Merge pull request #307 from ucb-bar/address-shrink

RR: undefined regs return zeros

src/main/scala/uncore/tilelink2/AddressDecoder.scala

@@ -25,13 +25,25 @@ object AddressDecoder
     // Verify the user did not give us an impossible problem
     ports.combinations(2).foreach { case Seq(x, y) =>
       x.foreach { a => y.foreach { b =>
-        require (!a.overlaps(b)) // it must be possible to disambiguate addresses!
+        require (!a.overlaps(b)) // it must be possible to disambiguate ports!
       } }
     }
+
     val maxBits = log2Ceil(ports.map(_.map(_.max).max).max + 1)
     val bits = (0 until maxBits).map(BigInt(1) << _).toSeq
     val selected = recurse(Seq(ports.map(_.sorted).sorted(portOrder)), bits)
-    selected.reduceLeft(_ | _)
+    val output = selected.reduceLeft(_ | _)
+
+    // Modify the AddressSets to allow the new wider match functions
+    val widePorts = ports.map { _.map { _.widen(~output) } }
+    // Verify that it remains possible to disambiguate all ports
+    widePorts.combinations(2).foreach { case Seq(x, y) =>
+      x.foreach { a => y.foreach { b =>
+        require (!a.overlaps(b))
+      } }
+    }
+
+    output
   }
 
   // A simpler version that works for a Seq[Int]
@@ -51,11 +63,12 @@ object AddressDecoder
   //   pick the bit which minimizes the number of ports in each partition
   //   as a secondary goal, reduce the number of AddressSets within a partition
 
-  val bigValue = 100000
-  def bitScore(partitions: Partitions): Int = {
+  def bitScore(partitions: Partitions): Seq[Int] = {
     val maxPortsPerPartition = partitions.map(_.size).max
+    val sumPortsPerPartition = partitions.map(_.size).sum
     val maxSetsPerPartition = partitions.map(_.map(_.size).sum).max
-    maxPortsPerPartition * bigValue + maxSetsPerPartition
+    val sumSetsPerPartition = partitions.map(_.map(_.size).sum).sum
+    Seq(maxPortsPerPartition, sumPortsPerPartition, maxSetsPerPartition, sumSetsPerPartition)
   }
 
   def partitionPort(port: Port, bit: BigInt): (Port, Port) = {
@@ -77,8 +90,8 @@ object AddressDecoder
   
   def partitionPartitions(partitions: Partitions, bit: BigInt): Partitions = {
     val partitioned_partitions = partitions.map(p => partitionPorts(p, bit))
-    val case_a_partitions = partitioned_partitions.map(_._1)
-    val case_b_partitions = partitioned_partitions.map(_._2)
+    val case_a_partitions = partitioned_partitions.map(_._1).filter(!_.isEmpty)
+    val case_b_partitions = partitioned_partitions.map(_._2).filter(!_.isEmpty)
     val new_partitions = (case_a_partitions ++ case_b_partitions).sorted(partitionOrder)
     // Prevent combinational memory explosion; if two partitions are equal, keep only one
     // Note: AddressSets in a port are sorted, and ports in a partition are sorted.
@@ -106,9 +119,9 @@ object AddressDecoder
       val score = bitScore(result)
       (score, bit, result)
     }
-    val (bestScore, bestBit, bestPartitions) = candidates.min(Ordering.by[(Int, BigInt, Partitions), Int](_._1))
+    val (bestScore, bestBit, bestPartitions) = candidates.min(Ordering.by[(Seq[Int], BigInt, Partitions), Iterable[Int]](_._1.toIterable))
     if (debug) println("=> Selected bit 0x%x".format(bestBit))
-    if (bestScore < 2*bigValue) {
+    if (bestScore(0) <= 1) {
       if (debug) println("---")
       Seq(bestBit)
     } else {

src/main/scala/uncore/tilelink2/Parameters.scala

@@ -98,6 +98,9 @@ case class AddressSet(base: BigInt, mask: BigInt) extends Ordered[AddressSet]
   // A strided slave serves discontiguous ranges
   def strided = alignment1 != mask
 
+  // Widen the match function to ignore all bits in imask
+  def widen(imask: BigInt) = AddressSet(base & ~imask, mask | imask)
+
   // AddressSets have one natural Ordering (the containment order)
   def compare(x: AddressSet) = {
     val primary   = (this.base - x.base).signum // smallest address first

src/main/scala/uncore/tilelink2/RegMapper.scala

@@ -2,8 +2,8 @@
 
 package uncore.tilelink2
 
-import Chisel._
-import chisel3.util.{Irrevocable, IrrevocableIO}
+import chisel3._
+import chisel3.util._
 
