[llvm] 2f1038c - [BranchProbabilityInfo] Use SmallVector (NFC)
Kazu Hirata via llvm-commits
llvm-commits at lists.llvm.org
Mon Nov 9 17:30:09 PST 2020
Author: Kazu Hirata
Date: 2020-11-09T17:29:40-08:00
New Revision: 2f1038c7b699e959e0521638e2e2818a849fe19c
URL: https://github.com/llvm/llvm-project/commit/2f1038c7b699e959e0521638e2e2818a849fe19c
DIFF: https://github.com/llvm/llvm-project/commit/2f1038c7b699e959e0521638e2e2818a849fe19c.diff
LOG: [BranchProbabilityInfo] Use SmallVector (NFC)
This patch simplifies BranchProbabilityInfo by changing the type of
Probs.
Without this patch:
DenseMap<Edge, BranchProbability> Probs
maps an ordered pair of a BasicBlock* and a successor index to an edge
probability.
With this patch:
DenseMap<const BasicBlock *, SmallVector<BranchProbability, 2>> Probs
maps a BasicBlock* to a vector of edge probabilities.
BranchProbabilityInfo has a property that for a given basic block, we
either have edge probabilities for all successors or do not have any
edge probability at all. This property combined with the current map
type leads to a somewhat complicated algorithm in eraseBlock to erase
map entries one by one while increasing the successor index.
The new map type allows us to remove the all edge probabilities for a
given basic block in a more intuitive manner, namely:
Probs.erase(BB);
Differential Revision: https://reviews.llvm.org/D91017
Added:
Modified:
llvm/include/llvm/Analysis/BranchProbabilityInfo.h
llvm/lib/Analysis/BranchProbabilityInfo.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/Analysis/BranchProbabilityInfo.h b/llvm/include/llvm/Analysis/BranchProbabilityInfo.h
index 64c3da80f6ea..b55b72cfa01e 100644
--- a/llvm/include/llvm/Analysis/BranchProbabilityInfo.h
+++ b/llvm/include/llvm/Analysis/BranchProbabilityInfo.h
@@ -266,7 +266,7 @@ class BranchProbabilityInfo {
// weight to just "inherit" the non-zero weight of an adjacent successor.
static const uint32_t DEFAULT_WEIGHT = 16;
- DenseMap<Edge, BranchProbability> Probs;
+ DenseMap<const BasicBlock *, SmallVector<BranchProbability, 2>> Probs;
/// Track the last function we run over for printing.
const Function *LastF = nullptr;
diff --git a/llvm/lib/Analysis/BranchProbabilityInfo.cpp b/llvm/lib/Analysis/BranchProbabilityInfo.cpp
index f235e9fb6a33..37504cf0a88c 100644
--- a/llvm/lib/Analysis/BranchProbabilityInfo.cpp
+++ b/llvm/lib/Analysis/BranchProbabilityInfo.cpp
@@ -1091,16 +1091,15 @@ BranchProbabilityInfo::getHotSucc(const BasicBlock *BB) const {
BranchProbability
BranchProbabilityInfo::getEdgeProbability(const BasicBlock *Src,
unsigned IndexInSuccessors) const {
- auto I = Probs.find(std::make_pair(Src, IndexInSuccessors));
- assert((Probs.end() == Probs.find(std::make_pair(Src, 0))) ==
- (Probs.end() == I) &&
- "Probability for I-th successor must always be defined along with the "
- "probability for the first successor");
-
- if (I != Probs.end())
- return I->second;
-
- return {1, static_cast<uint32_t>(succ_size(Src))};
+ auto I = Probs.find(Src);
+ if (I == Probs.end())
+ return {1, static_cast<uint32_t>(succ_size(Src))};
+
+ const SmallVector<BranchProbability, 2> &SrcProbs = I->second;
+ assert(SrcProbs.size() == Src->getTerminator()->getNumSuccessors() &&
+ "The number of edge probabilities must match the number of "
+ "successors.");
+ return SrcProbs[IndexInSuccessors];
}
BranchProbability
@@ -1114,13 +1113,18 @@ BranchProbabilityInfo::getEdgeProbability(const BasicBlock *Src,
