Bug Summary

File:lib/Transforms/InstCombine/InstCombineCompares.cpp
Warning:line 2289, column 35
Called C++ object pointer is null

Annotated Source Code

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/SetVector.h"
17#include "llvm/ADT/Statistic.h"
18#include "llvm/Analysis/ConstantFolding.h"
19#include "llvm/Analysis/InstructionSimplify.h"
20#include "llvm/Analysis/MemoryBuiltins.h"
21#include "llvm/Analysis/TargetLibraryInfo.h"
22#include "llvm/Analysis/VectorUtils.h"
23#include "llvm/IR/ConstantRange.h"
24#include "llvm/IR/DataLayout.h"
25#include "llvm/IR/GetElementPtrTypeIterator.h"
26#include "llvm/IR/IntrinsicInst.h"
27#include "llvm/IR/PatternMatch.h"
28#include "llvm/Support/Debug.h"
29#include "llvm/Support/KnownBits.h"
30
31using namespace llvm;
32using namespace PatternMatch;
33
34#define DEBUG_TYPE"instcombine" "instcombine"
35
36// How many times is a select replaced by one of its operands?
37STATISTIC(NumSel, "Number of select opts")static llvm::Statistic NumSel = {"instcombine", "NumSel", "Number of select opts"
, {0}, false};
38
39
40static ConstantInt *extractElement(Constant *V, Constant *Idx) {
41 return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
42}
43
44static bool hasAddOverflow(ConstantInt *Result,
45 ConstantInt *In1, ConstantInt *In2,
46 bool IsSigned) {
47 if (!IsSigned)
48 return Result->getValue().ult(In1->getValue());
49
50 if (In2->isNegative())
51 return Result->getValue().sgt(In1->getValue());
52 return Result->getValue().slt(In1->getValue());
53}
54
55/// Compute Result = In1+In2, returning true if the result overflowed for this
56/// type.
57static bool addWithOverflow(Constant *&Result, Constant *In1,
58 Constant *In2, bool IsSigned = false) {
59 Result = ConstantExpr::getAdd(In1, In2);
60
61 if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
62 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
63 Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
64 if (hasAddOverflow(extractElement(Result, Idx),
65 extractElement(In1, Idx),
66 extractElement(In2, Idx),
67 IsSigned))
68 return true;
69 }
70 return false;
71 }
72
73 return hasAddOverflow(cast<ConstantInt>(Result),
74 cast<ConstantInt>(In1), cast<ConstantInt>(In2),
75 IsSigned);
76}
77
78static bool hasSubOverflow(ConstantInt *Result,
79 ConstantInt *In1, ConstantInt *In2,
80 bool IsSigned) {
81 if (!IsSigned)
82 return Result->getValue().ugt(In1->getValue());
83
84 if (In2->isNegative())
85 return Result->getValue().slt(In1->getValue());
86
87 return Result->getValue().sgt(In1->getValue());
88}
89
90/// Compute Result = In1-In2, returning true if the result overflowed for this
91/// type.
92static bool subWithOverflow(Constant *&Result, Constant *In1,
93 Constant *In2, bool IsSigned = false) {
94 Result = ConstantExpr::getSub(In1, In2);
95
96 if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
97 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
98 Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
99 if (hasSubOverflow(extractElement(Result, Idx),
100 extractElement(In1, Idx),
101 extractElement(In2, Idx),
102 IsSigned))
103 return true;
104 }
105 return false;
106 }
107
108 return hasSubOverflow(cast<ConstantInt>(Result),
109 cast<ConstantInt>(In1), cast<ConstantInt>(In2),
110 IsSigned);
111}
112
113/// Given an icmp instruction, return true if any use of this comparison is a
114/// branch on sign bit comparison.
115static bool isBranchOnSignBitCheck(ICmpInst &I, bool isSignBit) {
116 for (auto *U : I.users())
117 if (isa<BranchInst>(U))
118 return isSignBit;
119 return false;
120}
121
122/// Given an exploded icmp instruction, return true if the comparison only
123/// checks the sign bit. If it only checks the sign bit, set TrueIfSigned if the
124/// result of the comparison is true when the input value is signed.
125static bool isSignBitCheck(ICmpInst::Predicate Pred, const APInt &RHS,
126 bool &TrueIfSigned) {
127 switch (Pred) {
128 case ICmpInst::ICMP_SLT: // True if LHS s< 0
129 TrueIfSigned = true;
130 return RHS.isNullValue();
131 case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
132 TrueIfSigned = true;
133 return RHS.isAllOnesValue();
134 case ICmpInst::ICMP_SGT: // True if LHS s> -1
135 TrueIfSigned = false;
136 return RHS.isAllOnesValue();
137 case ICmpInst::ICMP_UGT:
138 // True if LHS u> RHS and RHS == high-bit-mask - 1
139 TrueIfSigned = true;
140 return RHS.isMaxSignedValue();
141 case ICmpInst::ICMP_UGE:
142 // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
143 TrueIfSigned = true;
144 return RHS.isSignMask();
145 default:
146 return false;
147 }
148}
149
150/// Returns true if the exploded icmp can be expressed as a signed comparison
151/// to zero and updates the predicate accordingly.
152/// The signedness of the comparison is preserved.
153/// TODO: Refactor with decomposeBitTestICmp()?
154static bool isSignTest(ICmpInst::Predicate &Pred, const APInt &C) {
155 if (!ICmpInst::isSigned(Pred))
156 return false;
157
158 if (C.isNullValue())
159 return ICmpInst::isRelational(Pred);
160
161 if (C.isOneValue()) {
162 if (Pred == ICmpInst::ICMP_SLT) {
163 Pred = ICmpInst::ICMP_SLE;
164 return true;
165 }
166 } else if (C.isAllOnesValue()) {
167 if (Pred == ICmpInst::ICMP_SGT) {
168 Pred = ICmpInst::ICMP_SGE;
169 return true;
170 }
171 }
172
173 return false;
174}
175
176/// Given a signed integer type and a set of known zero and one bits, compute
177/// the maximum and minimum values that could have the specified known zero and
178/// known one bits, returning them in Min/Max.
179/// TODO: Move to method on KnownBits struct?
180static void computeSignedMinMaxValuesFromKnownBits(const KnownBits &Known,
181 APInt &Min, APInt &Max) {
182 assert(Known.getBitWidth() == Min.getBitWidth() &&((Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth
() == Max.getBitWidth() && "KnownZero, KnownOne and Min, Max must have equal bitwidth."
) ? static_cast<void> (0) : __assert_fail ("Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth() == Max.getBitWidth() && \"KnownZero, KnownOne and Min, Max must have equal bitwidth.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 184, __PRETTY_FUNCTION__))
183 Known.getBitWidth() == Max.getBitWidth() &&((Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth
() == Max.getBitWidth() && "KnownZero, KnownOne and Min, Max must have equal bitwidth."
) ? static_cast<void> (0) : __assert_fail ("Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth() == Max.getBitWidth() && \"KnownZero, KnownOne and Min, Max must have equal bitwidth.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 184, __PRETTY_FUNCTION__))
184 "KnownZero, KnownOne and Min, Max must have equal bitwidth.")((Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth
() == Max.getBitWidth() && "KnownZero, KnownOne and Min, Max must have equal bitwidth."
) ? static_cast<void> (0) : __assert_fail ("Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth() == Max.getBitWidth() && \"KnownZero, KnownOne and Min, Max must have equal bitwidth.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 184, __PRETTY_FUNCTION__));
185 APInt UnknownBits = ~(Known.Zero|Known.One);
186
187 // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
188 // bit if it is unknown.
189 Min = Known.One;
190 Max = Known.One|UnknownBits;
191
192 if (UnknownBits.isNegative()) { // Sign bit is unknown
193 Min.setSignBit();
194 Max.clearSignBit();
195 }
196}
197
198/// Given an unsigned integer type and a set of known zero and one bits, compute
199/// the maximum and minimum values that could have the specified known zero and
200/// known one bits, returning them in Min/Max.
201/// TODO: Move to method on KnownBits struct?
202static void computeUnsignedMinMaxValuesFromKnownBits(const KnownBits &Known,
203 APInt &Min, APInt &Max) {
204 assert(Known.getBitWidth() == Min.getBitWidth() &&((Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth
() == Max.getBitWidth() && "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."
) ? static_cast<void> (0) : __assert_fail ("Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth() == Max.getBitWidth() && \"Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 206, __PRETTY_FUNCTION__))
205 Known.getBitWidth() == Max.getBitWidth() &&((Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth
() == Max.getBitWidth() && "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."
) ? static_cast<void> (0) : __assert_fail ("Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth() == Max.getBitWidth() && \"Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 206, __PRETTY_FUNCTION__))
206 "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.")((Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth
() == Max.getBitWidth() && "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."
) ? static_cast<void> (0) : __assert_fail ("Known.getBitWidth() == Min.getBitWidth() && Known.getBitWidth() == Max.getBitWidth() && \"Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 206, __PRETTY_FUNCTION__));
207 APInt UnknownBits = ~(Known.Zero|Known.One);
208
209 // The minimum value is when the unknown bits are all zeros.
210 Min = Known.One;
211 // The maximum value is when the unknown bits are all ones.
212 Max = Known.One|UnknownBits;
213}
214
215/// This is called when we see this pattern:
216/// cmp pred (load (gep GV, ...)), cmpcst
217/// where GV is a global variable with a constant initializer. Try to simplify
218/// this into some simple computation that does not need the load. For example
219/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
220///
221/// If AndCst is non-null, then the loaded value is masked with that constant
222/// before doing the comparison. This handles cases like "A[i]&4 == 0".
223Instruction *InstCombiner::foldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
224 GlobalVariable *GV,
225 CmpInst &ICI,
226 ConstantInt *AndCst) {
227 Constant *Init = GV->getInitializer();
228 if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init))
229 return nullptr;
230
231 uint64_t ArrayElementCount = Init->getType()->getArrayNumElements();
232 // Don't blow up on huge arrays.
233 if (ArrayElementCount > MaxArraySizeForCombine)
234 return nullptr;
235
236 // There are many forms of this optimization we can handle, for now, just do
237 // the simple index into a single-dimensional array.
238 //
239 // Require: GEP GV, 0, i {{, constant indices}}
240 if (GEP->getNumOperands() < 3 ||
241 !isa<ConstantInt>(GEP->getOperand(1)) ||
242 !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
243 isa<Constant>(GEP->getOperand(2)))
244 return nullptr;
245
246 // Check that indices after the variable are constants and in-range for the
247 // type they index. Collect the indices. This is typically for arrays of
248 // structs.
249 SmallVector<unsigned, 4> LaterIndices;
250
251 Type *EltTy = Init->getType()->getArrayElementType();
252 for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
253 ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
254 if (!Idx) return nullptr; // Variable index.
255
256 uint64_t IdxVal = Idx->getZExtValue();
257 if ((unsigned)IdxVal != IdxVal) return nullptr; // Too large array index.
258
259 if (StructType *STy = dyn_cast<StructType>(EltTy))
260 EltTy = STy->getElementType(IdxVal);
261 else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
262 if (IdxVal >= ATy->getNumElements()) return nullptr;
263 EltTy = ATy->getElementType();
264 } else {
265 return nullptr; // Unknown type.
266 }
267
268 LaterIndices.push_back(IdxVal);
269 }
270
271 enum { Overdefined = -3, Undefined = -2 };
272
273 // Variables for our state machines.
274
275 // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
276 // "i == 47 | i == 87", where 47 is the first index the condition is true for,
277 // and 87 is the second (and last) index. FirstTrueElement is -2 when
278 // undefined, otherwise set to the first true element. SecondTrueElement is
279 // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
280 int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
281
282 // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
283 // form "i != 47 & i != 87". Same state transitions as for true elements.
284 int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
285
286 /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
287 /// define a state machine that triggers for ranges of values that the index
288 /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
289 /// This is -2 when undefined, -3 when overdefined, and otherwise the last
290 /// index in the range (inclusive). We use -2 for undefined here because we
291 /// use relative comparisons and don't want 0-1 to match -1.
292 int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
293
294 // MagicBitvector - This is a magic bitvector where we set a bit if the
295 // comparison is true for element 'i'. If there are 64 elements or less in
296 // the array, this will fully represent all the comparison results.
297 uint64_t MagicBitvector = 0;
298
299 // Scan the array and see if one of our patterns matches.
300 Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
301 for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) {
302 Constant *Elt = Init->getAggregateElement(i);
303 if (!Elt) return nullptr;
304
305 // If this is indexing an array of structures, get the structure element.
306 if (!LaterIndices.empty())
307 Elt = ConstantExpr::getExtractValue(Elt, LaterIndices);
308
309 // If the element is masked, handle it.
310 if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
311
312 // Find out if the comparison would be true or false for the i'th element.
313 Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
314 CompareRHS, DL, &TLI);
315 // If the result is undef for this element, ignore it.
316 if (isa<UndefValue>(C)) {
317 // Extend range state machines to cover this element in case there is an
318 // undef in the middle of the range.
319 if (TrueRangeEnd == (int)i-1)
320 TrueRangeEnd = i;
321 if (FalseRangeEnd == (int)i-1)
322 FalseRangeEnd = i;
323 continue;
324 }
325
326 // If we can't compute the result for any of the elements, we have to give
327 // up evaluating the entire conditional.
328 if (!isa<ConstantInt>(C)) return nullptr;
329
330 // Otherwise, we know if the comparison is true or false for this element,
331 // update our state machines.
332 bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
333
334 // State machine for single/double/range index comparison.
335 if (IsTrueForElt) {
336 // Update the TrueElement state machine.
337 if (FirstTrueElement == Undefined)
338 FirstTrueElement = TrueRangeEnd = i; // First true element.
339 else {
340 // Update double-compare state machine.
341 if (SecondTrueElement == Undefined)
342 SecondTrueElement = i;
343 else
344 SecondTrueElement = Overdefined;
345
346 // Update range state machine.
347 if (TrueRangeEnd == (int)i-1)
348 TrueRangeEnd = i;
349 else
350 TrueRangeEnd = Overdefined;
351 }
352 } else {
353 // Update the FalseElement state machine.
354 if (FirstFalseElement == Undefined)
355 FirstFalseElement = FalseRangeEnd = i; // First false element.
356 else {
357 // Update double-compare state machine.
358 if (SecondFalseElement == Undefined)
359 SecondFalseElement = i;
360 else
361 SecondFalseElement = Overdefined;
362
363 // Update range state machine.
364 if (FalseRangeEnd == (int)i-1)
365 FalseRangeEnd = i;
366 else
367 FalseRangeEnd = Overdefined;
368 }
369 }
370
371 // If this element is in range, update our magic bitvector.
372 if (i < 64 && IsTrueForElt)
373 MagicBitvector |= 1ULL << i;
374
375 // If all of our states become overdefined, bail out early. Since the
376 // predicate is expensive, only check it every 8 elements. This is only
377 // really useful for really huge arrays.
378 if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
379 SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
380 FalseRangeEnd == Overdefined)
381 return nullptr;
382 }
383
384 // Now that we've scanned the entire array, emit our new comparison(s). We
385 // order the state machines in complexity of the generated code.
386 Value *Idx = GEP->getOperand(2);
387
388 // If the index is larger than the pointer size of the target, truncate the
389 // index down like the GEP would do implicitly. We don't have to do this for
390 // an inbounds GEP because the index can't be out of range.
391 if (!GEP->isInBounds()) {
392 Type *IntPtrTy = DL.getIntPtrType(GEP->getType());
393 unsigned PtrSize = IntPtrTy->getIntegerBitWidth();
394 if (Idx->getType()->getPrimitiveSizeInBits() > PtrSize)
395 Idx = Builder->CreateTrunc(Idx, IntPtrTy);
396 }
397
398 // If the comparison is only true for one or two elements, emit direct
399 // comparisons.
400 if (SecondTrueElement != Overdefined) {
401 // None true -> false.
402 if (FirstTrueElement == Undefined)
403 return replaceInstUsesWith(ICI, Builder->getFalse());
404
405 Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
406
407 // True for one element -> 'i == 47'.
408 if (SecondTrueElement == Undefined)
409 return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
410
411 // True for two elements -> 'i == 47 | i == 72'.
412 Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx);
413 Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
414 Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx);
415 return BinaryOperator::CreateOr(C1, C2);
416 }
417
418 // If the comparison is only false for one or two elements, emit direct
419 // comparisons.
420 if (SecondFalseElement != Overdefined) {
421 // None false -> true.
422 if (FirstFalseElement == Undefined)
423 return replaceInstUsesWith(ICI, Builder->getTrue());
424
425 Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
426
427 // False for one element -> 'i != 47'.
428 if (SecondFalseElement == Undefined)
429 return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
430
431 // False for two elements -> 'i != 47 & i != 72'.
432 Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx);
433 Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
434 Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx);
435 return BinaryOperator::CreateAnd(C1, C2);
436 }
437
438 // If the comparison can be replaced with a range comparison for the elements
439 // where it is true, emit the range check.
440 if (TrueRangeEnd != Overdefined) {
441 assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare")((TrueRangeEnd != FirstTrueElement && "Should emit single compare"
) ? static_cast<void> (0) : __assert_fail ("TrueRangeEnd != FirstTrueElement && \"Should emit single compare\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 441, __PRETTY_FUNCTION__));
442
443 // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
444 if (FirstTrueElement) {
445 Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
446 Idx = Builder->CreateAdd(Idx, Offs);
447 }
448
449 Value *End = ConstantInt::get(Idx->getType(),
450 TrueRangeEnd-FirstTrueElement+1);
451 return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
452 }
453
454 // False range check.
455 if (FalseRangeEnd != Overdefined) {
456 assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare")((FalseRangeEnd != FirstFalseElement && "Should emit single compare"
) ? static_cast<void> (0) : __assert_fail ("FalseRangeEnd != FirstFalseElement && \"Should emit single compare\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 456, __PRETTY_FUNCTION__));
457 // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
458 if (FirstFalseElement) {
459 Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
460 Idx = Builder->CreateAdd(Idx, Offs);
461 }
462
463 Value *End = ConstantInt::get(Idx->getType(),
464 FalseRangeEnd-FirstFalseElement);
465 return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
466 }
467
468 // If a magic bitvector captures the entire comparison state
469 // of this load, replace it with computation that does:
470 // ((magic_cst >> i) & 1) != 0
471 {
472 Type *Ty = nullptr;
473
474 // Look for an appropriate type:
475 // - The type of Idx if the magic fits
476 // - The smallest fitting legal type if we have a DataLayout
477 // - Default to i32
478 if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth())
479 Ty = Idx->getType();
480 else
481 Ty = DL.getSmallestLegalIntType(Init->getContext(), ArrayElementCount);
482
483 if (Ty) {
484 Value *V = Builder->CreateIntCast(Idx, Ty, false);
485 V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
486 V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V);
487 return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
488 }
489 }
490
491 return nullptr;
492}
493
494/// Return a value that can be used to compare the *offset* implied by a GEP to
495/// zero. For example, if we have &A[i], we want to return 'i' for
496/// "icmp ne i, 0". Note that, in general, indices can be complex, and scales
497/// are involved. The above expression would also be legal to codegen as
498/// "icmp ne (i*4), 0" (assuming A is a pointer to i32).
499/// This latter form is less amenable to optimization though, and we are allowed
500/// to generate the first by knowing that pointer arithmetic doesn't overflow.
501///
502/// If we can't emit an optimized form for this expression, this returns null.
503///
504static Value *evaluateGEPOffsetExpression(User *GEP, InstCombiner &IC,
505 const DataLayout &DL) {
506 gep_type_iterator GTI = gep_type_begin(GEP);
507
508 // Check to see if this gep only has a single variable index. If so, and if
509 // any constant indices are a multiple of its scale, then we can compute this
510 // in terms of the scale of the variable index. For example, if the GEP
511 // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
512 // because the expression will cross zero at the same point.
513 unsigned i, e = GEP->getNumOperands();
514 int64_t Offset = 0;
515 for (i = 1; i != e; ++i, ++GTI) {
516 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
517 // Compute the aggregate offset of constant indices.
518 if (CI->isZero()) continue;
519
520 // Handle a struct index, which adds its field offset to the pointer.
521 if (StructType *STy = GTI.getStructTypeOrNull()) {
522 Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
523 } else {
524 uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
525 Offset += Size*CI->getSExtValue();
526 }
527 } else {
528 // Found our variable index.
529 break;
530 }
531 }
532
533 // If there are no variable indices, we must have a constant offset, just
534 // evaluate it the general way.
535 if (i == e) return nullptr;
536
537 Value *VariableIdx = GEP->getOperand(i);
538 // Determine the scale factor of the variable element. For example, this is
539 // 4 if the variable index is into an array of i32.
540 uint64_t VariableScale = DL.getTypeAllocSize(GTI.getIndexedType());
541
542 // Verify that there are no other variable indices. If so, emit the hard way.
543 for (++i, ++GTI; i != e; ++i, ++GTI) {
544 ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
545 if (!CI) return nullptr;
546
547 // Compute the aggregate offset of constant indices.
548 if (CI->isZero()) continue;
549
550 // Handle a struct index, which adds its field offset to the pointer.
551 if (StructType *STy = GTI.getStructTypeOrNull()) {
552 Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
553 } else {
554 uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
555 Offset += Size*CI->getSExtValue();
556 }
557 }
558
559 // Okay, we know we have a single variable index, which must be a
560 // pointer/array/vector index. If there is no offset, life is simple, return
561 // the index.
562 Type *IntPtrTy = DL.getIntPtrType(GEP->getOperand(0)->getType());
563 unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth();
564 if (Offset == 0) {
565 // Cast to intptrty in case a truncation occurs. If an extension is needed,
566 // we don't need to bother extending: the extension won't affect where the
567 // computation crosses zero.
568 if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) {
569 VariableIdx = IC.Builder->CreateTrunc(VariableIdx, IntPtrTy);
570 }
571 return VariableIdx;
572 }
573
574 // Otherwise, there is an index. The computation we will do will be modulo
575 // the pointer size, so get it.
576 uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
577
578 Offset &= PtrSizeMask;
579 VariableScale &= PtrSizeMask;
580
581 // To do this transformation, any constant index must be a multiple of the
582 // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
583 // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
584 // multiple of the variable scale.
585 int64_t NewOffs = Offset / (int64_t)VariableScale;
586 if (Offset != NewOffs*(int64_t)VariableScale)
587 return nullptr;
588
589 // Okay, we can do this evaluation. Start by converting the index to intptr.
590 if (VariableIdx->getType() != IntPtrTy)
591 VariableIdx = IC.Builder->CreateIntCast(VariableIdx, IntPtrTy,
592 true /*Signed*/);
593 Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
594 return IC.Builder->CreateAdd(VariableIdx, OffsetVal, "offset");
595}
596
597/// Returns true if we can rewrite Start as a GEP with pointer Base
598/// and some integer offset. The nodes that need to be re-written
599/// for this transformation will be added to Explored.
600static bool canRewriteGEPAsOffset(Value *Start, Value *Base,
601 const DataLayout &DL,
602 SetVector<Value *> &Explored) {
603 SmallVector<Value *, 16> WorkList(1, Start);
604 Explored.insert(Base);
605
606 // The following traversal gives us an order which can be used
607 // when doing the final transformation. Since in the final
608 // transformation we create the PHI replacement instructions first,
609 // we don't have to get them in any particular order.
610 //
611 // However, for other instructions we will have to traverse the
612 // operands of an instruction first, which means that we have to
613 // do a post-order traversal.
614 while (!WorkList.empty()) {
615 SetVector<PHINode *> PHIs;
616
617 while (!WorkList.empty()) {
618 if (Explored.size() >= 100)
619 return false;
620
621 Value *V = WorkList.back();
622
623 if (Explored.count(V) != 0) {
624 WorkList.pop_back();
625 continue;
626 }
627
628 if (!isa<IntToPtrInst>(V) && !isa<PtrToIntInst>(V) &&
629 !isa<GetElementPtrInst>(V) && !isa<PHINode>(V))
630 // We've found some value that we can't explore which is different from
631 // the base. Therefore we can't do this transformation.
632 return false;
633
634 if (isa<IntToPtrInst>(V) || isa<PtrToIntInst>(V)) {
635 auto *CI = dyn_cast<CastInst>(V);
636 if (!CI->isNoopCast(DL))
637 return false;
638
639 if (Explored.count(CI->getOperand(0)) == 0)
640 WorkList.push_back(CI->getOperand(0));
641 }
642
643 if (auto *GEP = dyn_cast<GEPOperator>(V)) {
644 // We're limiting the GEP to having one index. This will preserve
645 // the original pointer type. We could handle more cases in the
646 // future.
647 if (GEP->getNumIndices() != 1 || !GEP->isInBounds() ||
648 GEP->getType() != Start->getType())
649 return false;
650
651 if (Explored.count(GEP->getOperand(0)) == 0)
652 WorkList.push_back(GEP->getOperand(0));
653 }
654
655 if (WorkList.back() == V) {
656 WorkList.pop_back();
657 // We've finished visiting this node, mark it as such.
658 Explored.insert(V);
659 }
660
661 if (auto *PN = dyn_cast<PHINode>(V)) {
662 // We cannot transform PHIs on unsplittable basic blocks.
663 if (isa<CatchSwitchInst>(PN->getParent()->getTerminator()))
664 return false;
665 Explored.insert(PN);
666 PHIs.insert(PN);
667 }
668 }
669
670 // Explore the PHI nodes further.
671 for (auto *PN : PHIs)
672 for (Value *Op : PN->incoming_values())
673 if (Explored.count(Op) == 0)
674 WorkList.push_back(Op);
675 }
676
677 // Make sure that we can do this. Since we can't insert GEPs in a basic
678 // block before a PHI node, we can't easily do this transformation if
679 // we have PHI node users of transformed instructions.
680 for (Value *Val : Explored) {
681 for (Value *Use : Val->uses()) {
682
683 auto *PHI = dyn_cast<PHINode>(Use);
684 auto *Inst = dyn_cast<Instruction>(Val);
685
686 if (Inst == Base || Inst == PHI || !Inst || !PHI ||
687 Explored.count(PHI) == 0)
688 continue;
689
690 if (PHI->getParent() == Inst->getParent())
691 return false;
692 }
693 }
694 return true;
695}
696
697// Sets the appropriate insert point on Builder where we can add
698// a replacement Instruction for V (if that is possible).
699static void setInsertionPoint(IRBuilder<> &Builder, Value *V,
700 bool Before = true) {
701 if (auto *PHI = dyn_cast<PHINode>(V)) {
702 Builder.SetInsertPoint(&*PHI->getParent()->getFirstInsertionPt());
703 return;
704 }
705 if (auto *I = dyn_cast<Instruction>(V)) {
706 if (!Before)
707 I = &*std::next(I->getIterator());
708 Builder.SetInsertPoint(I);
709 return;
710 }
711 if (auto *A = dyn_cast<Argument>(V)) {
712 // Set the insertion point in the entry block.
713 BasicBlock &Entry = A->getParent()->getEntryBlock();
714 Builder.SetInsertPoint(&*Entry.getFirstInsertionPt());
715 return;
716 }
717 // Otherwise, this is a constant and we don't need to set a new
718 // insertion point.
719 assert(isa<Constant>(V) && "Setting insertion point for unknown value!")((isa<Constant>(V) && "Setting insertion point for unknown value!"
) ? static_cast<void> (0) : __assert_fail ("isa<Constant>(V) && \"Setting insertion point for unknown value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 719, __PRETTY_FUNCTION__));
720}
721
722/// Returns a re-written value of Start as an indexed GEP using Base as a
723/// pointer.
724static Value *rewriteGEPAsOffset(Value *Start, Value *Base,
725 const DataLayout &DL,
726 SetVector<Value *> &Explored) {
727 // Perform all the substitutions. This is a bit tricky because we can
728 // have cycles in our use-def chains.
729 // 1. Create the PHI nodes without any incoming values.
730 // 2. Create all the other values.
731 // 3. Add the edges for the PHI nodes.
732 // 4. Emit GEPs to get the original pointers.
733 // 5. Remove the original instructions.
734 Type *IndexType = IntegerType::get(
735 Base->getContext(), DL.getPointerTypeSizeInBits(Start->getType()));
736
737 DenseMap<Value *, Value *> NewInsts;
738 NewInsts[Base] = ConstantInt::getNullValue(IndexType);
739
740 // Create the new PHI nodes, without adding any incoming values.
741 for (Value *Val : Explored) {
742 if (Val == Base)
743 continue;
744 // Create empty phi nodes. This avoids cyclic dependencies when creating
745 // the remaining instructions.
746 if (auto *PHI = dyn_cast<PHINode>(Val))
747 NewInsts[PHI] = PHINode::Create(IndexType, PHI->getNumIncomingValues(),
748 PHI->getName() + ".idx", PHI);
749 }
750 IRBuilder<> Builder(Base->getContext());
751
752 // Create all the other instructions.
