1 //===-- llvm/CodeGen/MachineBasicBlock.h ------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Collect the sequence of machine instructions for a basic block.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_MACHINEBASICBLOCK_H
15 #define LLVM_CODEGEN_MACHINEBASICBLOCK_H
17 #include "llvm/CodeGen/MachineInstr.h"
18 #include "llvm/ADT/GraphTraits.h"
24 class MachineFunction;
30 struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> {
32 mutable ilist_half_node<MachineInstr> Sentinel;
34 // this is only set by the MachineBasicBlock owning the LiveList
35 friend class MachineBasicBlock;
36 MachineBasicBlock* Parent;
39 MachineInstr *createSentinel() const {
40 return static_cast<MachineInstr*>(&Sentinel);
42 void destroySentinel(MachineInstr *) const {}
44 MachineInstr *provideInitialHead() const { return createSentinel(); }
45 MachineInstr *ensureHead(MachineInstr*) const { return createSentinel(); }
46 static void noteHead(MachineInstr*, MachineInstr*) {}
48 void addNodeToList(MachineInstr* N);
49 void removeNodeFromList(MachineInstr* N);
50 void transferNodesFromList(ilist_traits &SrcTraits,
51 ilist_iterator<MachineInstr> first,
52 ilist_iterator<MachineInstr> last);
53 void deleteNode(MachineInstr *N);
55 void createNode(const MachineInstr &);
58 class MachineBasicBlock : public ilist_node<MachineBasicBlock> {
59 typedef ilist<MachineInstr> Instructions;
63 MachineFunction *xParent;
65 /// Predecessors/Successors - Keep track of the predecessor / successor
67 std::vector<MachineBasicBlock *> Predecessors;
68 std::vector<MachineBasicBlock *> Successors;
70 /// LiveIns - Keep track of the physical registers that are livein of
72 std::vector<unsigned> LiveIns;
74 /// Alignment - Alignment of the basic block. Zero if the basic block does
75 /// not need to be aligned.
78 /// IsLandingPad - Indicate that this basic block is entered via an
79 /// exception handler.
82 /// AddressTaken - Indicate that this basic block is potentially the
83 /// target of an indirect branch.
86 // Intrusive list support
87 MachineBasicBlock() {}
89 explicit MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb);
93 // MachineBasicBlocks are allocated and owned by MachineFunction.
94 friend class MachineFunction;
97 /// getBasicBlock - Return the LLVM basic block that this instance
98 /// corresponded to originally. Note that this may be NULL if this instance
99 /// does not correspond directly to an LLVM basic block.
101 const BasicBlock *getBasicBlock() const { return BB; }
103 /// getName - Return the name of the corresponding LLVM basic block, or
105 StringRef getName() const;
107 /// hasAddressTaken - Test whether this block is potentially the target
108 /// of an indirect branch.
109 bool hasAddressTaken() const { return AddressTaken; }
111 /// setHasAddressTaken - Set this block to reflect that it potentially
112 /// is the target of an indirect branch.
113 void setHasAddressTaken() { AddressTaken = true; }
115 /// getParent - Return the MachineFunction containing this basic block.
