C++ BinaryOperator::getName方法代码示例

Value *
ConstantOffsetExtractor::distributeExtsAndCloneChain(unsigned ChainIndex) {
  User *U = UserChain[ChainIndex];
  if (ChainIndex == 0) {
    assert(isa<ConstantInt>(U));
    // If U is a ConstantInt, applyExts will return a ConstantInt as well.
    return UserChain[ChainIndex] = cast<ConstantInt>(applyExts(U));
  }

  if (CastInst *Cast = dyn_cast<CastInst>(U)) {
    assert((isa<SExtInst>(Cast) || isa<ZExtInst>(Cast)) &&
           "We only traced into two types of CastInst: sext and zext");
    ExtInsts.push_back(Cast);
    UserChain[ChainIndex] = nullptr;
    return distributeExtsAndCloneChain(ChainIndex - 1);
  }

  // Function find only trace into BinaryOperator and CastInst.
  BinaryOperator *BO = cast<BinaryOperator>(U);
  // OpNo = which operand of BO is UserChain[ChainIndex - 1]
  unsigned OpNo = (BO->getOperand(0) == UserChain[ChainIndex - 1] ? 0 : 1);
  Value *TheOther = applyExts(BO->getOperand(1 - OpNo));
  Value *NextInChain = distributeExtsAndCloneChain(ChainIndex - 1);

  BinaryOperator *NewBO = nullptr;
  if (OpNo == 0) {
    NewBO = BinaryOperator::Create(BO->getOpcode(), NextInChain, TheOther,
                                   BO->getName(), IP);
  } else {
    NewBO = BinaryOperator::Create(BO->getOpcode(), TheOther, NextInChain,
                                   BO->getName(), IP);
  }
  return UserChain[ChainIndex] = NewBO;
}

/*
FindRoots()
  for each instruction I = ’R <- op, Ra, Rb’
    if op(I) not associative or commutative
       continue
    // I is a root unless R is a temporary
    //     (temporaries are only used once and by an instruction with the same operator)
    if NumUses(R) > 1 or op(Use(R)) != op(I)
       mark I as root, processed(root) = false
  order roots such that precedence of op(r$_i$) $\leq$ precedence of op(r$_{i+1}$)
  while roots not empty
    I = ’R <- op, Ra, Rb’ = Def(Pop(root))
    BalanceTree(I)
*/
bool findRoots(Function* f)
{
  bool changed = false;
  assert(f);
  std::vector<BinaryOperator*> roots;
  
  for(Function::iterator BB = f->begin(); BB != f->end(); ++BB)
  {
    for(BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
    {
      BinaryOperator* BO = dynamic_cast<BinaryOperator*>(&*II);
      if( BO and isCommutativeOperation(BO) and isAssociativeOperation(BO) )
      {
        if( getRealNumUses(BO) > 1 )
        {
          roots.push_back(BO);
          INTERNAL_MESSAGE("Root " << BO->getName() << " added for numUses > 1.\n");
        }
        else
        {
          for(Value::use_iterator UI = BO->use_begin(); UI != BO->use_end(); ++UI)
          {
            if( isDifferentOperation(BO, *UI)  )
            {
              roots.push_back(BO);
              INTERNAL_MESSAGE("Root " << BO->getName() << " added because it is different operation than " << (*UI)->getName() << "\n");
            } 
          }
        }
      }
    }
  }
  std::sort(roots.begin(), roots.end(), precedence_less_than);
  std::list<BinaryOperator*> root_queue;
  root_queue.resize(roots.size());
  std::copy(roots.begin(), roots.end(), root_queue.begin());
  std::map<Instruction*,bool> visitMap;
  int roots_balanced = 0;
  while( !root_queue.empty() )
  {
    BinaryOperator* BO = root_queue.front();
    root_queue.pop_front();
    bool root_changed = balanceTree(BO, visitMap, roots);
    if( root_changed )
      ++roots_balanced;
    changed = root_changed or changed;
  }
  std::stringstream ss;
  ss << "Attempted to balance " << roots.size() << " roots (";
  for(std::vector<BinaryOperator*>::iterator RI = roots.begin(); RI != roots.end(); ++RI)
  {
    if( RI != roots.begin() )
      ss << ", ";
    ss << getValueName((*RI));
  }
  ss << "), " << roots_balanced << " needed balancing.\n";
  LOG_MESSAGE1("Balancing", ss.str());
  return changed;
}

