LLVM  6.0.0svn
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
59 static cl::opt<bool,true>
60 VerifyLoopLCSSAFlag("verify-loop-lcssa", cl::location(VerifyLoopLCSSA),
61  cl::desc("Verify loop lcssa form (time consuming)"));
62 
63 /// Return true if the specified block is in the list.
64 static bool isExitBlock(BasicBlock *BB,
65  const SmallVectorImpl<BasicBlock *> &ExitBlocks) {
66  return is_contained(ExitBlocks, BB);
67 }
68 
69 /// For every instruction from the worklist, check to see if it has any uses
70 /// that are outside the current loop. If so, insert LCSSA PHI nodes and
71 /// rewrite the uses.
73  DominatorTree &DT, LoopInfo &LI) {
74  SmallVector<Use *, 16> UsesToRewrite;
75  SmallSetVector<PHINode *, 16> PHIsToRemove;
76  PredIteratorCache PredCache;
77  bool Changed = false;
78 
79  // Cache the Loop ExitBlocks across this loop. We expect to get a lot of
80  // instructions within the same loops, computing the exit blocks is
81  // expensive, and we're not mutating the loop structure.
83 
84  while (!Worklist.empty()) {
85  UsesToRewrite.clear();
86 
87  Instruction *I = Worklist.pop_back_val();
88  assert(!I->getType()->isTokenTy() && "Tokens shouldn't be in the worklist");
89  BasicBlock *InstBB = I->getParent();
90  Loop *L = LI.getLoopFor(InstBB);
91  assert(L && "Instruction belongs to a BB that's not part of a loop");
92  if (!LoopExitBlocks.count(L))
93  L->getExitBlocks(LoopExitBlocks[L]);
94  assert(LoopExitBlocks.count(L));
95  const SmallVectorImpl<BasicBlock *> &ExitBlocks = LoopExitBlocks[L];
96 
97  if (ExitBlocks.empty())
98  continue;
99 
100  for (Use &U : I->uses()) {
101  Instruction *User = cast<Instruction>(U.getUser());
102  BasicBlock *UserBB = User->getParent();
103  if (auto *PN = dyn_cast<PHINode>(User))
104  UserBB = PN->getIncomingBlock(U);
105 
106  if (InstBB != UserBB && !L->contains(UserBB))
107  UsesToRewrite.push_back(&U);
108  }
109 
110  // If there are no uses outside the loop, exit with no change.
111  if (UsesToRewrite.empty())
112  continue;
113 
114  ++NumLCSSA; // We are applying the transformation
115 
116  // Invoke instructions are special in that their result value is not
117  // available along their unwind edge. The code below tests to see whether
118  // DomBB dominates the value, so adjust DomBB to the normal destination
119  // block, which is effectively where the value is first usable.
120  BasicBlock *DomBB = InstBB;
121  if (auto *Inv = dyn_cast<InvokeInst>(I))
122  DomBB = Inv->getNormalDest();
123 
124  DomTreeNode *DomNode = DT.getNode(DomBB);
125 
126  SmallVector<PHINode *, 16> AddedPHIs;
127  SmallVector<PHINode *, 8> PostProcessPHIs;
128 
129  SmallVector<PHINode *, 4> InsertedPHIs;
130  SSAUpdater SSAUpdate(&InsertedPHIs);
131  SSAUpdate.Initialize(I->getType(), I->getName());
132 
133  // Insert the LCSSA phi's into all of the exit blocks dominated by the
134  // value, and add them to the Phi's map.
135  for (BasicBlock *ExitBB : ExitBlocks) {
136  if (!DT.dominates(DomNode, DT.getNode(ExitBB)))
137  continue;
138 
139  // If we already inserted something for this BB, don't reprocess it.
140  if (SSAUpdate.HasValueForBlock(ExitBB))
141  continue;
142 
143  PHINode *PN = PHINode::Create(I->getType(), PredCache.size(ExitBB),
144  I->getName() + ".lcssa", &ExitBB->front());
145 
146  // Add inputs from inside the loop for this PHI.
