1 //===-LTOCodeGenerator.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 LTOCodeGenerator class.
12 // LTO compilation consists of three phases: Pre-IPO, IPO and Post-IPO.
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
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).
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()).
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.
33 //===----------------------------------------------------------------------===//
35 #ifndef LTO_CODE_GENERATOR_H
36 #define LTO_CODE_GENERATOR_H
38 #include "llvm-c/lto.h"
39 #include "llvm/ADT/SmallPtrSet.h"
40 #include "llvm/ADT/StringMap.h"
41 #include "llvm/Linker.h"
44 #include "LTOPartition.h"
55 //===----------------------------------------------------------------------===//
56 /// LTOCodeGenerator - C++ class which implements the opaque lto_code_gen_t
59 struct LTOCodeGenerator {
60 static const char *getVersionString();
65 // Merge given module, return true on success.
66 bool addModule(struct LTOModule*, std::string &errMsg);
68 void setDebugInfo(lto_debug_model);
69 void setCodePICModel(lto_codegen_model);
71 void setCpu(const char* mCpu) { _mCpu = mCpu; }
73 void addMustPreserveSymbol(const char* sym) {
74 _mustPreserveSymbols[sym] = 1;
77 // To pass options to the driver and optimization passes. These options are
78 // not necessarily for debugging purpose (The function name is misleading).
79 // This function should be called before LTOCodeGenerator::compilexxx(),
80 // and LTOCodeGenerator::writeMergedModules().
82 void setCodeGenDebugOptions(const char *opts);
84 // Write the merged module to the file specified by the given path.
85 // Return true on success.
86 bool writeMergedModules(const char *path, std::string &errMsg);
88 // Compile the merged module into a *single* object file; the path to object
89 // file is returned to the caller via argument "name". Return true on
92 // NOTE that it is up to the linker to remove the intermediate object file.
93 // Do not try to remove the object file in LTOCodeGenerator's destructor
94 // as we don't who (LTOCodeGenerator or the obj file) will last longer.
96 bool compile_to_file(const char **name, std::string &errMsg);
98 // As with compile_to_file(), this function compiles the merged module into
99 // single object file. Instead of returning the object-file-path to the caller
100 // (linker), it brings the object to a buffer, and return the buffer to the
101 // caller. This function should delete intermediate object file once its content
102 // is brought to memory. Return NULL is the compilation was not successful.
104 const void *compile(size_t *length, std::string &errMsg);
106 // Return the paths of the intermediate files that linker needs to delete
107 // before it exits. The paths are delimited by a single '\0', and the last
108 // path is ended by double '\0's. The file could be a directory. In that
109 // case, the entire directory should be erased recusively. This function
110 // must be called after the compilexxx() is successfuly called, because
111 // only after that moment, compiler is aware which files need to be removed.
112 // If calling compilexxx() is not successful, it is up to compiler to clean
113 // up all the intermediate files generated during the compilation process.
115 const char *getFilesNeedToRemove();
118 void initializeLTOPasses();
119 bool determineTarget(std::string &errMsg);
121 bool prepareBeforeCompile(std::string &ErrMsg);
123 void performIPO(bool PerformPartition, std::string &ErrMsg);
124 bool performPostIPO(std::string &ErrMsg, bool MergeObjs = false,
125 const char **MergObjPath = 0);
126 bool generateObjectFile(llvm::raw_ostream &out, std::string &errMsg);
128 void applyScopeRestrictions();
129 void applyRestriction(llvm::GlobalValue &GV,
130 std::vector<const char*> &mustPreserveList,
131 llvm::SmallPtrSet<llvm::GlobalValue*, 8> &asmUsed,
132 llvm::Mangler &mangler);
135 typedef llvm::StringMap<uint8_t> StringSet;
137 llvm::LLVMContext& _context;
138 llvm::Linker _linker;
139 llvm::TargetMachine* _target;
140 bool _emitDwarfDebugInfo;
141 bool _scopeRestrictionsDone;
142 lto_codegen_model _codeModel;
143 StringSet _mustPreserveSymbols;
144 StringSet _asmUndefinedRefs;
145 llvm::MemoryBuffer* _nativeObjectFile;
146 std::vector<char*> _codegenOptions;
148 std::string _nativeObjectPath;
150 // To manage the partitions. If partition is not enabled, the whole merged
151 // module is considered as a single degenerated partition, and the "manager"
153 lto::IPOPartMgr PartitionMgr;
155 // To manage the intermediate files during the compilations.
156 lto::IPOFileMgr FileMgr;
158 // Sometimes we need to return a vector of strings in a "C" way (to work with
159 // the C-APIs). We encode such C-thinking string vector by concatenating all
160 // strings tegother with a single '\0' as the delimitor, the last string ended
162 SmallVector<char, 4> ConcatStrings;
164 // Make sure command line is parsed only once. It would otherwise complain
165 // and quite prematurely.
169 #endif // LTO_CODE_GENERATOR_H