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rocket-chip/rocket/src/main/scala/fpu.scala
Andrew Waterman 95de358a96 More of the same FPU fix
some SP ops followed by DP stores were not working because they
were encoded as subnormals, not NaNs.
2014-01-17 14:09:30 -08:00

588 lines
21 KiB
Scala

package rocket
import Chisel._
import Instructions._
import Util._
import FPConstants._
import uncore.constants.MemoryOpConstants._
object FPConstants
{
val FCMD_ADD = Bits("b000000")
val FCMD_SUB = Bits("b000001")
val FCMD_MUL = Bits("b000010")
val FCMD_DIV = Bits("b000011")
val FCMD_SQRT = Bits("b000100")
val FCMD_SGNJ = Bits("b000101")
val FCMD_SGNJN = Bits("b000110")
val FCMD_SGNJX = Bits("b000111")
val FCMD_CVT_L_FMT = Bits("b001000")
val FCMD_CVT_LU_FMT = Bits("b001001")
val FCMD_CVT_W_FMT = Bits("b001010")
val FCMD_CVT_WU_FMT = Bits("b001011")
val FCMD_CVT_FMT_L = Bits("b001100")
val FCMD_CVT_FMT_LU = Bits("b001101")
val FCMD_CVT_FMT_W = Bits("b001110")
val FCMD_CVT_FMT_WU = Bits("b001111")
val FCMD_CVT_FMT_S = Bits("b010000")
val FCMD_CVT_FMT_D = Bits("b010001")
val FCMD_EQ = Bits("b010101")
val FCMD_LT = Bits("b010110")
val FCMD_LE = Bits("b010111")
val FCMD_MIN = Bits("b011000")
val FCMD_MAX = Bits("b011001")
val FCMD_MFTX = Bits("b011100")
val FCMD_MXTF = Bits("b011110")
val FCMD_MADD = Bits("b100100")
val FCMD_MSUB = Bits("b100101")
val FCMD_NMSUB = Bits("b100110")
val FCMD_NMADD = Bits("b100111")
val FCMD_LOAD = Bits("b111000")
val FCMD_STORE = Bits("b111001")
val FCMD_X = Bits("b??????")
val FCMD_WIDTH = 6
val RM_SZ = 3
val FLAGS_SZ = 5
}
class FPUCtrlSigs extends Bundle
{
val cmd = Bits(width = FCMD_WIDTH)
val wen = Bool()
val ren1 = Bool()
val ren2 = Bool()
val ren3 = Bool()
val single = Bool()
val fromint = Bool()
val toint = Bool()
val fastpipe = Bool()
val fma = Bool()
val round = Bool()
}
class FPUDecoder extends Module
{
val io = new Bundle {
val inst = Bits(INPUT, 32)
val sigs = new FPUCtrlSigs().asOutput
}
val N = Bool(false)
val Y = Bool(true)
val X = Bool(false)
val decoder = DecodeLogic(io.inst,
List (FCMD_X, X,X,X,X,X,X,X,X,X,X),
Array(FLW -> List(FCMD_LOAD, Y,N,N,N,Y,N,N,N,N,N),
FLD -> List(FCMD_LOAD, Y,N,N,N,N,N,N,N,N,N),
FSW -> List(FCMD_STORE, N,N,Y,N,Y,N,Y,N,N,N),
FSD -> List(FCMD_STORE, N,N,Y,N,N,N,Y,N,N,N),
FMV_S_X -> List(FCMD_MXTF, Y,N,N,N,Y,Y,N,N,N,Y),
FMV_D_X -> List(FCMD_MXTF, Y,N,N,N,N,Y,N,N,N,Y),
FCVT_S_W -> List(FCMD_CVT_FMT_W, Y,N,N,N,Y,Y,N,N,N,Y),
FCVT_S_WU-> List(FCMD_CVT_FMT_WU,Y,N,N,N,Y,Y,N,N,N,Y),
