LLVM  8.0.0svn
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"
44 #include "llvm/IR/IntrinsicInst.h"
46 #include "llvm/Pass.h"
47 #include "llvm/Transforms/Utils.h"
50 using namespace llvm;
51 
52 #define DEBUG_TYPE "lcssa"
53 
54 STATISTIC(NumLCSSA, "Number of live out of a loop variables");
55 
56 #ifdef EXPENSIVE_CHECKS
57 static bool VerifyLoopLCSSA = true;
58 #else
59 static bool VerifyLoopLCSSA = false;
60 #endif
62  VerifyLoopLCSSAFlag("verify-loop-lcssa", cl::location(VerifyLoopLCSSA),
63  cl::Hidden,
64  cl::desc("Verify loop lcssa form (time consuming)"));
65 
66 /// Return true if the specified block is in the list.
67 static bool isExitBlock(BasicBlock *BB,
68  const SmallVectorImpl<BasicBlock *> &ExitBlocks) {
69  return is_contained(ExitBlocks, BB);
70 }
71 
72 /// For every instruction from the worklist, check to see if it has any uses
73 /// that are outside the current loop. If so, insert LCSSA PHI nodes and
74 /// rewrite the uses.
76  DominatorTree &DT, LoopInfo &LI) {
77  SmallVector<Use *, 16> UsesToRewrite;
78  SmallSetVector<PHINode *, 16> PHIsToRemove;
79  PredIteratorCache PredCache;
80  bool Changed = false;
81 
82  // Cache the Loop ExitBlocks across this loop. We expect to get a lot of
83  // instructions within the same loops, computing the exit blocks is
84  // expensive, and we're not mutating the loop structure.
86 
87  while (!Worklist.empty()) {
88  UsesToRewrite.clear();
89 
90  Instruction *I = Worklist.pop_back_val();
91  assert(!I->getType()->isTokenTy() && "Tokens shouldn't be in the worklist");
92  BasicBlock *InstBB = I->getParent();
93  Loop *L = LI.getLoopFor(InstBB);
94  assert(L && "Instruction belongs to a BB that's not part of a loop");
95  if (!LoopExitBlocks.count(L))
96  L->getExitBlocks(LoopExitBlocks[L]);
97  assert(LoopExitBlocks.count(L));
98  const SmallVectorImpl<BasicBlock *> &ExitBlocks = LoopExitBlocks[L];
99 
100  if (ExitBlocks.empty())
101  continue;
102 
103  for (Use &U : I->uses()) {
104  Instruction *User = cast<Instruction>(U.getUser());
105  BasicBlock *UserBB = User->getParent();
106  if (auto *PN = dyn_cast<PHINode>(User))
107  UserBB = PN->getIncomingBlock(U);
108 
109  if (InstBB != UserBB && !L->contains(UserBB))
110  UsesToRewrite.push_back(&U);
111  }
112 
113  // If there are no uses outside the loop, exit with no change.
114  if (UsesToRewrite.empty())
115  continue;
116 
117  ++NumLCSSA; // We are applying the transformation
118 
119  // Invoke instructions are special in that their result value is not
120  // available along their unwind edge. The code below tests to see whether
121  // DomBB dominates the value, so adjust DomBB to the normal destination
122  // block, which is effectively where the value is first usable.
123  BasicBlock *DomBB = InstBB;
124  if (auto *Inv = dyn_cast<InvokeInst>(I))
125  DomBB = Inv->getNormalDest();
126 
127  DomTreeNode *DomNode = DT.getNode(DomBB);
128 
129  SmallVector<PHINode *, 16> AddedPHIs;
130  SmallVector<PHINode *, 8> PostProcessPHIs;
131 
132  SmallVector<PHINode *, 4> InsertedPHIs;
133  SSAUpdater SSAUpdate(&InsertedPHIs);
134  SSAUpdate.Initialize(I->getType(), I->getName());
135 
136  // Insert the LCSSA phi's into all of the exit blocks dominated by the
137  // value, and add them to the Phi's map.
138  for (BasicBlock *ExitBB : ExitBlocks) {
139  if (!DT.dominates(DomNode, DT.getNode(ExitBB)))
140  continue;
141 
142  // If we already inserted something for this BB, don't reprocess it.
