LLVM  3.7.0
InstCombineCompares.cpp
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1 //===- InstCombineCompares.cpp --------------------------------------------===//
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 implements the visitICmp and visitFCmp functions.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "InstCombineInternal.h"
15 #include "llvm/ADT/APSInt.h"
16 #include "llvm/ADT/Statistic.h"
20 #include "llvm/IR/ConstantRange.h"
21 #include "llvm/IR/DataLayout.h"
23 #include "llvm/IR/IntrinsicInst.h"
24 #include "llvm/IR/PatternMatch.h"
26 #include "llvm/Support/Debug.h"
28 
29 using namespace llvm;
30 using namespace PatternMatch;
31 
32 #define DEBUG_TYPE "instcombine"
33 
34 // How many times is a select replaced by one of its operands?
35 STATISTIC(NumSel, "Number of select opts");
36 
37 // Initialization Routines
38 
40  return ConstantInt::get(cast<IntegerType>(C->getType()), 1);
41 }
42 
44  return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
45 }
46 
47 static bool HasAddOverflow(ConstantInt *Result,
48  ConstantInt *In1, ConstantInt *In2,
49  bool IsSigned) {
50  if (!IsSigned)
51  return Result->getValue().ult(In1->getValue());
52 
53  if (In2->isNegative())
54  return Result->getValue().sgt(In1->getValue());
55  return Result->getValue().slt(In1->getValue());
56 }
57 
58 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
59 /// overflowed for this type.
60 static bool AddWithOverflow(Constant *&Result, Constant *In1,
61  Constant *In2, bool IsSigned = false) {
62  Result = ConstantExpr::getAdd(In1, In2);
63 
64  if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
65  for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
67  if (HasAddOverflow(ExtractElement(Result, Idx),
68  ExtractElement(In1, Idx),
69  ExtractElement(In2, Idx),
70  IsSigned))
71  return true;
72  }
73  return false;
74  }
75 
76  return HasAddOverflow(cast<ConstantInt>(Result),
77  cast<ConstantInt>(In1), cast<ConstantInt>(In2),
78  IsSigned);
79 }
80 
81 static bool HasSubOverflow(ConstantInt *Result,
82  ConstantInt *In1, ConstantInt *In2,
83  bool IsSigned) {
84  if (!IsSigned)
85  return Result->getValue().ugt(In1->getValue());
86 
87  if (In2->isNegative())
88  return Result->getValue().slt(In1->getValue());
89 
90  return Result->getValue().sgt(In1->getValue());
91 }
92 
93 /// SubWithOverflow - Compute Result = In1-In2, returning true if the result
94 /// overflowed for this type.
95 static bool SubWithOverflow(Constant *&Result, Constant *In1,
96  Constant *In2, bool IsSigned = false) {
97  Result = ConstantExpr::getSub(In1, In2);
98 
99  if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
100  for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
102  if (HasSubOverflow(ExtractElement(Result, Idx),
103  ExtractElement(In1, Idx),
104  ExtractElement(In2, Idx),
105  IsSigned))
106  return true;
107  }
108  return false;
109  }
110 
111  return HasSubOverflow(cast<ConstantInt>(Result),
112  cast<ConstantInt>(In1), cast<ConstantInt>(In2),
113  IsSigned);
114 }
115 
116 /// isSignBitCheck - Given an exploded icmp instruction, return true if the
117 /// comparison only checks the sign bit. If it only checks the sign bit, set
118 /// TrueIfSigned if the result of the comparison is true when the input value is
119 /// signed.
121  bool &TrueIfSigned) {
122  switch (pred) {
123  case ICmpInst::ICMP_SLT: // True if LHS s< 0
124  TrueIfSigned = true;
125  return RHS->isZero();
126  case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
127  TrueIfSigned = true;
128  return RHS->isAllOnesValue();
129  case ICmpInst::ICMP_SGT: // True if LHS s> -1
130  TrueIfSigned = false;
131  return RHS->isAllOnesValue();
132  case ICmpInst::ICMP_UGT:
133  // True if LHS u> RHS and RHS == high-bit-mask - 1
134  TrueIfSigned = true;
135  return RHS->isMaxValue(true);
136  case ICmpInst::ICMP_UGE:
137  // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
138  TrueIfSigned = true;
139  return RHS->getValue().isSignBit();
140  default:
141  return false;
142  }
143 }
144 
145 /// Returns true if the exploded icmp can be expressed as a signed comparison
146 /// to zero and updates the predicate accordingly.
147 /// The signedness of the comparison is preserved.
148 static bool isSignTest(ICmpInst::Predicate &pred, const ConstantInt *RHS) {
149  if (!ICmpInst::isSigned(pred))
150  return false;
151 
152  if (RHS->isZero())
153  return ICmpInst::isRelational(pred);
154 
155  if (RHS->isOne()) {
156  if (pred == ICmpInst::ICMP_SLT) {
157  pred = ICmpInst::ICMP_SLE;
158  return true;
159  }
160  } else if (RHS->isAllOnesValue()) {
161  if (pred == ICmpInst::ICMP_SGT) {
162  pred = ICmpInst::ICMP_SGE;
163  return true;
164  }
165  }
166 
167  return false;
168 }
169 
170 // isHighOnes - Return true if the constant is of the form 1+0+.
171 // This is the same as lowones(~X).
172 static bool isHighOnes(const ConstantInt *CI) {
173  return (~CI->getValue() + 1).isPowerOf2();
174 }
175 
176 /// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
177 /// set of known zero and one bits, compute the maximum and minimum values that
178 /// could have the specified known zero and known one bits, returning them in
179 /// min/max.
180 static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
181  const APInt& KnownOne,
182  APInt& Min, APInt& Max) {
183  assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
184  KnownZero.getBitWidth() == Min.getBitWidth() &&
185  KnownZero.getBitWidth() == Max.getBitWidth() &&
186  "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
187  APInt UnknownBits = ~(KnownZero|KnownOne);
188 
189  // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
190  // bit if it is unknown.
191  Min = KnownOne;
192  Max = KnownOne|UnknownBits;
193 
194  if (UnknownBits.isNegative()) { // Sign bit is unknown
195  Min.setBit(Min.getBitWidth()-1);
196  Max.clearBit(Max.getBitWidth()-1);
197  }
198 }
199 
200 // ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
201 // a set of known zero and one bits, compute the maximum and minimum values that
202 // could have the specified known zero and known one bits, returning them in
203 // min/max.
204 static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
205  const APInt &KnownOne,
206  APInt &Min, APInt &Max) {
207  assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
208  KnownZero.getBitWidth() == Min.getBitWidth() &&
209  KnownZero.getBitWidth() == Max.getBitWidth() &&
210  "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
211  APInt UnknownBits = ~(KnownZero|KnownOne);
212 
213  // The minimum value is when the unknown bits are all zeros.
214  Min = KnownOne;
215  // The maximum value is when the unknown bits are all ones.
216  Max = KnownOne|UnknownBits;
217 }
218 
219 
220 
221 /// FoldCmpLoadFromIndexedGlobal - Called we see this pattern:
222 /// cmp pred (load (gep GV, ...)), cmpcst
223 /// where GV is a global variable with a constant initializer. Try to simplify
224 /// this into some simple computation that does not need the load. For example
225 /// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
226 ///
227 /// If AndCst is non-null, then the loaded value is masked with that constant
228 /// before doing the comparison. This handles cases like "A[i]&4 == 0".
231  CmpInst &ICI, ConstantInt *AndCst) {
232  Constant *Init = GV->getInitializer();
233  if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init))
234  return nullptr;
235 
236  uint64_t ArrayElementCount = Init->getType()->getArrayNumElements();
237  if (ArrayElementCount > 1024) return nullptr; // Don't blow up on huge arrays.
238 
239  // There are many forms of this optimization we can handle, for now, just do
240  // the simple index into a single-dimensional array.
241  //
242  // Require: GEP GV, 0, i {{, constant indices}}
243  if (GEP->getNumOperands() < 3 ||
244  !isa<ConstantInt>(GEP->getOperand(1)) ||
245  !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
246  isa<Constant>(GEP->getOperand(2)))
247  return nullptr;
248 
249  // Check that indices after the variable are constants and in-range for the
250  // type they index. Collect the indices. This is typically for arrays of
251  // structs.
252  SmallVector<unsigned, 4> LaterIndices;
253 
254  Type *EltTy = Init->getType()->getArrayElementType();
255  for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
256  ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
257  if (!Idx) return nullptr; // Variable index.
258 
259  uint64_t IdxVal = Idx->getZExtValue();
260  if ((unsigned)IdxVal != IdxVal) return nullptr; // Too large array index.
261 
262  if (StructType *STy = dyn_cast<StructType>(EltTy))
263  EltTy = STy->getElementType(IdxVal);
264  else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
265  if (IdxVal >= ATy->getNumElements()) return nullptr;
266  EltTy = ATy->getElementType();
267  } else {
268  return nullptr; // Unknown type.
269  }
270 
271  LaterIndices.push_back(IdxVal);
272  }
273 
274  enum { Overdefined = -3, Undefined = -2 };
275 
276  // Variables for our state machines.
277 
278  // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
279  // "i == 47 | i == 87", where 47 is the first index the condition is true for,
280  // and 87 is the second (and last) index. FirstTrueElement is -2 when
281  // undefined, otherwise set to the first true element. SecondTrueElement is
282  // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
283  int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
284 
285  // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
286  // form "i != 47 & i != 87". Same state transitions as for true elements.
287  int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
288 
289  /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
290  /// define a state machine that triggers for ranges of values that the index
291  /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
292  /// This is -2 when undefined, -3 when overdefined, and otherwise the last
293  /// index in the range (inclusive). We use -2 for undefined here because we
294  /// use relative comparisons and don't want 0-1 to match -1.
295  int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
296 
297  // MagicBitvector - This is a magic bitvector where we set a bit if the
298  // comparison is true for element 'i'. If there are 64 elements or less in
299  // the array, this will fully represent all the comparison results.
300  uint64_t MagicBitvector = 0;
301 
302  // Scan the array and see if one of our patterns matches.
303  Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
304  for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) {
305  Constant *Elt = Init->getAggregateElement(i);
306  if (!Elt) return nullptr;
307 
308  // If this is indexing an array of structures, get the structure element.
309  if (!LaterIndices.empty())
310  Elt = ConstantExpr::getExtractValue(Elt, LaterIndices);
311 
312  // If the element is masked, handle it.
313  if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
314 
315  // Find out if the comparison would be true or false for the i'th element.
317  CompareRHS, DL, TLI);
318  // If the result is undef for this element, ignore it.
319  if (isa<UndefValue>(C)) {
320  // Extend range state machines to cover this element in case there is an
321  // undef in the middle of the range.
322  if (TrueRangeEnd == (int)i-1)
323  TrueRangeEnd = i;
324  if (FalseRangeEnd == (int)i-1)
325  FalseRangeEnd = i;
326  continue;
327  }
328 
329  // If we can't compute the result for any of the elements, we have to give
330  // up evaluating the entire conditional.
331  if (!isa<ConstantInt>(C)) return nullptr;
332 
333  // Otherwise, we know if the comparison is true or false for this element,
334  // update our state machines.
335  bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
336 
337  // State machine for single/double/range index comparison.
338  if (IsTrueForElt) {
339  // Update the TrueElement state machine.
340  if (FirstTrueElement == Undefined)
341  FirstTrueElement = TrueRangeEnd = i; // First true element.
342  else {
343  // Update double-compare state machine.
344  if (SecondTrueElement == Undefined)
345  SecondTrueElement = i;
346  else
347  SecondTrueElement = Overdefined;
348 
349  // Update range state machine.
350  if (TrueRangeEnd == (int)i-1)
351  TrueRangeEnd = i;
352  else
353  TrueRangeEnd = Overdefined;
354  }
355  } else {
356  // Update the FalseElement state machine.
357  if (FirstFalseElement == Undefined)
358  FirstFalseElement = FalseRangeEnd = i; // First false element.
359  else {
360  // Update double-compare state machine.
361  if (SecondFalseElement == Undefined)
362  SecondFalseElement = i;
363  else
364  SecondFalseElement = Overdefined;
365 
366  // Update range state machine.
367  if (FalseRangeEnd == (int)i-1)
368  FalseRangeEnd = i;
369  else
370  FalseRangeEnd = Overdefined;
371  }
372  }
373 
374 
375  // If this element is in range, update our magic bitvector.
376  if (i < 64 && IsTrueForElt)
377  MagicBitvector |= 1ULL << i;
378 
379  // If all of our states become overdefined, bail out early. Since the
380  // predicate is expensive, only check it every 8 elements. This is only
381  // really useful for really huge arrays.
382  if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
383  SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
384  FalseRangeEnd == Overdefined)
385  return nullptr;
386  }
387 
388  // Now that we've scanned the entire array, emit our new comparison(s). We
389  // order the state machines in complexity of the generated code.
390  Value *Idx = GEP->getOperand(2);
391 
392  // If the index is larger than the pointer size of the target, truncate the
393  // index down like the GEP would do implicitly. We don't have to do this for
394  // an inbounds GEP because the index can't be out of range.
395  if (!GEP->isInBounds()) {
396  Type *IntPtrTy = DL.getIntPtrType(GEP->getType());
397  unsigned PtrSize = IntPtrTy->getIntegerBitWidth();
398  if (Idx->getType()->getPrimitiveSizeInBits() > PtrSize)
399  Idx = Builder->CreateTrunc(Idx, IntPtrTy);
400  }
401 
402  // If the comparison is only true for one or two elements, emit direct
403  // comparisons.
404  if (SecondTrueElement != Overdefined) {
405  // None true -> false.
406  if (FirstTrueElement == Undefined)
407  return ReplaceInstUsesWith(ICI, Builder->getFalse());
408 
409  Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
410 
411  // True for one element -> 'i == 47'.
412  if (SecondTrueElement == Undefined)
413  return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
414 
415  // True for two elements -> 'i == 47 | i == 72'.
416  Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx);
417  Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
418  Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx);
419  return BinaryOperator::CreateOr(C1, C2);
420  }
421 
422  // If the comparison is only false for one or two elements, emit direct
423  // comparisons.
424  if (SecondFalseElement != Overdefined) {
425  // None false -> true.
426  if (FirstFalseElement == Undefined)
427  return ReplaceInstUsesWith(ICI, Builder->getTrue());
428 
429  Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
430 
431  // False for one element -> 'i != 47'.
432  if (SecondFalseElement == Undefined)
433  return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
434 
435  // False for two elements -> 'i != 47 & i != 72'.
436  Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx);
437  Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
438  Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx);
439  return BinaryOperator::CreateAnd(C1, C2);
440  }
441 
442  // If the comparison can be replaced with a range comparison for the elements
443  // where it is true, emit the range check.
444  if (TrueRangeEnd != Overdefined) {
445  assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare");
446 
447  // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
448  if (FirstTrueElement) {
449  Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
450  Idx = Builder->CreateAdd(Idx, Offs);
451  }
452 
453  Value *End = ConstantInt::get(Idx->getType(),
454  TrueRangeEnd-FirstTrueElement+1);
455  return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
456  }
457 
458  // False range check.
459  if (FalseRangeEnd != Overdefined) {
460  assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare");
461  // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
462  if (FirstFalseElement) {
463  Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
464  Idx = Builder->CreateAdd(Idx, Offs);
465  }
466 
467  Value *End = ConstantInt::get(Idx->getType(),
468  FalseRangeEnd-FirstFalseElement);
469  return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
470  }
471 
472 
473  // If a magic bitvector captures the entire comparison state
474  // of this load, replace it with computation that does:
475  // ((magic_cst >> i) & 1) != 0
476  {
477  Type *Ty = nullptr;
478 
479  // Look for an appropriate type:
480  // - The type of Idx if the magic fits
481  // - The smallest fitting legal type if we have a DataLayout
482  // - Default to i32
483  if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth())
484  Ty = Idx->getType();
485  else
486  Ty = DL.getSmallestLegalIntType(Init->getContext(), ArrayElementCount);
487 
488  if (Ty) {
489  Value *V = Builder->CreateIntCast(Idx, Ty, false);
490  V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
491  V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V);
492  return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
493  }
494  }
495 
496  return nullptr;
497 }
498 
499 
500 /// EvaluateGEPOffsetExpression - Return a value that can be used to compare
501 /// the *offset* implied by a GEP to zero. For example, if we have &A[i], we
502 /// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can
503 /// be complex, and scales are involved. The above expression would also be
504 /// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).
505 /// This later form is less amenable to optimization though, and we are allowed
506 /// to generate the first by knowing that pointer arithmetic doesn't overflow.
507 ///
508 /// If we can't emit an optimized form for this expression, this returns null.
509 ///
511  const DataLayout &DL) {
513 
514  // Check to see if this gep only has a single variable index. If so, and if
515  // any constant indices are a multiple of its scale, then we can compute this
516  // in terms of the scale of the variable index. For example, if the GEP
517  // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
518  // because the expression will cross zero at the same point.
519  unsigned i, e = GEP->getNumOperands();
520  int64_t Offset = 0;
521  for (i = 1; i != e; ++i, ++GTI) {
522  if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
523  // Compute the aggregate offset of constant indices.
524  if (CI->isZero()) continue;
525 
526  // Handle a struct index, which adds its field offset to the pointer.
527  if (StructType *STy = dyn_cast<StructType>(*GTI)) {
528  Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
529  } else {
530  uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
531  Offset += Size*CI->getSExtValue();
532  }
533  } else {
534  // Found our variable index.
535  break;
536  }
537  }
538 
539  // If there are no variable indices, we must have a constant offset, just
540  // evaluate it the general way.
541  if (i == e) return nullptr;
542 
543  Value *VariableIdx = GEP->getOperand(i);
544  // Determine the scale factor of the variable element. For example, this is
545  // 4 if the variable index is into an array of i32.
546  uint64_t VariableScale = DL.getTypeAllocSize(GTI.getIndexedType());
547 
548  // Verify that there are no other variable indices. If so, emit the hard way.
549  for (++i, ++GTI; i != e; ++i, ++GTI) {
550  ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
551  if (!CI) return nullptr;
552 
553  // Compute the aggregate offset of constant indices.
554  if (CI->isZero()) continue;
555 
556  // Handle a struct index, which adds its field offset to the pointer.
557  if (StructType *STy = dyn_cast<StructType>(*GTI)) {
558  Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
559  } else {
560  uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
561  Offset += Size*CI->getSExtValue();
562  }
563  }
564 
565 
566 
567  // Okay, we know we have a single variable index, which must be a
568  // pointer/array/vector index. If there is no offset, life is simple, return
569  // the index.
570  Type *IntPtrTy = DL.getIntPtrType(GEP->getOperand(0)->getType());
571  unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth();
572  if (Offset == 0) {
573  // Cast to intptrty in case a truncation occurs. If an extension is needed,
574  // we don't need to bother extending: the extension won't affect where the
575  // computation crosses zero.
576  if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) {
577  VariableIdx = IC.Builder->CreateTrunc(VariableIdx, IntPtrTy);
578  }
579  return VariableIdx;
580  }
581 
582  // Otherwise, there is an index. The computation we will do will be modulo
583  // the pointer size, so get it.
584  uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
585 
586  Offset &= PtrSizeMask;
587  VariableScale &= PtrSizeMask;
588 
589  // To do this transformation, any constant index must be a multiple of the
590  // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
591  // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
592  // multiple of the variable scale.
593  int64_t NewOffs = Offset / (int64_t)VariableScale;
594  if (Offset != NewOffs*(int64_t)VariableScale)
595  return nullptr;
596 
597  // Okay, we can do this evaluation. Start by converting the index to intptr.
598  if (VariableIdx->getType() != IntPtrTy)
599  VariableIdx = IC.Builder->CreateIntCast(VariableIdx, IntPtrTy,
600  true /*Signed*/);
601  Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
602  return IC.Builder->CreateAdd(VariableIdx, OffsetVal, "offset");
603 }
604 
605 /// FoldGEPICmp - Fold comparisons between a GEP instruction and something
606 /// else. At this point we know that the GEP is on the LHS of the comparison.
608  ICmpInst::Predicate Cond,
609  Instruction &I) {
610  // Don't transform signed compares of GEPs into index compares. Even if the
611  // GEP is inbounds, the final add of the base pointer can have signed overflow
612  // and would change the result of the icmp.
613  // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be
614  // the maximum signed value for the pointer type.
615  if (ICmpInst::isSigned(Cond))
616  return nullptr;
617 
618  // Look through bitcasts and addrspacecasts. We do not however want to remove
619  // 0 GEPs.
620  if (!isa<GetElementPtrInst>(RHS))
621  RHS = RHS->stripPointerCasts();
622 
623  Value *PtrBase = GEPLHS->getOperand(0);
624  if (PtrBase == RHS && GEPLHS->isInBounds()) {
625  // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
626  // This transformation (ignoring the base and scales) is valid because we
627  // know pointers can't overflow since the gep is inbounds. See if we can
628  // output an optimized form.
629  Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, *this, DL);
630 
631  // If not, synthesize the offset the hard way.
632  if (!Offset)
633  Offset = EmitGEPOffset(GEPLHS);
634  return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
635  Constant::getNullValue(Offset->getType()));
636  } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
637  // If the base pointers are different, but the indices are the same, just
638  // compare the base pointer.
639  if (PtrBase != GEPRHS->getOperand(0)) {
640  bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
641  IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
642  GEPRHS->getOperand(0)->getType();
643  if (IndicesTheSame)
644  for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
645  if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
646  IndicesTheSame = false;
647  break;
648  }
649 
650  // If all indices are the same, just compare the base pointers.
651  if (IndicesTheSame)
652  return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0));
653 
654  // If we're comparing GEPs with two base pointers that only differ in type
655  // and both GEPs have only constant indices or just one use, then fold
656  // the compare with the adjusted indices.
657  if (GEPLHS->isInBounds() && GEPRHS->isInBounds() &&
658  (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) &&
659  (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) &&
660  PtrBase->stripPointerCasts() ==
661  GEPRHS->getOperand(0)->stripPointerCasts()) {
662  Value *LOffset = EmitGEPOffset(GEPLHS);
663  Value *ROffset = EmitGEPOffset(GEPRHS);
664 
665  // If we looked through an addrspacecast between different sized address
666  // spaces, the LHS and RHS pointers are different sized
667  // integers. Truncate to the smaller one.
668  Type *LHSIndexTy = LOffset->getType();
669  Type *RHSIndexTy = ROffset->getType();
670  if (LHSIndexTy != RHSIndexTy) {
671  if (LHSIndexTy->getPrimitiveSizeInBits() <
672  RHSIndexTy->getPrimitiveSizeInBits()) {
673  ROffset = Builder->CreateTrunc(ROffset, LHSIndexTy);
674  } else
675  LOffset = Builder->CreateTrunc(LOffset, RHSIndexTy);
676  }
677 
678  Value *Cmp = Builder->CreateICmp(ICmpInst::getSignedPredicate(Cond),
679  LOffset, ROffset);
680  return ReplaceInstUsesWith(I, Cmp);
681  }
682 
683  // Otherwise, the base pointers are different and the indices are
684  // different, bail out.
685  return nullptr;
686  }
687 
688  // If one of the GEPs has all zero indices, recurse.
689  if (GEPLHS->hasAllZeroIndices())
690  return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
692 
693  // If the other GEP has all zero indices, recurse.
694  if (GEPRHS->hasAllZeroIndices())
695  return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
696 
697  bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds();
698  if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
699  // If the GEPs only differ by one index, compare it.
700  unsigned NumDifferences = 0; // Keep track of # differences.
701  unsigned DiffOperand = 0; // The operand that differs.
702  for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
703  if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
704  if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
705  GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
706  // Irreconcilable differences.
707  NumDifferences = 2;
708  break;
709  } else {
710  if (NumDifferences++) break;
711  DiffOperand = i;
712  }
713  }
714 
715  if (NumDifferences == 0) // SAME GEP?
716  return ReplaceInstUsesWith(I, // No comparison is needed here.
