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+//===-- 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
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