C++ LoadInst::isSimple方法代码示例

bool AMDGPUCodeGenPrepare::canWidenScalarExtLoad(LoadInst &I) const {
  Type *Ty = I.getType();
  const DataLayout &DL = Mod->getDataLayout();
  int TySize = DL.getTypeSizeInBits(Ty);
  unsigned Align = I.getAlignment() ?
                   I.getAlignment() : DL.getABITypeAlignment(Ty);

  return I.isSimple() && TySize < 32 && Align >= 4 && DA->isUniform(&I);
}

///   %res = load {atomic|volatile} T* %ptr memory_order, align sizeof(T)
/// becomes:
///   %res = call T @llvm.nacl.atomic.load.i<size>(%ptr, memory_order)
void AtomicVisitor::visitLoadInst(LoadInst &I) {
  return; // XXX EMSCRIPTEN
  if (I.isSimple())
    return;
  PointerHelper<LoadInst> PH(*this, I);
  const NaCl::AtomicIntrinsics::AtomicIntrinsic *Intrinsic =
      findAtomicIntrinsic(I, Intrinsic::nacl_atomic_load, PH.PET);
  checkAlignment(I, I.getAlignment(), PH.BitSize / CHAR_BIT);
  Value *Args[] = {PH.P, freezeMemoryOrder(I, I.getOrdering())};
  replaceInstructionWithIntrinsicCall(I, Intrinsic, PH.OriginalPET, PH.PET,
                                      Args);
}

bool CallAnalyzer::visitLoad(LoadInst &I) {
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
    if (I.isSimple()) {
      accumulateSROACost(CostIt, InlineConstants::InstrCost);
      return true;
    }

    disableSROA(CostIt);
  }

  return false;
}

bool IRTranslator::translateLoad(const LoadInst &LI) {
  assert(LI.isSimple() && "only simple loads are supported at the moment");

  MachineFunction &MF = MIRBuilder.getMF();
  unsigned Res = getOrCreateVReg(LI);
  unsigned Addr = getOrCreateVReg(*LI.getPointerOperand());
  LLT VTy{*LI.getType()}, PTy{*LI.getPointerOperand()->getType()};

  MIRBuilder.buildLoad(
      VTy, PTy, Res, Addr,
      *MF.getMachineMemOperand(MachinePointerInfo(LI.getPointerOperand()),
                               MachineMemOperand::MOLoad,
                               VTy.getSizeInBits() / 8, getMemOpAlignment(LI)));
  return true;
}

/// \brief Check loop instructions safe for Loop versioning.
/// It returns true if it's safe else returns false.
/// Consider following:
/// 1) Check all load store in loop body are non atomic & non volatile.
/// 2) Check function call safety, by ensuring its not accessing memory.
/// 3) Loop body shouldn't have any may throw instruction.
bool LoopVersioningLICM::instructionSafeForVersioning(Instruction *I) {
  assert(I != nullptr && "Null instruction found!");
  // Check function call safety
  if (isa<CallInst>(I) && !AA->doesNotAccessMemory(CallSite(I))) {
    DEBUG(dbgs() << "    Unsafe call site found.\n");
    return false;
  }
  // Avoid loops with possiblity of throw
  if (I->mayThrow()) {
    DEBUG(dbgs() << "    May throw instruction found in loop body\n");
    return false;
  }
  // If current instruction is load instructions
  // make sure it's a simple load (non atomic & non volatile)
  if (I->mayReadFromMemory()) {
    LoadInst *Ld = dyn_cast<LoadInst>(I);
    if (!Ld || !Ld->isSimple()) {
      DEBUG(dbgs() << "    Found a non-simple load.\n");
      return false;
    }
    LoadAndStoreCounter++;
    collectStridedAccess(Ld);
    Value *Ptr = Ld->getPointerOperand();
    // Check loop invariant.
    if (SE->isLoopInvariant(SE->getSCEV(Ptr), CurLoop))
      InvariantCounter++;
  }
  // If current instruction is store instruction
  // make sure it's a simple store (non atomic & non volatile)
  else if (I->mayWriteToMemory()) {
    StoreInst *St = dyn_cast<StoreInst>(I);
    if (!St || !St->isSimple()) {
      DEBUG(dbgs() << "    Found a non-simple store.\n");
      return false;
    }
    LoadAndStoreCounter++;
    collectStridedAccess(St);
    Value *Ptr = St->getPointerOperand();
    // Check loop invariant.
    if (SE->isLoopInvariant(SE->getSCEV(Ptr), CurLoop))
      InvariantCounter++;