Value *ConstantOffsetExtractor::removeConstOffset(unsigned ChainIndex) {
  if (ChainIndex == 0) {
    assert(isa<ConstantInt>(UserChain[ChainIndex]));
    return ConstantInt::getNullValue(UserChain[ChainIndex]->getType());
  }

  BinaryOperator *BO = cast<BinaryOperator>(UserChain[ChainIndex]);
  unsigned OpNo = (BO->getOperand(0) == UserChain[ChainIndex - 1] ? 0 : 1);
  assert(BO->getOperand(OpNo) == UserChain[ChainIndex - 1]);
  Value *NextInChain = removeConstOffset(ChainIndex - 1);
  Value *TheOther = BO->getOperand(1 - OpNo);

  // If NextInChain is 0 and not the LHS of a sub, we can simplify the
  // sub-expression to be just TheOther.
  if (ConstantInt *CI = dyn_cast<ConstantInt>(NextInChain)) {
    if (CI->isZero() && !(BO->getOpcode() == Instruction::Sub && OpNo == 0))
      return TheOther;
  }

  if (BO->getOpcode() == Instruction::Or) {
    // Rebuild "or" as "add", because "or" may be invalid for the new
    // epxression.
    //
    // For instance, given
    //   a | (b + 5) where a and b + 5 have no common bits,
    // we can extract 5 as the constant offset.
    //
    // However, reusing the "or" in the new index would give us
    //   (a | b) + 5
    // which does not equal a | (b + 5).
    //
    // Replacing the "or" with "add" is fine, because
    //   a | (b + 5) = a + (b + 5) = (a + b) + 5
    if (OpNo == 0) {
      return BinaryOperator::CreateAdd(NextInChain, TheOther, BO->getName(),
                                       IP);
    } else {
      return BinaryOperator::CreateAdd(TheOther, NextInChain, BO->getName(),
                                       IP);
    }
  }

  // We can reuse BO in this case, because the new expression shares the same
  // instruction type and BO is used at most once.
  assert(BO->getNumUses() <= 1 &&
         "distributeExtsAndCloneChain clones each BinaryOperator in "
         "UserChain, so no one should be used more than "
         "once");
  BO->setOperand(OpNo, NextInChain);
  BO->setHasNoSignedWrap(false);
  BO->setHasNoUnsignedWrap(false);
  // Make sure it appears after all instructions we've inserted so far.
  BO->moveBefore(IP);
  return BO;
}

//.........这里部分代码省略.........
    // exit value and an equality or less than comparison.
    if (InitValue >= ExitValue ||
        NewPred == CmpInst::ICMP_SGT || NewPred == CmpInst::ICMP_SGE)
      return;
    
    uint32_t Range = uint32_t(ExitValue-InitValue);
    if (NewPred == CmpInst::ICMP_SLE) {
      // Normalize SLE -> SLT, check for infinite loop.
      if (++Range == 0) return;  // Range overflows.
    }
    
    unsigned Leftover = Range % uint32_t(IncValue);
    
    // If this is an equality comparison, we require that the strided value
    // exactly land on the exit value, otherwise the IV condition will wrap
    // around and do things the fp IV wouldn't.
    if ((NewPred == CmpInst::ICMP_EQ || NewPred == CmpInst::ICMP_NE) &&
        Leftover != 0)
      return;
    