 // A bus agnostic register interface to a register-based device
 
@@ -36,6 +36,23 @@ object RegMapper
     regmap.combinations(2).foreach { case Seq((reg1, _), (reg2, _)) =>
       require (reg1 != reg2)
     }
+    // Don't be an asshole...
+    regmap.foreach { reg => require (reg._1 >= 0) }
+    // Make sure registers fit
+    val inParams = in.bits.params
+    val inBits = inParams.indexBits
+    assert (regmap.map(_._1).max < (1 << inBits))
+
+    val out = Wire(Irrevocable(new RegMapperOutput(inParams)))
+    val front = Wire(Irrevocable(new RegMapperInput(inParams)))
+    front.bits := in.bits
+
+    // Must this device pipeline the control channel?
+    val pipelined = regmap.map(_._2.map(_.pipelined)).flatten.reduce(_ || _)
+    val depth = concurrency.getOrElse(if (pipelined) 1 else 0)
+    require (depth >= 0)
+    require (!pipelined || depth > 0)
+    val back = if (depth > 0) Queue(front, depth, pipe = depth == 1) else front
 
     // Convert to and from Bits
     def toBits(x: Int, tail: List[Boolean] = List.empty): List[Boolean] =
@@ -44,36 +61,33 @@ object RegMapper
 
     // Find the minimal mask that can decide the register map
     val mask = AddressDecoder(regmap.map(_._1))
+    val maskMatch = ~UInt(mask, width = inBits)
     val maskFilter = toBits(mask)
     val maskBits = maskFilter.filter(x => x).size
 
     // Calculate size and indexes into the register map
-    val endIndex = 1 << log2Ceil(regmap.map(_._1).max+1)
-    val params = RegMapperParams(log2Up(endIndex), bytes, in.bits.params.extraBits)
     val regSize = 1 << maskBits
     def regIndexI(x: Int) = ofBits((maskFilter zip toBits(x)).filter(_._1).map(_._2))
     def regIndexU(x: UInt) = if (maskBits == 0) UInt(0) else
       Cat((maskFilter zip x.toBools).filter(_._1).map(_._2).reverse)
 
+    // Protection flag for undefined registers
+    val iRightReg = Array.fill(regSize) { Bool(true) }
+    val oRightReg = Array.fill(regSize) { Bool(true) }
+
     // Flatten the regmap into (RegIndex:Int, Offset:Int, field:RegField)
     val flat = regmap.map { case (reg, fields) =>
       val offsets = fields.scanLeft(0)(_ + _.width).init
       val index = regIndexI(reg)
+      val uint = UInt(reg, width = inBits)
+      if (undefZero) {
+        iRightReg(index) = ((front.bits.index ^ uint) & maskMatch) === UInt(0)
+        oRightReg(index) = ((back .bits.index ^ uint) & maskMatch) === UInt(0)
+      }
       // println("mapping 0x%x -> 0x%x for 0x%x/%d".format(reg, index, mask, maskBits))
       (offsets zip fields) map { case (o, f) => (index, o, f) }
     }.flatten
 
-    val out = Wire(Irrevocable(new RegMapperOutput(params)))
-    val front = Wire(Irrevocable(new RegMapperInput(params)))
-    front.bits := in.bits
-
-    // Must this device pipeline the control channel?
-    val pipelined = flat.map(_._3.pipelined).reduce(_ || _)
-    val depth = concurrency.getOrElse(if (pipelined) 1 else 0)
-    require (depth >= 0)
-    require (!pipelined || depth > 0)
-    val back = if (depth > 0) Queue(front, depth, pipe = depth == 1) else front
-
     // Forward declaration of all flow control signals
     val rivalid = Wire(Vec(flat.size, Bool()))
     val wivalid = Wire(Vec(flat.size, Bool()))
@@ -122,10 +136,10 @@ object RegMapper
     }
 
     // Is the selected register ready?
-    val rifireMux = Vec(rifire.map(_.reduce(_ && _)))
-    val wifireMux = Vec(wifire.map(_.reduce(_ && _)))
-    val rofireMux = Vec(rofire.map(_.reduce(_ && _)))
-    val wofireMux = Vec(wofire.map(_.reduce(_ && _)))
+    val rifireMux = Vec(rifire.zipWithIndex.map { case (seq, i) => !iRightReg(i) || seq.reduce(_ && _)})
+    val wifireMux = Vec(wifire.zipWithIndex.map { case (seq, i) => !iRightReg(i) || seq.reduce(_ && _)})
+    val rofireMux = Vec(rofire.zipWithIndex.map { case (seq, i) => !oRightReg(i) || seq.reduce(_ && _)})
+    val wofireMux = Vec(wofire.zipWithIndex.map { case (seq, i) => !oRightReg(i) || seq.reduce(_ && _)})
     val iindex = regIndexU(front.bits.index)
     val oindex = regIndexU(back .bits.index)
     val iready = Mux(front.bits.read, rifireMux(iindex), wifireMux(iindex))
@@ -138,8 +152,8 @@ object RegMapper
     out.valid   := back.valid  && oready
 
