LLVM  7.0.0svn
LCSSA.cpp
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1 //===-- LCSSA.cpp - Convert loops into loop-closed SSA form ---------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This pass transforms loops by placing phi nodes at the end of the loops for
11 // all values that are live across the loop boundary. For example, it turns
12 // the left into the right code:
13 //
14 // for (...) for (...)
15 // if (c) if (c)
16 // X1 = ... X1 = ...
17 // else else
18 // X2 = ... X2 = ...
19 // X3 = phi(X1, X2) X3 = phi(X1, X2)
20 // ... = X3 + 4 X4 = phi(X3)
21 // ... = X4 + 4
22 //
23 // This is still valid LLVM; the extra phi nodes are purely redundant, and will
24 // be trivially eliminated by InstCombine. The major benefit of this
25 // transformation is that it makes many other loop optimizations, such as
26 // LoopUnswitching, simpler.
27 //
28 //===----------------------------------------------------------------------===//
29 
31 #include "llvm/ADT/STLExtras.h"
32 #include "llvm/ADT/Statistic.h"
36 #include "llvm/Analysis/LoopPass.h"
40 #include "llvm/IR/Constants.h"
41 #include "llvm/IR/Dominators.h"
42 #include "llvm/IR/Function.h"
43 #include "llvm/IR/Instructions.h"
45 #include "llvm/Pass.h"
46 #include "llvm/Transforms/Utils.h"
49 using namespace llvm;
50 
51 #define DEBUG_TYPE "lcssa"
52 
53 STATISTIC(NumLCSSA, "Number of live out of a loop variables");
54 
55 #ifdef EXPENSIVE_CHECKS
56 static bool VerifyLoopLCSSA = true;
57 #else
58 static bool VerifyLoopLCSSA = false;
59 #endif
61  VerifyLoopLCSSAFlag("verify-loop-lcssa", cl::location(VerifyLoopLCSSA),
62  cl::Hidden,
63  cl::desc("Verify loop lcssa form (time consuming)"));
64 
65 /// Return true if the specified block is in the list.
66 static bool isExitBlock(BasicBlock *BB,
67  const SmallVectorImpl<BasicBlock *> &ExitBlocks) {
68  return is_contained(ExitBlocks, BB);
69 }
70 
71 /// For every instruction from the worklist, check to see if it has any uses
72 /// that are outside the current loop. If so, insert LCSSA PHI nodes and
73 /// rewrite the uses.
75  DominatorTree &DT, LoopInfo &LI) {
76  SmallVector<Use *, 16> UsesToRewrite;
77  SmallSetVector<PHINode *, 16> PHIsToRemove;
78  PredIteratorCache PredCache;
79  bool Changed = false;
80 
81  // Cache the Loop ExitBlocks across this loop. We expect to get a lot of
82  // instructions within the same loops, computing the exit blocks is
83  // expensive, and we're not mutating the loop structure.
85 
86  while (!Worklist.empty()) {
87  UsesToRewrite.clear();
88 
89  Instruction *I = Worklist.pop_back_val();
90  assert(!I->getType()->isTokenTy() && "Tokens shouldn't be in the worklist");
91  BasicBlock *InstBB = I->getParent();
92  Loop *L = LI.getLoopFor(InstBB);
93  assert(L && "Instruction belongs to a BB that's not part of a loop");
94  if (!LoopExitBlocks.count(L))
95  L->getExitBlocks(LoopExitBlocks[L]);
96  assert(LoopExitBlocks.count(L));
97  const SmallVectorImpl<BasicBlock *> &ExitBlocks = LoopExitBlocks[L];
98 
99  if (ExitBlocks.empty())
100  continue;
101 
102  for (Use &U : I->uses()) {
103  Instruction *User = cast<Instruction>(U.getUser());
104  BasicBlock *UserBB = User->getParent();
105  if (auto *PN = dyn_cast<PHINode>(User))
106  UserBB = PN->getIncomingBlock(U);
107 
108  if (InstBB != UserBB && !L->contains(UserBB))
109  UsesToRewrite.push_back(&U);
110  }
111 
112  // If there are no uses outside the loop, exit with no change.