143  if (SSAUpdate.HasValueForBlock(ExitBB))
144  continue;
145 
146  PHINode *PN = PHINode::Create(I->getType(), PredCache.size(ExitBB),
147  I->getName() + ".lcssa", &ExitBB->front());
148  // Get the debug location from the original instruction.
149  PN->setDebugLoc(I->getDebugLoc());
150  // Add inputs from inside the loop for this PHI.
151  for (BasicBlock *Pred : PredCache.get(ExitBB)) {
152  PN->addIncoming(I, Pred);
153 
154  // If the exit block has a predecessor not within the loop, arrange for
155  // the incoming value use corresponding to that predecessor to be
156  // rewritten in terms of a different LCSSA PHI.
157  if (!L->contains(Pred))
158  UsesToRewrite.push_back(
160  PN->getNumIncomingValues() - 1)));
161  }
162 
163  AddedPHIs.push_back(PN);
164 
165  // Remember that this phi makes the value alive in this block.
166  SSAUpdate.AddAvailableValue(ExitBB, PN);
167 
168  // LoopSimplify might fail to simplify some loops (e.g. when indirect
169  // branches are involved). In such situations, it might happen that an
170  // exit for Loop L1 is the header of a disjoint Loop L2. Thus, when we
171  // create PHIs in such an exit block, we are also inserting PHIs into L2's
172  // header. This could break LCSSA form for L2 because these inserted PHIs
173  // can also have uses outside of L2. Remember all PHIs in such situation
174  // as to revisit than later on. FIXME: Remove this if indirectbr support
175  // into LoopSimplify gets improved.
176  if (auto *OtherLoop = LI.getLoopFor(ExitBB))
177  if (!L->contains(OtherLoop))
178  PostProcessPHIs.push_back(PN);
179  }
180 
181  // Rewrite all uses outside the loop in terms of the new PHIs we just
182  // inserted.
183  for (Use *UseToRewrite : UsesToRewrite) {
184  // If this use is in an exit block, rewrite to use the newly inserted PHI.
185  // This is required for correctness because SSAUpdate doesn't handle uses
186  // in the same block. It assumes the PHI we inserted is at the end of the
187  // block.
188  Instruction *User = cast<Instruction>(UseToRewrite->getUser());
189  BasicBlock *UserBB = User->getParent();
190  if (auto *PN = dyn_cast<PHINode>(User))
191  UserBB = PN->getIncomingBlock(*UseToRewrite);
192 
193  if (isa<PHINode>(UserBB->begin()) && isExitBlock(UserBB, ExitBlocks)) {
194  // Tell the VHs that the uses changed. This updates SCEV's caches.
195  if (UseToRewrite->get()->hasValueHandle())
196  ValueHandleBase::ValueIsRAUWd(*UseToRewrite, &UserBB->front());
197  UseToRewrite->set(&UserBB->front());
198  continue;
199  }
200 
201  // Otherwise, do full PHI insertion.
202  SSAUpdate.RewriteUse(*UseToRewrite);
203  }
204 
206  llvm::findDbgValues(DbgValues, I);
207 
208  // Update pre-existing debug value uses that reside outside the loop.
209  auto &Ctx = I->getContext();
210  for (auto DVI : DbgValues) {
211  BasicBlock *UserBB = DVI->getParent();
212  if (InstBB == UserBB || L->contains(UserBB))
213  continue;
214  // We currently only handle debug values residing in blocks where we have
215  // inserted a PHI instruction.
216  if (Value *V = SSAUpdate.FindValueForBlock(UserBB))
218  }
219 
220  // SSAUpdater might have inserted phi-nodes inside other loops. We'll need
221  // to post-process them to keep LCSSA form.
222  for (PHINode *InsertedPN : InsertedPHIs) {
223  if (auto *OtherLoop = LI.getLoopFor(InsertedPN->getParent()))
224  if (!L->contains(OtherLoop))
225  PostProcessPHIs.push_back(InsertedPN);
226  }
227 
228  // Post process PHI instructions that were inserted into another disjoint
229  // loop and update their exits properly.
