[llvm] r256263 - [BPI] Replace weights by probabilities in BPI.
Cong Hou via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 22 15:21:32 PST 2015
Thanks for letting me know this. Could you please send me some links
showing such errors?
thanks,
Cong
On Tue, Dec 22, 2015 at 3:05 PM, Eric Christopher <echristo at gmail.com>
wrote:
> Hi Cong,
>
> Just to let you know I'm seeing some (likely) divide by zeros here. I'm
> looking into it and will either fix, or revert and get a testcase for you.
>
> -eric
>
> On Tue, Dec 22, 2015 at 10:59 AM Cong Hou via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: conghou
>> Date: Tue Dec 22 12:56:14 2015
>> New Revision: 256263
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=256263&view=rev
>> Log:
>> [BPI] Replace weights by probabilities in BPI.
>>
>> This patch removes all weight-related interfaces from BPI and replace
>> them by probability versions. With this patch, we won't use edge weight
>> anymore in either IR or MC passes. Edge probabilitiy is a better
>> representation in terms of CFG update and validation.
>>
>>
>> Differential revision: http://reviews.llvm.org/D15519
>>
>>
>>
>> Modified:
>> llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h
>> llvm/trunk/include/llvm/Support/BranchProbability.h
>> llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
>> llvm/trunk/lib/CodeGen/StackProtector.cpp
>> llvm/trunk/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
>> llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
>> llvm/trunk/test/Analysis/BranchProbabilityInfo/noreturn.ll
>> llvm/trunk/test/Transforms/JumpThreading/update-edge-weight.ll
>>
>> Modified: llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h?rev=256263&r1=256262&r2=256263&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h (original)
>> +++ llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h Tue Dec 22
>> 12:56:14 2015
>> @@ -84,36 +84,14 @@ public:
>> raw_ostream &printEdgeProbability(raw_ostream &OS, const BasicBlock
>> *Src,
>> const BasicBlock *Dst) const;
>>
>> - /// \brief Get the raw edge weight calculated for the edge.
>> + /// \brief Set the raw edge probability for the given edge.
>> ///
>> - /// This returns the raw edge weight. It is guaranteed to fall between
>> 1 and
>> - /// UINT32_MAX. Note that the raw edge weight is not meaningful in
>> isolation.
>> - /// This interface should be very carefully, and primarily by routines
>> that
>> - /// are updating the analysis by later calling setEdgeWeight.
>> - uint32_t getEdgeWeight(const BasicBlock *Src,
>> - unsigned IndexInSuccessors) const;
>> -
>> - /// \brief Get the raw edge weight calculated for the block pair.
>> - ///
>> - /// This returns the sum of all raw edge weights from Src to Dst.
>> - /// It is guaranteed to fall between 1 and UINT32_MAX.
>> - uint32_t getEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst)
>> const;
>> -
>> - uint32_t getEdgeWeight(const BasicBlock *Src,
>> - succ_const_iterator Dst) const;
>> -
>> - /// \brief Set the raw edge weight for a given edge.
>> - ///
>> - /// This allows a pass to explicitly set the edge weight for an edge.
>> It can
>> - /// be used when updating the CFG to update and preserve the branch
>> + /// This allows a pass to explicitly set the edge probability for an
>> edge. It
>> + /// can be used when updating the CFG to update and preserve the branch
>> /// probability information. Read the implementation of how these edge
>> - /// weights are calculated carefully before using!
>> - void setEdgeWeight(const BasicBlock *Src, unsigned IndexInSuccessors,
>> - uint32_t Weight);
>> -
>> - static uint32_t getBranchWeightStackProtector(bool IsLikely) {
>> - return IsLikely ? (1u << 20) - 1 : 1;
>> - }
>> + /// probabilities are calculated carefully before using!
>> + void setEdgeProbability(const BasicBlock *Src, unsigned
>> IndexInSuccessors,
>> + BranchProbability Prob);
>>
>> static BranchProbability getBranchProbStackProtector(bool IsLikely) {
>> static const BranchProbability LikelyProb((1u << 20) - 1, 1u << 20);
>> @@ -135,7 +113,7 @@ private:
>> // weight to just "inherit" the non-zero weight of an adjacent
>> successor.
>> static const uint32_t DEFAULT_WEIGHT = 16;
>>
>> - DenseMap<Edge, uint32_t> Weights;
>> + DenseMap<Edge, BranchProbability> Probs;
>>
>> /// \brief Track the last function we run over for printing.
>> Function *LastF;
>> @@ -146,9 +124,6 @@ private:
>> /// \brief Track the set of blocks that always lead to a cold call.
>> SmallPtrSet<BasicBlock *, 16> PostDominatedByColdCall;
>>
>> - /// \brief Get sum of the block successors' weights.
