C++ StoreInst::getParent方法代码示例

/// RewriteSingleStoreAlloca - If there is only a single store to this value,
/// replace any loads of it that are directly dominated by the definition with
/// the value stored.
void PromoteMem2Reg::RewriteSingleStoreAlloca(AllocaInst *AI,
                                              AllocaInfo &Info,
                                              LargeBlockInfo &LBI) {
  StoreInst *OnlyStore = Info.OnlyStore;
  bool StoringGlobalVal = !isa<Instruction>(OnlyStore->getOperand(0));
  BasicBlock *StoreBB = OnlyStore->getParent();
  int StoreIndex = -1;

  // Clear out UsingBlocks.  We will reconstruct it here if needed.
  Info.UsingBlocks.clear();
  
  for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E; ) {
    Instruction *UserInst = cast<Instruction>(*UI++);
    if (!isa<LoadInst>(UserInst)) {
      assert(UserInst == OnlyStore && "Should only have load/stores");
      continue;
    }
    LoadInst *LI = cast<LoadInst>(UserInst);
    
    // Okay, if we have a load from the alloca, we want to replace it with the
    // only value stored to the alloca.  We can do this if the value is
    // dominated by the store.  If not, we use the rest of the mem2reg machinery
    // to insert the phi nodes as needed.
    if (!StoringGlobalVal) {  // Non-instructions are always dominated.
      if (LI->getParent() == StoreBB) {
        // If we have a use that is in the same block as the store, compare the
        // indices of the two instructions to see which one came first.  If the
        // load came before the store, we can't handle it.
        if (StoreIndex == -1)
          StoreIndex = LBI.getInstructionIndex(OnlyStore);

        if (unsigned(StoreIndex) > LBI.getInstructionIndex(LI)) {
          // Can't handle this load, bail out.
          Info.UsingBlocks.push_back(StoreBB);
          continue;
        }
        
      } else if (LI->getParent() != StoreBB &&
                 !dominates(StoreBB, LI->getParent())) {
        // If the load and store are in different blocks, use BB dominance to
        // check their relationships.  If the store doesn't dom the use, bail
        // out.
        Info.UsingBlocks.push_back(LI->getParent());
        continue;
      }
    }
    
    // Otherwise, we *can* safely rewrite this load.
    Value *ReplVal = OnlyStore->getOperand(0);
    // If the replacement value is the load, this must occur in unreachable
    // code.
    if (ReplVal == LI)
      ReplVal = UndefValue::get(LI->getType());
    LI->replaceAllUsesWith(ReplVal);
    if (AST && LI->getType()->isPointerTy())
      AST->deleteValue(LI);
    LI->eraseFromParent();
    LBI.deleteValue(LI);
  }
}

bool Scalarizer::visitStoreInst(StoreInst &SI) {
  if (!ScalarizeLoadStore)
    return false;
  if (!SI.isSimple())
    return false;

  VectorLayout Layout;
  Value *FullValue = SI.getValueOperand();
  if (!getVectorLayout(FullValue->getType(), SI.getAlignment(), Layout))
    return false;

  unsigned NumElems = Layout.VecTy->getNumElements();
  IRBuilder<> Builder(SI.getParent(), &SI);
  Scatterer Ptr = scatter(&SI, SI.getPointerOperand());
  Scatterer Val = scatter(&SI, FullValue);

  ValueVector Stores;
  Stores.resize(NumElems);
  for (unsigned I = 0; I < NumElems; ++I) {
    unsigned Align = Layout.getElemAlign(I);
    Stores[I] = Builder.CreateAlignedStore(Val[I], Ptr[I], Align);
  }
  transferMetadata(&SI, Stores);
  return true;
}

void DSGraphStats::visitStore(StoreInst &SI) {
  if (isNodeForValueUntyped(SI.getOperand(1), 0,SI.getParent()->getParent())) {
    NumUntypedMemAccesses++;
  } else {
    NumTypedMemAccesses++;
  }
}

