ExtractFunction.cpp revision 296417
1193323Sed//===- ExtractFunction.cpp - Extract a function from Program --------------===// 2193323Sed// 3193323Sed// The LLVM Compiler Infrastructure 4193323Sed// 5193323Sed// This file is distributed under the University of Illinois Open Source 6193323Sed// License. See LICENSE.TXT for details. 7193323Sed// 8193323Sed//===----------------------------------------------------------------------===// 9193323Sed// 10193323Sed// This file implements several methods that are used to extract functions, 11193323Sed// loops, or portions of a module from the rest of the module. 12193323Sed// 13193323Sed//===----------------------------------------------------------------------===// 14193323Sed 15193323Sed#include "BugDriver.h" 16249423Sdim#include "llvm/IR/Constants.h" 17249423Sdim#include "llvm/IR/DataLayout.h" 18249423Sdim#include "llvm/IR/DerivedTypes.h" 19249423Sdim#include "llvm/IR/LLVMContext.h" 20288943Sdim#include "llvm/IR/LegacyPassManager.h" 21249423Sdim#include "llvm/IR/Module.h" 22276479Sdim#include "llvm/IR/Verifier.h" 23249423Sdim#include "llvm/Pass.h" 24193323Sed#include "llvm/Support/CommandLine.h" 25193323Sed#include "llvm/Support/Debug.h" 26193323Sed#include "llvm/Support/FileUtilities.h" 27218885Sdim#include "llvm/Support/Path.h" 28218885Sdim#include "llvm/Support/Signals.h" 29249423Sdim#include "llvm/Support/ToolOutputFile.h" 30249423Sdim#include "llvm/Transforms/IPO.h" 31249423Sdim#include "llvm/Transforms/Scalar.h" 32249423Sdim#include "llvm/Transforms/Utils/Cloning.h" 33249423Sdim#include "llvm/Transforms/Utils/CodeExtractor.h" 34193323Sed#include <set> 35193323Sedusing namespace llvm; 36193323Sed 37276479Sdim#define DEBUG_TYPE "bugpoint" 38276479Sdim 39193323Sednamespace llvm { 40193323Sed bool DisableSimplifyCFG = false; 41198090Srdivacky extern cl::opt<std::string> OutputPrefix; 42193323Sed} // End llvm namespace 43193323Sed 44193323Sednamespace { 45193323Sed cl::opt<bool> 46193323Sed NoDCE ("disable-dce", 47193323Sed cl::desc("Do not use the -dce pass to reduce testcases")); 48193323Sed cl::opt<bool, true> 49193323Sed NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG), 50193323Sed cl::desc("Do not use the -simplifycfg pass to reduce testcases")); 51193323Sed 52234353Sdim Function* globalInitUsesExternalBA(GlobalVariable* GV) { 53234353Sdim if (!GV->hasInitializer()) 54276479Sdim return nullptr; 55234353Sdim 56234353Sdim Constant *I = GV->getInitializer(); 57234353Sdim 58234353Sdim // walk the values used by the initializer 59234353Sdim // (and recurse into things like ConstantExpr) 60234353Sdim std::vector<Constant*> Todo; 61234353Sdim std::set<Constant*> Done; 62234353Sdim Todo.push_back(I); 63234353Sdim 64234353Sdim while (!Todo.empty()) { 65234353Sdim Constant* V = Todo.back(); 66234353Sdim Todo.pop_back(); 67234353Sdim Done.insert(V); 68234353Sdim 69234353Sdim if (BlockAddress *BA = dyn_cast<BlockAddress>(V)) { 70234353Sdim Function *F = BA->getFunction(); 71234353Sdim if (F->isDeclaration()) 72234353Sdim return F; 73234353Sdim } 74234353Sdim 75234353Sdim for (User::op_iterator i = V->op_begin(), e = V->op_end(); i != e; ++i) { 76234353Sdim Constant *C = dyn_cast<Constant>(*i); 77234353Sdim if (C && !isa<GlobalValue>(C) && !Done.count(C)) 78234353Sdim Todo.push_back(C); 79234353Sdim } 80234353Sdim } 81276479Sdim return nullptr; 82234353Sdim } 83234353Sdim} // end anonymous namespace 84234353Sdim 85280031Sdimstd::unique_ptr<Module> 86280031SdimBugDriver::deleteInstructionFromProgram(const Instruction *I, 87280031Sdim unsigned Simplification) { 88212793Sdim // FIXME, use vmap? 89296417Sdim Module *Clone = CloneModule(Program).release(); 90193323Sed 91193323Sed const BasicBlock *PBB = I->getParent(); 92193323Sed const Function *PF = PBB->getParent(); 93193323Sed 94212793Sdim Module::iterator RFI = Clone->begin(); // Get iterator to corresponding fn 95193323Sed std::advance(RFI, std::distance(PF->getParent()->begin(), 96193323Sed Module::const_iterator(PF))); 97193323Sed 98193323Sed Function::iterator RBI = RFI->begin(); // Get iterator to corresponding BB 99193323Sed std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB))); 100193323Sed 101193323Sed BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst 102193323Sed std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I))); 103296417Sdim Instruction *TheInst = &*RI; // Got the corresponding instruction! 104193323Sed 105193323Sed // If this instruction produces a value, replace any users with null values 106210006Srdivacky if (!TheInst->getType()->isVoidTy()) 107193323Sed TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType())); 108193323Sed 109193323Sed // Remove the instruction from the program. 110193323Sed TheInst->getParent()->getInstList().erase(TheInst); 111193323Sed 112193323Sed // Spiff up the output a little bit. 113212793Sdim std::vector<std::string> Passes; 114193323Sed 115212793Sdim /// Can we get rid of the -disable-* options? 116193323Sed if (Simplification > 1 && !NoDCE) 117212793Sdim Passes.push_back("dce"); 118193323Sed if (Simplification && !DisableSimplifyCFG) 119212793Sdim Passes.push_back("simplifycfg"); // Delete dead control flow 120193323Sed 121212793Sdim Passes.push_back("verify"); 122280031Sdim std::unique_ptr<Module> New = runPassesOn(Clone, Passes); 123212793Sdim delete Clone; 124212793Sdim if (!New) { 125212793Sdim errs() << "Instruction removal failed. Sorry. :( Please report a bug!\n"; 126212793Sdim exit(1); 127212793Sdim } 128212793Sdim return New; 129193323Sed} 130193323Sed 131280031Sdimstd::unique_ptr<Module> 132280031SdimBugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) { 133193323Sed // Make all functions external, so GlobalDCE doesn't delete them... 134193323Sed for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) 135193323Sed I->setLinkage(GlobalValue::ExternalLinkage); 136193323Sed 137212793Sdim std::vector<std::string> CleanupPasses; 138212793Sdim CleanupPasses.push_back("globaldce"); 139193323Sed 140193323Sed if (MayModifySemantics) 141212793Sdim CleanupPasses.push_back("deadarghaX0r"); 142193323Sed else 143212793Sdim CleanupPasses.push_back("deadargelim"); 144193323Sed 145280031Sdim std::unique_ptr<Module> New = runPassesOn(M, CleanupPasses); 146276479Sdim if (!New) { 147198090Srdivacky errs() << "Final cleanups failed. Sorry. :( Please report a bug!\n"; 148280031Sdim return nullptr; 149193323Sed } 150193323Sed delete M; 151193323Sed return New; 152193323Sed} 153193323Sed 154280031Sdimstd::unique_ptr<Module> BugDriver::extractLoop(Module *M) { 155212793Sdim std::vector<std::string> LoopExtractPasses; 156212793Sdim LoopExtractPasses.push_back("loop-extract-single"); 157193323Sed 158280031Sdim std::unique_ptr<Module> NewM = runPassesOn(M, LoopExtractPasses); 159276479Sdim if (!NewM) { 160198090Srdivacky outs() << "*** Loop extraction failed: "; 161212793Sdim EmitProgressBitcode(M, "loopextraction", true); 162198090Srdivacky outs() << "*** Sorry. :( Please report a bug!\n"; 163276479Sdim return nullptr; 164193323Sed } 165193323Sed 166193323Sed // Check to see if we created any new functions. If not, no loops were 167193323Sed // extracted and we should return null. Limit the number of loops we extract 168193323Sed // to avoid taking forever. 