LLVM  3.7.0
ScalarEvolutionExpander.cpp
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1 //===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===//
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 file contains the implementation of the scalar evolution expander,
11 // which is used to generate the code corresponding to a given scalar evolution
12 // expression.
13 //
14 //===----------------------------------------------------------------------===//
15 
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/SmallSet.h"
20 #include "llvm/Analysis/LoopInfo.h"
22 #include "llvm/IR/DataLayout.h"
23 #include "llvm/IR/Dominators.h"
24 #include "llvm/IR/IntrinsicInst.h"
25 #include "llvm/IR/LLVMContext.h"
26 #include "llvm/IR/Module.h"
27 #include "llvm/IR/PatternMatch.h"
28 #include "llvm/Support/Debug.h"
30 
31 using namespace llvm;
32 using namespace PatternMatch;
33 
34 /// ReuseOrCreateCast - Arrange for there to be a cast of V to Ty at IP,
35 /// reusing an existing cast if a suitable one exists, moving an existing
36 /// cast if a suitable one exists but isn't in the right place, or
37 /// creating a new one.
38 Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
41  // This function must be called with the builder having a valid insertion
42  // point. It doesn't need to be the actual IP where the uses of the returned
43  // cast will be added, but it must dominate such IP.
44  // We use this precondition to produce a cast that will dominate all its
45  // uses. In particular, this is crucial for the case where the builder's
46  // insertion point *is* the point where we were asked to put the cast.
47  // Since we don't know the builder's insertion point is actually
48  // where the uses will be added (only that it dominates it), we are
49  // not allowed to move it.
50  BasicBlock::iterator BIP = Builder.GetInsertPoint();
51 
52  Instruction *Ret = nullptr;
53 
54  // Check to see if there is already a cast!
55  for (User *U : V->users())
56  if (U->getType() == Ty)
57  if (CastInst *CI = dyn_cast<CastInst>(U))
58  if (CI->getOpcode() == Op) {
59  // If the cast isn't where we want it, create a new cast at IP.
60  // Likewise, do not reuse a cast at BIP because it must dominate
61  // instructions that might be inserted before BIP.
62  if (BasicBlock::iterator(CI) != IP || BIP == IP) {
63  // Create a new cast, and leave the old cast in place in case
64  // it is being used as an insert point. Clear its operand
65  // so that it doesn't hold anything live.
66  Ret = CastInst::Create(Op, V, Ty, "", IP);
67  Ret->takeName(CI);
68  CI->replaceAllUsesWith(Ret);
69  CI->setOperand(0, UndefValue::get(V->getType()));
70  break;
71  }
72  Ret = CI;
73  break;
74  }
75 
76  // Create a new cast.
77  if (!Ret)
78  Ret = CastInst::Create(Op, V, Ty, V->getName(), IP);
79 
80  // We assert at the end of the function since IP might point to an
81  // instruction with different dominance properties than a cast
82  // (an invoke for example) and not dominate BIP (but the cast does).
83  assert(SE.DT->dominates(Ret, BIP));
84 
85  rememberInstruction(Ret);
86  return Ret;
87 }
88 
89 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
90 /// which must be possible with a noop cast, doing what we can to share
91 /// the casts.
92 Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) {
93  Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false);
94  assert((Op == Instruction::BitCast ||
95  Op == Instruction::PtrToInt ||
96  Op == Instruction::IntToPtr) &&
97  "InsertNoopCastOfTo cannot perform non-noop casts!");
98  assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) &&
99  "InsertNoopCastOfTo cannot change sizes!");
100 
101  // Short-circuit unnecessary bitcasts.
102  if (Op == Instruction::BitCast) {
103  if (V->getType() == Ty)
104  return V;
105  if (CastInst *CI = dyn_cast<CastInst>(V)) {
106  if (CI->getOperand(0)->getType() == Ty)
107  return CI->getOperand(0);
108  }
109  }
110  // Short-circuit unnecessary inttoptr<->ptrtoint casts.
111  if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) &&
112  SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {
113  if (CastInst *CI = dyn_cast<CastInst>(V))
114  if ((CI->getOpcode() == Instruction::PtrToInt ||
115  CI->getOpcode() == Instruction::IntToPtr) &&
116  SE.getTypeSizeInBits(CI->getType()) ==
117  SE.getTypeSizeInBits(CI->getOperand(0)->getType()))
118  return CI->getOperand(0);
119  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
120  if ((CE->getOpcode() == Instruction::PtrToInt ||
121  CE->getOpcode() == Instruction::IntToPtr) &&
122  SE.getTypeSizeInBits(CE->getType()) ==
123  SE.getTypeSizeInBits(CE->getOperand(0)->getType()))
124  return CE->getOperand(0);
125  }
126 
127  // Fold a cast of a constant.
128  if (Constant *C = dyn_cast<Constant>(V))
129  return ConstantExpr::getCast(Op, C, Ty);
130 
131  // Cast the argument at the beginning of the entry block, after
132  // any bitcasts of other arguments.
133  if (Argument *A = dyn_cast<Argument>(V)) {
134  BasicBlock::iterator IP = A->getParent()->getEntryBlock().begin();
135  while ((isa<BitCastInst>(IP) &&
136  isa<Argument>(cast<BitCastInst>(IP)->getOperand(0)) &&
137  cast<BitCastInst>(IP)->getOperand(0) != A) ||
138  isa<DbgInfoIntrinsic>(IP) ||
139  isa<LandingPadInst>(IP))
140  ++IP;
141  return ReuseOrCreateCast(A, Ty, Op, IP);
142  }
143 
144  // Cast the instruction immediately after the instruction.
145  Instruction *I = cast<Instruction>(V);
146  BasicBlock::iterator IP = I; ++IP;
147  if (InvokeInst *II = dyn_cast<InvokeInst>(I))
148  IP = II->getNormalDest()->begin();
149  while (isa<PHINode>(IP) || isa<LandingPadInst>(IP))
150  ++IP;
151  return ReuseOrCreateCast(I, Ty, Op, IP);
152 }
153 
154 /// InsertBinop - Insert the specified binary operator, doing a small amount
155 /// of work to avoid inserting an obviously redundant operation.
156 Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
157  Value *LHS, Value *RHS) {
158  // Fold a binop with constant operands.
159  if (Constant *CLHS = dyn_cast<Constant>(LHS))
160  if (Constant *CRHS = dyn_cast<Constant>(RHS))
161  return ConstantExpr::get(Opcode, CLHS, CRHS);
162 
163  // Do a quick scan to see if we have this binop nearby. If so, reuse it.
164  unsigned ScanLimit = 6;
165  BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
166  // Scanning starts from the last instruction before the insertion point.
167  BasicBlock::iterator IP = Builder.GetInsertPoint();
168  if (IP != BlockBegin) {
169  --IP;
170  for (; ScanLimit; --IP, --ScanLimit) {
171  // Don't count dbg.value against the ScanLimit, to avoid perturbing the
172  // generated code.
173  if (isa<DbgInfoIntrinsic>(IP))
174  ScanLimit++;
175  if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
176  IP->getOperand(1) == RHS)
177  return IP;
178  if (IP == BlockBegin) break;
179  }
180  }
181 
182  // Save the original insertion point so we can restore it when we're done.
183  DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
184  BuilderType::InsertPointGuard Guard(Builder);
185 
186  // Move the insertion point out of as many loops as we can.
187  while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
188  if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break;
189  BasicBlock *Preheader = L->getLoopPreheader();
190  if (!Preheader) break;
191 
192  // Ok, move up a level.
193  Builder.SetInsertPoint(Preheader, Preheader->getTerminator());
194  }
195 
196  // If we haven't found this binop, insert it.
197  Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS));
198  BO->setDebugLoc(Loc);
199  rememberInstruction(BO);
200 
201  return BO;
202 }
203 
204 /// FactorOutConstant - Test if S is divisible by Factor, using signed
205 /// division. If so, update S with Factor divided out and return true.
206 /// S need not be evenly divisible if a reasonable remainder can be
207 /// computed.
208 /// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made
209 /// unnecessary; in its place, just signed-divide Ops[i] by the scale and
210 /// check to see if the divide was folded.
211 static bool FactorOutConstant(const SCEV *&S, const SCEV *&Remainder,
212  const SCEV *Factor, ScalarEvolution &SE,
213  const DataLayout &DL) {
214  // Everything is divisible by one.
215  if (Factor->isOne())
216  return true;
217 
218  // x/x == 1.
219  if (S == Factor) {
220  S = SE.getConstant(S->getType(), 1);
221  return true;
222  }
223 
224  // For a Constant, check for a multiple of the given factor.
225  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
226  // 0/x == 0.
227  if (C->isZero())
228  return true;
229  // Check for divisibility.
230  if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor)) {
231  ConstantInt *CI =
233  C->getValue()->getValue().sdiv(
234  FC->getValue()->getValue()));
235  // If the quotient is zero and the remainder is non-zero, reject
236  // the value at this scale. It will be considered for subsequent
237  // smaller scales.
238  if (!CI->isZero()) {
239  const SCEV *Div = SE.getConstant(CI);
240  S = Div;
241  Remainder =
242  SE.getAddExpr(Remainder,
243  SE.getConstant(C->getValue()->getValue().srem(
244  FC->getValue()->getValue())));
245  return true;
246  }
247  }
248  }
249 
250  // In a Mul, check if there is a constant operand which is a multiple
251  // of the given factor.
252  if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
253  // Size is known, check if there is a constant operand which is a multiple
254  // of the given factor. If so, we can factor it.
255  const SCEVConstant *FC = cast<SCEVConstant>(Factor);
256  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
257  if (!C->getValue()->getValue().srem(FC->getValue()->getValue())) {
258  SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
259  NewMulOps[0] = SE.getConstant(
260  C->getValue()->getValue().sdiv(FC->getValue()->getValue()));
261  S = SE.getMulExpr(NewMulOps);
262  return true;
263  }
264  }
265 
266  // In an AddRec, check if both start and step are divisible.
267  if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
268  const SCEV *Step = A->getStepRecurrence(SE);
269  const SCEV *StepRem = SE.getConstant(Step->getType(), 0);
270  if (!FactorOutConstant(Step, StepRem, Factor, SE, DL))
271  return false;
272  if (!StepRem->isZero())
273  return false;
274  const SCEV *Start = A->getStart();
275  if (!FactorOutConstant(Start, Remainder, Factor, SE, DL))
276  return false;
277  S = SE.getAddRecExpr(Start, Step, A->getLoop(),
278  A->getNoWrapFlags(SCEV::FlagNW));
279  return true;
280  }
281 
282  return false;
283 }
284 
285 /// SimplifyAddOperands - Sort and simplify a list of add operands. NumAddRecs
286 /// is the number of SCEVAddRecExprs present, which are kept at the end of
287 /// the list.
288 ///
290  Type *Ty,
291  ScalarEvolution &SE) {
292  unsigned NumAddRecs = 0;
293  for (unsigned i = Ops.size(); i > 0 && isa<SCEVAddRecExpr>(Ops[i-1]); --i)
294  ++NumAddRecs;
295  // Group Ops into non-addrecs and addrecs.
296  SmallVector<const SCEV *, 8> NoAddRecs(Ops.begin(), Ops.end() - NumAddRecs);
297  SmallVector<const SCEV *, 8> AddRecs(Ops.end() - NumAddRecs, Ops.end());
298  // Let ScalarEvolution sort and simplify the non-addrecs list.
299  const SCEV *Sum = NoAddRecs.empty() ?
300  SE.getConstant(Ty, 0) :
301  SE.getAddExpr(NoAddRecs);
302  // If it returned an add, use the operands. Otherwise it simplified
303  // the sum into a single value, so just use that.
304  Ops.clear();
305  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum))
306  Ops.append(Add->op_begin(), Add->op_end());
307  else if (!Sum->isZero())
308  Ops.push_back(Sum);
309  // Then append the addrecs.
310  Ops.append(AddRecs.begin(), AddRecs.end());
311 }
312 
313 /// SplitAddRecs - Flatten a list of add operands, moving addrec start values
314 /// out to the top level. For example, convert {a + b,+,c} to a, b, {0,+,d}.
