[llvm] r256263 - [BPI] Replace weights by probabilities in BPI.
Eric Christopher via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 22 15:05:06 PST 2015
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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