LLVM  10.0.0svn
ScalarEvolutionExpander.cpp
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1 //===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis ------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains the implementation of the scalar evolution expander,
10 // which is used to generate the code corresponding to a given scalar evolution
11 // expression.
12 //
13 //===----------------------------------------------------------------------===//
14 
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/SmallSet.h"
19 #include "llvm/Analysis/LoopInfo.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/Dominators.h"
23 #include "llvm/IR/IntrinsicInst.h"
24 #include "llvm/IR/LLVMContext.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/IR/PatternMatch.h"
27 #include "llvm/Support/Debug.h"
29 
30 using namespace llvm;
31 using namespace PatternMatch;
32 
33 /// ReuseOrCreateCast - Arrange for there to be a cast of V to Ty at IP,
34 /// reusing an existing cast if a suitable one exists, moving an existing
35 /// cast if a suitable one exists but isn't in the right place, or
36 /// creating a new one.
37 Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
40  // This function must be called with the builder having a valid insertion
41  // point. It doesn't need to be the actual IP where the uses of the returned
42  // cast will be added, but it must dominate such IP.
43  // We use this precondition to produce a cast that will dominate all its
44  // uses. In particular, this is crucial for the case where the builder's
45  // insertion point *is* the point where we were asked to put the cast.
46  // Since we don't know the builder's insertion point is actually
47  // where the uses will be added (only that it dominates it), we are
48  // not allowed to move it.
49  BasicBlock::iterator BIP = Builder.GetInsertPoint();
50 
51  Instruction *Ret = nullptr;
52 
53  // Check to see if there is already a cast!
54  for (User *U : V->users())
55  if (U->getType() == Ty)
56  if (CastInst *CI = dyn_cast<CastInst>(U))
57  if (CI->getOpcode() == Op) {
58  // If the cast isn't where we want it, create a new cast at IP.
59  // Likewise, do not reuse a cast at BIP because it must dominate
60  // instructions that might be inserted before BIP.
61  if (BasicBlock::iterator(CI) != IP || BIP == IP) {
62  // Create a new cast, and leave the old cast in place in case
63  // it is being used as an insert point.
64  Ret = CastInst::Create(Op, V, Ty, "", &*IP);
65  Ret->takeName(CI);
66  CI->replaceAllUsesWith(Ret);
67  break;
68  }
69  Ret = CI;
70  break;
71  }
72 
73  // Create a new cast.
74  if (!Ret)
75  Ret = CastInst::Create(Op, V, Ty, V->getName(), &*IP);
76 
77  // We assert at the end of the function since IP might point to an
78  // instruction with different dominance properties than a cast
79  // (an invoke for example) and not dominate BIP (but the cast does).
80  assert(SE.DT.dominates(Ret, &*BIP));
81 
82  rememberInstruction(Ret);
83  return Ret;
84 }
85 
87  BasicBlock *MustDominate) {
89  if (auto *II = dyn_cast<InvokeInst>(I))
90  IP = II->getNormalDest()->begin();
91 
92  while (isa<PHINode>(IP))
93  ++IP;
94 
95  if (isa<FuncletPadInst>(IP) || isa<LandingPadInst>(IP)) {
96  ++IP;
97  } else if (isa<CatchSwitchInst>(IP)) {
98  IP = MustDominate->getFirstInsertionPt();
99  } else {
100  assert(!IP->isEHPad() && "unexpected eh pad!");
101  }
102 
103  return IP;
104 }
105 
106 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
107 /// which must be possible with a noop cast, doing what we can to share
108 /// the casts.
109 Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) {
110  Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false);
111  assert((Op == Instruction::BitCast ||
112  Op == Instruction::PtrToInt ||
113  Op == Instruction::IntToPtr) &&
114  "InsertNoopCastOfTo cannot perform non-noop casts!");
115  assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) &&
116  "InsertNoopCastOfTo cannot change sizes!");
117 
118  // Short-circuit unnecessary bitcasts.
119  if (Op == Instruction::BitCast) {
120  if (V->getType() == Ty)
121  return V;
122  if (CastInst *CI = dyn_cast<CastInst>(V)) {
123  if (CI->getOperand(0)->getType() == Ty)
124  return CI->getOperand(0);
125  }
126  }
127  // Short-circuit unnecessary inttoptr<->ptrtoint casts.
128  if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) &&
129  SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {
130  if (CastInst *CI = dyn_cast<CastInst>(V))
131  if ((CI->getOpcode() == Instruction::PtrToInt ||
132  CI->getOpcode() == Instruction::IntToPtr) &&
133  SE.getTypeSizeInBits(CI->getType()) ==
134  SE.getTypeSizeInBits(CI->getOperand(0)->getType()))
135  return CI->getOperand(0);
136  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
137  if ((CE->getOpcode() == Instruction::PtrToInt ||
138  CE->getOpcode() == Instruction::IntToPtr) &&
139  SE.getTypeSizeInBits(CE->getType()) ==
140  SE.getTypeSizeInBits(CE->getOperand(0)->getType()))
141  return CE->getOperand(0);
142  }
143 
144  // Fold a cast of a constant.
145  if (Constant *C = dyn_cast<Constant>(V))
146  return ConstantExpr::getCast(Op, C, Ty);
147 
148  // Cast the argument at the beginning of the entry block, after
149  // any bitcasts of other arguments.
150  if (Argument *A = dyn_cast<Argument>(V)) {
151  BasicBlock::iterator IP = A->getParent()->getEntryBlock().begin();
152  while ((isa<BitCastInst>(IP) &&
153  isa<Argument>(cast<BitCastInst>(IP)->getOperand(0)) &&
154  cast<BitCastInst>(IP)->getOperand(0) != A) ||
155  isa<DbgInfoIntrinsic>(IP))
156  ++IP;
157  return ReuseOrCreateCast(A, Ty, Op, IP);
158  }
159 
160  // Cast the instruction immediately after the instruction.
161  Instruction *I = cast<Instruction>(V);
162  BasicBlock::iterator IP = findInsertPointAfter(I, Builder.GetInsertBlock());
163  return ReuseOrCreateCast(I, Ty, Op, IP);
164 }
165 
166 /// InsertBinop - Insert the specified binary operator, doing a small amount
167 /// of work to avoid inserting an obviously redundant operation, and hoisting
168 /// to an outer loop when the opportunity is there and it is safe.
169 Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
170  Value *LHS, Value *RHS,
171  SCEV::NoWrapFlags Flags, bool IsSafeToHoist) {
172  // Fold a binop with constant operands.
173  if (Constant *CLHS = dyn_cast<Constant>(LHS))
174  if (Constant *CRHS = dyn_cast<Constant>(RHS))
175  return ConstantExpr::get(Opcode, CLHS, CRHS);
176 
177  // Do a quick scan to see if we have this binop nearby. If so, reuse it.
178  unsigned ScanLimit = 6;
179  BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
180  // Scanning starts from the last instruction before the insertion point.
181  BasicBlock::iterator IP = Builder.GetInsertPoint();
182  if (IP != BlockBegin) {
183  --IP;
184  for (; ScanLimit; --IP, --ScanLimit) {
185  // Don't count dbg.value against the ScanLimit, to avoid perturbing the
186  // generated code.
187  if (isa<DbgInfoIntrinsic>(IP))
188  ScanLimit++;
189 
190  auto canGenerateIncompatiblePoison = [&Flags](Instruction *I) {
191  // Ensure that no-wrap flags match.
192  if (isa<OverflowingBinaryOperator>(I)) {
193  if (I->hasNoSignedWrap() != (Flags & SCEV::FlagNSW))
194  return true;
195  if (I->hasNoUnsignedWrap() != (Flags & SCEV::FlagNUW))
196  return true;
197  }
198  // Conservatively, do not use any instruction which has any of exact
199  // flags installed.
200  if (isa<PossiblyExactOperator>(I) && I->isExact())
201  return true;
202  return false;
203  };
204  if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
205  IP->getOperand(1) == RHS && !canGenerateIncompatiblePoison(&*IP))
206  return &*IP;
207  if (IP == BlockBegin) break;
208  }
209  }
210 
211  // Save the original insertion point so we can restore it when we're done.
212  DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
213  SCEVInsertPointGuard Guard(Builder, this);
214 
215  if (IsSafeToHoist) {
216  // Move the insertion point out of as many loops as we can.
217  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
218  if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break;
219  BasicBlock *Preheader = L->getLoopPreheader();
220  if (!Preheader) break;
221 
222  // Ok, move up a level.
223  Builder.SetInsertPoint(Preheader->getTerminator());
224  }
225  }
226 
227  // If we haven't found this binop, insert it.
228  Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS));
229  BO->setDebugLoc(Loc);
230  if (Flags & SCEV::FlagNUW)
231  BO->setHasNoUnsignedWrap();
232  if (Flags & SCEV::FlagNSW)
233  BO->setHasNoSignedWrap();
234  rememberInstruction(BO);
235 
236  return BO;
237 }
238 
239 /// FactorOutConstant - Test if S is divisible by Factor, using signed
240 /// division. If so, update S with Factor divided out and return true.
241 /// S need not be evenly divisible if a reasonable remainder can be
242 /// computed.
243 /// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made
244 /// unnecessary; in its place, just signed-divide Ops[i] by the scale and
245 /// check to see if the divide was folded.
246 static bool FactorOutConstant(const SCEV *&S, const SCEV *&Remainder,
247  const SCEV *Factor, ScalarEvolution &SE,
248  const DataLayout &DL) {
249  // Everything is divisible by one.
250  if (Factor->isOne())
251  return true;
252 
253  // x/x == 1.
254  if (S == Factor) {
255  S = SE.getConstant(S->getType(), 1);
256  return true;
257  }
258 
259  // For a Constant, check for a multiple of the given factor.
260  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
261  // 0/x == 0.
262  if (C->isZero())
263  return true;
264  // Check for divisibility.
265  if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor)) {
266  ConstantInt *CI =
267  ConstantInt::get(SE.getContext(), C->getAPInt().sdiv(FC->getAPInt()));
268  // If the quotient is zero and the remainder is non-zero, reject
269  // the value at this scale. It will be considered for subsequent
270  // smaller scales.
271  if (!CI->isZero()) {
272  const SCEV *Div = SE.getConstant(CI);
273  S = Div;
274  Remainder = SE.getAddExpr(
275  Remainder, SE.getConstant(C->getAPInt().srem(FC->getAPInt())));
276  return true;
277  }
278  }
279  }
280 
281  // In a Mul, check if there is a constant operand which is a multiple
282  // of the given factor.
283  if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
284  // Size is known, check if there is a constant operand which is a multiple
285  // of the given factor. If so, we can factor it.
286  const SCEVConstant *FC = cast<SCEVConstant>(Factor);
287  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
288  if (!C->getAPInt().srem(FC->getAPInt())) {
289  SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
290  NewMulOps[0] = SE.getConstant(C->getAPInt().sdiv(FC->getAPInt()));
291  S = SE.getMulExpr(NewMulOps);
292  return true;
293  }
294  }
295 
296  // In an AddRec, check if both start and step are divisible.
297  if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
298  const SCEV *Step = A->getStepRecurrence(SE);
299  const SCEV *StepRem = SE.getConstant(Step->getType(), 0);
300  if (!FactorOutConstant(Step, StepRem, Factor, SE, DL))
301  return false;
302  if (!StepRem->isZero())
303  return false;
304  const SCEV *Start = A->getStart();
305  if (!FactorOutConstant(Start, Remainder, Factor, SE, DL))
306  return false;
307  S = SE.getAddRecExpr(Start, Step, A->getLoop(),
308  A->getNoWrapFlags(SCEV::FlagNW));
309  return true;
310  }
311 
312  return false;
313 }
314 
315 /// SimplifyAddOperands - Sort and simplify a list of add operands. NumAddRecs
316 /// is the number of SCEVAddRecExprs present, which are kept at the end of
317 /// the list.
318 ///
320  Type *Ty,
321  ScalarEvolution &SE) {
322  unsigned NumAddRecs = 0;
323  for (unsigned i = Ops.size(); i > 0 && isa<SCEVAddRecExpr>(Ops[i-1]); --i)
324  ++NumAddRecs;
325  // Group Ops into non-addrecs and addrecs.
326  SmallVector<const SCEV *, 8> NoAddRecs(Ops.begin(), Ops.end() - NumAddRecs);
327  SmallVector<const SCEV *, 8> AddRecs(Ops.end() - NumAddRecs, Ops.end());
328  // Let ScalarEvolution sort and simplify the non-addrecs list.
329  const SCEV *Sum = NoAddRecs.empty() ?
330  SE.getConstant(Ty, 0) :
331  SE.getAddExpr(NoAddRecs);
332  // If it returned an add, use the operands. Otherwise it simplified
333  // the sum into a single value, so just use that.
334  Ops.clear();
335  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum))
336  Ops.append(Add->op_begin(), Add->op_end());
337  else if (!Sum->isZero())
338  Ops.push_back(Sum);
339  // Then append the addrecs.
340  Ops.append(AddRecs.begin(), AddRecs.end());
341 }
342 
343 /// SplitAddRecs - Flatten a list of add operands, moving addrec start values
344 /// out to the top level. For example, convert {a + b,+,c} to a, b, {0,+,d}.
345 /// This helps expose more opportunities for folding parts of the expressions
346 /// into GEP indices.
347 ///
349  Type *Ty,
350  ScalarEvolution &SE) {
351  // Find the addrecs.
353  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
354  while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i])) {
355  const SCEV *Start = A->getStart();
356  if (Start->isZero()) break;
357  const SCEV *Zero = SE.getConstant(Ty, 0);
358  AddRecs.push_back(SE.getAddRecExpr(Zero,
359  A->getStepRecurrence(SE),
360  A->getLoop(),
361  A->getNoWrapFlags(SCEV::FlagNW)));
362  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
363  Ops[i] = Zero;
364  Ops.append(Add->op_begin(), Add->op_end());
365  e += Add->getNumOperands();
366  } else {
367  Ops[i] = Start;
368  }
369  }
370  if (!AddRecs.empty()) {
371  // Add the addrecs onto the end of the list.
