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"
39 #include "llvm/IR/Constants.h"
40 #include "llvm/IR/Dominators.h"
41 #include "llvm/IR/Function.h"
42 #include "llvm/IR/Instructions.h"
44 #include "llvm/Pass.h"
45 #include "llvm/Transforms/Scalar.h"
48 using namespace llvm;
49 
50 #define DEBUG_TYPE "lcssa"
51 
52 STATISTIC(NumLCSSA, "Number of live out of a loop variables");
53 
54 #ifdef EXPENSIVE_CHECKS
55 static bool VerifyLoopLCSSA = true;
56 #else
57 static bool VerifyLoopLCSSA = false;
58 #endif
60  VerifyLoopLCSSAFlag("verify-loop-lcssa", cl::location(VerifyLoopLCSSA),
61  cl::Hidden,
62  cl::desc("Verify loop lcssa form (time consuming)"));
63 
64 /// Return true if the specified block is in the list.
65 static bool isExitBlock(BasicBlock *BB,
66  const SmallVectorImpl<BasicBlock *> &ExitBlocks) {
67  return is_contained(ExitBlocks, BB);
68 }
69 
70 /// For every instruction from the worklist, check to see if it has any uses
71 /// that are outside the current loop. If so, insert LCSSA PHI nodes and
72 /// rewrite the uses.
74  DominatorTree &DT, LoopInfo &LI) {
75  SmallVector<Use *, 16> UsesToRewrite;
76  SmallSetVector<PHINode *, 16> PHIsToRemove;
77  PredIteratorCache PredCache;
78  bool Changed = false;
79 
80  // Cache the Loop ExitBlocks across this loop. We expect to get a lot of
81  // instructions within the same loops, computing the exit blocks is
82  // expensive, and we're not mutating the loop structure.
84 
85  while (!Worklist.empty()) {
86  UsesToRewrite.clear();
87 
88  Instruction *I = Worklist.pop_back_val();
89  assert(!I->getType()->isTokenTy() && "Tokens shouldn't be in the worklist");
90  BasicBlock *InstBB = I->getParent();
91  Loop *L = LI.getLoopFor(InstBB);
92  assert(L && "Instruction belongs to a BB that's not part of a loop");
93  if (!LoopExitBlocks.count(L))
94  L->getExitBlocks(LoopExitBlocks[L]);
95  assert(LoopExitBlocks.count(L));
96  const SmallVectorImpl<BasicBlock *> &ExitBlocks = LoopExitBlocks[L];
97 
98  if (ExitBlocks.empty())
99  continue;
100 
101  for (Use &U : I->uses()) {
102  Instruction *User = cast<Instruction>(U.getUser());
103  BasicBlock *UserBB = User->getParent();
104  if (auto *PN = dyn_cast<PHINode>(User))
105  UserBB = PN->getIncomingBlock(U);
106 
107  if (InstBB != UserBB && !L->contains(UserBB))
108  UsesToRewrite.push_back(&U);
109  }
110 
111  // If there are no uses outside the loop, exit with no change.
112  if (UsesToRewrite.empty())
113  continue;
114 
115  ++NumLCSSA; // We are applying the transformation
116 
117  // Invoke instructions are special in that their result value is not
118  // available along their unwind edge. The code below tests to see whether
119  // DomBB dominates the value, so adjust DomBB to the normal destination
120  // block, which is effectively where the value is first usable.
121  BasicBlock *DomBB = InstBB;
122  if (auto *Inv = dyn_cast<InvokeInst>(I))
123  DomBB = Inv->getNormalDest();
124 
125  DomTreeNode *DomNode = DT.getNode(DomBB);
126 
127  SmallVector<PHINode *, 16> AddedPHIs;
128  SmallVector<PHINode *, 8> PostProcessPHIs;
129 
130  SmallVector<PHINode *, 4> InsertedPHIs;
131  SSAUpdater SSAUpdate(&InsertedPHIs);
132  SSAUpdate.Initialize(I->getType(), I->getName());
133 
134  // Insert the LCSSA phi's into all of the exit blocks dominated by the
135  // value, and add them to the Phi's map.
