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tilelink2 AddressDecoder: improved heuristic

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This commit is contained in:
Wesley W. Terpstra 2016-09-16 00:27:26 -07:00
parent 4abba87b61
commit 023a54f122
1 changed files with 10 additions and 8 deletions
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18
src/main/scala/uncore/tilelink2/AddressDecoder.scala
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@ -25,13 +25,14 @@ object AddressDecoder
// Verify the user did not give us an impossible problem // Verify the user did not give us an impossible problem
ports.combinations(2).foreach { case Seq(x, y) => ports.combinations(2).foreach { case Seq(x, y) =>
x.foreach { a => y.foreach { b => x.foreach { a => y.foreach { b =>
require (!a.overlaps(b)) // it must be possible to disambiguate addresses! require (!a.overlaps(b)) // it must be possible to disambiguate ports!
} } } }
} }
val maxBits = log2Ceil(ports.map(_.map(_.max).max).max + 1) val maxBits = log2Ceil(ports.map(_.map(_.max).max).max + 1)
val bits = (0 until maxBits).map(BigInt(1) << _).toSeq val bits = (0 until maxBits).map(BigInt(1) << _).toSeq
val selected = recurse(Seq(ports.map(_.sorted).sorted(portOrder)), bits) val selected = recurse(Seq(ports.map(_.sorted).sorted(portOrder)), bits)
selected.reduceLeft(_ | _) selected.reduceLeft(_ | _)
// port validation via mask expansion
} }
// A simpler version that works for a Seq[Int] // A simpler version that works for a Seq[Int]
@ -51,11 +52,12 @@ object AddressDecoder
// pick the bit which minimizes the number of ports in each partition // pick the bit which minimizes the number of ports in each partition
// as a secondary goal, reduce the number of AddressSets within a partition // as a secondary goal, reduce the number of AddressSets within a partition
val bigValue = 100000 def bitScore(partitions: Partitions): Seq[Int] = {
def bitScore(partitions: Partitions): Int = {
val maxPortsPerPartition = partitions.map(_.size).max val maxPortsPerPartition = partitions.map(_.size).max
val sumPortsPerPartition = partitions.map(_.size).sum
val maxSetsPerPartition = partitions.map(_.map(_.size).sum).max val maxSetsPerPartition = partitions.map(_.map(_.size).sum).max
maxPortsPerPartition * bigValue + maxSetsPerPartition val sumSetsPerPartition = partitions.map(_.map(_.size).sum).sum
Seq(maxPortsPerPartition, sumPortsPerPartition, maxSetsPerPartition, sumSetsPerPartition)
} }
def partitionPort(port: Port, bit: BigInt): (Port, Port) = { def partitionPort(port: Port, bit: BigInt): (Port, Port) = {
@ -77,8 +79,8 @@ object AddressDecoder
def partitionPartitions(partitions: Partitions, bit: BigInt): Partitions = { def partitionPartitions(partitions: Partitions, bit: BigInt): Partitions = {
val partitioned_partitions = partitions.map(p => partitionPorts(p, bit)) val partitioned_partitions = partitions.map(p => partitionPorts(p, bit))
val case_a_partitions = partitioned_partitions.map(_._1) val case_a_partitions = partitioned_partitions.map(_._1).filter(!_.isEmpty)
val case_b_partitions = partitioned_partitions.map(_._2) val case_b_partitions = partitioned_partitions.map(_._2).filter(!_.isEmpty)
val new_partitions = (case_a_partitions ++ case_b_partitions).sorted(partitionOrder) val new_partitions = (case_a_partitions ++ case_b_partitions).sorted(partitionOrder)
// Prevent combinational memory explosion; if two partitions are equal, keep only one // Prevent combinational memory explosion; if two partitions are equal, keep only one
// Note: AddressSets in a port are sorted, and ports in a partition are sorted. // Note: AddressSets in a port are sorted, and ports in a partition are sorted.
@ -106,9 +108,9 @@ object AddressDecoder
val score = bitScore(result) val score = bitScore(result)
(score, bit, result) (score, bit, result)
} }
val (bestScore, bestBit, bestPartitions) = candidates.min(Ordering.by[(Int, BigInt, Partitions), Int](_._1)) val (bestScore, bestBit, bestPartitions) = candidates.min(Ordering.by[(Seq[Int], BigInt, Partitions), Iterable[Int]](_._1.toIterable))
if (debug) println("=> Selected bit 0x%x".format(bestBit)) if (debug) println("=> Selected bit 0x%x".format(bestBit))
if (bestScore < 2*bigValue) { if (bestScore(0) <= 1) {
if (debug) println("---") if (debug) println("---")
Seq(bestBit) Seq(bestBit)
} else { } else {