315 /// This helps expose more opportunities for folding parts of the expressions
316 /// into GEP indices.
317 ///
319  Type *Ty,
320  ScalarEvolution &SE) {
321  // Find the addrecs.
323  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
324  while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i])) {
325  const SCEV *Start = A->getStart();
326  if (Start->isZero()) break;
327  const SCEV *Zero = SE.getConstant(Ty, 0);
328  AddRecs.push_back(SE.getAddRecExpr(Zero,
329  A->getStepRecurrence(SE),
330  A->getLoop(),
331  A->getNoWrapFlags(SCEV::FlagNW)));
332  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
333  Ops[i] = Zero;
334  Ops.append(Add->op_begin(), Add->op_end());
335  e += Add->getNumOperands();
336  } else {
337  Ops[i] = Start;
338  }
339  }
340  if (!AddRecs.empty()) {
341  // Add the addrecs onto the end of the list.
342  Ops.append(AddRecs.begin(), AddRecs.end());
343  // Resort the operand list, moving any constants to the front.
344  SimplifyAddOperands(Ops, Ty, SE);
345  }
346 }
347 
348 /// expandAddToGEP - Expand an addition expression with a pointer type into
349 /// a GEP instead of using ptrtoint+arithmetic+inttoptr. This helps
350 /// BasicAliasAnalysis and other passes analyze the result. See the rules
351 /// for getelementptr vs. inttoptr in
352 /// http://llvm.org/docs/LangRef.html#pointeraliasing
353 /// for details.
354 ///
355 /// Design note: The correctness of using getelementptr here depends on
356 /// ScalarEvolution not recognizing inttoptr and ptrtoint operators, as
357 /// they may introduce pointer arithmetic which may not be safely converted
358 /// into getelementptr.
359 ///
360 /// Design note: It might seem desirable for this function to be more
361 /// loop-aware. If some of the indices are loop-invariant while others
362 /// aren't, it might seem desirable to emit multiple GEPs, keeping the
363 /// loop-invariant portions of the overall computation outside the loop.
364 /// However, there are a few reasons this is not done here. Hoisting simple
365 /// arithmetic is a low-level optimization that often isn't very
366 /// important until late in the optimization process. In fact, passes
367 /// like InstructionCombining will combine GEPs, even if it means
368 /// pushing loop-invariant computation down into loops, so even if the
369 /// GEPs were split here, the work would quickly be undone. The
370 /// LoopStrengthReduction pass, which is usually run quite late (and
371 /// after the last InstructionCombining pass), takes care of hoisting
372 /// loop-invariant portions of expressions, after considering what
373 /// can be folded using target addressing modes.
374 ///
375 Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
376  const SCEV *const *op_end,
377  PointerType *PTy,
378  Type *Ty,
379  Value *V) {
380  Type *OriginalElTy = PTy->getElementType();
381  Type *ElTy = OriginalElTy;
382  SmallVector<Value *, 4> GepIndices;
383  SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
384  bool AnyNonZeroIndices = false;
385 
386  // Split AddRecs up into parts as either of the parts may be usable
387  // without the other.
388  SplitAddRecs(Ops, Ty, SE);
389 
390  Type *IntPtrTy = DL.getIntPtrType(PTy);
391 
392  // Descend down the pointer's type and attempt to convert the other
393  // operands into GEP indices, at each level. The first index in a GEP
394  // indexes into the array implied by the pointer operand; the rest of
395  // the indices index into the element or field type selected by the
396  // preceding index.
397  for (;;) {
398  // If the scale size is not 0, attempt to factor out a scale for
399  // array indexing.
401  if (ElTy->isSized()) {
402  const SCEV *ElSize = SE.getSizeOfExpr(IntPtrTy, ElTy);
403  if (!ElSize->isZero()) {
405  for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
406  const SCEV *Op = Ops[i];
407  const SCEV *Remainder = SE.getConstant(Ty, 0);
408  if (FactorOutConstant(Op, Remainder, ElSize, SE, DL)) {
409  // Op now has ElSize factored out.
410  ScaledOps.push_back(Op);
411  if (!Remainder->isZero())
412  NewOps.push_back(Remainder);
413  AnyNonZeroIndices = true;
414  } else {
415  // The operand was not divisible, so add it to the list of operands
416  // we'll scan next iteration.
417  NewOps.push_back(Ops[i]);
418  }
419  }
420  // If we made any changes, update Ops.
421  if (!ScaledOps.empty()) {
422  Ops = NewOps;
423  SimplifyAddOperands(Ops, Ty, SE);
424  }
425  }
426  }
427 
428  // Record the scaled array index for this level of the type. If
429  // we didn't find any operands that could be factored, tentatively
430  // assume that element zero was selected (since the zero offset
431  // would obviously be folded away).
432  Value *Scaled = ScaledOps.empty() ?
434  expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
435  GepIndices.push_back(Scaled);
436 
437  // Collect struct field index operands.
438  while (StructType *STy = dyn_cast<StructType>(ElTy)) {
439  bool FoundFieldNo = false;
440  // An empty struct has no fields.
441  if (STy->getNumElements() == 0) break;
442  // Field offsets are known. See if a constant offset falls within any of
443  // the struct fields.
444  if (Ops.empty())
445  break;
446  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
447  if (SE.getTypeSizeInBits(C->getType()) <= 64) {
448  const StructLayout &SL = *DL.getStructLayout(STy);
449  uint64_t FullOffset = C->getValue()->getZExtValue();
450  if (FullOffset < SL.getSizeInBytes()) {
451  unsigned ElIdx = SL.getElementContainingOffset(FullOffset);
452  GepIndices.push_back(
454  ElTy = STy->getTypeAtIndex(ElIdx);
455  Ops[0] =
456  SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx));
457  AnyNonZeroIndices = true;
458  FoundFieldNo = true;
459  }
460  }
461  // If no struct field offsets were found, tentatively assume that
462  // field zero was selected (since the zero offset would obviously
463  // be folded away).
464  if (!FoundFieldNo) {
465  ElTy = STy->getTypeAtIndex(0u);
466  GepIndices.push_back(
468  }
469  }
470 
471  if (ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
472  ElTy = ATy->getElementType();
473  else
474  break;
475  }
476 
477  // If none of the operands were convertible to proper GEP indices, cast
478  // the base to i8* and do an ugly getelementptr with that. It's still
479  // better than ptrtoint+arithmetic+inttoptr at least.
480  if (!AnyNonZeroIndices) {
481  // Cast the base to i8*.
482  V = InsertNoopCastOfTo(V,
484 
485  assert(!isa<Instruction>(V) ||
486  SE.DT->dominates(cast<Instruction>(V), Builder.GetInsertPoint()));
487 
488  // Expand the operands for a plain byte offset.
489  Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
490 
491  // Fold a GEP with constant operands.
492  if (Constant *CLHS = dyn_cast<Constant>(V))
493  if (Constant *CRHS = dyn_cast<Constant>(Idx))
495  CLHS, CRHS);
496 
497  // Do a quick scan to see if we have this GEP nearby. If so, reuse it.
498  unsigned ScanLimit = 6;
499  BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
500  // Scanning starts from the last instruction before the insertion point.
501  BasicBlock::iterator IP = Builder.GetInsertPoint();
502  if (IP != BlockBegin) {
503  --IP;
504  for (; ScanLimit; --IP, --ScanLimit) {
505  // Don't count dbg.value against the ScanLimit, to avoid perturbing the
506  // generated code.
507  if (isa<DbgInfoIntrinsic>(IP))
508  ScanLimit++;
509  if (IP->getOpcode() == Instruction::GetElementPtr &&
510  IP->getOperand(0) == V && IP->getOperand(1) == Idx)
511  return IP;
512  if (IP == BlockBegin) break;
513  }
514  }
515 
516  // Save the original insertion point so we can restore it when we're done.
517  BuilderType::InsertPointGuard Guard(Builder);
518 
519  // Move the insertion point out of as many loops as we can.
520  while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
521  if (!L->isLoopInvariant(V) || !L->isLoopInvariant(Idx)) break;
522  BasicBlock *Preheader = L->getLoopPreheader();
523  if (!Preheader) break;
524 
525  // Ok, move up a level.
526  Builder.SetInsertPoint(Preheader, Preheader->getTerminator());
527  }
528 
529  // Emit a GEP.
530  Value *GEP = Builder.CreateGEP(Builder.getInt8Ty(), V, Idx, "uglygep");
531  rememberInstruction(GEP);
532 
533  return GEP;
534  }
535 
536  // Save the original insertion point so we can restore it when we're done.
537  BuilderType::InsertPoint SaveInsertPt = Builder.saveIP();
538 
539  // Move the insertion point out of as many loops as we can.
540  while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) {
541  if (!L->isLoopInvariant(V)) break;
542 
543  bool AnyIndexNotLoopInvariant = false;
544  for (SmallVectorImpl<Value *>::const_iterator I = GepIndices.begin(),
545  E = GepIndices.end(); I != E; ++I)
546  if (!L->isLoopInvariant(*I)) {
547  AnyIndexNotLoopInvariant = true;
548  break;
549  }
550  if (AnyIndexNotLoopInvariant)
551  break;
552 
553  BasicBlock *Preheader = L->getLoopPreheader();
554  if (!Preheader) break;
555 
556  // Ok, move up a level.
557  Builder.SetInsertPoint(Preheader, Preheader->getTerminator());
558  }
559 
560  // Insert a pretty getelementptr. Note that this GEP is not marked inbounds,
561  // because ScalarEvolution may have changed the address arithmetic to
562  // compute a value which is beyond the end of the allocated object.
563  Value *Casted = V;
564  if (V->getType() != PTy)
565  Casted = InsertNoopCastOfTo(Casted, PTy);
566  Value *GEP = Builder.CreateGEP(OriginalElTy, Casted,
567  GepIndices,
568  "scevgep");
569  Ops.push_back(SE.getUnknown(GEP));
570  rememberInstruction(GEP);
571 
572  // Restore the original insert point.
573  Builder.restoreIP(SaveInsertPt);
574 
575  return expand(SE.getAddExpr(Ops));
576 }
577 
578 /// PickMostRelevantLoop - Given two loops pick the one that's most relevant for
579 /// SCEV expansion. If they are nested, this is the most nested. If they are
580 /// neighboring, pick the later.
581 static const Loop *PickMostRelevantLoop(const Loop *A, const Loop *B,
582  DominatorTree &DT) {
583  if (!A) return B;
584  if (!B) return A;
585  if (A->contains(B)) return B;
586  if (B->contains(A)) return A;
587  if (DT.dominates(A->getHeader(), B->getHeader())) return B;
588  if (DT.dominates(B->getHeader(), A->getHeader())) return A;
589  return A; // Arbitrarily break the tie.
590 }
591 
592 /// getRelevantLoop - Get the most relevant loop associated with the given
593 /// expression, according to PickMostRelevantLoop.
594 const Loop *SCEVExpander::getRelevantLoop(const SCEV *S) {
595  // Test whether we've already computed the most relevant loop for this SCEV.
596  std::pair<DenseMap<const SCEV *, const Loop *>::iterator, bool> Pair =
597  RelevantLoops.insert(std::make_pair(S, nullptr));
598  if (!Pair.second)
599  return Pair.first->second;
600 
601  if (isa<SCEVConstant>(S))
602  // A constant has no relevant loops.
603  return nullptr;
604  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
605  if (const Instruction *I = dyn_cast<Instruction>(U->getValue()))
606  return Pair.first->second = SE.LI->getLoopFor(I->getParent());
607  // A non-instruction has no relevant loops.
