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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229340 91177308-0d34-0410-b5e6-96231b3b80d8
337 lines
14 KiB
C++
337 lines
14 KiB
C++
//===-- llvm/BasicBlock.h - Represent a basic block in the VM ---*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the declaration of the BasicBlock class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_BASICBLOCK_H
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#define LLVM_IR_BASICBLOCK_H
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#include "llvm/ADT/Twine.h"
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#include "llvm/ADT/ilist.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/SymbolTableListTraits.h"
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#include "llvm/Support/CBindingWrapping.h"
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#include "llvm/Support/DataTypes.h"
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namespace llvm {
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class CallInst;
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class LandingPadInst;
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class TerminatorInst;
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class LLVMContext;
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class BlockAddress;
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template<> struct ilist_traits<Instruction>
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: public SymbolTableListTraits<Instruction, BasicBlock> {
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/// \brief Return a node that marks the end of a list.
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///
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/// The sentinel is relative to this instance, so we use a non-static
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/// method.
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Instruction *createSentinel() const {
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// Since i(p)lists always publicly derive from their corresponding traits,
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// placing a data member in this class will augment the i(p)list. But since
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// the NodeTy is expected to be publicly derive from ilist_node<NodeTy>,
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// there is a legal viable downcast from it to NodeTy. We use this trick to
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// superimpose an i(p)list with a "ghostly" NodeTy, which becomes the
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// sentinel. Dereferencing the sentinel is forbidden (save the
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// ilist_node<NodeTy>), so no one will ever notice the superposition.
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return static_cast<Instruction*>(&Sentinel);
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}
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static void destroySentinel(Instruction*) {}
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Instruction *provideInitialHead() const { return createSentinel(); }
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Instruction *ensureHead(Instruction*) const { return createSentinel(); }
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static void noteHead(Instruction*, Instruction*) {}
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private:
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mutable ilist_half_node<Instruction> Sentinel;
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};
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/// \brief LLVM Basic Block Representation
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///
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/// This represents a single basic block in LLVM. A basic block is simply a
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/// container of instructions that execute sequentially. Basic blocks are Values
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/// because they are referenced by instructions such as branches and switch
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/// tables. The type of a BasicBlock is "Type::LabelTy" because the basic block
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/// represents a label to which a branch can jump.
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///
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/// A well formed basic block is formed of a list of non-terminating
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/// instructions followed by a single TerminatorInst instruction.
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/// TerminatorInst's may not occur in the middle of basic blocks, and must
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/// terminate the blocks. The BasicBlock class allows malformed basic blocks to
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/// occur because it may be useful in the intermediate stage of constructing or
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/// modifying a program. However, the verifier will ensure that basic blocks
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/// are "well formed".
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class BasicBlock : public Value, // Basic blocks are data objects also
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public ilist_node<BasicBlock> {
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friend class BlockAddress;
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public:
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typedef iplist<Instruction> InstListType;
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private:
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InstListType InstList;
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Function *Parent;
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void setParent(Function *parent);
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friend class SymbolTableListTraits<BasicBlock, Function>;
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BasicBlock(const BasicBlock &) = delete;
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void operator=(const BasicBlock &) = delete;
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/// \brief Constructor.
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///
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/// If the function parameter is specified, the basic block is automatically
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/// inserted at either the end of the function (if InsertBefore is null), or
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/// before the specified basic block.
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explicit BasicBlock(LLVMContext &C, const Twine &Name = "",
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Function *Parent = nullptr,
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BasicBlock *InsertBefore = nullptr);
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public:
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/// \brief Get the context in which this basic block lives.
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LLVMContext &getContext() const;
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/// Instruction iterators...
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typedef InstListType::iterator iterator;
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typedef InstListType::const_iterator const_iterator;
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typedef InstListType::reverse_iterator reverse_iterator;
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typedef InstListType::const_reverse_iterator const_reverse_iterator;
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/// \brief Creates a new BasicBlock.
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///
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/// If the Parent parameter is specified, the basic block is automatically
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/// inserted at either the end of the function (if InsertBefore is 0), or
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/// before the specified basic block.
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static BasicBlock *Create(LLVMContext &Context, const Twine &Name = "",
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Function *Parent = nullptr,
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BasicBlock *InsertBefore = nullptr) {
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return new BasicBlock(Context, Name, Parent, InsertBefore);
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}
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~BasicBlock();
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/// \brief Return the enclosing method, or null if none.
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const Function *getParent() const { return Parent; }
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Function *getParent() { return Parent; }
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const DataLayout *getDataLayout() const;
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/// \brief Returns the terminator instruction if the block is well formed or
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/// null if the block is not well formed.
