// GetSJSwitch - Return the switch statement that controls which handler
// (if any) gets called and the value returned to that handler.
LowerSetJmp::SwitchValuePair LowerSetJmp::GetSJSwitch(Function* Func,
BasicBlock* Rethrow)
{
if (SwitchValMap[Func].first) return SwitchValMap[Func];
BasicBlock* LongJmpPre = BasicBlock::Create("LongJmpBlkPre", Func);
BasicBlock::InstListType& LongJmpPreIL = LongJmpPre->getInstList();
// Keep track of the preliminary basic block for some of the other
// transformations.
PrelimBBMap[Func] = LongJmpPre;
// Grab the exception.
CallInst* Cond = CallInst::Create(IsLJException, "IsLJExcept");
LongJmpPreIL.push_back(Cond);
// The "decision basic block" gets the number associated with the
// setjmp call returning to switch on and the value returned by
// longjmp.
BasicBlock* DecisionBB = BasicBlock::Create("LJDecisionBB", Func);
BasicBlock::InstListType& DecisionBBIL = DecisionBB->getInstList();
BranchInst::Create(DecisionBB, Rethrow, Cond, LongJmpPre);
// Fill in the "decision" basic block.
CallInst* LJVal = CallInst::Create(GetLJValue, "LJVal");
DecisionBBIL.push_back(LJVal);
CallInst* SJNum = CallInst::Create(TryCatchLJ, GetSetJmpMap(Func), "SJNum");
DecisionBBIL.push_back(SJNum);
SwitchInst* SI = SwitchInst::Create(SJNum, Rethrow, 0, DecisionBB);
return SwitchValMap[Func] = SwitchValuePair(SI, LJVal);
}
void Graph::printGraphFromMod() {
int InstCount = 0;
for (iplist<Function>::iterator It = M->getFunctionList().begin(); It != M->getFunctionList().end(); ++It) {
Function * Fn = It;
for (iplist<BasicBlock>::iterator I = Fn->getBasicBlockList().begin(); I != Fn->getBasicBlockList().end(); ++I) {
BasicBlock * Bb = I;
DEBUG (errs() << Bb << '\n');
BasicBlock * PSBB = Bb->getSinglePredecessor();
if (PSBB != NULL) {
DEBUG (errs() << "Single Predecessor: \n" << PSBB << "\n_______________________" << '\n');
}
else if ((PSBB = (Bb->getUniquePredecessor())) != NULL)
DEBUG (errs() << "Unique Predecessor: " << PSBB << '\n');
else {
DEBUG (errs() << "No Predecessor\n_______________________\n");
}
// print the instructions
for (iplist<Instruction>::iterator X = Bb->getInstList().begin(); X != Bb->getInstList().end(); ++X) {
InstCount++;
DEBUG (errs() << (*X).getOpcodeName() << '\n');
}
DEBUG (errs() << "\n\n\n");
}
}
DEBUG (errs() << "Instruction Count = " << InstCount << "\n");
}
/// FoldBlockIntoPredecessor - Folds a basic block into its predecessor if it
/// only has one predecessor, and that predecessor only has one successor.
/// The LoopInfo Analysis that is passed will be kept consistent. If folding is
/// successful references to the containing loop must be removed from
/// ScalarEvolution by calling ScalarEvolution::forgetLoop because SE may have
/// references to the eliminated BB. The argument ForgottenLoops contains a set
/// of loops that have already been forgotten to prevent redundant, expensive
/// calls to ScalarEvolution::forgetLoop. Returns the new combined block.
static BasicBlock *
FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI, LPPassManager *LPM,
SmallPtrSetImpl<Loop *> &ForgottenLoops) {
// Merge basic blocks into their predecessor if there is only one distinct
// pred, and if there is only one distinct successor of the predecessor, and
// if there are no PHI nodes.
BasicBlock *OnlyPred = BB->getSinglePredecessor();
if (!OnlyPred) return nullptr;
if (OnlyPred->getTerminator()->getNumSuccessors() != 1)
return nullptr;
DEBUG(dbgs() << "Merging: " << *BB << "into: " << *OnlyPred);
// Resolve any PHI nodes at the start of the block. They are all
// guaranteed to have exactly one entry if they exist, unless there are
// multiple duplicate (but guaranteed to be equal) entries for the
// incoming edges. This occurs when there are multiple edges from
// OnlyPred to OnlySucc.
FoldSingleEntryPHINodes(BB);
// Delete the unconditional branch from the predecessor...
OnlyPred->getInstList().pop_back();
// Make all PHI nodes that referred to BB now refer to Pred as their
// source...
BB->replaceAllUsesWith(OnlyPred);
// Move all definitions in the successor to the predecessor...
OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
// OldName will be valid until erased.
StringRef OldName = BB->getName();
// Erase basic block from the function...
// ScalarEvolution holds references to loop exit blocks.
if (LPM) {
if (auto *SEWP =
LPM->getAnalysisIfAvailable<ScalarEvolutionWrapperPass>()) {
if (Loop *L = LI->getLoopFor(BB)) {
if (ForgottenLoops.insert(L).second)
SEWP->getSE().forgetLoop(L);
}
}
}
LI->removeBlock(BB);
// Inherit predecessor's name if it exists...
if (!OldName.empty() && !OnlyPred->hasName())
OnlyPred->setName(OldName);
BB->eraseFromParent();
return OnlyPred;
}
/// Folds a basic block into its predecessor if it only has one predecessor, and
/// that predecessor only has one successor.
/// The LoopInfo Analysis that is passed will be kept consistent.
static BasicBlock *
foldBlockIntoPredecessor(BasicBlock *BB, LoopInfo *LI, ScalarEvolution *SE,
DominatorTree *DT) {
// Merge basic blocks into their predecessor if there is only one distinct
// pred, and if there is only one distinct successor of the predecessor, and
// if there are no PHI nodes.
