llvm.org GIT mirror llvm / release_80 include / llvm / Transforms / IPO / FunctionImport.h
release_80

Tree @release_80 (Download .tar.gz)

FunctionImport.h @release_80

a7649e8
 
 
 
 
 
 
 
 
02ce807
 
a7649e8
02ce807
a7649e8
02ce807
5f76ad9
4668002
385d706
76c218e
bc8e1bc
5e8cf48
02ce807
 
 
5e8cf48
14aae01
a7649e8
 
02ce807
a7649e8
 
f7d58f1
 
 
5e8cf48
92f5878
 
 
 
39b5a02
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
645cd31
39b5a02
 
645cd31
 
 
 
 
39b5a02
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
92f5878
 
 
 
 
 
39b5a02
 
a7649e8
5e8cf48
 
 
02ce807
a7649e8
5e8cf48
02ce807
a7649e8
dead081
02ce807
 
dead081
a7649e8
dead081
14aae01
a7649e8
5e8cf48
82673ec
5e8cf48
 
 
 
 
 
dead081
a7649e8
5e8cf48
385d706
 
 
2fb9a98
385d706
 
5e8cf48
 
29d66c4
 
 
5e8cf48
 
 
 
 
 
 
 
 
4668002
5e8cf48
ccb80b9
a439f48
 
 
 
 
 
 
 
27af205
2140d92
 
 
 
 
 
 
 
 
426dcef
 
 
 
 
a4ca999
 
426dcef
 
 
ccb80b9
 
426dcef
 
 
a3f1de9
 
 
 
 
 
 
 
b46c3d9
 
 
a4ca999
27af205
 
 
 
 
 
 
 
 
 
 
 
 
055f556
27af205
4b05ce2
055f556
7b0ba29
 
 
32d095c
3253066
32d095c
3253066
 
32d095c
 
 
 
 
a7649e8
02ce807
 
 
//===- llvm/Transforms/IPO/FunctionImport.h - ThinLTO importing -*- C++ -*-===//
//
//                      The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_TRANSFORMS_IPO_FUNCTIONIMPORT_H
#define LLVM_TRANSFORMS_IPO_FUNCTIONIMPORT_H

#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/ModuleSummaryIndex.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Support/Error.h"
#include <functional>
#include <map>
#include <memory>
#include <string>
#include <system_error>
#include <unordered_set>
#include <utility>

namespace llvm {

class Module;

/// The function importer is automatically importing function from other modules
/// based on the provided summary informations.
class FunctionImporter {
public:
  /// Set of functions to import from a source module. Each entry is a set
  /// containing all the GUIDs of all functions to import for a source module.
  using FunctionsToImportTy = std::unordered_set<GlobalValue::GUID>;

  /// The different reasons selectCallee will chose not to import a
  /// candidate.
  enum ImportFailureReason {
    None,
    // We can encounter a global variable instead of a function in rare
    // situations with SamplePGO. See comments where this failure type is
    // set for more details.
    GlobalVar,
    // Found to be globally dead, so we don't bother importing.
    NotLive,
    // Instruction count over the current threshold.
    TooLarge,
    // Don't import something with interposable linkage as we can't inline it
    // anyway.
    InterposableLinkage,
    // Generally we won't end up failing due to this reason, as we expect
    // to find at least one summary for the GUID that is global or a local
    // in the referenced module for direct calls.
    LocalLinkageNotInModule,
    // This corresponds to the NotEligibleToImport being set on the summary,
    // which can happen in a few different cases (e.g. local that can't be
    // renamed or promoted because it is referenced on a llvm*.used variable).
    NotEligible,
    // This corresponds to NoInline being set on the function summary,
    // which will happen if it is known that the inliner will not be able
    // to inline the function (e.g. it is marked with a NoInline attribute).
    NoInline
  };

  /// Information optionally tracked for candidates the importer decided
  /// not to import. Used for optional stat printing.
  struct ImportFailureInfo {
    // The ValueInfo corresponding to the candidate. We save an index hash
    // table lookup for each GUID by stashing this here.
    ValueInfo VI;
    // The maximum call edge hotness for all failed imports of this candidate.
    CalleeInfo::HotnessType MaxHotness;
    // most recent reason for failing to import (doesn't necessarily correspond
    // to the attempt with the maximum hotness).
    ImportFailureReason Reason;
    // The number of times we tried to import candidate but failed.
    unsigned Attempts;
    ImportFailureInfo(ValueInfo VI, CalleeInfo::HotnessType MaxHotness,
                      ImportFailureReason Reason, unsigned Attempts)
        : VI(VI), MaxHotness(MaxHotness), Reason(Reason), Attempts(Attempts) {}
  };

  /// Map of callee GUID considered for import into a given module to a pair
  /// consisting of the largest threshold applied when deciding whether to
  /// import it and, if we decided to import, a pointer to the summary instance
  /// imported. If we decided not to import, the summary will be nullptr.
  using ImportThresholdsTy =
      DenseMap<GlobalValue::GUID,
               std::tuple<unsigned, const GlobalValueSummary *,
                          std::unique_ptr<ImportFailureInfo>>>;