>> - uint32_t getSumForBlock(const BasicBlock *BB) const;
>> -
>> bool calcUnreachableHeuristics(BasicBlock *BB);
>> bool calcMetadataWeights(BasicBlock *BB);
>> bool calcColdCallHeuristics(BasicBlock *BB);
>>
>> Modified: llvm/trunk/include/llvm/Support/BranchProbability.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/BranchProbability.h?rev=256263&r1=256262&r2=256263&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/Support/BranchProbability.h (original)
>> +++ llvm/trunk/include/llvm/Support/BranchProbability.h Tue Dec 22
>> 12:56:14 2015
>> @@ -63,11 +63,6 @@ public:
>> static void normalizeProbabilities(ProbabilityIter Begin,
>> ProbabilityIter End);
>>
>> - // Normalize a list of weights by scaling them down so that the sum of
>> them
>> - // doesn't exceed UINT32_MAX.
>> - template <class WeightListIter>
>> - static void normalizeEdgeWeights(WeightListIter Begin, WeightListIter
>> End);
>> -
>> uint32_t getNumerator() const { return N; }
>> static uint32_t getDenominator() { return D; }
>>
>> @@ -219,49 +214,6 @@ void BranchProbability::normalizeProbabi
>> I->N = (I->N * uint64_t(D) + Sum / 2) / Sum;
>> }
>>
>> -template <class WeightListIter>
>> -void BranchProbability::normalizeEdgeWeights(WeightListIter Begin,
>> - WeightListIter End) {
>> - // First we compute the sum with 64-bits of precision.
>> - uint64_t Sum = std::accumulate(Begin, End, uint64_t(0));
>> -
>> - if (Sum > UINT32_MAX) {
>> - // Compute the scale necessary to cause the weights to fit, and
>> re-sum with
>> - // that scale applied.
>> - assert(Sum / UINT32_MAX < UINT32_MAX &&
>> - "The sum of weights exceeds UINT32_MAX^2!");
>> - uint32_t Scale = Sum / UINT32_MAX + 1;
>> - for (auto I = Begin; I != End; ++I)
>> - *I /= Scale;
>> - Sum = std::accumulate(Begin, End, uint64_t(0));
>> - }
>> -
>> - // Eliminate zero weights.
>> - auto ZeroWeightNum = std::count(Begin, End, 0u);
>> - if (ZeroWeightNum > 0) {
>> - // If all weights are zeros, replace them by 1.
>> - if (Sum == 0)
>> - std::fill(Begin, End, 1u);
>> - else {
>> - // We are converting zeros into ones, and here we need to make
>> sure that
>> - // after this the sum won't exceed UINT32_MAX.
>> - if (Sum + ZeroWeightNum > UINT32_MAX) {
>> - for (auto I = Begin; I != End; ++I)
>> - *I /= 2;
>> - ZeroWeightNum = std::count(Begin, End, 0u);
>> - Sum = std::accumulate(Begin, End, uint64_t(0));
>> - }
>> - // Scale up non-zero weights and turn zero weights into ones.
>> - uint64_t ScalingFactor = (UINT32_MAX - ZeroWeightNum) / Sum;
>> - assert(ScalingFactor >= 1);
>> - if (ScalingFactor > 1)
>> - for (auto I = Begin; I != End; ++I)
>> - *I *= ScalingFactor;
>> - std::replace(Begin, End, 0u, 1u);
>> - }
>> - }
>> -}
>> -
>> }
>>
>> #endif
>>
>> Modified: llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp?rev=256263&r1=256262&r2=256263&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp (original)
>> +++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp Tue Dec 22 12:56:14
>> 2015
>> @@ -108,13 +108,6 @@ static const uint32_t IH_TAKEN_WEIGHT =
>> /// instruction. This is essentially never taken.
>> static const uint32_t IH_NONTAKEN_WEIGHT = 1;
>>
>> -// Standard weight value. Used when none of the heuristics set weight for
>> -// the edge.
>> -static const uint32_t NORMAL_WEIGHT = 16;
>> -
>> -// Minimum weight of an edge. Please note, that weight is NEVER 0.
>> -static const uint32_t MIN_WEIGHT = 1;
>> -
>> /// \brief Calculate edge weights for successors lead to unreachable.
