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rocket-chip/rocket/src/main/scala/nbdcache.scala

1063 lines
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Scala
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package rocket
import Chisel._
import Constants._
import uncore._
import Util._
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case class DCacheConfig(sets: Int, ways: Int, co: CoherencePolicy,
nmshr: Int, nrpq: Int, nsdq: Int,
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reqtagbits: Int = -1)
{
require(isPow2(sets))
require(isPow2(ways)) // TODO: relax this
def lines = sets*ways
def dm = ways == 1
def ppnbits = PADDR_BITS - PGIDX_BITS
def vpnbits = VADDR_BITS - PGIDX_BITS
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def pgidxbits = PGIDX_BITS
def offbits = OFFSET_BITS
def paddrbits = ppnbits + pgidxbits
def lineaddrbits = ppnbits - offbits
def idxbits = log2Up(sets)
def waybits = log2Up(ways)
def tagbits = lineaddrbits - idxbits
def databytes = 8 // assumed by StoreGen/LoadGen/AMOALU
def databits = databytes*8
}
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abstract class ReplacementPolicy
{
def way: UFix
def miss: Unit
def hit: Unit
}
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class RandomReplacement(implicit conf: DCacheConfig) extends ReplacementPolicy
{
private val replace = Bool()
replace := Bool(false)
val lfsr = LFSR16(replace)
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def way = if (conf.dm) UFix(0) else lfsr(conf.waybits-1,0)
def miss = replace := Bool(true)
def hit = {}
}
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case class StoreGen(typ: Bits, addr: Bits, dat: Bits)
{
val byte = typ === MT_B || typ === MT_BU
val half = typ === MT_H || typ === MT_HU
val word = typ === MT_W || typ === MT_WU
def mask =
Mux(byte, Bits( 1) << addr(2,0),
Mux(half, Bits( 3) << Cat(addr(2,1), Bits(0,1)),
Mux(word, Bits( 15) << Cat(addr(2), Bits(0,2)),
Bits(255))))
def data =
Mux(byte, Fill(8, dat( 7,0)),
Mux(half, Fill(4, dat(15,0)),
Mux(word, Fill(2, dat(31,0)),
dat)))
}
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case class LoadGen(typ: Bits, addr: Bits, dat: Bits)
{
val t = StoreGen(typ, addr, dat)
val sign = typ === MT_B || typ === MT_H || typ === MT_W || typ === MT_D
val wordShift = Mux(addr(2), dat(63,32), dat(31,0))
val word = Cat(Mux(t.word, Fill(32, sign && wordShift(31)), dat(63,32)), wordShift)
val halfShift = Mux(addr(1), word(31,16), word(15,0))
val half = Cat(Mux(t.half, Fill(48, sign && halfShift(15)), word(63,16)), halfShift)
val byteShift = Mux(addr(0), half(15,8), half(7,0))
val byte = Cat(Mux(t.byte, Fill(56, sign && byteShift(7)), half(63,8)), byteShift)
}
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class MSHRReq(implicit conf: DCacheConfig) extends Bundle {
val tag_miss = Bool()
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val old_dirty = Bool()
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val old_tag = Bits(width = conf.tagbits)
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val tag = Bits(width = conf.tagbits)
val idx = Bits(width = conf.idxbits)
val way_oh = Bits(width = conf.ways)
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val offset = Bits(width = conf.offbits)
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val cmd = Bits(width = 4)
val typ = Bits(width = 3)
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val cpu_tag = Bits(width = conf.reqtagbits)
val data = Bits(width = conf.databits)
override def clone = new MSHRReq().asInstanceOf[this.type]
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}
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class RPQEntry(implicit conf: DCacheConfig) extends Bundle {
val offset = Bits(width = conf.offbits)
val cmd = Bits(width = 4)
val typ = Bits(width = 3)
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val sdq_id = UFix(width = log2Up(conf.nsdq))
val cpu_tag = Bits(width = conf.reqtagbits)
override def clone = new RPQEntry().asInstanceOf[this.type]
}
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class Replay(implicit conf: DCacheConfig) extends RPQEntry {
val idx = Bits(width = conf.idxbits)
val way_oh = Bits(width = conf.ways)
override def clone = new Replay().asInstanceOf[this.type]
}
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class DataReq(implicit conf: DCacheConfig) extends Bundle {
val idx = Bits(width = conf.idxbits)
val offset = Bits(width = conf.offbits)
val cmd = Bits(width = 4)
val typ = Bits(width = 3)
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val data = Bits(width = conf.databits)
val way_oh = Bits(width = conf.ways)
override def clone = new DataReq().asInstanceOf[this.type]
}
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class DataArrayReq(implicit conf: DCacheConfig) extends Bundle {
val way_en = Bits(width = conf.ways)
val idx = Bits(width = conf.idxbits)
val offset = Bits(width = log2Up(REFILL_CYCLES))
val rw = Bool()
val wmask = Bits(width = MEM_DATA_BITS/8)
val data = Bits(width = MEM_DATA_BITS)
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override def clone = new DataArrayReq().asInstanceOf[this.type]
}
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class WritebackReq(implicit conf: DCacheConfig) extends Bundle {
val tag = Bits(width = conf.tagbits)
val idx = Bits(width = conf.idxbits)
val way_oh = Bits(width = conf.ways)
val tile_xact_id = Bits(width = TILE_XACT_ID_BITS)
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override def clone = new WritebackReq().asInstanceOf[this.type]
}
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class MetaData(implicit conf: DCacheConfig) extends Bundle {
val state = UFix(width = 2)
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val tag = Bits(width = conf.tagbits)
override def clone = new MetaData().asInstanceOf[this.type]
}
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class MetaArrayReq(implicit conf: DCacheConfig) extends Bundle {
val way_en = Bits(width = conf.ways)
val idx = Bits(width = conf.idxbits)
val rw = Bool()
val data = new MetaData()
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override def clone = new MetaArrayReq().asInstanceOf[this.type]
}
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class MSHR(id: Int)(implicit conf: DCacheConfig) extends Component {
val io = new Bundle {
val req_pri_val = Bool(INPUT)
val req_pri_rdy = Bool(OUTPUT)
val req_sec_val = Bool(INPUT)
val req_sec_rdy = Bool(OUTPUT)
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val req_bits = new MSHRReq().asInput
