlock* const block : Blocks())
     {
         iterateTailMerge(block);
+        if (block->isEmpty())
+        {
+            continue;
+        }
 
-        if (block->KindIs(BBJ_RETURN) && !block->isEmpty() && (block != genReturnBB))
+        if (block->KindIs(BBJ_THROW))
+        {
+            retOrThrowBlocks.Push(block);
+        }
+        else if (block->KindIs(BBJ_RETURN) && (block != genReturnBB))
         {
-            // Avoid spitting a return away from a possible tail call
+            // Avoid splitting a return away from a possible tail call
             //
             if (!block->hasSingleStmt())
             {
@@ -5389,14 +5397,14 @@ PhaseStatus Compiler::fgHeadTailMerge(bool early)
                 }
             }
 
-            retBlocks.Push(block);
+            retOrThrowBlocks.Push(block);
         }
     }
 
     predInfo.Reset();
-    for (int i = 0; i < retBlocks.Height(); i++)
+    for (int i = 0; i < retOrThrowBlocks.Height(); i++)
     {
-        predInfo.Push(PredInfo(retBlocks.Bottom(i), retBlocks.Bottom(i)->lastStmt()));
+        predInfo.Push(PredInfo(retOrThrowBlocks.Bottom(i), retOrThrowBlocks.Bottom(i)->lastStmt()));
     }
 
     tailMergePreds(nullptr);