>> ///
>> /// Predict that a successor which leads necessarily to an
>> @@ -157,22 +150,24 @@ bool BranchProbabilityInfo::calcUnreacha
>> return false;
>> }
>>
>> - uint32_t UnreachableWeight =
>> - std::max(UR_TAKEN_WEIGHT / (unsigned)UnreachableEdges.size(),
>> MIN_WEIGHT);
>> - for (SmallVectorImpl<unsigned>::iterator I = UnreachableEdges.begin(),
>> - E = UnreachableEdges.end();
>> - I != E; ++I)
>> - setEdgeWeight(BB, *I, UnreachableWeight);
>> -
>> - if (ReachableEdges.empty())
>> + if (ReachableEdges.empty()) {
>> + BranchProbability Prob(1, UnreachableEdges.size());
>> + for (unsigned SuccIdx : UnreachableEdges)
>> + setEdgeProbability(BB, SuccIdx, Prob);
>> return true;
>> - uint32_t ReachableWeight =
>> - std::max(UR_NONTAKEN_WEIGHT / (unsigned)ReachableEdges.size(),
>> - NORMAL_WEIGHT);
>> - for (SmallVectorImpl<unsigned>::iterator I = ReachableEdges.begin(),
>> - E = ReachableEdges.end();
>> - I != E; ++I)
>> - setEdgeWeight(BB, *I, ReachableWeight);
>> + }
>> +
>> + BranchProbability UnreachableProb(UR_TAKEN_WEIGHT,
>> + (UR_TAKEN_WEIGHT +
>> UR_NONTAKEN_WEIGHT) *
>> + UnreachableEdges.size());
>> + BranchProbability ReachableProb(UR_NONTAKEN_WEIGHT,
>> + (UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT)
>> *
>> + ReachableEdges.size());
>> +
>> + for (unsigned SuccIdx : UnreachableEdges)
>> + setEdgeProbability(BB, SuccIdx, UnreachableProb);
>> + for (unsigned SuccIdx : ReachableEdges)
>> + setEdgeProbability(BB, SuccIdx, ReachableProb);
>>
>> return true;
>> }
>> @@ -223,10 +218,12 @@ bool BranchProbabilityInfo::calcMetadata
>>
>> WeightSum = 0;
>> for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
>> - uint32_t W = Weights[i] / ScalingFactor;
>> - WeightSum += W;
>> - setEdgeWeight(BB, i, W);
>> + Weights[i] /= ScalingFactor;
>> + WeightSum += Weights[i];
>> }
>> + for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
>> + setEdgeProbability(BB, i, {Weights[i],
>> static_cast<uint32_t>(WeightSum)});
>> +
>> assert(WeightSum <= UINT32_MAX &&
>> "Expected weights to scale down to 32 bits");
>>
>> @@ -275,21 +272,24 @@ bool BranchProbabilityInfo::calcColdCall
>> if (TI->getNumSuccessors() == 1 || ColdEdges.empty())
>> return false;
>>
>> - uint32_t ColdWeight =
>> - std::max(CC_TAKEN_WEIGHT / (unsigned) ColdEdges.size(),
>> MIN_WEIGHT);
>> - for (SmallVectorImpl<unsigned>::iterator I = ColdEdges.begin(),
>> - E = ColdEdges.end();
>> - I != E; ++I)
>> - setEdgeWeight(BB, *I, ColdWeight);
>> -
>> - if (NormalEdges.empty())
>> + if (NormalEdges.empty()) {
>> + BranchProbability Prob(1, ColdEdges.size());
>> + for (unsigned SuccIdx : ColdEdges)
>> + setEdgeProbability(BB, SuccIdx, Prob);
>> return true;
>> - uint32_t NormalWeight = std::max(
>> - CC_NONTAKEN_WEIGHT / (unsigned) NormalEdges.size(), NORMAL_WEIGHT);
>> - for (SmallVectorImpl<unsigned>::iterator I = NormalEdges.begin(),
>> - E = NormalEdges.end();
>> - I != E; ++I)
>> - setEdgeWeight(BB, *I, NormalWeight);
>> + }
>> +
>> + BranchProbability ColdProb(CC_TAKEN_WEIGHT,
>> + (CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) *
>> + ColdEdges.size());
>> + BranchProbability NormalProb(CC_NONTAKEN_WEIGHT,
>> + (CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) *
>> + NormalEdges.size());
>> +
>> + for (unsigned SuccIdx : ColdEdges)
>> + setEdgeProbability(BB, SuccIdx, ColdProb);
>> + for (unsigned SuccIdx : NormalEdges)
>> + setEdgeProbability(BB, SuccIdx, NormalProb);
>>
>> return true;
>> }
>> @@ -322,8 +322,10 @@ bool BranchProbabilityInfo::calcPointerH
>> if (!isProb)
>> std::swap(TakenIdx, NonTakenIdx);
>>
>> - setEdgeWeight(BB, TakenIdx, PH_TAKEN_WEIGHT);
>> - setEdgeWeight(BB, NonTakenIdx, PH_NONTAKEN_WEIGHT);
>> + BranchProbability TakenProb(PH_TAKEN_WEIGHT,
>> + PH_TAKEN_WEIGHT + PH_NONTAKEN_WEIGHT);
>> + setEdgeProbability(BB, TakenIdx, TakenProb);
>> + setEdgeProbability(BB, NonTakenIdx, TakenProb.getCompl());
>> return true;
>> }
>>
>> @@ -351,37 +353,35 @@ bool BranchProbabilityInfo::calcLoopBran
>> if (BackEdges.empty() && ExitingEdges.empty())
>> return false;
>>
>> + // Collect the sum of probabilities of
>> back-edges/in-edges/exiting-edges, and
>> + // normalize them so that they sum up to one.