val req_sdq_id = UFix(INPUT, log2Up(conf.nsdq))
val idx_match = Bool(OUTPUT)
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val idx = Bits(OUTPUT, conf.idxbits)
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val refill_count = Bits(OUTPUT, log2Up(REFILL_CYCLES))
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val tag = Bits(OUTPUT, conf.tagbits)
val way_oh = Bits(OUTPUT, conf.ways)
val mem_req = (new FIFOIO) { new TransactionInit }
val meta_req = (new FIFOIO) { new MetaArrayReq() }
val replay = (new FIFOIO) { new Replay() }
val mem_abort = (new PipeIO) { new TransactionAbort }.flip
val mem_rep = (new PipeIO) { new TransactionReply }.flip
val mem_finish = (new FIFOIO) { new TransactionFinish }
val wb_req = (new FIFOIO) { new WritebackReq }
val probe_writeback = (new FIFOIO) { Bool() }.flip
val probe_refill = (new FIFOIO) { Bool() }.flip
}
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val s_invalid :: s_wb_req :: s_wb_resp :: s_meta_clear :: s_refill_req :: s_refill_resp :: s_drain_rpq :: Nil = Enum(7) { UFix() }
val state = Reg(resetVal = s_invalid)
val flush = Reg { Bool() }
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val xacx_type = Reg { UFix() }
val line_state = Reg { UFix() }
val refill_count = Reg { UFix(width = log2Up(REFILL_CYCLES)) }
val req = Reg { new MSHRReq() }
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val req_cmd = io.req_bits.cmd
val req_use_rpq = (req_cmd != M_PFR) && (req_cmd != M_PFW) && (req_cmd != M_FLA)
val idx_match = req.idx === io.req_bits.idx
val sec_rdy = idx_match && !flush && (state === s_wb_req || state === s_wb_resp || state === s_meta_clear || (state === s_refill_req || state === s_refill_resp) && !conf.co.needsTransactionOnSecondaryMiss(req_cmd, io.mem_req.bits))
val rpq = (new Queue(conf.nrpq)) { new RPQEntry }
rpq.io.enq.valid := (io.req_pri_val && io.req_pri_rdy || io.req_sec_val && sec_rdy) && req_use_rpq
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rpq.io.enq.bits := io.req_bits
rpq.io.enq.bits.sdq_id := io.req_sdq_id
rpq.io.deq.ready := io.replay.ready && (state === s_drain_rpq) || (state === s_invalid)
val abort = io.mem_abort.valid && io.mem_abort.bits.tile_xact_id === UFix(id)
val reply = io.mem_rep.valid && io.mem_rep.bits.tile_xact_id === UFix(id)
val refill_done = reply && refill_count.andR
val wb_done = reply && (state === s_wb_resp)
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val finish_q = (new Queue(2 /* wb + refill */)) { new TransactionFinish }
finish_q.io.enq.valid := wb_done || refill_done
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finish_q.io.enq.bits.global_xact_id := io.mem_rep.bits.global_xact_id
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when (state === s_drain_rpq && !rpq.io.deq.valid && !finish_q.io.deq.valid && io.meta_req.ready) {
state := s_invalid
}
when (state === s_refill_resp) {
when (refill_done) { state := s_drain_rpq }
when (reply) {
refill_count := refill_count + UFix(1)
line_state := conf.co.newStateOnTransactionReply(io.mem_rep.bits, io.mem_req.bits)
}
when (abort) { state := s_refill_req }
}
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when (state === s_refill_req) {
when (flush) { state := s_drain_rpq }
.elsewhen (abort) { state := s_refill_req }
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.elsewhen (io.mem_req.ready) { state := s_refill_resp }
}
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when (state === s_meta_clear && io.meta_req.ready) {
state := s_refill_req
}
when (state === s_wb_resp) {
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when (reply) { state := s_meta_clear }
when (abort) { state := s_wb_req }
}
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when (state === s_wb_req) {
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when (io.probe_writeback.valid && io.probe_writeback.bits && idx_match) { state := s_refill_req }
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.elsewhen (io.wb_req.ready) { state := s_wb_resp }
}
when (io.req_sec_val && io.req_sec_rdy) { // s_wb_req, s_wb_resp, s_refill_req
xacx_type := conf.co.getTransactionInitTypeOnSecondaryMiss(req_cmd, conf.co.newStateOnFlush(), io.mem_req.bits)
}
when ((state === s_invalid) && io.req_pri_val) {
flush := req_cmd === M_FLA
line_state := conf.co.newStateOnFlush()
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refill_count := UFix(0)
xacx_type := conf.co.getTransactionInitTypeOnPrimaryMiss(req_cmd, conf.co.newStateOnFlush())
req := io.req_bits
when (io.req_bits.tag_miss) {
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state := Mux(io.req_bits.old_dirty, s_wb_req, s_refill_req)
}
}
io.idx_match := (state != s_invalid) && idx_match
io.idx := req.idx
io.tag := req.tag
io.way_oh := req.way_oh
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io.refill_count := refill_count
io.req_pri_rdy := (state === s_invalid)
io.req_sec_rdy := sec_rdy && rpq.io.enq.ready
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io.meta_req.valid := (state === s_drain_rpq) && !rpq.io.deq.valid && !finish_q.io.deq.valid || (state === s_meta_clear)
io.meta_req.bits.rw := Bool(true)
io.meta_req.bits.idx := req.idx
io.meta_req.bits.data.state := Mux(state === s_meta_clear, conf.co.newStateOnFlush(), line_state)
io.meta_req.bits.data.tag := req.tag
io.meta_req.bits.way_en := req.way_oh
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io.wb_req.valid := (state === s_wb_req) && !(io.probe_writeback.valid && idx_match)
io.wb_req.bits.tag := req.old_tag
io.wb_req.bits.idx := req.idx
io.wb_req.bits.way_oh := req.way_oh
io.wb_req.bits.tile_xact_id := Bits(id)
io.probe_writeback.ready := (state != s_wb_resp && state != s_meta_clear && state != s_drain_rpq) || !idx_match
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io.probe_refill.ready := (state != s_refill_resp && state != s_drain_rpq) || !idx_match
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io.mem_req.valid := (state === s_refill_req) && !flush
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io.mem_req.bits.x_type := xacx_type
io.mem_req.bits.addr := Cat(req.tag, req.idx).toUFix
io.mem_req.bits.tile_xact_id := Bits(id)
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io.mem_finish <> finish_q.io.deq
io.replay.valid := (state === s_drain_rpq) && rpq.io.deq.valid
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io.replay.bits <> rpq.io.deq.bits
io.replay.bits.idx := req.idx
io.replay.bits.way_oh := req.way_oh
}
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class MSHRFile(implicit conf: DCacheConfig) extends Component {
