C++ iterator::getType方法代码示例

/// Handle a rare case where the disintegrated nodes instructions
/// no longer dominate all their uses. Not sure if this is really nessasary
void StructurizeCFG::rebuildSSA() {
  SSAUpdater Updater;
  for (const auto &BB : ParentRegion->blocks())
    for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
         II != IE; ++II) {

      bool Initialized = false;
      for (auto I = II->use_begin(), E = II->use_end(); I != E;) {
        Use &U = *I++;
        Instruction *User = cast<Instruction>(U.getUser());
        if (User->getParent() == BB) {
          continue;

        } else if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
          if (UserPN->getIncomingBlock(U) == BB)
            continue;
        }

        if (DT->dominates(II, User))
          continue;

        if (!Initialized) {
          Value *Undef = UndefValue::get(II->getType());
          Updater.Initialize(II->getType(), "");
          Updater.AddAvailableValue(&Func->getEntryBlock(), Undef);
          Updater.AddAvailableValue(BB, II);
          Initialized = true;
        }
        Updater.RewriteUseAfterInsertions(U);
      }
    }
}

void MemoryInstrumenter::checkFeatures(Module &M) {
  // Check whether any memory allocation function can
  // potentially be pointed by function pointers.
  // Also, all intrinsic functions will be called directly,
  // i.e. not via function pointers.
  for (Module::iterator F = M.begin(); F != M.end(); ++F) {
    if (DynAAUtils::IsMalloc(F) || F->isIntrinsic()) {
      for (Value::use_iterator UI = F->use_begin(); UI != F->use_end(); ++UI) {
        User *Usr = *UI;
        assert(isa<CallInst>(Usr) || isa<InvokeInst>(Usr));
        CallSite CS(cast<Instruction>(Usr));
        for (unsigned i = 0; i < CS.arg_size(); ++i)
          assert(CS.getArgument(i) != F);
      }
    }
  }

  // Check whether memory allocation functions are captured.
  for (Module::iterator F = M.begin(); F != M.end(); ++F) {
    // 0 is the return, 1 is the first parameter.
    if (F->isDeclaration() && F->doesNotAlias(0) && !DynAAUtils::IsMalloc(F)) {
      errs().changeColor(raw_ostream::RED);
      errs() << F->getName() << "'s return value is marked noalias, ";
      errs() << "but the function is not treated as malloc.\n";
      errs().resetColor();
    }
  }

  // Sequential types except pointer types shouldn't be used as the type of
  // an instruction, a function parameter, or a global variable.
  for (Module::global_iterator GI = M.global_begin(), E = M.global_end();
       GI != E; ++GI) {
    if (isa<SequentialType>(GI->getType()))
      assert(GI->getType()->isPointerTy());
  }
  for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
    for (Function::arg_iterator AI = F->arg_begin(); AI != F->arg_end(); ++AI) {
      if (isa<SequentialType>(AI->getType()))
        assert(AI->getType()->isPointerTy());
    }
  }
  for (Module::iterator F = M.begin(); F != M.end(); ++F) {
    for (Function::iterator BB = F->begin(); BB != F->end(); ++BB) {
      for (BasicBlock::iterator Ins = BB->begin(); Ins != BB->end(); ++Ins) {
        if (isa<SequentialType>(Ins->getType()))
          assert(Ins->getType()->isPointerTy());
      }
    }
  }

  // We don't support multi-process programs for now.
  if (!HookFork)
    assert(M.getFunction("fork") == NULL);
}

 virtual bool runOnFunction(Function& f)
 {
   CurrentFile::set(__FILE__);
   bool changed = false;
   // Make sure this is a function that we can use
   if (f.isDeclaration() /*|| !f.isDFFunction()*/ )
   {
     return changed ;
   }
   for(Function::iterator BB = f.begin(); BB != f.end(); ++BB)
   {
     begin:
     for(BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
     {
       if( !dynamic_cast<TerminatorInst*>(&*II) )
       {
         II->replaceAllUsesWith(UndefValue::get(II->getType()));
         II->eraseFromParent();
         goto begin;
       }
     }
   }
   changed = true;
   return changed;
 }

/// DeleteBasicBlock - remove the specified basic block from the program,
/// updating the callgraph to reflect any now-obsolete edges due to calls that
/// exist in the BB.
void PruneEH::DeleteBasicBlock(BasicBlock *BB) {
  assert(pred_begin(BB) == pred_end(BB) && "BB is not dead!");
  CallGraph &CG = getAnalysis<CallGraph>();