753 for (Value *Val : Explored) {
754
755 if (NewInsts.find(Val) != NewInsts.end())
756 continue;
757
758 if (auto *CI = dyn_cast<CastInst>(Val)) {
759 NewInsts[CI] = NewInsts[CI->getOperand(0)];
760 continue;
761 }
762 if (auto *GEP = dyn_cast<GEPOperator>(Val)) {
763 Value *Index = NewInsts[GEP->getOperand(1)] ? NewInsts[GEP->getOperand(1)]
764 : GEP->getOperand(1);
765 setInsertionPoint(Builder, GEP);
766 // Indices might need to be sign extended. GEPs will magically do
767 // this, but we need to do it ourselves here.
768 if (Index->getType()->getScalarSizeInBits() !=
769 NewInsts[GEP->getOperand(0)]->getType()->getScalarSizeInBits()) {
770 Index = Builder.CreateSExtOrTrunc(
771 Index, NewInsts[GEP->getOperand(0)]->getType(),
772 GEP->getOperand(0)->getName() + ".sext");
773 }
774
775 auto *Op = NewInsts[GEP->getOperand(0)];
776 if (isa<ConstantInt>(Op) && dyn_cast<ConstantInt>(Op)->isZero())
777 NewInsts[GEP] = Index;
778 else
779 NewInsts[GEP] = Builder.CreateNSWAdd(
780 Op, Index, GEP->getOperand(0)->getName() + ".add");
781 continue;
782 }
783 if (isa<PHINode>(Val))
784 continue;
785
786 llvm_unreachable("Unexpected instruction type")::llvm::llvm_unreachable_internal("Unexpected instruction type"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 786);
787 }
788
789 // Add the incoming values to the PHI nodes.
790 for (Value *Val : Explored) {
791 if (Val == Base)
792 continue;
793 // All the instructions have been created, we can now add edges to the
794 // phi nodes.
795 if (auto *PHI = dyn_cast<PHINode>(Val)) {
796 PHINode *NewPhi = static_cast<PHINode *>(NewInsts[PHI]);
797 for (unsigned I = 0, E = PHI->getNumIncomingValues(); I < E; ++I) {
798 Value *NewIncoming = PHI->getIncomingValue(I);
799
800 if (NewInsts.find(NewIncoming) != NewInsts.end())
801 NewIncoming = NewInsts[NewIncoming];
802
803 NewPhi->addIncoming(NewIncoming, PHI->getIncomingBlock(I));
804 }
805 }
806 }
807
808 for (Value *Val : Explored) {
809 if (Val == Base)
810 continue;
811
812 // Depending on the type, for external users we have to emit
813 // a GEP or a GEP + ptrtoint.
814 setInsertionPoint(Builder, Val, false);
815
816 // If required, create an inttoptr instruction for Base.
817 Value *NewBase = Base;
818 if (!Base->getType()->isPointerTy())
819 NewBase = Builder.CreateBitOrPointerCast(Base, Start->getType(),
820 Start->getName() + "to.ptr");
821
822 Value *GEP = Builder.CreateInBoundsGEP(
823 Start->getType()->getPointerElementType(), NewBase,
824 makeArrayRef(NewInsts[Val]), Val->getName() + ".ptr");
825
826 if (!Val->getType()->isPointerTy()) {
827 Value *Cast = Builder.CreatePointerCast(GEP, Val->getType(),
828 Val->getName() + ".conv");
829 GEP = Cast;
830 }
831 Val->replaceAllUsesWith(GEP);
832 }
833
834 return NewInsts[Start];
835}
836
837/// Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express
838/// the input Value as a constant indexed GEP. Returns a pair containing
839/// the GEPs Pointer and Index.
840static std::pair<Value *, Value *>
841getAsConstantIndexedAddress(Value *V, const DataLayout &DL) {
842 Type *IndexType = IntegerType::get(V->getContext(),
843 DL.getPointerTypeSizeInBits(V->getType()));
844
845 Constant *Index = ConstantInt::getNullValue(IndexType);
846 while (true) {
847 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
848 // We accept only inbouds GEPs here to exclude the possibility of
849 // overflow.
850 if (!GEP->isInBounds())
851 break;
852 if (GEP->hasAllConstantIndices() && GEP->getNumIndices() == 1 &&
853 GEP->getType() == V->getType()) {
854 V = GEP->getOperand(0);
855 Constant *GEPIndex = static_cast<Constant *>(GEP->getOperand(1));
856 Index = ConstantExpr::getAdd(
857 Index, ConstantExpr::getSExtOrBitCast(GEPIndex, IndexType));
858 continue;
859 }
860 break;
861 }
862 if (auto *CI = dyn_cast<IntToPtrInst>(V)) {
863 if (!CI->isNoopCast(DL))
864 break;
865 V = CI->getOperand(0);
866 continue;
867 }
868 if (auto *CI = dyn_cast<PtrToIntInst>(V)) {
869 if (!CI->isNoopCast(DL))
870 break;
871 V = CI->getOperand(0);
872 continue;
873 }
874 break;
875 }
876 return {V, Index};
877}
878
879/// Converts (CMP GEPLHS, RHS) if this change would make RHS a constant.
880/// We can look through PHIs, GEPs and casts in order to determine a common base
881/// between GEPLHS and RHS.
882static Instruction *transformToIndexedCompare(GEPOperator *GEPLHS, Value *RHS,
883 ICmpInst::Predicate Cond,
884 const DataLayout &DL) {
885 if (!GEPLHS->hasAllConstantIndices())
886 return nullptr;
887
888 // Make sure the pointers have the same type.
889 if (GEPLHS->getType() != RHS->getType())
890 return nullptr;
891
892 Value *PtrBase, *Index;
893 std::tie(PtrBase, Index) = getAsConstantIndexedAddress(GEPLHS, DL);
894
895 // The set of nodes that will take part in this transformation.
896 SetVector<Value *> Nodes;
897
898 if (!canRewriteGEPAsOffset(RHS, PtrBase, DL, Nodes))
899 return nullptr;
900
901 // We know we can re-write this as
902 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2)
903 // Since we've only looked through inbouds GEPs we know that we
904 // can't have overflow on either side. We can therefore re-write
905 // this as:
906 // OFFSET1 cmp OFFSET2
907 Value *NewRHS = rewriteGEPAsOffset(RHS, PtrBase, DL, Nodes);
908
909 // RewriteGEPAsOffset has replaced RHS and all of its uses with a re-written
910 // GEP having PtrBase as the pointer base, and has returned in NewRHS the
911 // offset. Since Index is the offset of LHS to the base pointer, we will now
912 // compare the offsets instead of comparing the pointers.
913 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Index, NewRHS);
914}
915
916/// Fold comparisons between a GEP instruction and something else. At this point
917/// we know that the GEP is on the LHS of the comparison.
918Instruction *InstCombiner::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
919 ICmpInst::Predicate Cond,
920 Instruction &I) {
921 // Don't transform signed compares of GEPs into index compares. Even if the
922 // GEP is inbounds, the final add of the base pointer can have signed overflow
923 // and would change the result of the icmp.
924 // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be
925 // the maximum signed value for the pointer type.
926 if (ICmpInst::isSigned(Cond))
927 return nullptr;
928
929 // Look through bitcasts and addrspacecasts. We do not however want to remove
930 // 0 GEPs.
931 if (!isa<GetElementPtrInst>(RHS))
932 RHS = RHS->stripPointerCasts();
933
934 Value *PtrBase = GEPLHS->getOperand(0);
935 if (PtrBase == RHS && GEPLHS->isInBounds()) {
936 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
937 // This transformation (ignoring the base and scales) is valid because we
938 // know pointers can't overflow since the gep is inbounds. See if we can
939 // output an optimized form.
940 Value *Offset = evaluateGEPOffsetExpression(GEPLHS, *this, DL);
941
942 // If not, synthesize the offset the hard way.
943 if (!Offset)
944 Offset = EmitGEPOffset(GEPLHS);
945 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
946 Constant::getNullValue(Offset->getType()));
947 } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
948 // If the base pointers are different, but the indices are the same, just
949 // compare the base pointer.
950 if (PtrBase != GEPRHS->getOperand(0)) {
951 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
952 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
953 GEPRHS->getOperand(0)->getType();
954 if (IndicesTheSame)
955 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
956 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
957 IndicesTheSame = false;
958 break;
959 }
960
961 // If all indices are the same, just compare the base pointers.
962 if (IndicesTheSame)
963 return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0));
964
965 // If we're comparing GEPs with two base pointers that only differ in type
966 // and both GEPs have only constant indices or just one use, then fold
967 // the compare with the adjusted indices.
968 if (GEPLHS->isInBounds() && GEPRHS->isInBounds() &&
969 (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) &&
970 (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) &&
971 PtrBase->stripPointerCasts() ==
972 GEPRHS->getOperand(0)->stripPointerCasts()) {
973 Value *LOffset = EmitGEPOffset(GEPLHS);
974 Value *ROffset = EmitGEPOffset(GEPRHS);
975
976 // If we looked through an addrspacecast between different sized address
977 // spaces, the LHS and RHS pointers are different sized
978 // integers. Truncate to the smaller one.
979 Type *LHSIndexTy = LOffset->getType();
980 Type *RHSIndexTy = ROffset->getType();
981 if (LHSIndexTy != RHSIndexTy) {
982 if (LHSIndexTy->getPrimitiveSizeInBits() <
983 RHSIndexTy->getPrimitiveSizeInBits()) {
984 ROffset = Builder->CreateTrunc(ROffset, LHSIndexTy);
985 } else
986 LOffset = Builder->CreateTrunc(LOffset, RHSIndexTy);
987 }
988
989 Value *Cmp = Builder->CreateICmp(ICmpInst::getSignedPredicate(Cond),
990 LOffset, ROffset);
991 return replaceInstUsesWith(I, Cmp);
992 }
993
994 // Otherwise, the base pointers are different and the indices are
995 // different. Try convert this to an indexed compare by looking through
996 // PHIs/casts.
997 return transformToIndexedCompare(GEPLHS, RHS, Cond, DL);
998 }
999
1000 // If one of the GEPs has all zero indices, recurse.
1001 if (GEPLHS->hasAllZeroIndices())
1002 return foldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
1003 ICmpInst::getSwappedPredicate(Cond), I);
1004
1005 // If the other GEP has all zero indices, recurse.
1006 if (GEPRHS->hasAllZeroIndices())
1007 return foldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
1008
1009 bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds();
1010 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
1011 // If the GEPs only differ by one index, compare it.
1012 unsigned NumDifferences = 0; // Keep track of # differences.
1013 unsigned DiffOperand = 0; // The operand that differs.
1014 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
1015 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
1016 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
1017 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
1018 // Irreconcilable differences.
1019 NumDifferences = 2;
1020 break;
1021 } else {
1022 if (NumDifferences++) break;
1023 DiffOperand = i;
1024 }
1025 }
1026
1027 if (NumDifferences == 0) // SAME GEP?
1028 return replaceInstUsesWith(I, // No comparison is needed here.
1029 Builder->getInt1(ICmpInst::isTrueWhenEqual(Cond)));
1030
1031 else if (NumDifferences == 1 && GEPsInBounds) {
1032 Value *LHSV = GEPLHS->getOperand(DiffOperand);
1033 Value *RHSV = GEPRHS->getOperand(DiffOperand);
1034 // Make sure we do a signed comparison here.
1035 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
1036 }
1037 }
1038
1039 // Only lower this if the icmp is the only user of the GEP or if we expect
1040 // the result to fold to a constant!
1041 if (GEPsInBounds && (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
1042 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
1043 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
1044 Value *L = EmitGEPOffset(GEPLHS);
1045 Value *R = EmitGEPOffset(GEPRHS);
1046 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
1047 }
1048 }
1049
1050 // Try convert this to an indexed compare by looking through PHIs/casts as a
1051 // last resort.
1052 return transformToIndexedCompare(GEPLHS, RHS, Cond, DL);
1053}
1054
1055Instruction *InstCombiner::foldAllocaCmp(ICmpInst &ICI,
1056 const AllocaInst *Alloca,
1057 const Value *Other) {
1058 assert(ICI.isEquality() && "Cannot fold non-equality comparison.")((ICI.isEquality() && "Cannot fold non-equality comparison."
) ? static_cast<void> (0) : __assert_fail ("ICI.isEquality() && \"Cannot fold non-equality comparison.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1058, __PRETTY_FUNCTION__));
1059
1060 // It would be tempting to fold away comparisons between allocas and any
1061 // pointer not based on that alloca (e.g. an argument). However, even
1062 // though such pointers cannot alias, they can still compare equal.
1063 //
1064 // But LLVM doesn't specify where allocas get their memory, so if the alloca
1065 // doesn't escape we can argue that it's impossible to guess its value, and we
1066 // can therefore act as if any such guesses are wrong.
1067 //
1068 // The code below checks that the alloca doesn't escape, and that it's only
1069 // used in a comparison once (the current instruction). The
1070 // single-comparison-use condition ensures that we're trivially folding all
1071 // comparisons against the alloca consistently, and avoids the risk of
1072 // erroneously folding a comparison of the pointer with itself.
1073
1074 unsigned MaxIter = 32; // Break cycles and bound to constant-time.
1075
1076 SmallVector<const Use *, 32> Worklist;
1077 for (const Use &U : Alloca->uses()) {
1078 if (Worklist.size() >= MaxIter)
1079 return nullptr;
1080 Worklist.push_back(&U);
1081 }
1082
1083 unsigned NumCmps = 0;
1084 while (!Worklist.empty()) {
1085 assert(Worklist.size() <= MaxIter)((Worklist.size() <= MaxIter) ? static_cast<void> (0
) : __assert_fail ("Worklist.size() <= MaxIter", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1085, __PRETTY_FUNCTION__));
1086 const Use *U = Worklist.pop_back_val();
1087 const Value *V = U->getUser();
1088 --MaxIter;
1089
1090 if (isa<BitCastInst>(V) || isa<GetElementPtrInst>(V) || isa<PHINode>(V) ||
1091 isa<SelectInst>(V)) {
1092 // Track the uses.
1093 } else if (isa<LoadInst>(V)) {
1094 // Loading from the pointer doesn't escape it.
1095 continue;
1096 } else if (const auto *SI = dyn_cast<StoreInst>(V)) {
1097 // Storing *to* the pointer is fine, but storing the pointer escapes it.
1098 if (SI->getValueOperand() == U->get())
1099 return nullptr;
1100 continue;
1101 } else if (isa<ICmpInst>(V)) {
1102 if (NumCmps++)
1103 return nullptr; // Found more than one cmp.
1104 continue;
1105 } else if (const auto *Intrin = dyn_cast<IntrinsicInst>(V)) {
1106 switch (Intrin->getIntrinsicID()) {
1107 // These intrinsics don't escape or compare the pointer. Memset is safe
1108 // because we don't allow ptrtoint. Memcpy and memmove are safe because
1109 // we don't allow stores, so src cannot point to V.
1110 case Intrinsic::lifetime_start: case Intrinsic::lifetime_end:
1111 case Intrinsic::dbg_declare: case Intrinsic::dbg_value:
1112 case Intrinsic::memcpy: case Intrinsic::memmove: case Intrinsic::memset:
1113 continue;
1114 default:
1115 return nullptr;
1116 }
1117 } else {
1118 return nullptr;
1119 }
1120 for (const Use &U : V->uses()) {
1121 if (Worklist.size() >= MaxIter)
1122 return nullptr;
1123 Worklist.push_back(&U);
1124 }
1125 }
1126
1127 Type *CmpTy = CmpInst::makeCmpResultType(Other->getType());
1128 return replaceInstUsesWith(
1129 ICI,
1130 ConstantInt::get(CmpTy, !CmpInst::isTrueWhenEqual(ICI.getPredicate())));
1131}
1132
1133/// Fold "icmp pred (X+CI), X".
1134Instruction *InstCombiner::foldICmpAddOpConst(Instruction &ICI,
1135 Value *X, ConstantInt *CI,
1136 ICmpInst::Predicate Pred) {
1137 // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
1138 // so the values can never be equal. Similarly for all other "or equals"
1139 // operators.
1140
1141 // (X+1) <u X --> X >u (MAXUINT-1) --> X == 255
1142 // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
1143 // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
1144 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
1145 Value *R =
1146 ConstantExpr::getSub(ConstantInt::getAllOnesValue(CI->getType()), CI);
1147 return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
1148 }
1149
1150 // (X+1) >u X --> X <u (0-1) --> X != 255
1151 // (X+2) >u X --> X <u (0-2) --> X <u 254
1152 // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
1153 if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE)
1154 return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI));
1155
1156 unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits();
1157 ConstantInt *SMax = ConstantInt::get(X->getContext(),
1158 APInt::getSignedMaxValue(BitWidth));
1159
1160 // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
1161 // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
1162 // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
1163 // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
1164 // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
1165 // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
1166 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
1167 return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI));
1168
1169 // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
1170 // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
1171 // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
1172 // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
1173 // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
1174 // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
1175
1176 assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)((Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) ?
static_cast<void> (0) : __assert_fail ("Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1176, __PRETTY_FUNCTION__));
1177 Constant *C = Builder->getInt(CI->getValue()-1);
1178 return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C));
1179}
1180
1181/// Handle "(icmp eq/ne (ashr/lshr AP2, A), AP1)" ->
1182/// (icmp eq/ne A, Log2(AP2/AP1)) ->
1183/// (icmp eq/ne A, Log2(AP2) - Log2(AP1)).
1184Instruction *InstCombiner::foldICmpShrConstConst(ICmpInst &I, Value *A,
1185 const APInt &AP1,
1186 const APInt &AP2) {
1187 assert(I.isEquality() && "Cannot fold icmp gt/lt")((I.isEquality() && "Cannot fold icmp gt/lt") ? static_cast
<void> (0) : __assert_fail ("I.isEquality() && \"Cannot fold icmp gt/lt\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1187, __PRETTY_FUNCTION__));
1188
1189 auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
1190 if (I.getPredicate() == I.ICMP_NE)
1191 Pred = CmpInst::getInversePredicate(Pred);
1192 return new ICmpInst(Pred, LHS, RHS);
1193 };
1194
1195 // Don't bother doing any work for cases which InstSimplify handles.
1196 if (AP2.isNullValue())
1197 return nullptr;
1198
1199 bool IsAShr = isa<AShrOperator>(I.getOperand(0));
1200 if (IsAShr) {
1201 if (AP2.isAllOnesValue())
1202 return nullptr;
1203 if (AP2.isNegative() != AP1.isNegative())
1204 return nullptr;
1205 if (AP2.sgt(AP1))
1206 return nullptr;
1207 }
1208
1209 if (!AP1)
1210 // 'A' must be large enough to shift out the highest set bit.
1211 return getICmp(I.ICMP_UGT, A,
1212 ConstantInt::get(A->getType(), AP2.logBase2()));
1213
1214 if (AP1 == AP2)
1215 return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
1216
1217 int Shift;
1218 if (IsAShr && AP1.isNegative())
1219 Shift = AP1.countLeadingOnes() - AP2.countLeadingOnes();
1220 else
1221 Shift = AP1.countLeadingZeros() - AP2.countLeadingZeros();
1222
1223 if (Shift > 0) {
1224 if (IsAShr && AP1 == AP2.ashr(Shift)) {
1225 // There are multiple solutions if we are comparing against -1 and the LHS
1226 // of the ashr is not a power of two.
1227 if (AP1.isAllOnesValue() && !AP2.isPowerOf2())
1228 return getICmp(I.ICMP_UGE, A, ConstantInt::get(A->getType(), Shift));
1229 return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1230 } else if (AP1 == AP2.lshr(Shift)) {
1231 return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1232 }
1233 }
1234
1235 // Shifting const2 will never be equal to const1.
1236 // FIXME: This should always be handled by InstSimplify?
1237 auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE);
1238 return replaceInstUsesWith(I, TorF);
1239}
1240
1241/// Handle "(icmp eq/ne (shl AP2, A), AP1)" ->
1242/// (icmp eq/ne A, TrailingZeros(AP1) - TrailingZeros(AP2)).
1243Instruction *InstCombiner::foldICmpShlConstConst(ICmpInst &I, Value *A,
1244 const APInt &AP1,
1245 const APInt &AP2) {
1246 assert(I.isEquality() && "Cannot fold icmp gt/lt")((I.isEquality() && "Cannot fold icmp gt/lt") ? static_cast
<void> (0) : __assert_fail ("I.isEquality() && \"Cannot fold icmp gt/lt\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1246, __PRETTY_FUNCTION__));
1247
1248 auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
1249 if (I.getPredicate() == I.ICMP_NE)
1250 Pred = CmpInst::getInversePredicate(Pred);
1251 return new ICmpInst(Pred, LHS, RHS);
1252 };
1253
1254 // Don't bother doing any work for cases which InstSimplify handles.
1255 if (AP2.isNullValue())
1256 return nullptr;
1257
1258 unsigned AP2TrailingZeros = AP2.countTrailingZeros();
1259
1260 if (!AP1 && AP2TrailingZeros != 0)
1261 return getICmp(
1262 I.ICMP_UGE, A,
1263 ConstantInt::get(A->getType(), AP2.getBitWidth() - AP2TrailingZeros));
1264
1265 if (AP1 == AP2)
1266 return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
1267
1268 // Get the distance between the lowest bits that are set.
1269 int Shift = AP1.countTrailingZeros() - AP2TrailingZeros;
1270
1271 if (Shift > 0 && AP2.shl(Shift) == AP1)
1272 return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1273
1274 // Shifting const2 will never be equal to const1.
1275 // FIXME: This should always be handled by InstSimplify?
1276 auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE);
1277 return replaceInstUsesWith(I, TorF);
1278}
1279
1280/// The caller has matched a pattern of the form:
1281/// I = icmp ugt (add (add A, B), CI2), CI1
1282/// If this is of the form:
1283/// sum = a + b
1284/// if (sum+128 >u 255)
1285/// Then replace it with llvm.sadd.with.overflow.i8.
1286///
1287static Instruction *processUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
1288 ConstantInt *CI2, ConstantInt *CI1,
1289 InstCombiner &IC) {
1290 // The transformation we're trying to do here is to transform this into an
1291 // llvm.sadd.with.overflow. To do this, we have to replace the original add
1292 // with a narrower add, and discard the add-with-constant that is part of the
1293 // range check (if we can't eliminate it, this isn't profitable).
1294
1295 // In order to eliminate the add-with-constant, the compare can be its only
1296 // use.
1297 Instruction *AddWithCst = cast<Instruction>(I.getOperand(0));
1298 if (!AddWithCst->hasOneUse())
1299 return nullptr;
1300
1301 // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow.
1302 if (!CI2->getValue().isPowerOf2())
1303 return nullptr;
1304 unsigned NewWidth = CI2->getValue().countTrailingZeros();
1305 if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31)
1306 return nullptr;
1307
1308 // The width of the new add formed is 1 more than the bias.
1309 ++NewWidth;
1310
1311 // Check to see that CI1 is an all-ones value with NewWidth bits.
1312 if (CI1->getBitWidth() == NewWidth ||
1313 CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth))
1314 return nullptr;
1315
1316 // This is only really a signed overflow check if the inputs have been
1317 // sign-extended; check for that condition. For example, if CI2 is 2^31 and
1318 // the operands of the add are 64 bits wide, we need at least 33 sign bits.
1319 unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1;
1320 if (IC.ComputeNumSignBits(A, 0, &I) < NeededSignBits ||
1321 IC.ComputeNumSignBits(B, 0, &I) < NeededSignBits)
1322 return nullptr;
1323
1324 // In order to replace the original add with a narrower
1325 // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant
1326 // and truncates that discard the high bits of the add. Verify that this is
1327 // the case.
1328 Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0));
1329 for (User *U : OrigAdd->users()) {
1330 if (U == AddWithCst)
1331 continue;
1332
1333 // Only accept truncates for now. We would really like a nice recursive
1334 // predicate like SimplifyDemandedBits, but which goes downwards the use-def
1335 // chain to see which bits of a value are actually demanded. If the
1336 // original add had another add which was then immediately truncated, we
1337 // could still do the transformation.
1338 TruncInst *TI = dyn_cast<TruncInst>(U);
1339 if (!TI || TI->getType()->getPrimitiveSizeInBits() > NewWidth)
1340 return nullptr;
1341 }
1342
1343 // If the pattern matches, truncate the inputs to the narrower type and
1344 // use the sadd_with_overflow intrinsic to efficiently compute both the
1345 // result and the overflow bit.
1346 Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth);
1347 Value *F = Intrinsic::getDeclaration(I.getModule(),
1348 Intrinsic::sadd_with_overflow, NewType);
1349
1350 InstCombiner::BuilderTy *Builder = IC.Builder;
1351
1352 // Put the new code above the original add, in case there are any uses of the
1353 // add between the add and the compare.
1354 Builder->SetInsertPoint(OrigAdd);
1355
1356 Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName() + ".trunc");
1357 Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName() + ".trunc");
1358 CallInst *Call = Builder->CreateCall(F, {TruncA, TruncB}, "sadd");
1359 Value *Add = Builder->CreateExtractValue(Call, 0, "sadd.result");
1360 Value *ZExt = Builder->CreateZExt(Add, OrigAdd->getType());
1361
1362 // The inner add was the result of the narrow add, zero extended to the
1363 // wider type. Replace it with the result computed by the intrinsic.
1364 IC.replaceInstUsesWith(*OrigAdd, ZExt);
1365
1366 // The original icmp gets replaced with the overflow value.
1367 return ExtractValueInst::Create(Call, 1, "sadd.overflow");
1368}
1369
1370// Fold icmp Pred X, C.
1371Instruction *InstCombiner::foldICmpWithConstant(ICmpInst &Cmp) {
1372 CmpInst::Predicate Pred = Cmp.getPredicate();
1373 Value *X = Cmp.getOperand(0);
1374
1375 const APInt *C;
1376 if (!match(Cmp.getOperand(1), m_APInt(C)))
1377 return nullptr;
1378
1379 Value *A = nullptr, *B = nullptr;
1380
1381 // Match the following pattern, which is a common idiom when writing
1382 // overflow-safe integer arithmetic functions. The source performs an addition
1383 // in wider type and explicitly checks for overflow using comparisons against
1384 // INT_MIN and INT_MAX. Simplify by using the sadd_with_overflow intrinsic.
1385 //
1386 // TODO: This could probably be generalized to handle other overflow-safe
1387 // operations if we worked out the formulas to compute the appropriate magic
1388 // constants.
1389 //
1390 // sum = a + b
1391 // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8
1392 {
1393 ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI
1394 if (Pred == ICmpInst::ICMP_UGT &&
1395 match(X, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2))))
1396 if (Instruction *Res = processUGT_ADDCST_ADD(
1397 Cmp, A, B, CI2, cast<ConstantInt>(Cmp.getOperand(1)), *this))
1398 return Res;
1399 }
1400
1401 // (icmp sgt smin(PosA, B) 0) -> (icmp sgt B 0)
1402 if (C->isNullValue() && Pred == ICmpInst::ICMP_SGT) {
1403 SelectPatternResult SPR = matchSelectPattern(X, A, B);
1404 if (SPR.Flavor == SPF_SMIN) {
1405 if (isKnownPositive(A, DL, 0, &AC, &Cmp, &DT))
1406 return new ICmpInst(Pred, B, Cmp.getOperand(1));
1407 if (isKnownPositive(B, DL, 0, &AC, &Cmp, &DT))
1408 return new ICmpInst(Pred, A, Cmp.getOperand(1));
1409 }
1410 }
1411
1412 // FIXME: Use m_APInt to allow folds for splat constants.
1413 ConstantInt *CI = dyn_cast<ConstantInt>(Cmp.getOperand(1));
1414 if (!CI)
1415 return nullptr;
1416
1417 // Canonicalize icmp instructions based on dominating conditions.
1418 BasicBlock *Parent = Cmp.getParent();
1419 BasicBlock *Dom = Parent->getSinglePredecessor();
1420 auto *BI = Dom ? dyn_cast<BranchInst>(Dom->getTerminator()) : nullptr;
1421 ICmpInst::Predicate Pred2;
1422 BasicBlock *TrueBB, *FalseBB;
1423 ConstantInt *CI2;
1424 if (BI && match(BI, m_Br(m_ICmp(Pred2, m_Specific(X), m_ConstantInt(CI2)),
1425 TrueBB, FalseBB)) &&
1426 TrueBB != FalseBB) {
1427 ConstantRange CR =
1428 ConstantRange::makeAllowedICmpRegion(Pred, CI->getValue());
1429 ConstantRange DominatingCR =
1430 (Parent == TrueBB)
1431 ? ConstantRange::makeExactICmpRegion(Pred2, CI2->getValue())
1432 : ConstantRange::makeExactICmpRegion(
1433 CmpInst::getInversePredicate(Pred2), CI2->getValue());
1434 ConstantRange Intersection = DominatingCR.intersectWith(CR);
1435 ConstantRange Difference = DominatingCR.difference(CR);
1436 if (Intersection.isEmptySet())
1437 return replaceInstUsesWith(Cmp, Builder->getFalse());
1438 if (Difference.isEmptySet())
1439 return replaceInstUsesWith(Cmp, Builder->getTrue());
1440
1441 // If this is a normal comparison, it demands all bits. If it is a sign
1442 // bit comparison, it only demands the sign bit.
