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fpu moved overflow rounding to writeback

This commit is contained in:
Dolu1990 2021-01-29 14:37:52 +01:00
parent fc3e6a6d0a
commit 3c4df1e963
2 changed files with 84 additions and 28 deletions
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34
src/main/scala/vexriscv/ip/fpu/FpuCore.scala
View File

@ -624,7 +624,7 @@ case class FpuCore( portCount : Int, p : FpuParameter) extends Component{
// val exp = math.exp + U(needShift)
// val man = needShift ? math.mulC(p.internalMantissaSize + 1, p.internalMantissaSize bits) | math.mulC(p.internalMantissaSize, p.internalMantissaSize bits)
val mulRounded = (math.mulC >> p.internalMantissaSize) + math.mulC(p.internalMantissaSize-1).asUInt
val mulRounded = (math.mulC >> p.internalMantissaSize)
val needShift = mulRounded.msb
val exp = math.exp + U(needShift)
val man = needShift ? mulRounded(1, p.internalMantissaSize bits) | mulRounded(0, p.internalMantissaSize bits)
@ -903,7 +903,6 @@ case class FpuCore( portCount : Int, p : FpuParameter) extends Component{
def xySign = shifter.xySign
val xSigned = xMantissa.twoComplement(xSign) //TODO Is that necessary ?
val overshot = (ySign && shifter.roundingScrap)
val ySigned = ((ySign ## Mux(ySign, ~yMantissa, yMantissa)).asUInt + (ySign && !shifter.roundingScrap).asUInt).asSInt //rounding here
val xyMantissa = U(xSigned +^ ySigned).trim(1 bits)
}
@ -916,11 +915,9 @@ case class FpuCore( portCount : Int, p : FpuParameter) extends Component{
val shiftOh = OHMasking.first(xyMantissa.asBools.reverse)
val shift = OHToUInt(shiftOh)
val mantissa = (xyMantissa |<< shift)
// val mantissa = ((shifter.roundingScrap.asUInt @@ xyMantissa.reversed) |>> shift).reversed >> 1
val exponent = xyExponent -^ shift + 1
xySign clearWhen(input.rs1.isZero && input.rs2.isZero)
val forceZero = xyMantissa === 0 || exponent.msb || (input.rs1.isZero && input.rs2.isZero)
val forceOverflow = exponent === exponentOne + 128
val forceZero = xyMantissa === 0 || (input.rs1.isZero && input.rs2.isZero)
// val forceOverflow = exponent === exponentOne + 128 //Handled by writeback rounding
val forceInfinity = (input.rs1.isInfinity || input.rs2.isInfinity)
val forceNan = input.rs1.isNan || input.rs2.isNan || (input.rs1.isInfinity && input.rs2.isInfinity && (input.rs1.sign ^ input.rs2.sign))
}
@ -949,13 +946,13 @@ case class FpuCore( portCount : Int, p : FpuParameter) extends Component{
}
} elsewhen(norm.forceInfinity) {
output.value.setInfinity
} elsewhen(norm.forceOverflow) {
} /*elsewhen(norm.forceOverflow) {
val doMax = input.roundMode.mux(
FpuRoundMode.RNE -> (True),
FpuRoundMode.RNE -> (False),
FpuRoundMode.RTZ -> (True),
FpuRoundMode.RDN -> (!output.value.sign),
FpuRoundMode.RUP -> (output.value.sign),
FpuRoundMode.RMM -> (True)
FpuRoundMode.RMM -> (False)
)
when(doMax){
output.value.exponent := exponentOne + 127
@ -963,7 +960,7 @@ case class FpuCore( portCount : Int, p : FpuParameter) extends Component{
} otherwise {
output.value.setInfinity
}
}
}*/
}
@ -992,9 +989,24 @@ case class FpuCore( portCount : Int, p : FpuParameter) extends Component{
math.mantissa := adder(0, p.internalMantissaSize bits)
val patched = CombInit(math)
when(!input.value.special && math.exponent === exponentOne + 128){
when(!math.special && math.exponent >= exponentOne + 128){
// patched.setInfinity
val doMax = input.roundMode.mux(
FpuRoundMode.RNE -> (False),
FpuRoundMode.RTZ -> (True),
FpuRoundMode.RDN -> (!math.sign),
FpuRoundMode.RUP -> (math.sign),
FpuRoundMode.RMM -> (False)
)
when(doMax){
patched.exponent := exponentOne + 127
patched.mantissa.setAll()
} otherwise {
patched.setInfinity
}
}
val output = input.swapPayload(RoundOutput())
output.source := input.source