608  return nullptr;
609  }
610  if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) {
611  const Loop *L = nullptr;
612  if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
613  L = AR->getLoop();
614  for (SCEVNAryExpr::op_iterator I = N->op_begin(), E = N->op_end();
615  I != E; ++I)
616  L = PickMostRelevantLoop(L, getRelevantLoop(*I), *SE.DT);
617  return RelevantLoops[N] = L;
618  }
619  if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) {
620  const Loop *Result = getRelevantLoop(C->getOperand());
621  return RelevantLoops[C] = Result;
622  }
623  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
624  const Loop *Result =
625  PickMostRelevantLoop(getRelevantLoop(D->getLHS()),
626  getRelevantLoop(D->getRHS()),
627  *SE.DT);
628  return RelevantLoops[D] = Result;
629  }
630  llvm_unreachable("Unexpected SCEV type!");
631 }
632 
633 namespace {
634 
635 /// LoopCompare - Compare loops by PickMostRelevantLoop.
636 class LoopCompare {
637  DominatorTree &DT;
638 public:
639  explicit LoopCompare(DominatorTree &dt) : DT(dt) {}
640 
641  bool operator()(std::pair<const Loop *, const SCEV *> LHS,
642  std::pair<const Loop *, const SCEV *> RHS) const {
643  // Keep pointer operands sorted at the end.
644  if (LHS.second->getType()->isPointerTy() !=
645  RHS.second->getType()->isPointerTy())
646  return LHS.second->getType()->isPointerTy();
647 
648  // Compare loops with PickMostRelevantLoop.
649  if (LHS.first != RHS.first)
650  return PickMostRelevantLoop(LHS.first, RHS.first, DT) != LHS.first;
651 
652  // If one operand is a non-constant negative and the other is not,
653  // put the non-constant negative on the right so that a sub can
654  // be used instead of a negate and add.
655  if (LHS.second->isNonConstantNegative()) {
656  if (!RHS.second->isNonConstantNegative())
657  return false;
658  } else if (RHS.second->isNonConstantNegative())
659  return true;
660 
661  // Otherwise they are equivalent according to this comparison.
662  return false;
663  }
664 };
665 
666 }
667 
668 Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
669  Type *Ty = SE.getEffectiveSCEVType(S->getType());
670 
671  // Collect all the add operands in a loop, along with their associated loops.
672  // Iterate in reverse so that constants are emitted last, all else equal, and
673  // so that pointer operands are inserted first, which the code below relies on
674  // to form more involved GEPs.
676  for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(S->op_end()),
677  E(S->op_begin()); I != E; ++I)
678  OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
679 
680  // Sort by loop. Use a stable sort so that constants follow non-constants and
681  // pointer operands precede non-pointer operands.
682  std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(*SE.DT));
683 
684  // Emit instructions to add all the operands. Hoist as much as possible
685  // out of loops, and form meaningful getelementptrs where possible.
686  Value *Sum = nullptr;
687  for (SmallVectorImpl<std::pair<const Loop *, const SCEV *> >::iterator
688  I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E; ) {
689  const Loop *CurLoop = I->first;
690  const SCEV *Op = I->second;
691  if (!Sum) {
692  // This is the first operand. Just expand it.
693  Sum = expand(Op);
694  ++I;
695  } else if (PointerType *PTy = dyn_cast<PointerType>(Sum->getType())) {
696  // The running sum expression is a pointer. Try to form a getelementptr
697  // at this level with that as the base.
699  for (; I != E && I->first == CurLoop; ++I) {
700  // If the operand is SCEVUnknown and not instructions, peek through
701  // it, to enable more of it to be folded into the GEP.
702  const SCEV *X = I->second;
703  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(X))
704  if (!isa<Instruction>(U->getValue()))
705  X = SE.getSCEV(U->getValue());
706  NewOps.push_back(X);
707  }
708  Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum);
709  } else if (PointerType *PTy = dyn_cast<PointerType>(Op->getType())) {
710  // The running sum is an integer, and there's a pointer at this level.
711  // Try to form a getelementptr. If the running sum is instructions,
712  // use a SCEVUnknown to avoid re-analyzing them.
714  NewOps.push_back(isa<Instruction>(Sum) ? SE.getUnknown(Sum) :
715  SE.getSCEV(Sum));
716  for (++I; I != E && I->first == CurLoop; ++I)
717  NewOps.push_back(I->second);
718  Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, expand(Op));
719  } else if (Op->isNonConstantNegative()) {
720  // Instead of doing a negate and add, just do a subtract.
721  Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty);
722  Sum = InsertNoopCastOfTo(Sum, Ty);
723  Sum = InsertBinop(Instruction::Sub, Sum, W);
724  ++I;
725  } else {
726  // A simple add.
727  Value *W = expandCodeFor(Op, Ty);
728  Sum = InsertNoopCastOfTo(Sum, Ty);
729  // Canonicalize a constant to the RHS.
730  if (isa<Constant>(Sum)) std::swap(Sum, W);
731  Sum = InsertBinop(Instruction::Add, Sum, W);
732  ++I;
733  }
734  }
735 
736  return Sum;
737 }
738 
739 Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
740  Type *Ty = SE.getEffectiveSCEVType(S->getType());
741 
742  // Collect all the mul operands in a loop, along with their associated loops.
743  // Iterate in reverse so that constants are emitted last, all else equal.
745  for (std::reverse_iterator<SCEVMulExpr::op_iterator> I(S->op_end()),
746  E(S->op_begin()); I != E; ++I)
747  OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
748 
749  // Sort by loop. Use a stable sort so that constants follow non-constants.
750  std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(*SE.DT));
751 
752  // Emit instructions to mul all the operands. Hoist as much as possible
753  // out of loops.
754  Value *Prod = nullptr;
755  for (SmallVectorImpl<std::pair<const Loop *, const SCEV *> >::iterator
756  I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E; ++I) {
757  const SCEV *Op = I->second;
758  if (!Prod) {
759  // This is the first operand. Just expand it.
760  Prod = expand(Op);
761  } else if (Op->isAllOnesValue()) {
762  // Instead of doing a multiply by negative one, just do a negate.
763  Prod = InsertNoopCastOfTo(Prod, Ty);
764  Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod);
765  } else {
766  // A simple mul.
767  Value *W = expandCodeFor(Op, Ty);
768  Prod = InsertNoopCastOfTo(Prod, Ty);
769  // Canonicalize a constant to the RHS.
770  if (isa<Constant>(Prod)) std::swap(Prod, W);
771  const APInt *RHS;
772  if (match(W, m_Power2(RHS))) {
773  // Canonicalize Prod*(1<<C) to Prod<<C.
774  assert(!Ty->isVectorTy() && "vector types are not SCEVable");
775  Prod = InsertBinop(Instruction::Shl, Prod,
776  ConstantInt::get(Ty, RHS->logBase2()));
777  } else {
778  Prod = InsertBinop(Instruction::Mul, Prod, W);
779  }
780  }
781  }
782 
783  return Prod;
784 }
785 
786 Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
787  Type *Ty = SE.getEffectiveSCEVType(S->getType());
788 
789  Value *LHS = expandCodeFor(S->getLHS(), Ty);
790  if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
791  const APInt &RHS = SC->getValue()->getValue();
792  if (RHS.isPowerOf2())
793  return InsertBinop(Instruction::LShr, LHS,
794  ConstantInt::get(Ty, RHS.logBase2()));
795  }
796 
797  Value *RHS = expandCodeFor(S->getRHS(), Ty);
798  return InsertBinop(Instruction::UDiv, LHS, RHS);
799 }
800 
801 /// Move parts of Base into Rest to leave Base with the minimal
802 /// expression that provides a pointer operand suitable for a
803 /// GEP expansion.
804 static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest,
805  ScalarEvolution &SE) {
806  while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) {
807  Base = A->getStart();
808  Rest = SE.getAddExpr(Rest,
809  SE.getAddRecExpr(SE.getConstant(A->getType(), 0),
810  A->getStepRecurrence(SE),
811  A->getLoop(),
812  A->getNoWrapFlags(SCEV::FlagNW)));
813  }
814  if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
815  Base = A->getOperand(A->getNumOperands()-1);
816  SmallVector<const SCEV *, 8> NewAddOps(A->op_begin(), A->op_end());
817  NewAddOps.back() = Rest;
818  Rest = SE.getAddExpr(NewAddOps);
819  ExposePointerBase(Base, Rest, SE);
820  }
821 }
822 
823 /// Determine if this is a well-behaved chain of instructions leading back to
824 /// the PHI. If so, it may be reused by expanded expressions.
825 bool SCEVExpander::isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV,
826  const Loop *L) {
827  if (IncV->getNumOperands() == 0 || isa<PHINode>(IncV) ||
828  (isa<CastInst>(IncV) && !isa<BitCastInst>(IncV)))
829  return false;
830  // If any of the operands don't dominate the insert position, bail.
831  // Addrec operands are always loop-invariant, so this can only happen
832  // if there are instructions which haven't been hoisted.
833  if (L == IVIncInsertLoop) {
834  for (User::op_iterator OI = IncV->op_begin()+1,
835  OE = IncV->op_end(); OI != OE; ++OI)
836  if (Instruction *OInst = dyn_cast<Instruction>(OI))
837  if (!SE.DT->dominates(OInst, IVIncInsertPos))
838  return false;
839  }
840  // Advance to the next instruction.
841  IncV = dyn_cast<Instruction>(IncV->getOperand(0));
842  if (!IncV)
843  return false;
844 
845  if (IncV->mayHaveSideEffects())
846  return false;
847 
848  if (IncV != PN)
849  return true;
850 
851  return isNormalAddRecExprPHI(PN, IncV, L);
852 }
853 
854 /// getIVIncOperand returns an induction variable increment's induction
855 /// variable operand.
856 ///
857 /// If allowScale is set, any type of GEP is allowed as long as the nonIV
858 /// operands dominate InsertPos.
859 ///
860 /// If allowScale is not set, ensure that a GEP increment conforms to one of the
861 /// simple patterns generated by getAddRecExprPHILiterally and
862 /// expandAddtoGEP. If the pattern isn't recognized, return NULL.
864  Instruction *InsertPos,
865  bool allowScale) {
866  if (IncV == InsertPos)
867  return nullptr;
868 
869  switch (IncV->getOpcode()) {
870  default:
871  return nullptr;
872  // Check for a simple Add/Sub or GEP of a loop invariant step.
873  case Instruction::Add:
874  case Instruction::Sub: {
875  Instruction *OInst = dyn_cast<Instruction>(IncV->getOperand(1));
876  if (!OInst || SE.DT->dominates(OInst, InsertPos))
877  return dyn_cast<Instruction>(IncV->getOperand(0));
878  return nullptr;
879  }
880  case Instruction::BitCast:
881  return dyn_cast<Instruction>(IncV->getOperand(0));
882  case Instruction::GetElementPtr:
883  for (Instruction::op_iterator I = IncV->op_begin()+1, E = IncV->op_end();
884  I != E; ++I) {
885  if (isa<Constant>(*I))
886  continue;
887  if (Instruction *OInst = dyn_cast<Instruction>(*I)) {
888  if (!SE.DT->dominates(OInst, InsertPos))
889  return nullptr;
890  }
891  if (allowScale) {
892  // allow any kind of GEP as long as it can be hoisted.
893  continue;
894  }
895  // This must be a pointer addition of constants (pretty), which is already
896  // handled, or some number of address-size elements (ugly). Ugly geps
897  // have 2 operands. i1* is used by the expander to represent an
898  // address-size element.
899  if (IncV->getNumOperands() != 2)
900  return nullptr;
901  unsigned AS = cast<PointerType>(IncV->getType())->getAddressSpace();
902  if (IncV->getType() != Type::getInt1PtrTy(SE.getContext(), AS)
903  && IncV->getType() != Type::getInt8PtrTy(SE.getContext(), AS))
904  return nullptr;
905  break;
906  }
907  return dyn_cast<Instruction>(IncV->getOperand(0));
908  }
909 }
910 
911 /// hoistStep - Attempt to hoist a simple IV increment above InsertPos to make
912 /// it available to other uses in this loop. Recursively hoist any operands,
913 /// until we reach a value that dominates InsertPos.
915  if (SE.DT->dominates(IncV, InsertPos))
916  return true;
917 
918  // InsertPos must itself dominate IncV so that IncV's new position satisfies
919  // its existing users.