FCVT_S_L -> List(FCMD_CVT_FMT_L, Y,N,N,N,Y,Y,N,N,N,Y),
FCVT_S_LU-> List(FCMD_CVT_FMT_LU,Y,N,N,N,Y,Y,N,N,N,Y),
FCVT_D_W -> List(FCMD_CVT_FMT_W, Y,N,N,N,N,Y,N,N,N,Y),
FCVT_D_WU-> List(FCMD_CVT_FMT_WU,Y,N,N,N,N,Y,N,N,N,Y),
FCVT_D_L -> List(FCMD_CVT_FMT_L, Y,N,N,N,N,Y,N,N,N,Y),
FCVT_D_LU-> List(FCMD_CVT_FMT_LU,Y,N,N,N,N,Y,N,N,N,Y),
FMV_X_S -> List(FCMD_MFTX, N,Y,N,N,Y,N,Y,N,N,Y),
FMV_X_D -> List(FCMD_MFTX, N,Y,N,N,N,N,Y,N,N,Y),
FCVT_W_S -> List(FCMD_CVT_W_FMT, N,Y,N,N,Y,N,Y,N,N,Y),
FCVT_WU_S-> List(FCMD_CVT_WU_FMT,N,Y,N,N,Y,N,Y,N,N,Y),
FCVT_L_S -> List(FCMD_CVT_L_FMT, N,Y,N,N,Y,N,Y,N,N,Y),
FCVT_LU_S-> List(FCMD_CVT_LU_FMT,N,Y,N,N,Y,N,Y,N,N,Y),
FCVT_W_D -> List(FCMD_CVT_W_FMT, N,Y,N,N,N,N,Y,N,N,Y),
FCVT_WU_D-> List(FCMD_CVT_WU_FMT,N,Y,N,N,N,N,Y,N,N,Y),
FCVT_L_D -> List(FCMD_CVT_L_FMT, N,Y,N,N,N,N,Y,N,N,Y),
FCVT_LU_D-> List(FCMD_CVT_LU_FMT,N,Y,N,N,N,N,Y,N,N,Y),
FCVT_S_D -> List(FCMD_CVT_FMT_D, Y,Y,N,N,Y,N,N,Y,N,Y),
FCVT_D_S -> List(FCMD_CVT_FMT_S, Y,Y,N,N,N,N,N,Y,N,Y),
FEQ_S -> List(FCMD_EQ, N,Y,Y,N,Y,N,Y,N,N,Y),
FLT_S -> List(FCMD_LT, N,Y,Y,N,Y,N,Y,N,N,Y),
FLE_S -> List(FCMD_LE, N,Y,Y,N,Y,N,Y,N,N,Y),
FEQ_D -> List(FCMD_EQ, N,Y,Y,N,N,N,Y,N,N,Y),
FLT_D -> List(FCMD_LT, N,Y,Y,N,N,N,Y,N,N,Y),
FLE_D -> List(FCMD_LE, N,Y,Y,N,N,N,Y,N,N,Y),
FSGNJ_S -> List(FCMD_SGNJ, Y,Y,Y,N,Y,N,N,Y,N,Y),
FSGNJN_S -> List(FCMD_SGNJN, Y,Y,Y,N,Y,N,N,Y,N,Y),
FSGNJX_S -> List(FCMD_SGNJX, Y,Y,Y,N,Y,N,N,Y,N,Y),
FSGNJ_D -> List(FCMD_SGNJ, Y,Y,Y,N,N,N,N,Y,N,Y),
FSGNJN_D -> List(FCMD_SGNJN, Y,Y,Y,N,N,N,N,Y,N,Y),
FSGNJX_D -> List(FCMD_SGNJX, Y,Y,Y,N,N,N,N,Y,N,Y),
FMIN_S -> List(FCMD_MIN, Y,Y,Y,N,Y,N,Y,Y,N,Y),
FMAX_S -> List(FCMD_MAX, Y,Y,Y,N,Y,N,Y,Y,N,Y),
FMIN_D -> List(FCMD_MIN, Y,Y,Y,N,N,N,Y,Y,N,Y),
FMAX_D -> List(FCMD_MAX, Y,Y,Y,N,N,N,Y,Y,N,Y),
FADD_S -> List(FCMD_ADD, Y,Y,Y,N,Y,N,N,N,Y,Y),
FSUB_S -> List(FCMD_SUB, Y,Y,Y,N,Y,N,N,N,Y,Y),
FMUL_S -> List(FCMD_MUL, Y,Y,Y,N,Y,N,N,N,Y,Y),
FADD_D -> List(FCMD_ADD, Y,Y,Y,N,N,N,N,N,Y,Y),
FSUB_D -> List(FCMD_SUB, Y,Y,Y,N,N,N,N,N,Y,Y),
FMUL_D -> List(FCMD_MUL, Y,Y,Y,N,N,N,N,N,Y,Y),
FMADD_S -> List(FCMD_MADD, Y,Y,Y,Y,Y,N,N,N,Y,Y),
FMSUB_S -> List(FCMD_MSUB, Y,Y,Y,Y,Y,N,N,N,Y,Y),
FNMADD_S -> List(FCMD_NMADD, Y,Y,Y,Y,Y,N,N,N,Y,Y),
FNMSUB_S -> List(FCMD_NMSUB, Y,Y,Y,Y,Y,N,N,N,Y,Y),
FMADD_D -> List(FCMD_MADD, Y,Y,Y,Y,N,N,N,N,Y,Y),
FMSUB_D -> List(FCMD_MSUB, Y,Y,Y,Y,N,N,N,N,Y,Y),
FNMADD_D -> List(FCMD_NMADD, Y,Y,Y,Y,N,N,N,N,Y,Y),
FNMSUB_D -> List(FCMD_NMSUB, Y,Y,Y,Y,N,N,N,N,Y,Y)
))
