LCOV - code coverage report
Current view: top level - include/llvm/LTO/legacy - ThinLTOCodeGenerator.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 15 15 100.0 %
Date: 2017-09-14 15:23:50 Functions: 4 4 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===-ThinLTOCodeGenerator.h - LLVM Link Time Optimizer -------------------===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // This file declares the ThinLTOCodeGenerator class, similar to the
      11             : // LTOCodeGenerator but for the ThinLTO scheme. It provides an interface for
      12             : // linker plugin.
      13             : //
      14             : //===----------------------------------------------------------------------===//
      15             : 
      16             : #ifndef LLVM_LTO_THINLTOCODEGENERATOR_H
      17             : #define LLVM_LTO_THINLTOCODEGENERATOR_H
      18             : 
      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"
      27             : 
      28             : #include <string>
      29             : 
      30             : namespace llvm {
      31             : class StringRef;
      32             : class LLVMContext;
      33             : class TargetMachine;
      34             : 
      35             : /// Wrapper around MemoryBufferRef, owning the identifier
      36         994 : class ThinLTOBuffer {
      37             :   std::string OwnedIdentifier;
      38             :   StringRef Buffer;
      39             : 
      40             : public:
      41             :   ThinLTOBuffer(StringRef Buffer, StringRef Identifier)
      42         254 :       : OwnedIdentifier(Identifier), Buffer(Buffer) {}
      43             : 
      44             :   MemoryBufferRef getMemBuffer() const {
      45             :     return MemoryBufferRef(Buffer,
      46         890 :                            {OwnedIdentifier.c_str(), OwnedIdentifier.size()});
      47             :   }
      48             :   StringRef getBuffer() const { return Buffer; }
      49         206 :   StringRef getBufferIdentifier() const { return OwnedIdentifier; }
      50             : };
      51             : 
      52             : /// Helper to gather options relevant to the target machine creation
      53         983 : struct TargetMachineBuilder {
      54             :   Triple TheTriple;
      55             :   std::string MCpu;
      56             :   std::string MAttr;
      57             :   TargetOptions Options;
      58             :   Optional<Reloc::Model> RelocModel;
      59             :   CodeGenOpt::Level CGOptLevel = CodeGenOpt::Aggressive;
      60             : 
      61             :   std::unique_ptr<TargetMachine> create() const;
      62             : };
      63             : 
      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
      69             : /// codegenerator.
      70        1347 : class ThinLTOCodeGenerator {
      71             : public:
      72             :   /// Add given module to the code generator.
      73             :   void addModule(StringRef Identifier, StringRef Data);
      74             : 
      75             :   /**
      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.
      79             :    */
      80             :   void preserveSymbol(StringRef Name);
      81             : 
      82             :   /**
      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.
      87             :    */
      88             :   void crossReferenceSymbol(StringRef Name);
      89             : 
      90             :   /**
      91             :    * Process all the modules that were added to the code generator in parallel.
      92             :    *
      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().
      96             :    */
      97             :   void run();
      98             : 
      99             :   /**
     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().
     104             :    */
     105             :   std::vector<std::unique_ptr<MemoryBuffer>> &getProducedBinaries() {
     106           2 :     return ProducedBinaries;
     107             :   }
     108             : 
     109             :   /**
     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().
     113             :    */
     114             :   std::vector<std::string> &getProducedBinaryFiles() {
     115             :     return ProducedBinaryFiles;
     116             :   }
     117             : 
     118             :   /**
     119             :    * \defgroup Options setters
     120             :    * @{
     121             :    */
     122             : 
     123             :   /**
     124             :    * \defgroup Cache controlling options
     125             :    *
     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.
     139             :    * @{
     140             :    */
     141             : 
     142         449 :   struct CachingOptions {
     143             :     std::string Path;                    // Path to the cache, empty to disable.
     144             :     CachePruningPolicy Policy;
     145             :   };
     146             : 
     147             :   /// Provide a path to a directory where to store the cached files for
     148             :   /// incremental build.
     149          91 :   void setCacheDir(std::string Path) { CacheOptions.Path = std::move(Path); }
     150             : 
     151             :   /// Cache policy: interval (seconds) between two prune of the cache. Set to a
     152             :   /// negative value (default) to disable pruning. A value of 0 will be ignored.