/// SimplifyStoreAtEndOfBlock - Turn things like:
///   if () { *P = v1; } else { *P = v2 }
/// into a phi node with a store in the successor.
///
/// Simplify things like:
///   *P = v1; if () { *P = v2; }
/// into a phi node with a store in the successor.
///
bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
  BasicBlock *StoreBB = SI.getParent();

  // Check to see if the successor block has exactly two incoming edges.  If
  // so, see if the other predecessor contains a store to the same location.
  // if so, insert a PHI node (if needed) and move the stores down.
  BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);

  // Determine whether Dest has exactly two predecessors and, if so, compute
  // the other predecessor.
  pred_iterator PI = pred_begin(DestBB);
  BasicBlock *P = *PI;
  BasicBlock *OtherBB = nullptr;

  if (P != StoreBB)
    OtherBB = P;

  if (++PI == pred_end(DestBB))
    return false;

  P = *PI;
  if (P != StoreBB) {
    if (OtherBB)
      return false;
    OtherBB = P;
  }
  if (++PI != pred_end(DestBB))
    return false;

  // Bail out if all the relevant blocks aren't distinct (this can happen,
  // for example, if SI is in an infinite loop)
  if (StoreBB == DestBB || OtherBB == DestBB)
    return false;

  // Verify that the other block ends in a branch and is not otherwise empty.
  BasicBlock::iterator BBI(OtherBB->getTerminator());
  BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
  if (!OtherBr || BBI == OtherBB->begin())
    return false;

  // If the other block ends in an unconditional branch, check for the 'if then
  // else' case.  there is an instruction before the branch.
  StoreInst *OtherStore = nullptr;
  if (OtherBr->isUnconditional()) {
    --BBI;
    // Skip over debugging info.
    while (isa<DbgInfoIntrinsic>(BBI) ||
           (isa<BitCastInst>(BBI) && BBI->getType()->isPointerTy())) {
      if (BBI==OtherBB->begin())
        return false;
      --BBI;
    }
    // If this isn't a store, isn't a store to the same location, or is not the
    // right kind of store, bail out.
    OtherStore = dyn_cast<StoreInst>(BBI);
    if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1) ||
        !SI.isSameOperationAs(OtherStore))
      return false;
  } else {
    // Otherwise, the other block ended with a conditional branch. If one of the
    // destinations is StoreBB, then we have the if/then case.
    if (OtherBr->getSuccessor(0) != StoreBB &&
        OtherBr->getSuccessor(1) != StoreBB)
      return false;

    // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
    // if/then triangle.  See if there is a store to the same ptr as SI that
    // lives in OtherBB.
    for (;; --BBI) {
      // Check to see if we find the matching store.
      if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
        if (OtherStore->getOperand(1) != SI.getOperand(1) ||
            !SI.isSameOperationAs(OtherStore))
          return false;
        break;
      }
      // If we find something that may be using or overwriting the stored
      // value, or if we run out of instructions, we can't do the xform.
      if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() ||
          BBI == OtherBB->begin())
        return false;
    }

    // In order to eliminate the store in OtherBr, we have to
    // make sure nothing reads or overwrites the stored value in
    // StoreBB.
    for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
      // FIXME: This should really be AA driven.
      if (I->mayReadFromMemory() || I->mayWriteToMemory())
        return false;
    }
  }
//.........这里部分代码省略.........

/// \brief Rewrite as many loads as possible given a single store.
///
/// When there is only a single store, we can use the domtree to trivially
/// replace all of the dominated loads with the stored value. Do so, and return
/// true if this has successfully promoted the alloca entirely. If this returns
/// false there were some loads which were not dominated by the single store
/// and thus must be phi-ed with undef. We fall back to the standard alloca
/// promotion algorithm in that case.
static bool rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info,
                                     LargeBlockInfo &LBI,
                                     DominatorTree &DT,
                                     AliasSetTracker *AST) {
  StoreInst *OnlyStore = Info.OnlyStore;
  bool StoringGlobalVal = !isa<Instruction>(OnlyStore->getOperand(0));
  BasicBlock *StoreBB = OnlyStore->getParent();
  int StoreIndex = -1;

