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" 15226633Sdim#include "llvm/Analysis/ConstantFolding.h" 16202375Srdivacky#include "llvm/Analysis/InstructionSimplify.h" 17202375Srdivacky#include "llvm/Analysis/MemoryBuiltins.h" 18249423Sdim#include "llvm/IR/DataLayout.h" 19249423Sdim#include "llvm/IR/IntrinsicInst.h" 20202375Srdivacky#include "llvm/Support/ConstantRange.h" 21202375Srdivacky#include "llvm/Support/GetElementPtrTypeIterator.h" 22202375Srdivacky#include "llvm/Support/PatternMatch.h" 23249423Sdim#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 61226633Sdim 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()); 83226633Sdim 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 96226633Sdim 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); 133226633Sdim 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 142249423Sdim/// Returns true if the exploded icmp can be expressed as a signed comparison 143249423Sdim/// to zero and updates the predicate accordingly. 144249423Sdim/// The signedness of the comparison is preserved. 145249423Sdimstatic bool isSignTest(ICmpInst::Predicate &pred, const ConstantInt *RHS) { 146249423Sdim if (!ICmpInst::isSigned(pred)) 147249423Sdim return false; 148249423Sdim 149249423Sdim if (RHS->isZero()) 150249423Sdim return ICmpInst::isRelational(pred); 151249423Sdim 152249423Sdim if (RHS->isOne()) { 153249423Sdim if (pred == ICmpInst::ICMP_SLT) { 154249423Sdim pred = ICmpInst::ICMP_SLE; 155249423Sdim return true; 156249423Sdim } 157249423Sdim } else if (RHS->isAllOnesValue()) { 158249423Sdim if (pred == ICmpInst::ICMP_SGT) { 159249423Sdim pred = ICmpInst::ICMP_SGE; 160249423Sdim return true; 161249423Sdim } 162249423Sdim } 163249423Sdim 164249423Sdim return false; 165249423Sdim} 166249423Sdim 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 173226633Sdim/// 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; 190226633Sdim 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); 209226633Sdim 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. 230202375Srdivacky if (!GEP->isInBounds() && TD == 0) return 0; 231226633Sdim 232234353Sdim Constant *Init = GV->getInitializer(); 233234353Sdim if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init)) 234234353Sdim return 0; 235251662Sdim 236234353Sdim uint64_t ArrayElementCount = Init->getType()->getArrayNumElements(); 237234353Sdim if (ArrayElementCount > 1024) return 0; // Don't blow up on huge arrays. 238226633Sdim 239202375Srdivacky // There are many forms of this optimization we can handle, for now, just do 240202375Srdivacky // the simple index into a single-dimensional array. 241202375Srdivacky // 242202375Srdivacky // Require: GEP GV, 0, i {{, constant indices}} 243202375Srdivacky if (GEP->getNumOperands() < 3 || 244202375Srdivacky !isa<ConstantInt>(GEP->getOperand(1)) || 245202375Srdivacky !cast<ConstantInt>(GEP->getOperand(1))->isZero() || 246202375Srdivacky isa<Constant>(GEP->getOperand(2))) 247202375Srdivacky return 0; 248202375Srdivacky 249202375Srdivacky // Check that indices after the variable are constants and in-range for the 250202375Srdivacky // type they index. Collect the indices. This is typically for arrays of 251202375Srdivacky // structs. 252202375Srdivacky SmallVector<unsigned, 4> LaterIndices; 253226633Sdim 254234353Sdim Type *EltTy = Init->getType()->getArrayElementType(); 255202375Srdivacky for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) { 256202375Srdivacky ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i)); 257202375Srdivacky if (Idx == 0) return 0; // Variable index. 258226633Sdim 259202375Srdivacky uint64_t IdxVal = Idx->getZExtValue(); 260202375Srdivacky if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index. 261226633Sdim 262226633Sdim if (StructType *STy = dyn_cast<StructType>(EltTy)) 263202375Srdivacky EltTy = STy->getElementType(IdxVal); 264226633Sdim else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) { 265202375Srdivacky if (IdxVal >= ATy->getNumElements()) return 0; 266202375Srdivacky EltTy = ATy->getElementType(); 267202375Srdivacky } else { 268202375Srdivacky return 0; // Unknown type. 269202375Srdivacky } 270226633Sdim 271202375Srdivacky LaterIndices.push_back(IdxVal); 272202375Srdivacky } 273226633Sdim 274202375Srdivacky enum { Overdefined = -3, Undefined = -2 }; 275202375Srdivacky 276202375Srdivacky // Variables for our state machines. 