136  for (BasicBlock *ExitBB : ExitBlocks) {
137  if (!DT.dominates(DomNode, DT.getNode(ExitBB)))
138  continue;
139 
140  // If we already inserted something for this BB, don't reprocess it.
141  if (SSAUpdate.HasValueForBlock(ExitBB))
142  continue;
143 
144  PHINode *PN = PHINode::Create(I->getType(), PredCache.size(ExitBB),
145  I->getName() + ".lcssa", &ExitBB->front());
146 
147  // Add inputs from inside the loop for this PHI.
148  for (BasicBlock *Pred : PredCache.get(ExitBB)) {
149  PN->addIncoming(I, Pred);
150 
151  // If the exit block has a predecessor not within the loop, arrange for
152  // the incoming value use corresponding to that predecessor to be
153  // rewritten in terms of a different LCSSA PHI.
154  if (!L->contains(Pred))
155  UsesToRewrite.push_back(
157  PN->getNumIncomingValues() - 1)));
158  }
159 
160  AddedPHIs.push_back(PN);
161 
162  // Remember that this phi makes the value alive in this block.
163  SSAUpdate.AddAvailableValue(ExitBB, PN);
164 
165  // LoopSimplify might fail to simplify some loops (e.g. when indirect
166  // branches are involved). In such situations, it might happen that an
167  // exit for Loop L1 is the header of a disjoint Loop L2. Thus, when we
168  // create PHIs in such an exit block, we are also inserting PHIs into L2's
169  // header. This could break LCSSA form for L2 because these inserted PHIs
170  // can also have uses outside of L2. Remember all PHIs in such situation
171  // as to revisit than later on. FIXME: Remove this if indirectbr support
172  // into LoopSimplify gets improved.
173  if (auto *OtherLoop = LI.getLoopFor(ExitBB))
174  if (!L->contains(OtherLoop))
175  PostProcessPHIs.push_back(PN);
176  }
177 
178  // Rewrite all uses outside the loop in terms of the new PHIs we just
179  // inserted.
180  for (Use *UseToRewrite : UsesToRewrite) {
181  // If this use is in an exit block, rewrite to use the newly inserted PHI.
182  // This is required for correctness because SSAUpdate doesn't handle uses
183  // in the same block. It assumes the PHI we inserted is at the end of the
184  // block.
185  Instruction *User = cast<Instruction>(UseToRewrite->getUser());
186  BasicBlock *UserBB = User->getParent();
187  if (auto *PN = dyn_cast<PHINode>(User))
188  UserBB = PN->getIncomingBlock(*UseToRewrite);
189 
190  if (isa<PHINode>(UserBB->begin()) && isExitBlock(UserBB, ExitBlocks)) {
191  // Tell the VHs that the uses changed. This updates SCEV's caches.
192  if (UseToRewrite->get()->hasValueHandle())
193  ValueHandleBase::ValueIsRAUWd(*UseToRewrite, &UserBB->front());
194  UseToRewrite->set(&UserBB->front());
195  continue;
196  }
197 
198  // Otherwise, do full PHI insertion.
199  SSAUpdate.RewriteUse(*UseToRewrite);
200  }
201 
202  // SSAUpdater might have inserted phi-nodes inside other loops. We'll need
203  // to post-process them to keep LCSSA form.
204  for (PHINode *InsertedPN : InsertedPHIs) {
205  if (auto *OtherLoop = LI.getLoopFor(InsertedPN->getParent()))
206  if (!L->contains(OtherLoop))
207  PostProcessPHIs.push_back(InsertedPN);
208  }
209 
210  // Post process PHI instructions that were inserted into another disjoint
211  // loop and update their exits properly.
212  for (auto *PostProcessPN : PostProcessPHIs)
213  if (!PostProcessPN->use_empty())
214  Worklist.push_back(PostProcessPN);
215 
216  // Keep track of PHI nodes that we want to remove because they did not have
217  // any uses rewritten.
218  for (PHINode *PN : AddedPHIs)
219  if (PN->use_empty())
220  PHIsToRemove.insert(PN);
221 
222  Changed = true;
223  }
224  // Remove PHI nodes that did not have any uses rewritten.
