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"
54 //===----------------------------------------------------------------------===//
55 /// LTOCodeGenerator - C++ class which implements the opaque lto_code_gen_t
58 struct LTOCodeGenerator {
59 static const char *getVersionString();
64 // Merge given module, return true on success.
65 bool addModule(struct LTOModule*, std::string &errMsg);
67 void setDebugInfo(lto_debug_model);
68 void setCodePICModel(lto_codegen_model);
70 void setCpu(const char* mCpu) { _mCpu = mCpu; }
72 void addMustPreserveSymbol(const char* sym) {
73 _mustPreserveSymbols[sym] = 1;
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().
81 void setCodeGenDebugOptions(const char *opts);
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);
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
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.
95 bool compile_to_file(const char **name, std::string &errMsg);
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.
103 const void *compile(size_t *length, std::string &errMsg);
106 void initializeLTOPasses();
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);
116 typedef llvm::StringMap<uint8_t> StringSet;
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;
129 std::string _nativeObjectPath;
132 #endif // LTO_CODE_GENERATOR_H