  // Clear out UsingBlocks.  We will reconstruct it here if needed.
  Info.UsingBlocks.clear();

  for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E;) {
    Instruction *UserInst = cast<Instruction>(*UI++);
    if (!isa<LoadInst>(UserInst)) {
      assert(UserInst == OnlyStore && "Should only have load/stores");
      continue;
    }
    LoadInst *LI = cast<LoadInst>(UserInst);

    // Okay, if we have a load from the alloca, we want to replace it with the
    // only value stored to the alloca.  We can do this if the value is
    // dominated by the store.  If not, we use the rest of the mem2reg machinery
    // to insert the phi nodes as needed.
    if (!StoringGlobalVal) { // Non-instructions are always dominated.
      if (LI->getParent() == StoreBB) {
        // If we have a use that is in the same block as the store, compare the
        // indices of the two instructions to see which one came first.  If the
        // load came before the store, we can't handle it.
        if (StoreIndex == -1)
          StoreIndex = LBI.getInstructionIndex(OnlyStore);

        if (unsigned(StoreIndex) > LBI.getInstructionIndex(LI)) {
          // Can't handle this load, bail out.
          Info.UsingBlocks.push_back(StoreBB);
          continue;
        }

      } else if (LI->getParent() != StoreBB &&
                 !DT.dominates(StoreBB, LI->getParent())) {
        // If the load and store are in different blocks, use BB dominance to
        // check their relationships.  If the store doesn't dom the use, bail
        // out.
        Info.UsingBlocks.push_back(LI->getParent());
        continue;
      }
    }

    // Otherwise, we *can* safely rewrite this load.
    Value *ReplVal = OnlyStore->getOperand(0);
    // If the replacement value is the load, this must occur in unreachable
    // code.
    if (ReplVal == LI)
      ReplVal = UndefValue::get(LI->getType());
    LI->replaceAllUsesWith(ReplVal);
    if (AST && LI->getType()->isPointerTy())
      AST->deleteValue(LI);
    LI->eraseFromParent();
    LBI.deleteValue(LI);
  }

  // Finally, after the scan, check to see if the store is all that is left.
  if (!Info.UsingBlocks.empty())
    return false; // If not, we'll have to fall back for the remainder.

  // Record debuginfo for the store and remove the declaration's
  // debuginfo.
  if (DbgDeclareInst *DDI = Info.DbgDeclare) {
    DIBuilder DIB(*AI->getParent()->getParent()->getParent());
    ConvertDebugDeclareToDebugValue(DDI, Info.OnlyStore, DIB);
    DDI->eraseFromParent();
  }
  // Remove the (now dead) store and alloca.
  Info.OnlyStore->eraseFromParent();
  LBI.deleteValue(Info.OnlyStore);

  if (AST)
    AST->deleteValue(AI);
  AI->eraseFromParent();
  LBI.deleteValue(AI);
  return true;
}

Value* LoopTripCount::insertTripCount(Loop* L, Instruction* InsertPos)
{
	// inspired from Loop::getCanonicalInductionVariable
	BasicBlock *H = L->getHeader();
	BasicBlock* LoopPred = L->getLoopPredecessor();
	BasicBlock* startBB = NULL;//which basicblock stores start value
	int OneStep = 0;// the extra add or plus step for calc

   Assert(LoopPred, "Require Loop has a Pred");
	DEBUG(errs()<<"loop  depth:"<<L->getLoopDepth()<<"\n");
	/** whats difference on use of predecessor and preheader??*/
	//RET_ON_FAIL(self->getLoopLatch()&&self->getLoopPreheader());
	//assert(self->getLoopLatch() && self->getLoopPreheader() && "need loop simplify form" );
	ret_null_fail(L->getLoopLatch(), "need loop simplify form");