     153             :   void setCachePruningInterval(int Interval) {
     154             :     if (Interval)
     155             :       CacheOptions.Policy.Interval = std::chrono::seconds(Interval);
     156             :   }
     157             : 
     158             :   /// Cache policy: expiration (in seconds) for an entry.
     159             :   /// A value of 0 will be ignored.
     160             :   void setCacheEntryExpiration(unsigned Expiration) {
     161             :     if (Expiration)
     162             :       CacheOptions.Policy.Expiration = std::chrono::seconds(Expiration);
     163             :   }
     164             : 
     165             :   /**
     166             :    * Sets the maximum cache size that can be persistent across build, in terms
     167             :    * of percentage of the available space on the the disk. Set to 100 to
     168             :    * indicate no limit, 50 to indicate that the cache size will not be left over
     169             :    * half the available space. A value over 100 will be reduced to 100, and a
     170             :    * value of 0 will be ignored.
     171             :    *
     172             :    *
     173             :    * The formula looks like:
     174             :    *  AvailableSpace = FreeSpace + ExistingCacheSize
     175             :    *  NewCacheSize = AvailableSpace * P/100
     176             :    *
     177             :    */
     178             :   void setMaxCacheSizeRelativeToAvailableSpace(unsigned Percentage) {
     179             :     if (Percentage)
     180             :       CacheOptions.Policy.MaxSizePercentageOfAvailableSpace = Percentage;
     181             :   }
     182             : 
     183             :   /**@}*/
     184             : 
     185             :   /// Set the path to a directory where to save temporaries at various stages of
     186             :   /// the processing.
     187           1 :   void setSaveTempsDir(std::string Path) { SaveTempsDir = std::move(Path); }
     188             : 
     189             :   /// Set the path to a directory where to save generated object files. This
     190             :   /// path can be used by a linker to request on-disk files instead of in-memory
     191             :   /// buffers. When set, results are available through getProducedBinaryFiles()
     192             :   /// instead of getProducedBinaries().
     193             :   void setGeneratedObjectsDirectory(std::string Path) {
     194           3 :     SavedObjectsDirectoryPath = std::move(Path);
     195             :   }
     196             : 
     197             :   /// CPU to use to initialize the TargetMachine
     198             :   void setCpu(std::string Cpu) { TMBuilder.MCpu = std::move(Cpu); }
     199             : 
     200             :   /// Subtarget attributes
     201             :   void setAttr(std::string MAttr) { TMBuilder.MAttr = std::move(MAttr); }
     202             : 
     203             :   /// TargetMachine options
     204             :   void setTargetOptions(TargetOptions Options) {
     205          91 :     TMBuilder.Options = std::move(Options);
     206             :   }
     207             : 
     208             :   /// Enable the Freestanding mode: indicate that the optimizer should not
     209             :   /// assume builtins are present on the target.
     210          91 :   void setFreestanding(bool Enabled) { Freestanding = Enabled; }
     211             : 
     212             :   /// CodeModel
     213             :   void setCodePICModel(Optional<Reloc::Model> Model) {
     214         182 :     TMBuilder.RelocModel = Model;
     215             :   }
     216             : 
     217             :   /// CodeGen optimization level
     218             :   void setCodeGenOptLevel(CodeGenOpt::Level CGOptLevel) {
     219             :     TMBuilder.CGOptLevel = CGOptLevel;
     220             :   }
     221             : 
     222             :   /// IR optimization level: from 0 to 3.
     223             :   void setOptLevel(unsigned NewOptLevel) {
     224             :     OptLevel = (NewOptLevel > 3) ? 3 : NewOptLevel;
     225             :   }
     226             : 
     227             :   /// Disable CodeGen, only run the stages till codegen and stop. The output
     228             :   /// will be bitcode.
     229             :   void disableCodeGen(bool Disable) { DisableCodeGen = Disable; }
     230             : 
     231             :   /// Perform CodeGen only: disable all other stages.
     232           3 :   void setCodeGenOnly(bool CGOnly) { CodeGenOnly = CGOnly; }
     233             : 
     234             :   /**@}*/
     235             : 
     236             :   /**
     237             :    * \defgroup Set of APIs to run individual stages in isolation.
