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 map
37 /// containing all the functions to import for a source module.
38 /// The keys is the GUID identifying a function to import, and the value
39 /// is the threshold applied when deciding to import it.
40 using FunctionsToImportTy = std::map<GlobalValue::GUID, unsigned>;
42 /// The map contains an entry for every module to import from, the key being
43 /// the module identifier to pass to the ModuleLoader. The value is the set of
44 /// functions to import.
45 using ImportMapTy = StringMap<FunctionsToImportTy>;
47 /// The set contains an entry for every global value the module exports.
48 using ExportSetTy = std::unordered_set<GlobalValue::GUID>;
50 /// A function of this type is used to load modules referenced by the index.
51 using ModuleLoaderTy =
52 std::function<Expected<std::unique_ptr<Module>>(StringRef Identifier)>;
54 /// Create a Function Importer.
55 FunctionImporter(const ModuleSummaryIndex &Index, ModuleLoaderTy ModuleLoader)
56 : Index(Index), ModuleLoader(std::move(ModuleLoader)) {}
58 /// Import functions in Module \p M based on the supplied import list.
59 Expected<bool> importFunctions(Module &M, const ImportMapTy &ImportList);
62 /// The summaries index used to trigger importing.
63 const ModuleSummaryIndex &Index;
65 /// Factory function to load a Module for a given identifier
66 ModuleLoaderTy ModuleLoader;
69 /// The function importing pass
70 class FunctionImportPass : public PassInfoMixin<FunctionImportPass> {
72 PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
75 /// Compute all the imports and exports for every module in the Index.
77 /// \p ModuleToDefinedGVSummaries contains for each Module a map
78 /// (GUID -> Summary) for every global defined in the module.
80 /// \p ImportLists will be populated with an entry for every Module we are
81 /// importing into. This entry is itself a map that can be passed to
82 /// FunctionImporter::importFunctions() above (see description there).
84 /// \p ExportLists contains for each Module the set of globals (GUID) that will
85 /// be imported by another module, or referenced by such a function. I.e. this
86 /// is the set of globals that need to be promoted/renamed appropriately.
87 void ComputeCrossModuleImport(
88 const ModuleSummaryIndex &Index,
89 const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
90 StringMap<FunctionImporter::ImportMapTy> &ImportLists,
91 StringMap<FunctionImporter::ExportSetTy> &ExportLists);
93 /// Compute all the imports for the given module using the Index.
95 /// \p ImportList will be populated with a map that can be passed to
96 /// FunctionImporter::importFunctions() above (see description there).
97 void ComputeCrossModuleImportForModule(
98 StringRef ModulePath, const ModuleSummaryIndex &Index,
99 FunctionImporter::ImportMapTy &ImportList);
101 /// Mark all external summaries in \p Index for import into the given module.
102 /// Used for distributed builds using a distributed index.
104 /// \p ImportList will be populated with a map that can be passed to
105 /// FunctionImporter::importFunctions() above (see description there).
106 void ComputeCrossModuleImportForModuleFromIndex(
107 StringRef ModulePath, const ModuleSummaryIndex &Index,
108 FunctionImporter::ImportMapTy &ImportList);
110 /// Compute all the symbols that are "dead": i.e these that can't be reached
111 /// in the graph from any of the given symbols listed in
112 /// \p GUIDPreservedSymbols.
113 void computeDeadSymbols(
114 ModuleSummaryIndex &Index,
115 const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols);
117 /// Compute the set of summaries needed for a ThinLTO backend compilation of
120 /// This includes summaries from that module (in case any global summary based
121 /// optimizations were recorded) and from any definitions in other modules that
122 /// should be imported.
124 /// \p ModuleToSummariesForIndex will be populated with the needed summaries
125 /// from each required module path. Use a std::map instead of StringMap to get
126 /// stable order for bitcode emission.
127 void gatherImportedSummariesForModule(
128 StringRef ModulePath,
129 const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
130 const FunctionImporter::ImportMapTy &ImportList,
131 std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex);
133 /// Emit into \p OutputFilename the files module \p ModulePath will import from.
135 EmitImportsFiles(StringRef ModulePath, StringRef OutputFilename,
136 const FunctionImporter::ImportMapTy &ModuleImports);
138 /// Resolve WeakForLinker values in \p TheModule based on the information
139 /// recorded in the summaries during global summary-based analysis.
140 void thinLTOResolveWeakForLinkerModule(Module &TheModule,
141 const GVSummaryMapTy &DefinedGlobals);
143 /// Internalize \p TheModule based on the information recorded in the summaries
144 /// during global summary-based analysis.
145 void thinLTOInternalizeModule(Module &TheModule,
146 const GVSummaryMapTy &DefinedGlobals);
148 } // end namespace llvm
150 #endif // LLVM_TRANSFORMS_IPO_FUNCTIONIMPORT_H