920  if (isa<PHINode>(InsertPos)
921  || !SE.DT->dominates(InsertPos->getParent(), IncV->getParent()))
922  return false;
923 
924  // Check that the chain of IV operands leading back to Phi can be hoisted.
926  for(;;) {
927  Instruction *Oper = getIVIncOperand(IncV, InsertPos, /*allowScale*/true);
928  if (!Oper)
929  return false;
930  // IncV is safe to hoist.
931  IVIncs.push_back(IncV);
932  IncV = Oper;
933  if (SE.DT->dominates(IncV, InsertPos))
934  break;
935  }
937  E = IVIncs.rend(); I != E; ++I) {
938  (*I)->moveBefore(InsertPos);
939  }
940  return true;
941 }
942 
943 /// Determine if this cyclic phi is in a form that would have been generated by
944 /// LSR. We don't care if the phi was actually expanded in this pass, as long
945 /// as it is in a low-cost form, for example, no implied multiplication. This
946 /// should match any patterns generated by getAddRecExprPHILiterally and
947 /// expandAddtoGEP.
948 bool SCEVExpander::isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV,
949  const Loop *L) {
950  for(Instruction *IVOper = IncV;
951  (IVOper = getIVIncOperand(IVOper, L->getLoopPreheader()->getTerminator(),
952  /*allowScale=*/false));) {
953  if (IVOper == PN)
954  return true;
955  }
956  return false;
957 }
958 
959 /// expandIVInc - Expand an IV increment at Builder's current InsertPos.
960 /// Typically this is the LatchBlock terminator or IVIncInsertPos, but we may
961 /// need to materialize IV increments elsewhere to handle difficult situations.
962 Value *SCEVExpander::expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
963  Type *ExpandTy, Type *IntTy,
964  bool useSubtract) {
965  Value *IncV;
966  // If the PHI is a pointer, use a GEP, otherwise use an add or sub.
967  if (ExpandTy->isPointerTy()) {
968  PointerType *GEPPtrTy = cast<PointerType>(ExpandTy);
969  // If the step isn't constant, don't use an implicitly scaled GEP, because
970  // that would require a multiply inside the loop.
971  if (!isa<ConstantInt>(StepV))
972  GEPPtrTy = PointerType::get(Type::getInt1Ty(SE.getContext()),
973  GEPPtrTy->getAddressSpace());
974  const SCEV *const StepArray[1] = { SE.getSCEV(StepV) };
975  IncV = expandAddToGEP(StepArray, StepArray+1, GEPPtrTy, IntTy, PN);
976  if (IncV->getType() != PN->getType()) {
977  IncV = Builder.CreateBitCast(IncV, PN->getType());
978  rememberInstruction(IncV);
979  }
980  } else {
981  IncV = useSubtract ?
982  Builder.CreateSub(PN, StepV, Twine(IVName) + ".iv.next") :
983  Builder.CreateAdd(PN, StepV, Twine(IVName) + ".iv.next");
984  rememberInstruction(IncV);
985  }
986  return IncV;
987 }
988 
989 /// \brief Hoist the addrec instruction chain rooted in the loop phi above the
990 /// position. This routine assumes that this is possible (has been checked).
991 static void hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
992  Instruction *Pos, PHINode *LoopPhi) {
993  do {
994  if (DT->dominates(InstToHoist, Pos))
995  break;
996  // Make sure the increment is where we want it. But don't move it
997  // down past a potential existing post-inc user.
998  InstToHoist->moveBefore(Pos);
999  Pos = InstToHoist;
1000  InstToHoist = cast<Instruction>(InstToHoist->getOperand(0));
1001  } while (InstToHoist != LoopPhi);
1002 }
1003 
1004 /// \brief Check whether we can cheaply express the requested SCEV in terms of
1005 /// the available PHI SCEV by truncation and/or invertion of the step.
1007  const SCEVAddRecExpr *Phi,
1008  const SCEVAddRecExpr *Requested,
1009  bool &InvertStep) {
1010  Type *PhiTy = SE.getEffectiveSCEVType(Phi->getType());
1011  Type *RequestedTy = SE.getEffectiveSCEVType(Requested->getType());
1012 
1013  if (RequestedTy->getIntegerBitWidth() > PhiTy->getIntegerBitWidth())
1014  return false;
1015 
1016  // Try truncate it if necessary.
1017  Phi = dyn_cast<SCEVAddRecExpr>(SE.getTruncateOrNoop(Phi, RequestedTy));
1018  if (!Phi)
1019  return false;
1020 
1021  // Check whether truncation will help.
1022  if (Phi == Requested) {
1023  InvertStep = false;
1024  return true;
1025  }
1026 
1027  // Check whether inverting will help: {R,+,-1} == R - {0,+,1}.
1028  if (SE.getAddExpr(Requested->getStart(),
1029  SE.getNegativeSCEV(Requested)) == Phi) {
1030  InvertStep = true;
1031  return true;
1032  }
1033 
1034  return false;
1035 }
1036 
1037 static bool IsIncrementNSW(ScalarEvolution &SE, const SCEVAddRecExpr *AR) {
1038  if (!isa<IntegerType>(AR->getType()))
1039  return false;
1040 
1041  unsigned BitWidth = cast<IntegerType>(AR->getType())->getBitWidth();
1042  Type *WideTy = IntegerType::get(AR->getType()->getContext(), BitWidth * 2);
1043  const SCEV *Step = AR->getStepRecurrence(SE);
1044  const SCEV *OpAfterExtend = SE.getAddExpr(SE.getSignExtendExpr(Step, WideTy),
1045  SE.getSignExtendExpr(AR, WideTy));
1046  const SCEV *ExtendAfterOp =
1047  SE.getSignExtendExpr(SE.getAddExpr(AR, Step), WideTy);
1048  return ExtendAfterOp == OpAfterExtend;
1049 }
1050 
1051 static bool IsIncrementNUW(ScalarEvolution &SE, const SCEVAddRecExpr *AR) {
1052  if (!isa<IntegerType>(AR->getType()))
1053  return false;
1054 
1055  unsigned BitWidth = cast<IntegerType>(AR->getType())->getBitWidth();
1056  Type *WideTy = IntegerType::get(AR->getType()->getContext(), BitWidth * 2);
1057  const SCEV *Step = AR->getStepRecurrence(SE);
1058  const SCEV *OpAfterExtend = SE.getAddExpr(SE.getZeroExtendExpr(Step, WideTy),
1059  SE.getZeroExtendExpr(AR, WideTy));
1060  const SCEV *ExtendAfterOp =
1061  SE.getZeroExtendExpr(SE.getAddExpr(AR, Step), WideTy);
1062  return ExtendAfterOp == OpAfterExtend;
1063 }
1064 
1065 /// getAddRecExprPHILiterally - Helper for expandAddRecExprLiterally. Expand
1066 /// the base addrec, which is the addrec without any non-loop-dominating
1067 /// values, and return the PHI.
1068 PHINode *
1069 SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
1070  const Loop *L,
1071  Type *ExpandTy,
1072  Type *IntTy,
1073  Type *&TruncTy,
1074  bool &InvertStep) {
1075  assert((!IVIncInsertLoop||IVIncInsertPos) && "Uninitialized insert position");
1076 
1077  // Reuse a previously-inserted PHI, if present.
1078  BasicBlock *LatchBlock = L->getLoopLatch();
1079  if (LatchBlock) {
1080  PHINode *AddRecPhiMatch = nullptr;
1081  Instruction *IncV = nullptr;
1082  TruncTy = nullptr;
1083  InvertStep = false;
1084 
1085  // Only try partially matching scevs that need truncation and/or
1086  // step-inversion if we know this loop is outside the current loop.
1087  bool TryNonMatchingSCEV = IVIncInsertLoop &&
1088  SE.DT->properlyDominates(LatchBlock, IVIncInsertLoop->getHeader());
1089 
1090  for (BasicBlock::iterator I = L->getHeader()->begin();
1091  PHINode *PN = dyn_cast<PHINode>(I); ++I) {
1092  if (!SE.isSCEVable(PN->getType()))
1093  continue;
1094 
1095  const SCEVAddRecExpr *PhiSCEV = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(PN));
1096  if (!PhiSCEV)
1097  continue;
1098 
1099  bool IsMatchingSCEV = PhiSCEV == Normalized;
1100  // We only handle truncation and inversion of phi recurrences for the
1101  // expanded expression if the expanded expression's loop dominates the
1102  // loop we insert to. Check now, so we can bail out early.
1103  if (!IsMatchingSCEV && !TryNonMatchingSCEV)
1104  continue;
1105 
1106  Instruction *TempIncV =
1107  cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock));
1108 
1109  // Check whether we can reuse this PHI node.
1110  if (LSRMode) {
1111  if (!isExpandedAddRecExprPHI(PN, TempIncV, L))
1112  continue;
1113  if (L == IVIncInsertLoop && !hoistIVInc(TempIncV, IVIncInsertPos))
1114  continue;
1115  } else {
1116  if (!isNormalAddRecExprPHI(PN, TempIncV, L))
1117  continue;
1118  }
1119 
1120  // Stop if we have found an exact match SCEV.
1121  if (IsMatchingSCEV) {
1122  IncV = TempIncV;
1123  TruncTy = nullptr;
1124  InvertStep = false;
1125  AddRecPhiMatch = PN;
1126  break;
1127  }
1128 
1129  // Try whether the phi can be translated into the requested form
1130  // (truncated and/or offset by a constant).
1131  if ((!TruncTy || InvertStep) &&
1132  canBeCheaplyTransformed(SE, PhiSCEV, Normalized, InvertStep)) {
1133  // Record the phi node. But don't stop we might find an exact match
1134  // later.
1135  AddRecPhiMatch = PN;
1136  IncV = TempIncV;
1137  TruncTy = SE.getEffectiveSCEVType(Normalized->getType());
1138  }
1139  }
1140 
1141  if (AddRecPhiMatch) {
1142  // Potentially, move the increment. We have made sure in
1143  // isExpandedAddRecExprPHI or hoistIVInc that this is possible.
1144  if (L == IVIncInsertLoop)
1145  hoistBeforePos(SE.DT, IncV, IVIncInsertPos, AddRecPhiMatch);
1146 
1147  // Ok, the add recurrence looks usable.
1148  // Remember this PHI, even in post-inc mode.
1149  InsertedValues.insert(AddRecPhiMatch);
1150  // Remember the increment.
1151  rememberInstruction(IncV);
1152  return AddRecPhiMatch;
1153  }
1154  }
1155 
1156  // Save the original insertion point so we can restore it when we're done.
1157  BuilderType::InsertPointGuard Guard(Builder);
1158 
1159  // Another AddRec may need to be recursively expanded below. For example, if
1160  // this AddRec is quadratic, the StepV may itself be an AddRec in this
1161  // loop. Remove this loop from the PostIncLoops set before expanding such
1162  // AddRecs. Otherwise, we cannot find a valid position for the step
1163  // (i.e. StepV can never dominate its loop header). Ideally, we could do
1164  // SavedIncLoops.swap(PostIncLoops), but we generally have a single element,
1165  // so it's not worth implementing SmallPtrSet::swap.
1166  PostIncLoopSet SavedPostIncLoops = PostIncLoops;
1167  PostIncLoops.clear();
1168 
1169  // Expand code for the start value.
1170  Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy,
1171  L->getHeader()->begin());
1172 
1173  // StartV must be hoisted into L's preheader to dominate the new phi.
1174  assert(!isa<Instruction>(StartV) ||
1175  SE.DT->properlyDominates(cast<Instruction>(StartV)->getParent(),
1176  L->getHeader()));
1177 
1178  // Expand code for the step value. Do this before creating the PHI so that PHI
1179  // reuse code doesn't see an incomplete PHI.
1180  const SCEV *Step = Normalized->getStepRecurrence(SE);
1181  // If the stride is negative, insert a sub instead of an add for the increment
1182  // (unless it's a constant, because subtracts of constants are canonicalized
1183  // to adds).
1184  bool useSubtract = !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
1185  if (useSubtract)
1186  Step = SE.getNegativeSCEV(Step);
1187  // Expand the step somewhere that dominates the loop header.