277226633Sdim 278202375Srdivacky // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form 279202375Srdivacky // "i == 47 | i == 87", where 47 is the first index the condition is true for, 280202375Srdivacky // and 87 is the second (and last) index. FirstTrueElement is -2 when 281202375Srdivacky // undefined, otherwise set to the first true element. SecondTrueElement is 282202375Srdivacky // -2 when undefined, -3 when overdefined and >= 0 when that index is true. 283202375Srdivacky int FirstTrueElement = Undefined, SecondTrueElement = Undefined; 284202375Srdivacky 285202375Srdivacky // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the 286202375Srdivacky // form "i != 47 & i != 87". Same state transitions as for true elements. 287202375Srdivacky int FirstFalseElement = Undefined, SecondFalseElement = Undefined; 288226633Sdim 289202375Srdivacky /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these 290202375Srdivacky /// define a state machine that triggers for ranges of values that the index 291202375Srdivacky /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'. 292202375Srdivacky /// This is -2 when undefined, -3 when overdefined, and otherwise the last 293202375Srdivacky /// index in the range (inclusive). We use -2 for undefined here because we 294202375Srdivacky /// use relative comparisons and don't want 0-1 to match -1. 295202375Srdivacky int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined; 296226633Sdim 297202375Srdivacky // MagicBitvector - This is a magic bitvector where we set a bit if the 298202375Srdivacky // comparison is true for element 'i'. If there are 64 elements or less in 299202375Srdivacky // the array, this will fully represent all the comparison results. 300202375Srdivacky uint64_t MagicBitvector = 0; 301226633Sdim 302226633Sdim 303202375Srdivacky // Scan the array and see if one of our patterns matches. 304202375Srdivacky Constant *CompareRHS = cast<Constant>(ICI.getOperand(1)); 305234353Sdim for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) { 306234353Sdim Constant *Elt = Init->getAggregateElement(i); 307234353Sdim if (Elt == 0) return 0; 308226633Sdim 309202375Srdivacky // If this is indexing an array of structures, get the structure element. 310202375Srdivacky if (!LaterIndices.empty()) 311224145Sdim Elt = ConstantExpr::getExtractValue(Elt, LaterIndices); 312226633Sdim 313202375Srdivacky // If the element is masked, handle it. 314202375Srdivacky if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst); 315226633Sdim 316202375Srdivacky // Find out if the comparison would be true or false for the i'th element. 317202375Srdivacky Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt, 318234353Sdim CompareRHS, TD, TLI); 319202375Srdivacky // If the result is undef for this element, ignore it. 320202375Srdivacky if (isa<UndefValue>(C)) { 321202375Srdivacky // Extend range state machines to cover this element in case there is an 322202375Srdivacky // undef in the middle of the range. 323202375Srdivacky if (TrueRangeEnd == (int)i-1) 324202375Srdivacky TrueRangeEnd = i; 325202375Srdivacky if (FalseRangeEnd == (int)i-1) 326202375Srdivacky FalseRangeEnd = i; 327202375Srdivacky continue; 328202375Srdivacky } 329226633Sdim 330202375Srdivacky // If we can't compute the result for any of the elements, we have to give 331202375Srdivacky // up evaluating the entire conditional. 332202375Srdivacky if (!isa<ConstantInt>(C)) return 0; 333226633Sdim 334202375Srdivacky // Otherwise, we know if the comparison is true or false for this element, 335202375Srdivacky // update our state machines. 336202375Srdivacky bool IsTrueForElt = !cast<ConstantInt>(C)->isZero(); 337226633Sdim 338202375Srdivacky // State machine for single/double/range index comparison. 339202375Srdivacky if (IsTrueForElt) { 340202375Srdivacky // Update the TrueElement state machine. 341202375Srdivacky if (FirstTrueElement == Undefined) 342202375Srdivacky FirstTrueElement = TrueRangeEnd = i; // First true element. 343202375Srdivacky else { 344202375Srdivacky // Update double-compare state machine. 345202375Srdivacky if (SecondTrueElement == Undefined) 346202375Srdivacky SecondTrueElement = i; 347202375Srdivacky else 348202375Srdivacky SecondTrueElement = Overdefined; 349226633Sdim 350202375Srdivacky // Update range state machine. 