147  for (BasicBlock *Pred : PredCache.get(ExitBB)) {
148  PN->addIncoming(I, Pred);
149 
150  // If the exit block has a predecessor not within the loop, arrange for
151  // the incoming value use corresponding to that predecessor to be
152  // rewritten in terms of a different LCSSA PHI.
153  if (!L->contains(Pred))
154  UsesToRewrite.push_back(
156  PN->getNumIncomingValues() - 1)));
157  }
158 
159  AddedPHIs.push_back(PN);
160 
161  // Remember that this phi makes the value alive in this block.
162  SSAUpdate.AddAvailableValue(ExitBB, PN);
163 
164  // LoopSimplify might fail to simplify some loops (e.g. when indirect
165  // branches are involved). In such situations, it might happen that an
166  // exit for Loop L1 is the header of a disjoint Loop L2. Thus, when we
167  // create PHIs in such an exit block, we are also inserting PHIs into L2's
168  // header. This could break LCSSA form for L2 because these inserted PHIs
169  // can also have uses outside of L2. Remember all PHIs in such situation
170  // as to revisit than later on. FIXME: Remove this if indirectbr support
171  // into LoopSimplify gets improved.
172  if (auto *OtherLoop = LI.getLoopFor(ExitBB))
173  if (!L->contains(OtherLoop))
174  PostProcessPHIs.push_back(PN);
175  }
176 
177  // Rewrite all uses outside the loop in terms of the new PHIs we just
178  // inserted.
179  for (Use *UseToRewrite : UsesToRewrite) {
180  // If this use is in an exit block, rewrite to use the newly inserted PHI.
181  // This is required for correctness because SSAUpdate doesn't handle uses
182  // in the same block. It assumes the PHI we inserted is at the end of the
183  // block.
184  Instruction *User = cast<Instruction>(UseToRewrite->getUser());
185  BasicBlock *UserBB = User->getParent();
186  if (auto *PN = dyn_cast<PHINode>(User))
187  UserBB = PN->getIncomingBlock(*UseToRewrite);
188 
189  if (isa<PHINode>(UserBB->begin()) && isExitBlock(UserBB, ExitBlocks)) {
190  // Tell the VHs that the uses changed. This updates SCEV's caches.
191  if (UseToRewrite->get()->hasValueHandle())
192  ValueHandleBase::ValueIsRAUWd(*UseToRewrite, &UserBB->front());
193  UseToRewrite->set(&UserBB->front());
194  continue;
195  }
196 
197  // Otherwise, do full PHI insertion.
198  SSAUpdate.RewriteUse(*UseToRewrite);
199  }
200 
201  // SSAUpdater might have inserted phi-nodes inside other loops. We'll need
202  // to post-process them to keep LCSSA form.
203  for (PHINode *InsertedPN : InsertedPHIs) {
204  if (auto *OtherLoop = LI.getLoopFor(InsertedPN->getParent()))
205  if (!L->contains(OtherLoop))
206  PostProcessPHIs.push_back(InsertedPN);
207  }
208 
209  // Post process PHI instructions that were inserted into another disjoint
210  // loop and update their exits properly.
211  for (auto *PostProcessPN : PostProcessPHIs)
212  if (!PostProcessPN->use_empty())
213  Worklist.push_back(PostProcessPN);
214 
215  // Keep track of PHI nodes that we want to remove because they did not have
216  // any uses rewritten.
217  for (PHINode *PN : AddedPHIs)
218  if (PN->use_empty())
219  PHIsToRemove.insert(PN);
220 
221  Changed = true;
222  }
223  // Remove PHI nodes that did not have any uses rewritten.
224  for (PHINode *PN : PHIsToRemove) {
225  assert (PN->use_empty() && "Trying to remove a phi with uses.");
226  PN->eraseFromParent();
227  }
228  return Changed;
229 }
230 
231 // Compute the set of BasicBlocks in the loop `L` dominating at least one exit.