372  Ops.append(AddRecs.begin(), AddRecs.end());
373  // Resort the operand list, moving any constants to the front.
374  SimplifyAddOperands(Ops, Ty, SE);
375  }
376 }
377 
378 /// expandAddToGEP - Expand an addition expression with a pointer type into
379 /// a GEP instead of using ptrtoint+arithmetic+inttoptr. This helps
380 /// BasicAliasAnalysis and other passes analyze the result. See the rules
381 /// for getelementptr vs. inttoptr in
382 /// http://llvm.org/docs/LangRef.html#pointeraliasing
383 /// for details.
384 ///
385 /// Design note: The correctness of using getelementptr here depends on
386 /// ScalarEvolution not recognizing inttoptr and ptrtoint operators, as
387 /// they may introduce pointer arithmetic which may not be safely converted
388 /// into getelementptr.
389 ///
390 /// Design note: It might seem desirable for this function to be more
391 /// loop-aware. If some of the indices are loop-invariant while others
392 /// aren't, it might seem desirable to emit multiple GEPs, keeping the
393 /// loop-invariant portions of the overall computation outside the loop.
394 /// However, there are a few reasons this is not done here. Hoisting simple
395 /// arithmetic is a low-level optimization that often isn't very
396 /// important until late in the optimization process. In fact, passes
397 /// like InstructionCombining will combine GEPs, even if it means
398 /// pushing loop-invariant computation down into loops, so even if the
399 /// GEPs were split here, the work would quickly be undone. The
400 /// LoopStrengthReduction pass, which is usually run quite late (and
401 /// after the last InstructionCombining pass), takes care of hoisting
402 /// loop-invariant portions of expressions, after considering what
403 /// can be folded using target addressing modes.
404 ///
405 Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
406  const SCEV *const *op_end,
407  PointerType *PTy,
408  Type *Ty,
409  Value *V) {
410  Type *OriginalElTy = PTy->getElementType();
411  Type *ElTy = OriginalElTy;
412  SmallVector<Value *, 4> GepIndices;
413  SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
414  bool AnyNonZeroIndices = false;
415 
416  // Split AddRecs up into parts as either of the parts may be usable
417  // without the other.
418  SplitAddRecs(Ops, Ty, SE);
419 
420  Type *IntPtrTy = DL.getIntPtrType(PTy);
421 
422  // Descend down the pointer's type and attempt to convert the other
423  // operands into GEP indices, at each level. The first index in a GEP
424  // indexes into the array implied by the pointer operand; the rest of
425  // the indices index into the element or field type selected by the
426  // preceding index.
427  for (;;) {
428  // If the scale size is not 0, attempt to factor out a scale for
429  // array indexing.
431  if (ElTy->isSized()) {
432  const SCEV *ElSize = SE.getSizeOfExpr(IntPtrTy, ElTy);
433  if (!ElSize->isZero()) {
435  for (const SCEV *Op : Ops) {
436  const SCEV *Remainder = SE.getConstant(Ty, 0);
437  if (FactorOutConstant(Op, Remainder, ElSize, SE, DL)) {
438  // Op now has ElSize factored out.
439  ScaledOps.push_back(Op);
440  if (!Remainder->isZero())
441  NewOps.push_back(Remainder);
442  AnyNonZeroIndices = true;
443  } else {
444  // The operand was not divisible, so add it to the list of operands
445  // we'll scan next iteration.
446  NewOps.push_back(Op);
447  }
448  }
449  // If we made any changes, update Ops.
450  if (!ScaledOps.empty()) {
451  Ops = NewOps;
452  SimplifyAddOperands(Ops, Ty, SE);
453  }
454  }
455  }
456 
457  // Record the scaled array index for this level of the type. If
458  // we didn't find any operands that could be factored, tentatively
459  // assume that element zero was selected (since the zero offset
460  // would obviously be folded away).
461  Value *Scaled = ScaledOps.empty() ?
463  expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
464  GepIndices.push_back(Scaled);
465 
466  // Collect struct field index operands.
467  while (StructType *STy = dyn_cast<StructType>(ElTy)) {
468  bool FoundFieldNo = false;
469  // An empty struct has no fields.
470  if (STy->getNumElements() == 0) break;
471  // Field offsets are known. See if a constant offset falls within any of
472  // the struct fields.
473  if (Ops.empty())
474  break;
475  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
476  if (SE.getTypeSizeInBits(C->getType()) <= 64) {
477  const StructLayout &SL = *DL.getStructLayout(STy);
478  uint64_t FullOffset = C->getValue()->getZExtValue();
479  if (FullOffset < SL.getSizeInBytes()) {
480  unsigned ElIdx = SL.getElementContainingOffset(FullOffset);
481  GepIndices.push_back(
483  ElTy = STy->getTypeAtIndex(ElIdx);
484  Ops[0] =
485  SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx));
486  AnyNonZeroIndices = true;
487  FoundFieldNo = true;
488  }
489  }
490  // If no struct field offsets were found, tentatively assume that
491  // field zero was selected (since the zero offset would obviously
492  // be folded away).
493  if (!FoundFieldNo) {
494  ElTy = STy->getTypeAtIndex(0u);
495  GepIndices.push_back(
497  }
498  }
499 
500  if (ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
501  ElTy = ATy->getElementType();
502  else
503  break;
504  }
505 
506  // If none of the operands were convertible to proper GEP indices, cast
507  // the base to i8* and do an ugly getelementptr with that. It's still
508  // better than ptrtoint+arithmetic+inttoptr at least.
509  if (!AnyNonZeroIndices) {
510  // Cast the base to i8*.
511  V = InsertNoopCastOfTo(V,
513 
514  assert(!isa<Instruction>(V) ||
515  SE.DT.dominates(cast<Instruction>(V), &*Builder.GetInsertPoint()));
516 
517  // Expand the operands for a plain byte offset.
518  Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
519 
520  // Fold a GEP with constant operands.
521  if (Constant *CLHS = dyn_cast<Constant>(V))
522  if (Constant *CRHS = dyn_cast<Constant>(Idx))
524  CLHS, CRHS);
525 
526  // Do a quick scan to see if we have this GEP nearby. If so, reuse it.
527  unsigned ScanLimit = 6;
528  BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
529  // Scanning starts from the last instruction before the insertion point.
530  BasicBlock::iterator IP = Builder.GetInsertPoint();
531  if (IP != BlockBegin) {
532  --IP;
533  for (; ScanLimit; --IP, --ScanLimit) {
534  // Don't count dbg.value against the ScanLimit, to avoid perturbing the
535  // generated code.
536  if (isa<DbgInfoIntrinsic>(IP))
537  ScanLimit++;
538  if (IP->getOpcode() == Instruction::GetElementPtr &&
539  IP->getOperand(0) == V && IP->getOperand(1) == Idx)
540  return &*IP;
541  if (IP == BlockBegin) break;
542  }
543  }
544 
545  // Save the original insertion point so we can restore it when we're done.
546  SCEVInsertPointGuard Guard(Builder, this);
547 
548  // Move the insertion point out of as many loops as we can.
549  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
550  if (!L->isLoopInvariant(V) || !L->isLoopInvariant(Idx)) break;
551  BasicBlock *Preheader = L->getLoopPreheader();
552  if (!Preheader) break;
553 
554  // Ok, move up a level.
555  Builder.SetInsertPoint(Preheader->getTerminator());
556  }
557 
558  // Emit a GEP.
559  Value *GEP = Builder.CreateGEP(Builder.getInt8Ty(), V, Idx, "uglygep");
560  rememberInstruction(GEP);
561 
562  return GEP;
563  }
564 
565  {
566  SCEVInsertPointGuard Guard(Builder, this);
567 
568  // Move the insertion point out of as many loops as we can.
569  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
570  if (!L->isLoopInvariant(V)) break;
571 
572  bool AnyIndexNotLoopInvariant = any_of(
573  GepIndices, [L](Value *Op) { return !L->isLoopInvariant(Op); });
574 
575  if (AnyIndexNotLoopInvariant)
576  break;
577 
578  BasicBlock *Preheader = L->getLoopPreheader();
579  if (!Preheader) break;
580 
581  // Ok, move up a level.
582  Builder.SetInsertPoint(Preheader->getTerminator());
583  }
584 
585  // Insert a pretty getelementptr. Note that this GEP is not marked inbounds,
586  // because ScalarEvolution may have changed the address arithmetic to
587  // compute a value which is beyond the end of the allocated object.
588  Value *Casted = V;
589  if (V->getType() != PTy)
590  Casted = InsertNoopCastOfTo(Casted, PTy);
591  Value *GEP = Builder.CreateGEP(OriginalElTy, Casted, GepIndices, "scevgep");
592  Ops.push_back(SE.getUnknown(GEP));
593  rememberInstruction(GEP);
594  }
595 
596  return expand(SE.getAddExpr(Ops));
597 }
598 
599 Value *SCEVExpander::expandAddToGEP(const SCEV *Op, PointerType *PTy, Type *Ty,
600  Value *V) {
601  const SCEV *const Ops[1] = {Op};
602  return expandAddToGEP(Ops, Ops + 1, PTy, Ty, V);
603 }
604 
605 /// PickMostRelevantLoop - Given two loops pick the one that's most relevant for
606 /// SCEV expansion. If they are nested, this is the most nested. If they are
607 /// neighboring, pick the later.
608 static const Loop *PickMostRelevantLoop(const Loop *A, const Loop *B,
609  DominatorTree &DT) {
610  if (!A) return B;
611  if (!B) return A;
612  if (A->contains(B)) return B;
613  if (B->contains(A)) return A;
614  if (DT.dominates(A->getHeader(), B->getHeader())) return B;
615  if (DT.dominates(B->getHeader(), A->getHeader())) return A;
616  return A; // Arbitrarily break the tie.
617 }
618 
619 /// getRelevantLoop - Get the most relevant loop associated with the given
620 /// expression, according to PickMostRelevantLoop.
621 const Loop *SCEVExpander::getRelevantLoop(const SCEV *S) {
622  // Test whether we've already computed the most relevant loop for this SCEV.
623  auto Pair = RelevantLoops.insert(std::make_pair(S, nullptr));
624  if (!Pair.second)
625  return Pair.first->second;
626 
627  if (isa<SCEVConstant>(S))
628  // A constant has no relevant loops.
629  return nullptr;
630  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
631  if (const Instruction *I = dyn_cast<Instruction>(U->getValue()))
632  return Pair.first->second = SE.LI.getLoopFor(I->getParent());
633  // A non-instruction has no relevant loops.
634  return nullptr;
635  }
636  if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) {
637  const Loop *L = nullptr;
638  if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
639  L = AR->getLoop();
640  for (const SCEV *Op : N->operands())
641  L = PickMostRelevantLoop(L, getRelevantLoop(Op), SE.DT);
642  return RelevantLoops[N] = L;
643  }
644  if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) {
645  const Loop *Result = getRelevantLoop(C->getOperand());
646  return RelevantLoops[C] = Result;
647  }
648  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
649  const Loop *Result = PickMostRelevantLoop(
650  getRelevantLoop(D->getLHS()), getRelevantLoop(D->getRHS()), SE.DT);
651  return RelevantLoops[D] = Result;
652  }
653  llvm_unreachable("Unexpected SCEV type!");
654 }
655 
656 namespace {
657 
658 /// LoopCompare - Compare loops by PickMostRelevantLoop.
659 class LoopCompare {
660  DominatorTree &DT;
661 public:
662  explicit LoopCompare(DominatorTree &dt) : DT(dt) {}
663 
664  bool operator()(std::pair<const Loop *, const SCEV *> LHS,
665  std::pair<const Loop *, const SCEV *> RHS) const {
666  // Keep pointer operands sorted at the end.
667  if (LHS.second->getType()->isPointerTy() !=
668  RHS.second->getType()->isPointerTy())
669  return LHS.second->getType()->isPointerTy();
670 
671  // Compare loops with PickMostRelevantLoop.
672  if (LHS.first != RHS.first)
673  return PickMostRelevantLoop(LHS.first, RHS.first, DT) != LHS.first;
674 
675  // If one operand is a non-constant negative and the other is not,
676  // put the non-constant negative on the right so that a sub can
677  // be used instead of a negate and add.
678  if (LHS.second->isNonConstantNegative()) {
679  if (!RHS.second->isNonConstantNegative())
680  return false;
681  } else if (RHS.second->isNonConstantNegative())
682  return true;
683 
684  // Otherwise they are equivalent according to this comparison.
685  return false;
686  }
687 };
688 
689 }
690 
691 Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
692  Type *Ty = SE.getEffectiveSCEVType(S->getType());
693 
694  // Collect all the add operands in a loop, along with their associated loops.
695  // Iterate in reverse so that constants are emitted last, all else equal, and
696  // so that pointer operands are inserted first, which the code below relies on
697  // to form more involved GEPs.
699  for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(S->op_end()),
700  E(S->op_begin()); I != E; ++I)
701  OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
702 
703  // Sort by loop. Use a stable sort so that constants follow non-constants and
704  // pointer operands precede non-pointer operands.
705  llvm::stable_sort(OpsAndLoops, LoopCompare(SE.DT));
706 
707  // Emit instructions to add all the operands. Hoist as much as possible
708  // out of loops, and form meaningful getelementptrs where possible.
709  Value *Sum = nullptr;
710  for (auto I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E;) {
711  const Loop *CurLoop = I->first;
712  const SCEV *Op = I->second;
713  if (!Sum) {
714  // This is the first operand. Just expand it.