val io = new Bundle {
val req = (new FIFOIO) { new MSHRReq }.flip
val secondary_miss = Bool(OUTPUT)
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val mem_resp_idx = Bits(OUTPUT, conf.idxbits)
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val mem_resp_offset = Bits(OUTPUT, log2Up(REFILL_CYCLES))
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val mem_resp_way_oh = Bits(OUTPUT, conf.ways)
val fence_rdy = Bool(OUTPUT)
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val mem_req = (new FIFOIO) { new TransactionInit }
val meta_req = (new FIFOIO) { new MetaArrayReq() }
val data_req = (new FIFOIO) { new DataReq() }
val mem_abort = (new PipeIO) { new TransactionAbort }.flip
val mem_rep = (new PipeIO) { new TransactionReply }.flip
val mem_finish = (new FIFOIO) { new TransactionFinish }
val wb_req = (new FIFOIO) { new WritebackReq }
val probe = (new FIFOIO) { Bool() }.flip
val cpu_resp_val = Bool(OUTPUT)
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val cpu_resp_tag = Bits(OUTPUT, conf.reqtagbits)
}
val sdq_val = Reg(resetVal = Bits(0, conf.nsdq))
val sdq_alloc_id = PriorityEncoder(~sdq_val(conf.nsdq-1,0))
val sdq_rdy = !sdq_val.andR
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val (req_read, req_write) = cpuCmdToRW(io.req.bits.cmd)
val sdq_enq = io.req.valid && io.req.ready && req_write
val sdq = Mem(conf.nsdq) { io.req.bits.data.clone }
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when (sdq_enq) { sdq(sdq_alloc_id) := io.req.bits.data }
val idxMatch = Vec(conf.nmshr) { Bool() }
val tagList = Vec(conf.nmshr) { Bits() }
val wbTagList = Vec(conf.nmshr) { Bits() }
val memRespMux = Vec(conf.nmshr) { new DataArrayReq }
val meta_req_arb = (new Arbiter(conf.nmshr)) { new MetaArrayReq() }
val mem_req_arb = (new Arbiter(conf.nmshr)) { new TransactionInit }
val mem_finish_arb = (new Arbiter(conf.nmshr)) { new TransactionFinish }
val wb_req_arb = (new Arbiter(conf.nmshr)) { new WritebackReq }
val replay_arb = (new Arbiter(conf.nmshr)) { new Replay() }
val alloc_arb = (new Arbiter(conf.nmshr)) { Bool() }
val tag_match = Mux1H(idxMatch, tagList) === io.req.bits.tag
val wb_probe_match = Mux1H(idxMatch, wbTagList) === io.req.bits.tag
var idx_match = Bool(false)
var pri_rdy = Bool(false)
var fence = Bool(false)
var sec_rdy = Bool(false)
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var writeback_probe_rdy = Bool(true)
var refill_probe_rdy = Bool(true)
for (i <- 0 to conf.nmshr-1) {
val mshr = new MSHR(i)
idxMatch(i) := mshr.io.idx_match
tagList(i) := mshr.io.tag
wbTagList(i) := mshr.io.wb_req.bits.tag
alloc_arb.io.in(i).valid := mshr.io.req_pri_rdy
mshr.io.req_pri_val := alloc_arb.io.in(i).ready
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mshr.io.req_sec_val := io.req.valid && sdq_rdy && tag_match
mshr.io.req_bits := io.req.bits
mshr.io.req_sdq_id := sdq_alloc_id
mshr.io.meta_req <> meta_req_arb.io.in(i)
mshr.io.mem_req <> mem_req_arb.io.in(i)
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mshr.io.mem_finish <> mem_finish_arb.io.in(i)
mshr.io.wb_req <> wb_req_arb.io.in(i)
mshr.io.replay <> replay_arb.io.in(i)
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mshr.io.probe_refill.valid := io.probe.valid && tag_match
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mshr.io.probe_writeback.valid := io.probe.valid
mshr.io.probe_writeback.bits := wb_probe_match
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mshr.io.mem_abort <> io.mem_abort
mshr.io.mem_rep <> io.mem_rep
memRespMux(i).idx := mshr.io.idx
memRespMux(i).offset := mshr.io.refill_count
memRespMux(i).way_en := mshr.io.way_oh
pri_rdy = pri_rdy || mshr.io.req_pri_rdy
sec_rdy = sec_rdy || mshr.io.req_sec_rdy
fence = fence || !mshr.io.req_pri_rdy
idx_match = idx_match || mshr.io.idx_match
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refill_probe_rdy = refill_probe_rdy && mshr.io.probe_refill.ready
writeback_probe_rdy = writeback_probe_rdy && mshr.io.probe_writeback.ready
}
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alloc_arb.io.out.ready := io.req.valid && sdq_rdy && !idx_match
meta_req_arb.io.out <> io.meta_req
mem_req_arb.io.out <> io.mem_req
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mem_finish_arb.io.out <> io.mem_finish
wb_req_arb.io.out <> io.wb_req
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io.req.ready := Mux(idx_match, tag_match && sec_rdy, pri_rdy) && sdq_rdy
io.secondary_miss := idx_match
val memResp = memRespMux(io.mem_rep.bits.tile_xact_id)
io.mem_resp_idx := memResp.idx
io.mem_resp_offset := memResp.offset
io.mem_resp_way_oh := memResp.way_en
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io.fence_rdy := !fence
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io.probe.ready := (refill_probe_rdy || !tag_match) && (writeback_probe_rdy || !wb_probe_match)
val replay = Queue(replay_arb.io.out, 1, pipe = true)
replay.ready := io.data_req.ready
io.data_req <> replay
val (replay_read, replay_write) = cpuCmdToRW(replay.bits.cmd)
val sdq_free = replay.valid && replay.ready && replay_write
sdq_val := sdq_val & ~((UFix(1) << replay.bits.sdq_id) & Fill(sdq_free, conf.nsdq)) |
PriorityEncoderOH(~sdq_val(conf.nsdq-1,0)) & Fill(conf.nsdq, sdq_enq && io.req.bits.tag_miss)
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val sdq_rdata = Reg() { io.req.bits.data.clone }
sdq_rdata := sdq(Mux(replay.valid && !replay.ready, replay.bits.sdq_id, replay_arb.io.out.bits.sdq_id))
io.data_req.bits.data := sdq_rdata
io.cpu_resp_val := Reg(replay.valid && replay.ready && replay_read, resetVal = Bool(false))
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io.cpu_resp_tag := Reg(replay.bits.cpu_tag)
}
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class WritebackUnit(implicit conf: DCacheConfig) extends Component {
val io = new Bundle {
val req = (new FIFOIO) { new WritebackReq() }.flip
val probe = (new FIFOIO) { new WritebackReq() }.flip
val data_req = (new FIFOIO) { new DataArrayReq() }
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val data_resp = Bits(INPUT, MEM_DATA_BITS)
val mem_req = (new FIFOIO) { new TransactionInit }
val mem_req_data = (new FIFOIO) { new TransactionInitData }
val probe_rep_data = (new FIFOIO) { new ProbeReplyData }
}
val valid = Reg(resetVal = Bool(false))
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val is_probe = Reg() { Bool() }
val data_req_fired = Reg(resetVal = Bool(false))
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val cmd_sent = Reg() { Bool() }
val cnt = Reg() { UFix(width = log2Up(REFILL_CYCLES+1)) }
