1
//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- 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
// This file defines the LoopInfo class that is used to identify natural loops
11
// and determine the loop depth of various nodes of the CFG. A natural loop
12
// has exactly one entry-point, which is called the header. Note that natural
13
// loops may actually be several loops that share the same header node.
15
// This analysis calculates the nesting structure of loops in a function. For
16
// each natural loop identified, this analysis identifies natural loops
17
// contained entirely within the loop and the basic blocks the make up the loop.
19
// It can calculate on the fly various bits of information, for example:
21
// * whether there is a preheader for the loop
22
// * the number of back edges to the header
23
// * whether or not a particular block branches out of the loop
24
// * the successor blocks of the loop
29
//===----------------------------------------------------------------------===//
31
#ifndef LLVM_ANALYSIS_LOOP_INFO_H
32
#define LLVM_ANALYSIS_LOOP_INFO_H
34
#include "llvm/Pass.h"
35
#include "llvm/ADT/DepthFirstIterator.h"
36
#include "llvm/ADT/GraphTraits.h"
37
#include "llvm/ADT/SmallVector.h"
38
#include "llvm/Analysis/Dominators.h"
39
#include "llvm/Support/CFG.h"
40
#include "llvm/Support/raw_ostream.h"
46
static void RemoveFromVector(std::vector<T*> &V, T *N) {
47
typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
48
assert(I != V.end() && "N is not in this list!");
55
template<class N, class M> class LoopInfoBase;
56
template<class N, class M> class LoopBase;
58
//===----------------------------------------------------------------------===//
59
/// LoopBase class - Instances of this class are used to represent loops that
60
/// are detected in the flow graph
62
template<class BlockT, class LoopT>
65
// SubLoops - Loops contained entirely within this one.
66
std::vector<LoopT *> SubLoops;
68
// Blocks - The list of blocks in this loop. First entry is the header node.
69
std::vector<BlockT*> Blocks;
72
LoopBase(const LoopBase<BlockT, LoopT> &);
74
const LoopBase<BlockT, LoopT>&operator=(const LoopBase<BlockT, LoopT> &);
76
/// Loop ctor - This creates an empty loop.
77
LoopBase() : ParentLoop(0) {}
79
for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
83
/// getLoopDepth - Return the nesting level of this loop. An outer-most
84
/// loop has depth 1, for consistency with loop depth values used for basic
85
/// blocks, where depth 0 is used for blocks not inside any loops.
86
unsigned getLoopDepth() const {
88
for (const LoopT *CurLoop = ParentLoop; CurLoop;
89
CurLoop = CurLoop->ParentLoop)
93
BlockT *getHeader() const { return Blocks.front(); }
94
LoopT *getParentLoop() const { return ParentLoop; }
96
/// contains - Return true if the specified loop is contained within in
99
bool contains(const LoopT *L) const {
100
if (L == this) return true;
101
if (L == 0) return false;
102
return contains(L->getParentLoop());
105
/// contains - Return true if the specified basic block is in this loop.
107
bool contains(const BlockT *BB) const {
108
return std::find(block_begin(), block_end(), BB) != block_end();
111
/// contains - Return true if the specified instruction is in this loop.
113
template<class InstT>
114
bool contains(const InstT *Inst) const {
115
return contains(Inst->getParent());
118
/// iterator/begin/end - Return the loops contained entirely within this loop.
120
const std::vector<LoopT *> &getSubLoops() const { return SubLoops; }
121
typedef typename std::vector<LoopT *>::const_iterator iterator;
122
iterator begin() const { return SubLoops.begin(); }
123
iterator end() const { return SubLoops.end(); }
124
bool empty() const { return SubLoops.empty(); }
126
/// getBlocks - Get a list of the basic blocks which make up this loop.
128
const std::vector<BlockT*> &getBlocks() const { return Blocks; }
129
typedef typename std::vector<BlockT*>::const_iterator block_iterator;
130
block_iterator block_begin() const { return Blocks.begin(); }
131
block_iterator block_end() const { return Blocks.end(); }
133
/// isLoopExiting - True if terminator in the block can branch to another
134
/// block that is outside of the current loop.
