xref: /XiangShan/src/main/scala/xiangshan/backend/exu/ExeUnit.scala (revision 9c890e56f8d2273bd80bf71c930986b28543cda8)

/***************************************************************************************
* Copyright (c) 2020-2021 Institute of Computing Technology, Chinese Academy of Sciences
* Copyright (c) 2020-2021 Peng Cheng Laboratory
*
* XiangShan is licensed under Mulan PSL v2.
* You can use this software according to the terms and conditions of the Mulan PSL v2.
* You may obtain a copy of Mulan PSL v2 at:
*          http://license.coscl.org.cn/MulanPSL2
*
* THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
* EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
* MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
*
* See the Mulan PSL v2 for more details.
***************************************************************************************/

package xiangshan.backend.exu

import org.chipsalliance.cde.config.Parameters
import chisel3._
import chisel3.experimental.hierarchy.{Definition, instantiable}
import chisel3.util._
import freechips.rocketchip.diplomacy.{LazyModule, LazyModuleImp}
import utility.DelayN
import utils._
import xiangshan.backend.fu.{CSRFileIO, FenceIO, FuncUnitInput}
import xiangshan.backend.Bundles.{ExuInput, ExuOutput, MemExuInput, MemExuOutput}
import xiangshan.{FPUCtrlSignals, HasXSParameter, Redirect, XSBundle, XSModule}
import xiangshan.backend.datapath.WbConfig.{PregWB, _}
import xiangshan.backend.fu.FuType

class ExeUnitIO(params: ExeUnitParams)(implicit p: Parameters) extends XSBundle {
  val flush = Flipped(ValidIO(new Redirect()))
  val in = Flipped(DecoupledIO(new ExuInput(params)))
  val out = DecoupledIO(new ExuOutput(params))
  val csrio = if (params.hasCSR) Some(new CSRFileIO) else None
  val fenceio = if (params.hasFence) Some(new FenceIO) else None
  val frm = if (params.needSrcFrm) Some(Input(UInt(3.W))) else None
}

class ExeUnit(val exuParams: ExeUnitParams)(implicit p: Parameters) extends LazyModule {
  override def shouldBeInlined: Boolean = false

  lazy val module = new ExeUnitImp(this)(p, exuParams)
}

class ExeUnitImp(
  override val wrapper: ExeUnit
)(implicit
  p: Parameters, exuParams: ExeUnitParams
) extends LazyModuleImp(wrapper) with HasXSParameter{
  private val fuCfgs = exuParams.fuConfigs

  val io = IO(new ExeUnitIO(exuParams))

  val funcUnit = fuCfgs.map(cfg => {
    assert(cfg.fuGen != null, cfg.name + "Cfg'fuGen is null !!!")
    val module = cfg.fuGen(p, cfg)
    module
  })

  val funcUnits = fuCfgs.zip(funcUnit).map{case(cfg, fu) =>
    val clk_en = WireInit(false.B)
    val fuVld_en = WireInit(false.B)
    val fuVld_en_reg = RegInit(false.B)
    val uncer_en_reg = RegInit(false.B)

    val lat0 = FuType.isLat0(io.in.bits.fuType)
    val latN = FuType.isLatN(io.in.bits.fuType)
    val uncerLat = FuType.isUncerLat(io.in.bits.fuType)

    def lat: Int = cfg.latency.latencyVal.getOrElse(0)

    val fuVldVec = (io.in.valid && latN) +: Seq.fill(lat)(RegInit(false.B))
    val fuRdyVec = Seq.fill(lat)(Wire(Bool())) :+ io.out.ready

    for (i <- 0 until lat) {
      fuRdyVec(i) := !fuVldVec(i + 1) || fuRdyVec(i + 1)
    }

    for (i <- 1 to lat) {
      when(fuRdyVec(i - 1) && fuVldVec(i - 1)) {
        fuVldVec(i) := fuVldVec(i - 1)
      }.elsewhen(fuRdyVec(i)) {
        fuVldVec(i) := false.B
      }
    }
    fuVld_en := fuVldVec.map(v => v).reduce(_ || _)
    fuVld_en_reg := fuVld_en

    when(uncerLat && io.in.fire) {
      uncer_en_reg := true.B
    }.elsewhen(uncerLat && io.out.fire) {
      uncer_en_reg := false.B
    }

    when(lat0 && io.in.fire) {
      clk_en := true.B
    }.elsewhen(latN && fuVld_en || fuVld_en_reg) {
      clk_en := true.B
    }.elsewhen(uncerLat && io.in.fire || uncer_en_reg) {
      clk_en := true.B
    }

