//===----------------------------------------------------------------------===//
//
//
-// 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
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;
BasicBlock *getPrev() { return Prev; }
const BasicBlock *getPrev() const { return Prev; }
+ /// use_back - Specialize the methods defined in Value, as we know that an
+ /// BasicBlock can only be used by Instructions (specifically PHI and terms).
+ 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;
-
+
+ /// 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.
///
///
void eraseFromParent();
- /// moveBefore - Unlink this instruction from its current function and
- /// insert it into the function that MovePos lives in, right before
- /// MovePos.
+ /// 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.
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;
}