1 //===-ThinLTOCodeGenerator.h - LLVM Link Time Optimizer -------------------===//
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 // This file declares the ThinLTOCodeGenerator class, similar to the
11 // LTOCodeGenerator but for the ThinLTO scheme. It provides an interface for
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_LTO_THINLTOCODEGENERATOR_H
17 #define LLVM_LTO_THINLTOCODEGENERATOR_H
19 #include "llvm-c/lto.h"
20 #include "llvm/ADT/StringSet.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/IR/ModuleSummaryIndex.h"
23 #include "llvm/Support/CachePruning.h"
24 #include "llvm/Support/CodeGen.h"
25 #include "llvm/Support/MemoryBuffer.h"
26 #include "llvm/Target/TargetOptions.h"
35 /// Wrapper around MemoryBufferRef, owning the identifier
37 std::string OwnedIdentifier;
41 ThinLTOBuffer(StringRef Buffer, StringRef Identifier)
42 : OwnedIdentifier(Identifier), Buffer(Buffer) {}
44 MemoryBufferRef getMemBuffer() const {
45 return MemoryBufferRef(Buffer,
46 {OwnedIdentifier.c_str(), OwnedIdentifier.size()});
48 StringRef getBuffer() const { return Buffer; }
49 StringRef getBufferIdentifier() const { return OwnedIdentifier; }
52 /// Helper to gather options relevant to the target machine creation
53 struct TargetMachineBuilder {
57 TargetOptions Options;
58 Optional<Reloc::Model> RelocModel;
59 CodeGenOpt::Level CGOptLevel = CodeGenOpt::Aggressive;
61 std::unique_ptr<TargetMachine> create() const;
64 /// This class define an interface similar to the LTOCodeGenerator, but adapted
65 /// for ThinLTO processing.
66 /// The ThinLTOCodeGenerator is not intended to be reuse for multiple
67 /// compilation: the model is that the client adds modules to the generator and
68 /// ask to perform the ThinLTO optimizations / codegen, and finally destroys the
70 class ThinLTOCodeGenerator {
72 /// Add given module to the code generator.
73 void addModule(StringRef Identifier, StringRef Data);
76 * Adds to a list of all global symbols that must exist in the final generated
77 * code. If a symbol is not listed there, it will be optimized away if it is
78 * inlined into every usage.
80 void preserveSymbol(StringRef Name);
83 * Adds to a list of all global symbols that are cross-referenced between
84 * ThinLTO files. If the ThinLTO CodeGenerator can ensure that every
85 * references from a ThinLTO module to this symbol is optimized away, then
86 * the symbol can be discarded.
88 void crossReferenceSymbol(StringRef Name);
91 * Process all the modules that were added to the code generator in parallel.
93 * Client can access the resulting object files using getProducedBinaries(),
94 * unless setGeneratedObjectsDirectory() has been called, in which case
95 * results are available through getProducedBinaryFiles().
100 * Return the "in memory" binaries produced by the code generator. This is
101 * filled after run() unless setGeneratedObjectsDirectory() has been
102 * called, in which case results are available through
103 * getProducedBinaryFiles().
105 std::vector<std::unique_ptr<MemoryBuffer>> &getProducedBinaries() {
106 return ProducedBinaries;
110 * Return the "on-disk" binaries produced by the code generator. This is
111 * filled after run() when setGeneratedObjectsDirectory() has been
112 * called, in which case results are available through getProducedBinaries().
114 std::vector<std::string> &getProducedBinaryFiles() {
115 return ProducedBinaryFiles;
119 * \defgroup Options setters
124 * \defgroup Cache controlling options
126 * These entry points control the ThinLTO cache. The cache is intended to
127 * support incremental build, and thus needs to be persistent accross build.
128 * The client enabled the cache by supplying a path to an existing directory.
129 * The code generator will use this to store objects files that may be reused
130 * during a subsequent build.
131 * To avoid filling the disk space, a few knobs are provided:
132 * - The pruning interval limit the frequency at which the garbage collector
133 * will try to scan the cache directory to prune it from expired entries.
134 * Setting to -1 disable the pruning (default).
135 * - The pruning expiration time indicates to the garbage collector how old
136 * an entry needs to be to be removed.
137 * - Finally, the garbage collector can be instructed to prune the cache till
138 * the occupied space goes below a threshold.
142 struct CachingOptions {
143 std::string Path; // Path to the cache, empty to disable.
144 CachePruningPolicy Policy;
147 /// Provide a path to a directory where to store the cached files for
148 /// incremental build.
149 void setCacheDir(std::string Path) { CacheOptions.Path = std::move(Path); }
151 /// Cache policy: interval (seconds) between two prunes of the cache. Set to a
152 /// negative value to disable pruning. A value of 0 will be ignored.
153 void setCachePruningInterval(int Interval) {
157 CacheOptions.Policy.Interval.reset();
159 CacheOptions.Policy.Interval = std::chrono::seconds(Interval);
162 /// Cache policy: expiration (in seconds) for an entry.
163 /// A value of 0 will be ignored.
164 void setCacheEntryExpiration(unsigned Expiration) {
166 CacheOptions.Policy.Expiration = std::chrono::seconds(Expiration);
170 * Sets the maximum cache size that can be persistent across build, in terms
171 * of percentage of the available space on the the disk. Set to 100 to
172 * indicate no limit, 50 to indicate that the cache size will not be left over
173 * half the available space. A value over 100 will be reduced to 100, and a
174 * value of 0 will be ignored.