val req = Reg() { new WritebackReq() }
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val dout_rdy = Mux(is_probe, io.probe_rep_data.ready, io.mem_req_data.ready)
data_req_fired := Bool(false)
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when (valid && io.mem_req.ready) {
cmd_sent := Bool(true)
}
when (io.data_req.valid && io.data_req.ready) {
data_req_fired := Bool(true)
cnt := cnt + UFix(1)
}
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when (data_req_fired && !dout_rdy) {
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data_req_fired := Bool(false)
cnt := cnt - UFix(1)
}
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.elsewhen (cmd_sent && (cnt === UFix(REFILL_CYCLES))) {
valid := Bool(false)
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}
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when (io.probe.valid && io.probe.ready) {
valid := Bool(true)
is_probe := Bool(true)
cmd_sent := Bool(true)
cnt := UFix(0)
req := io.probe.bits
}
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when (io.req.valid && io.req.ready) {
valid := Bool(true)
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is_probe := Bool(false)
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cmd_sent := Bool(false)
cnt := UFix(0)
req := io.req.bits
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}
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io.req.ready := !valid && !io.probe.valid
io.probe.ready := !valid
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io.data_req.valid := valid && (cnt < UFix(REFILL_CYCLES))
io.data_req.bits.way_en := req.way_oh
io.data_req.bits.idx := req.idx
io.data_req.bits.offset := cnt
io.data_req.bits.rw := Bool(false)
io.data_req.bits.wmask := Bits(0)
io.data_req.bits.data := Bits(0)
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io.mem_req.valid := valid && !cmd_sent
io.mem_req.bits.x_type := conf.co.getTransactionInitTypeOnWriteback()
io.mem_req.bits.addr := Cat(req.tag, req.idx).toUFix
io.mem_req.bits.tile_xact_id := req.tile_xact_id
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io.mem_req_data.valid := data_req_fired && !is_probe
io.mem_req_data.bits.data := io.data_resp
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io.probe_rep_data.valid := data_req_fired && is_probe
io.probe_rep_data.bits.data := io.data_resp
}
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class ProbeUnit(implicit conf: DCacheConfig) extends Component {
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val io = new Bundle {
val req = (new FIFOIO) { new ProbeRequest }.flip
val rep = (new FIFOIO) { new ProbeReply }
val meta_req = (new FIFOIO) { new MetaArrayReq }
val mshr_req = (new FIFOIO) { Bool() }
val wb_req = (new FIFOIO) { new WritebackReq }
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val tag_match_way_oh = Bits(INPUT, conf.ways)
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val line_state = UFix(INPUT, 2)
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val addr = Bits(OUTPUT, conf.lineaddrbits)
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}
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val s_reset :: s_invalid :: s_meta_req :: s_meta_resp :: s_mshr_req :: s_probe_rep :: s_writeback_req :: s_writeback_resp :: Nil = Enum(8) { UFix() }
val state = Reg(resetVal = s_reset)
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val line_state = Reg() { UFix() }
val way_oh = Reg() { Bits() }
val req = Reg() { new ProbeRequest() }
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val hit = way_oh.orR
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when ((state === s_writeback_resp) && io.wb_req.ready) {
state := s_invalid
}
when ((state === s_writeback_req) && io.wb_req.ready) {
state := s_writeback_resp
}
when ((state === s_probe_rep) && io.meta_req.ready && io.rep.ready) {
state := Mux(hit && conf.co.needsWriteback(line_state), s_writeback_req, s_invalid)
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}
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when ((state === s_mshr_req) && io.mshr_req.ready) {
state := s_meta_req
}
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when (state === s_meta_resp) {
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way_oh := io.tag_match_way_oh
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line_state := io.line_state
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state := Mux(!io.mshr_req.ready, s_mshr_req, s_probe_rep)
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}
when ((state === s_meta_req) && io.meta_req.ready) {
state := s_meta_resp
}
when ((state === s_invalid) && io.req.valid) {
state := s_meta_req
req := io.req.bits
}
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when (state === s_reset) { state := s_invalid }
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io.req.ready := state === s_invalid
io.rep.valid := state === s_probe_rep && io.meta_req.ready
io.rep.bits := conf.co.newProbeReply(req, Mux(hit, line_state, conf.co.newStateOnFlush))
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io.meta_req.valid := state === s_meta_req || state === s_meta_resp || state === s_mshr_req || state === s_probe_rep && hit
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io.meta_req.bits.way_en := Mux(state === s_probe_rep, way_oh, Fix(-1))
io.meta_req.bits.rw := state === s_probe_rep
io.meta_req.bits.idx := req.addr
io.meta_req.bits.data.state := conf.co.newStateOnProbeRequest(req, line_state)
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io.meta_req.bits.data.tag := req.addr >> UFix(conf.idxbits)
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io.mshr_req.valid := state === s_meta_resp || state === s_mshr_req
io.addr := req.addr
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io.wb_req.valid := state === s_writeback_req
io.wb_req.bits.way_oh := way_oh
io.wb_req.bits.idx := req.addr
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io.wb_req.bits.tag := req.addr >> UFix(conf.idxbits)
}
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class FlushUnit(lines: Int)(implicit conf: DCacheConfig) extends Component {
val io = new Bundle {
val req = (new FIFOIO) { Bool() }.flip
val meta_req = (new FIFOIO) { new MetaArrayReq() }
val mshr_req = (new FIFOIO) { Bool() }
}
val s_reset :: s_ready :: s_meta_read :: s_meta_wait :: Nil = Enum(4) { UFix() }
val state = Reg(resetVal = s_reset)
val idx_cnt = Reg(resetVal = UFix(0, log2Up(lines)))
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val next_idx_cnt = idx_cnt + UFix(1)