717  Builder->getInt1(ICmpInst::isTrueWhenEqual(Cond)));
718 
719  else if (NumDifferences == 1 && GEPsInBounds) {
720  Value *LHSV = GEPLHS->getOperand(DiffOperand);
721  Value *RHSV = GEPRHS->getOperand(DiffOperand);
722  // Make sure we do a signed comparison here.
723  return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
724  }
725  }
726 
727  // Only lower this if the icmp is the only user of the GEP or if we expect
728  // the result to fold to a constant!
729  if (GEPsInBounds && (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
730  (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
731  // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
732  Value *L = EmitGEPOffset(GEPLHS);
733  Value *R = EmitGEPOffset(GEPRHS);
734  return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
735  }
736  }
737  return nullptr;
738 }
739 
740 /// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X".
742  Value *X, ConstantInt *CI,
743  ICmpInst::Predicate Pred) {
744  // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
745  // so the values can never be equal. Similarly for all other "or equals"
746  // operators.
747 
748  // (X+1) <u X --> X >u (MAXUINT-1) --> X == 255
749  // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
750  // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
751  if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
752  Value *R =
754  return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
755  }
756 
757  // (X+1) >u X --> X <u (0-1) --> X != 255
758  // (X+2) >u X --> X <u (0-2) --> X <u 254
759  // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
760  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE)
762 
763  unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits();
765  APInt::getSignedMaxValue(BitWidth));
766 
767  // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
768  // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
769  // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
770  // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
771  // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
772  // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
773  if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
774  return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI));
775 
776  // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
777  // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
778  // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
779  // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
780  // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
781  // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
782 
783  assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE);
784  Constant *C = Builder->getInt(CI->getValue()-1);
785  return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C));
786 }
787 
788 /// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
789 /// and CmpRHS are both known to be integer constants.
791  ConstantInt *DivRHS) {
792  ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
793  const APInt &CmpRHSV = CmpRHS->getValue();
794 
795  // FIXME: If the operand types don't match the type of the divide
796  // then don't attempt this transform. The code below doesn't have the
797  // logic to deal with a signed divide and an unsigned compare (and
798  // vice versa). This is because (x /s C1) <s C2 produces different
799  // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
800  // (x /u C1) <u C2. Simply casting the operands and result won't
801  // work. :( The if statement below tests that condition and bails
802  // if it finds it.
803  bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
804  if (!ICI.isEquality() && DivIsSigned != ICI.isSigned())
805  return nullptr;
806  if (DivRHS->isZero())
807  return nullptr; // The ProdOV computation fails on divide by zero.
808  if (DivIsSigned && DivRHS->isAllOnesValue())
809  return nullptr; // The overflow computation also screws up here
810  if (DivRHS->isOne()) {
811  // This eliminates some funny cases with INT_MIN.
812  ICI.setOperand(0, DivI->getOperand(0)); // X/1 == X.
813  return &ICI;
814  }
815 
816  // Compute Prod = CI * DivRHS. We are essentially solving an equation
817  // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
818  // C2 (CI). By solving for X we can turn this into a range check
819  // instead of computing a divide.
820  Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
821 
822  // Determine if the product overflows by seeing if the product is
823  // not equal to the divide. Make sure we do the same kind of divide
824  // as in the LHS instruction that we're folding.
825  bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
826  ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
827 
828  // Get the ICmp opcode
829  ICmpInst::Predicate Pred = ICI.getPredicate();
830 
831  /// If the division is known to be exact, then there is no remainder from the
832  /// divide, so the covered range size is unit, otherwise it is the divisor.
833  ConstantInt *RangeSize = DivI->isExact() ? getOne(Prod) : DivRHS;
834 
835  // Figure out the interval that is being checked. For example, a comparison
836  // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
837  // Compute this interval based on the constants involved and the signedness of
838  // the compare/divide. This computes a half-open interval, keeping track of
839  // whether either value in the interval overflows. After analysis each
840  // overflow variable is set to 0 if it's corresponding bound variable is valid
841  // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
842  int LoOverflow = 0, HiOverflow = 0;
843  Constant *LoBound = nullptr, *HiBound = nullptr;
844 
845  if (!DivIsSigned) { // udiv
846  // e.g. X/5 op 3 --> [15, 20)
847  LoBound = Prod;
848  HiOverflow = LoOverflow = ProdOV;
849  if (!HiOverflow) {
850  // If this is not an exact divide, then many values in the range collapse
851  // to the same result value.
852  HiOverflow = AddWithOverflow(HiBound, LoBound, RangeSize, false);
853  }
854 
855  } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
856  if (CmpRHSV == 0) { // (X / pos) op 0
857  // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
858  LoBound = ConstantExpr::getNeg(SubOne(RangeSize));
859  HiBound = RangeSize;
860  } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
861  LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
862  HiOverflow = LoOverflow = ProdOV;
863  if (!HiOverflow)
864  HiOverflow = AddWithOverflow(HiBound, Prod, RangeSize, true);
865  } else { // (X / pos) op neg
866  // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
867  HiBound = AddOne(Prod);
868  LoOverflow = HiOverflow = ProdOV ? -1 : 0;
869  if (!LoOverflow) {
870  ConstantInt *DivNeg =cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
871  LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
872  }
873  }
874  } else if (DivRHS->isNegative()) { // Divisor is < 0.
875  if (DivI->isExact())
876  RangeSize = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
877  if (CmpRHSV == 0) { // (X / neg) op 0
878  // e.g. X/-5 op 0 --> [-4, 5)
879  LoBound = AddOne(RangeSize);
880  HiBound = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
881  if (HiBound == DivRHS) { // -INTMIN = INTMIN
882  HiOverflow = 1; // [INTMIN+1, overflow)
883  HiBound = nullptr; // e.g. X/INTMIN = 0 --> X > INTMIN
884  }
885  } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
886  // e.g. X/-5 op 3 --> [-19, -14)
887  HiBound = AddOne(Prod);
888  HiOverflow = LoOverflow = ProdOV ? -1 : 0;
889  if (!LoOverflow)
890  LoOverflow = AddWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0;
891  } else { // (X / neg) op neg
892  LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
893  LoOverflow = HiOverflow = ProdOV;
894  if (!HiOverflow)
895  HiOverflow = SubWithOverflow(HiBound, Prod, RangeSize, true);
896  }
897 
898  // Dividing by a negative swaps the condition. LT <-> GT
899  Pred = ICmpInst::getSwappedPredicate(Pred);
900  }
901 
902  Value *X = DivI->getOperand(0);
903  switch (Pred) {
904  default: llvm_unreachable("Unhandled icmp opcode!");
905  case ICmpInst::ICMP_EQ:
906  if (LoOverflow && HiOverflow)
907  return ReplaceInstUsesWith(ICI, Builder->getFalse());
908  if (HiOverflow)
909  return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
910  ICmpInst::ICMP_UGE, X, LoBound);
911  if (LoOverflow)
912  return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
913  ICmpInst::ICMP_ULT, X, HiBound);
914  return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound,
915  DivIsSigned, true));
916  case ICmpInst::ICMP_NE:
917  if (LoOverflow && HiOverflow)
918  return ReplaceInstUsesWith(ICI, Builder->getTrue());
919  if (HiOverflow)
920  return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
921  ICmpInst::ICMP_ULT, X, LoBound);
922  if (LoOverflow)
923  return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
924  ICmpInst::ICMP_UGE, X, HiBound);
925  return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound,
926  DivIsSigned, false));
927  case ICmpInst::ICMP_ULT:
928  case ICmpInst::ICMP_SLT:
929  if (LoOverflow == +1) // Low bound is greater than input range.
930  return ReplaceInstUsesWith(ICI, Builder->getTrue());
931  if (LoOverflow == -1) // Low bound is less than input range.
932  return ReplaceInstUsesWith(ICI, Builder->getFalse());
933  return new ICmpInst(Pred, X, LoBound);
934  case ICmpInst::ICMP_UGT:
935  case ICmpInst::ICMP_SGT:
936  if (HiOverflow == +1) // High bound greater than input range.
937  return ReplaceInstUsesWith(ICI, Builder->getFalse());
938  if (HiOverflow == -1) // High bound less than input range.
939  return ReplaceInstUsesWith(ICI, Builder->getTrue());
940  if (Pred == ICmpInst::ICMP_UGT)
941  return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
942  return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
943  }
944 }
945 
946 /// FoldICmpShrCst - Handle "icmp(([al]shr X, cst1), cst2)".
948  ConstantInt *ShAmt) {
949  const APInt &CmpRHSV = cast<ConstantInt>(ICI.getOperand(1))->getValue();
950 
951  // Check that the shift amount is in range. If not, don't perform
952  // undefined shifts. When the shift is visited it will be
953  // simplified.
954  uint32_t TypeBits = CmpRHSV.getBitWidth();
955  uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
956  if (ShAmtVal >= TypeBits || ShAmtVal == 0)
957  return nullptr;
958 
959  if (!ICI.isEquality()) {
960  // If we have an unsigned comparison and an ashr, we can't simplify this.
961  // Similarly for signed comparisons with lshr.
962  if (ICI.isSigned() != (Shr->getOpcode() == Instruction::AShr))
963  return nullptr;
964 
965  // Otherwise, all lshr and most exact ashr's are equivalent to a udiv/sdiv
966  // by a power of 2. Since we already have logic to simplify these,
967  // transform to div and then simplify the resultant comparison.
968  if (Shr->getOpcode() == Instruction::AShr &&
969  (!Shr->isExact() || ShAmtVal == TypeBits - 1))
970  return nullptr;
971 
972  // Revisit the shift (to delete it).
973  Worklist.Add(Shr);
974 
975  Constant *DivCst =
976  ConstantInt::get(Shr->getType(), APInt::getOneBitSet(TypeBits, ShAmtVal));
977 
978  Value *Tmp =
979  Shr->getOpcode() == Instruction::AShr ?
980  Builder->CreateSDiv(Shr->getOperand(0), DivCst, "", Shr->isExact()) :
981  Builder->CreateUDiv(Shr->getOperand(0), DivCst, "", Shr->isExact());
982 
983  ICI.setOperand(0, Tmp);
984 
985  // If the builder folded the binop, just return it.
986  BinaryOperator *TheDiv = dyn_cast<BinaryOperator>(Tmp);
987  if (!TheDiv)
988  return &ICI;
989 
990  // Otherwise, fold this div/compare.
991  assert(TheDiv->getOpcode() == Instruction::SDiv ||
992  TheDiv->getOpcode() == Instruction::UDiv);
993 
994  Instruction *Res = FoldICmpDivCst(ICI, TheDiv, cast<ConstantInt>(DivCst));
995  assert(Res && "This div/cst should have folded!");
996  return Res;
997  }
998 
999 
1000  // If we are comparing against bits always shifted out, the
1001  // comparison cannot succeed.
1002  APInt Comp = CmpRHSV << ShAmtVal;
1003  ConstantInt *ShiftedCmpRHS = Builder->getInt(Comp);
1004  if (Shr->getOpcode() == Instruction::LShr)
1005  Comp = Comp.lshr(ShAmtVal);
1006  else
1007  Comp = Comp.ashr(ShAmtVal);
1008 
1009  if (Comp != CmpRHSV) { // Comparing against a bit that we know is zero.
1010  bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
1011  Constant *Cst = Builder->getInt1(IsICMP_NE);
1012  return ReplaceInstUsesWith(ICI, Cst);
1013  }
1014 
1015  // Otherwise, check to see if the bits shifted out are known to be zero.
1016  // If so, we can compare against the unshifted value:
1017  // (X & 4) >> 1 == 2 --> (X & 4) == 4.
1018  if (Shr->hasOneUse() && Shr->isExact())
1019  return new ICmpInst(ICI.getPredicate(), Shr->getOperand(0), ShiftedCmpRHS);
1020 
1021  if (Shr->hasOneUse()) {
1022  // Otherwise strength reduce the shift into an and.
1023  APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
1024  Constant *Mask = Builder->getInt(Val);
1025 
1026  Value *And = Builder->CreateAnd(Shr->getOperand(0),
1027  Mask, Shr->getName()+".mask");
1028  return new ICmpInst(ICI.getPredicate(), And, ShiftedCmpRHS);
1029  }
1030  return nullptr;
1031 }
1032 
1033 /// FoldICmpCstShrCst - Handle "(icmp eq/ne (ashr/lshr const2, A), const1)" ->
1034 /// (icmp eq/ne A, Log2(const2/const1)) ->
1035 /// (icmp eq/ne A, Log2(const2) - Log2(const1)).
1037  ConstantInt *CI1,
1038  ConstantInt *CI2) {
1039  assert(I.isEquality() && "Cannot fold icmp gt/lt");
1040 
1041  auto getConstant = [&I, this](bool IsTrue) {
1042  if (I.getPredicate() == I.ICMP_NE)
1043  IsTrue = !IsTrue;
1044  return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), IsTrue));
1045  };
1046 
1047  auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
1048  if (I.getPredicate() == I.ICMP_NE)
1049  Pred = CmpInst::getInversePredicate(Pred);
1050  return new ICmpInst(Pred, LHS, RHS);
1051  };
1052 
1053  APInt AP1 = CI1->getValue();
1054  APInt AP2 = CI2->getValue();
1055 
1056  // Don't bother doing any work for cases which InstSimplify handles.
1057  if (AP2 == 0)
1058  return nullptr;
1059  bool IsAShr = isa<AShrOperator>(Op);
1060  if (IsAShr) {
1061  if (AP2.isAllOnesValue())
1062  return nullptr;
1063  if (AP2.isNegative() != AP1.isNegative())
1064  return nullptr;
1065  if (AP2.sgt(AP1))
1066  return nullptr;
1067  }
1068 
1069  if (!AP1)
1070  // 'A' must be large enough to shift out the highest set bit.
1071  return getICmp(I.ICMP_UGT, A,
1072  ConstantInt::get(A->getType(), AP2.logBase2()));
1073 
1074  if (AP1 == AP2)
1075  return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
1076 
1077  // Get the distance between the highest bit that's set.
1078  int Shift;
1079  // Both the constants are negative, take their positive to calculate log.
1080  if (IsAShr && AP1.isNegative())
1081  // Get the ones' complement of AP2 and AP1 when computing the distance.
1082  Shift = (~AP2).logBase2() - (~AP1).logBase2();
1083  else
1084  Shift = AP2.logBase2() - AP1.logBase2();
1085 
1086  if (Shift > 0) {
1087  if (IsAShr ? AP1 == AP2.ashr(Shift) : AP1 == AP2.lshr(Shift))
1088  return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1089  }
1090  // Shifting const2 will never be equal to const1.
1091  return getConstant(false);
1092 }
1093 
1094 /// FoldICmpCstShlCst - Handle "(icmp eq/ne (shl const2, A), const1)" ->
1095 /// (icmp eq/ne A, TrailingZeros(const1) - TrailingZeros(const2)).
1097  ConstantInt *CI1,
1098  ConstantInt *CI2) {
1099  assert(I.isEquality() && "Cannot fold icmp gt/lt");
1100 
1101  auto getConstant = [&I, this](bool IsTrue) {
1102  if (I.getPredicate() == I.ICMP_NE)
1103  IsTrue = !IsTrue;
1104  return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), IsTrue));
1105  };
1106 
1107  auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
1108  if (I.getPredicate() == I.ICMP_NE)
1109  Pred = CmpInst::getInversePredicate(Pred);
1110  return new ICmpInst(Pred, LHS, RHS);
1111  };
1112 
1113  APInt AP1 = CI1->getValue();
1114  APInt AP2 = CI2->getValue();
1115 
1116  // Don't bother doing any work for cases which InstSimplify handles.
1117  if (AP2 == 0)
1118  return nullptr;
1119 
1120  unsigned AP2TrailingZeros = AP2.countTrailingZeros();
1121 
1122  if (!AP1 && AP2TrailingZeros != 0)
1123  return getICmp(I.ICMP_UGE, A,
1124  ConstantInt::get(A->getType(), AP2.getBitWidth() - AP2TrailingZeros));
1125 
1126  if (AP1 == AP2)
1127  return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
1128 
1129  // Get the distance between the lowest bits that are set.
1130  int Shift = AP1.countTrailingZeros() - AP2TrailingZeros;
1131 
1132  if (Shift > 0 && AP2.shl(Shift) == AP1)
1133  return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1134 
1135  // Shifting const2 will never be equal to const1.
1136  return getConstant(false);
1137 }
1138 
1139 /// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
1140 ///
1142  Instruction *LHSI,
1143  ConstantInt *RHS) {
1144  const APInt &RHSV = RHS->getValue();
1145 
1146  switch (LHSI->getOpcode()) {
1147  case Instruction::Trunc:
1148  if (ICI.isEquality() && LHSI->hasOneUse()) {
1149  // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
1150  // of the high bits truncated out of x are known.
1151  unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
1152  SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
1153  APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
1154  computeKnownBits(LHSI->getOperand(0), KnownZero, KnownOne, 0, &ICI);
1155 
1156  // If all the high bits are known, we can do this xform.
1157  if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
1158  // Pull in the high bits from known-ones set.
1159  APInt NewRHS = RHS->getValue().zext(SrcBits);
1160  NewRHS |= KnownOne & APInt::getHighBitsSet(SrcBits, SrcBits-DstBits);
1161  return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
1162  Builder->getInt(NewRHS));
1163  }
1164  }
1165  break;
1166 
1167  case Instruction::Xor: // (icmp pred (xor X, XorCst), CI)
1168  if (ConstantInt *XorCst = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
1169  // If this is a comparison that tests the signbit (X < 0) or (x > -1),
1170  // fold the xor.
1171  if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
1172  (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
1173  Value *CompareVal = LHSI->getOperand(0);
1174 
1175  // If the sign bit of the XorCst is not set, there is no change to
1176  // the operation, just stop using the Xor.
1177  if (!XorCst->isNegative()) {
1178  ICI.setOperand(0, CompareVal);
1179  Worklist.Add(LHSI);
1180  return &ICI;
1181  }
1182 
1183  // Was the old condition true if the operand is positive?
1184  bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
1185 
1186  // If so, the new one isn't.
1187  isTrueIfPositive ^= true;
1188 
1189  if (isTrueIfPositive)
1190  return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal,
1191  SubOne(RHS));
1192  else
1193  return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal,
1194  AddOne(RHS));
1195  }
1196 
1197  if (LHSI->hasOneUse()) {
1198  // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
1199  if (!ICI.isEquality() && XorCst->getValue().isSignBit()) {
1200  const APInt &SignBit = XorCst->getValue();
1201  ICmpInst::Predicate Pred = ICI.isSigned()
1202  ? ICI.getUnsignedPredicate()
1203  : ICI.getSignedPredicate();
1204  return new ICmpInst(Pred, LHSI->getOperand(0),
1205  Builder->getInt(RHSV ^ SignBit));
1206  }
1207 
1208  // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
1209  if (!ICI.isEquality() && XorCst->isMaxValue(true)) {
1210  const APInt &NotSignBit = XorCst->getValue();
1211  ICmpInst::Predicate Pred = ICI.isSigned()
1212  ? ICI.getUnsignedPredicate()
1213  : ICI.getSignedPredicate();
1214  Pred = ICI.getSwappedPredicate(Pred);
1215  return new ICmpInst(Pred, LHSI->getOperand(0),
1216  Builder->getInt(RHSV ^ NotSignBit));
1217  }
1218  }
1219 
1220  // (icmp ugt (xor X, C), ~C) -> (icmp ult X, C)
1221  // iff -C is a power of 2
1222  if (ICI.getPredicate() == ICmpInst::ICMP_UGT &&
1223  XorCst->getValue() == ~RHSV && (RHSV + 1).isPowerOf2())
1224  return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), XorCst);
1225 
1226  // (icmp ult (xor X, C), -C) -> (icmp uge X, C)
1227  // iff -C is a power of 2
1228  if (ICI.getPredicate() == ICmpInst::ICMP_ULT &&
1229  XorCst->getValue() == -RHSV && RHSV.isPowerOf2())
1230  return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), XorCst);
1231  }
1232  break;
1233  case Instruction::And: // (icmp pred (and X, AndCst), RHS)
1234  if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
1235  LHSI->getOperand(0)->hasOneUse()) {
1236  ConstantInt *AndCst = cast<ConstantInt>(LHSI->getOperand(1));
1237 
1238  // If the LHS is an AND of a truncating cast, we can widen the
1239  // and/compare to be the input width without changing the value
1240  // produced, eliminating a cast.
1241  if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
1242  // We can do this transformation if either the AND constant does not
1243  // have its sign bit set or if it is an equality comparison.
1244  // Extending a relational comparison when we're checking the sign
1245  // bit would not work.
1246  if (ICI.isEquality() ||
1247  (!AndCst->isNegative() && RHSV.isNonNegative())) {
1248  Value *NewAnd =
1249  Builder->CreateAnd(Cast->getOperand(0),
1250  ConstantExpr::getZExt(AndCst, Cast->getSrcTy()));
1251  NewAnd->takeName(LHSI);
1252  return new ICmpInst(ICI.getPredicate(), NewAnd,
1253  ConstantExpr::getZExt(RHS, Cast->getSrcTy()));
1254  }
1255  }
1256 
1257  // If the LHS is an AND of a zext, and we have an equality compare, we can
1258  // shrink the and/compare to the smaller type, eliminating the cast.
1259  if (ZExtInst *Cast = dyn_cast<ZExtInst>(LHSI->getOperand(0))) {
1260  IntegerType *Ty = cast<IntegerType>(Cast->getSrcTy());
1261  // Make sure we don't compare the upper bits, SimplifyDemandedBits
1262  // should fold the icmp to true/false in that case.
1263  if (ICI.isEquality() && RHSV.getActiveBits() <= Ty->getBitWidth()) {
1264  Value *NewAnd =
1265  Builder->CreateAnd(Cast->getOperand(0),
1266  ConstantExpr::getTrunc(AndCst, Ty));
1267  NewAnd->takeName(LHSI);
1268  return new ICmpInst(ICI.getPredicate(), NewAnd,
1269  ConstantExpr::getTrunc(RHS, Ty));
1270  }
1271  }
1272 
1273  // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
1274  // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
1275  // happens a LOT in code produced by the C front-end, for bitfield
1276  // access.
1277  BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
1278  if (Shift && !Shift->isShift())
1279  Shift = nullptr;
1280 
1281  ConstantInt *ShAmt;
1282  ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : nullptr;
1283 
1284  // This seemingly simple opportunity to fold away a shift turns out to
1285  // be rather complicated. See PR17827
1286  // ( http://llvm.org/bugs/show_bug.cgi?id=17827 ) for details.
1287  if (ShAmt) {
1288  bool CanFold = false;
1289  unsigned ShiftOpcode = Shift->getOpcode();
1290  if (ShiftOpcode == Instruction::AShr) {
1291  // There may be some constraints that make this possible,
1292  // but nothing simple has been discovered yet.
1293  CanFold = false;
1294  } else if (ShiftOpcode == Instruction::Shl) {
1295  // For a left shift, we can fold if the comparison is not signed.
1296  // We can also fold a signed comparison if the mask value and
1297  // comparison value are not negative. These constraints may not be
1298  // obvious, but we can prove that they are correct using an SMT
1299  // solver.
1300  if (!ICI.isSigned() || (!AndCst->isNegative() && !RHS->isNegative()))
1301  CanFold = true;
1302  } else if (ShiftOpcode == Instruction::LShr) {
1303  // For a logical right shift, we can fold if the comparison is not
1304  // signed. We can also fold a signed comparison if the shifted mask
1305  // value and the shifted comparison value are not negative.
1306  // These constraints may not be obvious, but we can prove that they
1307  // are correct using an SMT solver.
1308  if (!ICI.isSigned())
1309  CanFold = true;
1310  else {
1311  ConstantInt *ShiftedAndCst =
1312  cast<ConstantInt>(ConstantExpr::getShl(AndCst, ShAmt));
1313  ConstantInt *ShiftedRHSCst =
1314  cast<ConstantInt>(ConstantExpr::getShl(RHS, ShAmt));
1315 
1316  if (!ShiftedAndCst->isNegative() && !ShiftedRHSCst->isNegative())
1317  CanFold = true;
1318  }
1319  }
1320 
1321  if (CanFold) {
1322  Constant *NewCst;
1323  if (ShiftOpcode == Instruction::Shl)
1324  NewCst = ConstantExpr::getLShr(RHS, ShAmt);
1325  else
1326  NewCst = ConstantExpr::getShl(RHS, ShAmt);
1327 
1328  // Check to see if we are shifting out any of the bits being
1329  // compared.
