mask bits when propagating bitwise ops (#1745)

* ConstProp: test bitwise op of signed literals

* ConstProp: use bit mask for FoldOr/FoldXor

* handle and also

* add UIntLiteral.masked helper

Co-authored-by: Jack Koenig <koenig@sifive.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/test/scala/firrtlTests/ConstantPropagationTests.scala b/src/test/scala/firrtlTests/ConstantPropagationTests.scala
index 131f9466..d81f8687 100644
--- a/src/test/scala/firrtlTests/ConstantPropagationTests.scala
+++ b/src/test/scala/firrtlTests/ConstantPropagationTests.scala
@@ -1508,6 +1508,30 @@ class ConstantPropagationIntegrationSpec extends LowTransformSpec {
     execute(input, check, Seq.empty)
   }
 
+  it should "optimize bitwise operations of signed literals" in {
+    val input =
+      s"""|circuit Foo:
+          |  module Foo:
+          |    output out1: UInt<2>
+          |    output out2: UInt<2>
+          |    output out3: UInt<2>
+          |    out1 <= xor(SInt<2>(-1), SInt<2>(1))
+          |    out2 <= or(SInt<2>(-1), SInt<2>(1))
+          |    out3 <= and(SInt<2>(-1), SInt<2>(-2))
+          |""".stripMargin
+    val check =
+      s"""|circuit Foo:
+          |  module Foo:
+          |    output out1: UInt<2>
+          |    output out2: UInt<2>
+          |    output out3: UInt<2>
+          |    out1 <= UInt<2>(2)
+          |    out2 <= UInt<2>(3)
+          |    out3 <= UInt<2>(2)
+          |""".stripMargin
+    execute(input, check, Seq.empty)
+  }
+
 }