1 //===-Config.h - LLVM Link Time Optimizer Configuration ---------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines the lto::Config data structure, which allows clients to 10 // configure LTO. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_LTO_CONFIG_H 15 #define LLVM_LTO_CONFIG_H 16 17 #include "llvm/ADT/DenseSet.h" 18 #include "llvm/Config/llvm-config.h" 19 #include "llvm/IR/DiagnosticInfo.h" 20 #include "llvm/IR/GlobalValue.h" 21 #include "llvm/IR/LLVMContext.h" 22 #include "llvm/IR/LegacyPassManager.h" 23 #include "llvm/Passes/PassBuilder.h" 24 #include "llvm/Support/CodeGen.h" 25 #include "llvm/Target/TargetOptions.h" 26 27 #include <functional> 28 29 namespace llvm { 30 31 class Error; 32 class Module; 33 class ModuleSummaryIndex; 34 class raw_pwrite_stream; 35 36 namespace lto { 37 38 /// LTO configuration. A linker can configure LTO by setting fields in this data 39 /// structure and passing it to the lto::LTO constructor. 40 struct Config { 41 enum VisScheme { 42 FromPrevailing, 43 ELF, 44 }; 45 // Note: when adding fields here, consider whether they need to be added to 46 // computeCacheKey in LTO.cpp. 47 std::string CPU; 48 TargetOptions Options; 49 std::vector<std::string> MAttrs; 50 std::vector<std::string> PassPlugins; 51 /// For adding passes that run right before codegen. 52 std::function<void(legacy::PassManager &)> PreCodeGenPassesHook; 53 Optional<Reloc::Model> RelocModel = Reloc::PIC_; 54 Optional<CodeModel::Model> CodeModel = None; 55 CodeGenOpt::Level CGOptLevel = CodeGenOpt::Default; 56 CodeGenFileType CGFileType = CGFT_ObjectFile; 57 unsigned OptLevel = 2; 58 bool DisableVerify = false; 59 60 /// Use the new pass manager 61 bool UseNewPM = LLVM_ENABLE_NEW_PASS_MANAGER; 62 63 /// Flag to indicate that the optimizer should not assume builtins are present 64 /// on the target. 65 bool Freestanding = false; 66 67 /// Disable entirely the optimizer, including importing for ThinLTO 68 bool CodeGenOnly = false; 69 70 /// Run PGO context sensitive IR instrumentation. 71 bool RunCSIRInstr = false; 72 73 /// Asserts whether we can assume whole program visibility during the LTO 74 /// link. 75 bool HasWholeProgramVisibility = false; 76 77 /// Always emit a Regular LTO object even when it is empty because no Regular 78 /// LTO modules were linked. This option is useful for some build system which 79 /// want to know a priori all possible output files. 80 bool AlwaysEmitRegularLTOObj = false; 81 82 /// Allows non-imported definitions to get the potentially more constraining 83 /// visibility from the prevailing definition. FromPrevailing is the default 84 /// because it works for many binary formats. ELF can use the more optimized 85 /// 'ELF' scheme. 86 VisScheme VisibilityScheme = FromPrevailing; 87 88 /// If this field is set, the set of passes run in the middle-end optimizer 89 /// will be the one specified by the string. Only works with the new pass 90 /// manager as the old one doesn't have this ability. 91 std::string OptPipeline; 92 93 // If this field is set, it has the same effect of specifying an AA pipeline 94 // identified by the string. Only works with the new pass manager, in 95 // conjunction OptPipeline. 96 std::string AAPipeline; 97 98 /// Setting this field will replace target triples in input files with this 99 /// triple. 100 std::string OverrideTriple; 101 102 /// Setting this field will replace unspecified target triples in input files 103 /// with this triple. 104 std::string DefaultTriple; 105 106 /// Context Sensitive PGO profile path. 107 std::string CSIRProfile; 108 109 /// Sample PGO profile path. 110 std::string SampleProfile; 111 112 /// Name remapping file for profile data. 113 std::string ProfileRemapping; 114 115 /// The directory to store .dwo files. 