1188  Value *StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin());
1189 
1190  // The no-wrap behavior proved by IsIncrement(NUW|NSW) is only applicable if
1191  // we actually do emit an addition. It does not apply if we emit a
1192  // subtraction.
1193  bool IncrementIsNUW = !useSubtract && IsIncrementNUW(SE, Normalized);
1194  bool IncrementIsNSW = !useSubtract && IsIncrementNSW(SE, Normalized);
1195 
1196  // Create the PHI.
1197  BasicBlock *Header = L->getHeader();
1198  Builder.SetInsertPoint(Header, Header->begin());
1199  pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
1200  PHINode *PN = Builder.CreatePHI(ExpandTy, std::distance(HPB, HPE),
1201  Twine(IVName) + ".iv");
1202  rememberInstruction(PN);
1203 
1204  // Create the step instructions and populate the PHI.
1205  for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
1206  BasicBlock *Pred = *HPI;
1207 
1208  // Add a start value.
1209  if (!L->contains(Pred)) {
1210  PN->addIncoming(StartV, Pred);
1211  continue;
1212  }
1213 
1214  // Create a step value and add it to the PHI.
1215  // If IVIncInsertLoop is non-null and equal to the addrec's loop, insert the
1216  // instructions at IVIncInsertPos.
1217  Instruction *InsertPos = L == IVIncInsertLoop ?
1218  IVIncInsertPos : Pred->getTerminator();
1219  Builder.SetInsertPoint(InsertPos);
1220  Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
1221 
1222  if (isa<OverflowingBinaryOperator>(IncV)) {
1223  if (IncrementIsNUW)
1224  cast<BinaryOperator>(IncV)->setHasNoUnsignedWrap();
1225  if (IncrementIsNSW)
1226  cast<BinaryOperator>(IncV)->setHasNoSignedWrap();
1227  }
1228  PN->addIncoming(IncV, Pred);
1229  }
1230 
1231  // After expanding subexpressions, restore the PostIncLoops set so the caller
1232  // can ensure that IVIncrement dominates the current uses.
1233  PostIncLoops = SavedPostIncLoops;
1234 
1235  // Remember this PHI, even in post-inc mode.
1236  InsertedValues.insert(PN);
1237 
1238  return PN;
1239 }
1240 
1241 Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
1242  Type *STy = S->getType();
1243  Type *IntTy = SE.getEffectiveSCEVType(STy);
1244  const Loop *L = S->getLoop();
1245 
1246  // Determine a normalized form of this expression, which is the expression
1247  // before any post-inc adjustment is made.
1248  const SCEVAddRecExpr *Normalized = S;
1249  if (PostIncLoops.count(L)) {
1251  Loops.insert(L);
1252  Normalized =
1253  cast<SCEVAddRecExpr>(TransformForPostIncUse(Normalize, S, nullptr,
1254  nullptr, Loops, SE, *SE.DT));
1255  }
1256 
1257  // Strip off any non-loop-dominating component from the addrec start.
1258  const SCEV *Start = Normalized->getStart();
1259  const SCEV *PostLoopOffset = nullptr;
1260  if (!SE.properlyDominates(Start, L->getHeader())) {
1261  PostLoopOffset = Start;
1262  Start = SE.getConstant(Normalized->getType(), 0);
1263  Normalized = cast<SCEVAddRecExpr>(
1264  SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE),
1265  Normalized->getLoop(),
1266  Normalized->getNoWrapFlags(SCEV::FlagNW)));
1267  }
1268 
1269  // Strip off any non-loop-dominating component from the addrec step.
1270  const SCEV *Step = Normalized->getStepRecurrence(SE);
1271  const SCEV *PostLoopScale = nullptr;
1272  if (!SE.dominates(Step, L->getHeader())) {
1273  PostLoopScale = Step;
1274  Step = SE.getConstant(Normalized->getType(), 1);
1275  Normalized =
1276  cast<SCEVAddRecExpr>(SE.getAddRecExpr(
1277  Start, Step, Normalized->getLoop(),
1278  Normalized->getNoWrapFlags(SCEV::FlagNW)));
1279  }
1280 
1281  // Expand the core addrec. If we need post-loop scaling, force it to
1282  // expand to an integer type to avoid the need for additional casting.
1283  Type *ExpandTy = PostLoopScale ? IntTy : STy;
1284  // In some cases, we decide to reuse an existing phi node but need to truncate
1285  // it and/or invert the step.
1286  Type *TruncTy = nullptr;
1287  bool InvertStep = false;
1288  PHINode *PN = getAddRecExprPHILiterally(Normalized, L, ExpandTy, IntTy,
1289  TruncTy, InvertStep);
1290 
1291  // Accommodate post-inc mode, if necessary.
1292  Value *Result;
1293  if (!PostIncLoops.count(L))
1294  Result = PN;
1295  else {
1296  // In PostInc mode, use the post-incremented value.
1297  BasicBlock *LatchBlock = L->getLoopLatch();
1298  assert(LatchBlock && "PostInc mode requires a unique loop latch!");
1299  Result = PN->getIncomingValueForBlock(LatchBlock);
1300 
1301  // For an expansion to use the postinc form, the client must call
1302  // expandCodeFor with an InsertPoint that is either outside the PostIncLoop
1303  // or dominated by IVIncInsertPos.
1304  if (isa<Instruction>(Result)
1305  && !SE.DT->dominates(cast<Instruction>(Result),
1306  Builder.GetInsertPoint())) {
1307  // The induction variable's postinc expansion does not dominate this use.
1308  // IVUsers tries to prevent this case, so it is rare. However, it can
1309  // happen when an IVUser outside the loop is not dominated by the latch
1310  // block. Adjusting IVIncInsertPos before expansion begins cannot handle
1311  // all cases. Consider a phi outide whose operand is replaced during
1312  // expansion with the value of the postinc user. Without fundamentally
1313  // changing the way postinc users are tracked, the only remedy is
1314  // inserting an extra IV increment. StepV might fold into PostLoopOffset,
1315  // but hopefully expandCodeFor handles that.
1316  bool useSubtract =
1317  !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
1318  if (useSubtract)
1319  Step = SE.getNegativeSCEV(Step);
1320  Value *StepV;
1321  {
1322  // Expand the step somewhere that dominates the loop header.
1323  BuilderType::InsertPointGuard Guard(Builder);
1324  StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin());
1325  }
1326  Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
1327  }
1328  }
1329 
1330  // We have decided to reuse an induction variable of a dominating loop. Apply
1331  // truncation and/or invertion of the step.
1332  if (TruncTy) {
1333  Type *ResTy = Result->getType();
1334  // Normalize the result type.
1335  if (ResTy != SE.getEffectiveSCEVType(ResTy))
1336  Result = InsertNoopCastOfTo(Result, SE.getEffectiveSCEVType(ResTy));
1337  // Truncate the result.
1338  if (TruncTy != Result->getType()) {
1339  Result = Builder.CreateTrunc(Result, TruncTy);
1340  rememberInstruction(Result);
1341  }
1342  // Invert the result.
1343  if (InvertStep) {
1344  Result = Builder.CreateSub(expandCodeFor(Normalized->getStart(), TruncTy),
1345  Result);
1346  rememberInstruction(Result);
1347  }
1348  }
1349 
1350  // Re-apply any non-loop-dominating scale.
1351  if (PostLoopScale) {
1352  assert(S->isAffine() && "Can't linearly scale non-affine recurrences.");
1353  Result = InsertNoopCastOfTo(Result, IntTy);
1354  Result = Builder.CreateMul(Result,
1355  expandCodeFor(PostLoopScale, IntTy));
1356  rememberInstruction(Result);
1357  }
1358 
1359  // Re-apply any non-loop-dominating offset.
1360  if (PostLoopOffset) {
1361  if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
1362  const SCEV *const OffsetArray[1] = { PostLoopOffset };
1363  Result = expandAddToGEP(OffsetArray, OffsetArray+1, PTy, IntTy, Result);
1364  } else {
1365  Result = InsertNoopCastOfTo(Result, IntTy);
1366  Result = Builder.CreateAdd(Result,
1367  expandCodeFor(PostLoopOffset, IntTy));
1368  rememberInstruction(Result);
1369  }
1370  }
1371 
1372  return Result;
1373 }
1374 
1375 Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
1376  if (!CanonicalMode) return expandAddRecExprLiterally(S);
1377 
1378  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1379  const Loop *L = S->getLoop();
1380 
1381  // First check for an existing canonical IV in a suitable type.
1382  PHINode *CanonicalIV = nullptr;
1383  if (PHINode *PN = L->getCanonicalInductionVariable())
1384  if (SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
1385  CanonicalIV = PN;
1386 
1387  // Rewrite an AddRec in terms of the canonical induction variable, if
1388  // its type is more narrow.
1389  if (CanonicalIV &&
1390  SE.getTypeSizeInBits(CanonicalIV->getType()) >
1391  SE.getTypeSizeInBits(Ty)) {
1393  for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i)
1394  NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
1395  Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(),
1397  BasicBlock::iterator NewInsertPt =
1398  std::next(BasicBlock::iterator(cast<Instruction>(V)));
1399  BuilderType::InsertPointGuard Guard(Builder);
1400  while (isa<PHINode>(NewInsertPt) || isa<DbgInfoIntrinsic>(NewInsertPt) ||
1401  isa<LandingPadInst>(NewInsertPt))
1402  ++NewInsertPt;
1403  V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), nullptr,
1404  NewInsertPt);
1405  return V;
1406  }
1407 
1408  // {X,+,F} --> X + {0,+,F}
1409  if (!S->getStart()->isZero()) {
1410  SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end());
1411  NewOps[0] = SE.getConstant(Ty, 0);
1412  const SCEV *Rest = SE.getAddRecExpr(NewOps, L,
1414 
1415  // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
1416  // comments on expandAddToGEP for details.
1417  const SCEV *Base = S->getStart();
1418  const SCEV *RestArray[1] = { Rest };
1419  // Dig into the expression to find the pointer base for a GEP.
1420  ExposePointerBase(Base, RestArray[0], SE);
1421  // If we found a pointer, expand the AddRec with a GEP.
1422  if (PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
1423  // Make sure the Base isn't something exotic, such as a multiplied
1424  // or divided pointer value. In those cases, the result type isn't
1425  // actually a pointer type.
1426  if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
1427  Value *StartV = expand(Base);
1428  assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
1429  return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV);
1430  }
1431  }
1432 
1433  // Just do a normal add. Pre-expand the operands to suppress folding.
1434  return expand(SE.getAddExpr(SE.getUnknown(expand(S->getStart())),
1435  SE.getUnknown(expand(Rest))));
1436  }
1437 
1438  // If we don't yet have a canonical IV, create one.
1439  if (!CanonicalIV) {
1440  // Create and insert the PHI node for the induction variable in the
1441  // specified loop.
1442  BasicBlock *Header = L->getHeader();
1443  pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
1444  CanonicalIV = PHINode::Create(Ty, std::distance(HPB, HPE), "indvar",
1445  Header->begin());
1446  rememberInstruction(CanonicalIV);
1447 
1448  SmallSet<BasicBlock *, 4> PredSeen;
1449  Constant *One = ConstantInt::get(Ty, 1);
1450  for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
1451  BasicBlock *HP = *HPI;
1452  if (!PredSeen.insert(HP).second) {
1453  // There must be an incoming value for each predecessor, even the
1454  // duplicates!
1455  CanonicalIV->addIncoming(CanonicalIV->getIncomingValueForBlock(HP), HP);
1456  continue;
1457  }
1458 
1459  if (L->contains(HP)) {
1460  // Insert a unit add instruction right before the terminator
1461  // corresponding to the back-edge.
1462  Instruction *Add = BinaryOperator::CreateAdd(CanonicalIV, One,
1463  "indvar.next",
1464  HP->getTerminator());
1465  Add->setDebugLoc(HP->getTerminator()->getDebugLoc());
1466  rememberInstruction(Add);
1467  CanonicalIV->addIncoming(Add, HP);
1468  } else {
1469  CanonicalIV->addIncoming(Constant::getNullValue(Ty), HP);
1470  }
1471  }
1472  }
1473 
1474  // {0,+,1} --> Insert a canonical induction variable into the loop!