136
bool isLoopExiting(const BlockT *BB) const {
137
typedef GraphTraits<BlockT*> BlockTraits;
138
for (typename BlockTraits::ChildIteratorType SI =
139
BlockTraits::child_begin(const_cast<BlockT*>(BB)),
140
SE = BlockTraits::child_end(const_cast<BlockT*>(BB)); SI != SE; ++SI) {
147
/// getNumBackEdges - Calculate the number of back edges to the loop header
149
unsigned getNumBackEdges() const {
150
unsigned NumBackEdges = 0;
151
BlockT *H = getHeader();
153
typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
154
for (typename InvBlockTraits::ChildIteratorType I =
155
InvBlockTraits::child_begin(const_cast<BlockT*>(H)),
156
E = InvBlockTraits::child_end(const_cast<BlockT*>(H)); I != E; ++I)
163
//===--------------------------------------------------------------------===//
164
// APIs for simple analysis of the loop.
166
// Note that all of these methods can fail on general loops (ie, there may not
167
// be a preheader, etc). For best success, the loop simplification and
168
// induction variable canonicalization pass should be used to normalize loops
169
// for easy analysis. These methods assume canonical loops.
171
/// getExitingBlocks - Return all blocks inside the loop that have successors
172
/// outside of the loop. These are the blocks _inside of the current loop_
173
/// which branch out. The returned list is always unique.
175
void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const {
176
// Sort the blocks vector so that we can use binary search to do quick
178
SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
179
std::sort(LoopBBs.begin(), LoopBBs.end());
181
typedef GraphTraits<BlockT*> BlockTraits;
182
for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
183
for (typename BlockTraits::ChildIteratorType I =
184
BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
186
if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) {
187
// Not in current loop? It must be an exit block.
188
ExitingBlocks.push_back(*BI);
193
/// getExitingBlock - If getExitingBlocks would return exactly one block,
194
/// return that block. Otherwise return null.
195
BlockT *getExitingBlock() const {
196
SmallVector<BlockT*, 8> ExitingBlocks;
197
getExitingBlocks(ExitingBlocks);
198
if (ExitingBlocks.size() == 1)
199
return ExitingBlocks[0];
203
/// getExitBlocks - Return all of the successor blocks of this loop. These
204
/// are the blocks _outside of the current loop_ which are branched to.
206
void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
207
// Sort the blocks vector so that we can use binary search to do quick
209
SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
210
std::sort(LoopBBs.begin(), LoopBBs.end());
212
typedef GraphTraits<BlockT*> BlockTraits;
213
for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
214
for (typename BlockTraits::ChildIteratorType I =
215
BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
217
if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
218
// Not in current loop? It must be an exit block.
219
ExitBlocks.push_back(*I);
222
/// getExitBlock - If getExitBlocks would return exactly one block,
223
/// return that block. Otherwise return null.
224
BlockT *getExitBlock() const {
225
SmallVector<BlockT*, 8> ExitBlocks;
226
getExitBlocks(ExitBlocks);
227
if (ExitBlocks.size() == 1)
228
return ExitBlocks[0];
232
/// getExitEdges - Return all pairs of (_inside_block_,_outside_block_).
233
typedef std::pair<const BlockT*,const BlockT*> Edge;
234
void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const {
235
// Sort the blocks vector so that we can use binary search to do quick
237
SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
238
std::sort(LoopBBs.begin(), LoopBBs.end());
240
typedef GraphTraits<BlockT*> BlockTraits;
241
for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
242
for (typename BlockTraits::ChildIteratorType I =
243
BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
245
if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
246
// Not in current loop? It must be an exit block.
247
ExitEdges.push_back(std::make_pair(*BI, *I));
250
/// getLoopPreheader - If there is a preheader for this loop, return it. A
251
/// loop has a preheader if there is only one edge to the header of the loop
252
/// from outside of the loop. If this is the case, the block branching to the
253
/// header of the loop is the preheader node.
255
/// This method returns null if there is no preheader for the loop.
257
BlockT *getLoopPreheader() const {
258
// Keep track of nodes outside the loop branching to the header...
261
// Loop over the predecessors of the header node...
262
BlockT *Header = getHeader();
263
typedef GraphTraits<BlockT*> BlockTraits;
264
typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
265
for (typename InvBlockTraits::ChildIteratorType PI =
266
InvBlockTraits::child_begin(Header),
267
PE = InvBlockTraits::child_end(Header); PI != PE; ++PI)
268
if (!contains(*PI)) { // If the block is not in the loop...
269
if (Out && Out != *PI)
270
return 0; // Multiple predecessors outside the loop
274
// Make sure there is only one exit out of the preheader.
275
assert(Out && "Header of loop has no predecessors from outside loop?");
276
typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out);
278
if (SI != BlockTraits::child_end(Out))
279
return 0; // Multiple exits from the block, must not be a preheader.
281
// If there is exactly one preheader, return it. If there was zero, then
282
// Out is still null.