76
src/test/scala/vexriscv/ip/fpu/FpuTest.scala
View File

@ -69,6 +69,7 @@ class FpuTest extends FunSuite{
val f32 = new {
val add = new TestCase("f32", "add")
val mul = new TestCase("f32", "mul")
}
val cpus = for(id <- 0 until portCount) yield new {
@ -137,7 +138,7 @@ class FpuTest extends FunSuite{
storeRaw(rs){rsp => body(b2f(rsp.value.toLong.toInt))}
}
def mul(rd : Int, rs1 : Int, rs2 : Int): Unit ={
def mul(rd : Int, rs1 : Int, rs2 : Int, rounding : FpuRoundMode.E = FpuRoundMode.RNE): Unit ={
cmdQueue += {cmd =>
cmd.opcode #= cmd.opcode.spinalEnum.MUL
cmd.rs1 #= rs1
@ -145,6 +146,7 @@ class FpuTest extends FunSuite{
cmd.rs3.randomize()
cmd.rd #= rd
cmd.arg #= 0
cmd.roundMode #= rounding
}
commitQueue += {cmd =>
cmd.write #= true
@ -388,6 +390,19 @@ class FpuTest extends FunSuite{
}
}
def testMulExact(a : Float, b : Float, ref : Float, flag : Int, rounding : FpuRoundMode.E): Unit ={
val rs = new RegAllocator()
val rs1, rs2, rs3 = rs.allocate()
val rd = Random.nextInt(32)
load(rs1, a)
load(rs2, b)
mul(rd,rs1,rs2, rounding)
storeFloat(rd){v =>
assert(f2b(v) == f2b(ref), f"## ${a} * $b = $v, $ref $rounding")
}
}
def testLoadStore(a : Float): Unit ={
val rd = Random.nextInt(32)
load(rd, a)
@ -418,6 +433,7 @@ class FpuTest extends FunSuite{
}
def testFma(a : Float, b : Float, c : Float): Unit ={
val rs = new RegAllocator()
val rs1, rs2, rs3 = rs.allocate()
@ -609,19 +625,34 @@ class FpuTest extends FunSuite{
// for(_ <- 0 until 1000000){
// val rounding = FpuRoundMode.RTZ
// val (a,b,c,f) = f32.mul(rounding).f32_2
// if(a > 0 && b > 0 && !c.isInfinity) testMulExact(a,b,c,f, rounding)
// }
// roundingModes.foreach(rounding => println(Clib.math.addF32(0.0f, 0.0f, rounding.position)))
// roundingModes.foreach(rounding => println(Clib.math.addF32(1.0f,-1.0f, rounding.position)))
println()
println(Clib.math.addF32(8.0f, b2f(0xBf800000), 0))
println(Clib.math.addF32(8.0f, b2f(0xBf800001), 0))
println(Clib.math.addF32(8.0f, b2f(0xBf800002), 0))
println(Clib.math.addF32(8.0f, b2f(0xBf800003), 0))
println(Clib.math.addF32(8.0f, b2f(0xBf800004), 0))
println(Clib.math.addF32(8.0f, b2f(0xBf800005), 0))
println(Clib.math.addF32(8.0f, b2f(0xBf800006), 0))
println(Clib.math.addF32(8.0f, b2f(0xBf800007), 0))
println(Clib.math.addF32(8.0f, b2f(0xBf800008), 0))
println("Mul done")
for(i <- 0 until 20) println(Clib.math.addF32(b2f(0x7f000000), b2f(0x7f000000-10+i), 0))
// simSuccess()
foreachRounding(r => println(Clib.math.addF32(b2f(0x7f7fffff), b2f(0x7f7fffff),r.position)))
println("")
foreachRounding(r => println(Clib.math.addF32(2.5787021E38f, 3.4027196E38f,r.position)))
println("")
// println(Clib.math.addF32(8.0f, b2f(0xBf800000), 0))
// println(Clib.math.addF32(8.0f, b2f(0xBf800001), 0))
// println(Clib.math.addF32(8.0f, b2f(0xBf800002), 0))
// println(Clib.math.addF32(8.0f, b2f(0xBf800003), 0))
// println(Clib.math.addF32(8.0f, b2f(0xBf800004), 0))
// println(Clib.math.addF32(8.0f, b2f(0xBf800005), 0))
// println(Clib.math.addF32(8.0f, b2f(0xBf800006), 0))
// println(Clib.math.addF32(8.0f, b2f(0xBf800007), 0))
// println(Clib.math.addF32(8.0f, b2f(0xBf800008), 0))
testAdd(-5.3687091E8f, 16.249022f, FpuRoundMode.RNE)
testAdd(-5.3687091E8f, 16.0f, FpuRoundMode.RNE)
@ -645,7 +676,13 @@ class FpuTest extends FunSuite{
for(_ <- 0 until 1000000){
val rounding = FpuRoundMode.elements.randomPick()
val (a,b,c,f) = f32.add(rounding).f32_2
if(/*a > 0 && b < 0 && */!c.isInfinity) testAddExact(a,b,c,f, rounding)
// if(a.isNaN) println("Nan")
// if(b.isNaN) println("Nan")
// if(a.isInfinity) println("Inf")
// if(b.isInfinity) println("Inf")
// if(a == 0f) println("Zero")
// if(b == 0f) println("Zero")
/*if(/*a > 0 && b < 0 && */!c.isInfinity) */testAddExact(a,b,c,f, rounding)
}
waitUntil(cmdQueue.isEmpty)
@ -924,10 +961,17 @@ object Clib {
object FpuCompileSo extends App{
println(Clib.math.addF32(1.00000011921f, 4.0f, FpuRoundMode.RNE.position))
println(Clib.math.addF32(1.00000011921f, 4.0f, FpuRoundMode.RTZ.position))
println(Clib.math.addF32(1.00000011921f, 4.0f, FpuRoundMode.RDN.position))
println(Clib.math.addF32(1.00000011921f, 4.0f, FpuRoundMode.RUP.position))
val b2f = lang.Float.intBitsToFloat(_)
for(e <- FpuRoundMode.elements) {
println(e)
for (i <- -2 until 50) println(i + " => " + Clib.math.addF32(b2f(0x7f000000), b2f(0x7f000000 + i), e.position))
println("")
}
// println(Clib.math.addF32(1.00000011921f, 4.0f, FpuRoundMode.RNE.position))
// println(Clib.math.addF32(1.00000011921f, 4.0f, FpuRoundMode.RTZ.position))
// println(Clib.math.addF32(1.00000011921f, 4.0f, FpuRoundMode.RDN.position))
// println(Clib.math.addF32(1.00000011921f, 4.0f, FpuRoundMode.RUP.position))
}
class ProcessStream(cmd : String){