1475  if (S->isAffine() && S->getOperand(1)->isOne()) {
1476  assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
1477  "IVs with types different from the canonical IV should "
1478  "already have been handled!");
1479  return CanonicalIV;
1480  }
1481 
1482  // {0,+,F} --> {0,+,1} * F
1483 
1484  // If this is a simple linear addrec, emit it now as a special case.
1485  if (S->isAffine()) // {0,+,F} --> i*F
1486  return
1487  expand(SE.getTruncateOrNoop(
1488  SE.getMulExpr(SE.getUnknown(CanonicalIV),
1489  SE.getNoopOrAnyExtend(S->getOperand(1),
1490  CanonicalIV->getType())),
1491  Ty));
1492 
1493  // If this is a chain of recurrences, turn it into a closed form, using the
1494  // folders, then expandCodeFor the closed form. This allows the folders to
1495  // simplify the expression without having to build a bunch of special code
1496  // into this folder.
1497  const SCEV *IH = SE.getUnknown(CanonicalIV); // Get I as a "symbolic" SCEV.
1498 
1499  // Promote S up to the canonical IV type, if the cast is foldable.
1500  const SCEV *NewS = S;
1501  const SCEV *Ext = SE.getNoopOrAnyExtend(S, CanonicalIV->getType());
1502  if (isa<SCEVAddRecExpr>(Ext))
1503  NewS = Ext;
1504 
1505  const SCEV *V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE);
1506  //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
1507 
1508  // Truncate the result down to the original type, if needed.
1509  const SCEV *T = SE.getTruncateOrNoop(V, Ty);
1510  return expand(T);
1511 }
1512 
1513 Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
1514  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1515  Value *V = expandCodeFor(S->getOperand(),
1516  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1517  Value *I = Builder.CreateTrunc(V, Ty);
1518  rememberInstruction(I);
1519  return I;
1520 }
1521 
1522 Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
1523  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1524  Value *V = expandCodeFor(S->getOperand(),
1525  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1526  Value *I = Builder.CreateZExt(V, Ty);
1527  rememberInstruction(I);
1528  return I;
1529 }
1530 
1531 Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
1532  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1533  Value *V = expandCodeFor(S->getOperand(),
1534  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1535  Value *I = Builder.CreateSExt(V, Ty);
1536  rememberInstruction(I);
1537  return I;
1538 }
1539 
1540 Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
1541  Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
1542  Type *Ty = LHS->getType();
1543  for (int i = S->getNumOperands()-2; i >= 0; --i) {
1544  // In the case of mixed integer and pointer types, do the
1545  // rest of the comparisons as integer.
1546  if (S->getOperand(i)->getType() != Ty) {
1547  Ty = SE.getEffectiveSCEVType(Ty);
1548  LHS = InsertNoopCastOfTo(LHS, Ty);
1549  }
1550  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1551  Value *ICmp = Builder.CreateICmpSGT(LHS, RHS);
1552  rememberInstruction(ICmp);
1553  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
1554  rememberInstruction(Sel);
1555  LHS = Sel;
1556  }
1557  // In the case of mixed integer and pointer types, cast the
1558  // final result back to the pointer type.
1559  if (LHS->getType() != S->getType())
1560  LHS = InsertNoopCastOfTo(LHS, S->getType());
1561  return LHS;
1562 }
1563 
1564 Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
1565  Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
1566  Type *Ty = LHS->getType();
1567  for (int i = S->getNumOperands()-2; i >= 0; --i) {
1568  // In the case of mixed integer and pointer types, do the
1569  // rest of the comparisons as integer.
1570  if (S->getOperand(i)->getType() != Ty) {
1571  Ty = SE.getEffectiveSCEVType(Ty);
1572  LHS = InsertNoopCastOfTo(LHS, Ty);
1573  }
1574  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1575  Value *ICmp = Builder.CreateICmpUGT(LHS, RHS);
1576  rememberInstruction(ICmp);
1577  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
1578  rememberInstruction(Sel);
1579  LHS = Sel;
1580  }
1581  // In the case of mixed integer and pointer types, cast the
1582  // final result back to the pointer type.
1583  if (LHS->getType() != S->getType())
1584  LHS = InsertNoopCastOfTo(LHS, S->getType());
1585  return LHS;
1586 }
1587 
1589  Instruction *IP) {
1590  Builder.SetInsertPoint(IP->getParent(), IP);
1591  return expandCodeFor(SH, Ty);
1592 }
1593 
1594 Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty) {
1595  // Expand the code for this SCEV.
1596  Value *V = expand(SH);
1597  if (Ty) {
1598  assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) &&
1599  "non-trivial casts should be done with the SCEVs directly!");
1600  V = InsertNoopCastOfTo(V, Ty);
1601  }
1602  return V;
1603 }
1604 
1605 Value *SCEVExpander::expand(const SCEV *S) {
1606  // Compute an insertion point for this SCEV object. Hoist the instructions
1607  // as far out in the loop nest as possible.
1608  Instruction *InsertPt = Builder.GetInsertPoint();
1609  for (Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock()); ;
1610  L = L->getParentLoop())
1611  if (SE.isLoopInvariant(S, L)) {
1612  if (!L) break;
1613  if (BasicBlock *Preheader = L->getLoopPreheader())
1614  InsertPt = Preheader->getTerminator();
1615  else {
1616  // LSR sets the insertion point for AddRec start/step values to the
1617  // block start to simplify value reuse, even though it's an invalid
1618  // position. SCEVExpander must correct for this in all cases.
1619  InsertPt = L->getHeader()->getFirstInsertionPt();
1620  }
1621  } else {
1622  // If the SCEV is computable at this level, insert it into the header
1623  // after the PHIs (and after any other instructions that we've inserted
1624  // there) so that it is guaranteed to dominate any user inside the loop.
1625  if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
1626  InsertPt = L->getHeader()->getFirstInsertionPt();
1627  while (InsertPt != Builder.GetInsertPoint()
1628  && (isInsertedInstruction(InsertPt)
1629  || isa<DbgInfoIntrinsic>(InsertPt))) {
1630  InsertPt = std::next(BasicBlock::iterator(InsertPt));
1631  }
1632  break;
1633  }
1634 
1635  // Check to see if we already expanded this here.
1636  std::map<std::pair<const SCEV *, Instruction *>, TrackingVH<Value> >::iterator
1637  I = InsertedExpressions.find(std::make_pair(S, InsertPt));
1638  if (I != InsertedExpressions.end())
1639  return I->second;
1640 
1641  BuilderType::InsertPointGuard Guard(Builder);
1642  Builder.SetInsertPoint(InsertPt->getParent(), InsertPt);
1643 
1644  // Expand the expression into instructions.
1645  Value *V = visit(S);
1646 
1647  // Remember the expanded value for this SCEV at this location.
1648  //
1649  // This is independent of PostIncLoops. The mapped value simply materializes
1650  // the expression at this insertion point. If the mapped value happened to be
1651  // a postinc expansion, it could be reused by a non-postinc user, but only if
1652  // its insertion point was already at the head of the loop.
1653  InsertedExpressions[std::make_pair(S, InsertPt)] = V;
1654  return V;
1655 }
1656 
1657 void SCEVExpander::rememberInstruction(Value *I) {
1658  if (!PostIncLoops.empty())
1659  InsertedPostIncValues.insert(I);
1660  else
1661  InsertedValues.insert(I);
1662 }
1663 
1664 /// getOrInsertCanonicalInductionVariable - This method returns the
1665 /// canonical induction variable of the specified type for the specified
1666 /// loop (inserting one if there is none). A canonical induction variable
1667 /// starts at zero and steps by one on each iteration.
1668 PHINode *
1670  Type *Ty) {
1671  assert(Ty->isIntegerTy() && "Can only insert integer induction variables!");
1672 
1673  // Build a SCEV for {0,+,1}<L>.
1674  // Conservatively use FlagAnyWrap for now.
1675  const SCEV *H = SE.getAddRecExpr(SE.getConstant(Ty, 0),
1676  SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
1677 
1678  // Emit code for it.
1679  BuilderType::InsertPointGuard Guard(Builder);
1680  PHINode *V = cast<PHINode>(expandCodeFor(H, nullptr,
1681  L->getHeader()->begin()));
1682 
1683  return V;
1684 }
1685 
1686 /// replaceCongruentIVs - Check for congruent phis in this loop header and
1687 /// replace them with their most canonical representative. Return the number of
1688 /// phis eliminated.
1689 ///
1690 /// This does not depend on any SCEVExpander state but should be used in
1691 /// the same context that SCEVExpander is used.
1693  SmallVectorImpl<WeakVH> &DeadInsts,
1694  const TargetTransformInfo *TTI) {
1695  // Find integer phis in order of increasing width.
1697  for (BasicBlock::iterator I = L->getHeader()->begin();
1698  PHINode *Phi = dyn_cast<PHINode>(I); ++I) {
1699  Phis.push_back(Phi);
1700  }
1701  if (TTI)
1702  std::sort(Phis.begin(), Phis.end(), [](Value *LHS, Value *RHS) {
1703  // Put pointers at the back and make sure pointer < pointer = false.
1704  if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
1705  return RHS->getType()->isIntegerTy() && !LHS->getType()->isIntegerTy();
1706  return RHS->getType()->getPrimitiveSizeInBits() <
1707  LHS->getType()->getPrimitiveSizeInBits();
1708  });
1709 
1710  unsigned NumElim = 0;
1712  // Process phis from wide to narrow. Map wide phis to their truncation
1713  // so narrow phis can reuse them.
1715  PEnd = Phis.end(); PIter != PEnd; ++PIter) {
1716  PHINode *Phi = *PIter;
1717 
1718  // Fold constant phis. They may be congruent to other constant phis and
1719  // would confuse the logic below that expects proper IVs.
1720  if (Value *V = SimplifyInstruction(Phi, DL, SE.TLI, SE.DT, SE.AC)) {
1721  Phi->replaceAllUsesWith(V);
1722  DeadInsts.emplace_back(Phi);
1723  ++NumElim;
1725  << "INDVARS: Eliminated constant iv: " << *Phi << '\n');
1726  continue;
1727  }
1728 
1729  if (!SE.isSCEVable(Phi->getType()))
1730  continue;
1731 
1732  PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
1733  if (!OrigPhiRef) {
1734  OrigPhiRef = Phi;
1735  if (Phi->getType()->isIntegerTy() && TTI
1736  && TTI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
1737  // This phi can be freely truncated to the narrowest phi type. Map the
1738  // truncated expression to it so it will be reused for narrow types.
1739  const SCEV *TruncExpr =
1740  SE.getTruncateExpr(SE.getSCEV(Phi), Phis.back()->getType());
1741  ExprToIVMap[TruncExpr] = Phi;
1742  }
1743  continue;
1744  }
1745 
1746  // Replacing a pointer phi with an integer phi or vice-versa doesn't make
1747  // sense.
1748  if (OrigPhiRef->getType()->isPointerTy() != Phi->getType()->isPointerTy())
1749  continue;
1750 
1751  if (BasicBlock *LatchBlock = L->getLoopLatch()) {
1752  Instruction *OrigInc =
1753  cast<Instruction>(OrigPhiRef->getIncomingValueForBlock(LatchBlock));
1754  Instruction *IsomorphicInc =
1755  cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
1756 
1757  // If this phi has the same width but is more canonical, replace the
1758  // original with it. As part of the "more canonical" determination,
1759  // respect a prior decision to use an IV chain.
1760  if (OrigPhiRef->getType() == Phi->getType()
1761  && !(ChainedPhis.count(Phi)
1762  || isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L))
1763  && (ChainedPhis.count(Phi)
1764  || isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
1765  std::swap(OrigPhiRef, Phi);
1766  std::swap(OrigInc, IsomorphicInc);
1767  }
1768  // Replacing the congruent phi is sufficient because acyclic redundancy
1769  // elimination, CSE/GVN, should handle the rest. However, once SCEV proves
1770  // that a phi is congruent, it's often the head of an IV user cycle that
1771  // is isomorphic with the original phi. It's worth eagerly cleaning up the
1772  // common case of a single IV increment so that DeleteDeadPHIs can remove
1773  // cycles that had postinc uses.