286
/// getLoopLatch - If there is a single latch block for this loop, return it.
287
/// A latch block is a block that contains a branch back to the header.
288
BlockT *getLoopLatch() const {
289
BlockT *Header = getHeader();
290
typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
291
typename InvBlockTraits::ChildIteratorType PI =
292
InvBlockTraits::child_begin(Header);
293
typename InvBlockTraits::ChildIteratorType PE =
294
InvBlockTraits::child_end(Header);
296
for (; PI != PE; ++PI)
305
//===--------------------------------------------------------------------===//
306
// APIs for updating loop information after changing the CFG
309
/// addBasicBlockToLoop - This method is used by other analyses to update loop
310
/// information. NewBB is set to be a new member of the current loop.
311
/// Because of this, it is added as a member of all parent loops, and is added
312
/// to the specified LoopInfo object as being in the current basic block. It
313
/// is not valid to replace the loop header with this method.
315
void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
317
/// replaceChildLoopWith - This is used when splitting loops up. It replaces
318
/// the OldChild entry in our children list with NewChild, and updates the
319
/// parent pointer of OldChild to be null and the NewChild to be this loop.
320
/// This updates the loop depth of the new child.
321
void replaceChildLoopWith(LoopT *OldChild,
323
assert(OldChild->ParentLoop == this && "This loop is already broken!");
324
assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
325
typename std::vector<LoopT *>::iterator I =
326
std::find(SubLoops.begin(), SubLoops.end(), OldChild);
327
assert(I != SubLoops.end() && "OldChild not in loop!");
329
OldChild->ParentLoop = 0;
330
NewChild->ParentLoop = static_cast<LoopT *>(this);
333
/// addChildLoop - Add the specified loop to be a child of this loop. This
334
/// updates the loop depth of the new child.
336
void addChildLoop(LoopT *NewChild) {
337
assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
338
NewChild->ParentLoop = static_cast<LoopT *>(this);
339
SubLoops.push_back(NewChild);
342
/// removeChildLoop - This removes the specified child from being a subloop of
343
/// this loop. The loop is not deleted, as it will presumably be inserted
344
/// into another loop.
345
LoopT *removeChildLoop(iterator I) {
346
assert(I != SubLoops.end() && "Cannot remove end iterator!");
348
assert(Child->ParentLoop == this && "Child is not a child of this loop!");
349
SubLoops.erase(SubLoops.begin()+(I-begin()));
350
Child->ParentLoop = 0;
354
/// addBlockEntry - This adds a basic block directly to the basic block list.
355
/// This should only be used by transformations that create new loops. Other
356
/// transformations should use addBasicBlockToLoop.
357
void addBlockEntry(BlockT *BB) {
358
Blocks.push_back(BB);
361
/// moveToHeader - This method is used to move BB (which must be part of this
362
/// loop) to be the loop header of the loop (the block that dominates all
364
void moveToHeader(BlockT *BB) {
365
if (Blocks[0] == BB) return;
366
for (unsigned i = 0; ; ++i) {
367
assert(i != Blocks.size() && "Loop does not contain BB!");
368
if (Blocks[i] == BB) {
369
Blocks[i] = Blocks[0];
376
/// removeBlockFromLoop - This removes the specified basic block from the
377
/// current loop, updating the Blocks as appropriate. This does not update
378
/// the mapping in the LoopInfo class.
379
void removeBlockFromLoop(BlockT *BB) {
380
RemoveFromVector(Blocks, BB);
383
/// verifyLoop - Verify loop structure
384
void verifyLoop() const {
386
assert(!Blocks.empty() && "Loop header is missing");
388
// Sort the blocks vector so that we can use binary search to do quick
390
SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
391
std::sort(LoopBBs.begin(), LoopBBs.end());
393
// Check the individual blocks.
