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Diffstat (limited to 'include/llvm/IR/BasicBlock.h')
-rw-r--r-- | include/llvm/IR/BasicBlock.h | 297 |
1 files changed, 297 insertions, 0 deletions
diff --git a/include/llvm/IR/BasicBlock.h b/include/llvm/IR/BasicBlock.h new file mode 100644 index 0000000000..15f4aa7044 --- /dev/null +++ b/include/llvm/IR/BasicBlock.h @@ -0,0 +1,297 @@ +//===-- llvm/BasicBlock.h - Represent a basic block in the VM ---*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file contains the declaration of the BasicBlock class. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_BASICBLOCK_H +#define LLVM_BASICBLOCK_H + +#include "llvm/ADT/Twine.h" +#include "llvm/ADT/ilist.h" +#include "llvm/IR/Instruction.h" +#include "llvm/IR/SymbolTableListTraits.h" +#include "llvm/Support/DataTypes.h" + +namespace llvm { + +class LandingPadInst; +class TerminatorInst; +class LLVMContext; +class BlockAddress; + +template<> struct ilist_traits<Instruction> + : public SymbolTableListTraits<Instruction, BasicBlock> { + // createSentinel is used to get hold of a node that marks the end of + // the list... + // The sentinel is relative to this instance, so we use a non-static + // method. + Instruction *createSentinel() const { + // since i(p)lists always publicly derive from the corresponding + // traits, placing a data member in this class will augment i(p)list. + // But since the NodeTy is expected to publicly derive from + // ilist_node<NodeTy>, there is a legal viable downcast from it + // to NodeTy. We use this trick to superpose i(p)list with a "ghostly" + // NodeTy, which becomes the sentinel. Dereferencing the sentinel is + // forbidden (save the ilist_node<NodeTy>) so no one will ever notice + // the superposition. + return static_cast<Instruction*>(&Sentinel); + } + static void destroySentinel(Instruction*) {} + + Instruction *provideInitialHead() const { return createSentinel(); } + Instruction *ensureHead(Instruction*) const { return createSentinel(); } + static void noteHead(Instruction*, Instruction*) {} +private: + mutable ilist_half_node<Instruction> Sentinel; +}; + +/// This represents a single basic block in LLVM. A basic block is simply a +/// container of instructions that execute sequentially. Basic blocks are Values +/// because they are referenced by instructions such as branches and switch +/// tables. The type of a BasicBlock is "Type::LabelTy" because the basic block +/// represents a label to which a branch can jump. +/// +/// A well formed basic block is formed of a list of non-terminating +/// instructions followed by a single TerminatorInst instruction. +/// TerminatorInst's may not occur in the middle of basic blocks, and must +/// terminate the blocks. The BasicBlock class allows malformed basic blocks to +/// occur because it may be useful in the intermediate stage of constructing or +/// modifying a program. However, the verifier will ensure that basic blocks +/// are "well formed". +/// @brief LLVM Basic Block Representation +class BasicBlock : public Value, // Basic blocks are data objects also + public ilist_node<BasicBlock> { + friend class BlockAddress; +public: + typedef iplist<Instruction> InstListType; +private: + InstListType InstList; + Function *Parent; + + void setParent(Function *parent); + friend class SymbolTableListTraits<BasicBlock, Function>; + + BasicBlock(const BasicBlock &) LLVM_DELETED_FUNCTION; + void operator=(const BasicBlock &) LLVM_DELETED_FUNCTION; + + /// BasicBlock ctor - If the function parameter is specified, the basic block + /// is automatically inserted at either the end of the function (if + /// InsertBefore is null), or before the specified basic block. + /// + explicit BasicBlock(LLVMContext &C, const Twine &Name = "", + Function *Parent = 0, BasicBlock *InsertBefore = 0); +public: + /// getContext - Get the context in which this basic block lives. + LLVMContext &getContext() const; + + /// Instruction iterators... + typedef InstListType::iterator iterator; + typedef InstListType::const_iterator const_iterator; + typedef InstListType::reverse_iterator reverse_iterator; + typedef InstListType::const_reverse_iterator const_reverse_iterator; + + /// Create - Creates a new BasicBlock. If the Parent parameter is specified, + /// the basic block is automatically inserted at either the end of the + /// function (if InsertBefore is 0), or before the specified basic block. + static BasicBlock *Create(LLVMContext &Context, const Twine &Name = "", + Function *Parent = 0,BasicBlock *InsertBefore = 0) { + return new BasicBlock(Context, Name, Parent, InsertBefore); + } + ~BasicBlock(); + + /// getParent - Return the enclosing method, or null if none + /// + const Function *getParent() const { return Parent; } + Function *getParent() { return Parent; } + + /// getTerminator() - If this is a well formed basic block, then this returns + /// a pointer to the terminator instruction. If it is not, then you get a + /// null pointer back. + /// + TerminatorInst *getTerminator(); + const TerminatorInst *getTerminator() const; + + /// Returns a pointer to the first instructon in this block that is not a + /// PHINode instruction. When adding instruction to the beginning of the + /// basic block, they should be added before the returned value, not before + /// the first instruction, which might be PHI. + /// Returns 0 is there's no non-PHI instruction. + Instruction* getFirstNonPHI(); + const Instruction* getFirstNonPHI() const { + return const_cast<BasicBlock*>(this)->getFirstNonPHI(); + } + + // Same as above, but also skip debug intrinsics. + Instruction* getFirstNonPHIOrDbg(); + const Instruction* getFirstNonPHIOrDbg() const { + return const_cast<BasicBlock*>(this)->getFirstNonPHIOrDbg(); + } + + // Same as above, but also skip lifetime intrinsics. + Instruction* getFirstNonPHIOrDbgOrLifetime(); + const Instruction* getFirstNonPHIOrDbgOrLifetime() const { + return const_cast<BasicBlock*>(this)->getFirstNonPHIOrDbgOrLifetime(); + } + + /// getFirstInsertionPt - Returns an iterator to the first instruction in this + /// block that is suitable for inserting