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//===- ExtractFunction.cpp - Extract a function from Program --------------===//
// The LLVM Compiler Infrastructure
// This file was developed by the LLVM research group and 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/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/FunctionUtils.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/FileUtilities.h"
#include <set>
#include <iostream>
using namespace llvm;
namespace llvm {
bool DisableSimplifyCFG = false;
} // 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"));
/// 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) const {
Module *Result = CloneModule(Program);
const BasicBlock *PBB = I->getParent();
const Function *PF = PBB->getParent();
Module::iterator RFI = Result->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() != Type::VoidTy)
// Remove the instruction from the program.
//writeProgramToFile("current.bc", Result);
// Spiff up the output a little bit.
PassManager Passes;
// Make sure that the appropriate target data is always used...
Passes.add(new TargetData(Result));
/// FIXME: If this used runPasses() like the methods below, we could get rid
/// of the -disable-* options!
if (Simplification > 1 && !NoDCE)
if (Simplification && !DisableSimplifyCFG)
Passes.add(createCFGSimplificationPass()); // Delete dead control flow
return Result;
static const PassInfo *getPI(Pass *P) {
const PassInfo *PI = P->getPassInfo();
delete P;
return PI;
/// 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<const PassInfo*> CleanupPasses;
if (MayModifySemantics)
Module *New = runPassesOn(M, CleanupPasses);
if (New == 0) {
std::cerr << "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<const PassInfo*> LoopExtractPasses;
Module *NewM = runPassesOn(M, LoopExtractPasses);
if (NewM == 0) {
Module *Old = swapProgramIn(M);
std::cout << "*** Loop extraction failed: ";
EmitProgressBytecode("loopextraction", true);
std::cout << "*** Sorry. :( Please report a bug!\n";
return 0;
// 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 0;
} 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;
for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
std::vector<Constant*> Elts;
Elts.push_back(ConstantInt::get(Type::Int32Ty, TorList[i].second));
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){
GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
if (!GV || GV->isDeclaration() || GV->hasInternalLinkage() ||
!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 = M2->getFunction(F->getName());
M2Tors.push_back(std::make_pair(F, Priority));
if (!M1Tors.empty()) {
Constant *M1Init = GetTorInit(M1Tors);
new GlobalVariable(M1Init->getType(), false, GlobalValue::AppendingLinkage,
M1Init, GlobalName, M1);
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(M2Init->getType(), false, GlobalValue::AppendingLinkage,
M2Init, GlobalName, M2);
/// 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) {
// 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)
Module *New = CloneModule(M);
// Make sure global initializers exist only in the safe module (CBE->.so)
for (Module::global_iterator I = New->global_begin(), E = New->global_end();
I != E; ++I)
I->setInitializer(0); // Delete the initializer to make it external
// Remove the Test functions from the Safe module
std::set<std::pair<std::string, const PointerType*> > TestFunctions;
for (unsigned i = 0, e = F.size(); i != e; ++i) {
TestFunctions.insert(std::make_pair(F[i]->getName(), F[i]->getType()));
Function *TNOF = M->getFunction(F[i]->getName());
assert(TNOF && "Function doesn't exist in module!");
assert(TNOF->getFunctionType() == F[i]->getFunctionType() && "wrong type?");
DEBUG(std::cerr << "Removing function " << F[i]->getName() << "\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(std::make_pair(I->getName(), I->getType())))
// 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);
SplitStaticCtorDtor("llvm.global_dtors", M, New);
return New;
// Basic Block Extraction Code
namespace {
std::vector<BasicBlock*> BlocksToNotExtract;
/// BlockExtractorPass - This pass is used by bugpoint to extract all blocks
/// from the module into their own functions except for those specified by the
/// BlocksToNotExtract list.
class BlockExtractorPass : public ModulePass {
bool runOnModule(Module &M);
static char ID; // Pass ID, replacement for typeid
BlockExtractorPass() : ModulePass((intptr_t)&ID) {}
char BlockExtractorPass::ID = 0;
XX("extract-bbs", "Extract Basic Blocks From Module (for bugpoint use)");
bool BlockExtractorPass::runOnModule(Module &M) {
std::set<BasicBlock*> TranslatedBlocksToNotExtract;
for (unsigned i = 0, e = BlocksToNotExtract.size(); i != e; ++i) {
BasicBlock *BB = BlocksToNotExtract[i];
Function *F = BB->getParent();
// Map the corresponding function in this module.
Function *MF = M.getFunction(F->getName());
// Figure out which index the basic block is in its function.
Function::iterator BBI = MF->begin();
std::advance(BBI, std::distance(F->begin(), Function::iterator(BB)));
// Now that we know which blocks to not extract, figure out which ones we WANT
// to extract.
std::vector<BasicBlock*> BlocksToExtract;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
if (!TranslatedBlocksToNotExtract.count(BB))
for (unsigned i = 0, e = BlocksToExtract.size(); i != e; ++i)
return !BlocksToExtract.empty();
/// 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) {
// Set the global list so that pass will be able to access it.
BlocksToNotExtract = BBs;
std::vector<const PassInfo*> PI;
PI.push_back(getPI(new BlockExtractorPass()));
Module *Ret = runPassesOn(M, PI);
if (Ret == 0) {
std::cout << "*** Basic Block extraction failed, please report a bug!\n";
M = swapProgramIn(M);
EmitProgressBytecode("basicblockextractfail", true);
return Ret;