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//===-- MissingFrameInferrer.h - Missing frame inferrer ---------- C++/-*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_PROFGEN_MISSINGFRAMEINFERRER_H
#define LLVM_TOOLS_LLVM_PROFGEN_MISSINGFRAMEINFERRER_H
#include "PerfReader.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include <unordered_map>
#include <unordered_set>
namespace llvm {
namespace sampleprof {
class ProfiledBinary;
struct BinaryFunction;
class MissingFrameInferrer {
public:
MissingFrameInferrer(ProfiledBinary *Binary) : Binary(Binary) {}
// Defininig a frame transition from a caller function to the callee function.
using CallerCalleePair = std::pair<BinaryFunction *, BinaryFunction *>;
void initialize(const ContextSampleCounterMap *SampleCounters);
// Given an input `Context`, output `NewContext` with inferred missing tail
// call frames.
void inferMissingFrames(const SmallVectorImpl<uint64_t> &Context,
SmallVectorImpl<uint64_t> &NewContext);
private:
friend class ProfiledBinary;
// Compute a unique tail call path for a pair of source frame address and
// target frame address. Append the unique path prefix (not including `To`) to
// `UniquePath` if exists. Return the whether this's a unqiue tail call
// path. The source/dest frame will typically be a pair of adjacent frame
// entries of call stack samples.
bool inferMissingFrames(uint64_t From, uint64_t To,
SmallVectorImpl<uint64_t> &UniquePath);
// Compute a unique tail call path from the source frame address to the target
// function. Output the unique path prefix (not including `To`) in
// `UniquePath` if exists. Return the number of possibly availabe tail call
// paths.
uint64_t computeUniqueTailCallPath(uint64_t From, BinaryFunction *To,
SmallVectorImpl<uint64_t> &UniquePath);
// Compute a unique tail call path from the source function to the target
// function. Output the unique path prefix (not including `To`) in
// `UniquePath` if exists. Return the number of possibly availabe tail call
// paths.
uint64_t computeUniqueTailCallPath(BinaryFunction *From, BinaryFunction *To,
SmallVectorImpl<uint64_t> &UniquePath);
ProfiledBinary *Binary;
// A map of call instructions to their target addresses. This is first
// populated with static call edges but then trimmed down to dynamic call
// edges based on LBR samples.
std::unordered_map<uint64_t, std::unordered_set<uint64_t>> CallEdges;
// A map of tail call instructions to their target addresses. This is first
// populated with static call edges but then trimmed down to dynamic call
// edges based on LBR samples.
std::unordered_map<uint64_t, std::unordered_set<uint64_t>> TailCallEdges;
// Dynamic call targets in terms of BinaryFunction for any calls.
std::unordered_map<uint64_t, std::unordered_set<BinaryFunction *>> CallEdgesF;
// Dynamic call targets in terms of BinaryFunction for tail calls.
std::unordered_map<uint64_t, std::unordered_set<BinaryFunction *>>
TailCallEdgesF;
// Dynamic tail call targets of caller functions.
std::unordered_map<BinaryFunction *, std::vector<uint64_t>> FuncToTailCallMap;
// Functions that are reachable via tail calls.
DenseSet<const BinaryFunction *> TailCallTargetFuncs;
struct PairHash {
std::size_t operator()(
const std::pair<BinaryFunction *, BinaryFunction *> &Pair) const {
return std::hash<BinaryFunction *>()(Pair.first) ^
std::hash<BinaryFunction *>()(Pair.second);
}
};
// Cached results from a CallerCalleePair to a unique call path between them.
std::unordered_map<CallerCalleePair, std::vector<uint64_t>, PairHash>
UniquePaths;
// Cached results from CallerCalleePair to the number of available call paths.
std::unordered_map<CallerCalleePair, uint64_t, PairHash> NonUniquePaths;
DenseSet<BinaryFunction *> Visiting;
uint32_t CurSearchingDepth = 0;
#if LLVM_ENABLE_STATS
DenseSet<std::pair<uint64_t, uint64_t>> ReachableViaUniquePaths;
DenseSet<std::pair<uint64_t, uint64_t>> Unreachables;
DenseSet<std::pair<uint64_t, uint64_t>> ReachableViaMultiPaths;
#endif
};
} // end namespace sampleprof
} // end namespace llvm
#endif
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