xref: /XiangShan/src/main/scala/xiangshan/frontend/IFU.scala (revision bdc12a65e7a134ee688a7f4499a4d947efa45d56)
1package xiangshan.frontend
2
3import chisel3._
4import chisel3.util._
5import chisel3.util.experimental.BoringUtils
6import device.RAMHelper
7import xiangshan._
8import utils._
9import xiangshan.cache._
10import chisel3.ExcitingUtils._
11
12trait HasIFUConst { this: XSModule =>
13  val resetVector = 0x80000000L//TODO: set reset vec
14  val groupAlign = log2Up(FetchWidth * 4 * 2)
15  def groupPC(pc: UInt): UInt = Cat(pc(VAddrBits-1, groupAlign), 0.U(groupAlign.W))
16  // each 1 bit in mask stands for 2 Bytes
17  def mask(pc: UInt): UInt = (Fill(PredictWidth * 2, 1.U(1.W)) >> pc(groupAlign - 1, 1))(PredictWidth - 1, 0)
18  def snpc(pc: UInt): UInt = pc + (PopCount(mask(pc)) << 1)
19
20  val IFUDebug = true
21}
22
23class GlobalHistoryInfo() extends XSBundle {
24  val sawNTBr = Bool()
25  val takenOnBr = Bool()
26  val saveHalfRVI = Bool()
27  def shifted = takenOnBr || sawNTBr
28  def newPtr(ptr: UInt) = Mux(shifted, ptr - 1.U, ptr)
29  implicit val name = "IFU"
30  def debug = XSDebug("[GHInfo] sawNTBr=%d, takenOnBr=%d, saveHalfRVI=%d\n", sawNTBr, takenOnBr, saveHalfRVI)
31  // override def toString(): String = "histPtr=%d, sawNTBr=%d, takenOnBr=%d, saveHalfRVI=%d".format(histPtr, sawNTBr, takenOnBr, saveHalfRVI)
32}
33
34class IFUIO extends XSBundle
35{
36  val fetchPacket = DecoupledIO(new FetchPacket)
37  val redirect = Flipped(ValidIO(new Redirect))
38  val outOfOrderBrInfo = Flipped(ValidIO(new BranchUpdateInfo))
39  val inOrderBrInfo = Flipped(ValidIO(new BranchUpdateInfo))
40  val icacheReq = DecoupledIO(new ICacheReq)
41  val icacheResp = Flipped(DecoupledIO(new ICacheResp))
42  val icacheFlush = Output(UInt(2.W))
43  val loopBufPar = Flipped(new LoopBufferParameters)
44}
45
46class IFU extends XSModule with HasIFUConst
47{
48  val io = IO(new IFUIO)
49  val bpu = BPU(EnableBPU)
50  val pd = Module(new PreDecode)
51
52  val if2_redirect, if3_redirect, if4_redirect = WireInit(false.B)
53  val if1_flush, if2_flush, if3_flush, if4_flush = WireInit(false.B)
54
55  val icacheResp = WireInit(Mux(io.loopBufPar.inLoop, io.loopBufPar.LBResp, io.icacheResp.bits))
56
57  if4_flush := io.redirect.valid || io.loopBufPar.LBredirect.valid
58  if3_flush := if4_flush || if4_redirect
59  if2_flush := if3_flush || if3_redirect
60  if1_flush := if2_flush || if2_redirect
61
62  //********************** IF1 ****************************//
63  val if1_valid = !reset.asBool && GTimer() > 500.U
64  val if1_npc = WireInit(0.U(VAddrBits.W))
65  val if2_ready = WireInit(false.B)
66  val if1_fire = if1_valid && (if2_ready || if1_flush) && (io.loopBufPar.inLoop || io.icacheReq.ready)
67
68
69  val if1_histPtr, if2_histPtr, if3_histPtr, if4_histPtr = Wire(UInt(log2Up(ExtHistoryLength).W))
70  val if2_newPtr, if3_newPtr, if4_newPtr = Wire(UInt(log2Up(ExtHistoryLength).W))
71
72  val extHist = RegInit(VecInit(Seq.fill(ExtHistoryLength)(0.U(1.W))))
73  val shiftPtr = WireInit(false.B)