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val way_cnt = if (conf.dm) UFix(0) else Reg(resetVal = UFix(0, conf.waybits))
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val next_way_cnt = way_cnt + UFix(1)
switch (state) {
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is(s_reset) {
when (io.meta_req.ready) {
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state := Mux(way_cnt === UFix(conf.ways-1) && idx_cnt.andR, s_ready, s_reset);
when (way_cnt === UFix(conf.ways-1)) { idx_cnt := next_idx_cnt };
if (!conf.dm) way_cnt := next_way_cnt;
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}
}
is(s_ready) { when (io.req.valid) { state := s_meta_read } }
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is(s_meta_read) { when (io.meta_req.ready) { state := s_meta_wait } }
is(s_meta_wait) {
state := s_meta_read
when (io.mshr_req.ready) {
state := s_meta_read
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when (way_cnt === UFix(conf.ways-1)) {
when (idx_cnt.andR) {
state := s_ready
}
idx_cnt := next_idx_cnt
}
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if (!conf.dm) way_cnt := next_way_cnt;
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}
}
}
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io.req.ready := state === s_ready
io.mshr_req.valid := state === s_meta_wait
io.meta_req.valid := (state === s_meta_read) || (state === s_reset)
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io.meta_req.bits.way_en := UFixToOH(way_cnt)
io.meta_req.bits.idx := idx_cnt
io.meta_req.bits.rw := (state === s_reset)
io.meta_req.bits.data.state := conf.co.newStateOnFlush()
io.meta_req.bits.data.tag := UFix(0)
}
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class MetaDataArrayArray(lines: Int)(implicit conf: DCacheConfig) extends Component {
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val io = new Bundle {
val req = (new FIFOIO) { new MetaArrayReq() }.flip
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val resp = Vec(conf.ways){ (new MetaData).asOutput }
val state_req = (new FIFOIO) { new MetaArrayReq() }.flip
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val way_en = Bits(OUTPUT, conf.ways)
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}
val permBits = io.req.bits.data.state.width
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val perms = Mem(lines) { UFix(width = permBits*conf.ways) }
val tags = Mem(lines, seqRead = true) { Bits(width = conf.tagbits*conf.ways) }
val tag = Reg() { Bits() }
val raddr = Reg() { Bits() }
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val way_en_ = Reg { Bits(width = conf.ways) }
when (io.state_req.valid && io.state_req.bits.rw) {
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perms.write(io.state_req.bits.idx, Fill(conf.ways, io.state_req.bits.data.state), FillInterleaved(permBits, io.state_req.bits.way_en))
}
when (io.req.valid) {
when (io.req.bits.rw) {
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perms.write(io.req.bits.idx, Fill(conf.ways, io.req.bits.data.state), FillInterleaved(permBits, io.req.bits.way_en))
tags.write(io.req.bits.idx, Fill(conf.ways, io.req.bits.data.tag), FillInterleaved(conf.tagbits, io.req.bits.way_en))
}
.otherwise {
raddr := io.req.bits.idx
tag := tags(io.req.bits.idx)
}
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way_en_ := io.req.bits.way_en
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}
val perm = perms(raddr)
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for (w <- 0 until conf.ways) {
io.resp(w).state := perm(permBits*(w+1)-1, permBits*w)
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io.resp(w).tag := tag(conf.tagbits*(w+1)-1, conf.tagbits*w)
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}
io.way_en := way_en_
io.req.ready := Bool(true)
io.state_req.ready := Bool(true)
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}
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class DataArray(lines: Int)(implicit conf: DCacheConfig) extends Component {
val io = new Bundle {
val req = (new FIFOIO) { new DataArrayReq() }.flip
val resp = Bits(width = MEM_DATA_BITS, dir = OUTPUT)
}
val wmask = FillInterleaved(8, io.req.bits.wmask)
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val addr = Cat(io.req.bits.idx, io.req.bits.offset)
val rdata = Reg() { Bits() }
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val array = Mem(lines*REFILL_CYCLES, seqRead = true){ Bits(width=MEM_DATA_BITS) }
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when (io.req.valid) {
when (io.req.bits.rw) { array.write(addr, io.req.bits.data, wmask) }
.otherwise { rdata := array(addr) }
}
io.resp := rdata
io.req.ready := Bool(true)
}
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class DataArrayArray(lines: Int)(implicit conf: DCacheConfig) extends Component {
val io = new Bundle {
val req = (new FIFOIO) { new DataArrayReq() }.flip
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val resp = Vec(conf.ways){ Bits(OUTPUT, MEM_DATA_BITS) }
val way_en = Bits(OUTPUT, conf.ways)
}
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val way_en_ = Reg { Bits(width = conf.ways) }
when (io.req.valid && io.req.ready) {
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way_en_ := io.req.bits.way_en
}
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for (w <- 0 until conf.ways) {
val way = new DataArray(lines)
way.io.req.bits <> io.req.bits
way.io.req.valid := io.req.valid && io.req.bits.way_en(w).toBool
way.io.resp <> io.resp(w)
}
io.way_en := way_en_
io.req.ready := Bool(true)
}
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class AMOALU extends Component {
val io = new Bundle {
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val cmd = Bits(INPUT, 4)
val typ = Bits(INPUT, 3)
val lhs = UFix(INPUT, 64)
val rhs = UFix(INPUT, 64)
val out = UFix(OUTPUT, 64)
}
val sgned = (io.cmd === M_XA_MIN) || (io.cmd === M_XA_MAX)
val sub = (io.cmd === M_XA_MIN) || (io.cmd === M_XA_MINU) || (io.cmd === M_XA_MAX) || (io.cmd === M_XA_MAXU)
val min = (io.cmd === M_XA_MIN) || (io.cmd === M_XA_MINU)
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val word = (io.typ === MT_W) || (io.typ === MT_WU)
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val adder_out = (Cat(io.lhs, UFix(0,1)).toUFix + Cat(io.rhs ^ Fill(io.rhs.width, sub), sub).toUFix) >> UFix(1)
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val cmp_lhs = Mux(word, io.lhs(31), io.lhs(63))
val cmp_rhs = Mux(word, io.rhs(31), io.rhs(63))
val cmp_diff = Mux(word, adder_out(31), adder_out(63))