BasicBlock *OnlyPred = BB->getSinglePredecessor();
if (!OnlyPred) return nullptr;
if (OnlyPred->getTerminator()->getNumSuccessors() != 1)
return nullptr;
LLVM_DEBUG(dbgs() << "Merging: " << *BB << "into: " << *OnlyPred);
// Resolve any PHI nodes at the start of the block. They are all
// guaranteed to have exactly one entry if they exist, unless there are
// multiple duplicate (but guaranteed to be equal) entries for the
// incoming edges. This occurs when there are multiple edges from
// OnlyPred to OnlySucc.
FoldSingleEntryPHINodes(BB);
// Delete the unconditional branch from the predecessor...
OnlyPred->getInstList().pop_back();
// Make all PHI nodes that referred to BB now refer to Pred as their
// source...
BB->replaceAllUsesWith(OnlyPred);
// Move all definitions in the successor to the predecessor...
OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
// OldName will be valid until erased.
StringRef OldName = BB->getName();
// Erase the old block and update dominator info.
if (DT)
if (DomTreeNode *DTN = DT->getNode(BB)) {
DomTreeNode *PredDTN = DT->getNode(OnlyPred);
SmallVector<DomTreeNode *, 8> Children(DTN->begin(), DTN->end());
for (auto *DI : Children)
DT->changeImmediateDominator(DI, PredDTN);
DT->eraseNode(BB);
}
LI->removeBlock(BB);
// Inherit predecessor's name if it exists...
if (!OldName.empty() && !OnlyPred->hasName())
OnlyPred->setName(OldName);
BB->eraseFromParent();
return OnlyPred;
}
void Graph::printInstrTotal() {
int InstCount = 0;
for (iplist<Function>::iterator It = M->getFunctionList().begin(); It != M->getFunctionList().end(); ++It) {
Function * Fn = It;
for (iplist<BasicBlock>::iterator I = Fn->getBasicBlockList().begin(); I != Fn->getBasicBlockList().end(); ++I) {
BasicBlock * Bb = I;
for (iplist<Instruction>::iterator X = Bb->getInstList().begin(); X != Bb->getInstList().end(); ++X) {
InstCount++;
}
}
}
DEBUG (errs() << "Instruction Count = " << InstCount << "\n");
}
// processSwitchInst - Replace the specified switch instruction with a sequence
// of chained if-then insts in a balanced binary search.
//
void LowerSwitch::processSwitchInst(SwitchInst *SI) {
BasicBlock *CurBlock = SI->getParent();
BasicBlock *OrigBlock = CurBlock;
Function *F = CurBlock->getParent();
Value *Val = SI->getOperand(0); // The value we are switching on...
BasicBlock* Default = SI->getDefaultDest();
// If there is only the default destination, don't bother with the code below.
if (SI->getNumOperands() == 2) {
BranchInst::Create(SI->getDefaultDest(), CurBlock);
CurBlock->getInstList().erase(SI);
return;
}
// Create a new, empty default block so that the new hierarchy of
// if-then statements go to this and the PHI nodes are happy.
BasicBlock* NewDefault = BasicBlock::Create(SI->getContext(), "NewDefault");
F->getBasicBlockList().insert(Default, NewDefault);
BranchInst::Create(Default, NewDefault);
// If there is an entry in any PHI nodes for the default edge, make sure
// to update them as well.
for (BasicBlock::iterator I = Default->begin(); isa<PHINode>(I); ++I) {
PHINode *PN = cast<PHINode>(I);
int BlockIdx = PN->getBasicBlockIndex(OrigBlock);
assert(BlockIdx != -1 && "Switch didn't go to this successor??");
PN->setIncomingBlock((unsigned)BlockIdx, NewDefault);
}
// Prepare cases vector.
CaseVector Cases;
unsigned numCmps = Clusterify(Cases, SI);
DEBUG(dbgs() << "Clusterify finished. Total clusters: " << Cases.size()
<< ". Total compares: " << numCmps << "\n");
DEBUG(dbgs() << "Cases: " << Cases << "\n");
(void)numCmps;
BasicBlock* SwitchBlock = switchConvert(Cases.begin(), Cases.end(), Val,
OrigBlock, NewDefault);
// Branch to our shiny new if-then stuff...
BranchInst::Create(SwitchBlock, OrigBlock);
// We are now done with the switch instruction, delete it.
CurBlock->getInstList().erase(SI);
}
/// ChangeToUnreachable - Insert an unreachable instruction before the specified
/// instruction, making it and the rest of the code in the block dead.
static void ChangeToUnreachable(Instruction *I, bool UseLLVMTrap) {
BasicBlock *BB = I->getParent();
// Loop over all of the successors, removing BB's entry from any PHI
// nodes.
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
(*SI)->removePredecessor(BB);
// Insert a call to llvm.trap right before this. This turns the undefined
// behavior into a hard fail instead of falling through into random code.
if (UseLLVMTrap) {
Function *TrapFn =
Intrinsic::getDeclaration(BB->getParent()->getParent(), Intrinsic::trap);
CallInst *CallTrap = CallInst::Create(TrapFn, "", I);
CallTrap->setDebugLoc(I->getDebugLoc());
}
new UnreachableInst(I->getContext(), I);
// All instructions after this are dead.
BasicBlock::iterator BBI = I, BBE = BB->end();
while (BBI != BBE) {
if (!BBI->use_empty())
BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
BB->getInstList().erase(BBI++);
}
}
/// See comments in Cloning.h.
BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB,
ValueToValueMapTy &VMap,
const Twine &NameSuffix, Function *F,
ClonedCodeInfo *CodeInfo) {
BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
// Loop over all instructions, and copy them over.
for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
II != IE; ++II) {
Instruction *NewInst = II->clone();
if (II->hasName())
NewInst->setName(II->getName()+NameSuffix);
NewBB->getInstList().push_back(NewInst);
VMap[&*II] = NewInst; // Add instruction map to value.
hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (isa<ConstantInt>(AI->getArraySize()))
hasStaticAllocas = true;
else
hasDynamicAllocas = true;
}
}
if (CodeInfo) {
CodeInfo->ContainsCalls |= hasCalls;
CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
BB != &BB->getParent()->getEntryBlock();
}
return NewBB;
}
bool UnreachableBlockElim::runOnFunction(Function &F) {
SmallPtrSet<BasicBlock*, 8> Reachable;
// Mark all reachable blocks.
for (df_ext_iterator<Function*, SmallPtrSet<BasicBlock*, 8> > I =
df_ext_begin(&F, Reachable), E = df_ext_end(&F, Reachable); I != E; ++I)
/* Mark all reachable blocks */;
// Loop over all dead blocks, remembering them and deleting all instructions
// in them.
std::vector<BasicBlock*> DeadBlocks;
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
if (!Reachable.count(I)) {
BasicBlock *BB = I;
DeadBlocks.push_back(BB);
while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) {
PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
BB->getInstList().pop_front();
}
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
(*SI)->removePredecessor(BB);
BB->dropAllReferences();
}
// Actually remove the blocks now.
ProfileInfo *PI = getAnalysisIfAvailable<ProfileInfo>();
for (unsigned i = 0, e = DeadBlocks.size(); i != e; ++i) {
if (PI) PI->removeBlock(DeadBlocks[i]);
DeadBlocks[i]->eraseFromParent();
}
return DeadBlocks.size();
}
static bool eliminateUnreachableBlock(Function &F) {
df_iterator_default_set<BasicBlock*> Reachable;
// Mark all reachable blocks.
for (BasicBlock *BB : depth_first_ext(&F, Reachable))
(void)BB/* Mark all reachable blocks */;
// Loop over all dead blocks, remembering them and deleting all instructions
// in them.
std::vector<BasicBlock*> DeadBlocks;
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
if (!Reachable.count(&*I)) {
BasicBlock *BB = &*I;
DeadBlocks.push_back(BB);
while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) {
PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
BB->getInstList().pop_front();
}
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
(*SI)->removePredecessor(BB);
BB->dropAllReferences();
}
// Actually remove the blocks now.
for (unsigned i = 0, e = DeadBlocks.size(); i != e; ++i) {
DeadBlocks[i]->eraseFromParent();
}
return !DeadBlocks.empty();
}
// visitInvokeInst - Converting the "invoke" instruction is fairly
// straight-forward. The old exception part is replaced by a query asking
// if this is a longjmp exception. If it is, then it goes to the longjmp
// exception blocks. Otherwise, control is passed the old exception.
void LowerSetJmp::visitInvokeInst(InvokeInst& II)
{
if (II.getCalledFunction())
if (!IsTransformableFunction(II.getCalledFunction()->getName()) ||
II.getCalledFunction()->isIntrinsic()) return;
BasicBlock* BB = II.getParent();
// If not reachable from a setjmp call, don't transform.
if (!DFSBlocks.count(BB)) return;
BasicBlock* ExceptBB = II.getUnwindDest();
Function* Func = BB->getParent();
BasicBlock* NewExceptBB = BasicBlock::Create("InvokeExcept", Func);
BasicBlock::InstListType& InstList = NewExceptBB->getInstList();
// If this is a longjmp exception, then branch to the preliminary BB of
// the longjmp exception handling. Otherwise, go to the old exception.
CallInst* IsLJExcept = CallInst::Create(IsLJException, "IsLJExcept");
InstList.push_back(IsLJExcept);
BranchInst::Create(PrelimBBMap[Func], ExceptBB, IsLJExcept, NewExceptBB);
II.setUnwindDest(NewExceptBB);
++InvokesTransformed;
}
/// Fold the loop tail into the loop exit by speculating the loop tail
/// instructions. Typically, this is a single post-increment. In the case of a
/// simple 2-block loop, hoisting the increment can be much better than
/// duplicating the entire loop header. In the case of loops with early exits,
/// rotation will not work anyway, but simplifyLoopLatch will put the loop in
/// canonical form so downstream passes can handle it.
///
/// I don't believe this invalidates SCEV.
bool LoopRotate::simplifyLoopLatch(Loop *L) {
BasicBlock *Latch = L->getLoopLatch();
if (!Latch || Latch->hasAddressTaken())
return false;
BranchInst *Jmp = dyn_cast<BranchInst>(Latch->getTerminator());
if (!Jmp || !Jmp->isUnconditional())
return false;
BasicBlock *LastExit = Latch->getSinglePredecessor();
if (!LastExit || !L->isLoopExiting(LastExit))
return false;
BranchInst *BI = dyn_cast<BranchInst>(LastExit->getTerminator());
if (!BI)
return false;
if (!shouldSpeculateInstrs(Latch->begin(), Jmp))
return false;
DEBUG(dbgs() << "Folding loop latch " << Latch->getName() << " into "
<< LastExit->getName() << "\n");
// Hoist the instructions from Latch into LastExit.
LastExit->getInstList().splice(BI, Latch->getInstList(), Latch->begin(), Jmp);
unsigned FallThruPath = BI->getSuccessor(0) == Latch ? 0 : 1;
BasicBlock *Header = Jmp->getSuccessor(0);
assert(Header == L->getHeader() && "expected a backward branch");
// Remove Latch from the CFG so that LastExit becomes the new Latch.
BI->setSuccessor(FallThruPath, Header);
Latch->replaceSuccessorsPhiUsesWith(LastExit);
Jmp->eraseFromParent();
// Nuke the Latch block.
assert(Latch->empty() && "unable to evacuate Latch");
LI->removeBlock(Latch);
if (DominatorTreeWrapperPass *DTWP =
getAnalysisIfAvailable<DominatorTreeWrapperPass>())
DTWP->getDomTree().eraseNode(Latch);
Latch->eraseFromParent();
return true;
}
Instruction::Instruction(Type *ty, unsigned it, Use *Ops, unsigned NumOps,
Instruction *InsertBefore)
: User(ty, Value::InstructionVal + it, Ops, NumOps), Parent(nullptr) {
// If requested, insert this instruction into a basic block...
if (InsertBefore) {
BasicBlock *BB = InsertBefore->getParent();
assert(BB && "Instruction to insert before is not in a basic block!");
BB->getInstList().insert(InsertBefore->getIterator(), this);
}
}
/// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into
/// an invoke, we have to turn all of the calls that can throw into
/// invokes. This function analyze BB to see if there are any calls, and if so,
/// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI
/// nodes in that block with the values specified in InvokeDestPHIValues.
