From f1bc20812edc0eccc4eda2fa79cc96bce873e063 Mon Sep 17 00:00:00 2001
From: Jack Koenig <koenig@sifive.com>
Date: Wed, 26 Jun 2024 11:49:40 -0700
Subject: [PATCH] Fix BoringUtils for identity views

---
 core/src/main/scala/chisel3/RawModule.scala   |   7 +-
 .../chiselTests/BoringUtilsTapSpec.scala      | 112 ++++++++++++++++++
 2 files changed, 118 insertions(+), 1 deletion(-)

diff --git a/core/src/main/scala/chisel3/RawModule.scala b/core/src/main/scala/chisel3/RawModule.scala
index 8981af1bab4..290c6ff854e 100644
--- a/core/src/main/scala/chisel3/RawModule.scala
+++ b/core/src/main/scala/chisel3/RawModule.scala
@@ -225,7 +225,12 @@ abstract class RawModule extends BaseModule {
   }
   private[chisel3] val stagedSecretCommands = collection.mutable.ArrayBuffer[Command]()
 
-  private[chisel3] def secretConnection(left: Data, right: Data)(implicit si: SourceInfo): Unit = {
+  private[chisel3] def secretConnection(left: Data, _right: Data)(implicit si: SourceInfo): Unit = {
+    val (right: Data, _) = chisel3.experimental.dataview
+      .reifyIdentityView(_right)
+      .getOrElse(
+        throwException(s"BoringUtils currently only support identity views, ${_right} has multiple targets.")
+      )
     val rhs = (left.probeInfo.nonEmpty, right.probeInfo.nonEmpty) match {
       case (true, true)                                 => ProbeDefine(si, left.lref, Node(right))
       case (true, false) if left.probeInfo.get.writable => ProbeDefine(si, left.lref, RWProbeExpr(Node(right)))
diff --git a/src/test/scala/chiselTests/BoringUtilsTapSpec.scala b/src/test/scala/chiselTests/BoringUtilsTapSpec.scala
index 6bdc2be0804..2bff53ae354 100644
--- a/src/test/scala/chiselTests/BoringUtilsTapSpec.scala
+++ b/src/test/scala/chiselTests/BoringUtilsTapSpec.scala
@@ -165,6 +165,60 @@ class BoringUtilsTapSpec extends ChiselFlatSpec with ChiselRunners with Utils wi
     )()
   }
 
+  it should "work for identity views" in {
+    import chisel3.experimental.dataview._
+    class Foo extends RawModule {
+      private val internalWire = Wire(Bool())
+      val view = internalWire.viewAs[Bool]
+    }
+    class Top extends RawModule {
+      val foo = Module(new Foo)
+      val outProbe = IO(probe.Probe(Bool()))
+      val out = IO(Bool())
+      probe.define(outProbe, BoringUtils.tap(foo.view))
+      out := BoringUtils.tapAndRead(foo.view)
+    }
+    val chirrtl = circt.stage.ChiselStage.emitCHIRRTL(new Top)
+    matchesAndOmits(chirrtl)(
+      "module Foo :",
+      "output bore : Probe<UInt<1>>",
+      "output out_bore : Probe<UInt<1>>",
+      "define bore = probe(internalWire)",
+      "define out_bore = probe(internalWire)",
+      "module Top :",
+      "define outProbe = foo.bore",
+      "connect out, read(foo.out_bore)"
+    )()
+  }
+
+  it should "NOT work [yet] for non-identity views" in {
+    import chisel3.experimental.dataview._
+    class MyBundle extends Bundle {
+      val a = Bool()
+      val b = Bool()
+    }
+    object MyBundle {
+      implicit val view: DataView[(Bool, Bool), MyBundle] = DataView(
+        _ => new MyBundle,
+        _._1 -> _.a,
+        _._2 -> _.b
+      )
+    }
+    class Foo extends RawModule {
+      private val w1, w2 = Wire(Bool())
+      val view = (w1, w2).viewAs[MyBundle]
+    }
+    class Top extends RawModule {
+      val foo = Module(new Foo)
+      val out = IO(new MyBundle)
+      val outProbe = IO(probe.Probe(new MyBundle))
+      probe.define(outProbe, BoringUtils.tap(foo.view))
+      out := BoringUtils.tapAndRead(foo.view)
+    }
+    val e = the[ChiselException] thrownBy circt.stage.ChiselStage.emitCHIRRTL(new Top)
+    e.getMessage should include("BoringUtils currently only support identity views")
+  }
+
   "Writable tap" should "work downwards from grandparent to grandchild" in {
     class Bar extends RawModule {
       val internalWire = Wire(Bool())
@@ -527,4 +581,62 @@ class BoringUtilsTapSpec extends ChiselFlatSpec with ChiselRunners with Utils wi
     )()
   }
 
+  it should "work for identity views" in {
+    import chisel3.experimental.dataview._
+    class Bar extends RawModule {
+      private val internalWire = Wire(Bool())
+      val view = internalWire.viewAs[Bool]
+    }
+    class Foo extends RawModule {
+      val bar = Module(new Bar)
+    }
+    class Top extends RawModule {
+      val foo = Module(new Foo)
+      val out = IO(Bool())
+      out := probe.read(BoringUtils.rwTap(foo.bar.view))
+      probe.forceInitial(BoringUtils.rwTap(foo.bar.view), false.B)
+    }
+    val chirrtl = circt.stage.ChiselStage.emitCHIRRTL(new Top)
+    matchesAndOmits(chirrtl)(
+      "module Bar :",
+      "output out_bore : RWProbe<UInt<1>>",
+      "define out_bore = rwprobe(internalWire)",
+      "module Foo :",
+      "output out_bore : RWProbe<UInt<1>>",
+      "define out_bore = bar.out_bore",
+      "module Top :",
+      "connect out, read(foo.out_bore)",
+      "force_initial(foo.bore, UInt<1>(0h0))"
+    )()
+  }
+
+  it should "NOT work [yet] for non-identity views" in {
+    import chisel3.experimental.dataview._
+    class MyBundle extends Bundle {
+      val a = Bool()
+      val b = Bool()
+    }
+    object MyBundle {
+      implicit val view: DataView[(Bool, Bool), MyBundle] = DataView(
+        _ => new MyBundle,
+        _._1 -> _.a,
+        _._2 -> _.b
+      )
+    }
+    class Bar extends RawModule {
+      private val w1, w2 = Wire(Bool())
+      val view = (w1, w2).viewAs[MyBundle]
+    }
+    class Foo extends RawModule {
+      val bar = Module(new Bar)
+    }
+    class Top extends RawModule {
+      val foo = Module(new Foo)
+      val out = IO(Bool())
+      out := probe.read(BoringUtils.rwTap(foo.bar.view))
+      probe.forceInitial(BoringUtils.rwTap(foo.bar.view), false.B)
+    }
+    val e = the[ChiselException] thrownBy circt.stage.ChiselStage.emitCHIRRTL(new Top)
+    e.getMessage should include("BoringUtils currently only support identity views")
+  }
 }