74  val newPtr = Wire(UInt(log2Up(ExtHistoryLength).W))
75  val ptr = Mux(shiftPtr, newPtr, if1_histPtr)
76  val hist = Wire(Vec(HistoryLength, UInt(1.W)))
77  for (i <- 0 until HistoryLength) {
78    hist(i) := extHist(ptr + i.U)
79  }
80
81  shiftPtr := false.B
82  newPtr := if1_histPtr
83
84
85
86  val if1_GHInfo = Wire(new GlobalHistoryInfo())
87  if1_GHInfo := 0.U.asTypeOf(new GlobalHistoryInfo)
88
89  //********************** IF2 ****************************//
90  val if2_valid = RegEnable(next = if1_valid, init = false.B, enable = if1_fire)
91  val if3_ready = WireInit(false.B)
92  val if2_fire = if2_valid && if3_ready && !if2_flush
93  val if2_pc = RegEnable(next = if1_npc, init = resetVector.U, enable = if1_fire)
94  val if2_snpc = snpc(if2_pc)
95  val if2_GHInfo = RegEnable(if1_GHInfo, if1_fire)
96  val if2_predHistPtr = RegEnable(ptr, enable=if1_fire)
97  if2_ready := if2_fire || !if2_valid || if2_flush
98  when (if2_flush) { if2_valid := if1_fire }
99  .elsewhen (if1_fire) { if2_valid := if1_valid }
100  .elsewhen (if2_fire) { if2_valid := false.B }
101
102  when (RegNext(reset.asBool) && !reset.asBool) {
103    if1_npc := resetVector.U(VAddrBits.W)
104  }.elsewhen (if2_fire) {
105    if1_npc := if2_snpc
106  }.otherwise {
107    if1_npc := RegNext(if1_npc)
108  }
109
110  val if2_bp = bpu.io.out(0).bits
111  // if taken, bp_redirect should be true
112  // when taken on half RVI, we suppress this redirect signal
113  if2_redirect := if2_fire && bpu.io.out(0).valid && if2_bp.redirect && !if2_bp.saveHalfRVI
114  when (if2_redirect) {
115    if1_npc := if2_bp.target
116  }
117
118  val if2_realGHInfo = Wire(new GlobalHistoryInfo())
119  if2_realGHInfo.sawNTBr     := if2_bp.hasNotTakenBrs
120  if2_realGHInfo.takenOnBr   := if2_bp.takenOnBr
121  if2_realGHInfo.saveHalfRVI := if2_bp.saveHalfRVI
122
123  when (if2_fire && if2_realGHInfo.shifted) {
124    shiftPtr := true.B
125    newPtr := if2_newPtr
126  }
127  when (if2_realGHInfo.shifted && if2_newPtr >= ptr) {
128    hist(if2_newPtr-ptr) := if2_realGHInfo.takenOnBr.asUInt
129  }
130
131
132
133  //********************** IF3 ****************************//
134  val if3_valid = RegEnable(next = if2_valid, init = false.B, enable = if2_fire)
135  val if4_ready = WireInit(false.B)
136  val if3_fire = if3_valid && if4_ready && (io.loopBufPar.inLoop || io.icacheResp.valid) && !if3_flush
137  val if3_pc = RegEnable(if2_pc, if2_fire)
138  val if3_GHInfo = RegEnable(if2_realGHInfo, if2_fire)
139  val if3_predHistPtr = RegEnable(if2_predHistPtr, enable=if2_fire)
140  if3_ready := if3_fire || !if3_valid || if3_flush
141  when (if3_flush) { if3_valid := false.B }
142  .elsewhen (if2_fire) { if3_valid := if2_valid }
143  .elsewhen (if3_fire) { if3_valid := false.B }
144
145  val if3_bp = bpu.io.out(1).bits
146
147  val if3_realGHInfo = Wire(new GlobalHistoryInfo())
148  if3_realGHInfo.sawNTBr     := if3_bp.hasNotTakenBrs
149  if3_realGHInfo.takenOnBr   := if3_bp.takenOnBr
150  if3_realGHInfo.saveHalfRVI := if3_bp.saveHalfRVI
151
