1202375Srdivacky//===- InstCombineCompares.cpp --------------------------------------------===// 2202375Srdivacky// 3202375Srdivacky// The LLVM Compiler Infrastructure 4202375Srdivacky// 5202375Srdivacky// This file is distributed under the University of Illinois Open Source 6202375Srdivacky// License. See LICENSE.TXT for details. 7202375Srdivacky// 8202375Srdivacky//===----------------------------------------------------------------------===// 9202375Srdivacky// 10202375Srdivacky// This file implements the visitICmp and visitFCmp functions. 11202375Srdivacky// 12202375Srdivacky//===----------------------------------------------------------------------===// 13202375Srdivacky 14202375Srdivacky#include "InstCombine.h" 15226890Sdim#include "llvm/Analysis/ConstantFolding.h" 16202375Srdivacky#include "llvm/Analysis/InstructionSimplify.h" 17202375Srdivacky#include "llvm/Analysis/MemoryBuiltins.h" 18252723Sdim#include "llvm/IR/DataLayout.h" 19252723Sdim#include "llvm/IR/IntrinsicInst.h" 20202375Srdivacky#include "llvm/Support/ConstantRange.h" 21202375Srdivacky#include "llvm/Support/GetElementPtrTypeIterator.h" 22202375Srdivacky#include "llvm/Support/PatternMatch.h" 23252723Sdim#include "llvm/Target/TargetLibraryInfo.h" 24202375Srdivackyusing namespace llvm; 25202375Srdivackyusing namespace PatternMatch; 26202375Srdivacky 27218893Sdimstatic ConstantInt *getOne(Constant *C) { 28218893Sdim return ConstantInt::get(cast<IntegerType>(C->getType()), 1); 29218893Sdim} 30218893Sdim 31202375Srdivacky/// AddOne - Add one to a ConstantInt 32202375Srdivackystatic Constant *AddOne(Constant *C) { 33202375Srdivacky return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1)); 34202375Srdivacky} 35202375Srdivacky/// SubOne - Subtract one from a ConstantInt 36218893Sdimstatic Constant *SubOne(Constant *C) { 37218893Sdim return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1)); 38202375Srdivacky} 39202375Srdivacky 40202375Srdivackystatic ConstantInt *ExtractElement(Constant *V, Constant *Idx) { 41202375Srdivacky return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx)); 42202375Srdivacky} 43202375Srdivacky 44202375Srdivackystatic bool HasAddOverflow(ConstantInt *Result, 45202375Srdivacky ConstantInt *In1, ConstantInt *In2, 46202375Srdivacky bool IsSigned) { 47224145Sdim if (!IsSigned) 48202375Srdivacky return Result->getValue().ult(In1->getValue()); 49224145Sdim 50224145Sdim if (In2->isNegative()) 51224145Sdim return Result->getValue().sgt(In1->getValue()); 52224145Sdim return Result->getValue().slt(In1->getValue()); 53202375Srdivacky} 54202375Srdivacky 55202375Srdivacky/// AddWithOverflow - Compute Result = In1+In2, returning true if the result 56202375Srdivacky/// overflowed for this type. 57202375Srdivackystatic bool AddWithOverflow(Constant *&Result, Constant *In1, 58202375Srdivacky Constant *In2, bool IsSigned = false) { 59202375Srdivacky Result = ConstantExpr::getAdd(In1, In2); 60202375Srdivacky 61226890Sdim if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) { 62202375Srdivacky for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 63202375Srdivacky Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i); 64202375Srdivacky if (HasAddOverflow(ExtractElement(Result, Idx), 65202375Srdivacky ExtractElement(In1, Idx), 66202375Srdivacky ExtractElement(In2, Idx), 67202375Srdivacky IsSigned)) 68202375Srdivacky return true; 69202375Srdivacky } 70202375Srdivacky return false; 71202375Srdivacky } 72202375Srdivacky 73202375Srdivacky return HasAddOverflow(cast<ConstantInt>(Result), 74202375Srdivacky cast<ConstantInt>(In1), cast<ConstantInt>(In2), 75202375Srdivacky IsSigned); 76202375Srdivacky} 77202375Srdivacky 78202375Srdivackystatic bool HasSubOverflow(ConstantInt *Result, 79202375Srdivacky ConstantInt *In1, ConstantInt *In2, 80202375Srdivacky bool IsSigned) { 81224145Sdim if (!IsSigned) 82202375Srdivacky return Result->getValue().ugt(In1->getValue()); 83226890Sdim 84224145Sdim if (In2->isNegative()) 85224145Sdim return Result->getValue().slt(In1->getValue()); 86224145Sdim 87224145Sdim return Result->getValue().sgt(In1->getValue()); 88202375Srdivacky} 89202375Srdivacky 90202375Srdivacky/// SubWithOverflow - Compute Result = In1-In2, returning true if the result 91202375Srdivacky/// overflowed for this type. 92202375Srdivackystatic bool SubWithOverflow(Constant *&Result, Constant *In1, 93202375Srdivacky Constant *In2, bool IsSigned = false) { 94202375Srdivacky Result = ConstantExpr::getSub(In1, In2); 95202375Srdivacky 96226890Sdim if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) { 97202375Srdivacky for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { 98202375Srdivacky Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i); 99202375Srdivacky if (HasSubOverflow(ExtractElement(Result, Idx), 100202375Srdivacky ExtractElement(In1, Idx), 101202375Srdivacky ExtractElement(In2, Idx), 102202375Srdivacky IsSigned)) 103202375Srdivacky return true; 104202375Srdivacky } 105202375Srdivacky return false; 106202375Srdivacky } 107202375Srdivacky 108202375Srdivacky return HasSubOverflow(cast<ConstantInt>(Result), 109202375Srdivacky cast<ConstantInt>(In1), cast<ConstantInt>(In2), 110202375Srdivacky IsSigned); 111202375Srdivacky} 112202375Srdivacky 113202375Srdivacky/// isSignBitCheck - Given an exploded icmp instruction, return true if the 114202375Srdivacky/// comparison only checks the sign bit. If it only checks the sign bit, set 115202375Srdivacky/// TrueIfSigned if the result of the comparison is true when the input value is 116202375Srdivacky/// signed. 117202375Srdivackystatic bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS, 118202375Srdivacky bool &TrueIfSigned) { 119202375Srdivacky switch (pred) { 120202375Srdivacky case ICmpInst::ICMP_SLT: // True if LHS s< 0 121202375Srdivacky TrueIfSigned = true; 122202375Srdivacky return RHS->isZero(); 123202375Srdivacky case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1 124202375Srdivacky TrueIfSigned = true; 125202375Srdivacky return RHS->isAllOnesValue(); 126202375Srdivacky case ICmpInst::ICMP_SGT: // True if LHS s> -1 127202375Srdivacky TrueIfSigned = false; 128202375Srdivacky return RHS->isAllOnesValue(); 129202375Srdivacky case ICmpInst::ICMP_UGT: 130202375Srdivacky // True if LHS u> RHS and RHS == high-bit-mask - 1 131202375Srdivacky TrueIfSigned = true; 132224145Sdim return RHS->isMaxValue(true); 133226890Sdim case ICmpInst::ICMP_UGE: 134202375Srdivacky // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc) 135202375Srdivacky TrueIfSigned = true; 136202375Srdivacky return RHS->getValue().isSignBit(); 137202375Srdivacky default: 138202375Srdivacky return false; 139202375Srdivacky } 140202375Srdivacky} 141202375Srdivacky 142252723Sdim/// Returns true if the exploded icmp can be expressed as a signed comparison 143252723Sdim/// to zero and updates the predicate accordingly. 144252723Sdim/// The signedness of the comparison is preserved. 145252723Sdimstatic bool isSignTest(ICmpInst::Predicate &pred, const ConstantInt *RHS) { 146252723Sdim if (!ICmpInst::isSigned(pred)) 147252723Sdim return false; 148252723Sdim 149252723Sdim if (RHS->isZero()) 150252723Sdim return ICmpInst::isRelational(pred); 151252723Sdim 152252723Sdim if (RHS->isOne()) { 153252723Sdim if (pred == ICmpInst::ICMP_SLT) { 154252723Sdim pred = ICmpInst::ICMP_SLE; 155252723Sdim return true; 156252723Sdim } 157252723Sdim } else if (RHS->isAllOnesValue()) { 158252723Sdim if (pred == ICmpInst::ICMP_SGT) { 159252723Sdim pred = ICmpInst::ICMP_SGE; 160252723Sdim return true; 161252723Sdim } 162252723Sdim } 163252723Sdim 164252723Sdim return false; 165252723Sdim} 166252723Sdim 167202375Srdivacky// isHighOnes - Return true if the constant is of the form 1+0+. 168202375Srdivacky// This is the same as lowones(~X). 169202375Srdivackystatic bool isHighOnes(const ConstantInt *CI) { 170202375Srdivacky return (~CI->getValue() + 1).isPowerOf2(); 171202375Srdivacky} 172202375Srdivacky 173226890Sdim/// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a 174202375Srdivacky/// set of known zero and one bits, compute the maximum and minimum values that 175202375Srdivacky/// could have the specified known zero and known one bits, returning them in 176202375Srdivacky/// min/max. 177202375Srdivackystatic void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero, 178202375Srdivacky const APInt& KnownOne, 179202375Srdivacky APInt& Min, APInt& Max) { 180202375Srdivacky assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() && 181202375Srdivacky KnownZero.getBitWidth() == Min.getBitWidth() && 182202375Srdivacky KnownZero.getBitWidth() == Max.getBitWidth() && 183202375Srdivacky "KnownZero, KnownOne and Min, Max must have equal bitwidth."); 184202375Srdivacky APInt UnknownBits = ~(KnownZero|KnownOne); 185202375Srdivacky 186202375Srdivacky // The minimum value is when all unknown bits are zeros, EXCEPT for the sign 187202375Srdivacky // bit if it is unknown. 188202375Srdivacky Min = KnownOne; 189202375Srdivacky Max = KnownOne|UnknownBits; 190226890Sdim 191202375Srdivacky if (UnknownBits.isNegative()) { // Sign bit is unknown 192218893Sdim Min.setBit(Min.getBitWidth()-1); 193218893Sdim Max.clearBit(Max.getBitWidth()-1); 194202375Srdivacky } 195202375Srdivacky} 196202375Srdivacky 197202375Srdivacky// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and 198202375Srdivacky// a set of known zero and one bits, compute the maximum and minimum values that 199202375Srdivacky// could have the specified known zero and known one bits, returning them in 200202375Srdivacky// min/max. 201202375Srdivackystatic void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero, 202202375Srdivacky const APInt &KnownOne, 203202375Srdivacky APInt &Min, APInt &Max) { 204202375Srdivacky assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() && 205202375Srdivacky KnownZero.getBitWidth() == Min.getBitWidth() && 206202375Srdivacky KnownZero.getBitWidth() == Max.getBitWidth() && 207202375Srdivacky "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."); 208202375Srdivacky APInt UnknownBits = ~(KnownZero|KnownOne); 209226890Sdim 210202375Srdivacky // The minimum value is when the unknown bits are all zeros. 211202375Srdivacky Min = KnownOne; 212202375Srdivacky // The maximum value is when the unknown bits are all ones. 213202375Srdivacky Max = KnownOne|UnknownBits; 214202375Srdivacky} 215202375Srdivacky 216202375Srdivacky 217202375Srdivacky 218202375Srdivacky/// FoldCmpLoadFromIndexedGlobal - Called we see this pattern: 219202375Srdivacky/// cmp pred (load (gep GV, ...)), cmpcst 220202375Srdivacky/// where GV is a global variable with a constant initializer. Try to simplify 221202375Srdivacky/// this into some simple computation that does not need the load. For example 222202375Srdivacky/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3". 223202375Srdivacky/// 224202375Srdivacky/// If AndCst is non-null, then the loaded value is masked with that constant 225202375Srdivacky/// before doing the comparison. This handles cases like "A[i]&4 == 0". 226202375SrdivackyInstruction *InstCombiner:: 227202375SrdivackyFoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, 228202375Srdivacky CmpInst &ICI, ConstantInt *AndCst) { 229202375Srdivacky // We need TD information to know the pointer size unless this is inbounds. 230263509Sdim if (!GEP->isInBounds() && TD == 0) 231263509Sdim return 0; 232226890Sdim 233235633Sdim Constant *Init = GV->getInitializer(); 234235633Sdim if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init)) 235235633Sdim return 0; 236252723Sdim 237235633Sdim uint64_t ArrayElementCount = Init->getType()->getArrayNumElements(); 238235633Sdim if (ArrayElementCount > 1024) return 0; // Don't blow up on huge arrays. 239226890Sdim 240202375Srdivacky // There are many forms of this optimization we can handle, for now, just do 241202375Srdivacky // the simple index into a single-dimensional array. 242202375Srdivacky // 243202375Srdivacky // Require: GEP GV, 0, i {{, constant indices}} 244202375Srdivacky if (GEP->getNumOperands() < 3 || 245202375Srdivacky !isa<ConstantInt>(GEP->getOperand(1)) || 246202375Srdivacky !cast<ConstantInt>(GEP->getOperand(1))->isZero() || 247202375Srdivacky isa<Constant>(GEP->getOperand(2))) 248202375Srdivacky return 0; 249202375Srdivacky 250202375Srdivacky // Check that indices after the variable are constants and in-range for the 251202375Srdivacky // type they index. Collect the indices. This is typically for arrays of 252202375Srdivacky // structs. 253202375Srdivacky SmallVector<unsigned, 4> LaterIndices; 254226890Sdim 255235633Sdim Type *EltTy = Init->getType()->getArrayElementType(); 256202375Srdivacky for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) { 257202375Srdivacky ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i)); 258202375Srdivacky if (Idx == 0) return 0; // Variable index. 259226890Sdim 260202375Srdivacky uint64_t IdxVal = Idx->getZExtValue(); 261202375Srdivacky if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index. 262226890Sdim 263226890Sdim if (StructType *STy = dyn_cast<StructType>(EltTy)) 264202375Srdivacky EltTy = STy->getElementType(IdxVal); 265226890Sdim else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) { 266202375Srdivacky if (IdxVal >= ATy->getNumElements()) return 0; 267202375Srdivacky EltTy = ATy->getElementType(); 268202375Srdivacky } else { 269202375Srdivacky return 0; // Unknown type. 270202375Srdivacky } 271226890Sdim 272202375Srdivacky LaterIndices.push_back(IdxVal); 273202375Srdivacky } 274226890Sdim 275202375Srdivacky enum { Overdefined = -3, Undefined = -2 }; 276202375Srdivacky 277202375Srdivacky // Variables for our state machines. 278226890Sdim 279202375Srdivacky // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form 280202375Srdivacky // "i == 47 | i == 87", where 47 is the first index the condition is true for, 281202375Srdivacky // and 87 is the second (and last) index. FirstTrueElement is -2 when 282202375Srdivacky // undefined, otherwise set to the first true element. SecondTrueElement is 283202375Srdivacky // -2 when undefined, -3 when overdefined and >= 0 when that index is true. 284202375Srdivacky int FirstTrueElement = Undefined, SecondTrueElement = Undefined; 285202375Srdivacky 286202375Srdivacky // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the 287202375Srdivacky // form "i != 47 & i != 87". Same state transitions as for true elements. 288202375Srdivacky int FirstFalseElement = Undefined, SecondFalseElement = Undefined; 289226890Sdim 290202375Srdivacky /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these 291202375Srdivacky /// define a state machine that triggers for ranges of values that the index 292202375Srdivacky /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'. 293202375Srdivacky /// This is -2 when undefined, -3 when overdefined, and otherwise the last 294202375Srdivacky /// index in the range (inclusive). We use -2 for undefined here because we 295202375Srdivacky /// use relative comparisons and don't want 0-1 to match -1. 296202375Srdivacky int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined; 297226890Sdim 298202375Srdivacky // MagicBitvector - This is a magic bitvector where we set a bit if the 299202375Srdivacky // comparison is true for element 'i'. If there are 64 elements or less in 300202375Srdivacky // the array, this will fully represent all the comparison results. 301202375Srdivacky uint64_t MagicBitvector = 0; 302226890Sdim 303226890Sdim 304202375Srdivacky // Scan the array and see if one of our patterns matches. 305202375Srdivacky Constant *CompareRHS = cast<Constant>(ICI.getOperand(1)); 306235633Sdim for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) { 307235633Sdim Constant *Elt = Init->getAggregateElement(i); 308235633Sdim if (Elt == 0) return 0; 309226890Sdim 310202375Srdivacky // If this is indexing an array of structures, get the structure element. 311202375Srdivacky if (!LaterIndices.empty()) 312224145Sdim Elt = ConstantExpr::getExtractValue(Elt, LaterIndices); 313226890Sdim 314202375Srdivacky // If the element is masked, handle it. 315202375Srdivacky if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst); 316226890Sdim 317202375Srdivacky // Find out if the comparison would be true or false for the i'th element. 318202375Srdivacky Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt, 319235633Sdim CompareRHS, TD, TLI); 320202375Srdivacky // If the result is undef for this element, ignore it. 321202375Srdivacky if (isa<UndefValue>(C)) { 322202375Srdivacky // Extend range state machines to cover this element in case there is an 323202375Srdivacky // undef in the middle of the range. 324202375Srdivacky if (TrueRangeEnd == (int)i-1) 325202375Srdivacky TrueRangeEnd = i; 326202375Srdivacky if (FalseRangeEnd == (int)i-1) 327202375Srdivacky FalseRangeEnd = i; 328202375Srdivacky continue; 329202375Srdivacky } 330226890Sdim 331202375Srdivacky // If we can't compute the result for any of the elements, we have to give 332202375Srdivacky // up evaluating the entire conditional. 333202375Srdivacky if (!isa<ConstantInt>(C)) return 0; 334226890Sdim 335202375Srdivacky // Otherwise, we know if the comparison is true or false for this element, 336202375Srdivacky // update our state machines. 337202375Srdivacky bool IsTrueForElt = !cast<ConstantInt>(C)->isZero(); 338226890Sdim 339202375Srdivacky // State machine for single/double/range index comparison. 340202375Srdivacky if (IsTrueForElt) { 341202375Srdivacky // Update the TrueElement state machine. 342202375Srdivacky if (FirstTrueElement == Undefined) 343202375Srdivacky FirstTrueElement = TrueRangeEnd = i; // First true element. 344202375Srdivacky else { 345202375Srdivacky // Update double-compare state machine. 346202375Srdivacky if (SecondTrueElement == Undefined) 347202375Srdivacky SecondTrueElement = i; 348202375Srdivacky else 349202375Srdivacky SecondTrueElement = Overdefined; 350226890Sdim 351202375Srdivacky // Update range state machine. 352202375Srdivacky if (TrueRangeEnd == (int)i-1) 353202375Srdivacky TrueRangeEnd = i; 354202375Srdivacky else 355202375Srdivacky TrueRangeEnd = Overdefined; 356202375Srdivacky } 357202375Srdivacky } else { 358202375Srdivacky // Update the FalseElement state machine. 359202375Srdivacky if (FirstFalseElement == Undefined) 360202375Srdivacky FirstFalseElement = FalseRangeEnd = i; // First false element. 361202375Srdivacky else { 362202375Srdivacky // Update double-compare state machine. 363202375Srdivacky if (SecondFalseElement == Undefined) 364202375Srdivacky SecondFalseElement = i; 365202375Srdivacky else 366202375Srdivacky SecondFalseElement = Overdefined; 367226890Sdim 368202375Srdivacky // Update range state machine. 369202375Srdivacky if (FalseRangeEnd == (int)i-1) 370202375Srdivacky FalseRangeEnd = i; 371202375Srdivacky else 372202375Srdivacky FalseRangeEnd = Overdefined; 373202375Srdivacky } 374202375Srdivacky } 375226890Sdim 376226890Sdim 377202375Srdivacky // If this element is in range, update our magic bitvector. 378202375Srdivacky if (i < 64 && IsTrueForElt) 379202375Srdivacky MagicBitvector |= 1ULL << i; 380226890Sdim 381202375Srdivacky // If all of our states become overdefined, bail out early. Since the 382202375Srdivacky // predicate is expensive, only check it every 8 elements. This is only 383202375Srdivacky // really useful for really huge arrays. 384202375Srdivacky if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined && 385202375Srdivacky SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined && 386202375Srdivacky FalseRangeEnd == Overdefined) 387202375Srdivacky return 0; 388202375Srdivacky } 389202375Srdivacky 390202375Srdivacky // Now that we've scanned the entire array, emit our new comparison(s). We 391202375Srdivacky // order the state machines in complexity of the generated code. 392202375Srdivacky Value *Idx = GEP->getOperand(2); 393202375Srdivacky 394202375Srdivacky // If the index is larger than the pointer size of the target, truncate the 395202375Srdivacky // index down like the GEP would do implicitly. We don't have to do this for 396202375Srdivacky // an inbounds GEP because the index can't be out of range. 397263509Sdim if (!GEP->isInBounds()) { 398263509Sdim Type *IntPtrTy = TD->getIntPtrType(GEP->getType()); 399263509Sdim unsigned PtrSize = IntPtrTy->getIntegerBitWidth(); 400263509Sdim if (Idx->getType()->getPrimitiveSizeInBits() > PtrSize) 401263509Sdim Idx = Builder->CreateTrunc(Idx, IntPtrTy); 402263509Sdim } 403226890Sdim 404202375Srdivacky // If the comparison is only true for one or two elements, emit direct 405202375Srdivacky // comparisons. 406202375Srdivacky if (SecondTrueElement != Overdefined) { 407202375Srdivacky // None true -> false. 408202375Srdivacky if (FirstTrueElement == Undefined) 409263509Sdim return ReplaceInstUsesWith(ICI, Builder->getFalse()); 410226890Sdim 411202375Srdivacky Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement); 412226890Sdim 413202375Srdivacky // True for one element -> 'i == 47'. 414202375Srdivacky if (SecondTrueElement == Undefined) 415202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx); 416226890Sdim 417202375Srdivacky // True for two elements -> 'i == 47 | i == 72'. 418202375Srdivacky Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx); 419202375Srdivacky Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement); 420202375Srdivacky Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx); 421202375Srdivacky return BinaryOperator::CreateOr(C1, C2); 422202375Srdivacky } 423202375Srdivacky 424202375Srdivacky // If the comparison is only false for one or two elements, emit direct 425202375Srdivacky // comparisons. 426202375Srdivacky if (SecondFalseElement != Overdefined) { 427202375Srdivacky // None false -> true. 428202375Srdivacky if (FirstFalseElement == Undefined) 429263509Sdim return ReplaceInstUsesWith(ICI, Builder->getTrue()); 430226890Sdim 431202375Srdivacky Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement); 432202375Srdivacky 433202375Srdivacky // False for one element -> 'i != 47'. 434202375Srdivacky if (SecondFalseElement == Undefined) 435202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx); 436226890Sdim 437202375Srdivacky // False for two elements -> 'i != 47 & i != 72'. 