113  if (UsesToRewrite.empty())
114  continue;
115 
116  ++NumLCSSA; // We are applying the transformation
117 
118  // Invoke instructions are special in that their result value is not
119  // available along their unwind edge. The code below tests to see whether
120  // DomBB dominates the value, so adjust DomBB to the normal destination
121  // block, which is effectively where the value is first usable.
122  BasicBlock *DomBB = InstBB;
123  if (auto *Inv = dyn_cast<InvokeInst>(I))
124  DomBB = Inv->getNormalDest();
125 
126  DomTreeNode *DomNode = DT.getNode(DomBB);
127 
128  SmallVector<PHINode *, 16> AddedPHIs;
129  SmallVector<PHINode *, 8> PostProcessPHIs;
130 
131  SmallVector<PHINode *, 4> InsertedPHIs;
132  SSAUpdater SSAUpdate(&InsertedPHIs);
133  SSAUpdate.Initialize(I->getType(), I->getName());
134 
135  // Insert the LCSSA phi's into all of the exit blocks dominated by the
136  // value, and add them to the Phi's map.
137  for (BasicBlock *ExitBB : ExitBlocks) {
138  if (!DT.dominates(DomNode, DT.getNode(ExitBB)))
139  continue;
140 
141  // If we already inserted something for this BB, don't reprocess it.
142  if (SSAUpdate.HasValueForBlock(ExitBB))
143  continue;
144 
145  PHINode *PN = PHINode::Create(I->getType(), PredCache.size(ExitBB),
146  I->getName() + ".lcssa", &ExitBB->front());
147 
148  // Add inputs from inside the loop for this PHI.
149  for (BasicBlock *Pred : PredCache.get(ExitBB)) {
150  PN->addIncoming(I, Pred);
151 
152  // If the exit block has a predecessor not within the loop, arrange for
153  // the incoming value use corresponding to that predecessor to be
154  // rewritten in terms of a different LCSSA PHI.
155  if (!L->contains(Pred))
156  UsesToRewrite.push_back(
158  PN->getNumIncomingValues() - 1)));
159  }
160 
161  AddedPHIs.push_back(PN);
162 
163  // Remember that this phi makes the value alive in this block.
164  SSAUpdate.AddAvailableValue(ExitBB, PN);
165 
166  // LoopSimplify might fail to simplify some loops (e.g. when indirect
167  // branches are involved). In such situations, it might happen that an
168  // exit for Loop L1 is the header of a disjoint Loop L2. Thus, when we
169  // create PHIs in such an exit block, we are also inserting PHIs into L2's
170  // header. This could break LCSSA form for L2 because these inserted PHIs
171  // can also have uses outside of L2. Remember all PHIs in such situation
172  // as to revisit than later on. FIXME: Remove this if indirectbr support
173  // into LoopSimplify gets improved.
174  if (auto *OtherLoop = LI.getLoopFor(ExitBB))
175  if (!L->contains(OtherLoop))
176  PostProcessPHIs.push_back(PN);
177  }
178 
179  // Rewrite all uses outside the loop in terms of the new PHIs we just
180  // inserted.
181  for (Use *UseToRewrite : UsesToRewrite) {
182  // If this use is in an exit block, rewrite to use the newly inserted PHI.
183  // This is required for correctness because SSAUpdate doesn't handle uses
184  // in the same block. It assumes the PHI we inserted is at the end of the
185  // block.
186  Instruction *User = cast<Instruction>(UseToRewrite->getUser());
187  BasicBlock *UserBB = User->getParent();
188  if (auto *PN = dyn_cast<PHINode>(User))
189  UserBB = PN->getIncomingBlock(*UseToRewrite);
190 
191  if (isa<PHINode>(UserBB->begin()) && isExitBlock(UserBB, ExitBlocks)) {
192  // Tell the VHs that the uses changed. This updates SCEV's caches.
193  if (UseToRewrite->get()->hasValueHandle())
194  ValueHandleBase::ValueIsRAUWd(*UseToRewrite, &UserBB->front());
195  UseToRewrite->set(&UserBB->front());
196  continue;
197  }
198 
199  // Otherwise, do full PHI insertion.