351202375Srdivacky if (TrueRangeEnd == (int)i-1) 352202375Srdivacky TrueRangeEnd = i; 353202375Srdivacky else 354202375Srdivacky TrueRangeEnd = Overdefined; 355202375Srdivacky } 356202375Srdivacky } else { 357202375Srdivacky // Update the FalseElement state machine. 358202375Srdivacky if (FirstFalseElement == Undefined) 359202375Srdivacky FirstFalseElement = FalseRangeEnd = i; // First false element. 360202375Srdivacky else { 361202375Srdivacky // Update double-compare state machine. 362202375Srdivacky if (SecondFalseElement == Undefined) 363202375Srdivacky SecondFalseElement = i; 364202375Srdivacky else 365202375Srdivacky SecondFalseElement = Overdefined; 366226633Sdim 367202375Srdivacky // Update range state machine. 368202375Srdivacky if (FalseRangeEnd == (int)i-1) 369202375Srdivacky FalseRangeEnd = i; 370202375Srdivacky else 371202375Srdivacky FalseRangeEnd = Overdefined; 372202375Srdivacky } 373202375Srdivacky } 374226633Sdim 375226633Sdim 376202375Srdivacky // If this element is in range, update our magic bitvector. 377202375Srdivacky if (i < 64 && IsTrueForElt) 378202375Srdivacky MagicBitvector |= 1ULL << i; 379226633Sdim 380202375Srdivacky // If all of our states become overdefined, bail out early. Since the 381202375Srdivacky // predicate is expensive, only check it every 8 elements. This is only 382202375Srdivacky // really useful for really huge arrays. 383202375Srdivacky if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined && 384202375Srdivacky SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined && 385202375Srdivacky FalseRangeEnd == Overdefined) 386202375Srdivacky return 0; 387202375Srdivacky } 388202375Srdivacky 389202375Srdivacky // Now that we've scanned the entire array, emit our new comparison(s). We 390202375Srdivacky // order the state machines in complexity of the generated code. 391202375Srdivacky Value *Idx = GEP->getOperand(2); 392202375Srdivacky 393202375Srdivacky // If the index is larger than the pointer size of the target, truncate the 394202375Srdivacky // index down like the GEP would do implicitly. We don't have to do this for 395202375Srdivacky // an inbounds GEP because the index can't be out of range. 396202375Srdivacky if (!GEP->isInBounds() && 397202375Srdivacky Idx->getType()->getPrimitiveSizeInBits() > TD->getPointerSizeInBits()) 398202375Srdivacky Idx = Builder->CreateTrunc(Idx, TD->getIntPtrType(Idx->getContext())); 399226633Sdim 400202375Srdivacky // If the comparison is only true for one or two elements, emit direct 401202375Srdivacky // comparisons. 402202375Srdivacky if (SecondTrueElement != Overdefined) { 403202375Srdivacky // None true -> false. 404202375Srdivacky if (FirstTrueElement == Undefined) 405202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(GEP->getContext())); 406226633Sdim 407202375Srdivacky Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement); 408226633Sdim 409202375Srdivacky // True for one element -> 'i == 47'. 410202375Srdivacky if (SecondTrueElement == Undefined) 411202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx); 412226633Sdim 413202375Srdivacky // True for two elements -> 'i == 47 | i == 72'. 414202375Srdivacky Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx); 415202375Srdivacky Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement); 416202375Srdivacky Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx); 417202375Srdivacky return BinaryOperator::CreateOr(C1, C2); 418202375Srdivacky } 419202375Srdivacky 420202375Srdivacky // If the comparison is only false for one or two elements, emit direct 421202375Srdivacky // comparisons. 422202375Srdivacky if (SecondFalseElement != Overdefined) { 423202375Srdivacky // None false -> true. 424202375Srdivacky if (FirstFalseElement == Undefined) 425202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(GEP->getContext())); 426226633Sdim 427202375Srdivacky Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement); 428202375Srdivacky 429202375Srdivacky // False for one element -> 'i != 47'. 430202375Srdivacky if (SecondFalseElement == Undefined) 431202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx); 432226633Sdim 433202375Srdivacky // False for two elements -> 'i != 47 & i != 72'. 434202375Srdivacky Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx); 435202375Srdivacky Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement); 436202375Srdivacky Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx); 437202375Srdivacky return BinaryOperator::CreateAnd(C1, C2); 438202375Srdivacky } 439226633Sdim 440202375Srdivacky // If the comparison can be replaced with a range comparison for the elements 441202375Srdivacky // where it is true, emit the range check. 