1443 bool UnusedBit;
1444 bool IsSignBit = isSignBitCheck(Pred, CI->getValue(), UnusedBit);
1445
1446 // Canonicalizing a sign bit comparison that gets used in a branch,
1447 // pessimizes codegen by generating branch on zero instruction instead
1448 // of a test and branch. So we avoid canonicalizing in such situations
1449 // because test and branch instruction has better branch displacement
1450 // than compare and branch instruction.
1451 if (!isBranchOnSignBitCheck(Cmp, IsSignBit) && !Cmp.isEquality()) {
1452 if (auto *AI = Intersection.getSingleElement())
1453 return new ICmpInst(ICmpInst::ICMP_EQ, X, Builder->getInt(*AI));
1454 if (auto *AD = Difference.getSingleElement())
1455 return new ICmpInst(ICmpInst::ICMP_NE, X, Builder->getInt(*AD));
1456 }
1457 }
1458
1459 return nullptr;
1460}
1461
1462/// Fold icmp (trunc X, Y), C.
1463Instruction *InstCombiner::foldICmpTruncConstant(ICmpInst &Cmp,
1464 Instruction *Trunc,
1465 const APInt *C) {
1466 ICmpInst::Predicate Pred = Cmp.getPredicate();
1467 Value *X = Trunc->getOperand(0);
1468 if (C->isOneValue() && C->getBitWidth() > 1) {
1469 // icmp slt trunc(signum(V)) 1 --> icmp slt V, 1
1470 Value *V = nullptr;
1471 if (Pred == ICmpInst::ICMP_SLT && match(X, m_Signum(m_Value(V))))
1472 return new ICmpInst(ICmpInst::ICMP_SLT, V,
1473 ConstantInt::get(V->getType(), 1));
1474 }
1475
1476 if (Cmp.isEquality() && Trunc->hasOneUse()) {
1477 // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
1478 // of the high bits truncated out of x are known.
1479 unsigned DstBits = Trunc->getType()->getScalarSizeInBits(),
1480 SrcBits = X->getType()->getScalarSizeInBits();
1481 KnownBits Known = computeKnownBits(X, 0, &Cmp);
1482
1483 // If all the high bits are known, we can do this xform.
1484 if ((Known.Zero | Known.One).countLeadingOnes() >= SrcBits - DstBits) {
1485 // Pull in the high bits from known-ones set.
1486 APInt NewRHS = C->zext(SrcBits);
1487 NewRHS |= Known.One & APInt::getHighBitsSet(SrcBits, SrcBits - DstBits);
1488 return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), NewRHS));
1489 }
1490 }
1491
1492 return nullptr;
1493}
1494
1495/// Fold icmp (xor X, Y), C.
1496Instruction *InstCombiner::foldICmpXorConstant(ICmpInst &Cmp,
1497 BinaryOperator *Xor,
1498 const APInt *C) {
1499 Value *X = Xor->getOperand(0);
1500 Value *Y = Xor->getOperand(1);
1501 const APInt *XorC;
1502 if (!match(Y, m_APInt(XorC)))
1503 return nullptr;
1504
1505 // If this is a comparison that tests the signbit (X < 0) or (x > -1),
1506 // fold the xor.
1507 ICmpInst::Predicate Pred = Cmp.getPredicate();
1508 if ((Pred == ICmpInst::ICMP_SLT && C->isNullValue()) ||
1509 (Pred == ICmpInst::ICMP_SGT && C->isAllOnesValue())) {
1510
1511 // If the sign bit of the XorCst is not set, there is no change to
1512 // the operation, just stop using the Xor.
1513 if (!XorC->isNegative()) {
1514 Cmp.setOperand(0, X);
1515 Worklist.Add(Xor);
1516 return &Cmp;
1517 }
1518
1519 // Was the old condition true if the operand is positive?
1520 bool isTrueIfPositive = Pred == ICmpInst::ICMP_SGT;
1521
1522 // If so, the new one isn't.
1523 isTrueIfPositive ^= true;
1524
1525 Constant *CmpConstant = cast<Constant>(Cmp.getOperand(1));
1526 if (isTrueIfPositive)
1527 return new ICmpInst(ICmpInst::ICMP_SGT, X, SubOne(CmpConstant));
1528 else
1529 return new ICmpInst(ICmpInst::ICMP_SLT, X, AddOne(CmpConstant));
1530 }
1531
1532 if (Xor->hasOneUse()) {
1533 // (icmp u/s (xor X SignMask), C) -> (icmp s/u X, (xor C SignMask))
1534 if (!Cmp.isEquality() && XorC->isSignMask()) {
1535 Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
1536 : Cmp.getSignedPredicate();
1537 return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), *C ^ *XorC));
1538 }
1539
1540 // (icmp u/s (xor X ~SignMask), C) -> (icmp s/u X, (xor C ~SignMask))
1541 if (!Cmp.isEquality() && XorC->isMaxSignedValue()) {
1542 Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
1543 : Cmp.getSignedPredicate();
1544 Pred = Cmp.getSwappedPredicate(Pred);
1545 return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), *C ^ *XorC));
1546 }
1547 }
1548
1549 // (icmp ugt (xor X, C), ~C) -> (icmp ult X, C)
1550 // iff -C is a power of 2
1551 if (Pred == ICmpInst::ICMP_UGT && *XorC == ~(*C) && (*C + 1).isPowerOf2())
1552 return new ICmpInst(ICmpInst::ICMP_ULT, X, Y);
1553
1554 // (icmp ult (xor X, C), -C) -> (icmp uge X, C)
1555 // iff -C is a power of 2
1556 if (Pred == ICmpInst::ICMP_ULT && *XorC == -(*C) && C->isPowerOf2())
1557 return new ICmpInst(ICmpInst::ICMP_UGE, X, Y);
1558
1559 return nullptr;
1560}
1561
1562/// Fold icmp (and (sh X, Y), C2), C1.
1563Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And,
1564 const APInt *C1, const APInt *C2) {
1565 BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0));
1566 if (!Shift || !Shift->isShift())
1567 return nullptr;
1568
1569 // If this is: (X >> C3) & C2 != C1 (where any shift and any compare could
1570 // exist), turn it into (X & (C2 << C3)) != (C1 << C3). This happens a LOT in
1571 // code produced by the clang front-end, for bitfield access.
1572 // This seemingly simple opportunity to fold away a shift turns out to be
1573 // rather complicated. See PR17827 for details.
1574 unsigned ShiftOpcode = Shift->getOpcode();
1575 bool IsShl = ShiftOpcode == Instruction::Shl;
1576 const APInt *C3;
1577 if (match(Shift->getOperand(1), m_APInt(C3))) {
1578 bool CanFold = false;
1579 if (ShiftOpcode == Instruction::AShr) {
1580 // There may be some constraints that make this possible, but nothing
1581 // simple has been discovered yet.
1582 CanFold = false;
1583 } else if (ShiftOpcode == Instruction::Shl) {
1584 // For a left shift, we can fold if the comparison is not signed. We can
1585 // also fold a signed comparison if the mask value and comparison value
1586 // are not negative. These constraints may not be obvious, but we can
1587 // prove that they are correct using an SMT solver.
1588 if (!Cmp.isSigned() || (!C2->isNegative() && !C1->isNegative()))
1589 CanFold = true;
1590 } else if (ShiftOpcode == Instruction::LShr) {
1591 // For a logical right shift, we can fold if the comparison is not signed.
1592 // We can also fold a signed comparison if the shifted mask value and the
1593 // shifted comparison value are not negative. These constraints may not be
1594 // obvious, but we can prove that they are correct using an SMT solver.
1595 if (!Cmp.isSigned() ||
1596 (!C2->shl(*C3).isNegative() && !C1->shl(*C3).isNegative()))
1597 CanFold = true;
1598 }
1599
1600 if (CanFold) {
1601 APInt NewCst = IsShl ? C1->lshr(*C3) : C1->shl(*C3);
1602 APInt SameAsC1 = IsShl ? NewCst.shl(*C3) : NewCst.lshr(*C3);
1603 // Check to see if we are shifting out any of the bits being compared.
1604 if (SameAsC1 != *C1) {
1605 // If we shifted bits out, the fold is not going to work out. As a
1606 // special case, check to see if this means that the result is always
1607 // true or false now.
1608 if (Cmp.getPredicate() == ICmpInst::ICMP_EQ)
1609 return replaceInstUsesWith(Cmp, ConstantInt::getFalse(Cmp.getType()));
1610 if (Cmp.getPredicate() == ICmpInst::ICMP_NE)
1611 return replaceInstUsesWith(Cmp, ConstantInt::getTrue(Cmp.getType()));
1612 } else {
1613 Cmp.setOperand(1, ConstantInt::get(And->getType(), NewCst));
1614 APInt NewAndCst = IsShl ? C2->lshr(*C3) : C2->shl(*C3);
1615 And->setOperand(1, ConstantInt::get(And->getType(), NewAndCst));
1616 And->setOperand(0, Shift->getOperand(0));
1617 Worklist.Add(Shift); // Shift is dead.
1618 return &Cmp;
1619 }
1620 }
1621 }
1622
1623 // Turn ((X >> Y) & C2) == 0 into (X & (C2 << Y)) == 0. The latter is
1624 // preferable because it allows the C2 << Y expression to be hoisted out of a
1625 // loop if Y is invariant and X is not.
1626 if (Shift->hasOneUse() && C1->isNullValue() && Cmp.isEquality() &&
1627 !Shift->isArithmeticShift() && !isa<Constant>(Shift->getOperand(0))) {
1628 // Compute C2 << Y.
1629 Value *NewShift =
1630 IsShl ? Builder->CreateLShr(And->getOperand(1), Shift->getOperand(1))
1631 : Builder->CreateShl(And->getOperand(1), Shift->getOperand(1));
1632
1633 // Compute X & (C2 << Y).
1634 Value *NewAnd = Builder->CreateAnd(Shift->getOperand(0), NewShift);
1635 Cmp.setOperand(0, NewAnd);
1636 return &Cmp;
1637 }
1638
1639 return nullptr;
1640}
1641
1642/// Fold icmp (and X, C2), C1.
1643Instruction *InstCombiner::foldICmpAndConstConst(ICmpInst &Cmp,
1644 BinaryOperator *And,
1645 const APInt *C1) {
1646 const APInt *C2;
1647 if (!match(And->getOperand(1), m_APInt(C2)))
1648 return nullptr;
1649
1650 if (!And->hasOneUse() || !And->getOperand(0)->hasOneUse())
1651 return nullptr;
1652
1653 // If the LHS is an 'and' of a truncate and we can widen the and/compare to
1654 // the input width without changing the value produced, eliminate the cast:
1655 //
1656 // icmp (and (trunc W), C2), C1 -> icmp (and W, C2'), C1'
1657 //
1658 // We can do this transformation if the constants do not have their sign bits
1659 // set or if it is an equality comparison. Extending a relational comparison
1660 // when we're checking the sign bit would not work.
1661 Value *W;
1662 if (match(And->getOperand(0), m_Trunc(m_Value(W))) &&
1663 (Cmp.isEquality() || (!C1->isNegative() && !C2->isNegative()))) {
1664 // TODO: Is this a good transform for vectors? Wider types may reduce
1665 // throughput. Should this transform be limited (even for scalars) by using
1666 // shouldChangeType()?
1667 if (!Cmp.getType()->isVectorTy()) {
1668 Type *WideType = W->getType();
1669 unsigned WideScalarBits = WideType->getScalarSizeInBits();
1670 Constant *ZextC1 = ConstantInt::get(WideType, C1->zext(WideScalarBits));
1671 Constant *ZextC2 = ConstantInt::get(WideType, C2->zext(WideScalarBits));
1672 Value *NewAnd = Builder->CreateAnd(W, ZextC2, And->getName());
1673 return new ICmpInst(Cmp.getPredicate(), NewAnd, ZextC1);
1674 }
1675 }
1676
1677 if (Instruction *I = foldICmpAndShift(Cmp, And, C1, C2))
1678 return I;
1679
1680 // (icmp pred (and (or (lshr A, B), A), 1), 0) -->
1681 // (icmp pred (and A, (or (shl 1, B), 1), 0))
1682 //
1683 // iff pred isn't signed
1684 if (!Cmp.isSigned() && C1->isNullValue() &&
1685 match(And->getOperand(1), m_One())) {
1686 Constant *One = cast<Constant>(And->getOperand(1));
1687 Value *Or = And->getOperand(0);
1688 Value *A, *B, *LShr;
1689 if (match(Or, m_Or(m_Value(LShr), m_Value(A))) &&
1690 match(LShr, m_LShr(m_Specific(A), m_Value(B)))) {
1691 unsigned UsesRemoved = 0;
1692 if (And->hasOneUse())
1693 ++UsesRemoved;
1694 if (Or->hasOneUse())
1695 ++UsesRemoved;
1696 if (LShr->hasOneUse())
1697 ++UsesRemoved;
1698
1699 // Compute A & ((1 << B) | 1)
1700 Value *NewOr = nullptr;
1701 if (auto *C = dyn_cast<Constant>(B)) {
1702 if (UsesRemoved >= 1)
1703 NewOr = ConstantExpr::getOr(ConstantExpr::getNUWShl(One, C), One);
1704 } else {
1705 if (UsesRemoved >= 3)
1706 NewOr = Builder->CreateOr(Builder->CreateShl(One, B, LShr->getName(),
1707 /*HasNUW=*/true),
1708 One, Or->getName());
1709 }
1710 if (NewOr) {
1711 Value *NewAnd = Builder->CreateAnd(A, NewOr, And->getName());
1712 Cmp.setOperand(0, NewAnd);
1713 return &Cmp;
1714 }
1715 }
1716 }
1717
1718 // (X & C2) > C1 --> (X & C2) != 0, if any bit set in (X & C2) will produce a
1719 // result greater than C1.
1720 unsigned NumTZ = C2->countTrailingZeros();
1721 if (Cmp.getPredicate() == ICmpInst::ICMP_UGT && NumTZ < C2->getBitWidth() &&
1722 APInt::getOneBitSet(C2->getBitWidth(), NumTZ).ugt(*C1)) {
1723 Constant *Zero = Constant::getNullValue(And->getType());
1724 return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
1725 }
1726
1727 return nullptr;
1728}
1729
1730/// Fold icmp (and X, Y), C.
1731Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &Cmp,
1732 BinaryOperator *And,
1733 const APInt *C) {
1734 if (Instruction *I = foldICmpAndConstConst(Cmp, And, C))
1735 return I;
1736
1737 // TODO: These all require that Y is constant too, so refactor with the above.
1738
1739 // Try to optimize things like "A[i] & 42 == 0" to index computations.
1740 Value *X = And->getOperand(0);
1741 Value *Y = And->getOperand(1);
1742 if (auto *LI = dyn_cast<LoadInst>(X))
1743 if (auto *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
1744 if (auto *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
1745 if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
1746 !LI->isVolatile() && isa<ConstantInt>(Y)) {
1747 ConstantInt *C2 = cast<ConstantInt>(Y);
1748 if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, Cmp, C2))
1749 return Res;
1750 }
1751
1752 if (!Cmp.isEquality())
1753 return nullptr;
1754
1755 // X & -C == -C -> X > u ~C
1756 // X & -C != -C -> X <= u ~C
1757 // iff C is a power of 2
1758 if (Cmp.getOperand(1) == Y && (-(*C)).isPowerOf2()) {
1759 auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGT
1760 : CmpInst::ICMP_ULE;
1761 return new ICmpInst(NewPred, X, SubOne(cast<Constant>(Cmp.getOperand(1))));
1762 }
1763
1764 // (X & C2) == 0 -> (trunc X) >= 0
1765 // (X & C2) != 0 -> (trunc X) < 0
1766 // iff C2 is a power of 2 and it masks the sign bit of a legal integer type.
1767 const APInt *C2;
1768 if (And->hasOneUse() && C->isNullValue() && match(Y, m_APInt(C2))) {
1769 int32_t ExactLogBase2 = C2->exactLogBase2();
1770 if (ExactLogBase2 != -1 && DL.isLegalInteger(ExactLogBase2 + 1)) {
1771 Type *NTy = IntegerType::get(Cmp.getContext(), ExactLogBase2 + 1);
1772 if (And->getType()->isVectorTy())
1773 NTy = VectorType::get(NTy, And->getType()->getVectorNumElements());
1774 Value *Trunc = Builder->CreateTrunc(X, NTy);
1775 auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_SGE
1776 : CmpInst::ICMP_SLT;
1777 return new ICmpInst(NewPred, Trunc, Constant::getNullValue(NTy));
1778 }
1779 }
1780
1781 return nullptr;
1782}
1783
1784/// Fold icmp (or X, Y), C.
1785Instruction *InstCombiner::foldICmpOrConstant(ICmpInst &Cmp, BinaryOperator *Or,
1786 const APInt *C) {
1787 ICmpInst::Predicate Pred = Cmp.getPredicate();
1788 if (C->isOneValue()) {
1789 // icmp slt signum(V) 1 --> icmp slt V, 1
1790 Value *V = nullptr;
1791 if (Pred == ICmpInst::ICMP_SLT && match(Or, m_Signum(m_Value(V))))
1792 return new ICmpInst(ICmpInst::ICMP_SLT, V,
1793 ConstantInt::get(V->getType(), 1));
1794 }
1795
1796 // X | C == C --> X <=u C
1797 // X | C != C --> X >u C
1798 // iff C+1 is a power of 2 (C is a bitmask of the low bits)
1799 if (Cmp.isEquality() && Cmp.getOperand(1) == Or->getOperand(1) &&
1800 (*C + 1).isPowerOf2()) {
1801 Pred = (Pred == CmpInst::ICMP_EQ) ? CmpInst::ICMP_ULE : CmpInst::ICMP_UGT;
1802 return new ICmpInst(Pred, Or->getOperand(0), Or->getOperand(1));
1803 }
1804
1805 if (!Cmp.isEquality() || !C->isNullValue() || !Or->hasOneUse())
1806 return nullptr;
1807
1808 Value *P, *Q;
1809 if (match(Or, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
1810 // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
1811 // -> and (icmp eq P, null), (icmp eq Q, null).
1812 Value *CmpP =
1813 Builder->CreateICmp(Pred, P, ConstantInt::getNullValue(P->getType()));
1814 Value *CmpQ =
1815 Builder->CreateICmp(Pred, Q, ConstantInt::getNullValue(Q->getType()));
1816 auto LogicOpc = Pred == ICmpInst::Predicate::ICMP_EQ ? Instruction::And
1817 : Instruction::Or;
1818 return BinaryOperator::Create(LogicOpc, CmpP, CmpQ);
1819 }
1820
1821 return nullptr;
1822}
1823
1824/// Fold icmp (mul X, Y), C.
1825Instruction *InstCombiner::foldICmpMulConstant(ICmpInst &Cmp,
1826 BinaryOperator *Mul,
1827 const APInt *C) {
1828 const APInt *MulC;
1829 if (!match(Mul->getOperand(1), m_APInt(MulC)))
1830 return nullptr;
1831
1832 // If this is a test of the sign bit and the multiply is sign-preserving with
1833 // a constant operand, use the multiply LHS operand instead.
1834 ICmpInst::Predicate Pred = Cmp.getPredicate();
1835 if (isSignTest(Pred, *C) && Mul->hasNoSignedWrap()) {
1836 if (MulC->isNegative())
1837 Pred = ICmpInst::getSwappedPredicate(Pred);
1838 return new ICmpInst(Pred, Mul->getOperand(0),
1839 Constant::getNullValue(Mul->getType()));
1840 }
1841
1842 return nullptr;
1843}
1844
1845/// Fold icmp (shl 1, Y), C.
1846static Instruction *foldICmpShlOne(ICmpInst &Cmp, Instruction *Shl,
1847 const APInt *C) {
1848 Value *Y;
1849 if (!match(Shl, m_Shl(m_One(), m_Value(Y))))
1850 return nullptr;
1851
1852 Type *ShiftType = Shl->getType();
1853 uint32_t TypeBits = C->getBitWidth();
1854 bool CIsPowerOf2 = C->isPowerOf2();
1855 ICmpInst::Predicate Pred = Cmp.getPredicate();
1856 if (Cmp.isUnsigned()) {
1857 // (1 << Y) pred C -> Y pred Log2(C)
1858 if (!CIsPowerOf2) {
1859 // (1 << Y) < 30 -> Y <= 4
1860 // (1 << Y) <= 30 -> Y <= 4
1861 // (1 << Y) >= 30 -> Y > 4
1862 // (1 << Y) > 30 -> Y > 4
1863 if (Pred == ICmpInst::ICMP_ULT)
1864 Pred = ICmpInst::ICMP_ULE;
1865 else if (Pred == ICmpInst::ICMP_UGE)
1866 Pred = ICmpInst::ICMP_UGT;
1867 }
1868
1869 // (1 << Y) >= 2147483648 -> Y >= 31 -> Y == 31
1870 // (1 << Y) < 2147483648 -> Y < 31 -> Y != 31
1871 unsigned CLog2 = C->logBase2();
1872 if (CLog2 == TypeBits - 1) {
1873 if (Pred == ICmpInst::ICMP_UGE)
1874 Pred = ICmpInst::ICMP_EQ;
1875 else if (Pred == ICmpInst::ICMP_ULT)
1876 Pred = ICmpInst::ICMP_NE;
1877 }
1878 return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, CLog2));
1879 } else if (Cmp.isSigned()) {
1880 Constant *BitWidthMinusOne = ConstantInt::get(ShiftType, TypeBits - 1);
1881 if (C->isAllOnesValue()) {
1882 // (1 << Y) <= -1 -> Y == 31
1883 if (Pred == ICmpInst::ICMP_SLE)
1884 return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne);
1885
1886 // (1 << Y) > -1 -> Y != 31
1887 if (Pred == ICmpInst::ICMP_SGT)
1888 return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne);
1889 } else if (!(*C)) {
1890 // (1 << Y) < 0 -> Y == 31
1891 // (1 << Y) <= 0 -> Y == 31
1892 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
1893 return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne);
1894
1895 // (1 << Y) >= 0 -> Y != 31
1896 // (1 << Y) > 0 -> Y != 31
1897 if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)
1898 return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne);
1899 }
1900 } else if (Cmp.isEquality() && CIsPowerOf2) {
1901 return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, C->logBase2()));
1902 }
1903
1904 return nullptr;
1905}
1906
1907/// Fold icmp (shl X, Y), C.
1908Instruction *InstCombiner::foldICmpShlConstant(ICmpInst &Cmp,
1909 BinaryOperator *Shl,
1910 const APInt *C) {
1911 const APInt *ShiftVal;
1912 if (Cmp.isEquality() && match(Shl->getOperand(0), m_APInt(ShiftVal)))
1913 return foldICmpShlConstConst(Cmp, Shl->getOperand(1), *C, *ShiftVal);
1914
1915 const APInt *ShiftAmt;
1916 if (!match(Shl->getOperand(1), m_APInt(ShiftAmt)))
1917 return foldICmpShlOne(Cmp, Shl, C);
1918
1919 // Check that the shift amount is in range. If not, don't perform undefined
1920 // shifts. When the shift is visited, it will be simplified.
1921 unsigned TypeBits = C->getBitWidth();
1922 if (ShiftAmt->uge(TypeBits))
1923 return nullptr;
1924
1925 ICmpInst::Predicate Pred = Cmp.getPredicate();
1926 Value *X = Shl->getOperand(0);
1927 Type *ShType = Shl->getType();
1928
1929 // NSW guarantees that we are only shifting out sign bits from the high bits,
1930 // so we can ASHR the compare constant without needing a mask and eliminate
1931 // the shift.
1932 if (Shl->hasNoSignedWrap()) {
1933 if (Pred == ICmpInst::ICMP_SGT) {
1934 // icmp Pred (shl nsw X, ShiftAmt), C --> icmp Pred X, (C >>s ShiftAmt)
1935 APInt ShiftedC = C->ashr(*ShiftAmt);
1936 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
1937 }
1938 if (Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) {
1939 // This is the same code as the SGT case, but assert the pre-condition
1940 // that is needed for this to work with equality predicates.
1941 assert(C->ashr(*ShiftAmt).shl(*ShiftAmt) == *C &&((C->ashr(*ShiftAmt).shl(*ShiftAmt) == *C && "Compare known true or false was not folded"
) ? static_cast<void> (0) : __assert_fail ("C->ashr(*ShiftAmt).shl(*ShiftAmt) == *C && \"Compare known true or false was not folded\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1942, __PRETTY_FUNCTION__))
1942 "Compare known true or false was not folded")((C->ashr(*ShiftAmt).shl(*ShiftAmt) == *C && "Compare known true or false was not folded"
) ? static_cast<void> (0) : __assert_fail ("C->ashr(*ShiftAmt).shl(*ShiftAmt) == *C && \"Compare known true or false was not folded\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1942, __PRETTY_FUNCTION__));
1943 APInt ShiftedC = C->ashr(*ShiftAmt);
1944 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
1945 }
1946 if (Pred == ICmpInst::ICMP_SLT) {
1947 // SLE is the same as above, but SLE is canonicalized to SLT, so convert:
1948 // (X << S) <=s C is equiv to X <=s (C >> S) for all C
1949 // (X << S) <s (C + 1) is equiv to X <s (C >> S) + 1 if C <s SMAX
1950 // (X << S) <s C is equiv to X <s ((C - 1) >> S) + 1 if C >s SMIN
1951 assert(!C->isMinSignedValue() && "Unexpected icmp slt")((!C->isMinSignedValue() && "Unexpected icmp slt")
? static_cast<void> (0) : __assert_fail ("!C->isMinSignedValue() && \"Unexpected icmp slt\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1951, __PRETTY_FUNCTION__));
1952 APInt ShiftedC = (*C - 1).ashr(*ShiftAmt) + 1;
1953 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
1954 }
1955 // If this is a signed comparison to 0 and the shift is sign preserving,
1956 // use the shift LHS operand instead; isSignTest may change 'Pred', so only
1957 // do that if we're sure to not continue on in this function.
1958 if (isSignTest(Pred, *C))
1959 return new ICmpInst(Pred, X, Constant::getNullValue(ShType));
1960 }
1961
1962 // NUW guarantees that we are only shifting out zero bits from the high bits,
1963 // so we can LSHR the compare constant without needing a mask and eliminate
1964 // the shift.
1965 if (Shl->hasNoUnsignedWrap()) {
1966 if (Pred == ICmpInst::ICMP_UGT) {
1967 // icmp Pred (shl nuw X, ShiftAmt), C --> icmp Pred X, (C >>u ShiftAmt)
1968 APInt ShiftedC = C->lshr(*ShiftAmt);
1969 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
1970 }
1971 if (Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) {
1972 // This is the same code as the UGT case, but assert the pre-condition
1973 // that is needed for this to work with equality predicates.
1974 assert(C->lshr(*ShiftAmt).shl(*ShiftAmt) == *C &&((C->lshr(*ShiftAmt).shl(*ShiftAmt) == *C && "Compare known true or false was not folded"
) ? static_cast<void> (0) : __assert_fail ("C->lshr(*ShiftAmt).shl(*ShiftAmt) == *C && \"Compare known true or false was not folded\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1975, __PRETTY_FUNCTION__))
1975 "Compare known true or false was not folded")((C->lshr(*ShiftAmt).shl(*ShiftAmt) == *C && "Compare known true or false was not folded"
) ? static_cast<void> (0) : __assert_fail ("C->lshr(*ShiftAmt).shl(*ShiftAmt) == *C && \"Compare known true or false was not folded\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1975, __PRETTY_FUNCTION__));
1976 APInt ShiftedC = C->lshr(*ShiftAmt);
1977 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
1978 }
1979 if (Pred == ICmpInst::ICMP_ULT) {
1980 // ULE is the same as above, but ULE is canonicalized to ULT, so convert:
1981 // (X << S) <=u C is equiv to X <=u (C >> S) for all C
1982 // (X << S) <u (C + 1) is equiv to X <u (C >> S) + 1 if C <u ~0u
1983 // (X << S) <u C is equiv to X <u ((C - 1) >> S) + 1 if C >u 0
1984 assert(C->ugt(0) && "ult 0 should have been eliminated")((C->ugt(0) && "ult 0 should have been eliminated"
) ? static_cast<void> (0) : __assert_fail ("C->ugt(0) && \"ult 0 should have been eliminated\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1984, __PRETTY_FUNCTION__));
1985 APInt ShiftedC = (*C - 1).lshr(*ShiftAmt) + 1;
1986 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
1987 }
1988 }
1989
1990 if (Cmp.isEquality() && Shl->hasOneUse()) {
1991 // Strength-reduce the shift into an 'and'.
