include/llvm/LTO/legacy/LTOCodeGenerator.h

   1 //===-LTOCodeGenerator.h - LLVM Link Time Optimizer -----------------------===//
   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 declares the LTOCodeGenerator class.
  10 //
  11 //   LTO compilation consists of three phases: Pre-IPO, IPO and Post-IPO.
  12 //
  13 //   The Pre-IPO phase compiles source code into bitcode file. The resulting
  14 // bitcode files, along with object files and libraries, will be fed to the
  15 // linker to through the IPO and Post-IPO phases. By using obj-file extension,
  16 // the resulting bitcode file disguises itself as an object file, and therefore
  17 // obviates the need of writing a special set of the make-rules only for LTO
  18 // compilation.
  19 //
  20 //   The IPO phase perform inter-procedural analyses and optimizations, and
  21 // the Post-IPO consists two sub-phases: intra-procedural scalar optimizations
  22 // (SOPT), and intra-procedural target-dependent code generator (CG).
  23 //
  24 //   As of this writing, we don't separate IPO and the Post-IPO SOPT. They
  25 // are intermingled together, and are driven by a single pass manager (see
  26 // PassManagerBuilder::populateLTOPassManager()).
  27 //
  28 //   The "LTOCodeGenerator" is the driver for the IPO and Post-IPO stages.
  29 // The "CodeGenerator" here is bit confusing. Don't confuse the "CodeGenerator"
  30 // with the machine specific code generator.
  31 //
  32 //===----------------------------------------------------------------------===//
  33
  34 #ifndef LLVM_LTO_LTOCODEGENERATOR_H
  35 #define LLVM_LTO_LTOCODEGENERATOR_H
  36
  37 #include "llvm-c/lto.h"
  38 #include "llvm/ADT/SmallPtrSet.h"
  39 #include "llvm/ADT/StringMap.h"
  40 #include "llvm/ADT/StringSet.h"
  41 #include "llvm/IR/GlobalValue.h"
  42 #include "llvm/IR/Module.h"
  43 #include "llvm/Support/Error.h"
  44 #include "llvm/Support/ToolOutputFile.h"
  45 #include "llvm/Target/TargetMachine.h"
  46 #include "llvm/Target/TargetOptions.h"
  47 #include <string>
  48 #include <vector>
  49
  50 /// Enable global value internalization in LTO.
  51 extern llvm::cl::opt<bool> EnableLTOInternalization;
  52
  53 namespace llvm {
  54 template <typename T> class ArrayRef;
  55   class LLVMContext;
  56   class DiagnosticInfo;
  57   class Linker;
  58   class Mangler;
  59   class MemoryBuffer;
  60   class TargetLibraryInfo;
  61   class TargetMachine;
  62   class raw_ostream;
  63   class raw_pwrite_stream;
  64
  65 //===----------------------------------------------------------------------===//
  66 /// C++ class which implements the opaque lto_code_gen_t type.
  67 ///
  68 struct LTOCodeGenerator {
  69   static const char *getVersionString();
  70
  71   LTOCodeGenerator(LLVMContext &Context);
  72   ~LTOCodeGenerator();
  73
  74   /// Merge given module.  Return true on success.
  75   ///
  76   /// Resets \a HasVerifiedInput.
  77   bool addModule(struct LTOModule *);
  78
  79   /// Set the destination module.
  80   ///
  81   /// Resets \a HasVerifiedInput.
  82   void setModule(std::unique_ptr<LTOModule> M);
  83
  84   void setAsmUndefinedRefs(struct LTOModule *);
  85   void setTargetOptions(const TargetOptions &Options);
  86   void setDebugInfo(lto_debug_model);
  87   void setCodePICModel(Optional<Reloc::Model> Model) { RelocModel = Model; }
  88
  89   /// Set the file type to be emitted (assembly or object code).
  90   /// The default is TargetMachine::CGFT_ObjectFile.
  91   void setFileType(TargetMachine::CodeGenFileType FT) { FileType = FT; }
  92
  93   void setCpu(StringRef MCpu) { this->MCpu = MCpu; }
  94   void setAttr(StringRef MAttr) { this->MAttr = MAttr; }
  95   void setOptLevel(unsigned OptLevel);
  96
  97   void setShouldInternalize(bool Value) { ShouldInternalize = Value; }
  98   void setShouldEmbedUselists(bool Value) { ShouldEmbedUselists = Value; }
  99
 100   /// Restore linkage of globals
 101   ///
 102   /// When set, the linkage of globals will be restored prior to code
 103   /// generation. That is, a global symbol that had external linkage prior to
 104   /// LTO will be emitted with external linkage again; and a local will remain
 105   /// local. Note that this option only affects the end result - globals may
 106   /// still be internalized in the process of LTO and may be modified and/or
 107   /// deleted where legal.
 108   ///
 109   /// The default behavior will internalize globals (unless on the preserve
 110   /// list) and, if parallel code generation is enabled, will externalize
 111   /// all locals.
 112   void setShouldRestoreGlobalsLinkage(bool Value) {
 113     ShouldRestoreGlobalsLinkage = Value;
 114   }
 115
 116   void addMustPreserveSymbol(StringRef Sym) { MustPreserveSymbols.insert(Sym); }
 117
 118   /// Pass options to the driver and optimization passes.
 119   ///
 120   /// These options are not necessarily for debugging purpose (the function
 121   /// name is misleading).  This function should be called before
 122   /// LTOCodeGenerator::compilexxx(), and
 123   /// LTOCodeGenerator::writeMergedModules().
 124   void setCodeGenDebugOptions(StringRef Opts);
 125
 126   /// Parse the options set in setCodeGenDebugOptions.