  CallGraphNode *CGN = CG[BB->getParent()];
  for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; ) {
    --I;
    if (CallInst *CI = dyn_cast<CallInst>(I)) {
      if (Function *Callee = CI->getCalledFunction())
        CGN->removeCallEdgeTo(CG[Callee]);
    } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
      if (Function *Callee = II->getCalledFunction())
        CGN->removeCallEdgeTo(CG[Callee]);
    }
    if (!I->use_empty())
      I->replaceAllUsesWith(UndefValue::get(I->getType()));
  }

  // Get the list of successors of this block.
  std::vector<BasicBlock*> Succs(succ_begin(BB), succ_end(BB));

  for (unsigned i = 0, e = Succs.size(); i != e; ++i)
    Succs[i]->removePredecessor(BB);

  BB->eraseFromParent();
}

void IntTest::pbzip2_like(Module &M) {
	TestBanner X("pbzip2-like");

	vector<StoreInst *> writes;
	Function *f_rand = M.getFunction("rand");
	assert(f_rand);
	Function *f_producer = M.getFunction("_Z8producerPv.SLICER");
	assert(f_producer);
	// Search along the CFG. We need to make sure reads and writes are in
	// a consistent order. 
	for (Function::iterator bb = f_producer->begin();
			bb != f_producer->end(); ++bb) {
		for (BasicBlock::iterator ins = bb->begin(); ins != bb->end(); ++ins) {
			if (CallInst *ci = dyn_cast<CallInst>(ins)) {
				if (ci->getCalledFunction() == f_rand) {
					for (BasicBlock::iterator j = bb->begin(); j != bb->end(); ++j) {
						if (StoreInst *si = dyn_cast<StoreInst>(j))
							writes.push_back(si);
					}
				}
			}
		}
	}
	errs() << "=== writes ===\n";
	for (size_t i = 0; i < writes.size(); ++i) {
		errs() << *writes[i] << "\n";
	}

	vector<LoadInst *> reads;
	Function *f_consumer = M.getFunction("_Z8consumerPv.SLICER");
	assert(f_consumer);
	for (Function::iterator bb = f_consumer->begin();
			bb != f_consumer->end(); ++bb) {
		for (BasicBlock::iterator ins = bb->begin(); ins != bb->end(); ++ins) {
			if (ins->getOpcode() == Instruction::Add &&
					ins->getType()->isIntegerTy(8)) {
				LoadInst *li = dyn_cast<LoadInst>(ins->getOperand(0));
				assert(li);
				reads.push_back(li);
			}
		}
	}
	errs() << "=== reads ===\n";
	for (size_t i = 0; i < reads.size(); ++i) {
		errs() << *reads[i] << "\n";
	}

	assert(writes.size() == reads.size());
	AliasAnalysis &AA = getAnalysis<AdvancedAlias>();
	for (size_t i = 0; i < writes.size(); ++i) {
		for (size_t j = i + 1; j < reads.size(); ++j) {
			errs() << "i = " << i << ", j = " << j << "... ";
			AliasAnalysis::AliasResult res = AA.alias(
					writes[i]->getPointerOperand(),
					reads[j]->getPointerOperand());
			assert(res == AliasAnalysis::NoAlias);
			print_pass(errs());
		}
	}
}

// Collect the list of loop induction variables with respect to which it might
// be possible to reroll the loop.
void LoopReroll::collectPossibleIVs(Loop *L,
                                    SmallInstructionVector &PossibleIVs) {
  BasicBlock *Header = L->getHeader();
  for (BasicBlock::iterator I = Header->begin(),
       IE = Header->getFirstInsertionPt(); I != IE; ++I) {
    if (!isa<PHINode>(I))
      continue;
    if (!I->getType()->isIntegerTy())
      continue;

    if (const SCEVAddRecExpr *PHISCEV =
        dyn_cast<SCEVAddRecExpr>(SE->getSCEV(I))) {
      if (PHISCEV->getLoop() != L)
        continue;
      if (!PHISCEV->isAffine())
        continue;
      if (const SCEVConstant *IncSCEV =
          dyn_cast<SCEVConstant>(PHISCEV->getStepRecurrence(*SE))) {
        if (!IncSCEV->getValue()->getValue().isStrictlyPositive())
          continue;
        if (IncSCEV->getValue()->uge(MaxInc))
          continue;

        DEBUG(dbgs() << "LRR: Possible IV: " << *I << " = " <<
              *PHISCEV << "\n");
        PossibleIVs.push_back(I);
      }
    }
  }
}

/// ChangeToUnreachable - Insert an unreachable instruction before the specified
/// instruction, making it and the rest of the code in the block dead.
static void ChangeToUnreachable(Instruction *I, bool UseLLVMTrap) {
  BasicBlock *BB = I->getParent();
  // Loop over all of the successors, removing BB's entry from any PHI
  // nodes.
  for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
    (*SI)->removePredecessor(BB);
  