394
for (block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
396
bool HasInsideLoopSuccs = false;
397
bool HasInsideLoopPreds = false;
398
SmallVector<BlockT *, 2> OutsideLoopPreds;
400
typedef GraphTraits<BlockT*> BlockTraits;
401
for (typename BlockTraits::ChildIteratorType SI =
402
BlockTraits::child_begin(BB), SE = BlockTraits::child_end(BB);
404
if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *SI)) {
405
HasInsideLoopSuccs = true;
408
typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
409
for (typename InvBlockTraits::ChildIteratorType PI =
410
InvBlockTraits::child_begin(BB), PE = InvBlockTraits::child_end(BB);
412
if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *PI))
413
HasInsideLoopPreds = true;
415
OutsideLoopPreds.push_back(*PI);
418
if (BB == getHeader()) {
419
assert(!OutsideLoopPreds.empty() && "Loop is unreachable!");
420
} else if (!OutsideLoopPreds.empty()) {
421
// A non-header loop shouldn't be reachable from outside the loop,
422
// though it is permitted if the predecessor is not itself actually
424
BlockT *EntryBB = BB->getParent()->begin();
425
for (df_iterator<BlockT *> NI = df_begin(EntryBB),
426
NE = df_end(EntryBB); NI != NE; ++NI)
427
for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i)
428
assert(*NI != OutsideLoopPreds[i] &&
429
"Loop has multiple entry points!");
431
assert(HasInsideLoopPreds && "Loop block has no in-loop predecessors!");
432
assert(HasInsideLoopSuccs && "Loop block has no in-loop successors!");
433
assert(BB != getHeader()->getParent()->begin() &&
434
"Loop contains function entry block!");
437
// Check the subloops.
438
for (iterator I = begin(), E = end(); I != E; ++I)
439
// Each block in each subloop should be contained within this loop.
440
for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end();
442
assert(std::binary_search(LoopBBs.begin(), LoopBBs.end(), *BI) &&
443
"Loop does not contain all the blocks of a subloop!");
446
// Check the parent loop pointer.
448
assert(std::find(ParentLoop->begin(), ParentLoop->end(), this) !=
450
"Loop is not a subloop of its parent!");
455
/// verifyLoop - Verify loop structure of this loop and all nested loops.
456
void verifyLoopNest() const {
459
// Verify the subloops.
460
for (iterator I = begin(), E = end(); I != E; ++I)
461
(*I)->verifyLoopNest();
464
void print(raw_ostream &OS, unsigned Depth = 0) const {
465
OS.indent(Depth*2) << "Loop at depth " << getLoopDepth()
468
for (unsigned i = 0; i < getBlocks().size(); ++i) {
470
BlockT *BB = getBlocks()[i];
471
WriteAsOperand(OS, BB, false);
472
if (BB == getHeader()) OS << "<header>";
473
if (BB == getLoopLatch()) OS << "<latch>";
474
if (isLoopExiting(BB)) OS << "<exiting>";
478
for (iterator I = begin(), E = end(); I != E; ++I)
479
(*I)->print(OS, Depth+2);
483
friend class LoopInfoBase<BlockT, LoopT>;
484
explicit LoopBase(BlockT *BB) : ParentLoop(0) {
485
Blocks.push_back(BB);
489
class Loop : public LoopBase<BasicBlock, Loop> {
493
/// isLoopInvariant - Return true if the specified value is loop invariant
495
bool isLoopInvariant(Value *V) const;
497
/// isLoopInvariant - Return true if the specified instruction is
500
bool isLoopInvariant(Instruction *I) const;
502
/// makeLoopInvariant - If the given value is an instruction inside of the
503
/// loop and it can be hoisted, do so to make it trivially loop-invariant.
504
/// Return true if the value after any hoisting is loop invariant. This
505
/// function can be used as a slightly more aggressive replacement for
508
/// If InsertPt is specified, it is the point to hoist instructions to.
509
/// If null, the terminator of the loop preheader is used.
511
bool makeLoopInvariant(Value *V, bool &Changed,
512
Instruction *InsertPt = 0) const;
514
/// makeLoopInvariant - If the given instruction is inside of the
515
/// loop and it can be hoisted, do so to make it trivially loop-invariant.
516
/// Return true if the instruction after any hoisting is loop invariant. This
517
/// function can be used as a slightly more aggressive replacement for
520
/// If InsertPt is specified, it is the point to hoist instructions to.
521
/// If null, the terminator of the loop preheader is used.
523
bool makeLoopInvariant(Instruction *I, bool &Changed,
524
Instruction *InsertPt = 0) const;
526
/// getCanonicalInductionVariable - Check to see if the loop has a canonical
527
/// induction variable: an integer recurrence that starts at 0 and increments
528
/// by one each time through the loop. If so, return the phi node that
529
/// corresponds to it.
531
/// The IndVarSimplify pass transforms loops to have a canonical induction
534
PHINode *getCanonicalInductionVariable() const;
536
/// getCanonicalInductionVariableIncrement - Return the LLVM value that holds
537
/// the canonical induction variable value for the "next" iteration of the
538
/// loop. This always succeeds if getCanonicalInductionVariable succeeds.