200  SSAUpdate.RewriteUse(*UseToRewrite);
201  }
202 
203  // SSAUpdater might have inserted phi-nodes inside other loops. We'll need
204  // to post-process them to keep LCSSA form.
205  for (PHINode *InsertedPN : InsertedPHIs) {
206  if (auto *OtherLoop = LI.getLoopFor(InsertedPN->getParent()))
207  if (!L->contains(OtherLoop))
208  PostProcessPHIs.push_back(InsertedPN);
209  }
210 
211  // Post process PHI instructions that were inserted into another disjoint
212  // loop and update their exits properly.
213  for (auto *PostProcessPN : PostProcessPHIs)
214  if (!PostProcessPN->use_empty())
215  Worklist.push_back(PostProcessPN);
216 
217  // Keep track of PHI nodes that we want to remove because they did not have
218  // any uses rewritten. If the new PHI is used, store it so that we can
219  // try to propagate dbg.value intrinsics to it.
220  SmallVector<PHINode *, 2> NeedDbgValues;
221  for (PHINode *PN : AddedPHIs)
222  if (PN->use_empty())
223  PHIsToRemove.insert(PN);
224  else
225  NeedDbgValues.push_back(PN);
226  insertDebugValuesForPHIs(InstBB, NeedDbgValues);
227  Changed = true;
228  }
229  // Remove PHI nodes that did not have any uses rewritten.
230  for (PHINode *PN : PHIsToRemove) {
231  assert (PN->use_empty() && "Trying to remove a phi with uses.");
232  PN->eraseFromParent();
233  }
234  return Changed;
235 }
236 
237 // Compute the set of BasicBlocks in the loop `L` dominating at least one exit.
239  Loop &L, DominatorTree &DT, SmallVector<BasicBlock *, 8> &ExitBlocks,
240  SmallSetVector<BasicBlock *, 8> &BlocksDominatingExits) {
241  SmallVector<BasicBlock *, 8> BBWorklist;
242 
243  // We start from the exit blocks, as every block trivially dominates itself
244  // (not strictly).
245  for (BasicBlock *BB : ExitBlocks)
246  BBWorklist.push_back(BB);
247 
248  while (!BBWorklist.empty()) {
249  BasicBlock *BB = BBWorklist.pop_back_val();
250 
251  // Check if this is a loop header. If this is the case, we're done.
252  if (L.getHeader() == BB)
253  continue;
254 
255  // Otherwise, add its immediate predecessor in the dominator tree to the
256  // worklist, unless we visited it already.
257  BasicBlock *IDomBB = DT.getNode(BB)->getIDom()->getBlock();
258 
259  // Exit blocks can have an immediate dominator not beloinging to the
260  // loop. For an exit block to be immediately dominated by another block
261  // outside the loop, it implies not all paths from that dominator, to the
262  // exit block, go through the loop.
263  // Example:
264  //
265  // |---- A
266  // | |
267  // | B<--
268  // | | |
269  // |---> C --
270  // |
271  // D
272  //
273  // C is the exit block of the loop and it's immediately dominated by A,
274  // which doesn't belong to the loop.
275  if (!L.contains(IDomBB))
276  continue;
277 
278  if (BlocksDominatingExits.insert(IDomBB))
279  BBWorklist.push_back(IDomBB);
280  }
281 }
282 
284  ScalarEvolution *SE) {
285  bool Changed = false;
286 
287  SmallVector<BasicBlock *, 8> ExitBlocks;
288  L.getExitBlocks(ExitBlocks);
289  if (ExitBlocks.empty())
290  return false;
291 
292  SmallSetVector<BasicBlock *, 8> BlocksDominatingExits;
293 
294  // We want to avoid use-scanning leveraging dominance informations.
295  // If a block doesn't dominate any of the loop exits, the none of the values
296  // defined in the loop can be used outside.
297  // We compute the set of blocks fullfilling the conditions in advance
298  // walking the dominator tree upwards until we hit a loop header.
299  computeBlocksDominatingExits(L, DT, ExitBlocks, BlocksDominatingExits);
300 
302 
303  // Look at all the instructions in the loop, checking to see if they have uses
304  // outside the loop. If so, put them into the worklist to rewrite those uses.