 127   ///
 128   /// Like \a setCodeGenDebugOptions(), this must be called before
 129   /// LTOCodeGenerator::compilexxx() and
 130   /// LTOCodeGenerator::writeMergedModules().
 131   void parseCodeGenDebugOptions();
 132
 133   /// Write the merged module to the file specified by the given path.  Return
 134   /// true on success.
 135   ///
 136   /// Calls \a verifyMergedModuleOnce().
 137   bool writeMergedModules(StringRef Path);
 138
 139   /// Compile the merged module into a *single* output file; the path to output
 140   /// file is returned to the caller via argument "name". Return true on
 141   /// success.
 142   ///
 143   /// \note It is up to the linker to remove the intermediate output file.  Do
 144   /// not try to remove the object file in LTOCodeGenerator's destructor as we
 145   /// don't who (LTOCodeGenerator or the output file) will last longer.
 146   bool compile_to_file(const char **Name, bool DisableVerify,
 147                        bool DisableInline, bool DisableGVNLoadPRE,
 148                        bool DisableVectorization);
 149
 150   /// As with compile_to_file(), this function compiles the merged module into
 151   /// single output file. Instead of returning the output file path to the
 152   /// caller (linker), it brings the output to a buffer, and returns the buffer
 153   /// to the caller. This function should delete the intermediate file once
 154   /// its content is brought to memory. Return NULL if the compilation was not
 155   /// successful.
 156   std::unique_ptr<MemoryBuffer> compile(bool DisableVerify, bool DisableInline,
 157                                         bool DisableGVNLoadPRE,
 158                                         bool DisableVectorization);
 159
 160   /// Optimizes the merged module.  Returns true on success.
 161   ///
 162   /// Calls \a verifyMergedModuleOnce().
 163   bool optimize(bool DisableVerify, bool DisableInline, bool DisableGVNLoadPRE,
 164                 bool DisableVectorization);
 165
 166   /// Compiles the merged optimized module into a single output file. It brings
 167   /// the output to a buffer, and returns the buffer to the caller. Return NULL
 168   /// if the compilation was not successful.
 169   std::unique_ptr<MemoryBuffer> compileOptimized();
 170
 171   /// Compile the merged optimized module into out.size() output files each
 172   /// representing a linkable partition of the module. If out contains more
 173   /// than one element, code generation is done in parallel with out.size()
 174   /// threads.  Output files will be written to members of out. Returns true on
 175   /// success.
 176   ///
 177   /// Calls \a verifyMergedModuleOnce().
 178   bool compileOptimized(ArrayRef<raw_pwrite_stream *> Out);
 179
 180   /// Enable the Freestanding mode: indicate that the optimizer should not
 181   /// assume builtins are present on the target.
 182   void setFreestanding(bool Enabled) { Freestanding = Enabled; }
 183
 184   void setDiagnosticHandler(lto_diagnostic_handler_t, void *);
 185
 186   LLVMContext &getContext() { return Context; }
 187
 188   void resetMergedModule() { MergedModule.reset(); }
 189   void DiagnosticHandler(const DiagnosticInfo &DI);
 190
 191 private:
 192   void initializeLTOPasses();
 193
 194   /// Verify the merged module on first call.
 195   ///
 196   /// Sets \a HasVerifiedInput on first call and doesn't run again on the same
 197   /// input.
 198   void verifyMergedModuleOnce();
 199
 200   bool compileOptimizedToFile(const char **Name);
 201   void restoreLinkageForExternals();
 202   void applyScopeRestrictions();
 203   void preserveDiscardableGVs(
 204       Module &TheModule,
 205       llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV);
 206
 207   bool determineTarget();
 208   std::unique_ptr<TargetMachine> createTargetMachine();
 209
 210   void emitError(const std::string &ErrMsg);
 211   void emitWarning(const std::string &ErrMsg);
 212
 213   void finishOptimizationRemarks();
 214
 215   LLVMContext &Context;
 216   std::unique_ptr<Module> MergedModule;
 217   std::unique_ptr<Linker> TheLinker;
 218   std::unique_ptr<TargetMachine> TargetMach;
 219   bool EmitDwarfDebugInfo = false;
 220   bool ScopeRestrictionsDone = false;
 221   bool HasVerifiedInput = false;
 222   Optional<Reloc::Model> RelocModel;
 223   StringSet<> MustPreserveSymbols;
 224   StringSet<> AsmUndefinedRefs;
 225   StringMap<GlobalValue::LinkageTypes> ExternalSymbols;
 226   std::vector<std::string> CodegenOptions;
 227   std::string FeatureStr;
 228   std::string MCpu;
 229   std::string MAttr;
 230   std::string NativeObjectPath;
 231   TargetOptions Options;
 232   CodeGenOpt::Level CGOptLevel = CodeGenOpt::Default;
 233   const Target *MArch = nullptr;
 234   std::string TripleStr;
 235   unsigned OptLevel = 2;
 236   lto_diagnostic_handler_t DiagHandler = nullptr;
 237   void *DiagContext = nullptr;
 238   bool ShouldInternalize = EnableLTOInternalization;
 239   bool ShouldEmbedUselists = false;
 240   bool ShouldRestoreGlobalsLinkage = false;
 241   TargetMachine::CodeGenFileType FileType = TargetMachine::CGFT_ObjectFile;
 242   std::unique_ptr<ToolOutputFile> DiagnosticOutputFile;
 243   bool Freestanding = false;
 244   std::unique_ptr<ToolOutputFile> StatsFile = nullptr;
 245 };
 246 }
 247 #endif