540
Instruction *getCanonicalInductionVariableIncrement() const;
542
/// getTripCount - Return a loop-invariant LLVM value indicating the number of
543
/// times the loop will be executed. Note that this means that the backedge
544
/// of the loop executes N-1 times. If the trip-count cannot be determined,
545
/// this returns null.
547
/// The IndVarSimplify pass transforms loops to have a form that this
548
/// function easily understands.
550
Value *getTripCount() const;
552
/// getSmallConstantTripCount - Returns the trip count of this loop as a
553
/// normal unsigned value, if possible. Returns 0 if the trip count is unknown
554
/// of not constant. Will also return 0 if the trip count is very large
557
/// The IndVarSimplify pass transforms loops to have a form that this
558
/// function easily understands.
560
unsigned getSmallConstantTripCount() const;
562
/// getSmallConstantTripMultiple - Returns the largest constant divisor of the
563
/// trip count of this loop as a normal unsigned value, if possible. This
564
/// means that the actual trip count is always a multiple of the returned
565
/// value (don't forget the trip count could very well be zero as well!).
567
/// Returns 1 if the trip count is unknown or not guaranteed to be the
568
/// multiple of a constant (which is also the case if the trip count is simply
569
/// constant, use getSmallConstantTripCount for that case), Will also return 1
570
/// if the trip count is very large (>= 2^32).
571
unsigned getSmallConstantTripMultiple() const;
573
/// isLCSSAForm - Return true if the Loop is in LCSSA form
574
bool isLCSSAForm() const;
576
/// isLoopSimplifyForm - Return true if the Loop is in the form that
577
/// the LoopSimplify form transforms loops to, which is sometimes called
579
bool isLoopSimplifyForm() const;
581
/// hasDedicatedExits - Return true if no exit block for the loop
582
/// has a predecessor that is outside the loop.
583
bool hasDedicatedExits() const;
585
/// getUniqueExitBlocks - Return all unique successor blocks of this loop.
586
/// These are the blocks _outside of the current loop_ which are branched to.
587
/// This assumes that loop exits are in canonical form.
589
void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
591
/// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
592
/// block, return that block. Otherwise return null.
593
BasicBlock *getUniqueExitBlock() const;
598
friend class LoopInfoBase<BasicBlock, Loop>;
599
explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
602
//===----------------------------------------------------------------------===//
603
/// LoopInfo - This class builds and contains all of the top level loop
604
/// structures in the specified function.
607
template<class BlockT, class LoopT>
609
// BBMap - Mapping of basic blocks to the inner most loop they occur in
610
std::map<BlockT *, LoopT *> BBMap;
611
std::vector<LoopT *> TopLevelLoops;
612
friend class LoopBase<BlockT, LoopT>;
614
void operator=(const LoopInfoBase &); // do not implement
615
LoopInfoBase(const LoopInfo &); // do not implement
618
~LoopInfoBase() { releaseMemory(); }
620
void releaseMemory() {
621
for (typename std::vector<LoopT *>::iterator I =
622
TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I)
623
delete *I; // Delete all of the loops...
625
BBMap.clear(); // Reset internal state of analysis
626
TopLevelLoops.clear();
629
/// iterator/begin/end - The interface to the top-level loops in the current
632
typedef typename std::vector<LoopT *>::const_iterator iterator;
633
iterator begin() const { return TopLevelLoops.begin(); }
634
iterator end() const { return TopLevelLoops.end(); }
635
bool empty() const { return TopLevelLoops.empty(); }
637
/// getLoopFor - Return the inner most loop that BB lives in. If a basic
638
/// block is in no loop (for example the entry node), null is returned.
640
LoopT *getLoopFor(const BlockT *BB) const {
641
typename std::map<BlockT *, LoopT *>::const_iterator I=
642
BBMap.find(const_cast<BlockT*>(BB));
643
return I != BBMap.end() ? I->second : 0;
646
/// operator[] - same as getLoopFor...
648
const LoopT *operator[](const BlockT *BB) const {
649
return getLoopFor(BB);
652
/// getLoopDepth - Return the loop nesting level of the specified block. A
653
/// depth of 0 means the block is not inside any loop.
655
unsigned getLoopDepth(const BlockT *BB) const {
656
const LoopT *L = getLoopFor(BB);
657
return L ? L->getLoopDepth() : 0;
660
// isLoopHeader - True if the block is a loop header node
661
bool isLoopHeader(BlockT *BB) const {
662
const LoopT *L = getLoopFor(BB);
663
return L && L->getHeader() == BB;
666
/// removeLoop - This removes the specified top-level loop from this loop info
667
/// object. The loop is not deleted, as it will presumably be inserted into
669
LoopT *removeLoop(iterator I) {
670
assert(I != end() && "Cannot remove end iterator!");
672
assert(L->getParentLoop() == 0 && "Not a top-level loop!");
673
TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
677
/// changeLoopFor - Change the top-level loop that contains BB to the
678
/// specified loop. This should be used by transformations that restructure
679
/// the loop hierarchy tree.