305  for (BasicBlock *BB : BlocksDominatingExits) {
306  for (Instruction &I : *BB) {
307  // Reject two common cases fast: instructions with no uses (like stores)
308  // and instructions with one use that is in the same block as this.
309  if (I.use_empty() ||
310  (I.hasOneUse() && I.user_back()->getParent() == BB &&
311  !isa<PHINode>(I.user_back())))
312  continue;
313 
314  // Tokens cannot be used in PHI nodes, so we skip over them.
315  // We can run into tokens which are live out of a loop with catchswitch
316  // instructions in Windows EH if the catchswitch has one catchpad which
317  // is inside the loop and another which is not.
318  if (I.getType()->isTokenTy())
319  continue;
320 
321  Worklist.push_back(&I);
322  }
323  }
324  Changed = formLCSSAForInstructions(Worklist, DT, *LI);
325 
326  // If we modified the code, remove any caches about the loop from SCEV to
327  // avoid dangling entries.
328  // FIXME: This is a big hammer, can we clear the cache more selectively?
329  if (SE && Changed)
330  SE->forgetLoop(&L);
331 
332  assert(L.isLCSSAForm(DT));
333 
334  return Changed;
335 }
336 
337 /// Process a loop nest depth first.
339  ScalarEvolution *SE) {
340  bool Changed = false;
341 
342  // Recurse depth-first through inner loops.
343  for (Loop *SubLoop : L.getSubLoops())
344  Changed |= formLCSSARecursively(*SubLoop, DT, LI, SE);
345 
346  Changed |= formLCSSA(L, DT, LI, SE);
347  return Changed;
348 }
349 
350 /// Process all loops in the function, inner-most out.
352  ScalarEvolution *SE) {
353  bool Changed = false;
354  for (auto &L : *LI)
355  Changed |= formLCSSARecursively(*L, DT, LI, SE);
356  return Changed;
357 }
358 
359 namespace {
360 struct LCSSAWrapperPass : public FunctionPass {
361  static char ID; // Pass identification, replacement for typeid
362  LCSSAWrapperPass() : FunctionPass(ID) {
364  }
365 
366  // Cached analysis information for the current function.
367  DominatorTree *DT;
368  LoopInfo *LI;
369  ScalarEvolution *SE;
370 
371  bool runOnFunction(Function &F) override;
372  void verifyAnalysis() const override {
373  // This check is very expensive. On the loop intensive compiles it may cause
374  // up to 10x slowdown. Currently it's disabled by default. LPPassManager
375  // always does limited form of the LCSSA verification. Similar reasoning
376  // was used for the LoopInfo verifier.
377  if (VerifyLoopLCSSA) {
378  assert(all_of(*LI,
379  [&](Loop *L) {
380  return L->isRecursivelyLCSSAForm(*DT, *LI);
381  }) &&
382  "LCSSA form is broken!");
383  }
384  };
385 
386  /// This transformation requires natural loop information & requires that
387  /// loop preheaders be inserted into the CFG. It maintains both of these,
388  /// as well as the CFG. It also requires dominator information.
389  void getAnalysisUsage(AnalysisUsage &AU) const override {
390  AU.setPreservesCFG();
391 
400 
401  // This is needed to perform LCSSA verification inside LPPassManager
404  }
405 };
406 }
407 
408 char LCSSAWrapperPass::ID = 0;
409 INITIALIZE_PASS_BEGIN(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
410  false, false)
414 INITIALIZE_PASS_END(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
415  false, false)
416 
417 Pass *llvm::createLCSSAPass() { return new LCSSAWrapperPass(); }
419 
420 /// Transform \p F into loop-closed SSA form.
422  LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
423  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
424  auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>();
425  SE = SEWP ? &SEWP->getSE() : nullptr;
426 
427  return formLCSSAOnAllLoops(LI, *DT, SE);
428 }
429 
431  auto &LI = AM.getResult<LoopAnalysis>(F);
432  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
433  auto *SE = AM.getCachedResult<ScalarEvolutionAnalysis>(F);
434  if (!formLCSSAOnAllLoops(&LI, DT, SE))
435  return PreservedAnalyses::all();
436 
438  PA.preserveSet<CFGAnalyses>();
439  PA.preserve<BasicAA>();
440  PA.preserve<GlobalsAA>();
441  PA.preserve<SCEVAA>();
443  return PA;
444 }
Legacy wrapper pass to provide the GlobalsAAResult object.