116 std::string DwoDir; 117 118 /// The name for the split debug info file used for the DW_AT_[GNU_]dwo_name 119 /// attribute in the skeleton CU. This should generally only be used when 120 /// running an individual backend directly via thinBackend(), as otherwise 121 /// all objects would use the same .dwo file. Not used as output path. 122 std::string SplitDwarfFile; 123 124 /// The path to write a .dwo file to. This should generally only be used when 125 /// running an individual backend directly via thinBackend(), as otherwise 126 /// all .dwo files will be written to the same path. Not used in skeleton CU. 127 std::string SplitDwarfOutput; 128 129 /// Optimization remarks file path. 130 std::string RemarksFilename; 131 132 /// Optimization remarks pass filter. 133 std::string RemarksPasses; 134 135 /// Whether to emit optimization remarks with hotness informations. 136 bool RemarksWithHotness = false; 137 138 /// The minimum hotness value a diagnostic needs in order to be included in 139 /// optimization diagnostics. 140 /// 141 /// The threshold is an Optional value, which maps to one of the 3 states: 142 /// 1. 0 => threshold disabled. All emarks will be printed. 143 /// 2. positive int => manual threshold by user. Remarks with hotness exceed 144 /// threshold will be printed. 145 /// 3. None => 'auto' threshold by user. The actual value is not 146 /// available at command line, but will be synced with 147 /// hotness threhold from profile summary during 148 /// compilation. 149 /// 150 /// If threshold option is not specified, it is disabled by default. 151 llvm::Optional<uint64_t> RemarksHotnessThreshold = 0; 152 153 /// The format used for serializing remarks (default: YAML). 154 std::string RemarksFormat; 155 156 /// Whether to emit the pass manager debuggging informations. 157 bool DebugPassManager = false; 158 159 /// Statistics output file path. 160 std::string StatsFile; 161 162 /// Specific thinLTO modules to compile. 163 std::vector<std::string> ThinLTOModulesToCompile; 164 165 /// Time trace enabled. 166 bool TimeTraceEnabled = false; 167 168 /// Time trace granularity. 169 unsigned TimeTraceGranularity = 500; 170 171 bool ShouldDiscardValueNames = true; 172 DiagnosticHandlerFunction DiagHandler; 173 174 /// Add FSAFDO discriminators. 175 bool AddFSDiscriminator = false; 176 177 /// If this field is set, LTO will write input file paths and symbol 178 /// resolutions here in llvm-lto2 command line flag format. This can be 179 /// used for testing and for running the LTO pipeline outside of the linker 180 /// with llvm-lto2. 181 std::unique_ptr<raw_ostream> ResolutionFile; 182 183 /// Tunable parameters for passes in the default pipelines. 184 PipelineTuningOptions PTO; 185 186 /// The following callbacks deal with tasks, which normally represent the 187 /// entire optimization and code generation pipeline for what will become a 188 /// single native object file. Each task has a unique identifier between 0 and 189 /// getMaxTasks()-1, which is supplied to the callback via the Task parameter. 190 /// A task represents the entire pipeline for ThinLTO and regular 191 /// (non-parallel) LTO, but a parallel code generation task will be split into 192 /// N tasks before code generation, where N is the parallelism level. 193 /// 194 /// LTO may decide to stop processing a task at any time, for example if the 195 /// module is empty or if a module hook (see below) returns false. For this 196 /// reason, the client should not expect to receive exactly getMaxTasks() 197 /// native object files. 198 199 /// A module hook may be used by a linker to perform actions during the LTO 200 /// pipeline. For example, a linker may use this function to implement 201 /// -save-temps. If this function returns false, any further processing for 202 /// that task is aborted. 203 /// 204 /// Module hooks must be thread safe with respect to the linker's internal 205 /// data structures. A module hook will never be called concurrently from 206 /// multiple threads with the same task ID, or the same module. 