//===-- llvm/BasicBlock.h - Represent a basic block in the VM ---*- C++ -*-===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-//
-// This file contains the declaration of the BasicBlock class, which represents
-// a single basic block in the VM.
//
-// Note that basic blocks themselves are Value's, because they are referenced
-// by instructions like branches and can go in switch tables and stuff...
+// The LLVM Compiler Infrastructure
//
-///===---------------------------------------------------------------------===//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
-// Note that well formed basic blocks are formed of a list of instructions
-// followed by a single TerminatorInst instruction. TerminatorInst's may not
-// occur in the middle of basic blocks, and must terminate the blocks.
+//===----------------------------------------------------------------------===//
//
-// This code allows malformed basic blocks to occur, because it may be useful
-// in the intermediate stage modification to a program.
+// This file contains the declaration of the BasicBlock class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Instruction.h"
#include "llvm/SymbolTableListTraits.h"
-#include "Support/ilist"
+#include "llvm/ADT/ilist.h"
+#include "llvm/Support/DataTypes.h"
namespace llvm {
class TerminatorInst;
-template <class _Term, class _BB> class SuccIterator; // Successor Iterator
-template <class _Ptr, class _USE_iterator> class PredIterator;
+class LLVMContext;
template<> struct ilist_traits<Instruction>
- : public SymbolTableListTraits<Instruction, BasicBlock, Function> {
- // createNode is used to create a node that marks the end of the list...
- static Instruction *createNode();
- static iplist<Instruction> &getList(BasicBlock *BB);
+ : 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_node<Instruction> Sentinel;
};
-struct BasicBlock : public Value { // Basic blocks are data objects also
+/// 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> {
+
+public:
typedef iplist<Instruction> InstListType;
-private :
+private:
InstListType InstList;
- BasicBlock *Prev, *Next; // Next and Prev links for our intrusive linked list
+ Function *Parent;
void setParent(Function *parent);
- void setNext(BasicBlock *N) { Next = N; }
- void setPrev(BasicBlock *N) { Prev = N; }
- friend class SymbolTableListTraits<BasicBlock, Function, Function>;
+ friend class SymbolTableListTraits<BasicBlock, Function>;
BasicBlock(const BasicBlock &); // Do not implement
void operator=(const BasicBlock &); // Do not implement
-public:
- /// Instruction iterators...
- typedef InstListType::iterator iterator;
- typedef InstListType::const_iterator const_iterator;
- typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
- typedef std::reverse_iterator<iterator> reverse_iterator;
-
/// 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.
///
- /// BasicBlock ctor - If the InsertBefore parameter is specified, the basic
- /// block is automatically inserted right before the specified block.
- ///
- BasicBlock(const std::string &Name = "", Function *Parent = 0,
- BasicBlock *InsertBefore = 0);
+ explicit BasicBlock(LLVMContext &C, const Twine &Name = "",
+ Function *Parent = 0, BasicBlock *InsertBefore = 0);
+public:
+ /// getContext - Get the context in which this basic block lives,
+ /// or null if it is not currently attached to a function.
+ LLVMContext &getContext() const;
+
+ /// Instruction iterators...
+ typedef InstListType::iterator iterator;
+ typedef InstListType::const_iterator const_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();
- // Specialize setName to take care of symbol table majik
- virtual void setName(const std::string &name, SymbolTable *ST = 0);
-
/// getParent - Return the enclosing method, or null if none
///
- const Function *getParent() const { return InstList.getParent(); }
- Function *getParent() { return InstList.getParent(); }
-
- // getNext/Prev - Return the next or previous basic block in the list.
- BasicBlock *getNext() { return Next; }
- const BasicBlock *getNext() const { return Next; }
- BasicBlock *getPrev() { return Prev; }
- const BasicBlock *getPrev() const { return Prev; }
-
+ const Function *getParent() const { return Parent; }
+ Function *getParent() { return Parent; }
+
+ /// use_back - Specialize the methods defined in Value, as we know that an
+ /// BasicBlock can only be used by Instructions (specifically PHI nodes and
+ /// terminators).
+ Instruction *use_back() { return cast<Instruction>(*use_begin());}
+ const Instruction *use_back() const { return cast<Instruction>(*use_begin());}
+
/// 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 *const getTerminator() const;
+ 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();
+ }
+
+ /// 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 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 unsigned size() const { return InstList.size(); }
+ 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(); }
+ 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; }
- virtual void print(std::ostream &OS) const { print(OS, 0); }
- void print(std::ostream &OS, AssemblyAnnotationWriter *AAW) const;
+ /// 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 BasicBlock *BB) { return true; }
+ static inline bool classof(const BasicBlock *) { return true; }
static inline bool classof(const Value *V) {
- return V->getValueType() == Value::BasicBlockVal;
+ return V->getValueID() == Value::BasicBlockVal;
}
/// dropAllReferences() - This function causes all the subinstructions to "let
/// '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
+ /// 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
+ /// 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);
+ 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 new 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.
+ /// 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
+ /// 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 *splitBasicBlock(iterator I, const std::string &BBName = "");
+ BasicBlock *splitBasicBlock(iterator I, const Twine &BBName = "");
};
} // End llvm namespace
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