// All edges with successors that aren't branches are "complex", because it
// requires complex logic to pick which counter to update.
GlobalVariable *GCOVProfiler::buildEdgeLookupTable(
Function *F,
GlobalVariable *Counters,
const UniqueVector<BasicBlock *> &Preds,
const UniqueVector<BasicBlock *> &Succs) {
// TODO: support invoke, threads. We rely on the fact that nothing can modify
// the whole-Module pred edge# between the time we set it and the time we next
// read it. Threads and invoke make this untrue.
// emit [(succs * preds) x i64*], logically [succ x [pred x i64*]].
Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
ArrayType *EdgeTableTy = ArrayType::get(
Int64PtrTy, Succs.size() * Preds.size());
Constant **EdgeTable = new Constant*[Succs.size() * Preds.size()];
Constant *NullValue = Constant::getNullValue(Int64PtrTy);
for (int i = 0, ie = Succs.size() * Preds.size(); i != ie; ++i)
EdgeTable[i] = NullValue;
unsigned Edge = 0;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
TerminatorInst *TI = BB->getTerminator();
int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
if (Successors > 1 && !isa<BranchInst>(TI) && !isa<ReturnInst>(TI)) {
for (int i = 0; i != Successors; ++i) {
BasicBlock *Succ = TI->getSuccessor(i);
IRBuilder<> builder(Succ);
Value *Counter = builder.CreateConstInBoundsGEP2_64(Counters, 0,
Edge + i);
EdgeTable[((Succs.idFor(Succ)-1) * Preds.size()) +
(Preds.idFor(BB)-1)] = cast<Constant>(Counter);
}
}
Edge += Successors;
}
ArrayRef<Constant*> V(&EdgeTable[0], Succs.size() * Preds.size());
GlobalVariable *EdgeTableGV =
new GlobalVariable(
*M, EdgeTableTy, true, GlobalValue::InternalLinkage,
ConstantArray::get(EdgeTableTy, V),
"__llvm_gcda_edge_table");
EdgeTableGV->setUnnamedAddr(true);
return EdgeTableGV;
}
// Propagate existing explicit probabilities from either profile data or
// 'expect' intrinsic processing.
bool BranchProbabilityInfo::calcMetadataWeights(BasicBlock *BB) {
TerminatorInst *TI = BB->getTerminator();
if (TI->getNumSuccessors() == 1)
return false;
if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
return false;
MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof);
if (!WeightsNode)
return false;
// Ensure there are weights for all of the successors. Note that the first
// operand to the metadata node is a name, not a weight.
if (WeightsNode->getNumOperands() != TI->getNumSuccessors() + 1)
return false;
// Build up the final weights that will be used in a temporary buffer, but
// don't add them until all weihts are present. Each weight value is clamped
// to [1, getMaxWeightFor(BB)].
uint32_t WeightLimit = getMaxWeightFor(BB);
SmallVector<uint32_t, 2> Weights;
Weights.reserve(TI->getNumSuccessors());
for (unsigned i = 1, e = WeightsNode->getNumOperands(); i != e; ++i) {
ConstantInt *Weight = dyn_cast<ConstantInt>(WeightsNode->getOperand(i));
if (!Weight)
return false;
Weights.push_back(
std::max<uint32_t>(1, Weight->getLimitedValue(WeightLimit)));
}
assert(Weights.size() == TI->getNumSuccessors() && "Checked above");
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
setEdgeWeight(BB, TI->getSuccessor(i), Weights[i]);
return true;
}
///////////////////
// NEW begin
///////////////////
// check dynamic pair satisfy anti-dependency
bool idenRegion::isAntiDepPair(LoadInst *Load, StoreInst *Store) {
// perform a DFS to check if store is after load
typedef std::pair<BasicBlock *, BasicBlock::iterator> WorkItem;
SmallVector<WorkItem, 8> Worklist;
SmallPtrSet<BasicBlock *, 32> Visited;
BasicBlock *LoadBB = Load->getParent();
Worklist.push_back(WorkItem(LoadBB, Load));
do {
BasicBlock *BB;
BasicBlock::iterator I, E;
tie(BB, I) = Worklist.pop_back_val();
errs() << "... On BB " << BB->getName() << "\n";
// If we revisited LoadBB, we scan to Load to complete cycle
// Otherwise we end at BB->end()
E = (BB == LoadBB && I == BB->begin()) ? Load : BB->end();
// errs() << "... Last instruction on current BB is " << getLocator(*E) << "\n";
// iterate throught BB to check if Load instruction exist in the BB
while (I != E) {
// errs() << "...... Inst: " << getLocator(*I) << "\n";
if (isa<StoreInst>(I) && dyn_cast<StoreInst>(I) == Store) {
return true;
}
++I;
}
// get current BB's succesor
TerminatorInst* ti = BB->getTerminator();
int numSuccesor = ti->getNumSuccessors();
for (int i = 0; i < numSuccesor; i++) {
BasicBlock* nextSuc = ti->getSuccessor(i);
// don't count backedge
if (Visited.insert(nextSuc) && !DT->dominates(nextSuc, BB)) {
Worklist.push_back(WorkItem(nextSuc, nextSuc->begin()));
}
}
} while(!Worklist.empty());
return false;
}
// Propagate existing explicit probabilities from either profile data or
// 'expect' intrinsic processing.
bool BranchProbabilityInfo::calcMetadataWeights(BasicBlock *BB) {
TerminatorInst *TI = BB->getTerminator();
if (TI->getNumSuccessors() == 1)
return false;
if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
return false;
MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof);
if (!WeightsNode)
return false;
// Check that the number of successors is manageable.
assert(TI->getNumSuccessors() < UINT32_MAX && "Too many successors");
// Ensure there are weights for all of the successors. Note that the first
// operand to the metadata node is a name, not a weight.
if (WeightsNode->getNumOperands() != TI->getNumSuccessors() + 1)
return false;
// Build up the final weights that will be used in a temporary buffer.
// Compute the sum of all weights to later decide whether they need to
// be scaled to fit in 32 bits.
uint64_t WeightSum = 0;
SmallVector<uint32_t, 2> Weights;
Weights.reserve(TI->getNumSuccessors());
for (unsigned i = 1, e = WeightsNode->getNumOperands(); i != e; ++i) {
ConstantInt *Weight =
mdconst::dyn_extract<ConstantInt>(WeightsNode->getOperand(i));
if (!Weight)
return false;
assert(Weight->getValue().getActiveBits() <= 32 &&
"Too many bits for uint32_t");
Weights.push_back(Weight->getZExtValue());
WeightSum += Weights.back();
}
assert(Weights.size() == TI->getNumSuccessors() && "Checked above");
// If the sum of weights does not fit in 32 bits, scale every weight down
// accordingly.
uint64_t ScalingFactor =
(WeightSum > UINT32_MAX) ? WeightSum / UINT32_MAX + 1 : 1;
WeightSum = 0;
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
uint32_t W = Weights[i] / ScalingFactor;
WeightSum += W;
setEdgeWeight(BB, i, W);
}
assert(WeightSum <= UINT32_MAX &&
"Expected weights to scale down to 32 bits");
return true;
}
void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) {
TerminatorInst *TI = getTerminator();
if (!TI)
// Cope with being called on a BasicBlock that doesn't have a terminator
// yet. Clang's CodeGenFunction::EmitReturnBlock() likes to do this.
return;
for (BasicBlock *Succ : TI->successors()) {
// N.B. Succ might not be a complete BasicBlock, so don't assume
// that it ends with a non-phi instruction.
for (iterator II = Succ->begin(), IE = Succ->end(); II != IE; ++II) {
PHINode *PN = dyn_cast<PHINode>(II);
if (!PN)
break;
int i;
while ((i = PN->getBasicBlockIndex(this)) >= 0)
PN->setIncomingBlock(i, New);
}
}
}
void Loop::setLoopID(MDNode *LoopID) const {
assert(LoopID && "Loop ID should not be null");
assert(LoopID->getNumOperands() > 0 && "Loop ID needs at least one operand");
assert(LoopID->getOperand(0) == LoopID && "Loop ID should refer to itself");
if (isLoopSimplifyForm()) {
getLoopLatch()->getTerminator()->setMetadata(LLVMContext::MD_loop, LoopID);
return;
}
BasicBlock *H = getHeader();
for (BasicBlock *BB : this->blocks()) {
TerminatorInst *TI = BB->getTerminator();
for (BasicBlock *Successor : TI->successors()) {
if (Successor == H)
TI->setMetadata(LLVMContext::MD_loop, LoopID);
}
}
}
/// MatchLoopHeaderHeuristic - Predict a successor that is a loop header or
/// a loop pre-header and does not post-dominate will be taken.
/// @returns a Prediction that is a pair in which the first element is the
/// successor taken, and the second the successor not taken.
