riscv/rocket-chip
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Retime PTW response valid bits

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It's not just to save the gate delay; it also reduces wire delay by
allowing the flops to be closer to their respective TLBs.
This commit is contained in:
Andrew Waterman 2017-03-20 01:30:09 -07:00
parent a03556220c
commit 44ca3b60ab
1 changed files with 4 additions and 4 deletions
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8
src/main/scala/rocket/PTW.scala
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@ -73,7 +73,7 @@ class PTW(n: Int)(implicit p: Parameters) extends CoreModule()(p) {
val state = Reg(init=s_ready) val state = Reg(init=s_ready)
val count = Reg(UInt(width = log2Up(pgLevels))) val count = Reg(UInt(width = log2Up(pgLevels)))
val s1_kill = Reg(next = Bool(false)) val s1_kill = Reg(next = Bool(false))
val resp_valid = Reg(next = Bool(false)) val resp_valid = Reg(next = Vec.fill(io.requestor.size)(Bool(false)))
val exception = Reg(next = io.mem.xcpt.pf.ld) val exception = Reg(next = io.mem.xcpt.pf.ld)
val r_req = Reg(new PTWReq) val r_req = Reg(new PTWReq)
@ -132,7 +132,7 @@ class PTW(n: Int)(implicit p: Parameters) extends CoreModule()(p) {
io.mem.invalidate_lr := Bool(false) io.mem.invalidate_lr := Bool(false)
for (i <- 0 until io.requestor.size) { for (i <- 0 until io.requestor.size) {
io.requestor(i).resp.valid := resp_valid && (r_req_dest === i) io.requestor(i).resp.valid := resp_valid(i)
io.requestor(i).resp.bits.pte := r_pte io.requestor(i).resp.bits.pte := r_pte
io.requestor(i).resp.bits.level := count io.requestor(i).resp.bits.level := count
io.requestor(i).resp.bits.pte.ppn := pte_addr >> pgIdxBits io.requestor(i).resp.bits.pte.ppn := pte_addr >> pgIdxBits
@ -172,13 +172,13 @@ class PTW(n: Int)(implicit p: Parameters) extends CoreModule()(p) {
count := count + 1 count := count + 1
}.otherwise { }.otherwise {
state := s_ready state := s_ready
resp_valid := true resp_valid(r_req_dest) := true
} }
} }
when (exception) { when (exception) {
r_pte.v := false r_pte.v := false
state := s_ready state := s_ready
resp_valid := true resp_valid(r_req_dest) := true
} }
} }
} }