LLVM  4.0.0
ScalarEvolutionExpander.cpp
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1 //===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis ------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains the implementation of the scalar evolution expander,
11 // which is used to generate the code corresponding to a given scalar evolution
12 // expression.
13 //
14 //===----------------------------------------------------------------------===//
15 
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/SmallSet.h"
20 #include "llvm/Analysis/LoopInfo.h"
22 #include "llvm/IR/DataLayout.h"
23 #include "llvm/IR/Dominators.h"
24 #include "llvm/IR/IntrinsicInst.h"
25 #include "llvm/IR/LLVMContext.h"
26 #include "llvm/IR/Module.h"
27 #include "llvm/IR/PatternMatch.h"
28 #include "llvm/Support/Debug.h"
30 
31 using namespace llvm;
32 using namespace PatternMatch;
33 
34 /// ReuseOrCreateCast - Arrange for there to be a cast of V to Ty at IP,
35 /// reusing an existing cast if a suitable one exists, moving an existing
36 /// cast if a suitable one exists but isn't in the right place, or
37 /// creating a new one.
38 Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
41  // This function must be called with the builder having a valid insertion
42  // point. It doesn't need to be the actual IP where the uses of the returned
43  // cast will be added, but it must dominate such IP.
44  // We use this precondition to produce a cast that will dominate all its
45  // uses. In particular, this is crucial for the case where the builder's
46  // insertion point *is* the point where we were asked to put the cast.
47  // Since we don't know the builder's insertion point is actually
48  // where the uses will be added (only that it dominates it), we are
49  // not allowed to move it.
50  BasicBlock::iterator BIP = Builder.GetInsertPoint();
51 
52  Instruction *Ret = nullptr;
53 
54  // Check to see if there is already a cast!
55  for (User *U : V->users())
56  if (U->getType() == Ty)
57  if (CastInst *CI = dyn_cast<CastInst>(U))
58  if (CI->getOpcode() == Op) {
59  // If the cast isn't where we want it, create a new cast at IP.
60  // Likewise, do not reuse a cast at BIP because it must dominate
61  // instructions that might be inserted before BIP.
62  if (BasicBlock::iterator(CI) != IP || BIP == IP) {
63  // Create a new cast, and leave the old cast in place in case
64  // it is being used as an insert point. Clear its operand
65  // so that it doesn't hold anything live.
66  Ret = CastInst::Create(Op, V, Ty, "", &*IP);
67  Ret->takeName(CI);
68  CI->replaceAllUsesWith(Ret);
69  CI->setOperand(0, UndefValue::get(V->getType()));
70  break;
71  }
72  Ret = CI;
73  break;
74  }
75 
76  // Create a new cast.
77  if (!Ret)
78  Ret = CastInst::Create(Op, V, Ty, V->getName(), &*IP);
79 
80  // We assert at the end of the function since IP might point to an
81  // instruction with different dominance properties than a cast
82  // (an invoke for example) and not dominate BIP (but the cast does).
83  assert(SE.DT.dominates(Ret, &*BIP));
84 
85  rememberInstruction(Ret);
86  return Ret;
87 }
88 
90  BasicBlock *MustDominate) {
92  if (auto *II = dyn_cast<InvokeInst>(I))
93  IP = II->getNormalDest()->begin();
94 
95  while (isa<PHINode>(IP))
96  ++IP;
97 
98  if (isa<FuncletPadInst>(IP) || isa<LandingPadInst>(IP)) {
99  ++IP;
100  } else if (isa<CatchSwitchInst>(IP)) {
101  IP = MustDominate->getFirstInsertionPt();
102  } else {
103  assert(!IP->isEHPad() && "unexpected eh pad!");
104  }
105 
106  return IP;
107 }
108 
109 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
110 /// which must be possible with a noop cast, doing what we can to share
111 /// the casts.
112 Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) {
113  Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false);
114  assert((Op == Instruction::BitCast ||
115  Op == Instruction::PtrToInt ||
116  Op == Instruction::IntToPtr) &&
117  "InsertNoopCastOfTo cannot perform non-noop casts!");
118  assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) &&
119  "InsertNoopCastOfTo cannot change sizes!");
120 
121  // Short-circuit unnecessary bitcasts.
122  if (Op == Instruction::BitCast) {
123  if (V->getType() == Ty)
124  return V;
125  if (CastInst *CI = dyn_cast<CastInst>(V)) {
126  if (CI->getOperand(0)->getType() == Ty)
127  return CI->getOperand(0);
128  }
129  }
130  // Short-circuit unnecessary inttoptr<->ptrtoint casts.
131  if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) &&
132  SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {
133  if (CastInst *CI = dyn_cast<CastInst>(V))
134  if ((CI->getOpcode() == Instruction::PtrToInt ||
135  CI->getOpcode() == Instruction::IntToPtr) &&
136  SE.getTypeSizeInBits(CI->getType()) ==
137  SE.getTypeSizeInBits(CI->getOperand(0)->getType()))
138  return CI->getOperand(0);
139  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
140  if ((CE->getOpcode() == Instruction::PtrToInt ||
141  CE->getOpcode() == Instruction::IntToPtr) &&
142  SE.getTypeSizeInBits(CE->getType()) ==
143  SE.getTypeSizeInBits(CE->getOperand(0)->getType()))
144  return CE->getOperand(0);
145  }
146 
147  // Fold a cast of a constant.
148  if (Constant *C = dyn_cast<Constant>(V))
149  return ConstantExpr::getCast(Op, C, Ty);
150 
151  // Cast the argument at the beginning of the entry block, after
152  // any bitcasts of other arguments.
153  if (Argument *A = dyn_cast<Argument>(V)) {
154  BasicBlock::iterator IP = A->getParent()->getEntryBlock().begin();
155  while ((isa<BitCastInst>(IP) &&
156  isa<Argument>(cast<BitCastInst>(IP)->getOperand(0)) &&
157  cast<BitCastInst>(IP)->getOperand(0) != A) ||
158  isa<DbgInfoIntrinsic>(IP))
159  ++IP;
160  return ReuseOrCreateCast(A, Ty, Op, IP);
161  }
162 
163  // Cast the instruction immediately after the instruction.
164  Instruction *I = cast<Instruction>(V);
165  BasicBlock::iterator IP = findInsertPointAfter(I, Builder.GetInsertBlock());
166  return ReuseOrCreateCast(I, Ty, Op, IP);
167 }
168 
169 /// InsertBinop - Insert the specified binary operator, doing a small amount
170 /// of work to avoid inserting an obviously redundant operation.
171 Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
172  Value *LHS, Value *RHS) {
173  // Fold a binop with constant operands.
174  if (Constant *CLHS = dyn_cast<Constant>(LHS))
175  if (Constant *CRHS = dyn_cast<Constant>(RHS))
176  return ConstantExpr::get(Opcode, CLHS, CRHS);
177 
178  // Do a quick scan to see if we have this binop nearby. If so, reuse it.
179  unsigned ScanLimit = 6;
180  BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
181  // Scanning starts from the last instruction before the insertion point.
182  BasicBlock::iterator IP = Builder.GetInsertPoint();
183  if (IP != BlockBegin) {
184  --IP;
185  for (; ScanLimit; --IP, --ScanLimit) {
186  // Don't count dbg.value against the ScanLimit, to avoid perturbing the
187  // generated code.
188  if (isa<DbgInfoIntrinsic>(IP))
189  ScanLimit++;
190  if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS &&
191  IP->getOperand(1) == RHS)
192  return &*IP;
193  if (IP == BlockBegin) break;
194  }
195  }
196 
197  // Save the original insertion point so we can restore it when we're done.
198  DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
199  SCEVInsertPointGuard Guard(Builder, this);
200 
201  // Move the insertion point out of as many loops as we can.
202  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
203  if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break;
204  BasicBlock *Preheader = L->getLoopPreheader();
205  if (!Preheader) break;
206 
207  // Ok, move up a level.
208  Builder.SetInsertPoint(Preheader->getTerminator());
209  }
210 
211  // If we haven't found this binop, insert it.
212  Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS));
213  BO->setDebugLoc(Loc);
214  rememberInstruction(BO);
215 
216  return BO;
217 }
218 
219 /// FactorOutConstant - Test if S is divisible by Factor, using signed
220 /// division. If so, update S with Factor divided out and return true.
221 /// S need not be evenly divisible if a reasonable remainder can be
222 /// computed.
223 /// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made
224 /// unnecessary; in its place, just signed-divide Ops[i] by the scale and
225 /// check to see if the divide was folded.
226 static bool FactorOutConstant(const SCEV *&S, const SCEV *&Remainder,
227  const SCEV *Factor, ScalarEvolution &SE,
228  const DataLayout &DL) {
229  // Everything is divisible by one.
230  if (Factor->isOne())
231  return true;
232 
233  // x/x == 1.
234  if (S == Factor) {
235  S = SE.getConstant(S->getType(), 1);
236  return true;
237  }
238 
239  // For a Constant, check for a multiple of the given factor.
240  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
241  // 0/x == 0.
242  if (C->isZero())
243  return true;
244  // Check for divisibility.
245  if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor)) {
246  ConstantInt *CI =
247  ConstantInt::get(SE.getContext(), C->getAPInt().sdiv(FC->getAPInt()));
248  // If the quotient is zero and the remainder is non-zero, reject
249  // the value at this scale. It will be considered for subsequent
250  // smaller scales.
251  if (!CI->isZero()) {
252  const SCEV *Div = SE.getConstant(CI);
253  S = Div;
254  Remainder = SE.getAddExpr(
255  Remainder, SE.getConstant(C->getAPInt().srem(FC->getAPInt())));
256  return true;
257  }
258  }
259  }
260 
261  // In a Mul, check if there is a constant operand which is a multiple
262  // of the given factor.
263  if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
264  // Size is known, check if there is a constant operand which is a multiple
265  // of the given factor. If so, we can factor it.
266  const SCEVConstant *FC = cast<SCEVConstant>(Factor);
267  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0)))
268  if (!C->getAPInt().srem(FC->getAPInt())) {
269  SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end());
270  NewMulOps[0] = SE.getConstant(C->getAPInt().sdiv(FC->getAPInt()));
271  S = SE.getMulExpr(NewMulOps);
272  return true;
273  }
274  }
275 
276  // In an AddRec, check if both start and step are divisible.
277  if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
278  const SCEV *Step = A->getStepRecurrence(SE);
279  const SCEV *StepRem = SE.getConstant(Step->getType(), 0);
280  if (!FactorOutConstant(Step, StepRem, Factor, SE, DL))
281  return false;
282  if (!StepRem->isZero())
283  return false;
284  const SCEV *Start = A->getStart();
285  if (!FactorOutConstant(Start, Remainder, Factor, SE, DL))
286  return false;
287  S = SE.getAddRecExpr(Start, Step, A->getLoop(),
288  A->getNoWrapFlags(SCEV::FlagNW));
289  return true;
290  }
291 
292  return false;
293 }
294 
295 /// SimplifyAddOperands - Sort and simplify a list of add operands. NumAddRecs
296 /// is the number of SCEVAddRecExprs present, which are kept at the end of
297 /// the list.
298 ///
300  Type *Ty,
301  ScalarEvolution &SE) {
302  unsigned NumAddRecs = 0;
303  for (unsigned i = Ops.size(); i > 0 && isa<SCEVAddRecExpr>(Ops[i-1]); --i)
304  ++NumAddRecs;
305  // Group Ops into non-addrecs and addrecs.
306  SmallVector<const SCEV *, 8> NoAddRecs(Ops.begin(), Ops.end() - NumAddRecs);
307  SmallVector<const SCEV *, 8> AddRecs(Ops.end() - NumAddRecs, Ops.end());
308  // Let ScalarEvolution sort and simplify the non-addrecs list.
309  const SCEV *Sum = NoAddRecs.empty() ?
310  SE.getConstant(Ty, 0) :
311  SE.getAddExpr(NoAddRecs);
312  // If it returned an add, use the operands. Otherwise it simplified
313  // the sum into a single value, so just use that.
314  Ops.clear();
315  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum))
316  Ops.append(Add->op_begin(), Add->op_end());
317  else if (!Sum->isZero())
318  Ops.push_back(Sum);
319  // Then append the addrecs.
320  Ops.append(AddRecs.begin(), AddRecs.end());
321 }
322 
323 /// SplitAddRecs - Flatten a list of add operands, moving addrec start values
324 /// out to the top level. For example, convert {a + b,+,c} to a, b, {0,+,d}.
325 /// This helps expose more opportunities for folding parts of the expressions
326 /// into GEP indices.
327 ///
329  Type *Ty,
330  ScalarEvolution &SE) {
331  // Find the addrecs.
333  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
334  while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i])) {
335  const SCEV *Start = A->getStart();
336  if (Start->isZero()) break;
337  const SCEV *Zero = SE.getConstant(Ty, 0);
338  AddRecs.push_back(SE.getAddRecExpr(Zero,
339  A->getStepRecurrence(SE),
340  A->getLoop(),
341  A->getNoWrapFlags(SCEV::FlagNW)));
342  if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) {
343  Ops[i] = Zero;
344  Ops.append(Add->op_begin(), Add->op_end());
345  e += Add->getNumOperands();
346  } else {
347  Ops[i] = Start;
348  }
349  }
350  if (!AddRecs.empty()) {
351  // Add the addrecs onto the end of the list.
352  Ops.append(AddRecs.begin(), AddRecs.end());
353  // Resort the operand list, moving any constants to the front.
354  SimplifyAddOperands(Ops, Ty, SE);
355  }
356 }
357 
358 /// expandAddToGEP - Expand an addition expression with a pointer type into
359 /// a GEP instead of using ptrtoint+arithmetic+inttoptr. This helps
360 /// BasicAliasAnalysis and other passes analyze the result. See the rules
361 /// for getelementptr vs. inttoptr in
362 /// http://llvm.org/docs/LangRef.html#pointeraliasing
363 /// for details.
