LLVM  7.0.0svn
ScalarEvolutionExpander.cpp
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1 //===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis ------------===//
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 
90  BasicBlock *MustDominate) {
92  if (auto *II = dyn_cast<InvokeInst>(I))
93  IP = II->getNormalDest()->begin();
94 
95  while (isa<PHINode>(IP))
96  ++IP;
97 
98  if (isa<FuncletPadInst>(IP) || isa<LandingPadInst>(IP)) {
99  ++IP;
100  } else if (isa<CatchSwitchInst>(IP)) {
101  IP = MustDominate->getFirstInsertionPt();
102  } else {
103  assert(!IP->isEHPad() && "unexpected eh pad!");
104  }
105 
106  return IP;
107 }
108 
109 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
110 /// which must be possible with a noop cast, doing what we can to share
111 /// the casts.
112 Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) {
113  Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false);
114  assert((Op == Instruction::BitCast ||
115  Op == Instruction::PtrToInt ||
116  Op == Instruction::IntToPtr) &&
117  "InsertNoopCastOfTo cannot perform non-noop casts!");
118  assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) &&
119  "InsertNoopCastOfTo cannot change sizes!");
120 
121  // Short-circuit unnecessary bitcasts.
122  if (Op == Instruction::BitCast) {
123  if (V->getType() == Ty)
124  return V;
125  if (CastInst *CI = dyn_cast<CastInst>(V)) {
126  if (CI->getOperand(0)->getType() == Ty)
127  return CI->getOperand(0);
128  }
129  }
130  // Short-circuit unnecessary inttoptr<->ptrtoint casts.
131  if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) &&
132  SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {
133  if (CastInst *CI = dyn_cast<CastInst>(V))
134  if ((CI->getOpcode() == Instruction::PtrToInt ||
135  CI->getOpcode() == Instruction::IntToPtr) &&
136  SE.getTypeSizeInBits(CI->getType()) ==
137  SE.getTypeSizeInBits(CI->getOperand(0)->getType()))
138  return CI->getOperand(0);
139  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
140  if ((CE->getOpcode() == Instruction::PtrToInt ||
141  CE->getOpcode() == Instruction::IntToPtr) &&
142  SE.getTypeSizeInBits(CE->getType()) ==
143  SE.getTypeSizeInBits(CE->getOperand(0)->getType()))
144  return CE->getOperand(0);
145  }
146 
147  // Fold a cast of a constant.
148  if (Constant *C = dyn_cast<Constant>(V))
149  return ConstantExpr::getCast(Op, C, Ty);
150 
151  // Cast the argument at the beginning of the entry block, after
152  // any bitcasts of other arguments.
153  if (Argument *A = dyn_cast<Argument>(V)) {
154  BasicBlock::iterator IP = A->getParent()->getEntryBlock().begin();
155  while ((isa<BitCastInst>(IP) &&
156  isa<Argument>(cast<BitCastInst>(IP)->getOperand(0)) &&
157  cast<BitCastInst>(IP)->getOperand(0) != A) ||
158  isa<DbgInfoIntrinsic>(IP))
159  ++IP;
160  return ReuseOrCreateCast(A, Ty, Op, IP);
161  }
162 
163  // Cast the instruction immediately after the instruction.
164  Instruction *I = cast<Instruction>(V);
165  BasicBlock::iterator IP = findInsertPointAfter(I, Builder.GetInsertBlock());
166  return ReuseOrCreateCast(I, Ty, Op, IP);
167 }
168 
169 /// InsertBinop - Insert the specified binary operator, doing a small amount
170 /// of work to avoid inserting an obviously redundant operation.
171 Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
172  Value *LHS, Value *RHS) {
173  // Fold a binop with constant operands.
174  if (Constant *CLHS = dyn_cast<Constant>(LHS))
175  if (Constant *CRHS = dyn_cast<Constant>(RHS))
176  return ConstantExpr::get(Opcode, CLHS, CRHS);
177 
178  // Do a quick scan to see if we have this binop nearby. If so, reuse it.
179  unsigned ScanLimit = 6;
180  BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
181  // Scanning starts from the last instruction before the insertion point.
182  BasicBlock::iterator IP = Builder.GetInsertPoint();
183  if (IP != BlockBegin) {
184  --IP;
185  for (; ScanLimit; --IP, --ScanLimit) {
186  // Don't count dbg.value against the ScanLimit, to avoid perturbing the
187  // generated code.
188  if (isa<DbgInfoIntrinsic>(IP))
189  ScanLimit++;
190 
191  // Conservatively, do not use any instruction which has any of wrap/exact
192  // flags installed.
193  // TODO: Instead of simply disable poison instructions we can be clever
194  // here and match SCEV to this instruction.
195  auto canGeneratePoison = [](Instruction *I) {
196  if (isa<OverflowingBinaryOperator>(I) &&
197  (I->hasNoSignedWrap() || I->hasNoUnsignedWrap()))
198  return true;
199  if (isa<PossiblyExactOperator>(I) && I->isExact())
200  return true;
201  return false;
202  };
203  if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
204  IP->getOperand(1) == RHS && !canGeneratePoison(&*IP))
205  return &*IP;
206  if (IP == BlockBegin) break;
207  }
208  }
209 
210  // Save the original insertion point so we can restore it when we're done.
211  DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
212  SCEVInsertPointGuard Guard(Builder, this);
213 
214  // Move the insertion point out of as many loops as we can.
215  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
216  if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break;
217  BasicBlock *Preheader = L->getLoopPreheader();
218  if (!Preheader) break;
219 
220  // Ok, move up a level.
221  Builder.SetInsertPoint(Preheader->getTerminator());
222  }
223 
224  // If we haven't found this binop, insert it.
225  Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS));
226  BO->setDebugLoc(Loc);
227  rememberInstruction(BO);
228 
229  return BO;
230 }
231 
232 /// FactorOutConstant - Test if S is divisible by Factor, using signed
233 /// division. If so, update S with Factor divided out and return true.
234 /// S need not be evenly divisible if a reasonable remainder can be
235 /// computed.
236 /// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made
237 /// unnecessary; in its place, just signed-divide Ops[i] by the scale and
238 /// check to see if the divide was folded.
239 static bool FactorOutConstant(const SCEV *&S, const SCEV *&Remainder,
240  const SCEV *Factor, ScalarEvolution &SE,
241  const DataLayout &DL) {
242  // Everything is divisible by one.
243  if (Factor->isOne())
244  return true;
245 
246  // x/x == 1.
247  if (S == Factor) {
248  S = SE.getConstant(S->getType(), 1);
249  return true;
250  }
251 
252  // For a Constant, check for a multiple of the given factor.
253  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
254  // 0/x == 0.
255  if (C->isZero())
256  return true;
257  // Check for divisibility.
258  if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor)) {
259  ConstantInt *CI =
260  ConstantInt::get(SE.getContext(), C->getAPInt().sdiv(FC->getAPInt()));
261  // If the quotient is zero and the remainder is non-zero, reject
262  // the value at this scale. It will be considered for subsequent
263  // smaller scales.
264  if (!CI->isZero()) {
265  const SCEV *Div = SE.getConstant(CI);
266  S = Div;
267  Remainder = SE.getAddExpr(
268  Remainder, SE.getConstant(C->getAPInt().srem(FC->getAPInt())));
269  return true;
270  }
271  }
272  }
273 
274  // In a Mul, check if there is a constant operand which is a multiple
275  // of the given factor.
276  if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
277  // Size is known, check if there is a constant operand which is a multiple
278  // of the given factor. If so, we can factor it.
279  const SCEVConstant *FC = cast<SCEVConstant>(Factor);
280  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
281  if (!C->getAPInt().srem(FC->getAPInt())) {
282  SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
283  NewMulOps[0] = SE.getConstant(C->getAPInt().sdiv(FC->getAPInt()));
284  S = SE.getMulExpr(NewMulOps);
285  return true;
286  }
287  }
288 
289  // In an AddRec, check if both start and step are divisible.
290  if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
291  const SCEV *Step = A->getStepRecurrence(SE);
292  const SCEV *StepRem = SE.getConstant(Step->getType(), 0);
293  if (!FactorOutConstant(Step, StepRem, Factor, SE, DL))
294  return false;
295  if (!StepRem->isZero())
296  return false;
297  const SCEV *Start = A->getStart();
298  if (!FactorOutConstant(Start, Remainder, Factor, SE, DL))
299  return false;
300  S = SE.getAddRecExpr(Start, Step, A->getLoop(),
301  A->getNoWrapFlags(SCEV::FlagNW));
302  return true;
303  }
304 
305  return false;
306 }
307 
308 /// SimplifyAddOperands - Sort and simplify a list of add operands. NumAddRecs
309 /// is the number of SCEVAddRecExprs present, which are kept at the end of
310 /// the list.
311 ///
313  Type *Ty,
314  ScalarEvolution &SE) {
315  unsigned NumAddRecs = 0;
316  for (unsigned i = Ops.size(); i > 0 && isa<SCEVAddRecExpr>(Ops[i-1]); --i)
317  ++NumAddRecs;
318  // Group Ops into non-addrecs and addrecs.
319  SmallVector<const SCEV *, 8> NoAddRecs(Ops.begin(), Ops.end() - NumAddRecs);
320  SmallVector<const SCEV *, 8> AddRecs(Ops.end() - NumAddRecs, Ops.end());
321  // Let ScalarEvolution sort and simplify the non-addrecs list.
322  const SCEV *Sum = NoAddRecs.empty() ?
323  SE.getConstant(Ty, 0) :
324  SE.getAddExpr(NoAddRecs);
325  // If it returned an add, use the operands. Otherwise it simplified
326  // the sum into a single value, so just use that.
327  Ops.clear();
328  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum))
329  Ops.append(Add->op_begin(), Add->op_end());
330  else if (!Sum->isZero())
331  Ops.push_back(Sum);
332  // Then append the addrecs.
333  Ops.append(AddRecs.begin(), AddRecs.end());
334 }
335 
336 /// SplitAddRecs - Flatten a list of add operands, moving addrec start values
337 /// out to the top level. For example, convert {a + b,+,c} to a, b, {0,+,d}.
338 /// This helps expose more opportunities for folding parts of the expressions
339 /// into GEP indices.
340 ///
342  Type *Ty,
343  ScalarEvolution &SE) {
344  // Find the addrecs.
346  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
347  while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i])) {
348  const SCEV *Start = A->getStart();
349  if (Start->isZero()) break;
350  const SCEV *Zero = SE.getConstant(Ty, 0);
351  AddRecs.push_back(SE.getAddRecExpr(Zero,
352  A->getStepRecurrence(SE),
353  A->getLoop(),
354  A->getNoWrapFlags(SCEV::FlagNW)));
355  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
356  Ops[i] = Zero;
357  Ops.append(Add->op_begin(), Add->op_end());
358  e += Add->getNumOperands();
359  } else {
360  Ops[i] = Start;
361  }
362  }
363  if (!AddRecs.empty()) {
364  // Add the addrecs onto the end of the list.
365  Ops.append(AddRecs.begin(), AddRecs.end());
366  // Resort the operand list, moving any constants to the front.
367  SimplifyAddOperands(Ops, Ty, SE);
368  }
369 }
370 
371 /// expandAddToGEP - Expand an addition expression with a pointer type into
372 /// a GEP instead of using ptrtoint+arithmetic+inttoptr. This helps
373 /// BasicAliasAnalysis and other passes analyze the result. See the rules
374 /// for getelementptr vs. inttoptr in
375 /// http://llvm.org/docs/LangRef.html#pointeraliasing
376 /// for details.
377 ///
378 /// Design note: The correctness of using getelementptr here depends on
379 /// ScalarEvolution not recognizing inttoptr and ptrtoint operators, as
380 /// they may introduce pointer arithmetic which may not be safely converted
381 /// into getelementptr.
382 ///
383 /// Design note: It might seem desirable for this function to be more
384 /// loop-aware. If some of the indices are loop-invariant while others
385 /// aren't, it might seem desirable to emit multiple GEPs, keeping the
386 /// loop-invariant portions of the overall computation outside the loop.
387 /// However, there are a few reasons this is not done here. Hoisting simple
388 /// arithmetic is a low-level optimization that often isn't very
389 /// important until late in the optimization process. In fact, passes
390 /// like InstructionCombining will combine GEPs, even if it means
391 /// pushing loop-invariant computation down into loops, so even if the
392 /// GEPs were split here, the work would quickly be undone. The
393 /// LoopStrengthReduction pass, which is usually run quite late (and
394 /// after the last InstructionCombining pass), takes care of hoisting
395 /// loop-invariant portions of expressions, after considering what
396 /// can be folded using target addressing modes.
397 ///
398 Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
399  const SCEV *const *op_end,
400  PointerType *PTy,
401  Type *Ty,
402  Value *V) {
403  Type *OriginalElTy = PTy->getElementType();
404  Type *ElTy = OriginalElTy;
405  SmallVector<Value *, 4> GepIndices;
406  SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
407  bool AnyNonZeroIndices = false;
408 
409  // Split AddRecs up into parts as either of the parts may be usable
410  // without the other.
411  SplitAddRecs(Ops, Ty, SE);
412 
413  Type *IntPtrTy = DL.getIntPtrType(PTy);
414 
415  // Descend down the pointer's type and attempt to convert the other
416  // operands into GEP indices, at each level. The first index in a GEP
417  // indexes into the array implied by the pointer operand; the rest of
418  // the indices index into the element or field type selected by the
419  // preceding index.
420  for (;;) {
421  // If the scale size is not 0, attempt to factor out a scale for
422  // array indexing.
424  if (ElTy->isSized()) {
425  const SCEV *ElSize = SE.getSizeOfExpr(IntPtrTy, ElTy);
426  if (!ElSize->isZero()) {
428  for (const SCEV *Op : Ops) {
429  const SCEV *Remainder = SE.getConstant(Ty, 0);
430  if (FactorOutConstant(Op, Remainder, ElSize, SE, DL)) {
431  // Op now has ElSize factored out.
