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llvm/Support/CFG.h git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1747 91177308-0d34-0410-b5e6-96231b3b80d8
156 lines
6.7 KiB
C++
156 lines
6.7 KiB
C++
//===-- llvm/BasicBlock.h - Represent a basic block in the VM ----*- C++ -*--=//
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//
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// This file contains the declaration of the BasicBlock class, which represents
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// a single basic block in the VM.
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//
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// Note that basic blocks themselves are Value's, because they are referenced
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// by instructions like branches and can go in switch tables and stuff...
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//
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//===----------------------------------------------------------------------===//
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//
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// Note that well formed basic blocks are formed of a list of instructions
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// followed by a single TerminatorInst instruction. TerminatorInst's may not
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// occur in the middle of basic blocks, and must terminate the blocks.
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//
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// This code allows malformed basic blocks to occur, because it may be useful
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// in the intermediate stage of analysis or modification of a program.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_BASICBLOCK_H
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#define LLVM_BASICBLOCK_H
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#include "llvm/ValueHolder.h"
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#include "llvm/Value.h"
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class Instruction;
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class Method;
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class TerminatorInst;
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class MachineCodeForBasicBlock;
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template <class _Term, class _BB> class SuccIterator; // Successor Iterator
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template <class _Ptr, class _USE_iterator> class PredIterator;
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class BasicBlock : public Value { // Basic blocks are data objects also
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public:
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typedef ValueHolder<Instruction, BasicBlock, Method> InstListType;
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private :
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InstListType InstList;
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MachineCodeForBasicBlock* machineInstrVec;
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friend class ValueHolder<BasicBlock,Method,Method>;
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void setParent(Method *parent);
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public:
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// Instruction iterators...
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typedef InstListType::iterator iterator;
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typedef InstListType::const_iterator const_iterator;
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typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
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typedef std::reverse_iterator<iterator> reverse_iterator;
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// Ctor, dtor
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BasicBlock(const std::string &Name = "", Method *Parent = 0);
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~BasicBlock();
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// Specialize setName to take care of symbol table majik
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virtual void setName(const std::string &name, SymbolTable *ST = 0);
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// getParent - Return the enclosing method, or null if none
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const Method *getParent() const { return InstList.getParent(); }
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Method *getParent() { return InstList.getParent(); }
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// getTerminator() - If this is a well formed basic block, then this returns
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// a pointer to the terminator instruction. If it is not, then you get a null
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// pointer back.
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//
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TerminatorInst *getTerminator();
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const TerminatorInst *const getTerminator() const;
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// Machine code accessor...
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inline MachineCodeForBasicBlock& getMachineInstrVec() const {
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return *machineInstrVec;
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}
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// Provide a scoped predecessor and successor iterator
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typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator;
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typedef PredIterator<const BasicBlock,
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Value::use_const_iterator> pred_const_iterator;
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typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
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typedef SuccIterator<const TerminatorInst*,
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const BasicBlock> succ_const_iterator;
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//===--------------------------------------------------------------------===//
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// Instruction iterator methods
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//
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inline iterator begin() { return InstList.begin(); }
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inline const_iterator begin() const { return InstList.begin(); }
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inline iterator end () { return InstList.end(); }
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inline const_iterator end () const { return InstList.end(); }
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inline reverse_iterator rbegin() { return InstList.rbegin(); }
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inline const_reverse_iterator rbegin() const { return InstList.rbegin(); }
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inline reverse_iterator rend () { return InstList.rend(); }
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inline const_reverse_iterator rend () const { return InstList.rend(); }
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inline unsigned size() const { return InstList.size(); }
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inline bool empty() const { return InstList.empty(); }
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inline const Instruction *front() const { return InstList.front(); }
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inline Instruction *front() { return InstList.front(); }
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inline const Instruction *back() const { return InstList.back(); }
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inline Instruction *back() { return InstList.back(); }
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// getInstList() - Return the underlying instruction list container. You need
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// to access it directly if you want to modify it currently.
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//
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const InstListType &getInstList() const { return InstList; }
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InstListType &getInstList() { return InstList; }
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// Methods for support type inquiry through isa, cast, and dyn_cast:
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static inline bool classof(const BasicBlock *BB) { return true; }
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static inline bool classof(const Value *V) {
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return V->getValueType() == Value::BasicBlockVal;
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}
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// hasConstantReferences() - This predicate is true if there is a
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// reference to this basic block in the constant pool for this method. For
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// example, if a block is reached through a switch table, that table resides
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// in the constant pool, and the basic block is reference from it.
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//
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bool hasConstantReferences() const;
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// dropAllReferences() - This function causes all the subinstructions to "let
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// go" of all references that they are maintaining. This allows one to
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// 'delete' a whole class at a time, even though there may be circular
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// references... first all references are dropped, and all use counts go to
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// zero. Then everything is delete'd for real. Note that no operations are
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// valid on an object that has "dropped all references", except operator
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// delete.
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//
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void dropAllReferences();
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// removePredecessor - This method is used to notify a BasicBlock that the
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// specified Predecessor of the block is no longer able to reach it. This is
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// actually not used to update the Predecessor list, but is actually used to
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// update the PHI nodes that reside in the block. Note that this should be
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// called while the predecessor still refers to this block.
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//
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void removePredecessor(BasicBlock *Pred);
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// splitBasicBlock - This splits a basic block into two at the specified
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// instruction. Note that all instructions BEFORE the specified iterator stay
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// as part of the original basic block, an unconditional branch is added to
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// the new BB, and the rest of the instructions in the BB are moved to the new
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// BB, including the old terminator. The newly formed BasicBlock is returned.
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// This function invalidates the specified iterator.
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//
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// Note that this only works on well formed basic blocks (must have a
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// terminator), and 'I' must not be the end of instruction list (which would
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// cause a degenerate basic block to be formed, having a terminator inside of
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// the basic block).
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//
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BasicBlock *splitBasicBlock(iterator I);
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};
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#endif
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