#ifndef LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
#define LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
-#include "llvm/InitializePasses.h"
-#include "llvm/Pass.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
#include "llvm/Support/BranchProbability.h"
namespace llvm {
class LoopInfo;
class raw_ostream;
-/// \brief Analysis pass providing branch probability information.
+/// \brief Analysis providing branch probability information.
///
-/// This is a function analysis pass which provides information on the relative
+/// This is a function analysis which provides information on the relative
/// probabilities of each "edge" in the function's CFG where such an edge is
-/// defined by a pair of basic blocks. The probability for a given block and
-/// a successor block are always relative to the probabilities of the other
-/// successor blocks. Another way of looking at it is that the probabilities
-/// for a given block B and each of its successors should sum to exactly
-/// one (100%).
-class BranchProbabilityInfo : public FunctionPass {
+/// defined by a pair (PredBlock and an index in the successors). The
+/// probability of an edge from one block is always relative to the
+/// probabilities of other edges from the block. The probabilites of all edges
+/// from a block sum to exactly one (100%).
+/// We use a pair (PredBlock and an index in the successors) to uniquely
+/// identify an edge, since we can have multiple edges from Src to Dst.
+/// As an example, we can have a switch which jumps to Dst with value 0 and
+/// value 10.
+class BranchProbabilityInfo {
public:
- static char ID;
-
- BranchProbabilityInfo() : FunctionPass(ID) {
- initializeBranchProbabilityInfoPass(*PassRegistry::getPassRegistry());
- }
+ void releaseMemory();
- void getAnalysisUsage(AnalysisUsage &AU) const;
- bool runOnFunction(Function &F);
- void print(raw_ostream &OS, const Module *M = 0) const;
+ void print(raw_ostream &OS) const;
/// \brief Get an edge's probability, relative to other out-edges of the Src.
///
/// (0%) and one (100%) of this edge executing, relative to other edges
/// leaving the 'Src' block. The returned probability is never zero, and can
/// only be one if the source block has only one successor.
+ BranchProbability getEdgeProbability(const BasicBlock *Src,
+ unsigned IndexInSuccessors) const;
+
+ /// \brief Get the probability of going from Src to Dst.
+ ///
+ /// It returns the sum of all probabilities for edges from Src to Dst.
BranchProbability getEdgeProbability(const BasicBlock *Src,
const BasicBlock *Dst) const;
raw_ostream &printEdgeProbability(raw_ostream &OS, const BasicBlock *Src,
const BasicBlock *Dst) const;
- /// \brief Get the raw edge weight calculated for the block pair.
+ /// \brief Get the raw edge weight calculated for the 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;
- /// \brief Set the raw edge weight for the block pair.
+ 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 a block. It can
+ /// 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
/// probability information. Read the implementation of how these edge
/// weights are calculated carefully before using!
- void setEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst,
+ void setEdgeWeight(const BasicBlock *Src, unsigned IndexInSuccessors,
uint32_t Weight);
+ static uint32_t getBranchWeightStackProtector(bool IsLikely) {
+ return IsLikely ? (1u << 20) - 1 : 1;
+ }
+
+ void calculate(Function &F, const LoopInfo& LI);
+
private:
- typedef std::pair<const BasicBlock *, const BasicBlock *> Edge;
+ // Since we allow duplicate edges from one basic block to another, we use
+ // a pair (PredBlock and an index in the successors) to specify an edge.
+ typedef std::pair<const BasicBlock *, unsigned> Edge;
// Default weight value. Used when we don't have information about the edge.
// TODO: DEFAULT_WEIGHT makes sense during static predication, when none of
/// \brief Track the set of blocks directly succeeded by a returning block.
SmallPtrSet<BasicBlock *, 16> PostDominatedByUnreachable;
+ /// \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);
bool calcPointerHeuristics(BasicBlock *BB);
- bool calcLoopBranchHeuristics(BasicBlock *BB);
+ bool calcLoopBranchHeuristics(BasicBlock *BB, const LoopInfo &LI);
bool calcZeroHeuristics(BasicBlock *BB);
bool calcFloatingPointHeuristics(BasicBlock *BB);
+ bool calcInvokeHeuristics(BasicBlock *BB);
+};
+
+/// \brief Legacy analysis pass which computes \c BranchProbabilityInfo.
+class BranchProbabilityInfoWrapperPass : public FunctionPass {
+ BranchProbabilityInfo BPI;
+
+public:
+ static char ID;
+
+ BranchProbabilityInfoWrapperPass() : FunctionPass(ID) {
+ initializeBranchProbabilityInfoWrapperPassPass(
+ *PassRegistry::getPassRegistry());
+ }
+
+ BranchProbabilityInfo &getBPI() { return BPI; }
+ const BranchProbabilityInfo &getBPI() const { return BPI; }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+ bool runOnFunction(Function &F) override;
+ void releaseMemory() override;
+ void print(raw_ostream &OS, const Module *M = nullptr) const override;
};
}
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