	BasicBlock* TE = NULL;//True Exit
	SmallVector<BasicBlock*,4> Exits;
	L->getExitingBlocks(Exits);

	if(Exits.size()==1) TE = Exits.front();
	else{
		if(std::find(Exits.begin(),Exits.end(),L->getLoopLatch())!=Exits.end()) TE = L->getLoopLatch();
		else{
			SmallVector<llvm::Loop::Edge,4> ExitEdges;
			L->getExitEdges(ExitEdges);
			//stl 用法,先把所有满足条件的元素(出口的结束符是不可到达)移动到数组的末尾,再统一删除
			ExitEdges.erase(std::remove_if(ExitEdges.begin(), ExitEdges.end(), 
						[](llvm::Loop::Edge& I){
						return isa<UnreachableInst>(I.second->getTerminator());
						}), ExitEdges.end());
			if(ExitEdges.size()==1) TE = const_cast<BasicBlock*>(ExitEdges.front().first);
		}
	}

	//process true exit
	ret_null_fail(TE, "need have a true exit");

	Instruction* IndOrNext = NULL;
	Value* END = NULL;
   //终止块的终止指令：分情况讨论branchinst,switchinst;
   //跳转指令br bool a1,a2;condition<-->bool
	if(isa<BranchInst>(TE->getTerminator())){
		const BranchInst* EBR = cast<BranchInst>(TE->getTerminator());
		Assert(EBR->isConditional(), "end branch is not conditional");
		ICmpInst* EC = dyn_cast<ICmpInst>(EBR->getCondition());
		if(EC->getPredicate() == EC->ICMP_SGT){
         Assert(!L->contains(EBR->getSuccessor(0)), *EBR<<":abnormal exit with great than");//终止块的终止指令---->跳出执行循环外的指令
         OneStep += 1;
      } else if(EC->getPredicate() == EC->ICMP_EQ)
         Assert(!L->contains(EBR->getSuccessor(0)), *EBR<<":abnormal exit with great than");
      else if(EC->getPredicate() == EC->ICMP_SLT) {
         ret_null_fail(!L->contains(EBR->getSuccessor(1)), *EBR<<":abnormal exit with less than");
      } else {
         ret_null_fail(0, *EC<<" unknow combination of end condition");
      }
		IndOrNext = dyn_cast<Instruction>(castoff(EC->getOperand(0)));//去掉类型转化
		END = EC->getOperand(1);
		DEBUG(errs()<<"end   value:"<<*EC<<"\n");
	}else if(isa<SwitchInst>(TE->getTerminator())){
		SwitchInst* ESW = const_cast<SwitchInst*>(cast<SwitchInst>(TE->getTerminator()));
		IndOrNext = dyn_cast<Instruction>(castoff(ESW->getCondition()));
		for(auto I = ESW->case_begin(),E = ESW->case_end();I!=E;++I){
			if(!L->contains(I.getCaseSuccessor())){
				ret_null_fail(!END,"");
				assert(!END && "shouldn't have two ends");
				END = I.getCaseValue();
			}
		}
		DEBUG(errs()<<"end   value:"<<*ESW<<"\n");
	}else{
		assert(0 && "unknow terminator type");
	}

	ret_null_fail(L->isLoopInvariant(END), "end value should be loop invariant");//至此得END值

	Value* start = NULL;
	Value* ind = NULL;
	Instruction* next = NULL;
	bool addfirst = false;//add before icmp ed

	DISABLE(errs()<<*IndOrNext<<"\n");
	if(isa<LoadInst>(IndOrNext)){
		//memory depend analysis
		Value* PSi = IndOrNext->getOperand(0);//point type Step.i

		int SICount[2] = {0};//store in predecessor count,store in loop body count
		for( auto I = PSi->use_begin(),E = PSi->use_end();I!=E;++I){
			DISABLE(errs()<<**I<<"\n");
			StoreInst* SI = dyn_cast<StoreInst>(*I);
			if(!SI || SI->getOperand(1) != PSi) continue;
			if(!start&&L->isLoopInvariant(SI->getOperand(0))) {
				if(SI->getParent() != LoopPred)
					if(std::find(pred_begin(LoopPred),pred_end(LoopPred),SI->getParent()) == pred_end(LoopPred)) continue;
				start = SI->getOperand(0);
				startBB = SI->getParent();
				++SICount[0];
			}
			Instruction* SI0 = dyn_cast<Instruction>(SI->getOperand(0));
			if(L->contains(SI) && SI0 && SI0->getOpcode() == Instruction::Add){
				next = SI0;
//.........这里部分代码省略.........