442202375Srdivacky if (TrueRangeEnd != Overdefined) { 443202375Srdivacky assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare"); 444226633Sdim 445202375Srdivacky // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1). 446202375Srdivacky if (FirstTrueElement) { 447202375Srdivacky Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement); 448202375Srdivacky Idx = Builder->CreateAdd(Idx, Offs); 449202375Srdivacky } 450226633Sdim 451202375Srdivacky Value *End = ConstantInt::get(Idx->getType(), 452202375Srdivacky TrueRangeEnd-FirstTrueElement+1); 453202375Srdivacky return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End); 454202375Srdivacky } 455226633Sdim 456202375Srdivacky // False range check. 457202375Srdivacky if (FalseRangeEnd != Overdefined) { 458202375Srdivacky assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare"); 459202375Srdivacky // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse). 460202375Srdivacky if (FirstFalseElement) { 461202375Srdivacky Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement); 462202375Srdivacky Idx = Builder->CreateAdd(Idx, Offs); 463202375Srdivacky } 464226633Sdim 465202375Srdivacky Value *End = ConstantInt::get(Idx->getType(), 466202375Srdivacky FalseRangeEnd-FirstFalseElement); 467202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End); 468202375Srdivacky } 469226633Sdim 470226633Sdim 471249423Sdim // If a magic bitvector captures the entire comparison state 472202375Srdivacky // of this load, replace it with computation that does: 473202375Srdivacky // ((magic_cst >> i) & 1) != 0 474249423Sdim { 475249423Sdim Type *Ty = 0; 476249423Sdim 477249423Sdim // Look for an appropriate type: 478249423Sdim // - The type of Idx if the magic fits 479249423Sdim // - The smallest fitting legal type if we have a DataLayout 480249423Sdim // - Default to i32 481249423Sdim if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth()) 482249423Sdim Ty = Idx->getType(); 483249423Sdim else if (TD) 484249423Sdim Ty = TD->getSmallestLegalIntType(Init->getContext(), ArrayElementCount); 485249423Sdim else if (ArrayElementCount <= 32) 486202375Srdivacky Ty = Type::getInt32Ty(Init->getContext()); 487249423Sdim 488249423Sdim if (Ty != 0) { 489249423Sdim Value *V = Builder->CreateIntCast(Idx, Ty, false); 490249423Sdim V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V); 491249423Sdim V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V); 492249423Sdim return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0)); 493249423Sdim } 494202375Srdivacky } 495226633Sdim 496202375Srdivacky return 0; 497202375Srdivacky} 498202375Srdivacky 499202375Srdivacky 500202375Srdivacky/// EvaluateGEPOffsetExpression - Return a value that can be used to compare 501202375Srdivacky/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we 502202375Srdivacky/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can 503202375Srdivacky/// be complex, and scales are involved. The above expression would also be 504202375Srdivacky/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32). 505202375Srdivacky/// This later form is less amenable to optimization though, and we are allowed 506202375Srdivacky/// to generate the first by knowing that pointer arithmetic doesn't overflow. 507202375Srdivacky/// 508202375Srdivacky/// If we can't emit an optimized form for this expression, this returns null. 509226633Sdim/// 510223017Sdimstatic Value *EvaluateGEPOffsetExpression(User *GEP, InstCombiner &IC) { 511243830Sdim DataLayout &TD = *IC.getDataLayout(); 512202375Srdivacky gep_type_iterator GTI = gep_type_begin(GEP); 513226633Sdim 514202375Srdivacky // Check to see if this gep only has a single variable index. If so, and if 515202375Srdivacky // any constant indices are a multiple of its scale, then we can compute this 516202375Srdivacky // in terms of the scale of the variable index. For example, if the GEP 517202375Srdivacky // implies an offset of "12 + i*4", then we can codegen this as "3 + i", 518202375Srdivacky // because the expression will cross zero at the same point. 