715  Sum = expand(Op);
716  ++I;
717  } else if (PointerType *PTy = dyn_cast<PointerType>(Sum->getType())) {
718  // The running sum expression is a pointer. Try to form a getelementptr
719  // at this level with that as the base.
721  for (; I != E && I->first == CurLoop; ++I) {
722  // If the operand is SCEVUnknown and not instructions, peek through
723  // it, to enable more of it to be folded into the GEP.
724  const SCEV *X = I->second;
725  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(X))
726  if (!isa<Instruction>(U->getValue()))
727  X = SE.getSCEV(U->getValue());
728  NewOps.push_back(X);
729  }
730  Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum);
731  } else if (PointerType *PTy = dyn_cast<PointerType>(Op->getType())) {
732  // The running sum is an integer, and there's a pointer at this level.
733  // Try to form a getelementptr. If the running sum is instructions,
734  // use a SCEVUnknown to avoid re-analyzing them.
736  NewOps.push_back(isa<Instruction>(Sum) ? SE.getUnknown(Sum) :
737  SE.getSCEV(Sum));
738  for (++I; I != E && I->first == CurLoop; ++I)
739  NewOps.push_back(I->second);
740  Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, expand(Op));
741  } else if (Op->isNonConstantNegative()) {
742  // Instead of doing a negate and add, just do a subtract.
743  Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty);
744  Sum = InsertNoopCastOfTo(Sum, Ty);
745  Sum = InsertBinop(Instruction::Sub, Sum, W, SCEV::FlagAnyWrap,
746  /*IsSafeToHoist*/ true);
747  ++I;
748  } else {
749  // A simple add.
750  Value *W = expandCodeFor(Op, Ty);
751  Sum = InsertNoopCastOfTo(Sum, Ty);
752  // Canonicalize a constant to the RHS.
753  if (isa<Constant>(Sum)) std::swap(Sum, W);
754  Sum = InsertBinop(Instruction::Add, Sum, W, S->getNoWrapFlags(),
755  /*IsSafeToHoist*/ true);
756  ++I;
757  }
758  }
759 
760  return Sum;
761 }
762 
763 Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
764  Type *Ty = SE.getEffectiveSCEVType(S->getType());
765 
766  // Collect all the mul operands in a loop, along with their associated loops.
767  // Iterate in reverse so that constants are emitted last, all else equal.
769  for (std::reverse_iterator<SCEVMulExpr::op_iterator> I(S->op_end()),
770  E(S->op_begin()); I != E; ++I)
771  OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
772 
773  // Sort by loop. Use a stable sort so that constants follow non-constants.
774  llvm::stable_sort(OpsAndLoops, LoopCompare(SE.DT));
775 
776  // Emit instructions to mul all the operands. Hoist as much as possible
777  // out of loops.
778  Value *Prod = nullptr;
779  auto I = OpsAndLoops.begin();
780 
781  // Expand the calculation of X pow N in the following manner:
782  // Let N = P1 + P2 + ... + PK, where all P are powers of 2. Then:
783  // X pow N = (X pow P1) * (X pow P2) * ... * (X pow PK).
784  const auto ExpandOpBinPowN = [this, &I, &OpsAndLoops, &Ty]() {
785  auto E = I;
786  // Calculate how many times the same operand from the same loop is included
787  // into this power.
788  uint64_t Exponent = 0;
789  const uint64_t MaxExponent = UINT64_MAX >> 1;
790  // No one sane will ever try to calculate such huge exponents, but if we
791  // need this, we stop on UINT64_MAX / 2 because we need to exit the loop
792  // below when the power of 2 exceeds our Exponent, and we want it to be
793  // 1u << 31 at most to not deal with unsigned overflow.
794  while (E != OpsAndLoops.end() && *I == *E && Exponent != MaxExponent) {
795  ++Exponent;
796  ++E;
797  }
798  assert(Exponent > 0 && "Trying to calculate a zeroth exponent of operand?");
799 
800  // Calculate powers with exponents 1, 2, 4, 8 etc. and include those of them
801  // that are needed into the result.
802  Value *P = expandCodeFor(I->second, Ty);
803  Value *Result = nullptr;
804  if (Exponent & 1)
805  Result = P;
806  for (uint64_t BinExp = 2; BinExp <= Exponent; BinExp <<= 1) {
807  P = InsertBinop(Instruction::Mul, P, P, SCEV::FlagAnyWrap,
808  /*IsSafeToHoist*/ true);
809  if (Exponent & BinExp)
810  Result = Result ? InsertBinop(Instruction::Mul, Result, P,
812  /*IsSafeToHoist*/ true)
813  : P;
814  }
815 
816  I = E;
817  assert(Result && "Nothing was expanded?");
818  return Result;
819  };
820 
821  while (I != OpsAndLoops.end()) {
822  if (!Prod) {
823  // This is the first operand. Just expand it.
824  Prod = ExpandOpBinPowN();
825  } else if (I->second->isAllOnesValue()) {
826  // Instead of doing a multiply by negative one, just do a negate.
827  Prod = InsertNoopCastOfTo(Prod, Ty);
828  Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod,
829  SCEV::FlagAnyWrap, /*IsSafeToHoist*/ true);
830  ++I;
831  } else {
832  // A simple mul.
833  Value *W = ExpandOpBinPowN();
834  Prod = InsertNoopCastOfTo(Prod, Ty);
835  // Canonicalize a constant to the RHS.
836  if (isa<Constant>(Prod)) std::swap(Prod, W);
837  const APInt *RHS;
838  if (match(W, m_Power2(RHS))) {
839  // Canonicalize Prod*(1<<C) to Prod<<C.
840  assert(!Ty->isVectorTy() && "vector types are not SCEVable");
841  auto NWFlags = S->getNoWrapFlags();
842  // clear nsw flag if shl will produce poison value.
843  if (RHS->logBase2() == RHS->getBitWidth() - 1)
844  NWFlags = ScalarEvolution::clearFlags(NWFlags, SCEV::FlagNSW);
845  Prod = InsertBinop(Instruction::Shl, Prod,
846  ConstantInt::get(Ty, RHS->logBase2()), NWFlags,
847  /*IsSafeToHoist*/ true);
848  } else {
849  Prod = InsertBinop(Instruction::Mul, Prod, W, S->getNoWrapFlags(),
850  /*IsSafeToHoist*/ true);
851  }
852  }
853  }
854 
855  return Prod;
856 }
857 
858 Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
859  Type *Ty = SE.getEffectiveSCEVType(S->getType());
860 
861  Value *LHS = expandCodeFor(S->getLHS(), Ty);
862  if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
863  const APInt &RHS = SC->getAPInt();
864  if (RHS.isPowerOf2())
865  return InsertBinop(Instruction::LShr, LHS,
866  ConstantInt::get(Ty, RHS.logBase2()),
867  SCEV::FlagAnyWrap, /*IsSafeToHoist*/ true);
868  }
869 
870  Value *RHS = expandCodeFor(S->getRHS(), Ty);
871  return InsertBinop(Instruction::UDiv, LHS, RHS, SCEV::FlagAnyWrap,
872  /*IsSafeToHoist*/ SE.isKnownNonZero(S->getRHS()));
873 }
874 
875 /// Move parts of Base into Rest to leave Base with the minimal
876 /// expression that provides a pointer operand suitable for a
877 /// GEP expansion.
878 static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest,
879  ScalarEvolution &SE) {
880  while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) {
881  Base = A->getStart();
882  Rest = SE.getAddExpr(Rest,
883  SE.getAddRecExpr(SE.getConstant(A->getType(), 0),
884  A->getStepRecurrence(SE),
885  A->getLoop(),
886  A->getNoWrapFlags(SCEV::FlagNW)));
887  }
888  if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
889  Base = A->getOperand(A->getNumOperands()-1);
890  SmallVector<const SCEV *, 8> NewAddOps(A->op_begin(), A->op_end());
891  NewAddOps.back() = Rest;
892  Rest = SE.getAddExpr(NewAddOps);
893  ExposePointerBase(Base, Rest, SE);
894  }
895 }
896 
897 /// Determine if this is a well-behaved chain of instructions leading back to
898 /// the PHI. If so, it may be reused by expanded expressions.
899 bool SCEVExpander::isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV,
900  const Loop *L) {
901  if (IncV->getNumOperands() == 0 || isa<PHINode>(IncV) ||
902  (isa<CastInst>(IncV) && !isa<BitCastInst>(IncV)))
903  return false;
904  // If any of the operands don't dominate the insert position, bail.
905  // Addrec operands are always loop-invariant, so this can only happen
906  // if there are instructions which haven't been hoisted.
907  if (L == IVIncInsertLoop) {
908  for (User::op_iterator OI = IncV->op_begin()+1,
909  OE = IncV->op_end(); OI != OE; ++OI)
910  if (Instruction *OInst = dyn_cast<Instruction>(OI))
911  if (!SE.DT.dominates(OInst, IVIncInsertPos))
912  return false;
913  }
914  // Advance to the next instruction.
915  IncV = dyn_cast<Instruction>(IncV->getOperand(0));
916  if (!IncV)
917  return false;
918 
919  if (IncV->mayHaveSideEffects())
920  return false;
921 
922  if (IncV == PN)
923  return true;
924 
925  return isNormalAddRecExprPHI(PN, IncV, L);
926 }
927 
928 /// getIVIncOperand returns an induction variable increment's induction
929 /// variable operand.
930 ///
931 /// If allowScale is set, any type of GEP is allowed as long as the nonIV
932 /// operands dominate InsertPos.
933 ///
934 /// If allowScale is not set, ensure that a GEP increment conforms to one of the
935 /// simple patterns generated by getAddRecExprPHILiterally and
936 /// expandAddtoGEP. If the pattern isn't recognized, return NULL.
938  Instruction *InsertPos,
939  bool allowScale) {
940  if (IncV == InsertPos)
941  return nullptr;
942 
943  switch (IncV->getOpcode()) {
944  default:
945  return nullptr;
946  // Check for a simple Add/Sub or GEP of a loop invariant step.
947  case Instruction::Add:
948  case Instruction::Sub: {
949  Instruction *OInst = dyn_cast<Instruction>(IncV->getOperand(1));
950  if (!OInst || SE.DT.dominates(OInst, InsertPos))
951  return dyn_cast<Instruction>(IncV->getOperand(0));
952  return nullptr;
953  }
954  case Instruction::BitCast:
955  return dyn_cast<Instruction>(IncV->getOperand(0));
956  case Instruction::GetElementPtr:
957  for (auto I = IncV->op_begin() + 1, E = IncV->op_end(); I != E; ++I) {
958  if (isa<Constant>(*I))
959  continue;
960  if (Instruction *OInst = dyn_cast<Instruction>(*I)) {
961  if (!SE.DT.dominates(OInst, InsertPos))
962  return nullptr;
963  }
964  if (allowScale) {
965  // allow any kind of GEP as long as it can be hoisted.
966  continue;
967  }
968  // This must be a pointer addition of constants (pretty), which is already
969  // handled, or some number of address-size elements (ugly). Ugly geps
970  // have 2 operands. i1* is used by the expander to represent an
971  // address-size element.
972  if (IncV->getNumOperands() != 2)
973  return nullptr;
974  unsigned AS = cast<PointerType>(IncV->getType())->getAddressSpace();
975  if (IncV->getType() != Type::getInt1PtrTy(SE.getContext(), AS)
976  && IncV->getType() != Type::getInt8PtrTy(SE.getContext(), AS))
977  return nullptr;
978  break;
979  }
980  return dyn_cast<Instruction>(IncV->getOperand(0));
981  }
982 }
983 
984 /// If the insert point of the current builder or any of the builders on the
985 /// stack of saved builders has 'I' as its insert point, update it to point to
986 /// the instruction after 'I'. This is intended to be used when the instruction
987 /// 'I' is being moved. If this fixup is not done and 'I' is moved to a
988 /// different block, the inconsistent insert point (with a mismatched
989 /// Instruction and Block) can lead to an instruction being inserted in a block
990 /// other than its parent.
991 void SCEVExpander::fixupInsertPoints(Instruction *I) {
992  BasicBlock::iterator It(*I);
993  BasicBlock::iterator NewInsertPt = std::next(It);
994  if (Builder.GetInsertPoint() == It)
995  Builder.SetInsertPoint(&*NewInsertPt);
996  for (auto *InsertPtGuard : InsertPointGuards)
997  if (InsertPtGuard->GetInsertPoint() == It)
998  InsertPtGuard->SetInsertPoint(NewInsertPt);
999 }
1000 
1001 /// hoistStep - Attempt to hoist a simple IV increment above InsertPos to make
1002 /// it available to other uses in this loop. Recursively hoist any operands,
1003 /// until we reach a value that dominates InsertPos.
1005  if (SE.DT.dominates(IncV, InsertPos))
1006  return true;
1007 
1008  // InsertPos must itself dominate IncV so that IncV's new position satisfies
1009  // its existing users.
1010  if (isa<PHINode>(InsertPos) ||
1011  !SE.DT.dominates(InsertPos->getParent(), IncV->getParent()))
1012  return false;
1013 
1014  if (!SE.LI.movementPreservesLCSSAForm(IncV, InsertPos))
1015  return false;
1016 
1017  // Check that the chain of IV operands leading back to Phi can be hoisted.
1019  for(;;) {
1020  Instruction *Oper = getIVIncOperand(IncV, InsertPos, /*allowScale*/true);
1021  if (!Oper)
1022  return false;
1023  // IncV is safe to hoist.
1024  IVIncs.push_back(IncV);
1025  IncV = Oper;
1026  if (SE.DT.dominates(IncV, InsertPos))
1027  break;
1028  }
1029  for (auto I = IVIncs.rbegin(), E = IVIncs.rend(); I != E; ++I) {
1030  fixupInsertPoints(*I);
1031  (*I)->moveBefore(InsertPos);
1032  }
1033  return true;
1034 }
1035 
1036 /// Determine if this cyclic phi is in a form that would have been generated by
1037 /// LSR. We don't care if the phi was actually expanded in this pass, as long
1038 /// as it is in a low-cost form, for example, no implied multiplication. This
1039 /// should match any patterns generated by getAddRecExprPHILiterally and
1040 /// expandAddtoGEP.
