| File: | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp |
| Warning: | line 3533, column 7 Called C++ object pointer is uninitialized |
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| 1 | //===- InstCombineCompares.cpp --------------------------------------------===// | ||||||||
| 2 | // | ||||||||
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||||||||
| 4 | // See https://llvm.org/LICENSE.txt for license information. | ||||||||
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||||||||
| 6 | // | ||||||||
| 7 | //===----------------------------------------------------------------------===// | ||||||||
| 8 | // | ||||||||
| 9 | // This file implements the visitICmp and visitFCmp functions. | ||||||||
| 10 | // | ||||||||
| 11 | //===----------------------------------------------------------------------===// | ||||||||
| 12 | |||||||||
| 13 | #include "InstCombineInternal.h" | ||||||||
| 14 | #include "llvm/ADT/APSInt.h" | ||||||||
| 15 | #include "llvm/ADT/SetVector.h" | ||||||||
| 16 | #include "llvm/ADT/Statistic.h" | ||||||||
| 17 | #include "llvm/Analysis/ConstantFolding.h" | ||||||||
| 18 | #include "llvm/Analysis/InstructionSimplify.h" | ||||||||
| 19 | #include "llvm/Analysis/TargetLibraryInfo.h" | ||||||||
| 20 | #include "llvm/IR/ConstantRange.h" | ||||||||
| 21 | #include "llvm/IR/DataLayout.h" | ||||||||
| 22 | #include "llvm/IR/GetElementPtrTypeIterator.h" | ||||||||
| 23 | #include "llvm/IR/IntrinsicInst.h" | ||||||||
| 24 | #include "llvm/IR/PatternMatch.h" | ||||||||
| 25 | #include "llvm/Support/Debug.h" | ||||||||
| 26 | #include "llvm/Support/KnownBits.h" | ||||||||
| 27 | |||||||||
| 28 | using namespace llvm; | ||||||||
| 29 | using namespace PatternMatch; | ||||||||
| 30 | |||||||||
| 31 | #define DEBUG_TYPE"instcombine" "instcombine" | ||||||||
| 32 | |||||||||
| 33 | // How many times is a select replaced by one of its operands? | ||||||||
| 34 | STATISTIC(NumSel, "Number of select opts")static llvm::Statistic NumSel = {"instcombine", "NumSel", "Number of select opts" }; | ||||||||
| 35 | |||||||||
| 36 | |||||||||
| 37 | /// Compute Result = In1+In2, returning true if the result overflowed for this | ||||||||
| 38 | /// type. | ||||||||
| 39 | static bool addWithOverflow(APInt &Result, const APInt &In1, | ||||||||
| 40 | const APInt &In2, bool IsSigned = false) { | ||||||||
| 41 | bool Overflow; | ||||||||
| 42 | if (IsSigned) | ||||||||
| 43 | Result = In1.sadd_ov(In2, Overflow); | ||||||||
| 44 | else | ||||||||
| 45 | Result = In1.uadd_ov(In2, Overflow); | ||||||||
| 46 | |||||||||
| 47 | return Overflow; | ||||||||
| 48 | } | ||||||||
| 49 | |||||||||
| 50 | /// Compute Result = In1-In2, returning true if the result overflowed for this | ||||||||
| 51 | /// type. | ||||||||
| 52 | static bool subWithOverflow(APInt &Result, const APInt &In1, | ||||||||
| 53 | const APInt &In2, bool IsSigned = false) { | ||||||||
| 54 | bool Overflow; | ||||||||
| 55 | if (IsSigned) | ||||||||
| 56 | Result = In1.ssub_ov(In2, Overflow); | ||||||||
| 57 | else | ||||||||
| 58 | Result = In1.usub_ov(In2, Overflow); | ||||||||
| 59 | |||||||||
| 60 | return Overflow; | ||||||||
| 61 | } | ||||||||
| 62 | |||||||||
| 63 | /// Given an icmp instruction, return true if any use of this comparison is a | ||||||||
| 64 | /// branch on sign bit comparison. | ||||||||
| 65 | static bool hasBranchUse(ICmpInst &I) { | ||||||||
| 66 | for (auto *U : I.users()) | ||||||||
| 67 | if (isa<BranchInst>(U)) | ||||||||
| 68 | return true; | ||||||||
| 69 | return false; | ||||||||
| 70 | } | ||||||||
| 71 | |||||||||
| 72 | /// Returns true if the exploded icmp can be expressed as a signed comparison | ||||||||
| 73 | /// to zero and updates the predicate accordingly. | ||||||||
| 74 | /// The signedness of the comparison is preserved. | ||||||||
| 75 | /// TODO: Refactor with decomposeBitTestICmp()? | ||||||||
| 76 | static bool isSignTest(ICmpInst::Predicate &Pred, const APInt &C) { | ||||||||
| 77 | if (!ICmpInst::isSigned(Pred)) | ||||||||
| 78 | return false; | ||||||||
| 79 | |||||||||
| 80 | if (C.isNullValue()) | ||||||||
| 81 | return ICmpInst::isRelational(Pred); | ||||||||
| 82 | |||||||||
| 83 | if (C.isOneValue()) { | ||||||||
| 84 | if (Pred == ICmpInst::ICMP_SLT) { | ||||||||
| 85 | Pred = ICmpInst::ICMP_SLE; | ||||||||
| 86 | return true; | ||||||||
| 87 | } | ||||||||
| 88 | } else if (C.isAllOnesValue()) { | ||||||||
| 89 | if (Pred == ICmpInst::ICMP_SGT) { | ||||||||
| 90 | Pred = ICmpInst::ICMP_SGE; | ||||||||
| 91 | return true; | ||||||||
| 92 | } | ||||||||
| 93 | } | ||||||||
| 94 | |||||||||
| 95 | return false; | ||||||||
| 96 | } | ||||||||
| 97 | |||||||||
| 98 | /// Given a signed integer type and a set of known zero and one bits, compute | ||||||||
| 99 | /// the maximum and minimum values that could have the specified known zero and | ||||||||
| 100 | /// known one bits, returning them in Min/Max. | ||||||||
| 101 | /// TODO: Move to method on KnownBits struct? | ||||||||
| 102 | static void computeSignedMinMaxValuesFromKnownBits(const KnownBits &Known, | ||||||||
| 103 | APInt &Min, APInt &Max) { | ||||||||
| 104 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 106, __PRETTY_FUNCTION__)) | ||||||||
| 105 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 106, __PRETTY_FUNCTION__)) | ||||||||
| 106 | "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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 106, __PRETTY_FUNCTION__)); | ||||||||
| 107 | APInt UnknownBits = ~(Known.Zero|Known.One); | ||||||||
| 108 | |||||||||
| 109 | // The minimum value is when all unknown bits are zeros, EXCEPT for the sign | ||||||||
| 110 | // bit if it is unknown. | ||||||||
| 111 | Min = Known.One; | ||||||||
| 112 | Max = Known.One|UnknownBits; | ||||||||
| 113 | |||||||||
| 114 | if (UnknownBits.isNegative()) { // Sign bit is unknown | ||||||||
| 115 | Min.setSignBit(); | ||||||||
| 116 | Max.clearSignBit(); | ||||||||
| 117 | } | ||||||||
| 118 | } | ||||||||
| 119 | |||||||||
| 120 | /// Given an unsigned integer type and a set of known zero and one bits, compute | ||||||||
| 121 | /// the maximum and minimum values that could have the specified known zero and | ||||||||
| 122 | /// known one bits, returning them in Min/Max. | ||||||||
| 123 | /// TODO: Move to method on KnownBits struct? | ||||||||
| 124 | static void computeUnsignedMinMaxValuesFromKnownBits(const KnownBits &Known, | ||||||||
| 125 | APInt &Min, APInt &Max) { | ||||||||
| 126 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 128, __PRETTY_FUNCTION__)) | ||||||||
| 127 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 128, __PRETTY_FUNCTION__)) | ||||||||
| 128 | "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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 128, __PRETTY_FUNCTION__)); | ||||||||
| 129 | APInt UnknownBits = ~(Known.Zero|Known.One); | ||||||||
| 130 | |||||||||
| 131 | // The minimum value is when the unknown bits are all zeros. | ||||||||
| 132 | Min = Known.One; | ||||||||
| 133 | // The maximum value is when the unknown bits are all ones. | ||||||||
| 134 | Max = Known.One|UnknownBits; | ||||||||
| 135 | } | ||||||||
| 136 | |||||||||
| 137 | /// This is called when we see this pattern: | ||||||||
| 138 | /// cmp pred (load (gep GV, ...)), cmpcst | ||||||||
| 139 | /// where GV is a global variable with a constant initializer. Try to simplify | ||||||||
| 140 | /// this into some simple computation that does not need the load. For example | ||||||||
| 141 | /// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3". | ||||||||
| 142 | /// | ||||||||
| 143 | /// If AndCst is non-null, then the loaded value is masked with that constant | ||||||||
| 144 | /// before doing the comparison. This handles cases like "A[i]&4 == 0". | ||||||||
| 145 | Instruction *InstCombiner::foldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, | ||||||||
| 146 | GlobalVariable *GV, | ||||||||
| 147 | CmpInst &ICI, | ||||||||
| 148 | ConstantInt *AndCst) { | ||||||||
| 149 | Constant *Init = GV->getInitializer(); | ||||||||
| 150 | if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init)) | ||||||||
| 151 | return nullptr; | ||||||||
| 152 | |||||||||
| 153 | uint64_t ArrayElementCount = Init->getType()->getArrayNumElements(); | ||||||||
| 154 | // Don't blow up on huge arrays. | ||||||||
| 155 | if (ArrayElementCount > MaxArraySizeForCombine) | ||||||||
| 156 | return nullptr; | ||||||||
| 157 | |||||||||
| 158 | // There are many forms of this optimization we can handle, for now, just do | ||||||||
| 159 | // the simple index into a single-dimensional array. | ||||||||
| 160 | // | ||||||||
| 161 | // Require: GEP GV, 0, i {{, constant indices}} | ||||||||
| 162 | if (GEP->getNumOperands() < 3 || | ||||||||
| 163 | !isa<ConstantInt>(GEP->getOperand(1)) || | ||||||||
| 164 | !cast<ConstantInt>(GEP->getOperand(1))->isZero() || | ||||||||
| 165 | isa<Constant>(GEP->getOperand(2))) | ||||||||
| 166 | return nullptr; | ||||||||
| 167 | |||||||||
| 168 | // Check that indices after the variable are constants and in-range for the | ||||||||
| 169 | // type they index. Collect the indices. This is typically for arrays of | ||||||||
| 170 | // structs. | ||||||||
| 171 | SmallVector<unsigned, 4> LaterIndices; | ||||||||
| 172 | |||||||||
| 173 | Type *EltTy = Init->getType()->getArrayElementType(); | ||||||||
| 174 | for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) { | ||||||||
| 175 | ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i)); | ||||||||
| 176 | if (!Idx) return nullptr; // Variable index. | ||||||||
| 177 | |||||||||
| 178 | uint64_t IdxVal = Idx->getZExtValue(); | ||||||||
| 179 | if ((unsigned)IdxVal != IdxVal) return nullptr; // Too large array index. | ||||||||
| 180 | |||||||||
| 181 | if (StructType *STy = dyn_cast<StructType>(EltTy)) | ||||||||
| 182 | EltTy = STy->getElementType(IdxVal); | ||||||||
| 183 | else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) { | ||||||||
| 184 | if (IdxVal >= ATy->getNumElements()) return nullptr; | ||||||||
| 185 | EltTy = ATy->getElementType(); | ||||||||
| 186 | } else { | ||||||||
| 187 | return nullptr; // Unknown type. | ||||||||
| 188 | } | ||||||||
| 189 | |||||||||
| 190 | LaterIndices.push_back(IdxVal); | ||||||||
| 191 | } | ||||||||
| 192 | |||||||||
| 193 | enum { Overdefined = -3, Undefined = -2 }; | ||||||||
| 194 | |||||||||
| 195 | // Variables for our state machines. | ||||||||
| 196 | |||||||||
| 197 | // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form | ||||||||
| 198 | // "i == 47 | i == 87", where 47 is the first index the condition is true for, | ||||||||
| 199 | // and 87 is the second (and last) index. FirstTrueElement is -2 when | ||||||||
| 200 | // undefined, otherwise set to the first true element. SecondTrueElement is | ||||||||
| 201 | // -2 when undefined, -3 when overdefined and >= 0 when that index is true. | ||||||||
| 202 | int FirstTrueElement = Undefined, SecondTrueElement = Undefined; | ||||||||
| 203 | |||||||||
| 204 | // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the | ||||||||
| 205 | // form "i != 47 & i != 87". Same state transitions as for true elements. | ||||||||
| 206 | int FirstFalseElement = Undefined, SecondFalseElement = Undefined; | ||||||||
| 207 | |||||||||
| 208 | /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these | ||||||||
| 209 | /// define a state machine that triggers for ranges of values that the index | ||||||||
| 210 | /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'. | ||||||||
| 211 | /// This is -2 when undefined, -3 when overdefined, and otherwise the last | ||||||||
| 212 | /// index in the range (inclusive). We use -2 for undefined here because we | ||||||||
| 213 | /// use relative comparisons and don't want 0-1 to match -1. | ||||||||
| 214 | int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined; | ||||||||
| 215 | |||||||||
| 216 | // MagicBitvector - This is a magic bitvector where we set a bit if the | ||||||||
| 217 | // comparison is true for element 'i'. If there are 64 elements or less in | ||||||||
| 218 | // the array, this will fully represent all the comparison results. | ||||||||
| 219 | uint64_t MagicBitvector = 0; | ||||||||
| 220 | |||||||||
| 221 | // Scan the array and see if one of our patterns matches. | ||||||||
| 222 | Constant *CompareRHS = cast<Constant>(ICI.getOperand(1)); | ||||||||
| 223 | for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) { | ||||||||
| 224 | Constant *Elt = Init->getAggregateElement(i); | ||||||||
| 225 | if (!Elt) return nullptr; | ||||||||
| 226 | |||||||||
| 227 | // If this is indexing an array of structures, get the structure element. | ||||||||
| 228 | if (!LaterIndices.empty()) | ||||||||
| 229 | Elt = ConstantExpr::getExtractValue(Elt, LaterIndices); | ||||||||
| 230 | |||||||||
| 231 | // If the element is masked, handle it. | ||||||||
| 232 | if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst); | ||||||||
| 233 | |||||||||
| 234 | // Find out if the comparison would be true or false for the i'th element. | ||||||||
| 235 | Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt, | ||||||||
| 236 | CompareRHS, DL, &TLI); | ||||||||
| 237 | // If the result is undef for this element, ignore it. | ||||||||
| 238 | if (isa<UndefValue>(C)) { | ||||||||
| 239 | // Extend range state machines to cover this element in case there is an | ||||||||
| 240 | // undef in the middle of the range. | ||||||||
| 241 | if (TrueRangeEnd == (int)i-1) | ||||||||
| 242 | TrueRangeEnd = i; | ||||||||
| 243 | if (FalseRangeEnd == (int)i-1) | ||||||||
| 244 | FalseRangeEnd = i; | ||||||||
| 245 | continue; | ||||||||
| 246 | } | ||||||||
| 247 | |||||||||
| 248 | // If we can't compute the result for any of the elements, we have to give | ||||||||
| 249 | // up evaluating the entire conditional. | ||||||||
| 250 | if (!isa<ConstantInt>(C)) return nullptr; | ||||||||
| 251 | |||||||||
| 252 | // Otherwise, we know if the comparison is true or false for this element, | ||||||||
| 253 | // update our state machines. | ||||||||
| 254 | bool IsTrueForElt = !cast<ConstantInt>(C)->isZero(); | ||||||||
| 255 | |||||||||
| 256 | // State machine for single/double/range index comparison. | ||||||||
| 257 | if (IsTrueForElt) { | ||||||||
| 258 | // Update the TrueElement state machine. | ||||||||
| 259 | if (FirstTrueElement == Undefined) | ||||||||
| 260 | FirstTrueElement = TrueRangeEnd = i; // First true element. | ||||||||
| 261 | else { | ||||||||
| 262 | // Update double-compare state machine. | ||||||||
| 263 | if (SecondTrueElement == Undefined) | ||||||||
| 264 | SecondTrueElement = i; | ||||||||
| 265 | else | ||||||||
| 266 | SecondTrueElement = Overdefined; | ||||||||
| 267 | |||||||||
| 268 | // Update range state machine. | ||||||||
| 269 | if (TrueRangeEnd == (int)i-1) | ||||||||
| 270 | TrueRangeEnd = i; | ||||||||
| 271 | else | ||||||||
| 272 | TrueRangeEnd = Overdefined; | ||||||||
| 273 | } | ||||||||
| 274 | } else { | ||||||||
| 275 | // Update the FalseElement state machine. | ||||||||
| 276 | if (FirstFalseElement == Undefined) | ||||||||
| 277 | FirstFalseElement = FalseRangeEnd = i; // First false element. | ||||||||
| 278 | else { | ||||||||
| 279 | // Update double-compare state machine. | ||||||||
| 280 | if (SecondFalseElement == Undefined) | ||||||||
| 281 | SecondFalseElement = i; | ||||||||
| 282 | else | ||||||||
| 283 | SecondFalseElement = Overdefined; | ||||||||
| 284 | |||||||||
| 285 | // Update range state machine. | ||||||||
| 286 | if (FalseRangeEnd == (int)i-1) | ||||||||
| 287 | FalseRangeEnd = i; | ||||||||
| 288 | else | ||||||||
| 289 | FalseRangeEnd = Overdefined; | ||||||||
| 290 | } | ||||||||
| 291 | } | ||||||||
| 292 | |||||||||
| 293 | // If this element is in range, update our magic bitvector. | ||||||||
| 294 | if (i < 64 && IsTrueForElt) | ||||||||
| 295 | MagicBitvector |= 1ULL << i; | ||||||||
| 296 | |||||||||
| 297 | // If all of our states become overdefined, bail out early. Since the | ||||||||
| 298 | // predicate is expensive, only check it every 8 elements. This is only | ||||||||
| 299 | // really useful for really huge arrays. | ||||||||
| 300 | if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined && | ||||||||
| 301 | SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined && | ||||||||
| 302 | FalseRangeEnd == Overdefined) | ||||||||
| 303 | return nullptr; | ||||||||
| 304 | } | ||||||||
| 305 | |||||||||
| 306 | // Now that we've scanned the entire array, emit our new comparison(s). We | ||||||||
| 307 | // order the state machines in complexity of the generated code. | ||||||||
| 308 | Value *Idx = GEP->getOperand(2); | ||||||||
| 309 | |||||||||
| 310 | // If the index is larger than the pointer size of the target, truncate the | ||||||||
| 311 | // index down like the GEP would do implicitly. We don't have to do this for | ||||||||
| 312 | // an inbounds GEP because the index can't be out of range. | ||||||||
| 313 | if (!GEP->isInBounds()) { | ||||||||
| 314 | Type *IntPtrTy = DL.getIntPtrType(GEP->getType()); | ||||||||
| 315 | unsigned PtrSize = IntPtrTy->getIntegerBitWidth(); | ||||||||
| 316 | if (Idx->getType()->getPrimitiveSizeInBits() > PtrSize) | ||||||||
| 317 | Idx = Builder.CreateTrunc(Idx, IntPtrTy); | ||||||||
| 318 | } | ||||||||
| 319 | |||||||||
| 320 | // If the comparison is only true for one or two elements, emit direct | ||||||||
| 321 | // comparisons. | ||||||||
| 322 | if (SecondTrueElement != Overdefined) { | ||||||||
| 323 | // None true -> false. | ||||||||
| 324 | if (FirstTrueElement == Undefined) | ||||||||
| 325 | return replaceInstUsesWith(ICI, Builder.getFalse()); | ||||||||
| 326 | |||||||||
| 327 | Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement); | ||||||||
| 328 | |||||||||
| 329 | // True for one element -> 'i == 47'. | ||||||||
| 330 | if (SecondTrueElement == Undefined) | ||||||||
| 331 | return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx); | ||||||||
| 332 | |||||||||
| 333 | // True for two elements -> 'i == 47 | i == 72'. | ||||||||
| 334 | Value *C1 = Builder.CreateICmpEQ(Idx, FirstTrueIdx); | ||||||||
| 335 | Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement); | ||||||||
| 336 | Value *C2 = Builder.CreateICmpEQ(Idx, SecondTrueIdx); | ||||||||
| 337 | return BinaryOperator::CreateOr(C1, C2); | ||||||||
| 338 | } | ||||||||
| 339 | |||||||||
| 340 | // If the comparison is only false for one or two elements, emit direct | ||||||||
| 341 | // comparisons. | ||||||||
| 342 | if (SecondFalseElement != Overdefined) { | ||||||||
| 343 | // None false -> true. | ||||||||
| 344 | if (FirstFalseElement == Undefined) | ||||||||
| 345 | return replaceInstUsesWith(ICI, Builder.getTrue()); | ||||||||
| 346 | |||||||||
| 347 | Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement); | ||||||||
| 348 | |||||||||
| 349 | // False for one element -> 'i != 47'. | ||||||||
| 350 | if (SecondFalseElement == Undefined) | ||||||||
| 351 | return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx); | ||||||||
| 352 | |||||||||
| 353 | // False for two elements -> 'i != 47 & i != 72'. | ||||||||
| 354 | Value *C1 = Builder.CreateICmpNE(Idx, FirstFalseIdx); | ||||||||
| 355 | Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement); | ||||||||
| 356 | Value *C2 = Builder.CreateICmpNE(Idx, SecondFalseIdx); | ||||||||
| 357 | return BinaryOperator::CreateAnd(C1, C2); | ||||||||
| 358 | } | ||||||||
| 359 | |||||||||
| 360 | // If the comparison can be replaced with a range comparison for the elements | ||||||||
| 361 | // where it is true, emit the range check. | ||||||||
| 362 | if (TrueRangeEnd != Overdefined) { | ||||||||
| 363 | 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\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 363, __PRETTY_FUNCTION__)); | ||||||||
| 364 | |||||||||
| 365 | // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1). | ||||||||
| 366 | if (FirstTrueElement) { | ||||||||
| 367 | Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement); | ||||||||
| 368 | Idx = Builder.CreateAdd(Idx, Offs); | ||||||||
| 369 | } | ||||||||
| 370 | |||||||||
| 371 | Value *End = ConstantInt::get(Idx->getType(), | ||||||||
| 372 | TrueRangeEnd-FirstTrueElement+1); | ||||||||
| 373 | return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End); | ||||||||
| 374 | } | ||||||||
| 375 | |||||||||
| 376 | // False range check. | ||||||||
| 377 | if (FalseRangeEnd != Overdefined) { | ||||||||
| 378 | 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\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 378, __PRETTY_FUNCTION__)); | ||||||||
| 379 | // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse). | ||||||||
| 380 | if (FirstFalseElement) { | ||||||||
| 381 | Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement); | ||||||||
| 382 | Idx = Builder.CreateAdd(Idx, Offs); | ||||||||
| 383 | } | ||||||||
| 384 | |||||||||
| 385 | Value *End = ConstantInt::get(Idx->getType(), | ||||||||
| 386 | FalseRangeEnd-FirstFalseElement); | ||||||||
| 387 | return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End); | ||||||||
| 388 | } | ||||||||
| 389 | |||||||||
| 390 | // If a magic bitvector captures the entire comparison state | ||||||||
| 391 | // of this load, replace it with computation that does: | ||||||||
| 392 | // ((magic_cst >> i) & 1) != 0 | ||||||||
| 393 | { | ||||||||
| 394 | Type *Ty = nullptr; | ||||||||
| 395 | |||||||||
| 396 | // Look for an appropriate type: | ||||||||
| 397 | // - The type of Idx if the magic fits | ||||||||
| 398 | // - The smallest fitting legal type | ||||||||
| 399 | if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth()) | ||||||||
| 400 | Ty = Idx->getType(); | ||||||||
| 401 | else | ||||||||
| 402 | Ty = DL.getSmallestLegalIntType(Init->getContext(), ArrayElementCount); | ||||||||
| 403 | |||||||||
| 404 | if (Ty) { | ||||||||
| 405 | Value *V = Builder.CreateIntCast(Idx, Ty, false); | ||||||||
| 406 | V = Builder.CreateLShr(ConstantInt::get(Ty, MagicBitvector), V); | ||||||||
| 407 | V = Builder.CreateAnd(ConstantInt::get(Ty, 1), V); | ||||||||
| 408 | return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0)); | ||||||||
| 409 | } | ||||||||
| 410 | } | ||||||||
| 411 | |||||||||
| 412 | return nullptr; | ||||||||
| 413 | } | ||||||||
| 414 | |||||||||
| 415 | /// Return a value that can be used to compare the *offset* implied by a GEP to | ||||||||
| 416 | /// zero. For example, if we have &A[i], we want to return 'i' for | ||||||||
| 417 | /// "icmp ne i, 0". Note that, in general, indices can be complex, and scales | ||||||||
| 418 | /// are involved. The above expression would also be legal to codegen as | ||||||||
| 419 | /// "icmp ne (i*4), 0" (assuming A is a pointer to i32). | ||||||||
| 420 | /// This latter form is less amenable to optimization though, and we are allowed | ||||||||
| 421 | /// to generate the first by knowing that pointer arithmetic doesn't overflow. | ||||||||
| 422 | /// | ||||||||
| 423 | /// If we can't emit an optimized form for this expression, this returns null. | ||||||||
| 424 | /// | ||||||||
| 425 | static Value *evaluateGEPOffsetExpression(User *GEP, InstCombiner &IC, | ||||||||
| 426 | const DataLayout &DL) { | ||||||||
| 427 | gep_type_iterator GTI = gep_type_begin(GEP); | ||||||||
| 428 | |||||||||
| 429 | // Check to see if this gep only has a single variable index. If so, and if | ||||||||
| 430 | // any constant indices are a multiple of its scale, then we can compute this | ||||||||
| 431 | // in terms of the scale of the variable index. For example, if the GEP | ||||||||
| 432 | // implies an offset of "12 + i*4", then we can codegen this as "3 + i", | ||||||||
| 433 | // because the expression will cross zero at the same point. | ||||||||
| 434 | unsigned i, e = GEP->getNumOperands(); | ||||||||
| 435 | int64_t Offset = 0; | ||||||||
| 436 | for (i = 1; i != e; ++i, ++GTI) { | ||||||||
| 437 | if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) { | ||||||||
| 438 | // Compute the aggregate offset of constant indices. | ||||||||
| 439 | if (CI->isZero()) continue; | ||||||||
| 440 | |||||||||
| 441 | // Handle a struct index, which adds its field offset to the pointer. | ||||||||
| 442 | if (StructType *STy = GTI.getStructTypeOrNull()) { | ||||||||
| 443 | Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); | ||||||||
| 444 | } else { | ||||||||
| 445 | uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType()); | ||||||||
| 446 | Offset += Size*CI->getSExtValue(); | ||||||||
| 447 | } | ||||||||
| 448 | } else { | ||||||||
| 449 | // Found our variable index. | ||||||||
| 450 | break; | ||||||||
| 451 | } | ||||||||
| 452 | } | ||||||||
| 453 | |||||||||
| 454 | // If there are no variable indices, we must have a constant offset, just | ||||||||
| 455 | // evaluate it the general way. | ||||||||
| 456 | if (i == e) return nullptr; | ||||||||
| 457 | |||||||||
| 458 | Value *VariableIdx = GEP->getOperand(i); | ||||||||
| 459 | // Determine the scale factor of the variable element. For example, this is | ||||||||
| 460 | // 4 if the variable index is into an array of i32. | ||||||||
| 461 | uint64_t VariableScale = DL.getTypeAllocSize(GTI.getIndexedType()); | ||||||||
| 462 | |||||||||
| 463 | // Verify that there are no other variable indices. If so, emit the hard way. | ||||||||
| 464 | for (++i, ++GTI; i != e; ++i, ++GTI) { | ||||||||
| 465 | ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i)); | ||||||||
| 466 | if (!CI) return nullptr; | ||||||||
| 467 | |||||||||
| 468 | // Compute the aggregate offset of constant indices. | ||||||||
| 469 | if (CI->isZero()) continue; | ||||||||
| 470 | |||||||||
| 471 | // Handle a struct index, which adds its field offset to the pointer. | ||||||||
| 472 | if (StructType *STy = GTI.getStructTypeOrNull()) { | ||||||||
| 473 | Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); | ||||||||
| 474 | } else { | ||||||||
| 475 | uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType()); | ||||||||
| 476 | Offset += Size*CI->getSExtValue(); | ||||||||
| 477 | } | ||||||||
| 478 | } | ||||||||
| 479 | |||||||||
| 480 | // Okay, we know we have a single variable index, which must be a | ||||||||
| 481 | // pointer/array/vector index. If there is no offset, life is simple, return | ||||||||
| 482 | // the index. | ||||||||
| 483 | Type *IntPtrTy = DL.getIntPtrType(GEP->getOperand(0)->getType()); | ||||||||
| 484 | unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth(); | ||||||||
| 485 | if (Offset == 0) { | ||||||||
| 486 | // Cast to intptrty in case a truncation occurs. If an extension is needed, | ||||||||
| 487 | // we don't need to bother extending: the extension won't affect where the | ||||||||
| 488 | // computation crosses zero. | ||||||||
| 489 | if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) { | ||||||||
| 490 | VariableIdx = IC.Builder.CreateTrunc(VariableIdx, IntPtrTy); | ||||||||
| 491 | } | ||||||||
| 492 | return VariableIdx; | ||||||||
| 493 | } | ||||||||
| 494 | |||||||||
| 495 | // Otherwise, there is an index. The computation we will do will be modulo | ||||||||
| 496 | // the pointer size. | ||||||||
| 497 | Offset = SignExtend64(Offset, IntPtrWidth); | ||||||||
| 498 | VariableScale = SignExtend64(VariableScale, IntPtrWidth); | ||||||||
| 499 | |||||||||
| 500 | // To do this transformation, any constant index must be a multiple of the | ||||||||
| 501 | // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i", | ||||||||
| 502 | // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a | ||||||||
| 503 | // multiple of the variable scale. | ||||||||
| 504 | int64_t NewOffs = Offset / (int64_t)VariableScale; | ||||||||
| 505 | if (Offset != NewOffs*(int64_t)VariableScale) | ||||||||
| 506 | return nullptr; | ||||||||
| 507 | |||||||||
| 508 | // Okay, we can do this evaluation. Start by converting the index to intptr. | ||||||||
| 509 | if (VariableIdx->getType() != IntPtrTy) | ||||||||
| 510 | VariableIdx = IC.Builder.CreateIntCast(VariableIdx, IntPtrTy, | ||||||||
| 511 | true /*Signed*/); | ||||||||
| 512 | Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs); | ||||||||
| 513 | return IC.Builder.CreateAdd(VariableIdx, OffsetVal, "offset"); | ||||||||
| 514 | } | ||||||||
| 515 | |||||||||
| 516 | /// Returns true if we can rewrite Start as a GEP with pointer Base | ||||||||
| 517 | /// and some integer offset. The nodes that need to be re-written | ||||||||
| 518 | /// for this transformation will be added to Explored. | ||||||||
| 519 | static bool canRewriteGEPAsOffset(Value *Start, Value *Base, | ||||||||
| 520 | const DataLayout &DL, | ||||||||
| 521 | SetVector<Value *> &Explored) { | ||||||||
| 522 | SmallVector<Value *, 16> WorkList(1, Start); | ||||||||
| 523 | Explored.insert(Base); | ||||||||
| 524 | |||||||||
| 525 | // The following traversal gives us an order which can be used | ||||||||
| 526 | // when doing the final transformation. Since in the final | ||||||||
| 527 | // transformation we create the PHI replacement instructions first, | ||||||||
| 528 | // we don't have to get them in any particular order. | ||||||||
| 529 | // | ||||||||
| 530 | // However, for other instructions we will have to traverse the | ||||||||
| 531 | // operands of an instruction first, which means that we have to | ||||||||
| 532 | // do a post-order traversal. | ||||||||
| 533 | while (!WorkList.empty()) { | ||||||||
| 534 | SetVector<PHINode *> PHIs; | ||||||||
| 535 | |||||||||
| 536 | while (!WorkList.empty()) { | ||||||||
| 537 | if (Explored.size() >= 100) | ||||||||
| 538 | return false; | ||||||||
| 539 | |||||||||
| 540 | Value *V = WorkList.back(); | ||||||||
| 541 | |||||||||
| 542 | if (Explored.count(V) != 0) { | ||||||||
| 543 | WorkList.pop_back(); | ||||||||
| 544 | continue; | ||||||||
| 545 | } | ||||||||
| 546 | |||||||||
| 547 | if (!isa<IntToPtrInst>(V) && !isa<PtrToIntInst>(V) && | ||||||||
| 548 | !isa<GetElementPtrInst>(V) && !isa<PHINode>(V)) | ||||||||
| 549 | // We've found some value that we can't explore which is different from | ||||||||
| 550 | // the base. Therefore we can't do this transformation. | ||||||||
| 551 | return false; | ||||||||
| 552 | |||||||||
| 553 | if (isa<IntToPtrInst>(V) || isa<PtrToIntInst>(V)) { | ||||||||
| 554 | auto *CI = dyn_cast<CastInst>(V); | ||||||||
| 555 | if (!CI->isNoopCast(DL)) | ||||||||
| 556 | return false; | ||||||||
| 557 | |||||||||
| 558 | if (Explored.count(CI->getOperand(0)) == 0) | ||||||||
| 559 | WorkList.push_back(CI->getOperand(0)); | ||||||||
| 560 | } | ||||||||
| 561 | |||||||||
| 562 | if (auto *GEP = dyn_cast<GEPOperator>(V)) { | ||||||||
| 563 | // We're limiting the GEP to having one index. This will preserve | ||||||||
| 564 | // the original pointer type. We could handle more cases in the | ||||||||
| 565 | // future. | ||||||||
| 566 | if (GEP->getNumIndices() != 1 || !GEP->isInBounds() || | ||||||||
| 567 | GEP->getType() != Start->getType()) | ||||||||
| 568 | return false; | ||||||||
| 569 | |||||||||
| 570 | if (Explored.count(GEP->getOperand(0)) == 0) | ||||||||
| 571 | WorkList.push_back(GEP->getOperand(0)); | ||||||||
| 572 | } | ||||||||
| 573 | |||||||||
| 574 | if (WorkList.back() == V) { | ||||||||
| 575 | WorkList.pop_back(); | ||||||||
| 576 | // We've finished visiting this node, mark it as such. | ||||||||
| 577 | Explored.insert(V); | ||||||||
| 578 | } | ||||||||
| 579 | |||||||||
| 580 | if (auto *PN = dyn_cast<PHINode>(V)) { | ||||||||
| 581 | // We cannot transform PHIs on unsplittable basic blocks. | ||||||||
| 582 | if (isa<CatchSwitchInst>(PN->getParent()->getTerminator())) | ||||||||
| 583 | return false; | ||||||||
| 584 | Explored.insert(PN); | ||||||||
| 585 | PHIs.insert(PN); | ||||||||
| 586 | } | ||||||||
| 587 | } | ||||||||
| 588 | |||||||||
| 589 | // Explore the PHI nodes further. | ||||||||
| 590 | for (auto *PN : PHIs) | ||||||||
| 591 | for (Value *Op : PN->incoming_values()) | ||||||||
| 592 | if (Explored.count(Op) == 0) | ||||||||
| 593 | WorkList.push_back(Op); | ||||||||
| 594 | } | ||||||||
| 595 | |||||||||
| 596 | // Make sure that we can do this. Since we can't insert GEPs in a basic | ||||||||
| 597 | // block before a PHI node, we can't easily do this transformation if | ||||||||
| 598 | // we have PHI node users of transformed instructions. | ||||||||
| 599 | for (Value *Val : Explored) { | ||||||||
| 600 | for (Value *Use : Val->uses()) { | ||||||||
| 601 | |||||||||
| 602 | auto *PHI = dyn_cast<PHINode>(Use); | ||||||||
| 603 | auto *Inst = dyn_cast<Instruction>(Val); | ||||||||
| 604 | |||||||||
| 605 | if (Inst == Base || Inst == PHI || !Inst || !PHI || | ||||||||
| 606 | Explored.count(PHI) == 0) | ||||||||
| 607 | continue; | ||||||||
| 608 | |||||||||
| 609 | if (PHI->getParent() == Inst->getParent()) | ||||||||
| 610 | return false; | ||||||||
| 611 | } | ||||||||
| 612 | } | ||||||||
| 613 | return true; | ||||||||
| 614 | } | ||||||||
| 615 | |||||||||
| 616 | // Sets the appropriate insert point on Builder where we can add | ||||||||
| 617 | // a replacement Instruction for V (if that is possible). | ||||||||
| 618 | static void setInsertionPoint(IRBuilder<> &Builder, Value *V, | ||||||||
| 619 | bool Before = true) { | ||||||||
| 620 | if (auto *PHI = dyn_cast<PHINode>(V)) { | ||||||||
| 621 | Builder.SetInsertPoint(&*PHI->getParent()->getFirstInsertionPt()); | ||||||||
| 622 | return; | ||||||||
| 623 | } | ||||||||
| 624 | if (auto *I = dyn_cast<Instruction>(V)) { | ||||||||
| 625 | if (!Before) | ||||||||
| 626 | I = &*std::next(I->getIterator()); | ||||||||
| 627 | Builder.SetInsertPoint(I); | ||||||||
| 628 | return; | ||||||||
| 629 | } | ||||||||
| 630 | if (auto *A = dyn_cast<Argument>(V)) { | ||||||||
| 631 | // Set the insertion point in the entry block. | ||||||||
| 632 | BasicBlock &Entry = A->getParent()->getEntryBlock(); | ||||||||
| 633 | Builder.SetInsertPoint(&*Entry.getFirstInsertionPt()); | ||||||||
| 634 | return; | ||||||||
| 635 | } | ||||||||
| 636 | // Otherwise, this is a constant and we don't need to set a new | ||||||||
| 637 | // insertion point. | ||||||||
| 638 | 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!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 638, __PRETTY_FUNCTION__)); | ||||||||
| 639 | } | ||||||||
| 640 | |||||||||
| 641 | /// Returns a re-written value of Start as an indexed GEP using Base as a | ||||||||
| 642 | /// pointer. | ||||||||
| 643 | static Value *rewriteGEPAsOffset(Value *Start, Value *Base, | ||||||||
| 644 | const DataLayout &DL, | ||||||||
| 645 | SetVector<Value *> &Explored) { | ||||||||
| 646 | // Perform all the substitutions. This is a bit tricky because we can | ||||||||
| 647 | // have cycles in our use-def chains. | ||||||||
| 648 | // 1. Create the PHI nodes without any incoming values. | ||||||||
| 649 | // 2. Create all the other values. | ||||||||
| 650 | // 3. Add the edges for the PHI nodes. | ||||||||
| 651 | // 4. Emit GEPs to get the original pointers. | ||||||||
| 652 | // 5. Remove the original instructions. | ||||||||
| 653 | Type *IndexType = IntegerType::get( | ||||||||
| 654 | Base->getContext(), DL.getIndexTypeSizeInBits(Start->getType())); | ||||||||
| 655 | |||||||||
| 656 | DenseMap<Value *, Value *> NewInsts; | ||||||||
| 657 | NewInsts[Base] = ConstantInt::getNullValue(IndexType); | ||||||||
| 658 | |||||||||
| 659 | // Create the new PHI nodes, without adding any incoming values. | ||||||||
| 660 | for (Value *Val : Explored) { | ||||||||
| 661 | if (Val == Base) | ||||||||
| 662 | continue; | ||||||||
| 663 | // Create empty phi nodes. This avoids cyclic dependencies when creating | ||||||||
| 664 | // the remaining instructions. | ||||||||
| 665 | if (auto *PHI = dyn_cast<PHINode>(Val)) | ||||||||
| 666 | NewInsts[PHI] = PHINode::Create(IndexType, PHI->getNumIncomingValues(), | ||||||||
| 667 | PHI->getName() + ".idx", PHI); | ||||||||
| 668 | } | ||||||||
| 669 | IRBuilder<> Builder(Base->getContext()); | ||||||||
| 670 | |||||||||
| 671 | // Create all the other instructions. | ||||||||
| 672 | for (Value *Val : Explored) { | ||||||||
| 673 | |||||||||
| 674 | if (NewInsts.find(Val) != NewInsts.end()) | ||||||||
| 675 | continue; | ||||||||
| 676 | |||||||||
| 677 | if (auto *CI = dyn_cast<CastInst>(Val)) { | ||||||||
| 678 | // Don't get rid of the intermediate variable here; the store can grow | ||||||||
| 679 | // the map which will invalidate the reference to the input value. | ||||||||
| 680 | Value *V = NewInsts[CI->getOperand(0)]; | ||||||||
| 681 | NewInsts[CI] = V; | ||||||||
| 682 | continue; | ||||||||
| 683 | } | ||||||||
| 684 | if (auto *GEP = dyn_cast<GEPOperator>(Val)) { | ||||||||
| 685 | Value *Index = NewInsts[GEP->getOperand(1)] ? NewInsts[GEP->getOperand(1)] | ||||||||
| 686 | : GEP->getOperand(1); | ||||||||
| 687 | setInsertionPoint(Builder, GEP); | ||||||||
| 688 | // Indices might need to be sign extended. GEPs will magically do | ||||||||
| 689 | // this, but we need to do it ourselves here. | ||||||||
| 690 | if (Index->getType()->getScalarSizeInBits() != | ||||||||
| 691 | NewInsts[GEP->getOperand(0)]->getType()->getScalarSizeInBits()) { | ||||||||
| 692 | Index = Builder.CreateSExtOrTrunc( | ||||||||
| 693 | Index, NewInsts[GEP->getOperand(0)]->getType(), | ||||||||
| 694 | GEP->getOperand(0)->getName() + ".sext"); | ||||||||
| 695 | } | ||||||||
| 696 | |||||||||
| 697 | auto *Op = NewInsts[GEP->getOperand(0)]; | ||||||||
| 698 | if (isa<ConstantInt>(Op) && cast<ConstantInt>(Op)->isZero()) | ||||||||
| 699 | NewInsts[GEP] = Index; | ||||||||
| 700 | else | ||||||||
| 701 | NewInsts[GEP] = Builder.CreateNSWAdd( | ||||||||
| 702 | Op, Index, GEP->getOperand(0)->getName() + ".add"); | ||||||||
| 703 | continue; | ||||||||
| 704 | } | ||||||||
| 705 | if (isa<PHINode>(Val)) | ||||||||
| 706 | continue; | ||||||||
| 707 | |||||||||
| 708 | llvm_unreachable("Unexpected instruction type")::llvm::llvm_unreachable_internal("Unexpected instruction type" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 708); | ||||||||
| 709 | } | ||||||||
| 710 | |||||||||
| 711 | // Add the incoming values to the PHI nodes. | ||||||||
| 712 | for (Value *Val : Explored) { | ||||||||
| 713 | if (Val == Base) | ||||||||
| 714 | continue; | ||||||||
| 715 | // All the instructions have been created, we can now add edges to the | ||||||||
| 716 | // phi nodes. | ||||||||
| 717 | if (auto *PHI = dyn_cast<PHINode>(Val)) { | ||||||||
| 718 | PHINode *NewPhi = static_cast<PHINode *>(NewInsts[PHI]); | ||||||||
| 719 | for (unsigned I = 0, E = PHI->getNumIncomingValues(); I < E; ++I) { | ||||||||
| 720 | Value *NewIncoming = PHI->getIncomingValue(I); | ||||||||
| 721 | |||||||||
| 722 | if (NewInsts.find(NewIncoming) != NewInsts.end()) | ||||||||
| 723 | NewIncoming = NewInsts[NewIncoming]; | ||||||||
| 724 | |||||||||
| 725 | NewPhi->addIncoming(NewIncoming, PHI->getIncomingBlock(I)); | ||||||||
| 726 | } | ||||||||
| 727 | } | ||||||||
| 728 | } | ||||||||
| 729 | |||||||||
| 730 | for (Value *Val : Explored) { | ||||||||
| 731 | if (Val == Base) | ||||||||
| 732 | continue; | ||||||||
| 733 | |||||||||
| 734 | // Depending on the type, for external users we have to emit | ||||||||