1992 Constant *Mask = ConstantInt::get(
1993 ShType,
1994 APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt->getZExtValue()));
1995 Value *And = Builder->CreateAnd(X, Mask, Shl->getName() + ".mask");
1996 Constant *LShrC = ConstantInt::get(ShType, C->lshr(*ShiftAmt));
1997 return new ICmpInst(Pred, And, LShrC);
1998 }
1999
2000 // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
2001 bool TrueIfSigned = false;
2002 if (Shl->hasOneUse() && isSignBitCheck(Pred, *C, TrueIfSigned)) {
2003 // (X << 31) <s 0 --> (X & 1) != 0
2004 Constant *Mask = ConstantInt::get(
2005 ShType,
2006 APInt::getOneBitSet(TypeBits, TypeBits - ShiftAmt->getZExtValue() - 1));
2007 Value *And = Builder->CreateAnd(X, Mask, Shl->getName() + ".mask");
2008 return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
2009 And, Constant::getNullValue(ShType));
2010 }
2011
2012 // Transform (icmp pred iM (shl iM %v, N), C)
2013 // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (C>>N))
2014 // Transform the shl to a trunc if (trunc (C>>N)) has no loss and M-N.
2015 // This enables us to get rid of the shift in favor of a trunc that may be
2016 // free on the target. It has the additional benefit of comparing to a
2017 // smaller constant that may be more target-friendly.
2018 unsigned Amt = ShiftAmt->getLimitedValue(TypeBits - 1);
2019 if (Shl->hasOneUse() && Amt != 0 && C->countTrailingZeros() >= Amt &&
2020 DL.isLegalInteger(TypeBits - Amt)) {
2021 Type *TruncTy = IntegerType::get(Cmp.getContext(), TypeBits - Amt);
2022 if (ShType->isVectorTy())
2023 TruncTy = VectorType::get(TruncTy, ShType->getVectorNumElements());
2024 Constant *NewC =
2025 ConstantInt::get(TruncTy, C->ashr(*ShiftAmt).trunc(TypeBits - Amt));
2026 return new ICmpInst(Pred, Builder->CreateTrunc(X, TruncTy), NewC);
2027 }
2028
2029 return nullptr;
2030}
2031
2032/// Fold icmp ({al}shr X, Y), C.
2033Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &Cmp,
2034 BinaryOperator *Shr,
2035 const APInt *C) {
2036 // An exact shr only shifts out zero bits, so:
2037 // icmp eq/ne (shr X, Y), 0 --> icmp eq/ne X, 0
2038 Value *X = Shr->getOperand(0);
2039 CmpInst::Predicate Pred = Cmp.getPredicate();
2040 if (Cmp.isEquality() && Shr->isExact() && Shr->hasOneUse() &&
2041 C->isNullValue())
2042 return new ICmpInst(Pred, X, Cmp.getOperand(1));
2043
2044 const APInt *ShiftVal;
2045 if (Cmp.isEquality() && match(Shr->getOperand(0), m_APInt(ShiftVal)))
1
Taking false branch
→
2046 return foldICmpShrConstConst(Cmp, Shr->getOperand(1), *C, *ShiftVal);
2047
2048 const APInt *ShiftAmt;
2049 if (!match(Shr->getOperand(1), m_APInt(ShiftAmt)))
2
←
Taking false branch
→
2050 return nullptr;
2051
2052 // Check that the shift amount is in range. If not, don't perform undefined
2053 // shifts. When the shift is visited it will be simplified.
2054 unsigned TypeBits = C->getBitWidth();
2055 unsigned ShAmtVal = ShiftAmt->getLimitedValue(TypeBits);
2056 if (ShAmtVal >= TypeBits || ShAmtVal == 0)
3
←
Assuming 'ShAmtVal' is not equal to 0
→
4
←
Taking false branch
→
2057 return nullptr;
2058
2059 bool IsAShr = Shr->getOpcode() == Instruction::AShr;
5
←
Assuming the condition is false
→
2060 if (!Cmp.isEquality()) {
6
←
Taking true branch
→
2061 // If we have an unsigned comparison and an ashr, we can't simplify this.
2062 // Similarly for signed comparisons with lshr.
2063 if (Cmp.isSigned() != IsAShr)
7
←
Assuming the condition is false
→
8
←
Taking false branch
→
2064 return nullptr;
2065
2066 // Otherwise, all lshr and most exact ashr's are equivalent to a udiv/sdiv
2067 // by a power of 2. Since we already have logic to simplify these,
2068 // transform to div and then simplify the resultant comparison.
2069 if (IsAShr && (!Shr->isExact() || ShAmtVal == TypeBits - 1))
2070 return nullptr;
2071
2072 // Revisit the shift (to delete it).
2073 Worklist.Add(Shr);
2074
2075 Constant *DivCst = ConstantInt::get(
2076 Shr->getType(), APInt::getOneBitSet(TypeBits, ShAmtVal));
2077
2078 Value *Tmp = IsAShr ? Builder->CreateSDiv(X, DivCst, "", Shr->isExact())
9
←
'?' condition is false
→
2079 : Builder->CreateUDiv(X, DivCst, "", Shr->isExact());
2080
2081 Cmp.setOperand(0, Tmp);
2082
2083 // If the builder folded the binop, just return it.
2084 BinaryOperator *TheDiv = dyn_cast<BinaryOperator>(Tmp);
2085 if (!TheDiv)
10
←
Taking false branch
→
2086 return &Cmp;
2087
2088 // Otherwise, fold this div/compare.
2089 assert(TheDiv->getOpcode() == Instruction::SDiv ||((TheDiv->getOpcode() == Instruction::SDiv || TheDiv->getOpcode
() == Instruction::UDiv) ? static_cast<void> (0) : __assert_fail
("TheDiv->getOpcode() == Instruction::SDiv || TheDiv->getOpcode() == Instruction::UDiv"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2090, __PRETTY_FUNCTION__))
2090 TheDiv->getOpcode() == Instruction::UDiv)((TheDiv->getOpcode() == Instruction::SDiv || TheDiv->getOpcode
() == Instruction::UDiv) ? static_cast<void> (0) : __assert_fail
("TheDiv->getOpcode() == Instruction::SDiv || TheDiv->getOpcode() == Instruction::UDiv"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2090, __PRETTY_FUNCTION__));
2091
2092 Instruction *Res = foldICmpDivConstant(Cmp, TheDiv, C);
11
←
Calling 'InstCombiner::foldICmpDivConstant'
→
2093 assert(Res && "This div/cst should have folded!")((Res && "This div/cst should have folded!") ? static_cast
<void> (0) : __assert_fail ("Res && \"This div/cst should have folded!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2093, __PRETTY_FUNCTION__));
2094 return Res;
2095 }
2096
2097 // Handle equality comparisons of shift-by-constant.
2098
2099 // If the comparison constant changes with the shift, the comparison cannot
2100 // succeed (bits of the comparison constant cannot match the shifted value).
2101 // This should be known by InstSimplify and already be folded to true/false.
2102 assert(((IsAShr && C->shl(ShAmtVal).ashr(ShAmtVal) == *C) ||((((IsAShr && C->shl(ShAmtVal).ashr(ShAmtVal) == *
C) || (!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) ==
*C)) && "Expected icmp+shr simplify did not occur.")
? static_cast<void> (0) : __assert_fail ("((IsAShr && C->shl(ShAmtVal).ashr(ShAmtVal) == *C) || (!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) == *C)) && \"Expected icmp+shr simplify did not occur.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2104, __PRETTY_FUNCTION__))
2103 (!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) == *C)) &&((((IsAShr && C->shl(ShAmtVal).ashr(ShAmtVal) == *
C) || (!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) ==
*C)) && "Expected icmp+shr simplify did not occur.")
? static_cast<void> (0) : __assert_fail ("((IsAShr && C->shl(ShAmtVal).ashr(ShAmtVal) == *C) || (!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) == *C)) && \"Expected icmp+shr simplify did not occur.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2104, __PRETTY_FUNCTION__))
2104 "Expected icmp+shr simplify did not occur.")((((IsAShr && C->shl(ShAmtVal).ashr(ShAmtVal) == *
C) || (!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) ==
*C)) && "Expected icmp+shr simplify did not occur.")
? static_cast<void> (0) : __assert_fail ("((IsAShr && C->shl(ShAmtVal).ashr(ShAmtVal) == *C) || (!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) == *C)) && \"Expected icmp+shr simplify did not occur.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2104, __PRETTY_FUNCTION__));
2105
2106 // Check if the bits shifted out are known to be zero. If so, we can compare
2107 // against the unshifted value:
2108 // (X & 4) >> 1 == 2 --> (X & 4) == 4.
2109 Constant *ShiftedCmpRHS = ConstantInt::get(Shr->getType(), *C << ShAmtVal);
2110 if (Shr->hasOneUse()) {
2111 if (Shr->isExact())
2112 return new ICmpInst(Pred, X, ShiftedCmpRHS);
2113
2114 // Otherwise strength reduce the shift into an 'and'.
2115 APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
2116 Constant *Mask = ConstantInt::get(Shr->getType(), Val);
2117 Value *And = Builder->CreateAnd(X, Mask, Shr->getName() + ".mask");
2118 return new ICmpInst(Pred, And, ShiftedCmpRHS);
2119 }
2120
2121 return nullptr;
2122}
2123
2124/// Fold icmp (udiv X, Y), C.
2125Instruction *InstCombiner::foldICmpUDivConstant(ICmpInst &Cmp,
2126 BinaryOperator *UDiv,
2127 const APInt *C) {
2128 const APInt *C2;
2129 if (!match(UDiv->getOperand(0), m_APInt(C2)))
2130 return nullptr;
2131
2132 assert(*C2 != 0 && "udiv 0, X should have been simplified already.")((*C2 != 0 && "udiv 0, X should have been simplified already."
) ? static_cast<void> (0) : __assert_fail ("*C2 != 0 && \"udiv 0, X should have been simplified already.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2132, __PRETTY_FUNCTION__));
2133
2134 // (icmp ugt (udiv C2, Y), C) -> (icmp ule Y, C2/(C+1))
2135 Value *Y = UDiv->getOperand(1);
2136 if (Cmp.getPredicate() == ICmpInst::ICMP_UGT) {
2137 assert(!C->isMaxValue() &&((!C->isMaxValue() && "icmp ugt X, UINT_MAX should have been simplified already."
) ? static_cast<void> (0) : __assert_fail ("!C->isMaxValue() && \"icmp ugt X, UINT_MAX should have been simplified already.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2138, __PRETTY_FUNCTION__))
2138 "icmp ugt X, UINT_MAX should have been simplified already.")((!C->isMaxValue() && "icmp ugt X, UINT_MAX should have been simplified already."
) ? static_cast<void> (0) : __assert_fail ("!C->isMaxValue() && \"icmp ugt X, UINT_MAX should have been simplified already.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2138, __PRETTY_FUNCTION__));
2139 return new ICmpInst(ICmpInst::ICMP_ULE, Y,
2140 ConstantInt::get(Y->getType(), C2->udiv(*C + 1)));
2141 }
2142
2143 // (icmp ult (udiv C2, Y), C) -> (icmp ugt Y, C2/C)
2144 if (Cmp.getPredicate() == ICmpInst::ICMP_ULT) {
2145 assert(*C != 0 && "icmp ult X, 0 should have been simplified already.")((*C != 0 && "icmp ult X, 0 should have been simplified already."
) ? static_cast<void> (0) : __assert_fail ("*C != 0 && \"icmp ult X, 0 should have been simplified already.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2145, __PRETTY_FUNCTION__));
2146 return new ICmpInst(ICmpInst::ICMP_UGT, Y,
2147 ConstantInt::get(Y->getType(), C2->udiv(*C)));
2148 }
2149
2150 return nullptr;
2151}
2152
2153/// Fold icmp ({su}div X, Y), C.
2154Instruction *InstCombiner::foldICmpDivConstant(ICmpInst &Cmp,
2155 BinaryOperator *Div,
2156 const APInt *C) {
2157 // Fold: icmp pred ([us]div X, C2), C -> range test
2158 // Fold this div into the comparison, producing a range check.
2159 // Determine, based on the divide type, what the range is being
2160 // checked. If there is an overflow on the low or high side, remember
2161 // it, otherwise compute the range [low, hi) bounding the new value.
2162 // See: InsertRangeTest above for the kinds of replacements possible.
2163 const APInt *C2;
2164 if (!match(Div->getOperand(1), m_APInt(C2)))
12
←
Taking false branch
→
2165 return nullptr;
2166
2167 // FIXME: If the operand types don't match the type of the divide
2168 // then don't attempt this transform. The code below doesn't have the
2169 // logic to deal with a signed divide and an unsigned compare (and
2170 // vice versa). This is because (x /s C2) <s C produces different
2171 // results than (x /s C2) <u C or (x /u C2) <s C or even
2172 // (x /u C2) <u C. Simply casting the operands and result won't
2173 // work. :( The if statement below tests that condition and bails
2174 // if it finds it.
2175 bool DivIsSigned = Div->getOpcode() == Instruction::SDiv;
2176 if (!Cmp.isEquality() && DivIsSigned != Cmp.isSigned())
2177 return nullptr;
2178
2179 // The ProdOV computation fails on divide by 0 and divide by -1. Cases with
2180 // INT_MIN will also fail if the divisor is 1. Although folds of all these
2181 // division-by-constant cases should be present, we can not assert that they
2182 // have happened before we reach this icmp instruction.
2183 if (C2->isNullValue() || C2->isOneValue() ||
13
←
Taking false branch
→
2184 (DivIsSigned && C2->isAllOnesValue()))
2185 return nullptr;
2186
2187 // TODO: We could do all of the computations below using APInt.
2188 Constant *CmpRHS = cast<Constant>(Cmp.getOperand(1));
2189 Constant *DivRHS = cast<Constant>(Div->getOperand(1));
2190
2191 // Compute Prod = CmpRHS * DivRHS. We are essentially solving an equation of
2192 // form X / C2 = C. We solve for X by multiplying C2 (DivRHS) and C (CmpRHS).
2193 // By solving for X, we can turn this into a range check instead of computing
2194 // a divide.
2195 Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
2196
2197 // Determine if the product overflows by seeing if the product is not equal to
2198 // the divide. Make sure we do the same kind of divide as in the LHS
2199 // instruction that we're folding.
2200 bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS)
14
←
'?' condition is true
→
15
←
Assuming the condition is false
→
2201 : ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
2202
2203 ICmpInst::Predicate Pred = Cmp.getPredicate();
2204
2205 // If the division is known to be exact, then there is no remainder from the
2206 // divide, so the covered range size is unit, otherwise it is the divisor.
2207 Constant *RangeSize =
2208 Div->isExact() ? ConstantInt::get(Div->getType(), 1) : DivRHS;
16
←
Assuming the condition is false
→
17
←
'?' condition is false
→
2209
2210 // Figure out the interval that is being checked. For example, a comparison
2211 // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
2212 // Compute this interval based on the constants involved and the signedness of
2213 // the compare/divide. This computes a half-open interval, keeping track of
2214 // whether either value in the interval overflows. After analysis each
2215 // overflow variable is set to 0 if it's corresponding bound variable is valid
2216 // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
2217 int LoOverflow = 0, HiOverflow = 0;
2218 Constant *LoBound = nullptr, *HiBound = nullptr;
18
←
'LoBound' initialized to a null pointer value
→
2219
2220 if (!DivIsSigned) { // udiv
19
←
Taking false branch
→
2221 // e.g. X/5 op 3 --> [15, 20)
2222 LoBound = Prod;
2223 HiOverflow = LoOverflow = ProdOV;
2224 if (!HiOverflow) {
2225 // If this is not an exact divide, then many values in the range collapse
2226 // to the same result value.
2227 HiOverflow = addWithOverflow(HiBound, LoBound, RangeSize, false);
2228 }
2229 } else if (C2->isStrictlyPositive()) { // Divisor is > 0.
20
←
Taking false branch
→
2230 if (C->isNullValue()) { // (X / pos) op 0
2231 // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
2232 LoBound = ConstantExpr::getNeg(SubOne(RangeSize));
2233 HiBound = RangeSize;
2234 } else if (C->isStrictlyPositive()) { // (X / pos) op pos
2235 LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
2236 HiOverflow = LoOverflow = ProdOV;
2237 if (!HiOverflow)
2238 HiOverflow = addWithOverflow(HiBound, Prod, RangeSize, true);
2239 } else { // (X / pos) op neg
2240 // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
2241 HiBound = AddOne(Prod);
2242 LoOverflow = HiOverflow = ProdOV ? -1 : 0;
2243 if (!LoOverflow) {
2244 Constant *DivNeg = ConstantExpr::getNeg(RangeSize);
2245 LoOverflow = addWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
2246 }
2247 }
2248 } else if (C2->isNegative()) { // Divisor is < 0.
21
←
Taking false branch
→
2249 if (Div->isExact())
2250 RangeSize = ConstantExpr::getNeg(RangeSize);
2251 if (C->isNullValue()) { // (X / neg) op 0
2252 // e.g. X/-5 op 0 --> [-4, 5)
2253 LoBound = AddOne(RangeSize);
2254 HiBound = ConstantExpr::getNeg(RangeSize);
2255 if (HiBound == DivRHS) { // -INTMIN = INTMIN
2256 HiOverflow = 1; // [INTMIN+1, overflow)
2257 HiBound = nullptr; // e.g. X/INTMIN = 0 --> X > INTMIN
2258 }
2259 } else if (C->isStrictlyPositive()) { // (X / neg) op pos
2260 // e.g. X/-5 op 3 --> [-19, -14)
2261 HiBound = AddOne(Prod);
2262 HiOverflow = LoOverflow = ProdOV ? -1 : 0;
2263 if (!LoOverflow)
2264 LoOverflow = addWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0;
2265 } else { // (X / neg) op neg
2266 LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
2267 LoOverflow = HiOverflow = ProdOV;
2268 if (!HiOverflow)
2269 HiOverflow = subWithOverflow(HiBound, Prod, RangeSize, true);
2270 }
2271
2272 // Dividing by a negative swaps the condition. LT <-> GT
2273 Pred = ICmpInst::getSwappedPredicate(Pred);
2274 }
2275
2276 Value *X = Div->getOperand(0);
2277 switch (Pred) {
22
←
Control jumps to 'case ICMP_EQ:' at line 2279
→
2278 default: llvm_unreachable("Unhandled icmp opcode!")::llvm::llvm_unreachable_internal("Unhandled icmp opcode!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2278);
2279 case ICmpInst::ICMP_EQ:
2280 if (LoOverflow && HiOverflow)
2281 return replaceInstUsesWith(Cmp, Builder->getFalse());
2282 if (HiOverflow)
23
←
Taking false branch
→
2283 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
2284 ICmpInst::ICMP_UGE, X, LoBound);
2285 if (LoOverflow)
24
←
Taking false branch
→
2286 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
2287 ICmpInst::ICMP_ULT, X, HiBound);
2288 return replaceInstUsesWith(
2289 Cmp, insertRangeTest(X, LoBound->getUniqueInteger(),
25
←
Called C++ object pointer is null
2290 HiBound->getUniqueInteger(), DivIsSigned, true));
2291 case ICmpInst::ICMP_NE:
2292 if (LoOverflow && HiOverflow)
2293 return replaceInstUsesWith(Cmp, Builder->getTrue());
2294 if (HiOverflow)
2295 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
2296 ICmpInst::ICMP_ULT, X, LoBound);
2297 if (LoOverflow)
2298 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
2299 ICmpInst::ICMP_UGE, X, HiBound);
2300 return replaceInstUsesWith(Cmp,
2301 insertRangeTest(X, LoBound->getUniqueInteger(),
2302 HiBound->getUniqueInteger(),
2303 DivIsSigned, false));
2304 case ICmpInst::ICMP_ULT:
2305 case ICmpInst::ICMP_SLT:
2306 if (LoOverflow == +1) // Low bound is greater than input range.
2307 return replaceInstUsesWith(Cmp, Builder->getTrue());
2308 if (LoOverflow == -1) // Low bound is less than input range.
2309 return replaceInstUsesWith(Cmp, Builder->getFalse());
2310 return new ICmpInst(Pred, X, LoBound);
2311 case ICmpInst::ICMP_UGT:
2312 case ICmpInst::ICMP_SGT:
2313 if (HiOverflow == +1) // High bound greater than input range.
2314 return replaceInstUsesWith(Cmp, Builder->getFalse());
2315 if (HiOverflow == -1) // High bound less than input range.
2316 return replaceInstUsesWith(Cmp, Builder->getTrue());
2317 if (Pred == ICmpInst::ICMP_UGT)
2318 return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
2319 return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
2320 }
2321
2322 return nullptr;
2323}
2324
2325/// Fold icmp (sub X, Y), C.
2326Instruction *InstCombiner::foldICmpSubConstant(ICmpInst &Cmp,
2327 BinaryOperator *Sub,
2328 const APInt *C) {
2329 Value *X = Sub->getOperand(0), *Y = Sub->getOperand(1);
2330 ICmpInst::Predicate Pred = Cmp.getPredicate();
2331
2332 // The following transforms are only worth it if the only user of the subtract
2333 // is the icmp.
2334 if (!Sub->hasOneUse())
2335 return nullptr;
2336
2337 if (Sub->hasNoSignedWrap()) {
2338 // (icmp sgt (sub nsw X, Y), -1) -> (icmp sge X, Y)
2339 if (Pred == ICmpInst::ICMP_SGT && C->isAllOnesValue())
2340 return new ICmpInst(ICmpInst::ICMP_SGE, X, Y);
2341
2342 // (icmp sgt (sub nsw X, Y), 0) -> (icmp sgt X, Y)
2343 if (Pred == ICmpInst::ICMP_SGT && C->isNullValue())
2344 return new ICmpInst(ICmpInst::ICMP_SGT, X, Y);
2345
2346 // (icmp slt (sub nsw X, Y), 0) -> (icmp slt X, Y)
2347 if (Pred == ICmpInst::ICMP_SLT && C->isNullValue())
2348 return new ICmpInst(ICmpInst::ICMP_SLT, X, Y);
2349
2350 // (icmp slt (sub nsw X, Y), 1) -> (icmp sle X, Y)
2351 if (Pred == ICmpInst::ICMP_SLT && C->isOneValue())
2352 return new ICmpInst(ICmpInst::ICMP_SLE, X, Y);
2353 }
2354
2355 const APInt *C2;
2356 if (!match(X, m_APInt(C2)))
2357 return nullptr;
2358
2359 // C2 - Y <u C -> (Y | (C - 1)) == C2
2360 // iff (C2 & (C - 1)) == C - 1 and C is a power of 2
2361 if (Pred == ICmpInst::ICMP_ULT && C->isPowerOf2() &&
2362 (*C2 & (*C - 1)) == (*C - 1))
2363 return new ICmpInst(ICmpInst::ICMP_EQ, Builder->CreateOr(Y, *C - 1), X);
2364
2365 // C2 - Y >u C -> (Y | C) != C2
2366 // iff C2 & C == C and C + 1 is a power of 2
2367 if (Pred == ICmpInst::ICMP_UGT && (*C + 1).isPowerOf2() && (*C2 & *C) == *C)
2368 return new ICmpInst(ICmpInst::ICMP_NE, Builder->CreateOr(Y, *C), X);
2369
2370 return nullptr;
2371}
2372
2373/// Fold icmp (add X, Y), C.
2374Instruction *InstCombiner::foldICmpAddConstant(ICmpInst &Cmp,
2375 BinaryOperator *Add,
2376 const APInt *C) {
2377 Value *Y = Add->getOperand(1);
2378 const APInt *C2;
2379 if (Cmp.isEquality() || !match(Y, m_APInt(C2)))
2380 return nullptr;
2381
2382 // Fold icmp pred (add X, C2), C.
2383 Value *X = Add->getOperand(0);
2384 Type *Ty = Add->getType();
2385 CmpInst::Predicate Pred = Cmp.getPredicate();
2386
2387 // If the add does not wrap, we can always adjust the compare by subtracting
2388 // the constants. Equality comparisons are handled elsewhere. SGE/SLE are
2389 // canonicalized to SGT/SLT.
2390 if (Add->hasNoSignedWrap() &&
2391 (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLT)) {
2392 bool Overflow;
2393 APInt NewC = C->ssub_ov(*C2, Overflow);
2394 // If there is overflow, the result must be true or false.
2395 // TODO: Can we assert there is no overflow because InstSimplify always
2396 // handles those cases?
2397 if (!Overflow)
2398 // icmp Pred (add nsw X, C2), C --> icmp Pred X, (C - C2)
2399 return new ICmpInst(Pred, X, ConstantInt::get(Ty, NewC));
2400 }
2401
2402 auto CR = ConstantRange::makeExactICmpRegion(Pred, *C).subtract(*C2);
2403 const APInt &Upper = CR.getUpper();
2404 const APInt &Lower = CR.getLower();
2405 if (Cmp.isSigned()) {
2406 if (Lower.isSignMask())
2407 return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantInt::get(Ty, Upper));
2408 if (Upper.isSignMask())
2409 return new ICmpInst(ICmpInst::ICMP_SGE, X, ConstantInt::get(Ty, Lower));
2410 } else {
2411 if (Lower.isMinValue())
2412 return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantInt::get(Ty, Upper));
2413 if (Upper.isMinValue())
2414 return new ICmpInst(ICmpInst::ICMP_UGE, X, ConstantInt::get(Ty, Lower));
2415 }
2416
2417 if (!Add->hasOneUse())
2418 return nullptr;
2419
2420 // X+C <u C2 -> (X & -C2) == C
2421 // iff C & (C2-1) == 0
2422 // C2 is a power of 2
2423 if (Pred == ICmpInst::ICMP_ULT && C->isPowerOf2() && (*C2 & (*C - 1)) == 0)
2424 return new ICmpInst(ICmpInst::ICMP_EQ, Builder->CreateAnd(X, -(*C)),
2425 ConstantExpr::getNeg(cast<Constant>(Y)));
2426
2427 // X+C >u C2 -> (X & ~C2) != C
2428 // iff C & C2 == 0
2429 // C2+1 is a power of 2
2430 if (Pred == ICmpInst::ICMP_UGT && (*C + 1).isPowerOf2() && (*C2 & *C) == 0)
2431 return new ICmpInst(ICmpInst::ICMP_NE, Builder->CreateAnd(X, ~(*C)),
2432 ConstantExpr::getNeg(cast<Constant>(Y)));
2433
2434 return nullptr;
2435}
2436
2437bool InstCombiner::matchThreeWayIntCompare(SelectInst *SI, Value *&LHS,
2438 Value *&RHS, ConstantInt *&Less,
2439 ConstantInt *&Equal,
2440 ConstantInt *&Greater) {
2441 // TODO: Generalize this to work with other comparison idioms or ensure
2442 // they get canonicalized into this form.
2443
2444 // select i1 (a == b), i32 Equal, i32 (select i1 (a < b), i32 Less, i32
2445 // Greater), where Equal, Less and Greater are placeholders for any three
2446 // constants.
2447 ICmpInst::Predicate PredA, PredB;
2448 if (match(SI->getTrueValue(), m_ConstantInt(Equal)) &&
2449 match(SI->getCondition(), m_ICmp(PredA, m_Value(LHS), m_Value(RHS))) &&
2450 PredA == ICmpInst::ICMP_EQ &&
2451 match(SI->getFalseValue(),
2452 m_Select(m_ICmp(PredB, m_Specific(LHS), m_Specific(RHS)),
2453 m_ConstantInt(Less), m_ConstantInt(Greater))) &&
2454 PredB == ICmpInst::ICMP_SLT) {
2455 return true;
2456 }
2457 return false;
2458}
2459
2460Instruction *InstCombiner::foldICmpSelectConstant(ICmpInst &Cmp,
2461 Instruction *Select,
2462 ConstantInt *C) {
2463
2464 assert(C && "Cmp RHS should be a constant int!")((C && "Cmp RHS should be a constant int!") ? static_cast
<void> (0) : __assert_fail ("C && \"Cmp RHS should be a constant int!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2464, __PRETTY_FUNCTION__));
2465 // If we're testing a constant value against the result of a three way
2466 // comparison, the result can be expressed directly in terms of the
2467 // original values being compared. Note: We could possibly be more
2468 // aggressive here and remove the hasOneUse test. The original select is
2469 // really likely to simplify or sink when we remove a test of the result.