>> + SmallVector<BranchProbability, 4> Probs(3,
>> BranchProbability::getZero());
>> + unsigned Denom = (BackEdges.empty() ? 0 : LBH_TAKEN_WEIGHT) +
>> + (InEdges.empty() ? 0 : LBH_TAKEN_WEIGHT) +
>> + (ExitingEdges.empty() ? 0 : LBH_NONTAKEN_WEIGHT);
>> + if (!BackEdges.empty())
>> + Probs[0] = BranchProbability(LBH_TAKEN_WEIGHT, Denom);
>> + if (!InEdges.empty())
>> + Probs[1] = BranchProbability(LBH_TAKEN_WEIGHT, Denom);
>> + if (!ExitingEdges.empty())
>> + Probs[2] = BranchProbability(LBH_NONTAKEN_WEIGHT, Denom);
>> +
>> if (uint32_t numBackEdges = BackEdges.size()) {
>> - uint32_t backWeight = LBH_TAKEN_WEIGHT / numBackEdges;
>> - if (backWeight < NORMAL_WEIGHT)
>> - backWeight = NORMAL_WEIGHT;
>> -
>> - for (SmallVectorImpl<unsigned>::iterator EI = BackEdges.begin(),
>> - EE = BackEdges.end(); EI != EE; ++EI) {
>> - setEdgeWeight(BB, *EI, backWeight);
>> - }
>> + auto Prob = Probs[0] / numBackEdges;
>> + for (unsigned SuccIdx : BackEdges)
>> + setEdgeProbability(BB, SuccIdx, Prob);
>> }
>>
>> if (uint32_t numInEdges = InEdges.size()) {
>> - uint32_t inWeight = LBH_TAKEN_WEIGHT / numInEdges;
>> - if (inWeight < NORMAL_WEIGHT)
>> - inWeight = NORMAL_WEIGHT;
>> -
>> - for (SmallVectorImpl<unsigned>::iterator EI = InEdges.begin(),
>> - EE = InEdges.end(); EI != EE; ++EI) {
>> - setEdgeWeight(BB, *EI, inWeight);
>> - }
>> + auto Prob = Probs[1] / numInEdges;
>> + for (unsigned SuccIdx : InEdges)
>> + setEdgeProbability(BB, SuccIdx, Prob);
>> }
>>
>> if (uint32_t numExitingEdges = ExitingEdges.size()) {
>> - uint32_t exitWeight = LBH_NONTAKEN_WEIGHT / numExitingEdges;
>> - if (exitWeight < MIN_WEIGHT)
>> - exitWeight = MIN_WEIGHT;
>> -
>> - for (SmallVectorImpl<unsigned>::iterator EI = ExitingEdges.begin(),
>> - EE = ExitingEdges.end(); EI != EE; ++EI) {
>> - setEdgeWeight(BB, *EI, exitWeight);
>> - }
>> + auto Prob = Probs[2] / numExitingEdges;
>> + for (unsigned SuccIdx : ExitingEdges)
>> + setEdgeProbability(BB, SuccIdx, Prob);
>> }
>>
>> return true;
>> @@ -463,9 +463,10 @@ bool BranchProbabilityInfo::calcZeroHeur
>> if (!isProb)
>> std::swap(TakenIdx, NonTakenIdx);
>>
>> - setEdgeWeight(BB, TakenIdx, ZH_TAKEN_WEIGHT);
>> - setEdgeWeight(BB, NonTakenIdx, ZH_NONTAKEN_WEIGHT);
>> -
>> + BranchProbability TakenProb(ZH_TAKEN_WEIGHT,
>> + ZH_TAKEN_WEIGHT + ZH_NONTAKEN_WEIGHT);
>> + setEdgeProbability(BB, TakenIdx, TakenProb);
>> + setEdgeProbability(BB, NonTakenIdx, TakenProb.getCompl());
>> return true;
>> }
>>
>> @@ -499,9 +500,10 @@ bool BranchProbabilityInfo::calcFloating
>> if (!isProb)
>> std::swap(TakenIdx, NonTakenIdx);
>>
>> - setEdgeWeight(BB, TakenIdx, FPH_TAKEN_WEIGHT);
>> - setEdgeWeight(BB, NonTakenIdx, FPH_NONTAKEN_WEIGHT);
>> -
>> + BranchProbability TakenProb(FPH_TAKEN_WEIGHT,
>> + FPH_TAKEN_WEIGHT + FPH_NONTAKEN_WEIGHT);
>> + setEdgeProbability(BB, TakenIdx, TakenProb);
>> + setEdgeProbability(BB, NonTakenIdx, TakenProb.getCompl());
>> return true;
>> }
>>
>> @@ -510,13 +512,15 @@ bool BranchProbabilityInfo::calcInvokeHe
>> if (!II)
>> return false;
>>
>> - setEdgeWeight(BB, 0/*Index for Normal*/, IH_TAKEN_WEIGHT);
>> - setEdgeWeight(BB, 1/*Index for Unwind*/, IH_NONTAKEN_WEIGHT);
>> + BranchProbability TakenProb(IH_TAKEN_WEIGHT,
>> + IH_TAKEN_WEIGHT + IH_NONTAKEN_WEIGHT);
>> + setEdgeProbability(BB, 0 /*Index for Normal*/, TakenProb);