432  ScaledOps.push_back(Op);
433  if (!Remainder->isZero())
434  NewOps.push_back(Remainder);
435  AnyNonZeroIndices = true;
436  } else {
437  // The operand was not divisible, so add it to the list of operands
438  // we'll scan next iteration.
439  NewOps.push_back(Op);
440  }
441  }
442  // If we made any changes, update Ops.
443  if (!ScaledOps.empty()) {
444  Ops = NewOps;
445  SimplifyAddOperands(Ops, Ty, SE);
446  }
447  }
448  }
449 
450  // Record the scaled array index for this level of the type. If
451  // we didn't find any operands that could be factored, tentatively
452  // assume that element zero was selected (since the zero offset
453  // would obviously be folded away).
454  Value *Scaled = ScaledOps.empty() ?
456  expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
457  GepIndices.push_back(Scaled);
458 
459  // Collect struct field index operands.
460  while (StructType *STy = dyn_cast<StructType>(ElTy)) {
461  bool FoundFieldNo = false;
462  // An empty struct has no fields.
463  if (STy->getNumElements() == 0) break;
464  // Field offsets are known. See if a constant offset falls within any of
465  // the struct fields.
466  if (Ops.empty())
467  break;
468  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
469  if (SE.getTypeSizeInBits(C->getType()) <= 64) {
470  const StructLayout &SL = *DL.getStructLayout(STy);
471  uint64_t FullOffset = C->getValue()->getZExtValue();
472  if (FullOffset < SL.getSizeInBytes()) {
473  unsigned ElIdx = SL.getElementContainingOffset(FullOffset);
474  GepIndices.push_back(
476  ElTy = STy->getTypeAtIndex(ElIdx);
477  Ops[0] =
478  SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx));
479  AnyNonZeroIndices = true;
480  FoundFieldNo = true;
481  }
482  }
483  // If no struct field offsets were found, tentatively assume that
484  // field zero was selected (since the zero offset would obviously
485  // be folded away).
486  if (!FoundFieldNo) {
487  ElTy = STy->getTypeAtIndex(0u);
488  GepIndices.push_back(
490  }
491  }
492 
493  if (ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
494  ElTy = ATy->getElementType();
495  else
496  break;
497  }
498 
499  // If none of the operands were convertible to proper GEP indices, cast
500  // the base to i8* and do an ugly getelementptr with that. It's still
501  // better than ptrtoint+arithmetic+inttoptr at least.
502  if (!AnyNonZeroIndices) {
503  // Cast the base to i8*.
504  V = InsertNoopCastOfTo(V,
506 
507  assert(!isa<Instruction>(V) ||
508  SE.DT.dominates(cast<Instruction>(V), &*Builder.GetInsertPoint()));
509 
510  // Expand the operands for a plain byte offset.
511  Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
512 
513  // Fold a GEP with constant operands.
514  if (Constant *CLHS = dyn_cast<Constant>(V))
515  if (Constant *CRHS = dyn_cast<Constant>(Idx))
517  CLHS, CRHS);
518 
519  // Do a quick scan to see if we have this GEP nearby. If so, reuse it.
520  unsigned ScanLimit = 6;
521  BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
522  // Scanning starts from the last instruction before the insertion point.
523  BasicBlock::iterator IP = Builder.GetInsertPoint();
524  if (IP != BlockBegin) {
525  --IP;
526  for (; ScanLimit; --IP, --ScanLimit) {
527  // Don't count dbg.value against the ScanLimit, to avoid perturbing the
528  // generated code.
529  if (isa<DbgInfoIntrinsic>(IP))
530  ScanLimit++;
531  if (IP->getOpcode() == Instruction::GetElementPtr &&
532  IP->getOperand(0) == V && IP->getOperand(1) == Idx)
533  return &*IP;
534  if (IP == BlockBegin) break;
535  }
536  }
537 
538  // Save the original insertion point so we can restore it when we're done.
539  SCEVInsertPointGuard Guard(Builder, this);
540 
541  // Move the insertion point out of as many loops as we can.
542  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
543  if (!L->isLoopInvariant(V) || !L->isLoopInvariant(Idx)) break;
544  BasicBlock *Preheader = L->getLoopPreheader();
545  if (!Preheader) break;
546 
547  // Ok, move up a level.
548  Builder.SetInsertPoint(Preheader->getTerminator());
549  }
550 
551  // Emit a GEP.
552  Value *GEP = Builder.CreateGEP(Builder.getInt8Ty(), V, Idx, "uglygep");
553  rememberInstruction(GEP);
554 
555  return GEP;
556  }
557 
558  {
559  SCEVInsertPointGuard Guard(Builder, this);
560 
561  // Move the insertion point out of as many loops as we can.
562  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
563  if (!L->isLoopInvariant(V)) break;
564 
565  bool AnyIndexNotLoopInvariant = any_of(
566  GepIndices, [L](Value *Op) { return !L->isLoopInvariant(Op); });
567 
568  if (AnyIndexNotLoopInvariant)
569  break;
570 
571  BasicBlock *Preheader = L->getLoopPreheader();
572  if (!Preheader) break;
573 
574  // Ok, move up a level.
575  Builder.SetInsertPoint(Preheader->getTerminator());
576  }
577 
578  // Insert a pretty getelementptr. Note that this GEP is not marked inbounds,
579  // because ScalarEvolution may have changed the address arithmetic to
580  // compute a value which is beyond the end of the allocated object.
581  Value *Casted = V;
582  if (V->getType() != PTy)
583  Casted = InsertNoopCastOfTo(Casted, PTy);
584  Value *GEP = Builder.CreateGEP(OriginalElTy, Casted, GepIndices, "scevgep");
585  Ops.push_back(SE.getUnknown(GEP));
586  rememberInstruction(GEP);
587  }
588 
589  return expand(SE.getAddExpr(Ops));
590 }
591 
592 /// PickMostRelevantLoop - Given two loops pick the one that's most relevant for
593 /// SCEV expansion. If they are nested, this is the most nested. If they are
594 /// neighboring, pick the later.
595 static const Loop *PickMostRelevantLoop(const Loop *A, const Loop *B,
596  DominatorTree &DT) {
597  if (!A) return B;
598  if (!B) return A;
599  if (A->contains(B)) return B;
600  if (B->contains(A)) return A;
601  if (DT.dominates(A->getHeader(), B->getHeader())) return B;
602  if (DT.dominates(B->getHeader(), A->getHeader())) return A;
603  return A; // Arbitrarily break the tie.
604 }
605 
606 /// getRelevantLoop - Get the most relevant loop associated with the given
607 /// expression, according to PickMostRelevantLoop.
608 const Loop *SCEVExpander::getRelevantLoop(const SCEV *S) {
609  // Test whether we've already computed the most relevant loop for this SCEV.
610  auto Pair = RelevantLoops.insert(std::make_pair(S, nullptr));
611  if (!Pair.second)
612  return Pair.first->second;
613 
614  if (isa<SCEVConstant>(S))
615  // A constant has no relevant loops.
616  return nullptr;
617  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
618  if (const Instruction *I = dyn_cast<Instruction>(U->getValue()))
619  return Pair.first->second = SE.LI.getLoopFor(I->getParent());
620  // A non-instruction has no relevant loops.
621  return nullptr;
622  }
623  if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) {
624  const Loop *L = nullptr;
625  if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
626  L = AR->getLoop();
627  for (const SCEV *Op : N->operands())
628  L = PickMostRelevantLoop(L, getRelevantLoop(Op), SE.DT);
629  return RelevantLoops[N] = L;
630  }
631  if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) {
632  const Loop *Result = getRelevantLoop(C->getOperand());
633  return RelevantLoops[C] = Result;
634  }
635  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
636  const Loop *Result = PickMostRelevantLoop(
637  getRelevantLoop(D->getLHS()), getRelevantLoop(D->getRHS()), SE.DT);
638  return RelevantLoops[D] = Result;
639  }
640  llvm_unreachable("Unexpected SCEV type!");
641 }
642 
643 namespace {
644 
645 /// LoopCompare - Compare loops by PickMostRelevantLoop.
646 class LoopCompare {
647  DominatorTree &DT;
648 public:
649  explicit LoopCompare(DominatorTree &dt) : DT(dt) {}
650 
651  bool operator()(std::pair<const Loop *, const SCEV *> LHS,
652  std::pair<const Loop *, const SCEV *> RHS) const {
653  // Keep pointer operands sorted at the end.
654  if (LHS.second->getType()->isPointerTy() !=
655  RHS.second->getType()->isPointerTy())
656  return LHS.second->getType()->isPointerTy();
657 
658  // Compare loops with PickMostRelevantLoop.
659  if (LHS.first != RHS.first)
660  return PickMostRelevantLoop(LHS.first, RHS.first, DT) != LHS.first;
661 
662  // If one operand is a non-constant negative and the other is not,
663  // put the non-constant negative on the right so that a sub can
664  // be used instead of a negate and add.
665  if (LHS.second->isNonConstantNegative()) {
666  if (!RHS.second->isNonConstantNegative())
667  return false;
668  } else if (RHS.second->isNonConstantNegative())
669  return true;
670 
671  // Otherwise they are equivalent according to this comparison.
672  return false;
673  }
674 };
675 
676 }
677 
678 Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
679  Type *Ty = SE.getEffectiveSCEVType(S->getType());
680 
681  // Collect all the add operands in a loop, along with their associated loops.
682  // Iterate in reverse so that constants are emitted last, all else equal, and
683  // so that pointer operands are inserted first, which the code below relies on
684  // to form more involved GEPs.
686  for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(S->op_end()),
687  E(S->op_begin()); I != E; ++I)
688  OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
689 
690  // Sort by loop. Use a stable sort so that constants follow non-constants and
691  // pointer operands precede non-pointer operands.
692  std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(SE.DT));
693 
694  // Emit instructions to add all the operands. Hoist as much as possible
695  // out of loops, and form meaningful getelementptrs where possible.
696  Value *Sum = nullptr;
697  for (auto I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E;) {
698  const Loop *CurLoop = I->first;
699  const SCEV *Op = I->second;
700  if (!Sum) {
701  // This is the first operand. Just expand it.
702  Sum = expand(Op);
703  ++I;
704  } else if (PointerType *PTy = dyn_cast<PointerType>(Sum->getType())) {
705  // The running sum expression is a pointer. Try to form a getelementptr
706  // at this level with that as the base.
708  for (; I != E && I->first == CurLoop; ++I) {
709  // If the operand is SCEVUnknown and not instructions, peek through
710  // it, to enable more of it to be folded into the GEP.
711  const SCEV *X = I->second;
712  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(X))
713  if (!isa<Instruction>(U->getValue()))
714  X = SE.getSCEV(U->getValue());
715  NewOps.push_back(X);
716  }
717  Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum);
718  } else if (PointerType *PTy = dyn_cast<PointerType>(Op->getType())) {
719  // The running sum is an integer, and there's a pointer at this level.
720  // Try to form a getelementptr. If the running sum is instructions,
721  // use a SCEVUnknown to avoid re-analyzing them.
723  NewOps.push_back(isa<Instruction>(Sum) ? SE.getUnknown(Sum) :
724  SE.getSCEV(Sum));
725  for (++I; I != E && I->first == CurLoop; ++I)
726  NewOps.push_back(I->second);
727  Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, expand(Op));
728  } else if (Op->isNonConstantNegative()) {
729  // Instead of doing a negate and add, just do a subtract.
730  Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty);
731  Sum = InsertNoopCastOfTo(Sum, Ty);
732  Sum = InsertBinop(Instruction::Sub, Sum, W);
733  ++I;
734  } else {
735  // A simple add.
736  Value *W = expandCodeFor(Op, Ty);
737  Sum = InsertNoopCastOfTo(Sum, Ty);
738  // Canonicalize a constant to the RHS.
739  if (isa<Constant>(Sum)) std::swap(Sum, W);
740  Sum = InsertBinop(Instruction::Add, Sum, W);
741  ++I;
742  }
743  }
744 
745  return Sum;
746 }
747 
748 Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
749  Type *Ty = SE.getEffectiveSCEVType(S->getType());
750 
751  // Collect all the mul operands in a loop, along with their associated loops.
752  // Iterate in reverse so that constants are emitted last, all else equal.
754  for (std::reverse_iterator<SCEVMulExpr::op_iterator> I(S->op_end()),
755  E(S->op_begin()); I != E; ++I)
756  OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
757 
758  // Sort by loop. Use a stable sort so that constants follow non-constants.
759  std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(SE.DT));
760 
761  // Emit instructions to mul all the operands. Hoist as much as possible
762  // out of loops.
763  Value *Prod = nullptr;
764  auto I = OpsAndLoops.begin();
765 
766  // Expand the calculation of X pow N in the following manner:
767  // Let N = P1 + P2 + ... + PK, where all P are powers of 2. Then:
768  // X pow N = (X pow P1) * (X pow P2) * ... * (X pow PK).
769  const auto ExpandOpBinPowN = [this, &I, &OpsAndLoops, &Ty]() {
770  auto E = I;
771  // Calculate how many times the same operand from the same loop is included
772  // into this power.
773  uint64_t Exponent = 0;
774  const uint64_t MaxExponent = UINT64_MAX >> 1;
775  // No one sane will ever try to calculate such huge exponents, but if we
776  // need this, we stop on UINT64_MAX / 2 because we need to exit the loop
777  // below when the power of 2 exceeds our Exponent, and we want it to be
778  // 1u << 31 at most to not deal with unsigned overflow.
779  while (E != OpsAndLoops.end() && *I == *E && Exponent != MaxExponent) {
780  ++Exponent;
781  ++E;
782  }
783  assert(Exponent > 0 && "Trying to calculate a zeroth exponent of operand?");
784 
785  // Calculate powers with exponents 1, 2, 4, 8 etc. and include those of them
786  // that are needed into the result.
