StaticDataProfileInfo.h

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#ifndef LLVM_ANALYSIS_STATICDATAPROFILEINFO_H
#define LLVM_ANALYSIS_STATICDATAPROFILEINFO_H
 
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/IR/Analysis.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
#include "llvm/Support/Compiler.h"
#include <memory>
 
namespace llvm {
 
struct AnalysisOptions;
 
namespace memprof {
/// Return -memprof-annotate-string-literal-section-prefix.
LLVM_ABI bool shouldAnnotateStringLiteralSectionPrefix(const LLVMContext &C);
 
// Represents the eligibility status of a global variable for section prefix
// annotation. Other than AnnotationOk, each enum value indicates a specific
// reason for ineligibility.
enum class AnnotationKind : uint8_t {
  AnnotationOK,
  DeclForLinker,
  ExplicitSection,
  ReservedName,
};
/// Returns the annotation kind of the global variable \p GV.
LLVM_ABI AnnotationKind getAnnotationKind(const GlobalVariable &GV);
 
/// Returns true if the annotation kind of the global variable \p GV is
/// AnnotationOK.
LLVM_ABI bool IsAnnotationOK(const GlobalVariable &GV);
} // namespace memprof
 
/// A class that holds the constants that represent static data and their
/// profile information and provides methods to operate on them.
class StaticDataProfileInfo {
public:
  /// A constant is tracked only if the following conditions are met.
  ///   1) It has local (i.e., private or internal) linkage.
  //    2) Its data kind is one of {.rodata, .data, .bss, .data.rel.ro}.
  //    3) It's eligible for section prefix annotation. See `AnnotationKind`
  //       above for ineligible reasons.
  DenseMap<const Constant *, uint64_t> ConstantProfileCounts;
 
  /// Keeps track of the constants that are seen at least once without profile
  /// counts.
  DenseSet<const Constant *> ConstantWithoutCounts;
 
  /// If \p C has a count, return it. Otherwise, return std::nullopt.
  LLVM_ABI std::optional<uint64_t>
  getConstantProfileCount(const Constant *C) const;
 
  /// Use signed enums for enum value comparison, and make 'LukewarmOrUnknown'
  /// as 0 so any accidentally uninitialized value will default to unknown.
  enum class StaticDataHotness : int8_t {
    Cold = -1,
    LukewarmOrUnknown = 0,
    Hot = 1,
  };
 
  /// Return the hotness of the constant \p C based on its profile count \p
  /// Count.
  LLVM_ABI StaticDataHotness getConstantHotnessUsingProfileCount(
      const Constant *C, const ProfileSummaryInfo *PSI, uint64_t Count) const;
 
  /// Return the hotness based on section prefix \p SectionPrefix.
  LLVM_ABI StaticDataHotness getSectionHotnessUsingDataAccessProfile(
      std::optional<StringRef> SectionPrefix) const;
 
  /// Return the string representation of the hotness enum \p Hotness.
  LLVM_ABI StringRef hotnessToStr(StaticDataHotness Hotness) const;
 
  const AnalysisOptions &Opts;
  bool EnableDataAccessProf = false;
 
public:
  StaticDataProfileInfo(const AnalysisOptions &Opts, bool EnableDataAccessProf)
      : Opts(Opts), EnableDataAccessProf(EnableDataAccessProf) {}
 
  /// Return -preserve-hot-data-section-prefix.
  LLVM_ABI static bool shouldPreserveHotDataSectionPrefix(const LLVMContext &C);
 
  /// If \p Count is not nullopt, add it to the profile count of the constant \p
  /// C in a saturating way, and clamp the count to \p getInstrMaxCountValue if
  /// the result exceeds it. Otherwise, mark the constant as having no profile
  /// count.
  LLVM_ABI void addConstantProfileCount(const Constant *C,
                                        std::optional<uint64_t> Count);
 
  /// Given a constant \p C, returns a section prefix.
  /// If \p C is a global variable, the section prefix is the bigger one
  /// between its existing section prefix and its use profile count. Otherwise,
  /// the section prefix is based on its use profile count.
  LLVM_ABI StringRef getConstantSectionPrefix(
      const Constant *C, const ProfileSummaryInfo *PSI) const;
};
 
/// This wraps the StaticDataProfileInfo object as an immutable pass, for a
/// backend pass to operate on.
class LLVM_ABI StaticDataProfileInfoWrapperPass : public ImmutablePass {
public:
  static char ID;
  StaticDataProfileInfoWrapperPass();
  bool doInitialization(Module &M) override;
  bool doFinalization(Module &M) override;
 
  StaticDataProfileInfo &getStaticDataProfileInfo() { return *Info; }
  const StaticDataProfileInfo &getStaticDataProfileInfo() const {
    return *Info;
  }
 
  /// This pass provides StaticDataProfileInfo for reads/writes but does not
  /// modify \p M or other analysis. All analysis are preserved.
  void getAnalysisUsage(AnalysisUsage &AU) const override {
    AU.setPreservesAll();
  }
 
private:
  std::unique_ptr<StaticDataProfileInfo> Info;
};
 
class LLVM_ABI StaticDataProfileInfoAnalysis
    : public AnalysisInfoMixin<StaticDataProfileInfoAnalysis> {
public:
  static AnalysisKey Key;
 
  class Result {
    std::unique_ptr<StaticDataProfileInfo> HeldInfo;
    Result(std::unique_ptr<StaticDataProfileInfo> &&Info)
        : HeldInfo(std::move(Info)) {}
    friend class StaticDataProfileInfoAnalysis;
 
  public:
    StaticDataProfileInfo &getStaticDataProfileInfo() {
      return *HeldInfo;
    }
 
    bool invalidate(Module &, const PreservedAnalyses &,
                    ModuleAnalysisManager::Invalidator &) {
      return false;
    }
  };
 
  Result run(Module &M, ModuleAnalysisManager &);
};
 
} // namespace llvm
 
#endif // LLVM_ANALYSIS_STATICDATAPROFILEINFO_H