152  class PrevHalfInstr extends Bundle {
153    val valid = Bool()
154    val taken = Bool()
155    val ghInfo = new GlobalHistoryInfo()
156    val fetchpc = UInt(VAddrBits.W) // only for debug
157    val idx = UInt(VAddrBits.W) // only for debug
158    val pc = UInt(VAddrBits.W)
159    val target = UInt(VAddrBits.W)
160    val instr = UInt(16.W)
161    val ipf = Bool()
162    val newPtr = UInt(log2Up(ExtHistoryLength).W)
163  }
164
165  val if3_prevHalfInstr = RegInit(0.U.asTypeOf(new PrevHalfInstr))
166  val if4_prevHalfInstr = Wire(new PrevHalfInstr)
167  // 32-bit instr crosses 2 pages, and the higher 16-bit triggers page fault
168  val crossPageIPF = WireInit(false.B)
169  when (if4_prevHalfInstr.valid) {
170    if3_prevHalfInstr := if4_prevHalfInstr
171  }
172  val prevHalfInstr = Mux(if4_prevHalfInstr.valid, if4_prevHalfInstr, if3_prevHalfInstr)
173
174  // the previous half of RVI instruction waits until it meets its last half
175  val if3_hasPrevHalfInstr = prevHalfInstr.valid && (prevHalfInstr.pc + 2.U) === if3_pc
176  // set to invalid once consumed or redirect from backend
177  val prevHalfConsumed = if3_hasPrevHalfInstr && if3_fire || if4_flush
178  when (prevHalfConsumed) {
179    if3_prevHalfInstr.valid := false.B
180  }
181
182  // when bp signal a redirect, we distinguish between taken and not taken
183  // if taken and saveHalfRVI is true, we do not redirect to the target
184  if3_redirect := if3_fire && bpu.io.out(1).valid && (if3_hasPrevHalfInstr && prevHalfInstr.taken || if3_bp.redirect && (if3_bp.taken && !if3_bp.saveHalfRVI || !if3_bp.taken) )
185
186  when (if3_redirect) {
187    when (!(if3_hasPrevHalfInstr && prevHalfInstr.taken)) {
188      if1_npc := if3_bp.target
189      when (if3_realGHInfo.shifted){
190        shiftPtr := true.B
191        newPtr := if3_newPtr
192      }
193    }
194  }
195
196  // when it does not redirect, we still need to modify hist(wire)
197  when(if3_realGHInfo.shifted && if3_newPtr >= ptr) {
198    hist(if3_newPtr-ptr) := if3_realGHInfo.takenOnBr
199  }
200  when (if3_hasPrevHalfInstr && prevHalfInstr.ghInfo.shifted && prevHalfInstr.newPtr >= ptr) {
201    hist(prevHalfInstr.newPtr-ptr) := prevHalfInstr.ghInfo.takenOnBr
202  }
203
204  //********************** IF4 ****************************//
205  val if4_pd = RegEnable(pd.io.out, if3_fire)
206  val if4_ipf = RegEnable(icacheResp.ipf || if3_hasPrevHalfInstr && prevHalfInstr.ipf, if3_fire)
207  val if4_crossPageIPF = RegEnable(crossPageIPF, if3_fire)
208  val if4_valid = RegInit(false.B)
209  val if4_fire = if4_valid && io.fetchPacket.ready
210  val if4_pc = RegEnable(if3_pc, if3_fire)
211
212  val if4_GHInfo = RegEnable(if3_realGHInfo, if3_fire)
213  val if4_predHistPtr = RegEnable(if3_predHistPtr, enable=if3_fire)
214  if4_ready := (if4_fire || !if4_valid || if4_flush) && GTimer() > 500.U
215  when (if4_flush)     { if4_valid := false.B }
216  .elsewhen (if3_fire) { if4_valid := if3_valid }
217  .elsewhen(if4_fire)  { if4_valid := false.B }
218