787  Value *P = expandCodeFor(I->second, Ty);
788  Value *Result = nullptr;
789  if (Exponent & 1)
790  Result = P;
791  for (uint64_t BinExp = 2; BinExp <= Exponent; BinExp <<= 1) {
792  P = InsertBinop(Instruction::Mul, P, P);
793  if (Exponent & BinExp)
794  Result = Result ? InsertBinop(Instruction::Mul, Result, P) : P;
795  }
796 
797  I = E;
798  assert(Result && "Nothing was expanded?");
799  return Result;
800  };
801 
802  while (I != OpsAndLoops.end()) {
803  if (!Prod) {
804  // This is the first operand. Just expand it.
805  Prod = ExpandOpBinPowN();
806  } else if (I->second->isAllOnesValue()) {
807  // Instead of doing a multiply by negative one, just do a negate.
808  Prod = InsertNoopCastOfTo(Prod, Ty);
809  Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod);
810  ++I;
811  } else {
812  // A simple mul.
813  Value *W = ExpandOpBinPowN();
814  Prod = InsertNoopCastOfTo(Prod, Ty);
815  // Canonicalize a constant to the RHS.
816  if (isa<Constant>(Prod)) std::swap(Prod, W);
817  const APInt *RHS;
818  if (match(W, m_Power2(RHS))) {
819  // Canonicalize Prod*(1<<C) to Prod<<C.
820  assert(!Ty->isVectorTy() && "vector types are not SCEVable");
821  Prod = InsertBinop(Instruction::Shl, Prod,
822  ConstantInt::get(Ty, RHS->logBase2()));
823  } else {
824  Prod = InsertBinop(Instruction::Mul, Prod, W);
825  }
826  }
827  }
828 
829  return Prod;
830 }
831 
832 Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
833  Type *Ty = SE.getEffectiveSCEVType(S->getType());
834 
835  Value *LHS = expandCodeFor(S->getLHS(), Ty);
836  if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
837  const APInt &RHS = SC->getAPInt();
838  if (RHS.isPowerOf2())
839  return InsertBinop(Instruction::LShr, LHS,
840  ConstantInt::get(Ty, RHS.logBase2()));
841  }
842 
843  Value *RHS = expandCodeFor(S->getRHS(), Ty);
844  return InsertBinop(Instruction::UDiv, LHS, RHS);
845 }
846 
847 /// Move parts of Base into Rest to leave Base with the minimal
848 /// expression that provides a pointer operand suitable for a
849 /// GEP expansion.
850 static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest,
851  ScalarEvolution &SE) {
852  while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) {
853  Base = A->getStart();
854  Rest = SE.getAddExpr(Rest,
855  SE.getAddRecExpr(SE.getConstant(A->getType(), 0),
856  A->getStepRecurrence(SE),
857  A->getLoop(),
858  A->getNoWrapFlags(SCEV::FlagNW)));
859  }
860  if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
861  Base = A->getOperand(A->getNumOperands()-1);
862  SmallVector<const SCEV *, 8> NewAddOps(A->op_begin(), A->op_end());
863  NewAddOps.back() = Rest;
864  Rest = SE.getAddExpr(NewAddOps);
865  ExposePointerBase(Base, Rest, SE);
866  }
867 }
868 
869 /// Determine if this is a well-behaved chain of instructions leading back to
870 /// the PHI. If so, it may be reused by expanded expressions.
871 bool SCEVExpander::isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV,
872  const Loop *L) {
873  if (IncV->getNumOperands() == 0 || isa<PHINode>(IncV) ||
874  (isa<CastInst>(IncV) && !isa<BitCastInst>(IncV)))
875  return false;
876  // If any of the operands don't dominate the insert position, bail.
877  // Addrec operands are always loop-invariant, so this can only happen
878  // if there are instructions which haven't been hoisted.
879  if (L == IVIncInsertLoop) {
880  for (User::op_iterator OI = IncV->op_begin()+1,
881  OE = IncV->op_end(); OI != OE; ++OI)
882  if (Instruction *OInst = dyn_cast<Instruction>(OI))
883  if (!SE.DT.dominates(OInst, IVIncInsertPos))
884  return false;
885  }
886  // Advance to the next instruction.
887  IncV = dyn_cast<Instruction>(IncV->getOperand(0));
888  if (!IncV)
889  return false;
890 
891  if (IncV->mayHaveSideEffects())
892  return false;
893 
894  if (IncV == PN)
895  return true;
896 
897  return isNormalAddRecExprPHI(PN, IncV, L);
898 }
899 
900 /// getIVIncOperand returns an induction variable increment's induction
901 /// variable operand.
902 ///
903 /// If allowScale is set, any type of GEP is allowed as long as the nonIV
904 /// operands dominate InsertPos.
905 ///
906 /// If allowScale is not set, ensure that a GEP increment conforms to one of the
907 /// simple patterns generated by getAddRecExprPHILiterally and
908 /// expandAddtoGEP. If the pattern isn't recognized, return NULL.
910  Instruction *InsertPos,
911  bool allowScale) {
912  if (IncV == InsertPos)
913  return nullptr;
914 
915  switch (IncV->getOpcode()) {
916  default:
917  return nullptr;
918  // Check for a simple Add/Sub or GEP of a loop invariant step.
919  case Instruction::Add:
920  case Instruction::Sub: {
921  Instruction *OInst = dyn_cast<Instruction>(IncV->getOperand(1));
922  if (!OInst || SE.DT.dominates(OInst, InsertPos))
923  return dyn_cast<Instruction>(IncV->getOperand(0));
924  return nullptr;
925  }
926  case Instruction::BitCast:
927  return dyn_cast<Instruction>(IncV->getOperand(0));
928  case Instruction::GetElementPtr:
929  for (auto I = IncV->op_begin() + 1, E = IncV->op_end(); I != E; ++I) {
930  if (isa<Constant>(*I))
931  continue;
932  if (Instruction *OInst = dyn_cast<Instruction>(*I)) {
933  if (!SE.DT.dominates(OInst, InsertPos))
934  return nullptr;
935  }
936  if (allowScale) {
937  // allow any kind of GEP as long as it can be hoisted.
938  continue;
939  }
940  // This must be a pointer addition of constants (pretty), which is already
941  // handled, or some number of address-size elements (ugly). Ugly geps
942  // have 2 operands. i1* is used by the expander to represent an
943  // address-size element.
944  if (IncV->getNumOperands() != 2)
945  return nullptr;
946  unsigned AS = cast<PointerType>(IncV->getType())->getAddressSpace();
947  if (IncV->getType() != Type::getInt1PtrTy(SE.getContext(), AS)
948  && IncV->getType() != Type::getInt8PtrTy(SE.getContext(), AS))
949  return nullptr;
950  break;
951  }
952  return dyn_cast<Instruction>(IncV->getOperand(0));
953  }
954 }
955 
956 /// If the insert point of the current builder or any of the builders on the
957 /// stack of saved builders has 'I' as its insert point, update it to point to
958 /// the instruction after 'I'. This is intended to be used when the instruction
959 /// 'I' is being moved. If this fixup is not done and 'I' is moved to a
960 /// different block, the inconsistent insert point (with a mismatched
961 /// Instruction and Block) can lead to an instruction being inserted in a block
962 /// other than its parent.
963 void SCEVExpander::fixupInsertPoints(Instruction *I) {
964  BasicBlock::iterator It(*I);
965  BasicBlock::iterator NewInsertPt = std::next(It);
966  if (Builder.GetInsertPoint() == It)
967  Builder.SetInsertPoint(&*NewInsertPt);
968  for (auto *InsertPtGuard : InsertPointGuards)
969  if (InsertPtGuard->GetInsertPoint() == It)
970  InsertPtGuard->SetInsertPoint(NewInsertPt);
971 }
972 
973 /// hoistStep - Attempt to hoist a simple IV increment above InsertPos to make
974 /// it available to other uses in this loop. Recursively hoist any operands,
975 /// until we reach a value that dominates InsertPos.
977  if (SE.DT.dominates(IncV, InsertPos))
978  return true;
979 
980  // InsertPos must itself dominate IncV so that IncV's new position satisfies
981  // its existing users.
982  if (isa<PHINode>(InsertPos) ||
983  !SE.DT.dominates(InsertPos->getParent(), IncV->getParent()))
984  return false;
985 
986  if (!SE.LI.movementPreservesLCSSAForm(IncV, InsertPos))
987  return false;
988 
989  // Check that the chain of IV operands leading back to Phi can be hoisted.
991  for(;;) {
992  Instruction *Oper = getIVIncOperand(IncV, InsertPos, /*allowScale*/true);
993  if (!Oper)
994  return false;
995  // IncV is safe to hoist.
996  IVIncs.push_back(IncV);
997  IncV = Oper;
998  if (SE.DT.dominates(IncV, InsertPos))
999  break;
1000  }
1001  for (auto I = IVIncs.rbegin(), E = IVIncs.rend(); I != E; ++I) {
1002  fixupInsertPoints(*I);
1003  (*I)->moveBefore(InsertPos);
1004  }
1005  return true;
1006 }
1007 
1008 /// Determine if this cyclic phi is in a form that would have been generated by
1009 /// LSR. We don't care if the phi was actually expanded in this pass, as long
1010 /// as it is in a low-cost form, for example, no implied multiplication. This
1011 /// should match any patterns generated by getAddRecExprPHILiterally and
1012 /// expandAddtoGEP.
1013 bool SCEVExpander::isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV,
1014  const Loop *L) {
1015  for(Instruction *IVOper = IncV;
1016  (IVOper = getIVIncOperand(IVOper, L->getLoopPreheader()->getTerminator(),
1017  /*allowScale=*/false));) {
1018  if (IVOper == PN)
1019  return true;
1020  }
1021  return false;
1022 }
1023 
1024 /// expandIVInc - Expand an IV increment at Builder's current InsertPos.
1025 /// Typically this is the LatchBlock terminator or IVIncInsertPos, but we may
1026 /// need to materialize IV increments elsewhere to handle difficult situations.
1027 Value *SCEVExpander::expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
1028  Type *ExpandTy, Type *IntTy,
1029  bool useSubtract) {
1030  Value *IncV;
1031  // If the PHI is a pointer, use a GEP, otherwise use an add or sub.
1032  if (ExpandTy->isPointerTy()) {
1033  PointerType *GEPPtrTy = cast<PointerType>(ExpandTy);
1034  // If the step isn't constant, don't use an implicitly scaled GEP, because
1035  // that would require a multiply inside the loop.
1036  if (!isa<ConstantInt>(StepV))
1037  GEPPtrTy = PointerType::get(Type::getInt1Ty(SE.getContext()),
1038  GEPPtrTy->getAddressSpace());
1039  const SCEV *const StepArray[1] = { SE.getSCEV(StepV) };
1040  IncV = expandAddToGEP(StepArray, StepArray+1, GEPPtrTy, IntTy, PN);
1041  if (IncV->getType() != PN->getType()) {
1042  IncV = Builder.CreateBitCast(IncV, PN->getType());
1043  rememberInstruction(IncV);
1044  }
1045  } else {
1046  IncV = useSubtract ?
1047  Builder.CreateSub(PN, StepV, Twine(IVName) + ".iv.next") :
1048  Builder.CreateAdd(PN, StepV, Twine(IVName) + ".iv.next");
1049  rememberInstruction(IncV);
1050  }
1051  return IncV;
1052 }
1053 
1054 /// \brief Hoist the addrec instruction chain rooted in the loop phi above the
1055 /// position. This routine assumes that this is possible (has been checked).
1056 void SCEVExpander::hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
1057  Instruction *Pos, PHINode *LoopPhi) {
1058  do {
1059  if (DT->dominates(InstToHoist, Pos))
1060  break;
1061  // Make sure the increment is where we want it. But don't move it
1062  // down past a potential existing post-inc user.
1063  fixupInsertPoints(InstToHoist);
1064  InstToHoist->moveBefore(Pos);
1065  Pos = InstToHoist;
1066  InstToHoist = cast<Instruction>(InstToHoist->getOperand(0));
1067  } while (InstToHoist != LoopPhi);
1068 }
1069 
1070 /// \brief Check whether we can cheaply express the requested SCEV in terms of
1071 /// the available PHI SCEV by truncation and/or inversion of the step.
1073  const SCEVAddRecExpr *Phi,
1074  const SCEVAddRecExpr *Requested,
1075  bool &InvertStep) {
1076  Type *PhiTy = SE.getEffectiveSCEVType(Phi->getType());
1077  Type *RequestedTy = SE.getEffectiveSCEVType(Requested->getType());
1078 
1079  if (RequestedTy->getIntegerBitWidth() > PhiTy->getIntegerBitWidth())
1080  return false;
1081 
1082  // Try truncate it if necessary.
1083  Phi = dyn_cast<SCEVAddRecExpr>(SE.getTruncateOrNoop(Phi, RequestedTy));
1084  if (!Phi)
1085  return false;
1086 
1087  // Check whether truncation will help.
1088  if (Phi == Requested) {
1089  InvertStep = false;
1090  return true;
1091  }
1092 
1093  // Check whether inverting will help: {R,+,-1} == R - {0,+,1}.