Prediction BranchHeuristicsInfo::MatchLoopHeaderHeuristic(BasicBlock *root)
const {
bool matched = false;
Prediction pred;
// Last instruction of basic block.
TerminatorInst *TI = root->getTerminator();
// Basic block successors. True and False branches.
BasicBlock *trueSuccessor = TI->getSuccessor(0);
BasicBlock *falseSuccessor = TI->getSuccessor(1);
// Get the most inner loop in which the true successor basic block is in.
Loop *loop = LI->getLoopFor(trueSuccessor);
// Check if exists a loop, the true branch successor is a loop header or a
// loop pre-header, and does not post dominate.
if (loop && (trueSuccessor == loop->getHeader() ||
trueSuccessor == loop->getLoopPreheader()) &&
!PDT->dominates(trueSuccessor, root)) {
matched = true;
pred = std::make_pair(trueSuccessor, falseSuccessor);
}
// Get the most inner loop in which the false successor basic block is in.
loop = LI->getLoopFor(falseSuccessor);
// Check if exists a loop,
// the false branch successor is a loop header or a loop pre-header, and
// does not post dominate.
if (loop && (falseSuccessor == loop->getHeader() ||
falseSuccessor == loop->getLoopPreheader()) &&
!PDT->dominates(falseSuccessor, root)) {
// If the heuristic matches both branches, predict none.
if (matched)
return empty;
matched = true;
pred = std::make_pair(falseSuccessor, trueSuccessor);
}
return (matched ? pred : empty);
}
/// MatchPointerHeuristic - Predict that a comparison of a pointer against
/// null or of two pointers will fail.
/// @returns a Prediction that is a pair in which the first element is the
/// successor taken, and the second the successor not taken.
Prediction BranchHeuristicsInfo::MatchPointerHeuristic(BasicBlock *root) const {
// Last instruction of basic block.
TerminatorInst *TI = root->getTerminator();
// Basic block successors. True and False branches.
BasicBlock *trueSuccessor = TI->getSuccessor(0);
BasicBlock *falseSuccessor = TI->getSuccessor(1);
// Is the last instruction a Branch Instruction?
BranchInst *BI = dyn_cast<BranchInst>(TI);
if (!BI || !BI->isConditional())
return empty;
// Conditional instruction.
Value *cond = BI->getCondition();
// Pointer comparisons are integer comparisons.
ICmpInst *II = dyn_cast<ICmpInst>(cond);
if (!II)
return empty;
// An integer comparison has always two operands.
Value *operand1 = II->getOperand(0);
Value *operand2 = II->getOperand(1);
// Obtain the type of comparison.
enum ICmpInst::Predicate signedPred = II->getSignedPredicate();
// The heuristic states that it must be compared against null,
// but in LLVM, null is also a PointerType, so it only requires
// to test if there is a comparison between two pointers.
if (signedPred == ICmpInst::ICMP_EQ &&
isa<PointerType>(operand1->getType()) && // NULL is a pointer type too
isa<PointerType>(operand2->getType())) { // NULL is a pointer type too
return std::make_pair(falseSuccessor, trueSuccessor);
} else if (signedPred != ICmpInst::ICMP_EQ &&
isa<PointerType>(operand1->getType()) &&
isa<PointerType>(operand2->getType())) {
return std::make_pair(trueSuccessor, falseSuccessor);
}
return empty;
}
void Loop::setLoopID(MDNode *LoopID) const {
assert(LoopID && "Loop ID should not be null");
assert(LoopID->getNumOperands() > 0 && "Loop ID needs at least one operand");
assert(LoopID->getOperand(0) == LoopID && "Loop ID should refer to itself");
if (isLoopSimplifyForm()) {
getLoopLatch()->getTerminator()->setMetadata(LoopMDName, LoopID);
return;
}
BasicBlock *H = getHeader();
for (block_iterator I = block_begin(), IE = block_end(); I != IE; ++I) {
TerminatorInst *TI = (*I)->getTerminator();
for (unsigned i = 0, ie = TI->getNumSuccessors(); i != ie; ++i) {
if (TI->getSuccessor(i) == H)
TI->setMetadata(LoopMDName, LoopID);
}
}
}
TerminatorInst *
llvm::SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore,
bool Unreachable, MDNode *BranchWeights,
DominatorTree *DT, LoopInfo *LI) {
BasicBlock *Head = SplitBefore->getParent();
BasicBlock *Tail = Head->splitBasicBlock(SplitBefore->getIterator());
TerminatorInst *HeadOldTerm = Head->getTerminator();
LLVMContext &C = Head->getContext();
BasicBlock *ThenBlock = BasicBlock::Create(C, "", Head->getParent(), Tail);
TerminatorInst *CheckTerm;
if (Unreachable)
CheckTerm = new UnreachableInst(C, ThenBlock);
else
CheckTerm = BranchInst::Create(Tail, ThenBlock);
CheckTerm->setDebugLoc(SplitBefore->getDebugLoc());
BranchInst *HeadNewTerm =
BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cond);
HeadNewTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
if (DT) {
if (DomTreeNode *OldNode = DT->getNode(Head)) {
std::vector<DomTreeNode *> Children(OldNode->begin(), OldNode->end());
DomTreeNode *NewNode = DT->addNewBlock(Tail, Head);
for (DomTreeNode *Child : Children)
DT->changeImmediateDominator(Child, NewNode);
// Head dominates ThenBlock.
DT->addNewBlock(ThenBlock, Head);
}
}
if (LI) {
if (Loop *L = LI->getLoopFor(Head)) {
L->addBasicBlockToLoop(ThenBlock, *LI);
L->addBasicBlockToLoop(Tail, *LI);
}
}
return CheckTerm;
}
/// matchEdges - Link every profile counter with an edge.
unsigned ProfileMetadataLoaderPass::matchEdges(Module &M, ProfileData &PB,
ArrayRef<unsigned> Counters) {
if (Counters.size() == 0) return 0;
unsigned ReadCount = 0;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (F->isDeclaration()) continue;
DEBUG(dbgs() << "Loading edges in '" << F->getName() << "'\n");
readEdge(ReadCount++, PB, PB.getEdge(0, &F->getEntryBlock()), Counters);
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
TerminatorInst *TI = BB->getTerminator();
for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s) {
readEdge(ReadCount++, PB, PB.getEdge(BB,TI->getSuccessor(s)),
Counters);
}
}
}
return ReadCount;
}
void hammock::findIR (BasicBlock *bBOring, BasicBlock *bBSuss, PostDominatorTree &PD) {
TerminatorInst *ti = bBSuss->getTerminator();
if (bBlocks.count(bBSuss)>0) {
return;
}
//Mark BasicBlock
bBlocks.insert(bBSuss);
//If the basic block is a posdominator and is not the start basic block, just return
if (PD.dominates(bBSuss, bBOring) && bBSuss != bBOring) {
return;
}else { //Advance the flooding
//If there is successor, go there
for (unsigned int i=0; i<ti->getNumSuccessors(); i++) {
findIR (bBOring, ti->getSuccessor(i), PD);
}
}
}
// In this pass we look for GEP and cast instructions that are used
// across basic blocks and rewrite them to improve basic-block-at-a-time
// selection.
bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) {
bool MadeChange = false;
// Split all critical edges where the dest block has a PHI.
if (CriticalEdgeSplit) {
TerminatorInst *BBTI = BB.getTerminator();
if (BBTI->getNumSuccessors() > 1 && !isa<IndirectBrInst>(BBTI)) {
for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i) {
BasicBlock *SuccBB = BBTI->getSuccessor(i);
if (isa<PHINode>(SuccBB->begin()) && isCriticalEdge(BBTI, i, true))
SplitEdgeNicely(BBTI, i, BackEdges, this);
}
}
}
SunkAddrs.clear();
CurInstIterator = BB.begin();
for (BasicBlock::iterator E = BB.end(); CurInstIterator != E; )
MadeChange |= OptimizeInst(CurInstIterator++);
return MadeChange;
}
void AddressSanitizer::instrumentAddress(AsanFunctionContext &AFC,
Instruction *OrigIns,
IRBuilder<> &IRB, Value *Addr,
uint32_t TypeSize, bool IsWrite) {
Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
Type *ShadowTy = IntegerType::get(
*C, std::max(8U, TypeSize >> MappingScale));
Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
Value *ShadowPtr = memToShadow(AddrLong, IRB);
Value *CmpVal = Constant::getNullValue(ShadowTy);
Value *ShadowValue = IRB.CreateLoad(
IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
size_t Granularity = 1 << MappingScale;
TerminatorInst *CrashTerm = 0;
if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
TerminatorInst *CheckTerm = splitBlockAndInsertIfThen(Cmp, false);
assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
BasicBlock *NextBB = CheckTerm->getSuccessor(0);
IRB.SetInsertPoint(CheckTerm);
Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
BasicBlock *CrashBlock = BasicBlock::Create(*C, "", &AFC.F, NextBB);
CrashTerm = new UnreachableInst(*C, CrashBlock);
BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
ReplaceInstWithInst(CheckTerm, NewTerm);
} else {
CrashTerm = splitBlockAndInsertIfThen(Cmp, true);
}
Instruction *Crash =
generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
Crash->setDebugLoc(OrigIns->getDebugLoc());
}
/// setBranchWeightMetadata - Translate the counter values associated with each
/// edge into branch weights for each conditional branch (a branch with 2 or
/// more desinations).
void ProfileMetadataLoaderPass::setBranchWeightMetadata(Module &M,
ProfileData &PB) {
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (F->isDeclaration()) continue;
DEBUG(dbgs() << "Setting branch metadata in '" << F->getName() << "'\n");
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
TerminatorInst *TI = BB->getTerminator();
unsigned NumSuccessors = TI->getNumSuccessors();
// If there is only one successor then we can not set a branch
// probability as the target is certain.
if (NumSuccessors < 2) continue;
// Load the weights of all edges leading from this terminator.