519202375Srdivacky unsigned i, e = GEP->getNumOperands(); 520202375Srdivacky int64_t Offset = 0; 521202375Srdivacky for (i = 1; i != e; ++i, ++GTI) { 522202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) { 523202375Srdivacky // Compute the aggregate offset of constant indices. 524202375Srdivacky if (CI->isZero()) continue; 525226633Sdim 526202375Srdivacky // Handle a struct index, which adds its field offset to the pointer. 527226633Sdim if (StructType *STy = dyn_cast<StructType>(*GTI)) { 528202375Srdivacky Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); 529202375Srdivacky } else { 530202375Srdivacky uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 531202375Srdivacky Offset += Size*CI->getSExtValue(); 532202375Srdivacky } 533202375Srdivacky } else { 534202375Srdivacky // Found our variable index. 535202375Srdivacky break; 536202375Srdivacky } 537202375Srdivacky } 538226633Sdim 539202375Srdivacky // If there are no variable indices, we must have a constant offset, just 540202375Srdivacky // evaluate it the general way. 541202375Srdivacky if (i == e) return 0; 542226633Sdim 543202375Srdivacky Value *VariableIdx = GEP->getOperand(i); 544202375Srdivacky // Determine the scale factor of the variable element. For example, this is 545202375Srdivacky // 4 if the variable index is into an array of i32. 546202375Srdivacky uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType()); 547226633Sdim 548202375Srdivacky // Verify that there are no other variable indices. If so, emit the hard way. 549202375Srdivacky for (++i, ++GTI; i != e; ++i, ++GTI) { 550202375Srdivacky ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i)); 551202375Srdivacky if (!CI) return 0; 552226633Sdim 553202375Srdivacky // Compute the aggregate offset of constant indices. 554202375Srdivacky if (CI->isZero()) continue; 555226633Sdim 556202375Srdivacky // Handle a struct index, which adds its field offset to the pointer. 557226633Sdim if (StructType *STy = dyn_cast<StructType>(*GTI)) { 558202375Srdivacky Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); 559202375Srdivacky } else { 560202375Srdivacky uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 561202375Srdivacky Offset += Size*CI->getSExtValue(); 562202375Srdivacky } 563202375Srdivacky } 564226633Sdim 565202375Srdivacky // Okay, we know we have a single variable index, which must be a 566202375Srdivacky // pointer/array/vector index. If there is no offset, life is simple, return 567202375Srdivacky // the index. 568202375Srdivacky unsigned IntPtrWidth = TD.getPointerSizeInBits(); 569202375Srdivacky if (Offset == 0) { 570202375Srdivacky // Cast to intptrty in case a truncation occurs. If an extension is needed, 571202375Srdivacky // we don't need to bother extending: the extension won't affect where the 572202375Srdivacky // computation crosses zero. 573223017Sdim if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) { 574226633Sdim Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext()); 575223017Sdim VariableIdx = IC.Builder->CreateTrunc(VariableIdx, IntPtrTy); 576223017Sdim } 577202375Srdivacky return VariableIdx; 578202375Srdivacky } 579226633Sdim 580202375Srdivacky // Otherwise, there is an index. The computation we will do will be modulo 581202375Srdivacky // the pointer size, so get it. 582202375Srdivacky uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth); 583226633Sdim 584202375Srdivacky Offset &= PtrSizeMask; 585202375Srdivacky VariableScale &= PtrSizeMask; 586226633Sdim 587202375Srdivacky // To do this transformation, any constant index must be a multiple of the 588202375Srdivacky // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i", 589202375Srdivacky // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a 590202375Srdivacky // multiple of the variable scale. 591202375Srdivacky int64_t NewOffs = Offset / (int64_t)VariableScale; 592202375Srdivacky if (Offset != NewOffs*(int64_t)VariableScale) 593202375Srdivacky return 0; 594226633Sdim 595202375Srdivacky // Okay, we can do this evaluation. Start by converting the index to intptr. 596226633Sdim Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext()); 597202375Srdivacky if (VariableIdx->getType() != IntPtrTy) 598223017Sdim VariableIdx = IC.Builder->CreateIntCast(VariableIdx, IntPtrTy, 599223017Sdim true /*Signed*/); 600202375Srdivacky Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs); 601223017Sdim return IC.Builder->CreateAdd(VariableIdx, OffsetVal, "offset"); 602202375Srdivacky} 603202375Srdivacky 604202375Srdivacky/// FoldGEPICmp - Fold comparisons between a GEP instruction and something 605202375Srdivacky/// else. At this point we know that the GEP is on the LHS of the comparison. 