tools/bugpoint/ExtractFunction.cpp

   1 //===- ExtractFunction.cpp - Extract a function from Program --------------===//
   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 implements several methods that are used to extract functions,
  11 // loops, or portions of a module from the rest of the module.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "BugDriver.h"
  16 #include "llvm/Constants.h"
  17 #include "llvm/DerivedTypes.h"
  18 #include "llvm/LLVMContext.h"
  19 #include "llvm/Module.h"
  20 #include "llvm/PassManager.h"
  21 #include "llvm/Pass.h"
  22 #include "llvm/Analysis/Verifier.h"
  23 #include "llvm/Assembly/Writer.h"
  24 #include "llvm/Transforms/IPO.h"
  25 #include "llvm/Transforms/Scalar.h"
  26 #include "llvm/Transforms/Utils/Cloning.h"
  27 #include "llvm/Transforms/Utils/FunctionUtils.h"
  28 #include "llvm/Target/TargetData.h"
  29 #include "llvm/Support/CommandLine.h"
  30 #include "llvm/Support/Debug.h"
  31 #include "llvm/Support/FileUtilities.h"
  32 #include "llvm/Support/ToolOutputFile.h"
  33 #include "llvm/Support/Path.h"
  34 #include "llvm/Support/Signals.h"
  35 #include <set>
  36 using namespace llvm;
  37
  38 namespace llvm {
  39   bool DisableSimplifyCFG = false;
  40   extern cl::opt<std::string> OutputPrefix;
  41 } // End llvm namespace
  42
  43 namespace {
  44   cl::opt<bool>
  45   NoDCE ("disable-dce",
  46          cl::desc("Do not use the -dce pass to reduce testcases"));
  47   cl::opt<bool, true>
  48   NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
  49          cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
  50 }
  51
  52 /// deleteInstructionFromProgram - This method clones the current Program and
  53 /// deletes the specified instruction from the cloned module.  It then runs a
  54 /// series of cleanup passes (ADCE and SimplifyCFG) to eliminate any code which
  55 /// depends on the value.  The modified module is then returned.
  56 ///
  57 Module *BugDriver::deleteInstructionFromProgram(const Instruction *I,
  58                                                 unsigned Simplification) {
  59   // FIXME, use vmap?
  60   Module *Clone = CloneModule(Program);
  61
  62   const BasicBlock *PBB = I->getParent();
  63   const Function *PF = PBB->getParent();
  64
  65   Module::iterator RFI = Clone->begin(); // Get iterator to corresponding fn
  66   std::advance(RFI, std::distance(PF->getParent()->begin(),
  67                                   Module::const_iterator(PF)));
  68
  69   Function::iterator RBI = RFI->begin();  // Get iterator to corresponding BB
  70   std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB)));
  71
  72   BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
  73   std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I)));
  74   Instruction *TheInst = RI;              // Got the corresponding instruction!
  75
  76   // If this instruction produces a value, replace any users with null values
  77   if (!TheInst->getType()->isVoidTy())
  78     TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
  79
  80   // Remove the instruction from the program.
  81   TheInst->getParent()->getInstList().erase(TheInst);
  82
  83   // Spiff up the output a little bit.
  84   std::vector<std::string> Passes;
  85
  86   /// Can we get rid of the -disable-* options?
  87   if (Simplification > 1 && !NoDCE)
  88     Passes.push_back("dce");
  89   if (Simplification && !DisableSimplifyCFG)
  90     Passes.push_back("simplifycfg");      // Delete dead control flow
  91
  92   Passes.push_back("verify");
  93   Module *New = runPassesOn(Clone, Passes);
  94   delete Clone;
  95   if (!New) {
  96     errs() << "Instruction removal failed.  Sorry. :(  Please report a bug!\n";
  97     exit(1);
  98   }
  99   return New;
 100 }
 101
 102 /// performFinalCleanups - This method clones the current Program and performs
 103 /// a series of cleanups intended to get rid of extra cruft on the module
 104 /// before handing it to the user.
 105 ///
 106 Module *BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
 107   // Make all functions external, so GlobalDCE doesn't delete them...
 108   for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
 109     I->setLinkage(GlobalValue::ExternalLinkage);
 110
 111   std::vector<std::string> CleanupPasses;
 112   CleanupPasses.push_back("globaldce");
 113
 114   if (MayModifySemantics)
 115     CleanupPasses.push_back("deadarghaX0r");
 116   else
 117     CleanupPasses.push_back("deadargelim");
 118
 119   Module *New = runPassesOn(M, CleanupPasses);
 120   if (New == 0) {
 121     errs() << "Final cleanups failed.  Sorry. :(  Please report a bug!\n";
 122     return M;
 123   }
 124   delete M;
 125   return New;
 126 }
 127
 128
 129 /// ExtractLoop - Given a module, extract up to one loop from it into a new
 130 /// function.  This returns null if there are no extractable loops in the
 131 /// program or if the loop extractor crashes.
