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/ADT/ArrayRef.h" 42 #include "llvm/Linker.h" 43 #include "llvm/Target/TargetOptions.h" 44 #include <string> 45 #include <vector> 46 47 namespace llvm { 48 class LLVMContext; 49 class GlobalValue; 50 class Mangler; 51 class MemoryBuffer; 52 class TargetLibraryInfo; 53 class TargetMachine; 54 class raw_ostream; 55 } 56 57 //===----------------------------------------------------------------------===// 58 /// LTOCodeGenerator - C++ class which implements the opaque lto_code_gen_t 59 /// type. 60 /// 61 struct LTOCodeGenerator { 62 static const char *getVersionString(); 63 64 LTOCodeGenerator(); 65 ~LTOCodeGenerator(); 66 67 // Merge given module, return true on success. 68 bool addModule(struct LTOModule*, std::string &errMsg); 69 70 void setTargetOptions(llvm::TargetOptions options); 71 void setDebugInfo(lto_debug_model); 72 void setCodePICModel(lto_codegen_model); 73 74 void setCpu(const char *mCpu) { MCpu = mCpu; } 75 76 void addMustPreserveSymbol(const char *sym) { MustPreserveSymbols[sym] = 1; } 77 78 // To pass options to the driver and optimization passes. These options are 79 // not necessarily for debugging purpose (The function name is misleading). 80 // This function should be called before LTOCodeGenerator::compilexxx(), 81 // and LTOCodeGenerator::writeMergedModules(). 82 // 83 void setCodeGenDebugOptions(const char *opts); 84 85 // Parse the options set in setCodeGenDebugOptions. Like 86 // setCodeGenDebugOptions, this must be called before 87 // LTOCodeGenerator::compilexxx() and LTOCodeGenerator::writeMergedModules() 88 void parseCodeGenDebugOptions(); 89 90 // Write the merged module to the file specified by the given path. 91 // Return true on success. 92 bool writeMergedModules(const char *path, std::string &errMsg); 93 94 // Compile the merged module into a *single* object file; the path to object 95 // file is returned to the caller via argument "name". Return true on 96 // success. 97 // 98 // NOTE that it is up to the linker to remove the intermediate object file. 99 // Do not try to remove the object file in LTOCodeGenerator's destructor 100 // as we don't who (LTOCodeGenerator or the obj file) will last longer. 101 // 102 bool compile_to_file(const char **name, 103 bool disableOpt, 104 bool disableInline, 105 bool disableGVNLoadPRE, 106 std::string &errMsg); 107 108 // As with compile_to_file(), this function compiles the merged module into 109 // single object file. Instead of returning the object-file-path to the caller 110 // (linker), it brings the object to a buffer, and return the buffer to the 111 // caller. This function should delete intermediate object file once its content 112 // is brought to memory. Return NULL if the compilation was not successful. 113 // 114 const void *compile(size_t *length, 115 bool disableOpt, 116 bool disableInline, 117 bool disableGVNLoadPRE, 118 std::string &errMsg); 119 120 private: 121 void initializeLTOPasses(); 122 123 bool generateObjectFile(llvm::raw_ostream &out, 124 bool disableOpt, 125 bool disableInline, 126 bool disableGVNLoadPRE, 127 std::string &errMsg); 128 void applyScopeRestrictions(); 129 void applyRestriction(llvm::GlobalValue &GV, 130 const llvm::ArrayRef<llvm::StringRef> &Libcalls, 131 std::vector<const char*> &MustPreserveList, 132 llvm::SmallPtrSet<llvm::GlobalValue*, 8> &AsmUsed, 133 llvm::Mangler &Mangler); 134 bool determineTarget(std::string &errMsg); 135 136 typedef llvm::StringMap<uint8_t> StringSet; 137 138 llvm::LLVMContext &Context; 139 llvm::Linker Linker; 140 llvm::TargetMachine *TargetMach; 141 bool EmitDwarfDebugInfo; 142 bool ScopeRestrictionsDone; 143 lto_codegen_model CodeModel; 144 StringSet MustPreserveSymbols; 145 StringSet AsmUndefinedRefs; 146 llvm::MemoryBuffer *NativeObjectFile; 147 std::vector<char *> CodegenOptions; 148 std::string MCpu; 149 std::string NativeObjectPath; 150 llvm::TargetOptions Options; 151 }; 152 153 #endif // LTO_CODE_GENERATOR_H 154