438202375Srdivacky Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx); 439202375Srdivacky Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement); 440202375Srdivacky Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx); 441202375Srdivacky return BinaryOperator::CreateAnd(C1, C2); 442202375Srdivacky } 443226890Sdim 444202375Srdivacky // If the comparison can be replaced with a range comparison for the elements 445202375Srdivacky // where it is true, emit the range check. 446202375Srdivacky if (TrueRangeEnd != Overdefined) { 447202375Srdivacky assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare"); 448226890Sdim 449202375Srdivacky // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1). 450202375Srdivacky if (FirstTrueElement) { 451202375Srdivacky Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement); 452202375Srdivacky Idx = Builder->CreateAdd(Idx, Offs); 453202375Srdivacky } 454226890Sdim 455202375Srdivacky Value *End = ConstantInt::get(Idx->getType(), 456202375Srdivacky TrueRangeEnd-FirstTrueElement+1); 457202375Srdivacky return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End); 458202375Srdivacky } 459226890Sdim 460202375Srdivacky // False range check. 461202375Srdivacky if (FalseRangeEnd != Overdefined) { 462202375Srdivacky assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare"); 463202375Srdivacky // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse). 464202375Srdivacky if (FirstFalseElement) { 465202375Srdivacky Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement); 466202375Srdivacky Idx = Builder->CreateAdd(Idx, Offs); 467202375Srdivacky } 468226890Sdim 469202375Srdivacky Value *End = ConstantInt::get(Idx->getType(), 470202375Srdivacky FalseRangeEnd-FirstFalseElement); 471202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End); 472202375Srdivacky } 473226890Sdim 474226890Sdim 475252723Sdim // If a magic bitvector captures the entire comparison state 476202375Srdivacky // of this load, replace it with computation that does: 477202375Srdivacky // ((magic_cst >> i) & 1) != 0 478252723Sdim { 479252723Sdim Type *Ty = 0; 480252723Sdim 481252723Sdim // Look for an appropriate type: 482252723Sdim // - The type of Idx if the magic fits 483252723Sdim // - The smallest fitting legal type if we have a DataLayout 484252723Sdim // - Default to i32 485252723Sdim if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth()) 486252723Sdim Ty = Idx->getType(); 487252723Sdim else if (TD) 488252723Sdim Ty = TD->getSmallestLegalIntType(Init->getContext(), ArrayElementCount); 489252723Sdim else if (ArrayElementCount <= 32) 490202375Srdivacky Ty = Type::getInt32Ty(Init->getContext()); 491252723Sdim 492252723Sdim if (Ty != 0) { 493252723Sdim Value *V = Builder->CreateIntCast(Idx, Ty, false); 494252723Sdim V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V); 495252723Sdim V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V); 496252723Sdim return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0)); 497252723Sdim } 498202375Srdivacky } 499226890Sdim 500202375Srdivacky return 0; 501202375Srdivacky} 502202375Srdivacky 503202375Srdivacky 504202375Srdivacky/// EvaluateGEPOffsetExpression - Return a value that can be used to compare 505202375Srdivacky/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we 506202375Srdivacky/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can 507202375Srdivacky/// be complex, and scales are involved. The above expression would also be 508202375Srdivacky/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32). 509202375Srdivacky/// This later form is less amenable to optimization though, and we are allowed 510202375Srdivacky/// to generate the first by knowing that pointer arithmetic doesn't overflow. 511202375Srdivacky/// 512202375Srdivacky/// If we can't emit an optimized form for this expression, this returns null. 513226890Sdim/// 514223017Sdimstatic Value *EvaluateGEPOffsetExpression(User *GEP, InstCombiner &IC) { 515245431Sdim DataLayout &TD = *IC.getDataLayout(); 516202375Srdivacky gep_type_iterator GTI = gep_type_begin(GEP); 517226890Sdim 518202375Srdivacky // Check to see if this gep only has a single variable index. If so, and if 519202375Srdivacky // any constant indices are a multiple of its scale, then we can compute this 520202375Srdivacky // in terms of the scale of the variable index. For example, if the GEP 521202375Srdivacky // implies an offset of "12 + i*4", then we can codegen this as "3 + i", 522202375Srdivacky // because the expression will cross zero at the same point. 523202375Srdivacky unsigned i, e = GEP->getNumOperands(); 524202375Srdivacky int64_t Offset = 0; 525202375Srdivacky for (i = 1; i != e; ++i, ++GTI) { 526202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) { 527202375Srdivacky // Compute the aggregate offset of constant indices. 528202375Srdivacky if (CI->isZero()) continue; 529226890Sdim 530202375Srdivacky // Handle a struct index, which adds its field offset to the pointer. 531226890Sdim if (StructType *STy = dyn_cast<StructType>(*GTI)) { 532202375Srdivacky Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); 533202375Srdivacky } else { 534202375Srdivacky uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 535202375Srdivacky Offset += Size*CI->getSExtValue(); 536202375Srdivacky } 537202375Srdivacky } else { 538202375Srdivacky // Found our variable index. 539202375Srdivacky break; 540202375Srdivacky } 541202375Srdivacky } 542226890Sdim 543202375Srdivacky // If there are no variable indices, we must have a constant offset, just 544202375Srdivacky // evaluate it the general way. 545202375Srdivacky if (i == e) return 0; 546226890Sdim 547202375Srdivacky Value *VariableIdx = GEP->getOperand(i); 548202375Srdivacky // Determine the scale factor of the variable element. For example, this is 549202375Srdivacky // 4 if the variable index is into an array of i32. 550202375Srdivacky uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType()); 551226890Sdim 552202375Srdivacky // Verify that there are no other variable indices. If so, emit the hard way. 553202375Srdivacky for (++i, ++GTI; i != e; ++i, ++GTI) { 554202375Srdivacky ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i)); 555202375Srdivacky if (!CI) return 0; 556226890Sdim 557202375Srdivacky // Compute the aggregate offset of constant indices. 558202375Srdivacky if (CI->isZero()) continue; 559226890Sdim 560202375Srdivacky // Handle a struct index, which adds its field offset to the pointer. 561226890Sdim if (StructType *STy = dyn_cast<StructType>(*GTI)) { 562202375Srdivacky Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); 563202375Srdivacky } else { 564202375Srdivacky uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 565202375Srdivacky Offset += Size*CI->getSExtValue(); 566202375Srdivacky } 567202375Srdivacky } 568226890Sdim 569263509Sdim 570263509Sdim 571202375Srdivacky // Okay, we know we have a single variable index, which must be a 572202375Srdivacky // pointer/array/vector index. If there is no offset, life is simple, return 573202375Srdivacky // the index. 574263509Sdim Type *IntPtrTy = TD.getIntPtrType(GEP->getOperand(0)->getType()); 575263509Sdim unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth(); 576202375Srdivacky if (Offset == 0) { 577202375Srdivacky // Cast to intptrty in case a truncation occurs. If an extension is needed, 578202375Srdivacky // we don't need to bother extending: the extension won't affect where the 579202375Srdivacky // computation crosses zero. 580223017Sdim if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) { 581223017Sdim VariableIdx = IC.Builder->CreateTrunc(VariableIdx, IntPtrTy); 582223017Sdim } 583202375Srdivacky return VariableIdx; 584202375Srdivacky } 585226890Sdim 586202375Srdivacky // Otherwise, there is an index. The computation we will do will be modulo 587202375Srdivacky // the pointer size, so get it. 588202375Srdivacky uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth); 589226890Sdim 590202375Srdivacky Offset &= PtrSizeMask; 591202375Srdivacky VariableScale &= PtrSizeMask; 592226890Sdim 593202375Srdivacky // To do this transformation, any constant index must be a multiple of the 594202375Srdivacky // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i", 595202375Srdivacky // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a 596202375Srdivacky // multiple of the variable scale. 597202375Srdivacky int64_t NewOffs = Offset / (int64_t)VariableScale; 598202375Srdivacky if (Offset != NewOffs*(int64_t)VariableScale) 599202375Srdivacky return 0; 600226890Sdim 601202375Srdivacky // Okay, we can do this evaluation. Start by converting the index to intptr. 602202375Srdivacky if (VariableIdx->getType() != IntPtrTy) 603223017Sdim VariableIdx = IC.Builder->CreateIntCast(VariableIdx, IntPtrTy, 604223017Sdim true /*Signed*/); 605202375Srdivacky Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs); 606223017Sdim return IC.Builder->CreateAdd(VariableIdx, OffsetVal, "offset"); 607202375Srdivacky} 608202375Srdivacky 609202375Srdivacky/// FoldGEPICmp - Fold comparisons between a GEP instruction and something 610202375Srdivacky/// else. At this point we know that the GEP is on the LHS of the comparison. 611202375SrdivackyInstruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, 612202375Srdivacky ICmpInst::Predicate Cond, 613202375Srdivacky Instruction &I) { 614235633Sdim // Don't transform signed compares of GEPs into index compares. Even if the 615235633Sdim // GEP is inbounds, the final add of the base pointer can have signed overflow 616235633Sdim // and would change the result of the icmp. 617235633Sdim // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be 618235633Sdim // the maximum signed value for the pointer type. 619235633Sdim if (ICmpInst::isSigned(Cond)) 620235633Sdim return 0; 621235633Sdim 622202375Srdivacky // Look through bitcasts. 623202375Srdivacky if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS)) 624202375Srdivacky RHS = BCI->getOperand(0); 625202375Srdivacky 626202375Srdivacky Value *PtrBase = GEPLHS->getOperand(0); 627202375Srdivacky if (TD && PtrBase == RHS && GEPLHS->isInBounds()) { 628202375Srdivacky // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0). 629202375Srdivacky // This transformation (ignoring the base and scales) is valid because we 630202375Srdivacky // know pointers can't overflow since the gep is inbounds. See if we can 631202375Srdivacky // output an optimized form. 632223017Sdim Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, *this); 633226890Sdim 634202375Srdivacky // If not, synthesize the offset the hard way. 635202375Srdivacky if (Offset == 0) 636202375Srdivacky Offset = EmitGEPOffset(GEPLHS); 637202375Srdivacky return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset, 638202375Srdivacky Constant::getNullValue(Offset->getType())); 639202375Srdivacky } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) { 640202375Srdivacky // If the base pointers are different, but the indices are the same, just 641202375Srdivacky // compare the base pointer. 642202375Srdivacky if (PtrBase != GEPRHS->getOperand(0)) { 643202375Srdivacky bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands(); 644202375Srdivacky IndicesTheSame &= GEPLHS->getOperand(0)->getType() == 645202375Srdivacky GEPRHS->getOperand(0)->getType(); 646202375Srdivacky if (IndicesTheSame) 647202375Srdivacky for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) 648202375Srdivacky if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { 649202375Srdivacky IndicesTheSame = false; 650202375Srdivacky break; 651202375Srdivacky } 652202375Srdivacky 653202375Srdivacky // If all indices are the same, just compare the base pointers. 654202375Srdivacky if (IndicesTheSame) 655263509Sdim return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0)); 656202375Srdivacky 657235633Sdim // If we're comparing GEPs with two base pointers that only differ in type 658235633Sdim // and both GEPs have only constant indices or just one use, then fold 659235633Sdim // the compare with the adjusted indices. 660235633Sdim if (TD && GEPLHS->isInBounds() && GEPRHS->isInBounds() && 661235633Sdim (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) && 662235633Sdim (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) && 663235633Sdim PtrBase->stripPointerCasts() == 664235633Sdim GEPRHS->getOperand(0)->stripPointerCasts()) { 665235633Sdim Value *Cmp = Builder->CreateICmp(ICmpInst::getSignedPredicate(Cond), 666235633Sdim EmitGEPOffset(GEPLHS), 667235633Sdim EmitGEPOffset(GEPRHS)); 668235633Sdim return ReplaceInstUsesWith(I, Cmp); 669235633Sdim } 670235633Sdim 671202375Srdivacky // Otherwise, the base pointers are different and the indices are 672202375Srdivacky // different, bail out. 673202375Srdivacky return 0; 674202375Srdivacky } 675202375Srdivacky 676202375Srdivacky // If one of the GEPs has all zero indices, recurse. 677202375Srdivacky bool AllZeros = true; 678202375Srdivacky for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) 679202375Srdivacky if (!isa<Constant>(GEPLHS->getOperand(i)) || 680202375Srdivacky !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) { 681202375Srdivacky AllZeros = false; 682202375Srdivacky break; 683202375Srdivacky } 684202375Srdivacky if (AllZeros) 685202375Srdivacky return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0), 686263509Sdim ICmpInst::getSwappedPredicate(Cond), I); 687202375Srdivacky 688202375Srdivacky // If the other GEP has all zero indices, recurse. 689202375Srdivacky AllZeros = true; 690202375Srdivacky for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) 691202375Srdivacky if (!isa<Constant>(GEPRHS->getOperand(i)) || 692202375Srdivacky !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) { 693202375Srdivacky AllZeros = false; 694202375Srdivacky break; 695202375Srdivacky } 696202375Srdivacky if (AllZeros) 697202375Srdivacky return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I); 698202375Srdivacky 699223017Sdim bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds(); 700202375Srdivacky if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { 701202375Srdivacky // If the GEPs only differ by one index, compare it. 702202375Srdivacky unsigned NumDifferences = 0; // Keep track of # differences. 703202375Srdivacky unsigned DiffOperand = 0; // The operand that differs. 704202375Srdivacky for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) 705202375Srdivacky if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { 706202375Srdivacky if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() != 707202375Srdivacky GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) { 708202375Srdivacky // Irreconcilable differences. 709202375Srdivacky NumDifferences = 2; 710202375Srdivacky break; 711202375Srdivacky } else { 712202375Srdivacky if (NumDifferences++) break; 713202375Srdivacky DiffOperand = i; 714202375Srdivacky } 715202375Srdivacky } 716202375Srdivacky 717202375Srdivacky if (NumDifferences == 0) // SAME GEP? 718202375Srdivacky return ReplaceInstUsesWith(I, // No comparison is needed here. 719263509Sdim Builder->getInt1(ICmpInst::isTrueWhenEqual(Cond))); 720202375Srdivacky 721223017Sdim else if (NumDifferences == 1 && GEPsInBounds) { 722202375Srdivacky Value *LHSV = GEPLHS->getOperand(DiffOperand); 723202375Srdivacky Value *RHSV = GEPRHS->getOperand(DiffOperand); 724202375Srdivacky // Make sure we do a signed comparison here. 725202375Srdivacky return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV); 726202375Srdivacky } 727202375Srdivacky } 728202375Srdivacky 729202375Srdivacky // Only lower this if the icmp is the only user of the GEP or if we expect 730202375Srdivacky // the result to fold to a constant! 731202375Srdivacky if (TD && 732223017Sdim GEPsInBounds && 733202375Srdivacky (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) && 734202375Srdivacky (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) { 735202375Srdivacky // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) 736202375Srdivacky Value *L = EmitGEPOffset(GEPLHS); 737202375Srdivacky Value *R = EmitGEPOffset(GEPRHS); 738202375Srdivacky return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R); 739202375Srdivacky } 740202375Srdivacky } 741202375Srdivacky return 0; 742202375Srdivacky} 743202375Srdivacky 744202375Srdivacky/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X". 745263509SdimInstruction *InstCombiner::FoldICmpAddOpCst(Instruction &ICI, 746202375Srdivacky Value *X, ConstantInt *CI, 747263509Sdim ICmpInst::Predicate Pred) { 748202375Srdivacky // If we have X+0, exit early (simplifying logic below) and let it get folded 749202375Srdivacky // elsewhere. icmp X+0, X -> icmp X, X 750202375Srdivacky if (CI->isZero()) { 751202375Srdivacky bool isTrue = ICmpInst::isTrueWhenEqual(Pred); 752202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue)); 753202375Srdivacky } 754226890Sdim 755202375Srdivacky // (X+4) == X -> false. 756202375Srdivacky if (Pred == ICmpInst::ICMP_EQ) 757263509Sdim return ReplaceInstUsesWith(ICI, Builder->getFalse()); 758202375Srdivacky 759202375Srdivacky // (X+4) != X -> true. 760202375Srdivacky if (Pred == ICmpInst::ICMP_NE) 761263509Sdim return ReplaceInstUsesWith(ICI, Builder->getTrue()); 762202375Srdivacky 763202375Srdivacky // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0, 764221345Sdim // so the values can never be equal. Similarly for all other "or equals" 765202375Srdivacky // operators. 766226890Sdim 767202375Srdivacky // (X+1) <u X --> X >u (MAXUINT-1) --> X == 255 768202375Srdivacky // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253 769202375Srdivacky // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0 770202375Srdivacky if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { 771226890Sdim Value *R = 772202375Srdivacky ConstantExpr::getSub(ConstantInt::getAllOnesValue(CI->getType()), CI); 773202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGT, X, R); 774202375Srdivacky } 775226890Sdim 776202375Srdivacky // (X+1) >u X --> X <u (0-1) --> X != 255 777202375Srdivacky // (X+2) >u X --> X <u (0-2) --> X <u 254 778202375Srdivacky // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0 779218893Sdim if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) 780202375Srdivacky return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI)); 781226890Sdim 782202375Srdivacky unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits(); 783202375Srdivacky ConstantInt *SMax = ConstantInt::get(X->getContext(), 784202375Srdivacky APInt::getSignedMaxValue(BitWidth)); 785202375Srdivacky 786202375Srdivacky // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127 787202375Srdivacky // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125 788202375Srdivacky // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0 789202375Srdivacky // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1 790202375Srdivacky // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126 791202375Srdivacky // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127 792218893Sdim if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) 793202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI)); 794226890Sdim 795202375Srdivacky // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127 796202375Srdivacky // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126 797202375Srdivacky // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1 798202375Srdivacky // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2 799202375Srdivacky // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126 800202375Srdivacky // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128 801226890Sdim 802202375Srdivacky assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE); 803263509Sdim Constant *C = Builder->getInt(CI->getValue()-1); 804202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C)); 805202375Srdivacky} 806202375Srdivacky 807202375Srdivacky/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS 808202375Srdivacky/// and CmpRHS are both known to be integer constants. 809202375SrdivackyInstruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, 810202375Srdivacky ConstantInt *DivRHS) { 811202375Srdivacky ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1)); 812202375Srdivacky const APInt &CmpRHSV = CmpRHS->getValue(); 813226890Sdim 814226890Sdim // FIXME: If the operand types don't match the type of the divide 815202375Srdivacky // then don't attempt this transform. The code below doesn't have the 816202375Srdivacky // logic to deal with a signed divide and an unsigned compare (and 817226890Sdim // vice versa). This is because (x /s C1) <s C2 produces different 818202375Srdivacky // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even 819226890Sdim // (x /u C1) <u C2. Simply casting the operands and result won't 820226890Sdim // work. :( The if statement below tests that condition and bails 821218893Sdim // if it finds it. 822202375Srdivacky bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv; 823202375Srdivacky if (!ICI.isEquality() && DivIsSigned != ICI.isSigned()) 824202375Srdivacky return 0; 825202375Srdivacky if (DivRHS->isZero()) 826202375Srdivacky return 0; // The ProdOV computation fails on divide by zero. 827202375Srdivacky if (DivIsSigned && DivRHS->isAllOnesValue()) 828202375Srdivacky return 0; // The overflow computation also screws up here 829218893Sdim if (DivRHS->isOne()) { 830218893Sdim // This eliminates some funny cases with INT_MIN. 831218893Sdim ICI.setOperand(0, DivI->getOperand(0)); // X/1 == X. 832218893Sdim return &ICI; 833218893Sdim } 834202375Srdivacky 835202375Srdivacky // Compute Prod = CI * DivRHS. We are essentially solving an equation 836226890Sdim // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and 837226890Sdim // C2 (CI). By solving for X we can turn this into a range check 838226890Sdim // instead of computing a divide. 839202375Srdivacky Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS); 840202375Srdivacky 841202375Srdivacky // Determine if the product overflows by seeing if the product is 842202375Srdivacky // not equal to the divide. Make sure we do the same kind of divide 843226890Sdim // as in the LHS instruction that we're folding. 