225  for (PHINode *PN : PHIsToRemove) {
226  assert (PN->use_empty() && "Trying to remove a phi with uses.");
227  PN->eraseFromParent();
228  }
229  return Changed;
230 }
231 
232 // Compute the set of BasicBlocks in the loop `L` dominating at least one exit.
234  Loop &L, DominatorTree &DT, SmallVector<BasicBlock *, 8> &ExitBlocks,
235  SmallSetVector<BasicBlock *, 8> &BlocksDominatingExits) {
236  SmallVector<BasicBlock *, 8> BBWorklist;
237 
238  // We start from the exit blocks, as every block trivially dominates itself
239  // (not strictly).
240  for (BasicBlock *BB : ExitBlocks)
241  BBWorklist.push_back(BB);
242 
243  while (!BBWorklist.empty()) {
244  BasicBlock *BB = BBWorklist.pop_back_val();
245 
246  // Check if this is a loop header. If this is the case, we're done.
247  if (L.getHeader() == BB)
248  continue;
249 
250  // Otherwise, add its immediate predecessor in the dominator tree to the
251  // worklist, unless we visited it already.
252  BasicBlock *IDomBB = DT.getNode(BB)->getIDom()->getBlock();
253 
254  // Exit blocks can have an immediate dominator not beloinging to the
255  // loop. For an exit block to be immediately dominated by another block
256  // outside the loop, it implies not all paths from that dominator, to the
257  // exit block, go through the loop.
258  // Example:
259  //
260  // |---- A
261  // | |
262  // | B<--
263  // | | |
264  // |---> C --
265  // |
266  // D
267  //
268  // C is the exit block of the loop and it's immediately dominated by A,
269  // which doesn't belong to the loop.
270  if (!L.contains(IDomBB))
271  continue;
272 
273  if (BlocksDominatingExits.insert(IDomBB))
274  BBWorklist.push_back(IDomBB);
275  }
276 }
277 
279  ScalarEvolution *SE) {
280  bool Changed = false;
281 
282  SmallVector<BasicBlock *, 8> ExitBlocks;
283  L.getExitBlocks(ExitBlocks);
284  if (ExitBlocks.empty())
285  return false;
286 
287  SmallSetVector<BasicBlock *, 8> BlocksDominatingExits;
288 
289  // We want to avoid use-scanning leveraging dominance informations.
290  // If a block doesn't dominate any of the loop exits, the none of the values
291  // defined in the loop can be used outside.
292  // We compute the set of blocks fullfilling the conditions in advance
293  // walking the dominator tree upwards until we hit a loop header.
294  computeBlocksDominatingExits(L, DT, ExitBlocks, BlocksDominatingExits);
295 
297 
298  // Look at all the instructions in the loop, checking to see if they have uses
299  // outside the loop. If so, put them into the worklist to rewrite those uses.
300  for (BasicBlock *BB : BlocksDominatingExits) {
301  for (Instruction &I : *BB) {
302  // Reject two common cases fast: instructions with no uses (like stores)
303  // and instructions with one use that is in the same block as this.
304  if (I.use_empty() ||
305  (I.hasOneUse() && I.user_back()->getParent() == BB &&
306  !isa<PHINode>(I.user_back())))
307  continue;
308 
309  // Tokens cannot be used in PHI nodes, so we skip over them.
310  // We can run into tokens which are live out of a loop with catchswitch
311  // instructions in Windows EH if the catchswitch has one catchpad which
312  // is inside the loop and another which is not.
313  if (I.getType()->isTokenTy())
314  continue;
315 
316  Worklist.push_back(&I);
317  }
318  }
319  Changed = formLCSSAForInstructions(Worklist, DT, *LI);
320 
321  // If we modified the code, remove any caches about the loop from SCEV to
322  // avoid dangling entries.
323  // FIXME: This is a big hammer, can we clear the cache more selectively?
324  if (SE && Changed)
325  SE->forgetLoop(&L);
326 
327  assert(L.isLCSSAForm(DT));
328 
329  return Changed;
330 }
331 
332 /// Process a loop nest depth first.