1094  if (SE.getAddExpr(Requested->getStart(),
1095  SE.getNegativeSCEV(Requested)) == Phi) {
1096  InvertStep = true;
1097  return true;
1098  }
1099 
1100  return false;
1101 }
1102 
1103 static bool IsIncrementNSW(ScalarEvolution &SE, const SCEVAddRecExpr *AR) {
1104  if (!isa<IntegerType>(AR->getType()))
1105  return false;
1106 
1107  unsigned BitWidth = cast<IntegerType>(AR->getType())->getBitWidth();
1108  Type *WideTy = IntegerType::get(AR->getType()->getContext(), BitWidth * 2);
1109  const SCEV *Step = AR->getStepRecurrence(SE);
1110  const SCEV *OpAfterExtend = SE.getAddExpr(SE.getSignExtendExpr(Step, WideTy),
1111  SE.getSignExtendExpr(AR, WideTy));
1112  const SCEV *ExtendAfterOp =
1113  SE.getSignExtendExpr(SE.getAddExpr(AR, Step), WideTy);
1114  return ExtendAfterOp == OpAfterExtend;
1115 }
1116 
1117 static bool IsIncrementNUW(ScalarEvolution &SE, const SCEVAddRecExpr *AR) {
1118  if (!isa<IntegerType>(AR->getType()))
1119  return false;
1120 
1121  unsigned BitWidth = cast<IntegerType>(AR->getType())->getBitWidth();
1122  Type *WideTy = IntegerType::get(AR->getType()->getContext(), BitWidth * 2);
1123  const SCEV *Step = AR->getStepRecurrence(SE);
1124  const SCEV *OpAfterExtend = SE.getAddExpr(SE.getZeroExtendExpr(Step, WideTy),
1125  SE.getZeroExtendExpr(AR, WideTy));
1126  const SCEV *ExtendAfterOp =
1127  SE.getZeroExtendExpr(SE.getAddExpr(AR, Step), WideTy);
1128  return ExtendAfterOp == OpAfterExtend;
1129 }
1130 
1131 /// getAddRecExprPHILiterally - Helper for expandAddRecExprLiterally. Expand
1132 /// the base addrec, which is the addrec without any non-loop-dominating
1133 /// values, and return the PHI.
1134 PHINode *
1135 SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
1136  const Loop *L,
1137  Type *ExpandTy,
1138  Type *IntTy,
1139  Type *&TruncTy,
1140  bool &InvertStep) {
1141  assert((!IVIncInsertLoop||IVIncInsertPos) && "Uninitialized insert position");
1142 
1143  // Reuse a previously-inserted PHI, if present.
1144  BasicBlock *LatchBlock = L->getLoopLatch();
1145  if (LatchBlock) {
1146  PHINode *AddRecPhiMatch = nullptr;
1147  Instruction *IncV = nullptr;
1148  TruncTy = nullptr;
1149  InvertStep = false;
1150 
1151  // Only try partially matching scevs that need truncation and/or
1152  // step-inversion if we know this loop is outside the current loop.
1153  bool TryNonMatchingSCEV =
1154  IVIncInsertLoop &&
1155  SE.DT.properlyDominates(LatchBlock, IVIncInsertLoop->getHeader());
1156 
1157  for (PHINode &PN : L->getHeader()->phis()) {
1158  if (!SE.isSCEVable(PN.getType()))
1159  continue;
1160 
1161  const SCEVAddRecExpr *PhiSCEV = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(&PN));
1162  if (!PhiSCEV)
1163  continue;
1164 
1165  bool IsMatchingSCEV = PhiSCEV == Normalized;
1166  // We only handle truncation and inversion of phi recurrences for the
1167  // expanded expression if the expanded expression's loop dominates the
1168  // loop we insert to. Check now, so we can bail out early.
1169  if (!IsMatchingSCEV && !TryNonMatchingSCEV)
1170  continue;
1171 
1172  Instruction *TempIncV =
1173  cast<Instruction>(PN.getIncomingValueForBlock(LatchBlock));
1174 
1175  // Check whether we can reuse this PHI node.
1176  if (LSRMode) {
1177  if (!isExpandedAddRecExprPHI(&PN, TempIncV, L))
1178  continue;
1179  if (L == IVIncInsertLoop && !hoistIVInc(TempIncV, IVIncInsertPos))
1180  continue;
1181  } else {
1182  if (!isNormalAddRecExprPHI(&PN, TempIncV, L))
1183  continue;
1184  }
1185 
1186  // Stop if we have found an exact match SCEV.
1187  if (IsMatchingSCEV) {
1188  IncV = TempIncV;
1189  TruncTy = nullptr;
1190  InvertStep = false;
1191  AddRecPhiMatch = &PN;
1192  break;
1193  }
1194 
1195  // Try whether the phi can be translated into the requested form
1196  // (truncated and/or offset by a constant).
1197  if ((!TruncTy || InvertStep) &&
1198  canBeCheaplyTransformed(SE, PhiSCEV, Normalized, InvertStep)) {
1199  // Record the phi node. But don't stop we might find an exact match
1200  // later.
1201  AddRecPhiMatch = &PN;
1202  IncV = TempIncV;
1203  TruncTy = SE.getEffectiveSCEVType(Normalized->getType());
1204  }
1205  }
1206 
1207  if (AddRecPhiMatch) {
1208  // Potentially, move the increment. We have made sure in
1209  // isExpandedAddRecExprPHI or hoistIVInc that this is possible.
1210  if (L == IVIncInsertLoop)
1211  hoistBeforePos(&SE.DT, IncV, IVIncInsertPos, AddRecPhiMatch);
1212 
1213  // Ok, the add recurrence looks usable.
1214  // Remember this PHI, even in post-inc mode.
1215  InsertedValues.insert(AddRecPhiMatch);
1216  // Remember the increment.
1217  rememberInstruction(IncV);
1218  return AddRecPhiMatch;
1219  }
1220  }
1221 
1222  // Save the original insertion point so we can restore it when we're done.
1223  SCEVInsertPointGuard Guard(Builder, this);
1224 
1225  // Another AddRec may need to be recursively expanded below. For example, if
1226  // this AddRec is quadratic, the StepV may itself be an AddRec in this
1227  // loop. Remove this loop from the PostIncLoops set before expanding such
1228  // AddRecs. Otherwise, we cannot find a valid position for the step
1229  // (i.e. StepV can never dominate its loop header). Ideally, we could do
1230  // SavedIncLoops.swap(PostIncLoops), but we generally have a single element,
1231  // so it's not worth implementing SmallPtrSet::swap.
1232  PostIncLoopSet SavedPostIncLoops = PostIncLoops;
1233  PostIncLoops.clear();
1234 
1235  // Expand code for the start value into the loop preheader.
1236  assert(L->getLoopPreheader() &&
1237  "Can't expand add recurrences without a loop preheader!");
1238  Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy,
1240 
1241  // StartV must have been be inserted into L's preheader to dominate the new
1242  // phi.
1243  assert(!isa<Instruction>(StartV) ||
1244  SE.DT.properlyDominates(cast<Instruction>(StartV)->getParent(),
1245  L->getHeader()));
1246 
1247  // Expand code for the step value. Do this before creating the PHI so that PHI
1248  // reuse code doesn't see an incomplete PHI.
1249  const SCEV *Step = Normalized->getStepRecurrence(SE);
1250  // If the stride is negative, insert a sub instead of an add for the increment
1251  // (unless it's a constant, because subtracts of constants are canonicalized
1252  // to adds).
1253  bool useSubtract = !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
1254  if (useSubtract)
1255  Step = SE.getNegativeSCEV(Step);
1256  // Expand the step somewhere that dominates the loop header.
1257  Value *StepV = expandCodeFor(Step, IntTy, &L->getHeader()->front());
1258 
1259  // The no-wrap behavior proved by IsIncrement(NUW|NSW) is only applicable if
1260  // we actually do emit an addition. It does not apply if we emit a
1261  // subtraction.
1262  bool IncrementIsNUW = !useSubtract && IsIncrementNUW(SE, Normalized);
1263  bool IncrementIsNSW = !useSubtract && IsIncrementNSW(SE, Normalized);
1264 
1265  // Create the PHI.
1266  BasicBlock *Header = L->getHeader();
1267  Builder.SetInsertPoint(Header, Header->begin());
1268  pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
1269  PHINode *PN = Builder.CreatePHI(ExpandTy, std::distance(HPB, HPE),
1270  Twine(IVName) + ".iv");
1271  rememberInstruction(PN);
1272 
1273  // Create the step instructions and populate the PHI.
1274  for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
1275  BasicBlock *Pred = *HPI;
1276 
1277  // Add a start value.
1278  if (!L->contains(Pred)) {
1279  PN->addIncoming(StartV, Pred);
1280  continue;
1281  }
1282 
1283  // Create a step value and add it to the PHI.
1284  // If IVIncInsertLoop is non-null and equal to the addrec's loop, insert the
1285  // instructions at IVIncInsertPos.
1286  Instruction *InsertPos = L == IVIncInsertLoop ?
1287  IVIncInsertPos : Pred->getTerminator();
1288  Builder.SetInsertPoint(InsertPos);
1289  Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
1290 
1291  if (isa<OverflowingBinaryOperator>(IncV)) {
1292  if (IncrementIsNUW)
1293  cast<BinaryOperator>(IncV)->setHasNoUnsignedWrap();
1294  if (IncrementIsNSW)
1295  cast<BinaryOperator>(IncV)->setHasNoSignedWrap();
1296  }
1297  PN->addIncoming(IncV, Pred);
1298  }
1299 
1300  // After expanding subexpressions, restore the PostIncLoops set so the caller
1301  // can ensure that IVIncrement dominates the current uses.
1302  PostIncLoops = SavedPostIncLoops;
1303 
1304  // Remember this PHI, even in post-inc mode.
1305  InsertedValues.insert(PN);
1306 
1307  return PN;
1308 }
1309 
1310 Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
1311  Type *STy = S->getType();
1312  Type *IntTy = SE.getEffectiveSCEVType(STy);
1313  const Loop *L = S->getLoop();
1314 
1315  // Determine a normalized form of this expression, which is the expression
1316  // before any post-inc adjustment is made.
1317  const SCEVAddRecExpr *Normalized = S;
1318  if (PostIncLoops.count(L)) {
1320  Loops.insert(L);
1321  Normalized = cast<SCEVAddRecExpr>(normalizeForPostIncUse(S, Loops, SE));
1322  }
1323 
1324  // Strip off any non-loop-dominating component from the addrec start.
1325  const SCEV *Start = Normalized->getStart();
1326  const SCEV *PostLoopOffset = nullptr;
1327  if (!SE.properlyDominates(Start, L->getHeader())) {
1328  PostLoopOffset = Start;
1329  Start = SE.getConstant(Normalized->getType(), 0);
1330  Normalized = cast<SCEVAddRecExpr>(
1331  SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE),
1332  Normalized->getLoop(),
1333  Normalized->getNoWrapFlags(SCEV::FlagNW)));
1334  }
1335 
1336  // Strip off any non-loop-dominating component from the addrec step.
1337  const SCEV *Step = Normalized->getStepRecurrence(SE);
1338  const SCEV *PostLoopScale = nullptr;
1339  if (!SE.dominates(Step, L->getHeader())) {
1340  PostLoopScale = Step;
1341  Step = SE.getConstant(Normalized->getType(), 1);
1342  if (!Start->isZero()) {
1343  // The normalization below assumes that Start is constant zero, so if
1344  // it isn't re-associate Start to PostLoopOffset.
1345  assert(!PostLoopOffset && "Start not-null but PostLoopOffset set?");
1346  PostLoopOffset = Start;
1347  Start = SE.getConstant(Normalized->getType(), 0);
1348  }
1349  Normalized =
1350  cast<SCEVAddRecExpr>(SE.getAddRecExpr(
1351  Start, Step, Normalized->getLoop(),
1352  Normalized->getNoWrapFlags(SCEV::FlagNW)));
1353  }
1354 
1355  // Expand the core addrec. If we need post-loop scaling, force it to
1356  // expand to an integer type to avoid the need for additional casting.
1357  Type *ExpandTy = PostLoopScale ? IntTy : STy;
1358  // We can't use a pointer type for the addrec if the pointer type is
1359  // non-integral.
1360  Type *AddRecPHIExpandTy =
1361  DL.isNonIntegralPointerType(STy) ? Normalized->getType() : ExpandTy;
1362 
1363  // In some cases, we decide to reuse an existing phi node but need to truncate
1364  // it and/or invert the step.
1365  Type *TruncTy = nullptr;
1366  bool InvertStep = false;
1367  PHINode *PN = getAddRecExprPHILiterally(Normalized, L, AddRecPHIExpandTy,
1368  IntTy, TruncTy, InvertStep);
1369 
1370  // Accommodate post-inc mode, if necessary.
1371  Value *Result;
1372  if (!PostIncLoops.count(L))
1373  Result = PN;
1374  else {
1375  // In PostInc mode, use the post-incremented value.
1376  BasicBlock *LatchBlock = L->getLoopLatch();
1377  assert(LatchBlock && "PostInc mode requires a unique loop latch!");
1378  Result = PN->getIncomingValueForBlock(LatchBlock);
1379 
1380  // For an expansion to use the postinc form, the client must call
1381  // expandCodeFor with an InsertPoint that is either outside the PostIncLoop
1382  // or dominated by IVIncInsertPos.
1383  if (isa<Instruction>(Result) &&
1384  !SE.DT.dominates(cast<Instruction>(Result),
1385  &*Builder.GetInsertPoint())) {
1386  // The induction variable's postinc expansion does not dominate this use.
1387  // IVUsers tries to prevent this case, so it is rare. However, it can
1388  // happen when an IVUser outside the loop is not dominated by the latch
1389  // block. Adjusting IVIncInsertPos before expansion begins cannot handle
1390  // all cases. Consider a phi outide whose operand is replaced during
1391  // expansion with the value of the postinc user. Without fundamentally
1392  // changing the way postinc users are tracked, the only remedy is
1393  // inserting an extra IV increment. StepV might fold into PostLoopOffset,
1394  // but hopefully expandCodeFor handles that.
1395  bool useSubtract =
1396  !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
1397  if (useSubtract)
1398  Step = SE.getNegativeSCEV(Step);
1399  Value *StepV;
1400  {
1401  // Expand the step somewhere that dominates the loop header.
1402  SCEVInsertPointGuard Guard(Builder, this);
1403  StepV = expandCodeFor(Step, IntTy, &L->getHeader()->front());
1404  }
1405  Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
1406  }
1407  }
1408 
1409  // We have decided to reuse an induction variable of a dominating loop. Apply
1410  // truncation and/or invertion of the step.
1411  if (TruncTy) {
1412  Type *ResTy = Result->getType();
1413  // Normalize the result type.