219  val if4_bp = Wire(new BranchPrediction)
220  if4_bp := bpu.io.out(2).bits
221
222  val if4_realGHInfo = Wire(new GlobalHistoryInfo())
223  if4_realGHInfo.sawNTBr     := if4_bp.hasNotTakenBrs
224  if4_realGHInfo.takenOnBr   := if4_bp.takenOnBr
225  if4_realGHInfo.saveHalfRVI := if4_bp.saveHalfRVI
226
227
228  val if4_cfi_jal = if4_pd.instrs(if4_bp.jmpIdx)
229  val if4_cfi_jal_tgt = if4_pd.pc(if4_bp.jmpIdx) + Mux(if4_pd.pd(if4_bp.jmpIdx).isRVC,
230    SignExt(Cat(if4_cfi_jal(12), if4_cfi_jal(8), if4_cfi_jal(10, 9), if4_cfi_jal(6), if4_cfi_jal(7), if4_cfi_jal(2), if4_cfi_jal(11), if4_cfi_jal(5, 3), 0.U(1.W)), XLEN),
231    SignExt(Cat(if4_cfi_jal(31), if4_cfi_jal(19, 12), if4_cfi_jal(20), if4_cfi_jal(30, 21), 0.U(1.W)), XLEN))
232  if4_bp.target := Mux(if4_pd.pd(if4_bp.jmpIdx).isJal && if4_bp.taken, if4_cfi_jal_tgt, bpu.io.out(2).bits.target)
233  if4_bp.redirect := bpu.io.out(2).bits.redirect || if4_pd.pd(if4_bp.jmpIdx).isJal && if4_bp.taken && if4_cfi_jal_tgt =/= bpu.io.out(2).bits.target
234
235  if4_prevHalfInstr := 0.U.asTypeOf(new PrevHalfInstr)
236  when (bpu.io.out(2).valid && if4_fire && if4_bp.saveHalfRVI) {
237    if4_prevHalfInstr.valid := true.B
238    if4_prevHalfInstr.taken := if4_bp.taken
239    if4_prevHalfInstr.ghInfo := if4_realGHInfo
240    // Make sure shifted can work
241    if4_prevHalfInstr.ghInfo.saveHalfRVI := false.B
242    if4_prevHalfInstr.newPtr := if4_newPtr
243    if4_prevHalfInstr.fetchpc := if4_pc
244    if4_prevHalfInstr.idx := PopCount(mask(if4_pc)) - 1.U
245    if4_prevHalfInstr.pc := if4_pd.pc(if4_prevHalfInstr.idx)
246    if4_prevHalfInstr.target := if4_bp.target
247    if4_prevHalfInstr.instr := if4_pd.instrs(if4_prevHalfInstr.idx)(15, 0)
248    if4_prevHalfInstr.ipf := if4_ipf
249  }
250
251  // Redirect and npc logic for if4
252  when (bpu.io.out(2).valid && if4_fire && if4_bp.redirect) {
253    if4_redirect := true.B
254    when (if4_bp.saveHalfRVI) {
255      if1_npc := snpc(if4_pc)
256    }.otherwise {
257      if1_npc := if4_bp.target
258    }
259  }
260  // }.elsewhen (bpu.io.out(2).valid && if4_fire/* && !if4_bp.redirect*/) {
261  //   // We redirect the pipeline to the next fetch packet,
262  //   // which contains the last half of the RVI instruction
263  //   when (if4_bp.saveHalfRVI && if4_bp.taken) {
264  //     if4_redirect := true.B
265  //     if1_npc := snpc(if4_pc)
266  //   }
267  // }
268
269  // This should cover the if4 redirect to snpc when saveHalfRVI
270  when (if3_redirect) {
271    when (if3_hasPrevHalfInstr && prevHalfInstr.taken) {
272      if1_npc := prevHalfInstr.target
273    }
274  }
275
276  // history logic for if4
277  when (bpu.io.out(2).valid && if4_fire && if4_bp.redirect) {
278    shiftPtr := true.B
279    newPtr := if4_newPtr
280  // }.elsewhen (bpu.io.out(2).valid && if4_fire/* && !if4_bp.redirect*/) {
281  //   // only if we hasn't seen not taken branches and
282  //   // see a not taken branch in if4 should we tell
283  //   // if3 and if4 to update histptr
284  //   // We do not shift global history pointer unless we have the full