    IsReadOnlyLoop = false;
  }
  return true;
}

bool Scalarizer::visitLoadInst(LoadInst &LI) {
  if (!ScalarizeLoadStore)
    return false;
  if (!LI.isSimple())
    return false;

  VectorLayout Layout;
  if (!getVectorLayout(LI.getType(), LI.getAlignment(), Layout))
    return false;

  unsigned NumElems = Layout.VecTy->getNumElements();
  IRBuilder<> Builder(LI.getParent(), &LI);
  Scatterer Ptr = scatter(&LI, LI.getPointerOperand());
  ValueVector Res;
  Res.resize(NumElems);

  for (unsigned I = 0; I < NumElems; ++I)
    Res[I] = Builder.CreateAlignedLoad(Ptr[I], Layout.getElemAlign(I),
                                       LI.getName() + ".i" + Twine(I));
  gather(&LI, Res);
  return true;
}

/// tryAggregating - When scanning forward over instructions, we look for
/// other loads or stores that could be aggregated with this one.
/// Returns the last instruction added (if one was added) since we might have
/// removed some loads or stores and that might invalidate an iterator.
Instruction *AggregateGlobalOpsOpt::tryAggregating(Instruction *StartInst, Value *StartPtr,
    bool DebugThis) {
  if (TD == 0) return 0;

  Module* M = StartInst->getParent()->getParent()->getParent();
  LLVMContext& Context = StartInst->getContext();

  Type* int8Ty = Type::getInt8Ty(Context);
  Type* sizeTy = Type::getInt64Ty(Context);
  Type* globalInt8PtrTy = int8Ty->getPointerTo(globalSpace);
  bool isLoad = isa<LoadInst>(StartInst);
  bool isStore = isa<StoreInst>(StartInst);
  Instruction *lastAddedInsn = NULL;
  Instruction *LastLoadOrStore = NULL;
 
  SmallVector<Instruction*, 8> toRemove;

  // Okay, so we now have a single global load/store. Scan to find
  // all subsequent stores of the same value to offset from the same pointer.
  // Join these together into ranges, so we can decide whether contiguous blocks
  // are stored.
  MemOpRanges Ranges(*TD);
 
  // Put the first store in since we want to preserve the order.
  Ranges.addInst(0, StartInst);

  BasicBlock::iterator BI = StartInst;
  for (++BI; !isa<TerminatorInst>(BI); ++BI) {

    if( isGlobalLoadOrStore(BI, globalSpace, isLoad, isStore) ) {
      // OK!
    } else {
      // If the instruction is readnone, ignore it, otherwise bail out.  We
      // don't even allow readonly here because we don't want something like:
      // A[1] = 2; strlen(A); A[2] = 2; -> memcpy(A, ...); strlen(A).
      if (BI->mayWriteToMemory())
        break;
      if (isStore && BI->mayReadFromMemory())
        break;
      continue;
    }

    if ( isStore && isa<StoreInst>(BI) ) {
      StoreInst *NextStore = cast<StoreInst>(BI);
      // If this is a store, see if we can merge it in.
      if (!NextStore->isSimple()) break;

      // Check to see if this store is to a constant offset from the start ptr.
      int64_t Offset;
      if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset, *TD))
        break;

      Ranges.addStore(Offset, NextStore);
      LastLoadOrStore = NextStore;
    } else {
      LoadInst *NextLoad = cast<LoadInst>(BI);
      if (!NextLoad->isSimple()) break;

      // Check to see if this load is to a constant offset from the start ptr.
      int64_t Offset;
      if (!IsPointerOffset(StartPtr, NextLoad->getPointerOperand(), Offset, *TD))
        break;

