llvm-extract.cpp revision 2c785880eadb75f821771352ccf4a442a1b05668 
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/Bitcode/ReaderWriter.h"
19#include "llvm/Transforms/IPO.h"
20#include "llvm/Target/TargetData.h"
21#include "llvm/Support/CommandLine.h"
22#include "llvm/Support/ManagedStatic.h"
23#include "llvm/Support/MemoryBuffer.h"
24#include "llvm/Support/PrettyStackTrace.h"
25#include "llvm/Support/raw_ostream.h"
26#include "llvm/System/Signals.h"
27#include <memory>
28using namespace llvm;
29
30// InputFilename - The filename to read from.
31static cl::opt<std::string>
32InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
33              cl::init("-"), cl::value_desc("filename"));
34
35static cl::opt<std::string>
36OutputFilename("o", cl::desc("Specify output filename"),
37               cl::value_desc("filename"), cl::init("-"));
38
39static cl::opt<bool>
40Force("f", cl::desc("Overwrite output files"));
41
42static cl::opt<bool>
43DeleteFn("delete", cl::desc("Delete specified Globals from Module"));
44
45static cl::opt<bool>
46Relink("relink",
47       cl::desc("Turn external linkage for callees of function to delete"));
48
49// ExtractFunc - The function to extract from the module...
50static cl::opt<std::string>
51ExtractFunc("func", cl::desc("Specify function to extract"), cl::init(""),
52            cl::value_desc("function"));
53
54// ExtractGlobal - The global to extract from the module...
55static cl::opt<std::string>
56ExtractGlobal("glob", cl::desc("Specify global to extract"), cl::init(""),
57              cl::value_desc("global"));
58
59int main(int argc, char **argv) {
60  // Print a stack trace if we signal out.
61  sys::PrintStackTraceOnErrorSignal();
62  PrettyStackTraceProgram X(argc, argv);
63
64  LLVMContext &Context = getGlobalContext();
65  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
66  cl::ParseCommandLineOptions(argc, argv, "llvm extractor\n");
67
68  std::auto_ptr<Module> M;
69
70  MemoryBuffer *Buffer = MemoryBuffer::getFileOrSTDIN(InputFilename);
71  if (Buffer == 0) {
72    errs() << argv[0] << ": Error reading file '" + InputFilename + "'\n";
73    return 1;
74  } else {
75    M.reset(ParseBitcodeFile(Buffer, Context));
76  }
77  delete Buffer;
78
79  if (M.get() == 0) {
80    errs() << argv[0] << ": bitcode didn't read correctly.\n";
81    return 1;
82  }
83
84  // Figure out which function we should extract
85  GlobalVariable *G = !ExtractGlobal.empty() ?
86    M.get()->getNamedGlobal(ExtractGlobal) : 0;
87
88  // Figure out which function we should extract
89  if (ExtractFunc.empty() && ExtractGlobal.empty()) ExtractFunc = "main";
90  Function *F = M.get()->getFunction(ExtractFunc);
91
92  if (F == 0 && G == 0) {
93    errs() << argv[0] << ": program doesn't contain function named '"
94           << ExtractFunc << "' or a global named '" << ExtractGlobal << "'!\n";
95    return 1;
96  }
97
98  // In addition to deleting all other functions, we also want to spiff it
99  // up a little bit.  Do this now.
100  PassManager Passes;
101  Passes.add(new TargetData(M.get())); // Use correct TargetData
102  // Either isolate the function or delete it from the Module
103  std::vector<GlobalValue*> GVs;
104  if (F) GVs.push_back(F);
105  if (G) GVs.push_back(G);
106
107  Passes.add(createGVExtractionPass(GVs, DeleteFn, Relink));
108  if (!DeleteFn)
109    Passes.add(createGlobalDCEPass());           // Delete unreachable globals
110  Passes.add(createDeadTypeEliminationPass());   // Remove dead types...
111  Passes.add(createStripDeadPrototypesPass());   // Remove dead func decls
112
113  raw_ostream *Out = 0;
114
115  if (OutputFilename != "-") {  // Not stdout?
116    std::string ErrorInfo;
117    Out = new raw_fd_ostream(OutputFilename.c_str(), /*Binary=*/true,
118                             Force, ErrorInfo);
119    if (!ErrorInfo.empty()) {
120      errs() << ErrorInfo << '\n';
121      if (!Force)
122        errs() << "Use -f command line argument to force output\n";
123      delete Out;
124      return 1;
125    }
126  } else {                      // Specified stdout
127    // FIXME: outs() is not binary!
128    Out = &outs();
129  }
130
131  Passes.add(createBitcodeWriterPass(*Out));
132  Passes.run(*M.get());
133
134  if (Out != &outs())
135    delete Out;
136  return 0;
137}
138