riscv/rocket-chip
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Use Mem instead of Vec[Reg]

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This commit is contained in:
Andrew Waterman
2014-05-18 19:25:43 -07:00
parent e91e12ed88
commit cbb37ccc3e
2 changed files with 36 additions and 39 deletions
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73
rocket/src/main/scala/btb.scala
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@@ -81,29 +81,29 @@ class BTB(implicit conf: BTBConfig) extends Module {
val invalidate = Bool(INPUT)
}
val idxValid = Vec.fill(conf.entries){Reg(init=Bool(false))}
val idxs = Vec.fill(conf.entries){Reg(UInt(width=conf.matchBits))}
val idxPages = Vec.fill(conf.entries){Reg(UInt(width=log2Up(conf.pages)))}
val tgts = Vec.fill(conf.entries){Reg(UInt(width=conf.matchBits))}
val tgtPages = Vec.fill(conf.entries){Reg(UInt(width=log2Up(conf.pages)))}
val pages = Vec.fill(conf.pages){Reg(UInt(width=conf.as.vaddrBits-conf.matchBits))}
val pageValid = Vec.fill(conf.pages){Reg(init=Bool(false))}
val idxValid = Reg(init=UInt(0, conf.entries))
val idxs = Mem(UInt(width=conf.matchBits), conf.entries)
val idxPages = Mem(UInt(width=log2Up(conf.pages)), conf.entries)
val tgts = Mem(UInt(width=conf.matchBits), conf.entries)
val tgtPages = Mem(UInt(width=log2Up(conf.pages)), conf.entries)
val pages = Mem(UInt(width=conf.as.vaddrBits-conf.matchBits), conf.pages)
val pageValid = Reg(init=UInt(0, conf.pages))
val idxPagesOH = idxPages.map(UIntToOH(_)(conf.pages-1,0))
val tgtPagesOH = tgtPages.map(UIntToOH(_)(conf.pages-1,0))
val useRAS = Vec.fill(conf.entries){Reg(Bool())}
val isJump = Vec.fill(conf.entries){Reg(Bool())}
val useRAS = Mem(Bool(), conf.entries)
val isJump = Mem(Bool(), conf.entries)
private def page(addr: UInt) = addr >> conf.matchBits
private def pageMatch(addr: UInt) = {
val p = page(addr)
Vec(pages.map(_ === p)).toBits & pageValid.toBits
Vec(pages.map(_ === p)).toBits & pageValid
}
private def tagMatch(addr: UInt, pgMatch: UInt): UInt = {
val idx = addr(conf.matchBits-1,0)
val idxMatch = idxs.map(_ === idx).toBits
val idxPageMatch = idxPagesOH.map(_ & pgMatch).map(_.orR).toBits
idxValid.toBits & idxMatch & idxPageMatch
idxValid & idxMatch & idxPageMatch
}
val update = Pipe(io.update)
@@ -137,52 +137,49 @@ class BTB(implicit conf: BTBConfig) extends Module {
val tgtPageRepl = Mux(samePage, idxPageUpdateOH, idxPageUpdateOH(conf.pages-2,0) << 1 | idxPageUpdateOH(conf.pages-1))
val tgtPageUpdate = OHToUInt(Mux(usePageHit, pageHit, tgtPageRepl))
val tgtPageReplEn = Mux(doTgtPageRepl, tgtPageRepl, UInt(0))
val doPageRepl = doIdxPageRepl || doTgtPageRepl
val pageReplEn = idxPageReplEn | tgtPageReplEn
idxPageRepl := UIntToOH(Counter(update.valid && (doIdxPageRepl || doTgtPageRepl), conf.pages)._1)
idxPageRepl := UIntToOH(Counter(update.valid && doPageRepl, conf.pages)._1)
when (update.valid && !(updateValid && !updateTarget)) {
val nextRepl = Counter(!updateHit && updateValid, conf.entries)._1
val waddr = Mux(updateHit, update.bits.prediction.bits.entry, nextRepl)
for (i <- 0 until conf.entries) {
when ((pageReplEn & (idxPagesOH(i) | tgtPagesOH(i))).orR) {
idxValid(i) := false
}
when (waddr === i) {
idxValid(i) := updateValid
when (updateTarget) {
if (i == 0) assert(io.req === update.bits.target, "BTB request != I$ target")
idxs(i) := update.bits.pc
idxPages(i) := idxPageUpdate
tgts(i) := update_target
tgtPages(i) := tgtPageUpdate
useRAS(i) := update.bits.isReturn
isJump(i) := update.bits.isJump
}
}
when (doPageRepl) {
val clearValid = for (i <- 0 until conf.entries)
yield (pageReplEn & (idxPagesOH(i) | tgtPagesOH(i))).orR
idxValid := idxValid & ~Vec(clearValid).toBits
}
when (updateTarget) {
assert(io.req === update.bits.target, "BTB request != I$ target")
idxValid := idxValid.bitSet(waddr, updateValid)
idxs(waddr) := update.bits.pc
tgts(waddr) := update_target
idxPages(waddr) := idxPageUpdate
tgtPages(waddr) := tgtPageUpdate
useRAS(waddr) := update.bits.isReturn
isJump(waddr) := update.bits.isJump
}
require(conf.pages % 2 == 0)
val idxWritesEven = (idxPageUpdateOH & Fill(conf.pages/2, UInt(1,2))).orR
def writeBank(i: Int, mod: Int, en: Bool, data: UInt) = {
for (i <- i until conf.pages by mod) {
when (en && pageReplEn(i)) {
pages(i) := data
pageValid(i) := true
}
}
}
def writeBank(i: Int, mod: Int, en: Bool, data: UInt) =
for (i <- i until conf.pages by mod)
when (en && pageReplEn(i)) { pages(i) := data }
writeBank(0, 2, Mux(idxWritesEven, doIdxPageRepl, doTgtPageRepl),
Mux(idxWritesEven, page(update.bits.pc), page(update_target)))
writeBank(1, 2, Mux(idxWritesEven, doTgtPageRepl, doIdxPageRepl),
Mux(idxWritesEven, page(update_target), page(update.bits.pc)))
when (doPageRepl) { pageValid := pageValid | pageReplEn }
}
when (io.invalidate) {
idxValid.foreach(_ := false)
pageValid.foreach(_ := false)
idxValid := 0
pageValid := 0
}
io.resp.valid := hits.toBits.orR