285  //   // RVI instruction
286  //   when (if4_newSawNTBrs && !if4_bp.takenOnBr) {
287  //     shiftPtr := true.B
288  //     // newPtr := if4_realGHInfo.newPtr
289  //   }
290  }
291
292  when (if4_realGHInfo.shifted && if4_newPtr >= ptr) {
293    hist(if4_newPtr-ptr) := if4_realGHInfo.takenOnBr
294  }
295
296  when (if3_redirect) {
297    // when redirect and if3_hasPrevHalfInstr, this prevHalfInstr should only be taken
298    when (if3_hasPrevHalfInstr && prevHalfInstr.ghInfo.shifted) {
299      shiftPtr := true.B
300      newPtr := prevHalfInstr.newPtr
301      extHist(prevHalfInstr.newPtr) := prevHalfInstr.ghInfo.takenOnBr
302    }
303  }
304
305  // modify GHR at the end of a prediction lifetime
306  when (if4_fire && if4_realGHInfo.shifted) {
307    extHist(if4_newPtr) := if4_realGHInfo.takenOnBr
308  }
309
310  // This is a histPtr which is only modified when a prediction
311  // is sent, so that it can get the final prediction info
312  val finalPredHistPtr = RegInit(0.U(log2Up(ExtHistoryLength).W))
313  if4_histPtr := finalPredHistPtr
314  if4_newPtr  := if3_histPtr
315  when (if4_fire && if4_realGHInfo.shifted) {
316    finalPredHistPtr := if4_newPtr
317  }
318
319  if3_histPtr := Mux(if4_realGHInfo.shifted && if4_valid && !if4_flush, if4_histPtr - 1.U, if4_histPtr)
320  if3_newPtr  := if2_histPtr
321
322  if2_histPtr := Mux(if3_realGHInfo.shifted && if3_valid && !if3_flush, if3_histPtr - 1.U, if3_histPtr)
323  if2_newPtr  := if1_histPtr
324
325  if1_histPtr := Mux(if2_realGHInfo.shifted && if2_valid && !if2_flush, if2_histPtr - 1.U, if2_histPtr)
326
327
328
329
330  when (io.outOfOrderBrInfo.valid && io.outOfOrderBrInfo.bits.isMisPred) {
331    val b = io.outOfOrderBrInfo.bits
332    val oldPtr = b.brInfo.histPtr
333    shiftPtr := true.B
334    when (!b.pd.isBr && !b.brInfo.sawNotTakenBranch) {
335      // If mispredicted cfi is not a branch,
336      // and there wasn't any not taken branch before it,
337      // we should only recover the pointer to an unshifted state
338      newPtr := oldPtr
339      finalPredHistPtr := oldPtr
340    }.otherwise {
341      newPtr := oldPtr - 1.U
342      finalPredHistPtr := oldPtr - 1.U
343      hist(0) := Mux(b.pd.isBr, b.taken, 0.U)
344      extHist(newPtr) := Mux(b.pd.isBr, b.taken, 0.U)
345    }
346  }
347
348  when (io.loopBufPar.LBredirect.valid) {
349    if1_npc := io.loopBufPar.LBredirect.bits
350  }
351
352  when (io.redirect.valid) {
353    if1_npc := io.redirect.bits.target
354  }
355
356  when(io.loopBufPar.inLoop) {
357    io.icacheReq.valid := if2_flush
358  }.otherwise {
359    io.icacheReq.valid := if1_valid && if2_ready
360    // io.icacheResp.ready := if3_ready
361  //io.icacheResp.ready := if3_valid
362  }
363  io.icacheResp.ready := if4_ready
364  io.icacheReq.bits.addr := if1_npc
365
366  // when(if4_bp.taken) {
367  //   when(if4_bp.saveHalfRVI) {
368  //     io.loopBufPar.LBReq := snpc(if4_pc)
369  //   }.otherwise {
370  //     io.loopBufPar.LBReq := if4_bp.target
371  //   }
