xref: /XiangShan/src/main/scala/xiangshan/backend/trace/TraceBuffer.scala (revision e836c7705c53f8360816d56db7f6d37725aad2a6) 
1package xiangshan.backend.trace
2
3import chisel3._
4import chisel3.util._
5import org.chipsalliance.cde.config.Parameters
6import utility.{CircularQueuePtr, HasCircularQueuePtrHelper}
7import xiangshan.{HasXSParameter, XSCoreParamsKey}
8
9class TraceBuffer(implicit val p: Parameters) extends Module
10  with HasXSParameter
11  with HasCircularQueuePtrHelper {
12
13  val io = IO(new Bundle {
14    val in = new Bundle{
15      val fromEncoder = Input(new FromEncoder)
16      val fromRob     = Flipped(new TraceBundle(hasIaddr = false, CommitWidth, IretireWidthCompressed))
17    }
18    val out = new Bundle { // output groups to pcMem
19      val blockCommit = Output(Bool())
20      val groups = new TraceBundle(hasIaddr = false, TraceGroupNum, IretireWidthCompressed)
21    }
22  })
23
24  // buffer: compress info from robCommit
25  val traceEntries = Reg(Vec(CommitWidth, ValidIO(new TraceBlock(false, IretireWidthCompressed))))
26  val blockCommit = RegInit(false.B) // to rob
27
28  /**
29   * compress, update blocks
30   */
31  val inValidVec = VecInit(io.in.fromRob.blocks.map(_.valid))
32  val inTypeIsNotNoneVec = VecInit(io.in.fromRob.blocks.map(block => Itype.isNotNone(block.bits.tracePipe.itype)))
33  val needPcVec = Wire(Vec(CommitWidth, Bool()))
34  for(i <- 0 until CommitWidth) {
35    val rightHasValid = if(i == CommitWidth - 1) false.B  else (inValidVec.asUInt(CommitWidth-1, i+1).orR)
36    needPcVec(i) := inValidVec(i) & (inTypeIsNotNoneVec(i) || !rightHasValid) & !blockCommit
37  }
38
39  val blocksUpdate = WireInit(io.in.fromRob.blocks)
40  for(i <- 1 until CommitWidth){
41    when(!needPcVec(i-1)){
42      blocksUpdate(i).bits.tracePipe.iretire := blocksUpdate(i - 1).bits.tracePipe.iretire + io.in.fromRob.blocks(i).bits.tracePipe.iretire
43      blocksUpdate(i).bits.ftqOffset.get := blocksUpdate(i - 1).bits.ftqOffset.get
44      blocksUpdate(i).bits.ftqIdx.get := blocksUpdate(i - 1).bits.ftqIdx.get
45     }
46  }
47
48  /**
49   * enq to traceEntries
50   */
51  val countVec = VecInit((0 until CommitWidth).map(i => PopCount(needPcVec.asUInt(i, 0))))
52  val numNeedPc = countVec(CommitWidth-1)
53
54  val enqPtr = RegInit(TracePtr(false.B, 0.U))
55  val deqPtr = RegInit(TracePtr(false.B, 0.U))
56  val deqPtrPre = RegNext(deqPtr)
57  val enqPtrNext = WireInit(enqPtr)
58  val deqPtrNext = WireInit(deqPtr)
59  enqPtr := enqPtrNext
60  deqPtr := deqPtrNext
61  val canNotTraceAll = distanceBetween(enqPtrNext, deqPtrNext) > 0.U
62  blockCommit := io.in.fromEncoder.enable && (canNotTraceAll || io.in.fromEncoder.stall)
63
64  enqPtrNext := enqPtr + numNeedPc
65  deqPtrNext := Mux(deqPtr + TraceGroupNum.U > enqPtrNext, enqPtrNext, deqPtr + TraceGroupNum.U)
66
67  val traceIdxVec = VecInit(countVec.map(count => (enqPtr + count - 1.U).value))
68  for(i <- 0 until CommitWidth){
69    when(needPcVec(i)){
70      traceEntries(traceIdxVec(i)) := blocksUpdate(i)
71    }
72  }
73
74  /**
75   * deq from traceEntries
76   */
77  val blockOut = WireInit(0.U.asTypeOf(io.out.groups))
78  for(i <- 0 until TraceGroupNum) {
79    when(deqPtrPre + i.U < enqPtr) {
80      blockOut.blocks(i) := traceEntries((deqPtrPre + i.U).value)
81    } .otherwise {
82      blockOut.blocks(i).valid := false.B
83    }
84  }
85
86  io.out.blockCommit := blockCommit
87  io.out.groups := blockOut
88
89  if(backendParams.debugEn){
90    dontTouch(countVec)
91    dontTouch(numNeedPc)
92    dontTouch(traceIdxVec)
93  }
94}
95
96class TracePtr(entries: Int) extends CircularQueuePtr[TracePtr](
97  entries
98) with HasCircularQueuePtrHelper {
99
100  def this()(implicit p: Parameters) = this(p(XSCoreParamsKey).CommitWidth)
101
102}
103
104object TracePtr {
105  def apply(f: Bool, v: UInt)(implicit p: Parameters): TracePtr = {
106    val ptr = Wire(new TracePtr)
107    ptr.flag := f
108    ptr.value := v
109    ptr
110  }
111}
112