     238             :    * @{
     239             :    */
     240             : 
     241             :   /**
     242             :    * Produce the combined summary index from all the bitcode files:
     243             :    * "thin-link".
     244             :    */
     245             :   std::unique_ptr<ModuleSummaryIndex> linkCombinedIndex();
     246             : 
     247             :   /**
     248             :    * Perform promotion and renaming of exported internal functions,
     249             :    * and additionally resolve weak and linkonce symbols.
     250             :    * Index is updated to reflect linkage changes from weak resolution.
     251             :    */
     252             :   void promote(Module &Module, ModuleSummaryIndex &Index);
     253             : 
     254             :   /**
     255             :    * Compute and emit the imported files for module at \p ModulePath.
     256             :    */
     257             :   static void emitImports(StringRef ModulePath, StringRef OutputName,
     258             :                           ModuleSummaryIndex &Index);
     259             : 
     260             :   /**
     261             :    * Perform cross-module importing for the module identified by
     262             :    * ModuleIdentifier.
     263             :    */
     264             :   void crossModuleImport(Module &Module, ModuleSummaryIndex &Index);
     265             : 
     266             :   /**
     267             :    * Compute the list of summaries needed for importing into module.
     268             :    */
     269             :   static void gatherImportedSummariesForModule(
     270             :       StringRef ModulePath, ModuleSummaryIndex &Index,
     271             :       std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex);
     272             : 
     273             :   /**
     274             :    * Perform internalization. Index is updated to reflect linkage changes.
     275             :    */
     276             :   void internalize(Module &Module, ModuleSummaryIndex &Index);
     277             : 
     278             :   /**
     279             :    * Perform post-importing ThinLTO optimizations.
     280             :    */
     281             :   void optimize(Module &Module);
     282             : 
     283             :   /**
     284             :    * Perform ThinLTO CodeGen.
     285             :    */
     286             :   std::unique_ptr<MemoryBuffer> codegen(Module &Module);
     287             : 
     288             :   /**@}*/
     289             : 
     290             : private:
     291             :   /// Helper factory to build a TargetMachine
     292             :   TargetMachineBuilder TMBuilder;
     293             : 
     294             :   /// Vector holding the in-memory buffer containing the produced binaries, when
     295             :   /// SavedObjectsDirectoryPath isn't set.
     296             :   std::vector<std::unique_ptr<MemoryBuffer>> ProducedBinaries;
     297             : 
     298             :   /// Path to generated files in the supplied SavedObjectsDirectoryPath if any.
     299             :   std::vector<std::string> ProducedBinaryFiles;
     300             : 
     301             :   /// Vector holding the input buffers containing the bitcode modules to
     302             :   /// process.
     303             :   std::vector<ThinLTOBuffer> Modules;
     304             : 
     305             :   /// Set of symbols that need to be preserved outside of the set of bitcode
     306             :   /// files.
     307             :   StringSet<> PreservedSymbols;
     308             : 
     309             :   /// Set of symbols that are cross-referenced between bitcode files.
     310             :   StringSet<> CrossReferencedSymbols;
     311             : 
     312             :   /// Control the caching behavior.
     313             :   CachingOptions CacheOptions;
     314             : 
     315             :   /// Path to a directory to save the temporary bitcode files.
     316             :   std::string SaveTempsDir;
     317             : 
     318             :   /// Path to a directory to save the generated object files.
     319             :   std::string SavedObjectsDirectoryPath;
     320             : 
     321             :   /// Flag to enable/disable CodeGen. When set to true, the process stops after
     322             :   /// optimizations and a bitcode is produced.
     323             :   bool DisableCodeGen = false;
     324             : 
     325             :   /// Flag to indicate that only the CodeGen will be performed, no cross-module
     326             :   /// importing or optimization.
     327             :   bool CodeGenOnly = false;
     328             : 
     329             :   /// Flag to indicate that the optimizer should not assume builtins are present
     330             :   /// on the target.
     331             :   bool Freestanding = false;
     332             : 
     333             :   /// IR Optimization Level [0-3].
     334             :   unsigned OptLevel = 3;
     335             : };
     336             : }
     337             : #endif

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