     // Which register is touched?
-    val frontSel = UIntToOH(iindex)
-    val backSel  = UIntToOH(oindex)
+    val frontSel = UIntToOH(iindex) & Cat(iRightReg.reverse)
+    val backSel  = UIntToOH(oindex) & Cat(oRightReg.reverse)
 
     // Include the per-register one-hot selected criteria
     for (reg <- 0 until regSize) {
@@ -159,9 +173,9 @@ object RegMapper
     }
 
     out.bits.read  := back.bits.read
-    out.bits.data  := Vec(dataOut)(oindex)
+    out.bits.data  := Mux(Vec(oRightReg)(oindex), Vec(dataOut)(oindex), UInt(0))
     out.bits.extra := back.bits.extra
 
-    (endIndex, out)
+    out
   }
 }

src/main/scala/uncore/tilelink2/RegisterRouter.scala

@@ -27,7 +27,7 @@ class TLRegisterNode(address: AddressSet, concurrency: Option[Int] = None, beatB
     val (sourceEnd, sourceOff) = (edge.bundle.sourceBits + sizeEnd, sizeEnd)
     val (addrLoEnd, addrLoOff) = (log2Up(beatBytes)      + sourceEnd, sourceEnd)
 
-    val params = RegMapperParams(log2Up(address.mask+1), beatBytes, addrLoEnd)
+    val params = RegMapperParams(log2Up((address.mask+1)/beatBytes), beatBytes, addrLoEnd)
     val in = Wire(Decoupled(new RegMapperInput(params)))
     in.bits.read  := a.bits.opcode === TLMessages.Get
     in.bits.index := a.bits.addr_hi
@@ -36,10 +36,7 @@ class TLRegisterNode(address: AddressSet, concurrency: Option[Int] = None, beatB
     in.bits.extra := Cat(edge.addr_lo(a.bits), a.bits.source, a.bits.size)
 
     // Invoke the register map builder
-    val (endIndex, out) = RegMapper(beatBytes, concurrency, undefZero, in, mapping:_*)
-
-    // All registers must fit inside the device address space
-    require (address.mask >= (endIndex-1)*beatBytes)
+    val out = RegMapper(beatBytes, concurrency, undefZero, in, mapping:_*)
 
     // No flow control needed
     in.valid  := a.valid

src/main/scala/uncore/tilelink2/RegisterRouterTest.scala

@@ -26,15 +26,15 @@ class RRTestCombinational(val bits: Int, rvalid: Bool => Bool, wready: Bool => B
     val wdata  = UInt(INPUT, width = bits)
   }
 
-  val rfire = io.rvalid && io.rready
-  val wfire = io.wvalid && io.wready
   val reg = Reg(UInt(width = bits))
 
-  io.rvalid := rvalid(rfire)
-  io.wready := wready(wfire)
+  val rvalid_s = rvalid(io.rready)
+  val wready_s = wready(io.wvalid)
+  io.rvalid := rvalid_s
+  io.wready := wready_s
 
   io.rdata := reg
-  when (wfire) { reg := io.wdata }
+  when (io.wvalid && wready_s) { reg := io.wdata }
 }
 
 object RRTestCombinational
@@ -43,19 +43,19 @@ object RRTestCombinational
 
   def always: Bool => Bool = _ => Bool(true)
 
-  def random: Bool => Bool = { fire =>
+  def random: Bool => Bool = { ready =>
     seed = seed + 1
     val lfsr = LFSR16Seed(seed)
-    val reg = RegInit(Bool(true))
-    reg := Mux(reg, !fire, lfsr(0) && lfsr(1))
-    reg
+    val valid = RegInit(Bool(true))
+    valid := Mux(valid, !ready, lfsr(0) && lfsr(1))
+    valid
   }
 
-  def delay(x: Int): Bool => Bool = { fire =>
+  def delay(x: Int): Bool => Bool = { ready =>
     val reg = RegInit(UInt(0, width = log2Ceil(x+1)))
-    val ready = reg === UInt(0)
-    reg := Mux(fire, UInt(x), Mux(ready, UInt(0), reg - UInt(1)))
-    ready
+    val valid = reg === UInt(0)
+    reg := Mux(ready && valid, UInt(x), Mux(valid, UInt(0), reg - UInt(1)))
+    valid
   }
 
   def combo(bits: Int, rvalid: Bool => Bool, wready: Bool => Bool): RegField = {