val less = Mux(cmp_lhs === cmp_rhs, cmp_diff, Mux(sgned, cmp_lhs, cmp_rhs))
val cmp_out = Mux(min === less, io.lhs, io.rhs)
val out = Mux(io.cmd === M_XA_ADD, adder_out,
Mux(io.cmd === M_XA_SWAP, io.rhs,
Mux(io.cmd === M_XA_AND, io.lhs & io.rhs,
Mux(io.cmd === M_XA_OR, io.lhs | io.rhs,
/* MIN[U]/MAX[U] */ cmp_out))));
io.out := Mux(word, Cat(out(31,0), out(31,0)).toUFix, out)
}
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class HellaCacheReq(implicit conf: DCacheConfig) extends Bundle {
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val kill = Bool()
val typ = Bits(width = 3)
val phys = Bool()
val addr = UFix(width = conf.ppnbits.max(conf.vpnbits+1) + conf.pgidxbits)
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val data = Bits(width = conf.databits)
val tag = Bits(width = conf.reqtagbits)
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val cmd = Bits(width = 4)
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override def clone = new HellaCacheReq().asInstanceOf[this.type]
}
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class HellaCacheResp(implicit conf: DCacheConfig) extends Bundle {
val miss = Bool()
val nack = Bool()
val replay = Bool()
val typ = Bits(width = 3)
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val data = Bits(width = conf.databits)
val data_subword = Bits(width = conf.databits)
val tag = Bits(width = conf.reqtagbits)
override def clone = new HellaCacheResp().asInstanceOf[this.type]
}
class AlignmentExceptions extends Bundle {
val ld = Bool()
val st = Bool()
}
class HellaCacheExceptions extends Bundle {
val ma = new AlignmentExceptions
val pf = new AlignmentExceptions
}
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// interface between D$ and processor/DTLB
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class ioHellaCache(implicit conf: DCacheConfig) extends Bundle {
val req = (new FIFOIO){ new HellaCacheReq }
val resp = (new PipeIO){ new HellaCacheResp }.flip
val xcpt = (new HellaCacheExceptions).asInput
val ptw = new IOTLBPTW().flip
}
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class HellaCache(implicit conf: DCacheConfig) extends Component {
val io = new Bundle {
val cpu = (new ioHellaCache).flip
val mem = new ioTileLink
}
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val lines = 1 << conf.idxbits
val indexbits = conf.idxbits
val tagmsb = conf.paddrbits-1
val taglsb = indexbits+conf.offbits
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val tagbits = tagmsb-taglsb+1
val indexmsb = taglsb-1
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val indexlsb = conf.offbits
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val offsetmsb = indexlsb-1
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val offsetlsb = log2Up(conf.databytes)
val ramindexlsb = log2Up(MEM_DATA_BITS/8)
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val early_nack = Reg { Bool() }
val r_cpu_req_val_ = Reg(io.cpu.req.valid && io.cpu.req.ready, resetVal = Bool(false))
val r_cpu_req_val = r_cpu_req_val_ && !io.cpu.req.bits.kill && !early_nack
val r_cpu_req_phys = Reg() { Bool() }
val r_cpu_req_vpn = Reg() { UFix() }
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val r_cpu_req_idx = Reg() { Bits() }
val r_cpu_req_cmd = Reg() { Bits() }
val r_cpu_req_type = Reg() { Bits() }
val r_cpu_req_tag = Reg() { Bits() }
val r_amo_replay_data = Reg() { Bits() }
val r_way_oh = Reg() { Bits() }
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val p_store_valid = Reg(resetVal = Bool(false))
val p_store_data = Reg() { Bits() }
val p_store_idx = Reg() { Bits() }
val p_store_cmd = Reg() { Bits() }
val p_store_type = Reg() { Bits() }
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val p_store_way_oh = Reg() { Bits() }
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val r_replay_amo = Reg(resetVal = Bool(false))
val req_store = (io.cpu.req.bits.cmd === M_XWR)
val req_load = (io.cpu.req.bits.cmd === M_XRD)
val req_amo = io.cpu.req.bits.cmd(3).toBool
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val req_read = req_load || req_amo
val req_write = req_store || req_amo
val r_req_load = (r_cpu_req_cmd === M_XRD)
val r_req_store = (r_cpu_req_cmd === M_XWR)
val r_req_flush = (r_cpu_req_cmd === M_FLA)
val r_req_fence = (r_cpu_req_cmd === M_FENCE)
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val r_req_prefetch = (r_cpu_req_cmd === M_PFR) || (r_cpu_req_cmd === M_PFW)
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val r_req_amo = r_cpu_req_cmd(3).toBool
val r_req_read = r_req_load || r_req_amo
val r_req_write = r_req_store || r_req_amo
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val r_req_readwrite = r_req_read || r_req_write || r_req_prefetch
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val nack_hit = Bool()
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val dtlb = new TLB(8)
dtlb.io.ptw <> io.cpu.ptw
dtlb.io.req.valid := r_cpu_req_val_ && r_req_readwrite && !r_cpu_req_phys
dtlb.io.req.bits.passthrough := r_cpu_req_phys
dtlb.io.req.bits.asid := UFix(0)
dtlb.io.req.bits.vpn := r_cpu_req_vpn
dtlb.io.req.bits.instruction := Bool(false)
val wb = new WritebackUnit
val prober = new ProbeUnit
val mshr = new MSHRFile
val flusher = new FlushUnit(lines)
val replay_amo_val = mshr.io.data_req.valid && mshr.io.data_req.bits.cmd(3).toBool
// reset and flush unit
val flushed = Reg(resetVal = Bool(true))
flushed := flushed && (!r_cpu_req_val || r_req_flush) || r_cpu_req_val && r_req_flush && mshr.io.fence_rdy && flusher.io.req.ready
flusher.io.req.valid := r_cpu_req_val && r_req_flush && mshr.io.fence_rdy && !flushed
flusher.io.mshr_req.ready := mshr.io.req.ready
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when (io.cpu.req.valid) {
r_cpu_req_phys := io.cpu.req.bits.phys
r_cpu_req_vpn := io.cpu.req.bits.addr >> taglsb
r_cpu_req_idx := io.cpu.req.bits.addr(indexmsb,0)
r_cpu_req_cmd := io.cpu.req.bits.cmd
r_cpu_req_type := io.cpu.req.bits.typ
r_cpu_req_tag := io.cpu.req.bits.tag
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}
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when (prober.io.meta_req.valid) {
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r_cpu_req_idx := Cat(prober.io.meta_req.bits.data.tag, prober.io.meta_req.bits.idx, mshr.io.data_req.bits.offset)(conf.pgidxbits-1,0)
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}
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when (mshr.io.data_req.valid) {
r_cpu_req_idx := Cat(mshr.io.data_req.bits.idx, mshr.io.data_req.bits.offset)
r_cpu_req_cmd := mshr.io.data_req.bits.cmd