| 735 | // a GEP or a GEP + ptrtoint. | ||||||||
| 736 | setInsertionPoint(Builder, Val, false); | ||||||||
| 737 | |||||||||
| 738 | // If required, create an inttoptr instruction for Base. | ||||||||
| 739 | Value *NewBase = Base; | ||||||||
| 740 | if (!Base->getType()->isPointerTy()) | ||||||||
| 741 | NewBase = Builder.CreateBitOrPointerCast(Base, Start->getType(), | ||||||||
| 742 | Start->getName() + "to.ptr"); | ||||||||
| 743 | |||||||||
| 744 | Value *GEP = Builder.CreateInBoundsGEP( | ||||||||
| 745 | Start->getType()->getPointerElementType(), NewBase, | ||||||||
| 746 | makeArrayRef(NewInsts[Val]), Val->getName() + ".ptr"); | ||||||||
| 747 | |||||||||
| 748 | if (!Val->getType()->isPointerTy()) { | ||||||||
| 749 | Value *Cast = Builder.CreatePointerCast(GEP, Val->getType(), | ||||||||
| 750 | Val->getName() + ".conv"); | ||||||||
| 751 | GEP = Cast; | ||||||||
| 752 | } | ||||||||
| 753 | Val->replaceAllUsesWith(GEP); | ||||||||
| 754 | } | ||||||||
| 755 | |||||||||
| 756 | return NewInsts[Start]; | ||||||||
| 757 | } | ||||||||
| 758 | |||||||||
| 759 | /// Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express | ||||||||
| 760 | /// the input Value as a constant indexed GEP. Returns a pair containing | ||||||||
| 761 | /// the GEPs Pointer and Index. | ||||||||
| 762 | static std::pair<Value *, Value *> | ||||||||
| 763 | getAsConstantIndexedAddress(Value *V, const DataLayout &DL) { | ||||||||
| 764 | Type *IndexType = IntegerType::get(V->getContext(), | ||||||||
| 765 | DL.getIndexTypeSizeInBits(V->getType())); | ||||||||
| 766 | |||||||||
| 767 | Constant *Index = ConstantInt::getNullValue(IndexType); | ||||||||
| 768 | while (true) { | ||||||||
| 769 | if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { | ||||||||
| 770 | // We accept only inbouds GEPs here to exclude the possibility of | ||||||||
| 771 | // overflow. | ||||||||
| 772 | if (!GEP->isInBounds()) | ||||||||
| 773 | break; | ||||||||
| 774 | if (GEP->hasAllConstantIndices() && GEP->getNumIndices() == 1 && | ||||||||
| 775 | GEP->getType() == V->getType()) { | ||||||||
| 776 | V = GEP->getOperand(0); | ||||||||
| 777 | Constant *GEPIndex = static_cast<Constant *>(GEP->getOperand(1)); | ||||||||
| 778 | Index = ConstantExpr::getAdd( | ||||||||
| 779 | Index, ConstantExpr::getSExtOrBitCast(GEPIndex, IndexType)); | ||||||||
| 780 | continue; | ||||||||
| 781 | } | ||||||||
| 782 | break; | ||||||||
| 783 | } | ||||||||
| 784 | if (auto *CI = dyn_cast<IntToPtrInst>(V)) { | ||||||||
| 785 | if (!CI->isNoopCast(DL)) | ||||||||
| 786 | break; | ||||||||
| 787 | V = CI->getOperand(0); | ||||||||
| 788 | continue; | ||||||||
| 789 | } | ||||||||
| 790 | if (auto *CI = dyn_cast<PtrToIntInst>(V)) { | ||||||||
| 791 | if (!CI->isNoopCast(DL)) | ||||||||
| 792 | break; | ||||||||
| 793 | V = CI->getOperand(0); | ||||||||
| 794 | continue; | ||||||||
| 795 | } | ||||||||
| 796 | break; | ||||||||
| 797 | } | ||||||||
| 798 | return {V, Index}; | ||||||||
| 799 | } | ||||||||
| 800 | |||||||||
| 801 | /// Converts (CMP GEPLHS, RHS) if this change would make RHS a constant. | ||||||||
| 802 | /// We can look through PHIs, GEPs and casts in order to determine a common base | ||||||||
| 803 | /// between GEPLHS and RHS. | ||||||||
| 804 | static Instruction *transformToIndexedCompare(GEPOperator *GEPLHS, Value *RHS, | ||||||||
| 805 | ICmpInst::Predicate Cond, | ||||||||
| 806 | const DataLayout &DL) { | ||||||||
| 807 | // FIXME: Support vector of pointers. | ||||||||
| 808 | if (GEPLHS->getType()->isVectorTy()) | ||||||||
| 809 | return nullptr; | ||||||||
| 810 | |||||||||
| 811 | if (!GEPLHS->hasAllConstantIndices()) | ||||||||
| 812 | return nullptr; | ||||||||
| 813 | |||||||||
| 814 | // Make sure the pointers have the same type. | ||||||||
| 815 | if (GEPLHS->getType() != RHS->getType()) | ||||||||
| 816 | return nullptr; | ||||||||
| 817 | |||||||||
| 818 | Value *PtrBase, *Index; | ||||||||
| 819 | std::tie(PtrBase, Index) = getAsConstantIndexedAddress(GEPLHS, DL); | ||||||||
| 820 | |||||||||
| 821 | // The set of nodes that will take part in this transformation. | ||||||||
| 822 | SetVector<Value *> Nodes; | ||||||||
| 823 | |||||||||
| 824 | if (!canRewriteGEPAsOffset(RHS, PtrBase, DL, Nodes)) | ||||||||
| 825 | return nullptr; | ||||||||
| 826 | |||||||||
| 827 | // We know we can re-write this as | ||||||||
| 828 | // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) | ||||||||
| 829 | // Since we've only looked through inbouds GEPs we know that we | ||||||||
| 830 | // can't have overflow on either side. We can therefore re-write | ||||||||
| 831 | // this as: | ||||||||
| 832 | // OFFSET1 cmp OFFSET2 | ||||||||
| 833 | Value *NewRHS = rewriteGEPAsOffset(RHS, PtrBase, DL, Nodes); | ||||||||
| 834 | |||||||||
| 835 | // RewriteGEPAsOffset has replaced RHS and all of its uses with a re-written | ||||||||
| 836 | // GEP having PtrBase as the pointer base, and has returned in NewRHS the | ||||||||
| 837 | // offset. Since Index is the offset of LHS to the base pointer, we will now | ||||||||
| 838 | // compare the offsets instead of comparing the pointers. | ||||||||
| 839 | return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Index, NewRHS); | ||||||||
| 840 | } | ||||||||
| 841 | |||||||||
| 842 | /// Fold comparisons between a GEP instruction and something else. At this point | ||||||||
| 843 | /// we know that the GEP is on the LHS of the comparison. | ||||||||
| 844 | Instruction *InstCombiner::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS, | ||||||||
| 845 | ICmpInst::Predicate Cond, | ||||||||
| 846 | Instruction &I) { | ||||||||
| 847 | // Don't transform signed compares of GEPs into index compares. Even if the | ||||||||
| 848 | // GEP is inbounds, the final add of the base pointer can have signed overflow | ||||||||
| 849 | // and would change the result of the icmp. | ||||||||
| 850 | // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be | ||||||||
| 851 | // the maximum signed value for the pointer type. | ||||||||
| 852 | if (ICmpInst::isSigned(Cond)) | ||||||||
| 853 | return nullptr; | ||||||||
| 854 | |||||||||
| 855 | // Look through bitcasts and addrspacecasts. We do not however want to remove | ||||||||
| 856 | // 0 GEPs. | ||||||||
| 857 | if (!isa<GetElementPtrInst>(RHS)) | ||||||||
| 858 | RHS = RHS->stripPointerCasts(); | ||||||||
| 859 | |||||||||
| 860 | Value *PtrBase = GEPLHS->getOperand(0); | ||||||||
| 861 | // FIXME: Support vector pointer GEPs. | ||||||||
| 862 | if (PtrBase == RHS && GEPLHS->isInBounds() && | ||||||||
| 863 | !GEPLHS->getType()->isVectorTy()) { | ||||||||
| 864 | // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0). | ||||||||
| 865 | // This transformation (ignoring the base and scales) is valid because we | ||||||||
| 866 | // know pointers can't overflow since the gep is inbounds. See if we can | ||||||||
| 867 | // output an optimized form. | ||||||||
| 868 | Value *Offset = evaluateGEPOffsetExpression(GEPLHS, *this, DL); | ||||||||
| 869 | |||||||||
| 870 | // If not, synthesize the offset the hard way. | ||||||||
| 871 | if (!Offset) | ||||||||
| 872 | Offset = EmitGEPOffset(GEPLHS); | ||||||||
| 873 | return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset, | ||||||||
| 874 | Constant::getNullValue(Offset->getType())); | ||||||||
| 875 | } | ||||||||
| 876 | |||||||||
| 877 | if (GEPLHS->isInBounds() && ICmpInst::isEquality(Cond) && | ||||||||
| 878 | isa<Constant>(RHS) && cast<Constant>(RHS)->isNullValue() && | ||||||||
| 879 | !NullPointerIsDefined(I.getFunction(), | ||||||||
| 880 | RHS->getType()->getPointerAddressSpace())) { | ||||||||
| 881 | // For most address spaces, an allocation can't be placed at null, but null | ||||||||
| 882 | // itself is treated as a 0 size allocation in the in bounds rules. Thus, | ||||||||
| 883 | // the only valid inbounds address derived from null, is null itself. | ||||||||
| 884 | // Thus, we have four cases to consider: | ||||||||
| 885 | // 1) Base == nullptr, Offset == 0 -> inbounds, null | ||||||||
| 886 | // 2) Base == nullptr, Offset != 0 -> poison as the result is out of bounds | ||||||||
| 887 | // 3) Base != nullptr, Offset == (-base) -> poison (crossing allocations) | ||||||||
| 888 | // 4) Base != nullptr, Offset != (-base) -> nonnull (and possibly poison) | ||||||||
| 889 | // | ||||||||
| 890 | // (Note if we're indexing a type of size 0, that simply collapses into one | ||||||||
| 891 | // of the buckets above.) | ||||||||
| 892 | // | ||||||||
| 893 | // In general, we're allowed to make values less poison (i.e. remove | ||||||||
| 894 | // sources of full UB), so in this case, we just select between the two | ||||||||
| 895 | // non-poison cases (1 and 4 above). | ||||||||
| 896 | // | ||||||||
| 897 | // For vectors, we apply the same reasoning on a per-lane basis. | ||||||||
| 898 | auto *Base = GEPLHS->getPointerOperand(); | ||||||||
| 899 | if (GEPLHS->getType()->isVectorTy() && Base->getType()->isPointerTy()) { | ||||||||
| 900 | int NumElts = GEPLHS->getType()->getVectorNumElements(); | ||||||||
| 901 | Base = Builder.CreateVectorSplat(NumElts, Base); | ||||||||
| 902 | } | ||||||||
| 903 | return new ICmpInst(Cond, Base, | ||||||||
| 904 | ConstantExpr::getPointerBitCastOrAddrSpaceCast( | ||||||||
| 905 | cast<Constant>(RHS), Base->getType())); | ||||||||
| 906 | } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) { | ||||||||
| 907 | // If the base pointers are different, but the indices are the same, just | ||||||||
| 908 | // compare the base pointer. | ||||||||
| 909 | if (PtrBase != GEPRHS->getOperand(0)) { | ||||||||
| 910 | bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands(); | ||||||||
| 911 | IndicesTheSame &= GEPLHS->getOperand(0)->getType() == | ||||||||
| 912 | GEPRHS->getOperand(0)->getType(); | ||||||||
| 913 | if (IndicesTheSame) | ||||||||
| 914 | for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) | ||||||||
| 915 | if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { | ||||||||
| 916 | IndicesTheSame = false; | ||||||||
| 917 | break; | ||||||||
| 918 | } | ||||||||
| 919 | |||||||||
| 920 | // If all indices are the same, just compare the base pointers. | ||||||||
| 921 | Type *BaseType = GEPLHS->getOperand(0)->getType(); | ||||||||
| 922 | if (IndicesTheSame && CmpInst::makeCmpResultType(BaseType) == I.getType()) | ||||||||
| 923 | return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0)); | ||||||||
| 924 | |||||||||
| 925 | // If we're comparing GEPs with two base pointers that only differ in type | ||||||||
| 926 | // and both GEPs have only constant indices or just one use, then fold | ||||||||
| 927 | // the compare with the adjusted indices. | ||||||||
| 928 | // FIXME: Support vector of pointers. | ||||||||
| 929 | if (GEPLHS->isInBounds() && GEPRHS->isInBounds() && | ||||||||
| 930 | (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) && | ||||||||
| 931 | (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) && | ||||||||
| 932 | PtrBase->stripPointerCasts() == | ||||||||
| 933 | GEPRHS->getOperand(0)->stripPointerCasts() && | ||||||||
| 934 | !GEPLHS->getType()->isVectorTy()) { | ||||||||
| 935 | Value *LOffset = EmitGEPOffset(GEPLHS); | ||||||||
| 936 | Value *ROffset = EmitGEPOffset(GEPRHS); | ||||||||
| 937 | |||||||||
| 938 | // If we looked through an addrspacecast between different sized address | ||||||||
| 939 | // spaces, the LHS and RHS pointers are different sized | ||||||||
| 940 | // integers. Truncate to the smaller one. | ||||||||
| 941 | Type *LHSIndexTy = LOffset->getType(); | ||||||||
| 942 | Type *RHSIndexTy = ROffset->getType(); | ||||||||
| 943 | if (LHSIndexTy != RHSIndexTy) { | ||||||||
| 944 | if (LHSIndexTy->getPrimitiveSizeInBits() < | ||||||||
| 945 | RHSIndexTy->getPrimitiveSizeInBits()) { | ||||||||
| 946 | ROffset = Builder.CreateTrunc(ROffset, LHSIndexTy); | ||||||||
| 947 | } else | ||||||||
| 948 | LOffset = Builder.CreateTrunc(LOffset, RHSIndexTy); | ||||||||
| 949 | } | ||||||||
| 950 | |||||||||
| 951 | Value *Cmp = Builder.CreateICmp(ICmpInst::getSignedPredicate(Cond), | ||||||||
| 952 | LOffset, ROffset); | ||||||||
| 953 | return replaceInstUsesWith(I, Cmp); | ||||||||
| 954 | } | ||||||||
| 955 | |||||||||
| 956 | // Otherwise, the base pointers are different and the indices are | ||||||||
| 957 | // different. Try convert this to an indexed compare by looking through | ||||||||
| 958 | // PHIs/casts. | ||||||||
| 959 | return transformToIndexedCompare(GEPLHS, RHS, Cond, DL); | ||||||||
| 960 | } | ||||||||
| 961 | |||||||||
| 962 | // If one of the GEPs has all zero indices, recurse. | ||||||||
| 963 | // FIXME: Handle vector of pointers. | ||||||||
| 964 | if (!GEPLHS->getType()->isVectorTy() && GEPLHS->hasAllZeroIndices()) | ||||||||
| 965 | return foldGEPICmp(GEPRHS, GEPLHS->getOperand(0), | ||||||||
| 966 | ICmpInst::getSwappedPredicate(Cond), I); | ||||||||
| 967 | |||||||||
| 968 | // If the other GEP has all zero indices, recurse. | ||||||||
| 969 | // FIXME: Handle vector of pointers. | ||||||||
| 970 | if (!GEPRHS->getType()->isVectorTy() && GEPRHS->hasAllZeroIndices()) | ||||||||
| 971 | return foldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I); | ||||||||
| 972 | |||||||||
| 973 | bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds(); | ||||||||
| 974 | if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { | ||||||||
| 975 | // If the GEPs only differ by one index, compare it. | ||||||||
| 976 | unsigned NumDifferences = 0; // Keep track of # differences. | ||||||||
| 977 | unsigned DiffOperand = 0; // The operand that differs. | ||||||||
| 978 | for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) | ||||||||
| 979 | if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { | ||||||||
| 980 | Type *LHSType = GEPLHS->getOperand(i)->getType(); | ||||||||
| 981 | Type *RHSType = GEPRHS->getOperand(i)->getType(); | ||||||||
| 982 | // FIXME: Better support for vector of pointers. | ||||||||
| 983 | if (LHSType->getPrimitiveSizeInBits() != | ||||||||
| 984 | RHSType->getPrimitiveSizeInBits() || | ||||||||
| 985 | (GEPLHS->getType()->isVectorTy() && | ||||||||
| 986 | (!LHSType->isVectorTy() || !RHSType->isVectorTy()))) { | ||||||||
| 987 | // Irreconcilable differences. | ||||||||
| 988 | NumDifferences = 2; | ||||||||
| 989 | break; | ||||||||
| 990 | } | ||||||||
| 991 | |||||||||
| 992 | if (NumDifferences++) break; | ||||||||
| 993 | DiffOperand = i; | ||||||||
| 994 | } | ||||||||
| 995 | |||||||||
| 996 | if (NumDifferences == 0) // SAME GEP? | ||||||||
| 997 | return replaceInstUsesWith(I, // No comparison is needed here. | ||||||||
| 998 | ConstantInt::get(I.getType(), ICmpInst::isTrueWhenEqual(Cond))); | ||||||||
| 999 | |||||||||
| 1000 | else if (NumDifferences == 1 && GEPsInBounds) { | ||||||||
| 1001 | Value *LHSV = GEPLHS->getOperand(DiffOperand); | ||||||||
| 1002 | Value *RHSV = GEPRHS->getOperand(DiffOperand); | ||||||||
| 1003 | // Make sure we do a signed comparison here. | ||||||||
| 1004 | return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV); | ||||||||
| 1005 | } | ||||||||
| 1006 | } | ||||||||
| 1007 | |||||||||
| 1008 | // Only lower this if the icmp is the only user of the GEP or if we expect | ||||||||
| 1009 | // the result to fold to a constant! | ||||||||
| 1010 | if (GEPsInBounds && (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) && | ||||||||
| 1011 | (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) { | ||||||||
| 1012 | // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) | ||||||||
| 1013 | Value *L = EmitGEPOffset(GEPLHS); | ||||||||
| 1014 | Value *R = EmitGEPOffset(GEPRHS); | ||||||||
| 1015 | return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R); | ||||||||
| 1016 | } | ||||||||
| 1017 | } | ||||||||
| 1018 | |||||||||
| 1019 | // Try convert this to an indexed compare by looking through PHIs/casts as a | ||||||||
| 1020 | // last resort. | ||||||||
| 1021 | return transformToIndexedCompare(GEPLHS, RHS, Cond, DL); | ||||||||
| 1022 | } | ||||||||
| 1023 | |||||||||
| 1024 | Instruction *InstCombiner::foldAllocaCmp(ICmpInst &ICI, | ||||||||
| 1025 | const AllocaInst *Alloca, | ||||||||
| 1026 | const Value *Other) { | ||||||||
| 1027 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 1027, __PRETTY_FUNCTION__)); | ||||||||
| 1028 | |||||||||
| 1029 | // It would be tempting to fold away comparisons between allocas and any | ||||||||
| 1030 | // pointer not based on that alloca (e.g. an argument). However, even | ||||||||
| 1031 | // though such pointers cannot alias, they can still compare equal. | ||||||||
| 1032 | // | ||||||||
| 1033 | // But LLVM doesn't specify where allocas get their memory, so if the alloca | ||||||||
| 1034 | // doesn't escape we can argue that it's impossible to guess its value, and we | ||||||||
| 1035 | // can therefore act as if any such guesses are wrong. | ||||||||
| 1036 | // | ||||||||
| 1037 | // The code below checks that the alloca doesn't escape, and that it's only | ||||||||
| 1038 | // used in a comparison once (the current instruction). The | ||||||||
| 1039 | // single-comparison-use condition ensures that we're trivially folding all | ||||||||
| 1040 | // comparisons against the alloca consistently, and avoids the risk of | ||||||||
| 1041 | // erroneously folding a comparison of the pointer with itself. | ||||||||
| 1042 | |||||||||
| 1043 | unsigned MaxIter = 32; // Break cycles and bound to constant-time. | ||||||||
| 1044 | |||||||||
| 1045 | SmallVector<const Use *, 32> Worklist; | ||||||||
| 1046 | for (const Use &U : Alloca->uses()) { | ||||||||
| 1047 | if (Worklist.size() >= MaxIter) | ||||||||
| 1048 | return nullptr; | ||||||||
| 1049 | Worklist.push_back(&U); | ||||||||
| 1050 | } | ||||||||
| 1051 | |||||||||
| 1052 | unsigned NumCmps = 0; | ||||||||
| 1053 | while (!Worklist.empty()) { | ||||||||
| 1054 | assert(Worklist.size() <= MaxIter)((Worklist.size() <= MaxIter) ? static_cast<void> (0 ) : __assert_fail ("Worklist.size() <= MaxIter", "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 1054, __PRETTY_FUNCTION__)); | ||||||||
| 1055 | const Use *U = Worklist.pop_back_val(); | ||||||||
| 1056 | const Value *V = U->getUser(); | ||||||||
| 1057 | --MaxIter; | ||||||||
| 1058 | |||||||||
| 1059 | if (isa<BitCastInst>(V) || isa<GetElementPtrInst>(V) || isa<PHINode>(V) || | ||||||||
| 1060 | isa<SelectInst>(V)) { | ||||||||
| 1061 | // Track the uses. | ||||||||
| 1062 | } else if (isa<LoadInst>(V)) { | ||||||||
| 1063 | // Loading from the pointer doesn't escape it. | ||||||||
| 1064 | continue; | ||||||||
| 1065 | } else if (const auto *SI = dyn_cast<StoreInst>(V)) { | ||||||||
| 1066 | // Storing *to* the pointer is fine, but storing the pointer escapes it. | ||||||||
| 1067 | if (SI->getValueOperand() == U->get()) | ||||||||
| 1068 | return nullptr; | ||||||||
| 1069 | continue; | ||||||||
| 1070 | } else if (isa<ICmpInst>(V)) { | ||||||||
| 1071 | if (NumCmps++) | ||||||||
| 1072 | return nullptr; // Found more than one cmp. | ||||||||
| 1073 | continue; | ||||||||
| 1074 | } else if (const auto *Intrin = dyn_cast<IntrinsicInst>(V)) { | ||||||||
| 1075 | switch (Intrin->getIntrinsicID()) { | ||||||||
| 1076 | // These intrinsics don't escape or compare the pointer. Memset is safe | ||||||||
| 1077 | // because we don't allow ptrtoint. Memcpy and memmove are safe because | ||||||||
| 1078 | // we don't allow stores, so src cannot point to V. | ||||||||
| 1079 | case Intrinsic::lifetime_start: case Intrinsic::lifetime_end: | ||||||||
| 1080 | case Intrinsic::memcpy: case Intrinsic::memmove: case Intrinsic::memset: | ||||||||
| 1081 | continue; | ||||||||
| 1082 | default: | ||||||||
| 1083 | return nullptr; | ||||||||
| 1084 | } | ||||||||
| 1085 | } else { | ||||||||
| 1086 | return nullptr; | ||||||||
| 1087 | } | ||||||||
| 1088 | for (const Use &U : V->uses()) { | ||||||||
| 1089 | if (Worklist.size() >= MaxIter) | ||||||||
| 1090 | return nullptr; | ||||||||
| 1091 | Worklist.push_back(&U); | ||||||||
| 1092 | } | ||||||||
| 1093 | } | ||||||||
| 1094 | |||||||||
| 1095 | Type *CmpTy = CmpInst::makeCmpResultType(Other->getType()); | ||||||||
| 1096 | return replaceInstUsesWith( | ||||||||
| 1097 | ICI, | ||||||||
| 1098 | ConstantInt::get(CmpTy, !CmpInst::isTrueWhenEqual(ICI.getPredicate()))); | ||||||||
| 1099 | } | ||||||||
| 1100 | |||||||||
| 1101 | /// Fold "icmp pred (X+C), X". | ||||||||
| 1102 | Instruction *InstCombiner::foldICmpAddOpConst(Value *X, const APInt &C, | ||||||||
| 1103 | ICmpInst::Predicate Pred) { | ||||||||
| 1104 | // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0, | ||||||||
| 1105 | // so the values can never be equal. Similarly for all other "or equals" | ||||||||
| 1106 | // operators. | ||||||||
| 1107 | assert(!!C && "C should not be zero!")((!!C && "C should not be zero!") ? static_cast<void > (0) : __assert_fail ("!!C && \"C should not be zero!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 1107, __PRETTY_FUNCTION__)); | ||||||||
| 1108 | |||||||||
| 1109 | // (X+1) <u X --> X >u (MAXUINT-1) --> X == 255 | ||||||||
| 1110 | // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253 | ||||||||
| 1111 | // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0 | ||||||||
| 1112 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { | ||||||||
| 1113 | Constant *R = ConstantInt::get(X->getType(), | ||||||||
| 1114 | APInt::getMaxValue(C.getBitWidth()) - C); | ||||||||
| 1115 | return new ICmpInst(ICmpInst::ICMP_UGT, X, R); | ||||||||
| 1116 | } | ||||||||
| 1117 | |||||||||
| 1118 | // (X+1) >u X --> X <u (0-1) --> X != 255 | ||||||||
| 1119 | // (X+2) >u X --> X <u (0-2) --> X <u 254 | ||||||||
| 1120 | // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0 | ||||||||
| 1121 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) | ||||||||
| 1122 | return new ICmpInst(ICmpInst::ICMP_ULT, X, | ||||||||
| 1123 | ConstantInt::get(X->getType(), -C)); | ||||||||
| 1124 | |||||||||
| 1125 | APInt SMax = APInt::getSignedMaxValue(C.getBitWidth()); | ||||||||
| 1126 | |||||||||
| 1127 | // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127 | ||||||||
| 1128 | // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125 | ||||||||
| 1129 | // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0 | ||||||||
| 1130 | // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1 | ||||||||
| 1131 | // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126 | ||||||||
| 1132 | // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127 | ||||||||
| 1133 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) | ||||||||
| 1134 | return new ICmpInst(ICmpInst::ICMP_SGT, X, | ||||||||
| 1135 | ConstantInt::get(X->getType(), SMax - C)); | ||||||||
| 1136 | |||||||||
| 1137 | // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127 | ||||||||
| 1138 | // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126 | ||||||||
| 1139 | // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1 | ||||||||
| 1140 | // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2 | ||||||||
| 1141 | // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126 | ||||||||
| 1142 | // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128 | ||||||||
| 1143 | |||||||||
| 1144 | 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" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 1144, __PRETTY_FUNCTION__)); | ||||||||
| 1145 | return new ICmpInst(ICmpInst::ICMP_SLT, X, | ||||||||
| 1146 | ConstantInt::get(X->getType(), SMax - (C - 1))); | ||||||||
| 1147 | } | ||||||||
| 1148 | |||||||||
| 1149 | /// Handle "(icmp eq/ne (ashr/lshr AP2, A), AP1)" -> | ||||||||
| 1150 | /// (icmp eq/ne A, Log2(AP2/AP1)) -> | ||||||||
| 1151 | /// (icmp eq/ne A, Log2(AP2) - Log2(AP1)). | ||||||||
| 1152 | Instruction *InstCombiner::foldICmpShrConstConst(ICmpInst &I, Value *A, | ||||||||
| 1153 | const APInt &AP1, | ||||||||
| 1154 | const APInt &AP2) { | ||||||||
| 1155 | 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\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 1155, __PRETTY_FUNCTION__)); | ||||||||
| 1156 | |||||||||
| 1157 | auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) { | ||||||||
| 1158 | if (I.getPredicate() == I.ICMP_NE) | ||||||||
| 1159 | Pred = CmpInst::getInversePredicate(Pred); | ||||||||
| 1160 | return new ICmpInst(Pred, LHS, RHS); | ||||||||
| 1161 | }; | ||||||||
| 1162 | |||||||||
| 1163 | // Don't bother doing any work for cases which InstSimplify handles. | ||||||||
| 1164 | if (AP2.isNullValue()) | ||||||||
| 1165 | return nullptr; | ||||||||
| 1166 | |||||||||
| 1167 | bool IsAShr = isa<AShrOperator>(I.getOperand(0)); | ||||||||
| 1168 | if (IsAShr) { | ||||||||
| 1169 | if (AP2.isAllOnesValue()) | ||||||||
| 1170 | return nullptr; | ||||||||
| 1171 | if (AP2.isNegative() != AP1.isNegative()) | ||||||||
| 1172 | return nullptr; | ||||||||
| 1173 | if (AP2.sgt(AP1)) | ||||||||
| 1174 | return nullptr; | ||||||||
| 1175 | } | ||||||||
| 1176 | |||||||||
| 1177 | if (!AP1) | ||||||||
| 1178 | // 'A' must be large enough to shift out the highest set bit. | ||||||||
| 1179 | return getICmp(I.ICMP_UGT, A, | ||||||||
| 1180 | ConstantInt::get(A->getType(), AP2.logBase2())); | ||||||||
| 1181 | |||||||||
| 1182 | if (AP1 == AP2) | ||||||||
| 1183 | return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType())); | ||||||||
| 1184 | |||||||||
| 1185 | int Shift; | ||||||||
| 1186 | if (IsAShr && AP1.isNegative()) | ||||||||
| 1187 | Shift = AP1.countLeadingOnes() - AP2.countLeadingOnes(); | ||||||||
| 1188 | else | ||||||||
| 1189 | Shift = AP1.countLeadingZeros() - AP2.countLeadingZeros(); | ||||||||
| 1190 | |||||||||
| 1191 | if (Shift > 0) { | ||||||||
| 1192 | if (IsAShr && AP1 == AP2.ashr(Shift)) { | ||||||||
| 1193 | // There are multiple solutions if we are comparing against -1 and the LHS | ||||||||
| 1194 | // of the ashr is not a power of two. | ||||||||
| 1195 | if (AP1.isAllOnesValue() && !AP2.isPowerOf2()) | ||||||||
| 1196 | return getICmp(I.ICMP_UGE, A, ConstantInt::get(A->getType(), Shift)); | ||||||||
| 1197 | return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift)); | ||||||||
| 1198 | } else if (AP1 == AP2.lshr(Shift)) { | ||||||||
| 1199 | return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift)); | ||||||||
| 1200 | } | ||||||||
| 1201 | } | ||||||||
| 1202 | |||||||||
| 1203 | // Shifting const2 will never be equal to const1. | ||||||||
| 1204 | // FIXME: This should always be handled by InstSimplify? | ||||||||
| 1205 | auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE); | ||||||||
| 1206 | return replaceInstUsesWith(I, TorF); | ||||||||
| 1207 | } | ||||||||
| 1208 | |||||||||
| 1209 | /// Handle "(icmp eq/ne (shl AP2, A), AP1)" -> | ||||||||
| 1210 | /// (icmp eq/ne A, TrailingZeros(AP1) - TrailingZeros(AP2)). | ||||||||
| 1211 | Instruction *InstCombiner::foldICmpShlConstConst(ICmpInst &I, Value *A, | ||||||||
| 1212 | const APInt &AP1, | ||||||||
| 1213 | const APInt &AP2) { | ||||||||
| 1214 | 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\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 1214, __PRETTY_FUNCTION__)); | ||||||||
| 1215 | |||||||||
| 1216 | auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) { | ||||||||
| 1217 | if (I.getPredicate() == I.ICMP_NE) | ||||||||
| 1218 | Pred = CmpInst::getInversePredicate(Pred); | ||||||||
| 1219 | return new ICmpInst(Pred, LHS, RHS); | ||||||||
| 1220 | }; | ||||||||
| 1221 | |||||||||
| 1222 | // Don't bother doing any work for cases which InstSimplify handles. | ||||||||
| 1223 | if (AP2.isNullValue()) | ||||||||
| 1224 | return nullptr; | ||||||||
| 1225 | |||||||||
| 1226 | unsigned AP2TrailingZeros = AP2.countTrailingZeros(); | ||||||||
| 1227 | |||||||||
| 1228 | if (!AP1 && AP2TrailingZeros != 0) | ||||||||
| 1229 | return getICmp( | ||||||||
| 1230 | I.ICMP_UGE, A, | ||||||||
| 1231 | ConstantInt::get(A->getType(), AP2.getBitWidth() - AP2TrailingZeros)); | ||||||||
| 1232 | |||||||||
| 1233 | if (AP1 == AP2) | ||||||||
| 1234 | return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType())); | ||||||||
| 1235 | |||||||||
| 1236 | // Get the distance between the lowest bits that are set. | ||||||||
| 1237 | int Shift = AP1.countTrailingZeros() - AP2TrailingZeros; | ||||||||
| 1238 | |||||||||
| 1239 | if (Shift > 0 && AP2.shl(Shift) == AP1) | ||||||||
| 1240 | return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift)); | ||||||||
| 1241 | |||||||||
| 1242 | // Shifting const2 will never be equal to const1. | ||||||||
| 1243 | // FIXME: This should always be handled by InstSimplify? | ||||||||
| 1244 | auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE); | ||||||||
| 1245 | return replaceInstUsesWith(I, TorF); | ||||||||
| 1246 | } | ||||||||
| 1247 | |||||||||
| 1248 | /// The caller has matched a pattern of the form: | ||||||||
| 1249 | /// I = icmp ugt (add (add A, B), CI2), CI1 | ||||||||
| 1250 | /// If this is of the form: | ||||||||
| 1251 | /// sum = a + b | ||||||||
| 1252 | /// if (sum+128 >u 255) | ||||||||
| 1253 | /// Then replace it with llvm.sadd.with.overflow.i8. | ||||||||
| 1254 | /// | ||||||||
| 1255 | static Instruction *processUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B, | ||||||||
| 1256 | ConstantInt *CI2, ConstantInt *CI1, | ||||||||
| 1257 | InstCombiner &IC) { | ||||||||
| 1258 | // The transformation we're trying to do here is to transform this into an | ||||||||
| 1259 | // llvm.sadd.with.overflow. To do this, we have to replace the original add | ||||||||
| 1260 | // with a narrower add, and discard the add-with-constant that is part of the | ||||||||
| 1261 | // range check (if we can't eliminate it, this isn't profitable). | ||||||||
| 1262 | |||||||||
| 1263 | // In order to eliminate the add-with-constant, the compare can be its only | ||||||||
| 1264 | // use. | ||||||||
| 1265 | Instruction *AddWithCst = cast<Instruction>(I.getOperand(0)); | ||||||||
| 1266 | if (!AddWithCst->hasOneUse()) | ||||||||
| 1267 | return nullptr; | ||||||||
| 1268 | |||||||||
| 1269 | // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow. | ||||||||
| 1270 | if (!CI2->getValue().isPowerOf2()) | ||||||||
| 1271 | return nullptr; | ||||||||
| 1272 | unsigned NewWidth = CI2->getValue().countTrailingZeros(); | ||||||||
| 1273 | if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31) | ||||||||
| 1274 | return nullptr; | ||||||||
| 1275 | |||||||||
| 1276 | // The width of the new add formed is 1 more than the bias. | ||||||||
| 1277 | ++NewWidth; | ||||||||
| 1278 | |||||||||
| 1279 | // Check to see that CI1 is an all-ones value with NewWidth bits. | ||||||||
| 1280 | if (CI1->getBitWidth() == NewWidth || | ||||||||
| 1281 | CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth)) | ||||||||
| 1282 | return nullptr; | ||||||||
| 1283 | |||||||||
| 1284 | // This is only really a signed overflow check if the inputs have been | ||||||||
| 1285 | // sign-extended; check for that condition. For example, if CI2 is 2^31 and | ||||||||
| 1286 | // the operands of the add are 64 bits wide, we need at least 33 sign bits. | ||||||||
| 1287 | unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1; | ||||||||
| 1288 | if (IC.ComputeNumSignBits(A, 0, &I) < NeededSignBits || | ||||||||
| 1289 | IC.ComputeNumSignBits(B, 0, &I) < NeededSignBits) | ||||||||
| 1290 | return nullptr; | ||||||||
| 1291 | |||||||||
| 1292 | // In order to replace the original add with a narrower | ||||||||
| 1293 | // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant | ||||||||
| 1294 | // and truncates that discard the high bits of the add. Verify that this is | ||||||||
| 1295 | // the case. | ||||||||
| 1296 | Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0)); | ||||||||
| 1297 | for (User *U : OrigAdd->users()) { | ||||||||
| 1298 | if (U == AddWithCst) | ||||||||
| 1299 | continue; | ||||||||
| 1300 | |||||||||
| 1301 | // Only accept truncates for now. We would really like a nice recursive | ||||||||
| 1302 | // predicate like SimplifyDemandedBits, but which goes downwards the use-def | ||||||||
| 1303 | // chain to see which bits of a value are actually demanded. If the | ||||||||
| 1304 | // original add had another add which was then immediately truncated, we | ||||||||
| 1305 | // could still do the transformation. | ||||||||
| 1306 | TruncInst *TI = dyn_cast<TruncInst>(U); | ||||||||
| 1307 | if (!TI || TI->getType()->getPrimitiveSizeInBits() > NewWidth) | ||||||||
| 1308 | return nullptr; | ||||||||
| 1309 | } | ||||||||
| 1310 | |||||||||
| 1311 | // If the pattern matches, truncate the inputs to the narrower type and | ||||||||
| 1312 | // use the sadd_with_overflow intrinsic to efficiently compute both the | ||||||||
| 1313 | // result and the overflow bit. | ||||||||
| 1314 | Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth); | ||||||||
| 1315 | Function *F = Intrinsic::getDeclaration( | ||||||||
| 1316 | I.getModule(), Intrinsic::sadd_with_overflow, NewType); | ||||||||
| 1317 | |||||||||
| 1318 | InstCombiner::BuilderTy &Builder = IC.Builder; | ||||||||
| 1319 | |||||||||
| 1320 | // Put the new code above the original add, in case there are any uses of the | ||||||||
| 1321 | // add between the add and the compare. | ||||||||
| 1322 | Builder.SetInsertPoint(OrigAdd); | ||||||||
| 1323 | |||||||||
| 1324 | Value *TruncA = Builder.CreateTrunc(A, NewType, A->getName() + ".trunc"); | ||||||||
| 1325 | Value *TruncB = Builder.CreateTrunc(B, NewType, B->getName() + ".trunc"); | ||||||||
| 1326 | CallInst *Call = Builder.CreateCall(F, {TruncA, TruncB}, "sadd"); | ||||||||
| 1327 | Value *Add = Builder.CreateExtractValue(Call, 0, "sadd.result"); | ||||||||
| 1328 | Value *ZExt = Builder.CreateZExt(Add, OrigAdd->getType()); | ||||||||
| 1329 | |||||||||
| 1330 | // The inner add was the result of the narrow add, zero extended to the | ||||||||
| 1331 | // wider type. Replace it with the result computed by the intrinsic. | ||||||||
| 1332 | IC.replaceInstUsesWith(*OrigAdd, ZExt); | ||||||||
| 1333 | |||||||||
| 1334 | // The original icmp gets replaced with the overflow value. | ||||||||
| 1335 | return ExtractValueInst::Create(Call, 1, "sadd.overflow"); | ||||||||
| 1336 | } | ||||||||
| 1337 | |||||||||
| 1338 | /// If we have: | ||||||||
| 1339 | /// icmp eq/ne (urem/srem %x, %y), 0 | ||||||||
| 1340 | /// iff %y is a power-of-two, we can replace this with a bit test: | ||||||||
| 1341 | /// icmp eq/ne (and %x, (add %y, -1)), 0 | ||||||||
| 1342 | Instruction *InstCombiner::foldIRemByPowerOfTwoToBitTest(ICmpInst &I) { | ||||||||
| 1343 | // This fold is only valid for equality predicates. | ||||||||
| 1344 | if (!I.isEquality()) | ||||||||
| 1345 | return nullptr; | ||||||||
| 1346 | ICmpInst::Predicate Pred; | ||||||||
| 1347 | Value *X, *Y, *Zero; | ||||||||
| 1348 | if (!match(&I, m_ICmp(Pred, m_OneUse(m_IRem(m_Value(X), m_Value(Y))), | ||||||||
| 1349 | m_CombineAnd(m_Zero(), m_Value(Zero))))) | ||||||||
| 1350 | return nullptr; | ||||||||
| 1351 | if (!isKnownToBeAPowerOfTwo(Y, /*OrZero*/ true, 0, &I)) | ||||||||
| 1352 | return nullptr; | ||||||||
| 1353 | // This may increase instruction count, we don't enforce that Y is a constant. | ||||||||
| 1354 | Value *Mask = Builder.CreateAdd(Y, Constant::getAllOnesValue(Y->getType())); | ||||||||
| 1355 | Value *Masked = Builder.CreateAnd(X, Mask); | ||||||||
| 1356 | return ICmpInst::Create(Instruction::ICmp, Pred, Masked, Zero); | ||||||||
| 1357 | } | ||||||||
| 1358 | |||||||||
| 1359 | /// Fold equality-comparison between zero and any (maybe truncated) right-shift | ||||||||
| 1360 | /// by one-less-than-bitwidth into a sign test on the original value. | ||||||||
| 1361 | Instruction *InstCombiner::foldSignBitTest(ICmpInst &I) { | ||||||||
| 1362 | Instruction *Val; | ||||||||
| 1363 | ICmpInst::Predicate Pred; | ||||||||
| 1364 | if (!I.isEquality() || !match(&I, m_ICmp(Pred, m_Instruction(Val), m_Zero()))) | ||||||||
| 1365 | return nullptr; | ||||||||
| 1366 | |||||||||
| 1367 | Value *X; | ||||||||
| 1368 | Type *XTy; | ||||||||
| 1369 | |||||||||
| 1370 | Constant *C; | ||||||||
| 1371 | if (match(Val, m_TruncOrSelf(m_Shr(m_Value(X), m_Constant(C))))) { | ||||||||
| 1372 | XTy = X->getType(); | ||||||||
| 1373 | unsigned XBitWidth = XTy->getScalarSizeInBits(); | ||||||||
| 1374 | if (!match(C, m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_EQ, | ||||||||
| 1375 | APInt(XBitWidth, XBitWidth - 1)))) | ||||||||
| 1376 | return nullptr; | ||||||||
| 1377 | } else if (isa<BinaryOperator>(Val) && | ||||||||
| 1378 | (X = reassociateShiftAmtsOfTwoSameDirectionShifts( | ||||||||
| 1379 | cast<BinaryOperator>(Val), SQ.getWithInstruction(Val), | ||||||||
| 1380 | /*AnalyzeForSignBitExtraction=*/true))) { | ||||||||
| 1381 | XTy = X->getType(); | ||||||||
| 1382 | } else | ||||||||
| 1383 | return nullptr; | ||||||||
| 1384 | |||||||||
| 1385 | return ICmpInst::Create(Instruction::ICmp, | ||||||||
| 1386 | Pred == ICmpInst::ICMP_EQ ? ICmpInst::ICMP_SGE | ||||||||
| 1387 | : ICmpInst::ICMP_SLT, | ||||||||
| 1388 | X, ConstantInt::getNullValue(XTy)); | ||||||||
| 1389 | } | ||||||||
| 1390 | |||||||||
| 1391 | // Handle icmp pred X, 0 | ||||||||
| 1392 | Instruction *InstCombiner::foldICmpWithZero(ICmpInst &Cmp) { | ||||||||
| 1393 | CmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 1394 | if (!match(Cmp.getOperand(1), m_Zero())) | ||||||||
| 1395 | return nullptr; | ||||||||
| 1396 | |||||||||
| 1397 | // (icmp sgt smin(PosA, B) 0) -> (icmp sgt B 0) | ||||||||
| 1398 | if (Pred == ICmpInst::ICMP_SGT) { | ||||||||
| 1399 | Value *A, *B; | ||||||||
| 1400 | SelectPatternResult SPR = matchSelectPattern(Cmp.getOperand(0), A, B); | ||||||||
| 1401 | if (SPR.Flavor == SPF_SMIN) { | ||||||||
| 1402 | if (isKnownPositive(A, DL, 0, &AC, &Cmp, &DT)) | ||||||||
| 1403 | return new ICmpInst(Pred, B, Cmp.getOperand(1)); | ||||||||
| 1404 | if (isKnownPositive(B, DL, 0, &AC, &Cmp, &DT)) | ||||||||
| 1405 | return new ICmpInst(Pred, A, Cmp.getOperand(1)); | ||||||||
| 1406 | } | ||||||||
| 1407 | } | ||||||||
| 1408 | |||||||||
| 1409 | if (Instruction *New = foldIRemByPowerOfTwoToBitTest(Cmp)) | ||||||||
| 1410 | return New; | ||||||||
| 1411 | |||||||||
| 1412 | // Given: | ||||||||
| 1413 | // icmp eq/ne (urem %x, %y), 0 | ||||||||
| 1414 | // Iff %x has 0 or 1 bits set, and %y has at least 2 bits set, omit 'urem': | ||||||||
| 1415 | // icmp eq/ne %x, 0 | ||||||||
| 1416 | Value *X, *Y; | ||||||||
| 1417 | if (match(Cmp.getOperand(0), m_URem(m_Value(X), m_Value(Y))) && | ||||||||
| 1418 | ICmpInst::isEquality(Pred)) { | ||||||||
| 1419 | KnownBits XKnown = computeKnownBits(X, 0, &Cmp); | ||||||||
| 1420 | KnownBits YKnown = computeKnownBits(Y, 0, &Cmp); | ||||||||
| 1421 | if (XKnown.countMaxPopulation() == 1 && YKnown.countMinPopulation() >= 2) | ||||||||
| 1422 | return new ICmpInst(Pred, X, Cmp.getOperand(1)); | ||||||||
| 1423 | } | ||||||||
| 1424 | |||||||||
| 1425 | return nullptr; | ||||||||
| 1426 | } | ||||||||
| 1427 | |||||||||
| 1428 | /// Fold icmp Pred X, C. | ||||||||
| 1429 | /// TODO: This code structure does not make sense. The saturating add fold | ||||||||
| 1430 | /// should be moved to some other helper and extended as noted below (it is also | ||||||||
