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/Module.h"
  19 #include "llvm/PassManager.h"
  20 #include "llvm/Pass.h"
  21 #include "llvm/Analysis/Verifier.h"
  22 #include "llvm/Transforms/IPO.h"
  23 #include "llvm/Transforms/Scalar.h"
  24 #include "llvm/Transforms/Utils/Cloning.h"
  25 #include "llvm/Transforms/Utils/FunctionUtils.h"
  26 #include "llvm/Target/TargetData.h"
  27 #include "llvm/Support/CommandLine.h"
  28 #include "llvm/Support/Debug.h"
  29 #include "llvm/Support/FileUtilities.h"
  30 #include "llvm/System/Path.h"
  31 #include "llvm/System/Signals.h"
  32 #include <set>
  33 #include <fstream>
  34 #include <iostream>
  35 using namespace llvm;
  36
  37 namespace llvm {
  38   bool DisableSimplifyCFG = false;
  39 } // End llvm namespace
  40
  41 namespace {
  42   cl::opt<bool>
  43   NoDCE ("disable-dce",
  44          cl::desc("Do not use the -dce pass to reduce testcases"));
  45   cl::opt<bool, true>
  46   NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
  47          cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
  48 }
  49
  50 /// deleteInstructionFromProgram - This method clones the current Program and
  51 /// deletes the specified instruction from the cloned module.  It then runs a
  52 /// series of cleanup passes (ADCE and SimplifyCFG) to eliminate any code which
  53 /// depends on the value.  The modified module is then returned.
  54 ///
  55 Module *BugDriver::deleteInstructionFromProgram(const Instruction *I,
  56                                                 unsigned Simplification) const {
  57   Module *Result = CloneModule(Program);
  58
  59   const BasicBlock *PBB = I->getParent();
  60   const Function *PF = PBB->getParent();
  61
  62   Module::iterator RFI = Result->begin(); // Get iterator to corresponding fn
  63   std::advance(RFI, std::distance(PF->getParent()->begin(),
  64                                   Module::const_iterator(PF)));
  65
  66   Function::iterator RBI = RFI->begin();  // Get iterator to corresponding BB
  67   std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB)));
  68
  69   BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
  70   std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I)));
  71   Instruction *TheInst = RI;              // Got the corresponding instruction!
  72
  73   // If this instruction produces a value, replace any users with null values
  74   if (isa<StructType>(TheInst->getType()))
  75     TheInst->replaceAllUsesWith(UndefValue::get(TheInst->getType()));
  76   else if (TheInst->getType() != Type::VoidTy)
  77     TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
  78
  79   // Remove the instruction from the program.
  80   TheInst->getParent()->getInstList().erase(TheInst);
  81
  82
  83   //writeProgramToFile("current.bc", Result);
  84
  85   // Spiff up the output a little bit.
  86   PassManager Passes;
  87   // Make sure that the appropriate target data is always used...
  88   Passes.add(new TargetData(Result));
  89
  90   /// FIXME: If this used runPasses() like the methods below, we could get rid
  91   /// of the -disable-* options!
  92   if (Simplification > 1 && !NoDCE)
  93     Passes.add(createDeadCodeEliminationPass());
  94   if (Simplification && !DisableSimplifyCFG)
  95     Passes.add(createCFGSimplificationPass());      // Delete dead control flow
  96
  97   Passes.add(createVerifierPass());
  98   Passes.run(*Result);
  99   return Result;
 100 }
 101
 102 static const PassInfo *getPI(Pass *P) {
 103   const PassInfo *PI = P->getPassInfo();
 104   delete P;
 105   return PI;
 106 }
 107
 108 /// performFinalCleanups - This method clones the current Program and performs
 109 /// a series of cleanups intended to get rid of extra cruft on the module
 110 /// before handing it to the user.
 111 ///
 112 Module *BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
 113   // Make all functions external, so GlobalDCE doesn't delete them...
 114   for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
 115     I->setLinkage(GlobalValue::ExternalLinkage);
 116
 117   std::vector<const PassInfo*> CleanupPasses;
 118   CleanupPasses.push_back(getPI(createGlobalDCEPass()));
 119   CleanupPasses.push_back(getPI(createDeadTypeEliminationPass()));
 120
 121   if (MayModifySemantics)
 122     CleanupPasses.push_back(getPI(createDeadArgHackingPass()));
 123   else
 124     CleanupPasses.push_back(getPI(createDeadArgEliminationPass()));
 125
 126   Module *New = runPassesOn(M, CleanupPasses);
 127   if (New == 0) {
 128     std::cerr << "Final cleanups failed.  Sorry. :(  Please report a bug!\n";
 129     return M;
 130   }
 131   delete M;
 132   return New;
 133 }
 134
 135
 136 /// ExtractLoop - Given a module, extract up to one loop from it into a new
 137 /// function.  This returns null if there are no extractable loops in the
 138 /// program or if the loop extractor crashes.
