xref: /XiangShan/src/main/scala/xiangshan/backend/Backend.scala (revision 66314a3840e5ebe6cc81ca4725bde95942f67489) 
1package xiangshan.backend
2
3import bus.simplebus.SimpleBusUC
4import chisel3._
5import chisel3.util._
6import chisel3.util.experimental.BoringUtils
7import noop.MemMMUIO
8import xiangshan._
9import xiangshan.backend.decode.{DecodeBuffer, DecodeStage}
10import xiangshan.backend.rename.Rename
11import xiangshan.backend.brq.Brq
12import xiangshan.backend.dispatch.Dispatch
13import xiangshan.backend.exu._
14import xiangshan.backend.fu.FunctionUnit
15import xiangshan.backend.issue.IssueQueue
16import xiangshan.backend.regfile.{Regfile, RfWritePort}
17import xiangshan.backend.roq.Roq
18
19
20/** Backend Pipeline:
21  * Decode -> Rename -> Dispatch-1 -> Dispatch-2 -> Issue -> Exe
22  */
23class Backend(implicit val p: XSConfig) extends XSModule
24  with NeedImpl {
25  val io = IO(new Bundle {
26    val dmem = new SimpleBusUC(addrBits = VAddrBits)
27    val memMMU = Flipped(new MemMMUIO)
28    val frontend = Flipped(new FrontendToBackendIO)
29  })
30
31
32  val aluExeUnits = Array.tabulate(exuParameters.AluCnt)(_ => Module(new AluExeUnit))
33  val jmpExeUnit = Module(new JmpExeUnit)
34  val mulExeUnits = Array.tabulate(exuParameters.MulCnt)(_ => Module(new MulExeUnit))
35  val mduExeUnits = Array.tabulate(exuParameters.MduCnt)(_ => Module(new MulDivExeUnit))
36  //  val fmacExeUnits = Array.tabulate(exuParameters.FmacCnt)(_ => Module(new Fmac))
37  //  val fmiscExeUnits = Array.tabulate(exuParameters.FmiscCnt)(_ => Module(new Fmisc))
38  //  val fmiscDivSqrtExeUnits = Array.tabulate(exuParameters.FmiscDivSqrtCnt)(_ => Module(new FmiscDivSqrt))
39  val lsuExeUnits = Array.tabulate(exuParameters.StuCnt)(_ => Module(new LsExeUnit))
40  val exeUnits = jmpExeUnit +: (aluExeUnits ++ mulExeUnits ++ mduExeUnits ++ lsuExeUnits)
41  exeUnits.foreach(_.io.dmem := DontCare)
42  exeUnits.foreach(_.io.scommit := DontCare)
43
44  val decode = Module(new DecodeStage)
45  val brq = Module(new Brq)
46  val decBuf = Module(new DecodeBuffer)
47  val rename = Module(new Rename)
48  val dispatch = Module(new Dispatch(exeUnits.map(_.config)))
49  val roq = Module(new Roq)
50  val intRf = Module(new Regfile(
51    numReadPorts = NRReadPorts,
52    numWirtePorts = NRWritePorts,
53    hasZero = true
54  ))
55  val fpRf = Module(new Regfile(
56    numReadPorts = NRReadPorts,
57    numWirtePorts = NRWritePorts,
58    hasZero = false
59  ))
60
61  // backend redirect, flush pipeline
62  val redirect = Mux(roq.io.redirect.valid, roq.io.redirect, brq.io.redirect)
63
64  val redirectInfo = Wire(new RedirectInfo)
65  // exception or misprediction
66  redirectInfo.valid := roq.io.redirect.valid || brq.io.out.valid
67  redirectInfo.misPred := !roq.io.redirect.valid && brq.io.redirect.valid
68  redirectInfo.redirect := redirect.bits
69
70  var iqInfo = new StringBuilder
71  val issueQueues = exeUnits.zipWithIndex.map({ case (eu, i) =>
72    def needBypass(cfg: ExuConfig): Boolean = cfg.enableBypass
73
74    val bypassCnt = exeUnits.map(_.config).count(needBypass)
75    def needWakeup(cfg: ExuConfig): Boolean =
76      (cfg.readIntRf && cfg.writeIntRf) || (cfg.readFpRf && cfg.writeFpRf)
77
78    val wakeupCnt = exeUnits.map(_.config).count(needWakeup)
79    assert(!(needBypass(eu.config) && !needWakeup(eu.config))) // needBypass but dont needWakeup is not allowed
80    val iq = Module(new IssueQueue(
81      eu.config,
82      wakeupCnt,
83      bypassCnt,
84      eu.config.enableBypass,
85      fifo = eu.config.supportedFuncUnits.contains(FunctionUnit.lsuCfg)
86    ))
87    iq.io.redirect <> redirect
88    iq.io.numExist <> dispatch.io.numExist(i)
89    iq.io.enqCtrl <> dispatch.io.enqIQCtrl(i)
90    iq.io.enqData <> dispatch.io.enqIQData(i)
91    for(
92      (wakeUpPort, exuOut) <-
93      iq.io.wakeUpPorts.zip(exeUnits.filter(e => needWakeup(e.config)).map(_.io.out))
94    ){
95      wakeUpPort.bits := exuOut.bits
96      wakeUpPort.valid := exuOut.valid