r_cpu_req_type := mshr.io.data_req.bits.typ
r_amo_replay_data := mshr.io.data_req.bits.data
r_way_oh := mshr.io.data_req.bits.way_oh
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}
when (flusher.io.meta_req.valid) {
r_cpu_req_idx := Cat(flusher.io.meta_req.bits.idx, mshr.io.data_req.bits.offset)
r_cpu_req_cmd := M_FLA
r_way_oh := flusher.io.meta_req.bits.way_en
}
val cpu_req_data = Mux(r_replay_amo, r_amo_replay_data, io.cpu.req.bits.data)
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val misaligned =
(((r_cpu_req_type === MT_H) || (r_cpu_req_type === MT_HU)) && (r_cpu_req_idx(0) != Bits(0))) ||
(((r_cpu_req_type === MT_W) || (r_cpu_req_type === MT_WU)) && (r_cpu_req_idx(1,0) != Bits(0))) ||
((r_cpu_req_type === MT_D) && (r_cpu_req_idx(2,0) != Bits(0)));
io.cpu.xcpt.ma.ld := r_cpu_req_val_ && r_req_read && misaligned
io.cpu.xcpt.ma.st := r_cpu_req_val_ && r_req_write && misaligned
io.cpu.xcpt.pf.ld := r_cpu_req_val_ && r_req_read && dtlb.io.resp.xcpt_ld
io.cpu.xcpt.pf.st := r_cpu_req_val_ && r_req_write && dtlb.io.resp.xcpt_st
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// tags
val meta = new MetaDataArrayArray(lines)
val meta_arb = (new Arbiter(4)) { new MetaArrayReq() }
flusher.io.meta_req <> meta_arb.io.in(0)
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meta_arb.io.out <> meta.io.req
// data
val data = new DataArrayArray(lines)
val data_arb = (new Arbiter(5)) { new DataArrayReq() }
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data_arb.io.out <> data.io.req
// cpu tag check
meta_arb.io.in(3).valid := io.cpu.req.valid
meta_arb.io.in(3).bits.idx := io.cpu.req.bits.addr(indexmsb,indexlsb)
meta_arb.io.in(3).bits.rw := Bool(false)
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meta_arb.io.in(3).bits.way_en := Fix(-1)
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val early_tag_nack = !meta_arb.io.in(3).ready
val cpu_req_ppn = Mux(prober.io.mshr_req.valid, prober.io.addr >> UFix(conf.pgidxbits-conf.offbits), dtlb.io.resp.ppn)
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val cpu_req_tag = Cat(cpu_req_ppn, r_cpu_req_idx)(tagmsb,taglsb)
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val tag_match_arr = (0 until conf.ways).map( w => conf.co.isValid(meta.io.resp(w).state) && (meta.io.resp(w).tag === cpu_req_tag))
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val tag_match = Cat(Bits(0),tag_match_arr:_*).orR
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val tag_match_way_oh = Cat(Bits(0),tag_match_arr.reverse:_*)(conf.ways-1, 0) //TODO: use Vec
val tag_hit_arr = (0 until conf.ways).map( w => conf.co.isHit(r_cpu_req_cmd, meta.io.resp(w).state) && (meta.io.resp(w).tag === cpu_req_tag))
val tag_hit = Cat(Bits(0),tag_hit_arr:_*).orR
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val meta_resp_way_oh = Mux(meta.io.way_en.andR, tag_match_way_oh, meta.io.way_en)
val data_resp_way_oh = Mux(data.io.way_en.andR, tag_match_way_oh, data.io.way_en)
val meta_resp_mux = Mux1H(meta_resp_way_oh, meta.io.resp)
val data_resp_mux = Mux1H(data_resp_way_oh, data.io.resp)
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// writeback unit
wb.io.req <> mshr.io.wb_req
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wb.io.data_req <> data_arb.io.in(3)
wb.io.data_resp <> data_resp_mux
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wb.io.probe_rep_data <> io.mem.probe_rep_data
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// replacement policy
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val replacer = new RandomReplacement
val replaced_way_oh = Mux(flusher.io.mshr_req.valid, r_way_oh, UFixToOH(replacer.way))
val meta_wb_mux = Mux1H(replaced_way_oh, meta.io.resp)
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// refill response
data_arb.io.in(0).bits.offset := mshr.io.mem_resp_offset
data_arb.io.in(0).bits.idx := mshr.io.mem_resp_idx
data_arb.io.in(0).bits.rw := Bool(true)
data_arb.io.in(0).bits.wmask := ~UFix(0, MEM_DATA_BITS/8)
data_arb.io.in(0).bits.data := io.mem.xact_rep.bits.data
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data_arb.io.in(0).bits.way_en := mshr.io.mem_resp_way_oh
data_arb.io.in(0).valid := io.mem.xact_rep.valid && conf.co.messageUpdatesDataArray(io.mem.xact_rep.bits)
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// load hits
data_arb.io.in(4).bits.offset := io.cpu.req.bits.addr(offsetmsb,ramindexlsb)
data_arb.io.in(4).bits.idx := io.cpu.req.bits.addr(indexmsb,indexlsb)
data_arb.io.in(4).bits.rw := Bool(false)
data_arb.io.in(4).valid := io.cpu.req.valid && req_read
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data_arb.io.in(4).bits.way_en := Fix(-1) // intiate load on all ways, mux after tag check
val early_load_nack = !data_arb.io.in(4).ready
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// store hits and AMO hits and misses use a pending store register.
// we nack new stores if a pending store can't retire for some reason.
// we drain a pending store if the CPU performs a store or a
// conflictig load, or if the cache is idle, or after a miss.
val p_store_idx_match = p_store_valid && (r_cpu_req_idx(indexmsb,indexlsb) === p_store_idx(indexmsb,indexlsb))
val p_store_offset_match = (r_cpu_req_idx(indexlsb-1,offsetlsb) === p_store_idx(indexlsb-1,offsetlsb))
val p_store_match = r_cpu_req_val_ && r_req_read && p_store_idx_match && p_store_offset_match
val drain_store_val = (p_store_valid && (!io.cpu.req.valid || req_write || wb.io.data_req.valid || mshr.io.data_req.valid)) || p_store_match
data_arb.io.in(2).bits.offset := p_store_idx(offsetmsb,ramindexlsb)
data_arb.io.in(2).bits.idx := p_store_idx(indexmsb,indexlsb)
data_arb.io.in(2).bits.rw := Bool(true)
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data_arb.io.in(2).valid := drain_store_val
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data_arb.io.in(2).bits.way_en := p_store_way_oh
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val drain_store = drain_store_val && data_arb.io.in(2).ready
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val p_amo = Reg(resetVal = Bool(false))
val p_store_rdy = !(p_store_valid && !drain_store) && !(mshr.io.data_req.valid || r_replay_amo || p_amo)
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p_amo := r_cpu_req_val && tag_hit && r_req_amo && mshr.io.req.ready && !nack_hit || r_replay_amo
p_store_valid := p_store_valid && !drain_store || (r_cpu_req_val && tag_hit && r_req_store && mshr.io.req.ready && !nack_hit) || p_amo
// tag update after a store to an exclusive clean line.