      Ranges.addLoad(Offset, NextLoad);
      LastLoadOrStore = NextLoad;
    }
  }

  // If we have no ranges, then we just had a single store with nothing that
  // could be merged in.  This is a very common case of course.
  if (!Ranges.moreThanOneOp())
    return 0;

  // Divide the instructions between StartInst and LastLoadOrStore into
  // addressing, memops, and uses of memops (uses of loads)
  reorderAddressingMemopsUses(StartInst, LastLoadOrStore, DebugThis);

  Instruction* insertBefore = StartInst;
  IRBuilder<> builder(insertBefore);

  // Now that we have full information about ranges, loop over the ranges and
  // emit memcpy's for anything big enough to be worthwhile.
  for (MemOpRanges::const_iterator I = Ranges.begin(), E = Ranges.end();
       I != E; ++I) {
    const MemOpRange &Range = *I;
    Value* oldBaseI = NULL;
    Value* newBaseI = NULL;

    if (Range.TheStores.size() == 1) continue; // Don't bother if there's only one thing...

    builder.SetInsertPoint(insertBefore);

    // Otherwise, we do want to transform this!  Create a new memcpy.
    // Get the starting pointer of the block.
    StartPtr = Range.StartPtr;

//.........这里部分代码省略.........

/// \brief Compute the reduction possible for a given instruction if we are able
/// to SROA an alloca.
///
/// The reduction for this instruction is added to the SROAReduction output
/// parameter. Returns false if this instruction is expected to defeat SROA in
/// general.
static bool countCodeReductionForSROAInst(Instruction *I,
                                          SmallVectorImpl<Value *> &Worklist,
                                          unsigned &SROAReduction) {
  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
    if (!LI->isSimple())
      return false;
    SROAReduction += InlineConstants::InstrCost;
    return true;
  }

  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
    if (!SI->isSimple())
      return false;
    SROAReduction += InlineConstants::InstrCost;
    return true;
  }

  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
    // If the GEP has variable indices, we won't be able to do much with it.
    if (!GEP->hasAllConstantIndices())
      return false;
    // A non-zero GEP will likely become a mask operation after SROA.
    if (GEP->hasAllZeroIndices())
      SROAReduction += InlineConstants::InstrCost;
    Worklist.push_back(GEP);
    return true;
  }

  if (BitCastInst *BCI = dyn_cast<BitCastInst>(I)) {
    // Track pointer through bitcasts.
    Worklist.push_back(BCI);
    SROAReduction += InlineConstants::InstrCost;
    return true;
  }

  // We just look for non-constant operands to ICmp instructions as those will
  // defeat SROA. The actual reduction for these happens even without SROA.
  if (ICmpInst *ICI = dyn_cast<ICmpInst>(I))
    return isa<Constant>(ICI->getOperand(1));

  if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
    // SROA can handle a select of alloca iff all uses of the alloca are
    // loads, and dereferenceable. We assume it's dereferenceable since
    // we're told the input is an alloca.
    for (Value::use_iterator UI = SI->use_begin(), UE = SI->use_end();
         UI != UE; ++UI) {
      LoadInst *LI = dyn_cast<LoadInst>(*UI);
      if (LI == 0 || !LI->isSimple())
        return false;
    }
    // We don't know whether we'll be deleting the rest of the chain of
    // instructions from the SelectInst on, because we don't know whether
    // the other side of the select is also an alloca or not.
    return true;
  }

  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
    switch (II->getIntrinsicID()) {
    default:
      return false;
    case Intrinsic::memset:
    case Intrinsic::memcpy:
    case Intrinsic::memmove:
    case Intrinsic::lifetime_start:
    case Intrinsic::lifetime_end:
      // SROA can usually chew through these intrinsics.
      SROAReduction += InlineConstants::InstrCost;
      return true;
    }
  }