680
void changeLoopFor(BlockT *BB, LoopT *L) {
681
LoopT *&OldLoop = BBMap[BB];
682
assert(OldLoop && "Block not in a loop yet!");
686
/// changeTopLevelLoop - Replace the specified loop in the top-level loops
687
/// list with the indicated loop.
688
void changeTopLevelLoop(LoopT *OldLoop,
690
typename std::vector<LoopT *>::iterator I =
691
std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop);
692
assert(I != TopLevelLoops.end() && "Old loop not at top level!");
694
assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 &&
695
"Loops already embedded into a subloop!");
698
/// addTopLevelLoop - This adds the specified loop to the collection of
700
void addTopLevelLoop(LoopT *New) {
701
assert(New->getParentLoop() == 0 && "Loop already in subloop!");
702
TopLevelLoops.push_back(New);
705
/// removeBlock - This method completely removes BB from all data structures,
706
/// including all of the Loop objects it is nested in and our mapping from
707
/// BasicBlocks to loops.
708
void removeBlock(BlockT *BB) {
709
typename std::map<BlockT *, LoopT *>::iterator I = BBMap.find(BB);
710
if (I != BBMap.end()) {
711
for (LoopT *L = I->second; L; L = L->getParentLoop())
712
L->removeBlockFromLoop(BB);
720
static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
721
const LoopT *ParentLoop) {
722
if (SubLoop == 0) return true;
723
if (SubLoop == ParentLoop) return false;
724
return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
727
void Calculate(DominatorTreeBase<BlockT> &DT) {
728
BlockT *RootNode = DT.getRootNode()->getBlock();
730
for (df_iterator<BlockT*> NI = df_begin(RootNode),
731
NE = df_end(RootNode); NI != NE; ++NI)
732
if (LoopT *L = ConsiderForLoop(*NI, DT))
733
TopLevelLoops.push_back(L);
736
LoopT *ConsiderForLoop(BlockT *BB, DominatorTreeBase<BlockT> &DT) {
737
if (BBMap.find(BB) != BBMap.end()) return 0;// Haven't processed this node?
739
std::vector<BlockT *> TodoStack;
741
// Scan the predecessors of BB, checking to see if BB dominates any of
742
// them. This identifies backedges which target this node...
743
typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
744
for (typename InvBlockTraits::ChildIteratorType I =
745
InvBlockTraits::child_begin(BB), E = InvBlockTraits::child_end(BB);
747
if (DT.dominates(BB, *I)) // If BB dominates its predecessor...
748
TodoStack.push_back(*I);
750
if (TodoStack.empty()) return 0; // No backedges to this block...
752
// Create a new loop to represent this basic block...
753
LoopT *L = new LoopT(BB);
756
BlockT *EntryBlock = BB->getParent()->begin();
758
while (!TodoStack.empty()) { // Process all the nodes in the loop
759
BlockT *X = TodoStack.back();
760
TodoStack.pop_back();
762
if (!L->contains(X) && // As of yet unprocessed??
763
DT.dominates(EntryBlock, X)) { // X is reachable from entry block?
764
// Check to see if this block already belongs to a loop. If this occurs
765
// then we have a case where a loop that is supposed to be a child of
766
// the current loop was processed before the current loop. When this
767
// occurs, this child loop gets added to a part of the current loop,
768
// making it a sibling to the current loop. We have to reparent this
771
const_cast<LoopT *>(getLoopFor(X)))
772
if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)){
773
// Remove the subloop from its current parent...
774
assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L);
775
LoopT *SLP = SubLoop->ParentLoop; // SubLoopParent
776
typename std::vector<LoopT *>::iterator I =
777
std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop);
778
assert(I != SLP->SubLoops.end() &&"SubLoop not a child of parent?");
779
SLP->SubLoops.erase(I); // Remove from parent...
781
// Add the subloop to THIS loop...
782
SubLoop->ParentLoop = L;
783
L->SubLoops.push_back(SubLoop);
786
// Normal case, add the block to our loop...
787
L->Blocks.push_back(X);
789
typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
791
// Add all of the predecessors of X to the end of the work stack...