| 1431 | /// possible that code has been made unnecessary - do we canonicalize IR to | ||||||||
| 1432 | /// overflow/saturating intrinsics or not?). | ||||||||
| 1433 | Instruction *InstCombiner::foldICmpWithConstant(ICmpInst &Cmp) { | ||||||||
| 1434 | // Match the following pattern, which is a common idiom when writing | ||||||||
| 1435 | // overflow-safe integer arithmetic functions. The source performs an addition | ||||||||
| 1436 | // in wider type and explicitly checks for overflow using comparisons against | ||||||||
| 1437 | // INT_MIN and INT_MAX. Simplify by using the sadd_with_overflow intrinsic. | ||||||||
| 1438 | // | ||||||||
| 1439 | // TODO: This could probably be generalized to handle other overflow-safe | ||||||||
| 1440 | // operations if we worked out the formulas to compute the appropriate magic | ||||||||
| 1441 | // constants. | ||||||||
| 1442 | // | ||||||||
| 1443 | // sum = a + b | ||||||||
| 1444 | // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8 | ||||||||
| 1445 | CmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 1446 | Value *Op0 = Cmp.getOperand(0), *Op1 = Cmp.getOperand(1); | ||||||||
| 1447 | Value *A, *B; | ||||||||
| 1448 | ConstantInt *CI, *CI2; // I = icmp ugt (add (add A, B), CI2), CI | ||||||||
| 1449 | if (Pred == ICmpInst::ICMP_UGT && match(Op1, m_ConstantInt(CI)) && | ||||||||
| 1450 | match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2)))) | ||||||||
| 1451 | if (Instruction *Res = processUGT_ADDCST_ADD(Cmp, A, B, CI2, CI, *this)) | ||||||||
| 1452 | return Res; | ||||||||
| 1453 | |||||||||
| 1454 | return nullptr; | ||||||||
| 1455 | } | ||||||||
| 1456 | |||||||||
| 1457 | /// Canonicalize icmp instructions based on dominating conditions. | ||||||||
| 1458 | Instruction *InstCombiner::foldICmpWithDominatingICmp(ICmpInst &Cmp) { | ||||||||
| 1459 | // This is a cheap/incomplete check for dominance - just match a single | ||||||||
| 1460 | // predecessor with a conditional branch. | ||||||||
| 1461 | BasicBlock *CmpBB = Cmp.getParent(); | ||||||||
| 1462 | BasicBlock *DomBB = CmpBB->getSinglePredecessor(); | ||||||||
| 1463 | if (!DomBB) | ||||||||
| 1464 | return nullptr; | ||||||||
| 1465 | |||||||||
| 1466 | Value *DomCond; | ||||||||
| 1467 | BasicBlock *TrueBB, *FalseBB; | ||||||||
| 1468 | if (!match(DomBB->getTerminator(), m_Br(m_Value(DomCond), TrueBB, FalseBB))) | ||||||||
| 1469 | return nullptr; | ||||||||
| 1470 | |||||||||
| 1471 | assert((TrueBB == CmpBB || FalseBB == CmpBB) &&(((TrueBB == CmpBB || FalseBB == CmpBB) && "Predecessor block does not point to successor?" ) ? static_cast<void> (0) : __assert_fail ("(TrueBB == CmpBB || FalseBB == CmpBB) && \"Predecessor block does not point to successor?\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 1472, __PRETTY_FUNCTION__)) | ||||||||
| 1472 | "Predecessor block does not point to successor?")(((TrueBB == CmpBB || FalseBB == CmpBB) && "Predecessor block does not point to successor?" ) ? static_cast<void> (0) : __assert_fail ("(TrueBB == CmpBB || FalseBB == CmpBB) && \"Predecessor block does not point to successor?\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 1472, __PRETTY_FUNCTION__)); | ||||||||
| 1473 | |||||||||
| 1474 | // The branch should get simplified. Don't bother simplifying this condition. | ||||||||
| 1475 | if (TrueBB == FalseBB) | ||||||||
| 1476 | return nullptr; | ||||||||
| 1477 | |||||||||
| 1478 | // Try to simplify this compare to T/F based on the dominating condition. | ||||||||
| 1479 | Optional<bool> Imp = isImpliedCondition(DomCond, &Cmp, DL, TrueBB == CmpBB); | ||||||||
| 1480 | if (Imp) | ||||||||
| 1481 | return replaceInstUsesWith(Cmp, ConstantInt::get(Cmp.getType(), *Imp)); | ||||||||
| 1482 | |||||||||
| 1483 | CmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 1484 | Value *X = Cmp.getOperand(0), *Y = Cmp.getOperand(1); | ||||||||
| 1485 | ICmpInst::Predicate DomPred; | ||||||||
| 1486 | const APInt *C, *DomC; | ||||||||
| 1487 | if (match(DomCond, m_ICmp(DomPred, m_Specific(X), m_APInt(DomC))) && | ||||||||
| 1488 | match(Y, m_APInt(C))) { | ||||||||
| 1489 | // We have 2 compares of a variable with constants. Calculate the constant | ||||||||
| 1490 | // ranges of those compares to see if we can transform the 2nd compare: | ||||||||
| 1491 | // DomBB: | ||||||||
| 1492 | // DomCond = icmp DomPred X, DomC | ||||||||
| 1493 | // br DomCond, CmpBB, FalseBB | ||||||||
| 1494 | // CmpBB: | ||||||||
| 1495 | // Cmp = icmp Pred X, C | ||||||||
| 1496 | ConstantRange CR = ConstantRange::makeAllowedICmpRegion(Pred, *C); | ||||||||
| 1497 | ConstantRange DominatingCR = | ||||||||
| 1498 | (CmpBB == TrueBB) ? ConstantRange::makeExactICmpRegion(DomPred, *DomC) | ||||||||
| 1499 | : ConstantRange::makeExactICmpRegion( | ||||||||
| 1500 | CmpInst::getInversePredicate(DomPred), *DomC); | ||||||||
| 1501 | ConstantRange Intersection = DominatingCR.intersectWith(CR); | ||||||||
| 1502 | ConstantRange Difference = DominatingCR.difference(CR); | ||||||||
| 1503 | if (Intersection.isEmptySet()) | ||||||||
| 1504 | return replaceInstUsesWith(Cmp, Builder.getFalse()); | ||||||||
| 1505 | if (Difference.isEmptySet()) | ||||||||
| 1506 | return replaceInstUsesWith(Cmp, Builder.getTrue()); | ||||||||
| 1507 | |||||||||
| 1508 | // Canonicalizing a sign bit comparison that gets used in a branch, | ||||||||
| 1509 | // pessimizes codegen by generating branch on zero instruction instead | ||||||||
| 1510 | // of a test and branch. So we avoid canonicalizing in such situations | ||||||||
| 1511 | // because test and branch instruction has better branch displacement | ||||||||
| 1512 | // than compare and branch instruction. | ||||||||
| 1513 | bool UnusedBit; | ||||||||
| 1514 | bool IsSignBit = isSignBitCheck(Pred, *C, UnusedBit); | ||||||||
| 1515 | if (Cmp.isEquality() || (IsSignBit && hasBranchUse(Cmp))) | ||||||||
| 1516 | return nullptr; | ||||||||
| 1517 | |||||||||
| 1518 | if (const APInt *EqC = Intersection.getSingleElement()) | ||||||||
| 1519 | return new ICmpInst(ICmpInst::ICMP_EQ, X, Builder.getInt(*EqC)); | ||||||||
| 1520 | if (const APInt *NeC = Difference.getSingleElement()) | ||||||||
| 1521 | return new ICmpInst(ICmpInst::ICMP_NE, X, Builder.getInt(*NeC)); | ||||||||
| 1522 | } | ||||||||
| 1523 | |||||||||
| 1524 | return nullptr; | ||||||||
| 1525 | } | ||||||||
| 1526 | |||||||||
| 1527 | /// Fold icmp (trunc X, Y), C. | ||||||||
| 1528 | Instruction *InstCombiner::foldICmpTruncConstant(ICmpInst &Cmp, | ||||||||
| 1529 | TruncInst *Trunc, | ||||||||
| 1530 | const APInt &C) { | ||||||||
| 1531 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 1532 | Value *X = Trunc->getOperand(0); | ||||||||
| 1533 | if (C.isOneValue() && C.getBitWidth() > 1) { | ||||||||
| 1534 | // icmp slt trunc(signum(V)) 1 --> icmp slt V, 1 | ||||||||
| 1535 | Value *V = nullptr; | ||||||||
| 1536 | if (Pred == ICmpInst::ICMP_SLT && match(X, m_Signum(m_Value(V)))) | ||||||||
| 1537 | return new ICmpInst(ICmpInst::ICMP_SLT, V, | ||||||||
| 1538 | ConstantInt::get(V->getType(), 1)); | ||||||||
| 1539 | } | ||||||||
| 1540 | |||||||||
| 1541 | if (Cmp.isEquality() && Trunc->hasOneUse()) { | ||||||||
| 1542 | // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all | ||||||||
| 1543 | // of the high bits truncated out of x are known. | ||||||||
| 1544 | unsigned DstBits = Trunc->getType()->getScalarSizeInBits(), | ||||||||
| 1545 | SrcBits = X->getType()->getScalarSizeInBits(); | ||||||||
| 1546 | KnownBits Known = computeKnownBits(X, 0, &Cmp); | ||||||||
| 1547 | |||||||||
| 1548 | // If all the high bits are known, we can do this xform. | ||||||||
| 1549 | if ((Known.Zero | Known.One).countLeadingOnes() >= SrcBits - DstBits) { | ||||||||
| 1550 | // Pull in the high bits from known-ones set. | ||||||||
| 1551 | APInt NewRHS = C.zext(SrcBits); | ||||||||
| 1552 | NewRHS |= Known.One & APInt::getHighBitsSet(SrcBits, SrcBits - DstBits); | ||||||||
| 1553 | return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), NewRHS)); | ||||||||
| 1554 | } | ||||||||
| 1555 | } | ||||||||
| 1556 | |||||||||
| 1557 | return nullptr; | ||||||||
| 1558 | } | ||||||||
| 1559 | |||||||||
| 1560 | /// Fold icmp (xor X, Y), C. | ||||||||
| 1561 | Instruction *InstCombiner::foldICmpXorConstant(ICmpInst &Cmp, | ||||||||
| 1562 | BinaryOperator *Xor, | ||||||||
| 1563 | const APInt &C) { | ||||||||
| 1564 | Value *X = Xor->getOperand(0); | ||||||||
| 1565 | Value *Y = Xor->getOperand(1); | ||||||||
| 1566 | const APInt *XorC; | ||||||||
| 1567 | if (!match(Y, m_APInt(XorC))) | ||||||||
| 1568 | return nullptr; | ||||||||
| 1569 | |||||||||
| 1570 | // If this is a comparison that tests the signbit (X < 0) or (x > -1), | ||||||||
| 1571 | // fold the xor. | ||||||||
| 1572 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 1573 | bool TrueIfSigned = false; | ||||||||
| 1574 | if (isSignBitCheck(Cmp.getPredicate(), C, TrueIfSigned)) { | ||||||||
| 1575 | |||||||||
| 1576 | // If the sign bit of the XorCst is not set, there is no change to | ||||||||
| 1577 | // the operation, just stop using the Xor. | ||||||||
| 1578 | if (!XorC->isNegative()) { | ||||||||
| 1579 | Cmp.setOperand(0, X); | ||||||||
| 1580 | Worklist.Add(Xor); | ||||||||
| 1581 | return &Cmp; | ||||||||
| 1582 | } | ||||||||
| 1583 | |||||||||
| 1584 | // Emit the opposite comparison. | ||||||||
| 1585 | if (TrueIfSigned) | ||||||||
| 1586 | return new ICmpInst(ICmpInst::ICMP_SGT, X, | ||||||||
| 1587 | ConstantInt::getAllOnesValue(X->getType())); | ||||||||
| 1588 | else | ||||||||
| 1589 | return new ICmpInst(ICmpInst::ICMP_SLT, X, | ||||||||
| 1590 | ConstantInt::getNullValue(X->getType())); | ||||||||
| 1591 | } | ||||||||
| 1592 | |||||||||
| 1593 | if (Xor->hasOneUse()) { | ||||||||
| 1594 | // (icmp u/s (xor X SignMask), C) -> (icmp s/u X, (xor C SignMask)) | ||||||||
| 1595 | if (!Cmp.isEquality() && XorC->isSignMask()) { | ||||||||
| 1596 | Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate() | ||||||||
| 1597 | : Cmp.getSignedPredicate(); | ||||||||
| 1598 | return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), C ^ *XorC)); | ||||||||
| 1599 | } | ||||||||
| 1600 | |||||||||
| 1601 | // (icmp u/s (xor X ~SignMask), C) -> (icmp s/u X, (xor C ~SignMask)) | ||||||||
| 1602 | if (!Cmp.isEquality() && XorC->isMaxSignedValue()) { | ||||||||
| 1603 | Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate() | ||||||||
| 1604 | : Cmp.getSignedPredicate(); | ||||||||
| 1605 | Pred = Cmp.getSwappedPredicate(Pred); | ||||||||
| 1606 | return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), C ^ *XorC)); | ||||||||
| 1607 | } | ||||||||
| 1608 | } | ||||||||
| 1609 | |||||||||
| 1610 | // Mask constant magic can eliminate an 'xor' with unsigned compares. | ||||||||
| 1611 | if (Pred == ICmpInst::ICMP_UGT) { | ||||||||
| 1612 | // (xor X, ~C) >u C --> X <u ~C (when C+1 is a power of 2) | ||||||||
| 1613 | if (*XorC == ~C && (C + 1).isPowerOf2()) | ||||||||
| 1614 | return new ICmpInst(ICmpInst::ICMP_ULT, X, Y); | ||||||||
| 1615 | // (xor X, C) >u C --> X >u C (when C+1 is a power of 2) | ||||||||
| 1616 | if (*XorC == C && (C + 1).isPowerOf2()) | ||||||||
| 1617 | return new ICmpInst(ICmpInst::ICMP_UGT, X, Y); | ||||||||
| 1618 | } | ||||||||
| 1619 | if (Pred == ICmpInst::ICMP_ULT) { | ||||||||
| 1620 | // (xor X, -C) <u C --> X >u ~C (when C is a power of 2) | ||||||||
| 1621 | if (*XorC == -C && C.isPowerOf2()) | ||||||||
| 1622 | return new ICmpInst(ICmpInst::ICMP_UGT, X, | ||||||||
| 1623 | ConstantInt::get(X->getType(), ~C)); | ||||||||
| 1624 | // (xor X, C) <u C --> X >u ~C (when -C is a power of 2) | ||||||||
| 1625 | if (*XorC == C && (-C).isPowerOf2()) | ||||||||
| 1626 | return new ICmpInst(ICmpInst::ICMP_UGT, X, | ||||||||
| 1627 | ConstantInt::get(X->getType(), ~C)); | ||||||||
| 1628 | } | ||||||||
| 1629 | return nullptr; | ||||||||
| 1630 | } | ||||||||
| 1631 | |||||||||
| 1632 | /// Fold icmp (and (sh X, Y), C2), C1. | ||||||||
| 1633 | Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And, | ||||||||
| 1634 | const APInt &C1, const APInt &C2) { | ||||||||
| 1635 | BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0)); | ||||||||
| 1636 | if (!Shift || !Shift->isShift()) | ||||||||
| 1637 | return nullptr; | ||||||||
| 1638 | |||||||||
| 1639 | // If this is: (X >> C3) & C2 != C1 (where any shift and any compare could | ||||||||
| 1640 | // exist), turn it into (X & (C2 << C3)) != (C1 << C3). This happens a LOT in | ||||||||
| 1641 | // code produced by the clang front-end, for bitfield access. | ||||||||
| 1642 | // This seemingly simple opportunity to fold away a shift turns out to be | ||||||||
| 1643 | // rather complicated. See PR17827 for details. | ||||||||
| 1644 | unsigned ShiftOpcode = Shift->getOpcode(); | ||||||||
| 1645 | bool IsShl = ShiftOpcode == Instruction::Shl; | ||||||||
| 1646 | const APInt *C3; | ||||||||
| 1647 | if (match(Shift->getOperand(1), m_APInt(C3))) { | ||||||||
| 1648 | bool CanFold = false; | ||||||||
| 1649 | if (ShiftOpcode == Instruction::Shl) { | ||||||||
| 1650 | // For a left shift, we can fold if the comparison is not signed. We can | ||||||||
| 1651 | // also fold a signed comparison if the mask value and comparison value | ||||||||
| 1652 | // are not negative. These constraints may not be obvious, but we can | ||||||||
| 1653 | // prove that they are correct using an SMT solver. | ||||||||
| 1654 | if (!Cmp.isSigned() || (!C2.isNegative() && !C1.isNegative())) | ||||||||
| 1655 | CanFold = true; | ||||||||
| 1656 | } else { | ||||||||
| 1657 | bool IsAshr = ShiftOpcode == Instruction::AShr; | ||||||||
| 1658 | // For a logical right shift, we can fold if the comparison is not signed. | ||||||||
| 1659 | // We can also fold a signed comparison if the shifted mask value and the | ||||||||
| 1660 | // shifted comparison value are not negative. These constraints may not be | ||||||||
| 1661 | // obvious, but we can prove that they are correct using an SMT solver. | ||||||||
| 1662 | // For an arithmetic shift right we can do the same, if we ensure | ||||||||
| 1663 | // the And doesn't use any bits being shifted in. Normally these would | ||||||||
| 1664 | // be turned into lshr by SimplifyDemandedBits, but not if there is an | ||||||||
| 1665 | // additional user. | ||||||||
| 1666 | if (!IsAshr || (C2.shl(*C3).lshr(*C3) == C2)) { | ||||||||
| 1667 | if (!Cmp.isSigned() || | ||||||||
| 1668 | (!C2.shl(*C3).isNegative() && !C1.shl(*C3).isNegative())) | ||||||||
| 1669 | CanFold = true; | ||||||||
| 1670 | } | ||||||||
| 1671 | } | ||||||||
| 1672 | |||||||||
| 1673 | if (CanFold) { | ||||||||
| 1674 | APInt NewCst = IsShl ? C1.lshr(*C3) : C1.shl(*C3); | ||||||||
| 1675 | APInt SameAsC1 = IsShl ? NewCst.shl(*C3) : NewCst.lshr(*C3); | ||||||||
| 1676 | // Check to see if we are shifting out any of the bits being compared. | ||||||||
| 1677 | if (SameAsC1 != C1) { | ||||||||
| 1678 | // If we shifted bits out, the fold is not going to work out. As a | ||||||||
| 1679 | // special case, check to see if this means that the result is always | ||||||||
| 1680 | // true or false now. | ||||||||
| 1681 | if (Cmp.getPredicate() == ICmpInst::ICMP_EQ) | ||||||||
| 1682 | return replaceInstUsesWith(Cmp, ConstantInt::getFalse(Cmp.getType())); | ||||||||
| 1683 | if (Cmp.getPredicate() == ICmpInst::ICMP_NE) | ||||||||
| 1684 | return replaceInstUsesWith(Cmp, ConstantInt::getTrue(Cmp.getType())); | ||||||||
| 1685 | } else { | ||||||||
| 1686 | Cmp.setOperand(1, ConstantInt::get(And->getType(), NewCst)); | ||||||||
| 1687 | APInt NewAndCst = IsShl ? C2.lshr(*C3) : C2.shl(*C3); | ||||||||
| 1688 | And->setOperand(1, ConstantInt::get(And->getType(), NewAndCst)); | ||||||||
| 1689 | And->setOperand(0, Shift->getOperand(0)); | ||||||||
| 1690 | Worklist.Add(Shift); // Shift is dead. | ||||||||
| 1691 | return &Cmp; | ||||||||
| 1692 | } | ||||||||
| 1693 | } | ||||||||
| 1694 | } | ||||||||
| 1695 | |||||||||
| 1696 | // Turn ((X >> Y) & C2) == 0 into (X & (C2 << Y)) == 0. The latter is | ||||||||
| 1697 | // preferable because it allows the C2 << Y expression to be hoisted out of a | ||||||||
| 1698 | // loop if Y is invariant and X is not. | ||||||||
| 1699 | if (Shift->hasOneUse() && C1.isNullValue() && Cmp.isEquality() && | ||||||||
| 1700 | !Shift->isArithmeticShift() && !isa<Constant>(Shift->getOperand(0))) { | ||||||||
| 1701 | // Compute C2 << Y. | ||||||||
| 1702 | Value *NewShift = | ||||||||
| 1703 | IsShl ? Builder.CreateLShr(And->getOperand(1), Shift->getOperand(1)) | ||||||||
| 1704 | : Builder.CreateShl(And->getOperand(1), Shift->getOperand(1)); | ||||||||
| 1705 | |||||||||
| 1706 | // Compute X & (C2 << Y). | ||||||||
| 1707 | Value *NewAnd = Builder.CreateAnd(Shift->getOperand(0), NewShift); | ||||||||
| 1708 | Cmp.setOperand(0, NewAnd); | ||||||||
| 1709 | return &Cmp; | ||||||||
| 1710 | } | ||||||||
| 1711 | |||||||||
| 1712 | return nullptr; | ||||||||
| 1713 | } | ||||||||
| 1714 | |||||||||
| 1715 | /// Fold icmp (and X, C2), C1. | ||||||||
| 1716 | Instruction *InstCombiner::foldICmpAndConstConst(ICmpInst &Cmp, | ||||||||
| 1717 | BinaryOperator *And, | ||||||||
| 1718 | const APInt &C1) { | ||||||||
| 1719 | bool isICMP_NE = Cmp.getPredicate() == ICmpInst::ICMP_NE; | ||||||||
| 1720 | |||||||||
| 1721 | // For vectors: icmp ne (and X, 1), 0 --> trunc X to N x i1 | ||||||||
| 1722 | // TODO: We canonicalize to the longer form for scalars because we have | ||||||||
| 1723 | // better analysis/folds for icmp, and codegen may be better with icmp. | ||||||||
| 1724 | if (isICMP_NE && Cmp.getType()->isVectorTy() && C1.isNullValue() && | ||||||||
| 1725 | match(And->getOperand(1), m_One())) | ||||||||
| 1726 | return new TruncInst(And->getOperand(0), Cmp.getType()); | ||||||||
| 1727 | |||||||||
| 1728 | const APInt *C2; | ||||||||
| 1729 | Value *X; | ||||||||
| 1730 | if (!match(And, m_And(m_Value(X), m_APInt(C2)))) | ||||||||
| 1731 | return nullptr; | ||||||||
| 1732 | |||||||||
| 1733 | // Don't perform the following transforms if the AND has multiple uses | ||||||||
| 1734 | if (!And->hasOneUse()) | ||||||||
| 1735 | return nullptr; | ||||||||
| 1736 | |||||||||
| 1737 | if (Cmp.isEquality() && C1.isNullValue()) { | ||||||||
| 1738 | // Restrict this fold to single-use 'and' (PR10267). | ||||||||
| 1739 | // Replace (and X, (1 << size(X)-1) != 0) with X s< 0 | ||||||||
| 1740 | if (C2->isSignMask()) { | ||||||||
| 1741 | Constant *Zero = Constant::getNullValue(X->getType()); | ||||||||
| 1742 | auto NewPred = isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE; | ||||||||
| 1743 | return new ICmpInst(NewPred, X, Zero); | ||||||||
| 1744 | } | ||||||||
| 1745 | |||||||||
| 1746 | // Restrict this fold only for single-use 'and' (PR10267). | ||||||||
| 1747 | // ((%x & C) == 0) --> %x u< (-C) iff (-C) is power of two. | ||||||||
| 1748 | if ((~(*C2) + 1).isPowerOf2()) { | ||||||||
| 1749 | Constant *NegBOC = | ||||||||
| 1750 | ConstantExpr::getNeg(cast<Constant>(And->getOperand(1))); | ||||||||
| 1751 | auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT; | ||||||||
| 1752 | return new ICmpInst(NewPred, X, NegBOC); | ||||||||
| 1753 | } | ||||||||
| 1754 | } | ||||||||
| 1755 | |||||||||
| 1756 | // If the LHS is an 'and' of a truncate and we can widen the and/compare to | ||||||||
| 1757 | // the input width without changing the value produced, eliminate the cast: | ||||||||
| 1758 | // | ||||||||
| 1759 | // icmp (and (trunc W), C2), C1 -> icmp (and W, C2'), C1' | ||||||||
| 1760 | // | ||||||||
| 1761 | // We can do this transformation if the constants do not have their sign bits | ||||||||
| 1762 | // set or if it is an equality comparison. Extending a relational comparison | ||||||||
| 1763 | // when we're checking the sign bit would not work. | ||||||||
| 1764 | Value *W; | ||||||||
| 1765 | if (match(And->getOperand(0), m_OneUse(m_Trunc(m_Value(W)))) && | ||||||||
| 1766 | (Cmp.isEquality() || (!C1.isNegative() && !C2->isNegative()))) { | ||||||||
| 1767 | // TODO: Is this a good transform for vectors? Wider types may reduce | ||||||||
| 1768 | // throughput. Should this transform be limited (even for scalars) by using | ||||||||
| 1769 | // shouldChangeType()? | ||||||||
| 1770 | if (!Cmp.getType()->isVectorTy()) { | ||||||||
| 1771 | Type *WideType = W->getType(); | ||||||||
| 1772 | unsigned WideScalarBits = WideType->getScalarSizeInBits(); | ||||||||
| 1773 | Constant *ZextC1 = ConstantInt::get(WideType, C1.zext(WideScalarBits)); | ||||||||
| 1774 | Constant *ZextC2 = ConstantInt::get(WideType, C2->zext(WideScalarBits)); | ||||||||
| 1775 | Value *NewAnd = Builder.CreateAnd(W, ZextC2, And->getName()); | ||||||||
| 1776 | return new ICmpInst(Cmp.getPredicate(), NewAnd, ZextC1); | ||||||||
| 1777 | } | ||||||||
| 1778 | } | ||||||||
| 1779 | |||||||||
| 1780 | if (Instruction *I = foldICmpAndShift(Cmp, And, C1, *C2)) | ||||||||
| 1781 | return I; | ||||||||
| 1782 | |||||||||
| 1783 | // (icmp pred (and (or (lshr A, B), A), 1), 0) --> | ||||||||
| 1784 | // (icmp pred (and A, (or (shl 1, B), 1), 0)) | ||||||||
| 1785 | // | ||||||||
| 1786 | // iff pred isn't signed | ||||||||
| 1787 | if (!Cmp.isSigned() && C1.isNullValue() && And->getOperand(0)->hasOneUse() && | ||||||||
| 1788 | match(And->getOperand(1), m_One())) { | ||||||||
| 1789 | Constant *One = cast<Constant>(And->getOperand(1)); | ||||||||
| 1790 | Value *Or = And->getOperand(0); | ||||||||
| 1791 | Value *A, *B, *LShr; | ||||||||
| 1792 | if (match(Or, m_Or(m_Value(LShr), m_Value(A))) && | ||||||||
| 1793 | match(LShr, m_LShr(m_Specific(A), m_Value(B)))) { | ||||||||
| 1794 | unsigned UsesRemoved = 0; | ||||||||
| 1795 | if (And->hasOneUse()) | ||||||||
| 1796 | ++UsesRemoved; | ||||||||
| 1797 | if (Or->hasOneUse()) | ||||||||
| 1798 | ++UsesRemoved; | ||||||||
| 1799 | if (LShr->hasOneUse()) | ||||||||
| 1800 | ++UsesRemoved; | ||||||||
| 1801 | |||||||||
| 1802 | // Compute A & ((1 << B) | 1) | ||||||||
| 1803 | Value *NewOr = nullptr; | ||||||||
| 1804 | if (auto *C = dyn_cast<Constant>(B)) { | ||||||||
| 1805 | if (UsesRemoved >= 1) | ||||||||
| 1806 | NewOr = ConstantExpr::getOr(ConstantExpr::getNUWShl(One, C), One); | ||||||||
| 1807 | } else { | ||||||||
| 1808 | if (UsesRemoved >= 3) | ||||||||
| 1809 | NewOr = Builder.CreateOr(Builder.CreateShl(One, B, LShr->getName(), | ||||||||
| 1810 | /*HasNUW=*/true), | ||||||||
| 1811 | One, Or->getName()); | ||||||||
| 1812 | } | ||||||||
| 1813 | if (NewOr) { | ||||||||
| 1814 | Value *NewAnd = Builder.CreateAnd(A, NewOr, And->getName()); | ||||||||
| 1815 | Cmp.setOperand(0, NewAnd); | ||||||||
| 1816 | return &Cmp; | ||||||||
| 1817 | } | ||||||||
| 1818 | } | ||||||||
| 1819 | } | ||||||||
| 1820 | |||||||||
| 1821 | return nullptr; | ||||||||
| 1822 | } | ||||||||
| 1823 | |||||||||
| 1824 | /// Fold icmp (and X, Y), C. | ||||||||
| 1825 | Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &Cmp, | ||||||||
| 1826 | BinaryOperator *And, | ||||||||
| 1827 | const APInt &C) { | ||||||||
| 1828 | if (Instruction *I = foldICmpAndConstConst(Cmp, And, C)) | ||||||||
| 1829 | return I; | ||||||||
| 1830 | |||||||||
| 1831 | // TODO: These all require that Y is constant too, so refactor with the above. | ||||||||
| 1832 | |||||||||
| 1833 | // Try to optimize things like "A[i] & 42 == 0" to index computations. | ||||||||
| 1834 | Value *X = And->getOperand(0); | ||||||||
| 1835 | Value *Y = And->getOperand(1); | ||||||||
| 1836 | if (auto *LI = dyn_cast<LoadInst>(X)) | ||||||||
| 1837 | if (auto *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0))) | ||||||||
| 1838 | if (auto *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) | ||||||||
| 1839 | if (GV->isConstant() && GV->hasDefinitiveInitializer() && | ||||||||
| 1840 | !LI->isVolatile() && isa<ConstantInt>(Y)) { | ||||||||
| 1841 | ConstantInt *C2 = cast<ConstantInt>(Y); | ||||||||
| 1842 | if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, Cmp, C2)) | ||||||||
| 1843 | return Res; | ||||||||
| 1844 | } | ||||||||
| 1845 | |||||||||
| 1846 | if (!Cmp.isEquality()) | ||||||||
| 1847 | return nullptr; | ||||||||
| 1848 | |||||||||
| 1849 | // X & -C == -C -> X > u ~C | ||||||||
| 1850 | // X & -C != -C -> X <= u ~C | ||||||||
| 1851 | // iff C is a power of 2 | ||||||||
| 1852 | if (Cmp.getOperand(1) == Y && (-C).isPowerOf2()) { | ||||||||
| 1853 | auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGT | ||||||||
| 1854 | : CmpInst::ICMP_ULE; | ||||||||
| 1855 | return new ICmpInst(NewPred, X, SubOne(cast<Constant>(Cmp.getOperand(1)))); | ||||||||
| 1856 | } | ||||||||
| 1857 | |||||||||
| 1858 | // (X & C2) == 0 -> (trunc X) >= 0 | ||||||||
| 1859 | // (X & C2) != 0 -> (trunc X) < 0 | ||||||||
| 1860 | // iff C2 is a power of 2 and it masks the sign bit of a legal integer type. | ||||||||
| 1861 | const APInt *C2; | ||||||||
| 1862 | if (And->hasOneUse() && C.isNullValue() && match(Y, m_APInt(C2))) { | ||||||||
| 1863 | int32_t ExactLogBase2 = C2->exactLogBase2(); | ||||||||
| 1864 | if (ExactLogBase2 != -1 && DL.isLegalInteger(ExactLogBase2 + 1)) { | ||||||||
| 1865 | Type *NTy = IntegerType::get(Cmp.getContext(), ExactLogBase2 + 1); | ||||||||
| 1866 | if (And->getType()->isVectorTy()) | ||||||||
| 1867 | NTy = VectorType::get(NTy, And->getType()->getVectorNumElements()); | ||||||||
| 1868 | Value *Trunc = Builder.CreateTrunc(X, NTy); | ||||||||
| 1869 | auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_SGE | ||||||||
| 1870 | : CmpInst::ICMP_SLT; | ||||||||
| 1871 | return new ICmpInst(NewPred, Trunc, Constant::getNullValue(NTy)); | ||||||||
| 1872 | } | ||||||||
| 1873 | } | ||||||||
| 1874 | |||||||||
| 1875 | return nullptr; | ||||||||
| 1876 | } | ||||||||
| 1877 | |||||||||
| 1878 | /// Fold icmp (or X, Y), C. | ||||||||
| 1879 | Instruction *InstCombiner::foldICmpOrConstant(ICmpInst &Cmp, BinaryOperator *Or, | ||||||||
| 1880 | const APInt &C) { | ||||||||
| 1881 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 1882 | if (C.isOneValue()) { | ||||||||
| 1883 | // icmp slt signum(V) 1 --> icmp slt V, 1 | ||||||||
| 1884 | Value *V = nullptr; | ||||||||
| 1885 | if (Pred == ICmpInst::ICMP_SLT && match(Or, m_Signum(m_Value(V)))) | ||||||||
| 1886 | return new ICmpInst(ICmpInst::ICMP_SLT, V, | ||||||||
| 1887 | ConstantInt::get(V->getType(), 1)); | ||||||||
| 1888 | } | ||||||||
| 1889 | |||||||||
| 1890 | Value *OrOp0 = Or->getOperand(0), *OrOp1 = Or->getOperand(1); | ||||||||
| 1891 | if (Cmp.isEquality() && Cmp.getOperand(1) == OrOp1) { | ||||||||
| 1892 | // X | C == C --> X <=u C | ||||||||
| 1893 | // X | C != C --> X >u C | ||||||||
| 1894 | // iff C+1 is a power of 2 (C is a bitmask of the low bits) | ||||||||
| 1895 | if ((C + 1).isPowerOf2()) { | ||||||||
| 1896 | Pred = (Pred == CmpInst::ICMP_EQ) ? CmpInst::ICMP_ULE : CmpInst::ICMP_UGT; | ||||||||
| 1897 | return new ICmpInst(Pred, OrOp0, OrOp1); | ||||||||
| 1898 | } | ||||||||
| 1899 | // More general: are all bits outside of a mask constant set or not set? | ||||||||
| 1900 | // X | C == C --> (X & ~C) == 0 | ||||||||
| 1901 | // X | C != C --> (X & ~C) != 0 | ||||||||
| 1902 | if (Or->hasOneUse()) { | ||||||||
| 1903 | Value *A = Builder.CreateAnd(OrOp0, ~C); | ||||||||
| 1904 | return new ICmpInst(Pred, A, ConstantInt::getNullValue(OrOp0->getType())); | ||||||||
| 1905 | } | ||||||||
| 1906 | } | ||||||||
| 1907 | |||||||||
| 1908 | if (!Cmp.isEquality() || !C.isNullValue() || !Or->hasOneUse()) | ||||||||
| 1909 | return nullptr; | ||||||||
| 1910 | |||||||||
| 1911 | Value *P, *Q; | ||||||||
| 1912 | if (match(Or, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) { | ||||||||
| 1913 | // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0 | ||||||||
| 1914 | // -> and (icmp eq P, null), (icmp eq Q, null). | ||||||||
| 1915 | Value *CmpP = | ||||||||
| 1916 | Builder.CreateICmp(Pred, P, ConstantInt::getNullValue(P->getType())); | ||||||||
| 1917 | Value *CmpQ = | ||||||||
| 1918 | Builder.CreateICmp(Pred, Q, ConstantInt::getNullValue(Q->getType())); | ||||||||
| 1919 | auto BOpc = Pred == CmpInst::ICMP_EQ ? Instruction::And : Instruction::Or; | ||||||||
| 1920 | return BinaryOperator::Create(BOpc, CmpP, CmpQ); | ||||||||
| 1921 | } | ||||||||
| 1922 | |||||||||
| 1923 | // Are we using xors to bitwise check for a pair of (in)equalities? Convert to | ||||||||
| 1924 | // a shorter form that has more potential to be folded even further. | ||||||||
| 1925 | Value *X1, *X2, *X3, *X4; | ||||||||
| 1926 | if (match(OrOp0, m_OneUse(m_Xor(m_Value(X1), m_Value(X2)))) && | ||||||||
| 1927 | match(OrOp1, m_OneUse(m_Xor(m_Value(X3), m_Value(X4))))) { | ||||||||
| 1928 | // ((X1 ^ X2) || (X3 ^ X4)) == 0 --> (X1 == X2) && (X3 == X4) | ||||||||
| 1929 | // ((X1 ^ X2) || (X3 ^ X4)) != 0 --> (X1 != X2) || (X3 != X4) | ||||||||
| 1930 | Value *Cmp12 = Builder.CreateICmp(Pred, X1, X2); | ||||||||
| 1931 | Value *Cmp34 = Builder.CreateICmp(Pred, X3, X4); | ||||||||
| 1932 | auto BOpc = Pred == CmpInst::ICMP_EQ ? Instruction::And : Instruction::Or; | ||||||||
| 1933 | return BinaryOperator::Create(BOpc, Cmp12, Cmp34); | ||||||||
| 1934 | } | ||||||||
| 1935 | |||||||||
| 1936 | return nullptr; | ||||||||
| 1937 | } | ||||||||
| 1938 | |||||||||
| 1939 | /// Fold icmp (mul X, Y), C. | ||||||||
| 1940 | Instruction *InstCombiner::foldICmpMulConstant(ICmpInst &Cmp, | ||||||||
| 1941 | BinaryOperator *Mul, | ||||||||
| 1942 | const APInt &C) { | ||||||||
| 1943 | const APInt *MulC; | ||||||||
| 1944 | if (!match(Mul->getOperand(1), m_APInt(MulC))) | ||||||||
| 1945 | return nullptr; | ||||||||
| 1946 | |||||||||
| 1947 | // If this is a test of the sign bit and the multiply is sign-preserving with | ||||||||
| 1948 | // a constant operand, use the multiply LHS operand instead. | ||||||||
| 1949 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 1950 | if (isSignTest(Pred, C) && Mul->hasNoSignedWrap()) { | ||||||||
| 1951 | if (MulC->isNegative()) | ||||||||
| 1952 | Pred = ICmpInst::getSwappedPredicate(Pred); | ||||||||
| 1953 | return new ICmpInst(Pred, Mul->getOperand(0), | ||||||||
| 1954 | Constant::getNullValue(Mul->getType())); | ||||||||
| 1955 | } | ||||||||
| 1956 | |||||||||
| 1957 | return nullptr; | ||||||||
| 1958 | } | ||||||||
| 1959 | |||||||||
| 1960 | /// Fold icmp (shl 1, Y), C. | ||||||||
| 1961 | static Instruction *foldICmpShlOne(ICmpInst &Cmp, Instruction *Shl, | ||||||||
| 1962 | const APInt &C) { | ||||||||
| 1963 | Value *Y; | ||||||||
| 1964 | if (!match(Shl, m_Shl(m_One(), m_Value(Y)))) | ||||||||
| 1965 | return nullptr; | ||||||||
| 1966 | |||||||||
| 1967 | Type *ShiftType = Shl->getType(); | ||||||||
| 1968 | unsigned TypeBits = C.getBitWidth(); | ||||||||
| 1969 | bool CIsPowerOf2 = C.isPowerOf2(); | ||||||||
| 1970 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 1971 | if (Cmp.isUnsigned()) { | ||||||||
| 1972 | // (1 << Y) pred C -> Y pred Log2(C) | ||||||||
| 1973 | if (!CIsPowerOf2) { | ||||||||
| 1974 | // (1 << Y) < 30 -> Y <= 4 | ||||||||
| 1975 | // (1 << Y) <= 30 -> Y <= 4 | ||||||||
| 1976 | // (1 << Y) >= 30 -> Y > 4 | ||||||||
| 1977 | // (1 << Y) > 30 -> Y > 4 | ||||||||
| 1978 | if (Pred == ICmpInst::ICMP_ULT) | ||||||||
| 1979 | Pred = ICmpInst::ICMP_ULE; | ||||||||
| 1980 | else if (Pred == ICmpInst::ICMP_UGE) | ||||||||
| 1981 | Pred = ICmpInst::ICMP_UGT; | ||||||||
| 1982 | } | ||||||||
| 1983 | |||||||||
| 1984 | // (1 << Y) >= 2147483648 -> Y >= 31 -> Y == 31 | ||||||||
| 1985 | // (1 << Y) < 2147483648 -> Y < 31 -> Y != 31 | ||||||||
| 1986 | unsigned CLog2 = C.logBase2(); | ||||||||
| 1987 | if (CLog2 == TypeBits - 1) { | ||||||||
| 1988 | if (Pred == ICmpInst::ICMP_UGE) | ||||||||
| 1989 | Pred = ICmpInst::ICMP_EQ; | ||||||||
| 1990 | else if (Pred == ICmpInst::ICMP_ULT) | ||||||||
| 1991 | Pred = ICmpInst::ICMP_NE; | ||||||||
| 1992 | } | ||||||||
| 1993 | return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, CLog2)); | ||||||||
| 1994 | } else if (Cmp.isSigned()) { | ||||||||
| 1995 | Constant *BitWidthMinusOne = ConstantInt::get(ShiftType, TypeBits - 1); | ||||||||
| 1996 | if (C.isAllOnesValue()) { | ||||||||
| 1997 | // (1 << Y) <= -1 -> Y == 31 | ||||||||
| 1998 | if (Pred == ICmpInst::ICMP_SLE) | ||||||||
| 1999 | return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne); | ||||||||
| 2000 | |||||||||
| 2001 | // (1 << Y) > -1 -> Y != 31 | ||||||||
| 2002 | if (Pred == ICmpInst::ICMP_SGT) | ||||||||
| 2003 | return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne); | ||||||||
| 2004 | } else if (!C) { | ||||||||
| 2005 | // (1 << Y) < 0 -> Y == 31 | ||||||||
| 2006 | // (1 << Y) <= 0 -> Y == 31 | ||||||||
| 2007 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) | ||||||||
| 2008 | return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne); | ||||||||
| 2009 | |||||||||
| 2010 | // (1 << Y) >= 0 -> Y != 31 | ||||||||
| 2011 | // (1 << Y) > 0 -> Y != 31 | ||||||||
| 2012 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) | ||||||||
| 2013 | return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne); | ||||||||
| 2014 | } | ||||||||
| 2015 | } else if (Cmp.isEquality() && CIsPowerOf2) { | ||||||||
| 2016 | return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, C.logBase2())); | ||||||||
| 2017 | } | ||||||||
| 2018 | |||||||||
| 2019 | return nullptr; | ||||||||
| 2020 | } | ||||||||
| 2021 | |||||||||
| 2022 | /// Fold icmp (shl X, Y), C. | ||||||||
| 2023 | Instruction *InstCombiner::foldICmpShlConstant(ICmpInst &Cmp, | ||||||||
| 2024 | BinaryOperator *Shl, | ||||||||
| 2025 | const APInt &C) { | ||||||||
| 2026 | const APInt *ShiftVal; | ||||||||
| 2027 | if (Cmp.isEquality() && match(Shl->getOperand(0), m_APInt(ShiftVal))) | ||||||||
| 2028 | return foldICmpShlConstConst(Cmp, Shl->getOperand(1), C, *ShiftVal); | ||||||||
| 2029 | |||||||||
| 2030 | const APInt *ShiftAmt; | ||||||||
| 2031 | if (!match(Shl->getOperand(1), m_APInt(ShiftAmt))) | ||||||||
| 2032 | return foldICmpShlOne(Cmp, Shl, C); | ||||||||
| 2033 | |||||||||
| 2034 | // Check that the shift amount is in range. If not, don't perform undefined | ||||||||
| 2035 | // shifts. When the shift is visited, it will be simplified. | ||||||||
| 2036 | unsigned TypeBits = C.getBitWidth(); | ||||||||
| 2037 | if (ShiftAmt->uge(TypeBits)) | ||||||||
| 2038 | return nullptr; | ||||||||
| 2039 | |||||||||
| 2040 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 2041 | Value *X = Shl->getOperand(0); | ||||||||
| 2042 | Type *ShType = Shl->getType(); | ||||||||
| 2043 | |||||||||
| 2044 | // NSW guarantees that we are only shifting out sign bits from the high bits, | ||||||||
| 2045 | // so we can ASHR the compare constant without needing a mask and eliminate | ||||||||
| 2046 | // the shift. | ||||||||
| 2047 | if (Shl->hasNoSignedWrap()) { | ||||||||
| 2048 | if (Pred == ICmpInst::ICMP_SGT) { | ||||||||
| 2049 | // icmp Pred (shl nsw X, ShiftAmt), C --> icmp Pred X, (C >>s ShiftAmt) | ||||||||
| 2050 | APInt ShiftedC = C.ashr(*ShiftAmt); | ||||||||
| 2051 | return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC)); | ||||||||
| 2052 | } | ||||||||
| 2053 | if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) && | ||||||||
| 2054 | C.ashr(*ShiftAmt).shl(*ShiftAmt) == C) { | ||||||||
| 2055 | APInt ShiftedC = C.ashr(*ShiftAmt); | ||||||||
| 2056 | return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC)); | ||||||||
| 2057 | } | ||||||||
| 2058 | if (Pred == ICmpInst::ICMP_SLT) { | ||||||||
| 2059 | // SLE is the same as above, but SLE is canonicalized to SLT, so convert: | ||||||||
| 2060 | // (X << S) <=s C is equiv to X <=s (C >> S) for all C | ||||||||
| 2061 | // (X << S) <s (C + 1) is equiv to X <s (C >> S) + 1 if C <s SMAX | ||||||||
| 2062 | // (X << S) <s C is equiv to X <s ((C - 1) >> S) + 1 if C >s SMIN | ||||||||
| 2063 | assert(!C.isMinSignedValue() && "Unexpected icmp slt")((!C.isMinSignedValue() && "Unexpected icmp slt") ? static_cast <void> (0) : __assert_fail ("!C.isMinSignedValue() && \"Unexpected icmp slt\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2063, __PRETTY_FUNCTION__)); | ||||||||
| 2064 | APInt ShiftedC = (C - 1).ashr(*ShiftAmt) + 1; | ||||||||
| 2065 | return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC)); | ||||||||
| 2066 | } | ||||||||
| 2067 | // If this is a signed comparison to 0 and the shift is sign preserving, | ||||||||
| 2068 | // use the shift LHS operand instead; isSignTest may change 'Pred', so only | ||||||||
| 2069 | // do that if we're sure to not continue on in this function. | ||||||||
| 2070 | if (isSignTest(Pred, C)) | ||||||||
| 2071 | return new ICmpInst(Pred, X, Constant::getNullValue(ShType)); | ||||||||
| 2072 | } | ||||||||
| 2073 | |||||||||
| 2074 | // NUW guarantees that we are only shifting out zero bits from the high bits, | ||||||||
| 2075 | // so we can LSHR the compare constant without needing a mask and eliminate | ||||||||
| 2076 | // the shift. | ||||||||
| 2077 | if (Shl->hasNoUnsignedWrap()) { | ||||||||
| 2078 | if (Pred == ICmpInst::ICMP_UGT) { | ||||||||
| 2079 | // icmp Pred (shl nuw X, ShiftAmt), C --> icmp Pred X, (C >>u ShiftAmt) | ||||||||
| 2080 | APInt ShiftedC = C.lshr(*ShiftAmt); | ||||||||
| 2081 | return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC)); | ||||||||
| 2082 | } | ||||||||
| 2083 | if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) && | ||||||||
| 2084 | C.lshr(*ShiftAmt).shl(*ShiftAmt) == C) { | ||||||||
| 2085 | APInt ShiftedC = C.lshr(*ShiftAmt); | ||||||||
| 2086 | return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC)); | ||||||||
| 2087 | } | ||||||||
| 2088 | if (Pred == ICmpInst::ICMP_ULT) { | ||||||||
| 2089 | // ULE is the same as above, but ULE is canonicalized to ULT, so convert: | ||||||||
| 2090 | // (X << S) <=u C is equiv to X <=u (C >> S) for all C | ||||||||
| 2091 | // (X << S) <u (C + 1) is equiv to X <u (C >> S) + 1 if C <u ~0u | ||||||||
| 2092 | // (X << S) <u C is equiv to X <u ((C - 1) >> S) + 1 if C >u 0 | ||||||||
| 2093 | 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\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2093, __PRETTY_FUNCTION__)); | ||||||||
| 2094 | APInt ShiftedC = (C - 1).lshr(*ShiftAmt) + 1; | ||||||||
| 2095 | return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC)); | ||||||||
| 2096 | } | ||||||||
| 2097 | } | ||||||||
| 2098 | |||||||||
| 2099 | if (Cmp.isEquality() && Shl->hasOneUse()) { | ||||||||
| 2100 | // Strength-reduce the shift into an 'and'. | ||||||||
| 2101 | Constant *Mask = ConstantInt::get( | ||||||||
| 2102 | ShType, | ||||||||
| 2103 | APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt->getZExtValue())); | ||||||||
| 2104 | Value *And = Builder.CreateAnd(X, Mask, Shl->getName() + ".mask"); | ||||||||
| 2105 | Constant *LShrC = ConstantInt::get(ShType, C.lshr(*ShiftAmt)); | ||||||||
| 2106 | return new ICmpInst(Pred, And, LShrC); | ||||||||
| 2107 | } | ||||||||
| 2108 | |||||||||
| 2109 | // Otherwise, if this is a comparison of the sign bit, simplify to and/test. | ||||||||
| 2110 | bool TrueIfSigned = false; | ||||||||
| 2111 | if (Shl->hasOneUse() && isSignBitCheck(Pred, C, TrueIfSigned)) { | ||||||||
| 2112 | // (X << 31) <s 0 --> (X & 1) != 0 | ||||||||
| 2113 | Constant *Mask = ConstantInt::get( | ||||||||
| 2114 | ShType, | ||||||||
| 2115 | APInt::getOneBitSet(TypeBits, TypeBits - ShiftAmt->getZExtValue() - 1)); | ||||||||