>> + setEdgeProbability(BB, 1 /*Index for Unwind*/, TakenProb.getCompl());
>> return true;
>> }
>>
>> void BranchProbabilityInfo::releaseMemory() {
>> - Weights.clear();
>> + Probs.clear();
>> }
>>
>> void BranchProbabilityInfo::print(raw_ostream &OS) const {
>> @@ -532,20 +536,6 @@ void BranchProbabilityInfo::print(raw_os
>> }
>> }
>>
>> -uint32_t BranchProbabilityInfo::getSumForBlock(const BasicBlock *BB)
>> const {
>> - uint32_t Sum = 0;
>> -
>> - for (succ_const_iterator I = succ_begin(BB), E = succ_end(BB); I != E;
>> ++I) {
>> - uint32_t Weight = getEdgeWeight(BB, I.getSuccessorIndex());
>> - uint32_t PrevSum = Sum;
>> -
>> - Sum += Weight;
>> - assert(Sum >= PrevSum); (void) PrevSum;
>> - }
>> -
>> - return Sum;
>> -}
>> -
>> bool BranchProbabilityInfo::
>> isEdgeHot(const BasicBlock *Src, const BasicBlock *Dst) const {
>> // Hot probability is at least 4/5 = 80%
>> @@ -554,113 +544,74 @@ isEdgeHot(const BasicBlock *Src, const B
>> }
>>
>> BasicBlock *BranchProbabilityInfo::getHotSucc(BasicBlock *BB) const {
>> - uint32_t Sum = 0;
>> - uint32_t MaxWeight = 0;
>> + auto MaxProb = BranchProbability::getZero();
>> BasicBlock *MaxSucc = nullptr;
>>
>> for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
>> BasicBlock *Succ = *I;
>> - uint32_t Weight = getEdgeWeight(BB, Succ);
>> - uint32_t PrevSum = Sum;
>> -
>> - Sum += Weight;
>> - assert(Sum > PrevSum); (void) PrevSum;
>> -
>> - if (Weight > MaxWeight) {
>> - MaxWeight = Weight;
>> + auto Prob = getEdgeProbability(BB, Succ);
>> + if (Prob > MaxProb) {
>> + MaxProb = Prob;
>> MaxSucc = Succ;
>> }
>> }
>>
>> // Hot probability is at least 4/5 = 80%
>> - if (BranchProbability(MaxWeight, Sum) > BranchProbability(4, 5))
>> + if (MaxProb > BranchProbability(4, 5))
>> return MaxSucc;
>>
>> return nullptr;
>> }
>>
>> -/// Get the raw edge weight for the edge. If can't find it, return
>> -/// DEFAULT_WEIGHT value. Here an edge is specified using PredBlock and
>> an index
>> -/// to the successors.
>> -uint32_t BranchProbabilityInfo::
>> -getEdgeWeight(const BasicBlock *Src, unsigned IndexInSuccessors) const {
>> - DenseMap<Edge, uint32_t>::const_iterator I =
>> - Weights.find(std::make_pair(Src, IndexInSuccessors));
>> +/// Get the raw edge probability for the edge. If can't find it, return a
>> +/// default probability 1/N where N is the number of successors. Here an
>> edge is
>> +/// specified using PredBlock and an
>> +/// index to the successors.
>> +BranchProbability
>> +BranchProbabilityInfo::getEdgeProbability(const BasicBlock *Src,
>> + unsigned IndexInSuccessors)
>> const {
>> + auto I = Probs.find(std::make_pair(Src, IndexInSuccessors));
>>
>> - if (I != Weights.end())
>> + if (I != Probs.end())
>> return I->second;
>>
>> - return DEFAULT_WEIGHT;
>> + return {1,
>> + static_cast<uint32_t>(std::distance(succ_begin(Src),
>> succ_end(Src)))};
>> }
>>
>> -uint32_t BranchProbabilityInfo::getEdgeWeight(const BasicBlock *Src,
>> - succ_const_iterator Dst)
>> const {
>> - return getEdgeWeight(Src, Dst.getSuccessorIndex());
>> +BranchProbability
>> +BranchProbabilityInfo::getEdgeProbability(const BasicBlock *Src,
>> + succ_const_iterator Dst) const
>> {
>> + return getEdgeProbability(Src, Dst.getSuccessorIndex());
>> }
>>
>> -/// Get the raw edge weight calculated for the block pair. This returns
>> the sum
>> -/// of all raw edge weights from Src to Dst.