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TerminatorInst *getTerminator();
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const TerminatorInst *getTerminator() const;
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/// \brief Returns the call instruction marked 'musttail' prior to the
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/// terminating return instruction of this basic block, if such a call is
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/// present. Otherwise, returns null.
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CallInst *getTerminatingMustTailCall();
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const CallInst *getTerminatingMustTailCall() const {
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return const_cast<BasicBlock *>(this)->getTerminatingMustTailCall();
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}
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/// \brief Returns a pointer to the first instruction in this block that is
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/// not a PHINode instruction.
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///
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/// When adding instructions to the beginning of the basic block, they should
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/// be added before the returned value, not before the first instruction,
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/// which might be PHI. Returns 0 is there's no non-PHI instruction.
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Instruction* getFirstNonPHI();
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const Instruction* getFirstNonPHI() const {
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return const_cast<BasicBlock*>(this)->getFirstNonPHI();
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}
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/// \brief Returns a pointer to the first instruction in this block that is not
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/// a PHINode or a debug intrinsic.
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Instruction* getFirstNonPHIOrDbg();
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const Instruction* getFirstNonPHIOrDbg() const {
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return const_cast<BasicBlock*>(this)->getFirstNonPHIOrDbg();
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}
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/// \brief Returns a pointer to the first instruction in this block that is not
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/// a PHINode, a debug intrinsic, or a lifetime intrinsic.
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Instruction* getFirstNonPHIOrDbgOrLifetime();
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const Instruction* getFirstNonPHIOrDbgOrLifetime() const {
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return const_cast<BasicBlock*>(this)->getFirstNonPHIOrDbgOrLifetime();
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}
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/// \brief Returns an iterator to the first instruction in this block that is
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/// suitable for inserting a non-PHI instruction.
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///
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/// In particular, it skips all PHIs and LandingPad instructions.
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iterator getFirstInsertionPt();
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const_iterator getFirstInsertionPt() const {
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return const_cast<BasicBlock*>(this)->getFirstInsertionPt();
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}
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/// \brief Unlink 'this' from the containing function, but do not delete it.
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void removeFromParent();
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/// \brief Unlink 'this' from the containing function and delete it.
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void eraseFromParent();
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/// \brief Unlink this basic block from its current function and insert it
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/// into the function that \p MovePos lives in, right before \p MovePos.
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void moveBefore(BasicBlock *MovePos);
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/// \brief Unlink this basic block from its current function and insert it
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/// right after \p MovePos in the function \p MovePos lives in.
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void moveAfter(BasicBlock *MovePos);
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/// \brief Insert unlinked basic block into a function.
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///
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/// Inserts an unlinked basic block into \c Parent. If \c InsertBefore is
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/// provided, inserts before that basic block, otherwise inserts at the end.
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///
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/// \pre \a getParent() is \c nullptr.
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void insertInto(Function *Parent, BasicBlock *InsertBefore = nullptr);
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/// \brief Return the predecessor of this block if it has a single predecessor
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/// block. Otherwise return a null pointer.
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BasicBlock *getSinglePredecessor();
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const BasicBlock *getSinglePredecessor() const {
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return const_cast<BasicBlock*>(this)->getSinglePredecessor();
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}
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/// \brief Return the predecessor of this block if it has a unique predecessor
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/// block. Otherwise return a null pointer.
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///
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/// Note that unique predecessor doesn't mean single edge, there can be
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/// multiple edges from the unique predecessor to this block (for example a
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/// switch statement with multiple cases having the same destination).
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BasicBlock *getUniquePredecessor();
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const BasicBlock *getUniquePredecessor() const {
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return const_cast<BasicBlock*>(this)->getUniquePredecessor();
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}
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/// Return the successor of this block if it has a unique successor.
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/// Otherwise return a null pointer. This method is analogous to
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/// getUniquePredeccessor above.
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BasicBlock *getUniqueSuccessor();
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const BasicBlock *getUniqueSuccessor() const {
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return const_cast<BasicBlock*>(this)->getUniqueSuccessor();
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}
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//===--------------------------------------------------------------------===//
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/// Instruction iterator methods
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///
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inline iterator begin() { return InstList.begin(); }
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inline const_iterator begin() const { return InstList.begin(); }
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inline iterator end () { return InstList.end(); }
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inline const_iterator end () const { return InstList.end(); }
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inline reverse_iterator rbegin() { return InstList.rbegin(); }
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inline const_reverse_iterator rbegin() const { return InstList.rbegin(); }
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inline reverse_iterator rend () { return InstList.rend(); }
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inline const_reverse_iterator rend () const { return InstList.rend(); }
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inline size_t size() const { return InstList.size(); }
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inline bool empty() const { return InstList.empty(); }
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inline const Instruction &front() const { return InstList.front(); }
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inline Instruction &front() { return InstList.front(); }
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inline const Instruction &back() const { return InstList.back(); }
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inline Instruction &back() { return InstList.back(); }
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/// \brief Return the underlying instruction list container.