117 const MachineFunction *getParent() const { return xParent; }
118 MachineFunction *getParent() { return xParent; }
120 typedef Instructions::iterator iterator;
121 typedef Instructions::const_iterator const_iterator;
122 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
123 typedef std::reverse_iterator<iterator> reverse_iterator;
125 unsigned size() const { return (unsigned)Insts.size(); }
126 bool empty() const { return Insts.empty(); }
128 MachineInstr& front() { return Insts.front(); }
129 MachineInstr& back() { return Insts.back(); }
130 const MachineInstr& front() const { return Insts.front(); }
131 const MachineInstr& back() const { return Insts.back(); }
133 iterator begin() { return Insts.begin(); }
134 const_iterator begin() const { return Insts.begin(); }
135 iterator end() { return Insts.end(); }
136 const_iterator end() const { return Insts.end(); }
137 reverse_iterator rbegin() { return Insts.rbegin(); }
138 const_reverse_iterator rbegin() const { return Insts.rbegin(); }
139 reverse_iterator rend () { return Insts.rend(); }
140 const_reverse_iterator rend () const { return Insts.rend(); }
142 // Machine-CFG iterators
143 typedef std::vector<MachineBasicBlock *>::iterator pred_iterator;
144 typedef std::vector<MachineBasicBlock *>::const_iterator const_pred_iterator;
145 typedef std::vector<MachineBasicBlock *>::iterator succ_iterator;
146 typedef std::vector<MachineBasicBlock *>::const_iterator const_succ_iterator;
147 typedef std::vector<MachineBasicBlock *>::reverse_iterator
148 pred_reverse_iterator;
149 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator
150 const_pred_reverse_iterator;
151 typedef std::vector<MachineBasicBlock *>::reverse_iterator
152 succ_reverse_iterator;
153 typedef std::vector<MachineBasicBlock *>::const_reverse_iterator
154 const_succ_reverse_iterator;
156 pred_iterator pred_begin() { return Predecessors.begin(); }
157 const_pred_iterator pred_begin() const { return Predecessors.begin(); }
158 pred_iterator pred_end() { return Predecessors.end(); }
159 const_pred_iterator pred_end() const { return Predecessors.end(); }
160 pred_reverse_iterator pred_rbegin()
161 { return Predecessors.rbegin();}
162 const_pred_reverse_iterator pred_rbegin() const
163 { return Predecessors.rbegin();}
164 pred_reverse_iterator pred_rend()
165 { return Predecessors.rend(); }
166 const_pred_reverse_iterator pred_rend() const
167 { return Predecessors.rend(); }
168 unsigned pred_size() const {
169 return (unsigned)Predecessors.size();
171 bool pred_empty() const { return Predecessors.empty(); }
172 succ_iterator succ_begin() { return Successors.begin(); }
173 const_succ_iterator succ_begin() const { return Successors.begin(); }
174 succ_iterator succ_end() { return Successors.end(); }
175 const_succ_iterator succ_end() const { return Successors.end(); }
176 succ_reverse_iterator succ_rbegin()
177 { return Successors.rbegin(); }
178 const_succ_reverse_iterator succ_rbegin() const
179 { return Successors.rbegin(); }
180 succ_reverse_iterator succ_rend()
181 { return Successors.rend(); }
182 const_succ_reverse_iterator succ_rend() const
183 { return Successors.rend(); }
184 unsigned succ_size() const {
185 return (unsigned)Successors.size();
187 bool succ_empty() const { return Successors.empty(); }
189 // LiveIn management methods.
191 /// addLiveIn - Add the specified register as a live in. Note that it
192 /// is an error to add the same register to the same set more than once.
193 void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); }
195 /// removeLiveIn - Remove the specified register from the live in set.
197 void removeLiveIn(unsigned Reg);
199 /// isLiveIn - Return true if the specified register is in the live in set.
201 bool isLiveIn(unsigned Reg) const;
203 // Iteration support for live in sets. These sets are kept in sorted
204 // order by their register number.
205 typedef std::vector<unsigned>::const_iterator livein_iterator;
206 livein_iterator livein_begin() const { return LiveIns.begin(); }
207 livein_iterator livein_end() const { return LiveIns.end(); }
208 bool livein_empty() const { return LiveIns.empty(); }
210 /// getAlignment - Return alignment of the basic block.
212 unsigned getAlignment() const { return Alignment; }
214 /// setAlignment - Set alignment of the basic block.
216 void setAlignment(unsigned Align) { Alignment = Align; }
218 /// isLandingPad - Returns true if the block is a landing pad. That is
219 /// this basic block is entered via an exception handler.
220 bool isLandingPad() const { return IsLandingPad; }
222 /// setIsLandingPad - Indicates the block is a landing pad. That is
223 /// this basic block is entered via an exception handler.
224 void setIsLandingPad() { IsLandingPad = true; }
226 // Code Layout methods.
228 /// moveBefore/moveAfter - move 'this' block before or after the specified
229 /// block. This only moves the block, it does not modify the CFG or adjust
230 /// potential fall-throughs at the end of the block.
231 void moveBefore(MachineBasicBlock *NewAfter);
232 void moveAfter(MachineBasicBlock *NewBefore);
234 /// updateTerminator - Update the terminator instructions in block to account
235 /// for changes to the layout. If the block previously used a fallthrough,
236 /// it may now need a branch, and if it previously used branching it may now
237 /// be able to use a fallthrough.
238 void updateTerminator();
240 // Machine-CFG mutators
242 /// addSuccessor - Add succ as a successor of this MachineBasicBlock.
243 /// The Predecessors list of succ is automatically updated.