1041 bool SCEVExpander::isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV,
1042  const Loop *L) {
1043  for(Instruction *IVOper = IncV;
1044  (IVOper = getIVIncOperand(IVOper, L->getLoopPreheader()->getTerminator(),
1045  /*allowScale=*/false));) {
1046  if (IVOper == PN)
1047  return true;
1048  }
1049  return false;
1050 }
1051 
1052 /// expandIVInc - Expand an IV increment at Builder's current InsertPos.
1053 /// Typically this is the LatchBlock terminator or IVIncInsertPos, but we may
1054 /// need to materialize IV increments elsewhere to handle difficult situations.
1055 Value *SCEVExpander::expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
1056  Type *ExpandTy, Type *IntTy,
1057  bool useSubtract) {
1058  Value *IncV;
1059  // If the PHI is a pointer, use a GEP, otherwise use an add or sub.
1060  if (ExpandTy->isPointerTy()) {
1061  PointerType *GEPPtrTy = cast<PointerType>(ExpandTy);
1062  // If the step isn't constant, don't use an implicitly scaled GEP, because
1063  // that would require a multiply inside the loop.
1064  if (!isa<ConstantInt>(StepV))
1065  GEPPtrTy = PointerType::get(Type::getInt1Ty(SE.getContext()),
1066  GEPPtrTy->getAddressSpace());
1067  IncV = expandAddToGEP(SE.getSCEV(StepV), GEPPtrTy, IntTy, PN);
1068  if (IncV->getType() != PN->getType()) {
1069  IncV = Builder.CreateBitCast(IncV, PN->getType());
1070  rememberInstruction(IncV);
1071  }
1072  } else {
1073  IncV = useSubtract ?
1074  Builder.CreateSub(PN, StepV, Twine(IVName) + ".iv.next") :
1075  Builder.CreateAdd(PN, StepV, Twine(IVName) + ".iv.next");
1076  rememberInstruction(IncV);
1077  }
1078  return IncV;
1079 }
1080 
1081 /// Hoist the addrec instruction chain rooted in the loop phi above the
1082 /// position. This routine assumes that this is possible (has been checked).
1083 void SCEVExpander::hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
1084  Instruction *Pos, PHINode *LoopPhi) {
1085  do {
1086  if (DT->dominates(InstToHoist, Pos))
1087  break;
1088  // Make sure the increment is where we want it. But don't move it
1089  // down past a potential existing post-inc user.
1090  fixupInsertPoints(InstToHoist);
1091  InstToHoist->moveBefore(Pos);
1092  Pos = InstToHoist;
1093  InstToHoist = cast<Instruction>(InstToHoist->getOperand(0));
1094  } while (InstToHoist != LoopPhi);
1095 }
1096 
1097 /// Check whether we can cheaply express the requested SCEV in terms of
1098 /// the available PHI SCEV by truncation and/or inversion of the step.
1100  const SCEVAddRecExpr *Phi,
1101  const SCEVAddRecExpr *Requested,
1102  bool &InvertStep) {
1103  Type *PhiTy = SE.getEffectiveSCEVType(Phi->getType());
1104  Type *RequestedTy = SE.getEffectiveSCEVType(Requested->getType());
1105 
1106  if (RequestedTy->getIntegerBitWidth() > PhiTy->getIntegerBitWidth())
1107  return false;
1108 
1109  // Try truncate it if necessary.
1110  Phi = dyn_cast<SCEVAddRecExpr>(SE.getTruncateOrNoop(Phi, RequestedTy));
1111  if (!Phi)
1112  return false;
1113 
1114  // Check whether truncation will help.
1115  if (Phi == Requested) {
1116  InvertStep = false;
1117  return true;
1118  }
1119 
1120  // Check whether inverting will help: {R,+,-1} == R - {0,+,1}.
1121  if (SE.getAddExpr(Requested->getStart(),
1122  SE.getNegativeSCEV(Requested)) == Phi) {
1123  InvertStep = true;
1124  return true;
1125  }
1126 
1127  return false;
1128 }
1129 
1130 static bool IsIncrementNSW(ScalarEvolution &SE, const SCEVAddRecExpr *AR) {
1131  if (!isa<IntegerType>(AR->getType()))
1132  return false;
1133 
1134  unsigned BitWidth = cast<IntegerType>(AR->getType())->getBitWidth();
1135  Type *WideTy = IntegerType::get(AR->getType()->getContext(), BitWidth * 2);
1136  const SCEV *Step = AR->getStepRecurrence(SE);
1137  const SCEV *OpAfterExtend = SE.getAddExpr(SE.getSignExtendExpr(Step, WideTy),
1138  SE.getSignExtendExpr(AR, WideTy));
1139  const SCEV *ExtendAfterOp =
1140  SE.getSignExtendExpr(SE.getAddExpr(AR, Step), WideTy);
1141  return ExtendAfterOp == OpAfterExtend;
1142 }
1143 
1144 static bool IsIncrementNUW(ScalarEvolution &SE, const SCEVAddRecExpr *AR) {
1145  if (!isa<IntegerType>(AR->getType()))
1146  return false;
1147 
1148  unsigned BitWidth = cast<IntegerType>(AR->getType())->getBitWidth();
1149  Type *WideTy = IntegerType::get(AR->getType()->getContext(), BitWidth * 2);
1150  const SCEV *Step = AR->getStepRecurrence(SE);
1151  const SCEV *OpAfterExtend = SE.getAddExpr(SE.getZeroExtendExpr(Step, WideTy),
1152  SE.getZeroExtendExpr(AR, WideTy));
1153  const SCEV *ExtendAfterOp =
1154  SE.getZeroExtendExpr(SE.getAddExpr(AR, Step), WideTy);
1155  return ExtendAfterOp == OpAfterExtend;
1156 }
1157 
1158 /// getAddRecExprPHILiterally - Helper for expandAddRecExprLiterally. Expand
1159 /// the base addrec, which is the addrec without any non-loop-dominating
1160 /// values, and return the PHI.
1161 PHINode *
1162 SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
1163  const Loop *L,
1164  Type *ExpandTy,
1165  Type *IntTy,
1166  Type *&TruncTy,
1167  bool &InvertStep) {
1168  assert((!IVIncInsertLoop||IVIncInsertPos) && "Uninitialized insert position");
1169 
1170  // Reuse a previously-inserted PHI, if present.
1171  BasicBlock *LatchBlock = L->getLoopLatch();
1172  if (LatchBlock) {
1173  PHINode *AddRecPhiMatch = nullptr;
1174  Instruction *IncV = nullptr;
1175  TruncTy = nullptr;
1176  InvertStep = false;
1177 
1178  // Only try partially matching scevs that need truncation and/or
1179  // step-inversion if we know this loop is outside the current loop.
1180  bool TryNonMatchingSCEV =
1181  IVIncInsertLoop &&
1182  SE.DT.properlyDominates(LatchBlock, IVIncInsertLoop->getHeader());
1183 
1184  for (PHINode &PN : L->getHeader()->phis()) {
1185  if (!SE.isSCEVable(PN.getType()))
1186  continue;
1187 
1188  const SCEVAddRecExpr *PhiSCEV = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(&PN));
1189  if (!PhiSCEV)
1190  continue;
1191 
1192  bool IsMatchingSCEV = PhiSCEV == Normalized;
1193  // We only handle truncation and inversion of phi recurrences for the
1194  // expanded expression if the expanded expression's loop dominates the
1195  // loop we insert to. Check now, so we can bail out early.
1196  if (!IsMatchingSCEV && !TryNonMatchingSCEV)
1197  continue;
1198 
1199  // TODO: this possibly can be reworked to avoid this cast at all.
1200  Instruction *TempIncV =
1202  if (!TempIncV)
1203  continue;
1204 
1205  // Check whether we can reuse this PHI node.
1206  if (LSRMode) {
1207  if (!isExpandedAddRecExprPHI(&PN, TempIncV, L))
1208  continue;
1209  if (L == IVIncInsertLoop && !hoistIVInc(TempIncV, IVIncInsertPos))
1210  continue;
1211  } else {
1212  if (!isNormalAddRecExprPHI(&PN, TempIncV, L))
1213  continue;
1214  }
1215 
1216  // Stop if we have found an exact match SCEV.
1217  if (IsMatchingSCEV) {
1218  IncV = TempIncV;
1219  TruncTy = nullptr;
1220  InvertStep = false;
1221  AddRecPhiMatch = &PN;
1222  break;
1223  }
1224 
1225  // Try whether the phi can be translated into the requested form
1226  // (truncated and/or offset by a constant).
1227  if ((!TruncTy || InvertStep) &&
1228  canBeCheaplyTransformed(SE, PhiSCEV, Normalized, InvertStep)) {
1229  // Record the phi node. But don't stop we might find an exact match
1230  // later.
1231  AddRecPhiMatch = &PN;
1232  IncV = TempIncV;
1233  TruncTy = SE.getEffectiveSCEVType(Normalized->getType());
1234  }
1235  }
1236 
1237  if (AddRecPhiMatch) {
1238  // Potentially, move the increment. We have made sure in
1239  // isExpandedAddRecExprPHI or hoistIVInc that this is possible.
1240  if (L == IVIncInsertLoop)
1241  hoistBeforePos(&SE.DT, IncV, IVIncInsertPos, AddRecPhiMatch);
1242 
1243  // Ok, the add recurrence looks usable.
1244  // Remember this PHI, even in post-inc mode.
1245  InsertedValues.insert(AddRecPhiMatch);
1246  // Remember the increment.
1247  rememberInstruction(IncV);
1248  return AddRecPhiMatch;
1249  }
1250  }
1251 
1252  // Save the original insertion point so we can restore it when we're done.
1253  SCEVInsertPointGuard Guard(Builder, this);
1254 
1255  // Another AddRec may need to be recursively expanded below. For example, if
1256  // this AddRec is quadratic, the StepV may itself be an AddRec in this
1257  // loop. Remove this loop from the PostIncLoops set before expanding such
1258  // AddRecs. Otherwise, we cannot find a valid position for the step
1259  // (i.e. StepV can never dominate its loop header). Ideally, we could do
1260  // SavedIncLoops.swap(PostIncLoops), but we generally have a single element,
1261  // so it's not worth implementing SmallPtrSet::swap.
1262  PostIncLoopSet SavedPostIncLoops = PostIncLoops;
1263  PostIncLoops.clear();
1264 
1265  // Expand code for the start value into the loop preheader.
1266  assert(L->getLoopPreheader() &&
1267  "Can't expand add recurrences without a loop preheader!");
1268  Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy,
1270 
1271  // StartV must have been be inserted into L's preheader to dominate the new
1272  // phi.
1273  assert(!isa<Instruction>(StartV) ||
1274  SE.DT.properlyDominates(cast<Instruction>(StartV)->getParent(),
1275  L->getHeader()));
1276 
1277  // Expand code for the step value. Do this before creating the PHI so that PHI
1278  // reuse code doesn't see an incomplete PHI.
1279  const SCEV *Step = Normalized->getStepRecurrence(SE);
1280  // If the stride is negative, insert a sub instead of an add for the increment
1281  // (unless it's a constant, because subtracts of constants are canonicalized
1282  // to adds).
1283  bool useSubtract = !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
1284  if (useSubtract)
1285  Step = SE.getNegativeSCEV(Step);
1286  // Expand the step somewhere that dominates the loop header.
1287  Value *StepV = expandCodeFor(Step, IntTy, &L->getHeader()->front());
1288 
1289  // The no-wrap behavior proved by IsIncrement(NUW|NSW) is only applicable if
1290  // we actually do emit an addition. It does not apply if we emit a
1291  // subtraction.
1292  bool IncrementIsNUW = !useSubtract && IsIncrementNUW(SE, Normalized);
1293  bool IncrementIsNSW = !useSubtract && IsIncrementNSW(SE, Normalized);
1294 
1295  // Create the PHI.
1296  BasicBlock *Header = L->getHeader();
1297  Builder.SetInsertPoint(Header, Header->begin());
1298  pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
1299  PHINode *PN = Builder.CreatePHI(ExpandTy, std::distance(HPB, HPE),
1300  Twine(IVName) + ".iv");
1301  rememberInstruction(PN);
1302 
1303  // Create the step instructions and populate the PHI.
1304  for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
1305  BasicBlock *Pred = *HPI;
1306 
1307  // Add a start value.
1308  if (!L->contains(Pred)) {
1309  PN->addIncoming(StartV, Pred);
1310  continue;
1311  }
1312 
1313  // Create a step value and add it to the PHI.
1314  // If IVIncInsertLoop is non-null and equal to the addrec's loop, insert the
1315  // instructions at IVIncInsertPos.
1316  Instruction *InsertPos = L == IVIncInsertLoop ?
1317  IVIncInsertPos : Pred->getTerminator();
1318  Builder.SetInsertPoint(InsertPos);
1319  Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
1320 
1321  if (isa<OverflowingBinaryOperator>(IncV)) {
1322  if (IncrementIsNUW)
1323  cast<BinaryOperator>(IncV)->setHasNoUnsignedWrap();
1324  if (IncrementIsNSW)
1325  cast<BinaryOperator>(IncV)->setHasNoSignedWrap();
1326  }
1327  PN->addIncoming(IncV, Pred);
1328  }
1329 
1330  // After expanding subexpressions, restore the PostIncLoops set so the caller
1331  // can ensure that IVIncrement dominates the current uses.
1332  PostIncLoops = SavedPostIncLoops;
1333 
1334  // Remember this PHI, even in post-inc mode.