2470 Value *OrigLHS, *OrigRHS;
2471 ConstantInt *C1LessThan, *C2Equal, *C3GreaterThan;
2472 if (Cmp.hasOneUse() &&
2473 matchThreeWayIntCompare(cast<SelectInst>(Select), OrigLHS, OrigRHS,
2474 C1LessThan, C2Equal, C3GreaterThan)) {
2475 assert(C1LessThan && C2Equal && C3GreaterThan)((C1LessThan && C2Equal && C3GreaterThan) ? static_cast
<void> (0) : __assert_fail ("C1LessThan && C2Equal && C3GreaterThan"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2475, __PRETTY_FUNCTION__));
2476
2477 bool TrueWhenLessThan =
2478 ConstantExpr::getCompare(Cmp.getPredicate(), C1LessThan, C)
2479 ->isAllOnesValue();
2480 bool TrueWhenEqual =
2481 ConstantExpr::getCompare(Cmp.getPredicate(), C2Equal, C)
2482 ->isAllOnesValue();
2483 bool TrueWhenGreaterThan =
2484 ConstantExpr::getCompare(Cmp.getPredicate(), C3GreaterThan, C)
2485 ->isAllOnesValue();
2486
2487 // This generates the new instruction that will replace the original Cmp
2488 // Instruction. Instead of enumerating the various combinations when
2489 // TrueWhenLessThan, TrueWhenEqual and TrueWhenGreaterThan are true versus
2490 // false, we rely on chaining of ORs and future passes of InstCombine to
2491 // simplify the OR further (i.e. a s< b || a == b becomes a s<= b).
2492
2493 // When none of the three constants satisfy the predicate for the RHS (C),
2494 // the entire original Cmp can be simplified to a false.
2495 Value *Cond = Builder->getFalse();
2496 if (TrueWhenLessThan)
2497 Cond = Builder->CreateOr(Cond, Builder->CreateICmp(ICmpInst::ICMP_SLT, OrigLHS, OrigRHS));
2498 if (TrueWhenEqual)
2499 Cond = Builder->CreateOr(Cond, Builder->CreateICmp(ICmpInst::ICMP_EQ, OrigLHS, OrigRHS));
2500 if (TrueWhenGreaterThan)
2501 Cond = Builder->CreateOr(Cond, Builder->CreateICmp(ICmpInst::ICMP_SGT, OrigLHS, OrigRHS));
2502
2503 return replaceInstUsesWith(Cmp, Cond);
2504 }
2505 return nullptr;
2506}
2507
2508/// Try to fold integer comparisons with a constant operand: icmp Pred X, C
2509/// where X is some kind of instruction.
2510Instruction *InstCombiner::foldICmpInstWithConstant(ICmpInst &Cmp) {
2511 const APInt *C;
2512 if (!match(Cmp.getOperand(1), m_APInt(C)))
2513 return nullptr;
2514
2515 BinaryOperator *BO;
2516 if (match(Cmp.getOperand(0), m_BinOp(BO))) {
2517 switch (BO->getOpcode()) {
2518 case Instruction::Xor:
2519 if (Instruction *I = foldICmpXorConstant(Cmp, BO, C))
2520 return I;
2521 break;
2522 case Instruction::And:
2523 if (Instruction *I = foldICmpAndConstant(Cmp, BO, C))
2524 return I;
2525 break;
2526 case Instruction::Or:
2527 if (Instruction *I = foldICmpOrConstant(Cmp, BO, C))
2528 return I;
2529 break;
2530 case Instruction::Mul:
2531 if (Instruction *I = foldICmpMulConstant(Cmp, BO, C))
2532 return I;
2533 break;
2534 case Instruction::Shl:
2535 if (Instruction *I = foldICmpShlConstant(Cmp, BO, C))
2536 return I;
2537 break;
2538 case Instruction::LShr:
2539 case Instruction::AShr:
2540 if (Instruction *I = foldICmpShrConstant(Cmp, BO, C))
2541 return I;
2542 break;
2543 case Instruction::UDiv:
2544 if (Instruction *I = foldICmpUDivConstant(Cmp, BO, C))
2545 return I;
2546 LLVM_FALLTHROUGH[[clang::fallthrough]];
2547 case Instruction::SDiv:
2548 if (Instruction *I = foldICmpDivConstant(Cmp, BO, C))
2549 return I;
2550 break;
2551 case Instruction::Sub:
2552 if (Instruction *I = foldICmpSubConstant(Cmp, BO, C))
2553 return I;
2554 break;
2555 case Instruction::Add:
2556 if (Instruction *I = foldICmpAddConstant(Cmp, BO, C))
2557 return I;
2558 break;
2559 default:
2560 break;
2561 }
2562 // TODO: These folds could be refactored to be part of the above calls.
2563 if (Instruction *I = foldICmpBinOpEqualityWithConstant(Cmp, BO, C))
2564 return I;
2565 }
2566
2567 // Match against CmpInst LHS being instructions other than binary operators.
2568 Instruction *LHSI;
2569 if (match(Cmp.getOperand(0), m_Instruction(LHSI))) {
2570 switch (LHSI->getOpcode()) {
2571 case Instruction::Select:
2572 {
2573 // For now, we only support constant integers while folding the
2574 // ICMP(SELECT)) pattern. We can extend this to support vector of integers
2575 // similar to the cases handled by binary ops above.
2576 if (ConstantInt *ConstRHS = dyn_cast<ConstantInt>(Cmp.getOperand(1)))
2577 if (Instruction *I = foldICmpSelectConstant(Cmp, LHSI, ConstRHS))
2578 return I;
2579 break;
2580 }
2581 case Instruction::Trunc:
2582 if (Instruction *I = foldICmpTruncConstant(Cmp, LHSI, C))
2583 return I;
2584 break;
2585 default:
2586 break;
2587 }
2588 }
2589
2590 if (Instruction *I = foldICmpIntrinsicWithConstant(Cmp, C))
2591 return I;
2592
2593 return nullptr;
2594}
2595
2596/// Fold an icmp equality instruction with binary operator LHS and constant RHS:
2597/// icmp eq/ne BO, C.
2598Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(ICmpInst &Cmp,
2599 BinaryOperator *BO,
2600 const APInt *C) {
2601 // TODO: Some of these folds could work with arbitrary constants, but this
2602 // function is limited to scalar and vector splat constants.
2603 if (!Cmp.isEquality())
2604 return nullptr;
2605
2606 ICmpInst::Predicate Pred = Cmp.getPredicate();
2607 bool isICMP_NE = Pred == ICmpInst::ICMP_NE;
2608 Constant *RHS = cast<Constant>(Cmp.getOperand(1));
2609 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2610
2611 switch (BO->getOpcode()) {
2612 case Instruction::SRem:
2613 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2614 if (C->isNullValue() && BO->hasOneUse()) {
2615 const APInt *BOC;
2616 if (match(BOp1, m_APInt(BOC)) && BOC->sgt(1) && BOC->isPowerOf2()) {
2617 Value *NewRem = Builder->CreateURem(BOp0, BOp1, BO->getName());
2618 return new ICmpInst(Pred, NewRem,
2619 Constant::getNullValue(BO->getType()));
2620 }
2621 }
2622 break;
2623 case Instruction::Add: {
2624 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2625 const APInt *BOC;
2626 if (match(BOp1, m_APInt(BOC))) {
2627 if (BO->hasOneUse()) {
2628 Constant *SubC = ConstantExpr::getSub(RHS, cast<Constant>(BOp1));
2629 return new ICmpInst(Pred, BOp0, SubC);
2630 }
2631 } else if (C->isNullValue()) {
2632 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2633 // efficiently invertible, or if the add has just this one use.
2634 if (Value *NegVal = dyn_castNegVal(BOp1))
2635 return new ICmpInst(Pred, BOp0, NegVal);
2636 if (Value *NegVal = dyn_castNegVal(BOp0))
2637 return new ICmpInst(Pred, NegVal, BOp1);
2638 if (BO->hasOneUse()) {
2639 Value *Neg = Builder->CreateNeg(BOp1);
2640 Neg->takeName(BO);
2641 return new ICmpInst(Pred, BOp0, Neg);
2642 }
2643 }
2644 break;
2645 }
2646 case Instruction::Xor:
2647 if (BO->hasOneUse()) {
2648 if (Constant *BOC = dyn_cast<Constant>(BOp1)) {
2649 // For the xor case, we can xor two constants together, eliminating
2650 // the explicit xor.
2651 return new ICmpInst(Pred, BOp0, ConstantExpr::getXor(RHS, BOC));
2652 } else if (C->isNullValue()) {
2653 // Replace ((xor A, B) != 0) with (A != B)
2654 return new ICmpInst(Pred, BOp0, BOp1);
2655 }
2656 }
2657 break;
2658 case Instruction::Sub:
2659 if (BO->hasOneUse()) {
2660 const APInt *BOC;
2661 if (match(BOp0, m_APInt(BOC))) {
2662 // Replace ((sub BOC, B) != C) with (B != BOC-C).
2663 Constant *SubC = ConstantExpr::getSub(cast<Constant>(BOp0), RHS);
2664 return new ICmpInst(Pred, BOp1, SubC);
2665 } else if (C->isNullValue()) {
2666 // Replace ((sub A, B) != 0) with (A != B).
2667 return new ICmpInst(Pred, BOp0, BOp1);
2668 }
2669 }
2670 break;
2671 case Instruction::Or: {
2672 const APInt *BOC;
2673 if (match(BOp1, m_APInt(BOC)) && BO->hasOneUse() && RHS->isAllOnesValue()) {
2674 // Comparing if all bits outside of a constant mask are set?
2675 // Replace (X | C) == -1 with (X & ~C) == ~C.
2676 // This removes the -1 constant.
2677 Constant *NotBOC = ConstantExpr::getNot(cast<Constant>(BOp1));
2678 Value *And = Builder->CreateAnd(BOp0, NotBOC);
2679 return new ICmpInst(Pred, And, NotBOC);
2680 }
2681 break;
2682 }
2683 case Instruction::And: {
2684 const APInt *BOC;
2685 if (match(BOp1, m_APInt(BOC))) {
2686 // If we have ((X & C) == C), turn it into ((X & C) != 0).
2687 if (C == BOC && C->isPowerOf2())
2688 return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
2689 BO, Constant::getNullValue(RHS->getType()));
2690
2691 // Don't perform the following transforms if the AND has multiple uses
2692 if (!BO->hasOneUse())
2693 break;
2694
2695 // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
2696 if (BOC->isSignMask()) {
2697 Constant *Zero = Constant::getNullValue(BOp0->getType());
2698 auto NewPred = isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
2699 return new ICmpInst(NewPred, BOp0, Zero);
2700 }
2701
2702 // ((X & ~7) == 0) --> X < 8
2703 if (C->isNullValue() && (~(*BOC) + 1).isPowerOf2()) {
2704 Constant *NegBOC = ConstantExpr::getNeg(cast<Constant>(BOp1));
2705 auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
2706 return new ICmpInst(NewPred, BOp0, NegBOC);
2707 }
2708 }
2709 break;
2710 }
2711 case Instruction::Mul:
2712 if (C->isNullValue() && BO->hasNoSignedWrap()) {
2713 const APInt *BOC;
2714 if (match(BOp1, m_APInt(BOC)) && !BOC->isNullValue()) {
2715 // The trivial case (mul X, 0) is handled by InstSimplify.
2716 // General case : (mul X, C) != 0 iff X != 0
2717 // (mul X, C) == 0 iff X == 0
2718 return new ICmpInst(Pred, BOp0, Constant::getNullValue(RHS->getType()));
2719 }
2720 }
2721 break;
2722 case Instruction::UDiv:
2723 if (C->isNullValue()) {
2724 // (icmp eq/ne (udiv A, B), 0) -> (icmp ugt/ule i32 B, A)
2725 auto NewPred = isICMP_NE ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT;
2726 return new ICmpInst(NewPred, BOp1, BOp0);
2727 }
2728 break;
2729 default:
2730 break;
2731 }
2732 return nullptr;
2733}
2734
2735/// Fold an icmp with LLVM intrinsic and constant operand: icmp Pred II, C.
2736Instruction *InstCombiner::foldICmpIntrinsicWithConstant(ICmpInst &Cmp,
2737 const APInt *C) {
2738 IntrinsicInst *II = dyn_cast<IntrinsicInst>(Cmp.getOperand(0));
2739 if (!II || !Cmp.isEquality())
2740 return nullptr;
2741
2742 // Handle icmp {eq|ne} <intrinsic>, intcst.
2743 switch (II->getIntrinsicID()) {
2744 case Intrinsic::bswap:
2745 Worklist.Add(II);
2746 Cmp.setOperand(0, II->getArgOperand(0));
2747 Cmp.setOperand(1, Builder->getInt(C->byteSwap()));
2748 return &Cmp;
2749 case Intrinsic::ctlz:
2750 case Intrinsic::cttz:
2751 // ctz(A) == bitwidth(A) -> A == 0 and likewise for !=
2752 if (*C == C->getBitWidth()) {
2753 Worklist.Add(II);
2754 Cmp.setOperand(0, II->getArgOperand(0));
2755 Cmp.setOperand(1, ConstantInt::getNullValue(II->getType()));
2756 return &Cmp;
2757 }
2758 break;
2759 case Intrinsic::ctpop: {
2760 // popcount(A) == 0 -> A == 0 and likewise for !=
2761 // popcount(A) == bitwidth(A) -> A == -1 and likewise for !=
2762 bool IsZero = C->isNullValue();
2763 if (IsZero || *C == C->getBitWidth()) {
2764 Worklist.Add(II);
2765 Cmp.setOperand(0, II->getArgOperand(0));
2766 auto *NewOp = IsZero ? Constant::getNullValue(II->getType())
2767 : Constant::getAllOnesValue(II->getType());
2768 Cmp.setOperand(1, NewOp);
2769 return &Cmp;
2770 }
2771 break;
2772 }
2773 default:
2774 break;
2775 }
2776 return nullptr;
2777}
2778
2779/// Handle icmp with constant (but not simple integer constant) RHS.
2780Instruction *InstCombiner::foldICmpInstWithConstantNotInt(ICmpInst &I) {
2781 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2782 Constant *RHSC = dyn_cast<Constant>(Op1);
2783 Instruction *LHSI = dyn_cast<Instruction>(Op0);
2784 if (!RHSC || !LHSI)
2785 return nullptr;
2786
2787 switch (LHSI->getOpcode()) {
2788 case Instruction::GetElementPtr:
2789 // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
2790 if (RHSC->isNullValue() &&
2791 cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
2792 return new ICmpInst(
2793 I.getPredicate(), LHSI->getOperand(0),
2794 Constant::getNullValue(LHSI->getOperand(0)->getType()));
2795 break;
2796 case Instruction::PHI:
2797 // Only fold icmp into the PHI if the phi and icmp are in the same
2798 // block. If in the same block, we're encouraging jump threading. If
2799 // not, we are just pessimizing the code by making an i1 phi.
2800 if (LHSI->getParent() == I.getParent())
2801 if (Instruction *NV = foldOpIntoPhi(I, cast<PHINode>(LHSI)))
2802 return NV;
2803 break;
2804 case Instruction::Select: {
2805 // If either operand of the select is a constant, we can fold the
2806 // comparison into the select arms, which will cause one to be
2807 // constant folded and the select turned into a bitwise or.
2808 Value *Op1 = nullptr, *Op2 = nullptr;
2809 ConstantInt *CI = nullptr;
2810 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
2811 Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
2812 CI = dyn_cast<ConstantInt>(Op1);
2813 }
2814 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
2815 Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
2816 CI = dyn_cast<ConstantInt>(Op2);
2817 }
2818
2819 // We only want to perform this transformation if it will not lead to
2820 // additional code. This is true if either both sides of the select
2821 // fold to a constant (in which case the icmp is replaced with a select
2822 // which will usually simplify) or this is the only user of the
2823 // select (in which case we are trading a select+icmp for a simpler
2824 // select+icmp) or all uses of the select can be replaced based on
2825 // dominance information ("Global cases").
2826 bool Transform = false;
2827 if (Op1 && Op2)
2828 Transform = true;
2829 else if (Op1 || Op2) {
2830 // Local case
2831 if (LHSI->hasOneUse())
2832 Transform = true;
2833 // Global cases
2834 else if (CI && !CI->isZero())
2835 // When Op1 is constant try replacing select with second operand.
2836 // Otherwise Op2 is constant and try replacing select with first
2837 // operand.
2838 Transform =
2839 replacedSelectWithOperand(cast<SelectInst>(LHSI), &I, Op1 ? 2 : 1);
2840 }
2841 if (Transform) {
2842 if (!Op1)
2843 Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1), RHSC,
2844 I.getName());
2845 if (!Op2)
2846 Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2), RHSC,
2847 I.getName());
2848 return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
2849 }
2850 break;
2851 }
2852 case Instruction::IntToPtr:
2853 // icmp pred inttoptr(X), null -> icmp pred X, 0
2854 if (RHSC->isNullValue() &&
2855 DL.getIntPtrType(RHSC->getType()) == LHSI->getOperand(0)->getType())
2856 return new ICmpInst(
2857 I.getPredicate(), LHSI->getOperand(0),
2858 Constant::getNullValue(LHSI->getOperand(0)->getType()));
2859 break;
2860
2861 case Instruction::Load:
2862 // Try to optimize things like "A[i] > 4" to index computations.
2863 if (GetElementPtrInst *GEP =
2864 dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
2865 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
2866 if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
2867 !cast<LoadInst>(LHSI)->isVolatile())
2868 if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, I))
2869 return Res;
2870 }
2871 break;
2872 }
2873
2874 return nullptr;
2875}
2876
2877/// Try to fold icmp (binop), X or icmp X, (binop).
2878/// TODO: A large part of this logic is duplicated in InstSimplify's
2879/// simplifyICmpWithBinOp(). We should be able to share that and avoid the code
2880/// duplication.
2881Instruction *InstCombiner::foldICmpBinOp(ICmpInst &I) {
2882 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2883
2884 // Special logic for binary operators.
2885 BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0);
2886 BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1);
2887 if (!BO0 && !BO1)
2888 return nullptr;
2889
2890 const CmpInst::Predicate Pred = I.getPredicate();
2891 bool NoOp0WrapProblem = false, NoOp1WrapProblem = false;
2892 if (BO0 && isa<OverflowingBinaryOperator>(BO0))
2893 NoOp0WrapProblem =
2894 ICmpInst::isEquality(Pred) ||
2895 (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) ||
2896 (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap());
2897 if (BO1 && isa<OverflowingBinaryOperator>(BO1))
2898 NoOp1WrapProblem =
2899 ICmpInst::isEquality(Pred) ||
2900 (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) ||
2901 (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap());
2902
2903 // Analyze the case when either Op0 or Op1 is an add instruction.
2904 // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
2905 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2906 if (BO0 && BO0->getOpcode() == Instruction::Add) {
2907 A = BO0->getOperand(0);
2908 B = BO0->getOperand(1);
2909 }
2910 if (BO1 && BO1->getOpcode() == Instruction::Add) {
2911 C = BO1->getOperand(0);
2912 D = BO1->getOperand(1);
2913 }
2914
2915 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2916 if ((A == Op1 || B == Op1) && NoOp0WrapProblem)
2917 return new ICmpInst(Pred, A == Op1 ? B : A,
2918 Constant::getNullValue(Op1->getType()));
2919
2920 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
2921 if ((C == Op0 || D == Op0) && NoOp1WrapProblem)
2922 return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()),
2923 C == Op0 ? D : C);
2924
2925 // icmp (X+Y), (X+Z) -> icmp Y, Z for equalities or if there is no overflow.
2926 if (A && C && (A == C || A == D || B == C || B == D) && NoOp0WrapProblem &&
2927 NoOp1WrapProblem &&
2928 // Try not to increase register pressure.
2929 BO0->hasOneUse() && BO1->hasOneUse()) {
2930 // Determine Y and Z in the form icmp (X+Y), (X+Z).
2931 Value *Y, *Z;
2932 if (A == C) {
2933 // C + B == C + D -> B == D
2934 Y = B;
2935 Z = D;
2936 } else if (A == D) {
2937 // D + B == C + D -> B == C
2938 Y = B;
2939 Z = C;
2940 } else if (B == C) {
2941 // A + C == C + D -> A == D
2942 Y = A;
2943 Z = D;
2944 } else {
2945 assert(B == D)((B == D) ? static_cast<void> (0) : __assert_fail ("B == D"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2945, __PRETTY_FUNCTION__));
2946 // A + D == C + D -> A == C
2947 Y = A;
2948 Z = C;
2949 }
2950 return new ICmpInst(Pred, Y, Z);
2951 }
2952
2953 // icmp slt (X + -1), Y -> icmp sle X, Y
2954 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT &&
2955 match(B, m_AllOnes()))
2956 return new ICmpInst(CmpInst::ICMP_SLE, A, Op1);
2957
2958 // icmp sge (X + -1), Y -> icmp sgt X, Y
2959 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE &&
2960 match(B, m_AllOnes()))
2961 return new ICmpInst(CmpInst::ICMP_SGT, A, Op1);
2962
2963 // icmp sle (X + 1), Y -> icmp slt X, Y
2964 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE && match(B, m_One()))
2965 return new ICmpInst(CmpInst::ICMP_SLT, A, Op1);
2966
2967 // icmp sgt (X + 1), Y -> icmp sge X, Y
2968 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT && match(B, m_One()))
2969 return new ICmpInst(CmpInst::ICMP_SGE, A, Op1);
2970
2971 // icmp sgt X, (Y + -1) -> icmp sge X, Y
2972 if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_SGT &&
2973 match(D, m_AllOnes()))
2974 return new ICmpInst(CmpInst::ICMP_SGE, Op0, C);
2975
2976 // icmp sle X, (Y + -1) -> icmp slt X, Y
2977 if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_SLE &&
2978 match(D, m_AllOnes()))
2979 return new ICmpInst(CmpInst::ICMP_SLT, Op0, C);
2980
2981 // icmp sge X, (Y + 1) -> icmp sgt X, Y
2982 if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_SGE && match(D, m_One()))
2983 return new ICmpInst(CmpInst::ICMP_SGT, Op0, C);
2984
2985 // icmp slt X, (Y + 1) -> icmp sle X, Y
2986 if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_SLT && match(D, m_One()))
2987 return new ICmpInst(CmpInst::ICMP_SLE, Op0, C);
2988
2989 // TODO: The subtraction-related identities shown below also hold, but
2990 // canonicalization from (X -nuw 1) to (X + -1) means that the combinations
2991 // wouldn't happen even if they were implemented.
2992 //
2993 // icmp ult (X - 1), Y -> icmp ule X, Y
2994 // icmp uge (X - 1), Y -> icmp ugt X, Y
2995 // icmp ugt X, (Y - 1) -> icmp uge X, Y
2996 // icmp ule X, (Y - 1) -> icmp ult X, Y
2997
2998 // icmp ule (X + 1), Y -> icmp ult X, Y
2999 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_ULE && match(B, m_One()))
3000 return new ICmpInst(CmpInst::ICMP_ULT, A, Op1);
3001
3002 // icmp ugt (X + 1), Y -> icmp uge X, Y
3003 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_UGT && match(B, m_One()))
3004 return new ICmpInst(CmpInst::ICMP_UGE, A, Op1);
3005
3006 // icmp uge X, (Y + 1) -> icmp ugt X, Y
3007 if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_UGE && match(D, m_One()))
3008 return new ICmpInst(CmpInst::ICMP_UGT, Op0, C);
3009
3010 // icmp ult X, (Y + 1) -> icmp ule X, Y
3011 if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_ULT && match(D, m_One()))
3012 return new ICmpInst(CmpInst::ICMP_ULE, Op0, C);
3013
3014 // if C1 has greater magnitude than C2:
3015 // icmp (X + C1), (Y + C2) -> icmp (X + C3), Y
3016 // s.t. C3 = C1 - C2
3017 //
3018 // if C2 has greater magnitude than C1:
3019 // icmp (X + C1), (Y + C2) -> icmp X, (Y + C3)
3020 // s.t. C3 = C2 - C1
3021 if (A && C && NoOp0WrapProblem && NoOp1WrapProblem &&
3022 (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned())
3023 if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
3024 if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) {
3025 const APInt &AP1 = C1->getValue();
3026 const APInt &AP2 = C2->getValue();
3027 if (AP1.isNegative() == AP2.isNegative()) {
3028 APInt AP1Abs = C1->getValue().abs();
3029 APInt AP2Abs = C2->getValue().abs();
3030 if (AP1Abs.uge(AP2Abs)) {
3031 ConstantInt *C3 = Builder->getInt(AP1 - AP2);
3032 Value *NewAdd = Builder->CreateNSWAdd(A, C3);
3033 return new ICmpInst(Pred, NewAdd, C);
3034 } else {
3035 ConstantInt *C3 = Builder->getInt(AP2 - AP1);
3036 Value *NewAdd = Builder->CreateNSWAdd(C, C3);
3037 return new ICmpInst(Pred, A, NewAdd);
3038 }
3039 }
3040 }
3041
3042 // Analyze the case when either Op0 or Op1 is a sub instruction.
3043 // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null).
3044 A = nullptr;
3045 B = nullptr;
3046 C = nullptr;
3047 D = nullptr;
3048 if (BO0 && BO0->getOpcode() == Instruction::Sub) {
3049 A = BO0->getOperand(0);
3050 B = BO0->getOperand(1);
3051 }
3052 if (BO1 && BO1->getOpcode() == Instruction::Sub) {
3053 C = BO1->getOperand(0);
3054 D = BO1->getOperand(1);
3055 }
3056
3057 // icmp (X-Y), X -> icmp 0, Y for equalities or if there is no overflow.
3058 if (A == Op1 && NoOp0WrapProblem)
3059 return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B);
3060
3061 // icmp X, (X-Y) -> icmp Y, 0 for equalities or if there is no overflow.
3062 if (C == Op0 && NoOp1WrapProblem)
3063 return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType()));
3064
3065 // icmp (Y-X), (Z-X) -> icmp Y, Z for equalities or if there is no overflow.
3066 if (B && D && B == D && NoOp0WrapProblem && NoOp1WrapProblem &&
3067 // Try not to increase register pressure.
3068 BO0->hasOneUse() && BO1->hasOneUse())
3069 return new ICmpInst(Pred, A, C);
3070
3071 // icmp (X-Y), (X-Z) -> icmp Z, Y for equalities or if there is no overflow.
3072 if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem &&
3073 // Try not to increase register pressure.
3074 BO0->hasOneUse() && BO1->hasOneUse())
3075 return new ICmpInst(Pred, D, B);
3076
3077 // icmp (0-X) < cst --> x > -cst
3078 if (NoOp0WrapProblem && ICmpInst::isSigned(Pred)) {
3079 Value *X;
3080 if (match(BO0, m_Neg(m_Value(X))))
3081 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1))
3082 if (!RHSC->isMinValue(/*isSigned=*/true))
3083 return new ICmpInst(I.getSwappedPredicate(), X,
3084 ConstantExpr::getNeg(RHSC));
3085 }
3086
3087 BinaryOperator *SRem = nullptr;
3088 // icmp (srem X, Y), Y
3089 if (BO0 && BO0->getOpcode() == Instruction::SRem && Op1 == BO0->getOperand(1))
3090 SRem = BO0;
3091 // icmp Y, (srem X, Y)
3092 else if (BO1 && BO1->getOpcode() == Instruction::SRem &&
3093 Op0 == BO1->getOperand(1))
3094 SRem = BO1;
3095 if (SRem) {
3096 // We don't check hasOneUse to avoid increasing register pressure because
3097 // the value we use is the same value this instruction was already using.
3098 switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) {
3099 default:
3100 break;
3101 case ICmpInst::ICMP_EQ:
3102 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3103 case ICmpInst::ICMP_NE:
3104 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
3105 case ICmpInst::ICMP_SGT:
3106 case ICmpInst::ICMP_SGE:
3107 return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1),
3108 Constant::getAllOnesValue(SRem->getType()));
3109 case ICmpInst::ICMP_SLT:
3110 case ICmpInst::ICMP_SLE:
3111 return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1),
3112 Constant::getNullValue(SRem->getType()));
3113 }
3114 }
3115
3116 if (BO0 && BO1 && BO0->getOpcode() == BO1->getOpcode() && BO0->hasOneUse() &&
3117 BO1->hasOneUse() && BO0->getOperand(1) == BO1->getOperand(1)) {
3118 switch (BO0->getOpcode()) {
3119 default:
3120 break;
3121 case Instruction::Add:
3122 case Instruction::Sub:
3123 case Instruction::Xor: {
3124 if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
3125 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
3126
3127 const APInt *C;
3128 if (match(BO0->getOperand(1), m_APInt(C))) {
3129 // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
3130 if (C->isSignMask()) {
3131 ICmpInst::Predicate NewPred =
3132 I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate();
3133 return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
3134 }
3135
3136 // icmp u/s (a ^ maxsignval), (b ^ maxsignval) --> icmp s/u' a, b
3137 if (BO0->getOpcode() == Instruction::Xor && C->isMaxSignedValue()) {
3138 ICmpInst::Predicate NewPred =
3139 I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate();
3140 NewPred = I.getSwappedPredicate(NewPred);
3141 return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
3142 }
3143 }
3144 break;
3145 }
3146 case Instruction::Mul: {
3147 if (!I.isEquality())
3148 break;
3149
3150 const APInt *C;
3151 if (match(BO0->getOperand(1), m_APInt(C)) && !C->isNullValue() &&
3152 !C->isOneValue()) {
3153 // icmp eq/ne (X * C), (Y * C) --> icmp (X & Mask), (Y & Mask)
3154 // Mask = -1 >> count-trailing-zeros(C).