>> -uint32_t BranchProbabilityInfo::
>> -getEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst) const {
>> - uint32_t Weight = 0;
>> - bool FoundWeight = false;
>> - DenseMap<Edge, uint32_t>::const_iterator MapI;
>> +/// Get the raw edge probability calculated for the block pair. This
>> returns the
>> +/// sum of all raw edge probabilities from Src to Dst.
>> +BranchProbability
>> +BranchProbabilityInfo::getEdgeProbability(const BasicBlock *Src,
>> + const BasicBlock *Dst) const {
>> + auto Prob = BranchProbability::getZero();
>> + bool FoundProb = false;
>> for (succ_const_iterator I = succ_begin(Src), E = succ_end(Src); I !=
>> E; ++I)
>> if (*I == Dst) {
>> - MapI = Weights.find(std::make_pair(Src, I.getSuccessorIndex()));
>> - if (MapI != Weights.end()) {
>> - FoundWeight = true;
>> - Weight += MapI->second;
>> + auto MapI = Probs.find(std::make_pair(Src, I.getSuccessorIndex()));
>> + if (MapI != Probs.end()) {
>> + FoundProb = true;
>> + Prob += MapI->second;
>> }
>> }
>> - return (!FoundWeight) ? DEFAULT_WEIGHT : Weight;
>> -}
>> -
>> -/// Set the edge weight for a given edge specified by PredBlock and an
>> index
>> -/// to the successors.
>> -void BranchProbabilityInfo::
>> -setEdgeWeight(const BasicBlock *Src, unsigned IndexInSuccessors,
>> - uint32_t Weight) {
>> - Weights[std::make_pair(Src, IndexInSuccessors)] = Weight;
>> - DEBUG(dbgs() << "set edge " << Src->getName() << " -> "
>> - << IndexInSuccessors << " successor weight to "
>> - << Weight << "\n");
>> + uint32_t succ_num = std::distance(succ_begin(Src), succ_end(Src));
>> + return FoundProb ? Prob : BranchProbability(1, succ_num);
>> }
>>
>> -/// Get an edge's probability, relative to other out-edges from Src.
>> -BranchProbability BranchProbabilityInfo::
>> -getEdgeProbability(const BasicBlock *Src, unsigned IndexInSuccessors)
>> const {
>> - uint32_t N = getEdgeWeight(Src, IndexInSuccessors);
>> - uint32_t D = getSumForBlock(Src);
>> -
>> - // It is possible that the edge weight on the only successor edge of
>> Src is
>> - // zero, in which case we return 100%.
>> - if (N == 0 && D == 0)
>> - return BranchProbability::getOne();
>> -
>> - return BranchProbability(N, D);
>> -}
>> -
>> -/// Get the probability of going from Src to Dst. It returns the sum of
>> all
>> -/// probabilities for edges from Src to Dst.
>> -BranchProbability BranchProbabilityInfo::
>> -getEdgeProbability(const BasicBlock *Src, const BasicBlock *Dst) const {
>> -
>> - uint32_t N = getEdgeWeight(Src, Dst);
>> - uint32_t D = getSumForBlock(Src);
>> -
>> - // It is possible that the edge weight on the only successor edge of
>> Src is
>> - // zero, in which case we return 100%.
>> - if (N == 0 && D == 0)
>> - return BranchProbability::getOne();
>> -
>> - return BranchProbability(N, D);
>> -}
>> -
>> -BranchProbability
>> -BranchProbabilityInfo::getEdgeProbability(const BasicBlock *Src,
>> - succ_const_iterator Dst) const
>> {
>> - return getEdgeProbability(Src, Dst.getSuccessorIndex());
>> +/// Set the edge probability for a given edge specified by PredBlock and
>> an
>> +/// index to the successors.