val cmd :: wen :: ren1 :: ren2 :: ren3 :: single :: fromint :: toint :: fastpipe :: fma :: round :: Nil = decoder
io.sigs.cmd := cmd
io.sigs.wen := wen.toBool
io.sigs.ren1 := ren1.toBool
io.sigs.ren2 := ren2.toBool
io.sigs.ren3 := ren3.toBool
io.sigs.single := single.toBool
io.sigs.fromint := fromint.toBool
io.sigs.toint := toint.toBool
io.sigs.fastpipe := fastpipe.toBool
io.sigs.fma := fma.toBool
io.sigs.round := round.toBool
}
class DpathFPUIO extends Bundle {
val inst = Bits(OUTPUT, 32)
val fromint_data = Bits(OUTPUT, 64)
val fcsr_rm = Bits(OUTPUT, FPConstants.RM_SZ)
val fcsr_flags = Valid(Bits(width = FPConstants.FLAGS_SZ)).flip
val store_data = Bits(INPUT, 64)
val toint_data = Bits(INPUT, 64)
val dmem_resp_val = Bool(OUTPUT)
val dmem_resp_type = Bits(OUTPUT, 3)
val dmem_resp_tag = UInt(OUTPUT, 5)
val dmem_resp_data = Bits(OUTPUT, 64)
}
class CtrlFPUIO extends Bundle {
val valid = Bool(OUTPUT)
val fcsr_rdy = Bool(INPUT)
val nack_mem = Bool(INPUT)
val illegal_rm = Bool(INPUT)
val killx = Bool(OUTPUT)
val killm = Bool(OUTPUT)
val dec = new FPUCtrlSigs().asInput
val sboard_set = Bool(INPUT)
val sboard_clr = Bool(INPUT)
val sboard_clra = UInt(INPUT, 5)
}
class FPToInt extends Module
{
class Input extends Bundle {
val single = Bool()
val cmd = Bits(width = FCMD_WIDTH)
val rm = Bits(width = 3)
val in1 = Bits(width = 65)
val in2 = Bits(width = 65)
override def clone = new Input().asInstanceOf[this.type]
}
val io = new Bundle {
val in = Valid(new Input).flip
val out = Valid(new Bundle {
val lt = Bool()
val store = Bits(width = 64)
val toint = Bits(width = 64)
val exc = Bits(width = 5)
})
}
val in = Reg(new Input)
val valid = Reg(next=io.in.valid)
when (io.in.valid) {
def upconvert(x: UInt) = hardfloat.recodedFloatNToRecodedFloatM(x, Bits(0), 23, 9, 52, 12)._1
when (io.in.bits.cmd === FCMD_STORE) {
in.in1 := io.in.bits.in2
}.otherwise {
val doUpconvert = io.in.bits.single && io.in.bits.cmd != FCMD_MFTX
in.in1 := Mux(doUpconvert, upconvert(io.in.bits.in1), io.in.bits.in1)
in.in2 := Mux(doUpconvert, upconvert(io.in.bits.in2), io.in.bits.in2)
}
in.single := io.in.bits.single
in.cmd := io.in.bits.cmd
in.rm := io.in.bits.rm
}
val unrec_s = hardfloat.recodedFloatNToFloatN(in.in1, 23, 9)
val unrec_d = hardfloat.recodedFloatNToFloatN(in.in1, 52, 12)
val unrec_out = Mux(in.single, Cat(Fill(32, unrec_s(31)), unrec_s), unrec_d)
val dcmp = Module(new hardfloat.recodedFloatNCompare(52, 12))
dcmp.io.a := in.in1
dcmp.io.b := in.in2
