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
47namespace 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///
61struct 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
120private:
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