1330  if (ConstantExpr::get(ShiftOpcode, NewCst, ShAmt) != RHS) {
1331  // If we shifted bits out, the fold is not going to work out.
1332  // As a special case, check to see if this means that the
1333  // result is always true or false now.
1334  if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
1335  return ReplaceInstUsesWith(ICI, Builder->getFalse());
1336  if (ICI.getPredicate() == ICmpInst::ICMP_NE)
1337  return ReplaceInstUsesWith(ICI, Builder->getTrue());
1338  } else {
1339  ICI.setOperand(1, NewCst);
1340  Constant *NewAndCst;
1341  if (ShiftOpcode == Instruction::Shl)
1342  NewAndCst = ConstantExpr::getLShr(AndCst, ShAmt);
1343  else
1344  NewAndCst = ConstantExpr::getShl(AndCst, ShAmt);
1345  LHSI->setOperand(1, NewAndCst);
1346  LHSI->setOperand(0, Shift->getOperand(0));
1347  Worklist.Add(Shift); // Shift is dead.
1348  return &ICI;
1349  }
1350  }
1351  }
1352 
1353  // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
1354  // preferable because it allows the C<<Y expression to be hoisted out
1355  // of a loop if Y is invariant and X is not.
1356  if (Shift && Shift->hasOneUse() && RHSV == 0 &&
1357  ICI.isEquality() && !Shift->isArithmeticShift() &&
1358  !isa<Constant>(Shift->getOperand(0))) {
1359  // Compute C << Y.
1360  Value *NS;
1361  if (Shift->getOpcode() == Instruction::LShr) {
1362  NS = Builder->CreateShl(AndCst, Shift->getOperand(1));
1363  } else {
1364  // Insert a logical shift.
1365  NS = Builder->CreateLShr(AndCst, Shift->getOperand(1));
1366  }
1367 
1368  // Compute X & (C << Y).
1369  Value *NewAnd =
1370  Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
1371 
1372  ICI.setOperand(0, NewAnd);
1373  return &ICI;
1374  }
1375 
1376  // (icmp pred (and (or (lshr X, Y), X), 1), 0) -->
1377  // (icmp pred (and X, (or (shl 1, Y), 1), 0))
1378  //
1379  // iff pred isn't signed
1380  {
1381  Value *X, *Y, *LShr;
1382  if (!ICI.isSigned() && RHSV == 0) {
1383  if (match(LHSI->getOperand(1), m_One())) {
1384  Constant *One = cast<Constant>(LHSI->getOperand(1));
1385  Value *Or = LHSI->getOperand(0);
1386  if (match(Or, m_Or(m_Value(LShr), m_Value(X))) &&
1387  match(LShr, m_LShr(m_Specific(X), m_Value(Y)))) {
1388  unsigned UsesRemoved = 0;
1389  if (LHSI->hasOneUse())
1390  ++UsesRemoved;
1391  if (Or->hasOneUse())
1392  ++UsesRemoved;
1393  if (LShr->hasOneUse())
1394  ++UsesRemoved;
1395  Value *NewOr = nullptr;
1396  // Compute X & ((1 << Y) | 1)
1397  if (auto *C = dyn_cast<Constant>(Y)) {
1398  if (UsesRemoved >= 1)
1399  NewOr =
1401  } else {
1402  if (UsesRemoved >= 3)
1403  NewOr = Builder->CreateOr(Builder->CreateShl(One, Y,
1404  LShr->getName(),
1405  /*HasNUW=*/true),
1406  One, Or->getName());
1407  }
1408  if (NewOr) {
1409  Value *NewAnd = Builder->CreateAnd(X, NewOr, LHSI->getName());
1410  ICI.setOperand(0, NewAnd);
1411  return &ICI;
1412  }
1413  }
1414  }
1415  }
1416  }
1417 
1418  // Replace ((X & AndCst) > RHSV) with ((X & AndCst) != 0), if any
1419  // bit set in (X & AndCst) will produce a result greater than RHSV.
1420  if (ICI.getPredicate() == ICmpInst::ICMP_UGT) {
1421  unsigned NTZ = AndCst->getValue().countTrailingZeros();
1422  if ((NTZ < AndCst->getBitWidth()) &&
1423  APInt::getOneBitSet(AndCst->getBitWidth(), NTZ).ugt(RHSV))
1424  return new ICmpInst(ICmpInst::ICMP_NE, LHSI,
1426  }
1427  }
1428 
1429  // Try to optimize things like "A[i]&42 == 0" to index computations.
1430  if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) {
1431  if (GetElementPtrInst *GEP =
1432  dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
1433  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
1434  if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
1435  !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) {
1436  ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1));
1437  if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C))
1438  return Res;
1439  }
1440  }
1441 
1442  // X & -C == -C -> X > u ~C
1443  // X & -C != -C -> X <= u ~C
1444  // iff C is a power of 2
1445  if (ICI.isEquality() && RHS == LHSI->getOperand(1) && (-RHSV).isPowerOf2())
1446  return new ICmpInst(
1449  LHSI->getOperand(0), SubOne(RHS));
1450  break;
1451 
1452  case Instruction::Or: {
1453  if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse())
1454  break;
1455  Value *P, *Q;
1456  if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
1457  // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
1458  // -> and (icmp eq P, null), (icmp eq Q, null).
1459  Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P,
1461  Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q,
1463  Instruction *Op;
1464  if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
1465  Op = BinaryOperator::CreateAnd(ICIP, ICIQ);
1466  else
1467  Op = BinaryOperator::CreateOr(ICIP, ICIQ);
1468  return Op;
1469  }
1470  break;
1471  }
1472 
1473  case Instruction::Mul: { // (icmp pred (mul X, Val), CI)
1474  ConstantInt *Val = dyn_cast<ConstantInt>(LHSI->getOperand(1));
1475  if (!Val) break;
1476 
1477  // If this is a signed comparison to 0 and the mul is sign preserving,
1478  // use the mul LHS operand instead.
1480  if (isSignTest(pred, RHS) && !Val->isZero() &&
1481  cast<BinaryOperator>(LHSI)->hasNoSignedWrap())
1482  return new ICmpInst(Val->isNegative() ?
1484  LHSI->getOperand(0),
1486 
1487  break;
1488  }
1489 
1490  case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
1491  uint32_t TypeBits = RHSV.getBitWidth();
1492  ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
1493  if (!ShAmt) {
1494  Value *X;
1495  // (1 << X) pred P2 -> X pred Log2(P2)
1496  if (match(LHSI, m_Shl(m_One(), m_Value(X)))) {
1497  bool RHSVIsPowerOf2 = RHSV.isPowerOf2();
1498  ICmpInst::Predicate Pred = ICI.getPredicate();
1499  if (ICI.isUnsigned()) {
1500  if (!RHSVIsPowerOf2) {
1501  // (1 << X) < 30 -> X <= 4
1502  // (1 << X) <= 30 -> X <= 4
1503  // (1 << X) >= 30 -> X > 4
1504  // (1 << X) > 30 -> X > 4
1505  if (Pred == ICmpInst::ICMP_ULT)
1506  Pred = ICmpInst::ICMP_ULE;
1507  else if (Pred == ICmpInst::ICMP_UGE)
1508  Pred = ICmpInst::ICMP_UGT;
1509  }
1510  unsigned RHSLog2 = RHSV.logBase2();
1511 
1512  // (1 << X) >= 2147483648 -> X >= 31 -> X == 31
1513  // (1 << X) < 2147483648 -> X < 31 -> X != 31
1514  if (RHSLog2 == TypeBits-1) {
1515  if (Pred == ICmpInst::ICMP_UGE)
1516  Pred = ICmpInst::ICMP_EQ;
1517  else if (Pred == ICmpInst::ICMP_ULT)
1518  Pred = ICmpInst::ICMP_NE;
1519  }
1520 
1521  return new ICmpInst(Pred, X,
1522  ConstantInt::get(RHS->getType(), RHSLog2));
1523  } else if (ICI.isSigned()) {
1524  if (RHSV.isAllOnesValue()) {
1525  // (1 << X) <= -1 -> X == 31
1526  if (Pred == ICmpInst::ICMP_SLE)
1527  return new ICmpInst(ICmpInst::ICMP_EQ, X,
1528  ConstantInt::get(RHS->getType(), TypeBits-1));
1529 
1530  // (1 << X) > -1 -> X != 31
1531  if (Pred == ICmpInst::ICMP_SGT)
1532  return new ICmpInst(ICmpInst::ICMP_NE, X,
1533  ConstantInt::get(RHS->getType(), TypeBits-1));
1534  } else if (!RHSV) {
1535  // (1 << X) < 0 -> X == 31
1536  // (1 << X) <= 0 -> X == 31
1537  if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
1538  return new ICmpInst(ICmpInst::ICMP_EQ, X,
1539  ConstantInt::get(RHS->getType(), TypeBits-1));
1540 
1541  // (1 << X) >= 0 -> X != 31
1542  // (1 << X) > 0 -> X != 31
1543  if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)
1544  return new ICmpInst(ICmpInst::ICMP_NE, X,
1545  ConstantInt::get(RHS->getType(), TypeBits-1));
1546  }
1547  } else if (ICI.isEquality()) {
1548  if (RHSVIsPowerOf2)
1549  return new ICmpInst(
1550  Pred, X, ConstantInt::get(RHS->getType(), RHSV.logBase2()));
1551  }
1552  }
1553  break;
1554  }
1555 
1556  // Check that the shift amount is in range. If not, don't perform
1557  // undefined shifts. When the shift is visited it will be
1558  // simplified.
1559  if (ShAmt->uge(TypeBits))
1560  break;
1561 
1562  if (ICI.isEquality()) {
1563  // If we are comparing against bits always shifted out, the
1564  // comparison cannot succeed.
1565  Constant *Comp =
1567  ShAmt);
1568  if (Comp != RHS) {// Comparing against a bit that we know is zero.
1569  bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
1570  Constant *Cst = Builder->getInt1(IsICMP_NE);
1571  return ReplaceInstUsesWith(ICI, Cst);
1572  }
1573 
1574  // If the shift is NUW, then it is just shifting out zeros, no need for an
1575  // AND.
1576  if (cast<BinaryOperator>(LHSI)->hasNoUnsignedWrap())
1577  return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
1578  ConstantExpr::getLShr(RHS, ShAmt));
1579 
1580  // If the shift is NSW and we compare to 0, then it is just shifting out
1581  // sign bits, no need for an AND either.
1582  if (cast<BinaryOperator>(LHSI)->hasNoSignedWrap() && RHSV == 0)
1583  return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
1584  ConstantExpr::getLShr(RHS, ShAmt));
1585 
1586  if (LHSI->hasOneUse()) {
1587  // Otherwise strength reduce the shift into an and.
1588  uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
1589  Constant *Mask = Builder->getInt(APInt::getLowBitsSet(TypeBits,
1590  TypeBits - ShAmtVal));
1591 
1592  Value *And =
1593  Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask");
1594  return new ICmpInst(ICI.getPredicate(), And,
1595  ConstantExpr::getLShr(RHS, ShAmt));
1596  }
1597  }
1598 
1599  // If this is a signed comparison to 0 and the shift is sign preserving,
1600  // use the shift LHS operand instead.
1602  if (isSignTest(pred, RHS) &&
1603  cast<BinaryOperator>(LHSI)->hasNoSignedWrap())
1604  return new ICmpInst(pred,
1605  LHSI->getOperand(0),
1607 
1608  // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
1609  bool TrueIfSigned = false;
1610  if (LHSI->hasOneUse() &&
1611  isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
1612  // (X << 31) <s 0 --> (X&1) != 0
1613  Constant *Mask = ConstantInt::get(LHSI->getOperand(0)->getType(),
1614  APInt::getOneBitSet(TypeBits,
1615  TypeBits-ShAmt->getZExtValue()-1));
1616  Value *And =
1617  Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask");
1618  return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
1619  And, Constant::getNullValue(And->getType()));
1620  }
1621 
1622  // Transform (icmp pred iM (shl iM %v, N), CI)
1623  // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (CI>>N))
1624  // Transform the shl to a trunc if (trunc (CI>>N)) has no loss and M-N.
1625  // This enables to get rid of the shift in favor of a trunc which can be
1626  // free on the target. It has the additional benefit of comparing to a
1627  // smaller constant, which will be target friendly.
1628  unsigned Amt = ShAmt->getLimitedValue(TypeBits-1);
1629  if (LHSI->hasOneUse() &&
1630  Amt != 0 && RHSV.countTrailingZeros() >= Amt) {
1631  Type *NTy = IntegerType::get(ICI.getContext(), TypeBits - Amt);
1634  ConstantInt::get(RHS->getType(), Amt)),
1635  NTy);
1636  return new ICmpInst(ICI.getPredicate(),
1637  Builder->CreateTrunc(LHSI->getOperand(0), NTy),
1638  NCI);
1639  }
1640 
1641  break;
1642  }
1643 
1644  case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
1645  case Instruction::AShr: {
1646  // Handle equality comparisons of shift-by-constant.
1647  BinaryOperator *BO = cast<BinaryOperator>(LHSI);
1648  if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
1649  if (Instruction *Res = FoldICmpShrCst(ICI, BO, ShAmt))
1650  return Res;
1651  }
1652 
1653  // Handle exact shr's.
1654  if (ICI.isEquality() && BO->isExact() && BO->hasOneUse()) {
1655  if (RHSV.isMinValue())
1656  return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), RHS);
1657  }
1658  break;
1659  }
1660 
1661  case Instruction::SDiv:
1662  case Instruction::UDiv:
1663  // Fold: icmp pred ([us]div X, C1), C2 -> range test
1664  // Fold this div into the comparison, producing a range check.
1665  // Determine, based on the divide type, what the range is being
1666  // checked. If there is an overflow on the low or high side, remember
1667  // it, otherwise compute the range [low, hi) bounding the new value.
1668  // See: InsertRangeTest above for the kinds of replacements possible.
1669  if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
1670  if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
1671  DivRHS))
1672  return R;
1673  break;
1674 
1675  case Instruction::Sub: {
1676  ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(0));
1677  if (!LHSC) break;
1678  const APInt &LHSV = LHSC->getValue();
1679 
1680  // C1-X <u C2 -> (X|(C2-1)) == C1
1681  // iff C1 & (C2-1) == C2-1
1682  // C2 is a power of 2
1683  if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() &&
1684  RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == (RHSV - 1))
1685  return new ICmpInst(ICmpInst::ICMP_EQ,
1686  Builder->CreateOr(LHSI->getOperand(1), RHSV - 1),
1687  LHSC);
1688 
1689  // C1-X >u C2 -> (X|C2) != C1
1690  // iff C1 & C2 == C2
1691  // C2+1 is a power of 2
1692  if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() &&
1693  (RHSV + 1).isPowerOf2() && (LHSV & RHSV) == RHSV)
1694  return new ICmpInst(ICmpInst::ICMP_NE,
1695  Builder->CreateOr(LHSI->getOperand(1), RHSV), LHSC);
1696  break;
1697  }
1698 
1699  case Instruction::Add:
1700  // Fold: icmp pred (add X, C1), C2
1701  if (!ICI.isEquality()) {
1702  ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
1703  if (!LHSC) break;
1704  const APInt &LHSV = LHSC->getValue();
1705 
1706  ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
1707  .subtract(LHSV);
1708 
1709  if (ICI.isSigned()) {
1710  if (CR.getLower().isSignBit()) {
1711  return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
1712  Builder->getInt(CR.getUpper()));
1713  } else if (CR.getUpper().isSignBit()) {
1714  return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
1715  Builder->getInt(CR.getLower()));
1716  }
1717  } else {
1718  if (CR.getLower().isMinValue()) {
1719  return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
1720  Builder->getInt(CR.getUpper()));
1721  } else if (CR.getUpper().isMinValue()) {
1722  return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
1723  Builder->getInt(CR.getLower()));
1724  }
1725  }
1726 
1727  // X-C1 <u C2 -> (X & -C2) == C1
1728  // iff C1 & (C2-1) == 0
1729  // C2 is a power of 2
1730  if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() &&
1731  RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == 0)
1732  return new ICmpInst(ICmpInst::ICMP_EQ,
1733  Builder->CreateAnd(LHSI->getOperand(0), -RHSV),
1734  ConstantExpr::getNeg(LHSC));
1735 
1736  // X-C1 >u C2 -> (X & ~C2) != C1
1737  // iff C1 & C2 == 0
1738  // C2+1 is a power of 2
1739  if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() &&
1740  (RHSV + 1).isPowerOf2() && (LHSV & RHSV) == 0)
1741  return new ICmpInst(ICmpInst::ICMP_NE,
1742  Builder->CreateAnd(LHSI->getOperand(0), ~RHSV),
1743  ConstantExpr::getNeg(LHSC));
1744  }
1745  break;
1746  }
1747 
1748  // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
1749  if (ICI.isEquality()) {
1750  bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
1751 
1752  // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
1753  // the second operand is a constant, simplify a bit.
1754  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
1755  switch (BO->getOpcode()) {
1756  case Instruction::SRem:
1757  // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
1758  if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
1759  const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
1760  if (V.sgt(1) && V.isPowerOf2()) {
1761  Value *NewRem =
1762  Builder->CreateURem(BO->getOperand(0), BO->getOperand(1),
1763  BO->getName());
1764  return new ICmpInst(ICI.getPredicate(), NewRem,
1765  Constant::getNullValue(BO->getType()));
1766  }
1767  }
1768  break;
1769  case Instruction::Add:
1770  // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
1771  if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1772  if (BO->hasOneUse())
1773  return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1774  ConstantExpr::getSub(RHS, BOp1C));
1775  } else if (RHSV == 0) {
1776  // Replace ((add A, B) != 0) with (A != -B) if A or B is
1777  // efficiently invertible, or if the add has just this one use.
1778  Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
1779 
1780  if (Value *NegVal = dyn_castNegVal(BOp1))
1781  return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
1782  if (Value *NegVal = dyn_castNegVal(BOp0))
1783  return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
1784  if (BO->hasOneUse()) {
1785  Value *Neg = Builder->CreateNeg(BOp1);
1786  Neg->takeName(BO);
1787  return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
1788  }
1789  }
1790  break;
1791  case Instruction::Xor:
1792  // For the xor case, we can xor two constants together, eliminating
1793  // the explicit xor.
1794  if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
1795  return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1796  ConstantExpr::getXor(RHS, BOC));
1797  } else if (RHSV == 0) {
1798  // Replace ((xor A, B) != 0) with (A != B)
1799  return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1800  BO->getOperand(1));
1801  }
1802  break;
1803  case Instruction::Sub:
1804  // Replace ((sub A, B) != C) with (B != A-C) if A & C are constants.
1805  if (ConstantInt *BOp0C = dyn_cast<ConstantInt>(BO->getOperand(0))) {
1806  if (BO->hasOneUse())
1807  return new ICmpInst(ICI.getPredicate(), BO->getOperand(1),
1808  ConstantExpr::getSub(BOp0C, RHS));
1809  } else if (RHSV == 0) {
1810  // Replace ((sub A, B) != 0) with (A != B)
1811  return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1812  BO->getOperand(1));
1813  }
1814  break;
1815  case Instruction::Or:
1816  // If bits are being or'd in that are not present in the constant we
1817  // are comparing against, then the comparison could never succeed!
1818  if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1819  Constant *NotCI = ConstantExpr::getNot(RHS);
1820  if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
1821  return ReplaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
1822  }
1823  break;
1824 
1825  case Instruction::And:
1826  if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1827  // If bits are being compared against that are and'd out, then the
1828  // comparison can never succeed!
1829  if ((RHSV & ~BOC->getValue()) != 0)
1830  return ReplaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
1831 
1832  // If we have ((X & C) == C), turn it into ((X & C) != 0).
1833  if (RHS == BOC && RHSV.isPowerOf2())
1834  return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
1835  ICmpInst::ICMP_NE, LHSI,
1837 
1838  // Don't perform the following transforms if the AND has multiple uses
1839  if (!BO->hasOneUse())
1840  break;
1841 
1842  // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
1843  if (BOC->getValue().isSignBit()) {
1844  Value *X = BO->getOperand(0);
1845  Constant *Zero = Constant::getNullValue(X->getType());
1846  ICmpInst::Predicate pred = isICMP_NE ?
1848  return new ICmpInst(pred, X, Zero);
1849  }
1850 
1851  // ((X & ~7) == 0) --> X < 8
1852  if (RHSV == 0 && isHighOnes(BOC)) {
1853  Value *X = BO->getOperand(0);
1854  Constant *NegX = ConstantExpr::getNeg(BOC);
1855  ICmpInst::Predicate pred = isICMP_NE ?
1857  return new ICmpInst(pred, X, NegX);
1858  }
1859  }
1860  break;
1861  case Instruction::Mul:
1862  if (RHSV == 0 && BO->hasNoSignedWrap()) {
1863  if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1864  // The trivial case (mul X, 0) is handled by InstSimplify
1865  // General case : (mul X, C) != 0 iff X != 0
1866  // (mul X, C) == 0 iff X == 0
1867  if (!BOC->isZero())
1868  return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1870  }
1871  }
1872  break;
1873  default: break;
1874  }
1875  } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
1876  // Handle icmp {eq|ne} <intrinsic>, intcst.
1877  switch (II->getIntrinsicID()) {
1878  case Intrinsic::bswap:
1879  Worklist.Add(II);
1880  ICI.setOperand(0, II->getArgOperand(0));
1881  ICI.setOperand(1, Builder->getInt(RHSV.byteSwap()));
1882  return &ICI;
1883  case Intrinsic::ctlz:
1884  case Intrinsic::cttz:
1885  // ctz(A) == bitwidth(a) -> A == 0 and likewise for !=
1886  if (RHSV == RHS->getType()->getBitWidth()) {
1887  Worklist.Add(II);
1888  ICI.setOperand(0, II->getArgOperand(0));
1889  ICI.setOperand(1, ConstantInt::get(RHS->getType(), 0));
1890  return &ICI;
1891  }
1892  break;
1893  case Intrinsic::ctpop:
1894  // popcount(A) == 0 -> A == 0 and likewise for !=
1895  if (RHS->isZero()) {
1896  Worklist.Add(II);
1897  ICI.setOperand(0, II->getArgOperand(0));
1898  ICI.setOperand(1, RHS);
1899  return &ICI;
1900  }
1901  break;
1902  default:
1903  break;
1904  }
1905  }
1906  }
1907  return nullptr;
1908 }
1909 
1910 /// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
1911 /// We only handle extending casts so far.
1912 ///
1914  const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
1915  Value *LHSCIOp = LHSCI->getOperand(0);
1916  Type *SrcTy = LHSCIOp->getType();
1917  Type *DestTy = LHSCI->getType();
1918  Value *RHSCIOp;
1919 
1920  // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
1921  // integer type is the same size as the pointer type.
1922  if (LHSCI->getOpcode() == Instruction::PtrToInt &&
1923  DL.getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth()) {
1924  Value *RHSOp = nullptr;
1925  if (PtrToIntOperator *RHSC = dyn_cast<PtrToIntOperator>(ICI.getOperand(1))) {
1926  Value *RHSCIOp = RHSC->getOperand(0);
1927  if (RHSCIOp->getType()->getPointerAddressSpace() ==
1928  LHSCIOp->getType()->getPointerAddressSpace()) {
1929  RHSOp = RHSC->getOperand(0);
1930  // If the pointer types don't match, insert a bitcast.
1931  if (LHSCIOp->getType() != RHSOp->getType())
1932  RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
1933  }
1934  } else if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1)))
1935  RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
1936 
1937  if (RHSOp)
1938  return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
1939  }
1940 
1941  // The code below only handles extension cast instructions, so far.
1942  // Enforce this.