///
/// Returns true to indicate that the next block should be skipped.
static bool HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
InvokeInliningInfo &Invoke) {
LandingPadInst *LPI = Invoke.getLandingPadInst();
for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
Instruction *I = BBI++;
if (LandingPadInst *L = dyn_cast<LandingPadInst>(I)) {
unsigned NumClauses = LPI->getNumClauses();
L->reserveClauses(NumClauses);
for (unsigned i = 0; i != NumClauses; ++i)
L->addClause(LPI->getClause(i));
}
// We only need to check for function calls: inlined invoke
// instructions require no special handling.
CallInst *CI = dyn_cast<CallInst>(I);
// If this call cannot unwind, don't convert it to an invoke.
// Inline asm calls cannot throw.
if (!CI || CI->doesNotThrow() || isa<InlineAsm>(CI->getCalledValue()))
continue;
// Convert this function call into an invoke instruction. First, split the
// basic block.
BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
// Delete the unconditional branch inserted by splitBasicBlock
BB->getInstList().pop_back();
// Create the new invoke instruction.
ImmutableCallSite CS(CI);
SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end());
InvokeInst *II = InvokeInst::Create(CI->getCalledValue(), Split,
Invoke.getOuterResumeDest(),
InvokeArgs, CI->getName(), BB);
II->setCallingConv(CI->getCallingConv());
II->setAttributes(CI->getAttributes());
// Make sure that anything using the call now uses the invoke! This also
// updates the CallGraph if present, because it uses a WeakVH.
CI->replaceAllUsesWith(II);
// Delete the original call
Split->getInstList().pop_front();
// Update any PHI nodes in the exceptional block to indicate that there is
// now a new entry in them.
Invoke.addIncomingPHIValuesFor(BB);
return false;
}
return false;
}
/// FoldBlockIntoPredecessor - Folds a basic block into its predecessor if it
/// only has one predecessor, and that predecessor only has one successor.
/// The LoopInfo Analysis that is passed will be kept consistent.
/// Returns the new combined block.
static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) {
// Merge basic blocks into their predecessor if there is only one distinct
// pred, and if there is only one distinct successor of the predecessor, and
// if there are no PHI nodes.
BasicBlock *OnlyPred = BB->getSinglePredecessor();
if (!OnlyPred) return 0;
if (OnlyPred->getTerminator()->getNumSuccessors() != 1)
return 0;
DOUT << "Merging: " << *BB << "into: " << *OnlyPred;
// Resolve any PHI nodes at the start of the block. They are all
// guaranteed to have exactly one entry if they exist, unless there are
// multiple duplicate (but guaranteed to be equal) entries for the
// incoming edges. This occurs when there are multiple edges from
// OnlyPred to OnlySucc.
FoldSingleEntryPHINodes(BB);
// Delete the unconditional branch from the predecessor...
OnlyPred->getInstList().pop_back();
// Move all definitions in the successor to the predecessor...
OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
// Make all PHI nodes that referred to BB now refer to Pred as their
// source...
BB->replaceAllUsesWith(OnlyPred);
std::string OldName = BB->getName();
// Erase basic block from the function...
LI->removeBlock(BB);
BB->eraseFromParent();
// Inherit predecessor's name if it exists...
if (!OldName.empty() && !OnlyPred->hasName())
OnlyPred->setName(OldName);
return OnlyPred;
}
int main() {
LLVMContext Context;
// Create the "module" or "program" or "translation unit" to hold the
// function
Module *M = new Module("test", Context);
// Create the main function: first create the type 'int ()'
FunctionType *FT =
FunctionType::get(Type::getInt32Ty(Context), /*not vararg*/false);
// By passing a module as the last parameter to the Function constructor,
// it automatically gets appended to the Module.
Function *F = Function::Create(FT, Function::ExternalLinkage, "main", M);
// Add a basic block to the function... again, it automatically inserts
// because of the last argument.
BasicBlock *BB = BasicBlock::Create(Context, "EntryBlock", F);
// Get pointers to the constant integers...
Value *Two = ConstantInt::get(Type::getInt32Ty(Context), 2);
Value *Three = ConstantInt::get(Type::getInt32Ty(Context), 3);
// Create the add instruction... does not insert...
Instruction *Add = BinaryOperator::Create(Instruction::Add, Two, Three,
"addresult");
// explicitly insert it into the basic block...
BB->getInstList().push_back(Add);
// Create the return instruction and add it to the basic block
BB->getInstList().push_back(ReturnInst::Create(Context, Add));
// Output the bitcode file to stdout
WriteBitcodeToFile(M, outs());
// Delete the module and all of its contents.
delete M;
return 0;
}
/// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into
/// an invoke, we have to turn all of the calls that can throw into
/// invokes. This function analyze BB to see if there are any calls, and if so,
/// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI
/// nodes in that block with the values specified in InvokeDestPHIValues.
///
static void HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
BasicBlock *InvokeDest,
const SmallVectorImpl<Value*> &InvokeDestPHIValues) {
for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
Instruction *I = BBI++;
// We only need to check for function calls: inlined invoke
// instructions require no special handling.
CallInst *CI = dyn_cast<CallInst>(I);
if (CI == 0) continue;
// If this call cannot unwind, don't convert it to an invoke.
if (CI->doesNotThrow())
continue;
// Convert this function call into an invoke instruction.
// First, split the basic block.
BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
// Next, create the new invoke instruction, inserting it at the end
// of the old basic block.