a non-PHI instruction. In particular, + /// it skips all PHIs and LandingPad instructions. + iterator getFirstInsertionPt(); + const_iterator getFirstInsertionPt() const { + return const_cast<BasicBlock*>(this)->getFirstInsertionPt(); + } + + /// removeFromParent - This method unlinks 'this' from the containing + /// function, but does not delete it. + /// + void removeFromParent(); + + /// eraseFromParent - This method unlinks 'this' from the containing function + /// and deletes it. + /// + void eraseFromParent(); + + /// moveBefore - Unlink this basic block from its current function and + /// insert it into the function that MovePos lives in, right before MovePos. + void moveBefore(BasicBlock *MovePos); + + /// moveAfter - Unlink this basic block from its current function and + /// insert it into the function that MovePos lives in, right after MovePos. + void moveAfter(BasicBlock *MovePos); + + + /// getSinglePredecessor - If this basic block has a single predecessor block, + /// return the block, otherwise return a null pointer. + BasicBlock *getSinglePredecessor(); + const BasicBlock *getSinglePredecessor() const { + return const_cast<BasicBlock*>(this)->getSinglePredecessor(); + } + + /// getUniquePredecessor - 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). + BasicBlock *getUniquePredecessor(); + const BasicBlock *getUniquePredecessor() const { + return const_cast<BasicBlock*>(this)->getUniquePredecessor(); + } + + //===--------------------------------------------------------------------===// + /// Instruction iterator methods + /// + inline iterator begin() { return InstList.begin(); } + inline const_iterator begin() const { return InstList.begin(); } + inline iterator end () { return InstList.end(); } + inline const_iterator end () const { return InstList.end(); } + + inline reverse_iterator rbegin() { return InstList.rbegin(); } + inline const_reverse_iterator rbegin() const { return InstList.rbegin(); } + inline reverse_iterator rend () { return InstList.rend(); } + inline const_reverse_iterator rend () const { return InstList.rend(); } + + inline size_t size() const { return InstList.size(); } + inline bool empty() const { return InstList.empty(); } + inline const Instruction &front() const { return InstList.front(); } + inline Instruction &front() { return InstList.front(); } + inline const Instruction &back() const { return InstList.back(); } + inline Instruction &back() { return InstList.back(); } + + /// getInstList() - Return the underlying instruction list container. You + /// need to access it directly if you want to modify it currently. + /// + const InstListType &getInstList() const { return InstList; } + InstListType &getInstList() { return InstList; } + + /// getSublistAccess() - returns pointer to member of instruction list + static iplist<Instruction> BasicBlock::*getSublistAccess(Instruction*) { + return &BasicBlock::InstList; + } + + /// getValueSymbolTable() - returns pointer to symbol table (if any) + ValueSymbolTable *getValueSymbolTable(); + + /// Methods for support type inquiry through isa, cast, and dyn_cast: + static inline bool classof(const Value *V) { + return V->getValueID() == Value::BasicBlockVal; + } + + /// dropAllReferences() - This function causes all the subinstructions to "let + /// go" of all references that they are maintaining. This allows one to + /// 'delete' a whole class at a time, even though there may be circular + /// references... first all references are dropped, and all use counts go to + /// zero. Then everything is delete'd for real. Note that no operations are + /// valid on an object that has "dropped all references", except operator + /// delete. + /// + void dropAllReferences(); + + /// removePredecessor - This method is used to notify a BasicBlock that the + /// specified Predecessor of the block is no longer able to reach it. This is + /// actually not used to update the Predecessor list, but is actually used to + /// update the PHI nodes that reside in the block. Note that this should be + /// called while the predecessor still refers to this block. + /// + void removePredecessor(BasicBlock *Pred, bool DontDeleteUselessPHIs = false); + + /// splitBasicBlock - 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 original BB, and the rest of the instructions in the BB are moved + /// to the new BB, including the old terminator. The newly formed BasicBlock + /// is returned. This function invalidates the specified 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). + /// + /// Also note that this doesn't preserve any passes. To split blocks while + /// keeping loop information consistent, use the SplitBlock utility function. + /// + BasicBlock *splitBasicBlock(iterator I, const Twine &BBName = ""); + + /// hasAddressTaken - returns true if there are any uses of this basic block + /// other than direct branches, switches, etc. to it. + bool hasAddressTaken() const { return getSubclassDataFromValue() != 0; } + + /// replaceSuccessorsPhiUsesWith - Update all phi nodes in all our successors + /// to refer to basic block New instead of to us. + void replaceSuccessorsPhiUsesWith(BasicBlock *New); + + /// isLandingPad - 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 isLandingPad() const; + + /// getLandingPadInst() - Return the landingpad instruction associated with + /// the landing pad. + LandingPadInst *getLandingPadInst(); + const LandingPadInst *getLandingPadInst() const; + +private: + /// AdjustBlockAddressRefCount - BasicBlock stores the number of BlockAddress + /// objects using it. This is almost always 0, sometimes one, possibly but + /// almost never 2, and inconceivably 3 or more. + void AdjustBlockAddressRefCount(int Amt) { + setValueSubclassData(getSubclassDataFromValue()+Amt); + assert((int)(signed char)getSubclassDataFromValue() >= 0 && + "Refcount wrap-around"); + } + // Shadow Value::setValueSubclassData with a private forwarding method so that + // any future subclasses cannot accidentally use it. + void setValueSubclassData(unsigned short D) { + Value::setValueSubclassData(D); + } +}; + +} // End llvm namespace + +#endif |