| //===-- BasicBlock.cpp - Implement BasicBlock related methods -------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the BasicBlock class for the IR library. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/IR/BasicBlock.h" |
| #include "SymbolTableListTraitsImpl.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/IR/CFG.h" |
| #include "llvm/IR/Constants.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/IR/LLVMContext.h" |
| #include "llvm/IR/Type.h" |
| #include <algorithm> |
| |
| using namespace llvm; |
| |
| ValueSymbolTable *BasicBlock::getValueSymbolTable() { |
| if (Function *F = getParent()) |
| return F->getValueSymbolTable(); |
| return nullptr; |
| } |
| |
| LLVMContext &BasicBlock::getContext() const { |
| return getType()->getContext(); |
| } |
| |
| template <> void llvm::invalidateParentIListOrdering(BasicBlock *BB) { |
| BB->invalidateOrders(); |
| } |
| |
| // Explicit instantiation of SymbolTableListTraits since some of the methods |
| // are not in the public header file... |
| template class llvm::SymbolTableListTraits<Instruction>; |
| |
| BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent, |
| BasicBlock *InsertBefore) |
| : Value(Type::getLabelTy(C), Value::BasicBlockVal), Parent(nullptr) { |
| |
| if (NewParent) |
| insertInto(NewParent, InsertBefore); |
| else |
| assert(!InsertBefore && |
| "Cannot insert block before another block with no function!"); |
| |
| setName(Name); |
| } |
| |
| void BasicBlock::insertInto(Function *NewParent, BasicBlock *InsertBefore) { |
| assert(NewParent && "Expected a parent"); |
| assert(!Parent && "Already has a parent"); |
| |
| if (InsertBefore) |
| NewParent->getBasicBlockList().insert(InsertBefore->getIterator(), this); |
| else |
| NewParent->getBasicBlockList().push_back(this); |
| } |
| |
| BasicBlock::~BasicBlock() { |
| validateInstrOrdering(); |
| |
| // If the address of the block is taken and it is being deleted (e.g. because |
| // it is dead), this means that there is either a dangling constant expr |
| // hanging off the block, or an undefined use of the block (source code |
| // expecting the address of a label to keep the block alive even though there |
| // is no indirect branch). Handle these cases by zapping the BlockAddress |
| // nodes. There are no other possible uses at this point. |
| if (hasAddressTaken()) { |
| assert(!use_empty() && "There should be at least one blockaddress!"); |
| Constant *Replacement = |
| ConstantInt::get(llvm::Type::getInt32Ty(getContext()), 1); |
| while (!use_empty()) { |
| BlockAddress *BA = cast<BlockAddress>(user_back()); |
| BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement, |
| BA->getType())); |
| BA->destroyConstant(); |
| } |
| } |
| |
| assert(getParent() == nullptr && "BasicBlock still linked into the program!"); |
| dropAllReferences(); |
| InstList.clear(); |
| } |
| |
| void BasicBlock::setParent(Function *parent) { |
| // Set Parent=parent, updating instruction symtab entries as appropriate. |
| InstList.setSymTabObject(&Parent, parent); |
| } |
| |
| iterator_range<filter_iterator<BasicBlock::const_iterator, |
| std::function<bool(const Instruction &)>>> |
| BasicBlock::instructionsWithoutDebug() const { |
| std::function<bool(const Instruction &)> Fn = [](const Instruction &I) { |
| return !isa<DbgInfoIntrinsic>(I); |
| }; |
| return make_filter_range(*this, Fn); |
| } |
| |
| iterator_range<filter_iterator<BasicBlock::iterator, |
| std::function<bool(Instruction &)>>> |
| BasicBlock::instructionsWithoutDebug() { |
| std::function<bool(Instruction &)> Fn = [](Instruction &I) { |
| return !isa<DbgInfoIntrinsic>(I); |
| }; |
| return make_filter_range(*this, Fn); |
| } |
| |
| filter_iterator<BasicBlock::const_iterator, |
| std::function<bool(const Instruction &)>>::difference_type |
| BasicBlock::sizeWithoutDebug() const { |