    if (cfg.ckAlwaysEn) {
      clk_en := true.B
    }

    val clk_gate = Module(new ClockGate)
    clk_gate.io.TE := false.B
    clk_gate.io.E := clk_en
    clk_gate.io.CK := clock
    fu.clock := clk_gate.io.Q
    fu
  }

  val busy = RegInit(false.B)
  val robIdx = RegEnable(io.in.bits.robIdx, io.in.fire)
  when (io.in.fire && io.in.bits.robIdx.needFlush(io.flush)) {
    busy := false.B
  }.elsewhen(busy && robIdx.needFlush(io.flush)){
    busy := false.B
  }.elsewhen(io.out.fire) {
    busy := false.B
  }.elsewhen(io.in.fire) {
    busy := true.B
  }

  if (exuParams.latencyCertain){
    busy := false.B
  }

  exuParams.wbPortConfigs.map{
    x => x match {
      case IntWB(port, priority) => assert(priority >= 0 && priority <= 2,
        s"${exuParams.name}: WbPort must priority=0 or priority=1")
      case VfWB (port, priority) => assert(priority >= 0 && priority <= 2,
        s"${exuParams.name}: WbPort must priority=0 or priority=1")
      case _ =>
    }
  }
  val intWbPort = exuParams.getIntWBPort
  if (intWbPort.isDefined){
    val sameIntPortExuParam = backendParams.allExuParams.filter(_.getIntWBPort.isDefined)
      .filter(_.getIntWBPort.get.port == intWbPort.get.port)
    val samePortOneCertainOneUncertain = sameIntPortExuParam.map(_.latencyCertain).contains(true) && sameIntPortExuParam.map(_.latencyCertain).contains(false)
    if (samePortOneCertainOneUncertain) sameIntPortExuParam.map(samePort =>
      samePort.wbPortConfigs.map(
        x => x match {
          case IntWB(port, priority) => {
            if (!samePort.latencyCertain) assert(priority == sameIntPortExuParam.size - 1,
              s"${samePort.name}: IntWbPort $port must latencyCertain priority=0 or latencyUnCertain priority=max(${sameIntPortExuParam.size - 1})")
            // Certain latency can be handled by WbBusyTable, so there is no need to limit the exu's WB priority
          }
          case _ =>
        }
      )
    )
  }
  val vfWbPort = exuParams.getVfWBPort
  if (vfWbPort.isDefined) {
    val sameVfPortExuParam = backendParams.allExuParams.filter(_.getVfWBPort.isDefined)
      .filter(_.getVfWBPort.get.port == vfWbPort.get.port)
    val samePortOneCertainOneUncertain = sameVfPortExuParam.map(_.latencyCertain).contains(true) && sameVfPortExuParam.map(_.latencyCertain).contains(false)
    if (samePortOneCertainOneUncertain)  sameVfPortExuParam.map(samePort =>
      samePort.wbPortConfigs.map(
        x => x match {
          case VfWB(port, priority) => {
            if (!samePort.latencyCertain) assert(priority == sameVfPortExuParam.size - 1,
              s"${samePort.name}: VfWbPort $port must latencyCertain priority=0 or latencyUnCertain priority=max(${sameVfPortExuParam.size - 1})")
            // Certain latency can be handled by WbBusyTable, so there is no need to limit the exu's WB priority
          }
          case _ =>
        }
      )
    )
  }
  if(backendParams.debugEn) {
    dontTouch(io.out.ready)
  }
  // rob flush --> funcUnits
  funcUnits.zipWithIndex.foreach { case (fu, i) =>
    fu.io.flush <> io.flush
  }

  def acceptCond(input: ExuInput): Seq[Bool] = {
    input.params.fuConfigs.map(_.fuSel(input))
  }

  val in1ToN = Module(new Dispatcher(new ExuInput(exuParams), funcUnits.length, acceptCond))

  // ExeUnit.in <---> Dispatcher.in
  in1ToN.io.in.valid := io.in.valid && !busy
  in1ToN.io.in.bits := io.in.bits
  io.in.ready := !busy && in1ToN.io.in.ready