364 ///
365 /// Design note: The correctness of using getelementptr here depends on
366 /// ScalarEvolution not recognizing inttoptr and ptrtoint operators, as
367 /// they may introduce pointer arithmetic which may not be safely converted
368 /// into getelementptr.
369 ///
370 /// Design note: It might seem desirable for this function to be more
371 /// loop-aware. If some of the indices are loop-invariant while others
372 /// aren't, it might seem desirable to emit multiple GEPs, keeping the
373 /// loop-invariant portions of the overall computation outside the loop.
374 /// However, there are a few reasons this is not done here. Hoisting simple
375 /// arithmetic is a low-level optimization that often isn't very
376 /// important until late in the optimization process. In fact, passes
377 /// like InstructionCombining will combine GEPs, even if it means
378 /// pushing loop-invariant computation down into loops, so even if the
379 /// GEPs were split here, the work would quickly be undone. The
380 /// LoopStrengthReduction pass, which is usually run quite late (and
381 /// after the last InstructionCombining pass), takes care of hoisting
382 /// loop-invariant portions of expressions, after considering what
383 /// can be folded using target addressing modes.
384 ///
385 Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
386  const SCEV *const *op_end,
387  PointerType *PTy,
388  Type *Ty,
389  Value *V) {
390  Type *OriginalElTy = PTy->getElementType();
391  Type *ElTy = OriginalElTy;
392  SmallVector<Value *, 4> GepIndices;
393  SmallVector<const SCEV *, 8> Ops(op_begin, op_end);
394  bool AnyNonZeroIndices = false;
395 
396  // Split AddRecs up into parts as either of the parts may be usable
397  // without the other.
398  SplitAddRecs(Ops, Ty, SE);
399 
400  Type *IntPtrTy = DL.getIntPtrType(PTy);
401 
402  // Descend down the pointer's type and attempt to convert the other
403  // operands into GEP indices, at each level. The first index in a GEP
404  // indexes into the array implied by the pointer operand; the rest of
405  // the indices index into the element or field type selected by the
406  // preceding index.
407  for (;;) {
408  // If the scale size is not 0, attempt to factor out a scale for
409  // array indexing.
411  if (ElTy->isSized()) {
412  const SCEV *ElSize = SE.getSizeOfExpr(IntPtrTy, ElTy);
413  if (!ElSize->isZero()) {
415  for (const SCEV *Op : Ops) {
416  const SCEV *Remainder = SE.getConstant(Ty, 0);
417  if (FactorOutConstant(Op, Remainder, ElSize, SE, DL)) {
418  // Op now has ElSize factored out.
419  ScaledOps.push_back(Op);
420  if (!Remainder->isZero())
421  NewOps.push_back(Remainder);
422  AnyNonZeroIndices = true;
423  } else {
424  // The operand was not divisible, so add it to the list of operands
425  // we'll scan next iteration.
426  NewOps.push_back(Op);
427  }
428  }
429  // If we made any changes, update Ops.
430  if (!ScaledOps.empty()) {
431  Ops = NewOps;
432  SimplifyAddOperands(Ops, Ty, SE);
433  }
434  }
435  }
436 
437  // Record the scaled array index for this level of the type. If
438  // we didn't find any operands that could be factored, tentatively
439  // assume that element zero was selected (since the zero offset
440  // would obviously be folded away).
441  Value *Scaled = ScaledOps.empty() ?
443  expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
444  GepIndices.push_back(Scaled);
445 
446  // Collect struct field index operands.
447  while (StructType *STy = dyn_cast<StructType>(ElTy)) {
448  bool FoundFieldNo = false;
449  // An empty struct has no fields.
450  if (STy->getNumElements() == 0) break;
451  // Field offsets are known. See if a constant offset falls within any of
452  // the struct fields.
453  if (Ops.empty())
454  break;
455  if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0]))
456  if (SE.getTypeSizeInBits(C->getType()) <= 64) {
457  const StructLayout &SL = *DL.getStructLayout(STy);
458  uint64_t FullOffset = C->getValue()->getZExtValue();
459  if (FullOffset < SL.getSizeInBytes()) {
460  unsigned ElIdx = SL.getElementContainingOffset(FullOffset);
461  GepIndices.push_back(
463  ElTy = STy->getTypeAtIndex(ElIdx);
464  Ops[0] =
465  SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx));
466  AnyNonZeroIndices = true;
467  FoundFieldNo = true;
468  }
469  }
470  // If no struct field offsets were found, tentatively assume that
471  // field zero was selected (since the zero offset would obviously
472  // be folded away).
473  if (!FoundFieldNo) {
474  ElTy = STy->getTypeAtIndex(0u);
475  GepIndices.push_back(
477  }
478  }
479 
480  if (ArrayType *ATy = dyn_cast<ArrayType>(ElTy))
481  ElTy = ATy->getElementType();
482  else
483  break;
484  }
485 
486  // If none of the operands were convertible to proper GEP indices, cast
487  // the base to i8* and do an ugly getelementptr with that. It's still
488  // better than ptrtoint+arithmetic+inttoptr at least.
489  if (!AnyNonZeroIndices) {
490  // Cast the base to i8*.
491  V = InsertNoopCastOfTo(V,
493 
494  assert(!isa<Instruction>(V) ||
495  SE.DT.dominates(cast<Instruction>(V), &*Builder.GetInsertPoint()));
496 
497  // Expand the operands for a plain byte offset.
498  Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
499 
500  // Fold a GEP with constant operands.
501  if (Constant *CLHS = dyn_cast<Constant>(V))
502  if (Constant *CRHS = dyn_cast<Constant>(Idx))
504  CLHS, CRHS);
505 
506  // Do a quick scan to see if we have this GEP nearby. If so, reuse it.
507  unsigned ScanLimit = 6;
508  BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin();
509  // Scanning starts from the last instruction before the insertion point.
510  BasicBlock::iterator IP = Builder.GetInsertPoint();
511  if (IP != BlockBegin) {
512  --IP;
513  for (; ScanLimit; --IP, --ScanLimit) {
514  // Don't count dbg.value against the ScanLimit, to avoid perturbing the
515  // generated code.
516  if (isa<DbgInfoIntrinsic>(IP))
517  ScanLimit++;
518  if (IP->getOpcode() == Instruction::GetElementPtr &&
519  IP->getOperand(0) == V && IP->getOperand(1) == Idx)
520  return &*IP;
521  if (IP == BlockBegin) break;
522  }
523  }
524 
525  // Save the original insertion point so we can restore it when we're done.
526  SCEVInsertPointGuard Guard(Builder, this);
527 
528  // Move the insertion point out of as many loops as we can.
529  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
530  if (!L->isLoopInvariant(V) || !L->isLoopInvariant(Idx)) break;
531  BasicBlock *Preheader = L->getLoopPreheader();
532  if (!Preheader) break;
533 
534  // Ok, move up a level.
535  Builder.SetInsertPoint(Preheader->getTerminator());
536  }
537 
538  // Emit a GEP.
539  Value *GEP = Builder.CreateGEP(Builder.getInt8Ty(), V, Idx, "uglygep");
540  rememberInstruction(GEP);
541 
542  return GEP;
543  }
544 
545  {
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)) break;
551 
552  bool AnyIndexNotLoopInvariant = any_of(
553  GepIndices, [L](Value *Op) { return !L->isLoopInvariant(Op); });
554 
555  if (AnyIndexNotLoopInvariant)
556  break;
557 
558  BasicBlock *Preheader = L->getLoopPreheader();
559  if (!Preheader) break;
560 
561  // Ok, move up a level.
562  Builder.SetInsertPoint(Preheader->getTerminator());
563  }
564 
565  // Insert a pretty getelementptr. Note that this GEP is not marked inbounds,
566  // because ScalarEvolution may have changed the address arithmetic to
567  // compute a value which is beyond the end of the allocated object.
568  Value *Casted = V;
569  if (V->getType() != PTy)
570  Casted = InsertNoopCastOfTo(Casted, PTy);
571  Value *GEP = Builder.CreateGEP(OriginalElTy, Casted, GepIndices, "scevgep");
572  Ops.push_back(SE.getUnknown(GEP));
573  rememberInstruction(GEP);
574  }
575 
576  return expand(SE.getAddExpr(Ops));
577 }
578 
579 /// PickMostRelevantLoop - Given two loops pick the one that's most relevant for
580 /// SCEV expansion. If they are nested, this is the most nested. If they are
581 /// neighboring, pick the later.
582 static const Loop *PickMostRelevantLoop(const Loop *A, const Loop *B,
583  DominatorTree &DT) {
584  if (!A) return B;
585  if (!B) return A;
586  if (A->contains(B)) return B;
587  if (B->contains(A)) return A;
588  if (DT.dominates(A->getHeader(), B->getHeader())) return B;
589  if (DT.dominates(B->getHeader(), A->getHeader())) return A;
590  return A; // Arbitrarily break the tie.
591 }
592 
593 /// getRelevantLoop - Get the most relevant loop associated with the given
594 /// expression, according to PickMostRelevantLoop.
595 const Loop *SCEVExpander::getRelevantLoop(const SCEV *S) {
596  // Test whether we've already computed the most relevant loop for this SCEV.
597  auto Pair = RelevantLoops.insert(std::make_pair(S, nullptr));
598  if (!Pair.second)
599  return Pair.first->second;
600 
601  if (isa<SCEVConstant>(S))
602  // A constant has no relevant loops.
603  return nullptr;
604  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
605  if (const Instruction *I = dyn_cast<Instruction>(U->getValue()))
606  return Pair.first->second = SE.LI.getLoopFor(I->getParent());
607  // A non-instruction has no relevant loops.
608  return nullptr;
609  }
610  if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) {
611  const Loop *L = nullptr;
612  if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
613  L = AR->getLoop();
614  for (const SCEV *Op : N->operands())
615  L = PickMostRelevantLoop(L, getRelevantLoop(Op), SE.DT);
616  return RelevantLoops[N] = L;
617  }
618  if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) {
619  const Loop *Result = getRelevantLoop(C->getOperand());
620  return RelevantLoops[C] = Result;
621  }
622  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
623  const Loop *Result = PickMostRelevantLoop(
624  getRelevantLoop(D->getLHS()), getRelevantLoop(D->getRHS()), SE.DT);
625  return RelevantLoops[D] = Result;
626  }
627  llvm_unreachable("Unexpected SCEV type!");
628 }
629 
630 namespace {
631 
632 /// LoopCompare - Compare loops by PickMostRelevantLoop.
633 class LoopCompare {
634  DominatorTree &DT;
635 public:
636  explicit LoopCompare(DominatorTree &dt) : DT(dt) {}
637 
638  bool operator()(std::pair<const Loop *, const SCEV *> LHS,
639  std::pair<const Loop *, const SCEV *> RHS) const {
640  // Keep pointer operands sorted at the end.
641  if (LHS.second->getType()->isPointerTy() !=
642  RHS.second->getType()->isPointerTy())
643  return LHS.second->getType()->isPointerTy();
644 
645  // Compare loops with PickMostRelevantLoop.
646  if (LHS.first != RHS.first)
647  return PickMostRelevantLoop(LHS.first, RHS.first, DT) != LHS.first;
648 
649  // If one operand is a non-constant negative and the other is not,
650  // put the non-constant negative on the right so that a sub can
651  // be used instead of a negate and add.
652  if (LHS.second->isNonConstantNegative()) {
653  if (!RHS.second->isNonConstantNegative())
654  return false;
655  } else if (RHS.second->isNonConstantNegative())
656  return true;
657 
658  // Otherwise they are equivalent according to this comparison.
659  return false;
660  }
661 };
662 
663 }
664 
665 Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
666  Type *Ty = SE.getEffectiveSCEVType(S->getType());
667 
668  // Collect all the add operands in a loop, along with their associated loops.
669  // Iterate in reverse so that constants are emitted last, all else equal, and
670  // so that pointer operands are inserted first, which the code below relies on
671  // to form more involved GEPs.
673  for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(S->op_end()),
674  E(S->op_begin()); I != E; ++I)
675  OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
676 
677  // Sort by loop. Use a stable sort so that constants follow non-constants and
678  // pointer operands precede non-pointer operands.
679  std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(SE.DT));
680 
681  // Emit instructions to add all the operands. Hoist as much as possible
682  // out of loops, and form meaningful getelementptrs where possible.
683  Value *Sum = nullptr;
684  for (auto I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E;) {
685  const Loop *CurLoop = I->first;
686  const SCEV *Op = I->second;
687  if (!Sum) {
688  // This is the first operand. Just expand it.
689  Sum = expand(Op);
690  ++I;
691  } else if (PointerType *PTy = dyn_cast<PointerType>(Sum->getType())) {
692  // The running sum expression is a pointer. Try to form a getelementptr
693  // at this level with that as the base.
695  for (; I != E && I->first == CurLoop; ++I) {
696  // If the operand is SCEVUnknown and not instructions, peek through
697  // it, to enable more of it to be folded into the GEP.
698  const SCEV *X = I->second;
699  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(X))
700  if (!isa<Instruction>(U->getValue()))
701  X = SE.getSCEV(U->getValue());
702  NewOps.push_back(X);
703  }
704  Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum);
705  } else if (PointerType *PTy = dyn_cast<PointerType>(Op->getType())) {
706  // The running sum is an integer, and there's a pointer at this level.
707  // Try to form a getelementptr. If the running sum is instructions,
708  // use a SCEVUnknown to avoid re-analyzing them.
710  NewOps.push_back(isa<Instruction>(Sum) ? SE.getUnknown(Sum) :
711  SE.getSCEV(Sum));
712  for (++I; I != E && I->first == CurLoop; ++I)
713  NewOps.push_back(I->second);
714  Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, expand(Op));
715  } else if (Op->isNonConstantNegative()) {
716  // Instead of doing a negate and add, just do a subtract.
