//===-- 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...
-//
-///===---------------------------------------------------------------------===//
-//
-// 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.
//===----------------------------------------------------------------------===//
#ifndef LLVM_BASICBLOCK_H
template<> struct ilist_traits<Instruction>
: public SymbolTableListTraits<Instruction, BasicBlock, Function> {
- // createSentinal is used to create a node that marks the end of the list...
- static Instruction *createSentinal();
- static void destroySentinal(Instruction *I) { delete I; }
+ // createSentinel is used to create a node that marks the end of the list...
+ static Instruction *createSentinel();
+ static void destroySentinel(Instruction *I) { delete I; }
static iplist<Instruction> &getList(BasicBlock *BB);
};
+/// 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:
typedef iplist<Instruction> InstListType;
/// 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
BasicBlock *InsertBefore = 0);
~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(); }
TerminatorInst *getTerminator();
const TerminatorInst *const 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();
+
/// removeFromParent - This method unlinks 'this' from the containing
/// function, but does not delete it.
///
/// and deletes it.
///
void eraseFromParent();
-
-
+
+ /// moveBefore - Unlink this instruction from its current function and
+ /// insert it into the function that MovePos lives in, right before
+ /// MovePos.
+ void moveBefore(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();
+ }
//===--------------------------------------------------------------------===//
/// 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 size_t size() const { return InstList.size(); }
inline bool empty() const { return InstList.empty(); }
inline const Instruction &front() const { return InstList.front(); }
void print(std::ostream &OS, AssemblyAnnotationWriter *AAW) const;
/// 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;
}
/// '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).