606202375SrdivackyInstruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, 607202375Srdivacky ICmpInst::Predicate Cond, 608202375Srdivacky Instruction &I) { 609234353Sdim // Don't transform signed compares of GEPs into index compares. Even if the 610234353Sdim // GEP is inbounds, the final add of the base pointer can have signed overflow 611234353Sdim // and would change the result of the icmp. 612234353Sdim // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be 613234353Sdim // the maximum signed value for the pointer type. 614234353Sdim if (ICmpInst::isSigned(Cond)) 615234353Sdim return 0; 616234353Sdim 617202375Srdivacky // Look through bitcasts. 618202375Srdivacky if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS)) 619202375Srdivacky RHS = BCI->getOperand(0); 620202375Srdivacky 621202375Srdivacky Value *PtrBase = GEPLHS->getOperand(0); 622202375Srdivacky if (TD && PtrBase == RHS && GEPLHS->isInBounds()) { 623202375Srdivacky // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0). 624202375Srdivacky // This transformation (ignoring the base and scales) is valid because we 625202375Srdivacky // know pointers can't overflow since the gep is inbounds. See if we can 626202375Srdivacky // output an optimized form. 627223017Sdim Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, *this); 628226633Sdim 629202375Srdivacky // If not, synthesize the offset the hard way. 630202375Srdivacky if (Offset == 0) 631202375Srdivacky Offset = EmitGEPOffset(GEPLHS); 632202375Srdivacky return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset, 633202375Srdivacky Constant::getNullValue(Offset->getType())); 634202375Srdivacky } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) { 635202375Srdivacky // If the base pointers are different, but the indices are the same, just 636202375Srdivacky // compare the base pointer. 637202375Srdivacky if (PtrBase != GEPRHS->getOperand(0)) { 638202375Srdivacky bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands(); 639202375Srdivacky IndicesTheSame &= GEPLHS->getOperand(0)->getType() == 640202375Srdivacky GEPRHS->getOperand(0)->getType(); 641202375Srdivacky if (IndicesTheSame) 642202375Srdivacky for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) 643202375Srdivacky if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { 644202375Srdivacky IndicesTheSame = false; 645202375Srdivacky break; 646202375Srdivacky } 647202375Srdivacky 648202375Srdivacky // If all indices are the same, just compare the base pointers. 649202375Srdivacky if (IndicesTheSame) 650202375Srdivacky return new ICmpInst(ICmpInst::getSignedPredicate(Cond), 651202375Srdivacky GEPLHS->getOperand(0), GEPRHS->getOperand(0)); 652202375Srdivacky 653234353Sdim // If we're comparing GEPs with two base pointers that only differ in type 654234353Sdim // and both GEPs have only constant indices or just one use, then fold 655234353Sdim // the compare with the adjusted indices. 656234353Sdim if (TD && GEPLHS->isInBounds() && GEPRHS->isInBounds() && 657234353Sdim (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) && 658234353Sdim (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) && 659234353Sdim PtrBase->stripPointerCasts() == 660234353Sdim GEPRHS->getOperand(0)->stripPointerCasts()) { 661234353Sdim Value *Cmp = Builder->CreateICmp(ICmpInst::getSignedPredicate(Cond), 662234353Sdim EmitGEPOffset(GEPLHS), 663234353Sdim EmitGEPOffset(GEPRHS)); 664234353Sdim return ReplaceInstUsesWith(I, Cmp); 665234353Sdim } 666234353Sdim 667202375Srdivacky // Otherwise, the base pointers are different and the indices are 668202375Srdivacky // different, bail out. 669202375Srdivacky return 0; 670202375Srdivacky } 671202375Srdivacky 672202375Srdivacky // If one of the GEPs has all zero indices, recurse. 673202375Srdivacky bool AllZeros = true; 674202375Srdivacky for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) 675202375Srdivacky if (!isa<Constant>(GEPLHS->getOperand(i)) || 676202375Srdivacky !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) { 677202375Srdivacky AllZeros = false; 678202375Srdivacky break; 679202375Srdivacky } 680202375Srdivacky if (AllZeros) 681202375Srdivacky return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0), 682202375Srdivacky ICmpInst::getSwappedPredicate(Cond), I); 683202375Srdivacky 684202375Srdivacky // If the other GEP has all zero indices, recurse. 