  // Dispatcher.out <---> FunctionUnits
  in1ToN.io.out.zip(funcUnits.map(_.io.in)).foreach {
    case (source: DecoupledIO[ExuInput], sink: DecoupledIO[FuncUnitInput]) =>
      sink.valid := source.valid
      source.ready := sink.ready

      sink.bits.data.src.zip(source.bits.src).foreach { case(fuSrc, exuSrc) => fuSrc := exuSrc }
      sink.bits.data.pc          .foreach(x => x := source.bits.pc.get)
      sink.bits.data.imm         := source.bits.imm
      sink.bits.ctrl.fuOpType    := source.bits.fuOpType
      sink.bits.ctrl.robIdx      := source.bits.robIdx
      sink.bits.ctrl.pdest       := source.bits.pdest
      sink.bits.ctrl.rfWen       .foreach(x => x := source.bits.rfWen.get)
      sink.bits.ctrl.fpWen       .foreach(x => x := source.bits.fpWen.get)
      sink.bits.ctrl.vecWen      .foreach(x => x := source.bits.vecWen.get)
      sink.bits.ctrl.flushPipe   .foreach(x => x := source.bits.flushPipe.get)
      sink.bits.ctrl.preDecode   .foreach(x => x := source.bits.preDecode.get)
      sink.bits.ctrl.ftqIdx      .foreach(x => x := source.bits.ftqIdx.get)
      sink.bits.ctrl.ftqOffset   .foreach(x => x := source.bits.ftqOffset.get)
      sink.bits.ctrl.predictInfo .foreach(x => x := source.bits.predictInfo.get)
      sink.bits.ctrl.fpu         .foreach(x => x := source.bits.fpu.get)
      sink.bits.ctrl.vpu         .foreach(x => x := source.bits.vpu.get)
      sink.bits.perfDebugInfo    := source.bits.perfDebugInfo
  }

  private val fuOutValidOH = funcUnits.map(_.io.out.valid)
  XSError(PopCount(fuOutValidOH) > 1.U, p"fuOutValidOH ${Binary(VecInit(fuOutValidOH).asUInt)} should be one-hot)\n")
  private val fuOutBitsVec = funcUnits.map(_.io.out.bits)
  private val fuRedirectVec: Seq[Option[ValidIO[Redirect]]] = funcUnits.map(_.io.out.bits.res.redirect)

  // Assume that one fu can only write int or fp or vec,
  // otherwise, wenVec should be assigned to wen in fu.
  private val fuIntWenVec = funcUnits.map(x => x.cfg.writeIntRf.B && x.io.out.bits.ctrl.rfWen.getOrElse(false.B))
  private val fuFpWenVec  = funcUnits.map(x => x.cfg.writeFpRf.B  && x.io.out.bits.ctrl.fpWen.getOrElse(false.B))
  private val fuVecWenVec = funcUnits.map(x => x.cfg.writeVecRf.B && x.io.out.bits.ctrl.vecWen.getOrElse(false.B))
  // FunctionUnits <---> ExeUnit.out
  io.out.valid := Cat(fuOutValidOH).orR
  funcUnits.foreach(fu => fu.io.out.ready := io.out.ready)

  // select one fu's result
  io.out.bits.data := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.res.data))
  io.out.bits.robIdx := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.ctrl.robIdx))
  io.out.bits.pdest := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.ctrl.pdest))
  io.out.bits.intWen.foreach(x => x := Mux1H(fuOutValidOH, fuIntWenVec))
  io.out.bits.fpWen.foreach(x => x := Mux1H(fuOutValidOH, fuFpWenVec))
  io.out.bits.vecWen.foreach(x => x := Mux1H(fuOutValidOH, fuVecWenVec))
  io.out.bits.redirect.foreach(x => x := Mux1H((fuOutValidOH zip fuRedirectVec).filter(_._2.isDefined).map(x => (x._1, x._2.get))))
  io.out.bits.fflags.foreach(x => x := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.res.fflags.getOrElse(0.U.asTypeOf(io.out.bits.fflags.get)))))
  io.out.bits.wflags.foreach(x => x := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.ctrl.fpu.getOrElse(0.U.asTypeOf(new FPUCtrlSignals)).wflags)))
  io.out.bits.vxsat.foreach(x => x := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.res.vxsat.getOrElse(0.U.asTypeOf(io.out.bits.vxsat.get)))))
  io.out.bits.exceptionVec.foreach(x => x := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.ctrl.exceptionVec.getOrElse(0.U.asTypeOf(io.out.bits.exceptionVec.get)))))
  io.out.bits.flushPipe.foreach(x => x := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.ctrl.flushPipe.getOrElse(0.U.asTypeOf(io.out.bits.flushPipe.get)))))
  io.out.bits.replay.foreach(x => x := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.ctrl.replay.getOrElse(0.U.asTypeOf(io.out.bits.replay.get)))))
  io.out.bits.predecodeInfo.foreach(x => x := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.ctrl.preDecode.getOrElse(0.U.asTypeOf(io.out.bits.predecodeInfo.get)))))

