[llvm] r256263 - [BPI] Replace weights by probabilities in BPI.
Eric Christopher via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 22 15:23:39 PST 2015
Working on a public testcase :)
I've sent you some other links though.
-eric
On Tue, Dec 22, 2015 at 3:21 PM Cong Hou <congh at google.com> wrote:
> 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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