  // If there is some other strange instruction, we're not going to be
  // able to do much if we inline this.
  return false;
}

    bool runOnFunction(Function &F) override {
    	AliasAnalysis AA = getAnalysis<AliasAnalysis>();
        DependenceAnalysis *DA = &(getAnalysis<DependenceAnalysis>());
        // iterate over basic blocks
        Function *func = &F;
        unsigned bb_num = 0;
        for (Function::iterator BB = func->begin(), BE = func->end();
       BB != BE; ++BB) {
        	errs() << "BB-" << bb_num << "\n";
            bb_num++;
            // iterator over instructions
            unsigned inst_num = 0;
            for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;++I) {
                Instruction *Ins = dyn_cast<Instruction>(I);
                if (!Ins)
                    return false;
                LoadInst *Ld = dyn_cast<LoadInst>(I);
                StoreInst *St = dyn_cast<StoreInst>(I);
                if (!St && !Ld)
                    continue;
                if (Ld && !Ld->isSimple())
                    return false;
                if (St && !St->isSimple())
                    return false;
                inst_num++;
                MemInstr.push_back(&*I);
                errs() << "MemInst-" << inst_num << ":" << *I << "\n";
            }

        	ValueVector::iterator I, IE, J, JE;
            for (I = MemInstr.begin(), IE = MemInstr.end(); I != IE; ++I) {
            for (J = I, JE = MemInstr.end(); J != JE; ++J) {
                std::vector<char> Dep;
                Instruction *Src = dyn_cast<Instruction>(*I);
                Instruction *Des = dyn_cast<Instruction>(*J);
                if (Src == Des)
                    continue;
                if (isa<LoadInst>(Src) && isa<LoadInst>(Des))
                    continue;
                if (auto D = DA->depends(Src, Des, true)) {
                    errs() << "Found Dependency between:\nSrc:" << *Src << "\nDes:" << *Des
                     << "\n";
                	if (D->isFlow()) {
                    	errs () << "Flow dependence not handled";
                    	return false;
                	}
                
                	if (D->isAnti()) {
                    	errs() << "Found Anti dependence \n";

						AliasAnalysis::AliasResult AA_dep = AA.alias(Src, Des);
                        AliasAnalysis::AliasResult AA_dep_1 = AA.alias(Des, Src);
                    	errs() << "The Ld->St alias result is " << AA_dep << "\n";
                    	errs() << "The St->Ld alias result is " << AA_dep_1 << "\n";
                    	
                        unsigned Levels = D->getLevels();
                    	errs() << "levels = " << Levels << "\n";
                    	char Direction;
                    	for (unsigned II = 1; II <= Levels; ++II) {
                        	const SCEV *Distance = D->getDistance(II);
                        	const SCEVConstant *SCEVConst = dyn_cast_or_null<SCEVConstant>(Distance);
                        	if (SCEVConst) {
                            	const ConstantInt *CI = SCEVConst->getValue();
                                //int64_t it_dist = CI->getUniqueInteger().getSExtValue();
                                //int it_dist = CI->getUniqueInteger().getSExtValue();
                               	unsigned it_dist = abs(CI->getUniqueInteger().getSExtValue());
                            	errs() << "distance is not null\n";
                            	//errs() << "distance = "<< *CI << "\n";
                            	errs() << "distance = "<< it_dist << "\n";
                       			if (CI->isNegative())
                            		Direction = '<';
                        		else if (CI->isZero())
                            		Direction = '=';
                        		else
                            		Direction = '>';
                        		Dep.push_back(Direction);
                        	} 
                        	else if (D->isScalar(II)) {
                        		Direction = 'S';
                        		Dep.push_back(Direction);
                        	} 
                        	else {
                            	unsigned Dir = D->getDirection(II);
                            	if (Dir == Dependence::DVEntry::LT || Dir == Dependence::DVEntry::LE)
                                	Direction = '<';
                            	else if (Dir == Dependence::DVEntry::GT || Dir == Dependence::DVEntry::GE)
                                	Direction = '>';
                            	else if (Dir == Dependence::DVEntry::EQ)
                                	Direction = '=';
                            	else
                                	Direction = '*';
                            	Dep.push_back(Direction);
                        	}
                    	}
                	}
              	}
            }
        	}
        }
        errs() << "------Hello World!--------\n";
//.........这里部分代码省略.........