1 //===----------------------------------------------------------------------===//
2 // LLVM extract Utility
4 // This utility changes the input module to only contain a single function,
5 // which is primarily used for debugging transformations.
7 //===----------------------------------------------------------------------===//
9 #include "llvm/Module.h"
10 #include "llvm/PassManager.h"
11 #include "llvm/Bytecode/Reader.h"
12 #include "llvm/Bytecode/WriteBytecodePass.h"
13 #include "llvm/Transforms/IPO.h"
14 #include "Support/CommandLine.h"
17 // InputFilename - The filename to read from.
18 static cl::opt<std::string>
19 InputFilename(cl::Positional, cl::desc("<input bytecode file>"),
20 cl::init("-"), cl::value_desc("filename"));
23 // ExtractFunc - The function to extract from the module... defaults to main.
24 static cl::opt<std::string>
25 ExtractFunc("func", cl::desc("Specify function to extract"), cl::init("main"),
26 cl::value_desc("function"));
29 struct FunctionExtractorPass : public Pass {
31 // Mark all global variables to be internal
32 for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; ++I)
34 I->setInternalLinkage(true);
38 // Loop over all of the functions in the module, dropping all references in
39 // functions that are not the named function.
40 for (Module::iterator I = M.begin(), E = M.end(); I != E;)
41 // Check to see if this is the named function!
42 if (I->getName() == ExtractFunc && !I->isExternal()) {
43 if (Named) { // Two functions, same name?
44 std::cerr << "extract ERROR: Two functions named: '" << ExtractFunc
49 // Yes, it is. Keep track of it...
52 // Make sure it's globally accessable...
53 Named->setInternalLinkage(false);
55 // Remove the named function from the module.
56 M.getFunctionList().remove(I);
58 // Nope it's not the named function, delete the body of the function
59 I->dropAllReferences();
63 // All of the functions that still have uses now must be used by global
64 // variables or the named function. Loop through them and create a new,
65 // external function for the used ones... making all uses point to the new
67 std::vector<Function*> NewFunctions;
69 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
70 if (!I->use_empty()) {
71 Function *New = new Function(I->getFunctionType(), false, I->getName());
72 I->replaceAllUsesWith(New);
73 NewFunctions.push_back(New);
76 // Now the module only has unused functions with their references dropped.
77 // Delete them all now!
78 M.getFunctionList().clear();
80 // Re-insert the named function...
82 M.getFunctionList().push_back(Named);
84 std::cerr << "Warning: Function '" << ExtractFunc << "' not found!\n";
86 // Insert all of the function stubs...
87 M.getFunctionList().insert(M.end(), NewFunctions.begin(),
94 static RegisterPass<FunctionExtractorPass> X("extract", "Function Extractor");
97 int main(int argc, char **argv) {
98 cl::ParseCommandLineOptions(argc, argv, " llvm extractor\n");
100 std::auto_ptr<Module> M(ParseBytecodeFile(InputFilename));
102 std::cerr << argv[0] << ": bytecode didn't read correctly.\n";
106 // In addition to just parsing the input from GCC, we also want to spiff it up
107 // a little bit. Do this now.
110 Passes.add(new FunctionExtractorPass());
111 Passes.add(createGlobalDCEPass()); // Delete unreachable globals
112 Passes.add(createConstantMergePass()); // Merge dup global constants
113 Passes.add(createDeadTypeEliminationPass()); // Remove dead types...
114 Passes.add(new WriteBytecodePass(&std::cout)); // Write bytecode to file...
116 Passes.run(*M.get());