1943  if (LHSCI->getOpcode() != Instruction::ZExt &&
1944  LHSCI->getOpcode() != Instruction::SExt)
1945  return nullptr;
1946 
1947  bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
1948  bool isSignedCmp = ICI.isSigned();
1949 
1950  if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
1951  // Not an extension from the same type?
1952  RHSCIOp = CI->getOperand(0);
1953  if (RHSCIOp->getType() != LHSCIOp->getType())
1954  return nullptr;
1955 
1956  // If the signedness of the two casts doesn't agree (i.e. one is a sext
1957  // and the other is a zext), then we can't handle this.
1958  if (CI->getOpcode() != LHSCI->getOpcode())
1959  return nullptr;
1960 
1961  // Deal with equality cases early.
1962  if (ICI.isEquality())
1963  return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
1964 
1965  // A signed comparison of sign extended values simplifies into a
1966  // signed comparison.
1967  if (isSignedCmp && isSignedExt)
1968  return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
1969 
1970  // The other three cases all fold into an unsigned comparison.
1971  return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
1972  }
1973 
1974  // If we aren't dealing with a constant on the RHS, exit early
1975  ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
1976  if (!CI)
1977  return nullptr;
1978 
1979  // Compute the constant that would happen if we truncated to SrcTy then
1980  // reextended to DestTy.
1981  Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
1982  Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(),
1983  Res1, DestTy);
1984 
1985  // If the re-extended constant didn't change...
1986  if (Res2 == CI) {
1987  // Deal with equality cases early.
1988  if (ICI.isEquality())
1989  return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
1990 
1991  // A signed comparison of sign extended values simplifies into a
1992  // signed comparison.
1993  if (isSignedExt && isSignedCmp)
1994  return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
1995 
1996  // The other three cases all fold into an unsigned comparison.
1997  return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1);
1998  }
1999 
2000  // The re-extended constant changed so the constant cannot be represented
2001  // in the shorter type. Consequently, we cannot emit a simple comparison.
2002  // All the cases that fold to true or false will have already been handled
2003  // by SimplifyICmpInst, so only deal with the tricky case.
2004 
2005  if (isSignedCmp || !isSignedExt)
2006  return nullptr;
2007 
2008  // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
2009  // should have been folded away previously and not enter in here.
2010 
2011  // We're performing an unsigned comp with a sign extended value.
2012  // This is true if the input is >= 0. [aka >s -1]
2013  Constant *NegOne = Constant::getAllOnesValue(SrcTy);
2014  Value *Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName());
2015 
2016  // Finally, return the value computed.
2017  if (ICI.getPredicate() == ICmpInst::ICMP_ULT)
2018  return ReplaceInstUsesWith(ICI, Result);
2019 
2020  assert(ICI.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!");
2021  return BinaryOperator::CreateNot(Result);
2022 }
2023 
2024 /// ProcessUGT_ADDCST_ADD - The caller has matched a pattern of the form:
2025 /// I = icmp ugt (add (add A, B), CI2), CI1
2026 /// If this is of the form:
2027 /// sum = a + b
2028 /// if (sum+128 >u 255)
2029 /// Then replace it with llvm.sadd.with.overflow.i8.
2030 ///
2032  ConstantInt *CI2, ConstantInt *CI1,
2033  InstCombiner &IC) {
2034  // The transformation we're trying to do here is to transform this into an
2035  // llvm.sadd.with.overflow. To do this, we have to replace the original add
2036  // with a narrower add, and discard the add-with-constant that is part of the
2037  // range check (if we can't eliminate it, this isn't profitable).
2038 
2039  // In order to eliminate the add-with-constant, the compare can be its only
2040  // use.
2041  Instruction *AddWithCst = cast<Instruction>(I.getOperand(0));
2042  if (!AddWithCst->hasOneUse()) return nullptr;
2043 
2044  // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow.
2045  if (!CI2->getValue().isPowerOf2()) return nullptr;
2046  unsigned NewWidth = CI2->getValue().countTrailingZeros();
2047  if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31) return nullptr;
2048 
2049  // The width of the new add formed is 1 more than the bias.
2050  ++NewWidth;
2051 
2052  // Check to see that CI1 is an all-ones value with NewWidth bits.
2053  if (CI1->getBitWidth() == NewWidth ||
2054  CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth))
2055  return nullptr;
2056 
2057  // This is only really a signed overflow check if the inputs have been
2058  // sign-extended; check for that condition. For example, if CI2 is 2^31 and
2059  // the operands of the add are 64 bits wide, we need at least 33 sign bits.
2060  unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1;
2061  if (IC.ComputeNumSignBits(A, 0, &I) < NeededSignBits ||
2062  IC.ComputeNumSignBits(B, 0, &I) < NeededSignBits)
2063  return nullptr;
2064 
2065  // In order to replace the original add with a narrower
2066  // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant
2067  // and truncates that discard the high bits of the add. Verify that this is
2068  // the case.
2069  Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0));
2070  for (User *U : OrigAdd->users()) {
2071  if (U == AddWithCst) continue;
2072 
2073  // Only accept truncates for now. We would really like a nice recursive
2074  // predicate like SimplifyDemandedBits, but which goes downwards the use-def
2075  // chain to see which bits of a value are actually demanded. If the
2076  // original add had another add which was then immediately truncated, we
2077  // could still do the transformation.
2078  TruncInst *TI = dyn_cast<TruncInst>(U);
2079  if (!TI || TI->getType()->getPrimitiveSizeInBits() > NewWidth)
2080  return nullptr;
2081  }
2082 
2083  // If the pattern matches, truncate the inputs to the narrower type and
2084  // use the sadd_with_overflow intrinsic to efficiently compute both the
2085  // result and the overflow bit.
2086  Module *M = I.getParent()->getParent()->getParent();
2087 
2088  Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth);
2089  Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow,
2090  NewType);
2091 
2092  InstCombiner::BuilderTy *Builder = IC.Builder;
2093 
2094  // Put the new code above the original add, in case there are any uses of the
2095  // add between the add and the compare.
2096  Builder->SetInsertPoint(OrigAdd);
2097 
2098  Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName()+".trunc");
2099  Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName()+".trunc");
2100  CallInst *Call = Builder->CreateCall(F, {TruncA, TruncB}, "sadd");
2101  Value *Add = Builder->CreateExtractValue(Call, 0, "sadd.result");
2102  Value *ZExt = Builder->CreateZExt(Add, OrigAdd->getType());
2103 
2104  // The inner add was the result of the narrow add, zero extended to the
2105  // wider type. Replace it with the result computed by the intrinsic.
2106  IC.ReplaceInstUsesWith(*OrigAdd, ZExt);
2107 
2108  // The original icmp gets replaced with the overflow value.
2109  return ExtractValueInst::Create(Call, 1, "sadd.overflow");
2110 }
2111 
2112 bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
2113  Value *RHS, Instruction &OrigI,
2114  Value *&Result, Constant *&Overflow) {
2115  if (OrigI.isCommutative() && isa<Constant>(LHS) && !isa<Constant>(RHS))
2116  std::swap(LHS, RHS);
2117 
2118  auto SetResult = [&](Value *OpResult, Constant *OverflowVal, bool ReuseName) {
2119  Result = OpResult;
2120  Overflow = OverflowVal;
2121  if (ReuseName)
2122  Result->takeName(&OrigI);
2123  return true;
2124  };
2125 
2126  switch (OCF) {
2127  case OCF_INVALID:
2128  llvm_unreachable("bad overflow check kind!");
2129 
2130  case OCF_UNSIGNED_ADD: {
2131  OverflowResult OR = computeOverflowForUnsignedAdd(LHS, RHS, &OrigI);
2133  return SetResult(Builder->CreateNUWAdd(LHS, RHS), Builder->getFalse(),
2134  true);
2135 
2137  return SetResult(Builder->CreateAdd(LHS, RHS), Builder->getTrue(), true);
2138  }
2139  // FALL THROUGH uadd into sadd
2140  case OCF_SIGNED_ADD: {
2141  // X + 0 -> {X, false}
2142  if (match(RHS, m_Zero()))
2143  return SetResult(LHS, Builder->getFalse(), false);
2144 
2145  // We can strength reduce this signed add into a regular add if we can prove
2146  // that it will never overflow.
2147  if (OCF == OCF_SIGNED_ADD)
2148  if (WillNotOverflowSignedAdd(LHS, RHS, OrigI))
2149  return SetResult(Builder->CreateNSWAdd(LHS, RHS), Builder->getFalse(),
2150  true);
2151  break;
2152  }
2153 
2154  case OCF_UNSIGNED_SUB:
2155  case OCF_SIGNED_SUB: {
2156  // X - 0 -> {X, false}
2157  if (match(RHS, m_Zero()))
2158  return SetResult(LHS, Builder->getFalse(), false);
2159 
2160  if (OCF == OCF_SIGNED_SUB) {
2161  if (WillNotOverflowSignedSub(LHS, RHS, OrigI))
2162  return SetResult(Builder->CreateNSWSub(LHS, RHS), Builder->getFalse(),
2163  true);
2164  } else {
2165  if (WillNotOverflowUnsignedSub(LHS, RHS, OrigI))
2166  return SetResult(Builder->CreateNUWSub(LHS, RHS), Builder->getFalse(),
2167  true);
2168  }
2169  break;
2170  }
2171 
2172  case OCF_UNSIGNED_MUL: {
2173  OverflowResult OR = computeOverflowForUnsignedMul(LHS, RHS, &OrigI);
2175  return SetResult(Builder->CreateNUWMul(LHS, RHS), Builder->getFalse(),
2176  true);
2178  return SetResult(Builder->CreateMul(LHS, RHS), Builder->getTrue(), true);
2179  } // FALL THROUGH
2180  case OCF_SIGNED_MUL:
2181  // X * undef -> undef
2182  if (isa<UndefValue>(RHS))
2183  return SetResult(RHS, UndefValue::get(Builder->getInt1Ty()), false);
2184 
2185  // X * 0 -> {0, false}
2186  if (match(RHS, m_Zero()))
2187  return SetResult(RHS, Builder->getFalse(), false);
2188 
2189  // X * 1 -> {X, false}
2190  if (match(RHS, m_One()))
2191  return SetResult(LHS, Builder->getFalse(), false);
2192 
2193  if (OCF == OCF_SIGNED_MUL)
2194  if (WillNotOverflowSignedMul(LHS, RHS, OrigI))
2195  return SetResult(Builder->CreateNSWMul(LHS, RHS), Builder->getFalse(),
2196  true);
2197  break;
2198  }
2199 
2200  return false;
2201 }
2202 
2203 /// \brief Recognize and process idiom involving test for multiplication
2204 /// overflow.
2205 ///
2206 /// The caller has matched a pattern of the form:
2207 /// I = cmp u (mul(zext A, zext B), V
2208 /// The function checks if this is a test for overflow and if so replaces
2209 /// multiplication with call to 'mul.with.overflow' intrinsic.
2210 ///
2211 /// \param I Compare instruction.
2212 /// \param MulVal Result of 'mult' instruction. It is one of the arguments of
2213 /// the compare instruction. Must be of integer type.
2214 /// \param OtherVal The other argument of compare instruction.
2215 /// \returns Instruction which must replace the compare instruction, NULL if no
2216 /// replacement required.
2218  Value *OtherVal, InstCombiner &IC) {
2219  // Don't bother doing this transformation for pointers, don't do it for
2220  // vectors.
2221  if (!isa<IntegerType>(MulVal->getType()))
2222  return nullptr;
2223 
2224  assert(I.getOperand(0) == MulVal || I.getOperand(1) == MulVal);
2225  assert(I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal);
2226  Instruction *MulInstr = cast<Instruction>(MulVal);
2227  assert(MulInstr->getOpcode() == Instruction::Mul);
2228 
2229  auto *LHS = cast<ZExtOperator>(MulInstr->getOperand(0)),
2230  *RHS = cast<ZExtOperator>(MulInstr->getOperand(1));
2231  assert(LHS->getOpcode() == Instruction::ZExt);
2232  assert(RHS->getOpcode() == Instruction::ZExt);
2233  Value *A = LHS->getOperand(0), *B = RHS->getOperand(0);
2234 
2235  // Calculate type and width of the result produced by mul.with.overflow.
2236  Type *TyA = A->getType(), *TyB = B->getType();
2237  unsigned WidthA = TyA->getPrimitiveSizeInBits(),
2238  WidthB = TyB->getPrimitiveSizeInBits();
2239  unsigned MulWidth;
2240  Type *MulType;
2241  if (WidthB > WidthA) {
2242  MulWidth = WidthB;
2243  MulType = TyB;
2244  } else {
2245  MulWidth = WidthA;
2246  MulType = TyA;
2247  }
2248 
2249  // In order to replace the original mul with a narrower mul.with.overflow,
2250  // all uses must ignore upper bits of the product. The number of used low
2251  // bits must be not greater than the width of mul.with.overflow.
2252  if (MulVal->hasNUsesOrMore(2))
2253  for (User *U : MulVal->users()) {
2254  if (U == &I)
2255  continue;
2256  if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
2257  // Check if truncation ignores bits above MulWidth.
2258  unsigned TruncWidth = TI->getType()->getPrimitiveSizeInBits();
2259  if (TruncWidth > MulWidth)
2260  return nullptr;
2261  } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
2262  // Check if AND ignores bits above MulWidth.
2263  if (BO->getOpcode() != Instruction::And)
2264  return nullptr;
2265  if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2266  const APInt &CVal = CI->getValue();
2267  if (CVal.getBitWidth() - CVal.countLeadingZeros() > MulWidth)
2268  return nullptr;
2269  }
2270  } else {
2271  // Other uses prohibit this transformation.
2272  return nullptr;
2273  }
2274  }
2275 
2276  // Recognize patterns
2277  switch (I.getPredicate()) {
2278  case ICmpInst::ICMP_EQ:
2279  case ICmpInst::ICMP_NE:
2280  // Recognize pattern:
2281  // mulval = mul(zext A, zext B)
2282  // cmp eq/neq mulval, zext trunc mulval
2283  if (ZExtInst *Zext = dyn_cast<ZExtInst>(OtherVal))
2284  if (Zext->hasOneUse()) {
2285  Value *ZextArg = Zext->getOperand(0);
2286  if (TruncInst *Trunc = dyn_cast<TruncInst>(ZextArg))
2287  if (Trunc->getType()->getPrimitiveSizeInBits() == MulWidth)
2288  break; //Recognized
2289  }
2290 
2291  // Recognize pattern:
2292  // mulval = mul(zext A, zext B)
2293  // cmp eq/neq mulval, and(mulval, mask), mask selects low MulWidth bits.
2294  ConstantInt *CI;
2295  Value *ValToMask;
2296  if (match(OtherVal, m_And(m_Value(ValToMask), m_ConstantInt(CI)))) {
2297  if (ValToMask != MulVal)
2298  return nullptr;
2299  const APInt &CVal = CI->getValue() + 1;
2300  if (CVal.isPowerOf2()) {
2301  unsigned MaskWidth = CVal.logBase2();
2302  if (MaskWidth == MulWidth)
2303  break; // Recognized
2304  }
2305  }
2306  return nullptr;
2307 
2308  case ICmpInst::ICMP_UGT:
2309  // Recognize pattern:
2310  // mulval = mul(zext A, zext B)
2311  // cmp ugt mulval, max
2312  if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
2313  APInt MaxVal = APInt::getMaxValue(MulWidth);
2314  MaxVal = MaxVal.zext(CI->getBitWidth());
2315  if (MaxVal.eq(CI->getValue()))
2316  break; // Recognized
2317  }
2318  return nullptr;
2319 
2320  case ICmpInst::ICMP_UGE:
2321  // Recognize pattern:
2322  // mulval = mul(zext A, zext B)
2323  // cmp uge mulval, max+1
2324  if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
2325  APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
2326  if (MaxVal.eq(CI->getValue()))
2327  break; // Recognized
2328  }
2329  return nullptr;
2330 
2331  case ICmpInst::ICMP_ULE:
2332  // Recognize pattern:
2333  // mulval = mul(zext A, zext B)
2334  // cmp ule mulval, max
2335  if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
2336  APInt MaxVal = APInt::getMaxValue(MulWidth);
2337  MaxVal = MaxVal.zext(CI->getBitWidth());
2338  if (MaxVal.eq(CI->getValue()))
2339  break; // Recognized
2340  }
2341  return nullptr;
2342 
2343  case ICmpInst::ICMP_ULT:
2344  // Recognize pattern:
2345  // mulval = mul(zext A, zext B)
2346  // cmp ule mulval, max + 1
2347  if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
2348  APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
2349  if (MaxVal.eq(CI->getValue()))
2350  break; // Recognized
2351  }
2352  return nullptr;
2353 
2354  default:
2355  return nullptr;
2356  }
2357 
2358  InstCombiner::BuilderTy *Builder = IC.Builder;
2359  Builder->SetInsertPoint(MulInstr);
2360  Module *M = I.getParent()->getParent()->getParent();
2361 
2362  // Replace: mul(zext A, zext B) --> mul.with.overflow(A, B)
2363  Value *MulA = A, *MulB = B;
2364  if (WidthA < MulWidth)
2365  MulA = Builder->CreateZExt(A, MulType);
2366  if (WidthB < MulWidth)
2367  MulB = Builder->CreateZExt(B, MulType);
2368  Value *F =
2369  Intrinsic::getDeclaration(M, Intrinsic::umul_with_overflow, MulType);
2370  CallInst *Call = Builder->CreateCall(F, {MulA, MulB}, "umul");
2371  IC.Worklist.Add(MulInstr);
2372 
2373  // If there are uses of mul result other than the comparison, we know that
2374  // they are truncation or binary AND. Change them to use result of
2375  // mul.with.overflow and adjust properly mask/size.
2376  if (MulVal->hasNUsesOrMore(2)) {
2377  Value *Mul = Builder->CreateExtractValue(Call, 0, "umul.value");
2378  for (User *U : MulVal->users()) {
2379  if (U == &I || U == OtherVal)
2380  continue;
2381  if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
2382  if (TI->getType()->getPrimitiveSizeInBits() == MulWidth)
2383  IC.ReplaceInstUsesWith(*TI, Mul);
2384  else
2385  TI->setOperand(0, Mul);
2386  } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
2387  assert(BO->getOpcode() == Instruction::And);
2388  // Replace (mul & mask) --> zext (mul.with.overflow & short_mask)
2389  ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));
2390  APInt ShortMask = CI->getValue().trunc(MulWidth);
2391  Value *ShortAnd = Builder->CreateAnd(Mul, ShortMask);
2392  Instruction *Zext =
2393  cast<Instruction>(Builder->CreateZExt(ShortAnd, BO->getType()));
2394  IC.Worklist.Add(Zext);
2395  IC.ReplaceInstUsesWith(*BO, Zext);
2396  } else {
2397  llvm_unreachable("Unexpected Binary operation");
2398  }
2399  IC.Worklist.Add(cast<Instruction>(U));
2400  }
2401  }
2402  if (isa<Instruction>(OtherVal))
2403  IC.Worklist.Add(cast<Instruction>(OtherVal));
2404 
2405  // The original icmp gets replaced with the overflow value, maybe inverted
2406  // depending on predicate.
2407  bool Inverse = false;
2408  switch (I.getPredicate()) {
2409  case ICmpInst::ICMP_NE:
2410  break;
2411  case ICmpInst::ICMP_EQ:
2412  Inverse = true;
2413  break;
2414  case ICmpInst::ICMP_UGT:
2415  case ICmpInst::ICMP_UGE:
2416  if (I.getOperand(0) == MulVal)
2417  break;
2418  Inverse = true;
2419  break;
2420  case ICmpInst::ICMP_ULT:
2421  case ICmpInst::ICMP_ULE:
2422  if (I.getOperand(1) == MulVal)
2423  break;
2424  Inverse = true;
2425  break;
2426  default:
2427  llvm_unreachable("Unexpected predicate");
2428  }
2429  if (Inverse) {
2430  Value *Res = Builder->CreateExtractValue(Call, 1);
2431  return BinaryOperator::CreateNot(Res);
2432  }
2433 
2434  return ExtractValueInst::Create(Call, 1);
2435 }
2436 
2437 // DemandedBitsLHSMask - When performing a comparison against a constant,
2438 // it is possible that not all the bits in the LHS are demanded. This helper
2439 // method computes the mask that IS demanded.
2441  unsigned BitWidth, bool isSignCheck) {
2442  if (isSignCheck)
2443  return APInt::getSignBit(BitWidth);
2444 
2446  if (!CI) return APInt::getAllOnesValue(BitWidth);
2447  const APInt &RHS = CI->getValue();
2448 
2449  switch (I.getPredicate()) {
2450  // For a UGT comparison, we don't care about any bits that
2451  // correspond to the trailing ones of the comparand. The value of these
2452  // bits doesn't impact the outcome of the comparison, because any value
2453  // greater than the RHS must differ in a bit higher than these due to carry.
2454  case ICmpInst::ICMP_UGT: {
2455  unsigned trailingOnes = RHS.countTrailingOnes();
2456  APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingOnes);
2457  return ~lowBitsSet;
2458  }
2459 
2460  // Similarly, for a ULT comparison, we don't care about the trailing zeros.
2461  // Any value less than the RHS must differ in a higher bit because of carries.
2462  case ICmpInst::ICMP_ULT: {
2463  unsigned trailingZeros = RHS.countTrailingZeros();
2464  APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingZeros);
2465  return ~lowBitsSet;
2466  }
2467 
2468  default:
2469  return APInt::getAllOnesValue(BitWidth);
2470  }
2471 
2472 }
2473 
2474 /// \brief Check if the order of \p Op0 and \p Op1 as operand in an ICmpInst
2475 /// should be swapped.
2476 /// The decision is based on how many times these two operands are reused
2477 /// as subtract operands and their positions in those instructions.
2478 /// The rational is that several architectures use the same instruction for
2479 /// both subtract and cmp, thus it is better if the order of those operands
2480 /// match.
2481 /// \return true if Op0 and Op1 should be swapped.
2482 static bool swapMayExposeCSEOpportunities(const Value * Op0,
2483  const Value * Op1) {
2484  // Filter out pointer value as those cannot appears directly in subtract.
2485  // FIXME: we may want to go through inttoptrs or bitcasts.
2486  if (Op0->getType()->isPointerTy())
2487  return false;
2488  // Count every uses of both Op0 and Op1 in a subtract.
2489  // Each time Op0 is the first operand, count -1: swapping is bad, the
2490  // subtract has already the same layout as the compare.
2491  // Each time Op0 is the second operand, count +1: swapping is good, the
2492  // subtract has a different layout as the compare.
2493  // At the end, if the benefit is greater than 0, Op0 should come second to
2494  // expose more CSE opportunities.
2495  int GlobalSwapBenefits = 0;
2496  for (const User *U : Op0->users()) {
2497  const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(U);
2498  if (!BinOp || BinOp->getOpcode() != Instruction::Sub)
2499  continue;
2500  // If Op0 is the first argument, this is not beneficial to swap the
2501  // arguments.
2502  int LocalSwapBenefits = -1;
2503  unsigned Op1Idx = 1;
2504  if (BinOp->getOperand(Op1Idx) == Op0) {
2505  Op1Idx = 0;
2506  LocalSwapBenefits = 1;
2507  }
2508  if (BinOp->getOperand(Op1Idx) != Op1)
2509  continue;
2510  GlobalSwapBenefits += LocalSwapBenefits;
2511  }
2512  return GlobalSwapBenefits > 0;
2513 }
2514 
2515 /// \brief Check that one use is in the same block as the definition and all
2516 /// other uses are in blocks dominated by a given block
2517 ///
2518 /// \param DI Definition
2519 /// \param UI Use
2520 /// \param DB Block that must dominate all uses of \p DI outside
2521 /// the parent block
2522 /// \return true when \p UI is the only use of \p DI in the parent block
2523 /// and all other uses of \p DI are in blocks dominated by \p DB.