val dcmp_out = (in.cmd & Cat(dcmp.io.a_lt_b, dcmp.io.a_eq_b)).orR
val dcmp_exc = (in.cmd & Cat(dcmp.io.a_lt_b_invalid, dcmp.io.a_eq_b_invalid)).orR << UInt(4)
val d2i = hardfloat.recodedFloatNToAny(in.in1, in.rm, ~in.cmd(1,0), 52, 12, 64)
io.out.bits.toint := unrec_out
io.out.bits.store := unrec_out
io.out.bits.exc := Bits(0)
when (in.cmd === FCMD_CVT_W_FMT || in.cmd === FCMD_CVT_WU_FMT) {
io.out.bits.toint := Cat(Fill(32, d2i._1(31)), d2i._1(31,0))
io.out.bits.exc := d2i._2
}
when (in.cmd === FCMD_CVT_L_FMT || in.cmd === FCMD_CVT_LU_FMT) {
io.out.bits.toint := d2i._1
io.out.bits.exc := d2i._2
}
when (in.cmd === FCMD_EQ || in.cmd === FCMD_LT || in.cmd === FCMD_LE) {
io.out.bits.toint := dcmp_out
io.out.bits.exc := dcmp_exc
}
io.out.valid := valid
io.out.bits.lt := dcmp.io.a_lt_b
}
class FPResult extends Bundle
{
val data = Bits(width = 65)
val exc = Bits(width = 5)
}
class IntToFP(val latency: Int) extends Module
{
class Input extends Bundle {
val single = Bool()
val cmd = Bits(width = FCMD_WIDTH)
val rm = Bits(width = 3)
val data = Bits(width = 64)
override def clone = new Input().asInstanceOf[this.type]
}
val io = new Bundle {
val in = Valid(new Input).flip
val out = Valid(new FPResult)
}
val in = Pipe(io.in)
val mux = new FPResult
mux.exc := Bits(0)
mux.data := hardfloat.floatNToRecodedFloatN(in.bits.data, 52, 12)
when (in.bits.single) {
mux.data := Cat(SInt(-1, 32), hardfloat.floatNToRecodedFloatN(in.bits.data, 23, 9))
}
when (in.bits.cmd === FCMD_CVT_FMT_W || in.bits.cmd === FCMD_CVT_FMT_WU ||
in.bits.cmd === FCMD_CVT_FMT_L || in.bits.cmd === FCMD_CVT_FMT_LU) {
when (in.bits.single) {
val u = hardfloat.anyToRecodedFloatN(in.bits.data, in.bits.rm, ~in.bits.cmd(1,0), 23, 9, 64)
mux.data := Cat(SInt(-1, 32), u._1)
mux.exc := u._2
}.otherwise {
val u = hardfloat.anyToRecodedFloatN(in.bits.data, in.bits.rm, ~in.bits.cmd(1,0), 52, 12, 64)
mux.data := u._1
mux.exc := u._2
}
}
io.out <> Pipe(in.valid, mux, latency-1)
}
class FPToFP(val latency: Int) extends Module
{
class Input extends Bundle {
val single = Bool()
val cmd = Bits(width = FCMD_WIDTH)
val rm = Bits(width = 3)
val in1 = Bits(width = 65)
val in2 = Bits(width = 65)
override def clone = new Input().asInstanceOf[this.type]
}
val io = new Bundle {
val in = Valid(new Input).flip
val out = Valid(new FPResult)
val lt = Bool(INPUT) // from FPToInt
}
val in = Pipe(io.in)
// fp->fp units
val sign_s = Mux(in.bits.cmd === FCMD_SGNJ, in.bits.in2(32),
Mux(in.bits.cmd === FCMD_SGNJN, ~in.bits.in2(32),
