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fix:FTB do not train immJump because predecode predirect corect #307

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Merged
NotTheEndOfTheWorld merged 1 commit into from
Aug 4, 2023
Merged

fix:FTB do not train immJump because predecode predirect corect #307

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11 changes: 8 additions & 3 deletions src/src/frontend/bpu/BPU.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ import frontend.bpu.bundles._
import frontend.bpu.components.Bundles.FtbEntryNdPort
import frontend.bpu.components.FTB
import frontend.bundles.{BpuFtqPort, FtqBlockBundle}
import spec.Param.BPU.BranchType
import spec._

// BPU is the Branch Predicting Unit
Expand Down Expand Up @@ -172,20 +173,24 @@ class BPU(
val ftbUpdateEntry = Wire(new FtbEntryNdPort)

// Only following conditions will trigger a FTB update:
// 1. This is a conditional branch
// 1. This is a conditional branch or the first time of direct Immediately Jump
// 2. First time a branch jumped
// 3. A FTB pollution is detected
// dirty case 1: target error || fallThroughAddr error;
// 2:At the same addr, original branch inst become nonBranch inst after cacop or change program

val ftbUpdateValid = if (Param.isFTBupdateRet) {
WireDefault(
io.bpuFtqPort.ftqTrainMeta.valid && ((directionPredictError && (!io.bpuFtqPort.ftqTrainMeta.ftbHit)) || io.bpuFtqPort.ftqTrainMeta.ftbDirty)
io.bpuFtqPort.ftqTrainMeta.valid &&
(((directionPredictError || io.bpuFtqPort.ftqTrainMeta.branchType === BranchType.call || io.bpuFtqPort.ftqTrainMeta.branchType === BranchType.uncond) && (!io.bpuFtqPort.ftqTrainMeta.ftbHit))
|| io.bpuFtqPort.ftqTrainMeta.ftbDirty)
)
// all kinds of target error can update
} else {
WireDefault(
io.bpuFtqPort.ftqTrainMeta.valid && ((directionPredictError && (!io.bpuFtqPort.ftqTrainMeta.ftbHit)) || (io.bpuFtqPort.ftqTrainMeta.ftbDirty && io.bpuFtqPort.ftqTrainMeta.ftbHit))
io.bpuFtqPort.ftqTrainMeta.valid &&
(((directionPredictError || io.bpuFtqPort.ftqTrainMeta.branchType === BranchType.call || io.bpuFtqPort.ftqTrainMeta.branchType === BranchType.uncond) && (!io.bpuFtqPort.ftqTrainMeta.ftbHit)) ||
(io.bpuFtqPort.ftqTrainMeta.ftbDirty && io.bpuFtqPort.ftqTrainMeta.ftbHit))
)
// case 1: the first time of a branch inst taken ( include conditon branch, indirect jump that hasn't been predicted taken),
// case 2: hit and dirty
Expand Down