717  Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty);
718  Sum = InsertNoopCastOfTo(Sum, Ty);
719  Sum = InsertBinop(Instruction::Sub, Sum, W);
720  ++I;
721  } else {
722  // A simple add.
723  Value *W = expandCodeFor(Op, Ty);
724  Sum = InsertNoopCastOfTo(Sum, Ty);
725  // Canonicalize a constant to the RHS.
726  if (isa<Constant>(Sum)) std::swap(Sum, W);
727  Sum = InsertBinop(Instruction::Add, Sum, W);
728  ++I;
729  }
730  }
731 
732  return Sum;
733 }
734 
735 Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
736  Type *Ty = SE.getEffectiveSCEVType(S->getType());
737 
738  // Collect all the mul operands in a loop, along with their associated loops.
739  // Iterate in reverse so that constants are emitted last, all else equal.
741  for (std::reverse_iterator<SCEVMulExpr::op_iterator> I(S->op_end()),
742  E(S->op_begin()); I != E; ++I)
743  OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I));
744 
745  // Sort by loop. Use a stable sort so that constants follow non-constants.
746  std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(SE.DT));
747 
748  // Emit instructions to mul all the operands. Hoist as much as possible
749  // out of loops.
750  Value *Prod = nullptr;
751  for (const auto &I : OpsAndLoops) {
752  const SCEV *Op = I.second;
753  if (!Prod) {
754  // This is the first operand. Just expand it.
755  Prod = expand(Op);
756  } else if (Op->isAllOnesValue()) {
757  // Instead of doing a multiply by negative one, just do a negate.
758  Prod = InsertNoopCastOfTo(Prod, Ty);
759  Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod);
760  } else {
761  // A simple mul.
762  Value *W = expandCodeFor(Op, Ty);
763  Prod = InsertNoopCastOfTo(Prod, Ty);
764  // Canonicalize a constant to the RHS.
765  if (isa<Constant>(Prod)) std::swap(Prod, W);
766  const APInt *RHS;
767  if (match(W, m_Power2(RHS))) {
768  // Canonicalize Prod*(1<<C) to Prod<<C.
769  assert(!Ty->isVectorTy() && "vector types are not SCEVable");
770  Prod = InsertBinop(Instruction::Shl, Prod,
771  ConstantInt::get(Ty, RHS->logBase2()));
772  } else {
773  Prod = InsertBinop(Instruction::Mul, Prod, W);
774  }
775  }
776  }
777 
778  return Prod;
779 }
780 
781 Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
782  Type *Ty = SE.getEffectiveSCEVType(S->getType());
783 
784  Value *LHS = expandCodeFor(S->getLHS(), Ty);
785  if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
786  const APInt &RHS = SC->getAPInt();
787  if (RHS.isPowerOf2())
788  return InsertBinop(Instruction::LShr, LHS,
789  ConstantInt::get(Ty, RHS.logBase2()));
790  }
791 
792  Value *RHS = expandCodeFor(S->getRHS(), Ty);
793  return InsertBinop(Instruction::UDiv, LHS, RHS);
794 }
795 
796 /// Move parts of Base into Rest to leave Base with the minimal
797 /// expression that provides a pointer operand suitable for a
798 /// GEP expansion.
799 static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest,
800  ScalarEvolution &SE) {
801  while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) {
802  Base = A->getStart();
803  Rest = SE.getAddExpr(Rest,
804  SE.getAddRecExpr(SE.getConstant(A->getType(), 0),
805  A->getStepRecurrence(SE),
806  A->getLoop(),
807  A->getNoWrapFlags(SCEV::FlagNW)));
808  }
809  if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) {
810  Base = A->getOperand(A->getNumOperands()-1);
811  SmallVector<const SCEV *, 8> NewAddOps(A->op_begin(), A->op_end());
812  NewAddOps.back() = Rest;
813  Rest = SE.getAddExpr(NewAddOps);
814  ExposePointerBase(Base, Rest, SE);
815  }
816 }
817 
818 /// Determine if this is a well-behaved chain of instructions leading back to
819 /// the PHI. If so, it may be reused by expanded expressions.
820 bool SCEVExpander::isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV,
821  const Loop *L) {
822  if (IncV->getNumOperands() == 0 || isa<PHINode>(IncV) ||
823  (isa<CastInst>(IncV) && !isa<BitCastInst>(IncV)))
824  return false;
825  // If any of the operands don't dominate the insert position, bail.
826  // Addrec operands are always loop-invariant, so this can only happen
827  // if there are instructions which haven't been hoisted.
828  if (L == IVIncInsertLoop) {
829  for (User::op_iterator OI = IncV->op_begin()+1,
830  OE = IncV->op_end(); OI != OE; ++OI)
831  if (Instruction *OInst = dyn_cast<Instruction>(OI))
832  if (!SE.DT.dominates(OInst, IVIncInsertPos))
833  return false;
834  }
835  // Advance to the next instruction.
836  IncV = dyn_cast<Instruction>(IncV->getOperand(0));
837  if (!IncV)
838  return false;
839 
840  if (IncV->mayHaveSideEffects())
841  return false;
842 
843  if (IncV != PN)
844  return true;
845 
846  return isNormalAddRecExprPHI(PN, IncV, L);
847 }
848 
849 /// getIVIncOperand returns an induction variable increment's induction
850 /// variable operand.
851 ///
852 /// If allowScale is set, any type of GEP is allowed as long as the nonIV
853 /// operands dominate InsertPos.
854 ///
855 /// If allowScale is not set, ensure that a GEP increment conforms to one of the
856 /// simple patterns generated by getAddRecExprPHILiterally and
857 /// expandAddtoGEP. If the pattern isn't recognized, return NULL.
859  Instruction *InsertPos,
860  bool allowScale) {
861  if (IncV == InsertPos)
862  return nullptr;
863 
864  switch (IncV->getOpcode()) {
865  default:
866  return nullptr;
867  // Check for a simple Add/Sub or GEP of a loop invariant step.
868  case Instruction::Add:
869  case Instruction::Sub: {
870  Instruction *OInst = dyn_cast<Instruction>(IncV->getOperand(1));
871  if (!OInst || SE.DT.dominates(OInst, InsertPos))
872  return dyn_cast<Instruction>(IncV->getOperand(0));
873  return nullptr;
874  }
875  case Instruction::BitCast:
876  return dyn_cast<Instruction>(IncV->getOperand(0));
877  case Instruction::GetElementPtr:
878  for (auto I = IncV->op_begin() + 1, E = IncV->op_end(); I != E; ++I) {
879  if (isa<Constant>(*I))
880  continue;
881  if (Instruction *OInst = dyn_cast<Instruction>(*I)) {
882  if (!SE.DT.dominates(OInst, InsertPos))
883  return nullptr;
884  }
885  if (allowScale) {
886  // allow any kind of GEP as long as it can be hoisted.
887  continue;
888  }
889  // This must be a pointer addition of constants (pretty), which is already
890  // handled, or some number of address-size elements (ugly). Ugly geps
891  // have 2 operands. i1* is used by the expander to represent an
892  // address-size element.
893  if (IncV->getNumOperands() != 2)
894  return nullptr;
895  unsigned AS = cast<PointerType>(IncV->getType())->getAddressSpace();
896  if (IncV->getType() != Type::getInt1PtrTy(SE.getContext(), AS)
897  && IncV->getType() != Type::getInt8PtrTy(SE.getContext(), AS))
898  return nullptr;
899  break;
900  }
901  return dyn_cast<Instruction>(IncV->getOperand(0));
902  }
903 }
904 
905 /// If the insert point of the current builder or any of the builders on the
906 /// stack of saved builders has 'I' as its insert point, update it to point to
907 /// the instruction after 'I'. This is intended to be used when the instruction
908 /// 'I' is being moved. If this fixup is not done and 'I' is moved to a
909 /// different block, the inconsistent insert point (with a mismatched
910 /// Instruction and Block) can lead to an instruction being inserted in a block
911 /// other than its parent.
912 void SCEVExpander::fixupInsertPoints(Instruction *I) {
913  BasicBlock::iterator It(*I);
914  BasicBlock::iterator NewInsertPt = std::next(It);
915  if (Builder.GetInsertPoint() == It)
916  Builder.SetInsertPoint(&*NewInsertPt);
917  for (auto *InsertPtGuard : InsertPointGuards)
918  if (InsertPtGuard->GetInsertPoint() == It)
919  InsertPtGuard->SetInsertPoint(NewInsertPt);
920 }
921 
922 /// hoistStep - Attempt to hoist a simple IV increment above InsertPos to make
923 /// it available to other uses in this loop. Recursively hoist any operands,
924 /// until we reach a value that dominates InsertPos.
926  if (SE.DT.dominates(IncV, InsertPos))
927  return true;
928 
929  // InsertPos must itself dominate IncV so that IncV's new position satisfies
930  // its existing users.
931  if (isa<PHINode>(InsertPos) ||
932  !SE.DT.dominates(InsertPos->getParent(), IncV->getParent()))
933  return false;
934 
935  if (!SE.LI.movementPreservesLCSSAForm(IncV, InsertPos))
936  return false;
937 
938  // Check that the chain of IV operands leading back to Phi can be hoisted.
940  for(;;) {
941  Instruction *Oper = getIVIncOperand(IncV, InsertPos, /*allowScale*/true);
942  if (!Oper)
943  return false;
944  // IncV is safe to hoist.
945  IVIncs.push_back(IncV);
946  IncV = Oper;
947  if (SE.DT.dominates(IncV, InsertPos))
948  break;
949  }
950  for (auto I = IVIncs.rbegin(), E = IVIncs.rend(); I != E; ++I) {
951  fixupInsertPoints(*I);
952  (*I)->moveBefore(InsertPos);
953  }
954  return true;
955 }
956 
957 /// Determine if this cyclic phi is in a form that would have been generated by
958 /// LSR. We don't care if the phi was actually expanded in this pass, as long
959 /// as it is in a low-cost form, for example, no implied multiplication. This
960 /// should match any patterns generated by getAddRecExprPHILiterally and
961 /// expandAddtoGEP.
962 bool SCEVExpander::isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV,
963  const Loop *L) {
964  for(Instruction *IVOper = IncV;
965  (IVOper = getIVIncOperand(IVOper, L->getLoopPreheader()->getTerminator(),
966  /*allowScale=*/false));) {
967  if (IVOper == PN)
968  return true;
969  }
970  return false;
971 }
972 
973 /// expandIVInc - Expand an IV increment at Builder's current InsertPos.
974 /// Typically this is the LatchBlock terminator or IVIncInsertPos, but we may
975 /// need to materialize IV increments elsewhere to handle difficult situations.
976 Value *SCEVExpander::expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
977  Type *ExpandTy, Type *IntTy,
978  bool useSubtract) {
979  Value *IncV;
980  // If the PHI is a pointer, use a GEP, otherwise use an add or sub.
981  if (ExpandTy->isPointerTy()) {
982  PointerType *GEPPtrTy = cast<PointerType>(ExpandTy);
983  // If the step isn't constant, don't use an implicitly scaled GEP, because
984  // that would require a multiply inside the loop.
985  if (!isa<ConstantInt>(StepV))
986  GEPPtrTy = PointerType::get(Type::getInt1Ty(SE.getContext()),
987  GEPPtrTy->getAddressSpace());
988  const SCEV *const StepArray[1] = { SE.getSCEV(StepV) };
989  IncV = expandAddToGEP(StepArray, StepArray+1, GEPPtrTy, IntTy, PN);
990  if (IncV->getType() != PN->getType()) {
991  IncV = Builder.CreateBitCast(IncV, PN->getType());
992  rememberInstruction(IncV);
993  }
994  } else {
995  IncV = useSubtract ?
996  Builder.CreateSub(PN, StepV, Twine(IVName) + ".iv.next") :
997  Builder.CreateAdd(PN, StepV, Twine(IVName) + ".iv.next");
998  rememberInstruction(IncV);
999  }
1000  return IncV;
1001 }
1002 
1003 /// \brief Hoist the addrec instruction chain rooted in the loop phi above the
1004 /// position. This routine assumes that this is possible (has been checked).
1005 void SCEVExpander::hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
1006  Instruction *Pos, PHINode *LoopPhi) {
1007  do {
1008  if (DT->dominates(InstToHoist, Pos))
1009  break;
1010  // Make sure the increment is where we want it. But don't move it
1011  // down past a potential existing post-inc user.
1012  fixupInsertPoints(InstToHoist);
1013  InstToHoist->moveBefore(Pos);
1014  Pos = InstToHoist;
1015  InstToHoist = cast<Instruction>(InstToHoist->getOperand(0));
1016  } while (InstToHoist != LoopPhi);
1017 }
1018 
1019 /// \brief Check whether we can cheaply express the requested SCEV in terms of
1020 /// the available PHI SCEV by truncation and/or inversion of the step.
1022  const SCEVAddRecExpr *Phi,
1023  const SCEVAddRecExpr *Requested,
1024  bool &InvertStep) {
1025  Type *PhiTy = SE.getEffectiveSCEVType(Phi->getType());
1026  Type *RequestedTy = SE.getEffectiveSCEVType(Requested->getType());
1027 
1028  if (RequestedTy->getIntegerBitWidth() > PhiTy->getIntegerBitWidth())
1029  return false;
1030 
1031  // Try truncate it if necessary.
1032  Phi = dyn_cast<SCEVAddRecExpr>(SE.getTruncateOrNoop(Phi, RequestedTy));
1033  if (!Phi)
1034  return false;
1035 
1036  // Check whether truncation will help.
1037  if (Phi == Requested) {
1038  InvertStep = false;
1039  return true;
1040  }
1041 
1042  // Check whether inverting will help: {R,+,-1} == R - {0,+,1}.