ImmutableCallSite CS(CI);
SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end());
InvokeInst *II =
InvokeInst::Create(CI->getCalledValue(), Split, InvokeDest,
InvokeArgs.begin(), InvokeArgs.end(),
CI->getName(), BB->getTerminator());
II->setCallingConv(CI->getCallingConv());
II->setAttributes(CI->getAttributes());
// Make sure that anything using the call now uses the invoke! This also
// updates the CallGraph if present, because it uses a WeakVH.
CI->replaceAllUsesWith(II);
// Delete the unconditional branch inserted by splitBasicBlock
BB->getInstList().pop_back();
Split->getInstList().pop_front(); // Delete the original call
// Update any PHI nodes in the exceptional block to indicate that
// there is now a new entry in them.
unsigned i = 0;
for (BasicBlock::iterator I = InvokeDest->begin();
isa<PHINode>(I); ++I, ++i)
cast<PHINode>(I)->addIncoming(InvokeDestPHIValues[i], BB);
// This basic block is now complete, the caller will continue scanning the
// next one.
return;
}
}
void CondProp::SimplifyBlock(BasicBlock *BB) {
if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) {
// If this is a conditional branch based on a phi node that is defined in
// this block, see if we can simplify predecessors of this block.
if (BI->isConditional() && isa<PHINode>(BI->getCondition()) &&
cast<PHINode>(BI->getCondition())->getParent() == BB)
SimplifyPredecessors(BI);
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
if (isa<PHINode>(SI->getCondition()) &&
cast<PHINode>(SI->getCondition())->getParent() == BB)
SimplifyPredecessors(SI);
}
// If possible, simplify the terminator of this block.
if (ConstantFoldTerminator(BB))
MadeChange = true;
// If this block ends with an unconditional branch and the only successor has
// only this block as a predecessor, merge the two blocks together.
if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator()))
if (BI->isUnconditional() && BI->getSuccessor(0)->getSinglePredecessor() &&
BB != BI->getSuccessor(0)) {
BasicBlock *Succ = BI->getSuccessor(0);
// If Succ has any PHI nodes, they are all single-entry PHI's.
while (PHINode *PN = dyn_cast<PHINode>(Succ->begin())) {
assert(PN->getNumIncomingValues() == 1 &&
"PHI doesn't match parent block");
PN->replaceAllUsesWith(PN->getIncomingValue(0));
PN->eraseFromParent();
}
// Remove BI.
BI->eraseFromParent();
// Move over all of the instructions.
BB->getInstList().splice(BB->end(), Succ->getInstList());
// Any phi nodes that had entries for Succ now have entries from BB.
Succ->replaceAllUsesWith(BB);
// Succ is now dead, but we cannot delete it without potentially
// invalidating iterators elsewhere. Just insert an unreachable
// instruction in it.
new UnreachableInst(BB->getContext(), Succ);
MadeChange = true;
}
}
// processSwitchInst - Replace the specified switch instruction with a sequence
// of chained if-then instructions.
//
void LowerSwitchPass::processSwitchInst(SwitchInst *SI) {
BasicBlock *origBlock = SI->getParent();
BasicBlock *defaultBlock = SI->getDefaultDest();
Function *F = origBlock->getParent();
Value *switchValue = SI->getCondition();
// Create a new, empty default block so that the new hierarchy of
// if-then statements go to this and the PHI nodes are happy.
BasicBlock* newDefault = BasicBlock::Create(getGlobalContext(), "newDefault");
#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 8)
F->getBasicBlockList().insert(defaultBlock->getIterator(), newDefault);
#else
F->getBasicBlockList().insert(defaultBlock, newDefault);
#endif
BranchInst::Create(defaultBlock, newDefault);
// If there is an entry in any PHI nodes for the default edge, make sure
// to update them as well.
for (BasicBlock::iterator I = defaultBlock->begin(); isa<PHINode>(I); ++I) {
PHINode *PN = cast<PHINode>(I);
int BlockIdx = PN->getBasicBlockIndex(origBlock);
assert(BlockIdx != -1 && "Switch didn't go to this successor??");
PN->setIncomingBlock((unsigned)BlockIdx, newDefault);
}
CaseVector cases;
#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 1)
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i)
cases.push_back(SwitchCase(i.getCaseValue(),
i.getCaseSuccessor()));
#else
for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
cases.push_back(SwitchCase(SI->getSuccessorValue(i),
SI->getSuccessor(i)));
#endif
// reverse cases, as switchConvert constructs a chain of
// basic blocks by appending to the front. if we reverse,
// the if comparisons will happen in the same order
// as the cases appear in the switch
std::reverse(cases.begin(), cases.end());
switchConvert(cases.begin(), cases.end(), switchValue, origBlock, newDefault);
// We are now done with the switch instruction, so delete it
origBlock->getInstList().erase(SI);
}
/// ChangeToUnreachable - Insert an unreachable instruction before the specified
/// instruction, making it and the rest of the code in the block dead.
static void ChangeToUnreachable(Instruction *I) {
BasicBlock *BB = I->getParent();
// Loop over all of the successors, removing BB's entry from any PHI
// nodes.
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
(*SI)->removePredecessor(BB);
new UnreachableInst(I);
// All instructions after this are dead.
BasicBlock::iterator BBI = I, BBE = BB->end();
while (BBI != BBE) {
if (!BBI->use_empty())
BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
BB->getInstList().erase(BBI++);
}
}
/// ChangeToCall - Convert the specified invoke into a normal call.
static void ChangeToCall(InvokeInst *II) {
BasicBlock *BB = II->getParent();
SmallVector<Value*, 8> Args(II->op_begin()+3, II->op_end());
CallInst *NewCall = CallInst::Create(II->getCalledValue(), Args.begin(),
Args.end(), "", II);
NewCall->takeName(II);
NewCall->setCallingConv(II->getCallingConv());
NewCall->setParamAttrs(II->getParamAttrs());
II->replaceAllUsesWith(NewCall);
// Follow the call by a branch to the normal destination.