in.bits.in1(32) ^ in.bits.in2(32))) // FCMD_SGNJX
val sign_d = Mux(in.bits.cmd === FCMD_SGNJ, in.bits.in2(64),
Mux(in.bits.cmd === FCMD_SGNJN, ~in.bits.in2(64),
in.bits.in1(64) ^ in.bits.in2(64))) // FCMD_SGNJX
val fsgnj = Cat(Mux(in.bits.single, in.bits.in1(64), sign_d), in.bits.in1(63,33),
Mux(in.bits.single, sign_s, in.bits.in1(32)), in.bits.in1(31,0))
val s2d = hardfloat.recodedFloatNToRecodedFloatM(in.bits.in1, in.bits.rm, 23, 9, 52, 12)
val d2s = hardfloat.recodedFloatNToRecodedFloatM(in.bits.in1, in.bits.rm, 52, 12, 23, 9)
val isnan1 = Mux(in.bits.single, in.bits.in1(31,29) === Bits("b111"), in.bits.in1(63,61) === Bits("b111"))
val isnan2 = Mux(in.bits.single, in.bits.in2(31,29) === Bits("b111"), in.bits.in2(63,61) === Bits("b111"))
val issnan1 = isnan1 && ~Mux(in.bits.single, in.bits.in1(22), in.bits.in1(51))
val issnan2 = isnan2 && ~Mux(in.bits.single, in.bits.in2(22), in.bits.in2(51))
val minmax_exc = Cat(issnan1 || issnan2, Bits(0,4))
val min = in.bits.cmd === FCMD_MIN
val minmax = Mux(isnan2 || !isnan1 && (min === io.lt), in.bits.in1, in.bits.in2)
val mux = new FPResult
mux.data := fsgnj
mux.exc := Bits(0)
when (in.bits.cmd === FCMD_MIN || in.bits.cmd === FCMD_MAX) {
mux.data := minmax
}
when (in.bits.cmd === FCMD_CVT_FMT_S || in.bits.cmd === FCMD_CVT_FMT_D) {
when (in.bits.single) {
mux.data := Cat(SInt(-1, 32), d2s._1)
mux.exc := d2s._2
}.otherwise {
mux.data := s2d._1
mux.exc := s2d._2
}
}
io.out <> Pipe(in.valid, mux, latency-1)
}
class ioFMA(width: Int) extends Bundle {
val valid = Bool(INPUT)
val cmd = Bits(INPUT, FCMD_WIDTH)
val rm = Bits(INPUT, 3)
val in1 = Bits(INPUT, width)
val in2 = Bits(INPUT, width)
val in3 = Bits(INPUT, width)
val out = Bits(OUTPUT, width)
val exc = Bits(OUTPUT, 5)
}
class FPUSFMAPipe(val latency: Int) extends Module
{
val io = new ioFMA(33)
val cmd = Reg(Bits())
val rm = Reg(Bits())
val in1 = Reg(Bits())
val in2 = Reg(Bits())
val in3 = Reg(Bits())
val cmd_fma = io.cmd === FCMD_MADD || io.cmd === FCMD_MSUB ||
io.cmd === FCMD_NMADD || io.cmd === FCMD_NMSUB
val cmd_addsub = io.cmd === FCMD_ADD || io.cmd === FCMD_SUB
val one = Bits("h80000000")
val zero = Cat(io.in1(32) ^ io.in2(32), Bits(0, 32))
val valid = Reg(next=io.valid)
when (io.valid) {
cmd := Cat(io.cmd(1) & (cmd_fma || cmd_addsub), io.cmd(0))
rm := io.rm
in1 := io.in1
in2 := Mux(cmd_addsub, one, io.in2)
in3 := Mux(cmd_fma, io.in3, Mux(cmd_addsub, io.in2, zero))
}
val fma = Module(new hardfloat.mulAddSubRecodedFloatN(23, 9))