1335  InsertedValues.insert(PN);
1336 
1337  return PN;
1338 }
1339 
1340 Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
1341  Type *STy = S->getType();
1342  Type *IntTy = SE.getEffectiveSCEVType(STy);
1343  const Loop *L = S->getLoop();
1344 
1345  // Determine a normalized form of this expression, which is the expression
1346  // before any post-inc adjustment is made.
1347  const SCEVAddRecExpr *Normalized = S;
1348  if (PostIncLoops.count(L)) {
1350  Loops.insert(L);
1351  Normalized = cast<SCEVAddRecExpr>(normalizeForPostIncUse(S, Loops, SE));
1352  }
1353 
1354  // Strip off any non-loop-dominating component from the addrec start.
1355  const SCEV *Start = Normalized->getStart();
1356  const SCEV *PostLoopOffset = nullptr;
1357  if (!SE.properlyDominates(Start, L->getHeader())) {
1358  PostLoopOffset = Start;
1359  Start = SE.getConstant(Normalized->getType(), 0);
1360  Normalized = cast<SCEVAddRecExpr>(
1361  SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE),
1362  Normalized->getLoop(),
1363  Normalized->getNoWrapFlags(SCEV::FlagNW)));
1364  }
1365 
1366  // Strip off any non-loop-dominating component from the addrec step.
1367  const SCEV *Step = Normalized->getStepRecurrence(SE);
1368  const SCEV *PostLoopScale = nullptr;
1369  if (!SE.dominates(Step, L->getHeader())) {
1370  PostLoopScale = Step;
1371  Step = SE.getConstant(Normalized->getType(), 1);
1372  if (!Start->isZero()) {
1373  // The normalization below assumes that Start is constant zero, so if
1374  // it isn't re-associate Start to PostLoopOffset.
1375  assert(!PostLoopOffset && "Start not-null but PostLoopOffset set?");
1376  PostLoopOffset = Start;
1377  Start = SE.getConstant(Normalized->getType(), 0);
1378  }
1379  Normalized =
1380  cast<SCEVAddRecExpr>(SE.getAddRecExpr(
1381  Start, Step, Normalized->getLoop(),
1382  Normalized->getNoWrapFlags(SCEV::FlagNW)));
1383  }
1384 
1385  // Expand the core addrec. If we need post-loop scaling, force it to
1386  // expand to an integer type to avoid the need for additional casting.
1387  Type *ExpandTy = PostLoopScale ? IntTy : STy;
1388  // We can't use a pointer type for the addrec if the pointer type is
1389  // non-integral.
1390  Type *AddRecPHIExpandTy =
1391  DL.isNonIntegralPointerType(STy) ? Normalized->getType() : ExpandTy;
1392 
1393  // In some cases, we decide to reuse an existing phi node but need to truncate
1394  // it and/or invert the step.
1395  Type *TruncTy = nullptr;
1396  bool InvertStep = false;
1397  PHINode *PN = getAddRecExprPHILiterally(Normalized, L, AddRecPHIExpandTy,
1398  IntTy, TruncTy, InvertStep);
1399 
1400  // Accommodate post-inc mode, if necessary.
1401  Value *Result;
1402  if (!PostIncLoops.count(L))
1403  Result = PN;
1404  else {
1405  // In PostInc mode, use the post-incremented value.
1406  BasicBlock *LatchBlock = L->getLoopLatch();
1407  assert(LatchBlock && "PostInc mode requires a unique loop latch!");
1408  Result = PN->getIncomingValueForBlock(LatchBlock);
1409 
1410  // For an expansion to use the postinc form, the client must call
1411  // expandCodeFor with an InsertPoint that is either outside the PostIncLoop
1412  // or dominated by IVIncInsertPos.
1413  if (isa<Instruction>(Result) &&
1414  !SE.DT.dominates(cast<Instruction>(Result),
1415  &*Builder.GetInsertPoint())) {
1416  // The induction variable's postinc expansion does not dominate this use.
1417  // IVUsers tries to prevent this case, so it is rare. However, it can
1418  // happen when an IVUser outside the loop is not dominated by the latch
1419  // block. Adjusting IVIncInsertPos before expansion begins cannot handle
1420  // all cases. Consider a phi outside whose operand is replaced during
1421  // expansion with the value of the postinc user. Without fundamentally
1422  // changing the way postinc users are tracked, the only remedy is
1423  // inserting an extra IV increment. StepV might fold into PostLoopOffset,
1424  // but hopefully expandCodeFor handles that.
1425  bool useSubtract =
1426  !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
1427  if (useSubtract)
1428  Step = SE.getNegativeSCEV(Step);
1429  Value *StepV;
1430  {
1431  // Expand the step somewhere that dominates the loop header.
1432  SCEVInsertPointGuard Guard(Builder, this);
1433  StepV = expandCodeFor(Step, IntTy, &L->getHeader()->front());
1434  }
1435  Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
1436  }
1437  }
1438 
1439  // We have decided to reuse an induction variable of a dominating loop. Apply
1440  // truncation and/or inversion of the step.
1441  if (TruncTy) {
1442  Type *ResTy = Result->getType();
1443  // Normalize the result type.
1444  if (ResTy != SE.getEffectiveSCEVType(ResTy))
1445  Result = InsertNoopCastOfTo(Result, SE.getEffectiveSCEVType(ResTy));
1446  // Truncate the result.
1447  if (TruncTy != Result->getType()) {
1448  Result = Builder.CreateTrunc(Result, TruncTy);
1449  rememberInstruction(Result);
1450  }
1451  // Invert the result.
1452  if (InvertStep) {
1453  Result = Builder.CreateSub(expandCodeFor(Normalized->getStart(), TruncTy),
1454  Result);
1455  rememberInstruction(Result);
1456  }
1457  }
1458 
1459  // Re-apply any non-loop-dominating scale.
1460  if (PostLoopScale) {
1461  assert(S->isAffine() && "Can't linearly scale non-affine recurrences.");
1462  Result = InsertNoopCastOfTo(Result, IntTy);
1463  Result = Builder.CreateMul(Result,
1464  expandCodeFor(PostLoopScale, IntTy));
1465  rememberInstruction(Result);
1466  }
1467 
1468  // Re-apply any non-loop-dominating offset.
1469  if (PostLoopOffset) {
1470  if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
1471  if (Result->getType()->isIntegerTy()) {
1472  Value *Base = expandCodeFor(PostLoopOffset, ExpandTy);
1473  Result = expandAddToGEP(SE.getUnknown(Result), PTy, IntTy, Base);
1474  } else {
1475  Result = expandAddToGEP(PostLoopOffset, PTy, IntTy, Result);
1476  }
1477  } else {
1478  Result = InsertNoopCastOfTo(Result, IntTy);
1479  Result = Builder.CreateAdd(Result,
1480  expandCodeFor(PostLoopOffset, IntTy));
1481  rememberInstruction(Result);
1482  }
1483  }
1484 
1485  return Result;
1486 }
1487 
1488 Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
1489  if (!CanonicalMode) return expandAddRecExprLiterally(S);
1490 
1491  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1492  const Loop *L = S->getLoop();
1493 
1494  // First check for an existing canonical IV in a suitable type.
1495  PHINode *CanonicalIV = nullptr;
1496  if (PHINode *PN = L->getCanonicalInductionVariable())
1497  if (SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
1498  CanonicalIV = PN;
1499 
1500  // Rewrite an AddRec in terms of the canonical induction variable, if
1501  // its type is more narrow.
1502  if (CanonicalIV &&
1503  SE.getTypeSizeInBits(CanonicalIV->getType()) >
1504  SE.getTypeSizeInBits(Ty)) {
1506  for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i)
1507  NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
1508  Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(),
1510  BasicBlock::iterator NewInsertPt =
1511  findInsertPointAfter(cast<Instruction>(V), Builder.GetInsertBlock());
1512  V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), nullptr,
1513  &*NewInsertPt);
1514  return V;
1515  }
1516 
1517  // {X,+,F} --> X + {0,+,F}
1518  if (!S->getStart()->isZero()) {
1519  SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end());
1520  NewOps[0] = SE.getConstant(Ty, 0);
1521  const SCEV *Rest = SE.getAddRecExpr(NewOps, L,
1523 
1524  // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
1525  // comments on expandAddToGEP for details.
1526  const SCEV *Base = S->getStart();
1527  // Dig into the expression to find the pointer base for a GEP.
1528  const SCEV *ExposedRest = Rest;
1529  ExposePointerBase(Base, ExposedRest, SE);
1530  // If we found a pointer, expand the AddRec with a GEP.
1531  if (PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
1532  // Make sure the Base isn't something exotic, such as a multiplied
1533  // or divided pointer value. In those cases, the result type isn't
1534  // actually a pointer type.
1535  if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
1536  Value *StartV = expand(Base);
1537  assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
1538  return expandAddToGEP(ExposedRest, PTy, Ty, StartV);
1539  }
1540  }
1541 
1542  // Just do a normal add. Pre-expand the operands to suppress folding.
1543  //
1544  // The LHS and RHS values are factored out of the expand call to make the
1545  // output independent of the argument evaluation order.
1546  const SCEV *AddExprLHS = SE.getUnknown(expand(S->getStart()));
1547  const SCEV *AddExprRHS = SE.getUnknown(expand(Rest));
1548  return expand(SE.getAddExpr(AddExprLHS, AddExprRHS));
1549  }
1550 
1551  // If we don't yet have a canonical IV, create one.
1552  if (!CanonicalIV) {
1553  // Create and insert the PHI node for the induction variable in the
1554  // specified loop.
1555  BasicBlock *Header = L->getHeader();
1556  pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
1557  CanonicalIV = PHINode::Create(Ty, std::distance(HPB, HPE), "indvar",
1558  &Header->front());
1559  rememberInstruction(CanonicalIV);
1560 
1561  SmallSet<BasicBlock *, 4> PredSeen;
1562  Constant *One = ConstantInt::get(Ty, 1);
1563  for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
1564  BasicBlock *HP = *HPI;
1565  if (!PredSeen.insert(HP).second) {
1566  // There must be an incoming value for each predecessor, even the
1567  // duplicates!
1568  CanonicalIV->addIncoming(CanonicalIV->getIncomingValueForBlock(HP), HP);
1569  continue;
1570  }
1571 
1572  if (L->contains(HP)) {
1573  // Insert a unit add instruction right before the terminator
1574  // corresponding to the back-edge.
1575  Instruction *Add = BinaryOperator::CreateAdd(CanonicalIV, One,
1576  "indvar.next",
1577  HP->getTerminator());
1578  Add->setDebugLoc(HP->getTerminator()->getDebugLoc());
1579  rememberInstruction(Add);
1580  CanonicalIV->addIncoming(Add, HP);
1581  } else {
1582  CanonicalIV->addIncoming(Constant::getNullValue(Ty), HP);
1583  }
1584  }
1585  }
1586 
1587  // {0,+,1} --> Insert a canonical induction variable into the loop!
1588  if (S->isAffine() && S->getOperand(1)->isOne()) {
1589  assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
1590  "IVs with types different from the canonical IV should "
1591  "already have been handled!");
1592  return CanonicalIV;
1593  }
1594 
1595  // {0,+,F} --> {0,+,1} * F
1596 
1597  // If this is a simple linear addrec, emit it now as a special case.
1598  if (S->isAffine()) // {0,+,F} --> i*F
1599  return
1600  expand(SE.getTruncateOrNoop(
1601  SE.getMulExpr(SE.getUnknown(CanonicalIV),
1602  SE.getNoopOrAnyExtend(S->getOperand(1),
1603  CanonicalIV->getType())),
1604  Ty));
1605 
1606  // If this is a chain of recurrences, turn it into a closed form, using the
1607  // folders, then expandCodeFor the closed form. This allows the folders to
1608  // simplify the expression without having to build a bunch of special code
1609  // into this folder.
1610  const SCEV *IH = SE.getUnknown(CanonicalIV); // Get I as a "symbolic" SCEV.
1611 
1612  // Promote S up to the canonical IV type, if the cast is foldable.
1613  const SCEV *NewS = S;
1614  const SCEV *Ext = SE.getNoopOrAnyExtend(S, CanonicalIV->getType());
1615  if (isa<SCEVAddRecExpr>(Ext))
1616  NewS = Ext;
1617 
1618  const SCEV *V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE);
1619  //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
1620 
1621  // Truncate the result down to the original type, if needed.
1622  const SCEV *T = SE.getTruncateOrNoop(V, Ty);
1623  return expand(T);
1624 }
1625 
1626 Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
1627  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1628  Value *V = expandCodeFor(S->getOperand(),
1629  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1630  Value *I = Builder.CreateTrunc(V, Ty);
1631  rememberInstruction(I);
1632  return I;
1633 }
1634 
1635 Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
1636  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1637  Value *V = expandCodeFor(S->getOperand(),
1638  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1639  Value *I = Builder.CreateZExt(V, Ty);
1640  rememberInstruction(I);
1641  return I;
1642 }
1643 
1644 Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
1645  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1646  Value *V = expandCodeFor(S->getOperand(),
1647  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1648  Value *I = Builder.CreateSExt(V, Ty);
1649  rememberInstruction(I);
1650  return I;
1651 }
1652 
1653 Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
1654  Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
1655  Type *Ty = LHS->getType();
1656  for (int i = S->getNumOperands()-2; i >= 0; --i) {
1657  // In the case of mixed integer and pointer types, do the
1658  // rest of the comparisons as integer.
1659  Type *OpTy = S->getOperand(i)->getType();
1660  if (OpTy->isIntegerTy() != Ty->isIntegerTy()) {
1661  Ty = SE.getEffectiveSCEVType(Ty);
1662  LHS = InsertNoopCastOfTo(LHS, Ty);
1663  }
1664  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1665  Value *ICmp = Builder.CreateICmpSGT(LHS, RHS);
1666  rememberInstruction(ICmp);
1667  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
1668  rememberInstruction(Sel);
1669  LHS = Sel;
1670  }
1671  // In the case of mixed integer and pointer types, cast the
1672  // final result back to the pointer type.