BranchInst::Create(II->getNormalDest(), II);
// Update PHI nodes in the unwind destination
II->getUnwindDest()->removePredecessor(BB);
BB->getInstList().erase(II);
}
/// This splits a basic block into two at the specified
/// instruction. Note that all instructions BEFORE the specified iterator stay
/// as part of the original basic block, an unconditional branch is added to
/// the new BB, and the rest of the instructions in the BB are moved to the new
/// BB, including the old terminator. This invalidates the iterator.
///
/// Note that this only works on well formed basic blocks (must have a
/// terminator), and 'I' must not be the end of instruction list (which would
/// cause a degenerate basic block to be formed, having a terminator inside of
/// the basic block).
///
BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName) {
assert(getTerminator() && "Can't use splitBasicBlock on degenerate BB!");
assert(I != InstList.end() &&
"Trying to get me to create degenerate basic block!");
BasicBlock *InsertBefore = std::next(Function::iterator(this))
.getNodePtrUnchecked();
BasicBlock *New = BasicBlock::Create(getContext(), BBName,
getParent(), InsertBefore);
// Save DebugLoc of split point before invalidating iterator.
DebugLoc Loc = I->getDebugLoc();
// Move all of the specified instructions from the original basic block into
// the new basic block.
New->getInstList().splice(New->end(), this->getInstList(), I, end());
// Add a branch instruction to the newly formed basic block.
BranchInst *BI = BranchInst::Create(New, this);
BI->setDebugLoc(Loc);
// Now we must loop through all of the successors of the New block (which
// _were_ the successors of the 'this' block), and update any PHI nodes in
// successors. If there were PHI nodes in the successors, then they need to
// know that incoming branches will be from New, not from Old.
//
for (succ_iterator I = succ_begin(New), E = succ_end(New); I != E; ++I) {
// Loop over any phi nodes in the basic block, updating the BB field of
// incoming values...
BasicBlock *Successor = *I;
PHINode *PN;
for (BasicBlock::iterator II = Successor->begin();
(PN = dyn_cast<PHINode>(II)); ++II) {
int IDX = PN->getBasicBlockIndex(this);
while (IDX != -1) {
PN->setIncomingBlock((unsigned)IDX, New);
IDX = PN->getBasicBlockIndex(this);
}
}
}
return New;
}
void HeterotbbTransform::copy_function (Function* NF, Function* F) {
DenseMap<const Value*, Value *> ValueMap;
// Get the names of the parameters for old function
for(Function::arg_iterator FI = F->arg_begin(), FE=F->arg_end(), DI=NF->arg_begin(); FE!=FI; ++FI,++DI) {
DI->setName(FI->getName());
ValueMap[FI]=DI;
}
for (Function::const_iterator BI=F->begin(),BE = F->end(); BI != BE; ++BI) {
const BasicBlock &FBB = *BI;
BasicBlock *NFBB = BasicBlock::Create(FBB.getContext(), "", NF);
ValueMap[&FBB] = NFBB;
if (FBB.hasName()) {
NFBB->setName(FBB.getName());
//DEBUG(dbgs()<<NFBB->getName()<<"\n");
}
for (BasicBlock::const_iterator II = FBB.begin(), IE = FBB.end(); II != IE; ++II) {
Instruction *NFInst = II->clone(/*F->getContext()*/);
if (II->hasName()) NFInst->setName(II->getName());
const Instruction *FInst = &(*II);
rewrite_instruction((Instruction *)FInst, NFInst, ValueMap);
NFBB->getInstList().push_back(NFInst);
ValueMap[II] = NFInst;
}
}
// Remap the instructions again to take care of forward jumps
for (Function::iterator BB = NF->begin(), BE=NF->end(); BB != BE; ++ BB) {
for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II) {
int opIdx = 0;
//DEBUG(dbgs()<<*II<<"\n");
for (User::op_iterator i = II->op_begin(), e = II->op_end(); i != e; ++i, opIdx++) {
Value *V = *i;
if (ValueMap[V] != NULL) {
II->setOperand(opIdx, ValueMap[V]);
}
}
}
}
//NF->dump();
}
void insertCallToAccessFunctionSequential(Function *F, Function *cF) {
CallInst *I;
BasicBlock *b;
Value::user_iterator i = F->user_begin(), e = F->user_end();
while (i != e) {
if (isa<CallInst>(*i)) {
I = dyn_cast<CallInst>(*i);
b = I->getParent();
BasicBlock::iterator helper(I);
CallInst *ci = dyn_cast<CallInst>(I->clone());
ci->setCalledFunction(cF);
b->getInstList().insertAfter(helper, ci);
i++;
I->replaceAllUsesWith(ci);
insertCallToPAPI(I, ci);
}
}
}
// switchConvert - Convert the switch statement into a binary lookup of
// the case values. The function recursively builds this tree.
//
BasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End,
Value* Val, BasicBlock* OrigBlock,
BasicBlock* Default)
{
unsigned Size = End - Begin;
if (Size == 1)
return newLeafBlock(*Begin, Val, OrigBlock, Default);
unsigned Mid = Size / 2;
std::vector<CaseRange> LHS(Begin, Begin + Mid);
DEBUG(dbgs() << "LHS: " << LHS << "\n");
std::vector<CaseRange> RHS(Begin + Mid, End);
DEBUG(dbgs() << "RHS: " << RHS << "\n");
CaseRange& Pivot = *(Begin + Mid);
DEBUG(dbgs() << "Pivot ==> "
<< cast<ConstantInt>(Pivot.Low)->getValue() << " -"
<< cast<ConstantInt>(Pivot.High)->getValue() << "\n");
BasicBlock* LBranch = switchConvert(LHS.begin(), LHS.end(), Val,
OrigBlock, Default);
BasicBlock* RBranch = switchConvert(RHS.begin(), RHS.end(), Val,
OrigBlock, Default);
// Create a new node that checks if the value is < pivot. Go to the
// left branch if it is and right branch if not.