2524 ///
2526  const Instruction *UI,
2527  const BasicBlock *DB) const {
2528  assert(DI && UI && "Instruction not defined\n");
2529  // ignore incomplete definitions
2530  if (!DI->getParent())
2531  return false;
2532  // DI and UI must be in the same block
2533  if (DI->getParent() != UI->getParent())
2534  return false;
2535  // Protect from self-referencing blocks
2536  if (DI->getParent() == DB)
2537  return false;
2538  // DominatorTree available?
2539  if (!DT)
2540  return false;
2541  for (const User *U : DI->users()) {
2542  auto *Usr = cast<Instruction>(U);
2543  if (Usr != UI && !DT->dominates(DB, Usr->getParent()))
2544  return false;
2545  }
2546  return true;
2547 }
2548 
2549 ///
2550 /// true when the instruction sequence within a block is select-cmp-br.
2551 ///
2552 static bool isChainSelectCmpBranch(const SelectInst *SI) {
2553  const BasicBlock *BB = SI->getParent();
2554  if (!BB)
2555  return false;
2556  auto *BI = dyn_cast_or_null<BranchInst>(BB->getTerminator());
2557  if (!BI || BI->getNumSuccessors() != 2)
2558  return false;
2559  auto *IC = dyn_cast<ICmpInst>(BI->getCondition());
2560  if (!IC || (IC->getOperand(0) != SI && IC->getOperand(1) != SI))
2561  return false;
2562  return true;
2563 }
2564 
2565 ///
2566 /// \brief True when a select result is replaced by one of its operands
2567 /// in select-icmp sequence. This will eventually result in the elimination
2568 /// of the select.
2569 ///
2570 /// \param SI Select instruction
2571 /// \param Icmp Compare instruction
2572 /// \param SIOpd Operand that replaces the select
2573 ///
2574 /// Notes:
2575 /// - The replacement is global and requires dominator information
2576 /// - The caller is responsible for the actual replacement
2577 ///
2578 /// Example:
2579 ///
2580 /// entry:
2581 /// %4 = select i1 %3, %C* %0, %C* null
2582 /// %5 = icmp eq %C* %4, null
2583 /// br i1 %5, label %9, label %7
2584 /// ...
2585 /// ; <label>:7 ; preds = %entry
2586 /// %8 = getelementptr inbounds %C* %4, i64 0, i32 0
2587 /// ...
2588 ///
2589 /// can be transformed to
2590 ///
2591 /// %5 = icmp eq %C* %0, null
2592 /// %6 = select i1 %3, i1 %5, i1 true
2593 /// br i1 %6, label %9, label %7
2594 /// ...
2595 /// ; <label>:7 ; preds = %entry
2596 /// %8 = getelementptr inbounds %C* %0, i64 0, i32 0 // replace by %0!
2597 ///
2598 /// Similar when the first operand of the select is a constant or/and
2599 /// the compare is for not equal rather than equal.
2600 ///
2601 /// NOTE: The function is only called when the select and compare constants
2602 /// are equal, the optimization can work only for EQ predicates. This is not a
2603 /// major restriction since a NE compare should be 'normalized' to an equal
2604 /// compare, which usually happens in the combiner and test case
2605 /// select-cmp-br.ll
2606 /// checks for it.
2608  const ICmpInst *Icmp,
2609  const unsigned SIOpd) {
2610  assert((SIOpd == 1 || SIOpd == 2) && "Invalid select operand!");
2611  if (isChainSelectCmpBranch(SI) && Icmp->getPredicate() == ICmpInst::ICMP_EQ) {
2612  BasicBlock *Succ = SI->getParent()->getTerminator()->getSuccessor(1);
2613  // The check for the unique predecessor is not the best that can be
2614  // done. But it protects efficiently against cases like when SI's
2615  // home block has two successors, Succ and Succ1, and Succ1 predecessor
2616  // of Succ. Then SI can't be replaced by SIOpd because the use that gets
2617  // replaced can be reached on either path. So the uniqueness check
2618  // guarantees that the path all uses of SI (outside SI's parent) are on
2619  // is disjoint from all other paths out of SI. But that information
2620  // is more expensive to compute, and the trade-off here is in favor
2621  // of compile-time.
2622  if (Succ->getUniquePredecessor() && dominatesAllUses(SI, Icmp, Succ)) {
2623  NumSel++;
2624  SI->replaceUsesOutsideBlock(SI->getOperand(SIOpd), SI->getParent());
2625  return true;
2626  }
2627  }
2628  return false;
2629 }
2630 
2632  bool Changed = false;
2633  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2634  unsigned Op0Cplxity = getComplexity(Op0);
2635  unsigned Op1Cplxity = getComplexity(Op1);
2636 
2637  /// Orders the operands of the compare so that they are listed from most
2638  /// complex to least complex. This puts constants before unary operators,
2639  /// before binary operators.
2640  if (Op0Cplxity < Op1Cplxity ||
2641  (Op0Cplxity == Op1Cplxity &&
2642  swapMayExposeCSEOpportunities(Op0, Op1))) {
2643  I.swapOperands();
2644  std::swap(Op0, Op1);
2645  Changed = true;
2646  }
2647 
2648  if (Value *V =
2649  SimplifyICmpInst(I.getPredicate(), Op0, Op1, DL, TLI, DT, AC, &I))
2650  return ReplaceInstUsesWith(I, V);
2651 
2652  // comparing -val or val with non-zero is the same as just comparing val
2653  // ie, abs(val) != 0 -> val != 0
2654  if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero()))
2655  {
2656  Value *Cond, *SelectTrue, *SelectFalse;
2657  if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue),
2658  m_Value(SelectFalse)))) {
2659  if (Value *V = dyn_castNegVal(SelectTrue)) {
2660  if (V == SelectFalse)
2661  return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
2662  }
2663  else if (Value *V = dyn_castNegVal(SelectFalse)) {
2664  if (V == SelectTrue)
2665  return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
2666  }
2667  }
2668  }
2669 
2670  Type *Ty = Op0->getType();
2671 
2672  // icmp's with boolean values can always be turned into bitwise operations
2673  if (Ty->isIntegerTy(1)) {
2674  switch (I.getPredicate()) {
2675  default: llvm_unreachable("Invalid icmp instruction!");
2676  case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
2677  Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp");
2678  return BinaryOperator::CreateNot(Xor);
2679  }
2680  case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
2681  return BinaryOperator::CreateXor(Op0, Op1);
2682 
2683  case ICmpInst::ICMP_UGT:
2684  std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
2685  // FALL THROUGH
2686  case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
2687  Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
2688  return BinaryOperator::CreateAnd(Not, Op1);
2689  }
2690  case ICmpInst::ICMP_SGT:
2691  std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
2692  // FALL THROUGH
2693  case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
2694  Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
2695  return BinaryOperator::CreateAnd(Not, Op0);
2696  }
2697  case ICmpInst::ICMP_UGE:
2698  std::swap(Op0, Op1); // Change icmp uge -> icmp ule
2699  // FALL THROUGH
2700  case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
2701  Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
2702  return BinaryOperator::CreateOr(Not, Op1);
2703  }
2704  case ICmpInst::ICMP_SGE:
2705  std::swap(Op0, Op1); // Change icmp sge -> icmp sle
2706  // FALL THROUGH
2707  case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
2708  Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
2709  return BinaryOperator::CreateOr(Not, Op0);
2710  }
2711  }
2712  }
2713 
2714  unsigned BitWidth = 0;
2715  if (Ty->isIntOrIntVectorTy())
2716  BitWidth = Ty->getScalarSizeInBits();
2717  else // Get pointer size.
2718  BitWidth = DL.getTypeSizeInBits(Ty->getScalarType());
2719 
2720  bool isSignBit = false;
2721 
2722  // See if we are doing a comparison with a constant.
2723  if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2724  Value *A = nullptr, *B = nullptr;
2725 
2726  // Match the following pattern, which is a common idiom when writing
2727  // overflow-safe integer arithmetic function. The source performs an
2728  // addition in wider type, and explicitly checks for overflow using
2729  // comparisons against INT_MIN and INT_MAX. Simplify this by using the
2730  // sadd_with_overflow intrinsic.
2731  //
2732  // TODO: This could probably be generalized to handle other overflow-safe
2733  // operations if we worked out the formulas to compute the appropriate
2734  // magic constants.
2735  //
2736  // sum = a + b
2737  // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8
2738  {
2739  ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI
2740  if (I.getPredicate() == ICmpInst::ICMP_UGT &&
2741  match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2))))
2742  if (Instruction *Res = ProcessUGT_ADDCST_ADD(I, A, B, CI2, CI, *this))
2743  return Res;
2744  }
2745 
2746  // The following transforms are only 'worth it' if the only user of the
2747  // subtraction is the icmp.
2748  if (Op0->hasOneUse()) {
2749  // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
2750  if (I.isEquality() && CI->isZero() &&
2751  match(Op0, m_Sub(m_Value(A), m_Value(B))))
2752  return new ICmpInst(I.getPredicate(), A, B);
2753 
2754  // (icmp sgt (sub nsw A B), -1) -> (icmp sge A, B)
2755  if (I.getPredicate() == ICmpInst::ICMP_SGT && CI->isAllOnesValue() &&
2756  match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
2757  return new ICmpInst(ICmpInst::ICMP_SGE, A, B);
2758 
2759  // (icmp sgt (sub nsw A B), 0) -> (icmp sgt A, B)
2760  if (I.getPredicate() == ICmpInst::ICMP_SGT && CI->isZero() &&
2761  match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
2762  return new ICmpInst(ICmpInst::ICMP_SGT, A, B);
2763 
2764  // (icmp slt (sub nsw A B), 0) -> (icmp slt A, B)
2765  if (I.getPredicate() == ICmpInst::ICMP_SLT && CI->isZero() &&
2766  match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
2767  return new ICmpInst(ICmpInst::ICMP_SLT, A, B);
2768 
2769  // (icmp slt (sub nsw A B), 1) -> (icmp sle A, B)
2770  if (I.getPredicate() == ICmpInst::ICMP_SLT && CI->isOne() &&
2771  match(Op0, m_NSWSub(m_Value(A), m_Value(B))))
2772  return new ICmpInst(ICmpInst::ICMP_SLE, A, B);
2773  }
2774 
2775  // If we have an icmp le or icmp ge instruction, turn it into the
2776  // appropriate icmp lt or icmp gt instruction. This allows us to rely on
2777  // them being folded in the code below. The SimplifyICmpInst code has
2778  // already handled the edge cases for us, so we just assert on them.
2779  switch (I.getPredicate()) {
2780  default: break;
2781  case ICmpInst::ICMP_ULE:
2782  assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE
2783  return new ICmpInst(ICmpInst::ICMP_ULT, Op0,
2784  Builder->getInt(CI->getValue()+1));
2785  case ICmpInst::ICMP_SLE:
2786  assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE
2787  return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
2788  Builder->getInt(CI->getValue()+1));
2789  case ICmpInst::ICMP_UGE:
2790  assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE
2791  return new ICmpInst(ICmpInst::ICMP_UGT, Op0,
2792  Builder->getInt(CI->getValue()-1));
2793  case ICmpInst::ICMP_SGE:
2794  assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE
2795  return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
2796  Builder->getInt(CI->getValue()-1));
2797  }
2798 
2799  if (I.isEquality()) {
2800  ConstantInt *CI2;
2801  if (match(Op0, m_AShr(m_ConstantInt(CI2), m_Value(A))) ||
2802  match(Op0, m_LShr(m_ConstantInt(CI2), m_Value(A)))) {
2803  // (icmp eq/ne (ashr/lshr const2, A), const1)
2804  if (Instruction *Inst = FoldICmpCstShrCst(I, Op0, A, CI, CI2))
2805  return Inst;
2806  }
2807  if (match(Op0, m_Shl(m_ConstantInt(CI2), m_Value(A)))) {
2808  // (icmp eq/ne (shl const2, A), const1)
2809  if (Instruction *Inst = FoldICmpCstShlCst(I, Op0, A, CI, CI2))
2810  return Inst;
2811  }
2812  }
2813 
2814  // If this comparison is a normal comparison, it demands all
2815  // bits, if it is a sign bit comparison, it only demands the sign bit.
2816  bool UnusedBit;
2817  isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
2818  }
2819 
2820  // See if we can fold the comparison based on range information we can get
2821  // by checking whether bits are known to be zero or one in the input.
2822  if (BitWidth != 0) {
2823  APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
2824  APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
2825 
2826  if (SimplifyDemandedBits(I.getOperandUse(0),
2827  DemandedBitsLHSMask(I, BitWidth, isSignBit),
2828  Op0KnownZero, Op0KnownOne, 0))
2829  return &I;
2830  if (SimplifyDemandedBits(I.getOperandUse(1),
2831  APInt::getAllOnesValue(BitWidth), Op1KnownZero,
2832  Op1KnownOne, 0))
2833  return &I;
2834 
2835  // Given the known and unknown bits, compute a range that the LHS could be
2836  // in. Compute the Min, Max and RHS values based on the known bits. For the
2837  // EQ and NE we use unsigned values.
2838  APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
2839  APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
2840  if (I.isSigned()) {
2841  ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
2842  Op0Min, Op0Max);
2843  ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
2844  Op1Min, Op1Max);
2845  } else {
2846  ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
2847  Op0Min, Op0Max);
2848  ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
2849  Op1Min, Op1Max);
2850  }
2851 
2852  // If Min and Max are known to be the same, then SimplifyDemandedBits
2853  // figured out that the LHS is a constant. Just constant fold this now so
2854  // that code below can assume that Min != Max.
2855  if (!isa<Constant>(Op0) && Op0Min == Op0Max)
2856  return new ICmpInst(I.getPredicate(),
2857  ConstantInt::get(Op0->getType(), Op0Min), Op1);
2858  if (!isa<Constant>(Op1) && Op1Min == Op1Max)
2859  return new ICmpInst(I.getPredicate(), Op0,
2860  ConstantInt::get(Op1->getType(), Op1Min));
2861 
2862  // Based on the range information we know about the LHS, see if we can
2863  // simplify this comparison. For example, (x&4) < 8 is always true.
2864  switch (I.getPredicate()) {
2865  default: llvm_unreachable("Unknown icmp opcode!");
2866  case ICmpInst::ICMP_EQ: {
2867  if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
2868  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2869 
2870  // If all bits are known zero except for one, then we know at most one
2871  // bit is set. If the comparison is against zero, then this is a check
2872  // to see if *that* bit is set.
2873  APInt Op0KnownZeroInverted = ~Op0KnownZero;
2874  if (~Op1KnownZero == 0) {
2875  // If the LHS is an AND with the same constant, look through it.
2876  Value *LHS = nullptr;
2877  ConstantInt *LHSC = nullptr;
2878  if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) ||
2879  LHSC->getValue() != Op0KnownZeroInverted)
2880  LHS = Op0;
2881 
2882  // If the LHS is 1 << x, and we know the result is a power of 2 like 8,
2883  // then turn "((1 << x)&8) == 0" into "x != 3".
2884  // or turn "((1 << x)&7) == 0" into "x > 2".
2885  Value *X = nullptr;
2886  if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
2887  APInt ValToCheck = Op0KnownZeroInverted;
2888  if (ValToCheck.isPowerOf2()) {
2889  unsigned CmpVal = ValToCheck.countTrailingZeros();
2890  return new ICmpInst(ICmpInst::ICMP_NE, X,
2891  ConstantInt::get(X->getType(), CmpVal));
2892  } else if ((++ValToCheck).isPowerOf2()) {
2893  unsigned CmpVal = ValToCheck.countTrailingZeros() - 1;
2894  return new ICmpInst(ICmpInst::ICMP_UGT, X,
2895  ConstantInt::get(X->getType(), CmpVal));
2896  }
2897  }
2898 
2899  // If the LHS is 8 >>u x, and we know the result is a power of 2 like 1,
2900  // then turn "((8 >>u x)&1) == 0" into "x != 3".
2901  const APInt *CI;
2902  if (Op0KnownZeroInverted == 1 &&
2903  match(LHS, m_LShr(m_Power2(CI), m_Value(X))))
2904  return new ICmpInst(ICmpInst::ICMP_NE, X,
2906  CI->countTrailingZeros()));
2907  }
2908 
2909  break;
2910  }
2911  case ICmpInst::ICMP_NE: {
2912  if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
2913  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2914 
2915  // If all bits are known zero except for one, then we know at most one
2916  // bit is set. If the comparison is against zero, then this is a check
2917  // to see if *that* bit is set.
2918  APInt Op0KnownZeroInverted = ~Op0KnownZero;
2919  if (~Op1KnownZero == 0) {
2920  // If the LHS is an AND with the same constant, look through it.
2921  Value *LHS = nullptr;
2922  ConstantInt *LHSC = nullptr;
2923  if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) ||
2924  LHSC->getValue() != Op0KnownZeroInverted)
2925  LHS = Op0;
2926 
2927  // If the LHS is 1 << x, and we know the result is a power of 2 like 8,
2928  // then turn "((1 << x)&8) != 0" into "x == 3".
2929  // or turn "((1 << x)&7) != 0" into "x < 3".
2930  Value *X = nullptr;
2931  if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
2932  APInt ValToCheck = Op0KnownZeroInverted;
2933  if (ValToCheck.isPowerOf2()) {
2934  unsigned CmpVal = ValToCheck.countTrailingZeros();
2935  return new ICmpInst(ICmpInst::ICMP_EQ, X,
2936  ConstantInt::get(X->getType(), CmpVal));
2937  } else if ((++ValToCheck).isPowerOf2()) {
2938  unsigned CmpVal = ValToCheck.countTrailingZeros();
2939  return new ICmpInst(ICmpInst::ICMP_ULT, X,
2940  ConstantInt::get(X->getType(), CmpVal));
2941  }
2942  }
2943 
2944  // If the LHS is 8 >>u x, and we know the result is a power of 2 like 1,
2945  // then turn "((8 >>u x)&1) != 0" into "x == 3".
2946  const APInt *CI;
2947  if (Op0KnownZeroInverted == 1 &&
2948  match(LHS, m_LShr(m_Power2(CI), m_Value(X))))
2949  return new ICmpInst(ICmpInst::ICMP_EQ, X,
2951  CI->countTrailingZeros()));
2952  }
2953 
2954  break;
2955  }
2956  case ICmpInst::ICMP_ULT:
2957  if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
2958  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2959  if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
2960  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2961  if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
2962  return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
2963  if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2964  if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C
2965  return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
2966  Builder->getInt(CI->getValue()-1));
2967 
2968  // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
2969  if (CI->isMinValue(true))
2970  return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
2972  }
2973  break;
2974  case ICmpInst::ICMP_UGT:
2975  if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
2976  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2977  if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
2978  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2979 
2980  if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
2981  return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
2982  if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2983  if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C
2984  return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
2985  Builder->getInt(CI->getValue()+1));
2986 
2987  // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
2988  if (CI->isMaxValue(true))
2989  return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
2991  }
2992  break;
2993  case ICmpInst::ICMP_SLT:
2994  if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
2995  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2996  if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
2997  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2998  if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
2999  return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
3000  if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
3001  if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C
3002  return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
3003  Builder->getInt(CI->getValue()-1));
3004  }
3005  break;
3006  case ICmpInst::ICMP_SGT:
3007  if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
3008  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
3009  if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
3010  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3011 
3012  if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
3013  return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
3014  if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
3015  if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C
3016  return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
3017  Builder->getInt(CI->getValue()+1));
3018  }
3019  break;
3020  case ICmpInst::ICMP_SGE:
3021  assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
3022  if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
3023  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
3024  if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
3025  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3026  break;
3027  case ICmpInst::ICMP_SLE:
3028  assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
3029  if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
3030  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
3031  if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
3032  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3033  break;
3034  case ICmpInst::ICMP_UGE:
3035  assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
3036  if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
3037  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
3038  if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
3039  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3040  break;
3041  case ICmpInst::ICMP_ULE:
3042  assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
3043  if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
3044  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
3045  if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
3046  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3047  break;
3048  }
3049 
3050  // Turn a signed comparison into an unsigned one if both operands
3051  // are known to have the same sign.
3052  if (I.isSigned() &&
3053  ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
3054  (Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
3055  return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
3056  }
3057 
3058  // Test if the ICmpInst instruction is used exclusively by a select as
3059  // part of a minimum or maximum operation. If so, refrain from doing
3060  // any other folding. This helps out other analyses which understand
3061  // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
3062  // and CodeGen. And in this case, at least one of the comparison
3063  // operands has at least one user besides the compare (the select),
3064  // which would often largely negate the benefit of folding anyway.
3065  if (I.hasOneUse())
3066  if (SelectInst *SI = dyn_cast<SelectInst>(*I.user_begin()))
3067  if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
3068  (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
3069  return nullptr;
3070 
3071  // See if we are doing a comparison between a constant and an instruction that
3072  // can be folded into the comparison.
3073  if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
3074  // Since the RHS is a ConstantInt (CI), if the left hand side is an
3075  // instruction, see if that instruction also has constants so that the
3076  // instruction can be folded into the icmp
3077  if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3078  if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
3079  return Res;
3080  }
3081 
3082  // Handle icmp with constant (but not simple integer constant) RHS
3083  if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3084  if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3085  switch (LHSI->getOpcode()) {
3086  case Instruction::GetElementPtr:
3087  // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
3088  if (RHSC->isNullValue() &&
3089  cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
3090  return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
3091  Constant::getNullValue(LHSI->getOperand(0)->getType()));
3092  break;
3093  case Instruction::PHI:
3094  // Only fold icmp into the PHI if the phi and icmp are in the same
3095  // block. If in the same block, we're encouraging jump threading. If
3096  // not, we are just pessimizing the code by making an i1 phi.
3097  if (LHSI->getParent() == I.getParent())
3098  if (Instruction *NV = FoldOpIntoPhi(I))
3099  return NV;
3100  break;
3101  case Instruction::Select: {
3102  // If either operand of the select is a constant, we can fold the
3103  // comparison into the select arms, which will cause one to be
3104  // constant folded and the select turned into a bitwise or.
3105  Value *Op1 = nullptr, *Op2 = nullptr;
3106  ConstantInt *CI = 0;
3107  if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3108  Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
3109  CI = dyn_cast<ConstantInt>(Op1);
3110  }
3111  if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3112  Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
3113  CI = dyn_cast<ConstantInt>(Op2);
3114  }
3115 
3116  // We only want to perform this transformation if it will not lead to
3117  // additional code. This is true if either both sides of the select
3118  // fold to a constant (in which case the icmp is replaced with a select
3119  // which will usually simplify) or this is the only user of the
3120  // select (in which case we are trading a select+icmp for a simpler
3121  // select+icmp) or all uses of the select can be replaced based on
3122  // dominance information ("Global cases").
3123  bool Transform = false;
3124  if (Op1 && Op2)
3125  Transform = true;
3126  else if (Op1 || Op2) {
3127  // Local case
3128  if (LHSI->hasOneUse())
3129  Transform = true;
3130  // Global cases
3131  else if (CI && !CI->isZero())
3132  // When Op1 is constant try replacing select with second operand.
3133  // Otherwise Op2 is constant and try replacing select with first
3134  // operand.
3135  Transform = replacedSelectWithOperand(cast<SelectInst>(LHSI), &I,
3136  Op1 ? 2 : 1);
3137  }
3138  if (Transform) {
3139  if (!Op1)
3140  Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1),
3141  RHSC, I.getName());
3142  if (!Op2)
3143  Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2),
3144  RHSC, I.getName());
3145  return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
3146  }
3147  break;
3148  }
3149  case Instruction::IntToPtr:
3150  // icmp pred inttoptr(X), null -> icmp pred X, 0
3151  if (RHSC->isNullValue() &&
3152  DL.getIntPtrType(RHSC->getType()) == LHSI->getOperand(0)->getType())
3153  return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
3154  Constant::getNullValue(LHSI->getOperand(0)->getType()));
3155  break;
3156 
3157  case Instruction::Load:
3158  // Try to optimize things like "A[i] > 4" to index computations.
3159  if (GetElementPtrInst *GEP =
3160  dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
3161  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
3162  if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
3163  !cast<LoadInst>(LHSI)->isVolatile())
3164  if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
3165  return Res;
3166  }
3167  break;
3168  }
3169  }
3170 
3171  // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
3172  if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
3173  if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
3174  return NI;
3175  if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
3176  if (Instruction *NI = FoldGEPICmp(GEP, Op0,
3178  return NI;
3179 
3180  // Test to see if the operands of the icmp are casted versions of other
3181  // values. If the ptr->ptr cast can be stripped off both arguments, we do so
3182  // now.