334  ScalarEvolution *SE) {
335  bool Changed = false;
336 
337  // Recurse depth-first through inner loops.
338  for (Loop *SubLoop : L.getSubLoops())
339  Changed |= formLCSSARecursively(*SubLoop, DT, LI, SE);
340 
341  Changed |= formLCSSA(L, DT, LI, SE);
342  return Changed;
343 }
344 
345 /// Process all loops in the function, inner-most out.
347  ScalarEvolution *SE) {
348  bool Changed = false;
349  for (auto &L : *LI)
350  Changed |= formLCSSARecursively(*L, DT, LI, SE);
351  return Changed;
352 }
353 
354 namespace {
355 struct LCSSAWrapperPass : public FunctionPass {
356  static char ID; // Pass identification, replacement for typeid
357  LCSSAWrapperPass() : FunctionPass(ID) {
359  }
360 
361  // Cached analysis information for the current function.
362  DominatorTree *DT;
363  LoopInfo *LI;
364  ScalarEvolution *SE;
365 
366  bool runOnFunction(Function &F) override;
367  void verifyAnalysis() const override {
368  // This check is very expensive. On the loop intensive compiles it may cause
369  // up to 10x slowdown. Currently it's disabled by default. LPPassManager
370  // always does limited form of the LCSSA verification. Similar reasoning
371  // was used for the LoopInfo verifier.
372  if (VerifyLoopLCSSA) {
373  assert(all_of(*LI,
374  [&](Loop *L) {
375  return L->isRecursivelyLCSSAForm(*DT, *LI);
376  }) &&
377  "LCSSA form is broken!");
378  }
379  };
380 
381  /// This transformation requires natural loop information & requires that
382  /// loop preheaders be inserted into the CFG. It maintains both of these,
383  /// as well as the CFG. It also requires dominator information.
384  void getAnalysisUsage(AnalysisUsage &AU) const override {
385  AU.setPreservesCFG();
386 
395 
396  // This is needed to perform LCSSA verification inside LPPassManager
399  }
400 };
401 }
402 
403 char LCSSAWrapperPass::ID = 0;
404 INITIALIZE_PASS_BEGIN(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
405  false, false)
409 INITIALIZE_PASS_END(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
410  false, false)
411 
412 Pass *llvm::createLCSSAPass() { return new LCSSAWrapperPass(); }
414 
415 /// Transform \p F into loop-closed SSA form.
417  LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
418  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
419  auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>();
420  SE = SEWP ? &SEWP->getSE() : nullptr;
421 
422  return formLCSSAOnAllLoops(LI, *DT, SE);
423 }
424 
426  auto &LI = AM.getResult<LoopAnalysis>(F);
427  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
428  auto *SE = AM.getCachedResult<ScalarEvolutionAnalysis>(F);
429  if (!formLCSSAOnAllLoops(&LI, DT, SE))
430  return PreservedAnalyses::all();
431 
433  PA.preserveSet<CFGAnalyses>();
434  PA.preserve<BasicAA>();
435  PA.preserve<GlobalsAA>();
436  PA.preserve<SCEVAA>();
438  return PA;
439 }
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:412
const Use & getOperandUse(unsigned i) const
Definition: User.h:167
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:814
STATISTIC(NumFunctions, "Total number of functions")
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:238
F(f)
static bool isExitBlock(BasicBlock *BB, const SmallVectorImpl< BasicBlock *> &ExitBlocks)
Return true if the specified block is in the list.
Definition: LCSSA.cpp:65
bool formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI, ScalarEvolution *SE)
Put a loop nest into LCSSA form.
Definition: LCSSA.cpp:333
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 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:140
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:73
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:57
This file contains the declarations for the subclasses of Constant, which represent the different fla...
char & LCSSAID
Definition: LCSSA.cpp:413
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:346
bool formLCSSA(Loop &L, DominatorTree &DT, LoopInfo *LI, ScalarEvolution *SE)
Put loop into LCSSA form.
Definition: LCSSA.cpp:278
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:240
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:425
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:409
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:233
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:267
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:873