    // If the stride would wrap around the i32 before exiting, we can't
    // transform the IV.
    if (Leftover != 0 && int32_t(ExitValue+IncValue) < ExitValue)
      return;
    
  } else {
    // If we have a negative stride, we require the init to be greater than the
    // exit value and an equality or greater than comparison.
    if (InitValue >= ExitValue ||
        NewPred == CmpInst::ICMP_SLT || NewPred == CmpInst::ICMP_SLE)
      return;
    
    uint32_t Range = uint32_t(InitValue-ExitValue);
    if (NewPred == CmpInst::ICMP_SGE) {
      // Normalize SGE -> SGT, check for infinite loop.
      if (++Range == 0) return;  // Range overflows.
    }
    
    unsigned Leftover = Range % uint32_t(-IncValue);
    
    // If this is an equality comparison, we require that the strided value
    // exactly land on the exit value, otherwise the IV condition will wrap
    // around and do things the fp IV wouldn't.
    if ((NewPred == CmpInst::ICMP_EQ || NewPred == CmpInst::ICMP_NE) &&
        Leftover != 0)
      return;
    
    // If the stride would wrap around the i32 before exiting, we can't
    // transform the IV.
    if (Leftover != 0 && int32_t(ExitValue+IncValue) > ExitValue)
      return;
  }
  
  const IntegerType *Int32Ty = Type::getInt32Ty(PN->getContext());

  // Insert new integer induction variable.
  PHINode *NewPHI = PHINode::Create(Int32Ty, PN->getName()+".int", PN);
  NewPHI->addIncoming(ConstantInt::get(Int32Ty, InitValue),
                      PN->getIncomingBlock(IncomingEdge));

  Value *NewAdd =
    BinaryOperator::CreateAdd(NewPHI, ConstantInt::get(Int32Ty, IncValue),
                              Incr->getName()+".int", Incr);
  NewPHI->addIncoming(NewAdd, PN->getIncomingBlock(BackEdge));

  ICmpInst *NewCompare = new ICmpInst(TheBr, NewPred, NewAdd,
                                      ConstantInt::get(Int32Ty, ExitValue),
                                      Compare->getName());

  // In the following deletions, PN may become dead and may be deleted.
  // Use a WeakVH to observe whether this happens.
  WeakVH WeakPH = PN;

  // Delete the old floating point exit comparison.  The branch starts using the
  // new comparison.
  NewCompare->takeName(Compare);
  Compare->replaceAllUsesWith(NewCompare);
  RecursivelyDeleteTriviallyDeadInstructions(Compare);

  // Delete the old floating point increment.
  Incr->replaceAllUsesWith(UndefValue::get(Incr->getType()));
  RecursivelyDeleteTriviallyDeadInstructions(Incr);

  // If the FP induction variable still has uses, this is because something else
  // in the loop uses its value.  In order to canonicalize the induction
  // variable, we chose to eliminate the IV and rewrite it in terms of an
  // int->fp cast.
  //
  // We give preference to sitofp over uitofp because it is faster on most
  // platforms.
  if (WeakPH) {
    Value *Conv = new SIToFPInst(NewPHI, PN->getType(), "indvar.conv",
                                 PN->getParent()->getFirstNonPHI());
    PN->replaceAllUsesWith(Conv);
    RecursivelyDeleteTriviallyDeadInstructions(PN);
  }

  // Add a new IVUsers entry for the newly-created integer PHI.
  IU->AddUsersIfInteresting(NewPHI);
}

// Peephole optimize the following instructions:
// %t1 = cast ? to x *
// %t2 = add x * %SP, %t1              ;; Constant must be 2nd operand
//
// Into: %t3 = getelementptr {<...>} * %SP, <element indices>
//       %t2 = cast <eltype> * %t3 to {<...>}*
//
static bool HandleCastToPointer(BasicBlock::iterator BI,
                                const PointerType *DestPTy,
                                const TargetData &TD) {
  CastInst &CI = cast<CastInst>(*BI);
  if (CI.use_empty()) return false;