3183  if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
3184  if (Op0->getType()->isPointerTy() &&
3185  (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
3186  // We keep moving the cast from the left operand over to the right
3187  // operand, where it can often be eliminated completely.
3188  Op0 = CI->getOperand(0);
3189 
3190  // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
3191  // so eliminate it as well.
3192  if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
3193  Op1 = CI2->getOperand(0);
3194 
3195  // If Op1 is a constant, we can fold the cast into the constant.
3196  if (Op0->getType() != Op1->getType()) {
3197  if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3198  Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
3199  } else {
3200  // Otherwise, cast the RHS right before the icmp
3201  Op1 = Builder->CreateBitCast(Op1, Op0->getType());
3202  }
3203  }
3204  return new ICmpInst(I.getPredicate(), Op0, Op1);
3205  }
3206  }
3207 
3208  if (isa<CastInst>(Op0)) {
3209  // Handle the special case of: icmp (cast bool to X), <cst>
3210  // This comes up when you have code like
3211  // int X = A < B;
3212  // if (X) ...
3213  // For generality, we handle any zero-extension of any operand comparison
3214  // with a constant or another cast from the same type.
3215  if (isa<Constant>(Op1) || isa<CastInst>(Op1))
3216  if (Instruction *R = visitICmpInstWithCastAndCast(I))
3217  return R;
3218  }
3219 
3220  // Special logic for binary operators.
3221  BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0);
3222  BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1);
3223  if (BO0 || BO1) {
3224  CmpInst::Predicate Pred = I.getPredicate();
3225  bool NoOp0WrapProblem = false, NoOp1WrapProblem = false;
3226  if (BO0 && isa<OverflowingBinaryOperator>(BO0))
3227  NoOp0WrapProblem = ICmpInst::isEquality(Pred) ||
3228  (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) ||
3229  (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap());
3230  if (BO1 && isa<OverflowingBinaryOperator>(BO1))
3231  NoOp1WrapProblem = ICmpInst::isEquality(Pred) ||
3232  (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) ||
3233  (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap());
3234 
3235  // Analyze the case when either Op0 or Op1 is an add instruction.
3236  // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
3237  Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
3238  if (BO0 && BO0->getOpcode() == Instruction::Add)
3239  A = BO0->getOperand(0), B = BO0->getOperand(1);
3240  if (BO1 && BO1->getOpcode() == Instruction::Add)
3241  C = BO1->getOperand(0), D = BO1->getOperand(1);
3242 
3243  // icmp (X+cst) < 0 --> X < -cst
3244  if (NoOp0WrapProblem && ICmpInst::isSigned(Pred) && match(Op1, m_Zero()))
3245  if (ConstantInt *RHSC = dyn_cast_or_null<ConstantInt>(B))
3246  if (!RHSC->isMinValue(/*isSigned=*/true))
3247  return new ICmpInst(Pred, A, ConstantExpr::getNeg(RHSC));
3248 
3249  // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
3250  if ((A == Op1 || B == Op1) && NoOp0WrapProblem)
3251  return new ICmpInst(Pred, A == Op1 ? B : A,
3252  Constant::getNullValue(Op1->getType()));
3253 
3254  // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
3255  if ((C == Op0 || D == Op0) && NoOp1WrapProblem)
3256  return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()),
3257  C == Op0 ? D : C);
3258 
3259  // icmp (X+Y), (X+Z) -> icmp Y, Z for equalities or if there is no overflow.
3260  if (A && C && (A == C || A == D || B == C || B == D) &&
3261  NoOp0WrapProblem && NoOp1WrapProblem &&
3262  // Try not to increase register pressure.
3263  BO0->hasOneUse() && BO1->hasOneUse()) {
3264  // Determine Y and Z in the form icmp (X+Y), (X+Z).
3265  Value *Y, *Z;
3266  if (A == C) {
3267  // C + B == C + D -> B == D
3268  Y = B;
3269  Z = D;
3270  } else if (A == D) {
3271  // D + B == C + D -> B == C
3272  Y = B;
3273  Z = C;
3274  } else if (B == C) {
3275  // A + C == C + D -> A == D
3276  Y = A;
3277  Z = D;
3278  } else {
3279  assert(B == D);
3280  // A + D == C + D -> A == C
3281  Y = A;
3282  Z = C;
3283  }
3284  return new ICmpInst(Pred, Y, Z);
3285  }
3286 
3287  // icmp slt (X + -1), Y -> icmp sle X, Y
3288  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT &&
3289  match(B, m_AllOnes()))
3290  return new ICmpInst(CmpInst::ICMP_SLE, A, Op1);
3291 
3292  // icmp sge (X + -1), Y -> icmp sgt X, Y
3293  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE &&
3294  match(B, m_AllOnes()))
3295  return new ICmpInst(CmpInst::ICMP_SGT, A, Op1);
3296 
3297  // icmp sle (X + 1), Y -> icmp slt X, Y
3298  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE &&
3299  match(B, m_One()))
3300  return new ICmpInst(CmpInst::ICMP_SLT, A, Op1);
3301 
3302  // icmp sgt (X + 1), Y -> icmp sge X, Y
3303  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT &&
3304  match(B, m_One()))
3305  return new ICmpInst(CmpInst::ICMP_SGE, A, Op1);
3306 
3307  // if C1 has greater magnitude than C2:
3308  // icmp (X + C1), (Y + C2) -> icmp (X + C3), Y
3309  // s.t. C3 = C1 - C2
3310  //
3311  // if C2 has greater magnitude than C1:
3312  // icmp (X + C1), (Y + C2) -> icmp X, (Y + C3)
3313  // s.t. C3 = C2 - C1
3314  if (A && C && NoOp0WrapProblem && NoOp1WrapProblem &&
3315  (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned())
3316  if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
3317  if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) {
3318  const APInt &AP1 = C1->getValue();
3319  const APInt &AP2 = C2->getValue();
3320  if (AP1.isNegative() == AP2.isNegative()) {
3321  APInt AP1Abs = C1->getValue().abs();
3322  APInt AP2Abs = C2->getValue().abs();
3323  if (AP1Abs.uge(AP2Abs)) {
3324  ConstantInt *C3 = Builder->getInt(AP1 - AP2);
3325  Value *NewAdd = Builder->CreateNSWAdd(A, C3);
3326  return new ICmpInst(Pred, NewAdd, C);
3327  } else {
3328  ConstantInt *C3 = Builder->getInt(AP2 - AP1);
3329  Value *NewAdd = Builder->CreateNSWAdd(C, C3);
3330  return new ICmpInst(Pred, A, NewAdd);
3331  }
3332  }
3333  }
3334 
3335 
3336  // Analyze the case when either Op0 or Op1 is a sub instruction.
3337  // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null).
3338  A = nullptr; B = nullptr; C = nullptr; D = nullptr;
3339  if (BO0 && BO0->getOpcode() == Instruction::Sub)
3340  A = BO0->getOperand(0), B = BO0->getOperand(1);
3341  if (BO1 && BO1->getOpcode() == Instruction::Sub)
3342  C = BO1->getOperand(0), D = BO1->getOperand(1);
3343 
3344  // icmp (X-Y), X -> icmp 0, Y for equalities or if there is no overflow.
3345  if (A == Op1 && NoOp0WrapProblem)
3346  return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B);
3347 
3348  // icmp X, (X-Y) -> icmp Y, 0 for equalities or if there is no overflow.
3349  if (C == Op0 && NoOp1WrapProblem)
3350  return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType()));
3351 
3352  // icmp (Y-X), (Z-X) -> icmp Y, Z for equalities or if there is no overflow.
3353  if (B && D && B == D && NoOp0WrapProblem && NoOp1WrapProblem &&
3354  // Try not to increase register pressure.
3355  BO0->hasOneUse() && BO1->hasOneUse())
3356  return new ICmpInst(Pred, A, C);
3357 
3358  // icmp (X-Y), (X-Z) -> icmp Z, Y for equalities or if there is no overflow.
3359  if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem &&
3360  // Try not to increase register pressure.
3361  BO0->hasOneUse() && BO1->hasOneUse())
3362  return new ICmpInst(Pred, D, B);
3363 
3364  // icmp (0-X) < cst --> x > -cst
3365  if (NoOp0WrapProblem && ICmpInst::isSigned(Pred)) {
3366  Value *X;
3367  if (match(BO0, m_Neg(m_Value(X))))
3368  if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1))
3369  if (!RHSC->isMinValue(/*isSigned=*/true))
3370  return new ICmpInst(I.getSwappedPredicate(), X,
3371  ConstantExpr::getNeg(RHSC));
3372  }
3373 
3374  BinaryOperator *SRem = nullptr;
3375  // icmp (srem X, Y), Y
3376  if (BO0 && BO0->getOpcode() == Instruction::SRem &&
3377  Op1 == BO0->getOperand(1))
3378  SRem = BO0;
3379  // icmp Y, (srem X, Y)
3380  else if (BO1 && BO1->getOpcode() == Instruction::SRem &&
3381  Op0 == BO1->getOperand(1))
3382  SRem = BO1;
3383  if (SRem) {
3384  // We don't check hasOneUse to avoid increasing register pressure because
3385  // the value we use is the same value this instruction was already using.
3386  switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) {
3387  default: break;
3388  case ICmpInst::ICMP_EQ:
3389  return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3390  case ICmpInst::ICMP_NE:
3391  return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
3392  case ICmpInst::ICMP_SGT:
3393  case ICmpInst::ICMP_SGE:
3394  return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1),
3396  case ICmpInst::ICMP_SLT:
3397  case ICmpInst::ICMP_SLE:
3398  return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1),
3399  Constant::getNullValue(SRem->getType()));
3400  }
3401  }
3402 
3403  if (BO0 && BO1 && BO0->getOpcode() == BO1->getOpcode() &&
3404  BO0->hasOneUse() && BO1->hasOneUse() &&
3405  BO0->getOperand(1) == BO1->getOperand(1)) {
3406  switch (BO0->getOpcode()) {
3407  default: break;
3408  case Instruction::Add:
3409  case Instruction::Sub:
3410  case Instruction::Xor:
3411  if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
3412  return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
3413  BO1->getOperand(0));
3414  // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
3415  if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) {
3416  if (CI->getValue().isSignBit()) {
3417  ICmpInst::Predicate Pred = I.isSigned()
3418  ? I.getUnsignedPredicate()
3419  : I.getSignedPredicate();
3420  return new ICmpInst(Pred, BO0->getOperand(0),
3421  BO1->getOperand(0));
3422  }
3423 
3424  if (CI->isMaxValue(true)) {
3425  ICmpInst::Predicate Pred = I.isSigned()
3426  ? I.getUnsignedPredicate()
3427  : I.getSignedPredicate();
3428  Pred = I.getSwappedPredicate(Pred);
3429  return new ICmpInst(Pred, BO0->getOperand(0),
3430  BO1->getOperand(0));
3431  }
3432  }
3433  break;
3434  case Instruction::Mul:
3435  if (!I.isEquality())
3436  break;
3437 
3438  if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) {
3439  // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
3440  // Mask = -1 >> count-trailing-zeros(Cst).
3441  if (!CI->isZero() && !CI->isOne()) {
3442  const APInt &AP = CI->getValue();
3445  AP.getBitWidth() -
3446  AP.countTrailingZeros()));
3447  Value *And1 = Builder->CreateAnd(BO0->getOperand(0), Mask);
3448  Value *And2 = Builder->CreateAnd(BO1->getOperand(0), Mask);
3449  return new ICmpInst(I.getPredicate(), And1, And2);
3450  }
3451  }
3452  break;
3453  case Instruction::UDiv:
3454  case Instruction::LShr:
3455  if (I.isSigned())
3456  break;
3457  // fall-through
3458  case Instruction::SDiv:
3459  case Instruction::AShr:
3460  if (!BO0->isExact() || !BO1->isExact())
3461  break;
3462  return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
3463  BO1->getOperand(0));
3464  case Instruction::Shl: {
3465  bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap();
3466  bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap();
3467  if (!NUW && !NSW)
3468  break;
3469  if (!NSW && I.isSigned())
3470  break;
3471  return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
3472  BO1->getOperand(0));
3473  }
3474  }
3475  }
3476  }
3477 
3478  { Value *A, *B;
3479  // Transform (A & ~B) == 0 --> (A & B) != 0
3480  // and (A & ~B) != 0 --> (A & B) == 0
3481  // if A is a power of 2.
3482  if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
3483  match(Op1, m_Zero()) &&
3484  isKnownToBeAPowerOfTwo(A, DL, false, 0, AC, &I, DT) && I.isEquality())
3485  return new ICmpInst(I.getInversePredicate(),
3486  Builder->CreateAnd(A, B),
3487  Op1);
3488 
3489  // ~x < ~y --> y < x
3490  // ~x < cst --> ~cst < x
3491  if (match(Op0, m_Not(m_Value(A)))) {
3492  if (match(Op1, m_Not(m_Value(B))))
3493  return new ICmpInst(I.getPredicate(), B, A);
3494  if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1))
3495  return new ICmpInst(I.getPredicate(), ConstantExpr::getNot(RHSC), A);
3496  }
3497 
3498  Instruction *AddI = nullptr;
3499  if (match(&I, m_UAddWithOverflow(m_Value(A), m_Value(B),
3500  m_Instruction(AddI))) &&
3501  isa<IntegerType>(A->getType())) {
3502  Value *Result;
3503  Constant *Overflow;
3504  if (OptimizeOverflowCheck(OCF_UNSIGNED_ADD, A, B, *AddI, Result,
3505  Overflow)) {
3506  ReplaceInstUsesWith(*AddI, Result);
3507  return ReplaceInstUsesWith(I, Overflow);
3508  }
3509  }
3510 
3511  // (zext a) * (zext b) --> llvm.umul.with.overflow.
3512  if (match(Op0, m_Mul(m_ZExt(m_Value(A)), m_ZExt(m_Value(B))))) {
3513  if (Instruction *R = ProcessUMulZExtIdiom(I, Op0, Op1, *this))
3514  return R;
3515  }
3516  if (match(Op1, m_Mul(m_ZExt(m_Value(A)), m_ZExt(m_Value(B))))) {
3517  if (Instruction *R = ProcessUMulZExtIdiom(I, Op1, Op0, *this))
3518  return R;
3519  }
3520  }
3521 
3522  if (I.isEquality()) {
3523  Value *A, *B, *C, *D;
3524 
3525  if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
3526  if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
3527  Value *OtherVal = A == Op1 ? B : A;
3528  return new ICmpInst(I.getPredicate(), OtherVal,
3530  }
3531 
3532  if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
3533  // A^c1 == C^c2 --> A == C^(c1^c2)
3534  ConstantInt *C1, *C2;
3535  if (match(B, m_ConstantInt(C1)) &&
3536  match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
3537  Constant *NC = Builder->getInt(C1->getValue() ^ C2->getValue());
3538  Value *Xor = Builder->CreateXor(C, NC);
3539  return new ICmpInst(I.getPredicate(), A, Xor);
3540  }
3541 
3542  // A^B == A^D -> B == D
3543  if (A == C) return new ICmpInst(I.getPredicate(), B, D);
3544  if (A == D) return new ICmpInst(I.getPredicate(), B, C);
3545  if (B == C) return new ICmpInst(I.getPredicate(), A, D);
3546  if (B == D) return new ICmpInst(I.getPredicate(), A, C);
3547  }
3548  }
3549 
3550  if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
3551  (A == Op0 || B == Op0)) {
3552  // A == (A^B) -> B == 0
3553  Value *OtherVal = A == Op0 ? B : A;
3554  return new ICmpInst(I.getPredicate(), OtherVal,
3556  }
3557 
3558  // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
3559  if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) &&
3560  match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) {
3561  Value *X = nullptr, *Y = nullptr, *Z = nullptr;
3562 
3563  if (A == C) {
3564  X = B; Y = D; Z = A;
3565  } else if (A == D) {
3566  X = B; Y = C; Z = A;
3567  } else if (B == C) {
3568  X = A; Y = D; Z = B;
3569  } else if (B == D) {
3570  X = A; Y = C; Z = B;
3571  }
3572 
3573  if (X) { // Build (X^Y) & Z
3574  Op1 = Builder->CreateXor(X, Y);
3575  Op1 = Builder->CreateAnd(Op1, Z);
3576  I.setOperand(0, Op1);
3577  I.setOperand(1, Constant::getNullValue(Op1->getType()));
3578  return &I;
3579  }
3580  }
3581 
3582  // Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B)
3583  // and (B & (1<<X)-1) == (zext A) --> A == (trunc B)
3584  ConstantInt *Cst1;
3585  if ((Op0->hasOneUse() &&
3586  match(Op0, m_ZExt(m_Value(A))) &&
3587  match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) ||
3588  (Op1->hasOneUse() &&
3589  match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) &&
3590  match(Op1, m_ZExt(m_Value(A))))) {
3591  APInt Pow2 = Cst1->getValue() + 1;
3592  if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) &&
3593  Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth())
3594  return new ICmpInst(I.getPredicate(), A,
3595  Builder->CreateTrunc(B, A->getType()));
3596  }
3597 
3598  // (A >> C) == (B >> C) --> (A^B) u< (1 << C)
3599  // For lshr and ashr pairs.
3600  if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_ConstantInt(Cst1)))) &&
3601  match(Op1, m_OneUse(m_LShr(m_Value(B), m_Specific(Cst1))))) ||
3602  (match(Op0, m_OneUse(m_AShr(m_Value(A), m_ConstantInt(Cst1)))) &&
3603  match(Op1, m_OneUse(m_AShr(m_Value(B), m_Specific(Cst1)))))) {
3604  unsigned TypeBits = Cst1->getBitWidth();
3605  unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
3606  if (ShAmt < TypeBits && ShAmt != 0) {
3610  Value *Xor = Builder->CreateXor(A, B, I.getName() + ".unshifted");
3611  APInt CmpVal = APInt::getOneBitSet(TypeBits, ShAmt);
3612  return new ICmpInst(Pred, Xor, Builder->getInt(CmpVal));
3613  }
3614  }
3615 
3616  // (A << C) == (B << C) --> ((A^B) & (~0U >> C)) == 0
3617  if (match(Op0, m_OneUse(m_Shl(m_Value(A), m_ConstantInt(Cst1)))) &&
3618  match(Op1, m_OneUse(m_Shl(m_Value(B), m_Specific(Cst1))))) {
3619  unsigned TypeBits = Cst1->getBitWidth();
3620  unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
3621  if (ShAmt < TypeBits && ShAmt != 0) {
3622  Value *Xor = Builder->CreateXor(A, B, I.getName() + ".unshifted");
3623  APInt AndVal = APInt::getLowBitsSet(TypeBits, TypeBits - ShAmt);
3624  Value *And = Builder->CreateAnd(Xor, Builder->getInt(AndVal),
3625  I.getName() + ".mask");
3626  return new ICmpInst(I.getPredicate(), And,
3627  Constant::getNullValue(Cst1->getType()));
3628  }
3629  }
3630 
3631  // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to
3632  // "icmp (and X, mask), cst"
3633  uint64_t ShAmt = 0;
3634  if (Op0->hasOneUse() &&
3636  m_ConstantInt(ShAmt))))) &&
3637  match(Op1, m_ConstantInt(Cst1)) &&
3638  // Only do this when A has multiple uses. This is most important to do
3639  // when it exposes other optimizations.
3640  !A->hasOneUse()) {
3641  unsigned ASize =cast<IntegerType>(A->getType())->getPrimitiveSizeInBits();
3642 
3643  if (ShAmt < ASize) {
3644  APInt MaskV =
3646  MaskV <<= ShAmt;
3647 
3648  APInt CmpV = Cst1->getValue().zext(ASize);
3649  CmpV <<= ShAmt;
3650 
3651  Value *Mask = Builder->CreateAnd(A, Builder->getInt(MaskV));
3652  return new ICmpInst(I.getPredicate(), Mask, Builder->getInt(CmpV));
3653  }
3654  }
3655  }
3656 
3657  // The 'cmpxchg' instruction returns an aggregate containing the old value and
3658  // an i1 which indicates whether or not we successfully did the swap.
3659  //
3660  // Replace comparisons between the old value and the expected value with the
3661  // indicator that 'cmpxchg' returns.
3662  //
3663  // N.B. This transform is only valid when the 'cmpxchg' is not permitted to
3664  // spuriously fail. In those cases, the old value may equal the expected
3665  // value but it is possible for the swap to not occur.
3666  if (I.getPredicate() == ICmpInst::ICMP_EQ)
3667  if (auto *EVI = dyn_cast<ExtractValueInst>(Op0))
3668  if (auto *ACXI = dyn_cast<AtomicCmpXchgInst>(EVI->getAggregateOperand()))
3669  if (EVI->getIndices()[0] == 0 && ACXI->getCompareOperand() == Op1 &&
3670  !ACXI->isWeak())
3671  return ExtractValueInst::Create(ACXI, 1);
3672 
3673  {
3674  Value *X; ConstantInt *Cst;
3675  // icmp X+Cst, X
3676  if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X)
3677  return FoldICmpAddOpCst(I, X, Cst, I.getPredicate());
3678 
3679  // icmp X, X+Cst
3680  if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
3681  return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate());
3682  }
3683  return Changed ? &I : nullptr;
3684 }
3685 
3686 /// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
3688  Instruction *LHSI,
3689  Constant *RHSC) {
3690  if (!isa<ConstantFP>(RHSC)) return nullptr;
3691  const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
3692 
3693  // Get the width of the mantissa. We don't want to hack on conversions that
3694  // might lose information from the integer, e.g. "i64 -> float"
3695  int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
3696  if (MantissaWidth == -1) return nullptr; // Unknown.
3697 
3698  IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
3699 
3700  // Check to see that the input is converted from an integer type that is small
3701  // enough that preserves all bits. TODO: check here for "known" sign bits.
3702  // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
3703  unsigned InputSize = IntTy->getScalarSizeInBits();
3704 
3705  // If this is a uitofp instruction, we need an extra bit to hold the sign.
3706  bool LHSUnsigned = isa<UIToFPInst>(LHSI);
3707  if (LHSUnsigned)
3708  ++InputSize;
3709 
3710  if (I.isEquality()) {
3712  bool IsExact = false;
3713  APSInt RHSCvt(IntTy->getBitWidth(), LHSUnsigned);
3714  RHS.convertToInteger(RHSCvt, APFloat::rmNearestTiesToEven, &IsExact);
3715 
3716  // If the floating point constant isn't an integer value, we know if we will
3717  // ever compare equal / not equal to it.
3718  if (!IsExact) {
3719  // TODO: Can never be -0.0 and other non-representable values
3720  APFloat RHSRoundInt(RHS);
3722  if (RHS.compare(RHSRoundInt) != APFloat::cmpEqual) {
3723  if (P == FCmpInst::FCMP_OEQ || P == FCmpInst::FCMP_UEQ)
3724  return ReplaceInstUsesWith(I, Builder->getFalse());
3725 
3726  assert(P == FCmpInst::FCMP_ONE || P == FCmpInst::FCMP_UNE);
3727  return ReplaceInstUsesWith(I, Builder->getTrue());
3728  }
3729  }
3730 
3731  // TODO: If the constant is exactly representable, is it always OK to do
3732  // equality compares as integer?
3733  }
3734 
3735  // Comparisons with zero are a special case where we know we won't lose
3736  // information.
3737  bool IsCmpZero = RHS.isPosZero();
3738 
3739  // If the conversion would lose info, don't hack on this.
3740  if ((int)InputSize > MantissaWidth && !IsCmpZero)
3741  return nullptr;
3742 
3743  // Otherwise, we can potentially simplify the comparison. We know that it
3744  // will always come through as an integer value and we know the constant is
3745  // not a NAN (it would have been previously simplified).