DEBUG(dbgs() << "-- Terminator with " << NumSuccessors
<< " successors:\n");
SmallVector<uint32_t, 4> Weights(NumSuccessors);
for (unsigned s = 0 ; s < NumSuccessors ; ++s) {
ProfileData::Edge edge = PB.getEdge(BB, TI->getSuccessor(s));
Weights[s] = (uint32_t)PB.getEdgeWeight(edge);
DEBUG(dbgs() << "---- Edge '" << edge << "' has weight "
<< Weights[s] << "\n");
}
// Set branch weight metadata. This will set branch probabilities of
// 100%/0% if that is true of the dynamic execution.
// BranchProbabilityInfo can account for this when it loads this metadata
// (it gives the unexectuted branch a weight of 1 for the purposes of
// probability calculations).
MDBuilder MDB(TI->getContext());
MDNode *Node = MDB.createBranchWeights(Weights);
TI->setMetadata(LLVMContext::MD_prof, Node);
NumTermsAnnotated++;
}
}
}
/// MatchLoopBranchHeuristic - Predict as taken an edge back to a loop's
/// head. Predict as not taken an edge exiting a loop.
/// @returns a Prediction that is a pair in which the first element is the
/// successor taken, and the second the successor not taken.
Prediction BranchHeuristicsInfo::MatchLoopBranchHeuristic(BasicBlock *root)
const {
bool matched = false;
Prediction pred;
// Last instruction of basic block.
TerminatorInst *TI = root->getTerminator();
// Basic block successors. True and False branches.
BasicBlock *trueSuccessor = TI->getSuccessor(0);
BasicBlock *falseSuccessor = TI->getSuccessor(1);
// True and false branch edges.
Edge trueEdge = std::make_pair(root, trueSuccessor);
Edge falseEdge = std::make_pair(root, falseSuccessor);
// If the true branch is a back edge to a loop's head or the false branch is
// an exit edge, match the heuristic.
if ((BPI->isBackEdge(trueEdge) && LI->isLoopHeader(trueSuccessor)) ||
BPI->isExitEdge(falseEdge)) {
matched = true;
pred = std::make_pair(trueSuccessor, falseSuccessor);
}
// Check the opposite situation, the other branch.
if ((BPI->isBackEdge(falseEdge) && LI->isLoopHeader(falseSuccessor)) ||
BPI->isExitEdge(trueEdge)) {
// If the heuristic matches both branches, predict none.
if (matched)
return empty;
matched = true;
pred = std::make_pair(falseSuccessor, trueSuccessor);
}
return (matched ? pred : empty);
}
void llvm::DeleteDeadBlock(BasicBlock *BB, DeferredDominance *DDT) {
assert((pred_begin(BB) == pred_end(BB) ||
// Can delete self loop.
BB->getSinglePredecessor() == BB) && "Block is not dead!");
TerminatorInst *BBTerm = BB->getTerminator();
std::vector<DominatorTree::UpdateType> Updates;
// Loop through all of our successors and make sure they know that one
// of their predecessors is going away.
if (DDT)
Updates.reserve(BBTerm->getNumSuccessors());
for (BasicBlock *Succ : BBTerm->successors()) {
Succ->removePredecessor(BB);
if (DDT)
Updates.push_back({DominatorTree::Delete, BB, Succ});
}
// Zap all the instructions in the block.
while (!BB->empty()) {
Instruction &I = BB->back();
// If this instruction is used, replace uses with an arbitrary value.
// Because control flow can't get here, we don't care what we replace the
// value with. Note that since this block is unreachable, and all values
// contained within it must dominate their uses, that all uses will
// eventually be removed (they are themselves dead).
if (!I.use_empty())
I.replaceAllUsesWith(UndefValue::get(I.getType()));
BB->getInstList().pop_back();
}
if (DDT) {
DDT->applyUpdates(Updates);
DDT->deleteBB(BB); // Deferred deletion of BB.
} else {
BB->eraseFromParent(); // Zap the block!
}
}
void CheckInserter::insertCycleChecks(Function &F) {
IdentifyBackEdges &IBE = getAnalysis<IdentifyBackEdges>();
for (Function::iterator B1 = F.begin(); B1 != F.end(); ++B1) {
TerminatorInst *TI = B1->getTerminator();
for (unsigned j = 0; j < TI->getNumSuccessors(); ++j) {
BasicBlock *B2 = TI->getSuccessor(j);
unsigned BackEdgeID = IBE.getID(B1, B2);
if (BackEdgeID != (unsigned)-1) {
assert(BackEdgeID < MaxNumBackEdges);
BasicBlock *BackEdgeBlock = BasicBlock::Create(
F.getContext(),
"backedge_" + B1->getName() + "_" + B2->getName(),
&F);
CallInst::Create(CycleCheck,
ConstantInt::get(IntType, BackEdgeID),
"",
BackEdgeBlock);
// BackEdgeBlock -> B2
// Fix the PHINodes in B2.
BranchInst::Create(B2, BackEdgeBlock);
for (BasicBlock::iterator I = B2->begin();
B2->getFirstNonPHI() != I;
++I) {
PHINode *PHI = cast<PHINode>(I);
// Note: If B2 has multiple incoming edges from B1 (e.g. B1 terminates
// with a SelectInst), its PHINodes must also have multiple incoming
// edges from B1. However, after adding BackEdgeBlock and essentially
// merging the multiple incoming edges from B1, there will be only one
// edge from BackEdgeBlock to B2. Therefore, we need to remove the
// redundant incoming edges from B2's PHINodes.
bool FirstIncomingFromB1 = true;
for (unsigned k = 0; k < PHI->getNumIncomingValues(); ++k) {
if (PHI->getIncomingBlock(k) == B1) {
if (FirstIncomingFromB1) {
FirstIncomingFromB1 = false;
PHI->setIncomingBlock(k, BackEdgeBlock);
} else {
PHI->removeIncomingValue(k, false);
--k;
}
}
}
}
// B1 -> BackEdgeBlock
// There might be multiple back edges from B1 to B2. Need to replace
// them all.
for (unsigned j2 = j; j2 < TI->getNumSuccessors(); ++j2) {
if (TI->getSuccessor(j2) == B2) {
TI->setSuccessor(j2, BackEdgeBlock);
}
}
}
}
}
}
//Return true if the subgraph denoted by bBlocks set attribute is a hammock graph
bool hammock::checkHammock (Function &F) {
//For each basicBlock
for (Function::iterator Fit = F.begin(), Fend = F.end(); Fit != Fend; ++Fit) {
TerminatorInst *ti = Fit->getTerminator();
if (bBlocks.count(Fit)==0) { //If it is out of subgraph
//Check if some respective successor is marked
for (unsigned int i=0; i<ti->getNumSuccessors(); i++) {
if (bBlocks.count(ti->getSuccessor(i))>0) {
return false;
}
}
}else { /*//If it is in subgrah
//Check if some respective successor is NOT marked
for (unsigned int i=0; i<ti->getNumSuccessors(); i++) {
if (bBlocks.count(ti->getSuccessor(i))==0) {
return false;
}
}*/
}
}
return true;
}
// visitCallInst - This converts all LLVM call instructions into invoke
// instructions. The except part of the invoke goes to the "LongJmpBlkPre"
// that grabs the exception and proceeds to determine if it's a longjmp
// exception or not.
void LowerSetJmp::visitCallInst(CallInst& CI)
{
if (CI.getCalledFunction())
if (!IsTransformableFunction(CI.getCalledFunction()->getName()) ||
CI.getCalledFunction()->isIntrinsic()) return;
BasicBlock* OldBB = CI.getParent();
// If not reachable from a setjmp call, don't transform.
if (!DFSBlocks.count(OldBB)) return;
BasicBlock* NewBB = OldBB->splitBasicBlock(CI);
assert(NewBB && "Couldn't split BB of \"call\" instruction!!");
DFSBlocks.insert(NewBB);
NewBB->setName("Call2Invoke");
Function* Func = OldBB->getParent();
// Construct the new "invoke" instruction.