| 2116 | Value *And = Builder.CreateAnd(X, Mask, Shl->getName() + ".mask"); | ||||||||
| 2117 | return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ, | ||||||||
| 2118 | And, Constant::getNullValue(ShType)); | ||||||||
| 2119 | } | ||||||||
| 2120 | |||||||||
| 2121 | // Simplify 'shl' inequality test into 'and' equality test. | ||||||||
| 2122 | if (Cmp.isUnsigned() && Shl->hasOneUse()) { | ||||||||
| 2123 | // (X l<< C2) u<=/u> C1 iff C1+1 is power of two -> X & (~C1 l>> C2) ==/!= 0 | ||||||||
| 2124 | if ((C + 1).isPowerOf2() && | ||||||||
| 2125 | (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_UGT)) { | ||||||||
| 2126 | Value *And = Builder.CreateAnd(X, (~C).lshr(ShiftAmt->getZExtValue())); | ||||||||
| 2127 | return new ICmpInst(Pred == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_EQ | ||||||||
| 2128 | : ICmpInst::ICMP_NE, | ||||||||
| 2129 | And, Constant::getNullValue(ShType)); | ||||||||
| 2130 | } | ||||||||
| 2131 | // (X l<< C2) u</u>= C1 iff C1 is power of two -> X & (-C1 l>> C2) ==/!= 0 | ||||||||
| 2132 | if (C.isPowerOf2() && | ||||||||
| 2133 | (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_UGE)) { | ||||||||
| 2134 | Value *And = | ||||||||
| 2135 | Builder.CreateAnd(X, (~(C - 1)).lshr(ShiftAmt->getZExtValue())); | ||||||||
| 2136 | return new ICmpInst(Pred == ICmpInst::ICMP_ULT ? ICmpInst::ICMP_EQ | ||||||||
| 2137 | : ICmpInst::ICMP_NE, | ||||||||
| 2138 | And, Constant::getNullValue(ShType)); | ||||||||
| 2139 | } | ||||||||
| 2140 | } | ||||||||
| 2141 | |||||||||
| 2142 | // Transform (icmp pred iM (shl iM %v, N), C) | ||||||||
| 2143 | // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (C>>N)) | ||||||||
| 2144 | // Transform the shl to a trunc if (trunc (C>>N)) has no loss and M-N. | ||||||||
| 2145 | // This enables us to get rid of the shift in favor of a trunc that may be | ||||||||
| 2146 | // free on the target. It has the additional benefit of comparing to a | ||||||||
| 2147 | // smaller constant that may be more target-friendly. | ||||||||
| 2148 | unsigned Amt = ShiftAmt->getLimitedValue(TypeBits - 1); | ||||||||
| 2149 | if (Shl->hasOneUse() && Amt != 0 && C.countTrailingZeros() >= Amt && | ||||||||
| 2150 | DL.isLegalInteger(TypeBits - Amt)) { | ||||||||
| 2151 | Type *TruncTy = IntegerType::get(Cmp.getContext(), TypeBits - Amt); | ||||||||
| 2152 | if (ShType->isVectorTy()) | ||||||||
| 2153 | TruncTy = VectorType::get(TruncTy, ShType->getVectorNumElements()); | ||||||||
| 2154 | Constant *NewC = | ||||||||
| 2155 | ConstantInt::get(TruncTy, C.ashr(*ShiftAmt).trunc(TypeBits - Amt)); | ||||||||
| 2156 | return new ICmpInst(Pred, Builder.CreateTrunc(X, TruncTy), NewC); | ||||||||
| 2157 | } | ||||||||
| 2158 | |||||||||
| 2159 | return nullptr; | ||||||||
| 2160 | } | ||||||||
| 2161 | |||||||||
| 2162 | /// Fold icmp ({al}shr X, Y), C. | ||||||||
| 2163 | Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &Cmp, | ||||||||
| 2164 | BinaryOperator *Shr, | ||||||||
| 2165 | const APInt &C) { | ||||||||
| 2166 | // An exact shr only shifts out zero bits, so: | ||||||||
| 2167 | // icmp eq/ne (shr X, Y), 0 --> icmp eq/ne X, 0 | ||||||||
| 2168 | Value *X = Shr->getOperand(0); | ||||||||
| 2169 | CmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 2170 | if (Cmp.isEquality() && Shr->isExact() && Shr->hasOneUse() && | ||||||||
| 2171 | C.isNullValue()) | ||||||||
| 2172 | return new ICmpInst(Pred, X, Cmp.getOperand(1)); | ||||||||
| 2173 | |||||||||
| 2174 | const APInt *ShiftVal; | ||||||||
| 2175 | if (Cmp.isEquality() && match(Shr->getOperand(0), m_APInt(ShiftVal))) | ||||||||
| 2176 | return foldICmpShrConstConst(Cmp, Shr->getOperand(1), C, *ShiftVal); | ||||||||
| 2177 | |||||||||
| 2178 | const APInt *ShiftAmt; | ||||||||
| 2179 | if (!match(Shr->getOperand(1), m_APInt(ShiftAmt))) | ||||||||
| 2180 | return nullptr; | ||||||||
| 2181 | |||||||||
| 2182 | // Check that the shift amount is in range. If not, don't perform undefined | ||||||||
| 2183 | // shifts. When the shift is visited it will be simplified. | ||||||||
| 2184 | unsigned TypeBits = C.getBitWidth(); | ||||||||
| 2185 | unsigned ShAmtVal = ShiftAmt->getLimitedValue(TypeBits); | ||||||||
| 2186 | if (ShAmtVal >= TypeBits || ShAmtVal == 0) | ||||||||
| 2187 | return nullptr; | ||||||||
| 2188 | |||||||||
| 2189 | bool IsAShr = Shr->getOpcode() == Instruction::AShr; | ||||||||
| 2190 | bool IsExact = Shr->isExact(); | ||||||||
| 2191 | Type *ShrTy = Shr->getType(); | ||||||||
| 2192 | // TODO: If we could guarantee that InstSimplify would handle all of the | ||||||||
| 2193 | // constant-value-based preconditions in the folds below, then we could assert | ||||||||
| 2194 | // those conditions rather than checking them. This is difficult because of | ||||||||
| 2195 | // undef/poison (PR34838). | ||||||||
| 2196 | if (IsAShr) { | ||||||||
| 2197 | if (Pred == CmpInst::ICMP_SLT || (Pred == CmpInst::ICMP_SGT && IsExact)) { | ||||||||
| 2198 | // icmp slt (ashr X, ShAmtC), C --> icmp slt X, (C << ShAmtC) | ||||||||
| 2199 | // icmp sgt (ashr exact X, ShAmtC), C --> icmp sgt X, (C << ShAmtC) | ||||||||
| 2200 | APInt ShiftedC = C.shl(ShAmtVal); | ||||||||
| 2201 | if (ShiftedC.ashr(ShAmtVal) == C) | ||||||||
| 2202 | return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC)); | ||||||||
| 2203 | } | ||||||||
| 2204 | if (Pred == CmpInst::ICMP_SGT) { | ||||||||
| 2205 | // icmp sgt (ashr X, ShAmtC), C --> icmp sgt X, ((C + 1) << ShAmtC) - 1 | ||||||||
| 2206 | APInt ShiftedC = (C + 1).shl(ShAmtVal) - 1; | ||||||||
| 2207 | if (!C.isMaxSignedValue() && !(C + 1).shl(ShAmtVal).isMinSignedValue() && | ||||||||
| 2208 | (ShiftedC + 1).ashr(ShAmtVal) == (C + 1)) | ||||||||
| 2209 | return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC)); | ||||||||
| 2210 | } | ||||||||
| 2211 | } else { | ||||||||
| 2212 | if (Pred == CmpInst::ICMP_ULT || (Pred == CmpInst::ICMP_UGT && IsExact)) { | ||||||||
| 2213 | // icmp ult (lshr X, ShAmtC), C --> icmp ult X, (C << ShAmtC) | ||||||||
| 2214 | // icmp ugt (lshr exact X, ShAmtC), C --> icmp ugt X, (C << ShAmtC) | ||||||||
| 2215 | APInt ShiftedC = C.shl(ShAmtVal); | ||||||||
| 2216 | if (ShiftedC.lshr(ShAmtVal) == C) | ||||||||
| 2217 | return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC)); | ||||||||
| 2218 | } | ||||||||
| 2219 | if (Pred == CmpInst::ICMP_UGT) { | ||||||||
| 2220 | // icmp ugt (lshr X, ShAmtC), C --> icmp ugt X, ((C + 1) << ShAmtC) - 1 | ||||||||
| 2221 | APInt ShiftedC = (C + 1).shl(ShAmtVal) - 1; | ||||||||
| 2222 | if ((ShiftedC + 1).lshr(ShAmtVal) == (C + 1)) | ||||||||
| 2223 | return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC)); | ||||||||
| 2224 | } | ||||||||
| 2225 | } | ||||||||
| 2226 | |||||||||
| 2227 | if (!Cmp.isEquality()) | ||||||||
| 2228 | return nullptr; | ||||||||
| 2229 | |||||||||
| 2230 | // Handle equality comparisons of shift-by-constant. | ||||||||
| 2231 | |||||||||
| 2232 | // If the comparison constant changes with the shift, the comparison cannot | ||||||||
| 2233 | // succeed (bits of the comparison constant cannot match the shifted value). | ||||||||
| 2234 | // This should be known by InstSimplify and already be folded to true/false. | ||||||||
| 2235 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2237, __PRETTY_FUNCTION__)) | ||||||||
| 2236 | (!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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2237, __PRETTY_FUNCTION__)) | ||||||||
| 2237 | "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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2237, __PRETTY_FUNCTION__)); | ||||||||
| 2238 | |||||||||
| 2239 | // If the bits shifted out are known zero, compare the unshifted value: | ||||||||
| 2240 | // (X & 4) >> 1 == 2 --> (X & 4) == 4. | ||||||||
| 2241 | if (Shr->isExact()) | ||||||||
| 2242 | return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, C << ShAmtVal)); | ||||||||
| 2243 | |||||||||
| 2244 | if (Shr->hasOneUse()) { | ||||||||
| 2245 | // Canonicalize the shift into an 'and': | ||||||||
| 2246 | // icmp eq/ne (shr X, ShAmt), C --> icmp eq/ne (and X, HiMask), (C << ShAmt) | ||||||||
| 2247 | APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); | ||||||||
| 2248 | Constant *Mask = ConstantInt::get(ShrTy, Val); | ||||||||
| 2249 | Value *And = Builder.CreateAnd(X, Mask, Shr->getName() + ".mask"); | ||||||||
| 2250 | return new ICmpInst(Pred, And, ConstantInt::get(ShrTy, C << ShAmtVal)); | ||||||||
| 2251 | } | ||||||||
| 2252 | |||||||||
| 2253 | return nullptr; | ||||||||
| 2254 | } | ||||||||
| 2255 | |||||||||
| 2256 | Instruction *InstCombiner::foldICmpSRemConstant(ICmpInst &Cmp, | ||||||||
| 2257 | BinaryOperator *SRem, | ||||||||
| 2258 | const APInt &C) { | ||||||||
| 2259 | // Match an 'is positive' or 'is negative' comparison of remainder by a | ||||||||
| 2260 | // constant power-of-2 value: | ||||||||
| 2261 | // (X % pow2C) sgt/slt 0 | ||||||||
| 2262 | const ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 2263 | if (Pred != ICmpInst::ICMP_SGT && Pred != ICmpInst::ICMP_SLT) | ||||||||
| 2264 | return nullptr; | ||||||||
| 2265 | |||||||||
| 2266 | // TODO: The one-use check is standard because we do not typically want to | ||||||||
| 2267 | // create longer instruction sequences, but this might be a special-case | ||||||||
| 2268 | // because srem is not good for analysis or codegen. | ||||||||
| 2269 | if (!SRem->hasOneUse()) | ||||||||
| 2270 | return nullptr; | ||||||||
| 2271 | |||||||||
| 2272 | const APInt *DivisorC; | ||||||||
| 2273 | if (!C.isNullValue() || !match(SRem->getOperand(1), m_Power2(DivisorC))) | ||||||||
| 2274 | return nullptr; | ||||||||
| 2275 | |||||||||
| 2276 | // Mask off the sign bit and the modulo bits (low-bits). | ||||||||
| 2277 | Type *Ty = SRem->getType(); | ||||||||
| 2278 | APInt SignMask = APInt::getSignMask(Ty->getScalarSizeInBits()); | ||||||||
| 2279 | Constant *MaskC = ConstantInt::get(Ty, SignMask | (*DivisorC - 1)); | ||||||||
| 2280 | Value *And = Builder.CreateAnd(SRem->getOperand(0), MaskC); | ||||||||
| 2281 | |||||||||
| 2282 | // For 'is positive?' check that the sign-bit is clear and at least 1 masked | ||||||||
| 2283 | // bit is set. Example: | ||||||||
| 2284 | // (i8 X % 32) s> 0 --> (X & 159) s> 0 | ||||||||
| 2285 | if (Pred == ICmpInst::ICMP_SGT) | ||||||||
| 2286 | return new ICmpInst(ICmpInst::ICMP_SGT, And, ConstantInt::getNullValue(Ty)); | ||||||||
| 2287 | |||||||||
| 2288 | // For 'is negative?' check that the sign-bit is set and at least 1 masked | ||||||||
| 2289 | // bit is set. Example: | ||||||||
| 2290 | // (i16 X % 4) s< 0 --> (X & 32771) u> 32768 | ||||||||
| 2291 | return new ICmpInst(ICmpInst::ICMP_UGT, And, ConstantInt::get(Ty, SignMask)); | ||||||||
| 2292 | } | ||||||||
| 2293 | |||||||||
| 2294 | /// Fold icmp (udiv X, Y), C. | ||||||||
| 2295 | Instruction *InstCombiner::foldICmpUDivConstant(ICmpInst &Cmp, | ||||||||
| 2296 | BinaryOperator *UDiv, | ||||||||
| 2297 | const APInt &C) { | ||||||||
| 2298 | const APInt *C2; | ||||||||
| 2299 | if (!match(UDiv->getOperand(0), m_APInt(C2))) | ||||||||
| 2300 | return nullptr; | ||||||||
| 2301 | |||||||||
| 2302 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2302, __PRETTY_FUNCTION__)); | ||||||||
| 2303 | |||||||||
| 2304 | // (icmp ugt (udiv C2, Y), C) -> (icmp ule Y, C2/(C+1)) | ||||||||
| 2305 | Value *Y = UDiv->getOperand(1); | ||||||||
| 2306 | if (Cmp.getPredicate() == ICmpInst::ICMP_UGT) { | ||||||||
| 2307 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2308, __PRETTY_FUNCTION__)) | ||||||||
| 2308 | "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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2308, __PRETTY_FUNCTION__)); | ||||||||
| 2309 | return new ICmpInst(ICmpInst::ICMP_ULE, Y, | ||||||||
| 2310 | ConstantInt::get(Y->getType(), C2->udiv(C + 1))); | ||||||||
| 2311 | } | ||||||||
| 2312 | |||||||||
| 2313 | // (icmp ult (udiv C2, Y), C) -> (icmp ugt Y, C2/C) | ||||||||
| 2314 | if (Cmp.getPredicate() == ICmpInst::ICMP_ULT) { | ||||||||
| 2315 | 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.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2315, __PRETTY_FUNCTION__)); | ||||||||
| 2316 | return new ICmpInst(ICmpInst::ICMP_UGT, Y, | ||||||||
| 2317 | ConstantInt::get(Y->getType(), C2->udiv(C))); | ||||||||
| 2318 | } | ||||||||
| 2319 | |||||||||
| 2320 | return nullptr; | ||||||||
| 2321 | } | ||||||||
| 2322 | |||||||||
| 2323 | /// Fold icmp ({su}div X, Y), C. | ||||||||
| 2324 | Instruction *InstCombiner::foldICmpDivConstant(ICmpInst &Cmp, | ||||||||
| 2325 | BinaryOperator *Div, | ||||||||
| 2326 | const APInt &C) { | ||||||||
| 2327 | // Fold: icmp pred ([us]div X, C2), C -> range test | ||||||||
| 2328 | // Fold this div into the comparison, producing a range check. | ||||||||
| 2329 | // Determine, based on the divide type, what the range is being | ||||||||
| 2330 | // checked. If there is an overflow on the low or high side, remember | ||||||||
| 2331 | // it, otherwise compute the range [low, hi) bounding the new value. | ||||||||
| 2332 | // See: InsertRangeTest above for the kinds of replacements possible. | ||||||||
| 2333 | const APInt *C2; | ||||||||
| 2334 | if (!match(Div->getOperand(1), m_APInt(C2))) | ||||||||
| 2335 | return nullptr; | ||||||||
| 2336 | |||||||||
| 2337 | // FIXME: If the operand types don't match the type of the divide | ||||||||
| 2338 | // then don't attempt this transform. The code below doesn't have the | ||||||||
| 2339 | // logic to deal with a signed divide and an unsigned compare (and | ||||||||
| 2340 | // vice versa). This is because (x /s C2) <s C produces different | ||||||||
| 2341 | // results than (x /s C2) <u C or (x /u C2) <s C or even | ||||||||
| 2342 | // (x /u C2) <u C. Simply casting the operands and result won't | ||||||||
| 2343 | // work. :( The if statement below tests that condition and bails | ||||||||
| 2344 | // if it finds it. | ||||||||
| 2345 | bool DivIsSigned = Div->getOpcode() == Instruction::SDiv; | ||||||||
| 2346 | if (!Cmp.isEquality() && DivIsSigned != Cmp.isSigned()) | ||||||||
| 2347 | return nullptr; | ||||||||
| 2348 | |||||||||
| 2349 | // The ProdOV computation fails on divide by 0 and divide by -1. Cases with | ||||||||
| 2350 | // INT_MIN will also fail if the divisor is 1. Although folds of all these | ||||||||
| 2351 | // division-by-constant cases should be present, we can not assert that they | ||||||||
| 2352 | // have happened before we reach this icmp instruction. | ||||||||
| 2353 | if (C2->isNullValue() || C2->isOneValue() || | ||||||||
| 2354 | (DivIsSigned && C2->isAllOnesValue())) | ||||||||
| 2355 | return nullptr; | ||||||||
| 2356 | |||||||||
| 2357 | // Compute Prod = C * C2. We are essentially solving an equation of | ||||||||
| 2358 | // form X / C2 = C. We solve for X by multiplying C2 and C. | ||||||||
| 2359 | // By solving for X, we can turn this into a range check instead of computing | ||||||||
| 2360 | // a divide. | ||||||||
| 2361 | APInt Prod = C * *C2; | ||||||||
| 2362 | |||||||||
| 2363 | // Determine if the product overflows by seeing if the product is not equal to | ||||||||
| 2364 | // the divide. Make sure we do the same kind of divide as in the LHS | ||||||||
| 2365 | // instruction that we're folding. | ||||||||
| 2366 | bool ProdOV = (DivIsSigned ? Prod.sdiv(*C2) : Prod.udiv(*C2)) != C; | ||||||||
| 2367 | |||||||||
| 2368 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 2369 | |||||||||
| 2370 | // If the division is known to be exact, then there is no remainder from the | ||||||||
| 2371 | // divide, so the covered range size is unit, otherwise it is the divisor. | ||||||||
| 2372 | APInt RangeSize = Div->isExact() ? APInt(C2->getBitWidth(), 1) : *C2; | ||||||||
| 2373 | |||||||||
| 2374 | // Figure out the interval that is being checked. For example, a comparison | ||||||||
| 2375 | // like "X /u 5 == 0" is really checking that X is in the interval [0, 5). | ||||||||
| 2376 | // Compute this interval based on the constants involved and the signedness of | ||||||||
| 2377 | // the compare/divide. This computes a half-open interval, keeping track of | ||||||||
| 2378 | // whether either value in the interval overflows. After analysis each | ||||||||
| 2379 | // overflow variable is set to 0 if it's corresponding bound variable is valid | ||||||||
| 2380 | // -1 if overflowed off the bottom end, or +1 if overflowed off the top end. | ||||||||
| 2381 | int LoOverflow = 0, HiOverflow = 0; | ||||||||
| 2382 | APInt LoBound, HiBound; | ||||||||
| 2383 | |||||||||
| 2384 | if (!DivIsSigned) { // udiv | ||||||||
| 2385 | // e.g. X/5 op 3 --> [15, 20) | ||||||||
| 2386 | LoBound = Prod; | ||||||||
| 2387 | HiOverflow = LoOverflow = ProdOV; | ||||||||
| 2388 | if (!HiOverflow) { | ||||||||
| 2389 | // If this is not an exact divide, then many values in the range collapse | ||||||||
| 2390 | // to the same result value. | ||||||||
| 2391 | HiOverflow = addWithOverflow(HiBound, LoBound, RangeSize, false); | ||||||||
| 2392 | } | ||||||||
| 2393 | } else if (C2->isStrictlyPositive()) { // Divisor is > 0. | ||||||||
| 2394 | if (C.isNullValue()) { // (X / pos) op 0 | ||||||||
| 2395 | // Can't overflow. e.g. X/2 op 0 --> [-1, 2) | ||||||||
| 2396 | LoBound = -(RangeSize - 1); | ||||||||
| 2397 | HiBound = RangeSize; | ||||||||
| 2398 | } else if (C.isStrictlyPositive()) { // (X / pos) op pos | ||||||||
| 2399 | LoBound = Prod; // e.g. X/5 op 3 --> [15, 20) | ||||||||
| 2400 | HiOverflow = LoOverflow = ProdOV; | ||||||||
| 2401 | if (!HiOverflow) | ||||||||
| 2402 | HiOverflow = addWithOverflow(HiBound, Prod, RangeSize, true); | ||||||||
| 2403 | } else { // (X / pos) op neg | ||||||||
| 2404 | // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14) | ||||||||
| 2405 | HiBound = Prod + 1; | ||||||||
| 2406 | LoOverflow = HiOverflow = ProdOV ? -1 : 0; | ||||||||
| 2407 | if (!LoOverflow) { | ||||||||
| 2408 | APInt DivNeg = -RangeSize; | ||||||||
| 2409 | LoOverflow = addWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0; | ||||||||
| 2410 | } | ||||||||
| 2411 | } | ||||||||
| 2412 | } else if (C2->isNegative()) { // Divisor is < 0. | ||||||||
| 2413 | if (Div->isExact()) | ||||||||
| 2414 | RangeSize.negate(); | ||||||||
| 2415 | if (C.isNullValue()) { // (X / neg) op 0 | ||||||||
| 2416 | // e.g. X/-5 op 0 --> [-4, 5) | ||||||||
| 2417 | LoBound = RangeSize + 1; | ||||||||
| 2418 | HiBound = -RangeSize; | ||||||||
| 2419 | if (HiBound == *C2) { // -INTMIN = INTMIN | ||||||||
| 2420 | HiOverflow = 1; // [INTMIN+1, overflow) | ||||||||
| 2421 | HiBound = APInt(); // e.g. X/INTMIN = 0 --> X > INTMIN | ||||||||
| 2422 | } | ||||||||
| 2423 | } else if (C.isStrictlyPositive()) { // (X / neg) op pos | ||||||||
| 2424 | // e.g. X/-5 op 3 --> [-19, -14) | ||||||||
| 2425 | HiBound = Prod + 1; | ||||||||
| 2426 | HiOverflow = LoOverflow = ProdOV ? -1 : 0; | ||||||||
| 2427 | if (!LoOverflow) | ||||||||
| 2428 | LoOverflow = addWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0; | ||||||||
| 2429 | } else { // (X / neg) op neg | ||||||||
| 2430 | LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20) | ||||||||
| 2431 | LoOverflow = HiOverflow = ProdOV; | ||||||||
| 2432 | if (!HiOverflow) | ||||||||
| 2433 | HiOverflow = subWithOverflow(HiBound, Prod, RangeSize, true); | ||||||||
| 2434 | } | ||||||||
| 2435 | |||||||||
| 2436 | // Dividing by a negative swaps the condition. LT <-> GT | ||||||||
| 2437 | Pred = ICmpInst::getSwappedPredicate(Pred); | ||||||||
| 2438 | } | ||||||||
| 2439 | |||||||||
| 2440 | Value *X = Div->getOperand(0); | ||||||||
| 2441 | switch (Pred) { | ||||||||
| 2442 | default: llvm_unreachable("Unhandled icmp opcode!")::llvm::llvm_unreachable_internal("Unhandled icmp opcode!", "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2442); | ||||||||
| 2443 | case ICmpInst::ICMP_EQ: | ||||||||
| 2444 | if (LoOverflow && HiOverflow) | ||||||||
| 2445 | return replaceInstUsesWith(Cmp, Builder.getFalse()); | ||||||||
| 2446 | if (HiOverflow) | ||||||||
| 2447 | return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : | ||||||||
| 2448 | ICmpInst::ICMP_UGE, X, | ||||||||
| 2449 | ConstantInt::get(Div->getType(), LoBound)); | ||||||||
| 2450 | if (LoOverflow) | ||||||||
| 2451 | return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : | ||||||||
| 2452 | ICmpInst::ICMP_ULT, X, | ||||||||
| 2453 | ConstantInt::get(Div->getType(), HiBound)); | ||||||||
| 2454 | return replaceInstUsesWith( | ||||||||
| 2455 | Cmp, insertRangeTest(X, LoBound, HiBound, DivIsSigned, true)); | ||||||||
| 2456 | case ICmpInst::ICMP_NE: | ||||||||
| 2457 | if (LoOverflow && HiOverflow) | ||||||||
| 2458 | return replaceInstUsesWith(Cmp, Builder.getTrue()); | ||||||||
| 2459 | if (HiOverflow) | ||||||||
| 2460 | return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : | ||||||||
| 2461 | ICmpInst::ICMP_ULT, X, | ||||||||
| 2462 | ConstantInt::get(Div->getType(), LoBound)); | ||||||||
| 2463 | if (LoOverflow) | ||||||||
| 2464 | return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : | ||||||||
| 2465 | ICmpInst::ICMP_UGE, X, | ||||||||
| 2466 | ConstantInt::get(Div->getType(), HiBound)); | ||||||||
| 2467 | return replaceInstUsesWith(Cmp, | ||||||||
| 2468 | insertRangeTest(X, LoBound, HiBound, | ||||||||
| 2469 | DivIsSigned, false)); | ||||||||
| 2470 | case ICmpInst::ICMP_ULT: | ||||||||
| 2471 | case ICmpInst::ICMP_SLT: | ||||||||
| 2472 | if (LoOverflow == +1) // Low bound is greater than input range. | ||||||||
| 2473 | return replaceInstUsesWith(Cmp, Builder.getTrue()); | ||||||||
| 2474 | if (LoOverflow == -1) // Low bound is less than input range. | ||||||||
| 2475 | return replaceInstUsesWith(Cmp, Builder.getFalse()); | ||||||||
| 2476 | return new ICmpInst(Pred, X, ConstantInt::get(Div->getType(), LoBound)); | ||||||||
| 2477 | case ICmpInst::ICMP_UGT: | ||||||||
| 2478 | case ICmpInst::ICMP_SGT: | ||||||||
| 2479 | if (HiOverflow == +1) // High bound greater than input range. | ||||||||
| 2480 | return replaceInstUsesWith(Cmp, Builder.getFalse()); | ||||||||
| 2481 | if (HiOverflow == -1) // High bound less than input range. | ||||||||
| 2482 | return replaceInstUsesWith(Cmp, Builder.getTrue()); | ||||||||
| 2483 | if (Pred == ICmpInst::ICMP_UGT) | ||||||||
| 2484 | return new ICmpInst(ICmpInst::ICMP_UGE, X, | ||||||||
| 2485 | ConstantInt::get(Div->getType(), HiBound)); | ||||||||
| 2486 | return new ICmpInst(ICmpInst::ICMP_SGE, X, | ||||||||
| 2487 | ConstantInt::get(Div->getType(), HiBound)); | ||||||||
| 2488 | } | ||||||||
| 2489 | |||||||||
| 2490 | return nullptr; | ||||||||
| 2491 | } | ||||||||
| 2492 | |||||||||
| 2493 | /// Fold icmp (sub X, Y), C. | ||||||||
| 2494 | Instruction *InstCombiner::foldICmpSubConstant(ICmpInst &Cmp, | ||||||||
| 2495 | BinaryOperator *Sub, | ||||||||
| 2496 | const APInt &C) { | ||||||||
| 2497 | Value *X = Sub->getOperand(0), *Y = Sub->getOperand(1); | ||||||||
| 2498 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 2499 | const APInt *C2; | ||||||||
| 2500 | APInt SubResult; | ||||||||
| 2501 | |||||||||
| 2502 | // icmp eq/ne (sub C, Y), C -> icmp eq/ne Y, 0 | ||||||||
| 2503 | if (match(X, m_APInt(C2)) && *C2 == C && Cmp.isEquality()) | ||||||||
| 2504 | return new ICmpInst(Cmp.getPredicate(), Y, | ||||||||
| 2505 | ConstantInt::get(Y->getType(), 0)); | ||||||||
| 2506 | |||||||||
| 2507 | // (icmp P (sub nuw|nsw C2, Y), C) -> (icmp swap(P) Y, C2-C) | ||||||||
| 2508 | if (match(X, m_APInt(C2)) && | ||||||||
| 2509 | ((Cmp.isUnsigned() && Sub->hasNoUnsignedWrap()) || | ||||||||
| 2510 | (Cmp.isSigned() && Sub->hasNoSignedWrap())) && | ||||||||
| 2511 | !subWithOverflow(SubResult, *C2, C, Cmp.isSigned())) | ||||||||
| 2512 | return new ICmpInst(Cmp.getSwappedPredicate(), Y, | ||||||||
| 2513 | ConstantInt::get(Y->getType(), SubResult)); | ||||||||
| 2514 | |||||||||
| 2515 | // The following transforms are only worth it if the only user of the subtract | ||||||||
| 2516 | // is the icmp. | ||||||||
| 2517 | if (!Sub->hasOneUse()) | ||||||||
| 2518 | return nullptr; | ||||||||
| 2519 | |||||||||
| 2520 | if (Sub->hasNoSignedWrap()) { | ||||||||
| 2521 | // (icmp sgt (sub nsw X, Y), -1) -> (icmp sge X, Y) | ||||||||
| 2522 | if (Pred == ICmpInst::ICMP_SGT && C.isAllOnesValue()) | ||||||||
| 2523 | return new ICmpInst(ICmpInst::ICMP_SGE, X, Y); | ||||||||
| 2524 | |||||||||
| 2525 | // (icmp sgt (sub nsw X, Y), 0) -> (icmp sgt X, Y) | ||||||||
| 2526 | if (Pred == ICmpInst::ICMP_SGT && C.isNullValue()) | ||||||||
| 2527 | return new ICmpInst(ICmpInst::ICMP_SGT, X, Y); | ||||||||
| 2528 | |||||||||
| 2529 | // (icmp slt (sub nsw X, Y), 0) -> (icmp slt X, Y) | ||||||||
| 2530 | if (Pred == ICmpInst::ICMP_SLT && C.isNullValue()) | ||||||||
| 2531 | return new ICmpInst(ICmpInst::ICMP_SLT, X, Y); | ||||||||
| 2532 | |||||||||
| 2533 | // (icmp slt (sub nsw X, Y), 1) -> (icmp sle X, Y) | ||||||||
| 2534 | if (Pred == ICmpInst::ICMP_SLT && C.isOneValue()) | ||||||||
| 2535 | return new ICmpInst(ICmpInst::ICMP_SLE, X, Y); | ||||||||
| 2536 | } | ||||||||
| 2537 | |||||||||
| 2538 | if (!match(X, m_APInt(C2))) | ||||||||
| 2539 | return nullptr; | ||||||||
| 2540 | |||||||||
| 2541 | // C2 - Y <u C -> (Y | (C - 1)) == C2 | ||||||||
| 2542 | // iff (C2 & (C - 1)) == C - 1 and C is a power of 2 | ||||||||
| 2543 | if (Pred == ICmpInst::ICMP_ULT && C.isPowerOf2() && | ||||||||
| 2544 | (*C2 & (C - 1)) == (C - 1)) | ||||||||
| 2545 | return new ICmpInst(ICmpInst::ICMP_EQ, Builder.CreateOr(Y, C - 1), X); | ||||||||
| 2546 | |||||||||
| 2547 | // C2 - Y >u C -> (Y | C) != C2 | ||||||||
| 2548 | // iff C2 & C == C and C + 1 is a power of 2 | ||||||||
| 2549 | if (Pred == ICmpInst::ICMP_UGT && (C + 1).isPowerOf2() && (*C2 & C) == C) | ||||||||
| 2550 | return new ICmpInst(ICmpInst::ICMP_NE, Builder.CreateOr(Y, C), X); | ||||||||
| 2551 | |||||||||
| 2552 | return nullptr; | ||||||||
| 2553 | } | ||||||||
| 2554 | |||||||||
| 2555 | /// Fold icmp (add X, Y), C. | ||||||||
| 2556 | Instruction *InstCombiner::foldICmpAddConstant(ICmpInst &Cmp, | ||||||||
| 2557 | BinaryOperator *Add, | ||||||||
| 2558 | const APInt &C) { | ||||||||
| 2559 | Value *Y = Add->getOperand(1); | ||||||||
| 2560 | const APInt *C2; | ||||||||
| 2561 | if (Cmp.isEquality() || !match(Y, m_APInt(C2))) | ||||||||
| 2562 | return nullptr; | ||||||||
| 2563 | |||||||||
| 2564 | // Fold icmp pred (add X, C2), C. | ||||||||
| 2565 | Value *X = Add->getOperand(0); | ||||||||
| 2566 | Type *Ty = Add->getType(); | ||||||||
| 2567 | CmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 2568 | |||||||||
| 2569 | // If the add does not wrap, we can always adjust the compare by subtracting | ||||||||
| 2570 | // the constants. Equality comparisons are handled elsewhere. SGE/SLE/UGE/ULE | ||||||||
| 2571 | // are canonicalized to SGT/SLT/UGT/ULT. | ||||||||
| 2572 | if ((Add->hasNoSignedWrap() && | ||||||||
| 2573 | (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLT)) || | ||||||||
| 2574 | (Add->hasNoUnsignedWrap() && | ||||||||
| 2575 | (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULT))) { | ||||||||
| 2576 | bool Overflow; | ||||||||
| 2577 | APInt NewC = | ||||||||
| 2578 | Cmp.isSigned() ? C.ssub_ov(*C2, Overflow) : C.usub_ov(*C2, Overflow); | ||||||||
| 2579 | // If there is overflow, the result must be true or false. | ||||||||
| 2580 | // TODO: Can we assert there is no overflow because InstSimplify always | ||||||||
| 2581 | // handles those cases? | ||||||||
| 2582 | if (!Overflow) | ||||||||
| 2583 | // icmp Pred (add nsw X, C2), C --> icmp Pred X, (C - C2) | ||||||||
| 2584 | return new ICmpInst(Pred, X, ConstantInt::get(Ty, NewC)); | ||||||||
| 2585 | } | ||||||||
| 2586 | |||||||||
| 2587 | auto CR = ConstantRange::makeExactICmpRegion(Pred, C).subtract(*C2); | ||||||||
| 2588 | const APInt &Upper = CR.getUpper(); | ||||||||
| 2589 | const APInt &Lower = CR.getLower(); | ||||||||
| 2590 | if (Cmp.isSigned()) { | ||||||||
| 2591 | if (Lower.isSignMask()) | ||||||||
| 2592 | return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantInt::get(Ty, Upper)); | ||||||||
| 2593 | if (Upper.isSignMask()) | ||||||||
| 2594 | return new ICmpInst(ICmpInst::ICMP_SGE, X, ConstantInt::get(Ty, Lower)); | ||||||||
| 2595 | } else { | ||||||||
| 2596 | if (Lower.isMinValue()) | ||||||||
| 2597 | return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantInt::get(Ty, Upper)); | ||||||||
| 2598 | if (Upper.isMinValue()) | ||||||||
| 2599 | return new ICmpInst(ICmpInst::ICMP_UGE, X, ConstantInt::get(Ty, Lower)); | ||||||||
| 2600 | } | ||||||||
| 2601 | |||||||||
| 2602 | if (!Add->hasOneUse()) | ||||||||
| 2603 | return nullptr; | ||||||||
| 2604 | |||||||||
| 2605 | // X+C <u C2 -> (X & -C2) == C | ||||||||
| 2606 | // iff C & (C2-1) == 0 | ||||||||
| 2607 | // C2 is a power of 2 | ||||||||
| 2608 | if (Pred == ICmpInst::ICMP_ULT && C.isPowerOf2() && (*C2 & (C - 1)) == 0) | ||||||||
| 2609 | return new ICmpInst(ICmpInst::ICMP_EQ, Builder.CreateAnd(X, -C), | ||||||||
| 2610 | ConstantExpr::getNeg(cast<Constant>(Y))); | ||||||||
| 2611 | |||||||||
| 2612 | // X+C >u C2 -> (X & ~C2) != C | ||||||||
| 2613 | // iff C & C2 == 0 | ||||||||
| 2614 | // C2+1 is a power of 2 | ||||||||
| 2615 | if (Pred == ICmpInst::ICMP_UGT && (C + 1).isPowerOf2() && (*C2 & C) == 0) | ||||||||
| 2616 | return new ICmpInst(ICmpInst::ICMP_NE, Builder.CreateAnd(X, ~C), | ||||||||
| 2617 | ConstantExpr::getNeg(cast<Constant>(Y))); | ||||||||
| 2618 | |||||||||
| 2619 | return nullptr; | ||||||||
| 2620 | } | ||||||||
| 2621 | |||||||||
| 2622 | bool InstCombiner::matchThreeWayIntCompare(SelectInst *SI, Value *&LHS, | ||||||||
| 2623 | Value *&RHS, ConstantInt *&Less, | ||||||||
| 2624 | ConstantInt *&Equal, | ||||||||
| 2625 | ConstantInt *&Greater) { | ||||||||
| 2626 | // TODO: Generalize this to work with other comparison idioms or ensure | ||||||||
| 2627 | // they get canonicalized into this form. | ||||||||
| 2628 | |||||||||
| 2629 | // select i1 (a == b), | ||||||||
| 2630 | // i32 Equal, | ||||||||
| 2631 | // i32 (select i1 (a < b), i32 Less, i32 Greater) | ||||||||
| 2632 | // where Equal, Less and Greater are placeholders for any three constants. | ||||||||
| 2633 | ICmpInst::Predicate PredA; | ||||||||
| 2634 | if (!match(SI->getCondition(), m_ICmp(PredA, m_Value(LHS), m_Value(RHS))) || | ||||||||
| 2635 | !ICmpInst::isEquality(PredA)) | ||||||||
| 2636 | return false; | ||||||||
| 2637 | Value *EqualVal = SI->getTrueValue(); | ||||||||
| 2638 | Value *UnequalVal = SI->getFalseValue(); | ||||||||
| 2639 | // We still can get non-canonical predicate here, so canonicalize. | ||||||||
| 2640 | if (PredA == ICmpInst::ICMP_NE) | ||||||||
| 2641 | std::swap(EqualVal, UnequalVal); | ||||||||
| 2642 | if (!match(EqualVal, m_ConstantInt(Equal))) | ||||||||
| 2643 | return false; | ||||||||
| 2644 | ICmpInst::Predicate PredB; | ||||||||
| 2645 | Value *LHS2, *RHS2; | ||||||||
| 2646 | if (!match(UnequalVal, m_Select(m_ICmp(PredB, m_Value(LHS2), m_Value(RHS2)), | ||||||||
| 2647 | m_ConstantInt(Less), m_ConstantInt(Greater)))) | ||||||||
| 2648 | return false; | ||||||||
| 2649 | // We can get predicate mismatch here, so canonicalize if possible: | ||||||||
| 2650 | // First, ensure that 'LHS' match. | ||||||||
| 2651 | if (LHS2 != LHS) { | ||||||||
| 2652 | // x sgt y <--> y slt x | ||||||||
| 2653 | std::swap(LHS2, RHS2); | ||||||||
| 2654 | PredB = ICmpInst::getSwappedPredicate(PredB); | ||||||||
| 2655 | } | ||||||||
| 2656 | if (LHS2 != LHS) | ||||||||
| 2657 | return false; | ||||||||
| 2658 | // We also need to canonicalize 'RHS'. | ||||||||
| 2659 | if (PredB == ICmpInst::ICMP_SGT && isa<Constant>(RHS2)) { | ||||||||
| 2660 | // x sgt C-1 <--> x sge C <--> not(x slt C) | ||||||||
| 2661 | auto FlippedStrictness = | ||||||||
| 2662 | getFlippedStrictnessPredicateAndConstant(PredB, cast<Constant>(RHS2)); | ||||||||
| 2663 | if (!FlippedStrictness) | ||||||||
| 2664 | return false; | ||||||||
| 2665 | assert(FlippedStrictness->first == ICmpInst::ICMP_SGE && "Sanity check")((FlippedStrictness->first == ICmpInst::ICMP_SGE && "Sanity check") ? static_cast<void> (0) : __assert_fail ("FlippedStrictness->first == ICmpInst::ICMP_SGE && \"Sanity check\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2665, __PRETTY_FUNCTION__)); | ||||||||
| 2666 | RHS2 = FlippedStrictness->second; | ||||||||
| 2667 | // And kind-of perform the result swap. | ||||||||
| 2668 | std::swap(Less, Greater); | ||||||||
| 2669 | PredB = ICmpInst::ICMP_SLT; | ||||||||
| 2670 | } | ||||||||
| 2671 | return PredB == ICmpInst::ICMP_SLT && RHS == RHS2; | ||||||||
| 2672 | } | ||||||||
| 2673 | |||||||||
| 2674 | Instruction *InstCombiner::foldICmpSelectConstant(ICmpInst &Cmp, | ||||||||
| 2675 | SelectInst *Select, | ||||||||
| 2676 | ConstantInt *C) { | ||||||||
| 2677 | |||||||||
| 2678 | 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!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2678, __PRETTY_FUNCTION__)); | ||||||||
| 2679 | // If we're testing a constant value against the result of a three way | ||||||||
| 2680 | // comparison, the result can be expressed directly in terms of the | ||||||||
| 2681 | // original values being compared. Note: We could possibly be more | ||||||||
| 2682 | // aggressive here and remove the hasOneUse test. The original select is | ||||||||
| 2683 | // really likely to simplify or sink when we remove a test of the result. | ||||||||
| 2684 | Value *OrigLHS, *OrigRHS; | ||||||||
| 2685 | ConstantInt *C1LessThan, *C2Equal, *C3GreaterThan; | ||||||||
| 2686 | if (Cmp.hasOneUse() && | ||||||||
| 2687 | matchThreeWayIntCompare(Select, OrigLHS, OrigRHS, C1LessThan, C2Equal, | ||||||||
| 2688 | C3GreaterThan)) { | ||||||||
| 2689 | assert(C1LessThan && C2Equal && C3GreaterThan)((C1LessThan && C2Equal && C3GreaterThan) ? static_cast <void> (0) : __assert_fail ("C1LessThan && C2Equal && C3GreaterThan" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 2689, __PRETTY_FUNCTION__)); | ||||||||
| 2690 | |||||||||
| 2691 | bool TrueWhenLessThan = | ||||||||
| 2692 | ConstantExpr::getCompare(Cmp.getPredicate(), C1LessThan, C) | ||||||||
| 2693 | ->isAllOnesValue(); | ||||||||
| 2694 | bool TrueWhenEqual = | ||||||||
| 2695 | ConstantExpr::getCompare(Cmp.getPredicate(), C2Equal, C) | ||||||||
| 2696 | ->isAllOnesValue(); | ||||||||
| 2697 | bool TrueWhenGreaterThan = | ||||||||
| 2698 | ConstantExpr::getCompare(Cmp.getPredicate(), C3GreaterThan, C) | ||||||||
| 2699 | ->isAllOnesValue(); | ||||||||
| 2700 | |||||||||
| 2701 | // This generates the new instruction that will replace the original Cmp | ||||||||
| 2702 | // Instruction. Instead of enumerating the various combinations when | ||||||||
| 2703 | // TrueWhenLessThan, TrueWhenEqual and TrueWhenGreaterThan are true versus | ||||||||
| 2704 | // false, we rely on chaining of ORs and future passes of InstCombine to | ||||||||
| 2705 | // simplify the OR further (i.e. a s< b || a == b becomes a s<= b). | ||||||||
| 2706 | |||||||||
| 2707 | // When none of the three constants satisfy the predicate for the RHS (C), | ||||||||
| 2708 | // the entire original Cmp can be simplified to a false. | ||||||||
| 2709 | Value *Cond = Builder.getFalse(); | ||||||||
| 2710 | if (TrueWhenLessThan) | ||||||||
| 2711 | Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_SLT, | ||||||||
| 2712 | OrigLHS, OrigRHS)); | ||||||||
| 2713 | if (TrueWhenEqual) | ||||||||
| 2714 | Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_EQ, | ||||||||
| 2715 | OrigLHS, OrigRHS)); | ||||||||
| 2716 | if (TrueWhenGreaterThan) | ||||||||
| 2717 | Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_SGT, | ||||||||
| 2718 | OrigLHS, OrigRHS)); | ||||||||
| 2719 | |||||||||
| 2720 | return replaceInstUsesWith(Cmp, Cond); | ||||||||
| 2721 | } | ||||||||
| 2722 | return nullptr; | ||||||||
| 2723 | } | ||||||||
| 2724 | |||||||||
| 2725 | static Instruction *foldICmpBitCast(ICmpInst &Cmp, | ||||||||
| 2726 | InstCombiner::BuilderTy &Builder) { | ||||||||
| 2727 | auto *Bitcast = dyn_cast<BitCastInst>(Cmp.getOperand(0)); | ||||||||
| 2728 | if (!Bitcast) | ||||||||
| 2729 | return nullptr; | ||||||||
| 2730 | |||||||||
| 2731 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 2732 | Value *Op1 = Cmp.getOperand(1); | ||||||||
| 2733 | Value *BCSrcOp = Bitcast->getOperand(0); | ||||||||
| 2734 | |||||||||
| 2735 | // Make sure the bitcast doesn't change the number of vector elements. | ||||||||
| 2736 | if (Bitcast->getSrcTy()->getScalarSizeInBits() == | ||||||||
| 2737 | Bitcast->getDestTy()->getScalarSizeInBits()) { | ||||||||
| 2738 | // Zero-equality and sign-bit checks are preserved through sitofp + bitcast. | ||||||||
| 2739 | Value *X; | ||||||||
| 2740 | if (match(BCSrcOp, m_SIToFP(m_Value(X)))) { | ||||||||
| 2741 | // icmp eq (bitcast (sitofp X)), 0 --> icmp eq X, 0 | ||||||||
| 2742 | // icmp ne (bitcast (sitofp X)), 0 --> icmp ne X, 0 | ||||||||
| 2743 | // icmp slt (bitcast (sitofp X)), 0 --> icmp slt X, 0 | ||||||||
| 2744 | // icmp sgt (bitcast (sitofp X)), 0 --> icmp sgt X, 0 | ||||||||
| 2745 | if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_SLT || | ||||||||
| 2746 | Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT) && | ||||||||
| 2747 | match(Op1, m_Zero())) | ||||||||
| 2748 | return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType())); | ||||||||
| 2749 | |||||||||
| 2750 | // icmp slt (bitcast (sitofp X)), 1 --> icmp slt X, 1 | ||||||||
| 2751 | if (Pred == ICmpInst::ICMP_SLT && match(Op1, m_One())) | ||||||||
| 2752 | return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), 1)); | ||||||||
| 2753 | |||||||||
| 2754 | // icmp sgt (bitcast (sitofp X)), -1 --> icmp sgt X, -1 | ||||||||
| 2755 | if (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes())) | ||||||||
| 2756 | return new ICmpInst(Pred, X, | ||||||||
| 2757 | ConstantInt::getAllOnesValue(X->getType())); | ||||||||
| 2758 | } | ||||||||
| 2759 | |||||||||
| 2760 | // Zero-equality checks are preserved through unsigned floating-point casts: | ||||||||
| 2761 | // icmp eq (bitcast (uitofp X)), 0 --> icmp eq X, 0 | ||||||||
| 2762 | // icmp ne (bitcast (uitofp X)), 0 --> icmp ne X, 0 | ||||||||
| 2763 | if (match(BCSrcOp, m_UIToFP(m_Value(X)))) | ||||||||
| 2764 | if (Cmp.isEquality() && match(Op1, m_Zero())) | ||||||||
| 2765 | return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType())); | ||||||||
| 2766 | } | ||||||||
| 2767 | |||||||||
| 2768 | // Test to see if the operands of the icmp are casted versions of other | ||||||||
| 2769 | // values. If the ptr->ptr cast can be stripped off both arguments, do so. | ||||||||
| 2770 | if (Bitcast->getType()->isPointerTy() && | ||||||||
| 2771 | (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) { | ||||||||
| 2772 | // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast | ||||||||
| 2773 | // so eliminate it as well. | ||||||||
| 2774 | if (auto *BC2 = dyn_cast<BitCastInst>(Op1)) | ||||||||
| 2775 | Op1 = BC2->getOperand(0); | ||||||||
| 2776 | |||||||||
| 2777 | Op1 = Builder.CreateBitCast(Op1, BCSrcOp->getType()); | ||||||||
| 2778 | return new ICmpInst(Pred, BCSrcOp, Op1); | ||||||||
| 2779 | } | ||||||||
| 2780 | |||||||||
| 2781 | // Folding: icmp <pred> iN X, C | ||||||||
