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