void PromoteMem2Reg::run() {
  Function &F = *DT.getRoot()->getParent();

  if (AST) PointerAllocaValues.resize(Allocas.size());
  AllocaDbgDeclares.resize(Allocas.size());

  AllocaInfo Info;
  LargeBlockInfo LBI;

  for (unsigned AllocaNum = 0; AllocaNum != Allocas.size(); ++AllocaNum) {
    AllocaInst *AI = Allocas[AllocaNum];

    assert(isAllocaPromotable(AI) &&
           "Cannot promote non-promotable alloca!");
    assert(AI->getParent()->getParent() == &F &&
           "All allocas should be in the same function, which is same as DF!");

    removeLifetimeIntrinsicUsers(AI);

    if (AI->use_empty()) {
      // If there are no uses of the alloca, just delete it now.
      if (AST) AST->deleteValue(AI);
      AI->eraseFromParent();

      // Remove the alloca from the Allocas list, since it has been processed
      RemoveFromAllocasList(AllocaNum);
      ++NumDeadAlloca;
      continue;
    }
    
    // Calculate the set of read and write-locations for each alloca.  This is
    // analogous to finding the 'uses' and 'definitions' of each variable.
    Info.AnalyzeAlloca(AI);

    // If there is only a single store to this value, replace any loads of
    // it that are directly dominated by the definition with the value stored.
    if (Info.DefiningBlocks.size() == 1) {
      RewriteSingleStoreAlloca(AI, Info, LBI);

      // Finally, after the scan, check to see if the store is all that is left.
      if (Info.UsingBlocks.empty()) {
        // Record debuginfo for the store and remove the declaration's debuginfo.
        if (DbgDeclareInst *DDI = Info.DbgDeclare) {
          if (!DIB)
            DIB = new DIBuilder(*DDI->getParent()->getParent()->getParent());
          ConvertDebugDeclareToDebugValue(DDI, Info.OnlyStore, *DIB);
          DDI->eraseFromParent();
        }
        // Remove the (now dead) store and alloca.
        Info.OnlyStore->eraseFromParent();
        LBI.deleteValue(Info.OnlyStore);

        if (AST) AST->deleteValue(AI);
        AI->eraseFromParent();
        LBI.deleteValue(AI);
        
        // The alloca has been processed, move on.
        RemoveFromAllocasList(AllocaNum);
        
        ++NumSingleStore;
        continue;
      }
    }
    
    // If the alloca is only read and written in one basic block, just perform a
    // linear sweep over the block to eliminate it.
    if (Info.OnlyUsedInOneBlock) {
      PromoteSingleBlockAlloca(AI, Info, LBI);
      
      // Finally, after the scan, check to see if the stores are all that is
      // left.
      if (Info.UsingBlocks.empty()) {
        
        // Remove the (now dead) stores and alloca.
        while (!AI->use_empty()) {
          StoreInst *SI = cast<StoreInst>(AI->use_back());
          // Record debuginfo for the store before removing it.
          if (DbgDeclareInst *DDI = Info.DbgDeclare) {
            if (!DIB)
              DIB = new DIBuilder(*SI->getParent()->getParent()->getParent());
            ConvertDebugDeclareToDebugValue(DDI, SI, *DIB);
          }
          SI->eraseFromParent();
          LBI.deleteValue(SI);
        }
        
        if (AST) AST->deleteValue(AI);
        AI->eraseFromParent();
        LBI.deleteValue(AI);
        
        // The alloca has been processed, move on.
        RemoveFromAllocasList(AllocaNum);
        
        // The alloca's debuginfo can be removed as well.
        if (DbgDeclareInst *DDI = Info.DbgDeclare)
          DDI->eraseFromParent();

        ++NumLocalPromoted;
        continue;
      }
//.........这里部分代码省略.........

