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Improve probe state machine 

- Reduce reliance on s2_prb_ack_data due to future ECC changes
- Shave a cycle off valid, but clean, probes
- Code cleanup
This commit is contained in:
Andrew Waterman 2017-06-28 15:24:58 -07:00
parent 85f37146d5
commit e9752f76ae
1 changed files with 27 additions and 33 deletions
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60
src/main/scala/rocket/DCache.scala
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@ -430,29 +430,9 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
val s2_release_data_valid = Reg(next = s1_release_data_valid && !releaseRejected)
val releaseDataBeat = Cat(UInt(0), c_count) + Mux(releaseRejected, UInt(0), s1_release_data_valid + Cat(UInt(0), s2_release_data_valid))
val nackResponseMessage = edge.ProbeAck(
b = probe_bits,
reportPermissions = TLPermissions.NtoN)
val voluntaryReleaseMessage = if (edge.manager.anySupportAcquireB) {
edge.Release(
fromSource = UInt(0),
toAddress = probe_bits.address,
lgSize = lgCacheBlockBytes,
shrinkPermissions = s2_shrink_param,
data = 0.U)._2
} else {
Wire(new TLBundleC(edge.bundle))
}
val probeResponseMessage = Mux(!s2_prb_ack_data,
edge.ProbeAck(
b = probe_bits,
reportPermissions = s2_report_param),
edge.ProbeAck(
b = probe_bits,
reportPermissions = s2_report_param,
data = 0.U))
val nackResponseMessage = edge.ProbeAck(b = probe_bits, reportPermissions = TLPermissions.NtoN)
val cleanReleaseMessage = edge.ProbeAck(b = probe_bits, reportPermissions = s2_report_param)
val dirtyReleaseMessage = edge.ProbeAck(b = probe_bits, reportPermissions = s2_report_param, data = 0.U)
tl_out.c.valid := s2_release_data_valid
tl_out.c.bits := nackResponseMessage
@ -465,29 +445,43 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
probe_bits.address := Cat(s2_victim_tag, s2_req.addr(idxMSB, idxLSB)) << idxLSB
}
when (s2_probe) {
when (s2_prb_ack_data) { release_state := s_probe_rep_dirty }
.elsewhen (s2_probe_state.isValid()) { release_state := s_probe_rep_clean }
.otherwise {
when (s2_prb_ack_data) {
release_state := s_probe_rep_dirty
}.elsewhen (s2_probe_state.isValid()) {
tl_out.c.valid := true
release_state := s_probe_rep_miss
tl_out.c.bits := cleanReleaseMessage
release_state := Mux(releaseDone, s_probe_write_meta, s_probe_rep_clean)
}.otherwise {
tl_out.c.valid := true
release_state := Mux(releaseDone, s_ready, s_probe_rep_miss)
}
}
when (releaseDone) { release_state := s_ready }
when (release_state.isOneOf(s_probe_rep_miss, s_probe_rep_clean)) {
when (release_state === s_probe_rep_miss) {
tl_out.c.valid := true
when (releaseDone) { release_state := s_ready }
}
when (release_state.isOneOf(s_probe_rep_clean, s_probe_rep_dirty)) {
tl_out.c.bits := probeResponseMessage
when (release_state === s_probe_rep_clean) {
tl_out.c.valid := true
tl_out.c.bits := cleanReleaseMessage
when (releaseDone) { release_state := s_probe_write_meta }
}
when (release_state === s_probe_rep_dirty) {
tl_out.c.bits := dirtyReleaseMessage
when (releaseDone) { release_state := s_probe_write_meta }
}
when (release_state.isOneOf(s_voluntary_writeback, s_voluntary_write_meta)) {
tl_out.c.bits := voluntaryReleaseMessage
if (edge.manager.anySupportAcquireB)
tl_out.c.bits := edge.Release(fromSource = 0.U,
toAddress = 0.U,
lgSize = lgCacheBlockBytes,
shrinkPermissions = s2_shrink_param,
data = 0.U)._2
newCoh := voluntaryNewCoh
releaseWay := s2_victim_way
when (releaseDone) { release_state := s_voluntary_write_meta }
when (tl_out.c.fire() && c_first) { release_ack_wait := true }
}
when (s2_probe && !tl_out.c.fire()) { s1_nack := true }
when (s2_probe && s2_probe_state.isValid()) { s1_nack := true }
tl_out.c.bits.address := probe_bits.address
tl_out.c.bits.data := s2_data_corrected