1673  if (LHS->getType() != S->getType())
1674  LHS = InsertNoopCastOfTo(LHS, S->getType());
1675  return LHS;
1676 }
1677 
1678 Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
1679  Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
1680  Type *Ty = LHS->getType();
1681  for (int i = S->getNumOperands()-2; i >= 0; --i) {
1682  // In the case of mixed integer and pointer types, do the
1683  // rest of the comparisons as integer.
1684  Type *OpTy = S->getOperand(i)->getType();
1685  if (OpTy->isIntegerTy() != Ty->isIntegerTy()) {
1686  Ty = SE.getEffectiveSCEVType(Ty);
1687  LHS = InsertNoopCastOfTo(LHS, Ty);
1688  }
1689  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1690  Value *ICmp = Builder.CreateICmpUGT(LHS, RHS);
1691  rememberInstruction(ICmp);
1692  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
1693  rememberInstruction(Sel);
1694  LHS = Sel;
1695  }
1696  // In the case of mixed integer and pointer types, cast the
1697  // final result back to the pointer type.
1698  if (LHS->getType() != S->getType())
1699  LHS = InsertNoopCastOfTo(LHS, S->getType());
1700  return LHS;
1701 }
1702 
1703 Value *SCEVExpander::visitSMinExpr(const SCEVSMinExpr *S) {
1704  Value *LHS = expand(S->getOperand(S->getNumOperands() - 1));
1705  Type *Ty = LHS->getType();
1706  for (int i = S->getNumOperands() - 2; i >= 0; --i) {
1707  // In the case of mixed integer and pointer types, do the
1708  // rest of the comparisons as integer.
1709  Type *OpTy = S->getOperand(i)->getType();
1710  if (OpTy->isIntegerTy() != Ty->isIntegerTy()) {
1711  Ty = SE.getEffectiveSCEVType(Ty);
1712  LHS = InsertNoopCastOfTo(LHS, Ty);
1713  }
1714  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1715  Value *ICmp = Builder.CreateICmpSLT(LHS, RHS);
1716  rememberInstruction(ICmp);
1717  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smin");
1718  rememberInstruction(Sel);
1719  LHS = Sel;
1720  }
1721  // In the case of mixed integer and pointer types, cast the
1722  // final result back to the pointer type.
1723  if (LHS->getType() != S->getType())
1724  LHS = InsertNoopCastOfTo(LHS, S->getType());
1725  return LHS;
1726 }
1727 
1728 Value *SCEVExpander::visitUMinExpr(const SCEVUMinExpr *S) {
1729  Value *LHS = expand(S->getOperand(S->getNumOperands() - 1));
1730  Type *Ty = LHS->getType();
1731  for (int i = S->getNumOperands() - 2; i >= 0; --i) {
1732  // In the case of mixed integer and pointer types, do the
1733  // rest of the comparisons as integer.
1734  Type *OpTy = S->getOperand(i)->getType();
1735  if (OpTy->isIntegerTy() != Ty->isIntegerTy()) {
1736  Ty = SE.getEffectiveSCEVType(Ty);
1737  LHS = InsertNoopCastOfTo(LHS, Ty);
1738  }
1739  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1740  Value *ICmp = Builder.CreateICmpULT(LHS, RHS);
1741  rememberInstruction(ICmp);
1742  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umin");
1743  rememberInstruction(Sel);
1744  LHS = Sel;
1745  }
1746  // In the case of mixed integer and pointer types, cast the
1747  // final result back to the pointer type.
1748  if (LHS->getType() != S->getType())
1749  LHS = InsertNoopCastOfTo(LHS, S->getType());
1750  return LHS;
1751 }
1752 
1754  Instruction *IP) {
1755  setInsertPoint(IP);
1756  return expandCodeFor(SH, Ty);
1757 }
1758 
1760  // Expand the code for this SCEV.
1761  Value *V = expand(SH);
1762  if (Ty) {
1763  assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) &&
1764  "non-trivial casts should be done with the SCEVs directly!");
1765  V = InsertNoopCastOfTo(V, Ty);
1766  }
1767  return V;
1768 }
1769 
1770 ScalarEvolution::ValueOffsetPair
1771 SCEVExpander::FindValueInExprValueMap(const SCEV *S,
1772  const Instruction *InsertPt) {
1773  SetVector<ScalarEvolution::ValueOffsetPair> *Set = SE.getSCEVValues(S);
1774  // If the expansion is not in CanonicalMode, and the SCEV contains any
1775  // sub scAddRecExpr type SCEV, it is required to expand the SCEV literally.
1776  if (CanonicalMode || !SE.containsAddRecurrence(S)) {
1777  // If S is scConstant, it may be worse to reuse an existing Value.
1778  if (S->getSCEVType() != scConstant && Set) {
1779  // Choose a Value from the set which dominates the insertPt.
1780  // insertPt should be inside the Value's parent loop so as not to break
1781  // the LCSSA form.
1782  for (auto const &VOPair : *Set) {
1783  Value *V = VOPair.first;
1784  ConstantInt *Offset = VOPair.second;
1785  Instruction *EntInst = nullptr;
1786  if (V && isa<Instruction>(V) && (EntInst = cast<Instruction>(V)) &&
1787  S->getType() == V->getType() &&
1788  EntInst->getFunction() == InsertPt->getFunction() &&
1789  SE.DT.dominates(EntInst, InsertPt) &&
1790  (SE.LI.getLoopFor(EntInst->getParent()) == nullptr ||
1791  SE.LI.getLoopFor(EntInst->getParent())->contains(InsertPt)))
1792  return {V, Offset};
1793  }
1794  }
1795  }
1796  return {nullptr, nullptr};
1797 }
1798 
1799 // The expansion of SCEV will either reuse a previous Value in ExprValueMap,
1800 // or expand the SCEV literally. Specifically, if the expansion is in LSRMode,
1801 // and the SCEV contains any sub scAddRecExpr type SCEV, it will be expanded
1802 // literally, to prevent LSR's transformed SCEV from being reverted. Otherwise,
1803 // the expansion will try to reuse Value from ExprValueMap, and only when it
1804 // fails, expand the SCEV literally.
1805 Value *SCEVExpander::expand(const SCEV *S) {
1806  // Compute an insertion point for this SCEV object. Hoist the instructions
1807  // as far out in the loop nest as possible.
1808  Instruction *InsertPt = &*Builder.GetInsertPoint();
1809 
1810  // We can move insertion point only if there is no div or rem operations
1811  // otherwise we are risky to move it over the check for zero denominator.
1812  auto SafeToHoist = [](const SCEV *S) {
1813  return !SCEVExprContains(S, [](const SCEV *S) {
1814  if (const auto *D = dyn_cast<SCEVUDivExpr>(S)) {
1815  if (const auto *SC = dyn_cast<SCEVConstant>(D->getRHS()))
1816  // Division by non-zero constants can be hoisted.
1817  return SC->getValue()->isZero();
1818  // All other divisions should not be moved as they may be
1819  // divisions by zero and should be kept within the
1820  // conditions of the surrounding loops that guard their
1821  // execution (see PR35406).
1822  return true;
1823  }
1824  return false;
1825  });
1826  };
1827  if (SafeToHoist(S)) {
1828  for (Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock());;
1829  L = L->getParentLoop()) {
1830  if (SE.isLoopInvariant(S, L)) {
1831  if (!L) break;
1832  if (BasicBlock *Preheader = L->getLoopPreheader())
1833  InsertPt = Preheader->getTerminator();
1834  else
1835  // LSR sets the insertion point for AddRec start/step values to the
1836  // block start to simplify value reuse, even though it's an invalid
1837  // position. SCEVExpander must correct for this in all cases.
1838  InsertPt = &*L->getHeader()->getFirstInsertionPt();
1839  } else {
1840  // If the SCEV is computable at this level, insert it into the header
1841  // after the PHIs (and after any other instructions that we've inserted
1842  // there) so that it is guaranteed to dominate any user inside the loop.
1843  if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
1844  InsertPt = &*L->getHeader()->getFirstInsertionPt();
1845  while (InsertPt->getIterator() != Builder.GetInsertPoint() &&
1846  (isInsertedInstruction(InsertPt) ||
1847  isa<DbgInfoIntrinsic>(InsertPt)))
1848  InsertPt = &*std::next(InsertPt->getIterator());
1849  break;
1850  }
1851  }
1852  }
1853 
1854  // IndVarSimplify sometimes sets the insertion point at the block start, even
1855  // when there are PHIs at that point. We must correct for this.
1856  if (isa<PHINode>(*InsertPt))
1857  InsertPt = &*InsertPt->getParent()->getFirstInsertionPt();
1858 
1859  // Check to see if we already expanded this here.
1860  auto I = InsertedExpressions.find(std::make_pair(S, InsertPt));
1861  if (I != InsertedExpressions.end())
1862  return I->second;
1863 
1864  SCEVInsertPointGuard Guard(Builder, this);
1865  Builder.SetInsertPoint(InsertPt);
1866 
1867  // Expand the expression into instructions.
1868  ScalarEvolution::ValueOffsetPair VO = FindValueInExprValueMap(S, InsertPt);
1869  Value *V = VO.first;
1870 
1871  if (!V)
1872  V = visit(S);
1873  else if (VO.second) {
1874  if (PointerType *Vty = dyn_cast<PointerType>(V->getType())) {
1875  Type *Ety = Vty->getPointerElementType();
1876  int64_t Offset = VO.second->getSExtValue();
1877  int64_t ESize = SE.getTypeSizeInBits(Ety);
1878  if ((Offset * 8) % ESize == 0) {
1879  ConstantInt *Idx =
1880  ConstantInt::getSigned(VO.second->getType(), -(Offset * 8) / ESize);
1881  V = Builder.CreateGEP(Ety, V, Idx, "scevgep");
1882  } else {
1883  ConstantInt *Idx =
1884  ConstantInt::getSigned(VO.second->getType(), -Offset);
1885  unsigned AS = Vty->getAddressSpace();
1886  V = Builder.CreateBitCast(V, Type::getInt8PtrTy(SE.getContext(), AS));
1887  V = Builder.CreateGEP(Type::getInt8Ty(SE.getContext()), V, Idx,
1888  "uglygep");
1889  V = Builder.CreateBitCast(V, Vty);
1890  }
1891  } else {
1892  V = Builder.CreateSub(V, VO.second);
1893  }
1894  }
1895  // Remember the expanded value for this SCEV at this location.
1896  //
1897  // This is independent of PostIncLoops. The mapped value simply materializes
1898  // the expression at this insertion point. If the mapped value happened to be
1899  // a postinc expansion, it could be reused by a non-postinc user, but only if
1900  // its insertion point was already at the head of the loop.
1901  InsertedExpressions[std::make_pair(S, InsertPt)] = V;
1902  return V;
1903 }
1904 
1905 void SCEVExpander::rememberInstruction(Value *I) {
1906  if (!PostIncLoops.empty())
1907  InsertedPostIncValues.insert(I);
1908  else
1909  InsertedValues.insert(I);
1910 }
1911 
1912 /// getOrInsertCanonicalInductionVariable - This method returns the
1913 /// canonical induction variable of the specified type for the specified
1914 /// loop (inserting one if there is none). A canonical induction variable
1915 /// starts at zero and steps by one on each iteration.
1916 PHINode *
1918  Type *Ty) {
1919  assert(Ty->isIntegerTy() && "Can only insert integer induction variables!");
1920 
1921  // Build a SCEV for {0,+,1}<L>.
1922  // Conservatively use FlagAnyWrap for now.
1923  const SCEV *H = SE.getAddRecExpr(SE.getConstant(Ty, 0),
1924  SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
1925 
1926  // Emit code for it.
1927  SCEVInsertPointGuard Guard(Builder, this);
1928  PHINode *V =
1929  cast<PHINode>(expandCodeFor(H, nullptr, &L->getHeader()->front()));
1930 
1931  return V;
1932 }
1933 
1934 /// replaceCongruentIVs - Check for congruent phis in this loop header and
1935 /// replace them with their most canonical representative. Return the number of
1936 /// phis eliminated.
1937 ///
1938 /// This does not depend on any SCEVExpander state but should be used in
1939 /// the same context that SCEVExpander is used.
1940 unsigned
1943  const TargetTransformInfo *TTI) {
1944  // Find integer phis in order of increasing width.
1946  for (PHINode &PN : L->getHeader()->phis())
1947  Phis.push_back(&PN);
1948 
1949  if (TTI)
1950  llvm::sort(Phis, [](Value *LHS, Value *RHS) {
1951  // Put pointers at the back and make sure pointer < pointer = false.
1952  if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
1953  return RHS->getType()->isIntegerTy() && !LHS->getType()->isIntegerTy();
1954  return RHS->getType()->getPrimitiveSizeInBits() <
1955  LHS->getType()->getPrimitiveSizeInBits();
1956  });
1957 
1958  unsigned NumElim = 0;
1960  // Process phis from wide to narrow. Map wide phis to their truncation
1961  // so narrow phis can reuse them.
1962  for (PHINode *Phi : Phis) {
1963  auto SimplifyPHINode = [&](PHINode *PN) -> Value * {
1964  if (Value *V = SimplifyInstruction(PN, {DL, &SE.TLI, &SE.DT, &SE.AC}))
1965  return V;
1966  if (!SE.isSCEVable(PN->getType()))
1967  return nullptr;
1968  auto *Const = dyn_cast<SCEVConstant>(SE.getSCEV(PN));
1969  if (!Const)
1970  return nullptr;
1971  return Const->getValue();
1972  };
1973 
1974  // Fold constant phis. They may be congruent to other constant phis and
1975  // would confuse the logic below that expects proper IVs.