  // Insert a call to llvm.trap right before this.  This turns the undefined
  // behavior into a hard fail instead of falling through into random code.
  if (UseLLVMTrap) {
    Function *TrapFn =
      Intrinsic::getDeclaration(BB->getParent()->getParent(), Intrinsic::trap);
    CallInst *CallTrap = CallInst::Create(TrapFn, "", I);
    CallTrap->setDebugLoc(I->getDebugLoc());
  }
  new UnreachableInst(I->getContext(), I);
  
  // All instructions after this are dead.
  BasicBlock::iterator BBI = I, BBE = BB->end();
  while (BBI != BBE) {
    if (!BBI->use_empty())
      BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
    BB->getInstList().erase(BBI++);
  }
}

/// \brief Analyze a basic block for its contribution to the inline cost.
///
/// This method walks the analyzer over every instruction in the given basic
/// block and accounts for their cost during inlining at this callsite. It
/// aborts early if the threshold has been exceeded or an impossible to inline
/// construct has been detected. It returns false if inlining is no longer
/// viable, and true if inlining remains viable.
bool CallAnalyzer::analyzeBlock(BasicBlock *BB,
                                SmallPtrSetImpl<const Value *> &EphValues) {
  for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
    // FIXME: Currently, the number of instructions in a function regardless of
    // our ability to simplify them during inline to constants or dead code,
    // are actually used by the vector bonus heuristic. As long as that's true,
    // we have to special case debug intrinsics here to prevent differences in
    // inlining due to debug symbols. Eventually, the number of unsimplified
    // instructions shouldn't factor into the cost computation, but until then,
    // hack around it here.
    if (isa<DbgInfoIntrinsic>(I))
      continue;

    // Skip ephemeral values.
    if (EphValues.count(I))
      continue;

    ++NumInstructions;
    if (isa<ExtractElementInst>(I) || I->getType()->isVectorTy())
      ++NumVectorInstructions;

    // If the instruction simplified to a constant, there is no cost to this
    // instruction. Visit the instructions using our InstVisitor to account for
    // all of the per-instruction logic. The visit tree returns true if we
    // consumed the instruction in any way, and false if the instruction's base
    // cost should count against inlining.
    if (Base::visit(I))
      ++NumInstructionsSimplified;
    else
      Cost += InlineConstants::InstrCost;

    // If the visit this instruction detected an uninlinable pattern, abort.
    if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca ||
        HasIndirectBr)
      return false;

    // If the caller is a recursive function then we don't want to inline
    // functions which allocate a lot of stack space because it would increase
    // the caller stack usage dramatically.
    if (IsCallerRecursive &&
        AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller)
      return false;

    if (NumVectorInstructions > NumInstructions/2)
      VectorBonus = FiftyPercentVectorBonus;
    else if (NumVectorInstructions > NumInstructions/10)
      VectorBonus = TenPercentVectorBonus;
    else
      VectorBonus = 0;

    // Check if we've past the threshold so we don't spin in huge basic
    // blocks that will never inline.
    if (Cost > (Threshold + VectorBonus))
      return false;
  }

  return true;
}

BasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB,
                                         ArrayRef<BasicBlock *> Preds,
                                         const char *Suffix, DominatorTree *DT,
                                         LoopInfo *LI, bool PreserveLCSSA) {
  // Do not attempt to split that which cannot be split.
  if (!BB->canSplitPredecessors())
    return nullptr;

  // For the landingpads we need to act a bit differently.
  // Delegate this work to the SplitLandingPadPredecessors.
  if (BB->isLandingPad()) {
    SmallVector<BasicBlock*, 2> NewBBs;
    std::string NewName = std::string(Suffix) + ".split-lp";

    SplitLandingPadPredecessors(BB, Preds, Suffix, NewName.c_str(), NewBBs, DT,
                                LI, PreserveLCSSA);
    return NewBBs[0];
  }

  // Create new basic block, insert right before the original block.
  BasicBlock *NewBB = BasicBlock::Create(
      BB->getContext(), BB->getName() + Suffix, BB->getParent(), BB);

  // The new block unconditionally branches to the old block.
  BranchInst *BI = BranchInst::Create(BB, NewBB);
  BI->setDebugLoc(BB->getFirstNonPHIOrDbg()->getDebugLoc());