fma.io.op := cmd
fma.io.roundingMode := rm
fma.io.a := in1
fma.io.b := in2
fma.io.c := in3
io.out := Pipe(valid, fma.io.out, latency-1).bits
io.exc := Pipe(valid, fma.io.exceptionFlags, latency-1).bits
}
class FPUDFMAPipe(val latency: Int) extends Module
{
val io = new ioFMA(65)
val cmd = Reg(Bits())
val rm = Reg(Bits())
val in1 = Reg(Bits())
val in2 = Reg(Bits())
val in3 = Reg(Bits())
val cmd_fma = io.cmd === FCMD_MADD || io.cmd === FCMD_MSUB ||
io.cmd === FCMD_NMADD || io.cmd === FCMD_NMSUB
val cmd_addsub = io.cmd === FCMD_ADD || io.cmd === FCMD_SUB
val one = Bits("h8000000000000000")
val zero = Cat(io.in1(64) ^ io.in2(64), Bits(0, 64))
val valid = Reg(next=io.valid)
when (io.valid) {
cmd := Cat(io.cmd(1) & (cmd_fma || cmd_addsub), io.cmd(0))
rm := io.rm
in1 := io.in1
in2 := Mux(cmd_addsub, one, io.in2)
in3 := Mux(cmd_fma, io.in3, Mux(cmd_addsub, io.in2, zero))
}
val fma = Module(new hardfloat.mulAddSubRecodedFloatN(52, 12))
fma.io.op := cmd
fma.io.roundingMode := rm
fma.io.a := in1
fma.io.b := in2
fma.io.c := in3
io.out := Pipe(valid, fma.io.out, latency-1).bits
io.exc := Pipe(valid, fma.io.exceptionFlags, latency-1).bits
}
class FPU(sfma_latency: Int, dfma_latency: Int) extends Module
{
val io = new Bundle {
val ctrl = (new CtrlFPUIO).flip
val dpath = (new DpathFPUIO).flip
val sfma = new ioFMA(33)
val dfma = new ioFMA(65)
}
val ex_reg_inst = Reg(Bits())
when (io.ctrl.valid) {
ex_reg_inst := io.dpath.inst
}
val ex_reg_valid = Reg(next=io.ctrl.valid, init=Bool(false))
val mem_reg_valid = Reg(next=ex_reg_valid && !io.ctrl.killx, init=Bool(false))
val killm = io.ctrl.killm || io.ctrl.nack_mem
val wb_reg_valid = Reg(next=mem_reg_valid && !killm, init=Bool(false))
val fp_decoder = Module(new FPUDecoder)
fp_decoder.io.inst := io.dpath.inst
val ctrl = RegEnable(fp_decoder.io.sigs, io.ctrl.valid)
val mem_ctrl = RegEnable(ctrl, ex_reg_valid)
val wb_ctrl = RegEnable(mem_ctrl, mem_reg_valid)
// load response
val load_wb = Reg(next=io.dpath.dmem_resp_val)
val load_wb_single = RegEnable(io.dpath.dmem_resp_type === MT_W || io.dpath.dmem_resp_type === MT_WU, io.dpath.dmem_resp_val)
val load_wb_data = RegEnable(io.dpath.dmem_resp_data, io.dpath.dmem_resp_val)
val load_wb_tag = RegEnable(io.dpath.dmem_resp_tag, io.dpath.dmem_resp_val)
val rec_s = hardfloat.floatNToRecodedFloatN(load_wb_data, 23, 9)
val rec_d = hardfloat.floatNToRecodedFloatN(load_wb_data, 52, 12)
val load_wb_data_recoded = Mux(load_wb_single, Cat(SInt(-1, 32), rec_s), rec_d)