Function* F = OrigBlock->getParent();
BasicBlock* NewNode = BasicBlock::Create(Val->getContext(), "NodeBlock");
Function::iterator FI = OrigBlock;
F->getBasicBlockList().insert(++FI, NewNode);
ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_SLT,
Val, Pivot.Low, "Pivot");
NewNode->getInstList().push_back(Comp);
BranchInst::Create(LBranch, RBranch, Comp, NewNode);
return NewNode;
}
/// MergeBasicBlockIntoOnlyPred - DestBB is a block with one predecessor and its
/// predecessor is known to have one successor (DestBB!). Eliminate the edge
/// between them, moving the instructions in the predecessor into DestBB and
/// deleting the predecessor block.
///
void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB) {
// If BB has single-entry PHI nodes, fold them.
while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
Value *NewVal = PN->getIncomingValue(0);
// Replace self referencing PHI with undef, it must be dead.
if (NewVal == PN) NewVal = UndefValue::get(PN->getType());
PN->replaceAllUsesWith(NewVal);
PN->eraseFromParent();
}
BasicBlock *PredBB = DestBB->getSinglePredecessor();
assert(PredBB && "Block doesn't have a single predecessor!");
// Splice all the instructions from PredBB to DestBB.
PredBB->getTerminator()->eraseFromParent();
DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
// Anything that branched to PredBB now branches to DestBB.
PredBB->replaceAllUsesWith(DestBB);
// Nuke BB.
PredBB->eraseFromParent();
}
/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor,
/// if possible. The return value indicates success or failure.
bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P) {
// Don't merge away blocks who have their address taken.
if (BB->hasAddressTaken()) return false;
// Can't merge if there are multiple predecessors, or no predecessors.
BasicBlock *PredBB = BB->getUniquePredecessor();
if (!PredBB) return false;
// Don't break self-loops.
if (PredBB == BB) return false;
// Don't break invokes.
if (isa<InvokeInst>(PredBB->getTerminator())) return false;
succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB));
BasicBlock *OnlySucc = BB;
for (; SI != SE; ++SI)
if (*SI != OnlySucc) {
OnlySucc = 0; // There are multiple distinct successors!
break;
}
// Can't merge if there are multiple successors.
if (!OnlySucc) return false;
// Can't merge if there is PHI loop.
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE; ++BI) {
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == PN)
return false;
} else
break;
}
// Begin by getting rid of unneeded PHIs.
if (isa<PHINode>(BB->front()))
FoldSingleEntryPHINodes(BB, P);
// Delete the unconditional branch from the predecessor...
PredBB->getInstList().pop_back();
// Make all PHI nodes that referred to BB now refer to Pred as their
// source...
BB->replaceAllUsesWith(PredBB);
// Move all definitions in the successor to the predecessor...
PredBB->getInstList().splice(PredBB->end(), BB->getInstList());
// Inherit predecessors name if it exists.
if (!PredBB->hasName())
PredBB->takeName(BB);
// Finally, erase the old block and update dominator info.
if (P) {
if (DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>()) {
if (DomTreeNode *DTN = DT->getNode(BB)) {
DomTreeNode *PredDTN = DT->getNode(PredBB);
SmallVector<DomTreeNode*, 8> Children(DTN->begin(), DTN->end());
for (SmallVector<DomTreeNode*, 8>::iterator DI = Children.begin(),
DE = Children.end(); DI != DE; ++DI)
DT->changeImmediateDominator(*DI, PredDTN);
DT->eraseNode(BB);
}
if (LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>())
LI->removeBlock(BB);
if (MemoryDependenceAnalysis *MD =
P->getAnalysisIfAvailable<MemoryDependenceAnalysis>())
MD->invalidateCachedPredecessors();
}
}
BB->eraseFromParent();
return true;
}
/// eliminateUnconditionalBranch - Clone the instructions from the destination
/// block into the source block, eliminating the specified unconditional branch.
/// If the destination block defines values used by successors of the dest
/// block, we may need to insert PHI nodes.
///
void TailDup::eliminateUnconditionalBranch(BranchInst *Branch) {
BasicBlock *SourceBlock = Branch->getParent();
BasicBlock *DestBlock = Branch->getSuccessor(0);
assert(SourceBlock != DestBlock && "Our predicate is broken!");
DEBUG(errs() << "TailDuplication[" << SourceBlock->getParent()->getName()
<< "]: Eliminating branch: " << *Branch);
// See if we can avoid duplicating code by moving it up to a dominator of both
// blocks.
if (BasicBlock *DomBlock = FindObviousSharedDomOf(SourceBlock, DestBlock)) {
DEBUG(errs() << "Found shared dominator: " << DomBlock->getName() << "\n");
// If there are non-phi instructions in DestBlock that have no operands
// defined in DestBlock, and if the instruction has no side effects, we can
// move the instruction to DomBlock instead of duplicating it.
BasicBlock::iterator BBI = DestBlock->getFirstNonPHI();
while (!isa<TerminatorInst>(BBI)) {
Instruction *I = BBI++;
bool CanHoist = I->isSafeToSpeculativelyExecute() &&
!I->mayReadFromMemory();
if (CanHoist) {
for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op)
if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(op)))
if (OpI->getParent() == DestBlock ||
(isa<InvokeInst>(OpI) && OpI->getParent() == DomBlock)) {
CanHoist = false;
break;
}
if (CanHoist) {
// Remove from DestBlock, move right before the term in DomBlock.
DestBlock->getInstList().remove(I);
DomBlock->getInstList().insert(DomBlock->getTerminator(), I);
DEBUG(errs() << "Hoisted: " << *I);
}
}
}
}
// Tail duplication can not update SSA properties correctly if the values
// defined in the duplicated tail are used outside of the tail itself. For
// this reason, we spill all values that are used outside of the tail to the
// stack.
for (BasicBlock::iterator I = DestBlock->begin(); I != DestBlock->end(); ++I)
if (I->isUsedOutsideOfBlock(DestBlock)) {
// We found a use outside of the tail. Create a new stack slot to
// break this inter-block usage pattern.
DemoteRegToStack(*I);
}
// We are going to have to map operands from the original block B to the new
// copy of the block B'. If there are PHI nodes in the DestBlock, these PHI
// nodes also define part of this mapping. Loop over these PHI nodes, adding
// them to our mapping.
