tensor: Fix timing of fullCTag

src/main/scala/radiance/core/TensorCoreDecoupled.scala

@@ -272,25 +272,25 @@ class TensorCoreDecoupled(
   // regfile latency is 1 cycle; don't need a deep response queue
   val respQueueCDepth = 1
   val respQueueC = Module(new Queue(
-    chiselTypeOf(io.respC), respQueueCDepth
+    new Bundle {
+      val tag = new TensorMemTag
+      val data = UInt(io.respC.widthOption.get.W)
+    },
+    respQueueCDepth
   ))
-  respQueueC.io.enq.valid := respCValid
-  respQueueC.io.enq.bits := io.respC
-
-  // serialize every two C responses into one full 4x4 C tile
-  val fullC = Module(new FillBuffer(
-    chiselTypeOf(io.respC), 2/*substeps*/
-  ))
-  fullC.io.enq.valid := respQueueC.io.deq.valid
-  fullC.io.enq.bits := respQueueC.io.deq.bits
-  respQueueC.io.deq.ready := fullC.io.enq.ready
-
   // make sure there's space at the response queue to be latched at the next
   // cycle
   val genReqC = (state === AccessorState.access) && respQueueC.io.enq.ready
   // 1-cycle delay
   respCValid := genReqC
 
+  // note rd is independent to sets
+  def rdGen(step: UInt, substep: UInt): UInt = {
+    // each step produces 4x4 output tile, written by 8 threads with 2 regs per
+    // thread
+    (step << 1/*2 substeps*/) + substep
+  }
+
   io.reqC.valid := genReqC
   io.reqC.bits := 5.U // FIXME
 
@@ -303,6 +303,28 @@ class TensorCoreDecoupled(
     }
     stateRegC.index := stateRegC.index + 1.U
   }
+  dontTouch(stateRegC)
+
+  // queue the regfile response to buffers
+  // these strictly belong to the execute stage
+  respQueueC.io.enq.valid := respCValid
+  respQueueC.io.enq.bits.tag.warp := warpAccess
+  respQueueC.io.enq.bits.tag.set := stateRegC.set
+  respQueueC.io.enq.bits.tag.index := stateRegC.index
+  respQueueC.io.enq.bits.data := io.respC
+
+  // serialize every two C responses into one full 4x4 C tile
+  val fullC = Module(new FillBuffer(
+    chiselTypeOf(respQueueC.io.deq.bits.data), 2/*substeps*/
+  ))
+  fullC.io.enq.valid := respQueueC.io.deq.valid
+  fullC.io.enq.bits := respQueueC.io.deq.bits.data
+  respQueueC.io.deq.ready := fullC.io.enq.ready
+  val fullCTag = Module(new Queue(
+    new TensorMemTag, entries = 1, pipe = true
+  ))
+  fullCTag.io.enq.valid := respQueueC.io.deq.valid
+  fullCTag.io.enq.bits := respQueueC.io.deq.bits.tag
 
   // ===========================================================================
   // Execute stage
@@ -391,18 +413,12 @@ class TensorCoreDecoupled(
   fullB.io.deq.ready := fullBBuf.io.enq.ready
   fullBTag.io.deq.ready := fullBBuf.io.enq.ready
 
-  // fullC is instiated at the access stage
+  // fullC/fullCTag is instiated at the access stage
-
-  val fullCTag = Module(new Queue(
-    new TensorMemTag, entries = 1, pipe = true
-  ))
-  fullCTag.io.enq.valid := respQueueB.valid
-  fullCTag.io.enq.bits := respQueueB.bits.tag
 
   val fullCBuf = Module(new Queue(
     new Bundle {
-      val data = chiselTypeOf(fullC.io.deq.bits)
       val tag = new TensorMemTag
+      val data = chiselTypeOf(fullC.io.deq.bits)
     }, entries = 1, pipe = true
   ))
   fullCBuf.io.enq.valid := fullC.io.deq.valid
@@ -413,7 +429,8 @@ class TensorCoreDecoupled(
 
   val dpuReady = Wire(Bool())
   val dpuFire = Wire(Bool())
-  val operandsValid = fullABuf.io.deq.valid && fullBBuf.io.deq.valid
+  val operandsValid =
+    fullABuf.io.deq.valid && fullBBuf.io.deq.valid && fullCBuf.io.deq.valid
   dpuFire := operandsValid && dpuReady
   dontTouch(dpuFire)
 
@@ -465,7 +482,7 @@ class TensorCoreDecoupled(
     (substepCompute === 1.U)
   fullBBuf.io.deq.ready := dpuFire && shouldDequeueB
 
-  // C buf should be synced with B buf
+  // C deq should be synced with B deq
   fullCBuf.io.deq.ready := dpuFire && shouldDequeueB
 
   dontTouch(respQueueA)
@@ -584,13 +601,6 @@ class TensorCoreDecoupled(
 
   // val widQueue = Queue(io.initiate, queueDepth, pipe = (queueDepth == 1))
 
-  // note rd is independent to sets
-  def rdGen(step: UInt, substep: UInt): UInt = {
-    // each step produces 4x4 output tile, written by 8 threads with 2 regs per
-    // thread
-    (step << 1/*2 substeps*/) + substep
-  }
-
   val warpWriteback = tagQueue.io.deq.bits.warp
   val setWriteback = tagQueue.io.deq.bits.set
   val stepWriteback = tagQueue.io.deq.bits.step