3155 if (unsigned TZs = C->countTrailingZeros()) {
3156 Constant *Mask = ConstantInt::get(
3157 BO0->getType(),
3158 APInt::getLowBitsSet(C->getBitWidth(), C->getBitWidth() - TZs));
3159 Value *And1 = Builder->CreateAnd(BO0->getOperand(0), Mask);
3160 Value *And2 = Builder->CreateAnd(BO1->getOperand(0), Mask);
3161 return new ICmpInst(Pred, And1, And2);
3162 }
3163 // If there are no trailing zeros in the multiplier, just eliminate
3164 // the multiplies (no masking is needed):
3165 // icmp eq/ne (X * C), (Y * C) --> icmp eq/ne X, Y
3166 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
3167 }
3168 break;
3169 }
3170 case Instruction::UDiv:
3171 case Instruction::LShr:
3172 if (I.isSigned() || !BO0->isExact() || !BO1->isExact())
3173 break;
3174 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
3175
3176 case Instruction::SDiv:
3177 if (!I.isEquality() || !BO0->isExact() || !BO1->isExact())
3178 break;
3179 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
3180
3181 case Instruction::AShr:
3182 if (!BO0->isExact() || !BO1->isExact())
3183 break;
3184 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
3185
3186 case Instruction::Shl: {
3187 bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap();
3188 bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap();
3189 if (!NUW && !NSW)
3190 break;
3191 if (!NSW && I.isSigned())
3192 break;
3193 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
3194 }
3195 }
3196 }
3197
3198 if (BO0) {
3199 // Transform A & (L - 1) `ult` L --> L != 0
3200 auto LSubOne = m_Add(m_Specific(Op1), m_AllOnes());
3201 auto BitwiseAnd = m_c_And(m_Value(), LSubOne);
3202
3203 if (match(BO0, BitwiseAnd) && Pred == ICmpInst::ICMP_ULT) {
3204 auto *Zero = Constant::getNullValue(BO0->getType());
3205 return new ICmpInst(ICmpInst::ICMP_NE, Op1, Zero);
3206 }
3207 }
3208
3209 return nullptr;
3210}
3211
3212/// Fold icmp Pred min|max(X, Y), X.
3213static Instruction *foldICmpWithMinMax(ICmpInst &Cmp) {
3214 ICmpInst::Predicate Pred = Cmp.getPredicate();
3215 Value *Op0 = Cmp.getOperand(0);
3216 Value *X = Cmp.getOperand(1);
3217
3218 // Canonicalize minimum or maximum operand to LHS of the icmp.
3219 if (match(X, m_c_SMin(m_Specific(Op0), m_Value())) ||
3220 match(X, m_c_SMax(m_Specific(Op0), m_Value())) ||
3221 match(X, m_c_UMin(m_Specific(Op0), m_Value())) ||
3222 match(X, m_c_UMax(m_Specific(Op0), m_Value()))) {
3223 std::swap(Op0, X);
3224 Pred = Cmp.getSwappedPredicate();
3225 }
3226
3227 Value *Y;
3228 if (match(Op0, m_c_SMin(m_Specific(X), m_Value(Y)))) {
3229 // smin(X, Y) == X --> X s<= Y
3230 // smin(X, Y) s>= X --> X s<= Y
3231 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SGE)
3232 return new ICmpInst(ICmpInst::ICMP_SLE, X, Y);
3233
3234 // smin(X, Y) != X --> X s> Y
3235 // smin(X, Y) s< X --> X s> Y
3236 if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SLT)
3237 return new ICmpInst(ICmpInst::ICMP_SGT, X, Y);
3238
3239 // These cases should be handled in InstSimplify:
3240 // smin(X, Y) s<= X --> true
3241 // smin(X, Y) s> X --> false
3242 return nullptr;
3243 }
3244
3245 if (match(Op0, m_c_SMax(m_Specific(X), m_Value(Y)))) {
3246 // smax(X, Y) == X --> X s>= Y
3247 // smax(X, Y) s<= X --> X s>= Y
3248 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SLE)
3249 return new ICmpInst(ICmpInst::ICMP_SGE, X, Y);
3250
3251 // smax(X, Y) != X --> X s< Y
3252 // smax(X, Y) s> X --> X s< Y
3253 if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SGT)
3254 return new ICmpInst(ICmpInst::ICMP_SLT, X, Y);
3255
3256 // These cases should be handled in InstSimplify:
3257 // smax(X, Y) s>= X --> true
3258 // smax(X, Y) s< X --> false
3259 return nullptr;
3260 }
3261
3262 if (match(Op0, m_c_UMin(m_Specific(X), m_Value(Y)))) {
3263 // umin(X, Y) == X --> X u<= Y
3264 // umin(X, Y) u>= X --> X u<= Y
3265 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_UGE)
3266 return new ICmpInst(ICmpInst::ICMP_ULE, X, Y);
3267
3268 // umin(X, Y) != X --> X u> Y
3269 // umin(X, Y) u< X --> X u> Y
3270 if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_ULT)
3271 return new ICmpInst(ICmpInst::ICMP_UGT, X, Y);
3272
3273 // These cases should be handled in InstSimplify:
3274 // umin(X, Y) u<= X --> true
3275 // umin(X, Y) u> X --> false
3276 return nullptr;
3277 }
3278
3279 if (match(Op0, m_c_UMax(m_Specific(X), m_Value(Y)))) {
3280 // umax(X, Y) == X --> X u>= Y
3281 // umax(X, Y) u<= X --> X u>= Y
3282 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_ULE)
3283 return new ICmpInst(ICmpInst::ICMP_UGE, X, Y);
3284
3285 // umax(X, Y) != X --> X u< Y
3286 // umax(X, Y) u> X --> X u< Y
3287 if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_UGT)
3288 return new ICmpInst(ICmpInst::ICMP_ULT, X, Y);
3289
3290 // These cases should be handled in InstSimplify:
3291 // umax(X, Y) u>= X --> true
3292 // umax(X, Y) u< X --> false
3293 return nullptr;
3294 }
3295
3296 return nullptr;
3297}
3298
3299Instruction *InstCombiner::foldICmpEquality(ICmpInst &I) {
3300 if (!I.isEquality())
3301 return nullptr;
3302
3303 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3304 Value *A, *B, *C, *D;
3305 if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
3306 if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
3307 Value *OtherVal = A == Op1 ? B : A;
3308 return new ICmpInst(I.getPredicate(), OtherVal,
3309 Constant::getNullValue(A->getType()));
3310 }
3311
3312 if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
3313 // A^c1 == C^c2 --> A == C^(c1^c2)
3314 ConstantInt *C1, *C2;
3315 if (match(B, m_ConstantInt(C1)) && match(D, m_ConstantInt(C2)) &&
3316 Op1->hasOneUse()) {
3317 Constant *NC = Builder->getInt(C1->getValue() ^ C2->getValue());
3318 Value *Xor = Builder->CreateXor(C, NC);
3319 return new ICmpInst(I.getPredicate(), A, Xor);
3320 }
3321
3322 // A^B == A^D -> B == D
3323 if (A == C)
3324 return new ICmpInst(I.getPredicate(), B, D);
3325 if (A == D)
3326 return new ICmpInst(I.getPredicate(), B, C);
3327 if (B == C)
3328 return new ICmpInst(I.getPredicate(), A, D);
3329 if (B == D)
3330 return new ICmpInst(I.getPredicate(), A, C);
3331 }
3332 }
3333
3334 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && (A == Op0 || B == Op0)) {
3335 // A == (A^B) -> B == 0
3336 Value *OtherVal = A == Op0 ? B : A;
3337 return new ICmpInst(I.getPredicate(), OtherVal,
3338 Constant::getNullValue(A->getType()));
3339 }
3340
3341 // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
3342 if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) &&
3343 match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) {
3344 Value *X = nullptr, *Y = nullptr, *Z = nullptr;
3345
3346 if (A == C) {
3347 X = B;
3348 Y = D;
3349 Z = A;
3350 } else if (A == D) {
3351 X = B;
3352 Y = C;
3353 Z = A;
3354 } else if (B == C) {
3355 X = A;
3356 Y = D;
3357 Z = B;
3358 } else if (B == D) {
3359 X = A;
3360 Y = C;
3361 Z = B;
3362 }
3363
3364 if (X) { // Build (X^Y) & Z
3365 Op1 = Builder->CreateXor(X, Y);
3366 Op1 = Builder->CreateAnd(Op1, Z);
3367 I.setOperand(0, Op1);
3368 I.setOperand(1, Constant::getNullValue(Op1->getType()));
3369 return &I;
3370 }
3371 }
3372
3373 // Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B)
3374 // and (B & (1<<X)-1) == (zext A) --> A == (trunc B)
3375 ConstantInt *Cst1;
3376 if ((Op0->hasOneUse() && match(Op0, m_ZExt(m_Value(A))) &&
3377 match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) ||
3378 (Op1->hasOneUse() && match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) &&
3379 match(Op1, m_ZExt(m_Value(A))))) {
3380 APInt Pow2 = Cst1->getValue() + 1;
3381 if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) &&
3382 Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth())
3383 return new ICmpInst(I.getPredicate(), A,
3384 Builder->CreateTrunc(B, A->getType()));
3385 }
3386
3387 // (A >> C) == (B >> C) --> (A^B) u< (1 << C)
3388 // For lshr and ashr pairs.
3389 if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_ConstantInt(Cst1)))) &&
3390 match(Op1, m_OneUse(m_LShr(m_Value(B), m_Specific(Cst1))))) ||
3391 (match(Op0, m_OneUse(m_AShr(m_Value(A), m_ConstantInt(Cst1)))) &&
3392 match(Op1, m_OneUse(m_AShr(m_Value(B), m_Specific(Cst1)))))) {
3393 unsigned TypeBits = Cst1->getBitWidth();
3394 unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
3395 if (ShAmt < TypeBits && ShAmt != 0) {
3396 ICmpInst::Predicate Pred = I.getPredicate() == ICmpInst::ICMP_NE
3397 ? ICmpInst::ICMP_UGE
3398 : ICmpInst::ICMP_ULT;
3399 Value *Xor = Builder->CreateXor(A, B, I.getName() + ".unshifted");
3400 APInt CmpVal = APInt::getOneBitSet(TypeBits, ShAmt);
3401 return new ICmpInst(Pred, Xor, Builder->getInt(CmpVal));
3402 }
3403 }
3404
3405 // (A << C) == (B << C) --> ((A^B) & (~0U >> C)) == 0
3406 if (match(Op0, m_OneUse(m_Shl(m_Value(A), m_ConstantInt(Cst1)))) &&
3407 match(Op1, m_OneUse(m_Shl(m_Value(B), m_Specific(Cst1))))) {
3408 unsigned TypeBits = Cst1->getBitWidth();
3409 unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
3410 if (ShAmt < TypeBits && ShAmt != 0) {
3411 Value *Xor = Builder->CreateXor(A, B, I.getName() + ".unshifted");
3412 APInt AndVal = APInt::getLowBitsSet(TypeBits, TypeBits - ShAmt);
3413 Value *And = Builder->CreateAnd(Xor, Builder->getInt(AndVal),
3414 I.getName() + ".mask");
3415 return new ICmpInst(I.getPredicate(), And,
3416 Constant::getNullValue(Cst1->getType()));
3417 }
3418 }
3419
3420 // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to
3421 // "icmp (and X, mask), cst"
3422 uint64_t ShAmt = 0;
3423 if (Op0->hasOneUse() &&
3424 match(Op0, m_Trunc(m_OneUse(m_LShr(m_Value(A), m_ConstantInt(ShAmt))))) &&
3425 match(Op1, m_ConstantInt(Cst1)) &&
3426 // Only do this when A has multiple uses. This is most important to do
3427 // when it exposes other optimizations.
3428 !A->hasOneUse()) {
3429 unsigned ASize = cast<IntegerType>(A->getType())->getPrimitiveSizeInBits();
3430
3431 if (ShAmt < ASize) {
3432 APInt MaskV =
3433 APInt::getLowBitsSet(ASize, Op0->getType()->getPrimitiveSizeInBits());
3434 MaskV <<= ShAmt;
3435
3436 APInt CmpV = Cst1->getValue().zext(ASize);
3437 CmpV <<= ShAmt;
3438
3439 Value *Mask = Builder->CreateAnd(A, Builder->getInt(MaskV));
3440 return new ICmpInst(I.getPredicate(), Mask, Builder->getInt(CmpV));
3441 }
3442 }
3443
3444 return nullptr;
3445}
3446
3447/// Handle icmp (cast x to y), (cast/cst). We only handle extending casts so
3448/// far.
3449Instruction *InstCombiner::foldICmpWithCastAndCast(ICmpInst &ICmp) {
3450 const CastInst *LHSCI = cast<CastInst>(ICmp.getOperand(0));
3451 Value *LHSCIOp = LHSCI->getOperand(0);
3452 Type *SrcTy = LHSCIOp->getType();
3453 Type *DestTy = LHSCI->getType();
3454 Value *RHSCIOp;
3455
3456 // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
3457 // integer type is the same size as the pointer type.
3458 if (LHSCI->getOpcode() == Instruction::PtrToInt &&
3459 DL.getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth()) {
3460 Value *RHSOp = nullptr;
3461 if (auto *RHSC = dyn_cast<PtrToIntOperator>(ICmp.getOperand(1))) {
3462 Value *RHSCIOp = RHSC->getOperand(0);
3463 if (RHSCIOp->getType()->getPointerAddressSpace() ==
3464 LHSCIOp->getType()->getPointerAddressSpace()) {
3465 RHSOp = RHSC->getOperand(0);
3466 // If the pointer types don't match, insert a bitcast.
3467 if (LHSCIOp->getType() != RHSOp->getType())
3468 RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
3469 }
3470 } else if (auto *RHSC = dyn_cast<Constant>(ICmp.getOperand(1))) {
3471 RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
3472 }
3473
3474 if (RHSOp)
3475 return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSOp);
3476 }
3477
3478 // The code below only handles extension cast instructions, so far.
3479 // Enforce this.
3480 if (LHSCI->getOpcode() != Instruction::ZExt &&
3481 LHSCI->getOpcode() != Instruction::SExt)
3482 return nullptr;
3483
3484 bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
3485 bool isSignedCmp = ICmp.isSigned();
3486
3487 if (auto *CI = dyn_cast<CastInst>(ICmp.getOperand(1))) {
3488 // Not an extension from the same type?
3489 RHSCIOp = CI->getOperand(0);
3490 if (RHSCIOp->getType() != LHSCIOp->getType())
3491 return nullptr;
3492
3493 // If the signedness of the two casts doesn't agree (i.e. one is a sext
3494 // and the other is a zext), then we can't handle this.
3495 if (CI->getOpcode() != LHSCI->getOpcode())
3496 return nullptr;
3497
3498 // Deal with equality cases early.
3499 if (ICmp.isEquality())
3500 return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSCIOp);
3501
3502 // A signed comparison of sign extended values simplifies into a
3503 // signed comparison.
3504 if (isSignedCmp && isSignedExt)
3505 return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSCIOp);
3506
3507 // The other three cases all fold into an unsigned comparison.
3508 return new ICmpInst(ICmp.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
3509 }
3510
3511 // If we aren't dealing with a constant on the RHS, exit early.
3512 auto *C = dyn_cast<Constant>(ICmp.getOperand(1));
3513 if (!C)
3514 return nullptr;
3515
3516 // Compute the constant that would happen if we truncated to SrcTy then
3517 // re-extended to DestTy.
3518 Constant *Res1 = ConstantExpr::getTrunc(C, SrcTy);
3519 Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
3520
3521 // If the re-extended constant didn't change...
3522 if (Res2 == C) {
3523 // Deal with equality cases early.
3524 if (ICmp.isEquality())
3525 return new ICmpInst(ICmp.getPredicate(), LHSCIOp, Res1);
3526
3527 // A signed comparison of sign extended values simplifies into a
3528 // signed comparison.
3529 if (isSignedExt && isSignedCmp)
3530 return new ICmpInst(ICmp.getPredicate(), LHSCIOp, Res1);
3531
3532 // The other three cases all fold into an unsigned comparison.
3533 return new ICmpInst(ICmp.getUnsignedPredicate(), LHSCIOp, Res1);
3534 }
3535
3536 // The re-extended constant changed, partly changed (in the case of a vector),
3537 // or could not be determined to be equal (in the case of a constant
3538 // expression), so the constant cannot be represented in the shorter type.
3539 // Consequently, we cannot emit a simple comparison.
3540 // All the cases that fold to true or false will have already been handled
3541 // by SimplifyICmpInst, so only deal with the tricky case.
3542
3543 if (isSignedCmp || !isSignedExt || !isa<ConstantInt>(C))
3544 return nullptr;
3545
3546 // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
3547 // should have been folded away previously and not enter in here.
3548
3549 // We're performing an unsigned comp with a sign extended value.
3550 // This is true if the input is >= 0. [aka >s -1]
3551 Constant *NegOne = Constant::getAllOnesValue(SrcTy);
3552 Value *Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICmp.getName());
3553
3554 // Finally, return the value computed.
3555 if (ICmp.getPredicate() == ICmpInst::ICMP_ULT)
3556 return replaceInstUsesWith(ICmp, Result);
3557
3558 assert(ICmp.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!")((ICmp.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!"
) ? static_cast<void> (0) : __assert_fail ("ICmp.getPredicate() == ICmpInst::ICMP_UGT && \"ICmp should be folded!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3558, __PRETTY_FUNCTION__));
3559 return BinaryOperator::CreateNot(Result);
3560}
3561
3562bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
3563 Value *RHS, Instruction &OrigI,
3564 Value *&Result, Constant *&Overflow) {
3565 if (OrigI.isCommutative() && isa<Constant>(LHS) && !isa<Constant>(RHS))
3566 std::swap(LHS, RHS);
3567
3568 auto SetResult = [&](Value *OpResult, Constant *OverflowVal, bool ReuseName) {
3569 Result = OpResult;
3570 Overflow = OverflowVal;
3571 if (ReuseName)
3572 Result->takeName(&OrigI);
3573 return true;
3574 };
3575
3576 // If the overflow check was an add followed by a compare, the insertion point
3577 // may be pointing to the compare. We want to insert the new instructions
3578 // before the add in case there are uses of the add between the add and the
3579 // compare.
3580 Builder->SetInsertPoint(&OrigI);
3581
3582 switch (OCF) {
3583 case OCF_INVALID:
3584 llvm_unreachable("bad overflow check kind!")::llvm::llvm_unreachable_internal("bad overflow check kind!",
"/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3584);
3585
3586 case OCF_UNSIGNED_ADD: {
3587 OverflowResult OR = computeOverflowForUnsignedAdd(LHS, RHS, &OrigI);
3588 if (OR == OverflowResult::NeverOverflows)
3589 return SetResult(Builder->CreateNUWAdd(LHS, RHS), Builder->getFalse(),
3590 true);
3591
3592 if (OR == OverflowResult::AlwaysOverflows)
3593 return SetResult(Builder->CreateAdd(LHS, RHS), Builder->getTrue(), true);
3594
3595 // Fall through uadd into sadd
3596 LLVM_FALLTHROUGH[[clang::fallthrough]];
3597 }
3598 case OCF_SIGNED_ADD: {
3599 // X + 0 -> {X, false}
3600 if (match(RHS, m_Zero()))
3601 return SetResult(LHS, Builder->getFalse(), false);
3602
3603 // We can strength reduce this signed add into a regular add if we can prove
3604 // that it will never overflow.
3605 if (OCF == OCF_SIGNED_ADD)
3606 if (willNotOverflowSignedAdd(LHS, RHS, OrigI))
3607 return SetResult(Builder->CreateNSWAdd(LHS, RHS), Builder->getFalse(),
3608 true);
3609 break;
3610 }
3611
3612 case OCF_UNSIGNED_SUB:
3613 case OCF_SIGNED_SUB: {
3614 // X - 0 -> {X, false}
3615 if (match(RHS, m_Zero()))
3616 return SetResult(LHS, Builder->getFalse(), false);
3617
3618 if (OCF == OCF_SIGNED_SUB) {
3619 if (willNotOverflowSignedSub(LHS, RHS, OrigI))
3620 return SetResult(Builder->CreateNSWSub(LHS, RHS), Builder->getFalse(),
3621 true);
3622 } else {
3623 if (willNotOverflowUnsignedSub(LHS, RHS, OrigI))
3624 return SetResult(Builder->CreateNUWSub(LHS, RHS), Builder->getFalse(),
3625 true);
3626 }
3627 break;
3628 }
3629
3630 case OCF_UNSIGNED_MUL: {
3631 OverflowResult OR = computeOverflowForUnsignedMul(LHS, RHS, &OrigI);
3632 if (OR == OverflowResult::NeverOverflows)
3633 return SetResult(Builder->CreateNUWMul(LHS, RHS), Builder->getFalse(),
3634 true);
3635 if (OR == OverflowResult::AlwaysOverflows)
3636 return SetResult(Builder->CreateMul(LHS, RHS), Builder->getTrue(), true);
3637 LLVM_FALLTHROUGH[[clang::fallthrough]];
3638 }
3639 case OCF_SIGNED_MUL:
3640 // X * undef -> undef
3641 if (isa<UndefValue>(RHS))
3642 return SetResult(RHS, UndefValue::get(Builder->getInt1Ty()), false);
3643
3644 // X * 0 -> {0, false}
3645 if (match(RHS, m_Zero()))
3646 return SetResult(RHS, Builder->getFalse(), false);
3647
3648 // X * 1 -> {X, false}
3649 if (match(RHS, m_One()))
3650 return SetResult(LHS, Builder->getFalse(), false);
3651
3652 if (OCF == OCF_SIGNED_MUL)
3653 if (willNotOverflowSignedMul(LHS, RHS, OrigI))
3654 return SetResult(Builder->CreateNSWMul(LHS, RHS), Builder->getFalse(),
3655 true);
3656 break;
3657 }
3658
3659 return false;
3660}
3661
3662/// \brief Recognize and process idiom involving test for multiplication
3663/// overflow.
3664///
3665/// The caller has matched a pattern of the form:
3666/// I = cmp u (mul(zext A, zext B), V
3667/// The function checks if this is a test for overflow and if so replaces
3668/// multiplication with call to 'mul.with.overflow' intrinsic.
3669///
3670/// \param I Compare instruction.
3671/// \param MulVal Result of 'mult' instruction. It is one of the arguments of
3672/// the compare instruction. Must be of integer type.
3673/// \param OtherVal The other argument of compare instruction.
3674/// \returns Instruction which must replace the compare instruction, NULL if no
3675/// replacement required.
3676static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal,
3677 Value *OtherVal, InstCombiner &IC) {
3678 // Don't bother doing this transformation for pointers, don't do it for
3679 // vectors.
3680 if (!isa<IntegerType>(MulVal->getType()))
3681 return nullptr;
3682
3683 assert(I.getOperand(0) == MulVal || I.getOperand(1) == MulVal)((I.getOperand(0) == MulVal || I.getOperand(1) == MulVal) ? static_cast
<void> (0) : __assert_fail ("I.getOperand(0) == MulVal || I.getOperand(1) == MulVal"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3683, __PRETTY_FUNCTION__));
3684 assert(I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal)((I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal)
? static_cast<void> (0) : __assert_fail ("I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3684, __PRETTY_FUNCTION__));
3685 auto *MulInstr = dyn_cast<Instruction>(MulVal);
3686 if (!MulInstr)
3687 return nullptr;
3688 assert(MulInstr->getOpcode() == Instruction::Mul)((MulInstr->getOpcode() == Instruction::Mul) ? static_cast
<void> (0) : __assert_fail ("MulInstr->getOpcode() == Instruction::Mul"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3688, __PRETTY_FUNCTION__));
3689
3690 auto *LHS = cast<ZExtOperator>(MulInstr->getOperand(0)),
3691 *RHS = cast<ZExtOperator>(MulInstr->getOperand(1));
3692 assert(LHS->getOpcode() == Instruction::ZExt)((LHS->getOpcode() == Instruction::ZExt) ? static_cast<
void> (0) : __assert_fail ("LHS->getOpcode() == Instruction::ZExt"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3692, __PRETTY_FUNCTION__));
3693 assert(RHS->getOpcode() == Instruction::ZExt)((RHS->getOpcode() == Instruction::ZExt) ? static_cast<
void> (0) : __assert_fail ("RHS->getOpcode() == Instruction::ZExt"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3693, __PRETTY_FUNCTION__));
3694 Value *A = LHS->getOperand(0), *B = RHS->getOperand(0);
3695
3696 // Calculate type and width of the result produced by mul.with.overflow.
3697 Type *TyA = A->getType(), *TyB = B->getType();
3698 unsigned WidthA = TyA->getPrimitiveSizeInBits(),
3699 WidthB = TyB->getPrimitiveSizeInBits();
3700 unsigned MulWidth;
3701 Type *MulType;
3702 if (WidthB > WidthA) {
3703 MulWidth = WidthB;
3704 MulType = TyB;
3705 } else {
3706 MulWidth = WidthA;
3707 MulType = TyA;
3708 }
3709
3710 // In order to replace the original mul with a narrower mul.with.overflow,
3711 // all uses must ignore upper bits of the product. The number of used low
3712 // bits must be not greater than the width of mul.with.overflow.
3713 if (MulVal->hasNUsesOrMore(2))
3714 for (User *U : MulVal->users()) {
3715 if (U == &I)
3716 continue;
3717 if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
3718 // Check if truncation ignores bits above MulWidth.
3719 unsigned TruncWidth = TI->getType()->getPrimitiveSizeInBits();
3720 if (TruncWidth > MulWidth)
3721 return nullptr;
3722 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
3723 // Check if AND ignores bits above MulWidth.
3724 if (BO->getOpcode() != Instruction::And)
3725 return nullptr;
3726 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3727 const APInt &CVal = CI->getValue();
3728 if (CVal.getBitWidth() - CVal.countLeadingZeros() > MulWidth)
3729 return nullptr;
3730 }
3731 } else {
3732 // Other uses prohibit this transformation.
3733 return nullptr;
3734 }
3735 }
3736
3737 // Recognize patterns
3738 switch (I.getPredicate()) {
3739 case ICmpInst::ICMP_EQ:
3740 case ICmpInst::ICMP_NE:
3741 // Recognize pattern:
3742 // mulval = mul(zext A, zext B)
3743 // cmp eq/neq mulval, zext trunc mulval
3744 if (ZExtInst *Zext = dyn_cast<ZExtInst>(OtherVal))
3745 if (Zext->hasOneUse()) {
3746 Value *ZextArg = Zext->getOperand(0);
3747 if (TruncInst *Trunc = dyn_cast<TruncInst>(ZextArg))
3748 if (Trunc->getType()->getPrimitiveSizeInBits() == MulWidth)
3749 break; //Recognized
3750 }
3751
3752 // Recognize pattern:
3753 // mulval = mul(zext A, zext B)
3754 // cmp eq/neq mulval, and(mulval, mask), mask selects low MulWidth bits.
3755 ConstantInt *CI;
3756 Value *ValToMask;
3757 if (match(OtherVal, m_And(m_Value(ValToMask), m_ConstantInt(CI)))) {
3758 if (ValToMask != MulVal)
3759 return nullptr;
3760 const APInt &CVal = CI->getValue() + 1;
3761 if (CVal.isPowerOf2()) {
3762 unsigned MaskWidth = CVal.logBase2();
3763 if (MaskWidth == MulWidth)
3764 break; // Recognized
3765 }
3766 }
3767 return nullptr;
3768
3769 case ICmpInst::ICMP_UGT:
3770 // Recognize pattern:
3771 // mulval = mul(zext A, zext B)
3772 // cmp ugt mulval, max
3773 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
3774 APInt MaxVal = APInt::getMaxValue(MulWidth);
3775 MaxVal = MaxVal.zext(CI->getBitWidth());
3776 if (MaxVal.eq(CI->getValue()))
3777 break; // Recognized
3778 }
3779 return nullptr;
3780
3781 case ICmpInst::ICMP_UGE:
3782 // Recognize pattern:
3783 // mulval = mul(zext A, zext B)
3784 // cmp uge mulval, max+1
3785 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
3786 APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
3787 if (MaxVal.eq(CI->getValue()))
3788 break; // Recognized
3789 }
3790 return nullptr;
3791
3792 case ICmpInst::ICMP_ULE:
3793 // Recognize pattern:
3794 // mulval = mul(zext A, zext B)
3795 // cmp ule mulval, max
3796 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
3797 APInt MaxVal = APInt::getMaxValue(MulWidth);
3798 MaxVal = MaxVal.zext(CI->getBitWidth());
3799 if (MaxVal.eq(CI->getValue()))
3800 break; // Recognized
3801 }
3802 return nullptr;
3803
3804 case ICmpInst::ICMP_ULT:
3805 // Recognize pattern:
3806 // mulval = mul(zext A, zext B)
3807 // cmp ule mulval, max + 1
3808 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
3809 APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
3810 if (MaxVal.eq(CI->getValue()))
3811 break; // Recognized
3812 }
3813 return nullptr;
3814
3815 default:
3816 return nullptr;
3817 }
3818
3819 InstCombiner::BuilderTy *Builder = IC.Builder;
3820 Builder->SetInsertPoint(MulInstr);
3821
3822 // Replace: mul(zext A, zext B) --> mul.with.overflow(A, B)
3823 Value *MulA = A, *MulB = B;
3824 if (WidthA < MulWidth)
3825 MulA = Builder->CreateZExt(A, MulType);
3826 if (WidthB < MulWidth)
3827 MulB = Builder->CreateZExt(B, MulType);
3828 Value *F = Intrinsic::getDeclaration(I.getModule(),
3829 Intrinsic::umul_with_overflow, MulType);
3830 CallInst *Call = Builder->CreateCall(F, {MulA, MulB}, "umul");
3831 IC.Worklist.Add(MulInstr);
3832
3833 // If there are uses of mul result other than the comparison, we know that
3834 // they are truncation or binary AND. Change them to use result of
3835 // mul.with.overflow and adjust properly mask/size.