// regfile
val regfile = Mem(Bits(width = 65), 32)
when (load_wb) { regfile(load_wb_tag) := load_wb_data_recoded }
val ex_rs1 = regfile(ex_reg_inst(19,15))
val ex_rs2 = regfile(ex_reg_inst(24,20))
val ex_rs3 = regfile(ex_reg_inst(31,27))
val ex_rm = Mux(ex_reg_inst(14,12) === Bits(7), io.dpath.fcsr_rm, ex_reg_inst(14,12))
val fpiu = Module(new FPToInt)
fpiu.io.in.valid := ex_reg_valid && ctrl.toint
fpiu.io.in.bits := ctrl
fpiu.io.in.bits.rm := ex_rm
fpiu.io.in.bits.in1 := ex_rs1
fpiu.io.in.bits.in2 := ex_rs2
io.dpath.store_data := fpiu.io.out.bits.store
io.dpath.toint_data := fpiu.io.out.bits.toint
val ifpu = Module(new IntToFP(3))
ifpu.io.in.valid := ex_reg_valid && ctrl.fromint
ifpu.io.in.bits := ctrl
ifpu.io.in.bits.rm := ex_rm
ifpu.io.in.bits.data := io.dpath.fromint_data
val fpmu = Module(new FPToFP(2))
fpmu.io.in.valid := ex_reg_valid && ctrl.fastpipe
fpmu.io.in.bits := ctrl
fpmu.io.in.bits.rm := ex_rm
fpmu.io.in.bits.in1 := ex_rs1
fpmu.io.in.bits.in2 := ex_rs2
fpmu.io.lt := fpiu.io.out.bits.lt
val cmd_fma = mem_ctrl.cmd === FCMD_MADD || mem_ctrl.cmd === FCMD_MSUB ||
mem_ctrl.cmd === FCMD_NMADD || mem_ctrl.cmd === FCMD_NMSUB
val cmd_addsub = mem_ctrl.cmd === FCMD_ADD || mem_ctrl.cmd === FCMD_SUB
val sfma = Module(new FPUSFMAPipe(sfma_latency))
sfma.io.valid := io.sfma.valid || ex_reg_valid && ctrl.fma && ctrl.single
sfma.io.in1 := Mux(io.sfma.valid, io.sfma.in1, ex_rs1)
sfma.io.in2 := Mux(io.sfma.valid, io.sfma.in2, ex_rs2)
sfma.io.in3 := Mux(io.sfma.valid, io.sfma.in3, ex_rs3)
sfma.io.cmd := Mux(io.sfma.valid, io.sfma.cmd, ctrl.cmd)
sfma.io.rm := Mux(io.sfma.valid, io.sfma.rm, ex_rm)
io.sfma.out := sfma.io.out
io.sfma.exc := sfma.io.exc
val dfma = Module(new FPUDFMAPipe(dfma_latency))
dfma.io.valid := io.dfma.valid || ex_reg_valid && ctrl.fma && !ctrl.single
dfma.io.in1 := Mux(io.dfma.valid, io.dfma.in1, ex_rs1)
dfma.io.in2 := Mux(io.dfma.valid, io.dfma.in2, ex_rs2)
dfma.io.in3 := Mux(io.dfma.valid, io.dfma.in3, ex_rs3)
dfma.io.cmd := Mux(io.dfma.valid, io.dfma.cmd, ctrl.cmd)
dfma.io.rm := Mux(io.dfma.valid, io.dfma.rm, ex_rm)
io.dfma.out := dfma.io.out
io.dfma.exc := dfma.io.exc
// writeback arbitration
case class Pipe(p: Module, lat: Int, cond: (FPUCtrlSigs) => Bool, wdata: Bits, wexc: Bits)
val pipes = List(
Pipe(fpmu, fpmu.latency, (c: FPUCtrlSigs) => c.fastpipe, fpmu.io.out.bits.data, fpmu.io.out.bits.exc),
Pipe(ifpu, ifpu.latency, (c: FPUCtrlSigs) => c.fromint, ifpu.io.out.bits.data, ifpu.io.out.bits.exc),
