[llvm] r256263 - [BPI] Replace weights by probabilities in BPI.
Cong Hou via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 22 15:27:46 PST 2015
Thanks! After reviewing my patch, I think I have found the places where
divide-by-zero may happen. I am working on the fix now. I will test it on
your testcase.
thanks,
Cong
On Tue, Dec 22, 2015 at 3:23 PM, Eric Christopher <echristo at gmail.com>
wrote:
> 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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