TerminatorInst* Term = OldBB->getTerminator();
CallSite CS(&CI);
std::vector<Value*> Params(CS.arg_begin(), CS.arg_end());
InvokeInst* II =
InvokeInst::Create(CI.getCalledValue(), NewBB, PrelimBBMap[Func],
Params.begin(), Params.end(), CI.getName(), Term);
II->setCallingConv(CI.getCallingConv());
II->setAttributes(CI.getAttributes());
// Replace the old call inst with the invoke inst and remove the call.
CI.replaceAllUsesWith(II);
CI.eraseFromParent();
// The old terminator is useless now that we have the invoke inst.
Term->eraseFromParent();
++CallsTransformed;
}
/// SplitEdge - Split the edge connecting specified block. Pass P must
/// not be NULL.
BasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, Pass *P) {
unsigned SuccNum = GetSuccessorNumber(BB, Succ);
// If this is a critical edge, let SplitCriticalEdge do it.
TerminatorInst *LatchTerm = BB->getTerminator();
if (SplitCriticalEdge(LatchTerm, SuccNum, P))
return LatchTerm->getSuccessor(SuccNum);
// If the edge isn't critical, then BB has a single successor or Succ has a
// single pred. Split the block.
if (BasicBlock *SP = Succ->getSinglePredecessor()) {
// If the successor only has a single pred, split the top of the successor
// block.
assert(SP == BB && "CFG broken");
SP = NULL;
return SplitBlock(Succ, Succ->begin(), P);
}
// Otherwise, if BB has a single successor, split it at the bottom of the
// block.
assert(BB->getTerminator()->getNumSuccessors() == 1 &&
"Should have a single succ!");
return SplitBlock(BB, BB->getTerminator(), P);
}
// Cleanly removes a terminator instruction.
void GNUstep::removeTerminator(BasicBlock *BB) {
TerminatorInst *BBTerm = BB->getTerminator();
// Remove the BB as a predecessor from all of successors
for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i) {
BBTerm->getSuccessor(i)->removePredecessor(BB);
}
BBTerm->replaceAllUsesWith(UndefValue::get(BBTerm->getType()));
// Remove the terminator instruction itself.
BBTerm->eraseFromParent();
}
/// shouldEliminateUnconditionalBranch - Return true if this branch looks
/// attractive to eliminate. We eliminate the branch if the destination basic
/// block has <= 5 instructions in it, not counting PHI nodes. In practice,
/// since one of these is a terminator instruction, this means that we will add
/// up to 4 instructions to the new block.
///
/// We don't count PHI nodes in the count since they will be removed when the
/// contents of the block are copied over.
///
bool TailDup::shouldEliminateUnconditionalBranch(TerminatorInst *TI,
unsigned Threshold) {
BranchInst *BI = dyn_cast<BranchInst>(TI);
if (!BI || !BI->isUnconditional()) return false; // Not an uncond branch!
BasicBlock *Dest = BI->getSuccessor(0);
if (Dest == BI->getParent()) return false; // Do not loop infinitely!
// Do not inline a block if we will just get another branch to the same block!
TerminatorInst *DTI = Dest->getTerminator();
if (BranchInst *DBI = dyn_cast<BranchInst>(DTI))
if (DBI->isUnconditional() && DBI->getSuccessor(0) == Dest)
return false; // Do not loop infinitely!
// FIXME: DemoteRegToStack cannot yet demote invoke instructions to the stack,
// because doing so would require breaking critical edges. This should be
// fixed eventually.
if (!DTI->use_empty())
return false;
// Do not bother with blocks with only a single predecessor: simplify
// CFG will fold these two blocks together!
pred_iterator PI = pred_begin(Dest), PE = pred_end(Dest);
++PI;
if (PI == PE) return false; // Exactly one predecessor!
BasicBlock::iterator I = Dest->getFirstNonPHI();
for (unsigned Size = 0; I != Dest->end(); ++I) {
if (Size == Threshold) return false; // The block is too large.
// Don't tail duplicate call instructions. They are very large compared to
// other instructions.
if (isa<CallInst>(I) || isa<InvokeInst>(I)) return false;
// Also alloca and malloc.
if (isa<AllocaInst>(I)) return false;
// Some vector instructions can expand into a number of instructions.
if (isa<ShuffleVectorInst>(I) || isa<ExtractElementInst>(I) ||
isa<InsertElementInst>(I)) return false;
// Only count instructions that are not debugger intrinsics.
if (!isa<DbgInfoIntrinsic>(I)) ++Size;
}
// Do not tail duplicate a block that has thousands of successors into a block
// with a single successor if the block has many other predecessors. This can
// cause an N^2 explosion in CFG edges (and PHI node entries), as seen in
// cases that have a large number of indirect gotos.
unsigned NumSuccs = DTI->getNumSuccessors();
if (NumSuccs > 8) {
unsigned TooMany = 128;
if (NumSuccs >= TooMany) return false;
TooMany = TooMany/NumSuccs;
for (; PI != PE; ++PI)
if (TooMany-- == 0) return false;
}
// If this unconditional branch is a fall-through, be careful about
// tail duplicating it. In particular, we don't want to taildup it if the
// original block will still be there after taildup is completed: doing so
// would eliminate the fall-through, requiring unconditional branches.
Function::iterator DestI = Dest;
if (&*--DestI == BI->getParent()) {
// The uncond branch is a fall-through. Tail duplication of the block is
// will eliminate the fall-through-ness and end up cloning the terminator
// at the end of the Dest block. Since the original Dest block will
// continue to exist, this means that one or the other will not be able to
// fall through. One typical example that this helps with is code like:
// if (a)
// foo();
// if (b)
// foo();
// Cloning the 'if b' block into the end of the first foo block is messy.
// The messy case is when the fall-through block falls through to other
// blocks. This is what we would be preventing if we cloned the block.
DestI = Dest;
if (++DestI != Dest->getParent()->end()) {
BasicBlock *DestSucc = DestI;
// If any of Dest's successors are fall-throughs, don't do this xform.
for (succ_iterator SI = succ_begin(Dest), SE = succ_end(Dest);
SI != SE; ++SI)
if (*SI == DestSucc)
return false;
}
}
// Finally, check that we haven't redirected to this target block earlier;
// there are cases where we loop forever if we don't check this (PR 2323).
if (!CycleDetector.insert(Dest))
return false;
return true;
}
bool OptimalEdgeProfiler::runOnModule(Module &M) {
Function *Main = M.getFunction("main");
if (Main == 0) {
errs() << "WARNING: cannot insert edge profiling into a module"
<< " with no main function!\n";
return false; // No main, no instrumentation!
}
// NumEdges counts all the edges that may be instrumented. Later on its
// decided which edges to actually instrument, to achieve optimal profiling.
// For the entry block a virtual edge (0,entry) is reserved, for each block
// with no successors an edge (BB,0) is reserved. These edges are necessary
// to calculate a truly optimal maximum spanning tree and thus an optimal
// instrumentation.
unsigned NumEdges = 0;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (F->isDeclaration()) continue;
// Reserve space for (0,entry) edge.
++NumEdges;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
// Keep track of which blocks need to be instrumented. We don't want to
// instrument blocks that are added as the result of breaking critical
// edges!
if (BB->getTerminator()->getNumSuccessors() == 0) {
// Reserve space for (BB,0) edge.
++NumEdges;
} else {
NumEdges += BB->getTerminator()->getNumSuccessors();
}
}
}
// In the profiling output a counter for each edge is reserved, but only few
// are used. This is done to be able to read back in the profile without
// calulating the maximum spanning tree again, instead each edge counter that
// is not used is initialised with -1 to signal that this edge counter has to
// be calculated from other edge counters on reading the profile info back
// in.
const Type *Int32 = Type::getInt32Ty(M.getContext());
const ArrayType *ATy = ArrayType::get(Int32, NumEdges);
GlobalVariable *Counters =
new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
Constant::getNullValue(ATy), "OptEdgeProfCounters");
NumEdgesInserted = 0;
std::vector<Constant*> Initializer(NumEdges);
Constant* Zero = ConstantInt::get(Int32, 0);
Constant* Uncounted = ConstantInt::get(Int32, ProfileInfoLoader::Uncounted);
// Instrument all of the edges not in MST...
unsigned i = 0;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (F->isDeclaration()) continue;
DEBUG(dbgs()<<"Working on "<<F->getNameStr()<<"\n");
// Calculate a Maximum Spanning Tree with the edge weights determined by
// ProfileEstimator. ProfileEstimator also assign weights to the virtual
// edges (0,entry) and (BB,0) (for blocks with no successors) and this
// edges also participate in the maximum spanning tree calculation.