685202375Srdivacky AllZeros = true; 686202375Srdivacky for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) 687202375Srdivacky if (!isa<Constant>(GEPRHS->getOperand(i)) || 688202375Srdivacky !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) { 689202375Srdivacky AllZeros = false; 690202375Srdivacky break; 691202375Srdivacky } 692202375Srdivacky if (AllZeros) 693202375Srdivacky return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I); 694202375Srdivacky 695223017Sdim bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds(); 696202375Srdivacky if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { 697202375Srdivacky // If the GEPs only differ by one index, compare it. 698202375Srdivacky unsigned NumDifferences = 0; // Keep track of # differences. 699202375Srdivacky unsigned DiffOperand = 0; // The operand that differs. 700202375Srdivacky for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) 701202375Srdivacky if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { 702202375Srdivacky if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() != 703202375Srdivacky GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) { 704202375Srdivacky // Irreconcilable differences. 705202375Srdivacky NumDifferences = 2; 706202375Srdivacky break; 707202375Srdivacky } else { 708202375Srdivacky if (NumDifferences++) break; 709202375Srdivacky DiffOperand = i; 710202375Srdivacky } 711202375Srdivacky } 712202375Srdivacky 713202375Srdivacky if (NumDifferences == 0) // SAME GEP? 714202375Srdivacky return ReplaceInstUsesWith(I, // No comparison is needed here. 715202375Srdivacky ConstantInt::get(Type::getInt1Ty(I.getContext()), 716202375Srdivacky ICmpInst::isTrueWhenEqual(Cond))); 717202375Srdivacky 718223017Sdim else if (NumDifferences == 1 && GEPsInBounds) { 719202375Srdivacky Value *LHSV = GEPLHS->getOperand(DiffOperand); 720202375Srdivacky Value *RHSV = GEPRHS->getOperand(DiffOperand); 721202375Srdivacky // Make sure we do a signed comparison here. 722202375Srdivacky return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV); 723202375Srdivacky } 724202375Srdivacky } 725202375Srdivacky 726202375Srdivacky // Only lower this if the icmp is the only user of the GEP or if we expect 727202375Srdivacky // the result to fold to a constant! 728202375Srdivacky if (TD && 729223017Sdim GEPsInBounds && 730202375Srdivacky (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) && 731202375Srdivacky (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) { 732202375Srdivacky // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) 733202375Srdivacky Value *L = EmitGEPOffset(GEPLHS); 734202375Srdivacky Value *R = EmitGEPOffset(GEPRHS); 735202375Srdivacky return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R); 736202375Srdivacky } 737202375Srdivacky } 738202375Srdivacky return 0; 739202375Srdivacky} 740202375Srdivacky 741202375Srdivacky/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X". 742202375SrdivackyInstruction *InstCombiner::FoldICmpAddOpCst(ICmpInst &ICI, 743202375Srdivacky Value *X, ConstantInt *CI, 744202375Srdivacky ICmpInst::Predicate Pred, 745202375Srdivacky Value *TheAdd) { 746202375Srdivacky // If we have X+0, exit early (simplifying logic below) and let it get folded 747202375Srdivacky // elsewhere. icmp X+0, X -> icmp X, X 748202375Srdivacky if (CI->isZero()) { 749202375Srdivacky bool isTrue = ICmpInst::isTrueWhenEqual(Pred); 750202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue)); 751202375Srdivacky } 752226633Sdim 753202375Srdivacky // (X+4) == X -> false. 754202375Srdivacky if (Pred == ICmpInst::ICMP_EQ) 755202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext())); 756202375Srdivacky 757202375Srdivacky // (X+4) != X -> true. 758202375Srdivacky if (Pred == ICmpInst::ICMP_NE) 759202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext())); 760202375Srdivacky 761202375Srdivacky // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0, 762221345Sdim // so the values can never be equal. Similarly for all other "or equals" 763202375Srdivacky // operators. 