230  for (auto *PostProcessPN : PostProcessPHIs)
231  if (!PostProcessPN->use_empty())
232  Worklist.push_back(PostProcessPN);
233 
234  // Keep track of PHI nodes that we want to remove because they did not have
235  // any uses rewritten. If the new PHI is used, store it so that we can
236  // try to propagate dbg.value intrinsics to it.
237  SmallVector<PHINode *, 2> NeedDbgValues;
238  for (PHINode *PN : AddedPHIs)
239  if (PN->use_empty())
240  PHIsToRemove.insert(PN);
241  else
242  NeedDbgValues.push_back(PN);
243  insertDebugValuesForPHIs(InstBB, NeedDbgValues);
244  Changed = true;
245  }
246  // Remove PHI nodes that did not have any uses rewritten. We need to redo the
247  // use_empty() check here, because even if the PHI node wasn't used when added
248  // to PHIsToRemove, later added PHI nodes can be using it. This cleanup is
249  // not guaranteed to handle trees/cycles of PHI nodes that only are used by
250  // each other. Such situations has only been noticed when the input IR
251  // contains unreachable code, and leaving some extra redundant PHI nodes in
252  // such situations is considered a minor problem.
253  for (PHINode *PN : PHIsToRemove)
254  if (PN->use_empty())
255  PN->eraseFromParent();
256  return Changed;
257 }
258 
259 // Compute the set of BasicBlocks in the loop `L` dominating at least one exit.
261  Loop &L, DominatorTree &DT, SmallVector<BasicBlock *, 8> &ExitBlocks,
262  SmallSetVector<BasicBlock *, 8> &BlocksDominatingExits) {
263  SmallVector<BasicBlock *, 8> BBWorklist;
264 
265  // We start from the exit blocks, as every block trivially dominates itself
266  // (not strictly).
267  for (BasicBlock *BB : ExitBlocks)
268  BBWorklist.push_back(BB);
269 
270  while (!BBWorklist.empty()) {
271  BasicBlock *BB = BBWorklist.pop_back_val();
272 
273  // Check if this is a loop header. If this is the case, we're done.
274  if (L.getHeader() == BB)
275  continue;
276 
277  // Otherwise, add its immediate predecessor in the dominator tree to the
278  // worklist, unless we visited it already.
279  BasicBlock *IDomBB = DT.getNode(BB)->getIDom()->getBlock();
280 
281  // Exit blocks can have an immediate dominator not beloinging to the
282  // loop. For an exit block to be immediately dominated by another block
283  // outside the loop, it implies not all paths from that dominator, to the
284  // exit block, go through the loop.
285  // Example:
286  //
287  // |---- A
288  // | |
289  // | B<--
290  // | | |
291  // |---> C --
292  // |
293  // D
294  //
295  // C is the exit block of the loop and it's immediately dominated by A,
296  // which doesn't belong to the loop.
297  if (!L.contains(IDomBB))
298  continue;
299 
300  if (BlocksDominatingExits.insert(IDomBB))
301  BBWorklist.push_back(IDomBB);
302  }
303 }
304 
306  ScalarEvolution *SE) {
307  bool Changed = false;
308 
309  SmallVector<BasicBlock *, 8> ExitBlocks;
310  L.getExitBlocks(ExitBlocks);
311  if (ExitBlocks.empty())
312  return false;
313 
314  SmallSetVector<BasicBlock *, 8> BlocksDominatingExits;
315 
316  // We want to avoid use-scanning leveraging dominance informations.
317  // If a block doesn't dominate any of the loop exits, the none of the values
318  // defined in the loop can be used outside.
319  // We compute the set of blocks fullfilling the conditions in advance
320  // walking the dominator tree upwards until we hit a loop header.
321  computeBlocksDominatingExits(L, DT, ExitBlocks, BlocksDominatingExits);
322 
324 
325  // Look at all the instructions in the loop, checking to see if they have uses
326  // outside the loop. If so, put them into the worklist to rewrite those uses.
327  for (BasicBlock *BB : BlocksDominatingExits) {
328  for (Instruction &I : *BB) {
329  // Reject two common cases fast: instructions with no uses (like stores)
330  // and instructions with one use that is in the same block as this.