792
TodoStack.insert(TodoStack.end(), InvBlockTraits::child_begin(X),
793
InvBlockTraits::child_end(X));
797
// If there are any loops nested within this loop, create them now!
798
for (typename std::vector<BlockT*>::iterator I = L->Blocks.begin(),
799
E = L->Blocks.end(); I != E; ++I)
800
if (LoopT *NewLoop = ConsiderForLoop(*I, DT)) {
801
L->SubLoops.push_back(NewLoop);
802
NewLoop->ParentLoop = L;
805
// Add the basic blocks that comprise this loop to the BBMap so that this
806
// loop can be found for them.
808
for (typename std::vector<BlockT*>::iterator I = L->Blocks.begin(),
809
E = L->Blocks.end(); I != E; ++I)
810
BBMap.insert(std::make_pair(*I, L));
812
// Now that we have a list of all of the child loops of this loop, check to
813
// see if any of them should actually be nested inside of each other. We
814
// can accidentally pull loops our of their parents, so we must make sure to
815
// organize the loop nests correctly now.
817
std::map<BlockT *, LoopT *> ContainingLoops;
818
for (unsigned i = 0; i != L->SubLoops.size(); ++i) {
819
LoopT *Child = L->SubLoops[i];
820
assert(Child->getParentLoop() == L && "Not proper child loop?");
822
if (LoopT *ContainingLoop = ContainingLoops[Child->getHeader()]) {
823
// If there is already a loop which contains this loop, move this loop
824
// into the containing loop.
825
MoveSiblingLoopInto(Child, ContainingLoop);
826
--i; // The loop got removed from the SubLoops list.
828
// This is currently considered to be a top-level loop. Check to see
829
// if any of the contained blocks are loop headers for subloops we
830
// have already processed.
831
for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) {
832
LoopT *&BlockLoop = ContainingLoops[Child->Blocks[b]];
833
if (BlockLoop == 0) { // Child block not processed yet...
835
} else if (BlockLoop != Child) {
836
LoopT *SubLoop = BlockLoop;
837
// Reparent all of the blocks which used to belong to BlockLoops
838
for (unsigned j = 0, f = SubLoop->Blocks.size(); j != f; ++j)
839
ContainingLoops[SubLoop->Blocks[j]] = Child;
841
// There is already a loop which contains this block, that means
842
// that we should reparent the loop which the block is currently
843
// considered to belong to to be a child of this loop.
844
MoveSiblingLoopInto(SubLoop, Child);
845
--i; // We just shrunk the SubLoops list.
855
/// MoveSiblingLoopInto - This method moves the NewChild loop to live inside
856
/// of the NewParent Loop, instead of being a sibling of it.
857
void MoveSiblingLoopInto(LoopT *NewChild,
859
LoopT *OldParent = NewChild->getParentLoop();
860
assert(OldParent && OldParent == NewParent->getParentLoop() &&
861
NewChild != NewParent && "Not sibling loops!");
863
// Remove NewChild from being a child of OldParent
864
typename std::vector<LoopT *>::iterator I =
865
std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(),
867
assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??");
868
OldParent->SubLoops.erase(I); // Remove from parent's subloops list
869
NewChild->ParentLoop = 0;
871
InsertLoopInto(NewChild, NewParent);
874
/// InsertLoopInto - This inserts loop L into the specified parent loop. If
875
/// the parent loop contains a loop which should contain L, the loop gets
876
/// inserted into L instead.
877
void InsertLoopInto(LoopT *L, LoopT *Parent) {
878
BlockT *LHeader = L->getHeader();
879
assert(Parent->contains(LHeader) &&
880
"This loop should not be inserted here!");
882
// Check to see if it belongs in a child loop...
883
for (unsigned i = 0, e = static_cast<unsigned>(Parent->SubLoops.size());
885
if (Parent->SubLoops[i]->contains(LHeader)) {
886
InsertLoopInto(L, Parent->SubLoops[i]);
890
// If not, insert it here!