// The third parameter of MaximumSpanningTree() has the effect that not the
// actual MST is returned but the edges _not_ in the MST.
ProfileInfo::EdgeWeights ECs =
getAnalysis<ProfileInfo>(*F).getEdgeWeights(F);
std::vector<ProfileInfo::EdgeWeight> EdgeVector(ECs.begin(), ECs.end());
MaximumSpanningTree<BasicBlock> MST (EdgeVector);
std::stable_sort(MST.begin(),MST.end());
// Check if (0,entry) not in the MST. If not, instrument edge
// (IncrementCounterInBlock()) and set the counter initially to zero, if
// the edge is in the MST the counter is initialised to -1.
BasicBlock *entry = &(F->getEntryBlock());
ProfileInfo::Edge edge = ProfileInfo::getEdge(0,entry);
if (!std::binary_search(MST.begin(), MST.end(), edge)) {
printEdgeCounter(edge,entry,i);
IncrementCounterInBlock(entry, i, Counters); ++NumEdgesInserted;
Initializer[i++] = (Zero);
} else{
Initializer[i++] = (Uncounted);
}
// InsertedBlocks contains all blocks that were inserted for splitting an
// edge, this blocks do not have to be instrumented.
DenseSet<BasicBlock*> InsertedBlocks;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
// Check if block was not inserted and thus does not have to be
// instrumented.
if (InsertedBlocks.count(BB)) continue;
// Okay, we have to add a counter of each outgoing edge not in MST. If
// the outgoing edge is not critical don't split it, just insert the
// counter in the source or destination of the edge. Also, if the block
// has no successors, the virtual edge (BB,0) is processed.
TerminatorInst *TI = BB->getTerminator();
if (TI->getNumSuccessors() == 0) {
ProfileInfo::Edge edge = ProfileInfo::getEdge(BB,0);
if (!std::binary_search(MST.begin(), MST.end(), edge)) {
printEdgeCounter(edge,BB,i);
IncrementCounterInBlock(BB, i, Counters); ++NumEdgesInserted;
Initializer[i++] = (Zero);
} else{
Initializer[i++] = (Uncounted);
}
}
for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s) {
BasicBlock *Succ = TI->getSuccessor(s);
ProfileInfo::Edge edge = ProfileInfo::getEdge(BB,Succ);
if (!std::binary_search(MST.begin(), MST.end(), edge)) {
// If the edge is critical, split it.
bool wasInserted = SplitCriticalEdge(TI, s, this);
Succ = TI->getSuccessor(s);
if (wasInserted)
InsertedBlocks.insert(Succ);
// Okay, we are guaranteed that the edge is no longer critical. If
// we only have a single successor, insert the counter in this block,
// otherwise insert it in the successor block.
if (TI->getNumSuccessors() == 1) {
// Insert counter at the start of the block
printEdgeCounter(edge,BB,i);
IncrementCounterInBlock(BB, i, Counters); ++NumEdgesInserted;
} else {
// Insert counter at the start of the block
printEdgeCounter(edge,Succ,i);
IncrementCounterInBlock(Succ, i, Counters); ++NumEdgesInserted;
}
Initializer[i++] = (Zero);
} else {
Initializer[i++] = (Uncounted);
}
}
}
}
// Check if the number of edges counted at first was the number of edges we
// considered for instrumentation.
assert(i==NumEdges && "the number of edges in counting array is wrong");
// Assing the now completely defined initialiser to the array.
Constant *init = ConstantArray::get(ATy, Initializer);
Counters->setInitializer(init);
// Add the initialization call to main.
InsertProfilingInitCall(Main, "llvm_start_opt_edge_profiling", Counters);
return true;
}
/// \brief Simplify one loop and queue further loops for simplification.
///
/// FIXME: Currently this accepts both lots of analyses that it uses and a raw
/// Pass pointer. The Pass pointer is used by numerous utilities to update
/// specific analyses. Rather than a pass it would be much cleaner and more
/// explicit if they accepted the analysis directly and then updated it.
static bool simplifyOneLoop(Loop *L, SmallVectorImpl<Loop *> &Worklist,
DominatorTree *DT, LoopInfo *LI,
ScalarEvolution *SE, Pass *PP,
AssumptionCache *AC) {
bool Changed = false;
ReprocessLoop:
// Check to see that no blocks (other than the header) in this loop have
// predecessors that are not in the loop. This is not valid for natural
// loops, but can occur if the blocks are unreachable. Since they are
// unreachable we can just shamelessly delete those CFG edges!
for (Loop::block_iterator BB = L->block_begin(), E = L->block_end();
BB != E; ++BB) {
if (*BB == L->getHeader()) continue;
SmallPtrSet<BasicBlock*, 4> BadPreds;
for (pred_iterator PI = pred_begin(*BB),
PE = pred_end(*BB); PI != PE; ++PI) {
BasicBlock *P = *PI;
if (!L->contains(P))
BadPreds.insert(P);
}
// Delete each unique out-of-loop (and thus dead) predecessor.
for (BasicBlock *P : BadPreds) {
DEBUG(dbgs() << "LoopSimplify: Deleting edge from dead predecessor "
<< P->getName() << "\n");
// Inform each successor of each dead pred.
for (succ_iterator SI = succ_begin(P), SE = succ_end(P); SI != SE; ++SI)
(*SI)->removePredecessor(P);
// Zap the dead pred's terminator and replace it with unreachable.
TerminatorInst *TI = P->getTerminator();
TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
P->getTerminator()->eraseFromParent();
new UnreachableInst(P->getContext(), P);
Changed = true;
}
}
// If there are exiting blocks with branches on undef, resolve the undef in
// the direction which will exit the loop. This will help simplify loop
// trip count computations.
SmallVector<BasicBlock*, 8> ExitingBlocks;
L->getExitingBlocks(ExitingBlocks);
for (SmallVectorImpl<BasicBlock *>::iterator I = ExitingBlocks.begin(),
E = ExitingBlocks.end(); I != E; ++I)
if (BranchInst *BI = dyn_cast<BranchInst>((*I)->getTerminator()))
if (BI->isConditional()) {
if (UndefValue *Cond = dyn_cast<UndefValue>(BI->getCondition())) {
DEBUG(dbgs() << "LoopSimplify: Resolving \"br i1 undef\" to exit in "
<< (*I)->getName() << "\n");
BI->setCondition(ConstantInt::get(Cond->getType(),
!L->contains(BI->getSuccessor(0))));
// This may make the loop analyzable, force SCEV recomputation.
if (SE)
SE->forgetLoop(L);
Changed = true;
}
}
// Does the loop already have a preheader? If so, don't insert one.
BasicBlock *Preheader = L->getLoopPreheader();
if (!Preheader) {
Preheader = InsertPreheaderForLoop(L, PP);
if (Preheader) {
++NumInserted;
Changed = true;
}
}
// Next, check to make sure that all exit nodes of the loop only have
// predecessors that are inside of the loop. This check guarantees that the
// loop preheader/header will dominate the exit blocks. If the exit block has
// predecessors from outside of the loop, split the edge now.
SmallVector<BasicBlock*, 8> ExitBlocks;
L->getExitBlocks(ExitBlocks);
SmallSetVector<BasicBlock *, 8> ExitBlockSet(ExitBlocks.begin(),
ExitBlocks.end());
for (SmallSetVector<BasicBlock *, 8>::iterator I = ExitBlockSet.begin(),
E = ExitBlockSet.end(); I != E; ++I) {
BasicBlock *ExitBlock = *I;
for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock);
PI != PE; ++PI)
// Must be exactly this loop: no subloops, parent loops, or non-loop preds
// allowed.
if (!L->contains(*PI)) {
if (rewriteLoopExitBlock(L, ExitBlock, DT, LI, PP)) {
++NumInserted;
Changed = true;
}
break;
}
}
// If the header has more than two predecessors at this point (from the
// preheader and from multiple backedges), we must adjust the loop.
BasicBlock *LoopLatch = L->getLoopLatch();
if (!LoopLatch) {
// If this is really a nested loop, rip it out into a child loop. Don't do
// this for loops with a giant number of backedges, just factor them into a
// common backedge instead.
if (L->getNumBackEdges() < 8) {
if (Loop *OuterL = separateNestedLoop(L, Preheader, DT, LI, SE, PP, AC)) {
++NumNested;
// Enqueue the outer loop as it should be processed next in our
// depth-first nest walk.
Worklist.push_back(OuterL);
// This is a big restructuring change, reprocess the whole loop.
Changed = true;
// GCC doesn't tail recursion eliminate this.
