424 lines
14 KiB
C++
424 lines
14 KiB
C++
//===- ExtractFunction.cpp - Extract a function from Program --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements several methods that are used to extract functions,
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// loops, or portions of a module from the rest of the module.
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//
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//===----------------------------------------------------------------------===//
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#include "BugDriver.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/LegacyPassManager.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Verifier.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/FileUtilities.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/Signals.h"
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#include "llvm/Support/ToolOutputFile.h"
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Transforms/Utils/CodeExtractor.h"
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#include <set>
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using namespace llvm;
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#define DEBUG_TYPE "bugpoint"
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namespace llvm {
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bool DisableSimplifyCFG = false;
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extern cl::opt<std::string> OutputPrefix;
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} // End llvm namespace
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namespace {
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cl::opt<bool> NoDCE("disable-dce",
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cl::desc("Do not use the -dce pass to reduce testcases"));
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cl::opt<bool, true>
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NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
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cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
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Function *globalInitUsesExternalBA(GlobalVariable *GV) {
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if (!GV->hasInitializer())
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return nullptr;
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Constant *I = GV->getInitializer();
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// walk the values used by the initializer
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// (and recurse into things like ConstantExpr)
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std::vector<Constant *> Todo;
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std::set<Constant *> Done;
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Todo.push_back(I);
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while (!Todo.empty()) {
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Constant *V = Todo.back();
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Todo.pop_back();
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Done.insert(V);
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if (BlockAddress *BA = dyn_cast<BlockAddress>(V)) {
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Function *F = BA->getFunction();
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if (F->isDeclaration())
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return F;
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}
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for (User::op_iterator i = V->op_begin(), e = V->op_end(); i != e; ++i) {
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Constant *C = dyn_cast<Constant>(*i);
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if (C && !isa<GlobalValue>(C) && !Done.count(C))
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Todo.push_back(C);
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}
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}
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return nullptr;
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}
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} // end anonymous namespace
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std::unique_ptr<Module>
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BugDriver::deleteInstructionFromProgram(const Instruction *I,
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unsigned Simplification) {
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// FIXME, use vmap?
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Module *Clone = CloneModule(Program).release();
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const BasicBlock *PBB = I->getParent();
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const Function *PF = PBB->getParent();
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Module::iterator RFI = Clone->begin(); // Get iterator to corresponding fn
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std::advance(
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RFI, std::distance(PF->getParent()->begin(), Module::const_iterator(PF)));
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Function::iterator RBI = RFI->begin(); // Get iterator to corresponding BB
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std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB)));
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BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
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std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I)));
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Instruction *TheInst = &*RI; // Got the corresponding instruction!
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// If this instruction produces a value, replace any users with null values
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if (!TheInst->getType()->isVoidTy())
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TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
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// Remove the instruction from the program.
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TheInst->getParent()->getInstList().erase(TheInst);
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// Spiff up the output a little bit.
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std::vector<std::string> Passes;
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/// Can we get rid of the -disable-* options?
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if (Simplification > 1 && !NoDCE)
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Passes.push_back("dce");
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if (Simplification && !DisableSimplifyCFG)
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Passes.push_back("simplifycfg"); // Delete dead control flow
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Passes.push_back("verify");
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std::unique_ptr<Module> New = runPassesOn(Clone, Passes);
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delete Clone;
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if (!New) {
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errs() << "Instruction removal failed. Sorry. :( Please report a bug!\n";
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exit(1);
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}
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return New;
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}
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std::unique_ptr<Module>
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BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
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// Make all functions external, so GlobalDCE doesn't delete them...
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for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
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I->setLinkage(GlobalValue::ExternalLinkage);
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std::vector<std::string> CleanupPasses;
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CleanupPasses.push_back("globaldce");
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if (MayModifySemantics)
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CleanupPasses.push_back("deadarghaX0r");
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else
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CleanupPasses.push_back("deadargelim");
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std::unique_ptr<Module> New = runPassesOn(M, CleanupPasses);
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if (!New) {
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errs() << "Final cleanups failed. Sorry. :( Please report a bug!\n";
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return nullptr;
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}
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delete M;
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return New;
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}
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std::unique_ptr<Module> BugDriver::extractLoop(Module *M) {
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std::vector<std::string> LoopExtractPasses;
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LoopExtractPasses.push_back("loop-extract-single");
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std::unique_ptr<Module> NewM = runPassesOn(M, LoopExtractPasses);
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if (!NewM) {
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outs() << "*** Loop extraction failed: ";
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EmitProgressBitcode(M, "loopextraction", true);
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outs() << "*** Sorry. :( Please report a bug!\n";
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return nullptr;
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}
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// Check to see if we created any new functions. If not, no loops were
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// extracted and we should return null. Limit the number of loops we extract
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// to avoid taking forever.