1414  if (ResTy != SE.getEffectiveSCEVType(ResTy))
1415  Result = InsertNoopCastOfTo(Result, SE.getEffectiveSCEVType(ResTy));
1416  // Truncate the result.
1417  if (TruncTy != Result->getType()) {
1418  Result = Builder.CreateTrunc(Result, TruncTy);
1419  rememberInstruction(Result);
1420  }
1421  // Invert the result.
1422  if (InvertStep) {
1423  Result = Builder.CreateSub(expandCodeFor(Normalized->getStart(), TruncTy),
1424  Result);
1425  rememberInstruction(Result);
1426  }
1427  }
1428 
1429  // Re-apply any non-loop-dominating scale.
1430  if (PostLoopScale) {
1431  assert(S->isAffine() && "Can't linearly scale non-affine recurrences.");
1432  Result = InsertNoopCastOfTo(Result, IntTy);
1433  Result = Builder.CreateMul(Result,
1434  expandCodeFor(PostLoopScale, IntTy));
1435  rememberInstruction(Result);
1436  }
1437 
1438  // Re-apply any non-loop-dominating offset.
1439  if (PostLoopOffset) {
1440  if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
1441  if (Result->getType()->isIntegerTy()) {
1442  Value *Base = expandCodeFor(PostLoopOffset, ExpandTy);
1443  const SCEV *const OffsetArray[1] = {SE.getUnknown(Result)};
1444  Result = expandAddToGEP(OffsetArray, OffsetArray + 1, PTy, IntTy, Base);
1445  } else {
1446  const SCEV *const OffsetArray[1] = {PostLoopOffset};
1447  Result =
1448  expandAddToGEP(OffsetArray, OffsetArray + 1, PTy, IntTy, Result);
1449  }
1450  } else {
1451  Result = InsertNoopCastOfTo(Result, IntTy);
1452  Result = Builder.CreateAdd(Result,
1453  expandCodeFor(PostLoopOffset, IntTy));
1454  rememberInstruction(Result);
1455  }
1456  }
1457 
1458  return Result;
1459 }
1460 
1461 Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
1462  if (!CanonicalMode) return expandAddRecExprLiterally(S);
1463 
1464  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1465  const Loop *L = S->getLoop();
1466 
1467  // First check for an existing canonical IV in a suitable type.
1468  PHINode *CanonicalIV = nullptr;
1469  if (PHINode *PN = L->getCanonicalInductionVariable())
1470  if (SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
1471  CanonicalIV = PN;
1472 
1473  // Rewrite an AddRec in terms of the canonical induction variable, if
1474  // its type is more narrow.
1475  if (CanonicalIV &&
1476  SE.getTypeSizeInBits(CanonicalIV->getType()) >
1477  SE.getTypeSizeInBits(Ty)) {
1479  for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i)
1480  NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
1481  Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(),
1483  BasicBlock::iterator NewInsertPt =
1484  findInsertPointAfter(cast<Instruction>(V), Builder.GetInsertBlock());
1485  V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), nullptr,
1486  &*NewInsertPt);
1487  return V;
1488  }
1489 
1490  // {X,+,F} --> X + {0,+,F}
1491  if (!S->getStart()->isZero()) {
1492  SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end());
1493  NewOps[0] = SE.getConstant(Ty, 0);
1494  const SCEV *Rest = SE.getAddRecExpr(NewOps, L,
1496 
1497  // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
1498  // comments on expandAddToGEP for details.
1499  const SCEV *Base = S->getStart();
1500  const SCEV *RestArray[1] = { Rest };
1501  // Dig into the expression to find the pointer base for a GEP.
1502  ExposePointerBase(Base, RestArray[0], SE);
1503  // If we found a pointer, expand the AddRec with a GEP.
1504  if (PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
1505  // Make sure the Base isn't something exotic, such as a multiplied
1506  // or divided pointer value. In those cases, the result type isn't
1507  // actually a pointer type.
1508  if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
1509  Value *StartV = expand(Base);
1510  assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
1511  return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV);
1512  }
1513  }
1514 
1515  // Just do a normal add. Pre-expand the operands to suppress folding.
1516  //
1517  // The LHS and RHS values are factored out of the expand call to make the
1518  // output independent of the argument evaluation order.
1519  const SCEV *AddExprLHS = SE.getUnknown(expand(S->getStart()));
1520  const SCEV *AddExprRHS = SE.getUnknown(expand(Rest));
1521  return expand(SE.getAddExpr(AddExprLHS, AddExprRHS));
1522  }
1523 
1524  // If we don't yet have a canonical IV, create one.
1525  if (!CanonicalIV) {
1526  // Create and insert the PHI node for the induction variable in the
1527  // specified loop.
1528  BasicBlock *Header = L->getHeader();
1529  pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
1530  CanonicalIV = PHINode::Create(Ty, std::distance(HPB, HPE), "indvar",
1531  &Header->front());
1532  rememberInstruction(CanonicalIV);
1533 
1534  SmallSet<BasicBlock *, 4> PredSeen;
1535  Constant *One = ConstantInt::get(Ty, 1);
1536  for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
1537  BasicBlock *HP = *HPI;
1538  if (!PredSeen.insert(HP).second) {
1539  // There must be an incoming value for each predecessor, even the
1540  // duplicates!
1541  CanonicalIV->addIncoming(CanonicalIV->getIncomingValueForBlock(HP), HP);
1542  continue;
1543  }
1544 
1545  if (L->contains(HP)) {
1546  // Insert a unit add instruction right before the terminator
1547  // corresponding to the back-edge.
1548  Instruction *Add = BinaryOperator::CreateAdd(CanonicalIV, One,
1549  "indvar.next",
1550  HP->getTerminator());
1551  Add->setDebugLoc(HP->getTerminator()->getDebugLoc());
1552  rememberInstruction(Add);
1553  CanonicalIV->addIncoming(Add, HP);
1554  } else {
1555  CanonicalIV->addIncoming(Constant::getNullValue(Ty), HP);
1556  }
1557  }
1558  }
1559 
1560  // {0,+,1} --> Insert a canonical induction variable into the loop!
1561  if (S->isAffine() && S->getOperand(1)->isOne()) {
1562  assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
1563  "IVs with types different from the canonical IV should "
1564  "already have been handled!");
1565  return CanonicalIV;
1566  }
1567 
1568  // {0,+,F} --> {0,+,1} * F
1569 
1570  // If this is a simple linear addrec, emit it now as a special case.
1571  if (S->isAffine()) // {0,+,F} --> i*F
1572  return
1573  expand(SE.getTruncateOrNoop(
1574  SE.getMulExpr(SE.getUnknown(CanonicalIV),
1575  SE.getNoopOrAnyExtend(S->getOperand(1),
1576  CanonicalIV->getType())),
1577  Ty));
1578 
1579  // If this is a chain of recurrences, turn it into a closed form, using the
1580  // folders, then expandCodeFor the closed form. This allows the folders to
1581  // simplify the expression without having to build a bunch of special code
1582  // into this folder.
1583  const SCEV *IH = SE.getUnknown(CanonicalIV); // Get I as a "symbolic" SCEV.
1584 
1585  // Promote S up to the canonical IV type, if the cast is foldable.
1586  const SCEV *NewS = S;
1587  const SCEV *Ext = SE.getNoopOrAnyExtend(S, CanonicalIV->getType());
1588  if (isa<SCEVAddRecExpr>(Ext))
1589  NewS = Ext;
1590 
1591  const SCEV *V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE);
1592  //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
1593 
1594  // Truncate the result down to the original type, if needed.
1595  const SCEV *T = SE.getTruncateOrNoop(V, Ty);
1596  return expand(T);
1597 }
1598 
1599 Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
1600  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1601  Value *V = expandCodeFor(S->getOperand(),
1602  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1603  Value *I = Builder.CreateTrunc(V, Ty);
1604  rememberInstruction(I);
1605  return I;
1606 }
1607 
1608 Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
1609  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1610  Value *V = expandCodeFor(S->getOperand(),
1611  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1612  Value *I = Builder.CreateZExt(V, Ty);
1613  rememberInstruction(I);
1614  return I;
1615 }
1616 
1617 Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
1618  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1619  Value *V = expandCodeFor(S->getOperand(),
1620  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1621  Value *I = Builder.CreateSExt(V, Ty);
1622  rememberInstruction(I);
1623  return I;
1624 }
1625 
1626 Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
1627  Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
1628  Type *Ty = LHS->getType();
1629  for (int i = S->getNumOperands()-2; i >= 0; --i) {
1630  // In the case of mixed integer and pointer types, do the
1631  // rest of the comparisons as integer.
1632  if (S->getOperand(i)->getType() != Ty) {
1633  Ty = SE.getEffectiveSCEVType(Ty);
1634  LHS = InsertNoopCastOfTo(LHS, Ty);
1635  }
1636  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1637  Value *ICmp = Builder.CreateICmpSGT(LHS, RHS);
1638  rememberInstruction(ICmp);
1639  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
1640  rememberInstruction(Sel);
1641  LHS = Sel;
1642  }
1643  // In the case of mixed integer and pointer types, cast the
1644  // final result back to the pointer type.
1645  if (LHS->getType() != S->getType())
1646  LHS = InsertNoopCastOfTo(LHS, S->getType());
1647  return LHS;
1648 }
1649 
1650 Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
1651  Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
1652  Type *Ty = LHS->getType();
1653  for (int i = S->getNumOperands()-2; i >= 0; --i) {
1654  // In the case of mixed integer and pointer types, do the
1655  // rest of the comparisons as integer.
1656  if (S->getOperand(i)->getType() != Ty) {
1657  Ty = SE.getEffectiveSCEVType(Ty);
1658  LHS = InsertNoopCastOfTo(LHS, Ty);
1659  }
1660  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1661  Value *ICmp = Builder.CreateICmpUGT(LHS, RHS);
1662  rememberInstruction(ICmp);
1663  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
1664  rememberInstruction(Sel);
1665  LHS = Sel;
1666  }
1667  // In the case of mixed integer and pointer types, cast the
1668  // final result back to the pointer type.
1669  if (LHS->getType() != S->getType())
1670  LHS = InsertNoopCastOfTo(LHS, S->getType());
1671  return LHS;
1672 }
1673 
1675  Instruction *IP) {
1676  setInsertPoint(IP);
1677  return expandCodeFor(SH, Ty);
1678 }
1679 
1681  // Expand the code for this SCEV.
1682  Value *V = expand(SH);
1683  if (Ty) {
1684  assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) &&
1685  "non-trivial casts should be done with the SCEVs directly!");
1686  V = InsertNoopCastOfTo(V, Ty);
1687  }
1688  return V;
1689 }
1690 
1691 ScalarEvolution::ValueOffsetPair
1692 SCEVExpander::FindValueInExprValueMap(const SCEV *S,
1693  const Instruction *InsertPt) {
1694  SetVector<ScalarEvolution::ValueOffsetPair> *Set = SE.getSCEVValues(S);
1695  // If the expansion is not in CanonicalMode, and the SCEV contains any
1696  // sub scAddRecExpr type SCEV, it is required to expand the SCEV literally.
1697  if (CanonicalMode || !SE.containsAddRecurrence(S)) {
1698  // If S is scConstant, it may be worse to reuse an existing Value.
1699  if (S->getSCEVType() != scConstant && Set) {
1700  // Choose a Value from the set which dominates the insertPt.
1701  // insertPt should be inside the Value's parent loop so as not to break
1702  // the LCSSA form.
1703  for (auto const &VOPair : *Set) {
1704  Value *V = VOPair.first;
1705  ConstantInt *Offset = VOPair.second;
1706  Instruction *EntInst = nullptr;
1707  if (V && isa<Instruction>(V) && (EntInst = cast<Instruction>(V)) &&
1708  S->getType() == V->getType() &&
1709  EntInst->getFunction() == InsertPt->getFunction() &&
1710  SE.DT.dominates(EntInst, InsertPt) &&
1711  (SE.LI.getLoopFor(EntInst->getParent()) == nullptr ||
1712  SE.LI.getLoopFor(EntInst->getParent())->contains(InsertPt)))
1713  return {V, Offset};
1714  }
1715  }
1716  }
1717  return {nullptr, nullptr};
1718 }
1719 
1720 // The expansion of SCEV will either reuse a previous Value in ExprValueMap,
1721 // or expand the SCEV literally. Specifically, if the expansion is in LSRMode,
1722 // and the SCEV contains any sub scAddRecExpr type SCEV, it will be expanded
1723 // literally, to prevent LSR's transformed SCEV from being reverted. Otherwise,
1724 // the expansion will try to reuse Value from ExprValueMap, and only when it
1725 // fails, expand the SCEV literally.
1726 Value *SCEVExpander::expand(const SCEV *S) {
1727  // Compute an insertion point for this SCEV object. Hoist the instructions
1728  // as far out in the loop nest as possible.
1729  Instruction *InsertPt = &*Builder.GetInsertPoint();
1730  for (Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock());;
1731  L = L->getParentLoop())
1732  if (SE.isLoopInvariant(S, L)) {
1733  if (!L) break;
1734  if (BasicBlock *Preheader = L->getLoopPreheader())
1735  InsertPt = Preheader->getTerminator();
1736  else {
1737  // LSR sets the insertion point for AddRec start/step values to the
1738  // block start to simplify value reuse, even though it's an invalid
1739  // position. SCEVExpander must correct for this in all cases.
1740  InsertPt = &*L->getHeader()->getFirstInsertionPt();
1741  }
1742  } else {
1743  // We can move insertion point only if there is no div or rem operations
1744  // otherwise we are risky to move it over the check for zero denominator.
1745  auto SafeToHoist = [](const SCEV *S) {
1746  return !SCEVExprContains(S, [](const SCEV *S) {
1747  if (const auto *D = dyn_cast<SCEVUDivExpr>(S)) {
1748  if (const auto *SC = dyn_cast<SCEVConstant>(D->getRHS()))
1749  // Division by non-zero constants can be hoisted.
