[Interpreter] Optimize equality check with null/undefined with a check on the map.

test/unittests/interpreter/bytecode-peephole-optimizer-unittest.cc

Index: test/unittests/interpreter/bytecode-peephole-optimizer-unittest.cc
diff --git a/test/unittests/interpreter/bytecode-peephole-optimizer-unittest.cc b/test/unittests/interpreter/bytecode-peephole-optimizer-unittest.cc
index d1c570d421cd45f1532a9751578677187054f64c..70c50b5e10f7e5dfb0b4d4044bd8d9d05e349e61 100644
--- a/test/unittests/interpreter/bytecode-peephole-optimizer-unittest.cc
+++ b/test/unittests/interpreter/bytecode-peephole-optimizer-unittest.cc
@@ -403,6 +403,25 @@ TEST_F(BytecodePeepholeOptimizerTest, MergeLdaZeroWithBinaryOp) {
   }
 }
 
+TEST_F(BytecodePeepholeOptimizerTest, MergeLdaNullOrUndefinedWithCompareOp) {
+  Bytecode first_bytecodes[] = {Bytecode::kLdaUndefined, Bytecode::kLdaNull};
+
+  for (auto first_bytecode : first_bytecodes) {
+    uint32_t reg_operand = Register(0).ToOperand();
+    uint32_t idx_operand = 1;
+    BytecodeNode first(first_bytecode);
+    BytecodeNode second(Bytecode::kTestEqual, reg_operand, idx_operand);
+    optimizer()->Write(&first);
+    optimizer()->Write(&second);
+    Flush();
+    CHECK_EQ(write_count(), 1);
+    CHECK_EQ(last_written().bytecode(), Bytecode::kTestUndetectable);
+    CHECK_EQ(last_written().operand_count(), 1);
+    CHECK_EQ(last_written().operand(0), reg_operand);
+    Reset();
+  }
+}
+
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8