844202375Srdivacky bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) : 845202375Srdivacky ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS; 846202375Srdivacky 847202375Srdivacky // Get the ICmp opcode 848202375Srdivacky ICmpInst::Predicate Pred = ICI.getPredicate(); 849202375Srdivacky 850218893Sdim /// If the division is known to be exact, then there is no remainder from the 851218893Sdim /// divide, so the covered range size is unit, otherwise it is the divisor. 852218893Sdim ConstantInt *RangeSize = DivI->isExact() ? getOne(Prod) : DivRHS; 853226890Sdim 854202375Srdivacky // Figure out the interval that is being checked. For example, a comparison 855226890Sdim // like "X /u 5 == 0" is really checking that X is in the interval [0, 5). 856202375Srdivacky // Compute this interval based on the constants involved and the signedness of 857202375Srdivacky // the compare/divide. This computes a half-open interval, keeping track of 858202375Srdivacky // whether either value in the interval overflows. After analysis each 859202375Srdivacky // overflow variable is set to 0 if it's corresponding bound variable is valid 860202375Srdivacky // -1 if overflowed off the bottom end, or +1 if overflowed off the top end. 861202375Srdivacky int LoOverflow = 0, HiOverflow = 0; 862202375Srdivacky Constant *LoBound = 0, *HiBound = 0; 863218893Sdim 864202375Srdivacky if (!DivIsSigned) { // udiv 865202375Srdivacky // e.g. X/5 op 3 --> [15, 20) 866202375Srdivacky LoBound = Prod; 867202375Srdivacky HiOverflow = LoOverflow = ProdOV; 868218893Sdim if (!HiOverflow) { 869218893Sdim // If this is not an exact divide, then many values in the range collapse 870218893Sdim // to the same result value. 871218893Sdim HiOverflow = AddWithOverflow(HiBound, LoBound, RangeSize, false); 872218893Sdim } 873226890Sdim 874202375Srdivacky } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0. 875202375Srdivacky if (CmpRHSV == 0) { // (X / pos) op 0 876202375Srdivacky // Can't overflow. e.g. X/2 op 0 --> [-1, 2) 877218893Sdim LoBound = ConstantExpr::getNeg(SubOne(RangeSize)); 878218893Sdim HiBound = RangeSize; 879202375Srdivacky } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos 880202375Srdivacky LoBound = Prod; // e.g. X/5 op 3 --> [15, 20) 881202375Srdivacky HiOverflow = LoOverflow = ProdOV; 882202375Srdivacky if (!HiOverflow) 883218893Sdim HiOverflow = AddWithOverflow(HiBound, Prod, RangeSize, true); 884202375Srdivacky } else { // (X / pos) op neg 885202375Srdivacky // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14) 886202375Srdivacky HiBound = AddOne(Prod); 887202375Srdivacky LoOverflow = HiOverflow = ProdOV ? -1 : 0; 888202375Srdivacky if (!LoOverflow) { 889218893Sdim ConstantInt *DivNeg =cast<ConstantInt>(ConstantExpr::getNeg(RangeSize)); 890202375Srdivacky LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0; 891218893Sdim } 892202375Srdivacky } 893224145Sdim } else if (DivRHS->isNegative()) { // Divisor is < 0. 894218893Sdim if (DivI->isExact()) 895218893Sdim RangeSize = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize)); 896202375Srdivacky if (CmpRHSV == 0) { // (X / neg) op 0 897202375Srdivacky // e.g. X/-5 op 0 --> [-4, 5) 898218893Sdim LoBound = AddOne(RangeSize); 899218893Sdim HiBound = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize)); 900202375Srdivacky if (HiBound == DivRHS) { // -INTMIN = INTMIN 901202375Srdivacky HiOverflow = 1; // [INTMIN+1, overflow) 902202375Srdivacky HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN 903202375Srdivacky } 904202375Srdivacky } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos 905202375Srdivacky // e.g. X/-5 op 3 --> [-19, -14) 906202375Srdivacky HiBound = AddOne(Prod); 907202375Srdivacky HiOverflow = LoOverflow = ProdOV ? -1 : 0; 908202375Srdivacky if (!LoOverflow) 909218893Sdim LoOverflow = AddWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0; 910202375Srdivacky } else { // (X / neg) op neg 911202375Srdivacky LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20) 912202375Srdivacky LoOverflow = HiOverflow = ProdOV; 913202375Srdivacky if (!HiOverflow) 914218893Sdim HiOverflow = SubWithOverflow(HiBound, Prod, RangeSize, true); 915202375Srdivacky } 916226890Sdim 917202375Srdivacky // Dividing by a negative swaps the condition. LT <-> GT 918202375Srdivacky Pred = ICmpInst::getSwappedPredicate(Pred); 919202375Srdivacky } 920202375Srdivacky 921202375Srdivacky Value *X = DivI->getOperand(0); 922202375Srdivacky switch (Pred) { 923202375Srdivacky default: llvm_unreachable("Unhandled icmp opcode!"); 924202375Srdivacky case ICmpInst::ICMP_EQ: 925202375Srdivacky if (LoOverflow && HiOverflow) 926263509Sdim return ReplaceInstUsesWith(ICI, Builder->getFalse()); 927204792Srdivacky if (HiOverflow) 928202375Srdivacky return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : 929202375Srdivacky ICmpInst::ICMP_UGE, X, LoBound); 930204792Srdivacky if (LoOverflow) 931202375Srdivacky return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : 932202375Srdivacky ICmpInst::ICMP_ULT, X, HiBound); 933218893Sdim return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound, 934218893Sdim DivIsSigned, true)); 935202375Srdivacky case ICmpInst::ICMP_NE: 936202375Srdivacky if (LoOverflow && HiOverflow) 937263509Sdim return ReplaceInstUsesWith(ICI, Builder->getTrue()); 938204792Srdivacky if (HiOverflow) 939202375Srdivacky return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : 940202375Srdivacky ICmpInst::ICMP_ULT, X, LoBound); 941204792Srdivacky if (LoOverflow) 942202375Srdivacky return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : 943202375Srdivacky ICmpInst::ICMP_UGE, X, HiBound); 944204792Srdivacky return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound, 945204792Srdivacky DivIsSigned, false)); 946202375Srdivacky case ICmpInst::ICMP_ULT: 947202375Srdivacky case ICmpInst::ICMP_SLT: 948202375Srdivacky if (LoOverflow == +1) // Low bound is greater than input range. 949263509Sdim return ReplaceInstUsesWith(ICI, Builder->getTrue()); 950202375Srdivacky if (LoOverflow == -1) // Low bound is less than input range. 951263509Sdim return ReplaceInstUsesWith(ICI, Builder->getFalse()); 952202375Srdivacky return new ICmpInst(Pred, X, LoBound); 953202375Srdivacky case ICmpInst::ICMP_UGT: 954202375Srdivacky case ICmpInst::ICMP_SGT: 955202375Srdivacky if (HiOverflow == +1) // High bound greater than input range. 956263509Sdim return ReplaceInstUsesWith(ICI, Builder->getFalse()); 957218893Sdim if (HiOverflow == -1) // High bound less than input range. 958263509Sdim return ReplaceInstUsesWith(ICI, Builder->getTrue()); 959202375Srdivacky if (Pred == ICmpInst::ICMP_UGT) 960202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound); 961218893Sdim return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound); 962202375Srdivacky } 963202375Srdivacky} 964202375Srdivacky 965218893Sdim/// FoldICmpShrCst - Handle "icmp(([al]shr X, cst1), cst2)". 966218893SdimInstruction *InstCombiner::FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *Shr, 967218893Sdim ConstantInt *ShAmt) { 968218893Sdim const APInt &CmpRHSV = cast<ConstantInt>(ICI.getOperand(1))->getValue(); 969226890Sdim 970218893Sdim // Check that the shift amount is in range. If not, don't perform 971218893Sdim // undefined shifts. When the shift is visited it will be 972218893Sdim // simplified. 973218893Sdim uint32_t TypeBits = CmpRHSV.getBitWidth(); 974218893Sdim uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); 975218893Sdim if (ShAmtVal >= TypeBits || ShAmtVal == 0) 976218893Sdim return 0; 977226890Sdim 978218893Sdim if (!ICI.isEquality()) { 979218893Sdim // If we have an unsigned comparison and an ashr, we can't simplify this. 980218893Sdim // Similarly for signed comparisons with lshr. 981218893Sdim if (ICI.isSigned() != (Shr->getOpcode() == Instruction::AShr)) 982218893Sdim return 0; 983226890Sdim 984223017Sdim // Otherwise, all lshr and most exact ashr's are equivalent to a udiv/sdiv 985223017Sdim // by a power of 2. Since we already have logic to simplify these, 986223017Sdim // transform to div and then simplify the resultant comparison. 987218893Sdim if (Shr->getOpcode() == Instruction::AShr && 988223017Sdim (!Shr->isExact() || ShAmtVal == TypeBits - 1)) 989218893Sdim return 0; 990226890Sdim 991218893Sdim // Revisit the shift (to delete it). 992218893Sdim Worklist.Add(Shr); 993226890Sdim 994218893Sdim Constant *DivCst = 995218893Sdim ConstantInt::get(Shr->getType(), APInt::getOneBitSet(TypeBits, ShAmtVal)); 996226890Sdim 997218893Sdim Value *Tmp = 998218893Sdim Shr->getOpcode() == Instruction::AShr ? 999218893Sdim Builder->CreateSDiv(Shr->getOperand(0), DivCst, "", Shr->isExact()) : 1000218893Sdim Builder->CreateUDiv(Shr->getOperand(0), DivCst, "", Shr->isExact()); 1001226890Sdim 1002218893Sdim ICI.setOperand(0, Tmp); 1003226890Sdim 1004218893Sdim // If the builder folded the binop, just return it. 1005218893Sdim BinaryOperator *TheDiv = dyn_cast<BinaryOperator>(Tmp); 1006218893Sdim if (TheDiv == 0) 1007218893Sdim return &ICI; 1008226890Sdim 1009218893Sdim // Otherwise, fold this div/compare. 1010218893Sdim assert(TheDiv->getOpcode() == Instruction::SDiv || 1011218893Sdim TheDiv->getOpcode() == Instruction::UDiv); 1012226890Sdim 1013218893Sdim Instruction *Res = FoldICmpDivCst(ICI, TheDiv, cast<ConstantInt>(DivCst)); 1014218893Sdim assert(Res && "This div/cst should have folded!"); 1015218893Sdim return Res; 1016218893Sdim } 1017226890Sdim 1018226890Sdim 1019218893Sdim // If we are comparing against bits always shifted out, the 1020218893Sdim // comparison cannot succeed. 1021218893Sdim APInt Comp = CmpRHSV << ShAmtVal; 1022263509Sdim ConstantInt *ShiftedCmpRHS = Builder->getInt(Comp); 1023218893Sdim if (Shr->getOpcode() == Instruction::LShr) 1024218893Sdim Comp = Comp.lshr(ShAmtVal); 1025218893Sdim else 1026218893Sdim Comp = Comp.ashr(ShAmtVal); 1027226890Sdim 1028218893Sdim if (Comp != CmpRHSV) { // Comparing against a bit that we know is zero. 1029218893Sdim bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; 1030263509Sdim Constant *Cst = Builder->getInt1(IsICMP_NE); 1031218893Sdim return ReplaceInstUsesWith(ICI, Cst); 1032218893Sdim } 1033226890Sdim 1034218893Sdim // Otherwise, check to see if the bits shifted out are known to be zero. 1035218893Sdim // If so, we can compare against the unshifted value: 1036218893Sdim // (X & 4) >> 1 == 2 --> (X & 4) == 4. 1037218893Sdim if (Shr->hasOneUse() && Shr->isExact()) 1038218893Sdim return new ICmpInst(ICI.getPredicate(), Shr->getOperand(0), ShiftedCmpRHS); 1039226890Sdim 1040218893Sdim if (Shr->hasOneUse()) { 1041218893Sdim // Otherwise strength reduce the shift into an and. 1042218893Sdim APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); 1043263509Sdim Constant *Mask = Builder->getInt(Val); 1044226890Sdim 1045218893Sdim Value *And = Builder->CreateAnd(Shr->getOperand(0), 1046218893Sdim Mask, Shr->getName()+".mask"); 1047218893Sdim return new ICmpInst(ICI.getPredicate(), And, ShiftedCmpRHS); 1048218893Sdim } 1049218893Sdim return 0; 1050218893Sdim} 1051202375Srdivacky 1052218893Sdim 1053202375Srdivacky/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)". 1054202375Srdivacky/// 1055202375SrdivackyInstruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, 1056202375Srdivacky Instruction *LHSI, 1057202375Srdivacky ConstantInt *RHS) { 1058202375Srdivacky const APInt &RHSV = RHS->getValue(); 1059226890Sdim 1060202375Srdivacky switch (LHSI->getOpcode()) { 1061202375Srdivacky case Instruction::Trunc: 1062202375Srdivacky if (ICI.isEquality() && LHSI->hasOneUse()) { 1063202375Srdivacky // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all 1064202375Srdivacky // of the high bits truncated out of x are known. 1065202375Srdivacky unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(), 1066202375Srdivacky SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits(); 1067202375Srdivacky APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0); 1068235633Sdim ComputeMaskedBits(LHSI->getOperand(0), KnownZero, KnownOne); 1069226890Sdim 1070202375Srdivacky // If all the high bits are known, we can do this xform. 1071202375Srdivacky if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) { 1072202375Srdivacky // Pull in the high bits from known-ones set. 1073218893Sdim APInt NewRHS = RHS->getValue().zext(SrcBits); 1074245431Sdim NewRHS |= KnownOne & APInt::getHighBitsSet(SrcBits, SrcBits-DstBits); 1075202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), 1076263509Sdim Builder->getInt(NewRHS)); 1077202375Srdivacky } 1078202375Srdivacky } 1079202375Srdivacky break; 1080226890Sdim 1081202375Srdivacky case Instruction::Xor: // (icmp pred (xor X, XorCST), CI) 1082202375Srdivacky if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { 1083202375Srdivacky // If this is a comparison that tests the signbit (X < 0) or (x > -1), 1084202375Srdivacky // fold the xor. 1085202375Srdivacky if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) || 1086202375Srdivacky (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) { 1087202375Srdivacky Value *CompareVal = LHSI->getOperand(0); 1088226890Sdim 1089202375Srdivacky // If the sign bit of the XorCST is not set, there is no change to 1090202375Srdivacky // the operation, just stop using the Xor. 1091224145Sdim if (!XorCST->isNegative()) { 1092202375Srdivacky ICI.setOperand(0, CompareVal); 1093202375Srdivacky Worklist.Add(LHSI); 1094202375Srdivacky return &ICI; 1095202375Srdivacky } 1096226890Sdim 1097202375Srdivacky // Was the old condition true if the operand is positive? 1098202375Srdivacky bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT; 1099226890Sdim 1100202375Srdivacky // If so, the new one isn't. 1101202375Srdivacky isTrueIfPositive ^= true; 1102226890Sdim 1103202375Srdivacky if (isTrueIfPositive) 1104202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, 1105202375Srdivacky SubOne(RHS)); 1106202375Srdivacky else 1107202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, 1108202375Srdivacky AddOne(RHS)); 1109202375Srdivacky } 1110202375Srdivacky 1111202375Srdivacky if (LHSI->hasOneUse()) { 1112202375Srdivacky // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit)) 1113202375Srdivacky if (!ICI.isEquality() && XorCST->getValue().isSignBit()) { 1114202375Srdivacky const APInt &SignBit = XorCST->getValue(); 1115202375Srdivacky ICmpInst::Predicate Pred = ICI.isSigned() 1116202375Srdivacky ? ICI.getUnsignedPredicate() 1117202375Srdivacky : ICI.getSignedPredicate(); 1118202375Srdivacky return new ICmpInst(Pred, LHSI->getOperand(0), 1119263509Sdim Builder->getInt(RHSV ^ SignBit)); 1120202375Srdivacky } 1121202375Srdivacky 1122202375Srdivacky // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A) 1123224145Sdim if (!ICI.isEquality() && XorCST->isMaxValue(true)) { 1124202375Srdivacky const APInt &NotSignBit = XorCST->getValue(); 1125202375Srdivacky ICmpInst::Predicate Pred = ICI.isSigned() 1126202375Srdivacky ? ICI.getUnsignedPredicate() 1127202375Srdivacky : ICI.getSignedPredicate(); 1128202375Srdivacky Pred = ICI.getSwappedPredicate(Pred); 1129202375Srdivacky return new ICmpInst(Pred, LHSI->getOperand(0), 1130263509Sdim Builder->getInt(RHSV ^ NotSignBit)); 1131202375Srdivacky } 1132202375Srdivacky } 1133263509Sdim 1134263509Sdim // (icmp ugt (xor X, C), ~C) -> (icmp ult X, C) 1135263509Sdim // iff -C is a power of 2 1136263509Sdim if (ICI.getPredicate() == ICmpInst::ICMP_UGT && 1137263509Sdim XorCST->getValue() == ~RHSV && (RHSV + 1).isPowerOf2()) 1138263509Sdim return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), XorCST); 1139263509Sdim 1140263509Sdim // (icmp ult (xor X, C), -C) -> (icmp uge X, C) 1141263509Sdim // iff -C is a power of 2 1142263509Sdim if (ICI.getPredicate() == ICmpInst::ICMP_ULT && 1143263509Sdim XorCST->getValue() == -RHSV && RHSV.isPowerOf2()) 1144263509Sdim return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), XorCST); 1145202375Srdivacky } 1146202375Srdivacky break; 1147202375Srdivacky case Instruction::And: // (icmp pred (and X, AndCST), RHS) 1148202375Srdivacky if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) && 1149202375Srdivacky LHSI->getOperand(0)->hasOneUse()) { 1150202375Srdivacky ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1)); 1151226890Sdim 1152202375Srdivacky // If the LHS is an AND of a truncating cast, we can widen the 1153202375Srdivacky // and/compare to be the input width without changing the value 1154202375Srdivacky // produced, eliminating a cast. 1155202375Srdivacky if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) { 1156202375Srdivacky // We can do this transformation if either the AND constant does not 1157226890Sdim // have its sign bit set or if it is an equality comparison. 1158202375Srdivacky // Extending a relational comparison when we're checking the sign 1159202375Srdivacky // bit would not work. 1160224145Sdim if (ICI.isEquality() || 1161224145Sdim (!AndCST->isNegative() && RHSV.isNonNegative())) { 1162224145Sdim Value *NewAnd = 1163202375Srdivacky Builder->CreateAnd(Cast->getOperand(0), 1164224145Sdim ConstantExpr::getZExt(AndCST, Cast->getSrcTy())); 1165224145Sdim NewAnd->takeName(LHSI); 1166202375Srdivacky return new ICmpInst(ICI.getPredicate(), NewAnd, 1167224145Sdim ConstantExpr::getZExt(RHS, Cast->getSrcTy())); 1168202375Srdivacky } 1169202375Srdivacky } 1170224145Sdim 1171224145Sdim // If the LHS is an AND of a zext, and we have an equality compare, we can 1172224145Sdim // shrink the and/compare to the smaller type, eliminating the cast. 1173224145Sdim if (ZExtInst *Cast = dyn_cast<ZExtInst>(LHSI->getOperand(0))) { 1174226890Sdim IntegerType *Ty = cast<IntegerType>(Cast->getSrcTy()); 1175224145Sdim // Make sure we don't compare the upper bits, SimplifyDemandedBits 1176224145Sdim // should fold the icmp to true/false in that case. 1177224145Sdim if (ICI.isEquality() && RHSV.getActiveBits() <= Ty->getBitWidth()) { 1178224145Sdim Value *NewAnd = 1179224145Sdim Builder->CreateAnd(Cast->getOperand(0), 1180224145Sdim ConstantExpr::getTrunc(AndCST, Ty)); 1181224145Sdim NewAnd->takeName(LHSI); 1182224145Sdim return new ICmpInst(ICI.getPredicate(), NewAnd, 1183224145Sdim ConstantExpr::getTrunc(RHS, Ty)); 1184224145Sdim } 1185224145Sdim } 1186224145Sdim 1187202375Srdivacky // If this is: (X >> C1) & C2 != C3 (where any shift and any compare 1188202375Srdivacky // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This 1189202375Srdivacky // happens a LOT in code produced by the C front-end, for bitfield 1190202375Srdivacky // access. 1191202375Srdivacky BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0)); 1192202375Srdivacky if (Shift && !Shift->isShift()) 1193202375Srdivacky Shift = 0; 1194226890Sdim 1195202375Srdivacky ConstantInt *ShAmt; 1196202375Srdivacky ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0; 1197226890Sdim Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift. 1198226890Sdim Type *AndTy = AndCST->getType(); // Type of the and. 1199226890Sdim 1200202375Srdivacky // We can fold this as long as we can't shift unknown bits 1201263509Sdim // into the mask. This can happen with signed shift 1202263509Sdim // rights, as they sign-extend. With logical shifts, 1203263509Sdim // we must still make sure the comparison is not signed 1204263509Sdim // because we are effectively changing the 1205263509Sdim // position of the sign bit (PR17827). 1206263509Sdim // TODO: We can relax these constraints a bit more. 1207202375Srdivacky if (ShAmt) { 1208263509Sdim bool CanFold = false; 1209263509Sdim unsigned ShiftOpcode = Shift->getOpcode(); 1210263509Sdim if (ShiftOpcode == Instruction::AShr) { 1211202375Srdivacky // To test for the bad case of the signed shr, see if any 1212202375Srdivacky // of the bits shifted in could be tested after the mask. 1213202375Srdivacky uint32_t TyBits = Ty->getPrimitiveSizeInBits(); 1214202375Srdivacky int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits); 1215226890Sdim 1216202375Srdivacky uint32_t BitWidth = AndTy->getPrimitiveSizeInBits(); 1217226890Sdim if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) & 1218202375Srdivacky AndCST->getValue()) == 0) 1219202375Srdivacky CanFold = true; 1220263509Sdim } else if (ShiftOpcode == Instruction::Shl || 1221263509Sdim ShiftOpcode == Instruction::LShr) { 1222263509Sdim CanFold = !ICI.isSigned(); 1223202375Srdivacky } 1224226890Sdim 1225202375Srdivacky if (CanFold) { 1226202375Srdivacky Constant *NewCst; 1227202375Srdivacky if (Shift->getOpcode() == Instruction::Shl) 1228202375Srdivacky NewCst = ConstantExpr::getLShr(RHS, ShAmt); 1229202375Srdivacky else 1230202375Srdivacky NewCst = ConstantExpr::getShl(RHS, ShAmt); 1231226890Sdim 1232202375Srdivacky // Check to see if we are shifting out any of the bits being 1233202375Srdivacky // compared. 1234202375Srdivacky if (ConstantExpr::get(Shift->getOpcode(), 1235202375Srdivacky NewCst, ShAmt) != RHS) { 1236202375Srdivacky // If we shifted bits out, the fold is not going to work out. 1237202375Srdivacky // As a special case, check to see if this means that the 1238202375Srdivacky // result is always true or false now. 1239202375Srdivacky if (ICI.getPredicate() == ICmpInst::ICMP_EQ) 1240263509Sdim return ReplaceInstUsesWith(ICI, Builder->getFalse()); 1241202375Srdivacky if (ICI.getPredicate() == ICmpInst::ICMP_NE) 1242263509Sdim return ReplaceInstUsesWith(ICI, Builder->getTrue()); 1243202375Srdivacky } else { 1244202375Srdivacky ICI.setOperand(1, NewCst); 1245202375Srdivacky Constant *NewAndCST; 1246202375Srdivacky if (Shift->getOpcode() == Instruction::Shl) 1247202375Srdivacky NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt); 1248202375Srdivacky else 1249202375Srdivacky NewAndCST = ConstantExpr::getShl(AndCST, ShAmt); 1250202375Srdivacky LHSI->setOperand(1, NewAndCST); 1251202375Srdivacky LHSI->setOperand(0, Shift->getOperand(0)); 1252202375Srdivacky Worklist.Add(Shift); // Shift is dead. 1253202375Srdivacky return &ICI; 1254202375Srdivacky } 1255202375Srdivacky } 1256202375Srdivacky } 1257226890Sdim 1258202375Srdivacky // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is 1259202375Srdivacky // preferable because it allows the C<<Y expression to be hoisted out 1260202375Srdivacky // of a loop if Y is invariant and X is not. 1261202375Srdivacky if (Shift && Shift->hasOneUse() && RHSV == 0 && 1262202375Srdivacky ICI.isEquality() && !Shift->isArithmeticShift() && 1263202375Srdivacky !isa<Constant>(Shift->getOperand(0))) { 1264202375Srdivacky // Compute C << Y. 1265202375Srdivacky Value *NS; 1266202375Srdivacky if (Shift->getOpcode() == Instruction::LShr) { 1267226890Sdim NS = Builder->CreateShl(AndCST, Shift->getOperand(1)); 1268202375Srdivacky } else { 1269202375Srdivacky // Insert a logical shift. 