1750  return SC->getValue()->isZero();
1751  // All other divisions should not be moved as they may be
1752  // divisions by zero and should be kept within the
1753  // conditions of the surrounding loops that guard their
1754  // execution (see PR35406).
1755  return true;
1756  }
1757  return false;
1758  });
1759  };
1760  // If the SCEV is computable at this level, insert it into the header
1761  // after the PHIs (and after any other instructions that we've inserted
1762  // there) so that it is guaranteed to dominate any user inside the loop.
1763  if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L) &&
1764  SafeToHoist(S))
1765  InsertPt = &*L->getHeader()->getFirstInsertionPt();
1766  while (InsertPt->getIterator() != Builder.GetInsertPoint() &&
1767  (isInsertedInstruction(InsertPt) ||
1768  isa<DbgInfoIntrinsic>(InsertPt))) {
1769  InsertPt = &*std::next(InsertPt->getIterator());
1770  }
1771  break;
1772  }
1773 
1774  // Check to see if we already expanded this here.
1775  auto I = InsertedExpressions.find(std::make_pair(S, InsertPt));
1776  if (I != InsertedExpressions.end())
1777  return I->second;
1778 
1779  SCEVInsertPointGuard Guard(Builder, this);
1780  Builder.SetInsertPoint(InsertPt);
1781 
1782  // Expand the expression into instructions.
1783  ScalarEvolution::ValueOffsetPair VO = FindValueInExprValueMap(S, InsertPt);
1784  Value *V = VO.first;
1785 
1786  if (!V)
1787  V = visit(S);
1788  else if (VO.second) {
1789  if (PointerType *Vty = dyn_cast<PointerType>(V->getType())) {
1790  Type *Ety = Vty->getPointerElementType();
1791  int64_t Offset = VO.second->getSExtValue();
1792  int64_t ESize = SE.getTypeSizeInBits(Ety);
1793  if ((Offset * 8) % ESize == 0) {
1794  ConstantInt *Idx =
1795  ConstantInt::getSigned(VO.second->getType(), -(Offset * 8) / ESize);
1796  V = Builder.CreateGEP(Ety, V, Idx, "scevgep");
1797  } else {
1798  ConstantInt *Idx =
1799  ConstantInt::getSigned(VO.second->getType(), -Offset);
1800  unsigned AS = Vty->getAddressSpace();
1801  V = Builder.CreateBitCast(V, Type::getInt8PtrTy(SE.getContext(), AS));
1802  V = Builder.CreateGEP(Type::getInt8Ty(SE.getContext()), V, Idx,
1803  "uglygep");
1804  V = Builder.CreateBitCast(V, Vty);
1805  }
1806  } else {
1807  V = Builder.CreateSub(V, VO.second);
1808  }
1809  }
1810  // Remember the expanded value for this SCEV at this location.
1811  //
1812  // This is independent of PostIncLoops. The mapped value simply materializes
1813  // the expression at this insertion point. If the mapped value happened to be
1814  // a postinc expansion, it could be reused by a non-postinc user, but only if
1815  // its insertion point was already at the head of the loop.
1816  InsertedExpressions[std::make_pair(S, InsertPt)] = V;
1817  return V;
1818 }
1819 
1820 void SCEVExpander::rememberInstruction(Value *I) {
1821  if (!PostIncLoops.empty())
1822  InsertedPostIncValues.insert(I);
1823  else
1824  InsertedValues.insert(I);
1825 }
1826 
1827 /// getOrInsertCanonicalInductionVariable - This method returns the
1828 /// canonical induction variable of the specified type for the specified
1829 /// loop (inserting one if there is none). A canonical induction variable
1830 /// starts at zero and steps by one on each iteration.
1831 PHINode *
1833  Type *Ty) {
1834  assert(Ty->isIntegerTy() && "Can only insert integer induction variables!");
1835 
1836  // Build a SCEV for {0,+,1}<L>.
1837  // Conservatively use FlagAnyWrap for now.
1838  const SCEV *H = SE.getAddRecExpr(SE.getConstant(Ty, 0),
1839  SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
1840 
1841  // Emit code for it.
1842  SCEVInsertPointGuard Guard(Builder, this);
1843  PHINode *V =
1844  cast<PHINode>(expandCodeFor(H, nullptr, &L->getHeader()->front()));
1845 
1846  return V;
1847 }
1848 
1849 /// replaceCongruentIVs - Check for congruent phis in this loop header and
1850 /// replace them with their most canonical representative. Return the number of
1851 /// phis eliminated.
1852 ///
1853 /// This does not depend on any SCEVExpander state but should be used in
1854 /// the same context that SCEVExpander is used.
1855 unsigned
1858  const TargetTransformInfo *TTI) {
1859  // Find integer phis in order of increasing width.
1861  for (PHINode &PN : L->getHeader()->phis())
1862  Phis.push_back(&PN);
1863 
1864  if (TTI)
1865  std::sort(Phis.begin(), Phis.end(), [](Value *LHS, Value *RHS) {
1866  // Put pointers at the back and make sure pointer < pointer = false.
1867  if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
1868  return RHS->getType()->isIntegerTy() && !LHS->getType()->isIntegerTy();
1869  return RHS->getType()->getPrimitiveSizeInBits() <
1870  LHS->getType()->getPrimitiveSizeInBits();
1871  });
1872 
1873  unsigned NumElim = 0;
1875  // Process phis from wide to narrow. Map wide phis to their truncation
1876  // so narrow phis can reuse them.
1877  for (PHINode *Phi : Phis) {
1878  auto SimplifyPHINode = [&](PHINode *PN) -> Value * {
1879  if (Value *V = SimplifyInstruction(PN, {DL, &SE.TLI, &SE.DT, &SE.AC}))
1880  return V;
1881  if (!SE.isSCEVable(PN->getType()))
1882  return nullptr;
1883  auto *Const = dyn_cast<SCEVConstant>(SE.getSCEV(PN));
1884  if (!Const)
1885  return nullptr;
1886  return Const->getValue();
1887  };
1888 
1889  // Fold constant phis. They may be congruent to other constant phis and
1890  // would confuse the logic below that expects proper IVs.
1891  if (Value *V = SimplifyPHINode(Phi)) {
1892  if (V->getType() != Phi->getType())
1893  continue;
1894  Phi->replaceAllUsesWith(V);
1895  DeadInsts.emplace_back(Phi);
1896  ++NumElim;
1898  << "INDVARS: Eliminated constant iv: " << *Phi << '\n');
1899  continue;
1900  }
1901 
1902  if (!SE.isSCEVable(Phi->getType()))
1903  continue;
1904 
1905  PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
1906  if (!OrigPhiRef) {
1907  OrigPhiRef = Phi;
1908  if (Phi->getType()->isIntegerTy() && TTI &&
1909  TTI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
1910  // This phi can be freely truncated to the narrowest phi type. Map the
1911  // truncated expression to it so it will be reused for narrow types.
1912  const SCEV *TruncExpr =
1913  SE.getTruncateExpr(SE.getSCEV(Phi), Phis.back()->getType());
1914  ExprToIVMap[TruncExpr] = Phi;
1915  }
1916  continue;
1917  }
1918 
1919  // Replacing a pointer phi with an integer phi or vice-versa doesn't make
1920  // sense.
1921  if (OrigPhiRef->getType()->isPointerTy() != Phi->getType()->isPointerTy())
1922  continue;
1923 
1924  if (BasicBlock *LatchBlock = L->getLoopLatch()) {
1925  Instruction *OrigInc = dyn_cast<Instruction>(
1926  OrigPhiRef->getIncomingValueForBlock(LatchBlock));
1927  Instruction *IsomorphicInc =
1928  dyn_cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
1929 
1930  if (OrigInc && IsomorphicInc) {
1931  // If this phi has the same width but is more canonical, replace the
1932  // original with it. As part of the "more canonical" determination,
1933  // respect a prior decision to use an IV chain.
1934  if (OrigPhiRef->getType() == Phi->getType() &&
1935  !(ChainedPhis.count(Phi) ||
1936  isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)) &&
1937  (ChainedPhis.count(Phi) ||
1938  isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
1939  std::swap(OrigPhiRef, Phi);
1940  std::swap(OrigInc, IsomorphicInc);
1941  }
1942  // Replacing the congruent phi is sufficient because acyclic
1943  // redundancy elimination, CSE/GVN, should handle the
1944  // rest. However, once SCEV proves that a phi is congruent,
1945  // it's often the head of an IV user cycle that is isomorphic
1946  // with the original phi. It's worth eagerly cleaning up the
1947  // common case of a single IV increment so that DeleteDeadPHIs
1948  // can remove cycles that had postinc uses.
1949  const SCEV *TruncExpr =
1950  SE.getTruncateOrNoop(SE.getSCEV(OrigInc), IsomorphicInc->getType());
1951  if (OrigInc != IsomorphicInc &&
1952  TruncExpr == SE.getSCEV(IsomorphicInc) &&
1953  SE.LI.replacementPreservesLCSSAForm(IsomorphicInc, OrigInc) &&
1954  hoistIVInc(OrigInc, IsomorphicInc)) {
1956  dbgs() << "INDVARS: Eliminated congruent iv.inc: "
1957  << *IsomorphicInc << '\n');
1958  Value *NewInc = OrigInc;
1959  if (OrigInc->getType() != IsomorphicInc->getType()) {
1960  Instruction *IP = nullptr;
1961  if (PHINode *PN = dyn_cast<PHINode>(OrigInc))
1962  IP = &*PN->getParent()->getFirstInsertionPt();
1963  else
1964  IP = OrigInc->getNextNode();
1965 
1966  IRBuilder<> Builder(IP);
1967  Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
1968  NewInc = Builder.CreateTruncOrBitCast(
1969  OrigInc, IsomorphicInc->getType(), IVName);
1970  }
1971  IsomorphicInc->replaceAllUsesWith(NewInc);
1972  DeadInsts.emplace_back(IsomorphicInc);
1973  }
1974  }
1975  }
1976  DEBUG_WITH_TYPE(DebugType, dbgs() << "INDVARS: Eliminated congruent iv: "
1977  << *Phi << '\n');
1978  ++NumElim;
1979  Value *NewIV = OrigPhiRef;
1980  if (OrigPhiRef->getType() != Phi->getType()) {
1981  IRBuilder<> Builder(&*L->getHeader()->getFirstInsertionPt());
1982  Builder.SetCurrentDebugLocation(Phi->getDebugLoc());
1983  NewIV = Builder.CreateTruncOrBitCast(OrigPhiRef, Phi->getType(), IVName);
1984  }
1985  Phi->replaceAllUsesWith(NewIV);
1986  DeadInsts.emplace_back(Phi);
1987  }
1988  return NumElim;
1989 }
1990 
1992  const Instruction *At, Loop *L) {
1994  getRelatedExistingExpansion(S, At, L);
1995  if (VO && VO.getValue().second == nullptr)
1996  return VO.getValue().first;
1997  return nullptr;
1998 }
1999 
2002  Loop *L) {
2003  using namespace llvm::PatternMatch;
2004 
2005  SmallVector<BasicBlock *, 4> ExitingBlocks;
2006  L->getExitingBlocks(ExitingBlocks);
2007 
2008  // Look for suitable value in simple conditions at the loop exits.
2009  for (BasicBlock *BB : ExitingBlocks) {
2010  ICmpInst::Predicate Pred;
2011  Instruction *LHS, *RHS;
2012  BasicBlock *TrueBB, *FalseBB;
2013 
2014  if (!match(BB->getTerminator(),
2015  m_Br(m_ICmp(Pred, m_Instruction(LHS), m_Instruction(RHS)),
2016  TrueBB, FalseBB)))
2017  continue;
2018 
2019  if (SE.getSCEV(LHS) == S && SE.DT.dominates(LHS, At))
2020  return ScalarEvolution::ValueOffsetPair(LHS, nullptr);
2021 
2022  if (SE.getSCEV(RHS) == S && SE.DT.dominates(RHS, At))
2023  return ScalarEvolution::ValueOffsetPair(RHS, nullptr);
2024  }
2025 
2026  // Use expand's logic which is used for reusing a previous Value in
2027  // ExprValueMap.
2028  ScalarEvolution::ValueOffsetPair VO = FindValueInExprValueMap(S, At);
2029  if (VO.first)
2030  return VO;
2031 
2032  // There is potential to make this significantly smarter, but this simple
2033  // heuristic already gets some interesting cases.
2034 
2035  // Can not find suitable value.
2036  return None;
2037 }
2038 
2039 bool SCEVExpander::isHighCostExpansionHelper(
2040  const SCEV *S, Loop *L, const Instruction *At,
2041  SmallPtrSetImpl<const SCEV *> &Processed) {
2042 
2043  // If we can find an existing value for this scev available at the point "At"
2044  // then consider the expression cheap.
2045  if (At && getRelatedExistingExpansion(S, At, L))
2046  return false;
2047 
2048  // Zero/One operand expressions
2049  switch (S->getSCEVType()) {
2050  case scUnknown:
2051  case scConstant:
2052  return false;
2053  case scTruncate:
2054  return isHighCostExpansionHelper(cast<SCEVTruncateExpr>(S)->getOperand(),
2055  L, At, Processed);
2056  case scZeroExtend:
2057  return isHighCostExpansionHelper(cast<SCEVZeroExtendExpr>(S)->getOperand(),
2058  L, At, Processed);
2059  case scSignExtend:
2060  return isHighCostExpansionHelper(cast<SCEVSignExtendExpr>(S)->getOperand(),
2061  L, At, Processed);
2062  }
2063 
2064  if (!Processed.insert(S).second)
2065  return false;
2066 
2067  if (auto *UDivExpr = dyn_cast<SCEVUDivExpr>(S)) {
2068  // If the divisor is a power of two and the SCEV type fits in a native
2069  // integer, consider the division cheap irrespective of whether it occurs in
2070  // the user code since it can be lowered into a right shift.