BranchProbability
BranchProbabilityInfo::getEdgeProbability(const BasicBlock *Src,
const BasicBlock *Dst) const {
- if (!Probs.count(std::make_pair(Src, 0)))
+ auto SrcProbsIt = Probs.find(Src);
+ if (SrcProbsIt == Probs.end())
return BranchProbability(llvm::count(successors(Src), Dst), succ_size(Src));
+ const SmallVector<BranchProbability, 2> &SrcProbs = SrcProbsIt->second;
+ assert(SrcProbs.size() == Src->getTerminator()->getNumSuccessors() &&
+ "The number of edge probabilities must match the number of "
+ "successors.");
auto Prob = BranchProbability::getZero();
for (const_succ_iterator I = succ_begin(Src), E = succ_end(Src); I != E; ++I)
if (*I == Dst)
- Prob += Probs.find(std::make_pair(Src, I.getSuccessorIndex()))->second;
+ Prob += SrcProbs[I.getSuccessorIndex()];
return Prob;
}
@@ -1135,8 +1139,10 @@ void BranchProbabilityInfo::setEdgeProbability(
Handles.insert(BasicBlockCallbackVH(Src, this));
uint64_t TotalNumerator = 0;
+ auto &SrcProbs = this->Probs[Src];
+ SrcProbs.reserve(Probs.size());
for (unsigned SuccIdx = 0; SuccIdx < Probs.size(); ++SuccIdx) {
- this->Probs[std::make_pair(Src, SuccIdx)] = Probs[SuccIdx];
+ SrcProbs.push_back(Probs[SuccIdx]);
LLVM_DEBUG(dbgs() << "set edge " << Src->getName() << " -> " << SuccIdx
<< " successor probability to " << Probs[SuccIdx]
<< "\n");
@@ -1159,16 +1165,17 @@ void BranchProbabilityInfo::copyEdgeProbabilities(BasicBlock *Src,
assert(NumSuccessors == Dst->getTerminator()->getNumSuccessors());
if (NumSuccessors == 0)
return; // Nothing to set.
- if (this->Probs.find(std::make_pair(Src, 0)) == this->Probs.end())
+ auto SrcProbsIt = this->Probs.find(Src);
+ if (SrcProbsIt == this->Probs.end())
return; // No probability is set for edges from Src. Keep the same for Dst.
Handles.insert(BasicBlockCallbackVH(Dst, this));
- for (unsigned SuccIdx = 0; SuccIdx < NumSuccessors; ++SuccIdx) {
- auto Prob = this->Probs[std::make_pair(Src, SuccIdx)];
- this->Probs[std::make_pair(Dst, SuccIdx)] = Prob;
+ auto &DstProbs = this->Probs[Dst];
+ DstProbs = SrcProbsIt->second;
+ for (unsigned SuccIdx = 0; SuccIdx < NumSuccessors; ++SuccIdx)
LLVM_DEBUG(dbgs() << "set edge " << Dst->getName() << " -> " << SuccIdx
- << " successor probability to " << Prob << "\n");
- }
+ << " successor probability to " << DstProbs[SuccIdx]
+ << "\n");
}
raw_ostream &
@@ -1184,23 +1191,8 @@ BranchProbabilityInfo::printEdgeProbability(raw_ostream &OS,
}
void BranchProbabilityInfo::eraseBlock(const BasicBlock *BB) {
- // Note that we cannot use successors of BB because the terminator of BB may
- // have changed when eraseBlock is called as a BasicBlockCallbackVH callback.
- // Instead we remove prob data for the block by iterating successors by their
- // indices from 0 till the last which exists. There could not be prob data for
- // a pair (BB, N) if there is no data for (BB, N-1) because the data is always
- // set for all successors from 0 to M at once by the method
- // setEdgeProbability().
Handles.erase(BasicBlockCallbackVH(BB, this));
- for (unsigned I = 0;; ++I) {
- auto MapI = Probs.find(std::make_pair(BB, I));
- if (MapI == Probs.end()) {
- assert(Probs.count(std::make_pair(BB, I + 1)) == 0 &&
- "Must be no more successors");
- return;
- }
- Probs.erase(MapI);
- }
+ Probs.erase(BB);
}
void BranchProbabilityInfo::calculate(const Function &F, const LoopInfo &LI,
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