169193323Sed static unsigned NumExtracted = 32; 170193323Sed if (M->size() == NewM->size() || --NumExtracted == 0) { 171276479Sdim return nullptr; 172193323Sed } else { 173193323Sed assert(M->size() < NewM->size() && "Loop extract removed functions?"); 174193323Sed Module::iterator MI = NewM->begin(); 175193323Sed for (unsigned i = 0, e = M->size(); i != e; ++i) 176193323Sed ++MI; 177193323Sed } 178193323Sed 179193323Sed return NewM; 180193323Sed} 181193323Sed 182296417Sdimstatic void eliminateAliases(GlobalValue *GV) { 183296417Sdim // First, check whether a GlobalAlias references this definition. 184296417Sdim // GlobalAlias MAY NOT reference declarations. 185296417Sdim for (;;) { 186296417Sdim // 1. Find aliases 187296417Sdim SmallVector<GlobalAlias*,1> aliases; 188296417Sdim Module *M = GV->getParent(); 189296417Sdim for (Module::alias_iterator I=M->alias_begin(), E=M->alias_end(); I!=E; ++I) 190296417Sdim if (I->getAliasee()->stripPointerCasts() == GV) 191296417Sdim aliases.push_back(&*I); 192296417Sdim if (aliases.empty()) 193296417Sdim break; 194296417Sdim // 2. Resolve aliases 195296417Sdim for (unsigned i=0, e=aliases.size(); i<e; ++i) { 196296417Sdim aliases[i]->replaceAllUsesWith(aliases[i]->getAliasee()); 197296417Sdim aliases[i]->eraseFromParent(); 198296417Sdim } 199296417Sdim // 3. Repeat until no more aliases found; there might 200296417Sdim // be an alias to an alias... 201296417Sdim } 202296417Sdim} 203193323Sed 204296417Sdim// 205296417Sdim// DeleteGlobalInitializer - "Remove" the global variable by deleting its initializer, 206296417Sdim// making it external. 207296417Sdim// 208296417Sdimvoid llvm::DeleteGlobalInitializer(GlobalVariable *GV) { 209296417Sdim eliminateAliases(GV); 210296417Sdim GV->setInitializer(nullptr); 211296417Sdim} 212296417Sdim 213193323Sed// DeleteFunctionBody - "Remove" the function by deleting all of its basic 214193323Sed// blocks, making it external. 215193323Sed// 216193323Sedvoid llvm::DeleteFunctionBody(Function *F) { 217296417Sdim eliminateAliases(F); 218296417Sdim 219193323Sed // delete the body of the function... 220193323Sed F->deleteBody(); 221193323Sed assert(F->isDeclaration() && "This didn't make the function external!"); 222193323Sed} 223193323Sed 224193323Sed/// GetTorInit - Given a list of entries for static ctors/dtors, return them 225193323Sed/// as a constant array. 226193323Sedstatic Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) { 227193323Sed assert(!TorList.empty() && "Don't create empty tor list!"); 228193323Sed std::vector<Constant*> ArrayElts; 229224133Sdim Type *Int32Ty = Type::getInt32Ty(TorList[0].first->getContext()); 230288943Sdim 231226584Sdim StructType *STy = 232288943Sdim StructType::get(Int32Ty, TorList[0].first->getType(), nullptr); 233193323Sed for (unsigned i = 0, e = TorList.size(); i != e; ++i) { 234224133Sdim Constant *Elts[] = { 235224133Sdim ConstantInt::get(Int32Ty, TorList[i].second), 236224133Sdim TorList[i].first 237224133Sdim }; 238224133Sdim ArrayElts.push_back(ConstantStruct::get(STy, Elts)); 239193323Sed } 240193323Sed return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(), 241193323Sed ArrayElts.size()), 242193323Sed ArrayElts); 243193323Sed} 244193323Sed 245193323Sed/// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and 246193323Sed/// M1 has all of the global variables. If M2 contains any functions that are 247193323Sed/// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and 248193323Sed/// prune appropriate entries out of M1s list. 249193323Sedstatic void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2, 250218885Sdim ValueToValueMapTy &VMap) { 251193323Sed GlobalVariable *GV = M1->getNamedGlobal(GlobalName); 252193323Sed if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() || 253193323Sed !GV->use_empty()) return; 254193323Sed 255193323Sed std::vector<std::pair<Function*, int> > M1Tors, M2Tors; 256193323Sed ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer()); 257193323Sed if (!InitList) return; 258193323Sed 259193323Sed for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) { 260193323Sed if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){ 261193323Sed if (CS->getNumOperands() != 2) return; // Not array of 2-element structs. 