  // Scan all of the uses, looking for any uses that are not add or sub
  // instructions.  If we have non-adds, do not make this transformation.
  //
  bool HasSubUse = false;  // Keep track of any subtracts...
  for (Value::use_iterator I = CI.use_begin(), E = CI.use_end();
       I != E; ++I)
    if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*I)) {
      if ((BO->getOpcode() != Instruction::Add &&
           BO->getOpcode() != Instruction::Sub) ||
          // Avoid add sbyte* %X, %X cases...
          BO->getOperand(0) == BO->getOperand(1))
        return false;
      else
        HasSubUse |= BO->getOpcode() == Instruction::Sub;
    } else {
      return false;
    }

  std::vector<Value*> Indices;
  Value *Src = CI.getOperand(0);
  const Type *Result = ConvertibleToGEP(DestPTy, Src, Indices, TD, &BI);
  if (Result == 0) return false;  // Not convertible...

  // Cannot handle subtracts if there is more than one index required...
  if (HasSubUse && Indices.size() != 1) return false;

  PRINT_PEEPHOLE2("cast-add-to-gep:in", *Src, CI);

  // If we have a getelementptr capability... transform all of the 
  // add instruction uses into getelementptr's.
  while (!CI.use_empty()) {
    BinaryOperator *I = cast<BinaryOperator>(*CI.use_begin());
    assert((I->getOpcode() == Instruction::Add ||
            I->getOpcode() == Instruction::Sub) && 
           "Use is not a valid add instruction!");
    
    // Get the value added to the cast result pointer...
    Value *OtherPtr = I->getOperand((I->getOperand(0) == &CI) ? 1 : 0);

    Instruction *GEP = new GetElementPtrInst(OtherPtr, Indices, I->getName());
    PRINT_PEEPHOLE1("cast-add-to-gep:i", *I);

    // If the instruction is actually a subtract, we are guaranteed to only have
    // one index (from code above), so we just need to negate the pointer index
    // long value.
    if (I->getOpcode() == Instruction::Sub) {
      Instruction *Neg = BinaryOperator::createNeg(GEP->getOperand(1), 
                                       GEP->getOperand(1)->getName()+".neg", I);
      GEP->setOperand(1, Neg);
    }

    if (GEP->getType() == I->getType()) {
      // Replace the old add instruction with the shiny new GEP inst
      ReplaceInstWithInst(I, GEP);
    } else {
      // If the type produced by the gep instruction differs from the original
      // add instruction type, insert a cast now.
      //

      // Insert the GEP instruction before the old add instruction...
      I->getParent()->getInstList().insert(I, GEP);

      PRINT_PEEPHOLE1("cast-add-to-gep:o", *GEP);
      GEP = new CastInst(GEP, I->getType());

      // Replace the old add instruction with the shiny new GEP inst
      ReplaceInstWithInst(I, GEP);
    }

    PRINT_PEEPHOLE1("cast-add-to-gep:o", *GEP);
  }
  return true;
}

//.........这里部分代码省略.........

  if (BranchInst *BI = dyn_cast<BranchInst>(EC->getParent()->getTerminator())) {
    if (!BI->isConditional()) return;
    if (BI->getCondition() != EC) return;
  }

  // Find exit value. If exit value can not be represented as an integer then
  // do not handle this floating point PH.
  ConstantFP *EV = NULL;
  unsigned EVIndex = 1;
  if (EC->getOperand(1) == Incr)
    EVIndex = 0;
  EV = dyn_cast<ConstantFP>(EC->getOperand(EVIndex));
  if (!EV) return;
  uint64_t intEV = Type::getInt32Ty(PH->getContext())->getPrimitiveSizeInBits();
  if (!convertToInt(EV->getValueAPF(), &intEV))
    return;

