1 //===- llvm/Transforms/IPO/FunctionImport.h - ThinLTO importing -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_TRANSFORMS_IPO_FUNCTIONIMPORT_H
11 #define LLVM_TRANSFORMS_IPO_FUNCTIONIMPORT_H
13 #include "llvm/ADT/DenseSet.h"
14 #include "llvm/ADT/StringMap.h"
15 #include "llvm/ADT/StringRef.h"
16 #include "llvm/IR/GlobalValue.h"
17 #include "llvm/IR/ModuleSummaryIndex.h"
18 #include "llvm/IR/PassManager.h"
19 #include "llvm/Support/Error.h"
24 #include <system_error>
25 #include <unordered_set>
32 /// The function importer is automatically importing function from other modules
33 /// based on the provided summary informations.
34 class FunctionImporter {
36 /// Set of functions to import from a source module. Each entry is a set
37 /// containing all the GUIDs of all functions to import for a source module.
38 using FunctionsToImportTy = std::unordered_set<GlobalValue::GUID>;
40 /// Map of callee GUID considered for import into a given module to a pair
41 /// consisting of the largest threshold applied when deciding whether to
42 /// import it and, if we decided to import, a pointer to the summary instance
43 /// imported. If we decided not to import, the summary will be nullptr.
44 using ImportThresholdsTy =
45 DenseMap<GlobalValue::GUID,
46 std::pair<unsigned, const GlobalValueSummary *>>;
48 /// The map contains an entry for every module to import from, the key being
49 /// the module identifier to pass to the ModuleLoader. The value is the set of
50 /// functions to import.
51 using ImportMapTy = StringMap<FunctionsToImportTy>;
53 /// The set contains an entry for every global value the module exports.
54 using ExportSetTy = std::unordered_set<GlobalValue::GUID>;
56 /// A function of this type is used to load modules referenced by the index.
57 using ModuleLoaderTy =
58 std::function<Expected<std::unique_ptr<Module>>(StringRef Identifier)>;
60 /// Create a Function Importer.
61 FunctionImporter(const ModuleSummaryIndex &Index, ModuleLoaderTy ModuleLoader)
62 : Index(Index), ModuleLoader(std::move(ModuleLoader)) {}
64 /// Import functions in Module \p M based on the supplied import list.
65 Expected<bool> importFunctions(Module &M, const ImportMapTy &ImportList);
68 /// The summaries index used to trigger importing.
69 const ModuleSummaryIndex &Index;
71 /// Factory function to load a Module for a given identifier
72 ModuleLoaderTy ModuleLoader;
75 /// The function importing pass
76 class FunctionImportPass : public PassInfoMixin<FunctionImportPass> {
78 PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
81 /// Compute all the imports and exports for every module in the Index.
83 /// \p ModuleToDefinedGVSummaries contains for each Module a map
84 /// (GUID -> Summary) for every global defined in the module.
86 /// \p ImportLists will be populated with an entry for every Module we are
87 /// importing into. This entry is itself a map that can be passed to
88 /// FunctionImporter::importFunctions() above (see description there).
90 /// \p ExportLists contains for each Module the set of globals (GUID) that will
91 /// be imported by another module, or referenced by such a function. I.e. this
92 /// is the set of globals that need to be promoted/renamed appropriately.
93 void ComputeCrossModuleImport(
94 const ModuleSummaryIndex &Index,
95 const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
96 StringMap<FunctionImporter::ImportMapTy> &ImportLists,
97 StringMap<FunctionImporter::ExportSetTy> &ExportLists);
99 /// Compute all the imports for the given module using the Index.
101 /// \p ImportList will be populated with a map that can be passed to
102 /// FunctionImporter::importFunctions() above (see description there).
103 void ComputeCrossModuleImportForModule(
104 StringRef ModulePath, const ModuleSummaryIndex &Index,
105 FunctionImporter::ImportMapTy &ImportList);
107 /// Mark all external summaries in \p Index for import into the given module.
108 /// Used for distributed builds using a distributed index.
110 /// \p ImportList will be populated with a map that can be passed to
111 /// FunctionImporter::importFunctions() above (see description there).
112 void ComputeCrossModuleImportForModuleFromIndex(
113 StringRef ModulePath, const ModuleSummaryIndex &Index,
114 FunctionImporter::ImportMapTy &ImportList);
116 /// PrevailingType enum used as a return type of callback passed
117 /// to computeDeadSymbols. Yes and No values used when status explicitly
118 /// set by symbols resolution, otherwise status is Unknown.
119 enum class PrevailingType { Yes, No, Unknown };
121 /// Compute all the symbols that are "dead": i.e these that can't be reached
122 /// in the graph from any of the given symbols listed in
123 /// \p GUIDPreservedSymbols. Non-prevailing symbols are symbols without a
124 /// prevailing copy anywhere in IR and are normally dead, \p isPrevailing
125 /// predicate returns status of symbol.
126 void computeDeadSymbols(
127 ModuleSummaryIndex &Index,
128 const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols,
129 function_ref<PrevailingType(GlobalValue::GUID)> isPrevailing);
131 /// Converts value \p GV to declaration, or replaces with a declaration if
132 /// it is an alias. Returns true if converted, false if replaced.
133 bool convertToDeclaration(GlobalValue &GV);
135 /// Compute the set of summaries needed for a ThinLTO backend compilation of
138 /// This includes summaries from that module (in case any global summary based
139 /// optimizations were recorded) and from any definitions in other modules that
140 /// should be imported.
142 /// \p ModuleToSummariesForIndex will be populated with the needed summaries
143 /// from each required module path. Use a std::map instead of StringMap to get
144 /// stable order for bitcode emission.
145 void gatherImportedSummariesForModule(
146 StringRef ModulePath,
147 const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
148 const FunctionImporter::ImportMapTy &ImportList,
149 std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex);
151 /// Emit into \p OutputFilename the files module \p ModulePath will import from.
152 std::error_code EmitImportsFiles(
153 StringRef ModulePath, StringRef OutputFilename,
154 const std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex);
156 /// Resolve WeakForLinker values in \p TheModule based on the information
157 /// recorded in the summaries during global summary-based analysis.
158 void thinLTOResolveWeakForLinkerModule(Module &TheModule,
159 const GVSummaryMapTy &DefinedGlobals);
161 /// Internalize \p TheModule based on the information recorded in the summaries
162 /// during global summary-based analysis.
163 void thinLTOInternalizeModule(Module &TheModule,
164 const GVSummaryMapTy &DefinedGlobals);
166 } // end namespace llvm
168 #endif // LLVM_TRANSFORMS_IPO_FUNCTIONIMPORT_H