val new_hit_state = conf.co.newStateOnHit(r_cpu_req_cmd, meta_resp_mux.state)
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val set_hit_state = r_cpu_req_val && tag_hit && meta_resp_mux.state != new_hit_state
meta.io.state_req.bits.rw := Bool(true)
meta.io.state_req.bits.idx := Reg(r_cpu_req_idx(indexmsb,indexlsb))
meta.io.state_req.bits.data.state := Reg(new_hit_state)
meta.io.state_req.bits.way_en := Reg(tag_match_way_oh)
meta.io.state_req.valid := Reg(set_hit_state, resetVal = Bool(false))
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// pending store data, also used for AMO RHS
val amoalu = new AMOALU
when (r_cpu_req_val_ && r_req_write && p_store_rdy || r_replay_amo) {
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p_store_idx := r_cpu_req_idx
p_store_type := r_cpu_req_type
p_store_cmd := r_cpu_req_cmd
p_store_way_oh := Mux(r_replay_amo, r_way_oh, tag_match_way_oh)
p_store_data := cpu_req_data
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}
when (p_amo) {
p_store_data := amoalu.io.out
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}
// miss handling
mshr.io.req.valid := r_cpu_req_val && r_req_readwrite && !nack_hit || flusher.io.mshr_req.valid
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mshr.io.req.bits.tag_miss := !tag_hit || flusher.io.mshr_req.valid
mshr.io.req.bits.old_dirty := conf.co.needsWriteback(meta_wb_mux.state) && (!tag_match || flusher.io.mshr_req.valid) // don't wb upgrades
mshr.io.req.bits.old_tag := meta_wb_mux.tag
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mshr.io.req.bits.tag := cpu_req_tag
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mshr.io.req.bits.idx := r_cpu_req_idx(indexmsb,indexlsb)
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mshr.io.req.bits.cpu_tag := r_cpu_req_tag
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mshr.io.req.bits.offset := r_cpu_req_idx(offsetmsb,0)
mshr.io.req.bits.cmd := r_cpu_req_cmd
mshr.io.req.bits.typ := r_cpu_req_type
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mshr.io.req.bits.way_oh := Mux(tag_match && !flusher.io.mshr_req.valid, tag_match_way_oh, replaced_way_oh)
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mshr.io.req.bits.data := cpu_req_data
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mshr.io.mem_rep <> io.mem.xact_rep
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mshr.io.mem_abort.valid := io.mem.xact_abort.valid
mshr.io.mem_abort.bits := io.mem.xact_abort.bits
io.mem.xact_abort.ready := Bool(true)
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mshr.io.meta_req <> meta_arb.io.in(1)
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when (mshr.io.req.fire()) { replacer.miss }
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// replays
val replay = mshr.io.data_req.bits
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val stall_replay = r_replay_amo || p_amo || flusher.io.meta_req.valid || p_store_valid
val replay_val = mshr.io.data_req.valid
val replay_fire = replay_val && !stall_replay
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val replay_rdy = data_arb.io.in(1).ready && !stall_replay
data_arb.io.in(1).bits.offset := replay.offset(offsetmsb,ramindexlsb)
data_arb.io.in(1).bits.idx := replay.idx
data_arb.io.in(1).bits.rw := replay.cmd === M_XWR
data_arb.io.in(1).valid := replay_fire
data_arb.io.in(1).bits.way_en := mshr.io.data_req.bits.way_oh
mshr.io.data_req.ready := replay_rdy
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r_replay_amo := replay_amo_val && replay_rdy
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// probes
prober.io.req <> io.mem.probe_req
prober.io.rep <> io.mem.probe_rep
prober.io.mshr_req <> mshr.io.probe
prober.io.wb_req <> wb.io.probe
prober.io.tag_match_way_oh := tag_match_way_oh
prober.io.line_state := meta_resp_mux.state
prober.io.meta_req.ready := meta_arb.io.in(2).ready && !replay_amo_val
meta_arb.io.in(2).valid := prober.io.meta_req.valid
meta_arb.io.in(2).bits := prober.io.meta_req.bits
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// store write mask generation.
// assumes store replays are higher-priority than pending stores.
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val store_offset = Mux(!replay_fire, p_store_idx(offsetmsb,0), replay.offset)
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val store_type = Mux(!replay_fire, p_store_type, replay.typ)
val store_wmask_wide = StoreGen(store_type, store_offset, Bits(0)).mask << Cat(store_offset(ramindexlsb-1,offsetlsb), Bits(0, log2Up(conf.databytes))).toUFix
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val store_data = Mux(!replay_fire, p_store_data, replay.data)
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val store_data_wide = Fill(MEM_DATA_BITS/conf.databits, store_data)
data_arb.io.in(1).bits.data := store_data_wide
data_arb.io.in(1).bits.wmask := store_wmask_wide
data_arb.io.in(2).bits.data := store_data_wide
data_arb.io.in(2).bits.wmask := store_wmask_wide
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// load data subword mux/sign extension.
// subword loads are delayed by one cycle.
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val loadgen_data = data_resp_mux >> Cat(r_cpu_req_idx(log2Up(MEM_DATA_BITS/8)-1,3), Bits(0,6))
val loadgen = LoadGen(r_cpu_req_type, r_cpu_req_idx, loadgen_data)
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amoalu.io.cmd := p_store_cmd
amoalu.io.typ := p_store_type
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amoalu.io.lhs := Reg(loadgen.word).toUFix
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amoalu.io.rhs := p_store_data.toUFix
early_nack := early_tag_nack || early_load_nack || r_cpu_req_val && r_req_amo || replay_amo_val || r_replay_amo
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// we usually nack rather than reporting that the cache is not ready.
// fences and flushes are the exceptions.
val pending_fence = Reg(resetVal = Bool(false))
pending_fence := (r_cpu_req_val_ && r_req_fence || pending_fence) && !mshr.io.fence_rdy
nack_hit := p_store_match || replay_val || r_req_write && !p_store_rdy ||
p_store_idx_match && meta.io.state_req.valid ||
!r_cpu_req_phys && dtlb.io.resp.miss
val nack_miss = !mshr.io.req.ready
val nack_flush = !mshr.io.fence_rdy && (r_req_fence || r_req_flush) ||
!flushed && r_req_flush
val nack = early_nack || r_req_readwrite && (nack_hit || nack_miss) || nack_flush
io.cpu.req.ready := flusher.io.req.ready && !(r_cpu_req_val_ && r_req_flush) && !pending_fence && (dtlb.io.req.ready || io.cpu.req.bits.phys)
io.cpu.resp.valid := (r_cpu_req_val && tag_hit && !mshr.io.secondary_miss && !nack && r_req_read) || mshr.io.cpu_resp_val
io.cpu.resp.bits.nack := r_cpu_req_val_ && !io.cpu.req.bits.kill && nack
io.cpu.resp.bits.replay := mshr.io.cpu_resp_val
io.cpu.resp.bits.miss := r_cpu_req_val_ && (!tag_hit || mshr.io.secondary_miss) && r_req_read
io.cpu.resp.bits.tag := Mux(mshr.io.cpu_resp_val, mshr.io.cpu_resp_tag, r_cpu_req_tag)
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io.cpu.resp.bits.typ := r_cpu_req_type
io.cpu.resp.bits.data := loadgen.word
io.cpu.resp.bits.data_subword := Reg(loadgen.byte)
val xact_init_arb = (new Arbiter(2)) { new TransactionInit }
xact_init_arb.io.in(0) <> wb.io.mem_req
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xact_init_arb.io.in(1).valid := mshr.io.mem_req.valid && prober.io.req.ready
mshr.io.mem_req.ready := xact_init_arb.io.in(1).ready && prober.io.req.ready
xact_init_arb.io.in(1).bits := mshr.io.mem_req.bits
io.mem.xact_init <> xact_init_arb.io.out
io.mem.xact_init_data <> wb.io.mem_req_data
io.mem.xact_finish <> mshr.io.mem_finish
}