| 2782 | // where X = bitcast <M x iK> (shufflevector <M x iK> %vec, undef, SC)) to iN | ||||||||
| 2783 | // and C is a splat of a K-bit pattern | ||||||||
| 2784 | // and SC is a constant vector = <C', C', C', ..., C'> | ||||||||
| 2785 | // Into: | ||||||||
| 2786 | // %E = extractelement <M x iK> %vec, i32 C' | ||||||||
| 2787 | // icmp <pred> iK %E, trunc(C) | ||||||||
| 2788 | const APInt *C; | ||||||||
| 2789 | if (!match(Cmp.getOperand(1), m_APInt(C)) || | ||||||||
| 2790 | !Bitcast->getType()->isIntegerTy() || | ||||||||
| 2791 | !Bitcast->getSrcTy()->isIntOrIntVectorTy()) | ||||||||
| 2792 | return nullptr; | ||||||||
| 2793 | |||||||||
| 2794 | Value *Vec; | ||||||||
| 2795 | Constant *Mask; | ||||||||
| 2796 | if (match(BCSrcOp, | ||||||||
| 2797 | m_ShuffleVector(m_Value(Vec), m_Undef(), m_Constant(Mask)))) { | ||||||||
| 2798 | // Check whether every element of Mask is the same constant | ||||||||
| 2799 | if (auto *Elem = dyn_cast_or_null<ConstantInt>(Mask->getSplatValue())) { | ||||||||
| 2800 | auto *VecTy = cast<VectorType>(BCSrcOp->getType()); | ||||||||
| 2801 | auto *EltTy = cast<IntegerType>(VecTy->getElementType()); | ||||||||
| 2802 | if (C->isSplat(EltTy->getBitWidth())) { | ||||||||
| 2803 | // Fold the icmp based on the value of C | ||||||||
| 2804 | // If C is M copies of an iK sized bit pattern, | ||||||||
| 2805 | // then: | ||||||||
| 2806 | // => %E = extractelement <N x iK> %vec, i32 Elem | ||||||||
| 2807 | // icmp <pred> iK %SplatVal, <pattern> | ||||||||
| 2808 | Value *Extract = Builder.CreateExtractElement(Vec, Elem); | ||||||||
| 2809 | Value *NewC = ConstantInt::get(EltTy, C->trunc(EltTy->getBitWidth())); | ||||||||
| 2810 | return new ICmpInst(Pred, Extract, NewC); | ||||||||
| 2811 | } | ||||||||
| 2812 | } | ||||||||
| 2813 | } | ||||||||
| 2814 | return nullptr; | ||||||||
| 2815 | } | ||||||||
| 2816 | |||||||||
| 2817 | /// Try to fold integer comparisons with a constant operand: icmp Pred X, C | ||||||||
| 2818 | /// where X is some kind of instruction. | ||||||||
| 2819 | Instruction *InstCombiner::foldICmpInstWithConstant(ICmpInst &Cmp) { | ||||||||
| 2820 | const APInt *C; | ||||||||
| 2821 | if (!match(Cmp.getOperand(1), m_APInt(C))) | ||||||||
| 2822 | return nullptr; | ||||||||
| 2823 | |||||||||
| 2824 | if (auto *BO = dyn_cast<BinaryOperator>(Cmp.getOperand(0))) { | ||||||||
| 2825 | switch (BO->getOpcode()) { | ||||||||
| 2826 | case Instruction::Xor: | ||||||||
| 2827 | if (Instruction *I = foldICmpXorConstant(Cmp, BO, *C)) | ||||||||
| 2828 | return I; | ||||||||
| 2829 | break; | ||||||||
| 2830 | case Instruction::And: | ||||||||
| 2831 | if (Instruction *I = foldICmpAndConstant(Cmp, BO, *C)) | ||||||||
| 2832 | return I; | ||||||||
| 2833 | break; | ||||||||
| 2834 | case Instruction::Or: | ||||||||
| 2835 | if (Instruction *I = foldICmpOrConstant(Cmp, BO, *C)) | ||||||||
| 2836 | return I; | ||||||||
| 2837 | break; | ||||||||
| 2838 | case Instruction::Mul: | ||||||||
| 2839 | if (Instruction *I = foldICmpMulConstant(Cmp, BO, *C)) | ||||||||
| 2840 | return I; | ||||||||
| 2841 | break; | ||||||||
| 2842 | case Instruction::Shl: | ||||||||
| 2843 | if (Instruction *I = foldICmpShlConstant(Cmp, BO, *C)) | ||||||||
| 2844 | return I; | ||||||||
| 2845 | break; | ||||||||
| 2846 | case Instruction::LShr: | ||||||||
| 2847 | case Instruction::AShr: | ||||||||
| 2848 | if (Instruction *I = foldICmpShrConstant(Cmp, BO, *C)) | ||||||||
| 2849 | return I; | ||||||||
| 2850 | break; | ||||||||
| 2851 | case Instruction::SRem: | ||||||||
| 2852 | if (Instruction *I = foldICmpSRemConstant(Cmp, BO, *C)) | ||||||||
| 2853 | return I; | ||||||||
| 2854 | break; | ||||||||
| 2855 | case Instruction::UDiv: | ||||||||
| 2856 | if (Instruction *I = foldICmpUDivConstant(Cmp, BO, *C)) | ||||||||
| 2857 | return I; | ||||||||
| 2858 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
| 2859 | case Instruction::SDiv: | ||||||||
| 2860 | if (Instruction *I = foldICmpDivConstant(Cmp, BO, *C)) | ||||||||
| 2861 | return I; | ||||||||
| 2862 | break; | ||||||||
| 2863 | case Instruction::Sub: | ||||||||
| 2864 | if (Instruction *I = foldICmpSubConstant(Cmp, BO, *C)) | ||||||||
| 2865 | return I; | ||||||||
| 2866 | break; | ||||||||
| 2867 | case Instruction::Add: | ||||||||
| 2868 | if (Instruction *I = foldICmpAddConstant(Cmp, BO, *C)) | ||||||||
| 2869 | return I; | ||||||||
| 2870 | break; | ||||||||
| 2871 | default: | ||||||||
| 2872 | break; | ||||||||
| 2873 | } | ||||||||
| 2874 | // TODO: These folds could be refactored to be part of the above calls. | ||||||||
| 2875 | if (Instruction *I = foldICmpBinOpEqualityWithConstant(Cmp, BO, *C)) | ||||||||
| 2876 | return I; | ||||||||
| 2877 | } | ||||||||
| 2878 | |||||||||
| 2879 | // Match against CmpInst LHS being instructions other than binary operators. | ||||||||
| 2880 | |||||||||
| 2881 | if (auto *SI = dyn_cast<SelectInst>(Cmp.getOperand(0))) { | ||||||||
| 2882 | // For now, we only support constant integers while folding the | ||||||||
| 2883 | // ICMP(SELECT)) pattern. We can extend this to support vector of integers | ||||||||
| 2884 | // similar to the cases handled by binary ops above. | ||||||||
| 2885 | if (ConstantInt *ConstRHS = dyn_cast<ConstantInt>(Cmp.getOperand(1))) | ||||||||
| 2886 | if (Instruction *I = foldICmpSelectConstant(Cmp, SI, ConstRHS)) | ||||||||
| 2887 | return I; | ||||||||
| 2888 | } | ||||||||
| 2889 | |||||||||
| 2890 | if (auto *TI = dyn_cast<TruncInst>(Cmp.getOperand(0))) { | ||||||||
| 2891 | if (Instruction *I = foldICmpTruncConstant(Cmp, TI, *C)) | ||||||||
| 2892 | return I; | ||||||||
| 2893 | } | ||||||||
| 2894 | |||||||||
| 2895 | if (auto *II = dyn_cast<IntrinsicInst>(Cmp.getOperand(0))) | ||||||||
| 2896 | if (Instruction *I = foldICmpIntrinsicWithConstant(Cmp, II, *C)) | ||||||||
| 2897 | return I; | ||||||||
| 2898 | |||||||||
| 2899 | return nullptr; | ||||||||
| 2900 | } | ||||||||
| 2901 | |||||||||
| 2902 | /// Fold an icmp equality instruction with binary operator LHS and constant RHS: | ||||||||
| 2903 | /// icmp eq/ne BO, C. | ||||||||
| 2904 | Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(ICmpInst &Cmp, | ||||||||
| 2905 | BinaryOperator *BO, | ||||||||
| 2906 | const APInt &C) { | ||||||||
| 2907 | // TODO: Some of these folds could work with arbitrary constants, but this | ||||||||
| 2908 | // function is limited to scalar and vector splat constants. | ||||||||
| 2909 | if (!Cmp.isEquality()) | ||||||||
| 2910 | return nullptr; | ||||||||
| 2911 | |||||||||
| 2912 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 2913 | bool isICMP_NE = Pred == ICmpInst::ICMP_NE; | ||||||||
| 2914 | Constant *RHS = cast<Constant>(Cmp.getOperand(1)); | ||||||||
| 2915 | Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1); | ||||||||
| 2916 | |||||||||
| 2917 | switch (BO->getOpcode()) { | ||||||||
| 2918 | case Instruction::SRem: | ||||||||
| 2919 | // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. | ||||||||
| 2920 | if (C.isNullValue() && BO->hasOneUse()) { | ||||||||
| 2921 | const APInt *BOC; | ||||||||
| 2922 | if (match(BOp1, m_APInt(BOC)) && BOC->sgt(1) && BOC->isPowerOf2()) { | ||||||||
| 2923 | Value *NewRem = Builder.CreateURem(BOp0, BOp1, BO->getName()); | ||||||||
| 2924 | return new ICmpInst(Pred, NewRem, | ||||||||
| 2925 | Constant::getNullValue(BO->getType())); | ||||||||
| 2926 | } | ||||||||
| 2927 | } | ||||||||
| 2928 | break; | ||||||||
| 2929 | case Instruction::Add: { | ||||||||
| 2930 | // Replace ((add A, B) != C) with (A != C-B) if B & C are constants. | ||||||||
| 2931 | const APInt *BOC; | ||||||||
| 2932 | if (match(BOp1, m_APInt(BOC))) { | ||||||||
| 2933 | if (BO->hasOneUse()) { | ||||||||
| 2934 | Constant *SubC = ConstantExpr::getSub(RHS, cast<Constant>(BOp1)); | ||||||||
| 2935 | return new ICmpInst(Pred, BOp0, SubC); | ||||||||
| 2936 | } | ||||||||
| 2937 | } else if (C.isNullValue()) { | ||||||||
| 2938 | // Replace ((add A, B) != 0) with (A != -B) if A or B is | ||||||||
| 2939 | // efficiently invertible, or if the add has just this one use. | ||||||||
| 2940 | if (Value *NegVal = dyn_castNegVal(BOp1)) | ||||||||
| 2941 | return new ICmpInst(Pred, BOp0, NegVal); | ||||||||
| 2942 | if (Value *NegVal = dyn_castNegVal(BOp0)) | ||||||||
| 2943 | return new ICmpInst(Pred, NegVal, BOp1); | ||||||||
| 2944 | if (BO->hasOneUse()) { | ||||||||
| 2945 | Value *Neg = Builder.CreateNeg(BOp1); | ||||||||
| 2946 | Neg->takeName(BO); | ||||||||
| 2947 | return new ICmpInst(Pred, BOp0, Neg); | ||||||||
| 2948 | } | ||||||||
| 2949 | } | ||||||||
| 2950 | break; | ||||||||
| 2951 | } | ||||||||
| 2952 | case Instruction::Xor: | ||||||||
| 2953 | if (BO->hasOneUse()) { | ||||||||
| 2954 | if (Constant *BOC = dyn_cast<Constant>(BOp1)) { | ||||||||
| 2955 | // For the xor case, we can xor two constants together, eliminating | ||||||||
| 2956 | // the explicit xor. | ||||||||
| 2957 | return new ICmpInst(Pred, BOp0, ConstantExpr::getXor(RHS, BOC)); | ||||||||
| 2958 | } else if (C.isNullValue()) { | ||||||||
| 2959 | // Replace ((xor A, B) != 0) with (A != B) | ||||||||
| 2960 | return new ICmpInst(Pred, BOp0, BOp1); | ||||||||
| 2961 | } | ||||||||
| 2962 | } | ||||||||
| 2963 | break; | ||||||||
| 2964 | case Instruction::Sub: | ||||||||
| 2965 | if (BO->hasOneUse()) { | ||||||||
| 2966 | const APInt *BOC; | ||||||||
| 2967 | if (match(BOp0, m_APInt(BOC))) { | ||||||||
| 2968 | // Replace ((sub BOC, B) != C) with (B != BOC-C). | ||||||||
| 2969 | Constant *SubC = ConstantExpr::getSub(cast<Constant>(BOp0), RHS); | ||||||||
| 2970 | return new ICmpInst(Pred, BOp1, SubC); | ||||||||
| 2971 | } else if (C.isNullValue()) { | ||||||||
| 2972 | // Replace ((sub A, B) != 0) with (A != B). | ||||||||
| 2973 | return new ICmpInst(Pred, BOp0, BOp1); | ||||||||
| 2974 | } | ||||||||
| 2975 | } | ||||||||
| 2976 | break; | ||||||||
| 2977 | case Instruction::Or: { | ||||||||
| 2978 | const APInt *BOC; | ||||||||
| 2979 | if (match(BOp1, m_APInt(BOC)) && BO->hasOneUse() && RHS->isAllOnesValue()) { | ||||||||
| 2980 | // Comparing if all bits outside of a constant mask are set? | ||||||||
| 2981 | // Replace (X | C) == -1 with (X & ~C) == ~C. | ||||||||
| 2982 | // This removes the -1 constant. | ||||||||
| 2983 | Constant *NotBOC = ConstantExpr::getNot(cast<Constant>(BOp1)); | ||||||||
| 2984 | Value *And = Builder.CreateAnd(BOp0, NotBOC); | ||||||||
| 2985 | return new ICmpInst(Pred, And, NotBOC); | ||||||||
| 2986 | } | ||||||||
| 2987 | break; | ||||||||
| 2988 | } | ||||||||
| 2989 | case Instruction::And: { | ||||||||
| 2990 | const APInt *BOC; | ||||||||
| 2991 | if (match(BOp1, m_APInt(BOC))) { | ||||||||
| 2992 | // If we have ((X & C) == C), turn it into ((X & C) != 0). | ||||||||
| 2993 | if (C == *BOC && C.isPowerOf2()) | ||||||||
| 2994 | return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE, | ||||||||
| 2995 | BO, Constant::getNullValue(RHS->getType())); | ||||||||
| 2996 | } | ||||||||
| 2997 | break; | ||||||||
| 2998 | } | ||||||||
| 2999 | case Instruction::Mul: | ||||||||
| 3000 | if (C.isNullValue() && BO->hasNoSignedWrap()) { | ||||||||
| 3001 | const APInt *BOC; | ||||||||
| 3002 | if (match(BOp1, m_APInt(BOC)) && !BOC->isNullValue()) { | ||||||||
| 3003 | // The trivial case (mul X, 0) is handled by InstSimplify. | ||||||||
| 3004 | // General case : (mul X, C) != 0 iff X != 0 | ||||||||
| 3005 | // (mul X, C) == 0 iff X == 0 | ||||||||
| 3006 | return new ICmpInst(Pred, BOp0, Constant::getNullValue(RHS->getType())); | ||||||||
| 3007 | } | ||||||||
| 3008 | } | ||||||||
| 3009 | break; | ||||||||
| 3010 | case Instruction::UDiv: | ||||||||
| 3011 | if (C.isNullValue()) { | ||||||||
| 3012 | // (icmp eq/ne (udiv A, B), 0) -> (icmp ugt/ule i32 B, A) | ||||||||
| 3013 | auto NewPred = isICMP_NE ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT; | ||||||||
| 3014 | return new ICmpInst(NewPred, BOp1, BOp0); | ||||||||
| 3015 | } | ||||||||
| 3016 | break; | ||||||||
| 3017 | default: | ||||||||
| 3018 | break; | ||||||||
| 3019 | } | ||||||||
| 3020 | return nullptr; | ||||||||
| 3021 | } | ||||||||
| 3022 | |||||||||
| 3023 | /// Fold an equality icmp with LLVM intrinsic and constant operand. | ||||||||
| 3024 | Instruction *InstCombiner::foldICmpEqIntrinsicWithConstant(ICmpInst &Cmp, | ||||||||
| 3025 | IntrinsicInst *II, | ||||||||
| 3026 | const APInt &C) { | ||||||||
| 3027 | Type *Ty = II->getType(); | ||||||||
| 3028 | unsigned BitWidth = C.getBitWidth(); | ||||||||
| 3029 | switch (II->getIntrinsicID()) { | ||||||||
| 3030 | case Intrinsic::bswap: | ||||||||
| 3031 | Worklist.Add(II); | ||||||||
| 3032 | Cmp.setOperand(0, II->getArgOperand(0)); | ||||||||
| 3033 | Cmp.setOperand(1, ConstantInt::get(Ty, C.byteSwap())); | ||||||||
| 3034 | return &Cmp; | ||||||||
| 3035 | |||||||||
| 3036 | case Intrinsic::ctlz: | ||||||||
| 3037 | case Intrinsic::cttz: { | ||||||||
| 3038 | // ctz(A) == bitwidth(A) -> A == 0 and likewise for != | ||||||||
| 3039 | if (C == BitWidth) { | ||||||||
| 3040 | Worklist.Add(II); | ||||||||
| 3041 | Cmp.setOperand(0, II->getArgOperand(0)); | ||||||||
| 3042 | Cmp.setOperand(1, ConstantInt::getNullValue(Ty)); | ||||||||
| 3043 | return &Cmp; | ||||||||
| 3044 | } | ||||||||
| 3045 | |||||||||
| 3046 | // ctz(A) == C -> A & Mask1 == Mask2, where Mask2 only has bit C set | ||||||||
| 3047 | // and Mask1 has bits 0..C+1 set. Similar for ctl, but for high bits. | ||||||||
| 3048 | // Limit to one use to ensure we don't increase instruction count. | ||||||||
| 3049 | unsigned Num = C.getLimitedValue(BitWidth); | ||||||||
| 3050 | if (Num != BitWidth && II->hasOneUse()) { | ||||||||
| 3051 | bool IsTrailing = II->getIntrinsicID() == Intrinsic::cttz; | ||||||||
| 3052 | APInt Mask1 = IsTrailing ? APInt::getLowBitsSet(BitWidth, Num + 1) | ||||||||
| 3053 | : APInt::getHighBitsSet(BitWidth, Num + 1); | ||||||||
| 3054 | APInt Mask2 = IsTrailing | ||||||||
| 3055 | ? APInt::getOneBitSet(BitWidth, Num) | ||||||||
| 3056 | : APInt::getOneBitSet(BitWidth, BitWidth - Num - 1); | ||||||||
| 3057 | Cmp.setOperand(0, Builder.CreateAnd(II->getArgOperand(0), Mask1)); | ||||||||
| 3058 | Cmp.setOperand(1, ConstantInt::get(Ty, Mask2)); | ||||||||
| 3059 | Worklist.Add(II); | ||||||||
| 3060 | return &Cmp; | ||||||||
| 3061 | } | ||||||||
| 3062 | break; | ||||||||
| 3063 | } | ||||||||
| 3064 | |||||||||
| 3065 | case Intrinsic::ctpop: { | ||||||||
| 3066 | // popcount(A) == 0 -> A == 0 and likewise for != | ||||||||
| 3067 | // popcount(A) == bitwidth(A) -> A == -1 and likewise for != | ||||||||
| 3068 | bool IsZero = C.isNullValue(); | ||||||||
| 3069 | if (IsZero || C == BitWidth) { | ||||||||
| 3070 | Worklist.Add(II); | ||||||||
| 3071 | Cmp.setOperand(0, II->getArgOperand(0)); | ||||||||
| 3072 | auto *NewOp = | ||||||||
| 3073 | IsZero ? Constant::getNullValue(Ty) : Constant::getAllOnesValue(Ty); | ||||||||
| 3074 | Cmp.setOperand(1, NewOp); | ||||||||
| 3075 | return &Cmp; | ||||||||
| 3076 | } | ||||||||
| 3077 | break; | ||||||||
| 3078 | } | ||||||||
| 3079 | |||||||||
| 3080 | case Intrinsic::uadd_sat: { | ||||||||
| 3081 | // uadd.sat(a, b) == 0 -> (a | b) == 0 | ||||||||
| 3082 | if (C.isNullValue()) { | ||||||||
| 3083 | Value *Or = Builder.CreateOr(II->getArgOperand(0), II->getArgOperand(1)); | ||||||||
| 3084 | return replaceInstUsesWith(Cmp, Builder.CreateICmp( | ||||||||
| 3085 | Cmp.getPredicate(), Or, Constant::getNullValue(Ty))); | ||||||||
| 3086 | |||||||||
| 3087 | } | ||||||||
| 3088 | break; | ||||||||
| 3089 | } | ||||||||
| 3090 | |||||||||
| 3091 | case Intrinsic::usub_sat: { | ||||||||
| 3092 | // usub.sat(a, b) == 0 -> a <= b | ||||||||
| 3093 | if (C.isNullValue()) { | ||||||||
| 3094 | ICmpInst::Predicate NewPred = Cmp.getPredicate() == ICmpInst::ICMP_EQ | ||||||||
| 3095 | ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT; | ||||||||
| 3096 | return ICmpInst::Create(Instruction::ICmp, NewPred, | ||||||||
| 3097 | II->getArgOperand(0), II->getArgOperand(1)); | ||||||||
| 3098 | } | ||||||||
| 3099 | break; | ||||||||
| 3100 | } | ||||||||
| 3101 | default: | ||||||||
| 3102 | break; | ||||||||
| 3103 | } | ||||||||
| 3104 | |||||||||
| 3105 | return nullptr; | ||||||||
| 3106 | } | ||||||||
| 3107 | |||||||||
| 3108 | /// Fold an icmp with LLVM intrinsic and constant operand: icmp Pred II, C. | ||||||||
| 3109 | Instruction *InstCombiner::foldICmpIntrinsicWithConstant(ICmpInst &Cmp, | ||||||||
| 3110 | IntrinsicInst *II, | ||||||||
| 3111 | const APInt &C) { | ||||||||
| 3112 | if (Cmp.isEquality()) | ||||||||
| 3113 | return foldICmpEqIntrinsicWithConstant(Cmp, II, C); | ||||||||
| 3114 | |||||||||
| 3115 | Type *Ty = II->getType(); | ||||||||
| 3116 | unsigned BitWidth = C.getBitWidth(); | ||||||||
| 3117 | switch (II->getIntrinsicID()) { | ||||||||
| 3118 | case Intrinsic::ctlz: { | ||||||||
| 3119 | // ctlz(0bXXXXXXXX) > 3 -> 0bXXXXXXXX < 0b00010000 | ||||||||
| 3120 | if (Cmp.getPredicate() == ICmpInst::ICMP_UGT && C.ult(BitWidth)) { | ||||||||
| 3121 | unsigned Num = C.getLimitedValue(); | ||||||||
| 3122 | APInt Limit = APInt::getOneBitSet(BitWidth, BitWidth - Num - 1); | ||||||||
| 3123 | return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_ULT, | ||||||||
| 3124 | II->getArgOperand(0), ConstantInt::get(Ty, Limit)); | ||||||||
| 3125 | } | ||||||||
| 3126 | |||||||||
| 3127 | // ctlz(0bXXXXXXXX) < 3 -> 0bXXXXXXXX > 0b00011111 | ||||||||
| 3128 | if (Cmp.getPredicate() == ICmpInst::ICMP_ULT && | ||||||||
| 3129 | C.uge(1) && C.ule(BitWidth)) { | ||||||||
| 3130 | unsigned Num = C.getLimitedValue(); | ||||||||
| 3131 | APInt Limit = APInt::getLowBitsSet(BitWidth, BitWidth - Num); | ||||||||
| 3132 | return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_UGT, | ||||||||
| 3133 | II->getArgOperand(0), ConstantInt::get(Ty, Limit)); | ||||||||
| 3134 | } | ||||||||
| 3135 | break; | ||||||||
| 3136 | } | ||||||||
| 3137 | case Intrinsic::cttz: { | ||||||||
| 3138 | // Limit to one use to ensure we don't increase instruction count. | ||||||||
| 3139 | if (!II->hasOneUse()) | ||||||||
| 3140 | return nullptr; | ||||||||
| 3141 | |||||||||
| 3142 | // cttz(0bXXXXXXXX) > 3 -> 0bXXXXXXXX & 0b00001111 == 0 | ||||||||
| 3143 | if (Cmp.getPredicate() == ICmpInst::ICMP_UGT && C.ult(BitWidth)) { | ||||||||
| 3144 | APInt Mask = APInt::getLowBitsSet(BitWidth, C.getLimitedValue() + 1); | ||||||||
| 3145 | return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, | ||||||||
| 3146 | Builder.CreateAnd(II->getArgOperand(0), Mask), | ||||||||
| 3147 | ConstantInt::getNullValue(Ty)); | ||||||||
| 3148 | } | ||||||||
| 3149 | |||||||||
| 3150 | // cttz(0bXXXXXXXX) < 3 -> 0bXXXXXXXX & 0b00000111 != 0 | ||||||||
| 3151 | if (Cmp.getPredicate() == ICmpInst::ICMP_ULT && | ||||||||
| 3152 | C.uge(1) && C.ule(BitWidth)) { | ||||||||
| 3153 | APInt Mask = APInt::getLowBitsSet(BitWidth, C.getLimitedValue()); | ||||||||
| 3154 | return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_NE, | ||||||||
| 3155 | Builder.CreateAnd(II->getArgOperand(0), Mask), | ||||||||
| 3156 | ConstantInt::getNullValue(Ty)); | ||||||||
| 3157 | } | ||||||||
| 3158 | break; | ||||||||
| 3159 | } | ||||||||
| 3160 | default: | ||||||||
| 3161 | break; | ||||||||
| 3162 | } | ||||||||
| 3163 | |||||||||
| 3164 | return nullptr; | ||||||||
| 3165 | } | ||||||||
| 3166 | |||||||||
| 3167 | /// Handle icmp with constant (but not simple integer constant) RHS. | ||||||||
| 3168 | Instruction *InstCombiner::foldICmpInstWithConstantNotInt(ICmpInst &I) { | ||||||||
| 3169 | Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); | ||||||||
| 3170 | Constant *RHSC = dyn_cast<Constant>(Op1); | ||||||||
| 3171 | Instruction *LHSI = dyn_cast<Instruction>(Op0); | ||||||||
| 3172 | if (!RHSC || !LHSI) | ||||||||
| 3173 | return nullptr; | ||||||||
| 3174 | |||||||||
| 3175 | switch (LHSI->getOpcode()) { | ||||||||
| 3176 | case Instruction::GetElementPtr: | ||||||||
| 3177 | // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null | ||||||||
| 3178 | if (RHSC->isNullValue() && | ||||||||
| 3179 | cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices()) | ||||||||
| 3180 | return new ICmpInst( | ||||||||
| 3181 | I.getPredicate(), LHSI->getOperand(0), | ||||||||
| 3182 | Constant::getNullValue(LHSI->getOperand(0)->getType())); | ||||||||
| 3183 | break; | ||||||||
| 3184 | case Instruction::PHI: | ||||||||
| 3185 | // Only fold icmp into the PHI if the phi and icmp are in the same | ||||||||
| 3186 | // block. If in the same block, we're encouraging jump threading. If | ||||||||
| 3187 | // not, we are just pessimizing the code by making an i1 phi. | ||||||||
| 3188 | if (LHSI->getParent() == I.getParent()) | ||||||||
| 3189 | if (Instruction *NV = foldOpIntoPhi(I, cast<PHINode>(LHSI))) | ||||||||
| 3190 | return NV; | ||||||||
| 3191 | break; | ||||||||
| 3192 | case Instruction::Select: { | ||||||||
| 3193 | // If either operand of the select is a constant, we can fold the | ||||||||
| 3194 | // comparison into the select arms, which will cause one to be | ||||||||
| 3195 | // constant folded and the select turned into a bitwise or. | ||||||||
| 3196 | Value *Op1 = nullptr, *Op2 = nullptr; | ||||||||
| 3197 | ConstantInt *CI = nullptr; | ||||||||
| 3198 | if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) { | ||||||||
| 3199 | Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); | ||||||||
| 3200 | CI = dyn_cast<ConstantInt>(Op1); | ||||||||
| 3201 | } | ||||||||
| 3202 | if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) { | ||||||||
| 3203 | Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); | ||||||||
| 3204 | CI = dyn_cast<ConstantInt>(Op2); | ||||||||
| 3205 | } | ||||||||
| 3206 | |||||||||
| 3207 | // We only want to perform this transformation if it will not lead to | ||||||||
| 3208 | // additional code. This is true if either both sides of the select | ||||||||
| 3209 | // fold to a constant (in which case the icmp is replaced with a select | ||||||||
| 3210 | // which will usually simplify) or this is the only user of the | ||||||||
| 3211 | // select (in which case we are trading a select+icmp for a simpler | ||||||||
| 3212 | // select+icmp) or all uses of the select can be replaced based on | ||||||||
| 3213 | // dominance information ("Global cases"). | ||||||||
| 3214 | bool Transform = false; | ||||||||
| 3215 | if (Op1 && Op2) | ||||||||
| 3216 | Transform = true; | ||||||||
| 3217 | else if (Op1 || Op2) { | ||||||||
| 3218 | // Local case | ||||||||
| 3219 | if (LHSI->hasOneUse()) | ||||||||
| 3220 | Transform = true; | ||||||||
| 3221 | // Global cases | ||||||||
| 3222 | else if (CI && !CI->isZero()) | ||||||||
| 3223 | // When Op1 is constant try replacing select with second operand. | ||||||||
| 3224 | // Otherwise Op2 is constant and try replacing select with first | ||||||||
| 3225 | // operand. | ||||||||
| 3226 | Transform = | ||||||||
| 3227 | replacedSelectWithOperand(cast<SelectInst>(LHSI), &I, Op1 ? 2 : 1); | ||||||||
| 3228 | } | ||||||||
| 3229 | if (Transform) { | ||||||||
| 3230 | if (!Op1) | ||||||||
| 3231 | Op1 = Builder.CreateICmp(I.getPredicate(), LHSI->getOperand(1), RHSC, | ||||||||
| 3232 | I.getName()); | ||||||||
| 3233 | if (!Op2) | ||||||||
| 3234 | Op2 = Builder.CreateICmp(I.getPredicate(), LHSI->getOperand(2), RHSC, | ||||||||
| 3235 | I.getName()); | ||||||||
| 3236 | return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); | ||||||||
| 3237 | } | ||||||||
| 3238 | break; | ||||||||
| 3239 | } | ||||||||
| 3240 | case Instruction::IntToPtr: | ||||||||
| 3241 | // icmp pred inttoptr(X), null -> icmp pred X, 0 | ||||||||
| 3242 | if (RHSC->isNullValue() && | ||||||||
| 3243 | DL.getIntPtrType(RHSC->getType()) == LHSI->getOperand(0)->getType()) | ||||||||
| 3244 | return new ICmpInst( | ||||||||
| 3245 | I.getPredicate(), LHSI->getOperand(0), | ||||||||
| 3246 | Constant::getNullValue(LHSI->getOperand(0)->getType())); | ||||||||
| 3247 | break; | ||||||||
| 3248 | |||||||||
| 3249 | case Instruction::Load: | ||||||||
| 3250 | // Try to optimize things like "A[i] > 4" to index computations. | ||||||||
| 3251 | if (GetElementPtrInst *GEP = | ||||||||
| 3252 | dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) { | ||||||||
| 3253 | if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) | ||||||||
| 3254 | if (GV->isConstant() && GV->hasDefinitiveInitializer() && | ||||||||
| 3255 | !cast<LoadInst>(LHSI)->isVolatile()) | ||||||||
| 3256 | if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, I)) | ||||||||
| 3257 | return Res; | ||||||||
| 3258 | } | ||||||||
| 3259 | break; | ||||||||
| 3260 | } | ||||||||
| 3261 | |||||||||
| 3262 | return nullptr; | ||||||||
| 3263 | } | ||||||||
| 3264 | |||||||||
| 3265 | /// Some comparisons can be simplified. | ||||||||
| 3266 | /// In this case, we are looking for comparisons that look like | ||||||||
| 3267 | /// a check for a lossy truncation. | ||||||||
| 3268 | /// Folds: | ||||||||
| 3269 | /// icmp SrcPred (x & Mask), x to icmp DstPred x, Mask | ||||||||
| 3270 | /// Where Mask is some pattern that produces all-ones in low bits: | ||||||||
| 3271 | /// (-1 >> y) | ||||||||
| 3272 | /// ((-1 << y) >> y) <- non-canonical, has extra uses | ||||||||
| 3273 | /// ~(-1 << y) | ||||||||
| 3274 | /// ((1 << y) + (-1)) <- non-canonical, has extra uses | ||||||||
| 3275 | /// The Mask can be a constant, too. | ||||||||
| 3276 | /// For some predicates, the operands are commutative. | ||||||||
| 3277 | /// For others, x can only be on a specific side. | ||||||||
| 3278 | static Value *foldICmpWithLowBitMaskedVal(ICmpInst &I, | ||||||||
| 3279 | InstCombiner::BuilderTy &Builder) { | ||||||||
| 3280 | ICmpInst::Predicate SrcPred; | ||||||||
| 3281 | Value *X, *M, *Y; | ||||||||
| 3282 | auto m_VariableMask = m_CombineOr( | ||||||||
| 3283 | m_CombineOr(m_Not(m_Shl(m_AllOnes(), m_Value())), | ||||||||
| 3284 | m_Add(m_Shl(m_One(), m_Value()), m_AllOnes())), | ||||||||
| 3285 | m_CombineOr(m_LShr(m_AllOnes(), m_Value()), | ||||||||
| 3286 | m_LShr(m_Shl(m_AllOnes(), m_Value(Y)), m_Deferred(Y)))); | ||||||||
| 3287 | auto m_Mask = m_CombineOr(m_VariableMask, m_LowBitMask()); | ||||||||
| 3288 | if (!match(&I, m_c_ICmp(SrcPred, | ||||||||
| 3289 | m_c_And(m_CombineAnd(m_Mask, m_Value(M)), m_Value(X)), | ||||||||
| 3290 | m_Deferred(X)))) | ||||||||
| 3291 | return nullptr; | ||||||||
| 3292 | |||||||||
| 3293 | ICmpInst::Predicate DstPred; | ||||||||
| 3294 | switch (SrcPred) { | ||||||||
| 3295 | case ICmpInst::Predicate::ICMP_EQ: | ||||||||
| 3296 | // x & (-1 >> y) == x -> x u<= (-1 >> y) | ||||||||
| 3297 | DstPred = ICmpInst::Predicate::ICMP_ULE; | ||||||||
| 3298 | break; | ||||||||
| 3299 | case ICmpInst::Predicate::ICMP_NE: | ||||||||
| 3300 | // x & (-1 >> y) != x -> x u> (-1 >> y) | ||||||||
| 3301 | DstPred = ICmpInst::Predicate::ICMP_UGT; | ||||||||
| 3302 | break; | ||||||||
| 3303 | case ICmpInst::Predicate::ICMP_UGT: | ||||||||
| 3304 | // x u> x & (-1 >> y) -> x u> (-1 >> y) | ||||||||
| 3305 | assert(X == I.getOperand(0) && "instsimplify took care of commut. variant")((X == I.getOperand(0) && "instsimplify took care of commut. variant" ) ? static_cast<void> (0) : __assert_fail ("X == I.getOperand(0) && \"instsimplify took care of commut. variant\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3305, __PRETTY_FUNCTION__)); | ||||||||
| 3306 | DstPred = ICmpInst::Predicate::ICMP_UGT; | ||||||||
| 3307 | break; | ||||||||
| 3308 | case ICmpInst::Predicate::ICMP_UGE: | ||||||||
| 3309 | // x & (-1 >> y) u>= x -> x u<= (-1 >> y) | ||||||||
| 3310 | assert(X == I.getOperand(1) && "instsimplify took care of commut. variant")((X == I.getOperand(1) && "instsimplify took care of commut. variant" ) ? static_cast<void> (0) : __assert_fail ("X == I.getOperand(1) && \"instsimplify took care of commut. variant\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3310, __PRETTY_FUNCTION__)); | ||||||||
| 3311 | DstPred = ICmpInst::Predicate::ICMP_ULE; | ||||||||
| 3312 | break; | ||||||||
| 3313 | case ICmpInst::Predicate::ICMP_ULT: | ||||||||
| 3314 | // x & (-1 >> y) u< x -> x u> (-1 >> y) | ||||||||
| 3315 | assert(X == I.getOperand(1) && "instsimplify took care of commut. variant")((X == I.getOperand(1) && "instsimplify took care of commut. variant" ) ? static_cast<void> (0) : __assert_fail ("X == I.getOperand(1) && \"instsimplify took care of commut. variant\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3315, __PRETTY_FUNCTION__)); | ||||||||
| 3316 | DstPred = ICmpInst::Predicate::ICMP_UGT; | ||||||||
| 3317 | break; | ||||||||
| 3318 | case ICmpInst::Predicate::ICMP_ULE: | ||||||||
| 3319 | // x u<= x & (-1 >> y) -> x u<= (-1 >> y) | ||||||||
| 3320 | assert(X == I.getOperand(0) && "instsimplify took care of commut. variant")((X == I.getOperand(0) && "instsimplify took care of commut. variant" ) ? static_cast<void> (0) : __assert_fail ("X == I.getOperand(0) && \"instsimplify took care of commut. variant\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3320, __PRETTY_FUNCTION__)); | ||||||||
| 3321 | DstPred = ICmpInst::Predicate::ICMP_ULE; | ||||||||
| 3322 | break; | ||||||||
| 3323 | case ICmpInst::Predicate::ICMP_SGT: | ||||||||
| 3324 | // x s> x & (-1 >> y) -> x s> (-1 >> y) | ||||||||
| 3325 | if (X != I.getOperand(0)) // X must be on LHS of comparison! | ||||||||
| 3326 | return nullptr; // Ignore the other case. | ||||||||
| 3327 | if (!match(M, m_Constant())) // Can not do this fold with non-constant. | ||||||||
| 3328 | return nullptr; | ||||||||
| 3329 | if (!match(M, m_NonNegative())) // Must not have any -1 vector elements. | ||||||||
| 3330 | return nullptr; | ||||||||
| 3331 | DstPred = ICmpInst::Predicate::ICMP_SGT; | ||||||||
| 3332 | break; | ||||||||
| 3333 | case ICmpInst::Predicate::ICMP_SGE: | ||||||||
| 3334 | // x & (-1 >> y) s>= x -> x s<= (-1 >> y) | ||||||||
| 3335 | if (X != I.getOperand(1)) // X must be on RHS of comparison! | ||||||||
| 3336 | return nullptr; // Ignore the other case. | ||||||||
| 3337 | if (!match(M, m_Constant())) // Can not do this fold with non-constant. | ||||||||
| 3338 | return nullptr; | ||||||||
| 3339 | if (!match(M, m_NonNegative())) // Must not have any -1 vector elements. | ||||||||
| 3340 | return nullptr; | ||||||||
| 3341 | DstPred = ICmpInst::Predicate::ICMP_SLE; | ||||||||
| 3342 | break; | ||||||||
| 3343 | case ICmpInst::Predicate::ICMP_SLT: | ||||||||
| 3344 | // x & (-1 >> y) s< x -> x s> (-1 >> y) | ||||||||
| 3345 | if (X != I.getOperand(1)) // X must be on RHS of comparison! | ||||||||
| 3346 | return nullptr; // Ignore the other case. | ||||||||
| 3347 | if (!match(M, m_Constant())) // Can not do this fold with non-constant. | ||||||||
| 3348 | return nullptr; | ||||||||
| 3349 | if (!match(M, m_NonNegative())) // Must not have any -1 vector elements. | ||||||||
| 3350 | return nullptr; | ||||||||
| 3351 | DstPred = ICmpInst::Predicate::ICMP_SGT; | ||||||||
| 3352 | break; | ||||||||
| 3353 | case ICmpInst::Predicate::ICMP_SLE: | ||||||||
| 3354 | // x s<= x & (-1 >> y) -> x s<= (-1 >> y) | ||||||||
| 3355 | if (X != I.getOperand(0)) // X must be on LHS of comparison! | ||||||||
| 3356 | return nullptr; // Ignore the other case. | ||||||||
| 3357 | if (!match(M, m_Constant())) // Can not do this fold with non-constant. | ||||||||
| 3358 | return nullptr; | ||||||||
| 3359 | if (!match(M, m_NonNegative())) // Must not have any -1 vector elements. | ||||||||
| 3360 | return nullptr; | ||||||||
| 3361 | DstPred = ICmpInst::Predicate::ICMP_SLE; | ||||||||
| 3362 | break; | ||||||||
| 3363 | default: | ||||||||
| 3364 | llvm_unreachable("All possible folds are handled.")::llvm::llvm_unreachable_internal("All possible folds are handled." , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3364); | ||||||||
| 3365 | } | ||||||||
| 3366 | |||||||||
| 3367 | // The mask value may be a vector constant that has undefined elements. But it | ||||||||
| 3368 | // may not be safe to propagate those undefs into the new compare, so replace | ||||||||
| 3369 | // those elements by copying an existing, defined, and safe scalar constant. | ||||||||
| 3370 | Type *OpTy = M->getType(); | ||||||||
| 3371 | auto *VecC = dyn_cast<Constant>(M); | ||||||||
| 3372 | if (OpTy->isVectorTy() && VecC && VecC->containsUndefElement()) { | ||||||||
| 3373 | Constant *SafeReplacementConstant = nullptr; | ||||||||
| 3374 | for (unsigned i = 0, e = OpTy->getVectorNumElements(); i != e; ++i) { | ||||||||
| 3375 | if (!isa<UndefValue>(VecC->getAggregateElement(i))) { | ||||||||
| 3376 | SafeReplacementConstant = VecC->getAggregateElement(i); | ||||||||
| 3377 | break; | ||||||||
| 3378 | } | ||||||||
| 3379 | } | ||||||||
| 3380 | assert(SafeReplacementConstant && "Failed to find undef replacement")((SafeReplacementConstant && "Failed to find undef replacement" ) ? static_cast<void> (0) : __assert_fail ("SafeReplacementConstant && \"Failed to find undef replacement\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3380, __PRETTY_FUNCTION__)); | ||||||||
| 3381 | M = Constant::replaceUndefsWith(VecC, SafeReplacementConstant); | ||||||||
| 3382 | } | ||||||||
| 3383 | |||||||||
| 3384 | return Builder.CreateICmp(DstPred, X, M); | ||||||||
| 3385 | } | ||||||||
| 3386 | |||||||||
| 3387 | /// Some comparisons can be simplified. | ||||||||
| 3388 | /// In this case, we are looking for comparisons that look like | ||||||||
| 3389 | /// a check for a lossy signed truncation. | ||||||||
| 3390 | /// Folds: (MaskedBits is a constant.) | ||||||||
| 3391 | /// ((%x << MaskedBits) a>> MaskedBits) SrcPred %x | ||||||||
| 3392 | /// Into: | ||||||||
| 3393 | /// (add %x, (1 << (KeptBits-1))) DstPred (1 << KeptBits) | ||||||||
| 3394 | /// Where KeptBits = bitwidth(%x) - MaskedBits | ||||||||
| 3395 | static Value * | ||||||||
| 3396 | foldICmpWithTruncSignExtendedVal(ICmpInst &I, | ||||||||
| 3397 | InstCombiner::BuilderTy &Builder) { | ||||||||
| 3398 | ICmpInst::Predicate SrcPred; | ||||||||
| 3399 | Value *X; | ||||||||
| 3400 | const APInt *C0, *C1; // FIXME: non-splats, potentially with undef. | ||||||||
| 3401 | // We are ok with 'shl' having multiple uses, but 'ashr' must be one-use. | ||||||||
| 3402 | if (!match(&I, m_c_ICmp(SrcPred, | ||||||||
| 3403 | m_OneUse(m_AShr(m_Shl(m_Value(X), m_APInt(C0)), | ||||||||
| 3404 | m_APInt(C1))), | ||||||||
| 3405 | m_Deferred(X)))) | ||||||||
| 3406 | return nullptr; | ||||||||
| 3407 | |||||||||
| 3408 | // Potential handling of non-splats: for each element: | ||||||||
| 3409 | // * if both are undef, replace with constant 0. | ||||||||
| 3410 | // Because (1<<0) is OK and is 1, and ((1<<0)>>1) is also OK and is 0. | ||||||||
| 3411 | // * if both are not undef, and are different, bailout. | ||||||||
| 3412 | // * else, only one is undef, then pick the non-undef one. | ||||||||
| 3413 | |||||||||
| 3414 | // The shift amount must be equal. | ||||||||
| 3415 | if (*C0 != *C1) | ||||||||
| 3416 | return nullptr; | ||||||||
| 3417 | const APInt &MaskedBits = *C0; | ||||||||
| 3418 | assert(MaskedBits != 0 && "shift by zero should be folded away already.")((MaskedBits != 0 && "shift by zero should be folded away already." ) ? static_cast<void> (0) : __assert_fail ("MaskedBits != 0 && \"shift by zero should be folded away already.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3418, __PRETTY_FUNCTION__)); | ||||||||
| 3419 | |||||||||
| 3420 | ICmpInst::Predicate DstPred; | ||||||||
| 3421 | switch (SrcPred) { | ||||||||
| 3422 | case ICmpInst::Predicate::ICMP_EQ: | ||||||||
| 3423 | // ((%x << MaskedBits) a>> MaskedBits) == %x | ||||||||
| 3424 | // => | ||||||||
| 3425 | // (add %x, (1 << (KeptBits-1))) u< (1 << KeptBits) | ||||||||
| 3426 | DstPred = ICmpInst::Predicate::ICMP_ULT; | ||||||||
| 3427 | break; | ||||||||
| 3428 | case ICmpInst::Predicate::ICMP_NE: | ||||||||
| 3429 | // ((%x << MaskedBits) a>> MaskedBits) != %x | ||||||||
| 3430 | // => | ||||||||
| 3431 | // (add %x, (1 << (KeptBits-1))) u>= (1 << KeptBits) | ||||||||
| 3432 | DstPred = ICmpInst::Predicate::ICMP_UGE; | ||||||||
| 3433 | break; | ||||||||
| 3434 | // FIXME: are more folds possible? | ||||||||
| 3435 | default: | ||||||||
| 3436 | return nullptr; | ||||||||
| 3437 | } | ||||||||
| 3438 | |||||||||
| 3439 | auto *XType = X->getType(); | ||||||||
| 3440 | const unsigned XBitWidth = XType->getScalarSizeInBits(); | ||||||||
| 3441 | const APInt BitWidth = APInt(XBitWidth, XBitWidth); | ||||||||
| 3442 | assert(BitWidth.ugt(MaskedBits) && "shifts should leave some bits untouched")((BitWidth.ugt(MaskedBits) && "shifts should leave some bits untouched" ) ? static_cast<void> (0) : __assert_fail ("BitWidth.ugt(MaskedBits) && \"shifts should leave some bits untouched\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3442, __PRETTY_FUNCTION__)); | ||||||||
| 3443 | |||||||||
| 3444 | // KeptBits = bitwidth(%x) - MaskedBits | ||||||||
| 3445 | const APInt KeptBits = BitWidth - MaskedBits; | ||||||||
| 3446 | assert(KeptBits.ugt(0) && KeptBits.ult(BitWidth) && "unreachable")((KeptBits.ugt(0) && KeptBits.ult(BitWidth) && "unreachable") ? static_cast<void> (0) : __assert_fail ("KeptBits.ugt(0) && KeptBits.ult(BitWidth) && \"unreachable\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3446, __PRETTY_FUNCTION__)); | ||||||||
| 3447 | // ICmpCst = (1 << KeptBits) | ||||||||
| 3448 | const APInt ICmpCst = APInt(XBitWidth, 1).shl(KeptBits); | ||||||||
| 3449 | assert(ICmpCst.isPowerOf2())((ICmpCst.isPowerOf2()) ? static_cast<void> (0) : __assert_fail ("ICmpCst.isPowerOf2()", "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3449, __PRETTY_FUNCTION__)); | ||||||||
| 3450 | // AddCst = (1 << (KeptBits-1)) | ||||||||
| 3451 | const APInt AddCst = ICmpCst.lshr(1); | ||||||||
| 3452 | assert(AddCst.ult(ICmpCst) && AddCst.isPowerOf2())((AddCst.ult(ICmpCst) && AddCst.isPowerOf2()) ? static_cast <void> (0) : __assert_fail ("AddCst.ult(ICmpCst) && AddCst.isPowerOf2()" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3452, __PRETTY_FUNCTION__)); | ||||||||
| 3453 | |||||||||
| 3454 | // T0 = add %x, AddCst | ||||||||
| 3455 | Value *T0 = Builder.CreateAdd(X, ConstantInt::get(XType, AddCst)); | ||||||||
| 3456 | // T1 = T0 DstPred ICmpCst | ||||||||
| 3457 | Value *T1 = Builder.CreateICmp(DstPred, T0, ConstantInt::get(XType, ICmpCst)); | ||||||||
| 3458 | |||||||||
| 3459 | return T1; | ||||||||
| 3460 | } | ||||||||
| 3461 | |||||||||
| 3462 | // Given pattern: | ||||||||
| 3463 | // icmp eq/ne (and ((x shift Q), (y oppositeshift K))), 0 | ||||||||
| 3464 | // we should move shifts to the same hand of 'and', i.e. rewrite as | ||||||||
| 3465 | // icmp eq/ne (and (x shift (Q+K)), y), 0 iff (Q+K) u< bitwidth(x) | ||||||||
| 3466 | // We are only interested in opposite logical shifts here. | ||||||||
| 3467 | // One of the shifts can be truncated. | ||||||||
| 3468 | // If we can, we want to end up creating 'lshr' shift. | ||||||||
| 3469 | static Value * | ||||||||
| 3470 | foldShiftIntoShiftInAnotherHandOfAndInICmp(ICmpInst &I, const SimplifyQuery SQ, | ||||||||
| 3471 | InstCombiner::BuilderTy &Builder) { | ||||||||
| 3472 | if (!I.isEquality() || !match(I.getOperand(1), m_Zero()) || | ||||||||
| 3473 | !I.getOperand(0)->hasOneUse()) | ||||||||
| 3474 | return nullptr; | ||||||||
| 3475 | |||||||||
