[llvm] r256263 - [BPI] Replace weights by probabilities in BPI.
Cong Hou via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 22 10:56:15 PST 2015
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:
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