 132 Module *BugDriver::ExtractLoop(Module *M) {
 133   std::vector<std::string> LoopExtractPasses;
 134   LoopExtractPasses.push_back("loop-extract-single");
 135
 136   Module *NewM = runPassesOn(M, LoopExtractPasses);
 137   if (NewM == 0) {
 138     outs() << "*** Loop extraction failed: ";
 139     EmitProgressBitcode(M, "loopextraction", true);
 140     outs() << "*** Sorry. :(  Please report a bug!\n";
 141     return 0;
 142   }
 143
 144   // Check to see if we created any new functions.  If not, no loops were
 145   // extracted and we should return null.  Limit the number of loops we extract
 146   // to avoid taking forever.
 147   static unsigned NumExtracted = 32;
 148   if (M->size() == NewM->size() || --NumExtracted == 0) {
 149     delete NewM;
 150     return 0;
 151   } else {
 152     assert(M->size() < NewM->size() && "Loop extract removed functions?");
 153     Module::iterator MI = NewM->begin();
 154     for (unsigned i = 0, e = M->size(); i != e; ++i)
 155       ++MI;
 156   }
 157
 158   return NewM;
 159 }
 160
 161
 162 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
 163 // blocks, making it external.
 164 //
 165 void llvm::DeleteFunctionBody(Function *F) {
 166   // delete the body of the function...
 167   F->deleteBody();
 168   assert(F->isDeclaration() && "This didn't make the function external!");
 169 }
 170
 171 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
 172 /// as a constant array.
 173 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
 174   assert(!TorList.empty() && "Don't create empty tor list!");
 175   std::vector<Constant*> ArrayElts;
 176   const Type *Int32Ty = Type::getInt32Ty(TorList[0].first->getContext());
 177
 178   const StructType *STy =
 179     StructType::get(Int32Ty, TorList[0].first->getType(), NULL);
 180   for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
 181     Constant *Elts[] = {
 182       ConstantInt::get(Int32Ty, TorList[i].second),
 183       TorList[i].first
 184     };
 185     ArrayElts.push_back(ConstantStruct::get(STy, Elts));
 186   }
 187   return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
 188                                            ArrayElts.size()),
 189                             ArrayElts);
 190 }
 191
 192 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
 193 /// M1 has all of the global variables.  If M2 contains any functions that are
 194 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
 195 /// prune appropriate entries out of M1s list.
 196 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
 197                                 ValueToValueMapTy &VMap) {
 198   GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
 199   if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
 200       !GV->use_empty()) return;
 201
 202   std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
 203   ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
 204   if (!InitList) return;
 205
 206   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
 207     if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
 208       if (CS->getNumOperands() != 2) return;  // Not array of 2-element structs.
 209
 210       if (CS->getOperand(1)->isNullValue())
 211         break;  // Found a null terminator, stop here.
 212
 213       ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
 214       int Priority = CI ? CI->getSExtValue() : 0;
 215
 216       Constant *FP = CS->getOperand(1);
 217       if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
 218         if (CE->isCast())
 219           FP = CE->getOperand(0);
 220       if (Function *F = dyn_cast<Function>(FP)) {
 221         if (!F->isDeclaration())
 222           M1Tors.push_back(std::make_pair(F, Priority));
 223         else {
 224           // Map to M2's version of the function.
 225           F = cast<Function>(VMap[F]);
 226           M2Tors.push_back(std::make_pair(F, Priority));
 227         }
 228       }
 229     }
 230   }
 231
 232   GV->eraseFromParent();
 233   if (!M1Tors.empty()) {
 234     Constant *M1Init = GetTorInit(M1Tors);
 235     new GlobalVariable(*M1, M1Init->getType(), false,
 236                        GlobalValue::AppendingLinkage,
 237                        M1Init, GlobalName);
 238   }
 239
 240   GV = M2->getNamedGlobal(GlobalName);
 241   assert(GV && "Not a clone of M1?");
 242   assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
 243
 244   GV->eraseFromParent();
 245   if (!M2Tors.empty()) {
 246     Constant *M2Init = GetTorInit(M2Tors);
 247     new GlobalVariable(*M2, M2Init->getType(), false,
 248                        GlobalValue::AppendingLinkage,
 249                        M2Init, GlobalName);
 250   }
 251 }
 252
 253
 254 /// SplitFunctionsOutOfModule - Given a module and a list of functions in the
 255 /// module, split the functions OUT of the specified module, and place them in
 256 /// the new module.
 257 Module *
 258 llvm::SplitFunctionsOutOfModule(Module *M,
 259                                 const std::vector<Function*> &F,
 260                                 ValueToValueMapTy &VMap) {
 261   // Make sure functions & globals are all external so that linkage
 262   // between the two modules will work.