1976  if (Value *V = SimplifyPHINode(Phi)) {
1977  if (V->getType() != Phi->getType())
1978  continue;
1979  Phi->replaceAllUsesWith(V);
1980  DeadInsts.emplace_back(Phi);
1981  ++NumElim;
1983  << "INDVARS: Eliminated constant iv: " << *Phi << '\n');
1984  continue;
1985  }
1986 
1987  if (!SE.isSCEVable(Phi->getType()))
1988  continue;
1989 
1990  PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
1991  if (!OrigPhiRef) {
1992  OrigPhiRef = Phi;
1993  if (Phi->getType()->isIntegerTy() && TTI &&
1994  TTI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
1995  // This phi can be freely truncated to the narrowest phi type. Map the
1996  // truncated expression to it so it will be reused for narrow types.
1997  const SCEV *TruncExpr =
1998  SE.getTruncateExpr(SE.getSCEV(Phi), Phis.back()->getType());
1999  ExprToIVMap[TruncExpr] = Phi;
2000  }
2001  continue;
2002  }
2003 
2004  // Replacing a pointer phi with an integer phi or vice-versa doesn't make
2005  // sense.
2006  if (OrigPhiRef->getType()->isPointerTy() != Phi->getType()->isPointerTy())
2007  continue;
2008 
2009  if (BasicBlock *LatchBlock = L->getLoopLatch()) {
2010  Instruction *OrigInc = dyn_cast<Instruction>(
2011  OrigPhiRef->getIncomingValueForBlock(LatchBlock));
2012  Instruction *IsomorphicInc =
2013  dyn_cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
2014 
2015  if (OrigInc && IsomorphicInc) {
2016  // If this phi has the same width but is more canonical, replace the
2017  // original with it. As part of the "more canonical" determination,
2018  // respect a prior decision to use an IV chain.
2019  if (OrigPhiRef->getType() == Phi->getType() &&
2020  !(ChainedPhis.count(Phi) ||
2021  isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)) &&
2022  (ChainedPhis.count(Phi) ||
2023  isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
2024  std::swap(OrigPhiRef, Phi);
2025  std::swap(OrigInc, IsomorphicInc);
2026  }
2027  // Replacing the congruent phi is sufficient because acyclic
2028  // redundancy elimination, CSE/GVN, should handle the
2029  // rest. However, once SCEV proves that a phi is congruent,
2030  // it's often the head of an IV user cycle that is isomorphic
2031  // with the original phi. It's worth eagerly cleaning up the
2032  // common case of a single IV increment so that DeleteDeadPHIs
2033  // can remove cycles that had postinc uses.
2034  const SCEV *TruncExpr =
2035  SE.getTruncateOrNoop(SE.getSCEV(OrigInc), IsomorphicInc->getType());
2036  if (OrigInc != IsomorphicInc &&
2037  TruncExpr == SE.getSCEV(IsomorphicInc) &&
2038  SE.LI.replacementPreservesLCSSAForm(IsomorphicInc, OrigInc) &&
2039  hoistIVInc(OrigInc, IsomorphicInc)) {
2041  dbgs() << "INDVARS: Eliminated congruent iv.inc: "
2042  << *IsomorphicInc << '\n');
2043  Value *NewInc = OrigInc;
2044  if (OrigInc->getType() != IsomorphicInc->getType()) {
2045  Instruction *IP = nullptr;
2046  if (PHINode *PN = dyn_cast<PHINode>(OrigInc))
2047  IP = &*PN->getParent()->getFirstInsertionPt();
2048  else
2049  IP = OrigInc->getNextNode();
2050 
2051  IRBuilder<> Builder(IP);
2052  Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
2053  NewInc = Builder.CreateTruncOrBitCast(
2054  OrigInc, IsomorphicInc->getType(), IVName);
2055  }
2056  IsomorphicInc->replaceAllUsesWith(NewInc);
2057  DeadInsts.emplace_back(IsomorphicInc);
2058  }
2059  }
2060  }
2061  DEBUG_WITH_TYPE(DebugType, dbgs() << "INDVARS: Eliminated congruent iv: "
2062  << *Phi << '\n');
2063  ++NumElim;
2064  Value *NewIV = OrigPhiRef;
2065  if (OrigPhiRef->getType() != Phi->getType()) {
2066  IRBuilder<> Builder(&*L->getHeader()->getFirstInsertionPt());
2067  Builder.SetCurrentDebugLocation(Phi->getDebugLoc());
2068  NewIV = Builder.CreateTruncOrBitCast(OrigPhiRef, Phi->getType(), IVName);
2069  }
2070  Phi->replaceAllUsesWith(NewIV);
2071  DeadInsts.emplace_back(Phi);
2072  }
2073  return NumElim;
2074 }
2075 
2077  const Instruction *At, Loop *L) {
2079  getRelatedExistingExpansion(S, At, L);
2080  if (VO && VO.getValue().second == nullptr)
2081  return VO.getValue().first;
2082  return nullptr;
2083 }
2084 
2087  Loop *L) {
2088  using namespace llvm::PatternMatch;
2089 
2090  SmallVector<BasicBlock *, 4> ExitingBlocks;
2091  L->getExitingBlocks(ExitingBlocks);
2092 
2093  // Look for suitable value in simple conditions at the loop exits.
2094  for (BasicBlock *BB : ExitingBlocks) {
2095  ICmpInst::Predicate Pred;
2096  Instruction *LHS, *RHS;
2097  BasicBlock *TrueBB, *FalseBB;
2098 
2099  if (!match(BB->getTerminator(),
2100  m_Br(m_ICmp(Pred, m_Instruction(LHS), m_Instruction(RHS)),
2101  TrueBB, FalseBB)))
2102  continue;
2103 
2104  if (SE.getSCEV(LHS) == S && SE.DT.dominates(LHS, At))
2105  return ScalarEvolution::ValueOffsetPair(LHS, nullptr);
2106 
2107  if (SE.getSCEV(RHS) == S && SE.DT.dominates(RHS, At))
2108  return ScalarEvolution::ValueOffsetPair(RHS, nullptr);
2109  }
2110 
2111  // Use expand's logic which is used for reusing a previous Value in
2112  // ExprValueMap.
2113  ScalarEvolution::ValueOffsetPair VO = FindValueInExprValueMap(S, At);
2114  if (VO.first)
2115  return VO;
2116 
2117  // There is potential to make this significantly smarter, but this simple
2118  // heuristic already gets some interesting cases.
2119 
2120  // Can not find suitable value.
2121  return None;
2122 }
2123 
2124 bool SCEVExpander::isHighCostExpansionHelper(
2125  const SCEV *S, Loop *L, const Instruction *At,
2126  SmallPtrSetImpl<const SCEV *> &Processed) {
2127 
2128  // If we can find an existing value for this scev available at the point "At"
2129  // then consider the expression cheap.
2130  if (At && getRelatedExistingExpansion(S, At, L))
2131  return false;
2132 
2133  // Zero/One operand expressions
2134  switch (S->getSCEVType()) {
2135  case scUnknown:
2136  case scConstant:
2137  return false;
2138  case scTruncate:
2139  return isHighCostExpansionHelper(cast<SCEVTruncateExpr>(S)->getOperand(),
2140  L, At, Processed);
2141  case scZeroExtend:
2142  return isHighCostExpansionHelper(cast<SCEVZeroExtendExpr>(S)->getOperand(),
2143  L, At, Processed);
2144  case scSignExtend:
2145  return isHighCostExpansionHelper(cast<SCEVSignExtendExpr>(S)->getOperand(),
2146  L, At, Processed);
2147  }
2148 
2149  if (!Processed.insert(S).second)
2150  return false;
2151 
2152  if (auto *UDivExpr = dyn_cast<SCEVUDivExpr>(S)) {
2153  // If the divisor is a power of two and the SCEV type fits in a native
2154  // integer (and the LHS not expensive), consider the division cheap
2155  // irrespective of whether it occurs in the user code since it can be
2156  // lowered into a right shift.
2157  if (auto *SC = dyn_cast<SCEVConstant>(UDivExpr->getRHS()))
2158  if (SC->getAPInt().isPowerOf2()) {
2159  if (isHighCostExpansionHelper(UDivExpr->getLHS(), L, At, Processed))
2160  return true;
2161  const DataLayout &DL =
2163  unsigned Width = cast<IntegerType>(UDivExpr->getType())->getBitWidth();
2164  return DL.isIllegalInteger(Width);
2165  }
2166 
2167  // UDivExpr is very likely a UDiv that ScalarEvolution's HowFarToZero or
2168  // HowManyLessThans produced to compute a precise expression, rather than a
2169  // UDiv from the user's code. If we can't find a UDiv in the code with some
2170  // simple searching, assume the former consider UDivExpr expensive to
2171  // compute.
2172  BasicBlock *ExitingBB = L->getExitingBlock();
2173  if (!ExitingBB)
2174  return true;
2175 
2176  // At the beginning of this function we already tried to find existing value
2177  // for plain 'S'. Now try to lookup 'S + 1' since it is common pattern
2178  // involving division. This is just a simple search heuristic.
2179  if (!At)
2180  At = &ExitingBB->back();
2181  if (!getRelatedExistingExpansion(
2182  SE.getAddExpr(S, SE.getConstant(S->getType(), 1)), At, L))
2183  return true;
2184  }
2185 
2186  // HowManyLessThans uses a Max expression whenever the loop is not guarded by
2187  // the exit condition.
2188  if (isa<SCEVMinMaxExpr>(S))
2189  return true;
2190 
2191  // Recurse past nary expressions, which commonly occur in the
2192  // BackedgeTakenCount. They may already exist in program code, and if not,
2193  // they are not too expensive rematerialize.
2194  if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(S)) {
2195  for (auto *Op : NAry->operands())
2196  if (isHighCostExpansionHelper(Op, L, At, Processed))
2197  return true;
2198  }
2199 
2200  // If we haven't recognized an expensive SCEV pattern, assume it's an
2201  // expression produced by program code.
2202  return false;
2203 }
2204 
2206  Instruction *IP) {
2207  assert(IP);
2208  switch (Pred->getKind()) {
2210  return expandUnionPredicate(cast<SCEVUnionPredicate>(Pred), IP);
2212  return expandEqualPredicate(cast<SCEVEqualPredicate>(Pred), IP);
2213  case SCEVPredicate::P_Wrap: {
2214  auto *AddRecPred = cast<SCEVWrapPredicate>(Pred);
2215  return expandWrapPredicate(AddRecPred, IP);
2216  }
2217  }
2218  llvm_unreachable("Unknown SCEV predicate type");
2219 }
2220 
2222  Instruction *IP) {
2223  Value *Expr0 = expandCodeFor(Pred->getLHS(), Pred->getLHS()->getType(), IP);
2224  Value *Expr1 = expandCodeFor(Pred->getRHS(), Pred->getRHS()->getType(), IP);
2225 
2226  Builder.SetInsertPoint(IP);
2227  auto *I = Builder.CreateICmpNE(Expr0, Expr1, "ident.check");
2228  return I;
2229 }
2230 
2232  Instruction *Loc, bool Signed) {
2233  assert(AR->isAffine() && "Cannot generate RT check for "
2234  "non-affine expression");
2235 
2236  SCEVUnionPredicate Pred;
2237  const SCEV *ExitCount =
2238  SE.getPredicatedBackedgeTakenCount(AR->getLoop(), Pred);
2239 
2240  assert(ExitCount != SE.getCouldNotCompute() && "Invalid loop count");
2241 
2242  const SCEV *Step = AR->getStepRecurrence(SE);
2243  const SCEV *Start = AR->getStart();
2244 
2245  Type *ARTy = AR->getType();
2246  unsigned SrcBits = SE.getTypeSizeInBits(ExitCount->getType());
2247  unsigned DstBits = SE.getTypeSizeInBits(ARTy);
2248 
2249  // The expression {Start,+,Step} has nusw/nssw if
2250  // Step < 0, Start - |Step| * Backedge <= Start
2251  // Step >= 0, Start + |Step| * Backedge > Start
2252  // and |Step| * Backedge doesn't unsigned overflow.
2253 
2254  IntegerType *CountTy = IntegerType::get(Loc->getContext(), SrcBits);
2255  Builder.SetInsertPoint(Loc);
2256  Value *TripCountVal = expandCodeFor(ExitCount, CountTy, Loc);
2257 
2258  IntegerType *Ty =
2259  IntegerType::get(Loc->getContext(), SE.getTypeSizeInBits(ARTy));
2260  Type *ARExpandTy = DL.isNonIntegralPointerType(ARTy) ? ARTy : Ty;
2261 
2262  Value *StepValue = expandCodeFor(Step, Ty, Loc);
2263  Value *NegStepValue = expandCodeFor(SE.getNegativeSCEV(Step), Ty, Loc);
2264  Value *StartValue = expandCodeFor(Start, ARExpandTy, Loc);
2265 
2266  ConstantInt *Zero =
2268 
2269  Builder.SetInsertPoint(Loc);
2270  // Compute |Step|
2271  Value *StepCompare = Builder.CreateICmp(ICmpInst::ICMP_SLT, StepValue, Zero);
2272  Value *AbsStep = Builder.CreateSelect(StepCompare, NegStepValue, StepValue);
2273 
2274  // Get the backedge taken count and truncate or extended to the AR type.