Pass interface - Implemented by all &#39;passes&#39;.
Definition: Pass.h:81
void initializeLCSSAWrapperPassPass(PassRegistry &)
DomTreeNodeBase< NodeT > * getNode(NodeT *BB) const
getNode - return the (Post)DominatorTree node for the specified basic block.
iterator_range< use_iterator > uses()
Definition: Value.h:360
AnalysisUsage & addPreserved()
Add the specified Pass class to the set of analyses preserved by this pass.
Helper class for SSA formation on a set of values defined in multiple blocks.
Definition: SSAUpdater.h:39
void addIncoming(Value *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:687
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
This is the interface for a simple mod/ref and alias analysis over globals.
void Initialize(Type *Ty, StringRef Name)
Reset this object to get ready for a new set of SSA updates with type &#39;Ty&#39;.
Definition: SSAUpdater.cpp:54
bool isRecursivelyLCSSAForm(DominatorTree &DT, const LoopInfo &LI) const
Return true if this Loop and all inner subloops are in LCSSA form.
Definition: LoopInfo.cpp:182
bool isLCSSAForm(DominatorTree &DT) const
Return true if the Loop is in LCSSA form.
Definition: LoopInfo.cpp:175
void AddAvailableValue(BasicBlock *BB, Value *V)
Indicate that a rewritten value is available in the specified block with the specified value...
Definition: SSAUpdater.cpp:67
The main scalar evolution driver.
Pass * createLCSSAPass()
Definition: LCSSA.cpp:417
const Use & getOperandUse(unsigned i) const
Definition: User.h:183
bool all_of(R &&range, UnaryPredicate P)
Provide wrappers to std::all_of which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:846
STATISTIC(NumFunctions, "Total number of functions")
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:225
F(f)
static bool isExitBlock(BasicBlock *BB, const SmallVectorImpl< BasicBlock *> &ExitBlocks)
Return true if the specified block is in the list.
Definition: LCSSA.cpp:66
bool formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI, ScalarEvolution *SE)
Put a loop nest into LCSSA form.
Definition: LCSSA.cpp:338
static unsigned getOperandNumForIncomingValue(unsigned i)
AnalysisUsage & addRequired()
ArrayRef< BasicBlock * > get(BasicBlock *BB)
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:51
This is the interface for a SCEV-based alias analysis.
LoopT * getLoopFor(const BlockT *BB) const
Return the inner most loop that BB lives in.
Definition: LoopInfo.h:678
A Use represents the edge between a Value definition and its users.
Definition: Use.h:56
Analysis pass that exposes the LoopInfo for a function.
Definition: LoopInfo.h:933
BlockT * getHeader() const
Definition: LoopInfo.h:100
void insertDebugValuesForPHIs(BasicBlock *BB, SmallVectorImpl< PHINode *> &InsertedPHIs)
Propagate dbg.value intrinsics through the newly inserted PHIs.
Definition: Local.cpp:1360
void getExitBlocks(SmallVectorImpl< BlockT *> &ExitBlocks) const
Return all of the successor blocks of this loop.
Definition: LoopInfoImpl.h:63
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
bool insert(const value_type &X)
Insert a new element into the SetVector.
Definition: SetVector.h:142
PredIteratorCache - This class is an extremely trivial cache for predecessor iterator queries...
Memory SSA
Definition: MemorySSA.cpp:65
AnalysisUsage & addPreservedID(const void *ID)
static void ValueIsRAUWd(Value *Old, Value *New)
Definition: Value.cpp:918
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:142
NodeT * getBlock() const
static bool runOnFunction(Function &F, bool PostInlining)
bool formLCSSAForInstructions(SmallVectorImpl< Instruction *> &Worklist, DominatorTree &DT, LoopInfo &LI)
Ensures LCSSA form for every instruction from the Worklist in the scope of innermost containing loop...
