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 #include <optional> 29 30 namespace llvm { 31 32 class Error; 33 class Module; 34 class ModuleSummaryIndex; 35 class raw_pwrite_stream; 36 37 namespace lto { 38 39 /// LTO configuration. A linker can configure LTO by setting fields in this data 40 /// structure and passing it to the lto::LTO constructor. 41 struct Config { 42 enum VisScheme { 43 FromPrevailing, 44 ELF, 45 }; 46 // Note: when adding fields here, consider whether they need to be added to 47 // computeLTOCacheKey in LTO.cpp. 48 std::string CPU; 49 TargetOptions Options; 50 std::vector<std::string> MAttrs; 51 std::vector<std::string> MllvmArgs; 52 std::vector<std::string> PassPlugins; 53 /// For adding passes that run right before codegen. 54 std::function<void(legacy::PassManager &)> PreCodeGenPassesHook; 55 std::optional<Reloc::Model> RelocModel = Reloc::PIC_; 56 std::optional<CodeModel::Model> CodeModel; 57 CodeGenOpt::Level CGOptLevel = CodeGenOpt::Default; 58 CodeGenFileType CGFileType = CGFT_ObjectFile; 59 unsigned OptLevel = 2; 60 bool VerifyEach = false; 61 bool DisableVerify = false; 62 63 /// Use the standard optimization pipeline. 64 bool UseDefaultPipeline = false; 65 66 /// Flag to indicate that the optimizer should not assume builtins are present 67 /// on the target. 68 bool Freestanding = false; 69 70 /// Disable entirely the optimizer, including importing for ThinLTO 71 bool CodeGenOnly = false; 72 73 /// Run PGO context sensitive IR instrumentation. 74 bool RunCSIRInstr = false; 75 76 /// Turn on/off the warning about a hash mismatch in the PGO profile data. 77 bool PGOWarnMismatch = true; 78 79 /// Asserts whether we can assume whole program visibility during the LTO 80 /// link. 81 bool HasWholeProgramVisibility = false; 82 83 /// Always emit a Regular LTO object even when it is empty because no Regular 84 /// LTO modules were linked. This option is useful for some build system which 85 /// want to know a priori all possible output files. 86 bool AlwaysEmitRegularLTOObj = false; 87 88 /// Allows non-imported definitions to get the potentially more constraining 89 /// visibility from the prevailing definition. FromPrevailing is the default 90 /// because it works for many binary formats. ELF can use the more optimized 91 /// 'ELF' scheme. 92 VisScheme VisibilityScheme = FromPrevailing; 93 94 /// If this field is set, the set of passes run in the middle-end optimizer 95 /// will be the one specified by the string. Only works with the new pass 96 /// manager as the old one doesn't have this ability. 97 std::string OptPipeline; 98 99 // If this field is set, it has the same effect of specifying an AA pipeline 100 // identified by the string. Only works with the new pass manager, in 101 // conjunction OptPipeline. 102 std::string AAPipeline; 103 104 /// Setting this field will replace target triples in input files with this 105 /// triple. 106 std::string OverrideTriple; 107 108 /// Setting this field will replace unspecified target triples in input files 109 /// with this triple. 110 std::string DefaultTriple; 111 112 /// Context Sensitive PGO profile path. 113 std::string CSIRProfile; 114 115 /// Sample PGO profile path. 116 std::string SampleProfile; 117 118 /// Name remapping file for profile data. 119 std::string ProfileRemapping; 120 121 /// The directory to store .dwo files. 122 std::string DwoDir; 123 124 /// The name for the split debug info file used for the DW_AT_[GNU_]dwo_name 125 /// attribute in the skeleton CU. This should generally only be used when 126 /// running an individual backend directly via thinBackend(), as otherwise 127 /// all objects would use the same .dwo file. Not used as output path. 128 std::string SplitDwarfFile; 129 130 /// The path to write a .dwo file to. This should generally only be used when 131 /// running an individual backend directly via thinBackend(), as otherwise 132 /// all .dwo files will be written to the same path. Not used in skeleton CU. 133 std::string SplitDwarfOutput; 134 135 /// Optimization remarks file path. 136 std::string RemarksFilename; 137 138 /// Optimization remarks pass filter. 139 std::string RemarksPasses; 140 141 /// Whether to emit optimization remarks with hotness informations. 142 bool RemarksWithHotness = false; 143 144 /// The minimum hotness value a diagnostic needs in order to be included in 145 /// optimization diagnostics. 146 /// 147 /// The threshold is an Optional value, which maps to one of the 3 states: 148 /// 1. 0 => threshold disabled. All emarks will be printed. 149 /// 2. positive int => manual threshold by user. Remarks with hotness exceed 150 /// threshold will be printed. 151 /// 3. None => 'auto' threshold by user. The actual value is not 152 /// available at command line, but will be synced with 153 /// hotness threhold from profile summary during 154 /// compilation. 155 /// 156 /// If threshold option is not specified, it is disabled by default. 157 std::optional<uint64_t> RemarksHotnessThreshold = 0; 158 159 /// The format used for serializing remarks (default: YAML). 160 std::string RemarksFormat; 161 162 /// Whether to emit the pass manager debuggging informations. 163 bool DebugPassManager = false; 164 165 /// Statistics output file path. 166 std::string StatsFile; 167 168 /// Specific thinLTO modules to compile. 169 std::vector<std::string> ThinLTOModulesToCompile; 170 171 /// Time trace enabled. 172 bool TimeTraceEnabled = false; 173 174 /// Time trace granularity. 175 unsigned TimeTraceGranularity = 500; 176 177 bool ShouldDiscardValueNames = true; 178 DiagnosticHandlerFunction DiagHandler; 179 180 /// Add FSAFDO discriminators. 