JIT: Use normalized block for comparison in RBO dominator walk

src/coreclr/jit/redundantbranchopts.cpp

@@ -895,6 +895,8 @@ bool Compiler::optRedundantDominatingBranch(BasicBlock* const block)
             break;
         }
 
+        currentBlock = skipSideEffectFreeBlocks(currentBlock);
+
         // Make sure this conditional dominator branches to the same
         // shared block as the original block.
         //

src/tests/JIT/opt/RedundantBranch/RedundantBranchDominating.cs

@@ -106,6 +106,26 @@ private static int Dom_04(int count)
         return 3;
     }
 
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    private static int Dom_05(int count)
+    {
+        if (count > 1)
+        {
+            if (count > 2)
+            {
+                if (count > 3)
+                {
+                    if (count > 4)
+                    {
+                        return 1;
+                    }
+                }
+            }
+        }
+
+        return 3;
+    }
+
     private static void RunTest(string name, Func<int, int> func, int[] expectedResults, int[] expectedEffects)
     {
         s_effects = 0;
@@ -141,4 +161,8 @@ public static void TestDom03() =>
     [Fact]
     public static void TestDom04() =>
         RunTest(nameof(Dom_04), Dom_04, new[] { 3, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1 }, new[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 });
+
+    [Fact]
+    public static void TestDom05() =>
+        RunTest(nameof(Dom_05), Dom_05, new[] { 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1 }, new[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 });
 }