Update reported width from div/rem to match FIRRTL results (#1748)

* Update reported width from div/rem to match FIRRTL results

* Add tests for width of % and / on UInt and SInt

* Add loop-based test for known UInt/SInt op result widths

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

1 files changed, 59 insertions, 0 deletions

diff --git a/src/test/scala/chiselTests/WidthSpec.scala b/src/test/scala/chiselTests/WidthSpec.scala
index 2a33c1d6..34159214 100644
--- a/src/test/scala/chiselTests/WidthSpec.scala
+++ b/src/test/scala/chiselTests/WidthSpec.scala
@@ -186,3 +186,62 @@ class RegInitWidthSpec extends WireDefaultRegInitSpecImpl {
   def builder2[T <: Data](x: T, y: T): T = RegInit(x, y)
 }
 
+class OpWidthSpec extends ChiselFlatSpec {
+  import firrtl._
+  import firrtl.ir._
+
+  val maxWidth = 5
+  val uIntOps: Seq[((UInt, UInt) => UInt, PrimOp)] =
+    Seq(
+      (_ +& _, PrimOps.Add),
+      (_ -& _, PrimOps.Sub),
+      (_ * _, PrimOps.Mul),
+      (_ / _, PrimOps.Div),
+      (_ % _, PrimOps.Rem),
+      (_ << _, PrimOps.Dshl),
+      (_ >> _, PrimOps.Dshr)
+    )
+
+  assertTesterPasses(new chisel3.testers.BasicTester {
+    for (i <- 0 to maxWidth) {
+      for (j <- 0 to maxWidth) {
+        for ((cOp, fOp) <- uIntOps) {
+          val args = Seq(i, j).map(w => Reference("", UIntType(IntWidth(w))))
+          fOp.propagateType(DoPrim(fOp, args, Nil, UnknownType)) match {
+            case UIntType(IntWidth(w)) =>
+              val x = 0.U(maxWidth.W).head(i)
+              val y = 0.U(maxWidth.W).head(j)
+              assert(w == cOp(x, y).getWidth)
+          }
+        }
+      }
+    }
+    stop()
+  })
+
+  val sIntOps: Seq[((SInt, SInt) => SInt, PrimOp)] =
+    Seq(
+      (_ +& _, PrimOps.Add),
+      (_ -& _, PrimOps.Sub),
+      (_ * _, PrimOps.Mul),
+      (_ / _, PrimOps.Div),
+      (_ % _, PrimOps.Rem)
+    )
+
+  assertTesterPasses(new chisel3.testers.BasicTester {
+    for (i <- 0 to maxWidth) {
+      for (j <- 0 to maxWidth) {
+        for ((cOp, fOp) <- sIntOps) {
+          val args = Seq(i, j).map(w => Reference("", SIntType(IntWidth(w))))
+          fOp.propagateType(DoPrim(fOp, args, Nil, UnknownType)) match {
+            case SIntType(IntWidth(w)) =>
+              val x = 0.U(maxWidth.W).head(i).asSInt
+              val y = 0.U(maxWidth.W).head(j).asSInt
+              assert(w == cOp(x, y).getWidth)
+          }
+        }
+      }
+    }
+    stop()
+  })
+}