| 3476 | auto m_AnyLogicalShift = m_LogicalShift(m_Value(), m_Value()); | ||||||||
| 3477 | |||||||||
| 3478 | // Look for an 'and' of two logical shifts, one of which may be truncated. | ||||||||
| 3479 | // We use m_TruncOrSelf() on the RHS to correctly handle commutative case. | ||||||||
| 3480 | Instruction *XShift, *MaybeTruncation, *YShift; | ||||||||
| 3481 | if (!match( | ||||||||
| |||||||||
| |||||||||
| 3482 | I.getOperand(0), | ||||||||
| 3483 | m_c_And(m_CombineAnd(m_AnyLogicalShift, m_Instruction(XShift)), | ||||||||
| 3484 | m_CombineAnd(m_TruncOrSelf(m_CombineAnd( | ||||||||
| 3485 | m_AnyLogicalShift, m_Instruction(YShift))), | ||||||||
| 3486 | m_Instruction(MaybeTruncation))))) | ||||||||
| 3487 | return nullptr; | ||||||||
| 3488 | |||||||||
| 3489 | // We potentially looked past 'trunc', but only when matching YShift, | ||||||||
| 3490 | // therefore YShift must have the widest type. | ||||||||
| 3491 | Instruction *WidestShift = YShift; | ||||||||
| 3492 | // Therefore XShift must have the shallowest type. | ||||||||
| 3493 | // Or they both have identical types if there was no truncation. | ||||||||
| 3494 | Instruction *NarrowestShift = XShift; | ||||||||
| 3495 | |||||||||
| 3496 | Type *WidestTy = WidestShift->getType(); | ||||||||
| 3497 | assert(NarrowestShift->getType() == I.getOperand(0)->getType() &&((NarrowestShift->getType() == I.getOperand(0)->getType () && "We did not look past any shifts while matching XShift though." ) ? static_cast<void> (0) : __assert_fail ("NarrowestShift->getType() == I.getOperand(0)->getType() && \"We did not look past any shifts while matching XShift though.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3498, __PRETTY_FUNCTION__)) | ||||||||
| 3498 | "We did not look past any shifts while matching XShift though.")((NarrowestShift->getType() == I.getOperand(0)->getType () && "We did not look past any shifts while matching XShift though." ) ? static_cast<void> (0) : __assert_fail ("NarrowestShift->getType() == I.getOperand(0)->getType() && \"We did not look past any shifts while matching XShift though.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3498, __PRETTY_FUNCTION__)); | ||||||||
| 3499 | bool HadTrunc = WidestTy != I.getOperand(0)->getType(); | ||||||||
| 3500 | |||||||||
| 3501 | // If YShift is a 'lshr', swap the shifts around. | ||||||||
| 3502 | if (match(YShift, m_LShr(m_Value(), m_Value()))) | ||||||||
| 3503 | std::swap(XShift, YShift); | ||||||||
| 3504 | |||||||||
| 3505 | // The shifts must be in opposite directions. | ||||||||
| 3506 | auto XShiftOpcode = XShift->getOpcode(); | ||||||||
| 3507 | if (XShiftOpcode == YShift->getOpcode()) | ||||||||
| 3508 | return nullptr; // Do not care about same-direction shifts here. | ||||||||
| 3509 | |||||||||
| 3510 | Value *X, *XShAmt, *Y, *YShAmt; | ||||||||
| 3511 | match(XShift, m_BinOp(m_Value(X), m_ZExtOrSelf(m_Value(XShAmt)))); | ||||||||
| 3512 | match(YShift, m_BinOp(m_Value(Y), m_ZExtOrSelf(m_Value(YShAmt)))); | ||||||||
| 3513 | |||||||||
| 3514 | // If one of the values being shifted is a constant, then we will end with | ||||||||
| 3515 | // and+icmp, and [zext+]shift instrs will be constant-folded. If they are not, | ||||||||
| 3516 | // however, we will need to ensure that we won't increase instruction count. | ||||||||
| 3517 | if (!isa<Constant>(X) && !isa<Constant>(Y)) { | ||||||||
| 3518 | // At least one of the hands of the 'and' should be one-use shift. | ||||||||
| 3519 | if (!match(I.getOperand(0), | ||||||||
| 3520 | m_c_And(m_OneUse(m_AnyLogicalShift), m_Value()))) | ||||||||
| 3521 | return nullptr; | ||||||||
| 3522 | if (HadTrunc) { | ||||||||
| 3523 | // Due to the 'trunc', we will need to widen X. For that either the old | ||||||||
| 3524 | // 'trunc' or the shift amt in the non-truncated shift should be one-use. | ||||||||
| 3525 | if (!MaybeTruncation->hasOneUse() && | ||||||||
| 3526 | !NarrowestShift->getOperand(1)->hasOneUse()) | ||||||||
| 3527 | return nullptr; | ||||||||
| 3528 | } | ||||||||
| 3529 | } | ||||||||
| 3530 | |||||||||
| 3531 | // We have two shift amounts from two different shifts. The types of those | ||||||||
| 3532 | // shift amounts may not match. If that's the case let's bailout now. | ||||||||
| 3533 | if (XShAmt->getType() != YShAmt->getType()) | ||||||||
| |||||||||
| 3534 | return nullptr; | ||||||||
| 3535 | |||||||||
| 3536 | // Can we fold (XShAmt+YShAmt) ? | ||||||||
| 3537 | auto *NewShAmt = dyn_cast_or_null<Constant>( | ||||||||
| 3538 | SimplifyAddInst(XShAmt, YShAmt, /*isNSW=*/false, | ||||||||
| 3539 | /*isNUW=*/false, SQ.getWithInstruction(&I))); | ||||||||
| 3540 | if (!NewShAmt) | ||||||||
| 3541 | return nullptr; | ||||||||
| 3542 | NewShAmt = ConstantExpr::getZExtOrBitCast(NewShAmt, WidestTy); | ||||||||
| 3543 | unsigned WidestBitWidth = WidestTy->getScalarSizeInBits(); | ||||||||
| 3544 | |||||||||
| 3545 | // Is the new shift amount smaller than the bit width? | ||||||||
| 3546 | // FIXME: could also rely on ConstantRange. | ||||||||
| 3547 | if (!match(NewShAmt, | ||||||||
| 3548 | m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_ULT, | ||||||||
| 3549 | APInt(WidestBitWidth, WidestBitWidth)))) | ||||||||
| 3550 | return nullptr; | ||||||||
| 3551 | |||||||||
| 3552 | // An extra legality check is needed if we had trunc-of-lshr. | ||||||||
| 3553 | if (HadTrunc && match(WidestShift, m_LShr(m_Value(), m_Value()))) { | ||||||||
| 3554 | auto CanFold = [NewShAmt, WidestBitWidth, NarrowestShift, SQ, | ||||||||
| 3555 | WidestShift]() { | ||||||||
| 3556 | // It isn't obvious whether it's worth it to analyze non-constants here. | ||||||||
| 3557 | // Also, let's basically give up on non-splat cases, pessimizing vectors. | ||||||||
| 3558 | // If *any* of these preconditions matches we can perform the fold. | ||||||||
| 3559 | Constant *NewShAmtSplat = NewShAmt->getType()->isVectorTy() | ||||||||
| 3560 | ? NewShAmt->getSplatValue() | ||||||||
| 3561 | : NewShAmt; | ||||||||
| 3562 | // If it's edge-case shift (by 0 or by WidestBitWidth-1) we can fold. | ||||||||
| 3563 | if (NewShAmtSplat && | ||||||||
| 3564 | (NewShAmtSplat->isNullValue() || | ||||||||
| 3565 | NewShAmtSplat->getUniqueInteger() == WidestBitWidth - 1)) | ||||||||
| 3566 | return true; | ||||||||
| 3567 | // We consider *min* leading zeros so a single outlier | ||||||||
| 3568 | // blocks the transform as opposed to allowing it. | ||||||||
| 3569 | if (auto *C = dyn_cast<Constant>(NarrowestShift->getOperand(0))) { | ||||||||
| 3570 | KnownBits Known = computeKnownBits(C, SQ.DL); | ||||||||
| 3571 | unsigned MinLeadZero = Known.countMinLeadingZeros(); | ||||||||
| 3572 | // If the value being shifted has at most lowest bit set we can fold. | ||||||||
| 3573 | unsigned MaxActiveBits = Known.getBitWidth() - MinLeadZero; | ||||||||
| 3574 | if (MaxActiveBits <= 1) | ||||||||
| 3575 | return true; | ||||||||
| 3576 | // Precondition: NewShAmt u<= countLeadingZeros(C) | ||||||||
| 3577 | if (NewShAmtSplat && NewShAmtSplat->getUniqueInteger().ule(MinLeadZero)) | ||||||||
| 3578 | return true; | ||||||||
| 3579 | } | ||||||||
| 3580 | if (auto *C = dyn_cast<Constant>(WidestShift->getOperand(0))) { | ||||||||
| 3581 | KnownBits Known = computeKnownBits(C, SQ.DL); | ||||||||
| 3582 | unsigned MinLeadZero = Known.countMinLeadingZeros(); | ||||||||
| 3583 | // If the value being shifted has at most lowest bit set we can fold. | ||||||||
| 3584 | unsigned MaxActiveBits = Known.getBitWidth() - MinLeadZero; | ||||||||
| 3585 | if (MaxActiveBits <= 1) | ||||||||
| 3586 | return true; | ||||||||
| 3587 | // Precondition: ((WidestBitWidth-1)-NewShAmt) u<= countLeadingZeros(C) | ||||||||
| 3588 | if (NewShAmtSplat) { | ||||||||
| 3589 | APInt AdjNewShAmt = | ||||||||
| 3590 | (WidestBitWidth - 1) - NewShAmtSplat->getUniqueInteger(); | ||||||||
| 3591 | if (AdjNewShAmt.ule(MinLeadZero)) | ||||||||
| 3592 | return true; | ||||||||
| 3593 | } | ||||||||
| 3594 | } | ||||||||
| 3595 | return false; // Can't tell if it's ok. | ||||||||
| 3596 | }; | ||||||||
| 3597 | if (!CanFold()) | ||||||||
| 3598 | return nullptr; | ||||||||
| 3599 | } | ||||||||
| 3600 | |||||||||
| 3601 | // All good, we can do this fold. | ||||||||
| 3602 | X = Builder.CreateZExt(X, WidestTy); | ||||||||
| 3603 | Y = Builder.CreateZExt(Y, WidestTy); | ||||||||
| 3604 | // The shift is the same that was for X. | ||||||||
| 3605 | Value *T0 = XShiftOpcode == Instruction::BinaryOps::LShr | ||||||||
| 3606 | ? Builder.CreateLShr(X, NewShAmt) | ||||||||
| 3607 | : Builder.CreateShl(X, NewShAmt); | ||||||||
| 3608 | Value *T1 = Builder.CreateAnd(T0, Y); | ||||||||
| 3609 | return Builder.CreateICmp(I.getPredicate(), T1, | ||||||||
| 3610 | Constant::getNullValue(WidestTy)); | ||||||||
| 3611 | } | ||||||||
| 3612 | |||||||||
| 3613 | /// Fold | ||||||||
| 3614 | /// (-1 u/ x) u< y | ||||||||
| 3615 | /// ((x * y) u/ x) != y | ||||||||
| 3616 | /// to | ||||||||
| 3617 | /// @llvm.umul.with.overflow(x, y) plus extraction of overflow bit | ||||||||
| 3618 | /// Note that the comparison is commutative, while inverted (u>=, ==) predicate | ||||||||
| 3619 | /// will mean that we are looking for the opposite answer. | ||||||||
| 3620 | Value *InstCombiner::foldUnsignedMultiplicationOverflowCheck(ICmpInst &I) { | ||||||||
| 3621 | ICmpInst::Predicate Pred; | ||||||||
| 3622 | Value *X, *Y; | ||||||||
| 3623 | Instruction *Mul; | ||||||||
| 3624 | bool NeedNegation; | ||||||||
| 3625 | // Look for: (-1 u/ x) u</u>= y | ||||||||
| 3626 | if (!I.isEquality() && | ||||||||
| 3627 | match(&I, m_c_ICmp(Pred, m_OneUse(m_UDiv(m_AllOnes(), m_Value(X))), | ||||||||
| 3628 | m_Value(Y)))) { | ||||||||
| 3629 | Mul = nullptr; | ||||||||
| 3630 | // Canonicalize as-if y was on RHS. | ||||||||
| 3631 | if (I.getOperand(1) != Y) | ||||||||
| 3632 | Pred = I.getSwappedPredicate(); | ||||||||
| 3633 | |||||||||
| 3634 | // Are we checking that overflow does not happen, or does happen? | ||||||||
| 3635 | switch (Pred) { | ||||||||
| 3636 | case ICmpInst::Predicate::ICMP_ULT: | ||||||||
| 3637 | NeedNegation = false; | ||||||||
| 3638 | break; // OK | ||||||||
| 3639 | case ICmpInst::Predicate::ICMP_UGE: | ||||||||
| 3640 | NeedNegation = true; | ||||||||
| 3641 | break; // OK | ||||||||
| 3642 | default: | ||||||||
| 3643 | return nullptr; // Wrong predicate. | ||||||||
| 3644 | } | ||||||||
| 3645 | } else // Look for: ((x * y) u/ x) !=/== y | ||||||||
| 3646 | if (I.isEquality() && | ||||||||
| 3647 | match(&I, m_c_ICmp(Pred, m_Value(Y), | ||||||||
| 3648 | m_OneUse(m_UDiv(m_CombineAnd(m_c_Mul(m_Deferred(Y), | ||||||||
| 3649 | m_Value(X)), | ||||||||
| 3650 | m_Instruction(Mul)), | ||||||||
| 3651 | m_Deferred(X)))))) { | ||||||||
| 3652 | NeedNegation = Pred == ICmpInst::Predicate::ICMP_EQ; | ||||||||
| 3653 | } else | ||||||||
| 3654 | return nullptr; | ||||||||
| 3655 | |||||||||
| 3656 | BuilderTy::InsertPointGuard Guard(Builder); | ||||||||
| 3657 | // If the pattern included (x * y), we'll want to insert new instructions | ||||||||
| 3658 | // right before that original multiplication so that we can replace it. | ||||||||
| 3659 | bool MulHadOtherUses = Mul && !Mul->hasOneUse(); | ||||||||
| 3660 | if (MulHadOtherUses) | ||||||||
| 3661 | Builder.SetInsertPoint(Mul); | ||||||||
| 3662 | |||||||||
| 3663 | Function *F = Intrinsic::getDeclaration( | ||||||||
| 3664 | I.getModule(), Intrinsic::umul_with_overflow, X->getType()); | ||||||||
| 3665 | CallInst *Call = Builder.CreateCall(F, {X, Y}, "umul"); | ||||||||
| 3666 | |||||||||
| 3667 | // If the multiplication was used elsewhere, to ensure that we don't leave | ||||||||
| 3668 | // "duplicate" instructions, replace uses of that original multiplication | ||||||||
| 3669 | // with the multiplication result from the with.overflow intrinsic. | ||||||||
| 3670 | if (MulHadOtherUses) | ||||||||
| 3671 | replaceInstUsesWith(*Mul, Builder.CreateExtractValue(Call, 0, "umul.val")); | ||||||||
| 3672 | |||||||||
| 3673 | Value *Res = Builder.CreateExtractValue(Call, 1, "umul.ov"); | ||||||||
| 3674 | if (NeedNegation) // This technically increases instruction count. | ||||||||
| 3675 | Res = Builder.CreateNot(Res, "umul.not.ov"); | ||||||||
| 3676 | |||||||||
| 3677 | return Res; | ||||||||
| 3678 | } | ||||||||
| 3679 | |||||||||
| 3680 | /// Try to fold icmp (binop), X or icmp X, (binop). | ||||||||
| 3681 | /// TODO: A large part of this logic is duplicated in InstSimplify's | ||||||||
| 3682 | /// simplifyICmpWithBinOp(). We should be able to share that and avoid the code | ||||||||
| 3683 | /// duplication. | ||||||||
| 3684 | Instruction *InstCombiner::foldICmpBinOp(ICmpInst &I, const SimplifyQuery &SQ) { | ||||||||
| 3685 | const SimplifyQuery Q = SQ.getWithInstruction(&I); | ||||||||
| 3686 | Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); | ||||||||
| 3687 | |||||||||
| 3688 | // Special logic for binary operators. | ||||||||
| 3689 | BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0); | ||||||||
| |||||||||
| 3690 | BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1); | ||||||||
| 3691 | if (!BO0
| ||||||||
| 3692 | return nullptr; | ||||||||
| 3693 | |||||||||
| 3694 | const CmpInst::Predicate Pred = I.getPredicate(); | ||||||||
| 3695 | Value *X; | ||||||||
| 3696 | |||||||||
| 3697 | // Convert add-with-unsigned-overflow comparisons into a 'not' with compare. | ||||||||
| 3698 | // (Op1 + X) u</u>= Op1 --> ~Op1 u</u>= X | ||||||||
| 3699 | if (match(Op0, m_OneUse(m_c_Add(m_Specific(Op1), m_Value(X)))) && | ||||||||
| 3700 | (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_UGE)) | ||||||||
| 3701 | return new ICmpInst(Pred, Builder.CreateNot(Op1), X); | ||||||||
| 3702 | // Op0 u>/u<= (Op0 + X) --> X u>/u<= ~Op0 | ||||||||
| 3703 | if (match(Op1, m_OneUse(m_c_Add(m_Specific(Op0), m_Value(X)))) && | ||||||||
| 3704 | (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULE)) | ||||||||
| 3705 | return new ICmpInst(Pred, X, Builder.CreateNot(Op0)); | ||||||||
| 3706 | |||||||||
| 3707 | bool NoOp0WrapProblem = false, NoOp1WrapProblem = false; | ||||||||
| 3708 | if (BO0
| ||||||||
| 3709 | NoOp0WrapProblem = | ||||||||
| 3710 | ICmpInst::isEquality(Pred) || | ||||||||
| 3711 | (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) || | ||||||||
| 3712 | (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap()); | ||||||||
| 3713 | if (BO1
| ||||||||
| 3714 | NoOp1WrapProblem = | ||||||||
| 3715 | ICmpInst::isEquality(Pred) || | ||||||||
| 3716 | (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) || | ||||||||
| 3717 | (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap()); | ||||||||
| 3718 | |||||||||
| 3719 | // Analyze the case when either Op0 or Op1 is an add instruction. | ||||||||
| 3720 | // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null). | ||||||||
| 3721 | Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr; | ||||||||
| 3722 | if (BO0
| ||||||||
| 3723 | A = BO0->getOperand(0); | ||||||||
| 3724 | B = BO0->getOperand(1); | ||||||||
| 3725 | } | ||||||||
| 3726 | if (BO1
| ||||||||
| 3727 | C = BO1->getOperand(0); | ||||||||
| 3728 | D = BO1->getOperand(1); | ||||||||
| 3729 | } | ||||||||
| 3730 | |||||||||
| 3731 | // icmp (A+B), A -> icmp B, 0 for equalities or if there is no overflow. | ||||||||
| 3732 | // icmp (A+B), B -> icmp A, 0 for equalities or if there is no overflow. | ||||||||
| 3733 | if ((A
| ||||||||
| 3734 | return new ICmpInst(Pred, A == Op1 ? B : A, | ||||||||
| 3735 | Constant::getNullValue(Op1->getType())); | ||||||||
| 3736 | |||||||||
| 3737 | // icmp C, (C+D) -> icmp 0, D for equalities or if there is no overflow. | ||||||||
| 3738 | // icmp D, (C+D) -> icmp 0, C for equalities or if there is no overflow. | ||||||||
| 3739 | if ((C
| ||||||||
| 3740 | return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()), | ||||||||
| 3741 | C == Op0 ? D : C); | ||||||||
| 3742 | |||||||||
| 3743 | // icmp (A+B), (A+D) -> icmp B, D for equalities or if there is no overflow. | ||||||||
| 3744 | if (A
| ||||||||
| 3745 | NoOp1WrapProblem) { | ||||||||
| 3746 | // Determine Y and Z in the form icmp (X+Y), (X+Z). | ||||||||
| 3747 | Value *Y, *Z; | ||||||||
| 3748 | if (A == C) { | ||||||||
| 3749 | // C + B == C + D -> B == D | ||||||||
| 3750 | Y = B; | ||||||||
| 3751 | Z = D; | ||||||||
| 3752 | } else if (A == D) { | ||||||||
| 3753 | // D + B == C + D -> B == C | ||||||||
| 3754 | Y = B; | ||||||||
| 3755 | Z = C; | ||||||||
| 3756 | } else if (B == C) { | ||||||||
| 3757 | // A + C == C + D -> A == D | ||||||||
| 3758 | Y = A; | ||||||||
| 3759 | Z = D; | ||||||||
| 3760 | } else { | ||||||||
| 3761 | assert(B == D)((B == D) ? static_cast<void> (0) : __assert_fail ("B == D" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3761, __PRETTY_FUNCTION__)); | ||||||||
| 3762 | // A + D == C + D -> A == C | ||||||||
| 3763 | Y = A; | ||||||||
| 3764 | Z = C; | ||||||||
| 3765 | } | ||||||||
| 3766 | return new ICmpInst(Pred, Y, Z); | ||||||||
| 3767 | } | ||||||||
| 3768 | |||||||||
| 3769 | // icmp slt (A + -1), Op1 -> icmp sle A, Op1 | ||||||||
| 3770 | if (A
| ||||||||
| 3771 | match(B, m_AllOnes())) | ||||||||
| 3772 | return new ICmpInst(CmpInst::ICMP_SLE, A, Op1); | ||||||||
| 3773 | |||||||||
| 3774 | // icmp sge (A + -1), Op1 -> icmp sgt A, Op1 | ||||||||
| 3775 | if (A
| ||||||||
| 3776 | match(B, m_AllOnes())) | ||||||||
| 3777 | return new ICmpInst(CmpInst::ICMP_SGT, A, Op1); | ||||||||
| 3778 | |||||||||
| 3779 | // icmp sle (A + 1), Op1 -> icmp slt A, Op1 | ||||||||
| 3780 | if (A
| ||||||||
| 3781 | return new ICmpInst(CmpInst::ICMP_SLT, A, Op1); | ||||||||
| 3782 | |||||||||
| 3783 | // icmp sgt (A + 1), Op1 -> icmp sge A, Op1 | ||||||||
| 3784 | if (A
| ||||||||
| 3785 | return new ICmpInst(CmpInst::ICMP_SGE, A, Op1); | ||||||||
| 3786 | |||||||||
| 3787 | // icmp sgt Op0, (C + -1) -> icmp sge Op0, C | ||||||||
| 3788 | if (C
| ||||||||
| 3789 | match(D, m_AllOnes())) | ||||||||
| 3790 | return new ICmpInst(CmpInst::ICMP_SGE, Op0, C); | ||||||||
| 3791 | |||||||||
| 3792 | // icmp sle Op0, (C + -1) -> icmp slt Op0, C | ||||||||
| 3793 | if (C
| ||||||||
| 3794 | match(D, m_AllOnes())) | ||||||||
| 3795 | return new ICmpInst(CmpInst::ICMP_SLT, Op0, C); | ||||||||
| 3796 | |||||||||
| 3797 | // icmp sge Op0, (C + 1) -> icmp sgt Op0, C | ||||||||
| 3798 | if (C
| ||||||||
| 3799 | return new ICmpInst(CmpInst::ICMP_SGT, Op0, C); | ||||||||
| 3800 | |||||||||
| 3801 | // icmp slt Op0, (C + 1) -> icmp sle Op0, C | ||||||||
| 3802 | if (C
| ||||||||
| 3803 | return new ICmpInst(CmpInst::ICMP_SLE, Op0, C); | ||||||||
| 3804 | |||||||||
| 3805 | // TODO: The subtraction-related identities shown below also hold, but | ||||||||
| 3806 | // canonicalization from (X -nuw 1) to (X + -1) means that the combinations | ||||||||
| 3807 | // wouldn't happen even if they were implemented. | ||||||||
| 3808 | // | ||||||||
| 3809 | // icmp ult (A - 1), Op1 -> icmp ule A, Op1 | ||||||||
| 3810 | // icmp uge (A - 1), Op1 -> icmp ugt A, Op1 | ||||||||
| 3811 | // icmp ugt Op0, (C - 1) -> icmp uge Op0, C | ||||||||
| 3812 | // icmp ule Op0, (C - 1) -> icmp ult Op0, C | ||||||||
| 3813 | |||||||||
| 3814 | // icmp ule (A + 1), Op0 -> icmp ult A, Op1 | ||||||||
| 3815 | if (A
| ||||||||
| 3816 | return new ICmpInst(CmpInst::ICMP_ULT, A, Op1); | ||||||||
| 3817 | |||||||||
| 3818 | // icmp ugt (A + 1), Op0 -> icmp uge A, Op1 | ||||||||
| 3819 | if (A
| ||||||||
| 3820 | return new ICmpInst(CmpInst::ICMP_UGE, A, Op1); | ||||||||
| 3821 | |||||||||
| 3822 | // icmp uge Op0, (C + 1) -> icmp ugt Op0, C | ||||||||
| 3823 | if (C
| ||||||||
| 3824 | return new ICmpInst(CmpInst::ICMP_UGT, Op0, C); | ||||||||
| 3825 | |||||||||
| 3826 | // icmp ult Op0, (C + 1) -> icmp ule Op0, C | ||||||||
| 3827 | if (C
| ||||||||
| 3828 | return new ICmpInst(CmpInst::ICMP_ULE, Op0, C); | ||||||||
| 3829 | |||||||||
| 3830 | // if C1 has greater magnitude than C2: | ||||||||
| 3831 | // icmp (A + C1), (C + C2) -> icmp (A + C3), C | ||||||||
| 3832 | // s.t. C3 = C1 - C2 | ||||||||
| 3833 | // | ||||||||
| 3834 | // if C2 has greater magnitude than C1: | ||||||||
| 3835 | // icmp (A + C1), (C + C2) -> icmp A, (C + C3) | ||||||||
| 3836 | // s.t. C3 = C2 - C1 | ||||||||
| 3837 | if (A
| ||||||||
| 3838 | (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned()) | ||||||||
| 3839 | if (ConstantInt *C1 = dyn_cast<ConstantInt>(B)) | ||||||||
| 3840 | if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) { | ||||||||
| 3841 | const APInt &AP1 = C1->getValue(); | ||||||||
| 3842 | const APInt &AP2 = C2->getValue(); | ||||||||
| 3843 | if (AP1.isNegative() == AP2.isNegative()) { | ||||||||
| 3844 | APInt AP1Abs = C1->getValue().abs(); | ||||||||
| 3845 | APInt AP2Abs = C2->getValue().abs(); | ||||||||
| 3846 | if (AP1Abs.uge(AP2Abs)) { | ||||||||
| 3847 | ConstantInt *C3 = Builder.getInt(AP1 - AP2); | ||||||||
| 3848 | Value *NewAdd = Builder.CreateNSWAdd(A, C3); | ||||||||
| 3849 | return new ICmpInst(Pred, NewAdd, C); | ||||||||
| 3850 | } else { | ||||||||
| 3851 | ConstantInt *C3 = Builder.getInt(AP2 - AP1); | ||||||||
| 3852 | Value *NewAdd = Builder.CreateNSWAdd(C, C3); | ||||||||
| 3853 | return new ICmpInst(Pred, A, NewAdd); | ||||||||
| 3854 | } | ||||||||
| 3855 | } | ||||||||
| 3856 | } | ||||||||
| 3857 | |||||||||
| 3858 | // Analyze the case when either Op0 or Op1 is a sub instruction. | ||||||||
| 3859 | // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null). | ||||||||
| 3860 | A = nullptr; | ||||||||
| 3861 | B = nullptr; | ||||||||
| 3862 | C = nullptr; | ||||||||
| 3863 | D = nullptr; | ||||||||
| 3864 | if (BO0
| ||||||||
| 3865 | A = BO0->getOperand(0); | ||||||||
| 3866 | B = BO0->getOperand(1); | ||||||||
| 3867 | } | ||||||||
| 3868 | if (BO1
| ||||||||
| 3869 | C = BO1->getOperand(0); | ||||||||
| 3870 | D = BO1->getOperand(1); | ||||||||
| 3871 | } | ||||||||
| 3872 | |||||||||
| 3873 | // icmp (A-B), A -> icmp 0, B for equalities or if there is no overflow. | ||||||||
| 3874 | if (A
| ||||||||
| 3875 | return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B); | ||||||||
| 3876 | // icmp C, (C-D) -> icmp D, 0 for equalities or if there is no overflow. | ||||||||
| 3877 | if (C
| ||||||||
| 3878 | return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType())); | ||||||||
| 3879 | |||||||||
| 3880 | // Convert sub-with-unsigned-overflow comparisons into a comparison of args. | ||||||||
| 3881 | // (A - B) u>/u<= A --> B u>/u<= A | ||||||||
| 3882 | if (A
| ||||||||
| 3883 | return new ICmpInst(Pred, B, A); | ||||||||
| 3884 | // C u</u>= (C - D) --> C u</u>= D | ||||||||
| 3885 | if (C
| ||||||||
| 3886 | return new ICmpInst(Pred, C, D); | ||||||||
| 3887 | // (A - B) u>=/u< A --> B u>/u<= A iff B != 0 | ||||||||
| 3888 | if (A
| ||||||||
| 3889 | isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) | ||||||||
| 3890 | return new ICmpInst(CmpInst::getFlippedStrictnessPredicate(Pred), B, A); | ||||||||
| 3891 | // C u<=/u> (C - D) --> C u</u>= D iff B != 0 | ||||||||
| 3892 | if (C
| ||||||||
| 3893 | isKnownNonZero(D, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT)) | ||||||||
| 3894 | return new ICmpInst(CmpInst::getFlippedStrictnessPredicate(Pred), C, D); | ||||||||
| 3895 | |||||||||
| 3896 | // icmp (A-B), (C-B) -> icmp A, C for equalities or if there is no overflow. | ||||||||
| 3897 | if (B
| ||||||||
| 3898 | return new ICmpInst(Pred, A, C); | ||||||||
| 3899 | |||||||||
| 3900 | // icmp (A-B), (A-D) -> icmp D, B for equalities or if there is no overflow. | ||||||||
| 3901 | if (A
| ||||||||
| 3902 | return new ICmpInst(Pred, D, B); | ||||||||
| 3903 | |||||||||
| 3904 | // icmp (0-X) < cst --> x > -cst | ||||||||
| 3905 | if (NoOp0WrapProblem
| ||||||||
| 3906 | Value *X; | ||||||||
| 3907 | if (match(BO0, m_Neg(m_Value(X)))) | ||||||||
| 3908 | if (Constant *RHSC = dyn_cast<Constant>(Op1)) | ||||||||
| 3909 | if (RHSC->isNotMinSignedValue()) | ||||||||
| 3910 | return new ICmpInst(I.getSwappedPredicate(), X, | ||||||||
| 3911 | ConstantExpr::getNeg(RHSC)); | ||||||||
| 3912 | } | ||||||||
| 3913 | |||||||||
| 3914 | BinaryOperator *SRem = nullptr; | ||||||||
| 3915 | // icmp (srem X, Y), Y | ||||||||
| 3916 | if (BO0
| ||||||||
| 3917 | SRem = BO0; | ||||||||
| 3918 | // icmp Y, (srem X, Y) | ||||||||
| 3919 | else if (BO1
| ||||||||
| 3920 | Op0 == BO1->getOperand(1)) | ||||||||
| 3921 | SRem = BO1; | ||||||||
| 3922 | if (SRem
| ||||||||
| 3923 | // We don't check hasOneUse to avoid increasing register pressure because | ||||||||
| 3924 | // the value we use is the same value this instruction was already using. | ||||||||
| 3925 | switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) { | ||||||||
| 3926 | default: | ||||||||
| 3927 | break; | ||||||||
| 3928 | case ICmpInst::ICMP_EQ: | ||||||||
| 3929 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 3930 | case ICmpInst::ICMP_NE: | ||||||||
| 3931 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 3932 | case ICmpInst::ICMP_SGT: | ||||||||
| 3933 | case ICmpInst::ICMP_SGE: | ||||||||
| 3934 | return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1), | ||||||||
| 3935 | Constant::getAllOnesValue(SRem->getType())); | ||||||||
| 3936 | case ICmpInst::ICMP_SLT: | ||||||||
| 3937 | case ICmpInst::ICMP_SLE: | ||||||||
| 3938 | return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1), | ||||||||
| 3939 | Constant::getNullValue(SRem->getType())); | ||||||||
| 3940 | } | ||||||||
| 3941 | } | ||||||||
| 3942 | |||||||||
| 3943 | if (BO0
| ||||||||
| 3944 | BO1->hasOneUse() && BO0->getOperand(1) == BO1->getOperand(1)) { | ||||||||
| 3945 | switch (BO0->getOpcode()) { | ||||||||
| 3946 | default: | ||||||||
| 3947 | break; | ||||||||
| 3948 | case Instruction::Add: | ||||||||
| 3949 | case Instruction::Sub: | ||||||||
| 3950 | case Instruction::Xor: { | ||||||||
| 3951 | if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b | ||||||||
| 3952 | return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0)); | ||||||||
| 3953 | |||||||||
| 3954 | const APInt *C; | ||||||||
| 3955 | if (match(BO0->getOperand(1), m_APInt(C))) { | ||||||||
| 3956 | // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b | ||||||||
| 3957 | if (C->isSignMask()) { | ||||||||
| 3958 | ICmpInst::Predicate NewPred = | ||||||||
| 3959 | I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate(); | ||||||||
| 3960 | return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0)); | ||||||||
| 3961 | } | ||||||||
| 3962 | |||||||||
| 3963 | // icmp u/s (a ^ maxsignval), (b ^ maxsignval) --> icmp s/u' a, b | ||||||||
| 3964 | if (BO0->getOpcode() == Instruction::Xor && C->isMaxSignedValue()) { | ||||||||
| 3965 | ICmpInst::Predicate NewPred = | ||||||||
| 3966 | I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate(); | ||||||||
| 3967 | NewPred = I.getSwappedPredicate(NewPred); | ||||||||
| 3968 | return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0)); | ||||||||
| 3969 | } | ||||||||
| 3970 | } | ||||||||
| 3971 | break; | ||||||||
| 3972 | } | ||||||||
| 3973 | case Instruction::Mul: { | ||||||||
| 3974 | if (!I.isEquality()) | ||||||||
| 3975 | break; | ||||||||
| 3976 | |||||||||
| 3977 | const APInt *C; | ||||||||
| 3978 | if (match(BO0->getOperand(1), m_APInt(C)) && !C->isNullValue() && | ||||||||
| 3979 | !C->isOneValue()) { | ||||||||
| 3980 | // icmp eq/ne (X * C), (Y * C) --> icmp (X & Mask), (Y & Mask) | ||||||||
| 3981 | // Mask = -1 >> count-trailing-zeros(C). | ||||||||
| 3982 | if (unsigned TZs = C->countTrailingZeros()) { | ||||||||
| 3983 | Constant *Mask = ConstantInt::get( | ||||||||
| 3984 | BO0->getType(), | ||||||||
| 3985 | APInt::getLowBitsSet(C->getBitWidth(), C->getBitWidth() - TZs)); | ||||||||
| 3986 | Value *And1 = Builder.CreateAnd(BO0->getOperand(0), Mask); | ||||||||
| 3987 | Value *And2 = Builder.CreateAnd(BO1->getOperand(0), Mask); | ||||||||
| 3988 | return new ICmpInst(Pred, And1, And2); | ||||||||
| 3989 | } | ||||||||
| 3990 | // If there are no trailing zeros in the multiplier, just eliminate | ||||||||
| 3991 | // the multiplies (no masking is needed): | ||||||||
| 3992 | // icmp eq/ne (X * C), (Y * C) --> icmp eq/ne X, Y | ||||||||
| 3993 | return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0)); | ||||||||
| 3994 | } | ||||||||
| 3995 | break; | ||||||||
| 3996 | } | ||||||||
| 3997 | case Instruction::UDiv: | ||||||||
| 3998 | case Instruction::LShr: | ||||||||
| 3999 | if (I.isSigned() || !BO0->isExact() || !BO1->isExact()) | ||||||||
| 4000 | break; | ||||||||
| 4001 | return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0)); | ||||||||
| 4002 | |||||||||
| 4003 | case Instruction::SDiv: | ||||||||
| 4004 | if (!I.isEquality() || !BO0->isExact() || !BO1->isExact()) | ||||||||
| 4005 | break; | ||||||||
| 4006 | return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0)); | ||||||||
| 4007 | |||||||||
| 4008 | case Instruction::AShr: | ||||||||
| 4009 | if (!BO0->isExact() || !BO1->isExact()) | ||||||||
| 4010 | break; | ||||||||
| 4011 | return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0)); | ||||||||
| 4012 | |||||||||
| 4013 | case Instruction::Shl: { | ||||||||
| 4014 | bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap(); | ||||||||
| 4015 | bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap(); | ||||||||
| 4016 | if (!NUW && !NSW) | ||||||||
| 4017 | break; | ||||||||
| 4018 | if (!NSW && I.isSigned()) | ||||||||
| 4019 | break; | ||||||||
| 4020 | return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0)); | ||||||||
| 4021 | } | ||||||||
| 4022 | } | ||||||||
| 4023 | } | ||||||||
| 4024 | |||||||||
| 4025 | if (BO0
| ||||||||
| 4026 | // Transform A & (L - 1) `ult` L --> L != 0 | ||||||||
| 4027 | auto LSubOne = m_Add(m_Specific(Op1), m_AllOnes()); | ||||||||
| 4028 | auto BitwiseAnd = m_c_And(m_Value(), LSubOne); | ||||||||
| 4029 | |||||||||
| 4030 | if (match(BO0, BitwiseAnd) && Pred == ICmpInst::ICMP_ULT) { | ||||||||
| 4031 | auto *Zero = Constant::getNullValue(BO0->getType()); | ||||||||
| 4032 | return new ICmpInst(ICmpInst::ICMP_NE, Op1, Zero); | ||||||||
| 4033 | } | ||||||||
| 4034 | } | ||||||||
| 4035 | |||||||||
| 4036 | if (Value *V
| ||||||||
| 4037 | return replaceInstUsesWith(I, V); | ||||||||
| 4038 | |||||||||
| 4039 | if (Value *V
| ||||||||
| 4040 | return replaceInstUsesWith(I, V); | ||||||||
| 4041 | |||||||||
| 4042 | if (Value *V
| ||||||||
| 4043 | return replaceInstUsesWith(I, V); | ||||||||
| 4044 | |||||||||
| 4045 | if (Value *V = foldShiftIntoShiftInAnotherHandOfAndInICmp(I, SQ, Builder)) | ||||||||
| 4046 | return replaceInstUsesWith(I, V); | ||||||||
| 4047 | |||||||||
| 4048 | return nullptr; | ||||||||
| 4049 | } | ||||||||
| 4050 | |||||||||
| 4051 | /// Fold icmp Pred min|max(X, Y), X. | ||||||||
| 4052 | static Instruction *foldICmpWithMinMax(ICmpInst &Cmp) { | ||||||||
| 4053 | ICmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
| 4054 | Value *Op0 = Cmp.getOperand(0); | ||||||||
| 4055 | Value *X = Cmp.getOperand(1); | ||||||||
| 4056 | |||||||||
| 4057 | // Canonicalize minimum or maximum operand to LHS of the icmp. | ||||||||
| 4058 | if (match(X, m_c_SMin(m_Specific(Op0), m_Value())) || | ||||||||
| 4059 | match(X, m_c_SMax(m_Specific(Op0), m_Value())) || | ||||||||
| 4060 | match(X, m_c_UMin(m_Specific(Op0), m_Value())) || | ||||||||
| 4061 | match(X, m_c_UMax(m_Specific(Op0), m_Value()))) { | ||||||||
| 4062 | std::swap(Op0, X); | ||||||||
| 4063 | Pred = Cmp.getSwappedPredicate(); | ||||||||
| 4064 | } | ||||||||
| 4065 | |||||||||
| 4066 | Value *Y; | ||||||||
| 4067 | if (match(Op0, m_c_SMin(m_Specific(X), m_Value(Y)))) { | ||||||||
| 4068 | // smin(X, Y) == X --> X s<= Y | ||||||||
| 4069 | // smin(X, Y) s>= X --> X s<= Y | ||||||||
| 4070 | if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SGE) | ||||||||
| 4071 | return new ICmpInst(ICmpInst::ICMP_SLE, X, Y); | ||||||||
| 4072 | |||||||||
| 4073 | // smin(X, Y) != X --> X s> Y | ||||||||
| 4074 | // smin(X, Y) s< X --> X s> Y | ||||||||
| 4075 | if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SLT) | ||||||||
| 4076 | return new ICmpInst(ICmpInst::ICMP_SGT, X, Y); | ||||||||
| 4077 | |||||||||
| 4078 | // These cases should be handled in InstSimplify: | ||||||||
| 4079 | // smin(X, Y) s<= X --> true | ||||||||
| 4080 | // smin(X, Y) s> X --> false | ||||||||
| 4081 | return nullptr; | ||||||||
| 4082 | } | ||||||||
| 4083 | |||||||||
| 4084 | if (match(Op0, m_c_SMax(m_Specific(X), m_Value(Y)))) { | ||||||||
| 4085 | // smax(X, Y) == X --> X s>= Y | ||||||||
| 4086 | // smax(X, Y) s<= X --> X s>= Y | ||||||||
| 4087 | if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SLE) | ||||||||
| 4088 | return new ICmpInst(ICmpInst::ICMP_SGE, X, Y); | ||||||||
| 4089 | |||||||||
| 4090 | // smax(X, Y) != X --> X s< Y | ||||||||
| 4091 | // smax(X, Y) s> X --> X s< Y | ||||||||
| 4092 | if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SGT) | ||||||||
| 4093 | return new ICmpInst(ICmpInst::ICMP_SLT, X, Y); | ||||||||
| 4094 | |||||||||
| 4095 | // These cases should be handled in InstSimplify: | ||||||||
| 4096 | // smax(X, Y) s>= X --> true | ||||||||
| 4097 | // smax(X, Y) s< X --> false | ||||||||
| 4098 | return nullptr; | ||||||||
| 4099 | } | ||||||||
| 4100 | |||||||||
| 4101 | if (match(Op0, m_c_UMin(m_Specific(X), m_Value(Y)))) { | ||||||||
| 4102 | // umin(X, Y) == X --> X u<= Y | ||||||||
| 4103 | // umin(X, Y) u>= X --> X u<= Y | ||||||||
| 4104 | if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_UGE) | ||||||||
| 4105 | return new ICmpInst(ICmpInst::ICMP_ULE, X, Y); | ||||||||
| 4106 | |||||||||
| 4107 | // umin(X, Y) != X --> X u> Y | ||||||||
| 4108 | // umin(X, Y) u< X --> X u> Y | ||||||||
| 4109 | if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_ULT) | ||||||||
| 4110 | return new ICmpInst(ICmpInst::ICMP_UGT, X, Y); | ||||||||
| 4111 | |||||||||
| 4112 | // These cases should be handled in InstSimplify: | ||||||||
| 4113 | // umin(X, Y) u<= X --> true | ||||||||
| 4114 | // umin(X, Y) u> X --> false | ||||||||
| 4115 | return nullptr; | ||||||||
| 4116 | } | ||||||||
| 4117 | |||||||||
| 4118 | if (match(Op0, m_c_UMax(m_Specific(X), m_Value(Y)))) { | ||||||||
| 4119 | // umax(X, Y) == X --> X u>= Y | ||||||||
| 4120 | // umax(X, Y) u<= X --> X u>= Y | ||||||||
| 4121 | if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_ULE) | ||||||||
| 4122 | return new ICmpInst(ICmpInst::ICMP_UGE, X, Y); | ||||||||
| 4123 | |||||||||
| 4124 | // umax(X, Y) != X --> X u< Y | ||||||||
| 4125 | // umax(X, Y) u> X --> X u< Y | ||||||||
| 4126 | if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_UGT) | ||||||||
| 4127 | return new ICmpInst(ICmpInst::ICMP_ULT, X, Y); | ||||||||
| 4128 | |||||||||
| 4129 | // These cases should be handled in InstSimplify: | ||||||||
| 4130 | // umax(X, Y) u>= X --> true | ||||||||
| 4131 | // umax(X, Y) u< X --> false | ||||||||
| 4132 | return nullptr; | ||||||||
| 4133 | } | ||||||||
| 4134 | |||||||||
| 4135 | return nullptr; | ||||||||
| 4136 | } | ||||||||
| 4137 | |||||||||
| 4138 | Instruction *InstCombiner::foldICmpEquality(ICmpInst &I) { | ||||||||
| 4139 | if (!I.isEquality()) | ||||||||
| 4140 | return nullptr; | ||||||||
| 4141 | |||||||||
| 4142 | Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); | ||||||||
| 4143 | const CmpInst::Predicate Pred = I.getPredicate(); | ||||||||
| 4144 | Value *A, *B, *C, *D; | ||||||||
| 4145 | if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) { | ||||||||
| 4146 | if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0 | ||||||||
| 4147 | Value *OtherVal = A == Op1 ? B : A; | ||||||||
| 4148 | return new ICmpInst(Pred, OtherVal, Constant::getNullValue(A->getType())); | ||||||||
| 4149 | } | ||||||||
| 4150 | |||||||||
| 4151 | if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) { | ||||||||
| 4152 | // A^c1 == C^c2 --> A == C^(c1^c2) | ||||||||
| 4153 | ConstantInt *C1, *C2; | ||||||||
| 4154 | if (match(B, m_ConstantInt(C1)) && match(D, m_ConstantInt(C2)) && | ||||||||
| 4155 | Op1->hasOneUse()) { | ||||||||
| 4156 | Constant *NC = Builder.getInt(C1->getValue() ^ C2->getValue()); | ||||||||
| 4157 | Value *Xor = Builder.CreateXor(C, NC); | ||||||||
| 4158 | return new ICmpInst(Pred, A, Xor); | ||||||||
| 4159 | } | ||||||||
| 4160 | |||||||||
| 4161 | // A^B == A^D -> B == D | ||||||||
| 4162 | if (A == C) | ||||||||
| 4163 | return new ICmpInst(Pred, B, D); | ||||||||
| 4164 | if (A == D) | ||||||||
| 4165 | return new ICmpInst(Pred, B, C); | ||||||||
| 4166 | if (B == C) | ||||||||
| 4167 | return new ICmpInst(Pred, A, D); | ||||||||
| 4168 | if (B == D) | ||||||||
| 4169 | return new ICmpInst(Pred, A, C); | ||||||||
| 4170 | } | ||||||||
| 4171 | } | ||||||||
| 4172 | |||||||||
| 4173 | if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && (A == Op0 || B == Op0)) { | ||||||||
| 4174 | // A == (A^B) -> B == 0 | ||||||||
| 4175 | Value *OtherVal = A == Op0 ? B : A; | ||||||||
| 4176 | return new ICmpInst(Pred, OtherVal, Constant::getNullValue(A->getType())); | ||||||||
| 4177 | } | ||||||||
| 4178 | |||||||||
| 4179 | // (X&Z) == (Y&Z) -> (X^Y) & Z == 0 | ||||||||
| 4180 | if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) && | ||||||||
| 4181 | match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) { | ||||||||
| 4182 | Value *X = nullptr, *Y = nullptr, *Z = nullptr; | ||||||||
| 4183 | |||||||||
| 4184 | if (A == C) { | ||||||||
| 4185 | X = B; | ||||||||
| 4186 | Y = D; | ||||||||
| 4187 | Z = A; | ||||||||
| 4188 | } else if (A == D) { | ||||||||
| 4189 | X = B; | ||||||||
| 4190 | Y = C; | ||||||||
| 4191 | Z = A; | ||||||||
| 4192 | } else if (B == C) { | ||||||||
| 4193 | X = A; | ||||||||
| 4194 | Y = D; | ||||||||
| 4195 | Z = B; | ||||||||
| 4196 | } else if (B == D) { | ||||||||
| 4197 | X = A; | ||||||||
| 4198 | Y = C; | ||||||||
| 4199 | Z = B; | ||||||||
| 4200 | } | ||||||||
| 4201 | |||||||||
| 4202 | if (X) { // Build (X^Y) & Z | ||||||||
| 4203 | Op1 = Builder.CreateXor(X, Y); | ||||||||
| 4204 | Op1 = Builder.CreateAnd(Op1, Z); | ||||||||
| 4205 | I.setOperand(0, Op1); | ||||||||
| 4206 | I.setOperand(1, Constant::getNullValue(Op1->getType())); | ||||||||
| 4207 | return &I; | ||||||||
| 4208 | } | ||||||||
| 4209 | } | ||||||||
| 4210 | |||||||||
| 4211 | // Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B) | ||||||||
| 4212 | // and (B & (1<<X)-1) == (zext A) --> A == (trunc B) | ||||||||
| 4213 | ConstantInt *Cst1; | ||||||||
| 4214 | if ((Op0->hasOneUse() && match(Op0, m_ZExt(m_Value(A))) && | ||||||||
| 4215 | match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) || | ||||||||
| 4216 | (Op1->hasOneUse() && match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) && | ||||||||
| 4217 | match(Op1, m_ZExt(m_Value(A))))) { | ||||||||
| 4218 | APInt Pow2 = Cst1->getValue() + 1; | ||||||||
| 4219 | if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) && | ||||||||
| 4220 | Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth()) | ||||||||
| 4221 | return new ICmpInst(Pred, A, Builder.CreateTrunc(B, A->getType())); | ||||||||
| 4222 | } | ||||||||
| 4223 | |||||||||
| 4224 | // (A >> C) == (B >> C) --> (A^B) u< (1 << C) | ||||||||
| 4225 | // For lshr and ashr pairs. | ||||||||
| 4226 | if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_ConstantInt(Cst1)))) && | ||||||||