3836 if (MulVal->hasNUsesOrMore(2)) {
3837 Value *Mul = Builder->CreateExtractValue(Call, 0, "umul.value");
3838 for (User *U : MulVal->users()) {
3839 if (U == &I || U == OtherVal)
3840 continue;
3841 if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
3842 if (TI->getType()->getPrimitiveSizeInBits() == MulWidth)
3843 IC.replaceInstUsesWith(*TI, Mul);
3844 else
3845 TI->setOperand(0, Mul);
3846 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
3847 assert(BO->getOpcode() == Instruction::And)((BO->getOpcode() == Instruction::And) ? static_cast<void
> (0) : __assert_fail ("BO->getOpcode() == Instruction::And"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3847, __PRETTY_FUNCTION__));
3848 // Replace (mul & mask) --> zext (mul.with.overflow & short_mask)
3849 ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));
3850 APInt ShortMask = CI->getValue().trunc(MulWidth);
3851 Value *ShortAnd = Builder->CreateAnd(Mul, ShortMask);
3852 Instruction *Zext =
3853 cast<Instruction>(Builder->CreateZExt(ShortAnd, BO->getType()));
3854 IC.Worklist.Add(Zext);
3855 IC.replaceInstUsesWith(*BO, Zext);
3856 } else {
3857 llvm_unreachable("Unexpected Binary operation")::llvm::llvm_unreachable_internal("Unexpected Binary operation"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3857);
3858 }
3859 IC.Worklist.Add(cast<Instruction>(U));
3860 }
3861 }
3862 if (isa<Instruction>(OtherVal))
3863 IC.Worklist.Add(cast<Instruction>(OtherVal));
3864
3865 // The original icmp gets replaced with the overflow value, maybe inverted
3866 // depending on predicate.
3867 bool Inverse = false;
3868 switch (I.getPredicate()) {
3869 case ICmpInst::ICMP_NE:
3870 break;
3871 case ICmpInst::ICMP_EQ:
3872 Inverse = true;
3873 break;
3874 case ICmpInst::ICMP_UGT:
3875 case ICmpInst::ICMP_UGE:
3876 if (I.getOperand(0) == MulVal)
3877 break;
3878 Inverse = true;
3879 break;
3880 case ICmpInst::ICMP_ULT:
3881 case ICmpInst::ICMP_ULE:
3882 if (I.getOperand(1) == MulVal)
3883 break;
3884 Inverse = true;
3885 break;
3886 default:
3887 llvm_unreachable("Unexpected predicate")::llvm::llvm_unreachable_internal("Unexpected predicate", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3887);
3888 }
3889 if (Inverse) {
3890 Value *Res = Builder->CreateExtractValue(Call, 1);
3891 return BinaryOperator::CreateNot(Res);
3892 }
3893
3894 return ExtractValueInst::Create(Call, 1);
3895}
3896
3897/// When performing a comparison against a constant, it is possible that not all
3898/// the bits in the LHS are demanded. This helper method computes the mask that
3899/// IS demanded.
3900static APInt getDemandedBitsLHSMask(ICmpInst &I, unsigned BitWidth,
3901 bool isSignCheck) {
3902 if (isSignCheck)
3903 return APInt::getSignMask(BitWidth);
3904
3905 ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(1));
3906 if (!CI) return APInt::getAllOnesValue(BitWidth);
3907 const APInt &RHS = CI->getValue();
3908
3909 switch (I.getPredicate()) {
3910 // For a UGT comparison, we don't care about any bits that
3911 // correspond to the trailing ones of the comparand. The value of these
3912 // bits doesn't impact the outcome of the comparison, because any value
3913 // greater than the RHS must differ in a bit higher than these due to carry.
3914 case ICmpInst::ICMP_UGT: {
3915 unsigned trailingOnes = RHS.countTrailingOnes();
3916 return APInt::getBitsSetFrom(BitWidth, trailingOnes);
3917 }
3918
3919 // Similarly, for a ULT comparison, we don't care about the trailing zeros.
3920 // Any value less than the RHS must differ in a higher bit because of carries.
3921 case ICmpInst::ICMP_ULT: {
3922 unsigned trailingZeros = RHS.countTrailingZeros();
3923 return APInt::getBitsSetFrom(BitWidth, trailingZeros);
3924 }
3925
3926 default:
3927 return APInt::getAllOnesValue(BitWidth);
3928 }
3929}
3930
3931/// \brief Check if the order of \p Op0 and \p Op1 as operand in an ICmpInst
3932/// should be swapped.
3933/// The decision is based on how many times these two operands are reused
3934/// as subtract operands and their positions in those instructions.
3935/// The rational is that several architectures use the same instruction for
3936/// both subtract and cmp, thus it is better if the order of those operands
3937/// match.
3938/// \return true if Op0 and Op1 should be swapped.
3939static bool swapMayExposeCSEOpportunities(const Value * Op0,
3940 const Value * Op1) {
3941 // Filter out pointer value as those cannot appears directly in subtract.
3942 // FIXME: we may want to go through inttoptrs or bitcasts.
3943 if (Op0->getType()->isPointerTy())
3944 return false;
3945 // Count every uses of both Op0 and Op1 in a subtract.
3946 // Each time Op0 is the first operand, count -1: swapping is bad, the
3947 // subtract has already the same layout as the compare.
3948 // Each time Op0 is the second operand, count +1: swapping is good, the
3949 // subtract has a different layout as the compare.
3950 // At the end, if the benefit is greater than 0, Op0 should come second to
3951 // expose more CSE opportunities.
3952 int GlobalSwapBenefits = 0;
3953 for (const User *U : Op0->users()) {
3954 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(U);
3955 if (!BinOp || BinOp->getOpcode() != Instruction::Sub)
3956 continue;
3957 // If Op0 is the first argument, this is not beneficial to swap the
3958 // arguments.
3959 int LocalSwapBenefits = -1;
3960 unsigned Op1Idx = 1;
3961 if (BinOp->getOperand(Op1Idx) == Op0) {
3962 Op1Idx = 0;
3963 LocalSwapBenefits = 1;
3964 }
3965 if (BinOp->getOperand(Op1Idx) != Op1)
3966 continue;
3967 GlobalSwapBenefits += LocalSwapBenefits;
3968 }
3969 return GlobalSwapBenefits > 0;
3970}
3971
3972/// \brief Check that one use is in the same block as the definition and all
3973/// other uses are in blocks dominated by a given block.
3974///
3975/// \param DI Definition
3976/// \param UI Use
3977/// \param DB Block that must dominate all uses of \p DI outside
3978/// the parent block
3979/// \return true when \p UI is the only use of \p DI in the parent block
3980/// and all other uses of \p DI are in blocks dominated by \p DB.
3981///
3982bool InstCombiner::dominatesAllUses(const Instruction *DI,
3983 const Instruction *UI,
3984 const BasicBlock *DB) const {
3985 assert(DI && UI && "Instruction not defined\n")((DI && UI && "Instruction not defined\n") ? static_cast
<void> (0) : __assert_fail ("DI && UI && \"Instruction not defined\\n\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3985, __PRETTY_FUNCTION__));
3986 // Ignore incomplete definitions.
3987 if (!DI->getParent())
3988 return false;
3989 // DI and UI must be in the same block.
3990 if (DI->getParent() != UI->getParent())
3991 return false;
3992 // Protect from self-referencing blocks.
3993 if (DI->getParent() == DB)
3994 return false;
3995 for (const User *U : DI->users()) {
3996 auto *Usr = cast<Instruction>(U);
3997 if (Usr != UI && !DT.dominates(DB, Usr->getParent()))
3998 return false;
3999 }
4000 return true;
4001}
4002
4003/// Return true when the instruction sequence within a block is select-cmp-br.
4004static bool isChainSelectCmpBranch(const SelectInst *SI) {
4005 const BasicBlock *BB = SI->getParent();
4006 if (!BB)
4007 return false;
4008 auto *BI = dyn_cast_or_null<BranchInst>(BB->getTerminator());
4009 if (!BI || BI->getNumSuccessors() != 2)
4010 return false;
4011 auto *IC = dyn_cast<ICmpInst>(BI->getCondition());
4012 if (!IC || (IC->getOperand(0) != SI && IC->getOperand(1) != SI))
4013 return false;
4014 return true;
4015}
4016
4017/// \brief True when a select result is replaced by one of its operands
4018/// in select-icmp sequence. This will eventually result in the elimination
4019/// of the select.
4020///
4021/// \param SI Select instruction
4022/// \param Icmp Compare instruction
4023/// \param SIOpd Operand that replaces the select
4024///
4025/// Notes:
4026/// - The replacement is global and requires dominator information
4027/// - The caller is responsible for the actual replacement
4028///
4029/// Example:
4030///
4031/// entry:
4032/// %4 = select i1 %3, %C* %0, %C* null
4033/// %5 = icmp eq %C* %4, null
4034/// br i1 %5, label %9, label %7
4035/// ...
4036/// ; <label>:7 ; preds = %entry
4037/// %8 = getelementptr inbounds %C* %4, i64 0, i32 0
4038/// ...
4039///
4040/// can be transformed to
4041///
4042/// %5 = icmp eq %C* %0, null
4043/// %6 = select i1 %3, i1 %5, i1 true
4044/// br i1 %6, label %9, label %7
4045/// ...
4046/// ; <label>:7 ; preds = %entry
4047/// %8 = getelementptr inbounds %C* %0, i64 0, i32 0 // replace by %0!
4048///
4049/// Similar when the first operand of the select is a constant or/and
4050/// the compare is for not equal rather than equal.
4051///
4052/// NOTE: The function is only called when the select and compare constants
4053/// are equal, the optimization can work only for EQ predicates. This is not a
4054/// major restriction since a NE compare should be 'normalized' to an equal
4055/// compare, which usually happens in the combiner and test case
4056/// select-cmp-br.ll checks for it.
4057bool InstCombiner::replacedSelectWithOperand(SelectInst *SI,
4058 const ICmpInst *Icmp,
4059 const unsigned SIOpd) {
4060 assert((SIOpd == 1 || SIOpd == 2) && "Invalid select operand!")(((SIOpd == 1 || SIOpd == 2) && "Invalid select operand!"
) ? static_cast<void> (0) : __assert_fail ("(SIOpd == 1 || SIOpd == 2) && \"Invalid select operand!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4060, __PRETTY_FUNCTION__));
4061 if (isChainSelectCmpBranch(SI) && Icmp->getPredicate() == ICmpInst::ICMP_EQ) {
4062 BasicBlock *Succ = SI->getParent()->getTerminator()->getSuccessor(1);
4063 // The check for the single predecessor is not the best that can be
4064 // done. But it protects efficiently against cases like when SI's
4065 // home block has two successors, Succ and Succ1, and Succ1 predecessor
4066 // of Succ. Then SI can't be replaced by SIOpd because the use that gets
4067 // replaced can be reached on either path. So the uniqueness check
4068 // guarantees that the path all uses of SI (outside SI's parent) are on
4069 // is disjoint from all other paths out of SI. But that information
4070 // is more expensive to compute, and the trade-off here is in favor
4071 // of compile-time. It should also be noticed that we check for a single
4072 // predecessor and not only uniqueness. This to handle the situation when
4073 // Succ and Succ1 points to the same basic block.
4074 if (Succ->getSinglePredecessor() && dominatesAllUses(SI, Icmp, Succ)) {
4075 NumSel++;
4076 SI->replaceUsesOutsideBlock(SI->getOperand(SIOpd), SI->getParent());
4077 return true;
4078 }
4079 }
4080 return false;
4081}
4082
4083/// Try to fold the comparison based on range information we can get by checking
4084/// whether bits are known to be zero or one in the inputs.
4085Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) {
4086 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4087 Type *Ty = Op0->getType();
4088 ICmpInst::Predicate Pred = I.getPredicate();
4089
4090 // Get scalar or pointer size.
4091 unsigned BitWidth = Ty->isIntOrIntVectorTy()
4092 ? Ty->getScalarSizeInBits()
4093 : DL.getTypeSizeInBits(Ty->getScalarType());
4094
4095 if (!BitWidth)
4096 return nullptr;
4097
4098 // If this is a normal comparison, it demands all bits. If it is a sign bit
4099 // comparison, it only demands the sign bit.
4100 bool IsSignBit = false;
4101 const APInt *CmpC;
4102 if (match(Op1, m_APInt(CmpC))) {
4103 bool UnusedBit;
4104 IsSignBit = isSignBitCheck(Pred, *CmpC, UnusedBit);
4105 }
4106
4107 KnownBits Op0Known(BitWidth);
4108 KnownBits Op1Known(BitWidth);
4109
4110 if (SimplifyDemandedBits(&I, 0,
4111 getDemandedBitsLHSMask(I, BitWidth, IsSignBit),
4112 Op0Known, 0))
4113 return &I;
4114
4115 if (SimplifyDemandedBits(&I, 1, APInt::getAllOnesValue(BitWidth),
4116 Op1Known, 0))
4117 return &I;
4118
4119 // Given the known and unknown bits, compute a range that the LHS could be
4120 // in. Compute the Min, Max and RHS values based on the known bits. For the
4121 // EQ and NE we use unsigned values.
4122 APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
4123 APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
4124 if (I.isSigned()) {
4125 computeSignedMinMaxValuesFromKnownBits(Op0Known, Op0Min, Op0Max);
4126 computeSignedMinMaxValuesFromKnownBits(Op1Known, Op1Min, Op1Max);
4127 } else {
4128 computeUnsignedMinMaxValuesFromKnownBits(Op0Known, Op0Min, Op0Max);
4129 computeUnsignedMinMaxValuesFromKnownBits(Op1Known, Op1Min, Op1Max);
4130 }
4131
4132 // If Min and Max are known to be the same, then SimplifyDemandedBits
4133 // figured out that the LHS is a constant. Constant fold this now, so that
4134 // code below can assume that Min != Max.
4135 if (!isa<Constant>(Op0) && Op0Min == Op0Max)
4136 return new ICmpInst(Pred, ConstantInt::get(Op0->getType(), Op0Min), Op1);
4137 if (!isa<Constant>(Op1) && Op1Min == Op1Max)
4138 return new ICmpInst(Pred, Op0, ConstantInt::get(Op1->getType(), Op1Min));
4139
4140 // Based on the range information we know about the LHS, see if we can
4141 // simplify this comparison. For example, (x&4) < 8 is always true.
4142 switch (Pred) {
4143 default:
4144 llvm_unreachable("Unknown icmp opcode!")::llvm::llvm_unreachable_internal("Unknown icmp opcode!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4144);
4145 case ICmpInst::ICMP_EQ:
4146 case ICmpInst::ICMP_NE: {
4147 if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) {
4148 return Pred == CmpInst::ICMP_EQ
4149 ? replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()))
4150 : replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4151 }
4152
4153 // If all bits are known zero except for one, then we know at most one bit
4154 // is set. If the comparison is against zero, then this is a check to see if
4155 // *that* bit is set.
4156 APInt Op0KnownZeroInverted = ~Op0Known.Zero;
4157 if (Op1Known.isZero()) {
4158 // If the LHS is an AND with the same constant, look through it.
4159 Value *LHS = nullptr;
4160 const APInt *LHSC;
4161 if (!match(Op0, m_And(m_Value(LHS), m_APInt(LHSC))) ||
4162 *LHSC != Op0KnownZeroInverted)
4163 LHS = Op0;
4164
4165 Value *X;
4166 if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
4167 APInt ValToCheck = Op0KnownZeroInverted;
4168 Type *XTy = X->getType();
4169 if (ValToCheck.isPowerOf2()) {
4170 // ((1 << X) & 8) == 0 -> X != 3
4171 // ((1 << X) & 8) != 0 -> X == 3
4172 auto *CmpC = ConstantInt::get(XTy, ValToCheck.countTrailingZeros());
4173 auto NewPred = ICmpInst::getInversePredicate(Pred);
4174 return new ICmpInst(NewPred, X, CmpC);
4175 } else if ((++ValToCheck).isPowerOf2()) {
4176 // ((1 << X) & 7) == 0 -> X >= 3
4177 // ((1 << X) & 7) != 0 -> X < 3
4178 auto *CmpC = ConstantInt::get(XTy, ValToCheck.countTrailingZeros());
4179 auto NewPred =
4180 Pred == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGE : CmpInst::ICMP_ULT;
4181 return new ICmpInst(NewPred, X, CmpC);
4182 }
4183 }
4184
4185 // Check if the LHS is 8 >>u x and the result is a power of 2 like 1.
4186 const APInt *CI;
4187 if (Op0KnownZeroInverted.isOneValue() &&
4188 match(LHS, m_LShr(m_Power2(CI), m_Value(X)))) {
4189 // ((8 >>u X) & 1) == 0 -> X != 3
4190 // ((8 >>u X) & 1) != 0 -> X == 3
4191 unsigned CmpVal = CI->countTrailingZeros();
4192 auto NewPred = ICmpInst::getInversePredicate(Pred);
4193 return new ICmpInst(NewPred, X, ConstantInt::get(X->getType(), CmpVal));
4194 }
4195 }
4196 break;
4197 }
4198 case ICmpInst::ICMP_ULT: {
4199 if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
4200 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4201 if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
4202 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
4203 if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
4204 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4205
4206 const APInt *CmpC;
4207 if (match(Op1, m_APInt(CmpC))) {
4208 // A <u C -> A == C-1 if min(A)+1 == C
4209 if (Op1Max == Op0Min + 1) {
4210 Constant *CMinus1 = ConstantInt::get(Op0->getType(), *CmpC - 1);
4211 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, CMinus1);
4212 }
4213 }
4214 break;
4215 }
4216 case ICmpInst::ICMP_UGT: {
4217 if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
4218 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4219
4220 if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
4221 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
4222
4223 if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
4224 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4225
4226 const APInt *CmpC;
4227 if (match(Op1, m_APInt(CmpC))) {
4228 // A >u C -> A == C+1 if max(a)-1 == C
4229 if (*CmpC == Op0Max - 1)
4230 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
4231 ConstantInt::get(Op1->getType(), *CmpC + 1));
4232 }
4233 break;
4234 }
4235 case ICmpInst::ICMP_SLT:
4236 if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
4237 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4238 if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
4239 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
4240 if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
4241 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4242 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
4243 if (Op1Max == Op0Min + 1) // A <s C -> A == C-1 if min(A)+1 == C
4244 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
4245 Builder->getInt(CI->getValue() - 1));
4246 }
4247 break;
4248 case ICmpInst::ICMP_SGT:
4249 if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
4250 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4251 if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
4252 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
4253
4254 if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
4255 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
4256 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
4257 if (Op1Min == Op0Max - 1) // A >s C -> A == C+1 if max(A)-1 == C
4258 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
4259 Builder->getInt(CI->getValue() + 1));
4260 }
4261 break;
4262 case ICmpInst::ICMP_SGE:
4263 assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!")((!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantInt>(Op1) && \"ICMP_SGE with ConstantInt not folded!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4263, __PRETTY_FUNCTION__));
4264 if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
4265 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4266 if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
4267 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
4268 break;
4269 case ICmpInst::ICMP_SLE:
4270 assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!")((!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantInt>(Op1) && \"ICMP_SLE with ConstantInt not folded!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4270, __PRETTY_FUNCTION__));
4271 if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
4272 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4273 if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
4274 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
4275 break;
4276 case ICmpInst::ICMP_UGE:
4277 assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!")((!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantInt>(Op1) && \"ICMP_UGE with ConstantInt not folded!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4277, __PRETTY_FUNCTION__));
4278 if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
4279 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4280 if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
4281 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
4282 break;
4283 case ICmpInst::ICMP_ULE:
4284 assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!")((!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantInt>(Op1) && \"ICMP_ULE with ConstantInt not folded!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4284, __PRETTY_FUNCTION__));
4285 if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
4286 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4287 if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
4288 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
4289 break;
4290 }
4291
4292 // Turn a signed comparison into an unsigned one if both operands are known to
4293 // have the same sign.
4294 if (I.isSigned() &&
4295 ((Op0Known.Zero.isNegative() && Op1Known.Zero.isNegative()) ||
4296 (Op0Known.One.isNegative() && Op1Known.One.isNegative())))
4297 return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
4298
4299 return nullptr;
4300}
4301
4302/// If we have an icmp le or icmp ge instruction with a constant operand, turn
4303/// it into the appropriate icmp lt or icmp gt instruction. This transform
4304/// allows them to be folded in visitICmpInst.
4305static ICmpInst *canonicalizeCmpWithConstant(ICmpInst &I) {
4306 ICmpInst::Predicate Pred = I.getPredicate();
4307 if (Pred != ICmpInst::ICMP_SLE && Pred != ICmpInst::ICMP_SGE &&
4308 Pred != ICmpInst::ICMP_ULE && Pred != ICmpInst::ICMP_UGE)
4309 return nullptr;
4310
4311 Value *Op0 = I.getOperand(0);
4312 Value *Op1 = I.getOperand(1);
4313 auto *Op1C = dyn_cast<Constant>(Op1);
4314 if (!Op1C)
4315 return nullptr;
4316
4317 // Check if the constant operand can be safely incremented/decremented without
4318 // overflowing/underflowing. For scalars, SimplifyICmpInst has already handled
4319 // the edge cases for us, so we just assert on them. For vectors, we must
4320 // handle the edge cases.
4321 Type *Op1Type = Op1->getType();
4322 bool IsSigned = I.isSigned();
4323 bool IsLE = (Pred == ICmpInst::ICMP_SLE || Pred == ICmpInst::ICMP_ULE);
4324 auto *CI = dyn_cast<ConstantInt>(Op1C);
4325 if (CI) {
4326 // A <= MAX -> TRUE ; A >= MIN -> TRUE
4327 assert(IsLE ? !CI->isMaxValue(IsSigned) : !CI->isMinValue(IsSigned))((IsLE ? !CI->isMaxValue(IsSigned) : !CI->isMinValue(IsSigned
)) ? static_cast<void> (0) : __assert_fail ("IsLE ? !CI->isMaxValue(IsSigned) : !CI->isMinValue(IsSigned)"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4327, __PRETTY_FUNCTION__));
4328 } else if (Op1Type->isVectorTy()) {
4329 // TODO? If the edge cases for vectors were guaranteed to be handled as they
4330 // are for scalar, we could remove the min/max checks. However, to do that,
4331 // we would have to use insertelement/shufflevector to replace edge values.
4332 unsigned NumElts = Op1Type->getVectorNumElements();
4333 for (unsigned i = 0; i != NumElts; ++i) {
4334 Constant *Elt = Op1C->getAggregateElement(i);
4335 if (!Elt)
4336 return nullptr;
4337
4338 if (isa<UndefValue>(Elt))
4339 continue;
4340
4341 // Bail out if we can't determine if this constant is min/max or if we
4342 // know that this constant is min/max.
4343 auto *CI = dyn_cast<ConstantInt>(Elt);
4344 if (!CI || (IsLE ? CI->isMaxValue(IsSigned) : CI->isMinValue(IsSigned)))
4345 return nullptr;
4346 }
4347 } else {
4348 // ConstantExpr?
4349 return nullptr;
4350 }
4351
4352 // Increment or decrement the constant and set the new comparison predicate:
4353 // ULE -> ULT ; UGE -> UGT ; SLE -> SLT ; SGE -> SGT
4354 Constant *OneOrNegOne = ConstantInt::get(Op1Type, IsLE ? 1 : -1, true);
4355 CmpInst::Predicate NewPred = IsLE ? ICmpInst::ICMP_ULT: ICmpInst::ICMP_UGT;
4356 NewPred = IsSigned ? ICmpInst::getSignedPredicate(NewPred) : NewPred;
4357 return new ICmpInst(NewPred, Op0, ConstantExpr::getAdd(Op1C, OneOrNegOne));
4358}
4359
4360/// Integer compare with boolean values can always be turned into bitwise ops.
4361static Instruction *canonicalizeICmpBool(ICmpInst &I,
4362 InstCombiner::BuilderTy &Builder) {
4363 Value *A = I.getOperand(0), *B = I.getOperand(1);
4364 assert(A->getType()->getScalarType()->isIntegerTy(1) && "Bools only")((A->getType()->getScalarType()->isIntegerTy(1) &&
"Bools only") ? static_cast<void> (0) : __assert_fail (
"A->getType()->getScalarType()->isIntegerTy(1) && \"Bools only\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4364, __PRETTY_FUNCTION__));
4365
4366 // A boolean compared to true/false can be simplified to Op0/true/false in
4367 // 14 out of the 20 (10 predicates * 2 constants) possible combinations.
4368 // Cases not handled by InstSimplify are always 'not' of Op0.
4369 if (match(B, m_Zero())) {
4370 switch (I.getPredicate()) {
4371 case CmpInst::ICMP_EQ: // A == 0 -> !A
4372 case CmpInst::ICMP_ULE: // A <=u 0 -> !A
4373 case CmpInst::ICMP_SGE: // A >=s 0 -> !A
4374 return BinaryOperator::CreateNot(A);
4375 default:
4376 llvm_unreachable("ICmp i1 X, C not simplified as expected.")::llvm::llvm_unreachable_internal("ICmp i1 X, C not simplified as expected."
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4376);
4377 }
4378 } else if (match(B, m_One())) {
4379 switch (I.getPredicate()) {
4380 case CmpInst::ICMP_NE: // A != 1 -> !A
4381 case CmpInst::ICMP_ULT: // A <u 1 -> !A
4382 case CmpInst::ICMP_SGT: // A >s -1 -> !A
4383 return BinaryOperator::CreateNot(A);
4384 default:
4385 llvm_unreachable("ICmp i1 X, C not simplified as expected.")::llvm::llvm_unreachable_internal("ICmp i1 X, C not simplified as expected."
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4385);
4386 }
4387 }
4388
4389 switch (I.getPredicate()) {
4390 default:
4391 llvm_unreachable("Invalid icmp instruction!")::llvm::llvm_unreachable_internal("Invalid icmp instruction!"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4391);
4392 case ICmpInst::ICMP_EQ:
4393 // icmp eq i1 A, B -> ~(A ^ B)
4394 return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
4395
4396 case ICmpInst::ICMP_NE:
4397 // icmp ne i1 A, B -> A ^ B
4398 return BinaryOperator::CreateXor(A, B);
4399
4400 case ICmpInst::ICMP_UGT:
4401 // icmp ugt -> icmp ult
4402 std::swap(A, B);
4403 LLVM_FALLTHROUGH[[clang::fallthrough]];
4404 case ICmpInst::ICMP_ULT:
4405 // icmp ult i1 A, B -> ~A & B
4406 return BinaryOperator::CreateAnd(Builder.CreateNot(A), B);
4407
4408 case ICmpInst::ICMP_SGT:
4409 // icmp sgt -> icmp slt
4410 std::swap(A, B);
4411 LLVM_FALLTHROUGH[[clang::fallthrough]];
4412 case ICmpInst::ICMP_SLT:
4413 // icmp slt i1 A, B -> A & ~B
4414 return BinaryOperator::CreateAnd(Builder.CreateNot(B), A);
4415
4416 case ICmpInst::ICMP_UGE:
4417 // icmp uge -> icmp ule
4418 std::swap(A, B);
4419 LLVM_FALLTHROUGH[[clang::fallthrough]];
4420 case ICmpInst::ICMP_ULE:
4421 // icmp ule i1 A, B -> ~A | B
4422 return BinaryOperator::CreateOr(Builder.CreateNot(A), B);
4423
4424 case ICmpInst::ICMP_SGE:
4425 // icmp sge -> icmp sle
4426 std::swap(A, B);
4427 LLVM_FALLTHROUGH[[clang::fallthrough]];
4428 case ICmpInst::ICMP_SLE:
4429 // icmp sle i1 A, B -> A | ~B
4430 return BinaryOperator::CreateOr(Builder.CreateNot(B), A);
4431 }
4432}
4433
4434Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
4435 bool Changed = false;
4436 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4437 unsigned Op0Cplxity = getComplexity(Op0);
4438 unsigned Op1Cplxity = getComplexity(Op1);
4439
4440 /// Orders the operands of the compare so that they are listed from most
4441 /// complex to least complex. This puts constants before unary operators,
4442 /// before binary operators.