| return std::distance(instructionsWithoutDebug().begin(), |
| instructionsWithoutDebug().end()); |
| } |
| |
| void BasicBlock::removeFromParent() { |
| getParent()->getBasicBlockList().remove(getIterator()); |
| } |
| |
| iplist<BasicBlock>::iterator BasicBlock::eraseFromParent() { |
| return getParent()->getBasicBlockList().erase(getIterator()); |
| } |
| |
| /// Unlink this basic block from its current function and |
| /// insert it into the function that MovePos lives in, right before MovePos. |
| void BasicBlock::moveBefore(BasicBlock *MovePos) { |
| MovePos->getParent()->getBasicBlockList().splice( |
| MovePos->getIterator(), getParent()->getBasicBlockList(), getIterator()); |
| } |
| |
| /// Unlink this basic block from its current function and |
| /// insert it into the function that MovePos lives in, right after MovePos. |
| void BasicBlock::moveAfter(BasicBlock *MovePos) { |
| MovePos->getParent()->getBasicBlockList().splice( |
| ++MovePos->getIterator(), getParent()->getBasicBlockList(), |
| getIterator()); |
| } |
| |
| const Module *BasicBlock::getModule() const { |
| return getParent()->getParent(); |
| } |
| |
| const Instruction *BasicBlock::getTerminator() const { |
| if (InstList.empty() || !InstList.back().isTerminator()) |
| return nullptr; |
| return &InstList.back(); |
| } |
| |
| const CallInst *BasicBlock::getTerminatingMustTailCall() const { |
| if (InstList.empty()) |
| return nullptr; |
| const ReturnInst *RI = dyn_cast<ReturnInst>(&InstList.back()); |
| if (!RI || RI == &InstList.front()) |
| return nullptr; |
| |
| const Instruction *Prev = RI->getPrevNode(); |
| if (!Prev) |
| return nullptr; |
| |
| if (Value *RV = RI->getReturnValue()) { |
| if (RV != Prev) |
| return nullptr; |
| |
| // Look through the optional bitcast. |
| if (auto *BI = dyn_cast<BitCastInst>(Prev)) { |
| RV = BI->getOperand(0); |
| Prev = BI->getPrevNode(); |
| if (!Prev || RV != Prev) |
| return nullptr; |
| } |
| } |
| |
| if (auto *CI = dyn_cast<CallInst>(Prev)) { |
| if (CI->isMustTailCall()) |
| return CI; |
| } |
| return nullptr; |
| } |
| |
| const CallInst *BasicBlock::getTerminatingDeoptimizeCall() const { |
| if (InstList.empty()) |
| return nullptr; |
| auto *RI = dyn_cast<ReturnInst>(&InstList.back()); |
| if (!RI || RI == &InstList.front()) |
| return nullptr; |
| |
| if (auto *CI = dyn_cast_or_null<CallInst>(RI->getPrevNode())) |
| if (Function *F = CI->getCalledFunction()) |
| if (F->getIntrinsicID() == Intrinsic::experimental_deoptimize) |
| return CI; |
| |
| return nullptr; |
| } |
| |
| const CallInst *BasicBlock::getPostdominatingDeoptimizeCall() const { |
| const BasicBlock* BB = this; |
| SmallPtrSet<const BasicBlock *, 8> Visited; |
| Visited.insert(BB); |
| while (auto *Succ = BB->getUniqueSuccessor()) { |
| if (!Visited.insert(Succ).second) |
| return nullptr; |
| BB = Succ; |
| } |
| return BB->getTerminatingDeoptimizeCall(); |
| } |
| |
| const Instruction* BasicBlock::getFirstNonPHI() const { |
| for (const Instruction &I : *this) |
| if (!isa<PHINode>(I)) |
| return &I; |
| return nullptr; |
| } |
| |
| const Instruction* BasicBlock::getFirstNonPHIOrDbg() const { |
| for (const Instruction &I : *this) |
| if (!isa<PHINode>(I) && !isa<DbgInfoIntrinsic>(I)) |
| return &I; |
| return nullptr; |
| } |
| |
| const Instruction* BasicBlock::getFirstNonPHIOrDbgOrLifetime() const { |
| for (const Instruction &I : *this) { |
| if (isa<PHINode>(I) || isa<DbgInfoIntrinsic>(I)) |
| continue; |
| |
| if (I.isLifetimeStartOrEnd()) |
| continue; |
| |
| return &I; |
| } |
| return nullptr; |
| } |
| |
| BasicBlock::const_iterator BasicBlock::getFirstInsertionPt() const { |
| const Instruction *FirstNonPHI = getFirstNonPHI(); |
| if (!FirstNonPHI) |
| return end(); |
| |
| const_iterator InsertPt = FirstNonPHI->getIterator(); |
| if (InsertPt->isEHPad()) ++InsertPt; |
| return InsertPt; |
| } |