1043  if (SE.getAddExpr(Requested->getStart(),
1044  SE.getNegativeSCEV(Requested)) == Phi) {
1045  InvertStep = true;
1046  return true;
1047  }
1048 
1049  return false;
1050 }
1051 
1052 static bool IsIncrementNSW(ScalarEvolution &SE, const SCEVAddRecExpr *AR) {
1053  if (!isa<IntegerType>(AR->getType()))
1054  return false;
1055 
1056  unsigned BitWidth = cast<IntegerType>(AR->getType())->getBitWidth();
1057  Type *WideTy = IntegerType::get(AR->getType()->getContext(), BitWidth * 2);
1058  const SCEV *Step = AR->getStepRecurrence(SE);
1059  const SCEV *OpAfterExtend = SE.getAddExpr(SE.getSignExtendExpr(Step, WideTy),
1060  SE.getSignExtendExpr(AR, WideTy));
1061  const SCEV *ExtendAfterOp =
1062  SE.getSignExtendExpr(SE.getAddExpr(AR, Step), WideTy);
1063  return ExtendAfterOp == OpAfterExtend;
1064 }
1065 
1066 static bool IsIncrementNUW(ScalarEvolution &SE, const SCEVAddRecExpr *AR) {
1067  if (!isa<IntegerType>(AR->getType()))
1068  return false;
1069 
1070  unsigned BitWidth = cast<IntegerType>(AR->getType())->getBitWidth();
1071  Type *WideTy = IntegerType::get(AR->getType()->getContext(), BitWidth * 2);
1072  const SCEV *Step = AR->getStepRecurrence(SE);
1073  const SCEV *OpAfterExtend = SE.getAddExpr(SE.getZeroExtendExpr(Step, WideTy),
1074  SE.getZeroExtendExpr(AR, WideTy));
1075  const SCEV *ExtendAfterOp =
1076  SE.getZeroExtendExpr(SE.getAddExpr(AR, Step), WideTy);
1077  return ExtendAfterOp == OpAfterExtend;
1078 }
1079 
1080 /// getAddRecExprPHILiterally - Helper for expandAddRecExprLiterally. Expand
1081 /// the base addrec, which is the addrec without any non-loop-dominating
1082 /// values, and return the PHI.
1083 PHINode *
1084 SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
1085  const Loop *L,
1086  Type *ExpandTy,
1087  Type *IntTy,
1088  Type *&TruncTy,
1089  bool &InvertStep) {
1090  assert((!IVIncInsertLoop||IVIncInsertPos) && "Uninitialized insert position");
1091 
1092  // Reuse a previously-inserted PHI, if present.
1093  BasicBlock *LatchBlock = L->getLoopLatch();
1094  if (LatchBlock) {
1095  PHINode *AddRecPhiMatch = nullptr;
1096  Instruction *IncV = nullptr;
1097  TruncTy = nullptr;
1098  InvertStep = false;
1099 
1100  // Only try partially matching scevs that need truncation and/or
1101  // step-inversion if we know this loop is outside the current loop.
1102  bool TryNonMatchingSCEV =
1103  IVIncInsertLoop &&
1104  SE.DT.properlyDominates(LatchBlock, IVIncInsertLoop->getHeader());
1105 
1106  for (auto &I : *L->getHeader()) {
1107  auto *PN = dyn_cast<PHINode>(&I);
1108  if (!PN || !SE.isSCEVable(PN->getType()))
1109  continue;
1110 
1111  const SCEVAddRecExpr *PhiSCEV = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(PN));
1112  if (!PhiSCEV)
1113  continue;
1114 
1115  bool IsMatchingSCEV = PhiSCEV == Normalized;
1116  // We only handle truncation and inversion of phi recurrences for the
1117  // expanded expression if the expanded expression's loop dominates the
1118  // loop we insert to. Check now, so we can bail out early.
1119  if (!IsMatchingSCEV && !TryNonMatchingSCEV)
1120  continue;
1121 
1122  Instruction *TempIncV =
1123  cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock));
1124 
1125  // Check whether we can reuse this PHI node.
1126  if (LSRMode) {
1127  if (!isExpandedAddRecExprPHI(PN, TempIncV, L))
1128  continue;
1129  if (L == IVIncInsertLoop && !hoistIVInc(TempIncV, IVIncInsertPos))
1130  continue;
1131  } else {
1132  if (!isNormalAddRecExprPHI(PN, TempIncV, L))
1133  continue;
1134  }
1135 
1136  // Stop if we have found an exact match SCEV.
1137  if (IsMatchingSCEV) {
1138  IncV = TempIncV;
1139  TruncTy = nullptr;
1140  InvertStep = false;
1141  AddRecPhiMatch = PN;
1142  break;
1143  }
1144 
1145  // Try whether the phi can be translated into the requested form
1146  // (truncated and/or offset by a constant).
1147  if ((!TruncTy || InvertStep) &&
1148  canBeCheaplyTransformed(SE, PhiSCEV, Normalized, InvertStep)) {
1149  // Record the phi node. But don't stop we might find an exact match
1150  // later.
1151  AddRecPhiMatch = PN;
1152  IncV = TempIncV;
1153  TruncTy = SE.getEffectiveSCEVType(Normalized->getType());
1154  }
1155  }
1156 
1157  if (AddRecPhiMatch) {
1158  // Potentially, move the increment. We have made sure in
1159  // isExpandedAddRecExprPHI or hoistIVInc that this is possible.
1160  if (L == IVIncInsertLoop)
1161  hoistBeforePos(&SE.DT, IncV, IVIncInsertPos, AddRecPhiMatch);
1162 
1163  // Ok, the add recurrence looks usable.
1164  // Remember this PHI, even in post-inc mode.
1165  InsertedValues.insert(AddRecPhiMatch);
1166  // Remember the increment.
1167  rememberInstruction(IncV);
1168  return AddRecPhiMatch;
1169  }
1170  }
1171 
1172  // Save the original insertion point so we can restore it when we're done.
1173  SCEVInsertPointGuard Guard(Builder, this);
1174 
1175  // Another AddRec may need to be recursively expanded below. For example, if
1176  // this AddRec is quadratic, the StepV may itself be an AddRec in this
1177  // loop. Remove this loop from the PostIncLoops set before expanding such
1178  // AddRecs. Otherwise, we cannot find a valid position for the step
1179  // (i.e. StepV can never dominate its loop header). Ideally, we could do
1180  // SavedIncLoops.swap(PostIncLoops), but we generally have a single element,
1181  // so it's not worth implementing SmallPtrSet::swap.
1182  PostIncLoopSet SavedPostIncLoops = PostIncLoops;
1183  PostIncLoops.clear();
1184 
1185  // Expand code for the start value into the loop preheader.
1186  assert(L->getLoopPreheader() &&
1187  "Can't expand add recurrences without a loop preheader!");
1188  Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy,
1189  L->getLoopPreheader()->getTerminator());
1190 
1191  // StartV must have been be inserted into L's preheader to dominate the new
1192  // phi.
1193  assert(!isa<Instruction>(StartV) ||
1194  SE.DT.properlyDominates(cast<Instruction>(StartV)->getParent(),
1195  L->getHeader()));
1196 
1197  // Expand code for the step value. Do this before creating the PHI so that PHI
1198  // reuse code doesn't see an incomplete PHI.
1199  const SCEV *Step = Normalized->getStepRecurrence(SE);
1200  // If the stride is negative, insert a sub instead of an add for the increment
1201  // (unless it's a constant, because subtracts of constants are canonicalized
1202  // to adds).
1203  bool useSubtract = !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
1204  if (useSubtract)
1205  Step = SE.getNegativeSCEV(Step);
1206  // Expand the step somewhere that dominates the loop header.
1207  Value *StepV = expandCodeFor(Step, IntTy, &L->getHeader()->front());
1208 
1209  // The no-wrap behavior proved by IsIncrement(NUW|NSW) is only applicable if
1210  // we actually do emit an addition. It does not apply if we emit a
1211  // subtraction.
1212  bool IncrementIsNUW = !useSubtract && IsIncrementNUW(SE, Normalized);
1213  bool IncrementIsNSW = !useSubtract && IsIncrementNSW(SE, Normalized);
1214 
1215  // Create the PHI.
1216  BasicBlock *Header = L->getHeader();
1217  Builder.SetInsertPoint(Header, Header->begin());
1218  pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
1219  PHINode *PN = Builder.CreatePHI(ExpandTy, std::distance(HPB, HPE),
1220  Twine(IVName) + ".iv");
1221  rememberInstruction(PN);
1222 
1223  // Create the step instructions and populate the PHI.
1224  for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
1225  BasicBlock *Pred = *HPI;
1226 
1227  // Add a start value.
1228  if (!L->contains(Pred)) {
1229  PN->addIncoming(StartV, Pred);
1230  continue;
1231  }
1232 
1233  // Create a step value and add it to the PHI.
1234  // If IVIncInsertLoop is non-null and equal to the addrec's loop, insert the
1235  // instructions at IVIncInsertPos.
1236  Instruction *InsertPos = L == IVIncInsertLoop ?
1237  IVIncInsertPos : Pred->getTerminator();
1238  Builder.SetInsertPoint(InsertPos);
1239  Value *IncV = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
1240 
1241  if (isa<OverflowingBinaryOperator>(IncV)) {
1242  if (IncrementIsNUW)
1243  cast<BinaryOperator>(IncV)->setHasNoUnsignedWrap();
1244  if (IncrementIsNSW)
1245  cast<BinaryOperator>(IncV)->setHasNoSignedWrap();
1246  }
1247  PN->addIncoming(IncV, Pred);
1248  }
1249 
1250  // After expanding subexpressions, restore the PostIncLoops set so the caller
1251  // can ensure that IVIncrement dominates the current uses.
1252  PostIncLoops = SavedPostIncLoops;
1253 
1254  // Remember this PHI, even in post-inc mode.
1255  InsertedValues.insert(PN);
1256 
1257  return PN;
1258 }
1259 
1260 Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
1261  Type *STy = S->getType();
1262  Type *IntTy = SE.getEffectiveSCEVType(STy);
1263  const Loop *L = S->getLoop();
1264 
1265  // Determine a normalized form of this expression, which is the expression
1266  // before any post-inc adjustment is made.
1267  const SCEVAddRecExpr *Normalized = S;
1268  if (PostIncLoops.count(L)) {
1270  Loops.insert(L);
1271  Normalized = cast<SCEVAddRecExpr>(TransformForPostIncUse(
1272  Normalize, S, nullptr, nullptr, Loops, SE, SE.DT));
1273  }
1274 
1275  // Strip off any non-loop-dominating component from the addrec start.
1276  const SCEV *Start = Normalized->getStart();
1277  const SCEV *PostLoopOffset = nullptr;
1278  if (!SE.properlyDominates(Start, L->getHeader())) {
1279  PostLoopOffset = Start;
1280  Start = SE.getConstant(Normalized->getType(), 0);
1281  Normalized = cast<SCEVAddRecExpr>(
1282  SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE),
1283  Normalized->getLoop(),
1284  Normalized->getNoWrapFlags(SCEV::FlagNW)));
1285  }
1286 
1287  // Strip off any non-loop-dominating component from the addrec step.
1288  const SCEV *Step = Normalized->getStepRecurrence(SE);
1289  const SCEV *PostLoopScale = nullptr;
1290  if (!SE.dominates(Step, L->getHeader())) {
1291  PostLoopScale = Step;
1292  Step = SE.getConstant(Normalized->getType(), 1);
1293  if (!Start->isZero()) {
1294  // The normalization below assumes that Start is constant zero, so if
1295  // it isn't re-associate Start to PostLoopOffset.
1296  assert(!PostLoopOffset && "Start not-null but PostLoopOffset set?");
1297  PostLoopOffset = Start;
1298  Start = SE.getConstant(Normalized->getType(), 0);
1299  }
1300  Normalized =
1301  cast<SCEVAddRecExpr>(SE.getAddRecExpr(
1302  Start, Step, Normalized->getLoop(),
1303  Normalized->getNoWrapFlags(SCEV::FlagNW)));
1304  }
1305 
1306  // Expand the core addrec. If we need post-loop scaling, force it to
1307  // expand to an integer type to avoid the need for additional casting.
1308  Type *ExpandTy = PostLoopScale ? IntTy : STy;
1309  // In some cases, we decide to reuse an existing phi node but need to truncate
1310  // it and/or invert the step.
1311  Type *TruncTy = nullptr;
1312  bool InvertStep = false;
1313  PHINode *PN = getAddRecExprPHILiterally(Normalized, L, ExpandTy, IntTy,
1314  TruncTy, InvertStep);
1315 
1316  // Accommodate post-inc mode, if necessary.
1317  Value *Result;
1318  if (!PostIncLoops.count(L))
1319  Result = PN;
1320  else {
1321  // In PostInc mode, use the post-incremented value.
1322  BasicBlock *LatchBlock = L->getLoopLatch();
1323  assert(LatchBlock && "PostInc mode requires a unique loop latch!");
1324  Result = PN->getIncomingValueForBlock(LatchBlock);
1325 
1326  // For an expansion to use the postinc form, the client must call
1327  // expandCodeFor with an InsertPoint that is either outside the PostIncLoop
1328  // or dominated by IVIncInsertPos.
1329  if (isa<Instruction>(Result) &&
1330  !SE.DT.dominates(cast<Instruction>(Result),
1331  &*Builder.GetInsertPoint())) {
1332  // The induction variable's postinc expansion does not dominate this use.
1333  // IVUsers tries to prevent this case, so it is rare. However, it can
1334  // happen when an IVUser outside the loop is not dominated by the latch
1335  // block. Adjusting IVIncInsertPos before expansion begins cannot handle
1336  // all cases. Consider a phi outide whose operand is replaced during
1337  // expansion with the value of the postinc user. Without fundamentally
1338  // changing the way postinc users are tracked, the only remedy is
1339  // inserting an extra IV increment. StepV might fold into PostLoopOffset,
1340  // but hopefully expandCodeFor handles that.