1270226890Sdim NS = Builder->CreateLShr(AndCST, Shift->getOperand(1)); 1271202375Srdivacky } 1272226890Sdim 1273202375Srdivacky // Compute X & (C << Y). 1274226890Sdim Value *NewAnd = 1275202375Srdivacky Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName()); 1276226890Sdim 1277202375Srdivacky ICI.setOperand(0, NewAnd); 1278202375Srdivacky return &ICI; 1279202375Srdivacky } 1280252723Sdim 1281252723Sdim // Replace ((X & AndCST) > RHSV) with ((X & AndCST) != 0), if any 1282252723Sdim // bit set in (X & AndCST) will produce a result greater than RHSV. 1283252723Sdim if (ICI.getPredicate() == ICmpInst::ICMP_UGT) { 1284252723Sdim unsigned NTZ = AndCST->getValue().countTrailingZeros(); 1285252723Sdim if ((NTZ < AndCST->getBitWidth()) && 1286252723Sdim APInt::getOneBitSet(AndCST->getBitWidth(), NTZ).ugt(RHSV)) 1287252723Sdim return new ICmpInst(ICmpInst::ICMP_NE, LHSI, 1288252723Sdim Constant::getNullValue(RHS->getType())); 1289252723Sdim } 1290202375Srdivacky } 1291226890Sdim 1292202375Srdivacky // Try to optimize things like "A[i]&42 == 0" to index computations. 1293202375Srdivacky if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) { 1294202375Srdivacky if (GetElementPtrInst *GEP = 1295202375Srdivacky dyn_cast<GetElementPtrInst>(LI->getOperand(0))) 1296202375Srdivacky if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) 1297202375Srdivacky if (GV->isConstant() && GV->hasDefinitiveInitializer() && 1298202375Srdivacky !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) { 1299202375Srdivacky ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1)); 1300202375Srdivacky if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C)) 1301202375Srdivacky return Res; 1302202375Srdivacky } 1303202375Srdivacky } 1304263509Sdim 1305263509Sdim // X & -C == -C -> X > u ~C 1306263509Sdim // X & -C != -C -> X <= u ~C 1307263509Sdim // iff C is a power of 2 1308263509Sdim if (ICI.isEquality() && RHS == LHSI->getOperand(1) && (-RHSV).isPowerOf2()) 1309263509Sdim return new ICmpInst( 1310263509Sdim ICI.getPredicate() == ICmpInst::ICMP_EQ ? ICmpInst::ICMP_UGT 1311263509Sdim : ICmpInst::ICMP_ULE, 1312263509Sdim LHSI->getOperand(0), SubOne(RHS)); 1313202375Srdivacky break; 1314202375Srdivacky 1315202375Srdivacky case Instruction::Or: { 1316202375Srdivacky if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse()) 1317202375Srdivacky break; 1318202375Srdivacky Value *P, *Q; 1319202375Srdivacky if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) { 1320202375Srdivacky // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0 1321202375Srdivacky // -> and (icmp eq P, null), (icmp eq Q, null). 1322202375Srdivacky Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P, 1323202375Srdivacky Constant::getNullValue(P->getType())); 1324202375Srdivacky Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q, 1325202375Srdivacky Constant::getNullValue(Q->getType())); 1326202375Srdivacky Instruction *Op; 1327202375Srdivacky if (ICI.getPredicate() == ICmpInst::ICMP_EQ) 1328202375Srdivacky Op = BinaryOperator::CreateAnd(ICIP, ICIQ); 1329202375Srdivacky else 1330202375Srdivacky Op = BinaryOperator::CreateOr(ICIP, ICIQ); 1331202375Srdivacky return Op; 1332202375Srdivacky } 1333202375Srdivacky break; 1334202375Srdivacky } 1335226890Sdim 1336252723Sdim case Instruction::Mul: { // (icmp pred (mul X, Val), CI) 1337252723Sdim ConstantInt *Val = dyn_cast<ConstantInt>(LHSI->getOperand(1)); 1338252723Sdim if (!Val) break; 1339252723Sdim 1340252723Sdim // If this is a signed comparison to 0 and the mul is sign preserving, 1341252723Sdim // use the mul LHS operand instead. 1342252723Sdim ICmpInst::Predicate pred = ICI.getPredicate(); 1343252723Sdim if (isSignTest(pred, RHS) && !Val->isZero() && 1344252723Sdim cast<BinaryOperator>(LHSI)->hasNoSignedWrap()) 1345252723Sdim return new ICmpInst(Val->isNegative() ? 1346252723Sdim ICmpInst::getSwappedPredicate(pred) : pred, 1347252723Sdim LHSI->getOperand(0), 1348252723Sdim Constant::getNullValue(RHS->getType())); 1349252723Sdim 1350252723Sdim break; 1351252723Sdim } 1352252723Sdim 1353202375Srdivacky case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI) 1354263509Sdim uint32_t TypeBits = RHSV.getBitWidth(); 1355202375Srdivacky ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1)); 1356263509Sdim if (!ShAmt) { 1357263509Sdim Value *X; 1358263509Sdim // (1 << X) pred P2 -> X pred Log2(P2) 1359263509Sdim if (match(LHSI, m_Shl(m_One(), m_Value(X)))) { 1360263509Sdim bool RHSVIsPowerOf2 = RHSV.isPowerOf2(); 1361263509Sdim ICmpInst::Predicate Pred = ICI.getPredicate(); 1362263509Sdim if (ICI.isUnsigned()) { 1363263509Sdim if (!RHSVIsPowerOf2) { 1364263509Sdim // (1 << X) < 30 -> X <= 4 1365263509Sdim // (1 << X) <= 30 -> X <= 4 1366263509Sdim // (1 << X) >= 30 -> X > 4 1367263509Sdim // (1 << X) > 30 -> X > 4 1368263509Sdim if (Pred == ICmpInst::ICMP_ULT) 1369263509Sdim Pred = ICmpInst::ICMP_ULE; 1370263509Sdim else if (Pred == ICmpInst::ICMP_UGE) 1371263509Sdim Pred = ICmpInst::ICMP_UGT; 1372263509Sdim } 1373263509Sdim unsigned RHSLog2 = RHSV.logBase2(); 1374226890Sdim 1375263509Sdim // (1 << X) >= 2147483648 -> X >= 31 -> X == 31 1376263509Sdim // (1 << X) > 2147483648 -> X > 31 -> false 1377263509Sdim // (1 << X) <= 2147483648 -> X <= 31 -> true 1378263509Sdim // (1 << X) < 2147483648 -> X < 31 -> X != 31 1379263509Sdim if (RHSLog2 == TypeBits-1) { 1380263509Sdim if (Pred == ICmpInst::ICMP_UGE) 1381263509Sdim Pred = ICmpInst::ICMP_EQ; 1382263509Sdim else if (Pred == ICmpInst::ICMP_UGT) 1383263509Sdim return ReplaceInstUsesWith(ICI, Builder->getFalse()); 1384263509Sdim else if (Pred == ICmpInst::ICMP_ULE) 1385263509Sdim return ReplaceInstUsesWith(ICI, Builder->getTrue()); 1386263509Sdim else if (Pred == ICmpInst::ICMP_ULT) 1387263509Sdim Pred = ICmpInst::ICMP_NE; 1388263509Sdim } 1389226890Sdim 1390263509Sdim return new ICmpInst(Pred, X, 1391263509Sdim ConstantInt::get(RHS->getType(), RHSLog2)); 1392263509Sdim } else if (ICI.isSigned()) { 1393263509Sdim if (RHSV.isAllOnesValue()) { 1394263509Sdim // (1 << X) <= -1 -> X == 31 1395263509Sdim if (Pred == ICmpInst::ICMP_SLE) 1396263509Sdim return new ICmpInst(ICmpInst::ICMP_EQ, X, 1397263509Sdim ConstantInt::get(RHS->getType(), TypeBits-1)); 1398263509Sdim 1399263509Sdim // (1 << X) > -1 -> X != 31 1400263509Sdim if (Pred == ICmpInst::ICMP_SGT) 1401263509Sdim return new ICmpInst(ICmpInst::ICMP_NE, X, 1402263509Sdim ConstantInt::get(RHS->getType(), TypeBits-1)); 1403263509Sdim } else if (!RHSV) { 1404263509Sdim // (1 << X) < 0 -> X == 31 1405263509Sdim // (1 << X) <= 0 -> X == 31 1406263509Sdim if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) 1407263509Sdim return new ICmpInst(ICmpInst::ICMP_EQ, X, 1408263509Sdim ConstantInt::get(RHS->getType(), TypeBits-1)); 1409263509Sdim 1410263509Sdim // (1 << X) >= 0 -> X != 31 1411263509Sdim // (1 << X) > 0 -> X != 31 1412263509Sdim if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) 1413263509Sdim return new ICmpInst(ICmpInst::ICMP_NE, X, 1414263509Sdim ConstantInt::get(RHS->getType(), TypeBits-1)); 1415263509Sdim } 1416263509Sdim } else if (ICI.isEquality()) { 1417263509Sdim if (RHSVIsPowerOf2) 1418263509Sdim return new ICmpInst( 1419263509Sdim Pred, X, ConstantInt::get(RHS->getType(), RHSV.logBase2())); 1420263509Sdim 1421263509Sdim return ReplaceInstUsesWith( 1422263509Sdim ICI, Pred == ICmpInst::ICMP_EQ ? Builder->getFalse() 1423263509Sdim : Builder->getTrue()); 1424263509Sdim } 1425263509Sdim } 1426263509Sdim break; 1427263509Sdim } 1428263509Sdim 1429202375Srdivacky // Check that the shift amount is in range. If not, don't perform 1430202375Srdivacky // undefined shifts. When the shift is visited it will be 1431202375Srdivacky // simplified. 1432202375Srdivacky if (ShAmt->uge(TypeBits)) 1433202375Srdivacky break; 1434226890Sdim 1435202375Srdivacky if (ICI.isEquality()) { 1436202375Srdivacky // If we are comparing against bits always shifted out, the 1437202375Srdivacky // comparison cannot succeed. 1438202375Srdivacky Constant *Comp = 1439202375Srdivacky ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), 1440202375Srdivacky ShAmt); 1441202375Srdivacky if (Comp != RHS) {// Comparing against a bit that we know is zero. 1442202375Srdivacky bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; 1443263509Sdim Constant *Cst = Builder->getInt1(IsICMP_NE); 1444202375Srdivacky return ReplaceInstUsesWith(ICI, Cst); 1445202375Srdivacky } 1446226890Sdim 1447218893Sdim // If the shift is NUW, then it is just shifting out zeros, no need for an 1448218893Sdim // AND. 1449218893Sdim if (cast<BinaryOperator>(LHSI)->hasNoUnsignedWrap()) 1450218893Sdim return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), 1451218893Sdim ConstantExpr::getLShr(RHS, ShAmt)); 1452226890Sdim 1453252723Sdim // If the shift is NSW and we compare to 0, then it is just shifting out 1454252723Sdim // sign bits, no need for an AND either. 1455252723Sdim if (cast<BinaryOperator>(LHSI)->hasNoSignedWrap() && RHSV == 0) 1456252723Sdim return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), 1457252723Sdim ConstantExpr::getLShr(RHS, ShAmt)); 1458252723Sdim 1459202375Srdivacky if (LHSI->hasOneUse()) { 1460202375Srdivacky // Otherwise strength reduce the shift into an and. 1461202375Srdivacky uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); 1462263509Sdim Constant *Mask = Builder->getInt(APInt::getLowBitsSet(TypeBits, 1463263509Sdim TypeBits - ShAmtVal)); 1464226890Sdim 1465202375Srdivacky Value *And = 1466202375Srdivacky Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask"); 1467202375Srdivacky return new ICmpInst(ICI.getPredicate(), And, 1468218893Sdim ConstantExpr::getLShr(RHS, ShAmt)); 1469202375Srdivacky } 1470202375Srdivacky } 1471226890Sdim 1472252723Sdim // If this is a signed comparison to 0 and the shift is sign preserving, 1473252723Sdim // use the shift LHS operand instead. 1474252723Sdim ICmpInst::Predicate pred = ICI.getPredicate(); 1475252723Sdim if (isSignTest(pred, RHS) && 1476252723Sdim cast<BinaryOperator>(LHSI)->hasNoSignedWrap()) 1477252723Sdim return new ICmpInst(pred, 1478252723Sdim LHSI->getOperand(0), 1479252723Sdim Constant::getNullValue(RHS->getType())); 1480252723Sdim 1481202375Srdivacky // Otherwise, if this is a comparison of the sign bit, simplify to and/test. 1482202375Srdivacky bool TrueIfSigned = false; 1483202375Srdivacky if (LHSI->hasOneUse() && 1484202375Srdivacky isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) { 1485202375Srdivacky // (X << 31) <s 0 --> (X&1) != 0 1486218893Sdim Constant *Mask = ConstantInt::get(LHSI->getOperand(0)->getType(), 1487226890Sdim APInt::getOneBitSet(TypeBits, 1488218893Sdim TypeBits-ShAmt->getZExtValue()-1)); 1489202375Srdivacky Value *And = 1490202375Srdivacky Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask"); 1491202375Srdivacky return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ, 1492202375Srdivacky And, Constant::getNullValue(And->getType())); 1493202375Srdivacky } 1494252723Sdim 1495252723Sdim // Transform (icmp pred iM (shl iM %v, N), CI) 1496252723Sdim // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (CI>>N)) 1497252723Sdim // Transform the shl to a trunc if (trunc (CI>>N)) has no loss and M-N. 1498252723Sdim // This enables to get rid of the shift in favor of a trunc which can be 1499252723Sdim // free on the target. It has the additional benefit of comparing to a 1500252723Sdim // smaller constant, which will be target friendly. 1501252723Sdim unsigned Amt = ShAmt->getLimitedValue(TypeBits-1); 1502252723Sdim if (LHSI->hasOneUse() && 1503252723Sdim Amt != 0 && RHSV.countTrailingZeros() >= Amt) { 1504252723Sdim Type *NTy = IntegerType::get(ICI.getContext(), TypeBits - Amt); 1505252723Sdim Constant *NCI = ConstantExpr::getTrunc( 1506252723Sdim ConstantExpr::getAShr(RHS, 1507252723Sdim ConstantInt::get(RHS->getType(), Amt)), 1508252723Sdim NTy); 1509252723Sdim return new ICmpInst(ICI.getPredicate(), 1510252723Sdim Builder->CreateTrunc(LHSI->getOperand(0), NTy), 1511252723Sdim NCI); 1512252723Sdim } 1513252723Sdim 1514202375Srdivacky break; 1515202375Srdivacky } 1516226890Sdim 1517202375Srdivacky case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI) 1518221345Sdim case Instruction::AShr: { 1519221345Sdim // Handle equality comparisons of shift-by-constant. 1520221345Sdim BinaryOperator *BO = cast<BinaryOperator>(LHSI); 1521221345Sdim if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { 1522221345Sdim if (Instruction *Res = FoldICmpShrCst(ICI, BO, ShAmt)) 1523218893Sdim return Res; 1524221345Sdim } 1525221345Sdim 1526221345Sdim // Handle exact shr's. 1527221345Sdim if (ICI.isEquality() && BO->isExact() && BO->hasOneUse()) { 1528221345Sdim if (RHSV.isMinValue()) 1529221345Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), RHS); 1530221345Sdim } 1531202375Srdivacky break; 1532221345Sdim } 1533226890Sdim 1534202375Srdivacky case Instruction::SDiv: 1535202375Srdivacky case Instruction::UDiv: 1536202375Srdivacky // Fold: icmp pred ([us]div X, C1), C2 -> range test 1537226890Sdim // Fold this div into the comparison, producing a range check. 1538226890Sdim // Determine, based on the divide type, what the range is being 1539226890Sdim // checked. If there is an overflow on the low or high side, remember 1540202375Srdivacky // it, otherwise compute the range [low, hi) bounding the new value. 1541202375Srdivacky // See: InsertRangeTest above for the kinds of replacements possible. 1542202375Srdivacky if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) 1543202375Srdivacky if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI), 1544202375Srdivacky DivRHS)) 1545202375Srdivacky return R; 1546202375Srdivacky break; 1547202375Srdivacky 1548263509Sdim case Instruction::Sub: { 1549263509Sdim ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(0)); 1550263509Sdim if (!LHSC) break; 1551263509Sdim const APInt &LHSV = LHSC->getValue(); 1552263509Sdim 1553263509Sdim // C1-X <u C2 -> (X|(C2-1)) == C1 1554263509Sdim // iff C1 & (C2-1) == C2-1 1555263509Sdim // C2 is a power of 2 1556263509Sdim if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() && 1557263509Sdim RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == (RHSV - 1)) 1558263509Sdim return new ICmpInst(ICmpInst::ICMP_EQ, 1559263509Sdim Builder->CreateOr(LHSI->getOperand(1), RHSV - 1), 1560263509Sdim LHSC); 1561263509Sdim 1562263509Sdim // C1-X >u C2 -> (X|C2) != C1 1563263509Sdim // iff C1 & C2 == C2 1564263509Sdim // C2+1 is a power of 2 1565263509Sdim if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() && 1566263509Sdim (RHSV + 1).isPowerOf2() && (LHSV & RHSV) == RHSV) 1567263509Sdim return new ICmpInst(ICmpInst::ICMP_NE, 1568263509Sdim Builder->CreateOr(LHSI->getOperand(1), RHSV), LHSC); 1569263509Sdim break; 1570263509Sdim } 1571263509Sdim 1572202375Srdivacky case Instruction::Add: 1573202375Srdivacky // Fold: icmp pred (add X, C1), C2 1574202375Srdivacky if (!ICI.isEquality()) { 1575202375Srdivacky ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1)); 1576202375Srdivacky if (!LHSC) break; 1577202375Srdivacky const APInt &LHSV = LHSC->getValue(); 1578202375Srdivacky 1579202375Srdivacky ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV) 1580202375Srdivacky .subtract(LHSV); 1581202375Srdivacky 1582202375Srdivacky if (ICI.isSigned()) { 1583202375Srdivacky if (CR.getLower().isSignBit()) { 1584202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0), 1585263509Sdim Builder->getInt(CR.getUpper())); 1586202375Srdivacky } else if (CR.getUpper().isSignBit()) { 1587202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0), 1588263509Sdim Builder->getInt(CR.getLower())); 1589202375Srdivacky } 1590202375Srdivacky } else { 1591202375Srdivacky if (CR.getLower().isMinValue()) { 1592202375Srdivacky return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), 1593263509Sdim Builder->getInt(CR.getUpper())); 1594202375Srdivacky } else if (CR.getUpper().isMinValue()) { 1595202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), 1596263509Sdim Builder->getInt(CR.getLower())); 1597202375Srdivacky } 1598202375Srdivacky } 1599263509Sdim 1600263509Sdim // X-C1 <u C2 -> (X & -C2) == C1 1601263509Sdim // iff C1 & (C2-1) == 0 1602263509Sdim // C2 is a power of 2 1603263509Sdim if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() && 1604263509Sdim RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == 0) 1605263509Sdim return new ICmpInst(ICmpInst::ICMP_EQ, 1606263509Sdim Builder->CreateAnd(LHSI->getOperand(0), -RHSV), 1607263509Sdim ConstantExpr::getNeg(LHSC)); 1608263509Sdim 1609263509Sdim // X-C1 >u C2 -> (X & ~C2) != C1 1610263509Sdim // iff C1 & C2 == 0 1611263509Sdim // C2+1 is a power of 2 1612263509Sdim if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() && 1613263509Sdim (RHSV + 1).isPowerOf2() && (LHSV & RHSV) == 0) 1614263509Sdim return new ICmpInst(ICmpInst::ICMP_NE, 1615263509Sdim Builder->CreateAnd(LHSI->getOperand(0), ~RHSV), 1616263509Sdim ConstantExpr::getNeg(LHSC)); 1617202375Srdivacky } 1618202375Srdivacky break; 1619202375Srdivacky } 1620226890Sdim 1621202375Srdivacky // Simplify icmp_eq and icmp_ne instructions with integer constant RHS. 1622202375Srdivacky if (ICI.isEquality()) { 1623202375Srdivacky bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; 1624226890Sdim 1625226890Sdim // If the first operand is (add|sub|and|or|xor|rem) with a constant, and 1626202375Srdivacky // the second operand is a constant, simplify a bit. 1627202375Srdivacky if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) { 1628202375Srdivacky switch (BO->getOpcode()) { 1629202375Srdivacky case Instruction::SRem: 1630202375Srdivacky // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. 1631202375Srdivacky if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){ 1632202375Srdivacky const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue(); 1633207618Srdivacky if (V.sgt(1) && V.isPowerOf2()) { 1634202375Srdivacky Value *NewRem = 1635202375Srdivacky Builder->CreateURem(BO->getOperand(0), BO->getOperand(1), 1636202375Srdivacky BO->getName()); 1637202375Srdivacky return new ICmpInst(ICI.getPredicate(), NewRem, 1638202375Srdivacky Constant::getNullValue(BO->getType())); 1639202375Srdivacky } 1640202375Srdivacky } 1641202375Srdivacky break; 1642202375Srdivacky case Instruction::Add: 1643202375Srdivacky // Replace ((add A, B) != C) with (A != C-B) if B & C are constants. 1644202375Srdivacky if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) { 1645202375Srdivacky if (BO->hasOneUse()) 1646202375Srdivacky return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1647202375Srdivacky ConstantExpr::getSub(RHS, BOp1C)); 1648202375Srdivacky } else if (RHSV == 0) { 1649202375Srdivacky // Replace ((add A, B) != 0) with (A != -B) if A or B is 1650202375Srdivacky // efficiently invertible, or if the add has just this one use. 1651202375Srdivacky Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1); 1652226890Sdim 1653202375Srdivacky if (Value *NegVal = dyn_castNegVal(BOp1)) 1654202375Srdivacky return new ICmpInst(ICI.getPredicate(), BOp0, NegVal); 1655221345Sdim if (Value *NegVal = dyn_castNegVal(BOp0)) 1656202375Srdivacky return new ICmpInst(ICI.getPredicate(), NegVal, BOp1); 1657221345Sdim if (BO->hasOneUse()) { 1658202375Srdivacky Value *Neg = Builder->CreateNeg(BOp1); 1659202375Srdivacky Neg->takeName(BO); 1660202375Srdivacky return new ICmpInst(ICI.getPredicate(), BOp0, Neg); 1661202375Srdivacky } 1662202375Srdivacky } 1663202375Srdivacky break; 1664202375Srdivacky case Instruction::Xor: 1665202375Srdivacky // For the xor case, we can xor two constants together, eliminating 1666202375Srdivacky // the explicit xor. 1667224145Sdim if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) { 1668224145Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1669202375Srdivacky ConstantExpr::getXor(RHS, BOC)); 1670224145Sdim } else if (RHSV == 0) { 1671224145Sdim // Replace ((xor A, B) != 0) with (A != B) 1672224145Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1673224145Sdim BO->getOperand(1)); 1674224145Sdim } 1675224145Sdim break; 1676202375Srdivacky case Instruction::Sub: 1677224145Sdim // Replace ((sub A, B) != C) with (B != A-C) if A & C are constants. 1678224145Sdim if (ConstantInt *BOp0C = dyn_cast<ConstantInt>(BO->getOperand(0))) { 1679224145Sdim if (BO->hasOneUse()) 1680224145Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(1), 1681224145Sdim ConstantExpr::getSub(BOp0C, RHS)); 1682224145Sdim } else if (RHSV == 0) { 1683224145Sdim // Replace ((sub A, B) != 0) with (A != B) 1684202375Srdivacky return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1685202375Srdivacky BO->getOperand(1)); 1686224145Sdim } 1687202375Srdivacky break; 1688202375Srdivacky case Instruction::Or: 1689202375Srdivacky // If bits are being or'd in that are not present in the constant we 1690202375Srdivacky // are comparing against, then the comparison could never succeed! 1691212904Sdim if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { 1692202375Srdivacky Constant *NotCI = ConstantExpr::getNot(RHS); 1693202375Srdivacky if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue()) 1694263509Sdim return ReplaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE)); 1695202375Srdivacky } 1696202375Srdivacky break; 1697226890Sdim 1698202375Srdivacky case Instruction::And: 1699202375Srdivacky if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { 1700202375Srdivacky // If bits are being compared against that are and'd out, then the 1701202375Srdivacky // comparison can never succeed! 1702202375Srdivacky if ((RHSV & ~BOC->getValue()) != 0) 1703263509Sdim return ReplaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE)); 1704226890Sdim 1705202375Srdivacky // If we have ((X & C) == C), turn it into ((X & C) != 0). 