| |
| void BasicBlock::dropAllReferences() { |
| for (Instruction &I : *this) |
| I.dropAllReferences(); |
| } |
| |
| /// If this basic block has a single predecessor block, |
| /// return the block, otherwise return a null pointer. |
| const BasicBlock *BasicBlock::getSinglePredecessor() const { |
| const_pred_iterator PI = pred_begin(this), E = pred_end(this); |
| if (PI == E) return nullptr; // No preds. |
| const BasicBlock *ThePred = *PI; |
| ++PI; |
| return (PI == E) ? ThePred : nullptr /*multiple preds*/; |
| } |
| |
| /// If this basic block has a unique predecessor block, |
| /// return the block, otherwise return a null pointer. |
| /// Note that unique predecessor doesn't mean single edge, there can be |
| /// multiple edges from the unique predecessor to this block (for example |
| /// a switch statement with multiple cases having the same destination). |
| const BasicBlock *BasicBlock::getUniquePredecessor() const { |
| const_pred_iterator PI = pred_begin(this), E = pred_end(this); |
| if (PI == E) return nullptr; // No preds. |
| const BasicBlock *PredBB = *PI; |
| ++PI; |
| for (;PI != E; ++PI) { |
| if (*PI != PredBB) |
| return nullptr; |
| // The same predecessor appears multiple times in the predecessor list. |
| // This is OK. |
| } |
| return PredBB; |
| } |
| |
| bool BasicBlock::hasNPredecessors(unsigned N) const { |
| return hasNItems(pred_begin(this), pred_end(this), N); |
| } |
| |
| bool BasicBlock::hasNPredecessorsOrMore(unsigned N) const { |
| return hasNItemsOrMore(pred_begin(this), pred_end(this), N); |
| } |
| |
| const BasicBlock *BasicBlock::getSingleSuccessor() const { |
| const_succ_iterator SI = succ_begin(this), E = succ_end(this); |
| if (SI == E) return nullptr; // no successors |
| const BasicBlock *TheSucc = *SI; |
| ++SI; |
| return (SI == E) ? TheSucc : nullptr /* multiple successors */; |
| } |
| |
| const BasicBlock *BasicBlock::getUniqueSuccessor() const { |
| const_succ_iterator SI = succ_begin(this), E = succ_end(this); |
| if (SI == E) return nullptr; // No successors |
| const BasicBlock *SuccBB = *SI; |
| ++SI; |
| for (;SI != E; ++SI) { |
| if (*SI != SuccBB) |
| return nullptr; |
| // The same successor appears multiple times in the successor list. |
| // This is OK. |
| } |
| return SuccBB; |
| } |
| |
| iterator_range<BasicBlock::phi_iterator> BasicBlock::phis() { |
| PHINode *P = empty() ? nullptr : dyn_cast<PHINode>(&*begin()); |
| return make_range<phi_iterator>(P, nullptr); |
| } |
| |
| /// Update PHI nodes in this BasicBlock before removal of predecessor \p Pred. |
| /// Note that this function does not actually remove the predecessor. |
| /// |
| /// If \p KeepOneInputPHIs is true then don't remove PHIs that are left with |
| /// zero or one incoming values, and don't simplify PHIs with all incoming |
| /// values the same. |
| void BasicBlock::removePredecessor(BasicBlock *Pred, |
| bool KeepOneInputPHIs) { |
| // Use hasNUsesOrMore to bound the cost of this assertion for complex CFGs. |
| assert((hasNUsesOrMore(16) || |
| find(pred_begin(this), pred_end(this), Pred) != pred_end(this)) && |
| "Pred is not a predecessor!"); |
| |
| // Return early if there are no PHI nodes to update. |
| if (!isa<PHINode>(begin())) |
| return; |
| unsigned NumPreds = cast<PHINode>(front()).getNumIncomingValues(); |
| |
| // Update all PHI nodes. |
| for (iterator II = begin(); isa<PHINode>(II);) { |
| PHINode *PN = cast<PHINode>(II++); |
| PN->removeIncomingValue(Pred, !KeepOneInputPHIs); |
| if (!KeepOneInputPHIs) { |
| // If we have a single predecessor, removeIncomingValue erased the PHI |
| // node itself. |
| if (NumPreds > 1) { |
| if (Value *PNV = PN->hasConstantValue()) { |
| // Replace the PHI node with its constant value. |
| PN->replaceAllUsesWith(PNV); |
| PN->eraseFromParent(); |
| } |
| } |
| } |
| } |
| } |
| |