1341  bool useSubtract =
1342  !ExpandTy->isPointerTy() && Step->isNonConstantNegative();
1343  if (useSubtract)
1344  Step = SE.getNegativeSCEV(Step);
1345  Value *StepV;
1346  {
1347  // Expand the step somewhere that dominates the loop header.
1348  SCEVInsertPointGuard Guard(Builder, this);
1349  StepV = expandCodeFor(Step, IntTy, &L->getHeader()->front());
1350  }
1351  Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
1352  }
1353  }
1354 
1355  // We have decided to reuse an induction variable of a dominating loop. Apply
1356  // truncation and/or invertion of the step.
1357  if (TruncTy) {
1358  Type *ResTy = Result->getType();
1359  // Normalize the result type.
1360  if (ResTy != SE.getEffectiveSCEVType(ResTy))
1361  Result = InsertNoopCastOfTo(Result, SE.getEffectiveSCEVType(ResTy));
1362  // Truncate the result.
1363  if (TruncTy != Result->getType()) {
1364  Result = Builder.CreateTrunc(Result, TruncTy);
1365  rememberInstruction(Result);
1366  }
1367  // Invert the result.
1368  if (InvertStep) {
1369  Result = Builder.CreateSub(expandCodeFor(Normalized->getStart(), TruncTy),
1370  Result);
1371  rememberInstruction(Result);
1372  }
1373  }
1374 
1375  // Re-apply any non-loop-dominating scale.
1376  if (PostLoopScale) {
1377  assert(S->isAffine() && "Can't linearly scale non-affine recurrences.");
1378  Result = InsertNoopCastOfTo(Result, IntTy);
1379  Result = Builder.CreateMul(Result,
1380  expandCodeFor(PostLoopScale, IntTy));
1381  rememberInstruction(Result);
1382  }
1383 
1384  // Re-apply any non-loop-dominating offset.
1385  if (PostLoopOffset) {
1386  if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
1387  const SCEV *const OffsetArray[1] = { PostLoopOffset };
1388  Result = expandAddToGEP(OffsetArray, OffsetArray+1, PTy, IntTy, Result);
1389  } else {
1390  Result = InsertNoopCastOfTo(Result, IntTy);
1391  Result = Builder.CreateAdd(Result,
1392  expandCodeFor(PostLoopOffset, IntTy));
1393  rememberInstruction(Result);
1394  }
1395  }
1396 
1397  return Result;
1398 }
1399 
1400 Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
1401  if (!CanonicalMode) return expandAddRecExprLiterally(S);
1402 
1403  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1404  const Loop *L = S->getLoop();
1405 
1406  // First check for an existing canonical IV in a suitable type.
1407  PHINode *CanonicalIV = nullptr;
1408  if (PHINode *PN = L->getCanonicalInductionVariable())
1409  if (SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty))
1410  CanonicalIV = PN;
1411 
1412  // Rewrite an AddRec in terms of the canonical induction variable, if
1413  // its type is more narrow.
1414  if (CanonicalIV &&
1415  SE.getTypeSizeInBits(CanonicalIV->getType()) >
1416  SE.getTypeSizeInBits(Ty)) {
1418  for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i)
1419  NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType());
1420  Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(),
1422  BasicBlock::iterator NewInsertPt =
1423  findInsertPointAfter(cast<Instruction>(V), Builder.GetInsertBlock());
1424  V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), nullptr,
1425  &*NewInsertPt);
1426  return V;
1427  }
1428 
1429  // {X,+,F} --> X + {0,+,F}
1430  if (!S->getStart()->isZero()) {
1431  SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end());
1432  NewOps[0] = SE.getConstant(Ty, 0);
1433  const SCEV *Rest = SE.getAddRecExpr(NewOps, L,
1435 
1436  // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the
1437  // comments on expandAddToGEP for details.
1438  const SCEV *Base = S->getStart();
1439  const SCEV *RestArray[1] = { Rest };
1440  // Dig into the expression to find the pointer base for a GEP.
1441  ExposePointerBase(Base, RestArray[0], SE);
1442  // If we found a pointer, expand the AddRec with a GEP.
1443  if (PointerType *PTy = dyn_cast<PointerType>(Base->getType())) {
1444  // Make sure the Base isn't something exotic, such as a multiplied
1445  // or divided pointer value. In those cases, the result type isn't
1446  // actually a pointer type.
1447  if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) {
1448  Value *StartV = expand(Base);
1449  assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!");
1450  return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV);
1451  }
1452  }
1453 
1454  // Just do a normal add. Pre-expand the operands to suppress folding.
1455  //
1456  // The LHS and RHS values are factored out of the expand call to make the
1457  // output independent of the argument evaluation order.
1458  const SCEV *AddExprLHS = SE.getUnknown(expand(S->getStart()));
1459  const SCEV *AddExprRHS = SE.getUnknown(expand(Rest));
1460  return expand(SE.getAddExpr(AddExprLHS, AddExprRHS));
1461  }
1462 
1463  // If we don't yet have a canonical IV, create one.
1464  if (!CanonicalIV) {
1465  // Create and insert the PHI node for the induction variable in the
1466  // specified loop.
1467  BasicBlock *Header = L->getHeader();
1468  pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header);
1469  CanonicalIV = PHINode::Create(Ty, std::distance(HPB, HPE), "indvar",
1470  &Header->front());
1471  rememberInstruction(CanonicalIV);
1472 
1473  SmallSet<BasicBlock *, 4> PredSeen;
1474  Constant *One = ConstantInt::get(Ty, 1);
1475  for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
1476  BasicBlock *HP = *HPI;
1477  if (!PredSeen.insert(HP).second) {
1478  // There must be an incoming value for each predecessor, even the
1479  // duplicates!
1480  CanonicalIV->addIncoming(CanonicalIV->getIncomingValueForBlock(HP), HP);
1481  continue;
1482  }
1483 
1484  if (L->contains(HP)) {
1485  // Insert a unit add instruction right before the terminator
1486  // corresponding to the back-edge.
1487  Instruction *Add = BinaryOperator::CreateAdd(CanonicalIV, One,
1488  "indvar.next",
1489  HP->getTerminator());
1490  Add->setDebugLoc(HP->getTerminator()->getDebugLoc());
1491  rememberInstruction(Add);
1492  CanonicalIV->addIncoming(Add, HP);
1493  } else {
1494  CanonicalIV->addIncoming(Constant::getNullValue(Ty), HP);
1495  }
1496  }
1497  }
1498 
1499  // {0,+,1} --> Insert a canonical induction variable into the loop!
1500  if (S->isAffine() && S->getOperand(1)->isOne()) {
1501  assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) &&
1502  "IVs with types different from the canonical IV should "
1503  "already have been handled!");
1504  return CanonicalIV;
1505  }
1506 
1507  // {0,+,F} --> {0,+,1} * F
1508 
1509  // If this is a simple linear addrec, emit it now as a special case.
1510  if (S->isAffine()) // {0,+,F} --> i*F
1511  return
1512  expand(SE.getTruncateOrNoop(
1513  SE.getMulExpr(SE.getUnknown(CanonicalIV),
1514  SE.getNoopOrAnyExtend(S->getOperand(1),
1515  CanonicalIV->getType())),
1516  Ty));
1517 
1518  // If this is a chain of recurrences, turn it into a closed form, using the
1519  // folders, then expandCodeFor the closed form. This allows the folders to
1520  // simplify the expression without having to build a bunch of special code
1521  // into this folder.
1522  const SCEV *IH = SE.getUnknown(CanonicalIV); // Get I as a "symbolic" SCEV.
1523 
1524  // Promote S up to the canonical IV type, if the cast is foldable.
1525  const SCEV *NewS = S;
1526  const SCEV *Ext = SE.getNoopOrAnyExtend(S, CanonicalIV->getType());
1527  if (isa<SCEVAddRecExpr>(Ext))
1528  NewS = Ext;
1529 
1530  const SCEV *V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE);
1531  //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n";
1532 
1533  // Truncate the result down to the original type, if needed.
1534  const SCEV *T = SE.getTruncateOrNoop(V, Ty);
1535  return expand(T);
1536 }
1537 
1538 Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
1539  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1540  Value *V = expandCodeFor(S->getOperand(),
1541  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1542  Value *I = Builder.CreateTrunc(V, Ty);
1543  rememberInstruction(I);
1544  return I;
1545 }
1546 
1547 Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
1548  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1549  Value *V = expandCodeFor(S->getOperand(),
1550  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1551  Value *I = Builder.CreateZExt(V, Ty);
1552  rememberInstruction(I);
1553  return I;
1554 }
1555 
1556 Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
1557  Type *Ty = SE.getEffectiveSCEVType(S->getType());
1558  Value *V = expandCodeFor(S->getOperand(),
1559  SE.getEffectiveSCEVType(S->getOperand()->getType()));
1560  Value *I = Builder.CreateSExt(V, Ty);
1561  rememberInstruction(I);
1562  return I;
1563 }
1564 
1565 Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
1566  Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
1567  Type *Ty = LHS->getType();
1568  for (int i = S->getNumOperands()-2; i >= 0; --i) {
1569  // In the case of mixed integer and pointer types, do the
1570  // rest of the comparisons as integer.
1571  if (S->getOperand(i)->getType() != Ty) {
1572  Ty = SE.getEffectiveSCEVType(Ty);
1573  LHS = InsertNoopCastOfTo(LHS, Ty);
1574  }
1575  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1576  Value *ICmp = Builder.CreateICmpSGT(LHS, RHS);
1577  rememberInstruction(ICmp);
1578  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
1579  rememberInstruction(Sel);
1580  LHS = Sel;
1581  }
1582  // In the case of mixed integer and pointer types, cast the
1583  // final result back to the pointer type.
1584  if (LHS->getType() != S->getType())
1585  LHS = InsertNoopCastOfTo(LHS, S->getType());
1586  return LHS;
1587 }
1588 
1589 Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
1590  Value *LHS = expand(S->getOperand(S->getNumOperands()-1));
1591  Type *Ty = LHS->getType();
1592  for (int i = S->getNumOperands()-2; i >= 0; --i) {
1593  // In the case of mixed integer and pointer types, do the
1594  // rest of the comparisons as integer.
1595  if (S->getOperand(i)->getType() != Ty) {
1596  Ty = SE.getEffectiveSCEVType(Ty);
1597  LHS = InsertNoopCastOfTo(LHS, Ty);
1598  }
1599  Value *RHS = expandCodeFor(S->getOperand(i), Ty);
1600  Value *ICmp = Builder.CreateICmpUGT(LHS, RHS);
1601  rememberInstruction(ICmp);
1602  Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
1603  rememberInstruction(Sel);
1604  LHS = Sel;
1605  }
1606  // In the case of mixed integer and pointer types, cast the
1607  // final result back to the pointer type.
1608  if (LHS->getType() != S->getType())
1609  LHS = InsertNoopCastOfTo(LHS, S->getType());
1610  return LHS;
1611 }
1612 
1614  Instruction *IP) {
1615  setInsertPoint(IP);
1616  return expandCodeFor(SH, Ty);
1617 }
1618 
1620  // Expand the code for this SCEV.
1621  Value *V = expand(SH);
1622  if (Ty) {
1623  assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) &&
1624  "non-trivial casts should be done with the SCEVs directly!");
1625  V = InsertNoopCastOfTo(V, Ty);
1626  }
1627  return V;
1628 }
1629 
1630 ScalarEvolution::ValueOffsetPair
1631 SCEVExpander::FindValueInExprValueMap(const SCEV *S,
1632  const Instruction *InsertPt) {
1633  SetVector<ScalarEvolution::ValueOffsetPair> *Set = SE.getSCEVValues(S);
1634  // If the expansion is not in CanonicalMode, and the SCEV contains any
1635  // sub scAddRecExpr type SCEV, it is required to expand the SCEV literally.
1636  if (CanonicalMode || !SE.containsAddRecurrence(S)) {
1637  // If S is scConstant, it may be worse to reuse an existing Value.
1638  if (S->getSCEVType() != scConstant && Set) {
1639  // Choose a Value from the set which dominates the insertPt.
1640  // insertPt should be inside the Value's parent loop so as not to break
1641  // the LCSSA form.
1642  for (auto const &VOPair : *Set) {
1643  Value *V = VOPair.first;
1644  ConstantInt *Offset = VOPair.second;
1645  Instruction *EntInst = nullptr;
1646  if (V && isa<Instruction>(V) && (EntInst = cast<Instruction>(V)) &&
1647  S->getType() == V->getType() &&
1648  EntInst->getFunction() == InsertPt->getFunction() &&
1649  SE.DT.dominates(EntInst, InsertPt) &&
1650  (SE.LI.getLoopFor(EntInst->getParent()) == nullptr ||
1651  SE.LI.getLoopFor(EntInst->getParent())->contains(InsertPt)))
1652  return {V, Offset};
1653  }
1654  }
1655  }
1656  return {nullptr, nullptr};
1657 }
1658 
1659 // The expansion of SCEV will either reuse a previous Value in ExprValueMap,
1660 // or expand the SCEV literally. Specifically, if the expansion is in LSRMode,
1661 // and the SCEV contains any sub scAddRecExpr type SCEV, it will be expanded
1662 // literally, to prevent LSR's transformed SCEV from being reverted. Otherwise,
1663 // the expansion will try to reuse Value from ExprValueMap, and only when it
1664 // fails, expand the SCEV literally.
1665 Value *SCEVExpander::expand(const SCEV *S) {
1666  // Compute an insertion point for this SCEV object. Hoist the instructions
1667  // as far out in the loop nest as possible.
1668  Instruction *InsertPt = &*Builder.GetInsertPoint();
1669  for (Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock());;
1670  L = L->getParentLoop())
1671  if (SE.isLoopInvariant(S, L)) {
1672  if (!L) break;
1673  if (BasicBlock *Preheader = L->getLoopPreheader())
1674  InsertPt = Preheader->getTerminator();
1675  else {
1676  // LSR sets the insertion point for AddRec start/step values to the
1677  // block start to simplify value reuse, even though it's an invalid
1678  // position. SCEVExpander must correct for this in all cases.