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static unsigned NumExtracted = 32;
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if (M->size() == NewM->size() || --NumExtracted == 0) {
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return nullptr;
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} else {
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assert(M->size() < NewM->size() && "Loop extract removed functions?");
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Module::iterator MI = NewM->begin();
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for (unsigned i = 0, e = M->size(); i != e; ++i)
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++MI;
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}
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return NewM;
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}
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static void eliminateAliases(GlobalValue *GV) {
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// First, check whether a GlobalAlias references this definition.
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// GlobalAlias MAY NOT reference declarations.
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for (;;) {
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// 1. Find aliases
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SmallVector<GlobalAlias *, 1> aliases;
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Module *M = GV->getParent();
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for (Module::alias_iterator I = M->alias_begin(), E = M->alias_end();
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I != E; ++I)
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if (I->getAliasee()->stripPointerCasts() == GV)
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aliases.push_back(&*I);
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if (aliases.empty())
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break;
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// 2. Resolve aliases
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for (unsigned i = 0, e = aliases.size(); i < e; ++i) {
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aliases[i]->replaceAllUsesWith(aliases[i]->getAliasee());
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aliases[i]->eraseFromParent();
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}
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// 3. Repeat until no more aliases found; there might
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// be an alias to an alias...
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}
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}
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//
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// DeleteGlobalInitializer - "Remove" the global variable by deleting its
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// initializer,
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// making it external.
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//
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void llvm::DeleteGlobalInitializer(GlobalVariable *GV) {
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eliminateAliases(GV);
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GV->setInitializer(nullptr);
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GV->setComdat(nullptr);
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}
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// DeleteFunctionBody - "Remove" the function by deleting all of its basic
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// blocks, making it external.
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//
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void llvm::DeleteFunctionBody(Function *F) {
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eliminateAliases(F);
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// Function declarations can't have comdats.
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F->setComdat(nullptr);
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// delete the body of the function...
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F->deleteBody();
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assert(F->isDeclaration() && "This didn't make the function external!");
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}
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/// GetTorInit - Given a list of entries for static ctors/dtors, return them
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/// as a constant array.
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static Constant *GetTorInit(std::vector<std::pair<Function *, int>> &TorList) {
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assert(!TorList.empty() && "Don't create empty tor list!");
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std::vector<Constant *> ArrayElts;
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Type *Int32Ty = Type::getInt32Ty(TorList[0].first->getContext());
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StructType *STy = StructType::get(Int32Ty, TorList[0].first->getType());
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for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
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Constant *Elts[] = {ConstantInt::get(Int32Ty, TorList[i].second),
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TorList[i].first};
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ArrayElts.push_back(ConstantStruct::get(STy, Elts));
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}
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return ConstantArray::get(
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ArrayType::get(ArrayElts[0]->getType(), ArrayElts.size()), ArrayElts);
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}
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/// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
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/// M1 has all of the global variables. If M2 contains any functions that are
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/// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
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/// prune appropriate entries out of M1s list.
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static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
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ValueToValueMapTy &VMap) {
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GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
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if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() || !GV->use_empty())
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return;
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std::vector<std::pair<Function *, int>> M1Tors, M2Tors;
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ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
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if (!InitList)
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return;
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for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
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if (ConstantStruct *CS =
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dyn_cast<ConstantStruct>(InitList->getOperand(i))) {
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if (CS->getNumOperands() != 2)
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return; // Not array of 2-element structs.
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if (CS->getOperand(1)->isNullValue())
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break; // Found a null terminator, stop here.
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ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
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int Priority = CI ? CI->getSExtValue() : 0;
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Constant *FP = CS->getOperand(1);
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if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
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if (CE->isCast())
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FP = CE->getOperand(0);
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if (Function *F = dyn_cast<Function>(FP)) {
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if (!F->isDeclaration())
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M1Tors.push_back(std::make_pair(F, Priority));
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else {
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// Map to M2's version of the function.
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F = cast<Function>(VMap[F]);
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M2Tors.push_back(std::make_pair(F, Priority));
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}
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}
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}
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}
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GV->eraseFromParent();
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if (!M1Tors.empty()) {
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Constant *M1Init = GetTorInit(M1Tors);
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new GlobalVariable(*M1, M1Init->getType(), false,
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GlobalValue::AppendingLinkage, M1Init, GlobalName);
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}
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GV = M2->getNamedGlobal(GlobalName);
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assert(GV && "Not a clone of M1?");
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assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
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GV->eraseFromParent();
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if (!M2Tors.empty()) {
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Constant *M2Init = GetTorInit(M2Tors);
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new GlobalVariable(*M2, M2Init->getType(), false,
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GlobalValue::AppendingLinkage, M2Init, GlobalName);
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}
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}
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std::unique_ptr<Module>
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llvm::SplitFunctionsOutOfModule(Module *M, const std::vector<Function *> &F,
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ValueToValueMapTy &VMap) {
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// Make sure functions & globals are all external so that linkage
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// between the two modules will work.
