Adds verilator flags (seemingly not working)

build.sc

@@ -51,6 +51,13 @@ object `TPchisel` extends SbtModule { m =>
         )
 
         val nproc = sys.env.get("NPROC").getOrElse("1");
+
+        override def forkEnv = T {
+            super.forkEnv() ++ Map(
+                "VERILATOR_FLAGS" -> "--O3 --noassert --no-coverage --x-assign fast --x-initial fast --trace-fst -CFLAGS -O3 -CFLAGS -march=native -CFLAGS -flto -LDFLAGS -flto --threads 4",
+                "VERILATOR_RECOMPILE" -> "false"
+            )
+        }
         override def forkArgs = super.forkArgs() ++ Seq(
             "-Dscalatest.parallel.enabled=true",
             "-Dscalatest.parallel.mode=concurrent",