207 /// 208 /// Note that in out-of-process backend scenarios, none of the hooks will be 209 /// called for ThinLTO tasks. 210 using ModuleHookFn = std::function<bool(unsigned Task, const Module &)>; 211 212 /// This module hook is called after linking (regular LTO) or loading 213 /// (ThinLTO) the module, before modifying it. 214 ModuleHookFn PreOptModuleHook; 215 216 /// This hook is called after promoting any internal functions 217 /// (ThinLTO-specific). 218 ModuleHookFn PostPromoteModuleHook; 219 220 /// This hook is called after internalizing the module. 221 ModuleHookFn PostInternalizeModuleHook; 222 223 /// This hook is called after importing from other modules (ThinLTO-specific). 224 ModuleHookFn PostImportModuleHook; 225 226 /// This module hook is called after optimization is complete. 227 ModuleHookFn PostOptModuleHook; 228 229 /// This module hook is called before code generation. It is similar to the 230 /// PostOptModuleHook, but for parallel code generation it is called after 231 /// splitting the module. 232 ModuleHookFn PreCodeGenModuleHook; 233 234 /// A combined index hook is called after all per-module indexes have been 235 /// combined (ThinLTO-specific). It can be used to implement -save-temps for 236 /// the combined index. 237 /// 238 /// If this function returns false, any further processing for ThinLTO tasks 239 /// is aborted. 240 /// 241 /// It is called regardless of whether the backend is in-process, although it 242 /// is not called from individual backend processes. 243 using CombinedIndexHookFn = std::function<bool( 244 const ModuleSummaryIndex &Index, 245 const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols)>; 246 CombinedIndexHookFn CombinedIndexHook; 247 248 /// This is a convenience function that configures this Config object to write 249 /// temporary files named after the given OutputFileName for each of the LTO 250 /// phases to disk. A client can use this function to implement -save-temps. 251 /// 252 /// FIXME: Temporary files derived from ThinLTO backends are currently named 253 /// after the input file name, rather than the output file name, when 254 /// UseInputModulePath is set to true. 255 /// 256 /// Specifically, it (1) sets each of the above module hooks and the combined 257 /// index hook to a function that calls the hook function (if any) that was 258 /// present in the appropriate field when the addSaveTemps function was 259 /// called, and writes the module to a bitcode file with a name prefixed by 260 /// the given output file name, and (2) creates a resolution file whose name 261 /// is prefixed by the given output file name and sets ResolutionFile to its 262 /// file handle. 263 Error addSaveTemps(std::string OutputFileName, 264 bool UseInputModulePath = false); 265 }; 266 267 struct LTOLLVMDiagnosticHandler : public DiagnosticHandler { 268 DiagnosticHandlerFunction *Fn; 269 LTOLLVMDiagnosticHandler(DiagnosticHandlerFunction *DiagHandlerFn) 270 : Fn(DiagHandlerFn) {} 271 bool handleDiagnostics(const DiagnosticInfo &DI) override { 272 (*Fn)(DI); 273 return true; 274 } 275 }; 276 /// A derived class of LLVMContext that initializes itself according to a given 277 /// Config object. The purpose of this class is to tie ownership of the 278 /// diagnostic handler to the context, as opposed to the Config object (which 279 /// may be ephemeral). 280 // FIXME: This should not be required as diagnostic handler is not callback. 281 struct LTOLLVMContext : LLVMContext { 282 283 LTOLLVMContext(const Config &C) : DiagHandler(C.DiagHandler) { 284 setDiscardValueNames(C.ShouldDiscardValueNames); 285 enableDebugTypeODRUniquing(); 286 setDiagnosticHandler( 287 std::make_unique<LTOLLVMDiagnosticHandler>(&DiagHandler), true); 288 } 289 DiagnosticHandlerFunction DiagHandler; 290 }; 291 292 } 293 } 294 295 #endif 296
Indexes created Mon Jun 08 00:24:58 UTC 2026