/// Rewrite as many loads as possible given a single store.
///
/// When there is only a single store, we can use the domtree to trivially
/// replace all of the dominated loads with the stored value. Do so, and return
/// true if this has successfully promoted the alloca entirely. If this returns
/// false there were some loads which were not dominated by the single store
/// and thus must be phi-ed with undef. We fall back to the standard alloca
/// promotion algorithm in that case.
static bool rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info,
                                     LargeBlockInfo &LBI, const DataLayout &DL,
                                     DominatorTree &DT, AssumptionCache *AC) {
  StoreInst *OnlyStore = Info.OnlyStore;
  bool StoringGlobalVal = !isa<Instruction>(OnlyStore->getOperand(0));
  BasicBlock *StoreBB = OnlyStore->getParent();
  int StoreIndex = -1;

  // Clear out UsingBlocks.  We will reconstruct it here if needed.
  Info.UsingBlocks.clear();

  for (auto UI = AI->user_begin(), E = AI->user_end(); UI != E;) {
    Instruction *UserInst = cast<Instruction>(*UI++);
    if (!isa<LoadInst>(UserInst)) {
      assert(UserInst == OnlyStore && "Should only have load/stores");
      continue;
    }
    LoadInst *LI = cast<LoadInst>(UserInst);

    // Okay, if we have a load from the alloca, we want to replace it with the
    // only value stored to the alloca.  We can do this if the value is
    // dominated by the store.  If not, we use the rest of the mem2reg machinery
    // to insert the phi nodes as needed.
    if (!StoringGlobalVal) { // Non-instructions are always dominated.
      if (LI->getParent() == StoreBB) {
        // If we have a use that is in the same block as the store, compare the
        // indices of the two instructions to see which one came first.  If the
        // load came before the store, we can't handle it.
        if (StoreIndex == -1)
          StoreIndex = LBI.getInstructionIndex(OnlyStore);

        if (unsigned(StoreIndex) > LBI.getInstructionIndex(LI)) {
          // Can't handle this load, bail out.
          Info.UsingBlocks.push_back(StoreBB);
          continue;
        }
      } else if (LI->getParent() != StoreBB &&
                 !DT.dominates(StoreBB, LI->getParent())) {
        // If the load and store are in different blocks, use BB dominance to
        // check their relationships.  If the store doesn't dom the use, bail
        // out.
        Info.UsingBlocks.push_back(LI->getParent());
        continue;
      }
    }

    // Otherwise, we *can* safely rewrite this load.
    Value *ReplVal = OnlyStore->getOperand(0);
    // If the replacement value is the load, this must occur in unreachable
    // code.
    if (ReplVal == LI)
      ReplVal = UndefValue::get(LI->getType());

    // If the load was marked as nonnull we don't want to lose
    // that information when we erase this Load. So we preserve
    // it with an assume.
    if (AC && LI->getMetadata(LLVMContext::MD_nonnull) &&
        !isKnownNonZero(ReplVal, DL, 0, AC, LI, &DT))
      addAssumeNonNull(AC, LI);

    LI->replaceAllUsesWith(ReplVal);
    LI->eraseFromParent();
    LBI.deleteValue(LI);
  }

  // Finally, after the scan, check to see if the store is all that is left.
  if (!Info.UsingBlocks.empty())
    return false; // If not, we'll have to fall back for the remainder.

  // Record debuginfo for the store and remove the declaration's
  // debuginfo.
  for (DbgVariableIntrinsic *DII : Info.DbgDeclares) {
    DIBuilder DIB(*AI->getModule(), /*AllowUnresolved*/ false);
    ConvertDebugDeclareToDebugValue(DII, Info.OnlyStore, DIB);
    DII->eraseFromParent();
    LBI.deleteValue(DII);
  }
  // Remove the (now dead) store and alloca.
  Info.OnlyStore->eraseFromParent();
  LBI.deleteValue(Info.OnlyStore);

  AI->eraseFromParent();
  LBI.deleteValue(AI);
  return true;
}