3746  assert(!RHS.isNaN() && "NaN comparison not already folded!");
3747 
3748  ICmpInst::Predicate Pred;
3749  switch (I.getPredicate()) {
3750  default: llvm_unreachable("Unexpected predicate!");
3751  case FCmpInst::FCMP_UEQ:
3752  case FCmpInst::FCMP_OEQ:
3753  Pred = ICmpInst::ICMP_EQ;
3754  break;
3755  case FCmpInst::FCMP_UGT:
3756  case FCmpInst::FCMP_OGT:
3757  Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
3758  break;
3759  case FCmpInst::FCMP_UGE:
3760  case FCmpInst::FCMP_OGE:
3761  Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
3762  break;
3763  case FCmpInst::FCMP_ULT:
3764  case FCmpInst::FCMP_OLT:
3765  Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
3766  break;
3767  case FCmpInst::FCMP_ULE:
3768  case FCmpInst::FCMP_OLE:
3769  Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
3770  break;
3771  case FCmpInst::FCMP_UNE:
3772  case FCmpInst::FCMP_ONE:
3773  Pred = ICmpInst::ICMP_NE;
3774  break;
3775  case FCmpInst::FCMP_ORD:
3776  return ReplaceInstUsesWith(I, Builder->getTrue());
3777  case FCmpInst::FCMP_UNO:
3778  return ReplaceInstUsesWith(I, Builder->getFalse());
3779  }
3780 
3781  // Now we know that the APFloat is a normal number, zero or inf.
3782 
3783  // See if the FP constant is too large for the integer. For example,
3784  // comparing an i8 to 300.0.
3785  unsigned IntWidth = IntTy->getScalarSizeInBits();
3786 
3787  if (!LHSUnsigned) {
3788  // If the RHS value is > SignedMax, fold the comparison. This handles +INF
3789  // and large values.
3790  APFloat SMax(RHS.getSemantics());
3791  SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
3793  if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
3794  if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
3795  Pred == ICmpInst::ICMP_SLE)
3796  return ReplaceInstUsesWith(I, Builder->getTrue());
3797  return ReplaceInstUsesWith(I, Builder->getFalse());
3798  }
3799  } else {
3800  // If the RHS value is > UnsignedMax, fold the comparison. This handles
3801  // +INF and large values.
3802  APFloat UMax(RHS.getSemantics());
3803  UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
3805  if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
3806  if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
3807  Pred == ICmpInst::ICMP_ULE)
3808  return ReplaceInstUsesWith(I, Builder->getTrue());
3809  return ReplaceInstUsesWith(I, Builder->getFalse());
3810  }
3811  }
3812 
3813  if (!LHSUnsigned) {
3814  // See if the RHS value is < SignedMin.
3815  APFloat SMin(RHS.getSemantics());
3816  SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
3818  if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
3819  if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
3820  Pred == ICmpInst::ICMP_SGE)
3821  return ReplaceInstUsesWith(I, Builder->getTrue());
3822  return ReplaceInstUsesWith(I, Builder->getFalse());
3823  }
3824  } else {
3825  // See if the RHS value is < UnsignedMin.
3826  APFloat SMin(RHS.getSemantics());
3827  SMin.convertFromAPInt(APInt::getMinValue(IntWidth), true,
3829  if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // umin > 12312.0
3830  if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_UGT ||
3831  Pred == ICmpInst::ICMP_UGE)
3832  return ReplaceInstUsesWith(I, Builder->getTrue());
3833  return ReplaceInstUsesWith(I, Builder->getFalse());
3834  }
3835  }
3836 
3837  // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
3838  // [0, UMAX], but it may still be fractional. See if it is fractional by
3839  // casting the FP value to the integer value and back, checking for equality.
3840  // Don't do this for zero, because -0.0 is not fractional.
3841  Constant *RHSInt = LHSUnsigned
3842  ? ConstantExpr::getFPToUI(RHSC, IntTy)
3843  : ConstantExpr::getFPToSI(RHSC, IntTy);
3844  if (!RHS.isZero()) {
3845  bool Equal = LHSUnsigned
3846  ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
3847  : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
3848  if (!Equal) {
3849  // If we had a comparison against a fractional value, we have to adjust
3850  // the compare predicate and sometimes the value. RHSC is rounded towards
3851  // zero at this point.
3852  switch (Pred) {
3853  default: llvm_unreachable("Unexpected integer comparison!");
3854  case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
3855  return ReplaceInstUsesWith(I, Builder->getTrue());
3856  case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
3857  return ReplaceInstUsesWith(I, Builder->getFalse());
3858  case ICmpInst::ICMP_ULE:
3859  // (float)int <= 4.4 --> int <= 4
3860  // (float)int <= -4.4 --> false
3861  if (RHS.isNegative())
3862  return ReplaceInstUsesWith(I, Builder->getFalse());
3863  break;
3864  case ICmpInst::ICMP_SLE:
3865  // (float)int <= 4.4 --> int <= 4
3866  // (float)int <= -4.4 --> int < -4
3867  if (RHS.isNegative())
3868  Pred = ICmpInst::ICMP_SLT;
3869  break;
3870  case ICmpInst::ICMP_ULT:
3871  // (float)int < -4.4 --> false
3872  // (float)int < 4.4 --> int <= 4
3873  if (RHS.isNegative())
3874  return ReplaceInstUsesWith(I, Builder->getFalse());
3875  Pred = ICmpInst::ICMP_ULE;
3876  break;
3877  case ICmpInst::ICMP_SLT:
3878  // (float)int < -4.4 --> int < -4
3879  // (float)int < 4.4 --> int <= 4
3880  if (!RHS.isNegative())
3881  Pred = ICmpInst::ICMP_SLE;
3882  break;
3883  case ICmpInst::ICMP_UGT:
3884  // (float)int > 4.4 --> int > 4
3885  // (float)int > -4.4 --> true
3886  if (RHS.isNegative())
3887  return ReplaceInstUsesWith(I, Builder->getTrue());
3888  break;
3889  case ICmpInst::ICMP_SGT:
3890  // (float)int > 4.4 --> int > 4
3891  // (float)int > -4.4 --> int >= -4
3892  if (RHS.isNegative())
3893  Pred = ICmpInst::ICMP_SGE;
3894  break;
3895  case ICmpInst::ICMP_UGE:
3896  // (float)int >= -4.4 --> true
3897  // (float)int >= 4.4 --> int > 4
3898  if (RHS.isNegative())
3899  return ReplaceInstUsesWith(I, Builder->getTrue());
3900  Pred = ICmpInst::ICMP_UGT;
3901  break;
3902  case ICmpInst::ICMP_SGE:
3903  // (float)int >= -4.4 --> int >= -4
3904  // (float)int >= 4.4 --> int > 4
3905  if (!RHS.isNegative())
3906  Pred = ICmpInst::ICMP_SGT;
3907  break;
3908  }
3909  }
3910  }
3911 
3912  // Lower this FP comparison into an appropriate integer version of the
3913  // comparison.
3914  return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
3915 }
3916 
3918  bool Changed = false;
3919 
3920  /// Orders the operands of the compare so that they are listed from most
3921  /// complex to least complex. This puts constants before unary operators,
3922  /// before binary operators.
3923  if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
3924  I.swapOperands();
3925  Changed = true;
3926  }
3927 
3928  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3929 
3930  if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1,
3931  I.getFastMathFlags(), DL, TLI, DT, AC, &I))
3932  return ReplaceInstUsesWith(I, V);
3933 
3934  // Simplify 'fcmp pred X, X'
3935  if (Op0 == Op1) {
3936  switch (I.getPredicate()) {
3937  default: llvm_unreachable("Unknown predicate!");
3938  case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
3939  case FCmpInst::FCMP_ULT: // True if unordered or less than
3940  case FCmpInst::FCMP_UGT: // True if unordered or greater than
3941  case FCmpInst::FCMP_UNE: // True if unordered or not equal
3942  // Canonicalize these to be 'fcmp uno %X, 0.0'.
3945  return &I;
3946 
3947  case FCmpInst::FCMP_ORD: // True if ordered (no nans)
3948  case FCmpInst::FCMP_OEQ: // True if ordered and equal
3949  case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
3950  case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
3951  // Canonicalize these to be 'fcmp ord %X, 0.0'.
3954  return &I;
3955  }
3956  }
3957 
3958  // Test if the FCmpInst instruction is used exclusively by a select as
3959  // part of a minimum or maximum operation. If so, refrain from doing
3960  // any other folding. This helps out other analyses which understand
3961  // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
3962  // and CodeGen. And in this case, at least one of the comparison
3963  // operands has at least one user besides the compare (the select),
3964  // which would often largely negate the benefit of folding anyway.
3965  if (I.hasOneUse())
3966  if (SelectInst *SI = dyn_cast<SelectInst>(*I.user_begin()))
3967  if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
3968  (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
3969  return nullptr;
3970 
3971  // Handle fcmp with constant RHS
3972  if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3973  if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3974  switch (LHSI->getOpcode()) {
3975  case Instruction::FPExt: {
3976  // fcmp (fpext x), C -> fcmp x, (fptrunc C) if fptrunc is lossless
3977  FPExtInst *LHSExt = cast<FPExtInst>(LHSI);
3978  ConstantFP *RHSF = dyn_cast<ConstantFP>(RHSC);
3979  if (!RHSF)
3980  break;
3981 
3982  const fltSemantics *Sem;
3983  // FIXME: This shouldn't be here.
3984  if (LHSExt->getSrcTy()->isHalfTy())
3985  Sem = &APFloat::IEEEhalf;
3986  else if (LHSExt->getSrcTy()->isFloatTy())
3987  Sem = &APFloat::IEEEsingle;
3988  else if (LHSExt->getSrcTy()->isDoubleTy())
3989  Sem = &APFloat::IEEEdouble;
3990  else if (LHSExt->getSrcTy()->isFP128Ty())
3991  Sem = &APFloat::IEEEquad;
3992  else if (LHSExt->getSrcTy()->isX86_FP80Ty())
3994  else if (LHSExt->getSrcTy()->isPPC_FP128Ty())
3995  Sem = &APFloat::PPCDoubleDouble;
3996  else
3997  break;
3998 
3999  bool Lossy;
4000  APFloat F = RHSF->getValueAPF();
4001  F.convert(*Sem, APFloat::rmNearestTiesToEven, &Lossy);
4002 
4003  // Avoid lossy conversions and denormals. Zero is a special case
4004  // that's OK to convert.
4005  APFloat Fabs = F;
4006  Fabs.clearSign();
4007  if (!Lossy &&
4008  ((Fabs.compare(APFloat::getSmallestNormalized(*Sem)) !=
4009  APFloat::cmpLessThan) || Fabs.isZero()))
4010 
4011  return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0),
4012  ConstantFP::get(RHSC->getContext(), F));
4013  break;
4014  }
4015  case Instruction::PHI:
4016  // Only fold fcmp into the PHI if the phi and fcmp are in the same
4017  // block. If in the same block, we're encouraging jump threading. If
4018  // not, we are just pessimizing the code by making an i1 phi.
4019  if (LHSI->getParent() == I.getParent())
4020  if (Instruction *NV = FoldOpIntoPhi(I))
4021  return NV;
4022  break;
4023  case Instruction::SIToFP:
4024  case Instruction::UIToFP:
4025  if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
4026  return NV;
4027  break;
4028  case Instruction::FSub: {
4029  // fcmp pred (fneg x), C -> fcmp swap(pred) x, -C
4030  Value *Op;
4031  if (match(LHSI, m_FNeg(m_Value(Op))))
4032  return new FCmpInst(I.getSwappedPredicate(), Op,
4033  ConstantExpr::getFNeg(RHSC));
4034  break;
4035  }
4036  case Instruction::Load:
4037  if (GetElementPtrInst *GEP =
4038  dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
4039  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
4040  if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
4041  !cast<LoadInst>(LHSI)->isVolatile())
4042  if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
4043  return Res;
4044  }
4045  break;
4046  case Instruction::Call: {
4047  if (!RHSC->isNullValue())
4048  break;
4049 
4050  CallInst *CI = cast<CallInst>(LHSI);
4051  const Function *F = CI->getCalledFunction();
4052  if (!F)
4053  break;
4054 
4055  // Various optimization for fabs compared with zero.
4057  if (F->getIntrinsicID() == Intrinsic::fabs ||
4058  (TLI->getLibFunc(F->getName(), Func) && TLI->has(Func) &&
4059  (Func == LibFunc::fabs || Func == LibFunc::fabsf ||
4060  Func == LibFunc::fabsl))) {
4061  switch (I.getPredicate()) {
4062  default:
4063  break;
4064  // fabs(x) < 0 --> false
4065  case FCmpInst::FCMP_OLT:
4066  return ReplaceInstUsesWith(I, Builder->getFalse());
4067  // fabs(x) > 0 --> x != 0
4068  case FCmpInst::FCMP_OGT:
4069  return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0), RHSC);
4070  // fabs(x) <= 0 --> x == 0
4071  case FCmpInst::FCMP_OLE:
4072  return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0), RHSC);
4073  // fabs(x) >= 0 --> !isnan(x)
4074  case FCmpInst::FCMP_OGE:
4075  return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0), RHSC);
4076  // fabs(x) == 0 --> x == 0
4077  // fabs(x) != 0 --> x != 0
4078  case FCmpInst::FCMP_OEQ:
4079  case FCmpInst::FCMP_UEQ:
4080  case FCmpInst::FCMP_ONE:
4081  case FCmpInst::FCMP_UNE:
4082  return new FCmpInst(I.getPredicate(), CI->getArgOperand(0), RHSC);
4083  }
4084  }
4085  }
4086  }
4087  }
4088 
4089  // fcmp pred (fneg x), (fneg y) -> fcmp swap(pred) x, y
4090  Value *X, *Y;
4091  if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_FNeg(m_Value(Y))))
4092  return new FCmpInst(I.getSwappedPredicate(), X, Y);
4093 
4094  // fcmp (fpext x), (fpext y) -> fcmp x, y
4095  if (FPExtInst *LHSExt = dyn_cast<FPExtInst>(Op0))
4096  if (FPExtInst *RHSExt = dyn_cast<FPExtInst>(Op1))
4097  if (LHSExt->getSrcTy() == RHSExt->getSrcTy())
4098  return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0),
4099  RHSExt->getOperand(0));
4100 
4101  return Changed ? &I : nullptr;
4102 }
static unsigned getBitWidth(Type *Ty, const DataLayout &DL)
Returns the bitwidth of the given scalar or pointer type (if unknown returns 0).
bool isArithmeticShift() const
isArithmeticShift - Return true if this is an arithmetic shift right.
Definition: Instruction.h:142
Value * EmitGEPOffset(IRBuilderTy *Builder, const DataLayout &DL, User *GEP, bool NoAssumptions=false)
EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the code necessary to compute th...
Definition: Local.h:193
const Use & getOperandUse(unsigned i) const
Definition: User.h:129
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
Definition: PatternMatch.h:506
static bool isHighOnes(const ConstantInt *CI)
APInt LLVM_ATTRIBUTE_UNUSED_RESULT ashr(unsigned shiftAmt) const
Arithmetic right-shift function.
Definition: APInt.cpp:1051
void push_back(const T &Elt)
Definition: SmallVector.h:222
OverflowingBinaryOp_match< LHS, RHS, Instruction::Sub, OverflowingBinaryOperator::NoSignedWrap > m_NSWSub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:577
static bool isEquality(Predicate Pred)
Determine if this is an equality predicate.
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:104
static ConstantInt * getFalse(LLVMContext &Context)
Definition: Constants.cpp:537
IntegerType * getType() const
getType - Specialize the getType() method to always return an IntegerType, which reduces the amount o...
Definition: Constants.h:140
Instruction::CastOps getOpcode() const
Return the opcode of this CastInst.
Definition: InstrTypes.h:649
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:64
This class is the base class for the comparison instructions.
Definition: InstrTypes.h:679
static APInt getSignBit(unsigned BitWidth)
Get the SignBit for a specific bit width.
Definition: APInt.h:446
APInt LLVM_ATTRIBUTE_UNUSED_RESULT byteSwap() const
Definition: APInt.cpp:790
BasicBlock * getUniquePredecessor()
Return the predecessor of this block if it has a unique predecessor block.
Definition: BasicBlock.cpp:224
APInt LLVM_ATTRIBUTE_UNUSED_RESULT abs() const
Get the absolute value;.
Definition: APInt.h:1571
Value * SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr, Instruction *CxtI=nullptr)
SimplifyICmpInst - Given operands for an ICmpInst, see if we can fold the result. ...
static APInt getAllOnesValue(unsigned numBits)
Get the all-ones value.
Definition: APInt.h:453
BinaryOp_match< LHS, RHS, Instruction::Sub > m_Sub(const LHS &L, const RHS &R)
Definition: PatternMatch.h:446
static BinaryOperator * CreateNot(Value *Op, const Twine &Name="", Instruction *InsertBefore=nullptr)
Instruction * FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, ICmpInst::Predicate Cond, Instruction &I)
FoldGEPICmp - Fold comparisons between a GEP instruction and something else.
static bool HasSubOverflow(ConstantInt *Result, ConstantInt *In1, ConstantInt *In2, bool IsSigned)
bool isNaN() const
Returns true if and only if the float is a quiet or signaling NaN.
Definition: APFloat.h:424
STATISTIC(NumFunctions,"Total number of functions")
Value * CreateIntCast(Value *V, Type *DestTy, bool isSigned, const Twine &Name="")
Definition: IRBuilder.h:1316
static const fltSemantics IEEEdouble
Definition: APFloat.h:133
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:114
static void ComputeSignedMinMaxValuesFromKnownBits(const APInt &KnownZero, const APInt &KnownOne, APInt &Min, APInt &Max)
ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a set of known zero and one ...
match_zero m_Zero()
Match an arbitrary zero/null constant.
Definition: PatternMatch.h:137
void setBit(unsigned bitPosition)
Set a given bit to 1.
Definition: APInt.cpp:588
unsigned getBitWidth() const
getBitWidth - Return the bitwidth of this constant.
Definition: Constants.h:111
This class represents zero extension of integer types.
unsigned getNumOperands() const
Definition: User.h:138
BinaryOp_match< LHS, RHS, Instruction::Mul > m_Mul(const LHS &L, const RHS &R)
Definition: PatternMatch.h:458
bool isNonNegative() const
Determine if this APInt Value is non-negative (>= 0)
Definition: APInt.h:324
static bool SubWithOverflow(Constant *&Result, Constant *In1, Constant *In2, bool IsSigned=false)
SubWithOverflow - Compute Result = In1-In2, returning true if the result overflowed for this type...
CallInst - This class represents a function call, abstracting a target machine's calling convention...
static APInt getLowBitsSet(unsigned numBits, unsigned loBitsSet)
Get a value with low bits set.
Definition: APInt.h:531
Predicate getInversePredicate() const
For example, EQ -> NE, UGT -> ULE, SLT -> SGE, OEQ -> UNE, UGT -> OLE, OLT -> UGE, etc.
Definition: InstrTypes.h:783
void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr)
Determine which bits of V are known to be either zero or one and return them in the KnownZero/KnownOn...
unsigned less or equal
Definition: InstrTypes.h:723
unsigned less than
Definition: InstrTypes.h:722
BinaryOp_match< LHS, RHS, Instruction::AShr > m_AShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:536
static Constant * getIntToPtr(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1822
bool isSigned() const
Determine if this instruction is using a signed comparison.
Definition: InstrTypes.h:826
static Constant * getExtractElement(Constant *Vec, Constant *Idx, Type *OnlyIfReducedTy=nullptr)
Definition: Constants.cpp:2123
0 1 0 0 True if ordered and less than
Definition: InstrTypes.h:703
bool isDoubleTy() const
isDoubleTy - Return true if this is 'double', a 64-bit IEEE fp type.
Definition: Type.h:146
void clearSign()
Definition: APFloat.cpp:1630
static Constant * getNUWShl(Constant *C1, Constant *C2)
Definition: Constants.h:960
1 1 1 0 True if unordered or not equal
Definition: InstrTypes.h:713
void Add(Instruction *I)
Add - Add the specified instruction to the worklist if it isn't already in it.
int getFPMantissaWidth() const
getFPMantissaWidth - Return the width of the mantissa of this type.
Definition: Type.cpp:146
Value * SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, FastMathFlags FMF, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr)
SimplifyFCmpInst - Given operands for an FCmpInst, see if we can fold the result. ...
static bool isEquality(Predicate P)
isEquality - Return true if this predicate is either EQ or NE.
FastMathFlags getFastMathFlags() const
Convenience function for getting all the fast-math flags, which must be an operator which supports th...
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:111
F(f)
Instruction * FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI, Constant *RHSC)
FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
LoadInst - an instruction for reading from memory.
Definition: Instructions.h:177
unsigned getBitWidth() const
Get the number of bits in this IntegerType.
Definition: DerivedTypes.h:61
FunctionType * getType(LLVMContext &Context, ID id, ArrayRef< Type * > Tys=None)
Return the function type for an intrinsic.
Definition: Function.cpp:822
Hexagon Common GEP
static Constant * getSub(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2269
bool replacedSelectWithOperand(SelectInst *SI, const ICmpInst *Icmp, const unsigned SIOpd)
True when a select result is replaced by one of its operands in select-icmp sequence.
unsigned getPointerAddressSpace() const
Get the address space of this pointer or pointer vector type.
Definition: Type.cpp:216
fneg_match< LHS > m_FNeg(const LHS &L)
Match a floating point negate.
Definition: PatternMatch.h:900
const Constant * getInitializer() const
getInitializer - Return the initializer for this global variable.
static APInt getSignedMaxValue(unsigned numBits)
Gets maximum signed value of APInt for a specific bit width.
Definition: APInt.h:426
static Constant * getNullValue(Type *Ty)
Definition: Constants.cpp:178
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:188
static Constant * getAdd(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2258
bool hasAllConstantIndices() const
Return true if all of the indices of this GEP are constant integers.
Definition: Operator.h:434
APInt Not(const APInt &APIVal)
Bitwise complement function.
Definition: APInt.h:1905
bool isNegative() const
Determine sign of this APInt.
Definition: APInt.h:319
bool uge(uint64_t Num) const
This function will return true iff this constant represents a value with active bits bigger than 64 b...
Definition: Constants.h:210
1 0 0 1 True if unordered or equal
Definition: InstrTypes.h:708
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:41
static const fltSemantics x87DoubleExtended
Definition: APFloat.h:136
Value * CreateExtractValue(Value *Agg, ArrayRef< unsigned > Idxs, const Twine &Name="")
Definition: IRBuilder.h:1541
1 0 0 0 True if unordered: isnan(X) | isnan(Y)
Definition: InstrTypes.h:707
static Value * EvaluateGEPOffsetExpression(User *GEP, InstCombiner &IC, const DataLayout &DL)
EvaluateGEPOffsetExpression - Return a value that can be used to compare the offset implied by a GEP ...
static unsigned getComplexity(Value *V)
Assign a complexity or rank value to LLVM Values.
BinaryOp_match< LHS, RHS, Instruction::Xor > m_Xor(const LHS &L, const RHS &R)
Definition: PatternMatch.h:518
SelectInst - This class represents the LLVM 'select' instruction.
OverflowCheckFlavor
Specific patterns of overflow check idioms that we match.
const StructLayout * getStructLayout(StructType *Ty) const
Returns a StructLayout object, indicating the alignment of the struct, its size, and the offsets of i...
Definition: DataLayout.cpp:551
This is the base class for all instructions that perform data casts.
Definition: InstrTypes.h:389
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:106
StructType - Class to represent struct types.
Definition: DerivedTypes.h:191
opStatus convertToInteger(integerPart *, unsigned int, bool, roundingMode, bool *) const
Definition: APFloat.cpp:2191
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
Type * getArrayElementType() const
Definition: Type.h:361
static Constant * getLShr(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2336
APInt LLVM_ATTRIBUTE_UNUSED_RESULT lshr(unsigned shiftAmt) const
Logical right-shift function.
Definition: APInt.cpp:1142
CastClass_match< OpTy, Instruction::Trunc > m_Trunc(const OpTy &Op)
Matches Trunc.