 139 Module *BugDriver::ExtractLoop(Module *M) {
 140   std::vector<const PassInfo*> LoopExtractPasses;
 141   LoopExtractPasses.push_back(getPI(createSingleLoopExtractorPass()));
 142
 143   Module *NewM = runPassesOn(M, LoopExtractPasses);
 144   if (NewM == 0) {
 145     Module *Old = swapProgramIn(M);
 146     std::cout << "*** Loop extraction failed: ";
 147     EmitProgressBitcode("loopextraction", true);
 148     std::cout << "*** Sorry. :(  Please report a bug!\n";
 149     swapProgramIn(Old);
 150     return 0;
 151   }
 152
 153   // Check to see if we created any new functions.  If not, no loops were
 154   // extracted and we should return null.  Limit the number of loops we extract
 155   // to avoid taking forever.
 156   static unsigned NumExtracted = 32;
 157   if (M->size() == NewM->size() || --NumExtracted == 0) {
 158     delete NewM;
 159     return 0;
 160   } else {
 161     assert(M->size() < NewM->size() && "Loop extract removed functions?");
 162     Module::iterator MI = NewM->begin();
 163     for (unsigned i = 0, e = M->size(); i != e; ++i)
 164       ++MI;
 165   }
 166
 167   return NewM;
 168 }
 169
 170
 171 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
 172 // blocks, making it external.
 173 //
 174 void llvm::DeleteFunctionBody(Function *F) {
 175   // delete the body of the function...
 176   F->deleteBody();
 177   assert(F->isDeclaration() && "This didn't make the function external!");
 178 }
 179
 180 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
 181 /// as a constant array.
 182 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
 183   assert(!TorList.empty() && "Don't create empty tor list!");
 184   std::vector<Constant*> ArrayElts;
 185   for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
 186     std::vector<Constant*> Elts;
 187     Elts.push_back(ConstantInt::get(Type::Int32Ty, TorList[i].second));
 188     Elts.push_back(TorList[i].first);
 189     ArrayElts.push_back(ConstantStruct::get(Elts));
 190   }
 191   return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
 192                                            ArrayElts.size()),
 193                             ArrayElts);
 194 }
 195
 196 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
 197 /// M1 has all of the global variables.  If M2 contains any functions that are
 198 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
 199 /// prune appropriate entries out of M1s list.
 200 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
 201                                 DenseMap<const Value*, Value*> ValueMap) {
 202   GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
 203   if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
 204       !GV->use_empty()) return;
 205
 206   std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
 207   ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
 208   if (!InitList) return;
 209
 210   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
 211     if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
 212       if (CS->getNumOperands() != 2) return;  // Not array of 2-element structs.
 213
 214       if (CS->getOperand(1)->isNullValue())
 215         break;  // Found a null terminator, stop here.
 216
 217       ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
 218       int Priority = CI ? CI->getSExtValue() : 0;
 219
 220       Constant *FP = CS->getOperand(1);
 221       if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
 222         if (CE->isCast())
 223           FP = CE->getOperand(0);
 224       if (Function *F = dyn_cast<Function>(FP)) {
 225         if (!F->isDeclaration())
 226           M1Tors.push_back(std::make_pair(F, Priority));
 227         else {
 228           // Map to M2's version of the function.
 229           F = cast<Function>(ValueMap[F]);
 230           M2Tors.push_back(std::make_pair(F, Priority));
 231         }
 232       }
 233     }
 234   }
 235
 236   GV->eraseFromParent();
 237   if (!M1Tors.empty()) {
 238     Constant *M1Init = GetTorInit(M1Tors);
 239     new GlobalVariable(M1Init->getType(), false, GlobalValue::AppendingLinkage,
 240                        M1Init, GlobalName, M1);
 241   }
 242
 243   GV = M2->getNamedGlobal(GlobalName);
 244   assert(GV && "Not a clone of M1?");
 245   assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
 246
 247   GV->eraseFromParent();
 248   if (!M2Tors.empty()) {
 249     Constant *M2Init = GetTorInit(M2Tors);
 250     new GlobalVariable(M2Init->getType(), false, GlobalValue::AppendingLinkage,
 251                        M2Init, GlobalName, M2);
 252   }
 253 }
 254
 255
 256 /// SplitFunctionsOutOfModule - Given a module and a list of functions in the
 257 /// module, split the functions OUT of the specified module, and place them in
 258 /// the new module.
 259 Module *
 260 llvm::SplitFunctionsOutOfModule(Module *M,
 261                                 const std::vector<Function*> &F,
 262                                 DenseMap<const Value*, Value*> &ValueMap) {
 263   // Make sure functions & globals are all external so that linkage
 264   // between the two modules will work.