2071  if (auto *SC = dyn_cast<SCEVConstant>(UDivExpr->getRHS()))
2072  if (SC->getAPInt().isPowerOf2()) {
2073  const DataLayout &DL =
2075  unsigned Width = cast<IntegerType>(UDivExpr->getType())->getBitWidth();
2076  return DL.isIllegalInteger(Width);
2077  }
2078 
2079  // UDivExpr is very likely a UDiv that ScalarEvolution's HowFarToZero or
2080  // HowManyLessThans produced to compute a precise expression, rather than a
2081  // UDiv from the user's code. If we can't find a UDiv in the code with some
2082  // simple searching, assume the former consider UDivExpr expensive to
2083  // compute.
2084  BasicBlock *ExitingBB = L->getExitingBlock();
2085  if (!ExitingBB)
2086  return true;
2087 
2088  // At the beginning of this function we already tried to find existing value
2089  // for plain 'S'. Now try to lookup 'S + 1' since it is common pattern
2090  // involving division. This is just a simple search heuristic.
2091  if (!At)
2092  At = &ExitingBB->back();
2093  if (!getRelatedExistingExpansion(
2094  SE.getAddExpr(S, SE.getConstant(S->getType(), 1)), At, L))
2095  return true;
2096  }
2097 
2098  // HowManyLessThans uses a Max expression whenever the loop is not guarded by
2099  // the exit condition.
2100  if (isa<SCEVSMaxExpr>(S) || isa<SCEVUMaxExpr>(S))
2101  return true;
2102 
2103  // Recurse past nary expressions, which commonly occur in the
2104  // BackedgeTakenCount. They may already exist in program code, and if not,
2105  // they are not too expensive rematerialize.
2106  if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(S)) {
2107  for (auto *Op : NAry->operands())
2108  if (isHighCostExpansionHelper(Op, L, At, Processed))
2109  return true;
2110  }
2111 
2112  // If we haven't recognized an expensive SCEV pattern, assume it's an
2113  // expression produced by program code.
2114  return false;
2115 }
2116 
2118  Instruction *IP) {
2119  assert(IP);
2120  switch (Pred->getKind()) {
2122  return expandUnionPredicate(cast<SCEVUnionPredicate>(Pred), IP);
2124  return expandEqualPredicate(cast<SCEVEqualPredicate>(Pred), IP);
2125  case SCEVPredicate::P_Wrap: {
2126  auto *AddRecPred = cast<SCEVWrapPredicate>(Pred);
2127  return expandWrapPredicate(AddRecPred, IP);
2128  }
2129  }
2130  llvm_unreachable("Unknown SCEV predicate type");
2131 }
2132 
2134  Instruction *IP) {
2135  Value *Expr0 = expandCodeFor(Pred->getLHS(), Pred->getLHS()->getType(), IP);
2136  Value *Expr1 = expandCodeFor(Pred->getRHS(), Pred->getRHS()->getType(), IP);
2137 
2138  Builder.SetInsertPoint(IP);
2139  auto *I = Builder.CreateICmpNE(Expr0, Expr1, "ident.check");
2140  return I;
2141 }
2142 
2144  Instruction *Loc, bool Signed) {
2145  assert(AR->isAffine() && "Cannot generate RT check for "
2146  "non-affine expression");
2147 
2148  SCEVUnionPredicate Pred;
2149  const SCEV *ExitCount =
2150  SE.getPredicatedBackedgeTakenCount(AR->getLoop(), Pred);
2151 
2152  assert(ExitCount != SE.getCouldNotCompute() && "Invalid loop count");
2153 
2154  const SCEV *Step = AR->getStepRecurrence(SE);
2155  const SCEV *Start = AR->getStart();
2156 
2157  unsigned SrcBits = SE.getTypeSizeInBits(ExitCount->getType());
2158  unsigned DstBits = SE.getTypeSizeInBits(AR->getType());
2159 
2160  // The expression {Start,+,Step} has nusw/nssw if
2161  // Step < 0, Start - |Step| * Backedge <= Start
2162  // Step >= 0, Start + |Step| * Backedge > Start
2163  // and |Step| * Backedge doesn't unsigned overflow.
2164 
2165  IntegerType *CountTy = IntegerType::get(Loc->getContext(), SrcBits);
2166  Builder.SetInsertPoint(Loc);
2167  Value *TripCountVal = expandCodeFor(ExitCount, CountTy, Loc);
2168 
2169  IntegerType *Ty =
2170  IntegerType::get(Loc->getContext(), SE.getTypeSizeInBits(AR->getType()));
2171 
2172  Value *StepValue = expandCodeFor(Step, Ty, Loc);
2173  Value *NegStepValue = expandCodeFor(SE.getNegativeSCEV(Step), Ty, Loc);
2174  Value *StartValue = expandCodeFor(Start, Ty, Loc);
2175 
2176  ConstantInt *Zero =
2178 
2179  Builder.SetInsertPoint(Loc);
2180  // Compute |Step|
2181  Value *StepCompare = Builder.CreateICmp(ICmpInst::ICMP_SLT, StepValue, Zero);
2182  Value *AbsStep = Builder.CreateSelect(StepCompare, NegStepValue, StepValue);
2183 
2184  // Get the backedge taken count and truncate or extended to the AR type.
2185  Value *TruncTripCount = Builder.CreateZExtOrTrunc(TripCountVal, Ty);
2186  auto *MulF = Intrinsic::getDeclaration(Loc->getModule(),
2187  Intrinsic::umul_with_overflow, Ty);
2188 
2189  // Compute |Step| * Backedge
2190  CallInst *Mul = Builder.CreateCall(MulF, {AbsStep, TruncTripCount}, "mul");
2191  Value *MulV = Builder.CreateExtractValue(Mul, 0, "mul.result");
2192  Value *OfMul = Builder.CreateExtractValue(Mul, 1, "mul.overflow");
2193 
2194  // Compute:
2195  // Start + |Step| * Backedge < Start
2196  // Start - |Step| * Backedge > Start
2197  Value *Add = Builder.CreateAdd(StartValue, MulV);
2198  Value *Sub = Builder.CreateSub(StartValue, MulV);
2199 
2200  Value *EndCompareGT = Builder.CreateICmp(
2201  Signed ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT, Sub, StartValue);
2202 
2203  Value *EndCompareLT = Builder.CreateICmp(
2204  Signed ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT, Add, StartValue);
2205 
2206  // Select the answer based on the sign of Step.
2207  Value *EndCheck =
2208  Builder.CreateSelect(StepCompare, EndCompareGT, EndCompareLT);
2209 
2210  // If the backedge taken count type is larger than the AR type,
2211  // check that we don't drop any bits by truncating it. If we are
2212  // droping bits, then we have overflow (unless the step is zero).
2213  if (SE.getTypeSizeInBits(CountTy) > SE.getTypeSizeInBits(Ty)) {
2214  auto MaxVal = APInt::getMaxValue(DstBits).zext(SrcBits);
2215  auto *BackedgeCheck =
2216  Builder.CreateICmp(ICmpInst::ICMP_UGT, TripCountVal,
2217  ConstantInt::get(Loc->getContext(), MaxVal));
2218  BackedgeCheck = Builder.CreateAnd(
2219  BackedgeCheck, Builder.CreateICmp(ICmpInst::ICMP_NE, StepValue, Zero));
2220 
2221  EndCheck = Builder.CreateOr(EndCheck, BackedgeCheck);
2222  }
2223 
2224  EndCheck = Builder.CreateOr(EndCheck, OfMul);
2225  return EndCheck;
2226 }
2227 
2229  Instruction *IP) {
2230  const auto *A = cast<SCEVAddRecExpr>(Pred->getExpr());
2231  Value *NSSWCheck = nullptr, *NUSWCheck = nullptr;
2232 
2233  // Add a check for NUSW
2235  NUSWCheck = generateOverflowCheck(A, IP, false);
2236 
2237  // Add a check for NSSW
2239  NSSWCheck = generateOverflowCheck(A, IP, true);
2240 
2241  if (NUSWCheck && NSSWCheck)
2242  return Builder.CreateOr(NUSWCheck, NSSWCheck);
2243 
2244  if (NUSWCheck)
2245  return NUSWCheck;
2246 
2247  if (NSSWCheck)
2248  return NSSWCheck;
2249 
2250  return ConstantInt::getFalse(IP->getContext());
2251 }
2252 
2254  Instruction *IP) {
2255  auto *BoolType = IntegerType::get(IP->getContext(), 1);
2256  Value *Check = ConstantInt::getNullValue(BoolType);
2257 
2258  // Loop over all checks in this set.
2259  for (auto Pred : Union->getPredicates()) {
2260  auto *NextCheck = expandCodeForPredicate(Pred, IP);
2261  Builder.SetInsertPoint(IP);
2262  Check = Builder.CreateOr(Check, NextCheck);
2263  }
2264 
2265  return Check;
2266 }
2267 
2268 namespace {
2269 // Search for a SCEV subexpression that is not safe to expand. Any expression
2270 // that may expand to a !isSafeToSpeculativelyExecute value is unsafe, namely
2271 // UDiv expressions. We don't know if the UDiv is derived from an IR divide
2272 // instruction, but the important thing is that we prove the denominator is
2273 // nonzero before expansion.
2274 //
2275 // IVUsers already checks that IV-derived expressions are safe. So this check is
2276 // only needed when the expression includes some subexpression that is not IV
2277 // derived.
2278 //
2279 // Currently, we only allow division by a nonzero constant here. If this is
2280 // inadequate, we could easily allow division by SCEVUnknown by using
2281 // ValueTracking to check isKnownNonZero().
2282 //
2283 // We cannot generally expand recurrences unless the step dominates the loop
2284 // header. The expander handles the special case of affine recurrences by
2285 // scaling the recurrence outside the loop, but this technique isn't generally
2286 // applicable. Expanding a nested recurrence outside a loop requires computing
2287 // binomial coefficients. This could be done, but the recurrence has to be in a
2288 // perfectly reduced form, which can't be guaranteed.
2289 struct SCEVFindUnsafe {
2290  ScalarEvolution &SE;
2291  bool IsUnsafe;
2292 
2293  SCEVFindUnsafe(ScalarEvolution &se): SE(se), IsUnsafe(false) {}
2294 
2295  bool follow(const SCEV *S) {
2296  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
2297  const SCEVConstant *SC = dyn_cast<SCEVConstant>(D->getRHS());
2298  if (!SC || SC->getValue()->isZero()) {
2299  IsUnsafe = true;
2300  return false;
2301  }
2302  }
2303  if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
2304  const SCEV *Step = AR->getStepRecurrence(SE);
2305  if (!AR->isAffine() && !SE.dominates(Step, AR->getLoop()->getHeader())) {
2306  IsUnsafe = true;
2307  return false;
2308  }
2309  }
2310  return true;
2311  }
2312  bool isDone() const { return IsUnsafe; }
2313 };
2314 }
2315 
2316 namespace llvm {
2317 bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE) {
2318  SCEVFindUnsafe Search(SE);
2319  visitAll(S, Search);
2320  return !Search.IsUnsafe;
2321 }
2322 
2323 bool isSafeToExpandAt(const SCEV *S, const Instruction *InsertionPoint,
2324  ScalarEvolution &SE) {
2325  return isSafeToExpand(S, SE) && SE.dominates(S, InsertionPoint->getParent());
2326 }
2327 }
static unsigned getBitWidth(Type *Ty, const DataLayout &DL)
Returns the bitwidth of the given scalar or pointer type.
const SCEV * getTruncateOrNoop(const SCEV *V, Type *Ty)
Return a SCEV corresponding to a conversion of the input value to the specified type.
static bool Check(DecodeStatus &Out, DecodeStatus In)
const NoneType None
Definition: None.h:24
uint64_t CallInst * C
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
bool hoistIVInc(Instruction *IncV, Instruction *InsertPos)
Utility for hoisting an IV increment.
static ConstantInt * getFalse(LLVMContext &Context)
Definition: Constants.cpp:548
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
static IntegerType * getInt1Ty(LLVMContext &C)
Definition: Type.cpp:173
void addIncoming(Value *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
BlockT * getLoopLatch() const
If there is a single latch block for this loop, return it.
Definition: LoopInfoImpl.h:157
Value * getExactExistingExpansion(const SCEV *S, const Instruction *At, Loop *L)
Try to find existing LLVM IR value for S available at the point At.
This class represents an incoming formal argument to a Function.
Definition: Argument.h:30
NodeTy * getNextNode()
Get the next node, or nullptr for the list tail.
Definition: ilist_node.h:289
const SCEV * getConstant(ConstantInt *V)
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
Type * getEffectiveSCEVType(Type *Ty) const
Return a type with the same bitwidth as the given type and which represents how SCEV will treat the g...
static Constant * getGetElementPtr(Type *Ty, Constant *C, ArrayRef< Constant *> IdxList, bool InBounds=false, Optional< unsigned > InRangeIndex=None, Type *OnlyIfReducedTy=nullptr)
Getelementptr form.
Definition: Constants.h:1120
bool isSized(SmallPtrSetImpl< Type *> *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:262
LLVM_ATTRIBUTE_ALWAYS_INLINE size_type size() const
Definition: SmallVector.h:136
bool isSafeToExpandAt(const SCEV *S, const Instruction *InsertionPoint, ScalarEvolution &SE)
Return true if the given expression is safe to expand in the sense that all materialized values are d...
const SCEV * normalizeForPostIncUse(const SCEV *S, const PostIncLoopSet &Loops, ScalarEvolution &SE)
Normalize S to be post-increment for all loops present in Loops.
The main scalar evolution driver.
APInt zext(unsigned width) const
Zero extend to a new width.
Definition: APInt.cpp:866
bool isZero() const
Return true if the expression is a constant zero.
This class represents a function call, abstracting a target machine&#39;s calling convention.
BlockT * getLoopPreheader() const
If there is a preheader for this loop, return it.
Definition: LoopInfoImpl.h:106
static PointerType * get(Type *ElementType, unsigned AddressSpace)
This constructs a pointer to an object of the specified type in a numbered address space...
