ir: add faster serializer (#1694)

This Serializer which is implemented
external to the IR node definition
uses a StringBuilder to achieve about a
1.7x performance improvement when serializing.

Eventually, all implementations of the
`serialize` methd should be replaced with
a call to `Serializer.serialize`.

However, for this PR we keep the old
code in place in order to allow for easy
regression testing with the benchmark JAR
like this:
> java -cp utils/bin/firrtl-benchmark.jar \
  firrtl.benchmark.hot.SerializationBenchmark \
  ~/benchmarks/medium.pb 2 5 test

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/test/scala/firrtlTests/formal/VerificationSpec.scala b/src/test/scala/firrtlTests/formal/VerificationSpec.scala
index 22dbc1f1..31c54e76 100644
--- a/src/test/scala/firrtlTests/formal/VerificationSpec.scala
+++ b/src/test/scala/firrtlTests/formal/VerificationSpec.scala
@@ -5,6 +5,7 @@ package firrtlTests.formal
 import firrtl.{SystemVerilogCompiler}
 import firrtl.testutils.FirrtlFlatSpec
 import logger.{LogLevel, Logger}
+import firrtl.ir
 
 class VerificationSpec extends FirrtlFlatSpec {
   behavior of "Formal"
@@ -57,4 +58,23 @@ class VerificationSpec extends FirrtlFlatSpec {
         |""".stripMargin.split("\n") map normalized
     executeTest(input, expected, compiler)
   }
+
+  "VerificationStatement" should "serialize correctly" in {
+    val clk = ir.Reference("clk")
+    val en = ir.Reference("en")
+    val pred = ir.Reference("pred")
+    val a = ir.Verification(ir.Formal.Assert, ir.NoInfo, clk, pred, en, ir.StringLit("test"))
+
+    assert(a.serialize == "assert(clk, pred, en, \"test\")")
+    assert(ir.Serializer.serialize(a) == "assert(clk, pred, en, \"test\")")
+
+    val b = ir.Verification(ir.Formal.Assume, ir.NoInfo, clk, en, pred, ir.StringLit("test \n test"))
+    assert(b.serialize == "assume(clk, en, pred, \"test \\n test\")")
+    assert(ir.Serializer.serialize(b) == "assume(clk, en, pred, \"test \\n test\")")
+
+    val c = ir.Verification(ir.Formal.Assume, ir.NoInfo, clk, pred, en, ir.StringLit("test \t test"))
+    assert(c.serialize == "assume(clk, pred, en, \"test \\t test\")")
+    assert(ir.Serializer.serialize(c) == "assume(clk, pred, en, \"test \\t test\")")
+
+  }
 }