 265   for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
 266     I->setLinkage(GlobalValue::ExternalLinkage);
 267   for (Module::global_iterator I = M->global_begin(), E = M->global_end();
 268        I != E; ++I) {
 269     if (I->hasName() && *I->getNameStart() == '\01')
 270       I->setName(I->getNameStart()+1, I->getNameLen()-1);
 271     I->setLinkage(GlobalValue::ExternalLinkage);
 272   }
 273
 274   DenseMap<const Value*, Value*> NewValueMap;
 275   Module *New = CloneModule(M, NewValueMap);
 276
 277   // Make sure global initializers exist only in the safe module (CBE->.so)
 278   for (Module::global_iterator I = New->global_begin(), E = New->global_end();
 279        I != E; ++I)
 280     I->setInitializer(0);  // Delete the initializer to make it external
 281
 282   // Remove the Test functions from the Safe module
 283   std::set<Function *> TestFunctions;
 284   for (unsigned i = 0, e = F.size(); i != e; ++i) {
 285     Function *TNOF = cast<Function>(ValueMap[F[i]]);
 286     DEBUG(std::cerr << "Removing function ");
 287     DEBUG(WriteAsOperand(std::cerr, TNOF, false));
 288     DEBUG(std::cerr << "\n");
 289     TestFunctions.insert(cast<Function>(NewValueMap[TNOF]));
 290     DeleteFunctionBody(TNOF);       // Function is now external in this module!
 291   }
 292
 293
 294   // Remove the Safe functions from the Test module
 295   for (Module::iterator I = New->begin(), E = New->end(); I != E; ++I)
 296     if (!TestFunctions.count(I))
 297       DeleteFunctionBody(I);
 298
 299
 300   // Make sure that there is a global ctor/dtor array in both halves of the
 301   // module if they both have static ctor/dtor functions.
 302   SplitStaticCtorDtor("llvm.global_ctors", M, New, NewValueMap);
 303   SplitStaticCtorDtor("llvm.global_dtors", M, New, NewValueMap);
 304
 305   return New;
 306 }
 307
 308 //===----------------------------------------------------------------------===//
 309 // Basic Block Extraction Code
 310 //===----------------------------------------------------------------------===//
 311
 312 /// ExtractMappedBlocksFromModule - Extract all but the specified basic blocks
 313 /// into their own functions.  The only detail is that M is actually a module
 314 /// cloned from the one the BBs are in, so some mapping needs to be performed.
 315 /// If this operation fails for some reason (ie the implementation is buggy),
 316 /// this function should return null, otherwise it returns a new Module.
 317 Module *BugDriver::ExtractMappedBlocksFromModule(const
 318                                                  std::vector<BasicBlock*> &BBs,
 319                                                  Module *M) {
 320   char *ExtraArg = NULL;
 321
 322   sys::Path uniqueFilename("bugpoint-extractblocks");
 323   std::string ErrMsg;
 324   if (uniqueFilename.createTemporaryFileOnDisk(true, &ErrMsg)) {
 325     std::cout << "*** Basic Block extraction failed!\n";
 326     std::cerr << "Error creating temporary file: " << ErrMsg << "\n";
 327     M = swapProgramIn(M);
 328     EmitProgressBitcode("basicblockextractfail", true);
 329     swapProgramIn(M);
 330     return 0;
 331   }
 332   sys::RemoveFileOnSignal(uniqueFilename);
 333
 334   std::ofstream BlocksToNotExtractFile(uniqueFilename.c_str());
 335   if (!BlocksToNotExtractFile) {
 336     std::cout << "*** Basic Block extraction failed!\n";
 337     std::cerr << "Error writing list of blocks to not extract: " << ErrMsg
 338               << "\n";
 339     M = swapProgramIn(M);
 340     EmitProgressBitcode("basicblockextractfail", true);
 341     swapProgramIn(M);
 342     return 0;
 343   }
 344   for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
 345        I != E; ++I) {
 346     BasicBlock *BB = *I;
 347     // If the BB doesn't have a name, give it one so we have something to key
 348     // off of.
 349     if (!BB->hasName()) BB->setName("tmpbb");
 350     BlocksToNotExtractFile << BB->getParent()->getName() << " "
 351                            << BB->getName() << "\n";
 352   }
 353   BlocksToNotExtractFile.close();
 354
 355   const char *uniqueFN = uniqueFilename.c_str();
 356   ExtraArg = (char*)malloc(23 + strlen(uniqueFN));
 357   strcat(strcpy(ExtraArg, "--extract-blocks-file="), uniqueFN);
 358
 359   std::vector<const PassInfo*> PI;
 360   std::vector<BasicBlock *> EmptyBBs; // This parameter is ignored.
 361   PI.push_back(getPI(createBlockExtractorPass(EmptyBBs)));
 362   Module *Ret = runPassesOn(M, PI, false, 1, &ExtraArg);
 363
 364   if (uniqueFilename.exists())
 365     uniqueFilename.eraseFromDisk(); // Free disk space
 366   free(ExtraArg);
 367
 368   if (Ret == 0) {
 369     std::cout << "*** Basic Block extraction failed, please report a bug!\n";
 370     M = swapProgramIn(M);
 371     EmitProgressBitcode("basicblockextractfail", true);
 372     swapProgramIn(M);
 373   }
 374   return Ret;
 375 }