llvm-extract.cpp revision 2df9504fec1ddf198321c7fe8c968154b4edbff3 
1//===- llvm-extract.cpp - LLVM function extraction utility ----------------===//
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 utility changes the input module to only contain a single function,
11// which is primarily used for debugging transformations.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/LLVMContext.h"
16#include "llvm/Module.h"
17#include "llvm/PassManager.h"
18#include "llvm/Assembly/PrintModulePass.h"
19#include "llvm/Bitcode/ReaderWriter.h"
20#include "llvm/Transforms/IPO.h"
21#include "llvm/Target/TargetData.h"
22#include "llvm/Support/CommandLine.h"
23#include "llvm/Support/IRReader.h"
24#include "llvm/Support/ManagedStatic.h"
25#include "llvm/Support/PrettyStackTrace.h"
26#include "llvm/Support/raw_ostream.h"
27#include "llvm/Support/SystemUtils.h"
28#include "llvm/System/Signals.h"
29#include <memory>
30using namespace llvm;
31
32// InputFilename - The filename to read from.
33static cl::opt<std::string>
34InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
35              cl::init("-"), cl::value_desc("filename"));
36
37static cl::opt<std::string>
38OutputFilename("o", cl::desc("Specify output filename"),
39               cl::value_desc("filename"), cl::init("-"));
40
41static cl::opt<bool>
42Force("f", cl::desc("Enable binary output on terminals"));
43
44static cl::opt<bool>
45DeleteFn("delete", cl::desc("Delete specified Globals from Module"));
46
47static cl::opt<bool>
48Relink("relink",
49       cl::desc("Turn external linkage for callees of function to delete"));
50
51// ExtractFuncs - The functions to extract from the module...
52static cl::list<std::string>
53ExtractFuncs("func", cl::desc("Specify function to extract"),
54             cl::ZeroOrMore, cl::value_desc("function"));
55
56// ExtractGlobals - The globals to extract from the module...
57static cl::list<std::string>
58ExtractGlobals("glob", cl::desc("Specify global to extract"),
59               cl::ZeroOrMore, cl::value_desc("global"));
60
61static cl::opt<bool>
62OutputAssembly("S",
63               cl::desc("Write output as LLVM assembly"), cl::Hidden);
64
65int main(int argc, char **argv) {
66  // Print a stack trace if we signal out.
67  sys::PrintStackTraceOnErrorSignal();
68  PrettyStackTraceProgram X(argc, argv);
69
70  LLVMContext &Context = getGlobalContext();
71  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
72  cl::ParseCommandLineOptions(argc, argv, "llvm extractor\n");
73
74  SMDiagnostic Err;
75  std::auto_ptr<Module> M;
76  M.reset(ParseIRFile(InputFilename, Err, Context));
77
78  if (M.get() == 0) {
79    Err.Print(argv[0], errs());
80    return 1;
81  }
82
83  std::vector<GlobalValue *> GVs;
84
85  // Figure out which globals we should extract.
86  for (size_t i = 0, e = ExtractGlobals.size(); i != e; ++i) {
87    GlobalValue *GV = M.get()->getNamedGlobal(ExtractGlobals[i]);
88    if (!GV) {
89      errs() << argv[0] << ": program doesn't contain global named '"
90             << ExtractGlobals[i] << "'!\n";
91      return 1;
92    }
93    GVs.push_back(GV);
94  }
95
96  // Figure out which functions we should extract.
97  for (size_t i = 0, e = ExtractFuncs.size(); i != e; ++i) {
98    GlobalValue *GV = M.get()->getFunction(ExtractFuncs[i]);
99    if (!GV) {
100      errs() << argv[0] << ": program doesn't contain function named '"
101             << ExtractFuncs[i] << "'!\n";
102      return 1;
103    }
104    GVs.push_back(GV);
105  }
106
107  // In addition to deleting all other functions, we also want to spiff it
108  // up a little bit.  Do this now.
109  PassManager Passes;
110  Passes.add(new TargetData(M.get())); // Use correct TargetData
111
112  Passes.add(createGVExtractionPass(GVs, DeleteFn, Relink));
113  if (!DeleteFn)
114    Passes.add(createGlobalDCEPass());           // Delete unreachable globals
115  Passes.add(createStripDeadDebugInfoPass());    // Remove dead debug info
116  Passes.add(createDeadTypeEliminationPass());   // Remove dead types...
117  Passes.add(createStripDeadPrototypesPass());   // Remove dead func decls
118
119  std::string ErrorInfo;
120  tool_output_file Out(OutputFilename.c_str(), ErrorInfo,
121                       raw_fd_ostream::F_Binary);
122  if (!ErrorInfo.empty()) {
123    errs() << ErrorInfo << '\n';
124    return 1;
125  }
126
127  if (OutputAssembly)
128    Passes.add(createPrintModulePass(&Out));
129  else if (Force || !CheckBitcodeOutputToConsole(Out, true))
130    Passes.add(createBitcodeWriterPass(Out));
131
132  Passes.run(*M.get());
133
134  // Declare success.
135  Out.keep();
136
137  return 0;
138}
139