331  if (I.use_empty() ||
332  (I.hasOneUse() && I.user_back()->getParent() == BB &&
333  !isa<PHINode>(I.user_back())))
334  continue;
335 
336  // Tokens cannot be used in PHI nodes, so we skip over them.
337  // We can run into tokens which are live out of a loop with catchswitch
338  // instructions in Windows EH if the catchswitch has one catchpad which
339  // is inside the loop and another which is not.
340  if (I.getType()->isTokenTy())
341  continue;
342 
343  Worklist.push_back(&I);
344  }
345  }
346  Changed = formLCSSAForInstructions(Worklist, DT, *LI);
347 
348  // If we modified the code, remove any caches about the loop from SCEV to
349  // avoid dangling entries.
350  // FIXME: This is a big hammer, can we clear the cache more selectively?
351  if (SE && Changed)
352  SE->forgetLoop(&L);
353 
354  assert(L.isLCSSAForm(DT));
355 
356  return Changed;
357 }
358 
359 /// Process a loop nest depth first.
361  ScalarEvolution *SE) {
362  bool Changed = false;
363 
364  // Recurse depth-first through inner loops.
365  for (Loop *SubLoop : L.getSubLoops())
366  Changed |= formLCSSARecursively(*SubLoop, DT, LI, SE);
367 
368  Changed |= formLCSSA(L, DT, LI, SE);
369  return Changed;
370 }
371 
372 /// Process all loops in the function, inner-most out.
374  ScalarEvolution *SE) {
375  bool Changed = false;
376  for (auto &L : *LI)
377  Changed |= formLCSSARecursively(*L, DT, LI, SE);
378  return Changed;
379 }
380 
381 namespace {
382 struct LCSSAWrapperPass : public FunctionPass {
383  static char ID; // Pass identification, replacement for typeid
384  LCSSAWrapperPass() : FunctionPass(ID) {
386  }
387 
388  // Cached analysis information for the current function.
389  DominatorTree *DT;
390  LoopInfo *LI;
391  ScalarEvolution *SE;
392 
393  bool runOnFunction(Function &F) override;
394  void verifyAnalysis() const override {
395  // This check is very expensive. On the loop intensive compiles it may cause
396  // up to 10x slowdown. Currently it's disabled by default. LPPassManager
397  // always does limited form of the LCSSA verification. Similar reasoning
398  // was used for the LoopInfo verifier.
399  if (VerifyLoopLCSSA) {
400  assert(all_of(*LI,
401  [&](Loop *L) {
402  return L->isRecursivelyLCSSAForm(*DT, *LI);
403  }) &&
404  "LCSSA form is broken!");
405  }
406  };
407 
408  /// This transformation requires natural loop information & requires that
409  /// loop preheaders be inserted into the CFG. It maintains both of these,
410  /// as well as the CFG. It also requires dominator information.
411  void getAnalysisUsage(AnalysisUsage &AU) const override {
412  AU.setPreservesCFG();
413 
422 
423  // This is needed to perform LCSSA verification inside LPPassManager
426  }
427 };
428 }
429 
430 char LCSSAWrapperPass::ID = 0;
431 INITIALIZE_PASS_BEGIN(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
432  false, false)
436 INITIALIZE_PASS_END(LCSSAWrapperPass, "lcssa", "Loop-Closed SSA Form Pass",
437  false, false)
438 
439 Pass *llvm::createLCSSAPass() { return new LCSSAWrapperPass(); }
441 
442 /// Transform \p F into loop-closed SSA form.
444  LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
445  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
446  auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>();
447  SE = SEWP ? &SEWP->getSE() : nullptr;
448 
449  return formLCSSAOnAllLoops(LI, *DT, SE);
450 }
451 
453  auto &LI = AM.getResult<LoopAnalysis>(F);
454  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
455  auto *SE = AM.getCachedResult<ScalarEvolutionAnalysis>(F);
456  if (!formLCSSAOnAllLoops(&LI, DT, SE))
457  return PreservedAnalyses::all();
458 
460  PA.preserveSet<CFGAnalyses>();
461  PA.preserve<BasicAA>();
462  PA.preserve<GlobalsAA>();
463  PA.preserve<SCEVAA>();
465  return PA;
466 }
Legacy wrapper pass to provide the GlobalsAAResult object.