>> +void BranchProbabilityInfo::setEdgeProbability(const BasicBlock *Src,
>> + unsigned
>> IndexInSuccessors,
>> + BranchProbability Prob) {
>> + Probs[std::make_pair(Src, IndexInSuccessors)] = Prob;
>> + DEBUG(dbgs() << "set edge " << Src->getName() << " -> " <<
>> IndexInSuccessors
>> + << " successor probability to " << Prob << "\n");
>> }
>>
>> raw_ostream &
>>
>> Modified: llvm/trunk/lib/CodeGen/StackProtector.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StackProtector.cpp?rev=256263&r1=256262&r2=256263&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/StackProtector.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/StackProtector.cpp Tue Dec 22 12:56:14 2015
>> @@ -453,12 +453,13 @@ bool StackProtector::InsertStackProtecto
>> LoadInst *LI1 = B.CreateLoad(StackGuardVar);
>> LoadInst *LI2 = B.CreateLoad(AI);
>> Value *Cmp = B.CreateICmpEQ(LI1, LI2);
>> - unsigned SuccessWeight =
>> - BranchProbabilityInfo::getBranchWeightStackProtector(true);
>> - unsigned FailureWeight =
>> - BranchProbabilityInfo::getBranchWeightStackProtector(false);
>> + auto SuccessProb =
>> + BranchProbabilityInfo::getBranchProbStackProtector(true);
>> + auto FailureProb =
>> + BranchProbabilityInfo::getBranchProbStackProtector(false);
>> MDNode *Weights = MDBuilder(F->getContext())
>> - .createBranchWeights(SuccessWeight,
>> FailureWeight);
>> +
>> .createBranchWeights(SuccessProb.getNumerator(),
>> +
>> FailureProb.getNumerator());
>> B.CreateCondBr(Cmp, NewBB, FailBB, Weights);
>> }
>> }
>>
>> Modified: llvm/trunk/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCISelDAGToDAG.cpp?rev=256263&r1=256262&r2=256263&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/PowerPC/PPCISelDAGToDAG.cpp (original)
>> +++ llvm/trunk/lib/Target/PowerPC/PPCISelDAGToDAG.cpp Tue Dec 22 12:56:14
>> 2015
>> @@ -414,8 +414,8 @@ static unsigned getBranchHint(unsigned P
>> const BasicBlock *TBB = BBTerm->getSuccessor(0);
>> const BasicBlock *FBB = BBTerm->getSuccessor(1);
>>
>> - uint32_t TWeight = FuncInfo->BPI->getEdgeWeight(BB, TBB);
>> - uint32_t FWeight = FuncInfo->BPI->getEdgeWeight(BB, FBB);
>> + auto TProb = FuncInfo->BPI->getEdgeProbability(BB, TBB);
>> + auto FProb = FuncInfo->BPI->getEdgeProbability(BB, FBB);
>>
>> // We only want to handle cases which are easy to predict at static
>> time, e.g.
>> // C++ throw statement, that is very likely not taken, or calling never
>> @@ -432,24 +432,22 @@ static unsigned getBranchHint(unsigned P
>> // 5. PH/ZH/FPH 20:12
>> const uint32_t Threshold = 10000;
>>
>> - // Minimal weight should be at least 1
>> - if (std::max(TWeight, FWeight) /
>> - std::max(1u, std::min(TWeight, FWeight)) < Threshold)
>> + if (std::max(TProb, FProb) / Threshold < std::min(TProb, FProb))
>> return PPC::BR_NO_HINT;
>>
>> DEBUG(dbgs() << "Use branch hint for '" << FuncInfo->Fn->getName() <<
>> "::"
>> << BB->getName() << "'\n"
>> - << " -> " << TBB->getName() << ": " << TWeight << "\n"
>> - << " -> " << FBB->getName() << ": " << FWeight << "\n");
>> + << " -> " << TBB->getName() << ": " << TProb << "\n"
>> + << " -> " << FBB->getName() << ": " << FProb << "\n");
>>
>> const BasicBlockSDNode *BBDN = cast<BasicBlockSDNode>(DestMBB);
>>
>> - // If Dest BasicBlock is False-BasicBlock (FBB), swap branch weight,
>> - // because we want 'TWeight' stands for 'branch weight' to Dest
>> BasicBlock
>> + // If Dest BasicBlock is False-BasicBlock (FBB), swap branch
>> probabilities,
>> + // because we want 'TProb' stands for 'branch probability' to Dest
>> BasicBlock
>> if (BBDN->getBasicBlock()->getBasicBlock() != TBB)
>> - std::swap(TWeight, FWeight);
>> + std::swap(TProb, FProb);
>>
>> - return (TWeight > FWeight) ? PPC::BR_TAKEN_HINT :
>> PPC::BR_NONTAKEN_HINT;
>> + return (TProb > FProb) ? PPC::BR_TAKEN_HINT : PPC::BR_NONTAKEN_HINT;
>> }
>>
>> // isOpcWithIntImmediate - This method tests to see if the node is a
>> specific
>>
>> Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=256263&r1=256262&r2=256263&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Tue Dec 22
>> 12:56:14 2015
>> @@ -1636,7 +1636,7 @@ void JumpThreading::UpdateBlockFreqAndEd
>> BFI->setBlockFreq(BB, BBNewFreq.getFrequency());
>>
>> // Collect updated outgoing edges' frequencies from BB and use them to
>> update
>> - // edge weights.