// FIXME: It isn't clear we can't rely on LLVM to TRE this.
goto ReprocessLoop;
}
}
// If we either couldn't, or didn't want to, identify nesting of the loops,
// insert a new block that all backedges target, then make it jump to the
// loop header.
LoopLatch = insertUniqueBackedgeBlock(L, Preheader, DT, LI);
if (LoopLatch) {
++NumInserted;
Changed = true;
}
}
const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
// Scan over the PHI nodes in the loop header. Since they now have only two
// incoming values (the loop is canonicalized), we may have simplified the PHI
// down to 'X = phi [X, Y]', which should be replaced with 'Y'.
PHINode *PN;
for (BasicBlock::iterator I = L->getHeader()->begin();
(PN = dyn_cast<PHINode>(I++)); )
if (Value *V = SimplifyInstruction(PN, DL, nullptr, DT, AC)) {
if (SE) SE->forgetValue(PN);
PN->replaceAllUsesWith(V);
PN->eraseFromParent();
}
// If this loop has multiple exits and the exits all go to the same
// block, attempt to merge the exits. This helps several passes, such
// as LoopRotation, which do not support loops with multiple exits.
// SimplifyCFG also does this (and this code uses the same utility
// function), however this code is loop-aware, where SimplifyCFG is
// not. That gives it the advantage of being able to hoist
// loop-invariant instructions out of the way to open up more
// opportunities, and the disadvantage of having the responsibility
// to preserve dominator information.
bool UniqueExit = true;
if (!ExitBlocks.empty())
for (unsigned i = 1, e = ExitBlocks.size(); i != e; ++i)
if (ExitBlocks[i] != ExitBlocks[0]) {
UniqueExit = false;
break;
}
if (UniqueExit) {
for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
BasicBlock *ExitingBlock = ExitingBlocks[i];
if (!ExitingBlock->getSinglePredecessor()) continue;
BranchInst *BI = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
if (!BI || !BI->isConditional()) continue;
CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
if (!CI || CI->getParent() != ExitingBlock) continue;
// Attempt to hoist out all instructions except for the
// comparison and the branch.
bool AllInvariant = true;
bool AnyInvariant = false;
for (BasicBlock::iterator I = ExitingBlock->begin(); &*I != BI; ) {
Instruction *Inst = I++;
// Skip debug info intrinsics.
if (isa<DbgInfoIntrinsic>(Inst))
continue;
if (Inst == CI)
continue;
if (!L->makeLoopInvariant(Inst, AnyInvariant,
Preheader ? Preheader->getTerminator()
: nullptr)) {
AllInvariant = false;
break;
}
}
if (AnyInvariant) {
Changed = true;
// The loop disposition of all SCEV expressions that depend on any
// hoisted values have also changed.
if (SE)
SE->forgetLoopDispositions(L);
}
if (!AllInvariant) continue;
// The block has now been cleared of all instructions except for
// a comparison and a conditional branch. SimplifyCFG may be able
// to fold it now.
if (!FoldBranchToCommonDest(BI))
continue;
// Success. The block is now dead, so remove it from the loop,
// update the dominator tree and delete it.
DEBUG(dbgs() << "LoopSimplify: Eliminating exiting block "
<< ExitingBlock->getName() << "\n");
// Notify ScalarEvolution before deleting this block. Currently assume the
// parent loop doesn't change (spliting edges doesn't count). If blocks,
// CFG edges, or other values in the parent loop change, then we need call
// to forgetLoop() for the parent instead.
if (SE)
SE->forgetLoop(L);
assert(pred_begin(ExitingBlock) == pred_end(ExitingBlock));
Changed = true;
LI->removeBlock(ExitingBlock);
DomTreeNode *Node = DT->getNode(ExitingBlock);
const std::vector<DomTreeNodeBase<BasicBlock> *> &Children =
Node->getChildren();
while (!Children.empty()) {
DomTreeNode *Child = Children.front();
DT->changeImmediateDominator(Child, Node->getIDom());
}
DT->eraseNode(ExitingBlock);
BI->getSuccessor(0)->removePredecessor(ExitingBlock);
BI->getSuccessor(1)->removePredecessor(ExitingBlock);
ExitingBlock->eraseFromParent();
}
}
return Changed;
}
/// \brief This method is called when the specified loop has more than one
/// backedge in it.
///
/// If this occurs, revector all of these backedges to target a new basic block
/// and have that block branch to the loop header. This ensures that loops
/// have exactly one backedge.
static BasicBlock *insertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader,
DominatorTree *DT, LoopInfo *LI) {
assert(L->getNumBackEdges() > 1 && "Must have > 1 backedge!");
// Get information about the loop
BasicBlock *Header = L->getHeader();
Function *F = Header->getParent();
// Unique backedge insertion currently depends on having a preheader.
if (!Preheader)
return nullptr;
// The header is not a landing pad; preheader insertion should ensure this.
assert(!Header->isLandingPad() && "Can't insert backedge to landing pad");
// Figure out which basic blocks contain back-edges to the loop header.
std::vector<BasicBlock*> BackedgeBlocks;
for (pred_iterator I = pred_begin(Header), E = pred_end(Header); I != E; ++I){
BasicBlock *P = *I;
// Indirectbr edges cannot be split, so we must fail if we find one.
if (isa<IndirectBrInst>(P->getTerminator()))
return nullptr;
if (P != Preheader) BackedgeBlocks.push_back(P);
}
// Create and insert the new backedge block...
BasicBlock *BEBlock = BasicBlock::Create(Header->getContext(),
Header->getName() + ".backedge", F);
BranchInst *BETerminator = BranchInst::Create(Header, BEBlock);
BETerminator->setDebugLoc(Header->getFirstNonPHI()->getDebugLoc());
DEBUG(dbgs() << "LoopSimplify: Inserting unique backedge block "
<< BEBlock->getName() << "\n");
// Move the new backedge block to right after the last backedge block.
Function::iterator InsertPos = BackedgeBlocks.back(); ++InsertPos;
F->getBasicBlockList().splice(InsertPos, F->getBasicBlockList(), BEBlock);
// Now that the block has been inserted into the function, create PHI nodes in
// the backedge block which correspond to any PHI nodes in the header block.
for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
PHINode *PN = cast<PHINode>(I);
PHINode *NewPN = PHINode::Create(PN->getType(), BackedgeBlocks.size(),
PN->getName()+".be", BETerminator);
// Loop over the PHI node, moving all entries except the one for the
// preheader over to the new PHI node.
unsigned PreheaderIdx = ~0U;
bool HasUniqueIncomingValue = true;
Value *UniqueValue = nullptr;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
BasicBlock *IBB = PN->getIncomingBlock(i);
Value *IV = PN->getIncomingValue(i);
if (IBB == Preheader) {
PreheaderIdx = i;
} else {
NewPN->addIncoming(IV, IBB);
if (HasUniqueIncomingValue) {
if (!UniqueValue)
UniqueValue = IV;
else if (UniqueValue != IV)
HasUniqueIncomingValue = false;
}
}
}
// Delete all of the incoming values from the old PN except the preheader's
assert(PreheaderIdx != ~0U && "PHI has no preheader entry??");
if (PreheaderIdx != 0) {
PN->setIncomingValue(0, PN->getIncomingValue(PreheaderIdx));
PN->setIncomingBlock(0, PN->getIncomingBlock(PreheaderIdx));
}
// Nuke all entries except the zero'th.
for (unsigned i = 0, e = PN->getNumIncomingValues()-1; i != e; ++i)
PN->removeIncomingValue(e-i, false);
// Finally, add the newly constructed PHI node as the entry for the BEBlock.
PN->addIncoming(NewPN, BEBlock);
// As an optimization, if all incoming values in the new PhiNode (which is a
// subset of the incoming values of the old PHI node) have the same value,
// eliminate the PHI Node.
if (HasUniqueIncomingValue) {
NewPN->replaceAllUsesWith(UniqueValue);
BEBlock->getInstList().erase(NewPN);
}
}
// Now that all of the PHI nodes have been inserted and adjusted, modify the
// backedge blocks to just to the BEBlock instead of the header.
for (unsigned i = 0, e = BackedgeBlocks.size(); i != e; ++i) {
TerminatorInst *TI = BackedgeBlocks[i]->getTerminator();
for (unsigned Op = 0, e = TI->getNumSuccessors(); Op != e; ++Op)
if (TI->getSuccessor(Op) == Header)
TI->setSuccessor(Op, BEBlock);
}
//===--- Update all analyses which we must preserve now -----------------===//
// Update Loop Information - we know that this block is now in the current
// loop and all parent loops.
L->addBasicBlockToLoop(BEBlock, *LI);
// Update dominator information
DT->splitBlock(BEBlock);
return BEBlock;
}
/// \brief Analyze a call site for potential inlining.