  io.csrio.foreach(exuio => funcUnits.foreach(fu => fu.io.csrio.foreach{
    fuio =>
      exuio <> fuio
      fuio.exception := DelayN(exuio.exception, 2)
  }))
  io.fenceio.foreach(exuio => funcUnits.foreach(fu => fu.io.fenceio.foreach(fuio => fuio <> exuio)))
  io.frm.foreach(exuio => funcUnits.foreach(fu => fu.io.frm.foreach(fuio => fuio <> exuio)))

  // debug info
  io.out.bits.debug     := 0.U.asTypeOf(io.out.bits.debug)
  io.out.bits.debug.isPerfCnt := funcUnits.map(_.io.csrio.map(_.isPerfCnt)).map(_.getOrElse(false.B)).reduce(_ || _)
  io.out.bits.debugInfo := Mux1H(fuOutValidOH, fuOutBitsVec.map(_.perfDebugInfo))
}

class DispatcherIO[T <: Data](private val gen: T, n: Int) extends Bundle {
  val in = Flipped(DecoupledIO(gen))

  val out = Vec(n, DecoupledIO(gen))
}

class Dispatcher[T <: Data](private val gen: T, n: Int, acceptCond: T => Seq[Bool])
  (implicit p: Parameters)
  extends Module {

  val io = IO(new DispatcherIO(gen, n))

  private val acceptVec: Vec[Bool] = VecInit(acceptCond(io.in.bits))

  XSError(io.in.valid && PopCount(acceptVec) > 1.U, s"s[ExeUnit] accept vec should no more than 1, ${Binary(acceptVec.asUInt)} ")
  XSError(io.in.valid && PopCount(acceptVec) === 0.U, "[ExeUnit] there is a inst not dispatched to any fu")

  io.out.zipWithIndex.foreach { case (out, i) =>
    out.valid := acceptVec(i) && io.in.valid
    out.bits := io.in.bits
  }

  io.in.ready := Mux1H(acceptVec,io.out.map(_.ready))
}

class MemExeUnitIO (implicit p: Parameters) extends XSBundle {
  val flush = Flipped(ValidIO(new Redirect()))
  val in = Flipped(DecoupledIO(new MemExuInput()))
  val out = DecoupledIO(new MemExuOutput())
}

class MemExeUnit(exuParams: ExeUnitParams)(implicit p: Parameters) extends XSModule {
  val io = IO(new MemExeUnitIO)
  val fu = exuParams.fuConfigs.head.fuGen(p, exuParams.fuConfigs.head)
  fu.io.flush             := io.flush
  fu.io.in.valid          := io.in.valid
  io.in.ready             := fu.io.in.ready

  fu.io.in.bits.ctrl.robIdx    := io.in.bits.uop.robIdx
  fu.io.in.bits.ctrl.pdest     := io.in.bits.uop.pdest
  fu.io.in.bits.ctrl.fuOpType  := io.in.bits.uop.fuOpType
  fu.io.in.bits.data.imm       := io.in.bits.uop.imm
  fu.io.in.bits.data.src.zip(io.in.bits.src).foreach(x => x._1 := x._2)
  fu.io.in.bits.perfDebugInfo := io.in.bits.uop.debugInfo

  io.out.valid            := fu.io.out.valid
  fu.io.out.ready         := io.out.ready

  io.out.bits             := 0.U.asTypeOf(io.out.bits) // dontCare other fields
  io.out.bits.data        := fu.io.out.bits.res.data
  io.out.bits.uop.robIdx  := fu.io.out.bits.ctrl.robIdx
  io.out.bits.uop.pdest   := fu.io.out.bits.ctrl.pdest
  io.out.bits.uop.fuType  := io.in.bits.uop.fuType
  io.out.bits.uop.fuOpType:= io.in.bits.uop.fuOpType
  io.out.bits.uop.sqIdx   := io.in.bits.uop.sqIdx
  io.out.bits.uop.debugInfo := fu.io.out.bits.perfDebugInfo

  io.out.bits.debug       := 0.U.asTypeOf(io.out.bits.debug)
}