1706202375Srdivacky if (RHS == BOC && RHSV.isPowerOf2()) 1707202375Srdivacky return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : 1708202375Srdivacky ICmpInst::ICMP_NE, LHSI, 1709202375Srdivacky Constant::getNullValue(RHS->getType())); 1710224145Sdim 1711224145Sdim // Don't perform the following transforms if the AND has multiple uses 1712224145Sdim if (!BO->hasOneUse()) 1713224145Sdim break; 1714224145Sdim 1715202375Srdivacky // Replace (and X, (1 << size(X)-1) != 0) with x s< 0 1716202375Srdivacky if (BOC->getValue().isSignBit()) { 1717202375Srdivacky Value *X = BO->getOperand(0); 1718202375Srdivacky Constant *Zero = Constant::getNullValue(X->getType()); 1719226890Sdim ICmpInst::Predicate pred = isICMP_NE ? 1720202375Srdivacky ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE; 1721202375Srdivacky return new ICmpInst(pred, X, Zero); 1722202375Srdivacky } 1723226890Sdim 1724202375Srdivacky // ((X & ~7) == 0) --> X < 8 1725202375Srdivacky if (RHSV == 0 && isHighOnes(BOC)) { 1726202375Srdivacky Value *X = BO->getOperand(0); 1727202375Srdivacky Constant *NegX = ConstantExpr::getNeg(BOC); 1728226890Sdim ICmpInst::Predicate pred = isICMP_NE ? 1729202375Srdivacky ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT; 1730202375Srdivacky return new ICmpInst(pred, X, NegX); 1731202375Srdivacky } 1732202375Srdivacky } 1733252723Sdim break; 1734252723Sdim case Instruction::Mul: 1735252723Sdim if (RHSV == 0 && BO->hasNoSignedWrap()) { 1736252723Sdim if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { 1737252723Sdim // The trivial case (mul X, 0) is handled by InstSimplify 1738252723Sdim // General case : (mul X, C) != 0 iff X != 0 1739252723Sdim // (mul X, C) == 0 iff X == 0 1740252723Sdim if (!BOC->isZero()) 1741252723Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1742252723Sdim Constant::getNullValue(RHS->getType())); 1743252723Sdim } 1744252723Sdim } 1745252723Sdim break; 1746202375Srdivacky default: break; 1747202375Srdivacky } 1748202375Srdivacky } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) { 1749202375Srdivacky // Handle icmp {eq|ne} <intrinsic>, intcst. 1750202375Srdivacky switch (II->getIntrinsicID()) { 1751202375Srdivacky case Intrinsic::bswap: 1752202375Srdivacky Worklist.Add(II); 1753210299Sed ICI.setOperand(0, II->getArgOperand(0)); 1754263509Sdim ICI.setOperand(1, Builder->getInt(RHSV.byteSwap())); 1755202375Srdivacky return &ICI; 1756202375Srdivacky case Intrinsic::ctlz: 1757202375Srdivacky case Intrinsic::cttz: 1758202375Srdivacky // ctz(A) == bitwidth(a) -> A == 0 and likewise for != 1759202375Srdivacky if (RHSV == RHS->getType()->getBitWidth()) { 1760202375Srdivacky Worklist.Add(II); 1761210299Sed ICI.setOperand(0, II->getArgOperand(0)); 1762202375Srdivacky ICI.setOperand(1, ConstantInt::get(RHS->getType(), 0)); 1763202375Srdivacky return &ICI; 1764202375Srdivacky } 1765202375Srdivacky break; 1766202375Srdivacky case Intrinsic::ctpop: 1767202375Srdivacky // popcount(A) == 0 -> A == 0 and likewise for != 1768202375Srdivacky if (RHS->isZero()) { 1769202375Srdivacky Worklist.Add(II); 1770210299Sed ICI.setOperand(0, II->getArgOperand(0)); 1771202375Srdivacky ICI.setOperand(1, RHS); 1772202375Srdivacky return &ICI; 1773202375Srdivacky } 1774202375Srdivacky break; 1775202375Srdivacky default: 1776210299Sed break; 1777202375Srdivacky } 1778202375Srdivacky } 1779202375Srdivacky } 1780202375Srdivacky return 0; 1781202375Srdivacky} 1782202375Srdivacky 1783202375Srdivacky/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst). 1784202375Srdivacky/// We only handle extending casts so far. 1785202375Srdivacky/// 1786202375SrdivackyInstruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) { 1787202375Srdivacky const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0)); 1788202375Srdivacky Value *LHSCIOp = LHSCI->getOperand(0); 1789226890Sdim Type *SrcTy = LHSCIOp->getType(); 1790226890Sdim Type *DestTy = LHSCI->getType(); 1791202375Srdivacky Value *RHSCIOp; 1792202375Srdivacky 1793226890Sdim // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the 1794202375Srdivacky // integer type is the same size as the pointer type. 1795202375Srdivacky if (TD && LHSCI->getOpcode() == Instruction::PtrToInt && 1796263509Sdim TD->getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth()) { 1797202375Srdivacky Value *RHSOp = 0; 1798202375Srdivacky if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) { 1799202375Srdivacky RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy); 1800202375Srdivacky } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) { 1801202375Srdivacky RHSOp = RHSC->getOperand(0); 1802202375Srdivacky // If the pointer types don't match, insert a bitcast. 1803202375Srdivacky if (LHSCIOp->getType() != RHSOp->getType()) 1804202375Srdivacky RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType()); 1805202375Srdivacky } 1806202375Srdivacky 1807202375Srdivacky if (RHSOp) 1808202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp); 1809202375Srdivacky } 1810226890Sdim 1811202375Srdivacky // The code below only handles extension cast instructions, so far. 1812202375Srdivacky // Enforce this. 1813202375Srdivacky if (LHSCI->getOpcode() != Instruction::ZExt && 1814202375Srdivacky LHSCI->getOpcode() != Instruction::SExt) 1815202375Srdivacky return 0; 1816202375Srdivacky 1817202375Srdivacky bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt; 1818202375Srdivacky bool isSignedCmp = ICI.isSigned(); 1819202375Srdivacky 1820202375Srdivacky if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) { 1821202375Srdivacky // Not an extension from the same type? 1822202375Srdivacky RHSCIOp = CI->getOperand(0); 1823226890Sdim if (RHSCIOp->getType() != LHSCIOp->getType()) 1824202375Srdivacky return 0; 1825226890Sdim 1826202375Srdivacky // If the signedness of the two casts doesn't agree (i.e. one is a sext 1827202375Srdivacky // and the other is a zext), then we can't handle this. 1828202375Srdivacky if (CI->getOpcode() != LHSCI->getOpcode()) 1829202375Srdivacky return 0; 1830202375Srdivacky 1831202375Srdivacky // Deal with equality cases early. 1832202375Srdivacky if (ICI.isEquality()) 1833202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); 1834202375Srdivacky 1835202375Srdivacky // A signed comparison of sign extended values simplifies into a 1836202375Srdivacky // signed comparison. 1837202375Srdivacky if (isSignedCmp && isSignedExt) 1838202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); 1839202375Srdivacky 1840202375Srdivacky // The other three cases all fold into an unsigned comparison. 1841202375Srdivacky return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp); 1842202375Srdivacky } 1843202375Srdivacky 1844202375Srdivacky // If we aren't dealing with a constant on the RHS, exit early 1845202375Srdivacky ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1)); 1846202375Srdivacky if (!CI) 1847202375Srdivacky return 0; 1848202375Srdivacky 1849202375Srdivacky // Compute the constant that would happen if we truncated to SrcTy then 1850202375Srdivacky // reextended to DestTy. 1851202375Srdivacky Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy); 1852202375Srdivacky Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), 1853202375Srdivacky Res1, DestTy); 1854202375Srdivacky 1855202375Srdivacky // If the re-extended constant didn't change... 1856202375Srdivacky if (Res2 == CI) { 1857202375Srdivacky // Deal with equality cases early. 1858202375Srdivacky if (ICI.isEquality()) 1859202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); 1860202375Srdivacky 1861202375Srdivacky // A signed comparison of sign extended values simplifies into a 1862202375Srdivacky // signed comparison. 1863202375Srdivacky if (isSignedExt && isSignedCmp) 1864202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); 1865202375Srdivacky 1866202375Srdivacky // The other three cases all fold into an unsigned comparison. 1867202375Srdivacky return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1); 1868202375Srdivacky } 1869202375Srdivacky 1870226890Sdim // The re-extended constant changed so the constant cannot be represented 1871202375Srdivacky // in the shorter type. Consequently, we cannot emit a simple comparison. 1872218893Sdim // All the cases that fold to true or false will have already been handled 1873218893Sdim // by SimplifyICmpInst, so only deal with the tricky case. 1874202375Srdivacky 1875218893Sdim if (isSignedCmp || !isSignedExt) 1876218893Sdim return 0; 1877202375Srdivacky 1878202375Srdivacky // Evaluate the comparison for LT (we invert for GT below). LE and GE cases 1879202375Srdivacky // should have been folded away previously and not enter in here. 1880202375Srdivacky 1881218893Sdim // We're performing an unsigned comp with a sign extended value. 1882218893Sdim // This is true if the input is >= 0. [aka >s -1] 1883218893Sdim Constant *NegOne = Constant::getAllOnesValue(SrcTy); 1884218893Sdim Value *Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName()); 1885218893Sdim 1886202375Srdivacky // Finally, return the value computed. 1887218893Sdim if (ICI.getPredicate() == ICmpInst::ICMP_ULT) 1888202375Srdivacky return ReplaceInstUsesWith(ICI, Result); 1889202375Srdivacky 1890218893Sdim assert(ICI.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!"); 1891202375Srdivacky return BinaryOperator::CreateNot(Result); 1892202375Srdivacky} 1893202375Srdivacky 1894218893Sdim/// ProcessUGT_ADDCST_ADD - The caller has matched a pattern of the form: 1895218893Sdim/// I = icmp ugt (add (add A, B), CI2), CI1 1896218893Sdim/// If this is of the form: 1897218893Sdim/// sum = a + b 1898218893Sdim/// if (sum+128 >u 255) 1899218893Sdim/// Then replace it with llvm.sadd.with.overflow.i8. 1900218893Sdim/// 1901218893Sdimstatic Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B, 1902218893Sdim ConstantInt *CI2, ConstantInt *CI1, 1903218893Sdim InstCombiner &IC) { 1904218893Sdim // The transformation we're trying to do here is to transform this into an 1905218893Sdim // llvm.sadd.with.overflow. To do this, we have to replace the original add 1906218893Sdim // with a narrower add, and discard the add-with-constant that is part of the 1907218893Sdim // range check (if we can't eliminate it, this isn't profitable). 1908226890Sdim 1909218893Sdim // In order to eliminate the add-with-constant, the compare can be its only 1910218893Sdim // use. 1911218893Sdim Instruction *AddWithCst = cast<Instruction>(I.getOperand(0)); 1912218893Sdim if (!AddWithCst->hasOneUse()) return 0; 1913226890Sdim 1914218893Sdim // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow. 1915218893Sdim if (!CI2->getValue().isPowerOf2()) return 0; 1916218893Sdim unsigned NewWidth = CI2->getValue().countTrailingZeros(); 1917218893Sdim if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31) return 0; 1918226890Sdim 1919218893Sdim // The width of the new add formed is 1 more than the bias. 1920218893Sdim ++NewWidth; 1921226890Sdim 1922218893Sdim // Check to see that CI1 is an all-ones value with NewWidth bits. 1923218893Sdim if (CI1->getBitWidth() == NewWidth || 1924218893Sdim CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth)) 1925218893Sdim return 0; 1926226890Sdim 1927235633Sdim // This is only really a signed overflow check if the inputs have been 1928235633Sdim // sign-extended; check for that condition. For example, if CI2 is 2^31 and 1929235633Sdim // the operands of the add are 64 bits wide, we need at least 33 sign bits. 1930235633Sdim unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1; 1931235633Sdim if (IC.ComputeNumSignBits(A) < NeededSignBits || 1932235633Sdim IC.ComputeNumSignBits(B) < NeededSignBits) 1933235633Sdim return 0; 1934235633Sdim 1935226890Sdim // In order to replace the original add with a narrower 1936218893Sdim // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant 1937218893Sdim // and truncates that discard the high bits of the add. Verify that this is 1938218893Sdim // the case. 1939218893Sdim Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0)); 1940218893Sdim for (Value::use_iterator UI = OrigAdd->use_begin(), E = OrigAdd->use_end(); 1941218893Sdim UI != E; ++UI) { 1942218893Sdim if (*UI == AddWithCst) continue; 1943226890Sdim 1944218893Sdim // Only accept truncates for now. We would really like a nice recursive 1945218893Sdim // predicate like SimplifyDemandedBits, but which goes downwards the use-def 1946218893Sdim // chain to see which bits of a value are actually demanded. If the 1947218893Sdim // original add had another add which was then immediately truncated, we 1948218893Sdim // could still do the transformation. 1949218893Sdim TruncInst *TI = dyn_cast<TruncInst>(*UI); 1950218893Sdim if (TI == 0 || 1951218893Sdim TI->getType()->getPrimitiveSizeInBits() > NewWidth) return 0; 1952218893Sdim } 1953226890Sdim 1954218893Sdim // If the pattern matches, truncate the inputs to the narrower type and 1955218893Sdim // use the sadd_with_overflow intrinsic to efficiently compute both the 1956218893Sdim // result and the overflow bit. 1957218893Sdim Module *M = I.getParent()->getParent()->getParent(); 1958226890Sdim 1959224145Sdim Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth); 1960218893Sdim Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow, 1961224145Sdim NewType); 1962202375Srdivacky 1963218893Sdim InstCombiner::BuilderTy *Builder = IC.Builder; 1964226890Sdim 1965218893Sdim // Put the new code above the original add, in case there are any uses of the 1966218893Sdim // add between the add and the compare. 1967218893Sdim Builder->SetInsertPoint(OrigAdd); 1968226890Sdim 1969218893Sdim Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName()+".trunc"); 1970218893Sdim Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName()+".trunc"); 1971218893Sdim CallInst *Call = Builder->CreateCall2(F, TruncA, TruncB, "sadd"); 1972218893Sdim Value *Add = Builder->CreateExtractValue(Call, 0, "sadd.result"); 1973218893Sdim Value *ZExt = Builder->CreateZExt(Add, OrigAdd->getType()); 1974226890Sdim 1975218893Sdim // The inner add was the result of the narrow add, zero extended to the 1976218893Sdim // wider type. Replace it with the result computed by the intrinsic. 1977218893Sdim IC.ReplaceInstUsesWith(*OrigAdd, ZExt); 1978226890Sdim 1979218893Sdim // The original icmp gets replaced with the overflow value. 1980218893Sdim return ExtractValueInst::Create(Call, 1, "sadd.overflow"); 1981218893Sdim} 1982202375Srdivacky 1983218893Sdimstatic Instruction *ProcessUAddIdiom(Instruction &I, Value *OrigAddV, 1984218893Sdim InstCombiner &IC) { 1985218893Sdim // Don't bother doing this transformation for pointers, don't do it for 1986218893Sdim // vectors. 1987218893Sdim if (!isa<IntegerType>(OrigAddV->getType())) return 0; 1988226890Sdim 1989218893Sdim // If the add is a constant expr, then we don't bother transforming it. 1990218893Sdim Instruction *OrigAdd = dyn_cast<Instruction>(OrigAddV); 1991218893Sdim if (OrigAdd == 0) return 0; 1992226890Sdim 1993218893Sdim Value *LHS = OrigAdd->getOperand(0), *RHS = OrigAdd->getOperand(1); 1994226890Sdim 1995218893Sdim // Put the new code above the original add, in case there are any uses of the 1996218893Sdim // add between the add and the compare. 1997218893Sdim InstCombiner::BuilderTy *Builder = IC.Builder; 1998218893Sdim Builder->SetInsertPoint(OrigAdd); 1999218893Sdim 2000218893Sdim Module *M = I.getParent()->getParent()->getParent(); 2001224145Sdim Type *Ty = LHS->getType(); 2002224145Sdim Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty); 2003218893Sdim CallInst *Call = Builder->CreateCall2(F, LHS, RHS, "uadd"); 2004218893Sdim Value *Add = Builder->CreateExtractValue(Call, 0); 2005218893Sdim 2006218893Sdim IC.ReplaceInstUsesWith(*OrigAdd, Add); 2007218893Sdim 2008218893Sdim // The original icmp gets replaced with the overflow value. 2009218893Sdim return ExtractValueInst::Create(Call, 1, "uadd.overflow"); 2010218893Sdim} 2011218893Sdim 2012218893Sdim// DemandedBitsLHSMask - When performing a comparison against a constant, 2013218893Sdim// it is possible that not all the bits in the LHS are demanded. This helper 2014218893Sdim// method computes the mask that IS demanded. 2015218893Sdimstatic APInt DemandedBitsLHSMask(ICmpInst &I, 2016218893Sdim unsigned BitWidth, bool isSignCheck) { 2017218893Sdim if (isSignCheck) 2018218893Sdim return APInt::getSignBit(BitWidth); 2019226890Sdim 2020218893Sdim ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(1)); 2021218893Sdim if (!CI) return APInt::getAllOnesValue(BitWidth); 2022218893Sdim const APInt &RHS = CI->getValue(); 2023226890Sdim 2024218893Sdim switch (I.getPredicate()) { 2025226890Sdim // For a UGT comparison, we don't care about any bits that 2026218893Sdim // correspond to the trailing ones of the comparand. The value of these 2027218893Sdim // bits doesn't impact the outcome of the comparison, because any value 2028218893Sdim // greater than the RHS must differ in a bit higher than these due to carry. 2029218893Sdim case ICmpInst::ICMP_UGT: { 2030218893Sdim unsigned trailingOnes = RHS.countTrailingOnes(); 2031218893Sdim APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingOnes); 2032218893Sdim return ~lowBitsSet; 2033218893Sdim } 2034226890Sdim 2035218893Sdim // Similarly, for a ULT comparison, we don't care about the trailing zeros. 2036218893Sdim // Any value less than the RHS must differ in a higher bit because of carries. 2037218893Sdim case ICmpInst::ICMP_ULT: { 2038218893Sdim unsigned trailingZeros = RHS.countTrailingZeros(); 2039218893Sdim APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingZeros); 2040218893Sdim return ~lowBitsSet; 2041218893Sdim } 2042226890Sdim 2043218893Sdim default: 2044218893Sdim return APInt::getAllOnesValue(BitWidth); 2045218893Sdim } 2046226890Sdim 2047218893Sdim} 2048218893Sdim 2049263509Sdim/// \brief Check if the order of \p Op0 and \p Op1 as operand in an ICmpInst 2050263509Sdim/// should be swapped. 2051263509Sdim/// The descision is based on how many times these two operands are reused 2052263509Sdim/// as subtract operands and their positions in those instructions. 2053263509Sdim/// The rational is that several architectures use the same instruction for 2054263509Sdim/// both subtract and cmp, thus it is better if the order of those operands 2055263509Sdim/// match. 2056263509Sdim/// \return true if Op0 and Op1 should be swapped. 2057263509Sdimstatic bool swapMayExposeCSEOpportunities(const Value * Op0, 2058263509Sdim const Value * Op1) { 2059263509Sdim // Filter out pointer value as those cannot appears directly in subtract. 2060263509Sdim // FIXME: we may want to go through inttoptrs or bitcasts. 2061263509Sdim if (Op0->getType()->isPointerTy()) 2062263509Sdim return false; 2063263509Sdim // Count every uses of both Op0 and Op1 in a subtract. 2064263509Sdim // Each time Op0 is the first operand, count -1: swapping is bad, the 2065263509Sdim // subtract has already the same layout as the compare. 2066263509Sdim // Each time Op0 is the second operand, count +1: swapping is good, the 2067263509Sdim // subtract has a diffrent layout as the compare. 2068263509Sdim // At the end, if the benefit is greater than 0, Op0 should come second to 2069263509Sdim // expose more CSE opportunities. 2070263509Sdim int GlobalSwapBenefits = 0; 2071263509Sdim for (Value::const_use_iterator UI = Op0->use_begin(), UIEnd = Op0->use_end(); UI != UIEnd; ++UI) { 2072263509Sdim const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(*UI); 2073263509Sdim if (!BinOp || BinOp->getOpcode() != Instruction::Sub) 2074263509Sdim continue; 2075263509Sdim // If Op0 is the first argument, this is not beneficial to swap the 2076263509Sdim // arguments. 2077263509Sdim int LocalSwapBenefits = -1; 2078263509Sdim unsigned Op1Idx = 1; 2079263509Sdim if (BinOp->getOperand(Op1Idx) == Op0) { 2080263509Sdim Op1Idx = 0; 2081263509Sdim LocalSwapBenefits = 1; 2082263509Sdim } 2083263509Sdim if (BinOp->getOperand(Op1Idx) != Op1) 2084263509Sdim continue; 2085263509Sdim GlobalSwapBenefits += LocalSwapBenefits; 2086263509Sdim } 2087263509Sdim return GlobalSwapBenefits > 0; 2088263509Sdim} 2089263509Sdim 2090202375SrdivackyInstruction *InstCombiner::visitICmpInst(ICmpInst &I) { 2091202375Srdivacky bool Changed = false; 2092203954Srdivacky Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); 2093263509Sdim unsigned Op0Cplxity = getComplexity(Op0); 2094263509Sdim unsigned Op1Cplxity = getComplexity(Op1); 2095226890Sdim 2096202375Srdivacky /// Orders the operands of the compare so that they are listed from most 2097202375Srdivacky /// complex to least complex. This puts constants before unary operators, 2098202375Srdivacky /// before binary operators. 