Pass interface - Implemented by all &#39;passes&#39;.
Definition: Pass.h:81
void initializeLCSSAWrapperPassPass(PassRegistry &)
iterator_range< use_iterator > uses()
Definition: Value.h:355
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:770
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:184
bool isLCSSAForm(DominatorTree &DT) const
Return true if the Loop is in LCSSA form.
Definition: LoopInfo.cpp:177
void AddAvailableValue(BasicBlock *BB, Value *V)
Indicate that a rewritten value is available in the specified block with the specified value...
Definition: SSAUpdater.cpp:72
The main scalar evolution driver.
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:714
Pass * createLCSSAPass()
Definition: LCSSA.cpp:439
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:1042
STATISTIC(NumFunctions, "Total number of functions")
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:231
F(f)
static bool isExitBlock(BasicBlock *BB, const SmallVectorImpl< BasicBlock *> &ExitBlocks)
Return true if the specified block is in the list.
Definition: LCSSA.cpp:67
bool formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI, ScalarEvolution *SE)
Put a loop nest into LCSSA form.
Definition: LCSSA.cpp:360
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:684
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:939
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:1447
void getExitBlocks(SmallVectorImpl< BlockT *> &ExitBlocks) const
Return all of the successor blocks of this loop.
Definition: LoopInfoImpl.h:63
void findDbgValues(SmallVectorImpl< DbgValueInst *> &DbgValues, Value *V)
Finds the llvm.dbg.value intrinsics describing a value.
Definition: Local.cpp:1513
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:66
AnalysisUsage & addPreservedID(const void *ID)
static void ValueIsRAUWd(Value *Old, Value *New)
Definition: Value.cpp:894
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:145
Value * FindValueForBlock(BasicBlock *BB) const
Return the value for the specified block if the SSAUpdater has one, otherwise return nullptr...
Definition: SSAUpdater.cpp:67
static MetadataAsValue * get(LLVMContext &Context, Metadata *MD)
Definition: Metadata.cpp:106
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:75
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:154
void setDebugLoc(DebugLoc Loc)
Set the debug location information for this instruction.
Definition: Instruction.h:304
LLVM Basic Block Representation.
Definition: BasicBlock.h:58
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:59
This file contains the declarations for the subclasses of Constant, which represent the different fla...
char & LCSSAID
Definition: LCSSA.cpp:440
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:160
DomTreeNodeBase< NodeT > * getNode(const NodeT *BB) const
getNode - return the (Post)DominatorTree node for the specified basic block.
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:373
bool formLCSSA(Loop &L, DominatorTree &DT, LoopInfo *LI, ScalarEvolution *SE)
Put loop into LCSSA form.
Definition: LCSSA.cpp:305
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.
static ValueAsMetadata * get(Value *V)
Definition: Metadata.cpp:349
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:847
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:249
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:381
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:286
unsigned getNumIncomingValues() const
Return the number of incoming edges.
void setOperand(unsigned i, Value *Val)
Definition: User.h:175
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
Definition: LCSSA.cpp:452
Represents analyses that only rely on functions&#39; control flow.
Definition: PassManager.h:115
Analysis pass that exposes the ScalarEvolution for a function.
lcssa
Definition: LCSSA.cpp:436
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.
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:307
static void computeBlocksDominatingExits(Loop &L, DominatorTree &DT, SmallVector< BasicBlock *, 8 > &ExitBlocks, SmallSetVector< BasicBlock *, 8 > &BlocksDominatingExits)
Definition: LCSSA.cpp:260
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:56
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:459
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:190
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:224
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:107
#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:789
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:175
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:146
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
LLVM_NODISCARD char front() const
front - Get the first character in the string.
Definition: StringRef.h:142
LLVM Value Representation.
Definition: Value.h:73
The legacy pass manager&#39;s analysis pass to compute loop information.
Definition: LoopInfo.h:964
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:260
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:190
LocationClass< Ty > location(Ty &L)
Definition: CommandLine.h:426
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:1101