Add support for no-dFMA units

ucb-bar · Mar 14, 2021 · e7919df · e7919df
1 parent 62c01f5
commit e7919df
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Showing 4 changed files with 29 additions and 15 deletions.
diff --git a/src/main/scala/TopLevelConfigs.scala b/src/main/scala/TopLevelConfigs.scala
@@ -37,6 +37,10 @@ class WithSmallPredRF extends Config((site, here, up) => {
     case HwachaNPredRFEntries => 128
 })
 
+class WithNoDFMA extends Config((site, here, up) => {
+    case HwachaBuildDFMA => false
+})
+
 class ISCA2016Config extends Config(
   new Process28nmConfig ++
   new WithNBanks(4) ++

diff --git a/src/main/scala/configs.scala b/src/main/scala/configs.scala
@@ -65,6 +65,7 @@ class DefaultHwachaConfig extends Config((site, here, up) => {
     case HwachaStagesHFMA => 3
     case HwachaStagesFConv => 2
     case HwachaStagesFCmp => 1
+    case HwachaBuildDFMA => true
 
     case HwachaNSeqEntries => 8
 

diff --git a/src/main/scala/lane.scala b/src/main/scala/lane.scala
@@ -21,6 +21,7 @@ case object HwachaStagesSFMA extends Field[Int]
 case object HwachaStagesHFMA extends Field[Int]
 case object HwachaStagesFConv extends Field[Int]
 case object HwachaStagesFCmp extends Field[Int]
+case object HwachaBuildDFMA extends Field[Boolean]
 
 abstract trait LaneParameters extends UsesHwachaParameters {
   val nSRAM = p(HwachaNSRAMRFEntries)

diff --git a/src/main/scala/vfu-fma.scala b/src/main/scala/vfu-fma.scala
@@ -56,25 +56,33 @@ class FMASlice(implicit p: Parameters) extends VXUModule()(p) with Packing {
       fn.op_is(FM_MUL) -> Bits(0, SZ_D)
     ))
 
+  val buildDFMA = p(HwachaBuildDFMA)
+  val buildSFMA = true
+  val buildHFMA = true
   val results =
-    List((stagesDFMA, SZ_D, FPD, recode_dp _, unpack_d _, ieee_dp _, repack_d _, expand_float_d _, (11, 53)),
-         (stagesSFMA, SZ_W, FPS, recode_sp _, unpack_w _, ieee_sp _, repack_w _, expand_float_s _, (8, 24)),
-         (stagesHFMA, SZ_H, FPH, recode_hp _, unpack_h _, ieee_hp _, repack_h _, expand_float_h _, (5, 11))) map {
-      case (stages, sz, fp, recode, unpack, ieee, repack, expand, (exp, sig)) => {
+    List((buildDFMA, stagesDFMA, SZ_D, FPD, recode_dp _, unpack_d _, ieee_dp _, repack_d _, expand_float_d _, (11, 53)),
+         (buildSFMA, stagesSFMA, SZ_W, FPS, recode_sp _, unpack_w _, ieee_sp _, repack_w _, expand_float_s _, (8, 24)),
+         (buildHFMA, stagesHFMA, SZ_H, FPH, recode_hp _, unpack_h _, ieee_hp _, repack_h _, expand_float_h _, (5, 11))) map {
+      case (build, stages, sz, fp, recode, unpack, ieee, repack, expand, (exp, sig)) => {
         val n = SZ_D / sz
         val val_fp = fn.fp_is(fp)
         val results = for (i <- (0 until n) if (confprec || i == 0)) yield {
-          val fma = Module(new freechips.rocketchip.tile.MulAddRecFNPipe(stages min 2, exp, sig))
-          fma.suggestName("fmaInst")
-          val valid = pred(i) && val_fp
-          fma.io.validin := valid
-          fma.io.op := dgate(valid, fma_op)
-          fma.io.a := recode(dgate(valid, unpack(fma_multiplicand, i)))
-          fma.io.b := recode(dgate(valid, unpack(fma_multiplier, i)))
-          fma.io.c := recode(dgate(valid, unpack(fma_addend, i)))
-          fma.io.roundingMode := dgate(valid, fn.rm)
-          val out = Pipe(fma.io.validout, ieee(fma.io.out), (stages - 2) max 0).bits
-          val exc = Pipe(fma.io.validout, fma.io.exceptionFlags, (stages - 2) max 0).bits
+          val (out, exc) = if (build) {
+            val fma = Module(new freechips.rocketchip.tile.MulAddRecFNPipe(stages min 2, exp, sig))
+            fma.suggestName("fmaInst")
+            val valid = pred(i) && val_fp
+              fma.io.validin := valid
+            fma.io.op := dgate(valid, fma_op)
+            fma.io.a := recode(dgate(valid, unpack(fma_multiplicand, i)))
+            fma.io.b := recode(dgate(valid, unpack(fma_multiplier, i)))
+            fma.io.c := recode(dgate(valid, unpack(fma_addend, i)))
+            fma.io.roundingMode := dgate(valid, fn.rm)
+            val out = Pipe(fma.io.validout, ieee(fma.io.out), (stages - 2) max 0).bits
+            val exc = Pipe(fma.io.validout, fma.io.exceptionFlags, (stages - 2) max 0).bits
+            (out, exc)
+          } else {
+            (0.U, 0.U)
+          }
           (out, exc)
         }
         val valid = active && val_fp