181 bool AddFSDiscriminator = false; 182 183 /// If this field is set, LTO will write input file paths and symbol 184 /// resolutions here in llvm-lto2 command line flag format. This can be 185 /// used for testing and for running the LTO pipeline outside of the linker 186 /// with llvm-lto2. 187 std::unique_ptr<raw_ostream> ResolutionFile; 188 189 /// Tunable parameters for passes in the default pipelines. 190 PipelineTuningOptions PTO; 191 192 /// The following callbacks deal with tasks, which normally represent the 193 /// entire optimization and code generation pipeline for what will become a 194 /// single native object file. Each task has a unique identifier between 0 and 195 /// getMaxTasks()-1, which is supplied to the callback via the Task parameter. 196 /// A task represents the entire pipeline for ThinLTO and regular 197 /// (non-parallel) LTO, but a parallel code generation task will be split into 198 /// N tasks before code generation, where N is the parallelism level. 199 /// 200 /// LTO may decide to stop processing a task at any time, for example if the 201 /// module is empty or if a module hook (see below) returns false. For this 202 /// reason, the client should not expect to receive exactly getMaxTasks() 203 /// native object files. 204 205 /// A module hook may be used by a linker to perform actions during the LTO 206 /// pipeline. For example, a linker may use this function to implement 207 /// -save-temps. If this function returns false, any further processing for 208 /// that task is aborted. 209 /// 210 /// Module hooks must be thread safe with respect to the linker's internal 211 /// data structures. A module hook will never be called concurrently from 212 /// multiple threads with the same task ID, or the same module. 213 /// 214 /// Note that in out-of-process backend scenarios, none of the hooks will be 215 /// called for ThinLTO tasks. 216 using ModuleHookFn = std::function<bool(unsigned Task, const Module &)>; 217 218 /// This module hook is called after linking (regular LTO) or loading 219 /// (ThinLTO) the module, before modifying it. 220 ModuleHookFn PreOptModuleHook; 221 222 /// This hook is called after promoting any internal functions 223 /// (ThinLTO-specific). 224 ModuleHookFn PostPromoteModuleHook; 225 226 /// This hook is called after internalizing the module. 227 ModuleHookFn PostInternalizeModuleHook; 228 229 /// This hook is called after importing from other modules (ThinLTO-specific). 230 ModuleHookFn PostImportModuleHook; 231 232 /// This module hook is called after optimization is complete. 233 ModuleHookFn PostOptModuleHook; 234 235 /// This module hook is called before code generation. It is similar to the 236 /// PostOptModuleHook, but for parallel code generation it is called after 237 /// splitting the module. 238 ModuleHookFn PreCodeGenModuleHook; 239 240 /// A combined index hook is called after all per-module indexes have been 241 /// combined (ThinLTO-specific). It can be used to implement -save-temps for 242 /// the combined index. 243 /// 244 /// If this function returns false, any further processing for ThinLTO tasks 245 /// is aborted. 246 /// 247 /// It is called regardless of whether the backend is in-process, although it 248 /// is not called from individual backend processes. 249 using CombinedIndexHookFn = std::function<bool( 250 const ModuleSummaryIndex &Index, 251 const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols)>; 252 CombinedIndexHookFn CombinedIndexHook; 253 254 /// This is a convenience function that configures this Config object to write 255 /// temporary files named after the given OutputFileName for each of the LTO 256 /// phases to disk. A client can use this function to implement -save-temps. 257 /// 258 /// FIXME: Temporary files derived from ThinLTO backends are currently named 259 /// after the input file name, rather than the output file name, when 260 /// UseInputModulePath is set to true. 261 /// 262 /// Specifically, it (1) sets each of the above module hooks and the combined 263 /// index hook to a function that calls the hook function (if any) that was 264 /// present in the appropriate field when the addSaveTemps function was 265 /// called, and writes the module to a bitcode file with a name prefixed by 266 /// the given output file name, and (2) creates a resolution file whose name 267 /// is prefixed by the given output file name and sets ResolutionFile to its 268 /// file handle. 269 /// 270 /// SaveTempsArgs can be specified to select which temps to save. 271 /// If SaveTempsArgs is not provided, all temps are saved. 272 Error addSaveTemps(std::string OutputFileName, 273 bool UseInputModulePath = false, 274 const DenseSet<StringRef> &SaveTempsArgs = {}); 275 }; 276 277 struct LTOLLVMDiagnosticHandler : public DiagnosticHandler { 278 DiagnosticHandlerFunction *Fn; 279 LTOLLVMDiagnosticHandler(DiagnosticHandlerFunction *DiagHandlerFn) 280 : Fn(DiagHandlerFn) {} 281 bool handleDiagnostics(const DiagnosticInfo &DI) override { 282 (*Fn)(DI); 283 return true; 284 } 285 }; 286 /// A derived class of LLVMContext that initializes itself according to a given 287 /// Config object. The purpose of this class is to tie ownership of the 288 /// diagnostic handler to the context, as opposed to the Config object (which 289 /// may be ephemeral). 290 // FIXME: This should not be required as diagnostic handler is not callback. 291 struct LTOLLVMContext : LLVMContext { 292 293 LTOLLVMContext(const Config &C) : DiagHandler(C.DiagHandler) { 294 setDiscardValueNames(C.ShouldDiscardValueNames); 295 enableDebugTypeODRUniquing(); 296 setDiagnosticHandler( 297 std::make_unique<LTOLLVMDiagnosticHandler>(&DiagHandler), true); 298 } 299 DiagnosticHandlerFunction DiagHandler; 300 }; 301 302 } 303 } 304 305 #endif 306