-//===-- llvm/BasicBlock.h - Represent a basic block in the VM ----*- C++ -*--=//
+//===-- llvm/BasicBlock.h - Represent a basic block in the VM ---*- C++ -*-===//
//
-// This file contains the declaration of the BasicBlock class, which represents
-// a single basic block in the VM.
+// The LLVM Compiler Infrastructure
//
-// Note that basic blocks themselves are Def's, because they are referenced
-// by instructions like branches and can go in switch tables and stuff...
-//
-// This may see wierd at first, but it's really pretty cool. :)
+// 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 of analysis or modification of a program.
+// This file contains the declaration of the BasicBlock class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_BASICBLOCK_H
#define LLVM_BASICBLOCK_H
-#include "llvm/Value.h" // Get the definition of Value
-#include "llvm/ValueHolder.h"
-#include "llvm/CFGdecls.h"
+#include "llvm/Instruction.h"
+#include "llvm/SymbolTableListTraits.h"
+#include "llvm/ADT/ilist.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
-class Instruction;
-class Method;
class TerminatorInst;
-class BasicBlock : public Value { // Basic blocks are data objects also
+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*) {}
+
+ static iplist<Instruction> &getList(BasicBlock *BB);
+ static ValueSymbolTable *getSymTab(BasicBlock *ItemParent);
+ static int getListOffset();
+private:
+ mutable ilist_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> {
+
public:
- typedef ValueHolder<Instruction, BasicBlock, Method> InstListType;
-private :
+ typedef iplist<Instruction> InstListType;
+private:
InstListType InstList;
+ Function *Parent;
- friend class ValueHolder<BasicBlock,Method,Method>;
- void setParent(Method *parent);
+ void setParent(Function *parent);
+ friend class SymbolTableListTraits<BasicBlock, Function>;
+ BasicBlock(const BasicBlock &); // Do not implement
+ void operator=(const BasicBlock &); // Do not implement
+
+ /// 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(const std::string &Name = "", Function *Parent = 0,
+ BasicBlock *InsertBefore = 0);
public:
- // Instruction iterators...
- typedef InstListType::iterator iterator;
- typedef InstListType::const_iterator const_iterator;
- typedef reverse_iterator<const_iterator> const_reverse_iterator;
- typedef reverse_iterator<iterator> reverse_iterator;
-
- typedef cfg::succ_iterator succ_iterator; // Include CFG.h to use these
- typedef cfg::pred_iterator pred_iterator;
- typedef cfg::succ_const_iterator succ_const_iterator;
- typedef cfg::pred_const_iterator pred_const_iterator;
-
- BasicBlock(const string &Name = "", Method *Parent = 0);
+ /// 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(const std::string &Name = "", Function *Parent = 0,
+ BasicBlock *InsertBefore = 0) {
+ return new BasicBlock(Name, Parent, InsertBefore);
+ }
~BasicBlock();
- // Specialize setName to take care of symbol table majik
- virtual void setName(const string &name);
-
- const Method *getParent() const { return InstList.getParent(); }
- Method *getParent() { return InstList.getParent(); }
-
- // 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.
- //
+ /// getParent - Return the enclosing method, or null if none
+ ///
+ 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
+ /// 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 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(); }
-
- // getInstList() - Return the underlying instruction list container. You need
- // to access it directly if you want to modify it currently.
- //
+ 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; }
- // hasConstantPoolReferences() - This predicate is true if there is a
- // reference to this basic block in the constant pool for this method. For
- // example, if a block is reached through a switch table, that table resides
- // in the constant pool, and the basic block is reference from it.
- //
- bool hasConstantPoolReferences() const;
-
- // 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.
- //
+ /// Methods for support type inquiry through isa, cast, and dyn_cast:
+ static inline bool classof(const BasicBlock *) { return true; }
+ 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);
-
- // 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.
- //
- // 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);
+ /// 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).
+ ///
+ BasicBlock *splitBasicBlock(iterator I, const std::string &BBName = "");
+
+
+ static unsigned getInstListOffset() {
+ BasicBlock *Obj = 0;
+ return unsigned(reinterpret_cast<uintptr_t>(&Obj->InstList));
+ }
};
+inline int
+ilist_traits<Instruction>::getListOffset() {
+ return BasicBlock::getInstListOffset();
+}
+
+} // End llvm namespace
+
#endif
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