| 4227 | match(Op1, m_OneUse(m_LShr(m_Value(B), m_Specific(Cst1))))) || | ||||||||
| 4228 | (match(Op0, m_OneUse(m_AShr(m_Value(A), m_ConstantInt(Cst1)))) && | ||||||||
| 4229 | match(Op1, m_OneUse(m_AShr(m_Value(B), m_Specific(Cst1)))))) { | ||||||||
| 4230 | unsigned TypeBits = Cst1->getBitWidth(); | ||||||||
| 4231 | unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits); | ||||||||
| 4232 | if (ShAmt < TypeBits && ShAmt != 0) { | ||||||||
| 4233 | ICmpInst::Predicate NewPred = | ||||||||
| 4234 | Pred == ICmpInst::ICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT; | ||||||||
| 4235 | Value *Xor = Builder.CreateXor(A, B, I.getName() + ".unshifted"); | ||||||||
| 4236 | APInt CmpVal = APInt::getOneBitSet(TypeBits, ShAmt); | ||||||||
| 4237 | return new ICmpInst(NewPred, Xor, Builder.getInt(CmpVal)); | ||||||||
| 4238 | } | ||||||||
| 4239 | } | ||||||||
| 4240 | |||||||||
| 4241 | // (A << C) == (B << C) --> ((A^B) & (~0U >> C)) == 0 | ||||||||
| 4242 | if (match(Op0, m_OneUse(m_Shl(m_Value(A), m_ConstantInt(Cst1)))) && | ||||||||
| 4243 | match(Op1, m_OneUse(m_Shl(m_Value(B), m_Specific(Cst1))))) { | ||||||||
| 4244 | unsigned TypeBits = Cst1->getBitWidth(); | ||||||||
| 4245 | unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits); | ||||||||
| 4246 | if (ShAmt < TypeBits && ShAmt != 0) { | ||||||||
| 4247 | Value *Xor = Builder.CreateXor(A, B, I.getName() + ".unshifted"); | ||||||||
| 4248 | APInt AndVal = APInt::getLowBitsSet(TypeBits, TypeBits - ShAmt); | ||||||||
| 4249 | Value *And = Builder.CreateAnd(Xor, Builder.getInt(AndVal), | ||||||||
| 4250 | I.getName() + ".mask"); | ||||||||
| 4251 | return new ICmpInst(Pred, And, Constant::getNullValue(Cst1->getType())); | ||||||||
| 4252 | } | ||||||||
| 4253 | } | ||||||||
| 4254 | |||||||||
| 4255 | // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to | ||||||||
| 4256 | // "icmp (and X, mask), cst" | ||||||||
| 4257 | uint64_t ShAmt = 0; | ||||||||
| 4258 | if (Op0->hasOneUse() && | ||||||||
| 4259 | match(Op0, m_Trunc(m_OneUse(m_LShr(m_Value(A), m_ConstantInt(ShAmt))))) && | ||||||||
| 4260 | match(Op1, m_ConstantInt(Cst1)) && | ||||||||
| 4261 | // Only do this when A has multiple uses. This is most important to do | ||||||||
| 4262 | // when it exposes other optimizations. | ||||||||
| 4263 | !A->hasOneUse()) { | ||||||||
| 4264 | unsigned ASize = cast<IntegerType>(A->getType())->getPrimitiveSizeInBits(); | ||||||||
| 4265 | |||||||||
| 4266 | if (ShAmt < ASize) { | ||||||||
| 4267 | APInt MaskV = | ||||||||
| 4268 | APInt::getLowBitsSet(ASize, Op0->getType()->getPrimitiveSizeInBits()); | ||||||||
| 4269 | MaskV <<= ShAmt; | ||||||||
| 4270 | |||||||||
| 4271 | APInt CmpV = Cst1->getValue().zext(ASize); | ||||||||
| 4272 | CmpV <<= ShAmt; | ||||||||
| 4273 | |||||||||
| 4274 | Value *Mask = Builder.CreateAnd(A, Builder.getInt(MaskV)); | ||||||||
| 4275 | return new ICmpInst(Pred, Mask, Builder.getInt(CmpV)); | ||||||||
| 4276 | } | ||||||||
| 4277 | } | ||||||||
| 4278 | |||||||||
| 4279 | // If both operands are byte-swapped or bit-reversed, just compare the | ||||||||
| 4280 | // original values. | ||||||||
| 4281 | // TODO: Move this to a function similar to foldICmpIntrinsicWithConstant() | ||||||||
| 4282 | // and handle more intrinsics. | ||||||||
| 4283 | if ((match(Op0, m_BSwap(m_Value(A))) && match(Op1, m_BSwap(m_Value(B)))) || | ||||||||
| 4284 | (match(Op0, m_BitReverse(m_Value(A))) && | ||||||||
| 4285 | match(Op1, m_BitReverse(m_Value(B))))) | ||||||||
| 4286 | return new ICmpInst(Pred, A, B); | ||||||||
| 4287 | |||||||||
| 4288 | // Canonicalize checking for a power-of-2-or-zero value: | ||||||||
| 4289 | // (A & (A-1)) == 0 --> ctpop(A) < 2 (two commuted variants) | ||||||||
| 4290 | // ((A-1) & A) != 0 --> ctpop(A) > 1 (two commuted variants) | ||||||||
| 4291 | if (!match(Op0, m_OneUse(m_c_And(m_Add(m_Value(A), m_AllOnes()), | ||||||||
| 4292 | m_Deferred(A)))) || | ||||||||
| 4293 | !match(Op1, m_ZeroInt())) | ||||||||
| 4294 | A = nullptr; | ||||||||
| 4295 | |||||||||
| 4296 | // (A & -A) == A --> ctpop(A) < 2 (four commuted variants) | ||||||||
| 4297 | // (-A & A) != A --> ctpop(A) > 1 (four commuted variants) | ||||||||
| 4298 | if (match(Op0, m_OneUse(m_c_And(m_Neg(m_Specific(Op1)), m_Specific(Op1))))) | ||||||||
| 4299 | A = Op1; | ||||||||
| 4300 | else if (match(Op1, | ||||||||
| 4301 | m_OneUse(m_c_And(m_Neg(m_Specific(Op0)), m_Specific(Op0))))) | ||||||||
| 4302 | A = Op0; | ||||||||
| 4303 | |||||||||
| 4304 | if (A) { | ||||||||
| 4305 | Type *Ty = A->getType(); | ||||||||
| 4306 | CallInst *CtPop = Builder.CreateUnaryIntrinsic(Intrinsic::ctpop, A); | ||||||||
| 4307 | return Pred == ICmpInst::ICMP_EQ | ||||||||
| 4308 | ? new ICmpInst(ICmpInst::ICMP_ULT, CtPop, ConstantInt::get(Ty, 2)) | ||||||||
| 4309 | : new ICmpInst(ICmpInst::ICMP_UGT, CtPop, ConstantInt::get(Ty, 1)); | ||||||||
| 4310 | } | ||||||||
| 4311 | |||||||||
| 4312 | return nullptr; | ||||||||
| 4313 | } | ||||||||
| 4314 | |||||||||
| 4315 | static Instruction *foldICmpWithZextOrSext(ICmpInst &ICmp, | ||||||||
| 4316 | InstCombiner::BuilderTy &Builder) { | ||||||||
| 4317 | assert(isa<CastInst>(ICmp.getOperand(0)) && "Expected cast for operand 0")((isa<CastInst>(ICmp.getOperand(0)) && "Expected cast for operand 0" ) ? static_cast<void> (0) : __assert_fail ("isa<CastInst>(ICmp.getOperand(0)) && \"Expected cast for operand 0\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4317, __PRETTY_FUNCTION__)); | ||||||||
| 4318 | auto *CastOp0 = cast<CastInst>(ICmp.getOperand(0)); | ||||||||
| 4319 | Value *X; | ||||||||
| 4320 | if (!match(CastOp0, m_ZExtOrSExt(m_Value(X)))) | ||||||||
| 4321 | return nullptr; | ||||||||
| 4322 | |||||||||
| 4323 | bool IsSignedExt = CastOp0->getOpcode() == Instruction::SExt; | ||||||||
| 4324 | bool IsSignedCmp = ICmp.isSigned(); | ||||||||
| 4325 | if (auto *CastOp1 = dyn_cast<CastInst>(ICmp.getOperand(1))) { | ||||||||
| 4326 | // If the signedness of the two casts doesn't agree (i.e. one is a sext | ||||||||
| 4327 | // and the other is a zext), then we can't handle this. | ||||||||
| 4328 | // TODO: This is too strict. We can handle some predicates (equality?). | ||||||||
| 4329 | if (CastOp0->getOpcode() != CastOp1->getOpcode()) | ||||||||
| 4330 | return nullptr; | ||||||||
| 4331 | |||||||||
| 4332 | // Not an extension from the same type? | ||||||||
| 4333 | Value *Y = CastOp1->getOperand(0); | ||||||||
| 4334 | Type *XTy = X->getType(), *YTy = Y->getType(); | ||||||||
| 4335 | if (XTy != YTy) { | ||||||||
| 4336 | // One of the casts must have one use because we are creating a new cast. | ||||||||
| 4337 | if (!CastOp0->hasOneUse() && !CastOp1->hasOneUse()) | ||||||||
| 4338 | return nullptr; | ||||||||
| 4339 | // Extend the narrower operand to the type of the wider operand. | ||||||||
| 4340 | if (XTy->getScalarSizeInBits() < YTy->getScalarSizeInBits()) | ||||||||
| 4341 | X = Builder.CreateCast(CastOp0->getOpcode(), X, YTy); | ||||||||
| 4342 | else if (YTy->getScalarSizeInBits() < XTy->getScalarSizeInBits()) | ||||||||
| 4343 | Y = Builder.CreateCast(CastOp0->getOpcode(), Y, XTy); | ||||||||
| 4344 | else | ||||||||
| 4345 | return nullptr; | ||||||||
| 4346 | } | ||||||||
| 4347 | |||||||||
| 4348 | // (zext X) == (zext Y) --> X == Y | ||||||||
| 4349 | // (sext X) == (sext Y) --> X == Y | ||||||||
| 4350 | if (ICmp.isEquality()) | ||||||||
| 4351 | return new ICmpInst(ICmp.getPredicate(), X, Y); | ||||||||
| 4352 | |||||||||
| 4353 | // A signed comparison of sign extended values simplifies into a | ||||||||
| 4354 | // signed comparison. | ||||||||
| 4355 | if (IsSignedCmp && IsSignedExt) | ||||||||
| 4356 | return new ICmpInst(ICmp.getPredicate(), X, Y); | ||||||||
| 4357 | |||||||||
| 4358 | // The other three cases all fold into an unsigned comparison. | ||||||||
| 4359 | return new ICmpInst(ICmp.getUnsignedPredicate(), X, Y); | ||||||||
| 4360 | } | ||||||||
| 4361 | |||||||||
| 4362 | // Below here, we are only folding a compare with constant. | ||||||||
| 4363 | auto *C = dyn_cast<Constant>(ICmp.getOperand(1)); | ||||||||
| 4364 | if (!C) | ||||||||
| 4365 | return nullptr; | ||||||||
| 4366 | |||||||||
| 4367 | // Compute the constant that would happen if we truncated to SrcTy then | ||||||||
| 4368 | // re-extended to DestTy. | ||||||||
| 4369 | Type *SrcTy = CastOp0->getSrcTy(); | ||||||||
| 4370 | Type *DestTy = CastOp0->getDestTy(); | ||||||||
| 4371 | Constant *Res1 = ConstantExpr::getTrunc(C, SrcTy); | ||||||||
| 4372 | Constant *Res2 = ConstantExpr::getCast(CastOp0->getOpcode(), Res1, DestTy); | ||||||||
| 4373 | |||||||||
| 4374 | // If the re-extended constant didn't change... | ||||||||
| 4375 | if (Res2 == C) { | ||||||||
| 4376 | if (ICmp.isEquality()) | ||||||||
| 4377 | return new ICmpInst(ICmp.getPredicate(), X, Res1); | ||||||||
| 4378 | |||||||||
| 4379 | // A signed comparison of sign extended values simplifies into a | ||||||||
| 4380 | // signed comparison. | ||||||||
| 4381 | if (IsSignedExt && IsSignedCmp) | ||||||||
| 4382 | return new ICmpInst(ICmp.getPredicate(), X, Res1); | ||||||||
| 4383 | |||||||||
| 4384 | // The other three cases all fold into an unsigned comparison. | ||||||||
| 4385 | return new ICmpInst(ICmp.getUnsignedPredicate(), X, Res1); | ||||||||
| 4386 | } | ||||||||
| 4387 | |||||||||
| 4388 | // The re-extended constant changed, partly changed (in the case of a vector), | ||||||||
| 4389 | // or could not be determined to be equal (in the case of a constant | ||||||||
| 4390 | // expression), so the constant cannot be represented in the shorter type. | ||||||||
| 4391 | // All the cases that fold to true or false will have already been handled | ||||||||
| 4392 | // by SimplifyICmpInst, so only deal with the tricky case. | ||||||||
| 4393 | if (IsSignedCmp || !IsSignedExt || !isa<ConstantInt>(C)) | ||||||||
| 4394 | return nullptr; | ||||||||
| 4395 | |||||||||
| 4396 | // Is source op positive? | ||||||||
| 4397 | // icmp ult (sext X), C --> icmp sgt X, -1 | ||||||||
| 4398 | if (ICmp.getPredicate() == ICmpInst::ICMP_ULT) | ||||||||
| 4399 | return new ICmpInst(CmpInst::ICMP_SGT, X, Constant::getAllOnesValue(SrcTy)); | ||||||||
| 4400 | |||||||||
| 4401 | // Is source op negative? | ||||||||
| 4402 | // icmp ugt (sext X), C --> icmp slt X, 0 | ||||||||
| 4403 | 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!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4403, __PRETTY_FUNCTION__)); | ||||||||
| 4404 | return new ICmpInst(CmpInst::ICMP_SLT, X, Constant::getNullValue(SrcTy)); | ||||||||
| 4405 | } | ||||||||
| 4406 | |||||||||
| 4407 | /// Handle icmp (cast x), (cast or constant). | ||||||||
| 4408 | Instruction *InstCombiner::foldICmpWithCastOp(ICmpInst &ICmp) { | ||||||||
| 4409 | auto *CastOp0 = dyn_cast<CastInst>(ICmp.getOperand(0)); | ||||||||
| 4410 | if (!CastOp0) | ||||||||
| 4411 | return nullptr; | ||||||||
| 4412 | if (!isa<Constant>(ICmp.getOperand(1)) && !isa<CastInst>(ICmp.getOperand(1))) | ||||||||
| 4413 | return nullptr; | ||||||||
| 4414 | |||||||||
| 4415 | Value *Op0Src = CastOp0->getOperand(0); | ||||||||
| 4416 | Type *SrcTy = CastOp0->getSrcTy(); | ||||||||
| 4417 | Type *DestTy = CastOp0->getDestTy(); | ||||||||
| 4418 | |||||||||
| 4419 | // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the | ||||||||
| 4420 | // integer type is the same size as the pointer type. | ||||||||
| 4421 | auto CompatibleSizes = [&](Type *SrcTy, Type *DestTy) { | ||||||||
| 4422 | if (isa<VectorType>(SrcTy)) { | ||||||||
| 4423 | SrcTy = cast<VectorType>(SrcTy)->getElementType(); | ||||||||
| 4424 | DestTy = cast<VectorType>(DestTy)->getElementType(); | ||||||||
| 4425 | } | ||||||||
| 4426 | return DL.getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth(); | ||||||||
| 4427 | }; | ||||||||
| 4428 | if (CastOp0->getOpcode() == Instruction::PtrToInt && | ||||||||
| 4429 | CompatibleSizes(SrcTy, DestTy)) { | ||||||||
| 4430 | Value *NewOp1 = nullptr; | ||||||||
| 4431 | if (auto *PtrToIntOp1 = dyn_cast<PtrToIntOperator>(ICmp.getOperand(1))) { | ||||||||
| 4432 | Value *PtrSrc = PtrToIntOp1->getOperand(0); | ||||||||
| 4433 | if (PtrSrc->getType()->getPointerAddressSpace() == | ||||||||
| 4434 | Op0Src->getType()->getPointerAddressSpace()) { | ||||||||
| 4435 | NewOp1 = PtrToIntOp1->getOperand(0); | ||||||||
| 4436 | // If the pointer types don't match, insert a bitcast. | ||||||||
| 4437 | if (Op0Src->getType() != NewOp1->getType()) | ||||||||
| 4438 | NewOp1 = Builder.CreateBitCast(NewOp1, Op0Src->getType()); | ||||||||
| 4439 | } | ||||||||
| 4440 | } else if (auto *RHSC = dyn_cast<Constant>(ICmp.getOperand(1))) { | ||||||||
| 4441 | NewOp1 = ConstantExpr::getIntToPtr(RHSC, SrcTy); | ||||||||
| 4442 | } | ||||||||
| 4443 | |||||||||
| 4444 | if (NewOp1) | ||||||||
| 4445 | return new ICmpInst(ICmp.getPredicate(), Op0Src, NewOp1); | ||||||||
| 4446 | } | ||||||||
| 4447 | |||||||||
| 4448 | return foldICmpWithZextOrSext(ICmp, Builder); | ||||||||
| 4449 | } | ||||||||
| 4450 | |||||||||
| 4451 | static bool isNeutralValue(Instruction::BinaryOps BinaryOp, Value *RHS) { | ||||||||
| 4452 | switch (BinaryOp) { | ||||||||
| 4453 | default: | ||||||||
| 4454 | llvm_unreachable("Unsupported binary op")::llvm::llvm_unreachable_internal("Unsupported binary op", "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4454); | ||||||||
| 4455 | case Instruction::Add: | ||||||||
| 4456 | case Instruction::Sub: | ||||||||
| 4457 | return match(RHS, m_Zero()); | ||||||||
| 4458 | case Instruction::Mul: | ||||||||
| 4459 | return match(RHS, m_One()); | ||||||||
| 4460 | } | ||||||||
| 4461 | } | ||||||||
| 4462 | |||||||||
| 4463 | OverflowResult InstCombiner::computeOverflow( | ||||||||
| 4464 | Instruction::BinaryOps BinaryOp, bool IsSigned, | ||||||||
| 4465 | Value *LHS, Value *RHS, Instruction *CxtI) const { | ||||||||
| 4466 | switch (BinaryOp) { | ||||||||
| 4467 | default: | ||||||||
| 4468 | llvm_unreachable("Unsupported binary op")::llvm::llvm_unreachable_internal("Unsupported binary op", "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4468); | ||||||||
| 4469 | case Instruction::Add: | ||||||||
| 4470 | if (IsSigned) | ||||||||
| 4471 | return computeOverflowForSignedAdd(LHS, RHS, CxtI); | ||||||||
| 4472 | else | ||||||||
| 4473 | return computeOverflowForUnsignedAdd(LHS, RHS, CxtI); | ||||||||
| 4474 | case Instruction::Sub: | ||||||||
| 4475 | if (IsSigned) | ||||||||
| 4476 | return computeOverflowForSignedSub(LHS, RHS, CxtI); | ||||||||
| 4477 | else | ||||||||
| 4478 | return computeOverflowForUnsignedSub(LHS, RHS, CxtI); | ||||||||
| 4479 | case Instruction::Mul: | ||||||||
| 4480 | if (IsSigned) | ||||||||
| 4481 | return computeOverflowForSignedMul(LHS, RHS, CxtI); | ||||||||
| 4482 | else | ||||||||
| 4483 | return computeOverflowForUnsignedMul(LHS, RHS, CxtI); | ||||||||
| 4484 | } | ||||||||
| 4485 | } | ||||||||
| 4486 | |||||||||
| 4487 | bool InstCombiner::OptimizeOverflowCheck( | ||||||||
| 4488 | Instruction::BinaryOps BinaryOp, bool IsSigned, Value *LHS, Value *RHS, | ||||||||
| 4489 | Instruction &OrigI, Value *&Result, Constant *&Overflow) { | ||||||||
| 4490 | if (OrigI.isCommutative() && isa<Constant>(LHS) && !isa<Constant>(RHS)) | ||||||||
| 4491 | std::swap(LHS, RHS); | ||||||||
| 4492 | |||||||||
| 4493 | // If the overflow check was an add followed by a compare, the insertion point | ||||||||
| 4494 | // may be pointing to the compare. We want to insert the new instructions | ||||||||
| 4495 | // before the add in case there are uses of the add between the add and the | ||||||||
| 4496 | // compare. | ||||||||
| 4497 | Builder.SetInsertPoint(&OrigI); | ||||||||
| 4498 | |||||||||
| 4499 | if (isNeutralValue(BinaryOp, RHS)) { | ||||||||
| 4500 | Result = LHS; | ||||||||
| 4501 | Overflow = Builder.getFalse(); | ||||||||
| 4502 | return true; | ||||||||
| 4503 | } | ||||||||
| 4504 | |||||||||
| 4505 | switch (computeOverflow(BinaryOp, IsSigned, LHS, RHS, &OrigI)) { | ||||||||
| 4506 | case OverflowResult::MayOverflow: | ||||||||
| 4507 | return false; | ||||||||
| 4508 | case OverflowResult::AlwaysOverflowsLow: | ||||||||
| 4509 | case OverflowResult::AlwaysOverflowsHigh: | ||||||||
| 4510 | Result = Builder.CreateBinOp(BinaryOp, LHS, RHS); | ||||||||
| 4511 | Result->takeName(&OrigI); | ||||||||
| 4512 | Overflow = Builder.getTrue(); | ||||||||
| 4513 | return true; | ||||||||
| 4514 | case OverflowResult::NeverOverflows: | ||||||||
| 4515 | Result = Builder.CreateBinOp(BinaryOp, LHS, RHS); | ||||||||
| 4516 | Result->takeName(&OrigI); | ||||||||
| 4517 | Overflow = Builder.getFalse(); | ||||||||
| 4518 | if (auto *Inst = dyn_cast<Instruction>(Result)) { | ||||||||
| 4519 | if (IsSigned) | ||||||||
| 4520 | Inst->setHasNoSignedWrap(); | ||||||||
| 4521 | else | ||||||||
| 4522 | Inst->setHasNoUnsignedWrap(); | ||||||||
| 4523 | } | ||||||||
| 4524 | return true; | ||||||||
| 4525 | } | ||||||||
| 4526 | |||||||||
| 4527 | llvm_unreachable("Unexpected overflow result")::llvm::llvm_unreachable_internal("Unexpected overflow result" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4527); | ||||||||
| 4528 | } | ||||||||
| 4529 | |||||||||
| 4530 | /// Recognize and process idiom involving test for multiplication | ||||||||
| 4531 | /// overflow. | ||||||||
| 4532 | /// | ||||||||
| 4533 | /// The caller has matched a pattern of the form: | ||||||||
| 4534 | /// I = cmp u (mul(zext A, zext B), V | ||||||||
| 4535 | /// The function checks if this is a test for overflow and if so replaces | ||||||||
| 4536 | /// multiplication with call to 'mul.with.overflow' intrinsic. | ||||||||
| 4537 | /// | ||||||||
| 4538 | /// \param I Compare instruction. | ||||||||
| 4539 | /// \param MulVal Result of 'mult' instruction. It is one of the arguments of | ||||||||
| 4540 | /// the compare instruction. Must be of integer type. | ||||||||
| 4541 | /// \param OtherVal The other argument of compare instruction. | ||||||||
| 4542 | /// \returns Instruction which must replace the compare instruction, NULL if no | ||||||||
| 4543 | /// replacement required. | ||||||||
| 4544 | static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal, | ||||||||
| 4545 | Value *OtherVal, InstCombiner &IC) { | ||||||||
| 4546 | // Don't bother doing this transformation for pointers, don't do it for | ||||||||
| 4547 | // vectors. | ||||||||
| 4548 | if (!isa<IntegerType>(MulVal->getType())) | ||||||||
| 4549 | return nullptr; | ||||||||
| 4550 | |||||||||
| 4551 | 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" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4551, __PRETTY_FUNCTION__)); | ||||||||
| 4552 | 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" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4552, __PRETTY_FUNCTION__)); | ||||||||
| 4553 | auto *MulInstr = dyn_cast<Instruction>(MulVal); | ||||||||
| 4554 | if (!MulInstr) | ||||||||
| 4555 | return nullptr; | ||||||||
| 4556 | assert(MulInstr->getOpcode() == Instruction::Mul)((MulInstr->getOpcode() == Instruction::Mul) ? static_cast <void> (0) : __assert_fail ("MulInstr->getOpcode() == Instruction::Mul" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4556, __PRETTY_FUNCTION__)); | ||||||||
| 4557 | |||||||||
| 4558 | auto *LHS = cast<ZExtOperator>(MulInstr->getOperand(0)), | ||||||||
| 4559 | *RHS = cast<ZExtOperator>(MulInstr->getOperand(1)); | ||||||||
| 4560 | assert(LHS->getOpcode() == Instruction::ZExt)((LHS->getOpcode() == Instruction::ZExt) ? static_cast< void> (0) : __assert_fail ("LHS->getOpcode() == Instruction::ZExt" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4560, __PRETTY_FUNCTION__)); | ||||||||
| 4561 | assert(RHS->getOpcode() == Instruction::ZExt)((RHS->getOpcode() == Instruction::ZExt) ? static_cast< void> (0) : __assert_fail ("RHS->getOpcode() == Instruction::ZExt" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4561, __PRETTY_FUNCTION__)); | ||||||||
| 4562 | Value *A = LHS->getOperand(0), *B = RHS->getOperand(0); | ||||||||
| 4563 | |||||||||
| 4564 | // Calculate type and width of the result produced by mul.with.overflow. | ||||||||
| 4565 | Type *TyA = A->getType(), *TyB = B->getType(); | ||||||||
| 4566 | unsigned WidthA = TyA->getPrimitiveSizeInBits(), | ||||||||
| 4567 | WidthB = TyB->getPrimitiveSizeInBits(); | ||||||||
| 4568 | unsigned MulWidth; | ||||||||
| 4569 | Type *MulType; | ||||||||
| 4570 | if (WidthB > WidthA) { | ||||||||
| 4571 | MulWidth = WidthB; | ||||||||
| 4572 | MulType = TyB; | ||||||||
| 4573 | } else { | ||||||||
| 4574 | MulWidth = WidthA; | ||||||||
| 4575 | MulType = TyA; | ||||||||
| 4576 | } | ||||||||
| 4577 | |||||||||
| 4578 | // In order to replace the original mul with a narrower mul.with.overflow, | ||||||||
| 4579 | // all uses must ignore upper bits of the product. The number of used low | ||||||||
| 4580 | // bits must be not greater than the width of mul.with.overflow. | ||||||||
| 4581 | if (MulVal->hasNUsesOrMore(2)) | ||||||||
| 4582 | for (User *U : MulVal->users()) { | ||||||||
| 4583 | if (U == &I) | ||||||||
| 4584 | continue; | ||||||||
| 4585 | if (TruncInst *TI = dyn_cast<TruncInst>(U)) { | ||||||||
| 4586 | // Check if truncation ignores bits above MulWidth. | ||||||||
| 4587 | unsigned TruncWidth = TI->getType()->getPrimitiveSizeInBits(); | ||||||||
| 4588 | if (TruncWidth > MulWidth) | ||||||||
| 4589 | return nullptr; | ||||||||
| 4590 | } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) { | ||||||||
| 4591 | // Check if AND ignores bits above MulWidth. | ||||||||
| 4592 | if (BO->getOpcode() != Instruction::And) | ||||||||
| 4593 | return nullptr; | ||||||||
| 4594 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) { | ||||||||
| 4595 | const APInt &CVal = CI->getValue(); | ||||||||
| 4596 | if (CVal.getBitWidth() - CVal.countLeadingZeros() > MulWidth) | ||||||||
| 4597 | return nullptr; | ||||||||
| 4598 | } else { | ||||||||
| 4599 | // In this case we could have the operand of the binary operation | ||||||||
| 4600 | // being defined in another block, and performing the replacement | ||||||||
| 4601 | // could break the dominance relation. | ||||||||
| 4602 | return nullptr; | ||||||||
| 4603 | } | ||||||||
| 4604 | } else { | ||||||||
| 4605 | // Other uses prohibit this transformation. | ||||||||
| 4606 | return nullptr; | ||||||||
| 4607 | } | ||||||||
| 4608 | } | ||||||||
| 4609 | |||||||||
| 4610 | // Recognize patterns | ||||||||
| 4611 | switch (I.getPredicate()) { | ||||||||
| 4612 | case ICmpInst::ICMP_EQ: | ||||||||
| 4613 | case ICmpInst::ICMP_NE: | ||||||||
| 4614 | // Recognize pattern: | ||||||||
| 4615 | // mulval = mul(zext A, zext B) | ||||||||
| 4616 | // cmp eq/neq mulval, zext trunc mulval | ||||||||
| 4617 | if (ZExtInst *Zext = dyn_cast<ZExtInst>(OtherVal)) | ||||||||
| 4618 | if (Zext->hasOneUse()) { | ||||||||
| 4619 | Value *ZextArg = Zext->getOperand(0); | ||||||||
| 4620 | if (TruncInst *Trunc = dyn_cast<TruncInst>(ZextArg)) | ||||||||
| 4621 | if (Trunc->getType()->getPrimitiveSizeInBits() == MulWidth) | ||||||||
| 4622 | break; //Recognized | ||||||||
| 4623 | } | ||||||||
| 4624 | |||||||||
| 4625 | // Recognize pattern: | ||||||||
| 4626 | // mulval = mul(zext A, zext B) | ||||||||
| 4627 | // cmp eq/neq mulval, and(mulval, mask), mask selects low MulWidth bits. | ||||||||
| 4628 | ConstantInt *CI; | ||||||||
| 4629 | Value *ValToMask; | ||||||||
| 4630 | if (match(OtherVal, m_And(m_Value(ValToMask), m_ConstantInt(CI)))) { | ||||||||
| 4631 | if (ValToMask != MulVal) | ||||||||
| 4632 | return nullptr; | ||||||||
| 4633 | const APInt &CVal = CI->getValue() + 1; | ||||||||
| 4634 | if (CVal.isPowerOf2()) { | ||||||||
| 4635 | unsigned MaskWidth = CVal.logBase2(); | ||||||||
| 4636 | if (MaskWidth == MulWidth) | ||||||||
| 4637 | break; // Recognized | ||||||||
| 4638 | } | ||||||||
| 4639 | } | ||||||||
| 4640 | return nullptr; | ||||||||
| 4641 | |||||||||
| 4642 | case ICmpInst::ICMP_UGT: | ||||||||
| 4643 | // Recognize pattern: | ||||||||
| 4644 | // mulval = mul(zext A, zext B) | ||||||||
| 4645 | // cmp ugt mulval, max | ||||||||
| 4646 | if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) { | ||||||||
| 4647 | APInt MaxVal = APInt::getMaxValue(MulWidth); | ||||||||
| 4648 | MaxVal = MaxVal.zext(CI->getBitWidth()); | ||||||||
| 4649 | if (MaxVal.eq(CI->getValue())) | ||||||||
| 4650 | break; // Recognized | ||||||||
| 4651 | } | ||||||||
| 4652 | return nullptr; | ||||||||
| 4653 | |||||||||
| 4654 | case ICmpInst::ICMP_UGE: | ||||||||
| 4655 | // Recognize pattern: | ||||||||
| 4656 | // mulval = mul(zext A, zext B) | ||||||||
| 4657 | // cmp uge mulval, max+1 | ||||||||
| 4658 | if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) { | ||||||||
| 4659 | APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth); | ||||||||
| 4660 | if (MaxVal.eq(CI->getValue())) | ||||||||
| 4661 | break; // Recognized | ||||||||
| 4662 | } | ||||||||
| 4663 | return nullptr; | ||||||||
| 4664 | |||||||||
| 4665 | case ICmpInst::ICMP_ULE: | ||||||||
| 4666 | // Recognize pattern: | ||||||||
| 4667 | // mulval = mul(zext A, zext B) | ||||||||
| 4668 | // cmp ule mulval, max | ||||||||
| 4669 | if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) { | ||||||||
| 4670 | APInt MaxVal = APInt::getMaxValue(MulWidth); | ||||||||
| 4671 | MaxVal = MaxVal.zext(CI->getBitWidth()); | ||||||||
| 4672 | if (MaxVal.eq(CI->getValue())) | ||||||||
| 4673 | break; // Recognized | ||||||||
| 4674 | } | ||||||||
| 4675 | return nullptr; | ||||||||
| 4676 | |||||||||
| 4677 | case ICmpInst::ICMP_ULT: | ||||||||
| 4678 | // Recognize pattern: | ||||||||
| 4679 | // mulval = mul(zext A, zext B) | ||||||||
| 4680 | // cmp ule mulval, max + 1 | ||||||||
| 4681 | if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) { | ||||||||
| 4682 | APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth); | ||||||||
| 4683 | if (MaxVal.eq(CI->getValue())) | ||||||||
| 4684 | break; // Recognized | ||||||||
| 4685 | } | ||||||||
| 4686 | return nullptr; | ||||||||
| 4687 | |||||||||
| 4688 | default: | ||||||||
| 4689 | return nullptr; | ||||||||
| 4690 | } | ||||||||
| 4691 | |||||||||
| 4692 | InstCombiner::BuilderTy &Builder = IC.Builder; | ||||||||
| 4693 | Builder.SetInsertPoint(MulInstr); | ||||||||
| 4694 | |||||||||
| 4695 | // Replace: mul(zext A, zext B) --> mul.with.overflow(A, B) | ||||||||
| 4696 | Value *MulA = A, *MulB = B; | ||||||||
| 4697 | if (WidthA < MulWidth) | ||||||||
| 4698 | MulA = Builder.CreateZExt(A, MulType); | ||||||||
| 4699 | if (WidthB < MulWidth) | ||||||||
| 4700 | MulB = Builder.CreateZExt(B, MulType); | ||||||||
| 4701 | Function *F = Intrinsic::getDeclaration( | ||||||||
| 4702 | I.getModule(), Intrinsic::umul_with_overflow, MulType); | ||||||||
| 4703 | CallInst *Call = Builder.CreateCall(F, {MulA, MulB}, "umul"); | ||||||||
| 4704 | IC.Worklist.Add(MulInstr); | ||||||||
| 4705 | |||||||||
| 4706 | // If there are uses of mul result other than the comparison, we know that | ||||||||
| 4707 | // they are truncation or binary AND. Change them to use result of | ||||||||
| 4708 | // mul.with.overflow and adjust properly mask/size. | ||||||||
| 4709 | if (MulVal->hasNUsesOrMore(2)) { | ||||||||
| 4710 | Value *Mul = Builder.CreateExtractValue(Call, 0, "umul.value"); | ||||||||
| 4711 | for (auto UI = MulVal->user_begin(), UE = MulVal->user_end(); UI != UE;) { | ||||||||
| 4712 | User *U = *UI++; | ||||||||
| 4713 | if (U == &I || U == OtherVal) | ||||||||
| 4714 | continue; | ||||||||
| 4715 | if (TruncInst *TI = dyn_cast<TruncInst>(U)) { | ||||||||
| 4716 | if (TI->getType()->getPrimitiveSizeInBits() == MulWidth) | ||||||||
| 4717 | IC.replaceInstUsesWith(*TI, Mul); | ||||||||
| 4718 | else | ||||||||
| 4719 | TI->setOperand(0, Mul); | ||||||||
| 4720 | } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) { | ||||||||
| 4721 | assert(BO->getOpcode() == Instruction::And)((BO->getOpcode() == Instruction::And) ? static_cast<void > (0) : __assert_fail ("BO->getOpcode() == Instruction::And" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4721, __PRETTY_FUNCTION__)); | ||||||||
| 4722 | // Replace (mul & mask) --> zext (mul.with.overflow & short_mask) | ||||||||
| 4723 | ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1)); | ||||||||
| 4724 | APInt ShortMask = CI->getValue().trunc(MulWidth); | ||||||||
| 4725 | Value *ShortAnd = Builder.CreateAnd(Mul, ShortMask); | ||||||||
| 4726 | Instruction *Zext = | ||||||||
| 4727 | cast<Instruction>(Builder.CreateZExt(ShortAnd, BO->getType())); | ||||||||
| 4728 | IC.Worklist.Add(Zext); | ||||||||
| 4729 | IC.replaceInstUsesWith(*BO, Zext); | ||||||||
| 4730 | } else { | ||||||||
| 4731 | llvm_unreachable("Unexpected Binary operation")::llvm::llvm_unreachable_internal("Unexpected Binary operation" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4731); | ||||||||
| 4732 | } | ||||||||
| 4733 | IC.Worklist.Add(cast<Instruction>(U)); | ||||||||
| 4734 | } | ||||||||
| 4735 | } | ||||||||
| 4736 | if (isa<Instruction>(OtherVal)) | ||||||||
| 4737 | IC.Worklist.Add(cast<Instruction>(OtherVal)); | ||||||||
| 4738 | |||||||||
| 4739 | // The original icmp gets replaced with the overflow value, maybe inverted | ||||||||
| 4740 | // depending on predicate. | ||||||||
| 4741 | bool Inverse = false; | ||||||||
| 4742 | switch (I.getPredicate()) { | ||||||||
| 4743 | case ICmpInst::ICMP_NE: | ||||||||
| 4744 | break; | ||||||||
| 4745 | case ICmpInst::ICMP_EQ: | ||||||||
| 4746 | Inverse = true; | ||||||||
| 4747 | break; | ||||||||
| 4748 | case ICmpInst::ICMP_UGT: | ||||||||
| 4749 | case ICmpInst::ICMP_UGE: | ||||||||
| 4750 | if (I.getOperand(0) == MulVal) | ||||||||
| 4751 | break; | ||||||||
| 4752 | Inverse = true; | ||||||||
| 4753 | break; | ||||||||
| 4754 | case ICmpInst::ICMP_ULT: | ||||||||
| 4755 | case ICmpInst::ICMP_ULE: | ||||||||
| 4756 | if (I.getOperand(1) == MulVal) | ||||||||
| 4757 | break; | ||||||||
| 4758 | Inverse = true; | ||||||||
| 4759 | break; | ||||||||
| 4760 | default: | ||||||||
| 4761 | llvm_unreachable("Unexpected predicate")::llvm::llvm_unreachable_internal("Unexpected predicate", "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4761); | ||||||||
| 4762 | } | ||||||||
| 4763 | if (Inverse) { | ||||||||
| 4764 | Value *Res = Builder.CreateExtractValue(Call, 1); | ||||||||
| 4765 | return BinaryOperator::CreateNot(Res); | ||||||||
| 4766 | } | ||||||||
| 4767 | |||||||||
| 4768 | return ExtractValueInst::Create(Call, 1); | ||||||||
| 4769 | } | ||||||||
| 4770 | |||||||||
| 4771 | /// When performing a comparison against a constant, it is possible that not all | ||||||||
| 4772 | /// the bits in the LHS are demanded. This helper method computes the mask that | ||||||||
| 4773 | /// IS demanded. | ||||||||
| 4774 | static APInt getDemandedBitsLHSMask(ICmpInst &I, unsigned BitWidth) { | ||||||||
| 4775 | const APInt *RHS; | ||||||||
| 4776 | if (!match(I.getOperand(1), m_APInt(RHS))) | ||||||||
| 4777 | return APInt::getAllOnesValue(BitWidth); | ||||||||
| 4778 | |||||||||
| 4779 | // If this is a normal comparison, it demands all bits. If it is a sign bit | ||||||||
| 4780 | // comparison, it only demands the sign bit. | ||||||||
| 4781 | bool UnusedBit; | ||||||||
| 4782 | if (isSignBitCheck(I.getPredicate(), *RHS, UnusedBit)) | ||||||||
| 4783 | return APInt::getSignMask(BitWidth); | ||||||||
| 4784 | |||||||||
| 4785 | switch (I.getPredicate()) { | ||||||||
| 4786 | // For a UGT comparison, we don't care about any bits that | ||||||||
| 4787 | // correspond to the trailing ones of the comparand. The value of these | ||||||||
| 4788 | // bits doesn't impact the outcome of the comparison, because any value | ||||||||
| 4789 | // greater than the RHS must differ in a bit higher than these due to carry. | ||||||||
| 4790 | case ICmpInst::ICMP_UGT: | ||||||||
| 4791 | return APInt::getBitsSetFrom(BitWidth, RHS->countTrailingOnes()); | ||||||||
| 4792 | |||||||||
| 4793 | // Similarly, for a ULT comparison, we don't care about the trailing zeros. | ||||||||
| 4794 | // Any value less than the RHS must differ in a higher bit because of carries. | ||||||||
| 4795 | case ICmpInst::ICMP_ULT: | ||||||||
| 4796 | return APInt::getBitsSetFrom(BitWidth, RHS->countTrailingZeros()); | ||||||||
| 4797 | |||||||||
| 4798 | default: | ||||||||
| 4799 | return APInt::getAllOnesValue(BitWidth); | ||||||||
| 4800 | } | ||||||||
| 4801 | } | ||||||||
| 4802 | |||||||||
| 4803 | /// Check if the order of \p Op0 and \p Op1 as operands in an ICmpInst | ||||||||
| 4804 | /// should be swapped. | ||||||||
| 4805 | /// The decision is based on how many times these two operands are reused | ||||||||
| 4806 | /// as subtract operands and their positions in those instructions. | ||||||||
| 4807 | /// The rationale is that several architectures use the same instruction for | ||||||||
| 4808 | /// both subtract and cmp. Thus, it is better if the order of those operands | ||||||||
| 4809 | /// match. | ||||||||
| 4810 | /// \return true if Op0 and Op1 should be swapped. | ||||||||
| 4811 | static bool swapMayExposeCSEOpportunities(const Value *Op0, const Value *Op1) { | ||||||||
| 4812 | // Filter out pointer values as those cannot appear directly in subtract. | ||||||||
| 4813 | // FIXME: we may want to go through inttoptrs or bitcasts. | ||||||||
| 4814 | if (Op0->getType()->isPointerTy()) | ||||||||
| 4815 | return false; | ||||||||
| 4816 | // If a subtract already has the same operands as a compare, swapping would be | ||||||||
| 4817 | // bad. If a subtract has the same operands as a compare but in reverse order, | ||||||||
| 4818 | // then swapping is good. | ||||||||
| 4819 | int GoodToSwap = 0; | ||||||||
| 4820 | for (const User *U : Op0->users()) { | ||||||||
| 4821 | if (match(U, m_Sub(m_Specific(Op1), m_Specific(Op0)))) | ||||||||
| 4822 | GoodToSwap++; | ||||||||
| 4823 | else if (match(U, m_Sub(m_Specific(Op0), m_Specific(Op1)))) | ||||||||
| 4824 | GoodToSwap--; | ||||||||
| 4825 | } | ||||||||
| 4826 | return GoodToSwap > 0; | ||||||||
| 4827 | } | ||||||||
| 4828 | |||||||||
| 4829 | /// Check that one use is in the same block as the definition and all | ||||||||
| 4830 | /// other uses are in blocks dominated by a given block. | ||||||||
| 4831 | /// | ||||||||
| 4832 | /// \param DI Definition | ||||||||
| 4833 | /// \param UI Use | ||||||||
| 4834 | /// \param DB Block that must dominate all uses of \p DI outside | ||||||||
| 4835 | /// the parent block | ||||||||
| 4836 | /// \return true when \p UI is the only use of \p DI in the parent block | ||||||||
| 4837 | /// and all other uses of \p DI are in blocks dominated by \p DB. | ||||||||
| 4838 | /// | ||||||||
| 4839 | bool InstCombiner::dominatesAllUses(const Instruction *DI, | ||||||||
| 4840 | const Instruction *UI, | ||||||||
| 4841 | const BasicBlock *DB) const { | ||||||||
| 4842 | 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\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4842, __PRETTY_FUNCTION__)); | ||||||||
| 4843 | // Ignore incomplete definitions. | ||||||||
| 4844 | if (!DI->getParent()) | ||||||||
| 4845 | return false; | ||||||||
| 4846 | // DI and UI must be in the same block. | ||||||||
| 4847 | if (DI->getParent() != UI->getParent()) | ||||||||
| 4848 | return false; | ||||||||
| 4849 | // Protect from self-referencing blocks. | ||||||||
| 4850 | if (DI->getParent() == DB) | ||||||||
| 4851 | return false; | ||||||||
| 4852 | for (const User *U : DI->users()) { | ||||||||
| 4853 | auto *Usr = cast<Instruction>(U); | ||||||||
| 4854 | if (Usr != UI && !DT.dominates(DB, Usr->getParent())) | ||||||||
| 4855 | return false; | ||||||||
| 4856 | } | ||||||||
| 4857 | return true; | ||||||||
| 4858 | } | ||||||||
| 4859 | |||||||||
| 4860 | /// Return true when the instruction sequence within a block is select-cmp-br. | ||||||||
| 4861 | static bool isChainSelectCmpBranch(const SelectInst *SI) { | ||||||||
| 4862 | const BasicBlock *BB = SI->getParent(); | ||||||||
| 4863 | if (!BB) | ||||||||
| 4864 | return false; | ||||||||
| 4865 | auto *BI = dyn_cast_or_null<BranchInst>(BB->getTerminator()); | ||||||||
| 4866 | if (!BI || BI->getNumSuccessors() != 2) | ||||||||
| 4867 | return false; | ||||||||
| 4868 | auto *IC = dyn_cast<ICmpInst>(BI->getCondition()); | ||||||||
| 4869 | if (!IC || (IC->getOperand(0) != SI && IC->getOperand(1) != SI)) | ||||||||
| 4870 | return false; | ||||||||
| 4871 | return true; | ||||||||
| 4872 | } | ||||||||
| 4873 | |||||||||
| 4874 | /// True when a select result is replaced by one of its operands | ||||||||
| 4875 | /// in select-icmp sequence. This will eventually result in the elimination | ||||||||
| 4876 | /// of the select. | ||||||||
| 4877 | /// | ||||||||
| 4878 | /// \param SI Select instruction | ||||||||
| 4879 | /// \param Icmp Compare instruction | ||||||||
| 4880 | /// \param SIOpd Operand that replaces the select | ||||||||
| 4881 | /// | ||||||||
| 4882 | /// Notes: | ||||||||
| 4883 | /// - The replacement is global and requires dominator information | ||||||||
| 4884 | /// - The caller is responsible for the actual replacement | ||||||||
| 4885 | /// | ||||||||
| 4886 | /// Example: | ||||||||
| 4887 | /// | ||||||||
| 4888 | /// entry: | ||||||||
| 4889 | /// %4 = select i1 %3, %C* %0, %C* null | ||||||||
| 4890 | /// %5 = icmp eq %C* %4, null | ||||||||
| 4891 | /// br i1 %5, label %9, label %7 | ||||||||
| 4892 | /// ... | ||||||||
| 4893 | /// ; <label>:7 ; preds = %entry | ||||||||
| 4894 | /// %8 = getelementptr inbounds %C* %4, i64 0, i32 0 | ||||||||
| 4895 | /// ... | ||||||||
| 4896 | /// | ||||||||
| 4897 | /// can be transformed to | ||||||||
| 4898 | /// | ||||||||
| 4899 | /// %5 = icmp eq %C* %0, null | ||||||||
| 4900 | /// %6 = select i1 %3, i1 %5, i1 true | ||||||||
| 4901 | /// br i1 %6, label %9, label %7 | ||||||||
| 4902 | /// ... | ||||||||
| 4903 | /// ; <label>:7 ; preds = %entry | ||||||||
| 4904 | /// %8 = getelementptr inbounds %C* %0, i64 0, i32 0 // replace by %0! | ||||||||
| 4905 | /// | ||||||||
| 4906 | /// Similar when the first operand of the select is a constant or/and | ||||||||
| 4907 | /// the compare is for not equal rather than equal. | ||||||||
| 4908 | /// | ||||||||
| 4909 | /// NOTE: The function is only called when the select and compare constants | ||||||||
| 4910 | /// are equal, the optimization can work only for EQ predicates. This is not a | ||||||||
| 4911 | /// major restriction since a NE compare should be 'normalized' to an equal | ||||||||
| 4912 | /// compare, which usually happens in the combiner and test case | ||||||||
| 4913 | /// select-cmp-br.ll checks for it. | ||||||||
| 4914 | bool InstCombiner::replacedSelectWithOperand(SelectInst *SI, | ||||||||
| 4915 | const ICmpInst *Icmp, | ||||||||
| 4916 | const unsigned SIOpd) { | ||||||||
| 4917 | 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!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4917, __PRETTY_FUNCTION__)); | ||||||||
| 4918 | if (isChainSelectCmpBranch(SI) && Icmp->getPredicate() == ICmpInst::ICMP_EQ) { | ||||||||
| 4919 | BasicBlock *Succ = SI->getParent()->getTerminator()->getSuccessor(1); | ||||||||
| 4920 | // The check for the single predecessor is not the best that can be | ||||||||
| 4921 | // done. But it protects efficiently against cases like when SI's | ||||||||