1679  InsertPt = &*L->getHeader()->getFirstInsertionPt();
1680  }
1681  } else {
1682  // If the SCEV is computable at this level, insert it into the header
1683  // after the PHIs (and after any other instructions that we've inserted
1684  // there) so that it is guaranteed to dominate any user inside the loop.
1685  if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
1686  InsertPt = &*L->getHeader()->getFirstInsertionPt();
1687  while (InsertPt->getIterator() != Builder.GetInsertPoint() &&
1688  (isInsertedInstruction(InsertPt) ||
1689  isa<DbgInfoIntrinsic>(InsertPt))) {
1690  InsertPt = &*std::next(InsertPt->getIterator());
1691  }
1692  break;
1693  }
1694 
1695  // Check to see if we already expanded this here.
1696  auto I = InsertedExpressions.find(std::make_pair(S, InsertPt));
1697  if (I != InsertedExpressions.end())
1698  return I->second;
1699 
1700  SCEVInsertPointGuard Guard(Builder, this);
1701  Builder.SetInsertPoint(InsertPt);
1702 
1703  // Expand the expression into instructions.
1704  ScalarEvolution::ValueOffsetPair VO = FindValueInExprValueMap(S, InsertPt);
1705  Value *V = VO.first;
1706 
1707  if (!V)
1708  V = visit(S);
1709  else if (VO.second) {
1710  if (PointerType *Vty = dyn_cast<PointerType>(V->getType())) {
1711  Type *Ety = Vty->getPointerElementType();
1712  int64_t Offset = VO.second->getSExtValue();
1713  int64_t ESize = SE.getTypeSizeInBits(Ety);
1714  if ((Offset * 8) % ESize == 0) {
1715  ConstantInt *Idx =
1716  ConstantInt::getSigned(VO.second->getType(), -(Offset * 8) / ESize);
1717  V = Builder.CreateGEP(Ety, V, Idx, "scevgep");
1718  } else {
1719  ConstantInt *Idx =
1720  ConstantInt::getSigned(VO.second->getType(), -Offset);
1721  unsigned AS = Vty->getAddressSpace();
1722  V = Builder.CreateBitCast(V, Type::getInt8PtrTy(SE.getContext(), AS));
1723  V = Builder.CreateGEP(Type::getInt8Ty(SE.getContext()), V, Idx,
1724  "uglygep");
1725  V = Builder.CreateBitCast(V, Vty);
1726  }
1727  } else {
1728  V = Builder.CreateSub(V, VO.second);
1729  }
1730  }
1731  // Remember the expanded value for this SCEV at this location.
1732  //
1733  // This is independent of PostIncLoops. The mapped value simply materializes
1734  // the expression at this insertion point. If the mapped value happened to be
1735  // a postinc expansion, it could be reused by a non-postinc user, but only if
1736  // its insertion point was already at the head of the loop.
1737  InsertedExpressions[std::make_pair(S, InsertPt)] = V;
1738  return V;
1739 }
1740 
1741 void SCEVExpander::rememberInstruction(Value *I) {
1742  if (!PostIncLoops.empty())
1743  InsertedPostIncValues.insert(I);
1744  else
1745  InsertedValues.insert(I);
1746 }
1747 
1748 /// getOrInsertCanonicalInductionVariable - This method returns the
1749 /// canonical induction variable of the specified type for the specified
1750 /// loop (inserting one if there is none). A canonical induction variable
1751 /// starts at zero and steps by one on each iteration.
1752 PHINode *
1754  Type *Ty) {
1755  assert(Ty->isIntegerTy() && "Can only insert integer induction variables!");
1756 
1757  // Build a SCEV for {0,+,1}<L>.
1758  // Conservatively use FlagAnyWrap for now.
1759  const SCEV *H = SE.getAddRecExpr(SE.getConstant(Ty, 0),
1760  SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
1761 
1762  // Emit code for it.
1763  SCEVInsertPointGuard Guard(Builder, this);
1764  PHINode *V =
1765  cast<PHINode>(expandCodeFor(H, nullptr, &L->getHeader()->front()));
1766 
1767  return V;
1768 }
1769 
1770 /// replaceCongruentIVs - Check for congruent phis in this loop header and
1771 /// replace them with their most canonical representative. Return the number of
1772 /// phis eliminated.
1773 ///
1774 /// This does not depend on any SCEVExpander state but should be used in
1775 /// the same context that SCEVExpander is used.
1777  SmallVectorImpl<WeakVH> &DeadInsts,
1778  const TargetTransformInfo *TTI) {
1779  // Find integer phis in order of increasing width.
1781  for (auto &I : *L->getHeader()) {
1782  if (auto *PN = dyn_cast<PHINode>(&I))
1783  Phis.push_back(PN);
1784  else
1785  break;
1786  }
1787 
1788  if (TTI)
1789  std::sort(Phis.begin(), Phis.end(), [](Value *LHS, Value *RHS) {
1790  // Put pointers at the back and make sure pointer < pointer = false.
1791  if (!LHS->getType()->isIntegerTy() || !RHS->getType()->isIntegerTy())
1792  return RHS->getType()->isIntegerTy() && !LHS->getType()->isIntegerTy();
1793  return RHS->getType()->getPrimitiveSizeInBits() <
1794  LHS->getType()->getPrimitiveSizeInBits();
1795  });
1796 
1797  unsigned NumElim = 0;
1799  // Process phis from wide to narrow. Map wide phis to their truncation
1800  // so narrow phis can reuse them.
1801  for (PHINode *Phi : Phis) {
1802  auto SimplifyPHINode = [&](PHINode *PN) -> Value * {
1803  if (Value *V = SimplifyInstruction(PN, DL, &SE.TLI, &SE.DT, &SE.AC))
1804  return V;
1805  if (!SE.isSCEVable(PN->getType()))
1806  return nullptr;
1807  auto *Const = dyn_cast<SCEVConstant>(SE.getSCEV(PN));
1808  if (!Const)
1809  return nullptr;
1810  return Const->getValue();
1811  };
1812 
1813  // Fold constant phis. They may be congruent to other constant phis and
1814  // would confuse the logic below that expects proper IVs.
1815  if (Value *V = SimplifyPHINode(Phi)) {
1816  if (V->getType() != Phi->getType())
1817  continue;
1818  Phi->replaceAllUsesWith(V);
1819  DeadInsts.emplace_back(Phi);
1820  ++NumElim;
1822  << "INDVARS: Eliminated constant iv: " << *Phi << '\n');
1823  continue;
1824  }
1825 
1826  if (!SE.isSCEVable(Phi->getType()))
1827  continue;
1828 
1829  PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
1830  if (!OrigPhiRef) {
1831  OrigPhiRef = Phi;
1832  if (Phi->getType()->isIntegerTy() && TTI &&
1833  TTI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
1834  // This phi can be freely truncated to the narrowest phi type. Map the
1835  // truncated expression to it so it will be reused for narrow types.
1836  const SCEV *TruncExpr =
1837  SE.getTruncateExpr(SE.getSCEV(Phi), Phis.back()->getType());
1838  ExprToIVMap[TruncExpr] = Phi;
1839  }
1840  continue;
1841  }
1842 
1843  // Replacing a pointer phi with an integer phi or vice-versa doesn't make
1844  // sense.
1845  if (OrigPhiRef->getType()->isPointerTy() != Phi->getType()->isPointerTy())
1846  continue;
1847 
1848  if (BasicBlock *LatchBlock = L->getLoopLatch()) {
1849  Instruction *OrigInc = dyn_cast<Instruction>(
1850  OrigPhiRef->getIncomingValueForBlock(LatchBlock));
1851  Instruction *IsomorphicInc =
1852  dyn_cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
1853 
1854  if (OrigInc && IsomorphicInc) {
1855  // If this phi has the same width but is more canonical, replace the
1856  // original with it. As part of the "more canonical" determination,
1857  // respect a prior decision to use an IV chain.
1858  if (OrigPhiRef->getType() == Phi->getType() &&
1859  !(ChainedPhis.count(Phi) ||
1860  isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)) &&
1861  (ChainedPhis.count(Phi) ||
1862  isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
1863  std::swap(OrigPhiRef, Phi);
1864  std::swap(OrigInc, IsomorphicInc);
1865  }
1866  // Replacing the congruent phi is sufficient because acyclic
1867  // redundancy elimination, CSE/GVN, should handle the
1868  // rest. However, once SCEV proves that a phi is congruent,
1869  // it's often the head of an IV user cycle that is isomorphic
1870  // with the original phi. It's worth eagerly cleaning up the
1871  // common case of a single IV increment so that DeleteDeadPHIs
1872  // can remove cycles that had postinc uses.
1873  const SCEV *TruncExpr =
1874  SE.getTruncateOrNoop(SE.getSCEV(OrigInc), IsomorphicInc->getType());
1875  if (OrigInc != IsomorphicInc &&
1876  TruncExpr == SE.getSCEV(IsomorphicInc) &&
1877  SE.LI.replacementPreservesLCSSAForm(IsomorphicInc, OrigInc) &&
1878  hoistIVInc(OrigInc, IsomorphicInc)) {
1880  dbgs() << "INDVARS: Eliminated congruent iv.inc: "
1881  << *IsomorphicInc << '\n');
1882  Value *NewInc = OrigInc;
1883  if (OrigInc->getType() != IsomorphicInc->getType()) {
1884  Instruction *IP = nullptr;
1885  if (PHINode *PN = dyn_cast<PHINode>(OrigInc))
1886  IP = &*PN->getParent()->getFirstInsertionPt();
1887  else
1888  IP = OrigInc->getNextNode();
1889 
1890  IRBuilder<> Builder(IP);
1891  Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
1892  NewInc = Builder.CreateTruncOrBitCast(
1893  OrigInc, IsomorphicInc->getType(), IVName);
1894  }
1895  IsomorphicInc->replaceAllUsesWith(NewInc);
1896  DeadInsts.emplace_back(IsomorphicInc);
1897  }
1898  }
1899  }
1900  DEBUG_WITH_TYPE(DebugType, dbgs() << "INDVARS: Eliminated congruent iv: "
1901  << *Phi << '\n');
1902  ++NumElim;
1903  Value *NewIV = OrigPhiRef;
1904  if (OrigPhiRef->getType() != Phi->getType()) {
1905  IRBuilder<> Builder(&*L->getHeader()->getFirstInsertionPt());
1906  Builder.SetCurrentDebugLocation(Phi->getDebugLoc());
1907  NewIV = Builder.CreateTruncOrBitCast(OrigPhiRef, Phi->getType(), IVName);
1908  }
1909  Phi->replaceAllUsesWith(NewIV);
1910  DeadInsts.emplace_back(Phi);
1911  }
1912  return NumElim;
1913 }
1914 
1916  const Instruction *At, Loop *L) {
1918  getRelatedExistingExpansion(S, At, L);
1919  if (VO && VO.getValue().second == nullptr)
1920  return VO.getValue().first;
1921  return nullptr;
1922 }
1923 
1926  Loop *L) {
1927  using namespace llvm::PatternMatch;
1928 
1929  SmallVector<BasicBlock *, 4> ExitingBlocks;
1930  L->getExitingBlocks(ExitingBlocks);
1931 
1932  // Look for suitable value in simple conditions at the loop exits.
1933  for (BasicBlock *BB : ExitingBlocks) {
1934  ICmpInst::Predicate Pred;
1935  Instruction *LHS, *RHS;
1936  BasicBlock *TrueBB, *FalseBB;
1937 
1938  if (!match(BB->getTerminator(),
1939  m_Br(m_ICmp(Pred, m_Instruction(LHS), m_Instruction(RHS)),
1940  TrueBB, FalseBB)))
1941  continue;
1942 
1943  if (SE.getSCEV(LHS) == S && SE.DT.dominates(LHS, At))
1944  return ScalarEvolution::ValueOffsetPair(LHS, nullptr);
1945 
1946  if (SE.getSCEV(RHS) == S && SE.DT.dominates(RHS, At))
1947  return ScalarEvolution::ValueOffsetPair(RHS, nullptr);
1948  }
1949 
1950  // Use expand's logic which is used for reusing a previous Value in
1951  // ExprValueMap.
1952  ScalarEvolution::ValueOffsetPair VO = FindValueInExprValueMap(S, At);
1953  if (VO.first)
1954  return VO;
1955 
1956  // There is potential to make this significantly smarter, but this simple
1957  // heuristic already gets some interesting cases.
1958 
1959  // Can not find suitable value.
1960  return None;
1961 }
1962 
1963 bool SCEVExpander::isHighCostExpansionHelper(
1964  const SCEV *S, Loop *L, const Instruction *At,
1965  SmallPtrSetImpl<const SCEV *> &Processed) {
1966 
1967  // If we can find an existing value for this scev available at the point "At"
1968  // then consider the expression cheap.
1969  if (At && getRelatedExistingExpansion(S, At, L))
1970  return false;
1971 
1972  // Zero/One operand expressions
1973  switch (S->getSCEVType()) {
1974  case scUnknown:
1975  case scConstant:
1976  return false;
1977  case scTruncate:
1978  return isHighCostExpansionHelper(cast<SCEVTruncateExpr>(S)->getOperand(),
1979  L, At, Processed);
1980  case scZeroExtend:
1981  return isHighCostExpansionHelper(cast<SCEVZeroExtendExpr>(S)->getOperand(),
1982  L, At, Processed);
1983  case scSignExtend:
1984  return isHighCostExpansionHelper(cast<SCEVSignExtendExpr>(S)->getOperand(),
1985  L, At, Processed);
1986  }
1987 
1988  if (!Processed.insert(S).second)
1989  return false;
1990 
1991  if (auto *UDivExpr = dyn_cast<SCEVUDivExpr>(S)) {
1992  // If the divisor is a power of two and the SCEV type fits in a native
1993  // integer, consider the division cheap irrespective of whether it occurs in
1994  // the user code since it can be lowered into a right shift.