97    }
98    iqInfo ++= {
99      s"[$i] ${eu.name} Queue wakeupCnt:$wakeupCnt bypassCnt:$bypassCnt" +
100        s" Supported Function:[" +
101        s"${
102          eu.config.supportedFuncUnits.map(
103            fu => FuType.functionNameMap(fu.fuType.litValue())).mkString(", "
104          )
105        }]\n"
106    }
107    eu.io.in <> iq.io.deq
108    eu.io.redirect <> redirect
109    iq
110  })
111
112  val bypassQueues = issueQueues.filter(_.enableBypass)
113  val bypassUnits = exeUnits.filter(_.config.enableBypass)
114  issueQueues.foreach(iq => {
115    for (i <- iq.io.bypassUops.indices) {
116      iq.io.bypassData(i).bits := bypassUnits(i).io.out.bits
117      iq.io.bypassData(i).valid := bypassUnits(i).io.out.valid
118    }
119    iq.io.bypassUops <> bypassQueues.map(_.io.selectedUop)
120  })
121
122  lsuExeUnits.foreach(_.io.dmem <> io.dmem)
123  lsuExeUnits.foreach(_.io.scommit <> roq.io.scommit)
124
125  io.frontend.redirectInfo <> redirectInfo
126  io.frontend.commits <> roq.io.commits
127
128  decode.io.in <> io.frontend.cfVec
129  brq.io.roqRedirect <> roq.io.redirect
130  brq.io.enqReqs <> decode.io.toBrq
131  for ((x, y) <- brq.io.exuRedirect.zip(exeUnits.filter(_.config.hasRedirect))) {
132    x.bits := y.io.out.bits
133    x.valid := y.io.out.fire() && y.io.out.bits.redirectValid
134  }
135  decode.io.brTags <> brq.io.brTags
136  decBuf.io.redirect <> redirect
137  decBuf.io.in <> decode.io.out
138
139  rename.io.redirect <> redirect
140  rename.io.roqCommits <> roq.io.commits
141  rename.io.in <> decBuf.io.out
142  rename.io.intRfReadAddr <> dispatch.io.readIntRf.map(_.addr)
143  rename.io.fpRfReadAddr <> dispatch.io.readFpRf.map(_.addr)
144  rename.io.intPregRdy <> dispatch.io.intPregRdy
145  rename.io.fpPregRdy <> dispatch.io.fpPregRdy
146
147  dispatch.io.redirect <> redirect
148  dispatch.io.fromRename <> rename.io.out
149
150  roq.io.brqRedirect <> brq.io.redirect
151  roq.io.dp1Req <> dispatch.io.toRoq
152  dispatch.io.roqIdxs <> roq.io.roqIdxs
153
154  intRf.io.readPorts <> dispatch.io.readIntRf
155  fpRf.io.readPorts <> dispatch.io.readFpRf
156
157  val exeWbReqs = exeUnits.map(_.io.out)
158
159  val wbIntIdx = exeUnits.zipWithIndex.filter(_._1.config.writeIntRf).map(_._2)
160  val wbFpIdx = exeUnits.zipWithIndex.filter(_._1.config.writeFpRf).map(_._2)
161
162  val wbu = Module(new Wbu(wbIntIdx, wbFpIdx))
163  wbu.io.in <> exeWbReqs
164
165  val wbIntResults = wbu.io.toIntRf
166  val wbFpResults = wbu.io.toFpRf
167
168  def exuOutToRfWrite(x: Valid[ExuOutput]): RfWritePort = {
169    val rfWrite = Wire(new RfWritePort)
170    rfWrite.wen := x.valid
171    rfWrite.addr := x.bits.uop.pdest
172    rfWrite.data := x.bits.data
173    rfWrite
174  }
175
176  intRf.io.writePorts <> wbIntResults.map(exuOutToRfWrite)
177  fpRf.io.writePorts <> wbFpResults.map(exuOutToRfWrite)
178
179  rename.io.wbIntResults <> wbIntResults
180  rename.io.wbFpResults <> wbFpResults
181
182  roq.io.exeWbResults.take(exeWbReqs.length).zip(wbu.io.toRoq).foreach(x => x._1 := x._2)
183  roq.io.exeWbResults.last := brq.io.out
184
185
186  // TODO: Remove sink and source
187  val tmp = WireInit(0.U)
188  val sinks = Array[String](
189    "DTLBFINISH",
190    "DTLBPF",
191    "DTLBENABLE",
192    "perfCntCondMdcacheLoss",
193    "perfCntCondMl2cacheLoss",
194    "perfCntCondMdcacheHit",
195    "lsuMMIO",
196    "perfCntCondMl2cacheHit",
197    "perfCntCondMl2cacheReq",
198    "mtip",
199    "perfCntCondMdcacheReq",
200    "meip"
201  )
202  for (s <- sinks) {
203    BoringUtils.addSink(tmp, s)
204  }
205
206  val debugIntReg, debugFpReg = WireInit(VecInit(Seq.fill(32)(0.U(XLEN.W))))
207  BoringUtils.addSink(debugIntReg, "DEBUG_INT_ARCH_REG")
208  BoringUtils.addSink(debugFpReg, "DEBUG_FP_ARCH_REG")
209  val debugArchReg = WireInit(VecInit(debugIntReg ++ debugFpReg))
210  if (!p.FPGAPlatform) {
211    BoringUtils.addSource(debugArchReg, "difftestRegs")
212  }
213
214  print(iqInfo)
215
216}
217