| bool BasicBlock::canSplitPredecessors() const { |
| const Instruction *FirstNonPHI = getFirstNonPHI(); |
| if (isa<LandingPadInst>(FirstNonPHI)) |
| return true; |
| // This is perhaps a little conservative because constructs like |
| // CleanupBlockInst are pretty easy to split. However, SplitBlockPredecessors |
| // cannot handle such things just yet. |
| if (FirstNonPHI->isEHPad()) |
| return false; |
| return true; |
| } |
| |
| bool BasicBlock::isLegalToHoistInto() const { |
| auto *Term = getTerminator(); |
| // No terminator means the block is under construction. |
| if (!Term) |
| return true; |
| |
| // If the block has no successors, there can be no instructions to hoist. |
| assert(Term->getNumSuccessors() > 0); |
| |
| // Instructions should not be hoisted across exception handling boundaries. |
| return !Term->isExceptionalTerminator(); |
| } |
| |
| /// 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 *New = BasicBlock::Create(getContext(), BBName, getParent(), |
| this->getNextNode()); |
| |
| // 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 (this). |
| // |
| New->replaceSuccessorsPhiUsesWith(this, New); |
| return New; |
| } |
| |
| void BasicBlock::replacePhiUsesWith(BasicBlock *Old, BasicBlock *New) { |
| // N.B. This might not be a complete BasicBlock, so don't assume |
| // that it ends with a non-phi instruction. |
| for (iterator II = begin(), IE = end(); II != IE; ++II) { |
| PHINode *PN = dyn_cast<PHINode>(II); |
| if (!PN) |
| break; |
| PN->replaceIncomingBlockWith(Old, New); |
| } |
| } |
| |
| void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *Old, |
| BasicBlock *New) { |
| Instruction *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; |
| llvm::for_each(successors(TI), [Old, New](BasicBlock *Succ) { |
| Succ->replacePhiUsesWith(Old, New); |
| }); |
| } |
| |
| void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) { |
| this->replaceSuccessorsPhiUsesWith(this, New); |
| } |
| |
| /// Return true if this basic block is a landing pad. I.e., it's |
| /// the destination of the 'unwind' edge of an invoke instruction. |
| bool BasicBlock::isLandingPad() const { |
| return isa<LandingPadInst>(getFirstNonPHI()); |
| } |
| |
| /// Return the landingpad instruction associated with the landing pad. |
| const LandingPadInst *BasicBlock::getLandingPadInst() const { |
| return dyn_cast<LandingPadInst>(getFirstNonPHI()); |
| } |
| |
| Optional<uint64_t> BasicBlock::getIrrLoopHeaderWeight() const { |
| const Instruction *TI = getTerminator(); |
| if (MDNode *MDIrrLoopHeader = |
| TI->getMetadata(LLVMContext::MD_irr_loop)) { |
| MDString *MDName = cast<MDString>(MDIrrLoopHeader->getOperand(0)); |
| if (MDName->getString().equals("loop_header_weight")) { |
| auto *CI = mdconst::extract<ConstantInt>(MDIrrLoopHeader->getOperand(1)); |
| return Optional<uint64_t>(CI->getValue().getZExtValue()); |
| } |
| } |
| return Optional<uint64_t>(); |
| } |
| |
| BasicBlock::iterator llvm::skipDebugIntrinsics(BasicBlock::iterator It) { |
| while (isa<DbgInfoIntrinsic>(It)) |
| ++It; |
| return It; |
| } |
| |
| void BasicBlock::renumberInstructions() { |
| unsigned Order = 0; |
| for (Instruction &I : *this) |
| I.Order = Order++; |
| |
| // Set the bit to indicate that the instruction order valid and cached. |
| BasicBlockBits Bits = getBasicBlockBits(); |
| Bits.InstrOrderValid = true; |
| setBasicBlockBits(Bits); |
| } |
| |
| #ifndef NDEBUG |
| /// In asserts builds, this checks the numbering. In non-asserts builds, it |
| /// is defined as a no-op inline function in BasicBlock.h. |
| void BasicBlock::validateInstrOrdering() const { |
| if (!isInstrOrderValid()) |
| return; |
| const Instruction *Prev = nullptr; |
| for (const Instruction &I : *this) { |
| assert((!Prev || Prev->comesBefore(&I)) && |
| "cached instruction ordering is incorrect"); |
| Prev = &I; |
| } |
| } |
| #endif |