>> + // edge probabilities.
>> SmallVector<uint64_t, 4> BBSuccFreq;
>> for (auto I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
>> auto SuccFreq = (*I == SuccBB)
>> @@ -1645,18 +1645,26 @@ void JumpThreading::UpdateBlockFreqAndEd
>> BBSuccFreq.push_back(SuccFreq.getFrequency());
>> }
>>
>> - // Normalize edge weights in Weights64 so that the sum of them can fit
>> in
>> - BranchProbability::normalizeEdgeWeights(BBSuccFreq.begin(),
>> BBSuccFreq.end());
>> + uint64_t MaxBBSuccFreq =
>> + *std::max_element(BBSuccFreq.begin(), BBSuccFreq.end());
>> + SmallVector<BranchProbability, 4> BBSuccProbs;
>> + for (uint64_t Freq : BBSuccFreq)
>> + BBSuccProbs.push_back(
>> + BranchProbability::getBranchProbability(Freq, MaxBBSuccFreq));
>>
>> - SmallVector<uint32_t, 4> Weights;
>> - for (auto Freq : BBSuccFreq)
>> - Weights.push_back(static_cast<uint32_t>(Freq));
>> -
>> - // Update edge weights in BPI.
>> - for (int I = 0, E = Weights.size(); I < E; I++)
>> - BPI->setEdgeWeight(BB, I, Weights[I]);
>> + // Normalize edge probabilities so that they sum up to one.
>> + BranchProbability::normalizeProbabilities(BBSuccProbs.begin(),
>> + BBSuccProbs.end());
>> +
>> + // Update edge probabilities in BPI.
>> + for (int I = 0, E = BBSuccProbs.size(); I < E; I++)
>> + BPI->setEdgeProbability(BB, I, BBSuccProbs[I]);
>> +
>> + if (BBSuccProbs.size() >= 2) {
>> + SmallVector<uint32_t, 4> Weights;
>> + for (auto Prob : BBSuccProbs)
>> + Weights.push_back(Prob.getNumerator());
>>
>> - if (Weights.size() >= 2) {
>> auto TI = BB->getTerminator();
>> TI->setMetadata(
>> LLVMContext::MD_prof,
>>
>> Modified: llvm/trunk/test/Analysis/BranchProbabilityInfo/noreturn.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/BranchProbabilityInfo/noreturn.ll?rev=256263&r1=256262&r2=256263&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Analysis/BranchProbabilityInfo/noreturn.ll (original)
>> +++ llvm/trunk/test/Analysis/BranchProbabilityInfo/noreturn.ll Tue Dec 22
>> 12:56:14 2015
>> @@ -26,11 +26,11 @@ entry:
>> i32 2, label %case_b
>> i32 3, label %case_c
>> i32 4, label %case_d]
>> -; CHECK: edge entry -> exit probability is 0x7fffe000 / 0x80000000 =
>> 100.00% [HOT edge]
>> -; CHECK: edge entry -> case_a probability is 0x00000800 / 0x80000000 =
>> 0.00%
>> -; CHECK: edge entry -> case_b probability is 0x00000800 / 0x80000000 =
>> 0.00%
>> -; CHECK: edge entry -> case_c probability is 0x00000800 / 0x80000000 =
>> 0.00%
>> -; CHECK: edge entry -> case_d probability is 0x00000800 / 0x80000000 =
>> 0.00%
>> +; CHECK: edge entry -> exit probability is 0x7ffff800 / 0x80000000 =
>> 100.00% [HOT edge]
>> +; CHECK: edge entry -> case_a probability is 0x00000200 / 0x80000000 =
>> 0.00%
>> +; CHECK: edge entry -> case_b probability is 0x00000200 / 0x80000000 =
>> 0.00%
>> +; CHECK: edge entry -> case_c probability is 0x00000200 / 0x80000000 =
>> 0.00%
>> +; CHECK: edge entry -> case_d probability is 0x00000200 / 0x80000000 =
>> 0.00%
>>
>> case_a:
>> br label %case_b
>>
>> Modified: llvm/trunk/test/Transforms/JumpThreading/update-edge-weight.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/JumpThreading/update-edge-weight.ll?rev=256263&r1=256262&r2=256263&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/JumpThreading/update-edge-weight.ll
>> (original)
>> +++ llvm/trunk/test/Transforms/JumpThreading/update-edge-weight.ll Tue
>> Dec 22 12:56:14 2015
>> @@ -2,7 +2,7 @@
>>
>> ; Test if edge weights are properly updated after jump threading.
>>
>> -; CHECK: !2 = !{!"branch_weights", i32 22, i32 7}
>> +; CHECK: !2 = !{!"branch_weights", i32 1629125526, i32 518358122}
>>
>> define void @foo(i32 %n) !prof !0 {
>> entry:
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>
>
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