///
/// Returns true if inlining this call is viable, and false if it is not
/// viable. It computes the cost and adjusts the threshold based on numerous
/// factors and heuristics. If this method returns false but the computed cost
/// is below the computed threshold, then inlining was forcibly disabled by
/// some artifact of the routine.
bool CallAnalyzer::analyzeCall(CallSite CS) {
++NumCallsAnalyzed;
// Track whether the post-inlining function would have more than one basic
// block. A single basic block is often intended for inlining. Balloon the
// threshold by 50% until we pass the single-BB phase.
bool SingleBB = true;
int SingleBBBonus = Threshold / 2;
Threshold += SingleBBBonus;
// Perform some tweaks to the cost and threshold based on the direct
// callsite information.
// We want to more aggressively inline vector-dense kernels, so up the
// threshold, and we'll lower it if the % of vector instructions gets too
// low.
assert(NumInstructions == 0);
assert(NumVectorInstructions == 0);
FiftyPercentVectorBonus = Threshold;
TenPercentVectorBonus = Threshold / 2;
// Give out bonuses per argument, as the instructions setting them up will
// be gone after inlining.
for (unsigned I = 0, E = CS.arg_size(); I != E; ++I) {
if (TD && CS.isByValArgument(I)) {
// We approximate the number of loads and stores needed by dividing the
// size of the byval type by the target's pointer size.
PointerType *PTy = cast<PointerType>(CS.getArgument(I)->getType());
unsigned TypeSize = TD->getTypeSizeInBits(PTy->getElementType());
unsigned PointerSize = TD->getPointerSizeInBits();
// Ceiling division.
unsigned NumStores = (TypeSize + PointerSize - 1) / PointerSize;
// If it generates more than 8 stores it is likely to be expanded as an
// inline memcpy so we take that as an upper bound. Otherwise we assume
// one load and one store per word copied.
// FIXME: The maxStoresPerMemcpy setting from the target should be used
// here instead of a magic number of 8, but it's not available via
// DataLayout.
NumStores = std::min(NumStores, 8U);
Cost -= 2 * NumStores * InlineConstants::InstrCost;
} else {
// For non-byval arguments subtract off one instruction per call
// argument.
Cost -= InlineConstants::InstrCost;
}
}
// If there is only one call of the function, and it has internal linkage,
// the cost of inlining it drops dramatically.
bool OnlyOneCallAndLocalLinkage = F.hasLocalLinkage() && F.hasOneUse() &&
&F == CS.getCalledFunction();
if (OnlyOneCallAndLocalLinkage)
Cost += InlineConstants::LastCallToStaticBonus;
// If the instruction after the call, or if the normal destination of the
// invoke is an unreachable instruction, the function is noreturn. As such,
// there is little point in inlining this unless there is literally zero
// cost.
Instruction *Instr = CS.getInstruction();
if (InvokeInst *II = dyn_cast<InvokeInst>(Instr)) {
if (isa<UnreachableInst>(II->getNormalDest()->begin()))
Threshold = 1;
} else if (isa<UnreachableInst>(++BasicBlock::iterator(Instr)))
Threshold = 1;
// If this function uses the coldcc calling convention, prefer not to inline
// it.
if (F.getCallingConv() == CallingConv::Cold)
Cost += InlineConstants::ColdccPenalty;
// Check if we're done. This can happen due to bonuses and penalties.
if (Cost > Threshold)
return false;
if (F.empty())
return true;
Function *Caller = CS.getInstruction()->getParent()->getParent();
// Check if the caller function is recursive itself.
for (Value::use_iterator U = Caller->use_begin(), E = Caller->use_end();
U != E; ++U) {
CallSite Site(cast<Value>(*U));
if (!Site)
continue;
Instruction *I = Site.getInstruction();
if (I->getParent()->getParent() == Caller) {
IsCallerRecursive = true;
break;
}
}
// Track whether we've seen a return instruction. The first return
// instruction is free, as at least one will usually disappear in inlining.
bool HasReturn = false;
// Populate our simplified values by mapping from function arguments to call
// arguments with known important simplifications.
CallSite::arg_iterator CAI = CS.arg_begin();
for (Function::arg_iterator FAI = F.arg_begin(), FAE = F.arg_end();
FAI != FAE; ++FAI, ++CAI) {
assert(CAI != CS.arg_end());
if (Constant *C = dyn_cast<Constant>(CAI))
SimplifiedValues[FAI] = C;
Value *PtrArg = *CAI;
if (ConstantInt *C = stripAndComputeInBoundsConstantOffsets(PtrArg)) {
ConstantOffsetPtrs[FAI] = std::make_pair(PtrArg, C->getValue());
// We can SROA any pointer arguments derived from alloca instructions.
if (isa<AllocaInst>(PtrArg)) {
SROAArgValues[FAI] = PtrArg;
SROAArgCosts[PtrArg] = 0;
}
}
}
NumConstantArgs = SimplifiedValues.size();
NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
NumAllocaArgs = SROAArgValues.size();
// The worklist of live basic blocks in the callee *after* inlining. We avoid
// adding basic blocks of the callee which can be proven to be dead for this
// particular call site in order to get more accurate cost estimates. This
// requires a somewhat heavyweight iteration pattern: we need to walk the
// basic blocks in a breadth-first order as we insert live successors. To
// accomplish this, prioritizing for small iterations because we exit after
// crossing our threshold, we use a small-size optimized SetVector.
typedef SetVector<BasicBlock *, SmallVector<BasicBlock *, 16>,
SmallPtrSet<BasicBlock *, 16> > BBSetVector;
BBSetVector BBWorklist;
BBWorklist.insert(&F.getEntryBlock());
// Note that we *must not* cache the size, this loop grows the worklist.
for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) {
// Bail out the moment we cross the threshold. This means we'll under-count
// the cost, but only when undercounting doesn't matter.
if (Cost > (Threshold + VectorBonus))
break;
BasicBlock *BB = BBWorklist[Idx];
if (BB->empty())
continue;
// Handle the terminator cost here where we can track returns and other
// function-wide constructs.
TerminatorInst *TI = BB->getTerminator();
// We never want to inline functions that contain an indirectbr. This is
// incorrect because all the blockaddress's (in static global initializers
// for example) would be referring to the original function, and this
// indirect jump would jump from the inlined copy of the function into the
// original function which is extremely undefined behavior.
// FIXME: This logic isn't really right; we can safely inline functions
// with indirectbr's as long as no other function or global references the
// blockaddress of a block within the current function. And as a QOI issue,
// if someone is using a blockaddress without an indirectbr, and that
// reference somehow ends up in another function or global, we probably
// don't want to inline this function.
if (isa<IndirectBrInst>(TI))
return false;
if (!HasReturn && isa<ReturnInst>(TI))
HasReturn = true;
else
Cost += InlineConstants::InstrCost;
// Analyze the cost of this block. If we blow through the threshold, this
// returns false, and we can bail on out.
if (!analyzeBlock(BB)) {
if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca)
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;
break;
}
// Add in the live successors by first checking whether we have terminator
// that may be simplified based on the values simplified by this call.
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
if (BI->isConditional()) {
Value *Cond = BI->getCondition();
if (ConstantInt *SimpleCond
= dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
BBWorklist.insert(BI->getSuccessor(SimpleCond->isZero() ? 1 : 0));
continue;
}
}
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
Value *Cond = SI->getCondition();
if (ConstantInt *SimpleCond
= dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
BBWorklist.insert(SI->findCaseValue(SimpleCond).getCaseSuccessor());
continue;
}
}
// If we're unable to select a particular successor, just count all of
// them.
for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize;
++TIdx)
BBWorklist.insert(TI->getSuccessor(TIdx));
// If we had any successors at this point, than post-inlining is likely to
// have them as well. Note that we assume any basic blocks which existed
// due to branches or switches which folded above will also fold after
// inlining.
if (SingleBB && TI->getNumSuccessors() > 1) {
// Take off the bonus we applied to the threshold.