Definition: LCSSA.cpp:74
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
size_t size(BasicBlock *BB) const
DomTreeNodeBase * getIDom() const
static cl::opt< bool, true > VerifyLoopLCSSAFlag("verify-loop-lcssa", cl::location(VerifyLoopLCSSA), cl::Hidden, cl::desc("Verify loop lcssa form (time consuming)"))
static bool VerifyLoopLCSSA
Definition: LCSSA.cpp:58
This file contains the declarations for the subclasses of Constant, which represent the different fla...
char & LCSSAID
Definition: LCSSA.cpp:418
Represent the analysis usage information of a pass.
Analysis pass providing a never-invalidated alias analysis result.
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:285
Analysis pass providing a never-invalidated alias analysis result.
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:159
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
char & LoopSimplifyID
static bool formLCSSAOnAllLoops(LoopInfo *LI, DominatorTree &DT, ScalarEvolution *SE)
Process all loops in the function, inner-most out.
Definition: LCSSA.cpp:351
bool formLCSSA(Loop &L, DominatorTree &DT, LoopInfo *LI, ScalarEvolution *SE)
Put loop into LCSSA form.
Definition: LCSSA.cpp:283
bool contains(const LoopT *L) const
Return true if the specified loop is contained within in this loop.
Definition: LoopInfo.h:110
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:298
Legacy wrapper pass to provide the SCEVAAResult object.
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:862
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:243
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:383
static PHINode * Create(Type *Ty, unsigned NumReservedValues, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Constructors - NumReservedValues is a hint for the number of incoming edges that this phi node will h...
void setPreservesCFG()
This function should be called by the pass, iff they do not:
Definition: Pass.cpp:285
unsigned getNumIncomingValues() const
Return the number of incoming edges.
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
Definition: LCSSA.cpp:430
Represents analyses that only rely on functions&#39; control flow.
Definition: PassManager.h:114
Analysis pass that exposes the ScalarEvolution for a function.
lcssa
Definition: LCSSA.cpp:414
const std::vector< LoopT * > & getSubLoops() const
Return the loops contained entirely within this loop.
Definition: LoopInfo.h:131
Analysis pass providing a never-invalidated alias analysis result.
static void computeBlocksDominatingExits(Loop &L, DominatorTree &DT, SmallVector< BasicBlock *, 8 > &ExitBlocks, SmallSetVector< BasicBlock *, 8 > &BlocksDominatingExits)
Definition: LCSSA.cpp:238
void forgetLoop(const Loop *L)
This method should be called by the client when it has changed a loop in a way that may effect Scalar...
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:61
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:439
bool isTokenTy() const
Return true if this is &#39;token&#39;.
Definition: Type.h:194
void preserveSet()
Mark an analysis set as preserved.
Definition: PassManager.h:189
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:224
#define I(x, y, z)
Definition: MD5.cpp:58
PassT::Result * getCachedResult(IRUnitT &IR) const
Get the cached result of an analysis pass for a given IR unit.
Definition: PassManager.h:706
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:174
INITIALIZE_PASS_BEGIN(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass", false, false) INITIALIZE_PASS_END(LCSSAWrapperPass
size_type count(const_arg_type_t< KeyT > Val) const
Return 1 if the specified key is in the map, 0 otherwise.
Definition: DenseMap.h:141
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
LLVM_NODISCARD char front() const
front - Get the first character in the string.
Definition: StringRef.h:142
The legacy pass manager&#39;s analysis pass to compute loop information.
Definition: LoopInfo.h:958
This is the interface for LLVM&#39;s primary stateless and local alias analysis.
A container for analyses that lazily runs them and caches their results.
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:254
A wrapper pass to provide the legacy pass manager access to a suitably prepared AAResults object...
void RewriteUse(Use &U)
Rewrite a use of the symbolic value.
Definition: SSAUpdater.cpp:185
LocationClass< Ty > location(Ty &L)
Definition: CommandLine.h:422
const BasicBlock * getParent() const
Definition: Instruction.h:67
bool HasValueForBlock(BasicBlock *BB) const
Return true if the SSAUpdater already has a value for the specified block.
Definition: SSAUpdater.cpp:63
Legacy wrapper pass to provide the BasicAAResult object.
bool is_contained(R &&Range, const E &Element)
Wrapper function around std::find to detect if an element exists in a container.
Definition: STLExtras.h:905