372  // }.otherwise {
373  //   io.loopBufPar.LBReq := snpc(if4_pc)
374  //   XSDebug(p"snpc(if4_pc)=${Hexadecimal(snpc(if4_pc))}\n")
375  // }
376  io.loopBufPar.LBReq := if3_pc
377  io.loopBufPar.tgtpc := if4_bp.target
378
379  io.icacheReq.bits.mask := mask(if1_npc)
380
381  io.icacheFlush := Cat(if3_flush, if2_flush)
382
383  val inOrderBrHist = Wire(Vec(HistoryLength, UInt(1.W)))
384  (0 until HistoryLength).foreach(i => inOrderBrHist(i) := extHist(i.U + io.inOrderBrInfo.bits.brInfo.predHistPtr))
385  bpu.io.inOrderBrInfo.valid := io.inOrderBrInfo.valid
386  bpu.io.inOrderBrInfo.bits := BranchUpdateInfoWithHist(io.inOrderBrInfo.bits, inOrderBrHist.asUInt)
387  bpu.io.outOfOrderBrInfo.valid := io.outOfOrderBrInfo.valid
388  bpu.io.outOfOrderBrInfo.bits := BranchUpdateInfoWithHist(io.outOfOrderBrInfo.bits, inOrderBrHist.asUInt) // Dont care about hist
389
390  // bpu.io.flush := Cat(if4_flush, if3_flush, if2_flush)
391  bpu.io.flush := VecInit(if2_flush, if3_flush, if4_flush)
392  bpu.io.cacheValid := (io.loopBufPar.inLoop || io.icacheResp.valid)
393  bpu.io.in.valid := if1_fire
394  bpu.io.in.bits.pc := if1_npc
395  bpu.io.in.bits.hist := hist.asUInt
396  bpu.io.in.bits.histPtr := ptr
397  bpu.io.in.bits.inMask := mask(if1_npc)
398  bpu.io.out(0).ready := if2_fire
399  bpu.io.out(1).ready := if3_fire
400  bpu.io.out(2).ready := if4_fire
401  bpu.io.predecode.valid := if4_valid
402  bpu.io.predecode.bits.mask := if4_pd.mask
403  bpu.io.predecode.bits.pd := if4_pd.pd
404  bpu.io.predecode.bits.isFetchpcEqualFirstpc := if4_pc === if4_pd.pc(0)
405  bpu.io.branchInfo.ready := if4_fire
406
407  when(io.loopBufPar.inLoop) {
408    pd.io.in := io.loopBufPar.LBResp
409    pd.io.in.mask := io.loopBufPar.LBResp.mask & mask(io.loopBufPar.LBResp.pc)
410    XSDebug("Fetch from LB\n")
411    XSDebug(p"pc=${Hexadecimal(io.loopBufPar.LBResp.pc)}\n")
412    XSDebug(p"data=${Hexadecimal(io.loopBufPar.LBResp.data)}\n")
413    XSDebug(p"mask=${Hexadecimal(io.loopBufPar.LBResp.mask)}\n")
414  }.otherwise {
415    pd.io.in := icacheResp
416  }
417  pd.io.prev.valid := if3_hasPrevHalfInstr
418  pd.io.prev.bits := prevHalfInstr.instr
419  // if a fetch packet triggers page fault, set the pf instruction to nop
420  when (!if3_hasPrevHalfInstr && icacheResp.ipf) {
421    val instrs = Wire(Vec(FetchWidth, UInt(32.W)))
422    (0 until FetchWidth).foreach(i => instrs(i) := ZeroExt("b0010011".U, 32)) // nop
423    pd.io.in.data := instrs.asUInt
424  }.elsewhen (if3_hasPrevHalfInstr && (prevHalfInstr.ipf || icacheResp.ipf)) {
425    pd.io.prev.bits := ZeroExt("b0010011".U, 16)
426    val instrs = Wire(Vec(FetchWidth, UInt(32.W)))
427    (0 until FetchWidth).foreach(i => instrs(i) := Cat(ZeroExt("b0010011".U, 16), Fill(16, 0.U(1.W))))
428    pd.io.in.data := instrs.asUInt
429
430    when (icacheResp.ipf && !prevHalfInstr.ipf) { crossPageIPF := true.B } // higher 16 bits page fault
431  }
432
433  //Performance Counter
434  if (!env.FPGAPlatform ) {
435    ExcitingUtils.addSource(io.fetchPacket.fire && !io.loopBufPar.inLoop, "CntFetchFromICache", Perf)