2099263509Sdim if (Op0Cplxity < Op1Cplxity || 2100263509Sdim (Op0Cplxity == Op1Cplxity && 2101263509Sdim swapMayExposeCSEOpportunities(Op0, Op1))) { 2102202375Srdivacky I.swapOperands(); 2103203954Srdivacky std::swap(Op0, Op1); 2104202375Srdivacky Changed = true; 2105202375Srdivacky } 2106226890Sdim 2107202375Srdivacky if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD)) 2108202375Srdivacky return ReplaceInstUsesWith(I, V); 2109202375Srdivacky 2110235633Sdim // comparing -val or val with non-zero is the same as just comparing val 2111235633Sdim // ie, abs(val) != 0 -> val != 0 2112235633Sdim if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero())) 2113235633Sdim { 2114235633Sdim Value *Cond, *SelectTrue, *SelectFalse; 2115235633Sdim if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue), 2116235633Sdim m_Value(SelectFalse)))) { 2117235633Sdim if (Value *V = dyn_castNegVal(SelectTrue)) { 2118235633Sdim if (V == SelectFalse) 2119235633Sdim return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1); 2120235633Sdim } 2121235633Sdim else if (Value *V = dyn_castNegVal(SelectFalse)) { 2122235633Sdim if (V == SelectTrue) 2123235633Sdim return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1); 2124235633Sdim } 2125235633Sdim } 2126235633Sdim } 2127235633Sdim 2128226890Sdim Type *Ty = Op0->getType(); 2129226890Sdim 2130202375Srdivacky // icmp's with boolean values can always be turned into bitwise operations 2131203954Srdivacky if (Ty->isIntegerTy(1)) { 2132202375Srdivacky switch (I.getPredicate()) { 2133202375Srdivacky default: llvm_unreachable("Invalid icmp instruction!"); 2134202375Srdivacky case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B) 2135202375Srdivacky Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp"); 2136202375Srdivacky return BinaryOperator::CreateNot(Xor); 2137202375Srdivacky } 2138202375Srdivacky case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B 2139202375Srdivacky return BinaryOperator::CreateXor(Op0, Op1); 2140202375Srdivacky 2141202375Srdivacky case ICmpInst::ICMP_UGT: 2142202375Srdivacky std::swap(Op0, Op1); // Change icmp ugt -> icmp ult 2143202375Srdivacky // FALL THROUGH 2144202375Srdivacky case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B 2145202375Srdivacky Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp"); 2146202375Srdivacky return BinaryOperator::CreateAnd(Not, Op1); 2147202375Srdivacky } 2148202375Srdivacky case ICmpInst::ICMP_SGT: 2149202375Srdivacky std::swap(Op0, Op1); // Change icmp sgt -> icmp slt 2150202375Srdivacky // FALL THROUGH 2151202375Srdivacky case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B 2152202375Srdivacky Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp"); 2153202375Srdivacky return BinaryOperator::CreateAnd(Not, Op0); 2154202375Srdivacky } 2155202375Srdivacky case ICmpInst::ICMP_UGE: 2156202375Srdivacky std::swap(Op0, Op1); // Change icmp uge -> icmp ule 2157202375Srdivacky // FALL THROUGH 2158202375Srdivacky case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B 2159202375Srdivacky Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp"); 2160202375Srdivacky return BinaryOperator::CreateOr(Not, Op1); 2161202375Srdivacky } 2162202375Srdivacky case ICmpInst::ICMP_SGE: 2163202375Srdivacky std::swap(Op0, Op1); // Change icmp sge -> icmp sle 2164202375Srdivacky // FALL THROUGH 2165202375Srdivacky case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B 2166202375Srdivacky Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp"); 2167202375Srdivacky return BinaryOperator::CreateOr(Not, Op0); 2168202375Srdivacky } 2169202375Srdivacky } 2170202375Srdivacky } 2171202375Srdivacky 2172202375Srdivacky unsigned BitWidth = 0; 2173218893Sdim if (Ty->isIntOrIntVectorTy()) 2174218893Sdim BitWidth = Ty->getScalarSizeInBits(); 2175218893Sdim else if (TD) // Pointers require TD info to get their size. 2176202375Srdivacky BitWidth = TD->getTypeSizeInBits(Ty->getScalarType()); 2177226890Sdim 2178202375Srdivacky bool isSignBit = false; 2179202375Srdivacky 2180202375Srdivacky // See if we are doing a comparison with a constant. 2181202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2182202375Srdivacky Value *A = 0, *B = 0; 2183226890Sdim 2184218893Sdim // Match the following pattern, which is a common idiom when writing 2185218893Sdim // overflow-safe integer arithmetic function. The source performs an 2186218893Sdim // addition in wider type, and explicitly checks for overflow using 2187218893Sdim // comparisons against INT_MIN and INT_MAX. Simplify this by using the 2188218893Sdim // sadd_with_overflow intrinsic. 2189218893Sdim // 2190218893Sdim // TODO: This could probably be generalized to handle other overflow-safe 2191226890Sdim // operations if we worked out the formulas to compute the appropriate 2192218893Sdim // magic constants. 2193226890Sdim // 2194218893Sdim // sum = a + b 2195218893Sdim // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8 2196218893Sdim { 2197218893Sdim ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI 2198218893Sdim if (I.getPredicate() == ICmpInst::ICMP_UGT && 2199218893Sdim match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2)))) 2200218893Sdim if (Instruction *Res = ProcessUGT_ADDCST_ADD(I, A, B, CI2, CI, *this)) 2201218893Sdim return Res; 2202218893Sdim } 2203226890Sdim 2204202375Srdivacky // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B) 2205202375Srdivacky if (I.isEquality() && CI->isZero() && 2206202375Srdivacky match(Op0, m_Sub(m_Value(A), m_Value(B)))) { 2207202375Srdivacky // (icmp cond A B) if cond is equality 2208202375Srdivacky return new ICmpInst(I.getPredicate(), A, B); 2209202375Srdivacky } 2210226890Sdim 2211202375Srdivacky // If we have an icmp le or icmp ge instruction, turn it into the 2212202375Srdivacky // appropriate icmp lt or icmp gt instruction. This allows us to rely on 2213202375Srdivacky // them being folded in the code below. The SimplifyICmpInst code has 2214202375Srdivacky // already handled the edge cases for us, so we just assert on them. 2215202375Srdivacky switch (I.getPredicate()) { 2216202375Srdivacky default: break; 2217202375Srdivacky case ICmpInst::ICMP_ULE: 2218202375Srdivacky assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE 2219202375Srdivacky return new ICmpInst(ICmpInst::ICMP_ULT, Op0, 2220263509Sdim Builder->getInt(CI->getValue()+1)); 2221202375Srdivacky case ICmpInst::ICMP_SLE: 2222202375Srdivacky assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE 2223202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, Op0, 2224263509Sdim Builder->getInt(CI->getValue()+1)); 2225202375Srdivacky case ICmpInst::ICMP_UGE: 2226221345Sdim assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE 2227202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGT, Op0, 2228263509Sdim Builder->getInt(CI->getValue()-1)); 2229202375Srdivacky case ICmpInst::ICMP_SGE: 2230221345Sdim assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE 2231202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGT, Op0, 2232263509Sdim Builder->getInt(CI->getValue()-1)); 2233202375Srdivacky } 2234226890Sdim 2235202375Srdivacky // If this comparison is a normal comparison, it demands all 2236202375Srdivacky // bits, if it is a sign bit comparison, it only demands the sign bit. 2237202375Srdivacky bool UnusedBit; 2238202375Srdivacky isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit); 2239202375Srdivacky } 2240202375Srdivacky 2241202375Srdivacky // See if we can fold the comparison based on range information we can get 2242202375Srdivacky // by checking whether bits are known to be zero or one in the input. 2243202375Srdivacky if (BitWidth != 0) { 2244202375Srdivacky APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0); 2245202375Srdivacky APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0); 2246202375Srdivacky 2247202375Srdivacky if (SimplifyDemandedBits(I.getOperandUse(0), 2248218893Sdim DemandedBitsLHSMask(I, BitWidth, isSignBit), 2249202375Srdivacky Op0KnownZero, Op0KnownOne, 0)) 2250202375Srdivacky return &I; 2251202375Srdivacky if (SimplifyDemandedBits(I.getOperandUse(1), 2252202375Srdivacky APInt::getAllOnesValue(BitWidth), 2253202375Srdivacky Op1KnownZero, Op1KnownOne, 0)) 2254202375Srdivacky return &I; 2255202375Srdivacky 2256202375Srdivacky // Given the known and unknown bits, compute a range that the LHS could be 2257202375Srdivacky // in. Compute the Min, Max and RHS values based on the known bits. For the 2258202375Srdivacky // EQ and NE we use unsigned values. 2259202375Srdivacky APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0); 2260202375Srdivacky APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0); 2261202375Srdivacky if (I.isSigned()) { 2262202375Srdivacky ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne, 2263202375Srdivacky Op0Min, Op0Max); 2264202375Srdivacky ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne, 2265202375Srdivacky Op1Min, Op1Max); 2266202375Srdivacky } else { 2267202375Srdivacky ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne, 2268202375Srdivacky Op0Min, Op0Max); 2269202375Srdivacky ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne, 2270202375Srdivacky Op1Min, Op1Max); 2271202375Srdivacky } 2272202375Srdivacky 2273202375Srdivacky // If Min and Max are known to be the same, then SimplifyDemandedBits 2274202375Srdivacky // figured out that the LHS is a constant. Just constant fold this now so 2275202375Srdivacky // that code below can assume that Min != Max. 2276202375Srdivacky if (!isa<Constant>(Op0) && Op0Min == Op0Max) 2277202375Srdivacky return new ICmpInst(I.getPredicate(), 2278221345Sdim ConstantInt::get(Op0->getType(), Op0Min), Op1); 2279202375Srdivacky if (!isa<Constant>(Op1) && Op1Min == Op1Max) 2280202375Srdivacky return new ICmpInst(I.getPredicate(), Op0, 2281221345Sdim ConstantInt::get(Op1->getType(), Op1Min)); 2282202375Srdivacky 2283202375Srdivacky // Based on the range information we know about the LHS, see if we can 2284221345Sdim // simplify this comparison. For example, (x&4) < 8 is always true. 2285202375Srdivacky switch (I.getPredicate()) { 2286202375Srdivacky default: llvm_unreachable("Unknown icmp opcode!"); 2287218893Sdim case ICmpInst::ICMP_EQ: { 2288202375Srdivacky if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) 2289221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2290226890Sdim 2291218893Sdim // If all bits are known zero except for one, then we know at most one 2292218893Sdim // bit is set. If the comparison is against zero, then this is a check 2293218893Sdim // to see if *that* bit is set. 2294218893Sdim APInt Op0KnownZeroInverted = ~Op0KnownZero; 2295218893Sdim if (~Op1KnownZero == 0 && Op0KnownZeroInverted.isPowerOf2()) { 2296218893Sdim // If the LHS is an AND with the same constant, look through it. 2297218893Sdim Value *LHS = 0; 2298218893Sdim ConstantInt *LHSC = 0; 2299218893Sdim if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) || 2300218893Sdim LHSC->getValue() != Op0KnownZeroInverted) 2301218893Sdim LHS = Op0; 2302226890Sdim 2303218893Sdim // If the LHS is 1 << x, and we know the result is a power of 2 like 8, 2304218893Sdim // then turn "((1 << x)&8) == 0" into "x != 3". 2305218893Sdim Value *X = 0; 2306218893Sdim if (match(LHS, m_Shl(m_One(), m_Value(X)))) { 2307218893Sdim unsigned CmpVal = Op0KnownZeroInverted.countTrailingZeros(); 2308218893Sdim return new ICmpInst(ICmpInst::ICMP_NE, X, 2309218893Sdim ConstantInt::get(X->getType(), CmpVal)); 2310218893Sdim } 2311226890Sdim 2312218893Sdim // If the LHS is 8 >>u x, and we know the result is a power of 2 like 1, 2313218893Sdim // then turn "((8 >>u x)&1) == 0" into "x != 3". 2314218893Sdim const APInt *CI; 2315218893Sdim if (Op0KnownZeroInverted == 1 && 2316218893Sdim match(LHS, m_LShr(m_Power2(CI), m_Value(X)))) 2317218893Sdim return new ICmpInst(ICmpInst::ICMP_NE, X, 2318218893Sdim ConstantInt::get(X->getType(), 2319218893Sdim CI->countTrailingZeros())); 2320218893Sdim } 2321226890Sdim 2322202375Srdivacky break; 2323218893Sdim } 2324218893Sdim case ICmpInst::ICMP_NE: { 2325202375Srdivacky if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) 2326221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2327226890Sdim 2328218893Sdim // If all bits are known zero except for one, then we know at most one 2329218893Sdim // bit is set. If the comparison is against zero, then this is a check 2330218893Sdim // to see if *that* bit is set. 2331218893Sdim APInt Op0KnownZeroInverted = ~Op0KnownZero; 2332218893Sdim if (~Op1KnownZero == 0 && Op0KnownZeroInverted.isPowerOf2()) { 2333218893Sdim // If the LHS is an AND with the same constant, look through it. 2334218893Sdim Value *LHS = 0; 2335218893Sdim ConstantInt *LHSC = 0; 2336218893Sdim if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) || 2337218893Sdim LHSC->getValue() != Op0KnownZeroInverted) 2338218893Sdim LHS = Op0; 2339226890Sdim 2340218893Sdim // If the LHS is 1 << x, and we know the result is a power of 2 like 8, 2341218893Sdim // then turn "((1 << x)&8) != 0" into "x == 3". 2342218893Sdim Value *X = 0; 2343218893Sdim if (match(LHS, m_Shl(m_One(), m_Value(X)))) { 2344218893Sdim unsigned CmpVal = Op0KnownZeroInverted.countTrailingZeros(); 2345218893Sdim return new ICmpInst(ICmpInst::ICMP_EQ, X, 2346218893Sdim ConstantInt::get(X->getType(), CmpVal)); 2347218893Sdim } 2348226890Sdim 2349218893Sdim // If the LHS is 8 >>u x, and we know the result is a power of 2 like 1, 2350218893Sdim // then turn "((8 >>u x)&1) != 0" into "x == 3". 2351218893Sdim const APInt *CI; 2352218893Sdim if (Op0KnownZeroInverted == 1 && 2353218893Sdim match(LHS, m_LShr(m_Power2(CI), m_Value(X)))) 2354218893Sdim return new ICmpInst(ICmpInst::ICMP_EQ, X, 2355218893Sdim ConstantInt::get(X->getType(), 2356218893Sdim CI->countTrailingZeros())); 2357218893Sdim } 2358226890Sdim 2359202375Srdivacky break; 2360218893Sdim } 2361202375Srdivacky case ICmpInst::ICMP_ULT: 2362202375Srdivacky if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B) 2363221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2364202375Srdivacky if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B) 2365221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2366202375Srdivacky if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B) 2367202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); 2368202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2369202375Srdivacky if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C 2370202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Op0, 2371263509Sdim Builder->getInt(CI->getValue()-1)); 2372202375Srdivacky 2373202375Srdivacky // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear 2374202375Srdivacky if (CI->isMinValue(true)) 2375202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGT, Op0, 2376202375Srdivacky Constant::getAllOnesValue(Op0->getType())); 2377202375Srdivacky } 2378202375Srdivacky break; 2379202375Srdivacky case ICmpInst::ICMP_UGT: 2380202375Srdivacky if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B) 2381221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2382202375Srdivacky if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B) 2383221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2384202375Srdivacky 2385202375Srdivacky if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B) 2386202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); 2387202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2388202375Srdivacky if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C 2389202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Op0, 2390263509Sdim Builder->getInt(CI->getValue()+1)); 2391202375Srdivacky 2392202375Srdivacky // (x >u 2147483647) -> (x <s 0) -> true if sign bit set 2393202375Srdivacky if (CI->isMaxValue(true)) 2394202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, Op0, 2395202375Srdivacky Constant::getNullValue(Op0->getType())); 2396202375Srdivacky } 2397202375Srdivacky break; 2398202375Srdivacky case ICmpInst::ICMP_SLT: 2399202375Srdivacky if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C) 2400221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2401202375Srdivacky if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C) 2402221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2403202375Srdivacky if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B) 2404202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); 2405202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2406202375Srdivacky if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C 2407202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Op0, 2408263509Sdim Builder->getInt(CI->getValue()-1)); 2409202375Srdivacky } 2410202375Srdivacky break; 2411202375Srdivacky case ICmpInst::ICMP_SGT: 2412202375Srdivacky if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B) 2413221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2414202375Srdivacky if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B) 2415221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2416202375Srdivacky 2417202375Srdivacky if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B) 2418202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); 2419202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2420202375Srdivacky if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C 2421202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Op0, 2422263509Sdim Builder->getInt(CI->getValue()+1)); 2423202375Srdivacky } 2424202375Srdivacky break; 2425202375Srdivacky case ICmpInst::ICMP_SGE: 2426202375Srdivacky assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!"); 2427202375Srdivacky if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B) 2428221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2429202375Srdivacky if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B) 2430221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2431202375Srdivacky break; 2432202375Srdivacky case ICmpInst::ICMP_SLE: 2433202375Srdivacky assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!"); 2434202375Srdivacky if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B) 2435221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2436202375Srdivacky if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B) 2437221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2438202375Srdivacky break; 2439202375Srdivacky case ICmpInst::ICMP_UGE: 2440202375Srdivacky assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!"); 2441202375Srdivacky if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B) 2442221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2443202375Srdivacky if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B) 2444221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2445202375Srdivacky break; 2446202375Srdivacky case ICmpInst::ICMP_ULE: 2447202375Srdivacky assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!"); 2448202375Srdivacky if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B) 2449221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2450202375Srdivacky if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B) 2451221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2452202375Srdivacky break; 2453202375Srdivacky } 2454202375Srdivacky 2455202375Srdivacky // Turn a signed comparison into an unsigned one if both operands 2456202375Srdivacky // are known to have the same sign. 2457202375Srdivacky if (I.isSigned() && 2458202375Srdivacky ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) || 2459202375Srdivacky (Op0KnownOne.isNegative() && Op1KnownOne.isNegative()))) 2460202375Srdivacky return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1); 2461202375Srdivacky } 2462202375Srdivacky 2463202375Srdivacky // Test if the ICmpInst instruction is used exclusively by a select as 2464202375Srdivacky // part of a minimum or maximum operation. If so, refrain from doing 2465202375Srdivacky // any other folding. This helps out other analyses which understand 2466202375Srdivacky // non-obfuscated minimum and maximum idioms, such as ScalarEvolution 2467202375Srdivacky // and CodeGen. And in this case, at least one of the comparison 2468202375Srdivacky // operands has at least one user besides the compare (the select), 2469202375Srdivacky // which would often largely negate the benefit of folding anyway. 2470202375Srdivacky if (I.hasOneUse()) 2471202375Srdivacky if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin())) 2472202375Srdivacky if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) || 2473202375Srdivacky (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1)) 2474202375Srdivacky return 0; 2475202375Srdivacky 2476202375Srdivacky // See if we are doing a comparison between a constant and an instruction that 2477202375Srdivacky // can be folded into the comparison. 2478202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2479226890Sdim // Since the RHS is a ConstantInt (CI), if the left hand side is an 2480226890Sdim // instruction, see if that instruction also has constants so that the 2481226890Sdim // instruction can be folded into the icmp 2482202375Srdivacky if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) 2483202375Srdivacky if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI)) 2484202375Srdivacky return Res; 2485202375Srdivacky } 2486202375Srdivacky 2487202375Srdivacky // Handle icmp with constant (but not simple integer constant) RHS 2488202375Srdivacky if (Constant *RHSC = dyn_cast<Constant>(Op1)) { 2489202375Srdivacky if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) 2490202375Srdivacky switch (LHSI->getOpcode()) { 2491202375Srdivacky case Instruction::GetElementPtr: 2492202375Srdivacky // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null 2493202375Srdivacky if (RHSC->isNullValue() && 2494202375Srdivacky cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices()) 2495202375Srdivacky return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), 2496202375Srdivacky Constant::getNullValue(LHSI->getOperand(0)->getType())); 2497202375Srdivacky break; 2498202375Srdivacky case Instruction::PHI: 2499202375Srdivacky // Only fold icmp into the PHI if the phi and icmp are in the same 2500202375Srdivacky // block. If in the same block, we're encouraging jump threading. If 2501202375Srdivacky // not, we are just pessimizing the code by making an i1 phi. 2502202375Srdivacky if (LHSI->getParent() == I.getParent()) 2503218893Sdim if (Instruction *NV = FoldOpIntoPhi(I)) 2504202375Srdivacky return NV; 2505202375Srdivacky break; 2506202375Srdivacky case Instruction::Select: { 2507202375Srdivacky // If either operand of the select is a constant, we can fold the 2508202375Srdivacky // comparison into the select arms, which will cause one to be 2509202375Srdivacky // constant folded and the select turned into a bitwise or. 2510202375Srdivacky Value *Op1 = 0, *Op2 = 0; 2511202375Srdivacky if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) 2512202375Srdivacky Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); 2513202375Srdivacky if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) 2514202375Srdivacky Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); 2515202375Srdivacky 2516202375Srdivacky // We only want to perform this transformation if it will not lead to 2517202375Srdivacky // additional code. This is true if either both sides of the select 2518202375Srdivacky // fold to a constant (in which case the icmp is replaced with a select 2519202375Srdivacky // which will usually simplify) or this is the only user of the 2520202375Srdivacky // select (in which case we are trading a select+icmp for a simpler 2521202375Srdivacky // select+icmp). 