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Improve QoR for FP->Int conversions

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This commit is contained in:
Andrew Waterman 2017-05-30 16:51:35 -07:00 committed by Wesley W. Terpstra
parent 07968df183
commit 84c4ae775f
1 changed files with 41 additions and 23 deletions
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64
src/main/scala/tile/FPU.scala
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@ -232,6 +232,7 @@ object FType {
trait HasFPUParameters {
val fLen: Int
val minXLen = 32
val (sExpWidth, sSigWidth) = (FType.S.exp, FType.S.sig)
val (dExpWidth, dSigWidth) = (FType.D.exp, FType.D.sig)
val floatTypes = FType.all.filter(_.ieeeWidth <= fLen)
@ -373,34 +374,55 @@ class FPToInt(implicit p: Parameters) extends FPUModule()(p) {
val in = RegEnable(io.in.bits, io.in.valid)
val valid = Reg(next=io.in.valid)
val tag = !in.singleIn
val classify_out = (floatTypes.map(t => t.classify(maxType.unsafeConvert(in.in1, t))): Seq[UInt])(tag)
val dcmp = Module(new hardfloat.CompareRecFN(maxExpWidth, maxSigWidth))
dcmp.io.a := in.in1
dcmp.io.b := in.in2
dcmp.io.signaling := !in.rm(1)
val tag = !in.singleOut
val store = ieee(in.in1)
val toint = Mux(in.rm(0), classify_out, store)
io.out.bits.store := Mux(in.singleOut, Fill(xLen/32, store(31, 0)), store)
io.out.bits.toint := Mux(in.singleOut, toint(31, 0).sextTo(xLen), toint)
val toint = Wire(init = store)
val intType = Wire(init = tag)
val nIntTypes = log2Ceil(xLen/minXLen) + 1
io.out.bits.store := ((0 until nIntTypes).map(i => Fill(1 << (nIntTypes - i - 1), store((minXLen << i) - 1, 0))): Seq[UInt])(tag)
io.out.bits.toint := ((0 until nIntTypes).map(i => toint((minXLen << i) - 1, 0).sextTo(xLen)): Seq[UInt])(intType)
io.out.bits.exc := Bits(0)
when (in.rm(0)) {
val classify_out = (floatTypes.map(t => t.classify(maxType.unsafeConvert(in.in1, t))): Seq[UInt])(tag)
toint := classify_out | (store >> minXLen << minXLen)
intType := 0
}
when (in.wflags) { // feq/flt/fle, fcvt
io.out.bits.toint := (~in.rm & Cat(dcmp.io.lt, dcmp.io.eq)).orR
toint := (~in.rm & Cat(dcmp.io.lt, dcmp.io.eq)).orR | (store >> minXLen << minXLen)
io.out.bits.exc := dcmp.io.exceptionFlags
intType := 0
when (!in.ren2) { // fcvt
val minXLen = 32
val n = log2Ceil(xLen/minXLen) + 1
for (i <- 0 until n) {
val conv = Module(new hardfloat.RecFNToIN(maxExpWidth, maxSigWidth, minXLen << i))
conv.io.in := in.in1
conv.io.roundingMode := in.rm
conv.io.signedOut := ~in.typ(0)
when (in.typ.extract(log2Ceil(n), 1) === i) {
io.out.bits.toint := conv.io.out.sextTo(xLen)
io.out.bits.exc := Cat(conv.io.intExceptionFlags(2, 1).orR, UInt(0, 3), conv.io.intExceptionFlags(0))
val cvtType = in.typ.extract(log2Ceil(nIntTypes), 1)
intType := cvtType
val conv = Module(new hardfloat.RecFNToIN(maxExpWidth, maxSigWidth, xLen))
conv.io.in := in.in1
conv.io.roundingMode := in.rm
conv.io.signedOut := ~in.typ(0)
toint := conv.io.out
io.out.bits.exc := Cat(conv.io.intExceptionFlags(2, 1).orR, UInt(0, 3), conv.io.intExceptionFlags(0))
for (i <- 0 until nIntTypes-1) {
val w = minXLen << i
when (cvtType === i) {
val narrow = Module(new hardfloat.RecFNToIN(maxExpWidth, maxSigWidth, w))
narrow.io.in := in.in1
narrow.io.roundingMode := in.rm
narrow.io.signedOut := ~in.typ(0)
val excSign = in.in1(maxExpWidth + maxSigWidth) && !maxType.isNaN(in.in1)
val excOut = Cat(conv.io.signedOut === excSign, Fill(w-1, !excSign))
val invalid = conv.io.intExceptionFlags(2) || narrow.io.intExceptionFlags(1)
when (invalid) { toint := Cat(conv.io.out >> w, excOut) }
io.out.bits.exc := Cat(invalid, UInt(0, 3), !invalid && conv.io.intExceptionFlags(0))
}
}
}
@ -424,7 +446,6 @@ class IntToFP(val latency: Int)(implicit p: Parameters) extends FPUModule()(p) {
mux.data := recode(in.bits.in1, !in.bits.singleIn)
val intValue = {
val minXLen = 32
val n = log2Ceil(xLen/minXLen) + 1
val res = Wire(init = in.bits.in1.asSInt)
for (i <- 0 until n-1) {
@ -490,15 +511,12 @@ class FPToFP(val latency: Int)(implicit p: Parameters) extends FPUModule()(p) {
fsgnjMux.data := Mux(isNaNOut, maxType.qNaN, Mux(isLHS, in.bits.in1, in.bits.in2))
}
val mux = Wire(new FPResult)
mux.exc := fsgnjMux.exc
val mux = Wire(init = fsgnjMux)
fLen match {
case 32 =>
mux.data := fsgnjMux.data
case 64 =>
val fsgnjSingle = maxType.unsafeConvert(fsgnjMux.data, FType.S)
mux.data := Mux(in.bits.singleOut, Cat(fsgnjMux.data >> fsgnjSingle.getWidth, fsgnjSingle), fsgnjMux.data)
when (in.bits.singleOut) { mux.data := Cat(fsgnjMux.data >> fsgnjSingle.getWidth, fsgnjSingle) }
when (in.bits.wflags && !in.bits.ren2) { // fcvt
val d2s = Module(new hardfloat.RecFNToRecFN(dExpWidth, dSigWidth, sExpWidth, sSigWidth))