436    ExcitingUtils.addSource(io.fetchPacket.fire && io.loopBufPar.inLoop, "CntFetchFromLoopBuffer", Perf)
437  }
438
439  io.fetchPacket.valid := if4_valid && !io.redirect.valid
440  io.fetchPacket.bits.instrs := if4_pd.instrs
441  io.fetchPacket.bits.mask := if4_pd.mask & (Fill(PredictWidth, !if4_bp.taken) | (Fill(PredictWidth, 1.U(1.W)) >> (~if4_bp.jmpIdx)))
442  io.fetchPacket.bits.pc := if4_pd.pc
443  (0 until PredictWidth).foreach(i => io.fetchPacket.bits.pnpc(i) := if4_pd.pc(i) + Mux(if4_pd.pd(i).isRVC, 2.U, 4.U))
444  when (if4_bp.taken) {
445    io.fetchPacket.bits.pnpc(if4_bp.jmpIdx) := if4_bp.target
446  }
447  io.fetchPacket.bits.brInfo := bpu.io.branchInfo.bits
448  (0 until PredictWidth).foreach(i => io.fetchPacket.bits.brInfo(i).histPtr := finalPredHistPtr)
449  (0 until PredictWidth).foreach(i => io.fetchPacket.bits.brInfo(i).predHistPtr := if4_predHistPtr)
450  io.fetchPacket.bits.pd := if4_pd.pd
451  io.fetchPacket.bits.ipf := if4_ipf
452  io.fetchPacket.bits.crossPageIPFFix := if4_crossPageIPF
453
454  // predTaken Vec
455  io.fetchPacket.bits.predTaken := if4_bp.taken
456
457  // debug info
458  if (IFUDebug) {
459    XSDebug(RegNext(reset.asBool) && !reset.asBool, "Reseting...\n")
460    XSDebug(io.icacheFlush(0).asBool, "Flush icache stage2...\n")
461    XSDebug(io.icacheFlush(1).asBool, "Flush icache stage3...\n")
462    XSDebug(io.redirect.valid, "Redirect from backend! isExcp=%d isFpp:%d isMisPred=%d isReplay=%d pc=%x\n",
463      io.redirect.bits.isException, io.redirect.bits.isFlushPipe, io.redirect.bits.isMisPred, io.redirect.bits.isReplay, io.redirect.bits.pc)
464    XSDebug(io.redirect.valid, p"Redirect from backend! target=${Hexadecimal(io.redirect.bits.target)} brTag=${io.redirect.bits.brTag}\n")
465
466    XSDebug("[IF1] v=%d     fire=%d            flush=%d pc=%x ptr=%d mask=%b\n", if1_valid, if1_fire, if1_flush, if1_npc, ptr, mask(if1_npc))
467    XSDebug("[IF2] v=%d r=%d fire=%d redirect=%d flush=%d pc=%x ptr=%d snpc=%x\n", if2_valid, if2_ready, if2_fire, if2_redirect, if2_flush, if2_pc, if2_histPtr, if2_snpc)
468    XSDebug("[IF3] v=%d r=%d fire=%d redirect=%d flush=%d pc=%x ptr=%d crossPageIPF=%d sawNTBrs=%d\n", if3_valid, if3_ready, if3_fire, if3_redirect, if3_flush, if3_pc, if3_histPtr, crossPageIPF, if3_realGHInfo.sawNTBr)
469    XSDebug("[IF4] v=%d r=%d fire=%d redirect=%d flush=%d pc=%x ptr=%d crossPageIPF=%d sawNTBrs=%d\n", if4_valid, if4_ready, if4_fire, if4_redirect, if4_flush, if4_pc, if4_histPtr, if4_crossPageIPF, if4_realGHInfo.sawNTBr)
470    XSDebug("[IF1][icacheReq] v=%d r=%d addr=%x\n", io.icacheReq.valid, io.icacheReq.ready, io.icacheReq.bits.addr)
471    XSDebug("[IF1][ghr] headPtr=%d shiftPtr=%d newPtr=%d ptr=%d\n", if1_histPtr, shiftPtr, newPtr, ptr)
472    XSDebug("[IF1][ghr] hist=%b\n", hist.asUInt)
473    XSDebug("[IF1][ghr] extHist=%b\n\n", extHist.asUInt)
474
475    XSDebug("[IF2][bp] redirect=%d taken=%d jmpIdx=%d hasNTBrs=%d target=%x saveHalfRVI=%d\n\n", if2_bp.redirect, if2_bp.taken, if2_bp.jmpIdx, if2_bp.hasNotTakenBrs, if2_bp.target, if2_bp.saveHalfRVI)