177 * The formula looks like:
178 * AvailableSpace = FreeSpace + ExistingCacheSize
179 * NewCacheSize = AvailableSpace * P/100
182 void setMaxCacheSizeRelativeToAvailableSpace(unsigned Percentage) {
184 CacheOptions.Policy.MaxSizePercentageOfAvailableSpace = Percentage;
189 /// Set the path to a directory where to save temporaries at various stages of
191 void setSaveTempsDir(std::string Path) { SaveTempsDir = std::move(Path); }
193 /// Set the path to a directory where to save generated object files. This
194 /// path can be used by a linker to request on-disk files instead of in-memory
195 /// buffers. When set, results are available through getProducedBinaryFiles()
196 /// instead of getProducedBinaries().
197 void setGeneratedObjectsDirectory(std::string Path) {
198 SavedObjectsDirectoryPath = std::move(Path);
201 /// CPU to use to initialize the TargetMachine
202 void setCpu(std::string Cpu) { TMBuilder.MCpu = std::move(Cpu); }
204 /// Subtarget attributes
205 void setAttr(std::string MAttr) { TMBuilder.MAttr = std::move(MAttr); }
207 /// TargetMachine options
208 void setTargetOptions(TargetOptions Options) {
209 TMBuilder.Options = std::move(Options);
212 /// Enable the Freestanding mode: indicate that the optimizer should not
213 /// assume builtins are present on the target.
214 void setFreestanding(bool Enabled) { Freestanding = Enabled; }
217 void setCodePICModel(Optional<Reloc::Model> Model) {
218 TMBuilder.RelocModel = Model;
221 /// CodeGen optimization level
222 void setCodeGenOptLevel(CodeGenOpt::Level CGOptLevel) {
223 TMBuilder.CGOptLevel = CGOptLevel;
226 /// IR optimization level: from 0 to 3.
227 void setOptLevel(unsigned NewOptLevel) {
228 OptLevel = (NewOptLevel > 3) ? 3 : NewOptLevel;
231 /// Disable CodeGen, only run the stages till codegen and stop. The output
233 void disableCodeGen(bool Disable) { DisableCodeGen = Disable; }
235 /// Perform CodeGen only: disable all other stages.
236 void setCodeGenOnly(bool CGOnly) { CodeGenOnly = CGOnly; }
241 * \defgroup Set of APIs to run individual stages in isolation.
246 * Produce the combined summary index from all the bitcode files:
249 std::unique_ptr<ModuleSummaryIndex> linkCombinedIndex();
252 * Perform promotion and renaming of exported internal functions,
253 * and additionally resolve weak and linkonce symbols.
254 * Index is updated to reflect linkage changes from weak resolution.
256 void promote(Module &Module, ModuleSummaryIndex &Index);
259 * Compute and emit the imported files for module at \p ModulePath.
261 static void emitImports(StringRef ModulePath, StringRef OutputName,
262 ModuleSummaryIndex &Index);
265 * Perform cross-module importing for the module identified by
268 void crossModuleImport(Module &Module, ModuleSummaryIndex &Index);
271 * Compute the list of summaries needed for importing into module.
273 static void gatherImportedSummariesForModule(
274 StringRef ModulePath, ModuleSummaryIndex &Index,
275 std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex);
278 * Perform internalization. Index is updated to reflect linkage changes.
280 void internalize(Module &Module, ModuleSummaryIndex &Index);
283 * Perform post-importing ThinLTO optimizations.
285 void optimize(Module &Module);
288 * Perform ThinLTO CodeGen.
290 std::unique_ptr<MemoryBuffer> codegen(Module &Module);
295 /// Helper factory to build a TargetMachine
296 TargetMachineBuilder TMBuilder;
298 /// Vector holding the in-memory buffer containing the produced binaries, when
299 /// SavedObjectsDirectoryPath isn't set.
300 std::vector<std::unique_ptr<MemoryBuffer>> ProducedBinaries;
302 /// Path to generated files in the supplied SavedObjectsDirectoryPath if any.
303 std::vector<std::string> ProducedBinaryFiles;
305 /// Vector holding the input buffers containing the bitcode modules to
307 std::vector<ThinLTOBuffer> Modules;
309 /// Set of symbols that need to be preserved outside of the set of bitcode
311 StringSet<> PreservedSymbols;
313 /// Set of symbols that are cross-referenced between bitcode files.
314 StringSet<> CrossReferencedSymbols;
316 /// Control the caching behavior.
317 CachingOptions CacheOptions;
319 /// Path to a directory to save the temporary bitcode files.
320 std::string SaveTempsDir;
322 /// Path to a directory to save the generated object files.
323 std::string SavedObjectsDirectoryPath;
325 /// Flag to enable/disable CodeGen. When set to true, the process stops after
326 /// optimizations and a bitcode is produced.
327 bool DisableCodeGen = false;
329 /// Flag to indicate that only the CodeGen will be performed, no cross-module
330 /// importing or optimization.
331 bool CodeGenOnly = false;
333 /// Flag to indicate that the optimizer should not assume builtins are present
335 bool Freestanding = false;
337 /// IR Optimization Level [0-3].
338 unsigned OptLevel = 3;