//
std::map<Value*, Value*> ValueMapping;
BasicBlock::iterator BI = DestBlock->begin();
bool HadPHINodes = isa<PHINode>(BI);
for (; PHINode *PN = dyn_cast<PHINode>(BI); ++BI)
ValueMapping[PN] = PN->getIncomingValueForBlock(SourceBlock);
// Clone the non-phi instructions of the dest block into the source block,
// keeping track of the mapping...
//
for (; BI != DestBlock->end(); ++BI) {
Instruction *New = BI->clone();
New->setName(BI->getName());
SourceBlock->getInstList().push_back(New);
ValueMapping[BI] = New;
}
// Now that we have built the mapping information and cloned all of the
// instructions (giving us a new terminator, among other things), walk the new
// instructions, rewriting references of old instructions to use new
// instructions.
//
BI = Branch; ++BI; // Get an iterator to the first new instruction
for (; BI != SourceBlock->end(); ++BI)
for (unsigned i = 0, e = BI->getNumOperands(); i != e; ++i) {
std::map<Value*, Value*>::const_iterator I =
ValueMapping.find(BI->getOperand(i));
if (I != ValueMapping.end())
BI->setOperand(i, I->second);
}
// Next we check to see if any of the successors of DestBlock had PHI nodes.
// If so, we need to add entries to the PHI nodes for SourceBlock now.
for (succ_iterator SI = succ_begin(DestBlock), SE = succ_end(DestBlock);
SI != SE; ++SI) {
BasicBlock *Succ = *SI;
for (BasicBlock::iterator PNI = Succ->begin(); isa<PHINode>(PNI); ++PNI) {
PHINode *PN = cast<PHINode>(PNI);
// Ok, we have a PHI node. Figure out what the incoming value was for the
// DestBlock.
Value *IV = PN->getIncomingValueForBlock(DestBlock);
// Remap the value if necessary...
std::map<Value*, Value*>::const_iterator I = ValueMapping.find(IV);
if (I != ValueMapping.end())
IV = I->second;
PN->addIncoming(IV, SourceBlock);
}
}
// Next, remove the old branch instruction, and any PHI node entries that we
// had.
BI = Branch; ++BI; // Get an iterator to the first new instruction
DestBlock->removePredecessor(SourceBlock); // Remove entries in PHI nodes...
SourceBlock->getInstList().erase(Branch); // Destroy the uncond branch...
// Final step: now that we have finished everything up, walk the cloned
// instructions one last time, constant propagating and DCE'ing them, because
// they may not be needed anymore.
//
if (HadPHINodes) {
while (BI != SourceBlock->end()) {
Instruction *Inst = BI++;
if (isInstructionTriviallyDead(Inst))
Inst->eraseFromParent();
else if (Constant *C = ConstantFoldInstruction(Inst)) {
Inst->replaceAllUsesWith(C);
Inst->eraseFromParent();
}
}
}
++NumEliminated; // We just killed a branch!
}
/// Create a clone of the blocks in a loop and connect them together.
/// This function doesn't create a clone of the loop structure.
///
/// There are two value maps that are defined and used. VMap is
/// for the values in the current loop instance. LVMap contains
/// the values from the last loop instance. We need the LVMap values
/// to update the initial values for the current loop instance.
///
static void CloneLoopBlocks(Loop *L,
bool FirstCopy,
BasicBlock *InsertTop,
BasicBlock *InsertBot,
std::vector<BasicBlock *> &NewBlocks,
LoopBlocksDFS &LoopBlocks,
ValueToValueMapTy &VMap,
ValueToValueMapTy &LVMap,
LoopInfo *LI) {
BasicBlock *Preheader = L->getLoopPreheader();
BasicBlock *Header = L->getHeader();
BasicBlock *Latch = L->getLoopLatch();
Function *F = Header->getParent();
LoopBlocksDFS::RPOIterator BlockBegin = LoopBlocks.beginRPO();
LoopBlocksDFS::RPOIterator BlockEnd = LoopBlocks.endRPO();
// For each block in the original loop, create a new copy,
// and update the value map with the newly created values.
for (LoopBlocksDFS::RPOIterator BB = BlockBegin; BB != BlockEnd; ++BB) {
BasicBlock *NewBB = CloneBasicBlock(*BB, VMap, ".unr", F);
NewBlocks.push_back(NewBB);
if (Loop *ParentLoop = L->getParentLoop())
ParentLoop->addBasicBlockToLoop(NewBB, LI->getBase());
VMap[*BB] = NewBB;
if (Header == *BB) {
// For the first block, add a CFG connection to this newly
// created block
InsertTop->getTerminator()->setSuccessor(0, NewBB);
// Change the incoming values to the ones defined in the
// previously cloned loop.
for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
PHINode *NewPHI = cast<PHINode>(VMap[I]);
if (FirstCopy) {
// We replace the first phi node with the value from the preheader
VMap[I] = NewPHI->getIncomingValueForBlock(Preheader);
NewBB->getInstList().erase(NewPHI);
} else {
// Update VMap with values from the previous block
unsigned idx = NewPHI->getBasicBlockIndex(Latch);
Value *InVal = NewPHI->getIncomingValue(idx);
if (Instruction *I = dyn_cast<Instruction>(InVal))
if (L->contains(I))
InVal = LVMap[InVal];
NewPHI->setIncomingValue(idx, InVal);
NewPHI->setIncomingBlock(idx, InsertTop);
}
}
}
if (Latch == *BB) {
VMap.erase((*BB)->getTerminator());
NewBB->getTerminator()->eraseFromParent();
BranchInst::Create(InsertBot, NewBB);
}
}
// LastValueMap is updated with the values for the current loop
// which are used the next time this function is called.
for (ValueToValueMapTy::iterator VI = VMap.begin(), VE = VMap.end();
VI != VE; ++VI) {
LVMap[VI->first] = VI->second;
}
}
/// \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;
}