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///
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/// Currently you need to access the underlying instruction list container
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/// directly if you want to modify it.
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const InstListType &getInstList() const { return InstList; }
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InstListType &getInstList() { return InstList; }
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/// \brief Returns a pointer to a member of the instruction list.
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static iplist<Instruction> BasicBlock::*getSublistAccess(Instruction*) {
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return &BasicBlock::InstList;
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}
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/// \brief Returns a pointer to the symbol table if one exists.
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ValueSymbolTable *getValueSymbolTable();
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/// \brief Methods for support type inquiry through isa, cast, and dyn_cast.
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static inline bool classof(const Value *V) {
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return V->getValueID() == Value::BasicBlockVal;
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}
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/// \brief Cause all subinstructions to "let go" of all the references that
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/// said subinstructions are maintaining.
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///
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/// This allows one to 'delete' a whole class at a time, even though there may
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/// be circular references... first all references are dropped, and all use
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/// counts go to zero. Then everything is delete'd for real. Note that no
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/// operations are valid on an object that has "dropped all references",
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/// except operator delete.
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void dropAllReferences();
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/// \brief Notify the BasicBlock that the predecessor \p Pred is no longer
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/// able to reach it.
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///
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/// This is actually not used to update the Predecessor list, but is actually
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/// used to update the PHI nodes that reside in the block. Note that this
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/// should be called while the predecessor still refers to this block.
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void removePredecessor(BasicBlock *Pred, bool DontDeleteUselessPHIs = false);
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/// \brief Split the basic block into two basic blocks at the specified
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/// instruction.
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///
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/// Note that all instructions BEFORE the specified iterator stay as part of
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/// the original basic block, an unconditional branch is added to the original
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/// BB, and the rest of the instructions in the BB are moved to the new BB,
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/// including the old terminator. The newly formed BasicBlock is returned.
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/// This function invalidates the specified iterator.
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///
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/// Note that this only works on well formed basic blocks (must have a
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/// terminator), and 'I' must not be the end of instruction list (which would
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/// cause a degenerate basic block to be formed, having a terminator inside of
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/// the basic block).
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///
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/// Also note that this doesn't preserve any passes. To split blocks while
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/// keeping loop information consistent, use the SplitBlock utility function.
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BasicBlock *splitBasicBlock(iterator I, const Twine &BBName = "");
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/// \brief Returns true if there are any uses of this basic block other than
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/// direct branches, switches, etc. to it.
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bool hasAddressTaken() const { return getSubclassDataFromValue() != 0; }
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/// \brief Update all phi nodes in this basic block's successors to refer to
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/// basic block \p New instead of to it.
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void replaceSuccessorsPhiUsesWith(BasicBlock *New);
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/// \brief Return true if this basic block is a landing pad.
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///
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/// Being a ``landing pad'' means that the basic block is the destination of
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/// the 'unwind' edge of an invoke instruction.
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bool isLandingPad() const;
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/// \brief Return the landingpad instruction associated with the landing pad.
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LandingPadInst *getLandingPadInst();
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const LandingPadInst *getLandingPadInst() const;
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private:
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/// \brief Increment the internal refcount of the number of BlockAddresses
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/// referencing this BasicBlock by \p Amt.
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///
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/// This is almost always 0, sometimes one possibly, but almost never 2, and
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/// inconceivably 3 or more.
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void AdjustBlockAddressRefCount(int Amt) {
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setValueSubclassData(getSubclassDataFromValue()+Amt);
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assert((int)(signed char)getSubclassDataFromValue() >= 0 &&
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"Refcount wrap-around");
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}
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/// \brief Shadow Value::setValueSubclassData with a private forwarding method
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/// so that any future subclasses cannot accidentally use it.
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void setValueSubclassData(unsigned short D) {
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Value::setValueSubclassData(D);
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}
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};
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// Create wrappers for C Binding types (see CBindingWrapping.h).
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DEFINE_SIMPLE_CONVERSION_FUNCTIONS(BasicBlock, LLVMBasicBlockRef)
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} // End llvm namespace
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#endif
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