| 4922 | // home block has two successors, Succ and Succ1, and Succ1 predecessor | ||||||||
| 4923 | // of Succ. Then SI can't be replaced by SIOpd because the use that gets | ||||||||
| 4924 | // replaced can be reached on either path. So the uniqueness check | ||||||||
| 4925 | // guarantees that the path all uses of SI (outside SI's parent) are on | ||||||||
| 4926 | // is disjoint from all other paths out of SI. But that information | ||||||||
| 4927 | // is more expensive to compute, and the trade-off here is in favor | ||||||||
| 4928 | // of compile-time. It should also be noticed that we check for a single | ||||||||
| 4929 | // predecessor and not only uniqueness. This to handle the situation when | ||||||||
| 4930 | // Succ and Succ1 points to the same basic block. | ||||||||
| 4931 | if (Succ->getSinglePredecessor() && dominatesAllUses(SI, Icmp, Succ)) { | ||||||||
| 4932 | NumSel++; | ||||||||
| 4933 | SI->replaceUsesOutsideBlock(SI->getOperand(SIOpd), SI->getParent()); | ||||||||
| 4934 | return true; | ||||||||
| 4935 | } | ||||||||
| 4936 | } | ||||||||
| 4937 | return false; | ||||||||
| 4938 | } | ||||||||
| 4939 | |||||||||
| 4940 | /// Try to fold the comparison based on range information we can get by checking | ||||||||
| 4941 | /// whether bits are known to be zero or one in the inputs. | ||||||||
| 4942 | Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) { | ||||||||
| 4943 | Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); | ||||||||
| 4944 | Type *Ty = Op0->getType(); | ||||||||
| 4945 | ICmpInst::Predicate Pred = I.getPredicate(); | ||||||||
| 4946 | |||||||||
| 4947 | // Get scalar or pointer size. | ||||||||
| 4948 | unsigned BitWidth = Ty->isIntOrIntVectorTy() | ||||||||
| 4949 | ? Ty->getScalarSizeInBits() | ||||||||
| 4950 | : DL.getPointerTypeSizeInBits(Ty->getScalarType()); | ||||||||
| 4951 | |||||||||
| 4952 | if (!BitWidth) | ||||||||
| 4953 | return nullptr; | ||||||||
| 4954 | |||||||||
| 4955 | KnownBits Op0Known(BitWidth); | ||||||||
| 4956 | KnownBits Op1Known(BitWidth); | ||||||||
| 4957 | |||||||||
| 4958 | if (SimplifyDemandedBits(&I, 0, | ||||||||
| 4959 | getDemandedBitsLHSMask(I, BitWidth), | ||||||||
| 4960 | Op0Known, 0)) | ||||||||
| 4961 | return &I; | ||||||||
| 4962 | |||||||||
| 4963 | if (SimplifyDemandedBits(&I, 1, APInt::getAllOnesValue(BitWidth), | ||||||||
| 4964 | Op1Known, 0)) | ||||||||
| 4965 | return &I; | ||||||||
| 4966 | |||||||||
| 4967 | // Given the known and unknown bits, compute a range that the LHS could be | ||||||||
| 4968 | // in. Compute the Min, Max and RHS values based on the known bits. For the | ||||||||
| 4969 | // EQ and NE we use unsigned values. | ||||||||
| 4970 | APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0); | ||||||||
| 4971 | APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0); | ||||||||
| 4972 | if (I.isSigned()) { | ||||||||
| 4973 | computeSignedMinMaxValuesFromKnownBits(Op0Known, Op0Min, Op0Max); | ||||||||
| 4974 | computeSignedMinMaxValuesFromKnownBits(Op1Known, Op1Min, Op1Max); | ||||||||
| 4975 | } else { | ||||||||
| 4976 | computeUnsignedMinMaxValuesFromKnownBits(Op0Known, Op0Min, Op0Max); | ||||||||
| 4977 | computeUnsignedMinMaxValuesFromKnownBits(Op1Known, Op1Min, Op1Max); | ||||||||
| 4978 | } | ||||||||
| 4979 | |||||||||
| 4980 | // If Min and Max are known to be the same, then SimplifyDemandedBits figured | ||||||||
| 4981 | // out that the LHS or RHS is a constant. Constant fold this now, so that | ||||||||
| 4982 | // code below can assume that Min != Max. | ||||||||
| 4983 | if (!isa<Constant>(Op0) && Op0Min == Op0Max) | ||||||||
| 4984 | return new ICmpInst(Pred, ConstantExpr::getIntegerValue(Ty, Op0Min), Op1); | ||||||||
| 4985 | if (!isa<Constant>(Op1) && Op1Min == Op1Max) | ||||||||
| 4986 | return new ICmpInst(Pred, Op0, ConstantExpr::getIntegerValue(Ty, Op1Min)); | ||||||||
| 4987 | |||||||||
| 4988 | // Based on the range information we know about the LHS, see if we can | ||||||||
| 4989 | // simplify this comparison. For example, (x&4) < 8 is always true. | ||||||||
| 4990 | switch (Pred) { | ||||||||
| 4991 | default: | ||||||||
| 4992 | llvm_unreachable("Unknown icmp opcode!")::llvm::llvm_unreachable_internal("Unknown icmp opcode!", "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 4992); | ||||||||
| 4993 | case ICmpInst::ICMP_EQ: | ||||||||
| 4994 | case ICmpInst::ICMP_NE: { | ||||||||
| 4995 | if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) { | ||||||||
| 4996 | return Pred == CmpInst::ICMP_EQ | ||||||||
| 4997 | ? replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())) | ||||||||
| 4998 | : replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 4999 | } | ||||||||
| 5000 | |||||||||
| 5001 | // If all bits are known zero except for one, then we know at most one bit | ||||||||
| 5002 | // is set. If the comparison is against zero, then this is a check to see if | ||||||||
| 5003 | // *that* bit is set. | ||||||||
| 5004 | APInt Op0KnownZeroInverted = ~Op0Known.Zero; | ||||||||
| 5005 | if (Op1Known.isZero()) { | ||||||||
| 5006 | // If the LHS is an AND with the same constant, look through it. | ||||||||
| 5007 | Value *LHS = nullptr; | ||||||||
| 5008 | const APInt *LHSC; | ||||||||
| 5009 | if (!match(Op0, m_And(m_Value(LHS), m_APInt(LHSC))) || | ||||||||
| 5010 | *LHSC != Op0KnownZeroInverted) | ||||||||
| 5011 | LHS = Op0; | ||||||||
| 5012 | |||||||||
| 5013 | Value *X; | ||||||||
| 5014 | if (match(LHS, m_Shl(m_One(), m_Value(X)))) { | ||||||||
| 5015 | APInt ValToCheck = Op0KnownZeroInverted; | ||||||||
| 5016 | Type *XTy = X->getType(); | ||||||||
| 5017 | if (ValToCheck.isPowerOf2()) { | ||||||||
| 5018 | // ((1 << X) & 8) == 0 -> X != 3 | ||||||||
| 5019 | // ((1 << X) & 8) != 0 -> X == 3 | ||||||||
| 5020 | auto *CmpC = ConstantInt::get(XTy, ValToCheck.countTrailingZeros()); | ||||||||
| 5021 | auto NewPred = ICmpInst::getInversePredicate(Pred); | ||||||||
| 5022 | return new ICmpInst(NewPred, X, CmpC); | ||||||||
| 5023 | } else if ((++ValToCheck).isPowerOf2()) { | ||||||||
| 5024 | // ((1 << X) & 7) == 0 -> X >= 3 | ||||||||
| 5025 | // ((1 << X) & 7) != 0 -> X < 3 | ||||||||
| 5026 | auto *CmpC = ConstantInt::get(XTy, ValToCheck.countTrailingZeros()); | ||||||||
| 5027 | auto NewPred = | ||||||||
| 5028 | Pred == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGE : CmpInst::ICMP_ULT; | ||||||||
| 5029 | return new ICmpInst(NewPred, X, CmpC); | ||||||||
| 5030 | } | ||||||||
| 5031 | } | ||||||||
| 5032 | |||||||||
| 5033 | // Check if the LHS is 8 >>u x and the result is a power of 2 like 1. | ||||||||
| 5034 | const APInt *CI; | ||||||||
| 5035 | if (Op0KnownZeroInverted.isOneValue() && | ||||||||
| 5036 | match(LHS, m_LShr(m_Power2(CI), m_Value(X)))) { | ||||||||
| 5037 | // ((8 >>u X) & 1) == 0 -> X != 3 | ||||||||
| 5038 | // ((8 >>u X) & 1) != 0 -> X == 3 | ||||||||
| 5039 | unsigned CmpVal = CI->countTrailingZeros(); | ||||||||
| 5040 | auto NewPred = ICmpInst::getInversePredicate(Pred); | ||||||||
| 5041 | return new ICmpInst(NewPred, X, ConstantInt::get(X->getType(), CmpVal)); | ||||||||
| 5042 | } | ||||||||
| 5043 | } | ||||||||
| 5044 | break; | ||||||||
| 5045 | } | ||||||||
| 5046 | case ICmpInst::ICMP_ULT: { | ||||||||
| 5047 | if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B) | ||||||||
| 5048 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 5049 | if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B) | ||||||||
| 5050 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 5051 | if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B) | ||||||||
| 5052 | return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); | ||||||||
| 5053 | |||||||||
| 5054 | const APInt *CmpC; | ||||||||
| 5055 | if (match(Op1, m_APInt(CmpC))) { | ||||||||
| 5056 | // A <u C -> A == C-1 if min(A)+1 == C | ||||||||
| 5057 | if (*CmpC == Op0Min + 1) | ||||||||
| 5058 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, | ||||||||
| 5059 | ConstantInt::get(Op1->getType(), *CmpC - 1)); | ||||||||
| 5060 | // X <u C --> X == 0, if the number of zero bits in the bottom of X | ||||||||
| 5061 | // exceeds the log2 of C. | ||||||||
| 5062 | if (Op0Known.countMinTrailingZeros() >= CmpC->ceilLogBase2()) | ||||||||
| 5063 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, | ||||||||
| 5064 | Constant::getNullValue(Op1->getType())); | ||||||||
| 5065 | } | ||||||||
| 5066 | break; | ||||||||
| 5067 | } | ||||||||
| 5068 | case ICmpInst::ICMP_UGT: { | ||||||||
| 5069 | if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B) | ||||||||
| 5070 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 5071 | if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B) | ||||||||
| 5072 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 5073 | if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B) | ||||||||
| 5074 | return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); | ||||||||
| 5075 | |||||||||
| 5076 | const APInt *CmpC; | ||||||||
| 5077 | if (match(Op1, m_APInt(CmpC))) { | ||||||||
| 5078 | // A >u C -> A == C+1 if max(a)-1 == C | ||||||||
| 5079 | if (*CmpC == Op0Max - 1) | ||||||||
| 5080 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, | ||||||||
| 5081 | ConstantInt::get(Op1->getType(), *CmpC + 1)); | ||||||||
| 5082 | // X >u C --> X != 0, if the number of zero bits in the bottom of X | ||||||||
| 5083 | // exceeds the log2 of C. | ||||||||
| 5084 | if (Op0Known.countMinTrailingZeros() >= CmpC->getActiveBits()) | ||||||||
| 5085 | return new ICmpInst(ICmpInst::ICMP_NE, Op0, | ||||||||
| 5086 | Constant::getNullValue(Op1->getType())); | ||||||||
| 5087 | } | ||||||||
| 5088 | break; | ||||||||
| 5089 | } | ||||||||
| 5090 | case ICmpInst::ICMP_SLT: { | ||||||||
| 5091 | if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C) | ||||||||
| 5092 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 5093 | if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C) | ||||||||
| 5094 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 5095 | if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B) | ||||||||
| 5096 | return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); | ||||||||
| 5097 | const APInt *CmpC; | ||||||||
| 5098 | if (match(Op1, m_APInt(CmpC))) { | ||||||||
| 5099 | if (*CmpC == Op0Min + 1) // A <s C -> A == C-1 if min(A)+1 == C | ||||||||
| 5100 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, | ||||||||
| 5101 | ConstantInt::get(Op1->getType(), *CmpC - 1)); | ||||||||
| 5102 | } | ||||||||
| 5103 | break; | ||||||||
| 5104 | } | ||||||||
| 5105 | case ICmpInst::ICMP_SGT: { | ||||||||
| 5106 | if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B) | ||||||||
| 5107 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 5108 | if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B) | ||||||||
| 5109 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 5110 | if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B) | ||||||||
| 5111 | return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); | ||||||||
| 5112 | const APInt *CmpC; | ||||||||
| 5113 | if (match(Op1, m_APInt(CmpC))) { | ||||||||
| 5114 | if (*CmpC == Op0Max - 1) // A >s C -> A == C+1 if max(A)-1 == C | ||||||||
| 5115 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, | ||||||||
| 5116 | ConstantInt::get(Op1->getType(), *CmpC + 1)); | ||||||||
| 5117 | } | ||||||||
| 5118 | break; | ||||||||
| 5119 | } | ||||||||
| 5120 | case ICmpInst::ICMP_SGE: | ||||||||
| 5121 | 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!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5121, __PRETTY_FUNCTION__)); | ||||||||
| 5122 | if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B) | ||||||||
| 5123 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 5124 | if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B) | ||||||||
| 5125 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 5126 | if (Op1Min == Op0Max) // A >=s B -> A == B if max(A) == min(B) | ||||||||
| 5127 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1); | ||||||||
| 5128 | break; | ||||||||
| 5129 | case ICmpInst::ICMP_SLE: | ||||||||
| 5130 | 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!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5130, __PRETTY_FUNCTION__)); | ||||||||
| 5131 | if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B) | ||||||||
| 5132 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 5133 | if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B) | ||||||||
| 5134 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 5135 | if (Op1Max == Op0Min) // A <=s B -> A == B if min(A) == max(B) | ||||||||
| 5136 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1); | ||||||||
| 5137 | break; | ||||||||
| 5138 | case ICmpInst::ICMP_UGE: | ||||||||
| 5139 | 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!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5139, __PRETTY_FUNCTION__)); | ||||||||
| 5140 | if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B) | ||||||||
| 5141 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 5142 | if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B) | ||||||||
| 5143 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 5144 | if (Op1Min == Op0Max) // A >=u B -> A == B if max(A) == min(B) | ||||||||
| 5145 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1); | ||||||||
| 5146 | break; | ||||||||
| 5147 | case ICmpInst::ICMP_ULE: | ||||||||
| 5148 | 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!\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5148, __PRETTY_FUNCTION__)); | ||||||||
| 5149 | if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B) | ||||||||
| 5150 | return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); | ||||||||
| 5151 | if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B) | ||||||||
| 5152 | return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); | ||||||||
| 5153 | if (Op1Max == Op0Min) // A <=u B -> A == B if min(A) == max(B) | ||||||||
| 5154 | return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1); | ||||||||
| 5155 | break; | ||||||||
| 5156 | } | ||||||||
| 5157 | |||||||||
| 5158 | // Turn a signed comparison into an unsigned one if both operands are known to | ||||||||
| 5159 | // have the same sign. | ||||||||
| 5160 | if (I.isSigned() && | ||||||||
| 5161 | ((Op0Known.Zero.isNegative() && Op1Known.Zero.isNegative()) || | ||||||||
| 5162 | (Op0Known.One.isNegative() && Op1Known.One.isNegative()))) | ||||||||
| 5163 | return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1); | ||||||||
| 5164 | |||||||||
| 5165 | return nullptr; | ||||||||
| 5166 | } | ||||||||
| 5167 | |||||||||
| 5168 | llvm::Optional<std::pair<CmpInst::Predicate, Constant *>> | ||||||||
| 5169 | llvm::getFlippedStrictnessPredicateAndConstant(CmpInst::Predicate Pred, | ||||||||
| 5170 | Constant *C) { | ||||||||
| 5171 | assert(ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate(Pred) &&((ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate (Pred) && "Only for relational integer predicates.") ? static_cast<void> (0) : __assert_fail ("ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate(Pred) && \"Only for relational integer predicates.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5172, __PRETTY_FUNCTION__)) | ||||||||
| 5172 | "Only for relational integer predicates.")((ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate (Pred) && "Only for relational integer predicates.") ? static_cast<void> (0) : __assert_fail ("ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate(Pred) && \"Only for relational integer predicates.\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5172, __PRETTY_FUNCTION__)); | ||||||||
| 5173 | |||||||||
| 5174 | Type *Type = C->getType(); | ||||||||
| 5175 | bool IsSigned = ICmpInst::isSigned(Pred); | ||||||||
| 5176 | |||||||||
| 5177 | CmpInst::Predicate UnsignedPred = ICmpInst::getUnsignedPredicate(Pred); | ||||||||
| 5178 | bool WillIncrement = | ||||||||
| 5179 | UnsignedPred == ICmpInst::ICMP_ULE || UnsignedPred == ICmpInst::ICMP_UGT; | ||||||||
| 5180 | |||||||||
| 5181 | // Check if the constant operand can be safely incremented/decremented | ||||||||
| 5182 | // without overflowing/underflowing. | ||||||||
| 5183 | auto ConstantIsOk = [WillIncrement, IsSigned](ConstantInt *C) { | ||||||||
| 5184 | return WillIncrement ? !C->isMaxValue(IsSigned) : !C->isMinValue(IsSigned); | ||||||||
| 5185 | }; | ||||||||
| 5186 | |||||||||
| 5187 | Constant *SafeReplacementConstant = nullptr; | ||||||||
| 5188 | if (auto *CI = dyn_cast<ConstantInt>(C)) { | ||||||||
| 5189 | // Bail out if the constant can't be safely incremented/decremented. | ||||||||
| 5190 | if (!ConstantIsOk(CI)) | ||||||||
| 5191 | return llvm::None; | ||||||||
| 5192 | } else if (Type->isVectorTy()) { | ||||||||
| 5193 | unsigned NumElts = Type->getVectorNumElements(); | ||||||||
| 5194 | for (unsigned i = 0; i != NumElts; ++i) { | ||||||||
| 5195 | Constant *Elt = C->getAggregateElement(i); | ||||||||
| 5196 | if (!Elt) | ||||||||
| 5197 | return llvm::None; | ||||||||
| 5198 | |||||||||
| 5199 | if (isa<UndefValue>(Elt)) | ||||||||
| 5200 | continue; | ||||||||
| 5201 | |||||||||
| 5202 | // Bail out if we can't determine if this constant is min/max or if we | ||||||||
| 5203 | // know that this constant is min/max. | ||||||||
| 5204 | auto *CI = dyn_cast<ConstantInt>(Elt); | ||||||||
| 5205 | if (!CI || !ConstantIsOk(CI)) | ||||||||
| 5206 | return llvm::None; | ||||||||
| 5207 | |||||||||
| 5208 | if (!SafeReplacementConstant) | ||||||||
| 5209 | SafeReplacementConstant = CI; | ||||||||
| 5210 | } | ||||||||
| 5211 | } else { | ||||||||
| 5212 | // ConstantExpr? | ||||||||
| 5213 | return llvm::None; | ||||||||
| 5214 | } | ||||||||
| 5215 | |||||||||
| 5216 | // It may not be safe to change a compare predicate in the presence of | ||||||||
| 5217 | // undefined elements, so replace those elements with the first safe constant | ||||||||
| 5218 | // that we found. | ||||||||
| 5219 | if (C->containsUndefElement()) { | ||||||||
| 5220 | assert(SafeReplacementConstant && "Replacement constant not set")((SafeReplacementConstant && "Replacement constant not set" ) ? static_cast<void> (0) : __assert_fail ("SafeReplacementConstant && \"Replacement constant not set\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5220, __PRETTY_FUNCTION__)); | ||||||||
| 5221 | C = Constant::replaceUndefsWith(C, SafeReplacementConstant); | ||||||||
| 5222 | } | ||||||||
| 5223 | |||||||||
| 5224 | CmpInst::Predicate NewPred = CmpInst::getFlippedStrictnessPredicate(Pred); | ||||||||
| 5225 | |||||||||
| 5226 | // Increment or decrement the constant. | ||||||||
| 5227 | Constant *OneOrNegOne = ConstantInt::get(Type, WillIncrement ? 1 : -1, true); | ||||||||
| 5228 | Constant *NewC = ConstantExpr::getAdd(C, OneOrNegOne); | ||||||||
| 5229 | |||||||||
| 5230 | return std::make_pair(NewPred, NewC); | ||||||||
| 5231 | } | ||||||||
| 5232 | |||||||||
| 5233 | /// If we have an icmp le or icmp ge instruction with a constant operand, turn | ||||||||
| 5234 | /// it into the appropriate icmp lt or icmp gt instruction. This transform | ||||||||
| 5235 | /// allows them to be folded in visitICmpInst. | ||||||||
| 5236 | static ICmpInst *canonicalizeCmpWithConstant(ICmpInst &I) { | ||||||||
| 5237 | ICmpInst::Predicate Pred = I.getPredicate(); | ||||||||
| 5238 | if (ICmpInst::isEquality(Pred) || !ICmpInst::isIntPredicate(Pred) || | ||||||||
| 5239 | isCanonicalPredicate(Pred)) | ||||||||
| 5240 | return nullptr; | ||||||||
| 5241 | |||||||||
| 5242 | Value *Op0 = I.getOperand(0); | ||||||||
| 5243 | Value *Op1 = I.getOperand(1); | ||||||||
| 5244 | auto *Op1C = dyn_cast<Constant>(Op1); | ||||||||
| 5245 | if (!Op1C) | ||||||||
| 5246 | return nullptr; | ||||||||
| 5247 | |||||||||
| 5248 | auto FlippedStrictness = getFlippedStrictnessPredicateAndConstant(Pred, Op1C); | ||||||||
| 5249 | if (!FlippedStrictness) | ||||||||
| 5250 | return nullptr; | ||||||||
| 5251 | |||||||||
| 5252 | return new ICmpInst(FlippedStrictness->first, Op0, FlippedStrictness->second); | ||||||||
| 5253 | } | ||||||||
| 5254 | |||||||||
| 5255 | /// Integer compare with boolean values can always be turned into bitwise ops. | ||||||||
| 5256 | static Instruction *canonicalizeICmpBool(ICmpInst &I, | ||||||||
| 5257 | InstCombiner::BuilderTy &Builder) { | ||||||||
| 5258 | Value *A = I.getOperand(0), *B = I.getOperand(1); | ||||||||
| 5259 | assert(A->getType()->isIntOrIntVectorTy(1) && "Bools only")((A->getType()->isIntOrIntVectorTy(1) && "Bools only" ) ? static_cast<void> (0) : __assert_fail ("A->getType()->isIntOrIntVectorTy(1) && \"Bools only\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5259, __PRETTY_FUNCTION__)); | ||||||||
| 5260 | |||||||||
| 5261 | // A boolean compared to true/false can be simplified to Op0/true/false in | ||||||||
| 5262 | // 14 out of the 20 (10 predicates * 2 constants) possible combinations. | ||||||||
| 5263 | // Cases not handled by InstSimplify are always 'not' of Op0. | ||||||||
| 5264 | if (match(B, m_Zero())) { | ||||||||
| 5265 | switch (I.getPredicate()) { | ||||||||
| 5266 | case CmpInst::ICMP_EQ: // A == 0 -> !A | ||||||||
| 5267 | case CmpInst::ICMP_ULE: // A <=u 0 -> !A | ||||||||
| 5268 | case CmpInst::ICMP_SGE: // A >=s 0 -> !A | ||||||||
| 5269 | return BinaryOperator::CreateNot(A); | ||||||||
| 5270 | default: | ||||||||
| 5271 | llvm_unreachable("ICmp i1 X, C not simplified as expected.")::llvm::llvm_unreachable_internal("ICmp i1 X, C not simplified as expected." , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5271); | ||||||||
| 5272 | } | ||||||||
| 5273 | } else if (match(B, m_One())) { | ||||||||
| 5274 | switch (I.getPredicate()) { | ||||||||
| 5275 | case CmpInst::ICMP_NE: // A != 1 -> !A | ||||||||
| 5276 | case CmpInst::ICMP_ULT: // A <u 1 -> !A | ||||||||
| 5277 | case CmpInst::ICMP_SGT: // A >s -1 -> !A | ||||||||
| 5278 | return BinaryOperator::CreateNot(A); | ||||||||
| 5279 | default: | ||||||||
| 5280 | llvm_unreachable("ICmp i1 X, C not simplified as expected.")::llvm::llvm_unreachable_internal("ICmp i1 X, C not simplified as expected." , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5280); | ||||||||
| 5281 | } | ||||||||
| 5282 | } | ||||||||
| 5283 | |||||||||
| 5284 | switch (I.getPredicate()) { | ||||||||
| 5285 | default: | ||||||||
| 5286 | llvm_unreachable("Invalid icmp instruction!")::llvm::llvm_unreachable_internal("Invalid icmp instruction!" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5286); | ||||||||
| 5287 | case ICmpInst::ICMP_EQ: | ||||||||
| 5288 | // icmp eq i1 A, B -> ~(A ^ B) | ||||||||
| 5289 | return BinaryOperator::CreateNot(Builder.CreateXor(A, B)); | ||||||||
| 5290 | |||||||||
| 5291 | case ICmpInst::ICMP_NE: | ||||||||
| 5292 | // icmp ne i1 A, B -> A ^ B | ||||||||
| 5293 | return BinaryOperator::CreateXor(A, B); | ||||||||
| 5294 | |||||||||
| 5295 | case ICmpInst::ICMP_UGT: | ||||||||
| 5296 | // icmp ugt -> icmp ult | ||||||||
| 5297 | std::swap(A, B); | ||||||||
| 5298 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
| 5299 | case ICmpInst::ICMP_ULT: | ||||||||
| 5300 | // icmp ult i1 A, B -> ~A & B | ||||||||
| 5301 | return BinaryOperator::CreateAnd(Builder.CreateNot(A), B); | ||||||||
| 5302 | |||||||||
| 5303 | case ICmpInst::ICMP_SGT: | ||||||||
| 5304 | // icmp sgt -> icmp slt | ||||||||
| 5305 | std::swap(A, B); | ||||||||
| 5306 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
| 5307 | case ICmpInst::ICMP_SLT: | ||||||||
| 5308 | // icmp slt i1 A, B -> A & ~B | ||||||||
| 5309 | return BinaryOperator::CreateAnd(Builder.CreateNot(B), A); | ||||||||
| 5310 | |||||||||
| 5311 | case ICmpInst::ICMP_UGE: | ||||||||
| 5312 | // icmp uge -> icmp ule | ||||||||
| 5313 | std::swap(A, B); | ||||||||
| 5314 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
| 5315 | case ICmpInst::ICMP_ULE: | ||||||||
| 5316 | // icmp ule i1 A, B -> ~A | B | ||||||||
| 5317 | return BinaryOperator::CreateOr(Builder.CreateNot(A), B); | ||||||||
| 5318 | |||||||||
| 5319 | case ICmpInst::ICMP_SGE: | ||||||||
| 5320 | // icmp sge -> icmp sle | ||||||||
| 5321 | std::swap(A, B); | ||||||||
| 5322 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
| 5323 | case ICmpInst::ICMP_SLE: | ||||||||
| 5324 | // icmp sle i1 A, B -> A | ~B | ||||||||
| 5325 | return BinaryOperator::CreateOr(Builder.CreateNot(B), A); | ||||||||
| 5326 | } | ||||||||
| 5327 | } | ||||||||
| 5328 | |||||||||
| 5329 | // Transform pattern like: | ||||||||
| 5330 | // (1 << Y) u<= X or ~(-1 << Y) u< X or ((1 << Y)+(-1)) u< X | ||||||||
| 5331 | // (1 << Y) u> X or ~(-1 << Y) u>= X or ((1 << Y)+(-1)) u>= X | ||||||||
| 5332 | // Into: | ||||||||
| 5333 | // (X l>> Y) != 0 | ||||||||
| 5334 | // (X l>> Y) == 0 | ||||||||
| 5335 | static Instruction *foldICmpWithHighBitMask(ICmpInst &Cmp, | ||||||||
| 5336 | InstCombiner::BuilderTy &Builder) { | ||||||||
| 5337 | ICmpInst::Predicate Pred, NewPred; | ||||||||
| 5338 | Value *X, *Y; | ||||||||
| 5339 | if (match(&Cmp, | ||||||||
| 5340 | m_c_ICmp(Pred, m_OneUse(m_Shl(m_One(), m_Value(Y))), m_Value(X)))) { | ||||||||
| 5341 | // We want X to be the icmp's second operand, so swap predicate if it isn't. | ||||||||
| 5342 | if (Cmp.getOperand(0) == X) | ||||||||
| 5343 | Pred = Cmp.getSwappedPredicate(); | ||||||||
| 5344 | |||||||||
| 5345 | switch (Pred) { | ||||||||
| 5346 | case ICmpInst::ICMP_ULE: | ||||||||
| 5347 | NewPred = ICmpInst::ICMP_NE; | ||||||||
| 5348 | break; | ||||||||
| 5349 | case ICmpInst::ICMP_UGT: | ||||||||
| 5350 | NewPred = ICmpInst::ICMP_EQ; | ||||||||
| 5351 | break; | ||||||||
| 5352 | default: | ||||||||
| 5353 | return nullptr; | ||||||||
| 5354 | } | ||||||||
| 5355 | } else if (match(&Cmp, m_c_ICmp(Pred, | ||||||||
| 5356 | m_OneUse(m_CombineOr( | ||||||||
| 5357 | m_Not(m_Shl(m_AllOnes(), m_Value(Y))), | ||||||||
| 5358 | m_Add(m_Shl(m_One(), m_Value(Y)), | ||||||||
| 5359 | m_AllOnes()))), | ||||||||
| 5360 | m_Value(X)))) { | ||||||||
| 5361 | // The variant with 'add' is not canonical, (the variant with 'not' is) | ||||||||
| 5362 | // we only get it because it has extra uses, and can't be canonicalized, | ||||||||
| 5363 | |||||||||
| 5364 | // We want X to be the icmp's second operand, so swap predicate if it isn't. | ||||||||
| 5365 | if (Cmp.getOperand(0) == X) | ||||||||
| 5366 | Pred = Cmp.getSwappedPredicate(); | ||||||||
| 5367 | |||||||||
| 5368 | switch (Pred) { | ||||||||
| 5369 | case ICmpInst::ICMP_ULT: | ||||||||
| 5370 | NewPred = ICmpInst::ICMP_NE; | ||||||||
| 5371 | break; | ||||||||
| 5372 | case ICmpInst::ICMP_UGE: | ||||||||
| 5373 | NewPred = ICmpInst::ICMP_EQ; | ||||||||
| 5374 | break; | ||||||||
| 5375 | default: | ||||||||
| 5376 | return nullptr; | ||||||||
| 5377 | } | ||||||||
| 5378 | } else | ||||||||
| 5379 | return nullptr; | ||||||||
| 5380 | |||||||||
| 5381 | Value *NewX = Builder.CreateLShr(X, Y, X->getName() + ".highbits"); | ||||||||
| 5382 | Constant *Zero = Constant::getNullValue(NewX->getType()); | ||||||||
| 5383 | return CmpInst::Create(Instruction::ICmp, NewPred, NewX, Zero); | ||||||||
| 5384 | } | ||||||||
| 5385 | |||||||||
| 5386 | static Instruction *foldVectorCmp(CmpInst &Cmp, | ||||||||
| 5387 | InstCombiner::BuilderTy &Builder) { | ||||||||
| 5388 | // If both arguments of the cmp are shuffles that use the same mask and | ||||||||
| 5389 | // shuffle within a single vector, move the shuffle after the cmp. | ||||||||
| 5390 | Value *LHS = Cmp.getOperand(0), *RHS = Cmp.getOperand(1); | ||||||||
| 5391 | Value *V1, *V2; | ||||||||
| 5392 | Constant *M; | ||||||||
| 5393 | if (match(LHS, m_ShuffleVector(m_Value(V1), m_Undef(), m_Constant(M))) && | ||||||||
| 5394 | match(RHS, m_ShuffleVector(m_Value(V2), m_Undef(), m_Specific(M))) && | ||||||||
| 5395 | V1->getType() == V2->getType() && | ||||||||
| 5396 | (LHS->hasOneUse() || RHS->hasOneUse())) { | ||||||||
| 5397 | // cmp (shuffle V1, M), (shuffle V2, M) --> shuffle (cmp V1, V2), M | ||||||||
| 5398 | CmpInst::Predicate P = Cmp.getPredicate(); | ||||||||
| 5399 | Value *NewCmp = isa<ICmpInst>(Cmp) ? Builder.CreateICmp(P, V1, V2) | ||||||||
| 5400 | : Builder.CreateFCmp(P, V1, V2); | ||||||||
| 5401 | return new ShuffleVectorInst(NewCmp, UndefValue::get(NewCmp->getType()), M); | ||||||||
| 5402 | } | ||||||||
| 5403 | return nullptr; | ||||||||
| 5404 | } | ||||||||
| 5405 | |||||||||
| 5406 | // extract(uadd.with.overflow(A, B), 0) ult A | ||||||||
| 5407 | // -> extract(uadd.with.overflow(A, B), 1) | ||||||||
| 5408 | static Instruction *foldICmpOfUAddOv(ICmpInst &I) { | ||||||||
| 5409 | CmpInst::Predicate Pred = I.getPredicate(); | ||||||||
| 5410 | Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); | ||||||||
| 5411 | |||||||||
| 5412 | Value *UAddOv; | ||||||||
| 5413 | Value *A, *B; | ||||||||
| 5414 | auto UAddOvResultPat = m_ExtractValue<0>( | ||||||||
| 5415 | m_Intrinsic<Intrinsic::uadd_with_overflow>(m_Value(A), m_Value(B))); | ||||||||
| 5416 | if (match(Op0, UAddOvResultPat) && | ||||||||
| 5417 | ((Pred == ICmpInst::ICMP_ULT && (Op1 == A || Op1 == B)) || | ||||||||
| 5418 | (Pred == ICmpInst::ICMP_EQ && match(Op1, m_ZeroInt()) && | ||||||||
| 5419 | (match(A, m_One()) || match(B, m_One()))) || | ||||||||
| 5420 | (Pred == ICmpInst::ICMP_NE && match(Op1, m_AllOnes()) && | ||||||||
| 5421 | (match(A, m_AllOnes()) || match(B, m_AllOnes()))))) | ||||||||
| 5422 | // extract(uadd.with.overflow(A, B), 0) < A | ||||||||
| 5423 | // extract(uadd.with.overflow(A, 1), 0) == 0 | ||||||||
| 5424 | // extract(uadd.with.overflow(A, -1), 0) != -1 | ||||||||
| 5425 | UAddOv = cast<ExtractValueInst>(Op0)->getAggregateOperand(); | ||||||||
| 5426 | else if (match(Op1, UAddOvResultPat) && | ||||||||
| 5427 | Pred == ICmpInst::ICMP_UGT && (Op0 == A || Op0 == B)) | ||||||||
| 5428 | // A > extract(uadd.with.overflow(A, B), 0) | ||||||||
| 5429 | UAddOv = cast<ExtractValueInst>(Op1)->getAggregateOperand(); | ||||||||
| 5430 | else | ||||||||
| 5431 | return nullptr; | ||||||||
| 5432 | |||||||||
| 5433 | return ExtractValueInst::Create(UAddOv, 1); | ||||||||
| 5434 | } | ||||||||
| 5435 | |||||||||
| 5436 | Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { | ||||||||
| 5437 | bool Changed = false; | ||||||||
| 5438 | const SimplifyQuery Q = SQ.getWithInstruction(&I); | ||||||||
| 5439 | Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); | ||||||||
| 5440 | unsigned Op0Cplxity = getComplexity(Op0); | ||||||||
| 5441 | unsigned Op1Cplxity = getComplexity(Op1); | ||||||||
| 5442 | |||||||||
| 5443 | /// Orders the operands of the compare so that they are listed from most | ||||||||
| 5444 | /// complex to least complex. This puts constants before unary operators, | ||||||||
| 5445 | /// before binary operators. | ||||||||
| 5446 | if (Op0Cplxity < Op1Cplxity || | ||||||||
| 5447 | (Op0Cplxity == Op1Cplxity && swapMayExposeCSEOpportunities(Op0, Op1))) { | ||||||||
| 5448 | I.swapOperands(); | ||||||||
| 5449 | std::swap(Op0, Op1); | ||||||||
| 5450 | Changed = true; | ||||||||
| 5451 | } | ||||||||
| 5452 | |||||||||
| 5453 | if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, Q)) | ||||||||
| 5454 | return replaceInstUsesWith(I, V); | ||||||||
| 5455 | |||||||||
| 5456 | // Comparing -val or val with non-zero is the same as just comparing val | ||||||||
| 5457 | // ie, abs(val) != 0 -> val != 0 | ||||||||
| 5458 | if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero())) { | ||||||||
| 5459 | Value *Cond, *SelectTrue, *SelectFalse; | ||||||||
| 5460 | if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue), | ||||||||
| 5461 | m_Value(SelectFalse)))) { | ||||||||
| 5462 | if (Value *V = dyn_castNegVal(SelectTrue)) { | ||||||||
| 5463 | if (V == SelectFalse) | ||||||||
| 5464 | return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1); | ||||||||
| 5465 | } | ||||||||
| 5466 | else if (Value *V = dyn_castNegVal(SelectFalse)) { | ||||||||
| 5467 | if (V == SelectTrue) | ||||||||
| 5468 | return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1); | ||||||||
| 5469 | } | ||||||||
| 5470 | } | ||||||||
| 5471 | } | ||||||||
| 5472 | |||||||||
| 5473 | if (Op0->getType()->isIntOrIntVectorTy(1)) | ||||||||
| 5474 | if (Instruction *Res = canonicalizeICmpBool(I, Builder)) | ||||||||
| 5475 | return Res; | ||||||||
| 5476 | |||||||||
| 5477 | if (ICmpInst *NewICmp = canonicalizeCmpWithConstant(I)) | ||||||||
| 5478 | return NewICmp; | ||||||||
| 5479 | |||||||||
| 5480 | if (Instruction *Res = foldICmpWithConstant(I)) | ||||||||
| 5481 | return Res; | ||||||||
| 5482 | |||||||||
| 5483 | if (Instruction *Res = foldICmpWithDominatingICmp(I)) | ||||||||
| 5484 | return Res; | ||||||||
| 5485 | |||||||||
| 5486 | if (Instruction *Res = foldICmpBinOp(I, Q)) | ||||||||
| 5487 | return Res; | ||||||||
| 5488 | |||||||||
| 5489 | if (Instruction *Res = foldICmpUsingKnownBits(I)) | ||||||||
| 5490 | return Res; | ||||||||
| 5491 | |||||||||
| 5492 | // Test if the ICmpInst instruction is used exclusively by a select as | ||||||||
| 5493 | // part of a minimum or maximum operation. If so, refrain from doing | ||||||||
| 5494 | // any other folding. This helps out other analyses which understand | ||||||||
| 5495 | // non-obfuscated minimum and maximum idioms, such as ScalarEvolution | ||||||||
| 5496 | // and CodeGen. And in this case, at least one of the comparison | ||||||||
| 5497 | // operands has at least one user besides the compare (the select), | ||||||||
| 5498 | // which would often largely negate the benefit of folding anyway. | ||||||||
| 5499 | // | ||||||||
| 5500 | // Do the same for the other patterns recognized by matchSelectPattern. | ||||||||
| 5501 | if (I.hasOneUse()) | ||||||||
| 5502 | if (SelectInst *SI = dyn_cast<SelectInst>(I.user_back())) { | ||||||||
| 5503 | Value *A, *B; | ||||||||
| 5504 | SelectPatternResult SPR = matchSelectPattern(SI, A, B); | ||||||||
| 5505 | if (SPR.Flavor != SPF_UNKNOWN) | ||||||||
| 5506 | return nullptr; | ||||||||
| 5507 | } | ||||||||
| 5508 | |||||||||
| 5509 | // Do this after checking for min/max to prevent infinite looping. | ||||||||
| 5510 | if (Instruction *Res = foldICmpWithZero(I)) | ||||||||
| 5511 | return Res; | ||||||||
| 5512 | |||||||||
| 5513 | // FIXME: We only do this after checking for min/max to prevent infinite | ||||||||
| 5514 | // looping caused by a reverse canonicalization of these patterns for min/max. | ||||||||
| 5515 | // FIXME: The organization of folds is a mess. These would naturally go into | ||||||||
| 5516 | // canonicalizeCmpWithConstant(), but we can't move all of the above folds | ||||||||
| 5517 | // down here after the min/max restriction. | ||||||||
| 5518 | ICmpInst::Predicate Pred = I.getPredicate(); | ||||||||
| 5519 | const APInt *C; | ||||||||
| 5520 | if (match(Op1, m_APInt(C))) { | ||||||||
| 5521 | // For i32: x >u 2147483647 -> x <s 0 -> true if sign bit set | ||||||||
| 5522 | if (Pred == ICmpInst::ICMP_UGT && C->isMaxSignedValue()) { | ||||||||
| 5523 | Constant *Zero = Constant::getNullValue(Op0->getType()); | ||||||||
| 5524 | return new ICmpInst(ICmpInst::ICMP_SLT, Op0, Zero); | ||||||||
| 5525 | } | ||||||||
| 5526 | |||||||||
| 5527 | // For i32: x <u 2147483648 -> x >s -1 -> true if sign bit clear | ||||||||
| 5528 | if (Pred == ICmpInst::ICMP_ULT && C->isMinSignedValue()) { | ||||||||
| 5529 | Constant *AllOnes = Constant::getAllOnesValue(Op0->getType()); | ||||||||
| 5530 | return new ICmpInst(ICmpInst::ICMP_SGT, Op0, AllOnes); | ||||||||
| 5531 | } | ||||||||
| 5532 | } | ||||||||
| 5533 | |||||||||
| 5534 | if (Instruction *Res = foldICmpInstWithConstant(I)) | ||||||||
| 5535 | return Res; | ||||||||
| 5536 | |||||||||
| 5537 | // Try to match comparison as a sign bit test. Intentionally do this after | ||||||||
| 5538 | // foldICmpInstWithConstant() to potentially let other folds to happen first. | ||||||||
| 5539 | if (Instruction *New = foldSignBitTest(I)) | ||||||||
| 5540 | return New; | ||||||||
| 5541 | |||||||||
| 5542 | if (Instruction *Res = foldICmpInstWithConstantNotInt(I)) | ||||||||
| 5543 | return Res; | ||||||||
| 5544 | |||||||||
| 5545 | // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now. | ||||||||
| 5546 | if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0)) | ||||||||
| 5547 | if (Instruction *NI = foldGEPICmp(GEP, Op1, I.getPredicate(), I)) | ||||||||
| 5548 | return NI; | ||||||||
| 5549 | if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1)) | ||||||||
| 5550 | if (Instruction *NI = foldGEPICmp(GEP, Op0, | ||||||||
| 5551 | ICmpInst::getSwappedPredicate(I.getPredicate()), I)) | ||||||||
| 5552 | return NI; | ||||||||
| 5553 | |||||||||
| 5554 | // Try to optimize equality comparisons against alloca-based pointers. | ||||||||
| 5555 | if (Op0->getType()->isPointerTy() && I.isEquality()) { | ||||||||
| 5556 | 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?\"" , "/build/llvm-toolchain-snapshot-10~++20200112100611+7fa5290d5bd/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5556, __PRETTY_FUNCTION__)); | ||||||||
| 5557 | if (auto *Alloca = dyn_cast<AllocaInst>(GetUnderlyingObject(Op0, DL))) | ||||||||
| 5558 | if (Instruction *New = foldAllocaCmp(I, Alloca, Op1)) | ||||||||
| 5559 | return New; | ||||||||
| 5560 | if (auto *Alloca = dyn_cast<AllocaInst>(GetUnderlyingObject(Op1, DL))) | ||||||||
| 5561 | if (Instruction *New = foldAllocaCmp(I, Alloca, Op0)) | ||||||||
| 5562 | return New; | ||||||||
| 5563 | } | ||||||||
| 5564 | |||||||||
| 5565 | if (Instruction *Res = foldICmpBitCast(I, Builder)) | ||||||||
| 5566 | return Res; | ||||||||
| 5567 | |||||||||
| 5568 | if (Instruction *R = foldICmpWithCastOp(I)) | ||||||||
| 5569 | return R; | ||||||||
| 5570 | |||||||||
| 5571 | if (Instruction *Res = foldICmpWithMinMax(I)) | ||||||||
| 5572 | return Res; | ||||||||
| 5573 | |||||||||
| 5574 | { | ||||||||
| 5575 | Value *A, *B; | ||||||||
| 5576 | // Transform (A & ~B) == 0 --> (A & B) != 0 | ||||||||
| 5577 | // and (A & ~B) != 0 --> (A & B) == 0 | ||||||||
| 5578 | // if A is a power of 2. | ||||||||
| 5579 | if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) && | ||||||||
| 5580 | match(Op1, m_Zero()) && | ||||||||
| 5581 | isKnownToBeAPowerOfTwo(A, false, 0, &I) && I.isEquality()) | ||||||||
| 5582 | return new ICmpInst(I.getInversePredicate(), Builder.CreateAnd(A, B), | ||||||||
| 5583 | Op1); | ||||||||
| 5584 | |||||||||
| 5585 | // ~X < ~Y --> Y < X | ||||||||
| 5586 | // ~X < C --> X > ~C | ||||||||
| 5587 | if (match(Op0, m_Not(m_Value(A)))) { | ||||||||
| 5588 | if (match(Op1, m_Not(m_Value(B)))) | ||||||||
| 5589 | return new ICmpInst(I.getPredicate(), B, A); | ||||||||
| 5590 | |||||||||
| 5591 | const APInt *C; | ||||||||
| 5592 | if (match(Op1, m_APInt(C))) | ||||||||
| 5593 | return new ICmpInst(I.getSwappedPredicate(), A, | ||||||||
| 5594 | ConstantInt::get(Op1->getType(), ~(*C))); | ||||||||
| 5595 | } | ||||||||
| 5596 | |||||||||
| 5597 | Instruction *AddI = nullptr; | ||||||||
| 5598 | if (match(&I, m_UAddWithOverflow(m_Value(A), m_Value(B), | ||||||||
| 5599 | m_Instruction(AddI))) && | ||||||||
| 5600 | isa<IntegerType>(A->getType())) { | ||||||||
| 5601 | Value *Result; | ||||||||
| 5602 | Constant *Overflow; | ||||||||
| 5603 | if (OptimizeOverflowCheck(Instruction::Add, /*Signed*/false, A, B, | ||||||||
| 5604 |