Use firrtl elses in elsewhen/otherwise case emission (#510)

Preprocess chisel3 IR before emission to determing whether
whens have alternatives.

1 files changed, 25 insertions, 0 deletions

diff --git a/src/test/scala/chiselTests/When.scala b/src/test/scala/chiselTests/When.scala
index d4491e13..d2646df7 100644
--- a/src/test/scala/chiselTests/When.scala
+++ b/src/test/scala/chiselTests/When.scala
@@ -53,6 +53,28 @@ class OverlappedWhenTester() extends BasicTester {
   }
 }
 
+class NoOtherwiseOverlappedWhenTester() extends BasicTester {
+  val cnt = Counter(4)
+  when(true.B) { cnt.inc() }
+
+  val out = Wire(UInt(3.W))
+  when(cnt.value <= 0.U) {
+    out := 1.U
+  } .elsewhen (cnt.value <= 1.U) {
+    out := 2.U
+  } .elsewhen (cnt.value <= 2.U) {
+    out := 3.U
+  } .elsewhen (cnt.value <= 3.U) {
+    out := 0.U
+  }
+
+  assert(out === cnt.value + 1.U)
+
+  when(cnt.value === 3.U) {
+    stop()
+  }
+}
+
 class WhenSpec extends ChiselFlatSpec {
   "When, elsewhen, and otherwise with orthogonal conditions" should "work" in {
     assertTesterPasses{ new WhenTester }
@@ -60,4 +82,7 @@ class WhenSpec extends ChiselFlatSpec {
   "When, elsewhen, and otherwise with overlapped conditions" should "work" in {
     assertTesterPasses{ new OverlappedWhenTester }
   }
+  "When and elsewhen without otherwise with overlapped conditions" should "work" in {
+    assertTesterPasses{ new NoOtherwiseOverlappedWhenTester }
+  }
 }