2522202375Srdivacky if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) { 2523202375Srdivacky if (!Op1) 2524202375Srdivacky Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1), 2525202375Srdivacky RHSC, I.getName()); 2526202375Srdivacky if (!Op2) 2527202375Srdivacky Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2), 2528202375Srdivacky RHSC, I.getName()); 2529202375Srdivacky return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); 2530202375Srdivacky } 2531202375Srdivacky break; 2532202375Srdivacky } 2533202375Srdivacky case Instruction::IntToPtr: 2534202375Srdivacky // icmp pred inttoptr(X), null -> icmp pred X, 0 2535202375Srdivacky if (RHSC->isNullValue() && TD && 2536263509Sdim TD->getIntPtrType(RHSC->getType()) == 2537202375Srdivacky LHSI->getOperand(0)->getType()) 2538202375Srdivacky return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), 2539202375Srdivacky Constant::getNullValue(LHSI->getOperand(0)->getType())); 2540202375Srdivacky break; 2541202375Srdivacky 2542202375Srdivacky case Instruction::Load: 2543202375Srdivacky // Try to optimize things like "A[i] > 4" to index computations. 2544202375Srdivacky if (GetElementPtrInst *GEP = 2545202375Srdivacky dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) { 2546202375Srdivacky if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) 2547202375Srdivacky if (GV->isConstant() && GV->hasDefinitiveInitializer() && 2548202375Srdivacky !cast<LoadInst>(LHSI)->isVolatile()) 2549202375Srdivacky if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) 2550202375Srdivacky return Res; 2551202375Srdivacky } 2552202375Srdivacky break; 2553202375Srdivacky } 2554202375Srdivacky } 2555202375Srdivacky 2556202375Srdivacky // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now. 2557202375Srdivacky if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0)) 2558202375Srdivacky if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I)) 2559202375Srdivacky return NI; 2560202375Srdivacky if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1)) 2561202375Srdivacky if (Instruction *NI = FoldGEPICmp(GEP, Op0, 2562202375Srdivacky ICmpInst::getSwappedPredicate(I.getPredicate()), I)) 2563202375Srdivacky return NI; 2564202375Srdivacky 2565202375Srdivacky // Test to see if the operands of the icmp are casted versions of other 2566202375Srdivacky // values. If the ptr->ptr cast can be stripped off both arguments, we do so 2567202375Srdivacky // now. 2568202375Srdivacky if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) { 2569226890Sdim if (Op0->getType()->isPointerTy() && 2570226890Sdim (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) { 2571202375Srdivacky // We keep moving the cast from the left operand over to the right 2572202375Srdivacky // operand, where it can often be eliminated completely. 2573202375Srdivacky Op0 = CI->getOperand(0); 2574202375Srdivacky 2575202375Srdivacky // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast 2576202375Srdivacky // so eliminate it as well. 2577202375Srdivacky if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1)) 2578202375Srdivacky Op1 = CI2->getOperand(0); 2579202375Srdivacky 2580202375Srdivacky // If Op1 is a constant, we can fold the cast into the constant. 2581202375Srdivacky if (Op0->getType() != Op1->getType()) { 2582202375Srdivacky if (Constant *Op1C = dyn_cast<Constant>(Op1)) { 2583202375Srdivacky Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType()); 2584202375Srdivacky } else { 2585202375Srdivacky // Otherwise, cast the RHS right before the icmp 2586202375Srdivacky Op1 = Builder->CreateBitCast(Op1, Op0->getType()); 2587202375Srdivacky } 2588202375Srdivacky } 2589202375Srdivacky return new ICmpInst(I.getPredicate(), Op0, Op1); 2590202375Srdivacky } 2591202375Srdivacky } 2592226890Sdim 2593202375Srdivacky if (isa<CastInst>(Op0)) { 2594202375Srdivacky // Handle the special case of: icmp (cast bool to X), <cst> 2595202375Srdivacky // This comes up when you have code like 2596202375Srdivacky // int X = A < B; 2597202375Srdivacky // if (X) ... 2598202375Srdivacky // For generality, we handle any zero-extension of any operand comparison 2599202375Srdivacky // with a constant or another cast from the same type. 2600202375Srdivacky if (isa<Constant>(Op1) || isa<CastInst>(Op1)) 2601202375Srdivacky if (Instruction *R = visitICmpInstWithCastAndCast(I)) 2602202375Srdivacky return R; 2603202375Srdivacky } 2604218893Sdim 2605218893Sdim // Special logic for binary operators. 2606218893Sdim BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0); 2607218893Sdim BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1); 2608218893Sdim if (BO0 || BO1) { 2609218893Sdim CmpInst::Predicate Pred = I.getPredicate(); 2610218893Sdim bool NoOp0WrapProblem = false, NoOp1WrapProblem = false; 2611218893Sdim if (BO0 && isa<OverflowingBinaryOperator>(BO0)) 2612218893Sdim NoOp0WrapProblem = ICmpInst::isEquality(Pred) || 2613218893Sdim (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) || 2614218893Sdim (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap()); 2615218893Sdim if (BO1 && isa<OverflowingBinaryOperator>(BO1)) 2616218893Sdim NoOp1WrapProblem = ICmpInst::isEquality(Pred) || 2617218893Sdim (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) || 2618218893Sdim (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap()); 2619218893Sdim 2620218893Sdim // Analyze the case when either Op0 or Op1 is an add instruction. 2621218893Sdim // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null). 2622218893Sdim Value *A = 0, *B = 0, *C = 0, *D = 0; 2623218893Sdim if (BO0 && BO0->getOpcode() == Instruction::Add) 2624218893Sdim A = BO0->getOperand(0), B = BO0->getOperand(1); 2625218893Sdim if (BO1 && BO1->getOpcode() == Instruction::Add) 2626218893Sdim C = BO1->getOperand(0), D = BO1->getOperand(1); 2627218893Sdim 2628218893Sdim // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 2629218893Sdim if ((A == Op1 || B == Op1) && NoOp0WrapProblem) 2630218893Sdim return new ICmpInst(Pred, A == Op1 ? B : A, 2631218893Sdim Constant::getNullValue(Op1->getType())); 2632218893Sdim 2633218893Sdim // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 2634218893Sdim if ((C == Op0 || D == Op0) && NoOp1WrapProblem) 2635218893Sdim return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()), 2636218893Sdim C == Op0 ? D : C); 2637218893Sdim 2638218893Sdim // icmp (X+Y), (X+Z) -> icmp Y, Z for equalities or if there is no overflow. 2639218893Sdim if (A && C && (A == C || A == D || B == C || B == D) && 2640218893Sdim NoOp0WrapProblem && NoOp1WrapProblem && 2641218893Sdim // Try not to increase register pressure. 2642218893Sdim BO0->hasOneUse() && BO1->hasOneUse()) { 2643218893Sdim // Determine Y and Z in the form icmp (X+Y), (X+Z). 2644245431Sdim Value *Y, *Z; 2645245431Sdim if (A == C) { 2646245431Sdim // C + B == C + D -> B == D 2647245431Sdim Y = B; 2648245431Sdim Z = D; 2649245431Sdim } else if (A == D) { 2650245431Sdim // D + B == C + D -> B == C 2651245431Sdim Y = B; 2652245431Sdim Z = C; 2653245431Sdim } else if (B == C) { 2654245431Sdim // A + C == C + D -> A == D 2655245431Sdim Y = A; 2656245431Sdim Z = D; 2657245431Sdim } else { 2658245431Sdim assert(B == D); 2659245431Sdim // A + D == C + D -> A == C 2660245431Sdim Y = A; 2661245431Sdim Z = C; 2662245431Sdim } 2663218893Sdim return new ICmpInst(Pred, Y, Z); 2664218893Sdim } 2665218893Sdim 2666252723Sdim // icmp slt (X + -1), Y -> icmp sle X, Y 2667252723Sdim if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT && 2668252723Sdim match(B, m_AllOnes())) 2669252723Sdim return new ICmpInst(CmpInst::ICMP_SLE, A, Op1); 2670252723Sdim 2671252723Sdim // icmp sge (X + -1), Y -> icmp sgt X, Y 2672252723Sdim if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE && 2673252723Sdim match(B, m_AllOnes())) 2674252723Sdim return new ICmpInst(CmpInst::ICMP_SGT, A, Op1); 2675252723Sdim 2676252723Sdim // icmp sle (X + 1), Y -> icmp slt X, Y 2677252723Sdim if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE && 2678252723Sdim match(B, m_One())) 2679252723Sdim return new ICmpInst(CmpInst::ICMP_SLT, A, Op1); 2680252723Sdim 2681252723Sdim // icmp sgt (X + 1), Y -> icmp sge X, Y 2682252723Sdim if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT && 2683252723Sdim match(B, m_One())) 2684252723Sdim return new ICmpInst(CmpInst::ICMP_SGE, A, Op1); 2685252723Sdim 2686252723Sdim // if C1 has greater magnitude than C2: 2687252723Sdim // icmp (X + C1), (Y + C2) -> icmp (X + C3), Y 2688252723Sdim // s.t. C3 = C1 - C2 2689252723Sdim // 2690252723Sdim // if C2 has greater magnitude than C1: 2691252723Sdim // icmp (X + C1), (Y + C2) -> icmp X, (Y + C3) 2692252723Sdim // s.t. C3 = C2 - C1 2693252723Sdim if (A && C && NoOp0WrapProblem && NoOp1WrapProblem && 2694252723Sdim (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned()) 2695252723Sdim if (ConstantInt *C1 = dyn_cast<ConstantInt>(B)) 2696252723Sdim if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) { 2697252723Sdim const APInt &AP1 = C1->getValue(); 2698252723Sdim const APInt &AP2 = C2->getValue(); 2699252723Sdim if (AP1.isNegative() == AP2.isNegative()) { 2700252723Sdim APInt AP1Abs = C1->getValue().abs(); 2701252723Sdim APInt AP2Abs = C2->getValue().abs(); 2702252723Sdim if (AP1Abs.uge(AP2Abs)) { 2703252723Sdim ConstantInt *C3 = Builder->getInt(AP1 - AP2); 2704252723Sdim Value *NewAdd = Builder->CreateNSWAdd(A, C3); 2705252723Sdim return new ICmpInst(Pred, NewAdd, C); 2706252723Sdim } else { 2707252723Sdim ConstantInt *C3 = Builder->getInt(AP2 - AP1); 2708252723Sdim Value *NewAdd = Builder->CreateNSWAdd(C, C3); 2709252723Sdim return new ICmpInst(Pred, A, NewAdd); 2710252723Sdim } 2711252723Sdim } 2712252723Sdim } 2713252723Sdim 2714252723Sdim 2715218893Sdim // Analyze the case when either Op0 or Op1 is a sub instruction. 2716218893Sdim // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null). 2717218893Sdim A = 0; B = 0; C = 0; D = 0; 2718218893Sdim if (BO0 && BO0->getOpcode() == Instruction::Sub) 2719218893Sdim A = BO0->getOperand(0), B = BO0->getOperand(1); 2720218893Sdim if (BO1 && BO1->getOpcode() == Instruction::Sub) 2721218893Sdim C = BO1->getOperand(0), D = BO1->getOperand(1); 2722218893Sdim 2723218893Sdim // icmp (X-Y), X -> icmp 0, Y for equalities or if there is no overflow. 2724218893Sdim if (A == Op1 && NoOp0WrapProblem) 2725218893Sdim return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B); 2726218893Sdim 2727218893Sdim // icmp X, (X-Y) -> icmp Y, 0 for equalities or if there is no overflow. 2728218893Sdim if (C == Op0 && NoOp1WrapProblem) 2729218893Sdim return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType())); 2730218893Sdim 2731218893Sdim // icmp (Y-X), (Z-X) -> icmp Y, Z for equalities or if there is no overflow. 2732218893Sdim if (B && D && B == D && NoOp0WrapProblem && NoOp1WrapProblem && 2733218893Sdim // Try not to increase register pressure. 2734218893Sdim BO0->hasOneUse() && BO1->hasOneUse()) 2735218893Sdim return new ICmpInst(Pred, A, C); 2736218893Sdim 2737218893Sdim // icmp (X-Y), (X-Z) -> icmp Z, Y for equalities or if there is no overflow. 2738218893Sdim if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem && 2739218893Sdim // Try not to increase register pressure. 2740218893Sdim BO0->hasOneUse() && BO1->hasOneUse()) 2741218893Sdim return new ICmpInst(Pred, D, B); 2742218893Sdim 2743221345Sdim BinaryOperator *SRem = NULL; 2744221345Sdim // icmp (srem X, Y), Y 2745221345Sdim if (BO0 && BO0->getOpcode() == Instruction::SRem && 2746221345Sdim Op1 == BO0->getOperand(1)) 2747221345Sdim SRem = BO0; 2748221345Sdim // icmp Y, (srem X, Y) 2749221345Sdim else if (BO1 && BO1->getOpcode() == Instruction::SRem && 2750221345Sdim Op0 == BO1->getOperand(1)) 2751221345Sdim SRem = BO1; 2752221345Sdim if (SRem) { 2753221345Sdim // We don't check hasOneUse to avoid increasing register pressure because 2754221345Sdim // the value we use is the same value this instruction was already using. 2755221345Sdim switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) { 2756221345Sdim default: break; 2757221345Sdim case ICmpInst::ICMP_EQ: 2758221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2759221345Sdim case ICmpInst::ICMP_NE: 2760221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2761221345Sdim case ICmpInst::ICMP_SGT: 2762221345Sdim case ICmpInst::ICMP_SGE: 2763221345Sdim return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1), 2764221345Sdim Constant::getAllOnesValue(SRem->getType())); 2765221345Sdim case ICmpInst::ICMP_SLT: 2766221345Sdim case ICmpInst::ICMP_SLE: 2767221345Sdim return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1), 2768221345Sdim Constant::getNullValue(SRem->getType())); 2769221345Sdim } 2770221345Sdim } 2771221345Sdim 2772218893Sdim if (BO0 && BO1 && BO0->getOpcode() == BO1->getOpcode() && 2773218893Sdim BO0->hasOneUse() && BO1->hasOneUse() && 2774218893Sdim BO0->getOperand(1) == BO1->getOperand(1)) { 2775218893Sdim switch (BO0->getOpcode()) { 2776218893Sdim default: break; 2777218893Sdim case Instruction::Add: 2778218893Sdim case Instruction::Sub: 2779218893Sdim case Instruction::Xor: 2780218893Sdim if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b 2781218893Sdim return new ICmpInst(I.getPredicate(), BO0->getOperand(0), 2782218893Sdim BO1->getOperand(0)); 2783218893Sdim // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b 2784218893Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) { 2785218893Sdim if (CI->getValue().isSignBit()) { 2786218893Sdim ICmpInst::Predicate Pred = I.isSigned() 2787218893Sdim ? I.getUnsignedPredicate() 2788218893Sdim : I.getSignedPredicate(); 2789218893Sdim return new ICmpInst(Pred, BO0->getOperand(0), 2790218893Sdim BO1->getOperand(0)); 2791202375Srdivacky } 2792226890Sdim 2793224145Sdim if (CI->isMaxValue(true)) { 2794218893Sdim ICmpInst::Predicate Pred = I.isSigned() 2795218893Sdim ? I.getUnsignedPredicate() 2796218893Sdim : I.getSignedPredicate(); 2797218893Sdim Pred = I.getSwappedPredicate(Pred); 2798218893Sdim return new ICmpInst(Pred, BO0->getOperand(0), 2799218893Sdim BO1->getOperand(0)); 2800218893Sdim } 2801218893Sdim } 2802218893Sdim break; 2803218893Sdim case Instruction::Mul: 2804218893Sdim if (!I.isEquality()) 2805202375Srdivacky break; 2806202375Srdivacky 2807218893Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) { 2808218893Sdim // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask 2809218893Sdim // Mask = -1 >> count-trailing-zeros(Cst). 2810218893Sdim if (!CI->isZero() && !CI->isOne()) { 2811218893Sdim const APInt &AP = CI->getValue(); 2812226890Sdim ConstantInt *Mask = ConstantInt::get(I.getContext(), 2813218893Sdim APInt::getLowBitsSet(AP.getBitWidth(), 2814218893Sdim AP.getBitWidth() - 2815218893Sdim AP.countTrailingZeros())); 2816218893Sdim Value *And1 = Builder->CreateAnd(BO0->getOperand(0), Mask); 2817218893Sdim Value *And2 = Builder->CreateAnd(BO1->getOperand(0), Mask); 2818218893Sdim return new ICmpInst(I.getPredicate(), And1, And2); 2819202375Srdivacky } 2820202375Srdivacky } 2821218893Sdim break; 2822221345Sdim case Instruction::UDiv: 2823221345Sdim case Instruction::LShr: 2824221345Sdim if (I.isSigned()) 2825221345Sdim break; 2826221345Sdim // fall-through 2827221345Sdim case Instruction::SDiv: 2828221345Sdim case Instruction::AShr: 2829223017Sdim if (!BO0->isExact() || !BO1->isExact()) 2830221345Sdim break; 2831221345Sdim return new ICmpInst(I.getPredicate(), BO0->getOperand(0), 2832221345Sdim BO1->getOperand(0)); 2833221345Sdim case Instruction::Shl: { 2834221345Sdim bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap(); 2835221345Sdim bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap(); 2836221345Sdim if (!NUW && !NSW) 2837221345Sdim break; 2838221345Sdim if (!NSW && I.isSigned()) 2839221345Sdim break; 2840221345Sdim return new ICmpInst(I.getPredicate(), BO0->getOperand(0), 2841221345Sdim BO1->getOperand(0)); 2842202375Srdivacky } 2843221345Sdim } 2844202375Srdivacky } 2845202375Srdivacky } 2846226890Sdim 2847202375Srdivacky { Value *A, *B; 2848252723Sdim // Transform (A & ~B) == 0 --> (A & B) != 0 2849252723Sdim // and (A & ~B) != 0 --> (A & B) == 0 2850252723Sdim // if A is a power of 2. 2851252723Sdim if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) && 2852252723Sdim match(Op1, m_Zero()) && isKnownToBeAPowerOfTwo(A) && I.isEquality()) 2853252723Sdim return new ICmpInst(I.getInversePredicate(), 2854252723Sdim Builder->CreateAnd(A, B), 2855252723Sdim Op1); 2856252723Sdim 2857218893Sdim // ~x < ~y --> y < x 2858218893Sdim // ~x < cst --> ~cst < x 2859218893Sdim if (match(Op0, m_Not(m_Value(A)))) { 2860218893Sdim if (match(Op1, m_Not(m_Value(B)))) 2861218893Sdim return new ICmpInst(I.getPredicate(), B, A); 2862218893Sdim if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1)) 2863218893Sdim return new ICmpInst(I.getPredicate(), ConstantExpr::getNot(RHSC), A); 2864218893Sdim } 2865218893Sdim 2866218893Sdim // (a+b) <u a --> llvm.uadd.with.overflow. 2867218893Sdim // (a+b) <u b --> llvm.uadd.with.overflow. 2868218893Sdim if (I.getPredicate() == ICmpInst::ICMP_ULT && 2869226890Sdim match(Op0, m_Add(m_Value(A), m_Value(B))) && 2870218893Sdim (Op1 == A || Op1 == B)) 2871218893Sdim if (Instruction *R = ProcessUAddIdiom(I, Op0, *this)) 2872218893Sdim return R; 2873226890Sdim 2874218893Sdim // a >u (a+b) --> llvm.uadd.with.overflow. 2875218893Sdim // b >u (a+b) --> llvm.uadd.with.overflow. 2876218893Sdim if (I.getPredicate() == ICmpInst::ICMP_UGT && 2877218893Sdim match(Op1, m_Add(m_Value(A), m_Value(B))) && 2878218893Sdim (Op0 == A || Op0 == B)) 2879218893Sdim if (Instruction *R = ProcessUAddIdiom(I, Op1, *this)) 2880218893Sdim return R; 2881202375Srdivacky } 2882226890Sdim 2883202375Srdivacky if (I.isEquality()) { 2884202375Srdivacky Value *A, *B, *C, *D; 2885218893Sdim 2886202375Srdivacky if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) { 2887202375Srdivacky if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0 2888202375Srdivacky Value *OtherVal = A == Op1 ? B : A; 2889202375Srdivacky return new ICmpInst(I.getPredicate(), OtherVal, 2890202375Srdivacky Constant::getNullValue(A->getType())); 2891202375Srdivacky } 2892202375Srdivacky 2893202375Srdivacky if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) { 2894202375Srdivacky // A^c1 == C^c2 --> A == C^(c1^c2) 2895202375Srdivacky ConstantInt *C1, *C2; 2896202375Srdivacky if (match(B, m_ConstantInt(C1)) && 2897202375Srdivacky match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) { 2898263509Sdim Constant *NC = Builder->getInt(C1->getValue() ^ C2->getValue()); 2899226890Sdim Value *Xor = Builder->CreateXor(C, NC); 2900202375Srdivacky return new ICmpInst(I.getPredicate(), A, Xor); 2901202375Srdivacky } 2902226890Sdim 2903202375Srdivacky // A^B == A^D -> B == D 2904202375Srdivacky if (A == C) return new ICmpInst(I.getPredicate(), B, D); 2905202375Srdivacky if (A == D) return new ICmpInst(I.getPredicate(), B, C); 2906202375Srdivacky if (B == C) return new ICmpInst(I.getPredicate(), A, D); 2907202375Srdivacky if (B == D) return new ICmpInst(I.getPredicate(), A, C); 2908202375Srdivacky } 2909202375Srdivacky } 2910226890Sdim 2911202375Srdivacky if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && 2912202375Srdivacky (A == Op0 || B == Op0)) { 2913202375Srdivacky // A == (A^B) -> B == 0 2914202375Srdivacky Value *OtherVal = A == Op0 ? B : A; 2915202375Srdivacky return new ICmpInst(I.getPredicate(), OtherVal, 2916202375Srdivacky Constant::getNullValue(A->getType())); 2917202375Srdivacky } 2918202375Srdivacky 2919202375Srdivacky // (X&Z) == (Y&Z) -> (X^Y) & Z == 0 2920226890Sdim if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) && 2921221345Sdim match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) { 2922202375Srdivacky Value *X = 0, *Y = 0, *Z = 0; 2923226890Sdim 2924202375Srdivacky if (A == C) { 2925202375Srdivacky X = B; Y = D; Z = A; 2926202375Srdivacky } else if (A == D) { 2927202375Srdivacky X = B; Y = C; Z = A; 2928202375Srdivacky } else if (B == C) { 2929202375Srdivacky X = A; Y = D; Z = B; 2930202375Srdivacky } else if (B == D) { 2931202375Srdivacky X = A; Y = C; Z = B; 2932202375Srdivacky } 2933226890Sdim 2934202375Srdivacky if (X) { // Build (X^Y) & Z 2935226890Sdim Op1 = Builder->CreateXor(X, Y); 2936226890Sdim Op1 = Builder->CreateAnd(Op1, Z); 2937202375Srdivacky I.setOperand(0, Op1); 2938202375Srdivacky I.setOperand(1, Constant::getNullValue(Op1->getType())); 2939202375Srdivacky return &I; 2940202375Srdivacky } 2941202375Srdivacky } 2942226890Sdim 2943245431Sdim // Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B) 2944245431Sdim // and (B & (1<<X)-1) == (zext A) --> A == (trunc B) 2945245431Sdim ConstantInt *Cst1; 2946245431Sdim if ((Op0->hasOneUse() && 2947245431Sdim match(Op0, m_ZExt(m_Value(A))) && 2948245431Sdim match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) || 2949245431Sdim (Op1->hasOneUse() && 2950245431Sdim match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) && 2951245431Sdim match(Op1, m_ZExt(m_Value(A))))) { 2952245431Sdim APInt Pow2 = Cst1->getValue() + 1; 2953245431Sdim if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) && 2954245431Sdim Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth()) 2955245431Sdim return new ICmpInst(I.getPredicate(), A, 2956245431Sdim Builder->CreateTrunc(B, A->getType())); 2957245431Sdim } 2958245431Sdim 2959263509Sdim // (A >> C) == (B >> C) --> (A^B) u< (1 << C) 2960263509Sdim // For lshr and ashr pairs. 2961263509Sdim if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_ConstantInt(Cst1)))) && 2962263509Sdim match(Op1, m_OneUse(m_LShr(m_Value(B), m_Specific(Cst1))))) || 2963263509Sdim (match(Op0, m_OneUse(m_AShr(m_Value(A), m_ConstantInt(Cst1)))) && 2964263509Sdim match(Op1, m_OneUse(m_AShr(m_Value(B), m_Specific(Cst1)))))) { 2965263509Sdim unsigned TypeBits = Cst1->getBitWidth(); 2966263509Sdim unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits); 2967263509Sdim if (ShAmt < TypeBits && ShAmt != 0) { 2968263509Sdim ICmpInst::Predicate Pred = I.getPredicate() == ICmpInst::ICMP_NE 2969263509Sdim ? ICmpInst::ICMP_UGE 2970263509Sdim : ICmpInst::ICMP_ULT; 2971263509Sdim Value *Xor = Builder->CreateXor(A, B, I.getName() + ".unshifted"); 2972263509Sdim APInt CmpVal = APInt::getOneBitSet(TypeBits, ShAmt); 2973263509Sdim return new ICmpInst(Pred, Xor, Builder->getInt(CmpVal)); 2974263509Sdim } 2975263509Sdim } 2976263509Sdim 2977221345Sdim // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to 2978221345Sdim // "icmp (and X, mask), cst" 2979221345Sdim uint64_t ShAmt = 0; 2980221345Sdim if (Op0->hasOneUse() && 2981221345Sdim match(Op0, m_Trunc(m_OneUse(m_LShr(m_Value(A), 2982221345Sdim m_ConstantInt(ShAmt))))) && 2983221345Sdim match(Op1, m_ConstantInt(Cst1)) && 2984221345Sdim // Only do this when A has multiple uses. This is most important to do 2985221345Sdim // when it exposes other optimizations. 