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
45namespace 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///
58struct 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
105private:
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