Definition: Type.cpp:617
unsigned less than
Definition: InstrTypes.h:878
Optional< ScalarEvolution::ValueOffsetPair > getRelatedExistingExpansion(const SCEV *S, const Instruction *At, Loop *L)
Try to find the ValueOffsetPair for S.
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:738
This class represents a truncation of an integer value to a smaller integer value.
Value * expandWrapPredicate(const SCEVWrapPredicate *P, Instruction *Loc)
A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a S...
A debug info location.
Definition: DebugLoc.h:34
const SCEV * getOperand() const
Hexagon Common GEP
static void SimplifyAddOperands(SmallVectorImpl< const SCEV *> &Ops, Type *Ty, ScalarEvolution &SE)
SimplifyAddOperands - Sort and simplify a list of add operands.
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:227
op_iterator op_begin()
Definition: User.h:214
unsigned getElementContainingOffset(uint64_t Offset) const
Given a valid byte offset into the structure, returns the structure index that contains it...
Definition: DataLayout.cpp:84
This is the base class for unary cast operator classes.
return AArch64::GPR64RegClass contains(Reg)
LLVMContext & getContext() const
Return the LLVMContext in which this type was uniqued.
Definition: Type.h:130
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:232
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:344
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:252
#define DEBUG_WITH_TYPE(TYPE, X)
DEBUG_WITH_TYPE macro - This macro should be used by passes to emit debug information.
Definition: Debug.h:64
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
Used to lazily calculate structure layout information for a target machine, based on the DataLayout s...
Definition: DataLayout.h:511
Hexagon Hardware Loops
Value * expandCodeForPredicate(const SCEVPredicate *Pred, Instruction *Loc)
Generates a code sequence that evaluates this predicate.
Type * getPointerElementType() const
Definition: Type.h:373
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:361
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
static const Loop * PickMostRelevantLoop(const Loop *A, const Loop *B, DominatorTree &DT)
PickMostRelevantLoop - Given two loops pick the one that&#39;s most relevant for SCEV expansion...
This is the base class for all instructions that perform data casts.
Definition: InstrTypes.h:560
Class to represent struct types.
Definition: DerivedTypes.h:201
A Use represents the edge between a Value definition and its users.
Definition: Use.h:56
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:42
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:197
LLVMContext & getContext() const
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:707
This node represents multiplication of some number of SCEVs.
Value * generateOverflowCheck(const SCEVAddRecExpr *AR, Instruction *Loc, bool Signed)
Generates code that evaluates if the AR expression will overflow.
const APInt & getAPInt() const
BlockT * getHeader() const
Definition: LoopInfo.h:100
ConstantInt * getValue() const
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:1747
A constant value that is initialized with an expression using other constant values.
Definition: Constants.h:867
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
bool isTruncateFree(Type *Ty1, Type *Ty2) const
Return true if it&#39;s free to truncate a value of type Ty1 to type Ty2.
This node represents a polynomial recurrence on the trip count of the specified loop.
const T & getValue() const LLVM_LVALUE_FUNCTION
Definition: Optional.h:179
Class to represent array types.
Definition: DerivedTypes.h:369
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:126
op_iterator op_begin() const
void SetCurrentDebugLocation(DebugLoc L)
Set location information used by debugging information.
Definition: IRBuilder.h:152
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:439
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power-of-2.
Definition: PatternMatch.h:375
const SCEV * getStepRecurrence(ScalarEvolution &SE) const
Constructs and returns the recurrence indicating how much this expression steps by.
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:301
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:142
Function * getDeclaration(Module *M, ID id, ArrayRef< Type *> Tys=None)
Create or insert an LLVM Function declaration for an intrinsic, and return it.
Definition: Function.cpp:980
const SCEV * getAddRecExpr(const SCEV *Start, const SCEV *Step, const Loop *L, SCEV::NoWrapFlags Flags)
Get an add recurrence expression for the specified loop.
static BinaryOperator * CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
Value * getOperand(unsigned i) const
Definition: User.h:154
Class to represent pointers.
Definition: DerivedTypes.h:467
#define P(N)
This means that we are dealing with an entirely unknown SCEV value, and only represent it as its LLVM...
const SCEV * getOperand(unsigned i) const
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
const_iterator getFirstInsertionPt() const
Returns an iterator to the first instruction in this block that is suitable for inserting a non-PHI i...
Definition: BasicBlock.cpp:200
void setDebugLoc(DebugLoc Loc)
Set the debug location information for this instruction.
Definition: Instruction.h:282
SCEVPredicateKind getKind() const
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
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:46
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This is an important base class in LLVM.
Definition: Constant.h:42
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator begin()
Definition: SmallVector.h:116
Value * getIncomingValueForBlock(const BasicBlock *BB) const
SmallSet - This maintains a set of unique values, optimizing for the case when the set is small (less...
Definition: SmallSet.h:36
bool isPointerTy() const
True if this is an instance of PointerType.
Definition: Type.h:221
const Instruction & front() const
Definition: BasicBlock.h:264
#define H(x, y, z)
Definition: MD5.cpp:57
const SCEV * getExpr() const override
Implementation of the SCEVPredicate interface.
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:371
bool mayHaveSideEffects() const
Return true if the instruction may have side effects.
Definition: Instruction.h:536
const SCEV * getAddExpr(SmallVectorImpl< const SCEV *> &Ops, SCEV::NoWrapFlags Flags=SCEV::FlagAnyWrap, unsigned Depth=0)
Get a canonical add expression, or something simpler if possible.
const SCEV * getLHS() const
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:113
brc_match< Cond_t > m_Br(const Cond_t &C, BasicBlock *&T, BasicBlock *&F)
op_iterator op_end()
Definition: User.h:216
bool any_of(R &&Range, UnaryPredicate P)
Provide wrappers to std::any_of which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:821
const Instruction & back() const
Definition: BasicBlock.h:266
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:853
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.
bool SCEVExprContains(const SCEV *Root, PredTy Pred)
Return true if any node in Root satisfies the predicate Pred.
Interval::pred_iterator pred_end(Interval *I)
Definition: Interval.h:116
bool isAffine() const
Return true if this represents an expression A + B*x where A and B are loop invariant values...
unsigned getAddressSpace() const
Return the address space of the Pointer type.
Definition: DerivedTypes.h:495
self_iterator getIterator()
Definition: ilist_node.h:82
Class to represent integer types.
Definition: DerivedTypes.h:40
std::pair< NoneType, bool > insert(const T &V)
insert - Insert an element into the set if it isn&#39;t already there.
Definition: SmallSet.h:81
static Expected< BitVector > expand(StringRef S, StringRef Original)
Definition: GlobPattern.cpp:28
const Function * getFunction() const
Return the function this instruction belongs to.
Definition: Instruction.cpp:59
const SCEV * getLHS() const
Returns the left hand side of the equality.
void getExitingBlocks(SmallVectorImpl< BlockT *> &ExitingBlocks) const
Return all blocks inside the loop that have successors outside of the loop.
Definition: LoopInfoImpl.h:35
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1356
const AMDGPUAS & AS
const SCEV * getRHS() const
Returns the right hand side of the equality.
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:220
const SCEV * getMulExpr(SmallVectorImpl< const SCEV *> &Ops, SCEV::NoWrapFlags Flags=SCEV::FlagAnyWrap, unsigned Depth=0)
Get a canonical multiply expression, or something simpler if possible.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
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...
signed greater than
Definition: InstrTypes.h:880
This class represents an assumption made using SCEV expressions which can be checked at run-time...
static bool IsIncrementNSW(ScalarEvolution &SE, const SCEVAddRecExpr *AR)
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...
static IntegerType * get(LLVMContext &C, unsigned NumBits)
This static method is the primary way of constructing an IntegerType.
Definition: Type.cpp:240
bool contains(const LoopT *L) const
Return true if the specified loop is contained within in this loop.
Definition: LoopInfo.h:110
unsigned getSCEVType() const
bool isNonConstantNegative() const
Return true if the specified scev is negated, but not a constant.
unsigned getNumOperands() const
Definition: User.h:176
static PointerType * getInt1PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:216
This is the shared class of boolean and integer constants.
Definition: Constants.h:84
Type * getType() const
Return the LLVM type of this SCEV expression.
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
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 &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:862
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:243
Module.h This file contains the declarations for the Module class.
signed less than
Definition: InstrTypes.h:882
uint64_t getSizeInBytes() const
Definition: DataLayout.h:519
CHAIN = SC CHAIN, Imm128 - System call.
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
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:585
static ConstantInt * getSigned(IntegerType *Ty, int64_t V)
Return a ConstantInt with the specified value for the specified type.
Definition: Constants.cpp:599
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...
unsigned logBase2() const
Definition: APInt.h:1727
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:923
PHINode * getCanonicalInductionVariable() const
Check to see if the loop has a canonical induction variable: an integer recurrence that starts at 0 a...
Definition: LoopInfo.cpp:111
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:55
Class for arbitrary precision integers.
Definition: APInt.h:69
This node represents an addition of some number of SCEVs.
static BasicBlock::iterator findInsertPointAfter(Instruction *I, BasicBlock *MustDominate)
bool isPowerOf2() const
Check if this APInt&#39;s value is a power of two greater than zero.
Definition: APInt.h:457
This class represents a signed maximum selection.
iterator_range< user_iterator > users()
Definition: Value.h:405
InstListType::iterator iterator
Instruction iterators...
Definition: BasicBlock.h:91
Value * expandUnionPredicate(const SCEVUnionPredicate *Pred, Instruction *Loc)
A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a S...
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1471
void visitAll(const SCEV *Root, SV &Visitor)
Use SCEVTraversal to visit all nodes in the given expression tree.
static APInt getMaxValue(unsigned numBits)
Gets maximum unsigned value of APInt for specific bit width.
Definition: APInt.h:523
void append(in_iter in_start, in_iter in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:396
This class represents a zero extension of a small integer value to a larger integer value...
Value * CreateTruncOrBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1511
static bool IsIncrementNUW(ScalarEvolution &SE, const SCEVAddRecExpr *AR)
LoopT * getParentLoop() const
Definition: LoopInfo.h:101
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&#39;s ...
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator end()
Definition: SmallVector.h:120
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:285
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:533
void emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:654
This class represents an analyzed expression in the program.
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:176
unsigned getIntegerBitWidth() const
Definition: DerivedTypes.h:97
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:61
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:439
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:224
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:108
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:58
#define N
bool isZero() const
This is just a convenience method to make client code smaller for a common code.
Definition: Constants.h:193
This class represents a sign extension of a small integer value to a larger integer value...
This class represents an unsigned maximum selection.
LLVM_NODISCARD 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:323
Instruction * getIVIncOperand(Instruction *IncV, Instruction *InsertPos, bool allowScale)
Return the induction variable increment&#39;s IV operand.
iterator_range< const_phi_iterator > phis() const
Returns a range that iterates over the phis in the basic block.
Definition: BasicBlock.h:308
const SCEV * getRHS() const
unsigned replaceCongruentIVs(Loop *L, const DominatorTree *DT, SmallVectorImpl< WeakTrackingVH > &DeadInsts, const TargetTransformInfo *TTI=nullptr)
replace congruent phis with their most canonical representative.
const SmallVectorImpl< const SCEVPredicate * > & getPredicates() const
DebugType
Definition: COFF.h:640
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This class represents a composition of other SCEV predicates, and is the class that most clients will...
bool isOne() const
Return true if the expression is a constant one.
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:115
const SCEV * getNegativeSCEV(const SCEV *V, SCEV::NoWrapFlags Flags=SCEV::FlagAnyWrap)
Return the SCEV object corresponding to -V.
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:565
Value * expandEqualPredicate(const SCEVEqualPredicate *Pred, Instruction *Loc)
A specialized variant of expandCodeForPredicate, handling the case when we are expanding code for a S...
LLVM Value Representation.
Definition: Value.h:73
A vector that has set insertion semantics.
Definition: SetVector.h:41
void moveBefore(Instruction *MovePos)
Unlink this instruction from its current basic block and insert it into the basic block that MovePos ...
Definition: Instruction.cpp:86
static Value * SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q)
See if we can fold the given phi. If not, returns null.
bool dominates(const SCEV *S, const BasicBlock *BB)
Return true if elements that makes up the given SCEV dominate the specified basic block...
unsigned greater than
Definition: InstrTypes.h:876
void sort(Policy policy, RandomAccessIterator Start, RandomAccessIterator End, const Comparator &Comp=Comparator())
Definition: Parallel.h:199
This pass exposes codegen information to IR-level passes.
bool isIllegalInteger(uint64_t Width) const
Definition: DataLayout.h:248
static APInt getNullValue(unsigned numBits)
Get the &#39;0&#39; value.
Definition: APInt.h:562
const TerminatorInst * getTerminator() const LLVM_READONLY
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:120
This node is a base class providing common functionality for n&#39;ary operators.
This class represents an assumption made on an AddRec expression.
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...
Value * SimplifyInstruction(Instruction *I, const SimplifyQuery &Q, OptimizationRemarkEmitter *ORE=nullptr)
See if we can compute a simplified version of this instruction.
BlockT * getExitingBlock() const
If getExitingBlocks would return exactly one block, return that block.
Definition: LoopInfoImpl.h:50
NoWrapFlags getNoWrapFlags(NoWrapFlags Mask=NoWrapMask) const
const SCEV * getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth=0)
This class represents an assumption that two SCEV expressions are equal, and this can be checked at r...
static IntegerType * getInt8Ty(LLVMContext &C)
Definition: Type.cpp:174
IncrementWrapFlags getFlags() const
Returns the set assumed no overflow flags.
Type * getElementType() const
Definition: DerivedTypes.h:486
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:422
const SCEV * getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth=0)
const BasicBlock * getParent() const
Definition: Instruction.h:67
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...
This class represents a constant integer value.
CmpClass_match< LHS, RHS, ICmpInst, ICmpInst::Predicate > m_ICmp(ICmpInst::Predicate &Pred, const LHS &L, const RHS &R)
Definition: PatternMatch.h:900