Pipe(sfma, sfma.latency, (c: FPUCtrlSigs) => c.fma && c.single, Cat(SInt(-1, 32), sfma.io.out), sfma.io.exc),
Pipe(dfma, dfma.latency, (c: FPUCtrlSigs) => c.fma && !c.single, dfma.io.out, dfma.io.exc))
def latencyMask(c: FPUCtrlSigs, offset: Int) = {
require(pipes.forall(_.lat >= offset))
pipes.map(p => Mux(p.cond(c), UInt(1 << p.lat-offset), UInt(0))).reduce(_|_)
}
def pipeid(c: FPUCtrlSigs) = pipes.zipWithIndex.map(p => Mux(p._1.cond(c), UInt(p._2), UInt(0))).reduce(_|_)
val maxLatency = pipes.map(_.lat).max
val memLatencyMask = latencyMask(mem_ctrl, 2)
val wen = Reg(init=Bits(0, maxLatency-1))
val winfo = Vec.fill(maxLatency-1){Reg(Bits())}
val mem_wen = mem_reg_valid && (mem_ctrl.fma || mem_ctrl.fastpipe || mem_ctrl.fromint)
val (write_port_busy, mem_winfo) = (Reg(Bool()), Reg(Bits()))
when (ex_reg_valid) {
write_port_busy := mem_wen && (memLatencyMask & latencyMask(ctrl, 1)).orR || (wen & latencyMask(ctrl, 0)).orR
mem_winfo := Cat(pipeid(ctrl), ex_reg_inst(11,7))
}
for (i <- 0 until maxLatency-2) {
when (wen(i+1)) { winfo(i) := winfo(i+1) }
}
wen := wen >> 1
when (mem_wen) {
when (!killm) {
wen := wen >> 1 | memLatencyMask
}
for (i <- 0 until maxLatency-1) {
when (!write_port_busy && memLatencyMask(i)) {
winfo(i) := mem_winfo
}
}
}
val waddr = winfo(0)(4,0).toUInt
val wsrc = winfo(0) >> waddr.getWidth
val wdata = Vec(pipes.map(_.wdata))(wsrc)
val wexc = Vec(pipes.map(_.wexc))(wsrc)
when (wen(0)) { regfile(waddr(4,0)) := wdata }
val wb_toint_valid = wb_reg_valid && wb_ctrl.toint
val wb_toint_exc = RegEnable(fpiu.io.out.bits.exc, mem_ctrl.toint)
io.dpath.fcsr_flags.valid := wb_toint_valid || wen(0)
io.dpath.fcsr_flags.bits :=
Mux(wb_toint_valid, wb_toint_exc, UInt(0)) |
Mux(wen(0), wexc, UInt(0))
val fp_inflight = wb_reg_valid && wb_ctrl.toint || wen.orR
val units_busy = mem_reg_valid && mem_ctrl.fma && Reg(next=Mux(ctrl.single, io.sfma.valid, io.dfma.valid))
io.ctrl.fcsr_rdy := !fp_inflight
io.ctrl.nack_mem := units_busy || write_port_busy
io.ctrl.dec <> fp_decoder.io.sigs
def useScoreboard(f: ((Pipe, Int)) => Bool) = pipes.zipWithIndex.filter(_._1.lat > 3).map(x => f(x)).fold(Bool(false))(_||_)
io.ctrl.sboard_set := wb_reg_valid && Reg(next=useScoreboard(_._1.cond(mem_ctrl)))
io.ctrl.sboard_clr := wen(0) && useScoreboard(x => wsrc === UInt(x._2))
io.ctrl.sboard_clra := waddr
// we don't currently support round-max-magnitude (rm=4)
io.ctrl.illegal_rm := ex_rm(2) && ctrl.round
}