1774  const SCEV *TruncExpr = SE.getTruncateOrNoop(SE.getSCEV(OrigInc),
1775  IsomorphicInc->getType());
1776  if (OrigInc != IsomorphicInc
1777  && TruncExpr == SE.getSCEV(IsomorphicInc)
1778  && ((isa<PHINode>(OrigInc) && isa<PHINode>(IsomorphicInc))
1779  || hoistIVInc(OrigInc, IsomorphicInc))) {
1781  << "INDVARS: Eliminated congruent iv.inc: "
1782  << *IsomorphicInc << '\n');
1783  Value *NewInc = OrigInc;
1784  if (OrigInc->getType() != IsomorphicInc->getType()) {
1785  Instruction *IP = nullptr;
1786  if (PHINode *PN = dyn_cast<PHINode>(OrigInc))
1787  IP = PN->getParent()->getFirstInsertionPt();
1788  else
1789  IP = OrigInc->getNextNode();
1790 
1791  IRBuilder<> Builder(IP);
1792  Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
1793  NewInc = Builder.
1794  CreateTruncOrBitCast(OrigInc, IsomorphicInc->getType(), IVName);
1795  }
1796  IsomorphicInc->replaceAllUsesWith(NewInc);
1797  DeadInsts.emplace_back(IsomorphicInc);
1798  }
1799  }
1801  << "INDVARS: Eliminated congruent iv: " << *Phi << '\n');
1802  ++NumElim;
1803  Value *NewIV = OrigPhiRef;
1804  if (OrigPhiRef->getType() != Phi->getType()) {
1805  IRBuilder<> Builder(L->getHeader()->getFirstInsertionPt());
1806  Builder.SetCurrentDebugLocation(Phi->getDebugLoc());
1807  NewIV = Builder.CreateTruncOrBitCast(OrigPhiRef, Phi->getType(), IVName);
1808  }
1809  Phi->replaceAllUsesWith(NewIV);
1810  DeadInsts.emplace_back(Phi);
1811  }
1812  return NumElim;
1813 }
1814 
1815 bool SCEVExpander::isHighCostExpansionHelper(
1816  const SCEV *S, Loop *L, SmallPtrSetImpl<const SCEV *> &Processed) {
1817 
1818  // Zero/One operand expressions
1819  switch (S->getSCEVType()) {
1820  case scUnknown:
1821  case scConstant:
1822  return false;
1823  case scTruncate:
1824  return isHighCostExpansionHelper(cast<SCEVTruncateExpr>(S)->getOperand(), L,
1825  Processed);
1826  case scZeroExtend:
1827  return isHighCostExpansionHelper(cast<SCEVZeroExtendExpr>(S)->getOperand(),
1828  L, Processed);
1829  case scSignExtend:
1830  return isHighCostExpansionHelper(cast<SCEVSignExtendExpr>(S)->getOperand(),
1831  L, Processed);
1832  }
1833 
1834  if (!Processed.insert(S).second)
1835  return false;
1836 
1837  if (auto *UDivExpr = dyn_cast<SCEVUDivExpr>(S)) {
1838  // If the divisor is a power of two and the SCEV type fits in a native
1839  // integer, consider the divison cheap irrespective of whether it occurs in
1840  // the user code since it can be lowered into a right shift.
1841  if (auto *SC = dyn_cast<SCEVConstant>(UDivExpr->getRHS()))
1842  if (SC->getValue()->getValue().isPowerOf2()) {
1843  const DataLayout &DL =
1844  L->getHeader()->getParent()->getParent()->getDataLayout();
1845  unsigned Width = cast<IntegerType>(UDivExpr->getType())->getBitWidth();
1846  return DL.isIllegalInteger(Width);
1847  }
1848 
1849  // UDivExpr is very likely a UDiv that ScalarEvolution's HowFarToZero or
1850  // HowManyLessThans produced to compute a precise expression, rather than a
1851  // UDiv from the user's code. If we can't find a UDiv in the code with some
1852  // simple searching, assume the former consider UDivExpr expensive to
1853  // compute.
1854  BasicBlock *ExitingBB = L->getExitingBlock();
1855  if (!ExitingBB)
1856  return true;
1857 
1858  BranchInst *ExitingBI = dyn_cast<BranchInst>(ExitingBB->getTerminator());
1859  if (!ExitingBI || !ExitingBI->isConditional())
1860  return true;
1861 
1862  ICmpInst *OrigCond = dyn_cast<ICmpInst>(ExitingBI->getCondition());
1863  if (!OrigCond)
1864  return true;
1865 
1866  const SCEV *RHS = SE.getSCEV(OrigCond->getOperand(1));
1867  RHS = SE.getMinusSCEV(RHS, SE.getConstant(RHS->getType(), 1));
1868  if (RHS != S) {
1869  const SCEV *LHS = SE.getSCEV(OrigCond->getOperand(0));
1870  LHS = SE.getMinusSCEV(LHS, SE.getConstant(LHS->getType(), 1));
1871  if (LHS != S)
1872  return true;
1873  }
1874  }
1875 
1876  // HowManyLessThans uses a Max expression whenever the loop is not guarded by
1877  // the exit condition.
1878  if (isa<SCEVSMaxExpr>(S) || isa<SCEVUMaxExpr>(S))
1879  return true;
1880 
1881  // Recurse past nary expressions, which commonly occur in the
1882  // BackedgeTakenCount. They may already exist in program code, and if not,
1883  // they are not too expensive rematerialize.
1884  if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(S)) {
1885  for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
1886  I != E; ++I) {
1887  if (isHighCostExpansionHelper(*I, L, Processed))
1888  return true;
1889  }
1890  }
1891 
1892  // If we haven't recognized an expensive SCEV pattern, assume it's an
1893  // expression produced by program code.
1894  return false;
1895 }
1896 
1897 namespace {
1898 // Search for a SCEV subexpression that is not safe to expand. Any expression
1899 // that may expand to a !isSafeToSpeculativelyExecute value is unsafe, namely
1900 // UDiv expressions. We don't know if the UDiv is derived from an IR divide
1901 // instruction, but the important thing is that we prove the denominator is
1902 // nonzero before expansion.
1903 //
1904 // IVUsers already checks that IV-derived expressions are safe. So this check is
1905 // only needed when the expression includes some subexpression that is not IV
1906 // derived.
1907 //
1908 // Currently, we only allow division by a nonzero constant here. If this is
1909 // inadequate, we could easily allow division by SCEVUnknown by using
1910 // ValueTracking to check isKnownNonZero().
1911 //
1912 // We cannot generally expand recurrences unless the step dominates the loop
1913 // header. The expander handles the special case of affine recurrences by
1914 // scaling the recurrence outside the loop, but this technique isn't generally
1915 // applicable. Expanding a nested recurrence outside a loop requires computing
1916 // binomial coefficients. This could be done, but the recurrence has to be in a
1917 // perfectly reduced form, which can't be guaranteed.
1918 struct SCEVFindUnsafe {
1919  ScalarEvolution &SE;
1920  bool IsUnsafe;
1921 
1922  SCEVFindUnsafe(ScalarEvolution &se): SE(se), IsUnsafe(false) {}
1923 
1924  bool follow(const SCEV *S) {
1925  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
1926  const SCEVConstant *SC = dyn_cast<SCEVConstant>(D->getRHS());
1927  if (!SC || SC->getValue()->isZero()) {
1928  IsUnsafe = true;
1929  return false;
1930  }
1931  }
1932  if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
1933  const SCEV *Step = AR->getStepRecurrence(SE);
1934  if (!AR->isAffine() && !SE.dominates(Step, AR->getLoop()->getHeader())) {
1935  IsUnsafe = true;
1936  return false;
1937  }
1938  }
1939  return true;
1940  }
1941  bool isDone() const { return IsUnsafe; }
1942 };
1943 }
1944 
1945 namespace llvm {
1946 bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE) {
1947  SCEVFindUnsafe Search(SE);
1948  visitAll(S, Search);
1949  return !Search.IsUnsafe;
1950 }
1951 }
NoWrapFlags getNoWrapFlags(NoWrapFlags Mask=NoWrapMask) const
static unsigned getBitWidth(Type *Ty, const DataLayout &DL)
Returns the bitwidth of the given scalar or pointer type (if unknown returns 0).
const SCEV * getTruncateOrNoop(const SCEV *V, Type *Ty)
getTruncateOrNoop - Return a SCEV corresponding to a conversion of the input value to the specified t...
std::reverse_iterator< iterator > reverse_iterator
Definition: SmallVector.h:104
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:104
bool hoistIVInc(Instruction *IncV, Instruction *InsertPos)
Utility for hoisting an IV increment.
static IntegerType * getInt1Ty(LLVMContext &C)
Definition: Type.cpp:236
void addIncoming(Value *V, BasicBlock *BB)
addIncoming - Add an incoming value to the end of the PHI list
LLVM Argument representation.
Definition: Argument.h:35
const SCEV * TransformForPostIncUse(TransformKind Kind, const SCEV *S, Instruction *User, Value *OperandValToReplace, PostIncLoopSet &Loops, ScalarEvolution &SE, DominatorTree &DT)
TransformForPostIncUse - Transform the given expression according to the given transformation kind...
bool isOne() const
isOne - Return true if the expression is a constant one.
const SCEV * getConstant(ConstantInt *V)
LLVMContext & getContext() const
bool isZero() const
isZero - Return true if the expression is a constant zero.
unsigned getNumOperands() const
Definition: User.h:138
ScalarEvolution - This class is the main scalar evolution driver.
static PointerType * get(Type *ElementType, unsigned AddressSpace)
PointerType::get - This constructs a pointer to an object of the specified type in a numbered address...
Definition: Type.cpp:738
bool mayHaveSideEffects() const
mayHaveSideEffects - Return true if the instruction may have side effects.
Definition: Instruction.h:387
static Constant * getGetElementPtr(Type *Ty, Constant *C, ArrayRef< Constant * > IdxList, bool InBounds=false, Type *OnlyIfReducedTy=nullptr)
Getelementptr form.
Definition: Constants.h:1092
bool isIllegalInteger(unsigned Width) const
Definition: DataLayout.h:246
const SCEV * getStepRecurrence(ScalarEvolution &SE) const
getStepRecurrence - This method constructs and returns the recurrence indicating how much this expres...
SCEVTruncateExpr - This class represents a truncation of an integer value to a smaller integer value...
LoopT * getParentLoop() const
Definition: LoopInfo.h:97
A debug info location.
Definition: DebugLoc.h:34
unsigned getAddressSpace() const
Return the address space of the Pointer type.
Definition: DerivedTypes.h:472
Hexagon Common GEP
op_iterator op_begin()
Definition: User.h:183
BlockT * getHeader() const
Definition: LoopInfo.h:96
SCEVCastExpr - This is the base class for unary cast operator classes.
const SCEV * getStart() const
static Constant * getNullValue(Type *Ty)
Definition: Constants.cpp:178
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:188
BlockT * getLoopLatch() const
getLoopLatch - If there is a single latch block for this loop, return it.
Definition: LoopInfoImpl.h:156
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:242
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:231
#define DEBUG_WITH_TYPE(TYPE, X)
DEBUG_WITH_TYPE macro - This macro should be used by passes to emit debug information.
Definition: Debug.h:62
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:41
Used to lazily calculate structure layout information for a target machine, based on the DataLayout s...
Definition: DataLayout.h:475
Hexagon Hardware Loops
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:79
static const Loop * PickMostRelevantLoop(const Loop *A, const Loop *B, DominatorTree &DT)
PickMostRelevantLoop - Given two loops pick the one that's most relevant for SCEV expansion...
This is the base class for all instructions that perform data casts.
Definition: InstrTypes.h:389
NodeTy * getNextNode()
Get the next node, or 0 for the list tail.