Threshold -= SingleBBBonus;
SingleBB = false;
}
}
// If this is a noduplicate call, we can still inline as long as
// inlining this would cause the removal of the caller (so the instruction
// is not actually duplicated, just moved).
if (!OnlyOneCallAndLocalLinkage && ContainsNoDuplicateCall)
return false;
Threshold += VectorBonus;
return Cost < Threshold;
}
bool GCOVProfiler::emitProfileArcs() {
NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
if (!CU_Nodes) return false;
bool Result = false;
bool InsertIndCounterIncrCode = false;
for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
DICompileUnit CU(CU_Nodes->getOperand(i));
DIArray SPs = CU.getSubprograms();
SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> CountersBySP;
for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
DISubprogram SP(SPs.getElement(i));
if (!SP.Verify()) continue;
Function *F = SP.getFunction();
if (!F) continue;
if (!Result) Result = true;
unsigned Edges = 0;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
TerminatorInst *TI = BB->getTerminator();
if (isa<ReturnInst>(TI))
++Edges;
else
Edges += TI->getNumSuccessors();
}
ArrayType *CounterTy =
ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
GlobalVariable *Counters =
new GlobalVariable(*M, CounterTy, false,
GlobalValue::InternalLinkage,
Constant::getNullValue(CounterTy),
"__llvm_gcov_ctr");
CountersBySP.push_back(std::make_pair(Counters, (MDNode*)SP));
UniqueVector<BasicBlock *> ComplexEdgePreds;
UniqueVector<BasicBlock *> ComplexEdgeSuccs;
unsigned Edge = 0;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
TerminatorInst *TI = BB->getTerminator();
int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
if (Successors) {
IRBuilder<> Builder(TI);
if (Successors == 1) {
Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
Edge);
Value *Count = Builder.CreateLoad(Counter);
Count = Builder.CreateAdd(Count,
ConstantInt::get(Type::getInt64Ty(*Ctx),1));
Builder.CreateStore(Count, Counter);
} else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
Value *Sel = Builder.CreateSelect(
BI->getCondition(),
ConstantInt::get(Type::getInt64Ty(*Ctx), Edge),
ConstantInt::get(Type::getInt64Ty(*Ctx), Edge + 1));
SmallVector<Value *, 2> Idx;
Idx.push_back(Constant::getNullValue(Type::getInt64Ty(*Ctx)));
Idx.push_back(Sel);
Value *Counter = Builder.CreateInBoundsGEP(Counters, Idx);
Value *Count = Builder.CreateLoad(Counter);
Count = Builder.CreateAdd(Count,
ConstantInt::get(Type::getInt64Ty(*Ctx),1));
Builder.CreateStore(Count, Counter);
} else {
ComplexEdgePreds.insert(BB);
for (int i = 0; i != Successors; ++i)
ComplexEdgeSuccs.insert(TI->getSuccessor(i));
}
Edge += Successors;
}
}
if (!ComplexEdgePreds.empty()) {
GlobalVariable *EdgeTable =
buildEdgeLookupTable(F, Counters,
ComplexEdgePreds, ComplexEdgeSuccs);
GlobalVariable *EdgeState = getEdgeStateValue();
Type *Int32Ty = Type::getInt32Ty(*Ctx);
for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
IRBuilder<> Builder(ComplexEdgePreds[i+1]->getTerminator());
Builder.CreateStore(ConstantInt::get(Int32Ty, i), EdgeState);
}
for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
// call runtime to perform increment
BasicBlock::iterator InsertPt =
ComplexEdgeSuccs[i+1]->getFirstInsertionPt();
IRBuilder<> Builder(InsertPt);
Value *CounterPtrArray =
Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
i * ComplexEdgePreds.size());
// Build code to increment the counter.
InsertIndCounterIncrCode = true;
Builder.CreateCall2(getIncrementIndirectCounterFunc(),
EdgeState, CounterPtrArray);
}
}
}
insertCounterWriteout(CountersBySP);
insertFlush(CountersBySP);
}
if (InsertIndCounterIncrCode)
insertIndirectCounterIncrement();
return Result;
}
bool ReduceCrashingBlocks::TestBlocks(std::vector<const BasicBlock*> &BBs) {
// Clone the program to try hacking it apart...
ValueToValueMapTy VMap;
Module *M = CloneModule(BD.getProgram(), VMap);
// Convert list to set for fast lookup...
SmallPtrSet<BasicBlock*, 8> Blocks;
for (unsigned i = 0, e = BBs.size(); i != e; ++i)
Blocks.insert(cast<BasicBlock>(VMap[BBs[i]]));
outs() << "Checking for crash with only these blocks:";
unsigned NumPrint = Blocks.size();
if (NumPrint > 10) NumPrint = 10;
for (unsigned i = 0, e = NumPrint; i != e; ++i)
outs() << " " << BBs[i]->getName();
if (NumPrint < Blocks.size())
outs() << "... <" << Blocks.size() << " total>";
outs() << ": ";
// Loop over and delete any hack up any blocks that are not listed...
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
if (!Blocks.count(&*BB) && BB->getTerminator()->getNumSuccessors()) {
// Loop over all of the successors of this block, deleting any PHI nodes
// that might include it.
for (succ_iterator SI = succ_begin(&*BB), E = succ_end(&*BB); SI != E;
++SI)
(*SI)->removePredecessor(&*BB);
TerminatorInst *BBTerm = BB->getTerminator();
if (!BB->getTerminator()->getType()->isVoidTy())
BBTerm->replaceAllUsesWith(Constant::getNullValue(BBTerm->getType()));
// Replace the old terminator instruction.
BB->getInstList().pop_back();
new UnreachableInst(BB->getContext(), &*BB);
}
// The CFG Simplifier pass may delete one of the basic blocks we are
// interested in. If it does we need to take the block out of the list. Make
// a "persistent mapping" by turning basic blocks into <function, name> pairs.
// This won't work well if blocks are unnamed, but that is just the risk we
// have to take.
std::vector<std::pair<std::string, std::string> > BlockInfo;
for (BasicBlock *BB : Blocks)
BlockInfo.emplace_back(BB->getParent()->getName(), BB->getName());
// Now run the CFG simplify pass on the function...
std::vector<std::string> Passes;
Passes.push_back("simplifycfg");
Passes.push_back("verify");
std::unique_ptr<Module> New = BD.runPassesOn(M, Passes);
delete M;
if (!New) {
errs() << "simplifycfg failed!\n";
exit(1);
}
M = New.release();
// Try running on the hacked up program...
if (TestFn(BD, M)) {
BD.setNewProgram(M); // It crashed, keep the trimmed version...
// Make sure to use basic block pointers that point into the now-current
// module, and that they don't include any deleted blocks.
BBs.clear();
const ValueSymbolTable &GST = M->getValueSymbolTable();
for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {
Function *F = cast<Function>(GST.lookup(BlockInfo[i].first));
ValueSymbolTable &ST = F->getValueSymbolTable();
Value* V = ST.lookup(BlockInfo[i].second);
if (V && V->getType() == Type::getLabelTy(V->getContext()))
BBs.push_back(cast<BasicBlock>(V));
}
return true;
}
delete M; // It didn't crash, try something else.
return false;
}
bool ScopDetection::isValidCFG(BasicBlock &BB,
DetectionContext &Context) const {
Region &RefRegion = Context.CurRegion;
TerminatorInst *TI = BB.getTerminator();
// Return instructions are only valid if the region is the top level region.
if (isa<ReturnInst>(TI) && !RefRegion.getExit() && TI->getNumOperands() == 0)
return true;
BranchInst *Br = dyn_cast<BranchInst>(TI);
if (!Br)
return invalid<ReportNonBranchTerminator>(Context, /*Assert=*/true, &BB);
if (Br->isUnconditional())
return true;
Value *Condition = Br->getCondition();
// UndefValue is not allowed as condition.
if (isa<UndefValue>(Condition))
return invalid<ReportUndefCond>(Context, /*Assert=*/true, &BB);
// Only Constant and ICmpInst are allowed as condition.
if (!(isa<Constant>(Condition) || isa<ICmpInst>(Condition)))
return invalid<ReportInvalidCond>(Context, /*Assert=*/true, &BB);
// Allow perfectly nested conditions.
assert(Br->getNumSuccessors() == 2 && "Unexpected number of successors");
if (ICmpInst *ICmp = dyn_cast<ICmpInst>(Condition)) {
// Unsigned comparisons are not allowed. They trigger overflow problems
// in the code generation.
//
// TODO: This is not sufficient and just hides bugs. However it does pretty
// well.
if (ICmp->isUnsigned())
return false;
// Are both operands of the ICmp affine?
if (isa<UndefValue>(ICmp->getOperand(0)) ||
isa<UndefValue>(ICmp->getOperand(1)))
return invalid<ReportUndefOperand>(Context, /*Assert=*/true, &BB);
Loop *L = LI->getLoopFor(ICmp->getParent());
const SCEV *LHS = SE->getSCEVAtScope(ICmp->getOperand(0), L);
const SCEV *RHS = SE->getSCEVAtScope(ICmp->getOperand(1), L);
if (!isAffineExpr(&Context.CurRegion, LHS, *SE) ||
!isAffineExpr(&Context.CurRegion, RHS, *SE))
return invalid<ReportNonAffBranch>(Context, /*Assert=*/true, &BB, LHS,
RHS);
}
// Allow loop exit conditions.
Loop *L = LI->getLoopFor(&BB);
if (L && L->getExitingBlock() == &BB)
return true;
// Allow perfectly nested conditions.
Region *R = RI->getRegionFor(&BB);
if (R->getEntry() != &BB)
return invalid<ReportCondition>(Context, /*Assert=*/true, &BB);
return true;
}