  // Move the edges from Preds to point to NewBB instead of BB.
  for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
    // This is slightly more strict than necessary; the minimum requirement
    // is that there be no more than one indirectbr branching to BB. And
    // all BlockAddress uses would need to be updated.
    assert(!isa<IndirectBrInst>(Preds[i]->getTerminator()) &&
           "Cannot split an edge from an IndirectBrInst");
    Preds[i]->getTerminator()->replaceUsesOfWith(BB, NewBB);
  }

  // Insert a new PHI node into NewBB for every PHI node in BB and that new PHI
  // node becomes an incoming value for BB's phi node.  However, if the Preds
  // list is empty, we need to insert dummy entries into the PHI nodes in BB to
  // account for the newly created predecessor.
  if (Preds.empty()) {
    // Insert dummy values as the incoming value.
    for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++I)
      cast<PHINode>(I)->addIncoming(UndefValue::get(I->getType()), NewBB);
    return NewBB;
  }

  // Update DominatorTree, LoopInfo, and LCCSA analysis information.
  bool HasLoopExit = false;
  UpdateAnalysisInformation(BB, NewBB, Preds, DT, LI, PreserveLCSSA,
                            HasLoopExit);

  // Update the PHI nodes in BB with the values coming from NewBB.
  UpdatePHINodes(BB, NewBB, Preds, BI, HasLoopExit);
  return NewBB;
}

void MemoryInstrumenter::checkFeatures(Module &M) {
    // Check whether any memory allocation function can
    // potentially be pointed by function pointers.
    // Also, all intrinsic functions will be called directly,
    // i.e. not via function pointers.
    for (Module::iterator F = M.begin(); F != M.end(); ++F) {
        if (DynAAUtils::IsMalloc(F) || F->isIntrinsic()) {
            for (Value::use_iterator UI = F->use_begin(); UI != F->use_end(); ++UI) {
                User *Usr = *UI;
                assert(isa<CallInst>(Usr) || isa<InvokeInst>(Usr));
                CallSite CS(cast<Instruction>(Usr));
                for (unsigned i = 0; i < CS.arg_size(); ++i)
                    assert(CS.getArgument(i) != F);
            }
        }
    }

    // Check whether memory allocation functions are captured.
    for (Module::iterator F = M.begin(); F != M.end(); ++F) {
        // 0 is the return, 1 is the first parameter.
        if (F->isDeclaration() && F->doesNotAlias(0) && !DynAAUtils::IsMalloc(F)) {
            errs().changeColor(raw_ostream::RED);
            errs() << F->getName() << "'s return value is marked noalias, ";
            errs() << "but the function is not treated as malloc.\n";
            errs().resetColor();
        }
    }

    // Global variables shouldn't be of the array type.
    for (Module::global_iterator GI = M.global_begin(), E = M.global_end();
            GI != E; ++GI) {
        assert(!GI->getType()->isArrayTy());
    }
    // A function parameter or an instruction can be an array, but we don't
    // instrument such constructs for now. Issue a warning on such cases.
    for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
        for (Function::arg_iterator AI = F->arg_begin(); AI != F->arg_end(); ++AI) {
            if (AI->getType()->isArrayTy()) {
                errs().changeColor(raw_ostream::RED);
                errs() << F->getName() << ":" << *AI << " is an array\n";
                errs().resetColor();
            }
        }
    }
    for (Module::iterator F = M.begin(); F != M.end(); ++F) {
        for (Function::iterator BB = F->begin(); BB != F->end(); ++BB) {
            for (BasicBlock::iterator Ins = BB->begin(); Ins != BB->end(); ++Ins) {
                if (Ins->getType()->isArrayTy()) {
                    errs().changeColor(raw_ostream::RED);
                    errs() << F->getName() << ":" << *Ins << " is an array\n";
                    errs().resetColor();
                }
            }
        }
    }
}

// bypassSlowDivision - This optimization identifies DIV instructions that can
// be profitably bypassed and carried out with a shorter, faster divide.
bool llvm::bypassSlowDivision(Function &F,
                              Function::iterator &I,
                              const DenseMap<unsigned int, unsigned int> &BypassWidths) {
  DivCacheTy DivCache;

  bool MadeChange = false;
  for (BasicBlock::iterator J = I->begin(); J != I->end(); J++) {

    // Get instruction details
    unsigned Opcode = J->getOpcode();
    bool UseDivOp = Opcode == Instruction::SDiv || Opcode == Instruction::UDiv;
    bool UseRemOp = Opcode == Instruction::SRem || Opcode == Instruction::URem;
    bool UseSignedOp = Opcode == Instruction::SDiv ||
                       Opcode == Instruction::SRem;

    // Only optimize div or rem ops
    if (!UseDivOp && !UseRemOp)
      continue;