245 void addSuccessor(MachineBasicBlock *succ);
247 /// removeSuccessor - Remove successor from the successors list of this
248 /// MachineBasicBlock. The Predecessors list of succ is automatically updated.
250 void removeSuccessor(MachineBasicBlock *succ);
252 /// removeSuccessor - Remove specified successor from the successors list of
253 /// this MachineBasicBlock. The Predecessors list of succ is automatically
254 /// updated. Return the iterator to the element after the one removed.
256 succ_iterator removeSuccessor(succ_iterator I);
258 /// transferSuccessors - Transfers all the successors from MBB to this
259 /// machine basic block (i.e., copies all the successors fromMBB and
260 /// remove all the successors from fromMBB).
261 void transferSuccessors(MachineBasicBlock *fromMBB);
263 /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as
264 /// in transferSuccessors, and update PHI operands in the successor blocks
265 /// which refer to fromMBB to refer to this.
266 void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB);
268 /// isSuccessor - Return true if the specified MBB is a successor of this
270 bool isSuccessor(const MachineBasicBlock *MBB) const;
272 /// isLayoutSuccessor - Return true if the specified MBB will be emitted
273 /// immediately after this block, such that if this block exits by
274 /// falling through, control will transfer to the specified MBB. Note
275 /// that MBB need not be a successor at all, for example if this block
276 /// ends with an unconditional branch to some other block.
277 bool isLayoutSuccessor(const MachineBasicBlock *MBB) const;
279 /// canFallThrough - Return true if the block can implicitly transfer
280 /// control to the block after it by falling off the end of it. This should
281 /// return false if it can reach the block after it, but it uses an explicit
282 /// branch to do so (e.g., a table jump). True is a conservative answer.
283 bool canFallThrough();
285 /// Returns a pointer to the first instructon in this block that is not a
286 /// PHINode instruction. When adding instruction to the beginning of the
287 /// basic block, they should be added before the returned value, not before
288 /// the first instruction, which might be PHI.
289 /// Returns end() is there's no non-PHI instruction.
290 iterator getFirstNonPHI();
292 /// getFirstTerminator - returns an iterator to the first terminator
293 /// instruction of this basic block. If a terminator does not exist,
295 iterator getFirstTerminator();
297 /// SplitCriticalEdge - Split the critical edge from this block to the
298 /// given successor block, and return the newly created block, or null
299 /// if splitting is not possible.
301 /// This function updates LiveVariables, MachineDominatorTree, and
302 /// MachineLoopInfo, as applicable.
303 MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P);
305 void pop_front() { Insts.pop_front(); }
306 void pop_back() { Insts.pop_back(); }
307 void push_back(MachineInstr *MI) { Insts.push_back(MI); }
308 template<typename IT>
309 void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); }
310 iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); }
311 iterator insertAfter(iterator I, MachineInstr *M) {
312 return Insts.insertAfter(I, M);
315 // erase - Remove the specified element or range from the instruction list.
316 // These functions delete any instructions removed.
318 iterator erase(iterator I) { return Insts.erase(I); }
319 iterator erase(iterator I, iterator E) { return Insts.erase(I, E); }
320 MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); }
321 void clear() { Insts.clear(); }
323 /// splice - Take an instruction from MBB 'Other' at the position From,
324 /// and insert it into this MBB right before 'where'.
325 void splice(iterator where, MachineBasicBlock *Other, iterator From) {
326 Insts.splice(where, Other->Insts, From);
329 /// splice - Take a block of instructions from MBB 'Other' in the range [From,
330 /// To), and insert them into this MBB right before 'where'.
331 void splice(iterator where, MachineBasicBlock *Other, iterator From,
333 Insts.splice(where, Other->Insts, From, To);
336 /// removeFromParent - This method unlinks 'this' from the containing
337 /// function, and returns it, but does not delete it.
338 MachineBasicBlock *removeFromParent();
340 /// eraseFromParent - This method unlinks 'this' from the containing
341 /// function and deletes it.
342 void eraseFromParent();
344 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
345 /// 'Old', change the code and CFG so that it branches to 'New' instead.
346 void ReplaceUsesOfBlockWith(MachineBasicBlock *Old, MachineBasicBlock *New);
348 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in
349 /// the CFG to be inserted. If we have proven that MBB can only branch to
350 /// DestA and DestB, remove any other MBB successors from the CFG. DestA and
351 /// DestB can be null. Besides DestA and DestB, retain other edges leading
352 /// to LandingPads (currently there can be only one; we don't check or require
353 /// that here). Note it is possible that DestA and/or DestB are LandingPads.