Definition: PatternMatch.h:801
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:517
unsigned logBase2(const APInt &APIVal)
Returns the floor log base 2 of the specified APInt value.
Definition: APInt.h:1782
The core instruction combiner logic.
static Constant * AddOne(Constant *C)
Add one to a Constant.
0 1 0 1 True if ordered and less than or equal
Definition: InstrTypes.h:704
static const fltSemantics IEEEquad
Definition: APFloat.h:134
static ConstantInt * ExtractElement(Constant *V, Constant *Idx)
not_match< LHS > m_Not(const LHS &L)
Definition: PatternMatch.h:854
bool isNegative() const
Definition: Constants.h:156
BinaryOp_match< LHS, RHS, Instruction::Add > m_Add(const LHS &L, const RHS &R)
Definition: PatternMatch.h:434
uint64_t getZExtValue() const
Return the constant as a 64-bit unsigned integer value after it has been zero extended as appropriate...
Definition: Constants.h:117
static Constant * get(unsigned Opcode, Constant *C1, Constant *C2, unsigned Flags=0, Type *OnlyIfReducedTy=nullptr)
get - Return a binary or shift operator constant expression, folding if possible. ...
Definition: Constants.cpp:1868
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1727
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:878
static SelectInst * Create(Value *C, Value *S1, Value *S2, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const
Definition: SmallVector.h:57
CastClass_match< OpTy, Instruction::ZExt > m_ZExt(const OpTy &Op)
Matches ZExt.
Definition: PatternMatch.h:813
bool isHalfTy() const
isHalfTy - Return true if this is 'half', a 16-bit IEEE fp type.
Definition: Type.h:140
static Constant * getAShr(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2341
ArrayType - Class to represent array types.
Definition: DerivedTypes.h:336
bool isKnownToBeAPowerOfTwo(Value *V, const DataLayout &DL, bool OrZero=false, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr)
isKnownToBeAPowerOfTwo - Return true if the given value is known to have exactly one bit set when def...
This instruction compares its operands according to the predicate given to the constructor.
uint64_t getLimitedValue(uint64_t Limit=~0ULL) const
getLimitedValue - If the value is smaller than the specified limit, return it, otherwise return the l...
Definition: Constants.h:219
bool sgt(const APInt &RHS) const
Signed greather than comparison.
Definition: APInt.h:1119
This class represents a no-op cast from one type to another.
static APInt DemandedBitsLHSMask(ICmpInst &I, unsigned BitWidth, bool isSignCheck)
unsigned getActiveBits() const
Compute the number of active bits in the value.
Definition: APInt.h:1297
class_match< ConstantInt > m_ConstantInt()
Match an arbitrary ConstantInt and ignore it.
Definition: PatternMatch.h:75
Predicate getUnsignedPredicate() const
For example, EQ->EQ, SLE->ULE, UGT->UGT, etc.
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:866
static bool AddWithOverflow(Constant *&Result, Constant *In1, Constant *In2, bool IsSigned=false)
AddWithOverflow - Compute Result = In1+In2, returning true if the result overflowed for this type...
APInt LLVM_ATTRIBUTE_UNUSED_RESULT shl(unsigned shiftAmt) const
Left-shift function.
Definition: APInt.h:868
SelectClass_match< Cond, LHS, RHS > m_Select(const Cond &C, const LHS &L, const RHS &R)
Definition: PatternMatch.h:758
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power of 2.
Definition: PatternMatch.h:272
static Constant * getUDiv(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2291
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:256
static bool isChainSelectCmpBranch(const SelectInst *SI)
true when the instruction sequence within a block is select-cmp-br.
Instruction * visitICmpInstWithCastAndCast(ICmpInst &ICI)
visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
bool isPPC_FP128Ty() const
isPPC_FP128Ty - Return true if this is powerpc long double.
Definition: Type.h:155
This class represents a truncation of integer types.
void SetInsertPoint(BasicBlock *TheBB)
This specifies that created instructions should be appended to the end of the specified block...
Definition: IRBuilder.h:85
bool isInBounds() const
isInBounds - Determine whether the GEP has the inbounds flag.
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.cpp:520
opStatus convertFromAPInt(const APInt &, bool, roundingMode)
Definition: APFloat.cpp:2272
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:491
static APInt getHighBitsSet(unsigned numBits, unsigned hiBitsSet)
Get a value with high bits set.
Definition: APInt.h:513
static Constant * getBitCast(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1835
GetElementPtrInst - an instruction for type-safe pointer arithmetic to access elements of arrays and ...
Definition: Instructions.h:830
A self-contained host- and target-independent arbitrary-precision floating-point software implementat...
Definition: APFloat.h:122
OverflowResult computeOverflowForUnsignedAdd(Value *LHS, Value *RHS, const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT)
static Instruction * ProcessUMulZExtIdiom(ICmpInst &I, Value *MulVal, Value *OtherVal, InstCombiner &IC)
Recognize and process idiom involving test for multiplication overflow.
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:55
bool isIntOrIntVectorTy() const
isIntOrIntVectorTy - Return true if this is an integer type or a vector of integer types...
Definition: Type.h:201
#define P(N)
static Instruction * ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B, ConstantInt *CI2, ConstantInt *CI1, InstCombiner &IC)
ProcessUGT_ADDCST_ADD - The caller has matched a pattern of the form: I = icmp ugt (add (add A...
static bool isSignTest(ICmpInst::Predicate &pred, const ConstantInt *RHS)
Returns true if the exploded icmp can be expressed as a signed comparison to zero and updates the pre...
static Constant * getFNeg(Constant *C)
Definition: Constants.cpp:2246
BinaryOp_match< LHS, RHS, Instruction::LShr > m_LShr(const LHS &L, const RHS &R)
Definition: PatternMatch.h:530
static APFloat getSmallestNormalized(const fltSemantics &Sem, bool Negative=false)
Returns the smallest (by magnitude) normalized finite number in the given semantics.
Definition: APFloat.cpp:3437
bool eq(const APInt &RHS) const
Equality comparison.
Definition: APInt.h:1001
static CmpInst * Create(OtherOps Op, unsigned short predicate, Value *S1, Value *S2, const Twine &Name="", Instruction *InsertBefore=nullptr)
Construct a compare instruction, given the opcode, the predicate and the two operands.
static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero, const APInt &KnownOne, APInt &Min, APInt &Max)
APInt LLVM_ATTRIBUTE_UNUSED_RESULT trunc(unsigned width) const
Truncate to new width.
Definition: APInt.cpp:932
cmpResult compare(const APFloat &) const
IEEE comparison with another floating point number (NaNs compare unordered, 0==-0).
Definition: APFloat.cpp:1893
LLVM Basic Block Representation.
Definition: BasicBlock.h:65
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
BinaryOp_match< LHS, RHS, Instruction::Or > m_Or(const LHS &L, const RHS &R)
Definition: PatternMatch.h:512
BasicBlock * getSuccessor(unsigned idx) const
Return the specified successor.
Definition: InstrTypes.h:62
static volatile int One
Definition: InfiniteTest.cpp:9
static ExtractValueInst * Create(Value *Agg, ArrayRef< unsigned > Idxs, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
bool isEquality() const
isEquality - Return true if this predicate is either EQ or NE.
Value * CreateAdd(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:704
bool isMaxValue(bool isSigned) const
This function will return true iff this constant represents the largest value that may be represented...
Definition: Constants.h:186
This is an important base class in LLVM.
Definition: Constant.h:41
Instruction * ReplaceInstUsesWith(Instruction &I, Value *V)
A combiner-aware RAUW-like routine.
bool isFloatTy() const
isFloatTy - Return true if this is 'float', a 32-bit IEEE fp type.
Definition: Type.h:143
static Constant * getAnd(Constant *C1, Constant *C2)
Definition: Constants.cpp:2317
APInt Or(const APInt &LHS, const APInt &RHS)
Bitwise OR function for APInt.
Definition: APInt.h:1895
Instruction * FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI, ConstantInt *DivRHS)
FoldICmpShrCst - Handle "icmp(([al]shr X, cst1), cst2)".
ConstantFP - Floating Point Values [float, double].
Definition: Constants.h:233
APInt Xor(const APInt &LHS, const APInt &RHS)
Bitwise XOR function for APInt.
Definition: APInt.h:1900
cst_pred_ty< is_all_ones > m_AllOnes()
Match an integer or vector with all bits set to true.
Definition: PatternMatch.h:252
static APInt getOneBitSet(unsigned numBits, unsigned BitNo)
Return an APInt with exactly one bit set in the result.
Definition: APInt.h:479
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:322
bool sle(const APInt &RHS) const
Signed less or equal comparison.
Definition: APInt.h:1085
BinaryOp_match< LHS, RHS, Instruction::Shl > m_Shl(const LHS &L, const RHS &R)
Definition: PatternMatch.h:524
OverflowResult computeOverflowForUnsignedMul(Value *LHS, Value *RHS, const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT)
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang","erlang-compatible garbage collector")
This instruction compares its operands according to the predicate given to the constructor.
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:697
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1273
opStatus convert(const fltSemantics &, roundingMode, bool *)
APFloat::convert - convert a value of one floating point type to another.
Definition: APFloat.cpp:1972
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1137
Instruction * visitICmpInst(ICmpInst &I)
Value * getOperand(unsigned i) const
Definition: User.h:118
0 1 1 1 True if ordered (no nans)
Definition: InstrTypes.h:706
bool isCommutative() const
isCommutative - Return true if the instruction is commutative:
Definition: Instruction.h:327
static Constant * getICmp(unsigned short pred, Constant *LHS, Constant *RHS, bool OnlyIfReduced=false)
get* - Return some common constants without having to specify the full Instruction::OPCODE identifier...
Definition: Constants.cpp:2074
Class to represent integer types.
Definition: DerivedTypes.h:37
Type * getSrcTy() const
Return the source type, as a convenience.
Definition: InstrTypes.h:654
Predicate getPredicate() const
Return the predicate for this instruction.
Definition: InstrTypes.h:760
static Constant * getNot(Constant *C)
Definition: Constants.cpp:2252
Constant * getAggregateElement(unsigned Elt) const
getAggregateElement - For aggregates (struct/array/vector) return the constant that corresponds to th...
Definition: Constants.cpp:250
static Constant * getAllOnesValue(Type *Ty)
Get the all ones value.
Definition: Constants.cpp:230
Instruction * FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A, ConstantInt *CI1, ConstantInt *CI2)
FoldICmpCstShrCst - Handle "(icmp eq/ne (ashr/lshr const2, A), const1)" -> (icmp eq/ne A...
bool isFP128Ty() const
isFP128Ty - Return true if this is 'fp128'.
Definition: Type.h:152
bool isPointerTy() const
isPointerTy - True if this is an instance of PointerType.
Definition: Type.h:217
static UndefValue * get(Type *T)
get() - Static factory methods - Return an 'undef' object of the specified type.
Definition: Constants.cpp:1473
void swapOperands()
Exchange the two operands to this instruction in such a way that it does not modify the semantics of ...
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:519
CallInst * CreateCall(Value *Callee, ArrayRef< Value * > Args=None, const Twine &Name="")
Definition: IRBuilder.h:1467
bool hasNoSignedWrap() const
Determine whether the no signed wrap flag is set.
Constant * ConstantFoldCompareInstOperands(unsigned Predicate, Constant *LHS, Constant *RHS, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldCompareInstOperands - Attempt to constant fold a compare instruction (icmp/fcmp) with the...
bool isPowerOf2() const
Check if this APInt's value is a power of two greater than zero.
Definition: APInt.h:386
1 1 0 1 True if unordered, less than, or equal
Definition: InstrTypes.h:712
static const fltSemantics IEEEhalf
Definition: APFloat.h:131
signed greater than
Definition: InstrTypes.h:724
bool isRelational() const
isRelational - Return true if the predicate is relational (not EQ or NE).
hexagon gen pred
InstCombineWorklist & Worklist
A worklist of the instructions that need to be simplified.
neg_match< LHS > m_Neg(const LHS &L)
Match an integer negate.
Definition: PatternMatch.h:877
bool ugt(const APInt &RHS) const
Unsigned greather than comparison.
Definition: APInt.h:1101
unsigned countTrailingZeros() const
Count the number of trailing zero bits.
Definition: APInt.cpp:749
IntegerType * getIntPtrType(LLVMContext &C, unsigned AddressSpace=0) const
Returns an integer type with size at least as big as that of a pointer in the given address space...
Definition: DataLayout.cpp:694
0 0 1 0 True if ordered and greater than
Definition: InstrTypes.h:701
static Constant * getSIToFP(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1776
BinaryOps getOpcode() const
Definition: InstrTypes.h:323
bool isPosZero() const
Definition: APFloat.h:438
static IntegerType * get(LLVMContext &C, unsigned NumBits)
This static method is the primary way of constructing an IntegerType.
Definition: Type.cpp:304
static const fltSemantics PPCDoubleDouble
Definition: APFloat.h:135
unsigned getIntegerBitWidth() const
Definition: Type.cpp:176
This is the shared class of boolean and integer constants.
Definition: Constants.h:47
Value * CreateZExt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1192
bool slt(const APInt &RHS) const
Signed less than comparison.
Definition: APInt.cpp:552
bool isNegative() const
IEEE-754R isSignMinus: Returns true if and only if the current value is negative. ...
Definition: APFloat.h:399
uint64_t getTypeAllocSize(Type *Ty) const
Returns the offset in bytes between successive objects of the specified type, including alignment pad...
Definition: DataLayout.h:388
static Constant * getSDiv(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2296
unsigned getScalarSizeInBits() const LLVM_READONLY
getScalarSizeInBits - If this is a vector type, return the getPrimitiveSizeInBits value for the eleme...
Definition: Type.cpp:139
unsigned logBase2() const
Definition: APInt.h:1521
1 1 0 0 True if unordered or less than
Definition: InstrTypes.h:711
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:222
bool hasAllZeroIndices() const
Return true if all of the indices of this GEP are zeros.
Definition: Operator.h:421
This class represents a range of values.
Definition: ConstantRange.h:43
signed less than
Definition: InstrTypes.h:726
const APInt & getLower() const
Return the lower value for this range.
Definition: ConstantRange.h:87
bool isTrueWhenEqual() const
This is just a convenience.
Definition: InstrTypes.h:838
SequentialType * getType() const
Definition: Instructions.h:922
Value * stripPointerCasts()
Strip off pointer casts, all-zero GEPs, and aliases.
Definition: Value.cpp:458
bool isStrictlyPositive() const
Determine if this APInt Value is positive.
Definition: APInt.h:332
Predicate getSwappedPredicate() const
For example, EQ->EQ, SLE->SGE, ULT->UGT, OEQ->OEQ, ULE->UGE, OLT->OGT, etc.
Definition: InstrTypes.h:799
static APInt getMinValue(unsigned numBits)
Gets minimum unsigned value of APInt for a specific bit width.
Definition: APInt.h:433
static Constant * getTrunc(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1699
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:582
Function * getCalledFunction() const
getCalledFunction - Return the function called, or null if this is an indirect function invocation...
bool isZero() const
This is just a convenience method to make client code smaller for a common code.
Definition: Constants.h:161
static Constant * get(Type *Ty, double V)
get() - This returns a ConstantFP, or a vector containing a splat of a ConstantFP, for the specified value in the specified type.
Definition: Constants.cpp:652
#define NC
Definition: regutils.h:42
bool isNullValue() const
isNullValue - Return true if this is the value that would be returned by getNullValue.
Definition: Constants.cpp:75
bool isExact() const
Determine whether the exact flag is set.
static ConstantInt * getTrue(LLVMContext &Context)
Definition: Constants.cpp:530
void setPredicate(Predicate P)
Set the predicate for this instruction to the specified value.
Definition: InstrTypes.h:765
void setOperand(unsigned i, Value *Val)
Definition: User.h:122
bool isAllOnesValue() const
isAllOnesValue - Return true if this is the value that would be returned by getAllOnesValue.
Definition: Constants.cpp:88
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:576
Value * getArgOperand(unsigned i) const
getArgOperand/setArgOperand - Return/set the i-th call argument.
signed less or equal
Definition: InstrTypes.h:727
VectorType - Class to represent vector types.
Definition: DerivedTypes.h:362
Class for arbitrary precision integers.
Definition: APInt.h:73
bool isIntegerTy() const
isIntegerTy - True if this is an instance of IntegerType.
Definition: Type.h:193
static bool HasAddOverflow(ConstantInt *Result, ConstantInt *In1, ConstantInt *In2, bool IsSigned)
CastClass_match< OpTy, Instruction::PtrToInt > m_PtrToInt(const OpTy &Op)
Matches PtrToInt.
Definition: PatternMatch.h:795
iterator_range< user_iterator > users()
Definition: Value.h:300
static ConstantInt * getOne(Constant *C)
static Constant * getFPToUI(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1787
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1591
LLVM_ATTRIBUTE_UNUSED_RESULT std::enable_if< !is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:285
static APInt getMaxValue(unsigned numBits)
Gets maximum unsigned value of APInt for specific bit width.
Definition: APInt.h:421
bool isMinValue() const
Determine if this is the smallest unsigned value.
Definition: APInt.h:361
const Type * getScalarType() const LLVM_READONLY
getScalarType - If this is a vector type, return the element type, otherwise return 'this'...
Definition: Type.cpp:51
APInt And(const APInt &LHS, const APInt &RHS)
Bitwise AND function for APInt.
Definition: APInt.h:1890
static Constant * getNeg(Constant *C, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2239
bool isAllOnesValue() const
Determine if all bits are set.
Definition: APInt.h:337
static bool isZero(Value *V, const DataLayout &DL, DominatorTree *DT, AssumptionCache *AC)
Definition: Lint.cpp:697
static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS, bool &TrueIfSigned)
isSignBitCheck - Given an exploded icmp instruction, return true if the comparison only checks the si...
static const fltSemantics IEEEsingle
Definition: APFloat.h:132
bool isX86_FP80Ty() const
isX86_FP80Ty - Return true if this is x86 long double.
Definition: Type.h:149
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:239
opStatus roundToIntegral(roundingMode)
Definition: APFloat.cpp:1849
OverflowResult
bool isInBounds() const
Test whether this is an inbounds GEP, as defined by LangRef.html.
Definition: Operator.h:379
unsigned greater or equal
Definition: InstrTypes.h:721
void clearBit(unsigned bitPosition)
Set a given bit to 0.
Definition: APInt.cpp:597
#define I(x, y, z)
Definition: MD5.cpp:54
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
static Constant * getOr(Constant *C1, Constant *C2)
Definition: Constants.cpp:2321
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:311
0 1 1 0 True if ordered and operands are unequal
Definition: InstrTypes.h:705
bool isSignBit() const
Check if the APInt's value is returned by getSignBit.
Definition: APInt.h:395
static ConstantRange makeConstantRange(Predicate pred, const APInt &C)
Initialize a set of values that all satisfy the predicate with C.
unsigned countTrailingOnes() const
Count the number of trailing one bits.
Definition: APInt.h:1403
static Constant * getShl(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2329
Instruction * visitICmpInstWithInstAndIntCst(ICmpInst &ICI, Instruction *LHS, ConstantInt *RHS)
visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
uint64_t getArrayNumElements() const
Definition: Type.cpp:208
1 0 1 0 True if unordered or greater than
Definition: InstrTypes.h:709
Instruction * FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, ConstantInt *DivRHS)
FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS and CmpRHS are both known...
bool hasNUsesOrMore(unsigned N) const
Return true if this value has N users or more.
Definition: Value.cpp:104
Instruction * FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, CmpInst &ICI, ConstantInt *AndCst=nullptr)
FoldCmpLoadFromIndexedGlobal - Called we see this pattern: cmp pred (load (gep GV, ...)), cmpcst where GV is a global variable with a constant initializer.
Instruction * FoldICmpCstShlCst(ICmpInst &I, Value *Op, Value *A, ConstantInt *CI1, ConstantInt *CI2)
FoldICmpCstShlCst - Handle "(icmp eq/ne (shl const2, A), const1)" -> (icmp eq/ne A, TrailingZeros(const1) - TrailingZeros(const2)).
bool isUnsigned() const
Determine if this instruction is using an unsigned comparison.
Definition: InstrTypes.h:832
const APInt & getUpper() const
Return the upper value for this range.
Definition: ConstantRange.h:91
void swapOperands()
Exchange the two operands to this instruction in such a way that it does not modify the semantics of ...
user_iterator user_begin()
Definition: Value.h:294
static APInt getSignedMinValue(unsigned numBits)
Gets minimum signed value of APInt for a specific bit width.
Definition: APInt.h:436
static bool swapMayExposeCSEOpportunities(const Value *Op0, const Value *Op1)
Check if the order of Op0 and Op1 as operand in an ICmpInst should be swapped.
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
getPrimitiveSizeInBits - Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:121
unsigned ComputeNumSignBits(Value *Op, unsigned Depth=0, Instruction *CxtI=nullptr) const
0 0 0 1 True if ordered and equal
Definition: InstrTypes.h:700
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:365
Value * CreateTrunc(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1189
LLVM Value Representation.
Definition: Value.h:69
bool hasNoUnsignedWrap() const
Determine whether the no unsigned wrap flag is set.
This file provides internal interfaces used to implement the InstCombine.
1 0 1 1 True if unordered, greater than, or equal
Definition: InstrTypes.h:710
unsigned getOpcode() const
getOpcode() returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:112
bool isZero() const
Returns true if and only if the float is plus or minus zero.
Definition: APFloat.h:414
cst_pred_ty< is_one > m_One()
Match an integer 1 or a vector with all elements equal to 1.
Definition: PatternMatch.h:244
static Constant * getUIToFP(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1765
static Constant * getFPToSI(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1798
unsigned countLeadingZeros() const
The APInt version of the countLeadingZeros functions in MathExtras.h.
Definition: APInt.h:1361
Predicate getSignedPredicate() const
For example, EQ->EQ, SLE->SLE, UGT->SGT, etc.
Instruction * visitFCmpInst(FCmpInst &I)
static Constant * getExtractValue(Constant *Agg, ArrayRef< unsigned > Idxs, Type *OnlyIfReducedTy=nullptr)
Definition: Constants.cpp:2215
unsigned greater than
Definition: InstrTypes.h:720
bool dominatesAllUses(const Instruction *DI, const Instruction *UI, const BasicBlock *DB) const
Check that one use is in the same block as the definition and all other uses are in blocks dominated ...
APInt LLVM_ATTRIBUTE_UNUSED_RESULT zext(unsigned width) const
Zero extend to a new width.
Definition: APInt.cpp:996
void replaceUsesOutsideBlock(Value *V, BasicBlock *BB)
replaceUsesOutsideBlock - Go through the uses list for this definition and make each use point to "V"...
Definition: Value.cpp:384
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml","ocaml 3.10-compatible collector")
static bool isVolatile(Instruction *Inst)
static Constant * getMul(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2280
This class represents an extension of floating point types.
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:125
0 0 1 1 True if ordered and greater than or equal
Definition: InstrTypes.h:702
bool ule(const APInt &RHS) const
Unsigned less or equal comparison.
Definition: APInt.h:1069
const fltSemantics & getSemantics() const
Definition: APFloat.h:435
const BasicBlock * getParent() const
Definition: Instruction.h:72
static Constant * SubOne(Constant *C)
Subtract one from a Constant.
bool isOne() const
This is just a convenience method to make client code smaller for a common case.
Definition: Constants.h:169
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:299
Instruction * FoldICmpAddOpCst(Instruction &ICI, Value *X, ConstantInt *CI, ICmpInst::Predicate Pred)
FoldICmpAddOpCst - Fold "icmp pred (X+CI), X".
signed greater or equal
Definition: InstrTypes.h:725
UAddWithOverflow_match< LHS_t, RHS_t, Sum_t > m_UAddWithOverflow(const LHS_t &L, const RHS_t &R, const Sum_t &S)
Match an icmp instruction checking for unsigned overflow on addition.
IntrinsicInst - A useful wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:37
static Constant * getXor(Constant *C1, Constant *C2)
Definition: Constants.cpp:2325
gep_type_iterator gep_type_begin(const User *GEP)