233  Loop &L, DominatorTree &DT, SmallVector<BasicBlock *, 8> &ExitBlocks,
234  SmallSetVector<BasicBlock *, 8> &BlocksDominatingExits) {
235  SmallVector<BasicBlock *, 8> BBWorklist;
236 
237  // We start from the exit blocks, as every block trivially dominates itself
238  // (not strictly).
239  for (BasicBlock *BB : ExitBlocks)
240  BBWorklist.push_back(BB);
241 
242  while (!BBWorklist.empty()) {
243  BasicBlock *BB = BBWorklist.pop_back_val();
244 
245  // Check if this is a loop header. If this is the case, we're done.
246  if (L.getHeader() == BB)
247  continue;
248 
249  // Otherwise, add its immediate predecessor in the dominator tree to the
250  // worklist, unless we visited it already.
251  BasicBlock *IDomBB = DT.getNode(BB)->getIDom()->getBlock();
252 
253  // Exit blocks can have an immediate dominator not beloinging to the
254  // loop. For an exit block to be immediately dominated by another block
255  // outside the loop, it implies not all paths from that dominator, to the
256  // exit block, go through the loop.
257  // Example:
258  //
259  // |---- A
260  // | |
261  // | B<--
262  // | | |
263  // |---> C --
264  // |
265  // D
266  //
267  // C is the exit block of the loop and it's immediately dominated by A,
268  // which doesn't belong to the loop.
269  if (!L.contains(IDomBB))
270  continue;
271 
272  if (BlocksDominatingExits.insert(IDomBB))
273  BBWorklist.push_back(IDomBB);
274  }
275 }
276 
278  ScalarEvolution *SE) {
279  bool Changed = false;
280 
281  SmallVector<BasicBlock *, 8> ExitBlocks;
282  L.getExitBlocks(ExitBlocks);
283  if (ExitBlocks.empty())
284  return false;
285 
286  SmallSetVector<BasicBlock *, 8> BlocksDominatingExits;
287 
288  // We want to avoid use-scanning leveraging dominance informations.
289  // If a block doesn't dominate any of the loop exits, the none of the values
290  // defined in the loop can be used outside.
291  // We compute the set of blocks fullfilling the conditions in advance
292  // walking the dominator tree upwards until we hit a loop header.
293  computeBlocksDominatingExits(L, DT, ExitBlocks, BlocksDominatingExits);
294 
296 
297  // Look at all the instructions in the loop, checking to see if they have uses
298  // outside the loop. If so, put them into the worklist to rewrite those uses.
299  for (BasicBlock *BB : BlocksDominatingExits) {
300  for (Instruction &I : *BB) {
301  // Reject two common cases fast: instructions with no uses (like stores)
302  // and instructions with one use that is in the same block as this.
303  if (I.use_empty() ||
304  (I.hasOneUse() && I.user_back()->getParent() == BB &&
305  !isa<PHINode>(I.user_back())))
306  continue;
307 
308  // Tokens cannot be used in PHI nodes, so we skip over them.
309  // We can run into tokens which are live out of a loop with catchswitch
310  // instructions in Windows EH if the catchswitch has one catchpad which
311  // is inside the loop and another which is not.
312  if (I.getType()->isTokenTy())
313  continue;
314 
315  Worklist.push_back(&I);
316  }
317  }
318  Changed = formLCSSAForInstructions(Worklist, DT, *LI);
319 
320  // If we modified the code, remove any caches about the loop from SCEV to
321  // avoid dangling entries.
322  // FIXME: This is a big hammer, can we clear the cache more selectively?
323  if (SE && Changed)
324  SE->forgetLoop(&L);
325 
326  assert(L.isLCSSAForm(DT));
327 
328  return Changed;
329 }
330 
331 /// Process a loop nest depth first.