476    // XSDebug("[IF2][GHInfo]: %s\n", if2_realGHInfo)
477    if2_realGHInfo.debug
478
479    XSDebug("[IF3][icacheResp] v=%d r=%d pc=%x mask=%b\n", io.icacheResp.valid, io.icacheResp.ready, io.icacheResp.bits.pc, io.icacheResp.bits.mask)
480    XSDebug("[IF3][bp] redirect=%d taken=%d jmpIdx=%d hasNTBrs=%d target=%x saveHalfRVI=%d\n", if3_bp.redirect, if3_bp.taken, if3_bp.jmpIdx, if3_bp.hasNotTakenBrs, if3_bp.target, if3_bp.saveHalfRVI)
481    // XSDebug("[IF3][prevHalfInstr] v=%d redirect=%d fetchpc=%x idx=%d tgt=%x taken=%d instr=%x\n\n",
482    //   prev_half_valid, prev_half_redirect, prev_half_fetchpc, prev_half_idx, prev_half_tgt, prev_half_taken, prev_half_instr)
483    XSDebug("[IF3][    prevHalfInstr] v=%d taken=%d fetchpc=%x idx=%d pc=%x tgt=%x instr=%x ipf=%d\n",
484      prevHalfInstr.valid, prevHalfInstr.taken, prevHalfInstr.fetchpc, prevHalfInstr.idx, prevHalfInstr.pc, prevHalfInstr.target, prevHalfInstr.instr, prevHalfInstr.ipf)
485    XSDebug("[IF3][if3_prevHalfInstr] v=%d taken=%d fetchpc=%x idx=%d pc=%x tgt=%x instr=%x ipf=%d\n\n",
486      if3_prevHalfInstr.valid, if3_prevHalfInstr.taken, if3_prevHalfInstr.fetchpc, if3_prevHalfInstr.idx, if3_prevHalfInstr.pc, if3_prevHalfInstr.target, if3_prevHalfInstr.instr, if3_prevHalfInstr.ipf)
487    // XSDebug("[IF3][GHInfo]: %s\n", if3_realGHInfo)
488    if3_realGHInfo.debug
489
490    XSDebug("[IF4][predecode] mask=%b\n", if4_pd.mask)
491    XSDebug("[IF4][bp] redirect=%d taken=%d jmpIdx=%d hasNTBrs=%d target=%x saveHalfRVI=%d\n", if4_bp.redirect, if4_bp.taken, if4_bp.jmpIdx, if4_bp.hasNotTakenBrs, if4_bp.target, if4_bp.saveHalfRVI)
492    XSDebug(if4_pd.pd(if4_bp.jmpIdx).isJal && if4_bp.taken, "[IF4] cfi is jal!  instr=%x target=%x\n", if4_cfi_jal, if4_cfi_jal_tgt)
493    XSDebug("[IF4][if4_prevHalfInstr] v=%d taken=%d fetchpc=%x idx=%d pc=%x tgt=%x instr=%x ipf=%d\n",
494      if4_prevHalfInstr.valid, if4_prevHalfInstr.taken, if4_prevHalfInstr.fetchpc, if4_prevHalfInstr.idx, if4_prevHalfInstr.pc, if4_prevHalfInstr.target, if4_prevHalfInstr.instr, if4_prevHalfInstr.ipf)
495    // XSDebug("[IF4][GHInfo]: %s\n", if4_realGHInfo)
496    if4_realGHInfo.debug
497    XSDebug(io.fetchPacket.fire(), "[IF4][fetchPacket] v=%d r=%d mask=%b ipf=%d crossPageIPF=%d\n",
498      io.fetchPacket.valid, io.fetchPacket.ready, io.fetchPacket.bits.mask, io.fetchPacket.bits.ipf, io.fetchPacket.bits.crossPageIPFFix)
499    for (i <- 0 until PredictWidth) {
500      XSDebug(io.fetchPacket.fire(), "[IF4][fetchPacket] %b %x pc=%x pnpc=%x pd: rvc=%d brType=%b call=%d ret=%d\n",
501        io.fetchPacket.bits.mask(i),
502        io.fetchPacket.bits.instrs(i),
503        io.fetchPacket.bits.pc(i),
504        io.fetchPacket.bits.pnpc(i),
505        io.fetchPacket.bits.pd(i).isRVC,
506        io.fetchPacket.bits.pd(i).brType,
507        io.fetchPacket.bits.pd(i).isCall,
508        io.fetchPacket.bits.pd(i).isRet
509      )
510    }
511  }
512}