1995  if (auto *SC = dyn_cast<SCEVConstant>(UDivExpr->getRHS()))
1996  if (SC->getAPInt().isPowerOf2()) {
1997  const DataLayout &DL =
1998  L->getHeader()->getParent()->getParent()->getDataLayout();
1999  unsigned Width = cast<IntegerType>(UDivExpr->getType())->getBitWidth();
2000  return DL.isIllegalInteger(Width);
2001  }
2002 
2003  // UDivExpr is very likely a UDiv that ScalarEvolution's HowFarToZero or
2004  // HowManyLessThans produced to compute a precise expression, rather than a
2005  // UDiv from the user's code. If we can't find a UDiv in the code with some
2006  // simple searching, assume the former consider UDivExpr expensive to
2007  // compute.
2008  BasicBlock *ExitingBB = L->getExitingBlock();
2009  if (!ExitingBB)
2010  return true;
2011 
2012  // At the beginning of this function we already tried to find existing value
2013  // for plain 'S'. Now try to lookup 'S + 1' since it is common pattern
2014  // involving division. This is just a simple search heuristic.
2015  if (!At)
2016  At = &ExitingBB->back();
2017  if (!getRelatedExistingExpansion(
2018  SE.getAddExpr(S, SE.getConstant(S->getType(), 1)), At, L))
2019  return true;
2020  }
2021 
2022  // HowManyLessThans uses a Max expression whenever the loop is not guarded by
2023  // the exit condition.
2024  if (isa<SCEVSMaxExpr>(S) || isa<SCEVUMaxExpr>(S))
2025  return true;
2026 
2027  // Recurse past nary expressions, which commonly occur in the
2028  // BackedgeTakenCount. They may already exist in program code, and if not,
2029  // they are not too expensive rematerialize.
2030  if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(S)) {
2031  for (auto *Op : NAry->operands())
2032  if (isHighCostExpansionHelper(Op, L, At, Processed))
2033  return true;
2034  }
2035 
2036  // If we haven't recognized an expensive SCEV pattern, assume it's an
2037  // expression produced by program code.
2038  return false;
2039 }
2040 
2042  Instruction *IP) {
2043  assert(IP);
2044  switch (Pred->getKind()) {
2046  return expandUnionPredicate(cast<SCEVUnionPredicate>(Pred), IP);
2048  return expandEqualPredicate(cast<SCEVEqualPredicate>(Pred), IP);
2049  case SCEVPredicate::P_Wrap: {
2050  auto *AddRecPred = cast<SCEVWrapPredicate>(Pred);
2051  return expandWrapPredicate(AddRecPred, IP);
2052  }
2053  }
2054  llvm_unreachable("Unknown SCEV predicate type");
2055 }
2056 
2058  Instruction *IP) {
2059  Value *Expr0 = expandCodeFor(Pred->getLHS(), Pred->getLHS()->getType(), IP);
2060  Value *Expr1 = expandCodeFor(Pred->getRHS(), Pred->getRHS()->getType(), IP);
2061 
2062  Builder.SetInsertPoint(IP);
2063  auto *I = Builder.CreateICmpNE(Expr0, Expr1, "ident.check");
2064  return I;
2065 }
2066 
2068  Instruction *Loc, bool Signed) {
2069  assert(AR->isAffine() && "Cannot generate RT check for "
2070  "non-affine expression");
2071 
2072  SCEVUnionPredicate Pred;
2073  const SCEV *ExitCount =
2074  SE.getPredicatedBackedgeTakenCount(AR->getLoop(), Pred);
2075 
2076  assert(ExitCount != SE.getCouldNotCompute() && "Invalid loop count");
2077 
2078  const SCEV *Step = AR->getStepRecurrence(SE);
2079  const SCEV *Start = AR->getStart();
2080 
2081  unsigned SrcBits = SE.getTypeSizeInBits(ExitCount->getType());
2082  unsigned DstBits = SE.getTypeSizeInBits(AR->getType());
2083 
2084  // The expression {Start,+,Step} has nusw/nssw if
2085  // Step < 0, Start - |Step| * Backedge <= Start
2086  // Step >= 0, Start + |Step| * Backedge > Start
2087  // and |Step| * Backedge doesn't unsigned overflow.
2088 
2089  IntegerType *CountTy = IntegerType::get(Loc->getContext(), SrcBits);
2090  Builder.SetInsertPoint(Loc);
2091  Value *TripCountVal = expandCodeFor(ExitCount, CountTy, Loc);
2092 
2093  IntegerType *Ty =
2094  IntegerType::get(Loc->getContext(), SE.getTypeSizeInBits(AR->getType()));
2095 
2096  Value *StepValue = expandCodeFor(Step, Ty, Loc);
2097  Value *NegStepValue = expandCodeFor(SE.getNegativeSCEV(Step), Ty, Loc);
2098  Value *StartValue = expandCodeFor(Start, Ty, Loc);
2099 
2100  ConstantInt *Zero =
2102 
2103  Builder.SetInsertPoint(Loc);
2104  // Compute |Step|
2105  Value *StepCompare = Builder.CreateICmp(ICmpInst::ICMP_SLT, StepValue, Zero);
2106  Value *AbsStep = Builder.CreateSelect(StepCompare, NegStepValue, StepValue);
2107 
2108  // Get the backedge taken count and truncate or extended to the AR type.
2109  Value *TruncTripCount = Builder.CreateZExtOrTrunc(TripCountVal, Ty);
2110  auto *MulF = Intrinsic::getDeclaration(Loc->getModule(),
2111  Intrinsic::umul_with_overflow, Ty);
2112 
2113  // Compute |Step| * Backedge
2114  CallInst *Mul = Builder.CreateCall(MulF, {AbsStep, TruncTripCount}, "mul");
2115  Value *MulV = Builder.CreateExtractValue(Mul, 0, "mul.result");
2116  Value *OfMul = Builder.CreateExtractValue(Mul, 1, "mul.overflow");
2117 
2118  // Compute:
2119  // Start + |Step| * Backedge < Start
2120  // Start - |Step| * Backedge > Start
2121  Value *Add = Builder.CreateAdd(StartValue, MulV);
2122  Value *Sub = Builder.CreateSub(StartValue, MulV);
2123 
2124  Value *EndCompareGT = Builder.CreateICmp(
2125  Signed ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT, Sub, StartValue);
2126 
2127  Value *EndCompareLT = Builder.CreateICmp(
2128  Signed ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT, Add, StartValue);
2129 
2130  // Select the answer based on the sign of Step.
2131  Value *EndCheck =
2132  Builder.CreateSelect(StepCompare, EndCompareGT, EndCompareLT);
2133 
2134  // If the backedge taken count type is larger than the AR type,
2135  // check that we don't drop any bits by truncating it. If we are
2136  // droping bits, then we have overflow (unless the step is zero).
2137  if (SE.getTypeSizeInBits(CountTy) > SE.getTypeSizeInBits(Ty)) {
2138  auto MaxVal = APInt::getMaxValue(DstBits).zext(SrcBits);
2139  auto *BackedgeCheck =
2140  Builder.CreateICmp(ICmpInst::ICMP_UGT, TripCountVal,
2141  ConstantInt::get(Loc->getContext(), MaxVal));
2142  BackedgeCheck = Builder.CreateAnd(
2143  BackedgeCheck, Builder.CreateICmp(ICmpInst::ICMP_NE, StepValue, Zero));
2144 
2145  EndCheck = Builder.CreateOr(EndCheck, BackedgeCheck);
2146  }
2147 
2148  EndCheck = Builder.CreateOr(EndCheck, OfMul);
2149  return EndCheck;
2150 }
2151 
2153  Instruction *IP) {
2154  const auto *A = cast<SCEVAddRecExpr>(Pred->getExpr());
2155  Value *NSSWCheck = nullptr, *NUSWCheck = nullptr;
2156 
2157  // Add a check for NUSW
2159  NUSWCheck = generateOverflowCheck(A, IP, false);
2160 
2161  // Add a check for NSSW
2163  NSSWCheck = generateOverflowCheck(A, IP, true);
2164 
2165  if (NUSWCheck && NSSWCheck)
2166  return Builder.CreateOr(NUSWCheck, NSSWCheck);
2167 
2168  if (NUSWCheck)
2169  return NUSWCheck;
2170 
2171  if (NSSWCheck)
2172  return NSSWCheck;
2173 
2174  return ConstantInt::getFalse(IP->getContext());
2175 }
2176 
2178  Instruction *IP) {
2179  auto *BoolType = IntegerType::get(IP->getContext(), 1);
2180  Value *Check = ConstantInt::getNullValue(BoolType);
2181 
2182  // Loop over all checks in this set.
2183  for (auto Pred : Union->getPredicates()) {
2184  auto *NextCheck = expandCodeForPredicate(Pred, IP);
2185  Builder.SetInsertPoint(IP);
2186  Check = Builder.CreateOr(Check, NextCheck);
2187  }
2188 
2189  return Check;
2190 }
2191 
2192 namespace {
2193 // Search for a SCEV subexpression that is not safe to expand. Any expression
2194 // that may expand to a !isSafeToSpeculativelyExecute value is unsafe, namely
2195 // UDiv expressions. We don't know if the UDiv is derived from an IR divide
2196 // instruction, but the important thing is that we prove the denominator is
2197 // nonzero before expansion.
2198 //
2199 // IVUsers already checks that IV-derived expressions are safe. So this check is
2200 // only needed when the expression includes some subexpression that is not IV
2201 // derived.
2202 //
2203 // Currently, we only allow division by a nonzero constant here. If this is
2204 // inadequate, we could easily allow division by SCEVUnknown by using
2205 // ValueTracking to check isKnownNonZero().
2206 //
2207 // We cannot generally expand recurrences unless the step dominates the loop
2208 // header. The expander handles the special case of affine recurrences by
2209 // scaling the recurrence outside the loop, but this technique isn't generally
2210 // applicable. Expanding a nested recurrence outside a loop requires computing
2211 // binomial coefficients. This could be done, but the recurrence has to be in a
2212 // perfectly reduced form, which can't be guaranteed.
2213 struct SCEVFindUnsafe {
2214  ScalarEvolution &SE;
2215  bool IsUnsafe;
2216 
2217  SCEVFindUnsafe(ScalarEvolution &se): SE(se), IsUnsafe(false) {}
2218 
2219  bool follow(const SCEV *S) {
2220  if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
2221  const SCEVConstant *SC = dyn_cast<SCEVConstant>(D->getRHS());
2222  if (!SC || SC->getValue()->isZero()) {
2223  IsUnsafe = true;
2224  return false;
2225  }
2226  }
2227  if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
2228  const SCEV *Step = AR->getStepRecurrence(SE);
2229  if (!AR->isAffine() && !SE.dominates(Step, AR->getLoop()->getHeader())) {
2230  IsUnsafe = true;
2231  return false;
2232  }
2233  }
2234  return true;
2235  }
2236  bool isDone() const { return IsUnsafe; }
2237 };
2238 }
2239 
2240 namespace llvm {
2241 bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE) {
2242  SCEVFindUnsafe Search(SE);
2243  visitAll(S, Search);
2244  return !Search.IsUnsafe;
2245 }
2246 }
NoWrapFlags getNoWrapFlags(NoWrapFlags Mask=NoWrapMask) const
MachineLoop * L
static unsigned getBitWidth(Type *Ty, const DataLayout &DL)
Returns the bitwidth of the given scalar or pointer type (if unknown returns 0).
const SCEV * getTruncateOrNoop(const SCEV *V, Type *Ty)
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
IncrementWrapFlags getFlags() const
Returns the set assumed no overflow flags.
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:102
bool hoistIVInc(Instruction *IncV, Instruction *InsertPos)
Utility for hoisting an IV increment.
static ConstantInt * getFalse(LLVMContext &Context)
Definition: Constants.cpp:513
static IntegerType * getInt1Ty(LLVMContext &C)
Definition: Type.cpp:166
void addIncoming(Value *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
Value * getExactExistingExpansion(const SCEV *S, const Instruction *At, Loop *L)
Try to find existing LLVM IR value for S available at the point At.
LLVM Argument representation.
Definition: Argument.h:34
const SCEV * TransformForPostIncUse(TransformKind Kind, const SCEV *S, Instruction *User, Value *OperandValToReplace, PostIncLoopSet &Loops, ScalarEvolution &SE, DominatorTree &DT)
TransformForPostIncUse - Transform the given expression according to the given transformation kind...
const Instruction & back() const
Definition: BasicBlock.h:242
bool isOne() const
Return true if the expression is a constant one.
NodeTy * getNextNode()
Get the next node, or nullptr for the list tail.
Definition: ilist_node.h:274
const SCEV * getConstant(ConstantInt *V)
size_t i
LLVMContext & getContext() const
bool isZero() const
Return true if the expression is a constant zero.
unsigned getNumOperands() const
Definition: User.h:167
The main scalar evolution driver.
This class represents a function call, abstracting a target machine's calling convention.
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:655
unsigned less than
Definition: InstrTypes.h:905
bool mayHaveSideEffects() const
Return true if the instruction may have side effects.
Definition: Instruction.h:450
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:1126
const SCEV * getStepRecurrence(ScalarEvolution &SE) const
Constructs and returns the recurrence indicating how much this expression steps by.
Optional< ScalarEvolution::ValueOffsetPair > getRelatedExistingExpansion(const SCEV *S, const Instruction *At, Loop *L)
Try to find the ValueOffsetPair for S.
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...
LoopT * getParentLoop() const
Definition: LoopInfo.h:103
A debug info location.
Definition: DebugLoc.h:34
const Instruction & front() const
Definition: BasicBlock.h:240
unsigned getAddressSpace() const
Return the address space of the Pointer type.