4443 if (Op0Cplxity < Op1Cplxity ||
4444 (Op0Cplxity == Op1Cplxity && swapMayExposeCSEOpportunities(Op0, Op1))) {
4445 I.swapOperands();
4446 std::swap(Op0, Op1);
4447 Changed = true;
4448 }
4449
4450 if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1,
4451 SQ.getWithInstruction(&I)))
4452 return replaceInstUsesWith(I, V);
4453
4454 // comparing -val or val with non-zero is the same as just comparing val
4455 // ie, abs(val) != 0 -> val != 0
4456 if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero())) {
4457 Value *Cond, *SelectTrue, *SelectFalse;
4458 if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue),
4459 m_Value(SelectFalse)))) {
4460 if (Value *V = dyn_castNegVal(SelectTrue)) {
4461 if (V == SelectFalse)
4462 return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
4463 }
4464 else if (Value *V = dyn_castNegVal(SelectFalse)) {
4465 if (V == SelectTrue)
4466 return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
4467 }
4468 }
4469 }
4470
4471 if (Op0->getType()->getScalarType()->isIntegerTy(1))
4472 if (Instruction *Res = canonicalizeICmpBool(I, *Builder))
4473 return Res;
4474
4475 if (ICmpInst *NewICmp = canonicalizeCmpWithConstant(I))
4476 return NewICmp;
4477
4478 if (Instruction *Res = foldICmpWithConstant(I))
4479 return Res;
4480
4481 if (Instruction *Res = foldICmpUsingKnownBits(I))
4482 return Res;
4483
4484 // Test if the ICmpInst instruction is used exclusively by a select as
4485 // part of a minimum or maximum operation. If so, refrain from doing
4486 // any other folding. This helps out other analyses which understand
4487 // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
4488 // and CodeGen. And in this case, at least one of the comparison
4489 // operands has at least one user besides the compare (the select),
4490 // which would often largely negate the benefit of folding anyway.
4491 if (I.hasOneUse())
4492 if (SelectInst *SI = dyn_cast<SelectInst>(*I.user_begin()))
4493 if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
4494 (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
4495 return nullptr;
4496
4497 // FIXME: We only do this after checking for min/max to prevent infinite
4498 // looping caused by a reverse canonicalization of these patterns for min/max.
4499 // FIXME: The organization of folds is a mess. These would naturally go into
4500 // canonicalizeCmpWithConstant(), but we can't move all of the above folds
4501 // down here after the min/max restriction.
4502 ICmpInst::Predicate Pred = I.getPredicate();
4503 const APInt *C;
4504 if (match(Op1, m_APInt(C))) {
4505 // For i32: x >u 2147483647 -> x <s 0 -> true if sign bit set
4506 if (Pred == ICmpInst::ICMP_UGT && C->isMaxSignedValue()) {
4507 Constant *Zero = Constant::getNullValue(Op0->getType());
4508 return new ICmpInst(ICmpInst::ICMP_SLT, Op0, Zero);
4509 }
4510
4511 // For i32: x <u 2147483648 -> x >s -1 -> true if sign bit clear
4512 if (Pred == ICmpInst::ICMP_ULT && C->isMinSignedValue()) {
4513 Constant *AllOnes = Constant::getAllOnesValue(Op0->getType());
4514 return new ICmpInst(ICmpInst::ICMP_SGT, Op0, AllOnes);
4515 }
4516 }
4517
4518 if (Instruction *Res = foldICmpInstWithConstant(I))
4519 return Res;
4520
4521 if (Instruction *Res = foldICmpInstWithConstantNotInt(I))
4522 return Res;
4523
4524 // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
4525 if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
4526 if (Instruction *NI = foldGEPICmp(GEP, Op1, I.getPredicate(), I))
4527 return NI;
4528 if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
4529 if (Instruction *NI = foldGEPICmp(GEP, Op0,
4530 ICmpInst::getSwappedPredicate(I.getPredicate()), I))
4531 return NI;
4532
4533 // Try to optimize equality comparisons against alloca-based pointers.
4534 if (Op0->getType()->isPointerTy() && I.isEquality()) {
4535 assert(Op1->getType()->isPointerTy() && "Comparing pointer with non-pointer?")((Op1->getType()->isPointerTy() && "Comparing pointer with non-pointer?"
) ? static_cast<void> (0) : __assert_fail ("Op1->getType()->isPointerTy() && \"Comparing pointer with non-pointer?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4535, __PRETTY_FUNCTION__));
4536 if (auto *Alloca = dyn_cast<AllocaInst>(GetUnderlyingObject(Op0, DL)))
4537 if (Instruction *New = foldAllocaCmp(I, Alloca, Op1))
4538 return New;
4539 if (auto *Alloca = dyn_cast<AllocaInst>(GetUnderlyingObject(Op1, DL)))
4540 if (Instruction *New = foldAllocaCmp(I, Alloca, Op0))
4541 return New;
4542 }
4543
4544 // Test to see if the operands of the icmp are casted versions of other
4545 // values. If the ptr->ptr cast can be stripped off both arguments, we do so
4546 // now.
4547 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
4548 if (Op0->getType()->isPointerTy() &&
4549 (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
4550 // We keep moving the cast from the left operand over to the right
4551 // operand, where it can often be eliminated completely.
4552 Op0 = CI->getOperand(0);
4553
4554 // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
4555 // so eliminate it as well.
4556 if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
4557 Op1 = CI2->getOperand(0);
4558
4559 // If Op1 is a constant, we can fold the cast into the constant.
4560 if (Op0->getType() != Op1->getType()) {
4561 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
4562 Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
4563 } else {
4564 // Otherwise, cast the RHS right before the icmp
4565 Op1 = Builder->CreateBitCast(Op1, Op0->getType());
4566 }
4567 }
4568 return new ICmpInst(I.getPredicate(), Op0, Op1);
4569 }
4570 }
4571
4572 if (isa<CastInst>(Op0)) {
4573 // Handle the special case of: icmp (cast bool to X), <cst>
4574 // This comes up when you have code like
4575 // int X = A < B;
4576 // if (X) ...
4577 // For generality, we handle any zero-extension of any operand comparison
4578 // with a constant or another cast from the same type.
4579 if (isa<Constant>(Op1) || isa<CastInst>(Op1))
4580 if (Instruction *R = foldICmpWithCastAndCast(I))
4581 return R;
4582 }
4583
4584 if (Instruction *Res = foldICmpBinOp(I))
4585 return Res;
4586
4587 if (Instruction *Res = foldICmpWithMinMax(I))
4588 return Res;
4589
4590 {
4591 Value *A, *B;
4592 // Transform (A & ~B) == 0 --> (A & B) != 0
4593 // and (A & ~B) != 0 --> (A & B) == 0
4594 // if A is a power of 2.
4595 if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
4596 match(Op1, m_Zero()) &&
4597 isKnownToBeAPowerOfTwo(A, false, 0, &I) && I.isEquality())
4598 return new ICmpInst(I.getInversePredicate(),
4599 Builder->CreateAnd(A, B),
4600 Op1);
4601
4602 // ~X < ~Y --> Y < X
4603 // ~X < C --> X > ~C
4604 if (match(Op0, m_Not(m_Value(A)))) {
4605 if (match(Op1, m_Not(m_Value(B))))
4606 return new ICmpInst(I.getPredicate(), B, A);
4607
4608 const APInt *C;
4609 if (match(Op1, m_APInt(C)))
4610 return new ICmpInst(I.getSwappedPredicate(), A,
4611 ConstantInt::get(Op1->getType(), ~(*C)));
4612 }
4613
4614 Instruction *AddI = nullptr;
4615 if (match(&I, m_UAddWithOverflow(m_Value(A), m_Value(B),
4616 m_Instruction(AddI))) &&
4617 isa<IntegerType>(A->getType())) {
4618 Value *Result;
4619 Constant *Overflow;
4620 if (OptimizeOverflowCheck(OCF_UNSIGNED_ADD, A, B, *AddI, Result,
4621 Overflow)) {
4622 replaceInstUsesWith(*AddI, Result);
4623 return replaceInstUsesWith(I, Overflow);
4624 }
4625 }
4626
4627 // (zext a) * (zext b) --> llvm.umul.with.overflow.
4628 if (match(Op0, m_Mul(m_ZExt(m_Value(A)), m_ZExt(m_Value(B))))) {
4629 if (Instruction *R = processUMulZExtIdiom(I, Op0, Op1, *this))
4630 return R;
4631 }
4632 if (match(Op1, m_Mul(m_ZExt(m_Value(A)), m_ZExt(m_Value(B))))) {
4633 if (Instruction *R = processUMulZExtIdiom(I, Op1, Op0, *this))
4634 return R;
4635 }
4636 }
4637
4638 if (Instruction *Res = foldICmpEquality(I))
4639 return Res;
4640
4641 // The 'cmpxchg' instruction returns an aggregate containing the old value and
4642 // an i1 which indicates whether or not we successfully did the swap.
4643 //
4644 // Replace comparisons between the old value and the expected value with the
4645 // indicator that 'cmpxchg' returns.
4646 //
4647 // N.B. This transform is only valid when the 'cmpxchg' is not permitted to
4648 // spuriously fail. In those cases, the old value may equal the expected
4649 // value but it is possible for the swap to not occur.
4650 if (I.getPredicate() == ICmpInst::ICMP_EQ)
4651 if (auto *EVI = dyn_cast<ExtractValueInst>(Op0))
4652 if (auto *ACXI = dyn_cast<AtomicCmpXchgInst>(EVI->getAggregateOperand()))
4653 if (EVI->getIndices()[0] == 0 && ACXI->getCompareOperand() == Op1 &&
4654 !ACXI->isWeak())
4655 return ExtractValueInst::Create(ACXI, 1);
4656
4657 {
4658 Value *X; ConstantInt *Cst;
4659 // icmp X+Cst, X
4660 if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X)
4661 return foldICmpAddOpConst(I, X, Cst, I.getPredicate());
4662
4663 // icmp X, X+Cst
4664 if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
4665 return foldICmpAddOpConst(I, X, Cst, I.getSwappedPredicate());
4666 }
4667 return Changed ? &I : nullptr;
4668}
4669
4670/// Fold fcmp ([us]itofp x, cst) if possible.
4671Instruction *InstCombiner::foldFCmpIntToFPConst(FCmpInst &I, Instruction *LHSI,
4672 Constant *RHSC) {
4673 if (!isa<ConstantFP>(RHSC)) return nullptr;
4674 const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
4675
4676 // Get the width of the mantissa. We don't want to hack on conversions that
4677 // might lose information from the integer, e.g. "i64 -> float"
4678 int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
4679 if (MantissaWidth == -1) return nullptr; // Unknown.
4680
4681 IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
4682
4683 bool LHSUnsigned = isa<UIToFPInst>(LHSI);
4684
4685 if (I.isEquality()) {
4686 FCmpInst::Predicate P = I.getPredicate();
4687 bool IsExact = false;
4688 APSInt RHSCvt(IntTy->getBitWidth(), LHSUnsigned);
4689 RHS.convertToInteger(RHSCvt, APFloat::rmNearestTiesToEven, &IsExact);
4690
4691 // If the floating point constant isn't an integer value, we know if we will
4692 // ever compare equal / not equal to it.
4693 if (!IsExact) {
4694 // TODO: Can never be -0.0 and other non-representable values
4695 APFloat RHSRoundInt(RHS);
4696 RHSRoundInt.roundToIntegral(APFloat::rmNearestTiesToEven);
4697 if (RHS.compare(RHSRoundInt) != APFloat::cmpEqual) {
4698 if (P == FCmpInst::FCMP_OEQ || P == FCmpInst::FCMP_UEQ)
4699 return replaceInstUsesWith(I, Builder->getFalse());
4700
4701 assert(P == FCmpInst::FCMP_ONE || P == FCmpInst::FCMP_UNE)((P == FCmpInst::FCMP_ONE || P == FCmpInst::FCMP_UNE) ? static_cast
<void> (0) : __assert_fail ("P == FCmpInst::FCMP_ONE || P == FCmpInst::FCMP_UNE"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4701, __PRETTY_FUNCTION__));
4702 return replaceInstUsesWith(I, Builder->getTrue());
4703 }
4704 }
4705
4706 // TODO: If the constant is exactly representable, is it always OK to do
4707 // equality compares as integer?
4708 }
4709
4710 // Check to see that the input is converted from an integer type that is small
4711 // enough that preserves all bits. TODO: check here for "known" sign bits.
4712 // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
4713 unsigned InputSize = IntTy->getScalarSizeInBits();
4714
4715 // Following test does NOT adjust InputSize downwards for signed inputs,
4716 // because the most negative value still requires all the mantissa bits
4717 // to distinguish it from one less than that value.
4718 if ((int)InputSize > MantissaWidth) {
4719 // Conversion would lose accuracy. Check if loss can impact comparison.
4720 int Exp = ilogb(RHS);
4721 if (Exp == APFloat::IEK_Inf) {
4722 int MaxExponent = ilogb(APFloat::getLargest(RHS.getSemantics()));
4723 if (MaxExponent < (int)InputSize - !LHSUnsigned)
4724 // Conversion could create infinity.
4725 return nullptr;
4726 } else {
4727 // Note that if RHS is zero or NaN, then Exp is negative
4728 // and first condition is trivially false.
4729 if (MantissaWidth <= Exp && Exp <= (int)InputSize - !LHSUnsigned)
4730 // Conversion could affect comparison.
4731 return nullptr;
4732 }
4733 }
4734
4735 // Otherwise, we can potentially simplify the comparison. We know that it
4736 // will always come through as an integer value and we know the constant is
4737 // not a NAN (it would have been previously simplified).
4738 assert(!RHS.isNaN() && "NaN comparison not already folded!")((!RHS.isNaN() && "NaN comparison not already folded!"
) ? static_cast<void> (0) : __assert_fail ("!RHS.isNaN() && \"NaN comparison not already folded!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4738, __PRETTY_FUNCTION__));
4739
4740 ICmpInst::Predicate Pred;
4741 switch (I.getPredicate()) {
4742 default: llvm_unreachable("Unexpected predicate!")::llvm::llvm_unreachable_internal("Unexpected predicate!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4742);
4743 case FCmpInst::FCMP_UEQ:
4744 case FCmpInst::FCMP_OEQ:
4745 Pred = ICmpInst::ICMP_EQ;
4746 break;
4747 case FCmpInst::FCMP_UGT:
4748 case FCmpInst::FCMP_OGT:
4749 Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
4750 break;
4751 case FCmpInst::FCMP_UGE:
4752 case FCmpInst::FCMP_OGE:
4753 Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
4754 break;
4755 case FCmpInst::FCMP_ULT:
4756 case FCmpInst::FCMP_OLT:
4757 Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
4758 break;
4759 case FCmpInst::FCMP_ULE:
4760 case FCmpInst::FCMP_OLE:
4761 Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
4762 break;
4763 case FCmpInst::FCMP_UNE:
4764 case FCmpInst::FCMP_ONE:
4765 Pred = ICmpInst::ICMP_NE;
4766 break;
4767 case FCmpInst::FCMP_ORD:
4768 return replaceInstUsesWith(I, Builder->getTrue());
4769 case FCmpInst::FCMP_UNO:
4770 return replaceInstUsesWith(I, Builder->getFalse());
4771 }
4772
4773 // Now we know that the APFloat is a normal number, zero or inf.
4774
4775 // See if the FP constant is too large for the integer. For example,
4776 // comparing an i8 to 300.0.
4777 unsigned IntWidth = IntTy->getScalarSizeInBits();
4778
4779 if (!LHSUnsigned) {
4780 // If the RHS value is > SignedMax, fold the comparison. This handles +INF
4781 // and large values.
4782 APFloat SMax(RHS.getSemantics());
4783 SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
4784 APFloat::rmNearestTiesToEven);
4785 if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
4786 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
4787 Pred == ICmpInst::ICMP_SLE)
4788 return replaceInstUsesWith(I, Builder->getTrue());
4789 return replaceInstUsesWith(I, Builder->getFalse());
4790 }
4791 } else {
4792 // If the RHS value is > UnsignedMax, fold the comparison. This handles
4793 // +INF and large values.
4794 APFloat UMax(RHS.getSemantics());
4795 UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
4796 APFloat::rmNearestTiesToEven);
4797 if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
4798 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
4799 Pred == ICmpInst::ICMP_ULE)
4800 return replaceInstUsesWith(I, Builder->getTrue());
4801 return replaceInstUsesWith(I, Builder->getFalse());
4802 }
4803 }
4804
4805 if (!LHSUnsigned) {
4806 // See if the RHS value is < SignedMin.
4807 APFloat SMin(RHS.getSemantics());
4808 SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
4809 APFloat::rmNearestTiesToEven);
4810 if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
4811 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
4812 Pred == ICmpInst::ICMP_SGE)
4813 return replaceInstUsesWith(I, Builder->getTrue());
4814 return replaceInstUsesWith(I, Builder->getFalse());
4815 }
4816 } else {
4817 // See if the RHS value is < UnsignedMin.
4818 APFloat SMin(RHS.getSemantics());
4819 SMin.convertFromAPInt(APInt::getMinValue(IntWidth), true,
4820 APFloat::rmNearestTiesToEven);
4821 if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // umin > 12312.0
4822 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_UGT ||
4823 Pred == ICmpInst::ICMP_UGE)
4824 return replaceInstUsesWith(I, Builder->getTrue());
4825 return replaceInstUsesWith(I, Builder->getFalse());
4826 }
4827 }
4828
4829 // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
4830 // [0, UMAX], but it may still be fractional. See if it is fractional by
4831 // casting the FP value to the integer value and back, checking for equality.
4832 // Don't do this for zero, because -0.0 is not fractional.
4833 Constant *RHSInt = LHSUnsigned
4834 ? ConstantExpr::getFPToUI(RHSC, IntTy)
4835 : ConstantExpr::getFPToSI(RHSC, IntTy);
4836 if (!RHS.isZero()) {
4837 bool Equal = LHSUnsigned
4838 ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
4839 : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
4840 if (!Equal) {
4841 // If we had a comparison against a fractional value, we have to adjust
4842 // the compare predicate and sometimes the value. RHSC is rounded towards
4843 // zero at this point.
4844 switch (Pred) {
4845 default: llvm_unreachable("Unexpected integer comparison!")::llvm::llvm_unreachable_internal("Unexpected integer comparison!"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4845);
4846 case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
4847 return replaceInstUsesWith(I, Builder->getTrue());
4848 case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
4849 return replaceInstUsesWith(I, Builder->getFalse());
4850 case ICmpInst::ICMP_ULE:
4851 // (float)int <= 4.4 --> int <= 4
4852 // (float)int <= -4.4 --> false
4853 if (RHS.isNegative())
4854 return replaceInstUsesWith(I, Builder->getFalse());
4855 break;
4856 case ICmpInst::ICMP_SLE:
4857 // (float)int <= 4.4 --> int <= 4
4858 // (float)int <= -4.4 --> int < -4
4859 if (RHS.isNegative())
4860 Pred = ICmpInst::ICMP_SLT;
4861 break;
4862 case ICmpInst::ICMP_ULT:
4863 // (float)int < -4.4 --> false
4864 // (float)int < 4.4 --> int <= 4
4865 if (RHS.isNegative())
4866 return replaceInstUsesWith(I, Builder->getFalse());
4867 Pred = ICmpInst::ICMP_ULE;
4868 break;
4869 case ICmpInst::ICMP_SLT:
4870 // (float)int < -4.4 --> int < -4
4871 // (float)int < 4.4 --> int <= 4
4872 if (!RHS.isNegative())
4873 Pred = ICmpInst::ICMP_SLE;
4874 break;
4875 case ICmpInst::ICMP_UGT:
4876 // (float)int > 4.4 --> int > 4
4877 // (float)int > -4.4 --> true
4878 if (RHS.isNegative())
4879 return replaceInstUsesWith(I, Builder->getTrue());
4880 break;
4881 case ICmpInst::ICMP_SGT:
4882 // (float)int > 4.4 --> int > 4
4883 // (float)int > -4.4 --> int >= -4
4884 if (RHS.isNegative())
4885 Pred = ICmpInst::ICMP_SGE;
4886 break;
4887 case ICmpInst::ICMP_UGE:
4888 // (float)int >= -4.4 --> true
4889 // (float)int >= 4.4 --> int > 4
4890 if (RHS.isNegative())
4891 return replaceInstUsesWith(I, Builder->getTrue());
4892 Pred = ICmpInst::ICMP_UGT;
4893 break;
4894 case ICmpInst::ICMP_SGE:
4895 // (float)int >= -4.4 --> int >= -4
4896 // (float)int >= 4.4 --> int > 4
4897 if (!RHS.isNegative())
4898 Pred = ICmpInst::ICMP_SGT;
4899 break;
4900 }
4901 }
4902 }
4903
4904 // Lower this FP comparison into an appropriate integer version of the
4905 // comparison.
4906 return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
4907}
4908
4909Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
4910 bool Changed = false;
4911
4912 /// Orders the operands of the compare so that they are listed from most
4913 /// complex to least complex. This puts constants before unary operators,
4914 /// before binary operators.
4915 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
4916 I.swapOperands();
4917 Changed = true;
4918 }
4919
4920 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4921
4922 if (Value *V =
4923 SimplifyFCmpInst(I.getPredicate(), Op0, Op1, I.getFastMathFlags(),
4924 SQ.getWithInstruction(&I)))
4925 return replaceInstUsesWith(I, V);
4926
4927 // Simplify 'fcmp pred X, X'
4928 if (Op0 == Op1) {
4929 switch (I.getPredicate()) {
4930 default: llvm_unreachable("Unknown predicate!")::llvm::llvm_unreachable_internal("Unknown predicate!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4930);
4931 case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
4932 case FCmpInst::FCMP_ULT: // True if unordered or less than
4933 case FCmpInst::FCMP_UGT: // True if unordered or greater than
4934 case FCmpInst::FCMP_UNE: // True if unordered or not equal
4935 // Canonicalize these to be 'fcmp uno %X, 0.0'.
4936 I.setPredicate(FCmpInst::FCMP_UNO);
4937 I.setOperand(1, Constant::getNullValue(Op0->getType()));
4938 return &I;
4939
4940 case FCmpInst::FCMP_ORD: // True if ordered (no nans)
4941 case FCmpInst::FCMP_OEQ: // True if ordered and equal
4942 case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
4943 case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
4944 // Canonicalize these to be 'fcmp ord %X, 0.0'.
4945 I.setPredicate(FCmpInst::FCMP_ORD);
4946 I.setOperand(1, Constant::getNullValue(Op0->getType()));
4947 return &I;
4948 }
4949 }
4950
4951 // Test if the FCmpInst instruction is used exclusively by a select as
4952 // part of a minimum or maximum operation. If so, refrain from doing
4953 // any other folding. This helps out other analyses which understand
4954 // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
4955 // and CodeGen. And in this case, at least one of the comparison
4956 // operands has at least one user besides the compare (the select),
4957 // which would often largely negate the benefit of folding anyway.
4958 if (I.hasOneUse())
4959 if (SelectInst *SI = dyn_cast<SelectInst>(*I.user_begin()))
4960 if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
4961 (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
4962 return nullptr;
4963
4964 // Handle fcmp with constant RHS
4965 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
4966 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
4967 switch (LHSI->getOpcode()) {
4968 case Instruction::FPExt: {
4969 // fcmp (fpext x), C -> fcmp x, (fptrunc C) if fptrunc is lossless
4970 FPExtInst *LHSExt = cast<FPExtInst>(LHSI);
4971 ConstantFP *RHSF = dyn_cast<ConstantFP>(RHSC);
4972 if (!RHSF)
4973 break;
4974
4975 const fltSemantics *Sem;
4976 // FIXME: This shouldn't be here.
4977 if (LHSExt->getSrcTy()->isHalfTy())
4978 Sem = &APFloat::IEEEhalf();
4979 else if (LHSExt->getSrcTy()->isFloatTy())
4980 Sem = &APFloat::IEEEsingle();
4981 else if (LHSExt->getSrcTy()->isDoubleTy())
4982 Sem = &APFloat::IEEEdouble();
4983 else if (LHSExt->getSrcTy()->isFP128Ty())
4984 Sem = &APFloat::IEEEquad();
4985 else if (LHSExt->getSrcTy()->isX86_FP80Ty())
4986 Sem = &APFloat::x87DoubleExtended();
4987 else if (LHSExt->getSrcTy()->isPPC_FP128Ty())
4988 Sem = &APFloat::PPCDoubleDouble();
4989 else
4990 break;
4991
4992 bool Lossy;
4993 APFloat F = RHSF->getValueAPF();
4994 F.convert(*Sem, APFloat::rmNearestTiesToEven, &Lossy);
4995
4996 // Avoid lossy conversions and denormals. Zero is a special case
4997 // that's OK to convert.
4998 APFloat Fabs = F;
4999 Fabs.clearSign();
5000 if (!Lossy &&
5001 ((Fabs.compare(APFloat::getSmallestNormalized(*Sem)) !=
5002 APFloat::cmpLessThan) || Fabs.isZero()))
5003
5004 return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0),
5005 ConstantFP::get(RHSC->getContext(), F));
5006 break;
5007 }
5008 case Instruction::PHI:
5009 // Only fold fcmp into the PHI if the phi and fcmp are in the same
5010 // block. If in the same block, we're encouraging jump threading. If
5011 // not, we are just pessimizing the code by making an i1 phi.
5012 if (LHSI->getParent() == I.getParent())
5013 if (Instruction *NV = foldOpIntoPhi(I, cast<PHINode>(LHSI)))
5014 return NV;
5015 break;
5016 case Instruction::SIToFP:
5017 case Instruction::UIToFP:
5018 if (Instruction *NV = foldFCmpIntToFPConst(I, LHSI, RHSC))
5019 return NV;
5020 break;
5021 case Instruction::FSub: {
5022 // fcmp pred (fneg x), C -> fcmp swap(pred) x, -C
5023 Value *Op;
5024 if (match(LHSI, m_FNeg(m_Value(Op))))
5025 return new FCmpInst(I.getSwappedPredicate(), Op,
5026 ConstantExpr::getFNeg(RHSC));
5027 break;
5028 }
5029 case Instruction::Load:
5030 if (GetElementPtrInst *GEP =
5031 dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
5032 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
5033 if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
5034 !cast<LoadInst>(LHSI)->isVolatile())
5035 if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, I))
5036 return Res;
5037 }
5038 break;
5039 case Instruction::Call: {
5040 if (!RHSC->isNullValue())
5041 break;
5042
5043 CallInst *CI = cast<CallInst>(LHSI);
5044 Intrinsic::ID IID = getIntrinsicForCallSite(CI, &TLI);
5045 if (IID != Intrinsic::fabs)
5046 break;
5047
5048 // Various optimization for fabs compared with zero.
5049 switch (I.getPredicate()) {
5050 default:
5051 break;
5052 // fabs(x) < 0 --> false
5053 case FCmpInst::FCMP_OLT:
5054 llvm_unreachable("handled by SimplifyFCmpInst")::llvm::llvm_unreachable_internal("handled by SimplifyFCmpInst"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5054);
5055 // fabs(x) > 0 --> x != 0
5056 case FCmpInst::FCMP_OGT:
5057 return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0), RHSC);
5058 // fabs(x) <= 0 --> x == 0
5059 case FCmpInst::FCMP_OLE:
5060 return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0), RHSC);
5061 // fabs(x) >= 0 --> !isnan(x)
5062 case FCmpInst::FCMP_OGE:
5063 return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0), RHSC);
5064 // fabs(x) == 0 --> x == 0
5065 // fabs(x) != 0 --> x != 0
5066 case FCmpInst::FCMP_OEQ:
5067 case FCmpInst::FCMP_UEQ:
5068 case FCmpInst::FCMP_ONE:
5069 case FCmpInst::FCMP_UNE:
5070 return new FCmpInst(I.getPredicate(), CI->getArgOperand(0), RHSC);
5071 }
5072 }
5073 }
5074 }
5075
5076 // fcmp pred (fneg x), (fneg y) -> fcmp swap(pred) x, y
5077 Value *X, *Y;
5078 if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_FNeg(m_Value(Y))))
5079 return new FCmpInst(I.getSwappedPredicate(), X, Y);
5080
5081 // fcmp (fpext x), (fpext y) -> fcmp x, y
5082 if (FPExtInst *LHSExt = dyn_cast<FPExtInst>(Op0))
5083 if (FPExtInst *RHSExt = dyn_cast<FPExtInst>(Op1))
5084 if (LHSExt->getSrcTy() == RHSExt->getSrcTy())
5085 return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0),
5086 RHSExt->getOperand(0));
5087
5088 return Changed ? &I : nullptr;
5089}