  // Find new predicate for integer comparison.
  CmpInst::Predicate NewPred = CmpInst::BAD_ICMP_PREDICATE;
  switch (EC->getPredicate()) {
  case CmpInst::FCMP_OEQ:
  case CmpInst::FCMP_UEQ:
    NewPred = CmpInst::ICMP_EQ;
    break;
  case CmpInst::FCMP_OGT:
  case CmpInst::FCMP_UGT:
    NewPred = CmpInst::ICMP_UGT;
    break;
  case CmpInst::FCMP_OGE:
  case CmpInst::FCMP_UGE:
    NewPred = CmpInst::ICMP_UGE;
    break;
  case CmpInst::FCMP_OLT:
  case CmpInst::FCMP_ULT:
    NewPred = CmpInst::ICMP_ULT;
    break;
  case CmpInst::FCMP_OLE:
  case CmpInst::FCMP_ULE:
    NewPred = CmpInst::ICMP_ULE;
    break;
  default:
    break;
  }
  if (NewPred == CmpInst::BAD_ICMP_PREDICATE) return;

  // Insert new integer induction variable.
  PHINode *NewPHI = PHINode::Create(Type::getInt32Ty(PH->getContext()),
                                    PH->getName()+".int", PH);
  NewPHI->addIncoming(ConstantInt::get(Type::getInt32Ty(PH->getContext()),
                                       newInitValue),
                      PH->getIncomingBlock(IncomingEdge));

  Value *NewAdd = BinaryOperator::CreateAdd(NewPHI,
                           ConstantInt::get(Type::getInt32Ty(PH->getContext()),
                                                             newIncrValue),
                                            Incr->getName()+".int", Incr);
  NewPHI->addIncoming(NewAdd, PH->getIncomingBlock(BackEdge));

  // The back edge is edge 1 of newPHI, whatever it may have been in the
  // original PHI.
  ConstantInt *NewEV = ConstantInt::get(Type::getInt32Ty(PH->getContext()),
                                        intEV);
  Value *LHS = (EVIndex == 1 ? NewPHI->getIncomingValue(1) : NewEV);
  Value *RHS = (EVIndex == 1 ? NewEV : NewPHI->getIncomingValue(1));
  ICmpInst *NewEC = new ICmpInst(EC->getParent()->getTerminator(),
                                 NewPred, LHS, RHS, EC->getName());

  // In the following deletions, PH may become dead and may be deleted.
  // Use a WeakVH to observe whether this happens.
  WeakVH WeakPH = PH;

  // Delete old, floating point, exit comparison instruction.
  NewEC->takeName(EC);
  EC->replaceAllUsesWith(NewEC);
  RecursivelyDeleteTriviallyDeadInstructions(EC);

  // Delete old, floating point, increment instruction.
  Incr->replaceAllUsesWith(UndefValue::get(Incr->getType()));
  RecursivelyDeleteTriviallyDeadInstructions(Incr);

  // Replace floating induction variable, if it isn't already deleted.
  // Give SIToFPInst preference over UIToFPInst because it is faster on
  // platforms that are widely used.
  if (WeakPH && !PH->use_empty()) {
    if (useSIToFPInst(*InitValue, *EV, newInitValue, intEV)) {
      SIToFPInst *Conv = new SIToFPInst(NewPHI, PH->getType(), "indvar.conv",
                                        PH->getParent()->getFirstNonPHI());
      PH->replaceAllUsesWith(Conv);
    } else {
      UIToFPInst *Conv = new UIToFPInst(NewPHI, PH->getType(), "indvar.conv",
                                        PH->getParent()->getFirstNonPHI());
      PH->replaceAllUsesWith(Conv);
    }
    RecursivelyDeleteTriviallyDeadInstructions(PH);
  }

  // Add a new IVUsers entry for the newly-created integer PHI.
  IU->AddUsersIfInteresting(NewPHI);
}