2275  Value *TruncTripCount = Builder.CreateZExtOrTrunc(TripCountVal, Ty);
2276  auto *MulF = Intrinsic::getDeclaration(Loc->getModule(),
2277  Intrinsic::umul_with_overflow, Ty);
2278 
2279  // Compute |Step| * Backedge
2280  CallInst *Mul = Builder.CreateCall(MulF, {AbsStep, TruncTripCount}, "mul");
2281  Value *MulV = Builder.CreateExtractValue(Mul, 0, "mul.result");
2282  Value *OfMul = Builder.CreateExtractValue(Mul, 1, "mul.overflow");
2283 
2284  // Compute:
2285  // Start + |Step| * Backedge < Start
2286  // Start - |Step| * Backedge > Start
2287  Value *Add = nullptr, *Sub = nullptr;
2288  if (PointerType *ARPtrTy = dyn_cast<PointerType>(ARExpandTy)) {
2289  const SCEV *MulS = SE.getSCEV(MulV);
2290  const SCEV *NegMulS = SE.getNegativeSCEV(MulS);
2291  Add = Builder.CreateBitCast(expandAddToGEP(MulS, ARPtrTy, Ty, StartValue),
2292  ARPtrTy);
2293  Sub = Builder.CreateBitCast(
2294  expandAddToGEP(NegMulS, ARPtrTy, Ty, StartValue), ARPtrTy);
2295  } else {
2296  Add = Builder.CreateAdd(StartValue, MulV);
2297  Sub = Builder.CreateSub(StartValue, MulV);
2298  }
2299 
2300  Value *EndCompareGT = Builder.CreateICmp(
2301  Signed ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT, Sub, StartValue);
2302 
2303  Value *EndCompareLT = Builder.CreateICmp(
2304  Signed ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT, Add, StartValue);
2305 
2306  // Select the answer based on the sign of Step.
2307  Value *EndCheck =
2308  Builder.CreateSelect(StepCompare, EndCompareGT, EndCompareLT);
2309 
2310  // If the backedge taken count type is larger than the AR type,
2311  // check that we don't drop any bits by truncating it. If we are
2312  // dropping bits, then we have overflow (unless the step is zero).
2313  if (SE.getTypeSizeInBits(CountTy) > SE.getTypeSizeInBits(Ty)) {
2314  auto MaxVal = APInt::getMaxValue(DstBits).zext(SrcBits);
2315  auto *BackedgeCheck =
2316  Builder.CreateICmp(ICmpInst::ICMP_UGT, TripCountVal,
2317  ConstantInt::get(Loc->getContext(), MaxVal));
2318  BackedgeCheck = Builder.CreateAnd(
2319  BackedgeCheck, Builder.CreateICmp(ICmpInst::ICMP_NE, StepValue, Zero));
2320 
2321  EndCheck = Builder.CreateOr(EndCheck, BackedgeCheck);
2322  }
2323 
2324  EndCheck = Builder.CreateOr(EndCheck, OfMul);
2325  return EndCheck;
2326 }
2327 
2329  Instruction *IP) {
2330  const auto *A = cast<SCEVAddRecExpr>(Pred->getExpr());
2331  Value *NSSWCheck = nullptr, *NUSWCheck = nullptr;
2332 
2333  // Add a check for NUSW
2335  NUSWCheck = generateOverflowCheck(A, IP, false);
2336 
2337  // Add a check for NSSW
2339  NSSWCheck = generateOverflowCheck(A, IP, true);
2340 
2341  if (NUSWCheck && NSSWCheck)
2342  return Builder.CreateOr(NUSWCheck, NSSWCheck);
2343 
2344  if (NUSWCheck)
2345  return NUSWCheck;
2346 
2347  if (NSSWCheck)
2348  return NSSWCheck;
2349 
2350  return ConstantInt::getFalse(IP->getContext());
2351 }
2352 
2354  Instruction *IP) {
2355  auto *BoolType = IntegerType::get(IP->getContext(), 1);
2356  Value *Check = ConstantInt::getNullValue(BoolType);
2357 
2358  // Loop over all checks in this set.
2359  for (auto Pred : Union->getPredicates()) {
2360  auto *NextCheck = expandCodeForPredicate(Pred, IP);
2361  Builder.SetInsertPoint(IP);
2362  Check = Builder.CreateOr(Check, NextCheck);
2363  }
2364 
2365  return Check;
2366 }
2367 
2368 namespace {
2369 // Search for a SCEV subexpression that is not safe to expand. Any expression
2370 // that may expand to a !isSafeToSpeculativelyExecute value is unsafe, namely
2371 // UDiv expressions. We don't know if the UDiv is derived from an IR divide
2372 // instruction, but the important thing is that we prove the denominator is
2373 // nonzero before expansion.
2374 //
2375 // IVUsers already checks that IV-derived expressions are safe. So this check is
2376 // only needed when the expression includes some subexpression that is not IV
2377 // derived.
2378 //
2379 // Currently, we only allow division by a nonzero constant here. If this is
2380 // inadequate, we could easily allow division by SCEVUnknown by using
2381 // ValueTracking to check isKnownNonZero().
2382 //
2383 // We cannot generally expand recurrences unless the step dominates the loop
2384 // header. The expander handles the special case of affine recurrences by
2385 // scaling the recurrence outside the loop, but this technique isn't generally
2386 // applicable. Expanding a nested recurrence outside a loop requires computing
2387 // binomial coefficients. This could be done, but the recurrence has to be in a
2388 // perfectly reduced form, which can't be guaranteed.
2389 struct SCEVFindUnsafe {
2390  ScalarEvolution &SE;
2391  bool IsUnsafe;
2392 
2393  SCEVFindUnsafe(ScalarEvolution &se): SE(se), IsUnsafe(false) {}
2394 
2395  bool follow(const SCEV *S) {
2396  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
2397  const SCEVConstant *SC = dyn_cast<SCEVConstant>(D->getRHS());
2398  if (!SC || SC->getValue()->isZero()) {
2399  IsUnsafe = true;
2400  return false;
2401  }
2402  }
2403  if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
2404  const SCEV *Step = AR->getStepRecurrence(SE);
2405  if (!AR->isAffine() && !SE.dominates(Step, AR->getLoop()->getHeader())) {
2406  IsUnsafe = true;
2407  return false;
2408  }
2409  }
2410  return true;
2411  }
2412  bool isDone() const { return IsUnsafe; }
2413 };
2414 }
2415 
2416 namespace llvm {
2417 bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE) {
2418  SCEVFindUnsafe Search(SE);
2419  visitAll(S, Search);
2420  return !Search.IsUnsafe;
2421 }
2422 
2423 bool isSafeToExpandAt(const SCEV *S, const Instruction *InsertionPoint,
2424  ScalarEvolution &SE) {
2425  if (!isSafeToExpand(S, SE))
2426  return false;
2427  // We have to prove that the expanded site of S dominates InsertionPoint.
2428  // This is easy when not in the same block, but hard when S is an instruction
2429  // to be expanded somewhere inside the same block as our insertion point.
2430  // What we really need here is something analogous to an OrderedBasicBlock,
2431  // but for the moment, we paper over the problem by handling two common and
2432  // cheap to check cases.
2433  if (SE.properlyDominates(S, InsertionPoint->getParent()))
2434  return true;
2435  if (SE.dominates(S, InsertionPoint->getParent())) {
2436  if (InsertionPoint->getParent()->getTerminator() == InsertionPoint)
2437  return true;
2438  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S))
2439  for (const Value *V : InsertionPoint->operand_values())
2440  if (V == U->getValue())
2441  return true;
2442  }
2443  return false;
2444 }
2445 }
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:23
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:603
reference emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:641
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
static IntegerType * getInt1Ty(LLVMContext &C)
Definition: Type.cpp:172
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:211
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:29
NodeTy * getNextNode()
Get the next node, or nullptr for the list tail.
Definition: ilist_node.h:288
const SCEV * getConstant(ConstantInt *V)
This class represents lattice values for constants.
Definition: AllocatorList.h:23
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:1153
bool isSized(SmallPtrSetImpl< Type *> *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:264
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:860
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:160
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:632
unsigned less than
Definition: InstrTypes.h:757
bool properlyDominates(const SCEV *S, const BasicBlock *BB)
Return true if elements that makes up the given SCEV properly dominate the specified basic block...
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:745
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:33
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.
const Instruction * 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:137
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:229
op_iterator op_begin()
Definition: User.h:229
unsigned getElementContainingOffset(uint64_t Offset) const
Given a valid byte offset into the structure, returns the structure index that contains it...
Definition: DataLayout.cpp:83
This is the base class for unary cast operator classes.
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1515
return AArch64::GPR64RegClass contains(Reg)
LLVMContext & getContext() const
Return the LLVMContext in which this type was uniqued.
Definition: Type.h:129
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:274
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:343
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:268
#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:47
Used to lazily calculate structure layout information for a target machine, based on the DataLayout s...
Definition: DataLayout.h:563
Hexagon Hardware Loops
Value * expandCodeForPredicate(const SCEVPredicate *Pred, Instruction *Loc)
Generates a code sequence that evaluates this predicate.
Type * getPointerElementType() const
Definition: Type.h:376
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:369
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:80
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:439
Class to represent struct types.
Definition: DerivedTypes.h:233
A Use represents the edge between a Value definition and its users.
Definition: Use.h:55
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:41
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:196
LLVMContext & getContext() const
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:779
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:105
ConstantInt * getValue() const
A constant value that is initialized with an expression using other constant values.
Definition: Constants.h:888
#define UINT64_MAX
Definition: DataTypes.h:83
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:255
Class to represent array types.
Definition: DerivedTypes.h:403
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:125
op_iterator op_begin() const
void SetCurrentDebugLocation(DebugLoc L)
Set location information used by debugging information.
Definition: IRBuilder.h:156
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:429
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power-of-2.
Definition: PatternMatch.h:407
This class represents a signed minimum selection.
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:291
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
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:1043
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:169
Class to represent pointers.
Definition: DerivedTypes.h:544
#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:216
void setDebugLoc(DebugLoc Loc)
Set the debug location information for this instruction.
Definition: Instruction.h:318
SCEVPredicateKind getKind() const
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
This class represents a binary unsigned division operation.
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This is an important base class in LLVM.
Definition: Constant.h:41
This class represents an unsigned minimum selection.
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:134
bool isPointerTy() const
True if this is an instance of PointerType.
Definition: Type.h:223
const Instruction & front() const
Definition: BasicBlock.h:280
#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:370
bool mayHaveSideEffects() const
Return true if the instruction may have side effects.
Definition: Instruction.h:572
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:112
brc_match< Cond_t > m_Br(const Cond_t &C, BasicBlock *&T, BasicBlock *&F)
op_iterator op_end()
Definition: User.h:231
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:1184
const Instruction & back() const
Definition: BasicBlock.h:282
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:732
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:115
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:572
self_iterator getIterator()
Definition: ilist_node.h:81
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:180
static LLVM_NODISCARD SCEV::NoWrapFlags clearFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OffFlags)
static Expected< BitVector > expand(StringRef S, StringRef Original)
Definition: GlobPattern.cpp:27
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:34
const SCEV * getRHS() const
Returns the right hand side of the equality.
size_t size() const
Definition: SmallVector.h:52
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:219
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:759
This class represents an assumption made using SCEV expressions which can be checked at run-time...
static bool IsIncrementNSW(ScalarEvolution &SE, const SCEVAddRecExpr *AR)
void sort(IteratorTy Start, IteratorTy End)
Definition: STLExtras.h:1107
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:239
void setHasNoSignedWrap(bool b=true)
Set or clear the nsw flag on this instruction, which must be an operator which supports this flag...
bool contains(const LoopT *L) const
Return true if the specified loop is contained within in this loop.
Definition: LoopInfo.h:115
unsigned getSCEVType() const
bool isNonConstantNegative() const
Return true if the specified scev is negated, but not a constant.
unsigned getNumOperands() const
Definition: User.h:191
static PointerType * getInt1PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:215
This is the shared class of boolean and integer constants.
Definition: Constants.h:83
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:837
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:248
Module.h This file contains the declarations for the Module class.
signed less than
Definition: InstrTypes.h:761
uint64_t getSizeInBytes() const
Definition: DataLayout.h:571
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:640
static ConstantInt * getSigned(IntegerType *Ty, int64_t V)
Return a ConstantInt with the specified value for the specified type.
Definition: Constants.cpp:654
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:1754
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:940
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:146
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:463
This class represents a signed maximum selection.
iterator_range< user_iterator > users()
Definition: Value.h:419
InstListType::iterator iterator
Instruction iterators...
Definition: BasicBlock.h:89
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:1548
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:529
void append(in_iter in_start, in_iter in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:387
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:1986
static bool IsIncrementNUW(ScalarEvolution &SE, const SCEVAddRecExpr *AR)
LoopT * getParentLoop() const
Definition: LoopInfo.h:106
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 ...
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:321
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:585
This class represents an analyzed expression in the program.
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:175
unsigned getIntegerBitWidth() const
Definition: DerivedTypes.h:97
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:55
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:509
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:106
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:192
iterator_range< value_op_iterator > operand_values()
Definition: User.h:261
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:332
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:324
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
void setHasNoUnsignedWrap(bool b=true)
Set or clear the nuw flag on this instruction, which must be an operator which supports this flag...
DebugType
Definition: COFF.h:645
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.
void stable_sort(R &&Range)
Definition: STLExtras.h:1301
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:114
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:575
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:40
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:755
This pass exposes codegen information to IR-level passes.
bool isIllegalInteger(uint64_t Width) const
Definition: DataLayout.h:262
static APInt getNullValue(unsigned numBits)
Get the &#39;0&#39; value.
Definition: APInt.h:568
This node is a base class providing common functionality for n&#39;ary operators.
This class represents an assumption made on an AddRec expression.
NoWrapFlags
NoWrapFlags are bitfield indices into SubclassData.
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:49
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:173
IncrementWrapFlags getFlags() const
Returns the set assumed no overflow flags.
Type * getElementType() const
Definition: DerivedTypes.h:563
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:553
const SCEV * getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth=0)
const BasicBlock * getParent() const
Definition: Instruction.h:66
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)
static Constant * get(unsigned Opcode, Constant *C1, unsigned Flags=0, Type *OnlyIfReducedTy=nullptr)
get - Return a unary operator constant expression, folding if possible.
Definition: Constants.cpp:1824