Upstream intervals (#870)

Major features:

- Added Interval type, as well as PrimOps asInterval, clip, wrap, and sqz.
- Changed PrimOp names: bpset -> setp, bpshl -> incp, bpshr -> decp
- Refactored width/bound inferencer into a separate constraint solver
- Added transforms to infer, trim, and remove interval bounds
- Tests for said features

Plan to be released with 1.3

1 files changed, 27 insertions, 0 deletions

diff --git a/src/main/scala/firrtl/constraint/IsVar.scala b/src/main/scala/firrtl/constraint/IsVar.scala
new file mode 100644
index 00000000..98396fa0
--- /dev/null
+++ b/src/main/scala/firrtl/constraint/IsVar.scala
@@ -0,0 +1,27 @@
+// See LICENSE for license details.
+
+package firrtl.constraint
+
+object IsVar {
+  def unapply(i: Constraint): Option[String] = i match {
+    case i: IsVar => Some(i.name)
+    case _ => None
+  }
+}
+
+/** Extend to be a constraint variable */
+trait IsVar extends Constraint {
+
+  def name: String
+
+  override def serialize: String = name
+
+  override def map(f: Constraint=>Constraint): Constraint = this
+
+  override def reduce() = this
+
+  val children = Vector()
+}
+
+case class VarCon(name: String) extends IsVar
+