1 files changed, 44 insertions, 0 deletions
diff --git a/src/test/scala/firrtlTests/ConstantPropagationTests.scala b/src/test/scala/firrtlTests/ConstantPropagationTests.scala
index ef52507f..cc7a5e32 100644
--- a/src/test/scala/firrtlTests/ConstantPropagationTests.scala
+++ b/src/test/scala/firrtlTests/ConstantPropagationTests.scala
@@ -1393,6 +1393,50 @@ class ConstantPropagationIntegrationSpec extends LowTransformSpec {
       """.stripMargin
     execute(input, check, Seq.empty)
   }
+
+  private def matchingArgs(op: String, iType: String, oType: String, result: String): Unit = {
+    val input =
+      s"""circuit Top :
+         |  module Top :
+         |    input i : ${iType}
+         |    output o : ${oType}
+         |    o <= ${op}(i, i)
+      """.stripMargin
+    val check =
+      s"""circuit Top :
+         |  module Top :
+         |    input i : ${iType}
+         |    output o : ${oType}
+         |    o <= ${result}
+      """.stripMargin
+    execute(input, check, Seq.empty)
+  }
+
+  it should "optimize some binary operations when arguments match" in {
+    // Signedness matters
+    matchingArgs("sub", "UInt<8>", "UInt<8>", """ UInt<8>("h0")  """ )
+    matchingArgs("sub", "SInt<8>", "SInt<8>", """ SInt<8>("h0")  """ )
+    matchingArgs("div", "UInt<8>", "UInt<8>", """ UInt<8>("h1")  """ )
+    matchingArgs("div", "SInt<8>", "SInt<8>", """ SInt<8>("h1")  """ )
+    matchingArgs("rem", "UInt<8>", "UInt<8>", """ UInt<8>("h0")  """ )
+    matchingArgs("rem", "SInt<8>", "SInt<8>", """ SInt<8>("h0")  """ )
+    matchingArgs("and", "UInt<8>", "UInt<8>", """ i              """ )
+    matchingArgs("and", "SInt<8>", "UInt<8>", """ asUInt(i)      """ )
+    // Signedness doesn't matter
+    matchingArgs("or",  "UInt<8>", "UInt<8>", """ i """ )
+    matchingArgs("or",  "SInt<8>", "UInt<8>", """ asUInt(i) """ )
+    matchingArgs("xor", "UInt<8>", "UInt<8>", """ UInt<8>("h0")  """ )
+    matchingArgs("xor", "SInt<8>", "UInt<8>", """ UInt<8>("h0")  """ )
+    // Always true
+    matchingArgs("eq",  "UInt<8>", "UInt<1>", """ UInt<1>("h1")  """ )
+    matchingArgs("leq", "UInt<8>", "UInt<1>", """ UInt<1>("h1")  """ )
+    matchingArgs("geq", "UInt<8>", "UInt<1>", """ UInt<1>("h1")  """ )
+    // Never true
+    matchingArgs("neq", "UInt<8>", "UInt<1>", """ UInt<1>("h0")  """ )
+    matchingArgs("lt",  "UInt<8>", "UInt<1>", """ UInt<1>("h0")  """ )
+    matchingArgs("gt",  "UInt<8>", "UInt<1>", """ UInt<1>("h0")  """ )
+  }
+
 }