1 //===-LTOCodeGenerator.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 LTOCodeGenerator class. 11 // 12 // LTO compilation consists of three phases: Pre-IPO, IPO and Post-IPO. 13 // 14 // The Pre-IPO phase compiles source code into bitcode file. The resulting 15 // bitcode files, along with object files and libraries, will be fed to the 16 // linker to through the IPO and Post-IPO phases. By using obj-file extension, 17 // the resulting bitcode file disguises itself as an object file, and therefore 18 // obviates the need of writing a special set of the make-rules only for LTO 19 // compilation. 20 // 21 // The IPO phase perform inter-procedural analyses and optimizations, and 22 // the Post-IPO consists two sub-phases: intra-procedural scalar optimizations 23 // (SOPT), and intra-procedural target-dependent code generator (CG). 24 // 25 // As of this writing, we don't separate IPO and the Post-IPO SOPT. They 26 // are intermingled together, and are driven by a single pass manager (see 27 // PassManagerBuilder::populateLTOPassManager()). 28 // 29 // The "LTOCodeGenerator" is the driver for the IPO and Post-IPO stages. 30 // The "CodeGenerator" here is bit confusing. Don't confuse the "CodeGenerator" 31 // with the machine specific code generator. 32 // 33 //===----------------------------------------------------------------------===// 34 35 #ifndef LTO_CODE_GENERATOR_H 36 #define LTO_CODE_GENERATOR_H 37 38 #include "llvm-c/lto.h" 39 #include "llvm/ADT/SmallPtrSet.h" 40 #include "llvm/ADT/StringMap.h" 41 #include "llvm/Linker.h" 42 #include <string> 43 #include <vector> 44 45 namespace llvm { 46 class LLVMContext; 47 class GlobalValue; 48 class Mangler; 49 class MemoryBuffer; 50 class TargetMachine; 51 class raw_ostream; 52 } 53 54 //===----------------------------------------------------------------------===// 55 /// LTOCodeGenerator - C++ class which implements the opaque lto_code_gen_t 56 /// type. 57 /// 58 struct LTOCodeGenerator { 59 static const char *getVersionString(); 60 61 LTOCodeGenerator(); 62 ~LTOCodeGenerator(); 63 64 // Merge given module, return true on success. 65 bool addModule(struct LTOModule*, std::string &errMsg); 66 67 void setDebugInfo(lto_debug_model); 68 void setCodePICModel(lto_codegen_model); 69 70 void setCpu(const char* mCpu) { _mCpu = mCpu; } 71 72 void addMustPreserveSymbol(const char* sym) { 73 _mustPreserveSymbols[sym] = 1; 74 } 75 76 // To pass options to the driver and optimization passes. These options are 77 // not necessarily for debugging purpose (The function name is misleading). 78 // This function should be called before LTOCodeGenerator::compilexxx(), 79 // and LTOCodeGenerator::writeMergedModules(). 80 // 81 void setCodeGenDebugOptions(const char *opts); 82 83 // Write the merged module to the file specified by the given path. 84 // Return true on success. 85 bool writeMergedModules(const char *path, std::string &errMsg); 86 87 // Compile the merged module into a *single* object file; the path to object 88 // file is returned to the caller via argument "name". Return true on 89 // success. 90 // 91 // NOTE that it is up to the linker to remove the intermediate object file. 92 // Do not try to remove the object file in LTOCodeGenerator's destructor 93 // as we don't who (LTOCodeGenerator or the obj file) will last longer. 94 // 95 bool compile_to_file(const char **name, std::string &errMsg); 96 97 // As with compile_to_file(), this function compiles the merged module into 98 // single object file. Instead of returning the object-file-path to the caller 99 // (linker), it brings the object to a buffer, and return the buffer to the 100 // caller. This function should delete intermediate object file once its content 101 // is brought to memory. Return NULL is the compilation was not successful. 102 // 103 const void *compile(size_t *length, std::string &errMsg); 104 105 private: 106 void initializeLTOPasses(); 107 108 bool generateObjectFile(llvm::raw_ostream &out, std::string &errMsg); 109 void applyScopeRestrictions(); 110 void applyRestriction(llvm::GlobalValue &GV, 111 std::vector<const char*> &mustPreserveList, 112 llvm::SmallPtrSet<llvm::GlobalValue*, 8> &asmUsed, 113 llvm::Mangler &mangler); 114 bool determineTarget(std::string &errMsg); 115 116 typedef llvm::StringMap<uint8_t> StringSet; 117 118 llvm::LLVMContext& _context; 119 llvm::Linker _linker; 120 llvm::TargetMachine* _target; 121 bool _emitDwarfDebugInfo; 122 bool _scopeRestrictionsDone; 123 lto_codegen_model _codeModel; 124 StringSet _mustPreserveSymbols; 125 StringSet _asmUndefinedRefs; 126 llvm::MemoryBuffer* _nativeObjectFile; 127 std::vector<char*> _codegenOptions; 128 std::string _mCpu; 129 std::string _nativeObjectPath; 130 }; 131 132 #endif // LTO_CODE_GENERATOR_H 133