 263   for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
 264     I->setLinkage(GlobalValue::ExternalLinkage);
 265   for (Module::global_iterator I = M->global_begin(), E = M->global_end();
 266        I != E; ++I) {
 267     if (I->hasName() && I->getName()[0] == '\01')
 268       I->setName(I->getName().substr(1));
 269     I->setLinkage(GlobalValue::ExternalLinkage);
 270   }
 271
 272   ValueToValueMapTy NewVMap;
 273   Module *New = CloneModule(M, NewVMap);
 274
 275   // Make sure global initializers exist only in the safe module (CBE->.so)
 276   for (Module::global_iterator I = New->global_begin(), E = New->global_end();
 277        I != E; ++I)
 278     I->setInitializer(0);  // Delete the initializer to make it external
 279
 280   // Remove the Test functions from the Safe module
 281   std::set<Function *> TestFunctions;
 282   for (unsigned i = 0, e = F.size(); i != e; ++i) {
 283     Function *TNOF = cast<Function>(VMap[F[i]]);
 284     DEBUG(errs() << "Removing function ");
 285     DEBUG(WriteAsOperand(errs(), TNOF, false));
 286     DEBUG(errs() << "\n");
 287     TestFunctions.insert(cast<Function>(NewVMap[TNOF]));
 288     DeleteFunctionBody(TNOF);       // Function is now external in this module!
 289   }
 290
 291
 292   // Remove the Safe functions from the Test module
 293   for (Module::iterator I = New->begin(), E = New->end(); I != E; ++I)
 294     if (!TestFunctions.count(I))
 295       DeleteFunctionBody(I);
 296
 297
 298   // Make sure that there is a global ctor/dtor array in both halves of the
 299   // module if they both have static ctor/dtor functions.
 300   SplitStaticCtorDtor("llvm.global_ctors", M, New, NewVMap);
 301   SplitStaticCtorDtor("llvm.global_dtors", M, New, NewVMap);
 302
 303   return New;
 304 }
 305
 306 //===----------------------------------------------------------------------===//
 307 // Basic Block Extraction Code
 308 //===----------------------------------------------------------------------===//
 309
 310 /// ExtractMappedBlocksFromModule - Extract all but the specified basic blocks
 311 /// into their own functions.  The only detail is that M is actually a module
 312 /// cloned from the one the BBs are in, so some mapping needs to be performed.
 313 /// If this operation fails for some reason (ie the implementation is buggy),
 314 /// this function should return null, otherwise it returns a new Module.
 315 Module *BugDriver::ExtractMappedBlocksFromModule(const
 316                                                  std::vector<BasicBlock*> &BBs,
 317                                                  Module *M) {
 318   sys::Path uniqueFilename(OutputPrefix + "-extractblocks");
 319   std::string ErrMsg;
 320   if (uniqueFilename.createTemporaryFileOnDisk(true, &ErrMsg)) {
 321     outs() << "*** Basic Block extraction failed!\n";
 322     errs() << "Error creating temporary file: " << ErrMsg << "\n";
 323     EmitProgressBitcode(M, "basicblockextractfail", true);
 324     return 0;
 325   }
 326   sys::RemoveFileOnSignal(uniqueFilename);
 327
 328   std::string ErrorInfo;
 329   tool_output_file BlocksToNotExtractFile(uniqueFilename.c_str(), ErrorInfo);
 330   if (!ErrorInfo.empty()) {
 331     outs() << "*** Basic Block extraction failed!\n";
 332     errs() << "Error writing list of blocks to not extract: " << ErrorInfo
 333            << "\n";
 334     EmitProgressBitcode(M, "basicblockextractfail", true);
 335     return 0;
 336   }
 337   for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
 338        I != E; ++I) {
 339     BasicBlock *BB = *I;
 340     // If the BB doesn't have a name, give it one so we have something to key
 341     // off of.
 342     if (!BB->hasName()) BB->setName("tmpbb");
 343     BlocksToNotExtractFile.os() << BB->getParent()->getNameStr() << " "
 344                                 << BB->getName() << "\n";
 345   }
 346   BlocksToNotExtractFile.os().close();
 347   if (BlocksToNotExtractFile.os().has_error()) {
 348     errs() << "Error writing list of blocks to not extract: " << ErrorInfo
 349            << "\n";
 350     EmitProgressBitcode(M, "basicblockextractfail", true);
 351     BlocksToNotExtractFile.os().clear_error();
 352     return 0;
 353   }
 354   BlocksToNotExtractFile.keep();
 355
 356   std::string uniqueFN = "--extract-blocks-file=" + uniqueFilename.str();
 357   const char *ExtraArg = uniqueFN.c_str();
 358
 359   std::vector<std::string> PI;
 360   PI.push_back("extract-blocks");
 361   Module *Ret = runPassesOn(M, PI, false, 1, &ExtraArg);
 362
 363   uniqueFilename.eraseFromDisk(); // Free disk space
 364
 365   if (Ret == 0) {
 366     outs() << "*** Basic Block extraction failed, please report a bug!\n";
 367     EmitProgressBitcode(M, "basicblockextractfail", true);
 368   }
 369   return Ret;
 370 }