333  ScalarEvolution *SE) {
334  bool Changed = false;
335 
336  // Recurse depth-first through inner loops.
337  for (Loop *SubLoop : L.getSubLoops())
338  Changed |= formLCSSARecursively(*SubLoop, DT, LI, SE);
339 
340  Changed |= formLCSSA(L, DT, LI, SE);
341  return Changed;
342 }
343 
344 /// Process all loops in the function, inner-most out.
346  ScalarEvolution *SE) {
347  bool Changed = false;
348  for (auto &L : *LI)
349  Changed |= formLCSSARecursively(*L, DT, LI, SE);
350  return Changed;
351 }
352 
353 namespace {
354 struct LCSSAWrapperPass : public FunctionPass {
355  static char ID; // Pass identification, replacement for typeid
356  LCSSAWrapperPass() : FunctionPass(ID) {
358  }
359 
360  // Cached analysis information for the current function.
361  DominatorTree *DT;
362  LoopInfo *LI;
363  ScalarEvolution *SE;
364 
365  bool runOnFunction(Function &F) override;
366  void verifyAnalysis() const override {
367  // This check is very expensive. On the loop intensive compiles it may cause
368  // up to 10x slowdown. Currently it's disabled by default. LPPassManager
369  // always does limited form of the LCSSA verification. Similar reasoning
370  // was used for the LoopInfo verifier.
371  if (VerifyLoopLCSSA) {
372  assert(all_of(*LI,
373  [&](Loop *L) {
374  return L->isRecursivelyLCSSAForm(*DT, *LI);
375  }) &&
376  "LCSSA form is broken!");
377  }
378  };
379 
380  /// This transformation requires natural loop information & requires that
381  /// loop preheaders be inserted into the CFG. It maintains both of these,
382  /// as well as the CFG. It also requires dominator information.
383  void getAnalysisUsage(AnalysisUsage &AU) const override {
384  AU.setPreservesCFG();
385 
394 
395  // This is needed to perform LCSSA verification inside LPPassManager
398  }
399 };
400 }
401 
402 char LCSSAWrapperPass::ID = 0;
403 INITIALIZE_PASS_BEGIN(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
404  false, false)
408 INITIALIZE_PASS_END(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
409  false, false)
410 
411 Pass *llvm::createLCSSAPass() { return new LCSSAWrapperPass(); }
413 
414 /// Transform \p F into loop-closed SSA form.
416  LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
417  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
418  auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>();
419  SE = SEWP ? &SEWP->getSE() : nullptr;
420 
421  return formLCSSAOnAllLoops(LI, *DT, SE);
422 }
423 
425  auto &LI = AM.getResult<LoopAnalysis>(F);
426  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
427  auto *SE = AM.getCachedResult<ScalarEvolutionAnalysis>(F);
428  if (!formLCSSAOnAllLoops(&LI, DT, SE))
429  return PreservedAnalyses::all();
430 
432  PA.preserveSet<CFGAnalyses>();
433  PA.preserve<BasicAA>();
434  PA.preserve<GlobalsAA>();
435  PA.preserve<SCEVAA>();
437  return PA;
438 }
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:356
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:411
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:767
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:64
bool formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI, ScalarEvolution *SE)
Put a loop nest into LCSSA form.
Definition: LCSSA.cpp:332
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
static cl::opt< bool, true > VerifyLoopLCSSAFlag("verify-loop-lcssa", cl::location(VerifyLoopLCSSA), cl::desc("Verify loop lcssa form (time consuming)"))
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:908
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:72
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 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:412
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:345
bool formLCSSA(Loop &L, DominatorTree &DT, LoopInfo *LI, ScalarEvolution *SE)
Put loop into LCSSA form.
Definition: LCSSA.cpp:277
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:864
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:239
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:385
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:424
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:408
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:232
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:220
#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:187
LocationClass< Ty > location(Ty &L)
Definition: CommandLine.h:422
const BasicBlock * getParent() const
Definition: Instruction.h:66
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:821