262193323Sed 263193323Sed if (CS->getOperand(1)->isNullValue()) 264193323Sed break; // Found a null terminator, stop here. 265193323Sed 266193323Sed ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0)); 267193323Sed int Priority = CI ? CI->getSExtValue() : 0; 268193323Sed 269193323Sed Constant *FP = CS->getOperand(1); 270193323Sed if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP)) 271193323Sed if (CE->isCast()) 272193323Sed FP = CE->getOperand(0); 273193323Sed if (Function *F = dyn_cast<Function>(FP)) { 274193323Sed if (!F->isDeclaration()) 275193323Sed M1Tors.push_back(std::make_pair(F, Priority)); 276193323Sed else { 277193323Sed // Map to M2's version of the function. 278210006Srdivacky F = cast<Function>(VMap[F]); 279193323Sed M2Tors.push_back(std::make_pair(F, Priority)); 280193323Sed } 281193323Sed } 282193323Sed } 283193323Sed } 284193323Sed 285193323Sed GV->eraseFromParent(); 286193323Sed if (!M1Tors.empty()) { 287193323Sed Constant *M1Init = GetTorInit(M1Tors); 288198090Srdivacky new GlobalVariable(*M1, M1Init->getType(), false, 289198090Srdivacky GlobalValue::AppendingLinkage, 290198090Srdivacky M1Init, GlobalName); 291193323Sed } 292193323Sed 293193323Sed GV = M2->getNamedGlobal(GlobalName); 294193323Sed assert(GV && "Not a clone of M1?"); 295193323Sed assert(GV->use_empty() && "llvm.ctors shouldn't have uses!"); 296193323Sed 297193323Sed GV->eraseFromParent(); 298193323Sed if (!M2Tors.empty()) { 299193323Sed Constant *M2Init = GetTorInit(M2Tors); 300198090Srdivacky new GlobalVariable(*M2, M2Init->getType(), false, 301198090Srdivacky GlobalValue::AppendingLinkage, 302198090Srdivacky M2Init, GlobalName); 303193323Sed } 304193323Sed} 305193323Sed 306296417Sdimstd::unique_ptr<Module> 307296417Sdimllvm::SplitFunctionsOutOfModule(Module *M, const std::vector<Function *> &F, 308218885Sdim ValueToValueMapTy &VMap) { 309193323Sed // Make sure functions & globals are all external so that linkage 310193323Sed // between the two modules will work. 311193323Sed for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) 312193323Sed I->setLinkage(GlobalValue::ExternalLinkage); 313193323Sed for (Module::global_iterator I = M->global_begin(), E = M->global_end(); 314193323Sed I != E; ++I) { 315198090Srdivacky if (I->hasName() && I->getName()[0] == '\01') 316198090Srdivacky I->setName(I->getName().substr(1)); 317193323Sed I->setLinkage(GlobalValue::ExternalLinkage); 318193323Sed } 319193323Sed 320218885Sdim ValueToValueMapTy NewVMap; 321296417Sdim std::unique_ptr<Module> New = CloneModule(M, NewVMap); 322193323Sed 323193323Sed // Remove the Test functions from the Safe module 324193323Sed std::set<Function *> TestFunctions; 325193323Sed for (unsigned i = 0, e = F.size(); i != e; ++i) { 326210006Srdivacky Function *TNOF = cast<Function>(VMap[F[i]]); 327198090Srdivacky DEBUG(errs() << "Removing function "); 328276479Sdim DEBUG(TNOF->printAsOperand(errs(), false)); 329198090Srdivacky DEBUG(errs() << "\n"); 330210006Srdivacky TestFunctions.insert(cast<Function>(NewVMap[TNOF])); 331193323Sed DeleteFunctionBody(TNOF); // Function is now external in this module! 