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for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
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I->setLinkage(GlobalValue::ExternalLinkage);
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for (Module::global_iterator I = M->global_begin(), E = M->global_end();
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I != E; ++I) {
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if (I->hasName() && I->getName()[0] == '\01')
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I->setName(I->getName().substr(1));
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I->setLinkage(GlobalValue::ExternalLinkage);
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}
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ValueToValueMapTy NewVMap;
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std::unique_ptr<Module> New = CloneModule(M, NewVMap);
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// Remove the Test functions from the Safe module
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std::set<Function *> TestFunctions;
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for (unsigned i = 0, e = F.size(); i != e; ++i) {
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Function *TNOF = cast<Function>(VMap[F[i]]);
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DEBUG(errs() << "Removing function ");
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DEBUG(TNOF->printAsOperand(errs(), false));
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DEBUG(errs() << "\n");
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TestFunctions.insert(cast<Function>(NewVMap[TNOF]));
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DeleteFunctionBody(TNOF); // Function is now external in this module!
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}
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// Remove the Safe functions from the Test module
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for (Function &I : *New)
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if (!TestFunctions.count(&I))
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DeleteFunctionBody(&I);
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// Try to split the global initializers evenly
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for (GlobalVariable &I : M->globals()) {
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GlobalVariable *GV = cast<GlobalVariable>(NewVMap[&I]);
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if (Function *TestFn = globalInitUsesExternalBA(&I)) {
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if (Function *SafeFn = globalInitUsesExternalBA(GV)) {
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errs() << "*** Error: when reducing functions, encountered "
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"the global '";
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GV->printAsOperand(errs(), false);
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errs() << "' with an initializer that references blockaddresses "
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"from safe function '"
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<< SafeFn->getName() << "' and from test function '"
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<< TestFn->getName() << "'.\n";
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exit(1);
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}
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DeleteGlobalInitializer(&I); // Delete the initializer to make it external
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} else {
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// If we keep it in the safe module, then delete it in the test module
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DeleteGlobalInitializer(GV);
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}
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}
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// Make sure that there is a global ctor/dtor array in both halves of the
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// module if they both have static ctor/dtor functions.
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SplitStaticCtorDtor("llvm.global_ctors", M, New.get(), NewVMap);
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SplitStaticCtorDtor("llvm.global_dtors", M, New.get(), NewVMap);
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return New;
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}
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//===----------------------------------------------------------------------===//
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// Basic Block Extraction Code
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//===----------------------------------------------------------------------===//
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std::unique_ptr<Module>
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BugDriver::extractMappedBlocksFromModule(const std::vector<BasicBlock *> &BBs,
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Module *M) {
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SmallString<128> Filename;
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int FD;
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std::error_code EC = sys::fs::createUniqueFile(
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OutputPrefix + "-extractblocks%%%%%%%", FD, Filename);
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if (EC) {
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outs() << "*** Basic Block extraction failed!\n";
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errs() << "Error creating temporary file: " << EC.message() << "\n";
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EmitProgressBitcode(M, "basicblockextractfail", true);
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return nullptr;
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}
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sys::RemoveFileOnSignal(Filename);
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tool_output_file BlocksToNotExtractFile(Filename.c_str(), FD);
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for (std::vector<BasicBlock *>::const_iterator I = BBs.begin(), E = BBs.end();
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I != E; ++I) {
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BasicBlock *BB = *I;
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// If the BB doesn't have a name, give it one so we have something to key
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// off of.
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if (!BB->hasName())
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BB->setName("tmpbb");
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BlocksToNotExtractFile.os() << BB->getParent()->getName() << " "
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<< BB->getName() << "\n";
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}
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BlocksToNotExtractFile.os().close();
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if (BlocksToNotExtractFile.os().has_error()) {
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errs() << "Error writing list of blocks to not extract\n";
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EmitProgressBitcode(M, "basicblockextractfail", true);
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BlocksToNotExtractFile.os().clear_error();
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return nullptr;
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}
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BlocksToNotExtractFile.keep();
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std::string uniqueFN = "--extract-blocks-file=";
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uniqueFN += Filename.str();
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const char *ExtraArg = uniqueFN.c_str();
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std::vector<std::string> PI;
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PI.push_back("extract-blocks");
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std::unique_ptr<Module> Ret = runPassesOn(M, PI, 1, &ExtraArg);
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sys::fs::remove(Filename.c_str());
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if (!Ret) {
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outs() << "*** Basic Block extraction failed, please report a bug!\n";
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EmitProgressBitcode(M, "basicblockextractfail", true);
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}
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return Ret;
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}
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