Definition: ilist_node.h:80
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:106
StructType - Class to represent struct types.
Definition: DerivedTypes.h:191
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
A Use represents the edge between a Value definition and its users.
Definition: Use.h:69
const SCEV *const * op_iterator
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APInt.h:33
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:517
bool isSized(SmallPtrSetImpl< const Type * > *Visited=nullptr) const
isSized - Return true if it makes sense to take the size of this type.
Definition: Type.h:268
Windows NT (Windows on ARM)
op_iterator op_begin() const
#define false
Definition: ConvertUTF.c:65
SCEVMulExpr - This node represents multiplication of some number of SCEVs.
static Constant * get(unsigned Opcode, Constant *C1, Constant *C2, unsigned Flags=0, Type *OnlyIfReducedTy=nullptr)
get - Return a binary or shift operator constant expression, folding if possible. ...
Definition: Constants.cpp:1868
ConstantExpr - a constant value that is initialized with an expression using other constant values...
Definition: Constants.h:852
LLVMContext & getContext() const
getContext - Return the LLVMContext in which this type was uniqued.
Definition: Type.h:125
SCEVAddRecExpr - This node represents a polynomial recurrence on the trip count of the specified loop...
bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const
Definition: SmallVector.h:57
ArrayType - Class to represent array types.
Definition: DerivedTypes.h:336
void SetCurrentDebugLocation(DebugLoc L)
Set location information used by debugging information.
Definition: IRBuilder.h:109
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:351
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power of 2.
Definition: PatternMatch.h:272
Type * getEffectiveSCEVType(Type *Ty) const
getEffectiveSCEVType - Return a type with the same bitwidth as the given type and which represents ho...
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:256
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:67
Type * getElementType() const
Definition: DerivedTypes.h:323
const SCEV * getAddRecExpr(const SCEV *Start, const SCEV *Step, const Loop *L, SCEV::NoWrapFlags Flags)
getAddRecExpr - Get an add recurrence expression for the specified loop.
static BinaryOperator * CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
PointerType - Class to represent pointers.
Definition: DerivedTypes.h:449
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:491
SCEVUnknown - This means that we are dealing with an entirely unknown SCEV value, and only represent ...
bool isAffine() const
isAffine - Return true if this represents an expression A + B*x where A and B are loop invariant valu...
void setDebugLoc(DebugLoc Loc)
setDebugLoc - Set the debug location information for this instruction.
Definition: Instruction.h:227
BlockT * getLoopPreheader() const
getLoopPreheader - If there is a preheader for this loop, return it.
Definition: LoopInfoImpl.h:108
LLVM Basic Block Representation.
Definition: BasicBlock.h:65
SCEVUDivExpr - This class represents a binary unsigned division operation.
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
static volatile int One
Definition: InfiniteTest.cpp:9
Type * getType() const
getType - Return the LLVM type of this SCEV expression.
BranchInst - Conditional or Unconditional Branch instruction.
static void SplitAddRecs(SmallVectorImpl< const SCEV * > &Ops, Type *Ty, ScalarEvolution &SE)
SplitAddRecs - Flatten a list of add operands, moving addrec start values out to the top level...
bool isVectorTy() const
isVectorTy - True if this is an instance of VectorType.
Definition: Type.h:226
Value handle that tracks a Value across RAUW.
Definition: ValueHandle.h:280
This is an important base class in LLVM.
Definition: Constant.h:41
const SCEV * getOperand(unsigned i) const
SmallSet - This maintains a set of unique values, optimizing for the case when the set is small (less...
Definition: SmallSet.h:32
#define H(x, y, z)
Definition: MD5.cpp:53
Normalize - Normalize according to the given loops.
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:264
Interval::pred_iterator pred_begin(Interval *I)
pred_begin/pred_end - define methods so that Intervals may be used just like BasicBlocks can with the...
Definition: Interval.h:114
const DebugLoc & getDebugLoc() const
getDebugLoc - Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:230
op_iterator op_end()
Definition: User.h:185
bool contains(const LoopT *L) const
contains - Return true if the specified loop is contained within in this loop.
Definition: LoopInfo.h:105
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang","erlang-compatible garbage collector")
This instruction compares its operands according to the predicate given to the constructor.
static bool FactorOutConstant(const SCEV *&S, const SCEV *&Remainder, const SCEV *Factor, ScalarEvolution &SE, const DataLayout &DL)
FactorOutConstant - Test if S is divisible by Factor, using signed division.
Value * expandCodeFor(const SCEV *SH, Type *Ty, Instruction *I)
Insert code to directly compute the specified SCEV expression into the program.
BlockT * getExitingBlock() const
getExitingBlock - If getExitingBlocks would return exactly one block, return that block...
Definition: LoopInfoImpl.h:51
Value * getOperand(unsigned i) const
Definition: User.h:118
Interval::pred_iterator pred_end(Interval *I)
Definition: Interval.h:117
std::pair< NoneType, bool > insert(const T &V)
insert - Insert an element into the set if it isn't already there.
Definition: SmallSet.h:69
const SCEV * getLHS() const
static void SimplifyAddOperands(SmallVectorImpl< const SCEV * > &Ops, Type *Ty, ScalarEvolution &SE)
SimplifyAddOperands - Sort and simplify a list of add operands.
void append(in_iter in_start, in_iter in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:416
bool isPointerTy() const
isPointerTy - True if this is an instance of PointerType.
Definition: Type.h:217
static UndefValue * get(Type *T)
get() - Static factory methods - Return an 'undef' object of the specified type.
Definition: Constants.cpp:1473
bool isNonConstantNegative() const
isNonConstantNegative - Return true if the specified scev is negated, but not a constant.
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:283
bool isPowerOf2() const
Check if this APInt's value is a power of two greater than zero.
Definition: APInt.h:386
const SCEV * getRHS() const
static bool IsIncrementNSW(ScalarEvolution &SE, const SCEVAddRecExpr *AR)
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:214
static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest, ScalarEvolution &SE)
Move parts of Base into Rest to leave Base with the minimal expression that provides a pointer operan...
bool isConditional() const
unsigned replaceCongruentIVs(Loop *L, const DominatorTree *DT, SmallVectorImpl< WeakVH > &DeadInsts, const TargetTransformInfo *TTI=nullptr)
replace congruent phis with their most canonical representative.
static IntegerType * get(LLVMContext &C, unsigned NumBits)
This static method is the primary way of constructing an IntegerType.
Definition: Type.cpp:304
static PointerType * getInt1PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:279
unsigned getIntegerBitWidth() const
Definition: Type.cpp:176
This is the shared class of boolean and integer constants.
Definition: Constants.h:47
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
unsigned logBase2() const
Definition: APInt.h:1521
PHINode * getOrInsertCanonicalInductionVariable(const Loop *L, Type *Ty)
This method returns the canonical induction variable of the specified type for the specified loop (in...
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
bool isAllOnesValue() const
isAllOnesValue - Return true if the expression is a constant all-ones value.
Module.h This file contains the declarations for the Module class.
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:222
CHAIN = SC CHAIN, Imm128 - System call.
uint64_t getSizeInBytes() const
Definition: DataLayout.h:481
PHINode * getCanonicalInductionVariable() const
getCanonicalInductionVariable - Check to see if the loop has a canonical induction variable: an integ...
Definition: LoopInfo.cpp:135
unsigned getElementContainingOffset(uint64_t Offset) const
Given a valid byte offset into the structure, returns the structure index that contains it...
Definition: DataLayout.cpp:74
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:582
bool isZero() const
This is just a convenience method to make client code smaller for a common code.
Definition: Constants.h:161
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...
ConstantInt * getValue() const
static void hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist, Instruction *Pos, PHINode *LoopPhi)
Hoist the addrec instruction chain rooted in the loop phi above the position.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:123
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:576
Class for arbitrary precision integers.
Definition: APInt.h:73
SCEVAddExpr - This node represents an addition of some number of SCEVs.
const SCEV * getSignExtendExpr(const SCEV *Op, Type *Ty)
Value * getIncomingValueForBlock(const BasicBlock *BB) const
bool isIntegerTy() const
isIntegerTy - True if this is an instance of IntegerType.
Definition: Type.h:193
SCEVSMaxExpr - This class represents a signed maximum selection.
iterator_range< user_iterator > users()
Definition: Value.h:300
LLVM_ATTRIBUTE_UNUSED_RESULT std::enable_if< !is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:285
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1591
const SCEV * getAddExpr(SmallVectorImpl< const SCEV * > &Ops, SCEV::NoWrapFlags Flags=SCEV::FlagAnyWrap)
getAddExpr - Get a canonical add expression, or something simpler if possible.
void visitAll(const SCEV *Root, SV &Visitor)
Use SCEVTraversal to visit all nodes in the given expression tree.
SCEVZeroExtendExpr - This class represents a zero extension of a small integer value to a larger inte...
static bool IsIncrementNUW(ScalarEvolution &SE, const SCEVAddRecExpr *AR)
static CastInst * Create(Instruction::CastOps, Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Provides a way to construct any of the CastInst subclasses using an opcode instead of the subclass's ...
Value * getCondition() const
void emplace_back(ArgTypes &&...Args)
Definition: SmallVector.h:652
SCEV - This class represents an analyzed expression in the program.
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:239
static Instruction::CastOps getCastOpcode(const Value *Val, bool SrcIsSigned, Type *Ty, bool DstIsSigned)
Returns the opcode necessary to cast Val into Ty using usual casting rules.
#define I(x, y, z)
Definition: MD5.cpp:54
#define N
static cl::opt< unsigned > ScanLimit("aarch64-load-store-scan-limit", cl::init(20), cl::Hidden)
TerminatorInst * getTerminator()
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:124
SCEVSignExtendExpr - This class represents a sign extension of a small integer value to a larger inte...
SCEVUMaxExpr - This class represents an unsigned maximum selection.
Instruction * getIVIncOperand(Instruction *IncV, Instruction *InsertPos, bool allowScale)
Return the induction variable increment's IV operand.
const Loop * getLoop() const
unsigned getSCEVType() const
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
getPrimitiveSizeInBits - Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:121
LLVM Value Representation.
Definition: Value.h:69
unsigned getOpcode() const
getOpcode() returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:112
void moveBefore(Instruction *MovePos)
moveBefore - Unlink this instruction from its current basic block and insert it into the basic block ...
Definition: Instruction.cpp:89
bool isTruncateFree(Type *Ty1, Type *Ty2) const
Return true if it's free to truncate a value of type Ty1 to type Ty2.
InvokeInst - Invoke instruction.
C - The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
op_iterator op_end() const
Value * SimplifyInstruction(Instruction *I, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr)
SimplifyInstruction - See if we can compute a simplified version of this instruction.
This pass exposes codegen information to IR-level passes.
const SCEV * getNegativeSCEV(const SCEV *V)
getNegativeSCEV - Return the SCEV object corresponding to -V.
iterator getFirstInsertionPt()
Returns an iterator to the first instruction in this block that is suitable for inserting a non-PHI i...
Definition: BasicBlock.cpp:194
const SCEV * getZeroExtendExpr(const SCEV *Op, Type *Ty)
SCEVNAryExpr - This node is a base class providing common functionality for n'ary operators...
bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE)
Return true if the given expression is safe to expand in the sense that all materialized values are s...
const SCEV * getOperand() const
const SCEV * getMulExpr(SmallVectorImpl< const SCEV * > &Ops, SCEV::NoWrapFlags Flags=SCEV::FlagAnyWrap)
getMulExpr - Get a canonical multiply expression, or something simpler if possible.
static IntegerType * getInt8Ty(LLVMContext &C)
Definition: Type.cpp:237
const BasicBlock * getParent() const
Definition: Instruction.h:72
static bool canBeCheaplyTransformed(ScalarEvolution &SE, const SCEVAddRecExpr *Phi, const SCEVAddRecExpr *Requested, bool &InvertStep)
Check whether we can cheaply express the requested SCEV in terms of the available PHI SCEV by truncat...
SCEVConstant - This class represents a constant integer value.