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power(rob): add clock gate for walkingPtrVec and vstart #3611

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power(rob): add clock gate for walkingPtrVec and vstart #3611

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18 changes: 10 additions & 8 deletions src/main/scala/xiangshan/backend/rob/Rob.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -598,7 +598,8 @@ class RobImp(override val wrapper: Rob)(implicit p: Parameters, params: BackendP
XSPerfAccumulate("replay_inst_num", io.flushOut.valid && isFlushPipe && deqHasReplayInst)

val exceptionHappen = (state === s_idle) && deqPtrEntryValid && (intrEnable || deqHasException && (!deqIsVlsException || deqVlsCanCommit)) && !lastCycleFlush
io.exception.valid := RegNext(exceptionHappen)
val exceptionHappenReg = GatedValidRegNext(exceptionHappen)
io.exception.valid := exceptionHappenReg
io.exception.bits.pc := RegEnable(debug_deqUop.pc, exceptionHappen)
io.exception.bits.gpaddr := io.readGPAMemData.gpaddr
io.exception.bits.isForVSnonLeafPTE := io.readGPAMemData.isForVSnonLeafPTE
Expand Down Expand Up @@ -638,10 +639,12 @@ class RobImp(override val wrapper: Rob)(implicit p: Parameters, params: BackendP
*/
// T redirect.valid, T+1 use walkPtrVec read robEntries, T+2 start walk, shouldWalkVec used in T+2
val shouldWalkVec = Wire(Vec(CommitWidth,Bool()))
val walkingPtrVec = RegNext(walkPtrVec)
// Maybe we can use walkPtrVec - CommitWidth here to save area
val walkingPtrVec = RegEnable(walkPtrVec, state === s_walk)
val redirectValidReg = RegNext(io.redirect.valid)
when(io.redirect.valid){
shouldWalkVec := 0.U.asTypeOf(shouldWalkVec)
}.elsewhen(RegNext(io.redirect.valid)){
}.elsewhen(redirectValidReg){
shouldWalkVec := 0.U.asTypeOf(shouldWalkVec)
}.elsewhen(state === s_walk){
shouldWalkVec := VecInit(walkingPtrVec.map(_ <= lastWalkPtr).zip(donotNeedWalk).map(x => x._1 && !x._2))
Expand Down Expand Up @@ -688,8 +691,8 @@ class RobImp(override val wrapper: Rob)(implicit p: Parameters, params: BackendP
vecExcpInfo.bits.vstart := exceptionDataRead.bits.vstart
}

io.csr.vstart.valid := RegNext(Mux(exceptionHappen, exceptionDataRead.bits.vstartEn, resetVstart))
io.csr.vstart.bits := RegNext(Mux(exceptionHappen, exceptionDataRead.bits.vstart, 0.U))
io.csr.vstart.valid := GatedValidRegNext(Mux(exceptionHappen, exceptionDataRead.bits.vstartEn, resetVstart))
io.csr.vstart.bits := Mux(exceptionHappenReg, RegEnable(exceptionDataRead.bits.vstart, exceptionHappen), 0.U)

val vxsat = Wire(Valid(Bool()))
vxsat.valid := io.commits.isCommit && vxsat.bits
Expand Down Expand Up @@ -799,7 +802,7 @@ class RobImp(override val wrapper: Rob)(implicit p: Parameters, params: BackendP
* (2) walk: when walking comes to the end, switch to s_idle
*/
state_next := Mux(
io.redirect.valid || RegNext(io.redirect.valid), s_walk,
io.redirect.valid || redirectValidReg, s_walk,
Mux(
state === s_walk && walkFinished && rab.io.status.walkEnd && vtypeBuffer.io.status.walkEnd, s_idle,
state
Expand Down Expand Up @@ -861,7 +864,7 @@ class RobImp(override val wrapper: Rob)(implicit p: Parameters, params: BackendP
}
when(io.redirect.valid) {
donotNeedWalk := Fill(donotNeedWalk.length, true.B).asTypeOf(donotNeedWalk)
}.elsewhen(RegNext(io.redirect.valid)){
}.elsewhen(redirectValidReg){
donotNeedWalk := (0 until CommitWidth).map(i => (i.U < walkPtrLowBits))
}.otherwise{
donotNeedWalk := 0.U.asTypeOf(donotNeedWalk)
Expand Down Expand Up @@ -892,7 +895,6 @@ class RobImp(override val wrapper: Rob)(implicit p: Parameters, params: BackendP
deqPtrGroup.zipWithIndex.map { case (deq, i) => deq := deqPtrVec(0) + i.U }
val commitReadAddr = Mux(state === s_idle, VecInit(deqPtrVec.map(_.value)), VecInit(walkPtrVec.map(_.value)))

val redirectValidReg = RegNext(io.redirect.valid)
val redirectBegin = Reg(UInt(log2Up(RobSize).W))
val redirectEnd = Reg(UInt(log2Up(RobSize).W))
when(io.redirect.valid){
Expand Down
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