332193323Sed } 333193323Sed 334193323Sed 335193323Sed // Remove the Safe functions from the Test module 336296417Sdim for (Function &I : *New) 337296417Sdim if (!TestFunctions.count(&I)) 338296417Sdim DeleteFunctionBody(&I); 339193323Sed 340234353Sdim // Try to split the global initializers evenly 341296417Sdim for (GlobalVariable &I : M->globals()) { 342296417Sdim GlobalVariable *GV = cast<GlobalVariable>(NewVMap[&I]); 343296417Sdim if (Function *TestFn = globalInitUsesExternalBA(&I)) { 344234353Sdim if (Function *SafeFn = globalInitUsesExternalBA(GV)) { 345234353Sdim errs() << "*** Error: when reducing functions, encountered " 346234353Sdim "the global '"; 347276479Sdim GV->printAsOperand(errs(), false); 348234353Sdim errs() << "' with an initializer that references blockaddresses " 349234353Sdim "from safe function '" << SafeFn->getName() 350234353Sdim << "' and from test function '" << TestFn->getName() << "'.\n"; 351234353Sdim exit(1); 352234353Sdim } 353296417Sdim DeleteGlobalInitializer(&I); // Delete the initializer to make it external 354234353Sdim } else { 355234353Sdim // If we keep it in the safe module, then delete it in the test module 356296417Sdim DeleteGlobalInitializer(GV); 357234353Sdim } 358234353Sdim } 359234353Sdim 360193323Sed // Make sure that there is a global ctor/dtor array in both halves of the 361193323Sed // module if they both have static ctor/dtor functions. 362296417Sdim SplitStaticCtorDtor("llvm.global_ctors", M, New.get(), NewVMap); 363296417Sdim SplitStaticCtorDtor("llvm.global_dtors", M, New.get(), NewVMap); 364296417Sdim 365193323Sed return New; 366193323Sed} 367193323Sed 368193323Sed//===----------------------------------------------------------------------===// 369193323Sed// Basic Block Extraction Code 370193323Sed//===----------------------------------------------------------------------===// 371193323Sed 372280031Sdimstd::unique_ptr<Module> 373280031SdimBugDriver::extractMappedBlocksFromModule(const std::vector<BasicBlock *> &BBs, 374280031Sdim Module *M) { 375261991Sdim SmallString<128> Filename; 376261991Sdim int FD; 377276479Sdim std::error_code EC = sys::fs::createUniqueFile( 378261991Sdim OutputPrefix + "-extractblocks%%%%%%%", FD, Filename); 379261991Sdim if (EC) { 380198090Srdivacky outs() << "*** Basic Block extraction failed!\n"; 381261991Sdim errs() << "Error creating temporary file: " << EC.message() << "\n"; 382212793Sdim EmitProgressBitcode(M, "basicblockextractfail", true); 383276479Sdim return nullptr; 384193323Sed } 385261991Sdim sys::RemoveFileOnSignal(Filename); 386193323Sed 387261991Sdim tool_output_file BlocksToNotExtractFile(Filename.c_str(), FD); 388193323Sed for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end(); 389193323Sed I != E; ++I) { 390193323Sed BasicBlock *BB = *I; 391193323Sed // If the BB doesn't have a name, give it one so we have something to key 392193323Sed // off of. 393193323Sed if (!BB->hasName()) BB->setName("tmpbb"); 394234353Sdim BlocksToNotExtractFile.os() << BB->getParent()->getName() << " " 395212793Sdim << BB->getName() << "\n"; 396193323Sed } 397212793Sdim BlocksToNotExtractFile.os().close(); 398212793Sdim if (BlocksToNotExtractFile.os().has_error()) { 399261991Sdim errs() << "Error writing list of blocks to not extract\n"; 400212793Sdim EmitProgressBitcode(M, "basicblockextractfail", true); 401212793Sdim BlocksToNotExtractFile.os().clear_error(); 402276479Sdim return nullptr; 403212793Sdim } 404212793Sdim BlocksToNotExtractFile.keep(); 405193323Sed 406261991Sdim std::string uniqueFN = "--extract-blocks-file="; 407261991Sdim uniqueFN += Filename.str(); 408203954Srdivacky const char *ExtraArg = uniqueFN.c_str(); 409193323Sed 410212793Sdim std::vector<std::string> PI; 411212793Sdim PI.push_back("extract-blocks"); 412280031Sdim std::unique_ptr<Module> Ret = runPassesOn(M, PI, false, 1, &ExtraArg); 413193323Sed 414261991Sdim sys::fs::remove(Filename.c_str()); 415193323Sed 416276479Sdim if (!Ret) { 417198090Srdivacky outs() << "*** Basic Block extraction failed, please report a bug!\n"; 418212793Sdim EmitProgressBitcode(M, "basicblockextractfail", true); 419193323Sed } 420193323Sed return Ret; 421193323Sed} 422