  /// The map contains an entry for every module to import from, the key being
  /// the module identifier to pass to the ModuleLoader. The value is the set of
  /// functions to import.
  using ImportMapTy = StringMap<FunctionsToImportTy>;

  /// The set contains an entry for every global value the module exports.
  using ExportSetTy = std::unordered_set<GlobalValue::GUID>;

  /// A function of this type is used to load modules referenced by the index.
  using ModuleLoaderTy =
      std::function<Expected<std::unique_ptr<Module>>(StringRef Identifier)>;

  /// Create a Function Importer.
  FunctionImporter(const ModuleSummaryIndex &Index, ModuleLoaderTy ModuleLoader)
      : Index(Index), ModuleLoader(std::move(ModuleLoader)) {}

  /// Import functions in Module \p M based on the supplied import list.
  Expected<bool> importFunctions(Module &M, const ImportMapTy &ImportList);

private:
  /// The summaries index used to trigger importing.
  const ModuleSummaryIndex &Index;

  /// Factory function to load a Module for a given identifier
  ModuleLoaderTy ModuleLoader;
};

/// The function importing pass
class FunctionImportPass : public PassInfoMixin<FunctionImportPass> {
public:
  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
};

/// Compute all the imports and exports for every module in the Index.
///
/// \p ModuleToDefinedGVSummaries contains for each Module a map
/// (GUID -> Summary) for every global defined in the module.
///
/// \p ImportLists will be populated with an entry for every Module we are
/// importing into. This entry is itself a map that can be passed to
/// FunctionImporter::importFunctions() above (see description there).
///
/// \p ExportLists contains for each Module the set of globals (GUID) that will
/// be imported by another module, or referenced by such a function. I.e. this
/// is the set of globals that need to be promoted/renamed appropriately.
void ComputeCrossModuleImport(
    const ModuleSummaryIndex &Index,
    const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
    StringMap<FunctionImporter::ImportMapTy> &ImportLists,
    StringMap<FunctionImporter::ExportSetTy> &ExportLists);

/// Compute all the imports for the given module using the Index.
///
/// \p ImportList will be populated with a map that can be passed to
/// FunctionImporter::importFunctions() above (see description there).
void ComputeCrossModuleImportForModule(
    StringRef ModulePath, const ModuleSummaryIndex &Index,
    FunctionImporter::ImportMapTy &ImportList);

/// Mark all external summaries in \p Index for import into the given module.
/// Used for distributed builds using a distributed index.
///
/// \p ImportList will be populated with a map that can be passed to
/// FunctionImporter::importFunctions() above (see description there).
void ComputeCrossModuleImportForModuleFromIndex(
    StringRef ModulePath, const ModuleSummaryIndex &Index,
    FunctionImporter::ImportMapTy &ImportList);

/// PrevailingType enum used as a return type of callback passed
/// to computeDeadSymbols. Yes and No values used when status explicitly
/// set by symbols resolution, otherwise status is Unknown.
enum class PrevailingType { Yes, No, Unknown };

/// Compute all the symbols that are "dead": i.e these that can't be reached
/// in the graph from any of the given symbols listed in
/// \p GUIDPreservedSymbols. Non-prevailing symbols are symbols without a
/// prevailing copy anywhere in IR and are normally dead, \p isPrevailing
/// predicate returns status of symbol.
void computeDeadSymbols(
    ModuleSummaryIndex &Index,
    const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols,
    function_ref<PrevailingType(GlobalValue::GUID)> isPrevailing);

/// Compute dead symbols and run constant propagation in combined index
/// after that.
void computeDeadSymbolsWithConstProp(
    ModuleSummaryIndex &Index,
    const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols,
    function_ref<PrevailingType(GlobalValue::GUID)> isPrevailing,
    bool ImportEnabled);

/// Converts value \p GV to declaration, or replaces with a declaration if
/// it is an alias. Returns true if converted, false if replaced.
bool convertToDeclaration(GlobalValue &GV);

/// Compute the set of summaries needed for a ThinLTO backend compilation of
/// \p ModulePath.
//
/// This includes summaries from that module (in case any global summary based
/// optimizations were recorded) and from any definitions in other modules that
/// should be imported.
//
/// \p ModuleToSummariesForIndex will be populated with the needed summaries
/// from each required module path. Use a std::map instead of StringMap to get
/// stable order for bitcode emission.
void gatherImportedSummariesForModule(
    StringRef ModulePath,
    const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
    const FunctionImporter::ImportMapTy &ImportList,
    std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex);

/// Emit into \p OutputFilename the files module \p ModulePath will import from.
std::error_code EmitImportsFiles(
    StringRef ModulePath, StringRef OutputFilename,
    const std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex);

/// Resolve prevailing symbol linkages in \p TheModule based on the information
/// recorded in the summaries during global summary-based analysis.
void thinLTOResolvePrevailingInModule(Module &TheModule,
                                      const GVSummaryMapTy &DefinedGlobals);

/// Internalize \p TheModule based on the information recorded in the summaries
/// during global summary-based analysis.
void thinLTOInternalizeModule(Module &TheModule,
                              const GVSummaryMapTy &DefinedGlobals);

} // end namespace llvm

#endif // LLVM_TRANSFORMS_IPO_FUNCTIONIMPORT_H