891
Parent->SubLoops.push_back(L);
892
L->ParentLoop = Parent;
897
void print(raw_ostream &OS) const {
898
for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
899
TopLevelLoops[i]->print(OS);
901
for (std::map<BasicBlock*, LoopT*>::const_iterator I = BBMap.begin(),
902
E = BBMap.end(); I != E; ++I)
903
OS << "BB '" << I->first->getName() << "' level = "
904
<< I->second->getLoopDepth() << "\n";
909
class LoopInfo : public FunctionPass {
910
LoopInfoBase<BasicBlock, Loop> LI;
911
friend class LoopBase<BasicBlock, Loop>;
913
void operator=(const LoopInfo &); // do not implement
914
LoopInfo(const LoopInfo &); // do not implement
916
static char ID; // Pass identification, replacement for typeid
918
LoopInfo() : FunctionPass(&ID) {}
920
LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; }
922
/// iterator/begin/end - The interface to the top-level loops in the current
925
typedef LoopInfoBase<BasicBlock, Loop>::iterator iterator;
926
inline iterator begin() const { return LI.begin(); }
927
inline iterator end() const { return LI.end(); }
928
bool empty() const { return LI.empty(); }
930
/// getLoopFor - Return the inner most loop that BB lives in. If a basic
931
/// block is in no loop (for example the entry node), null is returned.
933
inline Loop *getLoopFor(const BasicBlock *BB) const {
934
return LI.getLoopFor(BB);
937
/// operator[] - same as getLoopFor...
939
inline const Loop *operator[](const BasicBlock *BB) const {
940
return LI.getLoopFor(BB);
943
/// getLoopDepth - Return the loop nesting level of the specified block. A
944
/// depth of 0 means the block is not inside any loop.
946
inline unsigned getLoopDepth(const BasicBlock *BB) const {
947
return LI.getLoopDepth(BB);
950
// isLoopHeader - True if the block is a loop header node
951
inline bool isLoopHeader(BasicBlock *BB) const {
952
return LI.isLoopHeader(BB);
955
/// runOnFunction - Calculate the natural loop information.
957
virtual bool runOnFunction(Function &F);
959
virtual void verifyAnalysis() const;
961
virtual void releaseMemory() { LI.releaseMemory(); }
963
virtual void print(raw_ostream &O, const Module* M = 0) const;
965
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
967
/// removeLoop - This removes the specified top-level loop from this loop info
968
/// object. The loop is not deleted, as it will presumably be inserted into
970
inline Loop *removeLoop(iterator I) { return LI.removeLoop(I); }
972
/// changeLoopFor - Change the top-level loop that contains BB to the
973
/// specified loop. This should be used by transformations that restructure
974
/// the loop hierarchy tree.
975
inline void changeLoopFor(BasicBlock *BB, Loop *L) {
976
LI.changeLoopFor(BB, L);
979
/// changeTopLevelLoop - Replace the specified loop in the top-level loops
980
/// list with the indicated loop.
981
inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
982
LI.changeTopLevelLoop(OldLoop, NewLoop);
985
/// addTopLevelLoop - This adds the specified loop to the collection of
987
inline void addTopLevelLoop(Loop *New) {
988
LI.addTopLevelLoop(New);
991
/// removeBlock - This method completely removes BB from all data structures,
992
/// including all of the Loop objects it is nested in and our mapping from
993
/// BasicBlocks to loops.
994
void removeBlock(BasicBlock *BB) {
1000
// Allow clients to walk the list of nested loops...
1001
template <> struct GraphTraits<const Loop*> {
1002
typedef const Loop NodeType;
1003
typedef LoopInfo::iterator ChildIteratorType;
1005
static NodeType *getEntryNode(const Loop *L) { return L; }
1006
static inline ChildIteratorType child_begin(NodeType *N) {
1009
static inline ChildIteratorType child_end(NodeType *N) {
1014
template <> struct GraphTraits<Loop*> {
1015
typedef Loop NodeType;
1016
typedef LoopInfo::iterator ChildIteratorType;
1018
static NodeType *getEntryNode(Loop *L) { return L; }
1019
static inline ChildIteratorType child_begin(NodeType *N) {
1022
static inline ChildIteratorType child_end(NodeType *N) {
1027
template<class BlockT, class LoopT>
1029
LoopBase<BlockT, LoopT>::addBasicBlockToLoop(BlockT *NewBB,
1030
LoopInfoBase<BlockT, LoopT> &LIB) {
1031
assert((Blocks.empty() || LIB[getHeader()] == this) &&
1032
"Incorrect LI specified for this loop!");
1033
assert(NewBB && "Cannot add a null basic block to the loop!");
1034
assert(LIB[NewBB] == 0 && "BasicBlock already in the loop!");
1036
LoopT *L = static_cast<LoopT *>(this);
1038
// Add the loop mapping to the LoopInfo object...
1039
LIB.BBMap[NewBB] = L;
1041
// Add the basic block to this loop and all parent loops...
1043
L->Blocks.push_back(NewBB);
1044
L = L->getParentLoop();
1048
} // End llvm namespace