2986221345Sdim !A->hasOneUse()) { 2987221345Sdim unsigned ASize =cast<IntegerType>(A->getType())->getPrimitiveSizeInBits(); 2988226890Sdim 2989221345Sdim if (ShAmt < ASize) { 2990221345Sdim APInt MaskV = 2991221345Sdim APInt::getLowBitsSet(ASize, Op0->getType()->getPrimitiveSizeInBits()); 2992221345Sdim MaskV <<= ShAmt; 2993226890Sdim 2994221345Sdim APInt CmpV = Cst1->getValue().zext(ASize); 2995221345Sdim CmpV <<= ShAmt; 2996226890Sdim 2997221345Sdim Value *Mask = Builder->CreateAnd(A, Builder->getInt(MaskV)); 2998221345Sdim return new ICmpInst(I.getPredicate(), Mask, Builder->getInt(CmpV)); 2999221345Sdim } 3000221345Sdim } 3001202375Srdivacky } 3002226890Sdim 3003202375Srdivacky { 3004202375Srdivacky Value *X; ConstantInt *Cst; 3005202375Srdivacky // icmp X+Cst, X 3006202375Srdivacky if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X) 3007263509Sdim return FoldICmpAddOpCst(I, X, Cst, I.getPredicate()); 3008202375Srdivacky 3009202375Srdivacky // icmp X, X+Cst 3010202375Srdivacky if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X) 3011263509Sdim return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate()); 3012202375Srdivacky } 3013202375Srdivacky return Changed ? &I : 0; 3014202375Srdivacky} 3015202375Srdivacky 3016202375Srdivacky/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible. 3017202375Srdivacky/// 3018202375SrdivackyInstruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I, 3019202375Srdivacky Instruction *LHSI, 3020202375Srdivacky Constant *RHSC) { 3021202375Srdivacky if (!isa<ConstantFP>(RHSC)) return 0; 3022202375Srdivacky const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF(); 3023226890Sdim 3024202375Srdivacky // Get the width of the mantissa. We don't want to hack on conversions that 3025202375Srdivacky // might lose information from the integer, e.g. "i64 -> float" 3026202375Srdivacky int MantissaWidth = LHSI->getType()->getFPMantissaWidth(); 3027202375Srdivacky if (MantissaWidth == -1) return 0; // Unknown. 3028226890Sdim 3029202375Srdivacky // Check to see that the input is converted from an integer type that is small 3030202375Srdivacky // enough that preserves all bits. TODO: check here for "known" sign bits. 3031202375Srdivacky // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e. 3032202375Srdivacky unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits(); 3033226890Sdim 3034202375Srdivacky // If this is a uitofp instruction, we need an extra bit to hold the sign. 3035202375Srdivacky bool LHSUnsigned = isa<UIToFPInst>(LHSI); 3036202375Srdivacky if (LHSUnsigned) 3037202375Srdivacky ++InputSize; 3038226890Sdim 3039202375Srdivacky // If the conversion would lose info, don't hack on this. 3040202375Srdivacky if ((int)InputSize > MantissaWidth) 3041202375Srdivacky return 0; 3042226890Sdim 3043202375Srdivacky // Otherwise, we can potentially simplify the comparison. We know that it 3044202375Srdivacky // will always come through as an integer value and we know the constant is 3045202375Srdivacky // not a NAN (it would have been previously simplified). 3046202375Srdivacky assert(!RHS.isNaN() && "NaN comparison not already folded!"); 3047226890Sdim 3048202375Srdivacky ICmpInst::Predicate Pred; 3049202375Srdivacky switch (I.getPredicate()) { 3050202375Srdivacky default: llvm_unreachable("Unexpected predicate!"); 3051202375Srdivacky case FCmpInst::FCMP_UEQ: 3052202375Srdivacky case FCmpInst::FCMP_OEQ: 3053202375Srdivacky Pred = ICmpInst::ICMP_EQ; 3054202375Srdivacky break; 3055202375Srdivacky case FCmpInst::FCMP_UGT: 3056202375Srdivacky case FCmpInst::FCMP_OGT: 3057202375Srdivacky Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT; 3058202375Srdivacky break; 3059202375Srdivacky case FCmpInst::FCMP_UGE: 3060202375Srdivacky case FCmpInst::FCMP_OGE: 3061202375Srdivacky Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE; 3062202375Srdivacky break; 3063202375Srdivacky case FCmpInst::FCMP_ULT: 3064202375Srdivacky case FCmpInst::FCMP_OLT: 3065202375Srdivacky Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT; 3066202375Srdivacky break; 3067202375Srdivacky case FCmpInst::FCMP_ULE: 3068202375Srdivacky case FCmpInst::FCMP_OLE: 3069202375Srdivacky Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE; 3070202375Srdivacky break; 3071202375Srdivacky case FCmpInst::FCMP_UNE: 3072202375Srdivacky case FCmpInst::FCMP_ONE: 3073202375Srdivacky Pred = ICmpInst::ICMP_NE; 3074202375Srdivacky break; 3075202375Srdivacky case FCmpInst::FCMP_ORD: 3076263509Sdim return ReplaceInstUsesWith(I, Builder->getTrue()); 3077202375Srdivacky case FCmpInst::FCMP_UNO: 3078263509Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3079202375Srdivacky } 3080226890Sdim 3081226890Sdim IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType()); 3082226890Sdim 3083202375Srdivacky // Now we know that the APFloat is a normal number, zero or inf. 3084226890Sdim 3085202375Srdivacky // See if the FP constant is too large for the integer. For example, 3086202375Srdivacky // comparing an i8 to 300.0. 3087202375Srdivacky unsigned IntWidth = IntTy->getScalarSizeInBits(); 3088226890Sdim 3089202375Srdivacky if (!LHSUnsigned) { 3090202375Srdivacky // If the RHS value is > SignedMax, fold the comparison. This handles +INF 3091202375Srdivacky // and large values. 3092263509Sdim APFloat SMax(RHS.getSemantics()); 3093202375Srdivacky SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true, 3094202375Srdivacky APFloat::rmNearestTiesToEven); 3095202375Srdivacky if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0 3096202375Srdivacky if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT || 3097202375Srdivacky Pred == ICmpInst::ICMP_SLE) 3098263509Sdim return ReplaceInstUsesWith(I, Builder->getTrue()); 3099263509Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3100202375Srdivacky } 3101202375Srdivacky } else { 3102202375Srdivacky // If the RHS value is > UnsignedMax, fold the comparison. This handles 3103202375Srdivacky // +INF and large values. 3104263509Sdim APFloat UMax(RHS.getSemantics()); 3105202375Srdivacky UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false, 3106202375Srdivacky APFloat::rmNearestTiesToEven); 3107202375Srdivacky if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0 3108202375Srdivacky if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT || 3109202375Srdivacky Pred == ICmpInst::ICMP_ULE) 3110263509Sdim return ReplaceInstUsesWith(I, Builder->getTrue()); 3111263509Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3112202375Srdivacky } 3113202375Srdivacky } 3114226890Sdim 3115202375Srdivacky if (!LHSUnsigned) { 3116202375Srdivacky // See if the RHS value is < SignedMin. 3117263509Sdim APFloat SMin(RHS.getSemantics()); 3118202375Srdivacky SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true, 3119202375Srdivacky APFloat::rmNearestTiesToEven); 3120202375Srdivacky if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0 3121202375Srdivacky if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT || 3122202375Srdivacky Pred == ICmpInst::ICMP_SGE) 3123263509Sdim return ReplaceInstUsesWith(I, Builder->getTrue()); 3124263509Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3125202375Srdivacky } 3126235633Sdim } else { 3127235633Sdim // See if the RHS value is < UnsignedMin. 3128263509Sdim APFloat SMin(RHS.getSemantics()); 3129235633Sdim SMin.convertFromAPInt(APInt::getMinValue(IntWidth), true, 3130235633Sdim APFloat::rmNearestTiesToEven); 3131235633Sdim if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // umin > 12312.0 3132235633Sdim if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_UGT || 3133235633Sdim Pred == ICmpInst::ICMP_UGE) 3134263509Sdim return ReplaceInstUsesWith(I, Builder->getTrue()); 3135263509Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3136235633Sdim } 3137202375Srdivacky } 3138202375Srdivacky 3139202375Srdivacky // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or 3140202375Srdivacky // [0, UMAX], but it may still be fractional. See if it is fractional by 3141202375Srdivacky // casting the FP value to the integer value and back, checking for equality. 3142202375Srdivacky // Don't do this for zero, because -0.0 is not fractional. 3143202375Srdivacky Constant *RHSInt = LHSUnsigned 3144202375Srdivacky ? ConstantExpr::getFPToUI(RHSC, IntTy) 3145202375Srdivacky : ConstantExpr::getFPToSI(RHSC, IntTy); 3146202375Srdivacky if (!RHS.isZero()) { 3147202375Srdivacky bool Equal = LHSUnsigned 3148202375Srdivacky ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC 3149202375Srdivacky : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC; 3150202375Srdivacky if (!Equal) { 3151202375Srdivacky // If we had a comparison against a fractional value, we have to adjust 3152202375Srdivacky // the compare predicate and sometimes the value. RHSC is rounded towards 3153202375Srdivacky // zero at this point. 3154202375Srdivacky switch (Pred) { 3155202375Srdivacky default: llvm_unreachable("Unexpected integer comparison!"); 3156202375Srdivacky case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true 3157263509Sdim return ReplaceInstUsesWith(I, Builder->getTrue()); 3158202375Srdivacky case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false 3159263509Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3160202375Srdivacky case ICmpInst::ICMP_ULE: 3161202375Srdivacky // (float)int <= 4.4 --> int <= 4 3162202375Srdivacky // (float)int <= -4.4 --> false 3163202375Srdivacky if (RHS.isNegative()) 3164263509Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3165202375Srdivacky break; 3166202375Srdivacky case ICmpInst::ICMP_SLE: 3167202375Srdivacky // (float)int <= 4.4 --> int <= 4 3168202375Srdivacky // (float)int <= -4.4 --> int < -4 3169202375Srdivacky if (RHS.isNegative()) 3170202375Srdivacky Pred = ICmpInst::ICMP_SLT; 3171202375Srdivacky break; 3172202375Srdivacky case ICmpInst::ICMP_ULT: 3173202375Srdivacky // (float)int < -4.4 --> false 3174202375Srdivacky // (float)int < 4.4 --> int <= 4 3175202375Srdivacky if (RHS.isNegative()) 3176263509Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3177202375Srdivacky Pred = ICmpInst::ICMP_ULE; 3178202375Srdivacky break; 3179202375Srdivacky case ICmpInst::ICMP_SLT: 3180202375Srdivacky // (float)int < -4.4 --> int < -4 3181202375Srdivacky // (float)int < 4.4 --> int <= 4 3182202375Srdivacky if (!RHS.isNegative()) 3183202375Srdivacky Pred = ICmpInst::ICMP_SLE; 3184202375Srdivacky break; 3185202375Srdivacky case ICmpInst::ICMP_UGT: 3186202375Srdivacky // (float)int > 4.4 --> int > 4 3187202375Srdivacky // (float)int > -4.4 --> true 3188202375Srdivacky if (RHS.isNegative()) 3189263509Sdim return ReplaceInstUsesWith(I, Builder->getTrue()); 3190202375Srdivacky break; 3191202375Srdivacky case ICmpInst::ICMP_SGT: 3192202375Srdivacky // (float)int > 4.4 --> int > 4 3193202375Srdivacky // (float)int > -4.4 --> int >= -4 3194202375Srdivacky if (RHS.isNegative()) 3195202375Srdivacky Pred = ICmpInst::ICMP_SGE; 3196202375Srdivacky break; 3197202375Srdivacky case ICmpInst::ICMP_UGE: 3198202375Srdivacky // (float)int >= -4.4 --> true 3199202375Srdivacky // (float)int >= 4.4 --> int > 4 3200245431Sdim if (RHS.isNegative()) 3201263509Sdim return ReplaceInstUsesWith(I, Builder->getTrue()); 3202202375Srdivacky Pred = ICmpInst::ICMP_UGT; 3203202375Srdivacky break; 3204202375Srdivacky case ICmpInst::ICMP_SGE: 3205202375Srdivacky // (float)int >= -4.4 --> int >= -4 3206202375Srdivacky // (float)int >= 4.4 --> int > 4 3207202375Srdivacky if (!RHS.isNegative()) 3208202375Srdivacky Pred = ICmpInst::ICMP_SGT; 3209202375Srdivacky break; 3210202375Srdivacky } 3211202375Srdivacky } 3212202375Srdivacky } 3213202375Srdivacky 3214202375Srdivacky // Lower this FP comparison into an appropriate integer version of the 3215202375Srdivacky // comparison. 3216202375Srdivacky return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt); 3217202375Srdivacky} 3218202375Srdivacky 3219202375SrdivackyInstruction *InstCombiner::visitFCmpInst(FCmpInst &I) { 3220202375Srdivacky bool Changed = false; 3221226890Sdim 3222202375Srdivacky /// Orders the operands of the compare so that they are listed from most 3223202375Srdivacky /// complex to least complex. This puts constants before unary operators, 3224202375Srdivacky /// before binary operators. 3225202375Srdivacky if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) { 3226202375Srdivacky I.swapOperands(); 3227202375Srdivacky Changed = true; 3228202375Srdivacky } 3229202375Srdivacky 3230202375Srdivacky Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); 3231226890Sdim 3232202375Srdivacky if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, TD)) 3233202375Srdivacky return ReplaceInstUsesWith(I, V); 3234202375Srdivacky 3235202375Srdivacky // Simplify 'fcmp pred X, X' 3236202375Srdivacky if (Op0 == Op1) { 3237202375Srdivacky switch (I.getPredicate()) { 3238202375Srdivacky default: llvm_unreachable("Unknown predicate!"); 3239202375Srdivacky case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y) 3240202375Srdivacky case FCmpInst::FCMP_ULT: // True if unordered or less than 3241202375Srdivacky case FCmpInst::FCMP_UGT: // True if unordered or greater than 3242202375Srdivacky case FCmpInst::FCMP_UNE: // True if unordered or not equal 3243202375Srdivacky // Canonicalize these to be 'fcmp uno %X, 0.0'. 3244202375Srdivacky I.setPredicate(FCmpInst::FCMP_UNO); 3245202375Srdivacky I.setOperand(1, Constant::getNullValue(Op0->getType())); 3246202375Srdivacky return &I; 3247226890Sdim 3248202375Srdivacky case FCmpInst::FCMP_ORD: // True if ordered (no nans) 3249202375Srdivacky case FCmpInst::FCMP_OEQ: // True if ordered and equal 3250202375Srdivacky case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal 3251202375Srdivacky case FCmpInst::FCMP_OLE: // True if ordered and less than or equal 3252202375Srdivacky // Canonicalize these to be 'fcmp ord %X, 0.0'. 3253202375Srdivacky I.setPredicate(FCmpInst::FCMP_ORD); 3254202375Srdivacky I.setOperand(1, Constant::getNullValue(Op0->getType())); 3255202375Srdivacky return &I; 3256202375Srdivacky } 3257202375Srdivacky } 3258226890Sdim 3259202375Srdivacky // Handle fcmp with constant RHS 3260202375Srdivacky if (Constant *RHSC = dyn_cast<Constant>(Op1)) { 3261202375Srdivacky if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) 3262202375Srdivacky switch (LHSI->getOpcode()) { 3263221345Sdim case Instruction::FPExt: { 3264221345Sdim // fcmp (fpext x), C -> fcmp x, (fptrunc C) if fptrunc is lossless 3265221345Sdim FPExtInst *LHSExt = cast<FPExtInst>(LHSI); 3266221345Sdim ConstantFP *RHSF = dyn_cast<ConstantFP>(RHSC); 3267221345Sdim if (!RHSF) 3268221345Sdim break; 3269221345Sdim 3270221345Sdim const fltSemantics *Sem; 3271221345Sdim // FIXME: This shouldn't be here. 3272235633Sdim if (LHSExt->getSrcTy()->isHalfTy()) 3273235633Sdim Sem = &APFloat::IEEEhalf; 3274235633Sdim else if (LHSExt->getSrcTy()->isFloatTy()) 3275221345Sdim Sem = &APFloat::IEEEsingle; 3276221345Sdim else if (LHSExt->getSrcTy()->isDoubleTy()) 3277221345Sdim Sem = &APFloat::IEEEdouble; 3278221345Sdim else if (LHSExt->getSrcTy()->isFP128Ty()) 3279221345Sdim Sem = &APFloat::IEEEquad; 3280221345Sdim else if (LHSExt->getSrcTy()->isX86_FP80Ty()) 3281221345Sdim Sem = &APFloat::x87DoubleExtended; 3282245431Sdim else if (LHSExt->getSrcTy()->isPPC_FP128Ty()) 3283245431Sdim Sem = &APFloat::PPCDoubleDouble; 3284221345Sdim else 3285221345Sdim break; 3286221345Sdim 3287221345Sdim bool Lossy; 3288221345Sdim APFloat F = RHSF->getValueAPF(); 3289221345Sdim F.convert(*Sem, APFloat::rmNearestTiesToEven, &Lossy); 3290221345Sdim 3291226890Sdim // Avoid lossy conversions and denormals. Zero is a special case 3292226890Sdim // that's OK to convert. 3293226890Sdim APFloat Fabs = F; 3294226890Sdim Fabs.clearSign(); 3295221345Sdim if (!Lossy && 3296226890Sdim ((Fabs.compare(APFloat::getSmallestNormalized(*Sem)) != 3297226890Sdim APFloat::cmpLessThan) || Fabs.isZero())) 3298226890Sdim 3299221345Sdim return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0), 3300221345Sdim ConstantFP::get(RHSC->getContext(), F)); 3301221345Sdim break; 3302221345Sdim } 3303202375Srdivacky case Instruction::PHI: 3304202375Srdivacky // Only fold fcmp into the PHI if the phi and fcmp are in the same 3305202375Srdivacky // block. If in the same block, we're encouraging jump threading. If 3306202375Srdivacky // not, we are just pessimizing the code by making an i1 phi. 3307202375Srdivacky if (LHSI->getParent() == I.getParent()) 3308218893Sdim if (Instruction *NV = FoldOpIntoPhi(I)) 3309202375Srdivacky return NV; 3310202375Srdivacky break; 3311202375Srdivacky case Instruction::SIToFP: 3312202375Srdivacky case Instruction::UIToFP: 3313202375Srdivacky if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC)) 3314202375Srdivacky return NV; 3315202375Srdivacky break; 3316202375Srdivacky case Instruction::Select: { 3317202375Srdivacky // If either operand of the select is a constant, we can fold the 3318202375Srdivacky // comparison into the select arms, which will cause one to be 3319202375Srdivacky // constant folded and the select turned into a bitwise or. 3320202375Srdivacky Value *Op1 = 0, *Op2 = 0; 3321202375Srdivacky if (LHSI->hasOneUse()) { 3322202375Srdivacky if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) { 3323202375Srdivacky // Fold the known value into the constant operand. 3324202375Srdivacky Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); 3325202375Srdivacky // Insert a new FCmp of the other select operand. 3326202375Srdivacky Op2 = Builder->CreateFCmp(I.getPredicate(), 3327202375Srdivacky LHSI->getOperand(2), RHSC, I.getName()); 3328202375Srdivacky } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) { 3329202375Srdivacky // Fold the known value into the constant operand. 3330202375Srdivacky Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); 3331202375Srdivacky // Insert a new FCmp of the other select operand. 3332202375Srdivacky Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1), 3333202375Srdivacky RHSC, I.getName()); 3334202375Srdivacky } 3335202375Srdivacky } 3336202375Srdivacky 3337202375Srdivacky if (Op1) 3338202375Srdivacky return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); 3339202375Srdivacky break; 3340202375Srdivacky } 3341221345Sdim case Instruction::FSub: { 3342221345Sdim // fcmp pred (fneg x), C -> fcmp swap(pred) x, -C 3343221345Sdim Value *Op; 3344221345Sdim if (match(LHSI, m_FNeg(m_Value(Op)))) 3345221345Sdim return new FCmpInst(I.getSwappedPredicate(), Op, 3346221345Sdim ConstantExpr::getFNeg(RHSC)); 3347221345Sdim break; 3348221345Sdim } 3349204642Srdivacky case Instruction::Load: 3350204642Srdivacky if (GetElementPtrInst *GEP = 3351204642Srdivacky dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) { 3352204642Srdivacky if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) 3353204642Srdivacky if (GV->isConstant() && GV->hasDefinitiveInitializer() && 3354204642Srdivacky !cast<LoadInst>(LHSI)->isVolatile()) 3355204642Srdivacky if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) 3356204642Srdivacky return Res; 3357204642Srdivacky } 3358204642Srdivacky break; 3359245431Sdim case Instruction::Call: { 3360245431Sdim CallInst *CI = cast<CallInst>(LHSI); 3361245431Sdim LibFunc::Func Func; 3362245431Sdim // Various optimization for fabs compared with zero. 3363245431Sdim if (RHSC->isNullValue() && CI->getCalledFunction() && 3364245431Sdim TLI->getLibFunc(CI->getCalledFunction()->getName(), Func) && 3365245431Sdim TLI->has(Func)) { 3366245431Sdim if (Func == LibFunc::fabs || Func == LibFunc::fabsf || 3367245431Sdim Func == LibFunc::fabsl) { 3368245431Sdim switch (I.getPredicate()) { 3369245431Sdim default: break; 3370245431Sdim // fabs(x) < 0 --> false 3371245431Sdim case FCmpInst::FCMP_OLT: 3372245431Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3373245431Sdim // fabs(x) > 0 --> x != 0 3374245431Sdim case FCmpInst::FCMP_OGT: 3375245431Sdim return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0), 3376245431Sdim RHSC); 3377245431Sdim // fabs(x) <= 0 --> x == 0 3378245431Sdim case FCmpInst::FCMP_OLE: 3379245431Sdim return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0), 3380245431Sdim RHSC); 3381245431Sdim // fabs(x) >= 0 --> !isnan(x) 3382245431Sdim case FCmpInst::FCMP_OGE: 3383245431Sdim return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0), 3384245431Sdim RHSC); 3385245431Sdim // fabs(x) == 0 --> x == 0 3386245431Sdim // fabs(x) != 0 --> x != 0 3387245431Sdim case FCmpInst::FCMP_OEQ: 3388245431Sdim case FCmpInst::FCMP_UEQ: 3389245431Sdim case FCmpInst::FCMP_ONE: 3390245431Sdim case FCmpInst::FCMP_UNE: 3391245431Sdim return new FCmpInst(I.getPredicate(), CI->getArgOperand(0), 3392245431Sdim RHSC); 3393245431Sdim } 3394245431Sdim } 3395245431Sdim } 3396202375Srdivacky } 3397245431Sdim } 3398202375Srdivacky } 3399202375Srdivacky 3400221345Sdim // fcmp pred (fneg x), (fneg y) -> fcmp swap(pred) x, y 3401221345Sdim Value *X, *Y; 3402221345Sdim if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_FNeg(m_Value(Y)))) 3403221345Sdim return new FCmpInst(I.getSwappedPredicate(), X, Y); 3404221345Sdim 3405221345Sdim // fcmp (fpext x), (fpext y) -> fcmp x, y 3406221345Sdim if (FPExtInst *LHSExt = dyn_cast<FPExtInst>(Op0)) 3407221345Sdim if (FPExtInst *RHSExt = dyn_cast<FPExtInst>(Op1)) 3408221345Sdim if (LHSExt->getSrcTy() == RHSExt->getSrcTy()) 3409221345Sdim return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0), 3410221345Sdim RHSExt->getOperand(0)); 3411221345Sdim 3412202375Srdivacky return Changed ? &I : 0; 3413202375Srdivacky} 3414