    // Skip division on vector types, only optimize integer instructions
    if (!J->getType()->isIntegerTy())
      continue;

    // Get bitwidth of div/rem instruction
    IntegerType *T = cast<IntegerType>(J->getType());
    unsigned int bitwidth = T->getBitWidth();

    // Continue if bitwidth is not bypassed
    DenseMap<unsigned int, unsigned int>::const_iterator BI = BypassWidths.find(bitwidth);
    if (BI == BypassWidths.end())
      continue;

    // Get type for div/rem instruction with bypass bitwidth
    IntegerType *BT = IntegerType::get(J->getContext(), BI->second);

    MadeChange |= reuseOrInsertFastDiv(F, I, J, BT, UseDivOp,
                                       UseSignedOp, DivCache);
  }

  return MadeChange;
}

/// DeleteBasicBlock - remove the specified basic block from the program,
/// updating the callgraph to reflect any now-obsolete edges due to calls that
/// exist in the BB.
void PruneEH::DeleteBasicBlock(BasicBlock *BB) {
  assert(pred_empty(BB) && "BB is not dead!");
  CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();

  Instruction *TokenInst = nullptr;

  CallGraphNode *CGN = CG[BB->getParent()];
  for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; ) {
    --I;

    if (I->getType()->isTokenTy()) {
      TokenInst = &*I;
      break;
    }

    if (auto CS = CallSite (&*I)) {
      const Function *Callee = CS.getCalledFunction();
      if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID()))
        CGN->removeCallEdgeFor(CS);
      else if (!Callee->isIntrinsic())
        CGN->removeCallEdgeFor(CS);
    }

    if (!I->use_empty())
      I->replaceAllUsesWith(UndefValue::get(I->getType()));
  }

  if (TokenInst) {
    if (!isa<TerminatorInst>(TokenInst))
      changeToUnreachable(TokenInst->getNextNode(), /*UseLLVMTrap=*/false);
  } else {
    // Get the list of successors of this block.
    std::vector<BasicBlock *> Succs(succ_begin(BB), succ_end(BB));

    for (unsigned i = 0, e = Succs.size(); i != e; ++i)
      Succs[i]->removePredecessor(BB);

    BB->eraseFromParent();
  }
}

/// Handle a rare case where the disintegrated nodes instructions
/// no longer dominate all their uses. Not sure if this is really nessasary
void StructurizeCFG::rebuildSSA() {
  SSAUpdater Updater;
  for (Region::block_iterator I = ParentRegion->block_begin(),
                              E = ParentRegion->block_end();
       I != E; ++I) {

    BasicBlock *BB = *I;
    for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
         II != IE; ++II) {

      bool Initialized = false;
      for (Use *I = &II->use_begin().getUse(), *Next; I; I = Next) {

        Next = I->getNext();

        Instruction *User = cast<Instruction>(I->getUser());
        if (User->getParent() == BB) {
          continue;

        } else if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
          if (UserPN->getIncomingBlock(*I) == BB)
            continue;
        }

        if (DT->dominates(II, User))
          continue;

        if (!Initialized) {
          Value *Undef = UndefValue::get(II->getType());
          Updater.Initialize(II->getType(), "");
          Updater.AddAvailableValue(&Func->getEntryBlock(), Undef);
          Updater.AddAvailableValue(BB, II);
          Initialized = true;
        }
        Updater.RewriteUseAfterInsertions(*I);
      }
    }
  }
}

bool SSIEverything::runOnFunction(Function &F) {
  SmallVector<Instruction *, 16> Insts;
  SSI &ssi = getAnalysis<SSI>();

  if (F.isDeclaration() || F.isIntrinsic()) return false;

  for (Function::iterator B = F.begin(), BE = F.end(); B != BE; ++B)
    for (BasicBlock::iterator I = B->begin(), E = B->end(); I != E; ++I)
      if (!I->getType()->isVoidTy())
        Insts.push_back(I);

  ssi.createSSI(Insts);
  return true;
}

/// ChangeToUnreachable - Insert an unreachable instruction before the specified
/// instruction, making it and the rest of the code in the block dead.
static void ChangeToUnreachable(Instruction *I) {
    BasicBlock *BB = I->getParent();
    // Loop over all of the successors, removing BB's entry from any PHI
    // nodes.
    for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
        (*SI)->removePredecessor(BB);

    new UnreachableInst(I);

    // All instructions after this are dead.
    BasicBlock::iterator BBI = I, BBE = BB->end();
    while (BBI != BBE) {
        if (!BBI->use_empty())
            BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
        BB->getInstList().erase(BBI++);
    }
}