354 bool CorrectExtraCFGEdges(MachineBasicBlock *DestA,
355 MachineBasicBlock *DestB,
358 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
359 /// any DBG_VALUE instructions. Return UnknownLoc if there is none.
360 DebugLoc findDebugLoc(MachineBasicBlock::iterator &MBBI);
362 // Debugging methods.
364 void print(raw_ostream &OS) const;
366 /// getNumber - MachineBasicBlocks are uniquely numbered at the function
367 /// level, unless they're not in a MachineFunction yet, in which case this
370 int getNumber() const { return Number; }
371 void setNumber(int N) { Number = N; }
373 /// getSymbol - Return the MCSymbol for this basic block.
375 MCSymbol *getSymbol() const;
377 private: // Methods used to maintain doubly linked list of blocks...
378 friend struct ilist_traits<MachineBasicBlock>;
380 // Machine-CFG mutators
382 /// addPredecessor - Remove pred as a predecessor of this MachineBasicBlock.
383 /// Don't do this unless you know what you're doing, because it doesn't
384 /// update pred's successors list. Use pred->addSuccessor instead.
386 void addPredecessor(MachineBasicBlock *pred);
388 /// removePredecessor - Remove pred as a predecessor of this
389 /// MachineBasicBlock. Don't do this unless you know what you're
390 /// doing, because it doesn't update pred's successors list. Use
391 /// pred->removeSuccessor instead.
393 void removePredecessor(MachineBasicBlock *pred);
396 raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB);
398 void WriteAsOperand(raw_ostream &, const MachineBasicBlock*, bool t);
400 //===--------------------------------------------------------------------===//
401 // GraphTraits specializations for machine basic block graphs (machine-CFGs)
402 //===--------------------------------------------------------------------===//
404 // Provide specializations of GraphTraits to be able to treat a
405 // MachineFunction as a graph of MachineBasicBlocks...
408 template <> struct GraphTraits<MachineBasicBlock *> {
409 typedef MachineBasicBlock NodeType;
410 typedef MachineBasicBlock::succ_iterator ChildIteratorType;
412 static NodeType *getEntryNode(MachineBasicBlock *BB) { return BB; }
413 static inline ChildIteratorType child_begin(NodeType *N) {
414 return N->succ_begin();
416 static inline ChildIteratorType child_end(NodeType *N) {
417 return N->succ_end();
421 template <> struct GraphTraits<const MachineBasicBlock *> {
422 typedef const MachineBasicBlock NodeType;
423 typedef MachineBasicBlock::const_succ_iterator ChildIteratorType;
425 static NodeType *getEntryNode(const MachineBasicBlock *BB) { return BB; }
426 static inline ChildIteratorType child_begin(NodeType *N) {
427 return N->succ_begin();
429 static inline ChildIteratorType child_end(NodeType *N) {
430 return N->succ_end();
434 // Provide specializations of GraphTraits to be able to treat a
435 // MachineFunction as a graph of MachineBasicBlocks... and to walk it
436 // in inverse order. Inverse order for a function is considered
437 // to be when traversing the predecessor edges of a MBB
438 // instead of the successor edges.
440 template <> struct GraphTraits<Inverse<MachineBasicBlock*> > {
441 typedef MachineBasicBlock NodeType;
442 typedef MachineBasicBlock::pred_iterator ChildIteratorType;
443 static NodeType *getEntryNode(Inverse<MachineBasicBlock *> G) {
446 static inline ChildIteratorType child_begin(NodeType *N) {
447 return N->pred_begin();
449 static inline ChildIteratorType child_end(NodeType *N) {
450 return N->pred_end();
454 template <> struct GraphTraits<Inverse<const MachineBasicBlock*> > {
455 typedef const MachineBasicBlock NodeType;
456 typedef MachineBasicBlock::const_pred_iterator ChildIteratorType;
457 static NodeType *getEntryNode(Inverse<const MachineBasicBlock*> G) {
460 static inline ChildIteratorType child_begin(NodeType *N) {
461 return N->pred_begin();
463 static inline ChildIteratorType child_end(NodeType *N) {
464 return N->pred_end();
468 } // End llvm namespace