Definition: DerivedTypes.h:471
Hexagon Common GEP
Type * getElementType() const
Definition: DerivedTypes.h:462
op_iterator op_begin()
Definition: User.h:205
BlockT * getHeader() const
Definition: LoopInfo.h:102
This is the base class for unary cast operator classes.
return AArch64::GPR64RegClass contains(Reg)
Type * getPointerElementType() const
Definition: Type.h:358
const SCEV * getStart() const
static Constant * getNullValue(Type *Ty)
Constructor to create a '0' constant of arbitrary type.
Definition: Constants.cpp:195
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:191
BlockT * getLoopLatch() const
If there is a single latch block for this loop, return it.
Definition: LoopInfoImpl.h:157
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:345
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:228
#define DEBUG_WITH_TYPE(TYPE, X)
DEBUG_WITH_TYPE macro - This macro should be used by passes to emit debug information.
Definition: Debug.h:69
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:41
Used to lazily calculate structure layout information for a target machine, based on the DataLayout s...
Definition: DataLayout.h:496
Hexagon Hardware Loops
Value * expandCodeForPredicate(const SCEVPredicate *Pred, Instruction *Loc)
Generates a code sequence that evaluates this predicate.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
static const Loop * PickMostRelevantLoop(const Loop *A, const Loop *B, DominatorTree &DT)
PickMostRelevantLoop - Given two loops pick the one that's most relevant for SCEV expansion...
This is the base class for all instructions that perform data casts.
Definition: InstrTypes.h:578
Class to represent struct types.
Definition: DerivedTypes.h:199
A Use represents the edge between a Value definition and its users.
Definition: Use.h:56
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:32
static GCRegistry::Add< StatepointGC > D("statepoint-example","an example strategy for statepoint")
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:588
void getExitingBlocks(SmallVectorImpl< BlockT * > &ExitingBlocks) const
Return all blocks inside the loop that have successors outside of the loop.
Definition: LoopInfoImpl.h:36
Windows NT (Windows on ARM)
op_iterator op_begin() const
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.
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:60
static Constant * get(unsigned Opcode, Constant *C1, Constant *C2, unsigned Flags=0, Type *OnlyIfReducedTy=nullptr)
get - Return a binary or shift operator constant expression, folding if possible. ...
Definition: Constants.cpp:1728
A constant value that is initialized with an expression using other constant values.
Definition: Constants.h:873
LLVMContext & getContext() const
Return the LLVMContext in which this type was uniqued.
Definition: Type.h:128
This node represents a polynomial recurrence on the trip count of the specified loop.
static Value * SimplifyPHINode(PHINode *PN, const Query &Q)
See if we can fold the given phi. If not, returns null.
const T & getValue() const LLVM_LVALUE_FUNCTION
Definition: Optional.h:121
Class to represent array types.
Definition: DerivedTypes.h:345
Function Alias Analysis false
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:949
static GCRegistry::Add< OcamlGC > B("ocaml","ocaml 3.10-compatible GC")
const Function * getFunction() const
Return the function this instruction belongs to.
Definition: Instruction.cpp:68
void SetCurrentDebugLocation(DebugLoc L)
Set location information used by debugging information.
Definition: IRBuilder.h:151
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:401
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power of 2.
Definition: PatternMatch.h:272
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...
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:263
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:96
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)
Class to represent pointers.
Definition: DerivedTypes.h:443
static GCRegistry::Add< CoreCLRGC > E("coreclr","CoreCLR-compatible GC")
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:517
bool isSized(SmallPtrSetImpl< Type * > *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:254
This means that we are dealing with an entirely unknown SCEV value, and only represent it as its LLVM...
bool isAffine() const
Return true if this represents an expression A + B*x where A and B are loop invariant values...
void setDebugLoc(DebugLoc Loc)
Set the debug location information for this instruction.
Definition: Instruction.h:256
BlockT * getLoopPreheader() const
If there is a preheader for this loop, return it.
Definition: LoopInfoImpl.h:109
LLVM Basic Block Representation.
Definition: BasicBlock.h:51
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
Type * getType() const
Return the LLVM type of this SCEV expression.
static void SplitAddRecs(SmallVectorImpl< const SCEV * > &Ops, Type *Ty, ScalarEvolution &SE)
SplitAddRecs - Flatten a list of add operands, moving addrec start values out to the top level...
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:219
This is an important base class in LLVM.
Definition: Constant.h:42
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator begin()
Definition: SmallVector.h:115
const SCEV * getOperand(unsigned i) const
SmallSet - This maintains a set of unique values, optimizing for the case when the set is small (less...
Definition: SmallSet.h:36
#define H(x, y, z)
Definition: MD5.cpp:53
Normalize - Normalize according to the given loops.
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:368
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:116
bool isIllegalInteger(uint64_t Width) const
Definition: DataLayout.h:249
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:259
brc_match< Cond_t > m_Br(const Cond_t &C, BasicBlock *&T, BasicBlock *&F)
Definition: PatternMatch.h:942
op_iterator op_end()
Definition: User.h:207
const SCEVUnknown * getLHS() const
Returns the left hand side of the equality.
bool contains(const LoopT *L) const
Return true if the specified loop is contained within in this loop.
Definition: LoopInfo.h:109
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:743
uint32_t Offset
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang","erlang-compatible garbage collector")
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:880
static bool FactorOutConstant(const SCEV *&S, const SCEV *&Remainder, const SCEV *Factor, ScalarEvolution &SE, const DataLayout &DL)
FactorOutConstant - Test if S is divisible by Factor, using signed division.
Value * expandCodeFor(const SCEV *SH, Type *Ty, Instruction *I)
Insert code to directly compute the specified SCEV expression into the program.
BlockT * getExitingBlock() const
If getExitingBlocks would return exactly one block, return that block.
Definition: LoopInfoImpl.h:52
Value * getOperand(unsigned i) const
Definition: User.h:145
Interval::pred_iterator pred_end(Interval *I)
Definition: Interval.h:119
self_iterator getIterator()
Definition: ilist_node.h:81
unsigned getIntegerBitWidth() const
Definition: DerivedTypes.h:96
Class to represent integer types.
Definition: DerivedTypes.h:39
std::pair< NoneType, bool > insert(const T &V)
insert - Insert an element into the set if it isn't already there.
Definition: SmallSet.h:80
static Expected< BitVector > expand(StringRef S, StringRef Original)
Definition: GlobPattern.cpp:28
const SCEV * getLHS() const
static void SimplifyAddOperands(SmallVectorImpl< const SCEV * > &Ops, Type *Ty, ScalarEvolution &SE)
SimplifyAddOperands - Sort and simplify a list of add operands.
const APInt & getAPInt() const
void append(in_iter in_start, in_iter in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:392
bool isPointerTy() const
True if this is an instance of PointerType.
Definition: Type.h:213
static UndefValue * get(Type *T)
Static factory methods - Return an 'undef' object of the specified type.
Definition: Constants.cpp:1337
bool isNonConstantNegative() const
Return true if the specified scev is negated, but not a constant.
SCEVPredicateKind getKind() const
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:654
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:213
bool isPowerOf2() const
Check if this APInt's value is a power of two greater than zero.
Definition: APInt.h:391
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
const SCEV * getRHS() const
signed greater than
Definition: InstrTypes.h:907
This class represents an assumption made using SCEV expressions which can be checked at run-time...
static bool IsIncrementNSW(ScalarEvolution &SE, const SCEVAddRecExpr *AR)
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:218
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...
unsigned replaceCongruentIVs(Loop *L, const DominatorTree *DT, SmallVectorImpl< WeakVH > &DeadInsts, const TargetTransformInfo *TTI=nullptr)
replace congruent phis with their most canonical representative.
static IntegerType * get(LLVMContext &C, unsigned NumBits)
This static method is the primary way of constructing an IntegerType.
Definition: Type.cpp:234
const SCEVConstant * getRHS() const
Returns the right hand side of the equality.
Iterator for intrusive lists based on ilist_node.
static PointerType * getInt1PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:209
This is the shared class of boolean and integer constants.
Definition: Constants.h:88
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:58
unsigned logBase2() const
Definition: APInt.h:1507
PHINode * getOrInsertCanonicalInductionVariable(const Loop *L, Type *Ty)
This method returns the canonical induction variable of the specified type for the specified loop (in...
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:843
bool isAllOnesValue() const
Return true if the expression is a constant all-ones value.
Module.h This file contains the declarations for the Module class.
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:230
signed less than
Definition: InstrTypes.h:909
CHAIN = SC CHAIN, Imm128 - System call.
uint64_t getSizeInBytes() const
Definition: DataLayout.h:503
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:110
unsigned getElementContainingOffset(uint64_t Offset) const
Given a valid byte offset into the structure, returns the structure index that contains it...
Definition: DataLayout.cpp:79
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:558
static ConstantInt * getSigned(IntegerType *Ty, int64_t V)
Return a ConstantInt with the specified value for the specified type.
Definition: Constants.cpp:572
bool isZero() const
This is just a convenience method to make client code smaller for a common code.
Definition: Constants.h:198
static PHINode * Create(Type *Ty, unsigned NumReservedValues, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Constructors - NumReservedValues is a hint for the number of incoming edges that this phi node will h...
ConstantInt * getValue() const
static GCRegistry::Add< ShadowStackGC > C("shadow-stack","Very portable GC for uncooperative code generators")
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:586
Class for arbitrary precision integers.
Definition: APInt.h:77
This node represents an addition of some number of SCEVs.
static BasicBlock::iterator findInsertPointAfter(Instruction *I, BasicBlock *MustDominate)
const SCEV * getSignExtendExpr(const SCEV *Op, Type *Ty)
Value * getIncomingValueForBlock(const BasicBlock *BB) const
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:195
This class represents a signed maximum selection.
iterator_range< user_iterator > users()
Definition: Value.h:370
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:1452
const SCEV * getAddExpr(SmallVectorImpl< const SCEV * > &Ops, SCEV::NoWrapFlags Flags=SCEV::FlagAnyWrap)
Get a canonical add expression, or something simpler if possible.
void visitAll(const SCEV *Root, SV &Visitor)
Use SCEVTraversal to visit all nodes in the given expression tree.
static APInt getMaxValue(unsigned numBits)
Gets maximum unsigned value of APInt for specific bit width.
Definition: APInt.h:426
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:1386
static bool IsIncrementNUW(ScalarEvolution &SE, const SCEVAddRecExpr *AR)
static CastInst * Create(Instruction::CastOps, Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Provides a way to construct any of the CastInst subclasses using an opcode instead of the subclass's ...
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator end()
Definition: SmallVector.h:119
void emplace_back(ArgTypes &&...Args)
Definition: SmallVector.h:635
This class represents an analyzed expression in the program.
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:169
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:368
static Instruction::CastOps getCastOpcode(const Value *Val, bool SrcIsSigned, Type *Ty, bool DstIsSigned)
Returns the opcode necessary to cast Val into Ty using usual casting rules.
#define I(x, y, z)
Definition: MD5.cpp:54
#define N
TerminatorInst * getTerminator()
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:124
LLVM_ATTRIBUTE_ALWAYS_INLINE size_type size() const
Definition: SmallVector.h:135
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:287
Instruction * getIVIncOperand(Instruction *IncV, Instruction *InsertPos, bool allowScale)
Return the induction variable increment's IV operand.
static volatile int Zero
const Loop * getLoop() const
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This class represents a composition of other SCEV predicates, and is the class that most clients will...
unsigned getSCEVType() const
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:108
const SCEV * getNegativeSCEV(const SCEV *V, SCEV::NoWrapFlags Flags=SCEV::FlagAnyWrap)
Return the SCEV object corresponding to -V.
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:71
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:111
A vector that has set insertion semantics.
Definition: SetVector.h:41
void moveBefore(Instruction *MovePos)
Unlink this instruction from its current basic block and insert it into the basic block that MovePos ...
Definition: Instruction.cpp:95
bool isTruncateFree(Type *Ty1, Type *Ty2) const
Return true if it's free to truncate a value of type Ty1 to type Ty2.
op_iterator op_end() const
unsigned greater than
Definition: InstrTypes.h:903
APInt zext(unsigned width) const
Zero extend to a new width.
Definition: APInt.cpp:980
Value * SimplifyInstruction(Instruction *I, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr)
See if we can compute a simplified version of this instruction.
This pass exposes codegen information to IR-level passes.
iterator getFirstInsertionPt()
Returns an iterator to the first instruction in this block that is suitable for inserting a non-PHI i...
Definition: BasicBlock.cpp:209
static APInt getNullValue(unsigned numBits)
Get the '0' value.
Definition: APInt.h:465
const SCEV * getZeroExtendExpr(const SCEV *Op, Type *Ty)
This node is a base class providing common functionality for n'ary operators.
This class represents an assumption made on an AddRec expression.
int64_t getSExtValue() const
Return the constant as a 64-bit integer value after it has been sign extended as appropriate for the ...
Definition: Constants.h:162
bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE)
Return true if the given expression is safe to expand in the sense that all materialized values are s...
const SCEV * getOperand() const
static GCRegistry::Add< ErlangGC > A("erlang","erlang-compatible garbage collector")
const SCEV * getMulExpr(SmallVectorImpl< const SCEV * > &Ops, SCEV::NoWrapFlags Flags=SCEV::FlagAnyWrap)
Get a canonical multiply expression, or something simpler if possible.
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:167
const BasicBlock * getParent() const
Definition: Instruction.h:62
const SmallVectorImpl< const SCEVPredicate * > & getPredicates() const
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:300
static bool canBeCheaplyTransformed(ScalarEvolution &SE, const SCEVAddRecExpr *Phi, const SCEVAddRecExpr *Requested, bool &InvertStep)
Check whether we can cheaply express the requested SCEV in terms of the available PHI SCEV by truncat...
This class represents a constant integer value.
CmpClass_match< LHS, RHS, ICmpInst, ICmpInst::Predicate > m_ICmp(ICmpInst::Predicate &Pred, const LHS &L, const RHS &R)
Definition: PatternMatch.h:726