764226633Sdim 765202375Srdivacky // (X+1) <u X --> X >u (MAXUINT-1) --> X == 255 766202375Srdivacky // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253 767202375Srdivacky // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0 768202375Srdivacky if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { 769226633Sdim Value *R = 770202375Srdivacky ConstantExpr::getSub(ConstantInt::getAllOnesValue(CI->getType()), CI); 771202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGT, X, R); 772202375Srdivacky } 773226633Sdim 774202375Srdivacky // (X+1) >u X --> X <u (0-1) --> X != 255 775202375Srdivacky // (X+2) >u X --> X <u (0-2) --> X <u 254 776202375Srdivacky // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0 777218893Sdim if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) 778202375Srdivacky return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI)); 779226633Sdim 780202375Srdivacky unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits(); 781202375Srdivacky ConstantInt *SMax = ConstantInt::get(X->getContext(), 782202375Srdivacky APInt::getSignedMaxValue(BitWidth)); 783202375Srdivacky 784202375Srdivacky // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127 785202375Srdivacky // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125 786202375Srdivacky // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0 787202375Srdivacky // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1 788202375Srdivacky // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126 789202375Srdivacky // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127 790218893Sdim if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) 791202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI)); 792226633Sdim 793202375Srdivacky // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127 794202375Srdivacky // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126 795202375Srdivacky // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1 796202375Srdivacky // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2 797202375Srdivacky // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126 798202375Srdivacky // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128 799226633Sdim 800202375Srdivacky assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE); 801202375Srdivacky Constant *C = ConstantInt::get(X->getContext(), CI->getValue()-1); 802202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C)); 803202375Srdivacky} 804202375Srdivacky 805202375Srdivacky/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS 806202375Srdivacky/// and CmpRHS are both known to be integer constants. 807202375SrdivackyInstruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, 808202375Srdivacky ConstantInt *DivRHS) { 809202375Srdivacky ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1)); 810202375Srdivacky const APInt &CmpRHSV = CmpRHS->getValue(); 811226633Sdim 812226633Sdim // FIXME: If the operand types don't match the type of the divide 813202375Srdivacky // then don't attempt this transform. The code below doesn't have the 814202375Srdivacky // logic to deal with a signed divide and an unsigned compare (and 815226633Sdim // vice versa). This is because (x /s C1) <s C2 produces different 816202375Srdivacky // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even 817226633Sdim // (x /u C1) <u C2. Simply casting the operands and result won't 818226633Sdim // work. :( The if statement below tests that condition and bails 819218893Sdim // if it finds it. 820202375Srdivacky bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv; 821202375Srdivacky if (!ICI.isEquality() && DivIsSigned != ICI.isSigned()) 822202375Srdivacky return 0; 823202375Srdivacky if (DivRHS->isZero()) 824202375Srdivacky return 0; // The ProdOV computation fails on divide by zero. 825202375Srdivacky if (DivIsSigned && DivRHS->isAllOnesValue()) 826202375Srdivacky return 0; // The overflow computation also screws up here 827218893Sdim if (DivRHS->isOne()) { 828218893Sdim // This eliminates some funny cases with INT_MIN. 829218893Sdim ICI.setOperand(0, DivI->getOperand(0)); // X/1 == X. 830218893Sdim return &ICI; 831218893Sdim } 832202375Srdivacky 833202375Srdivacky // Compute Prod = CI * DivRHS. We are essentially solving an equation 834226633Sdim // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and 835226633Sdim // C2 (CI). By solving for X we can turn this into a range check 836226633Sdim // instead of computing a divide. 837202375Srdivacky Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS); 838202375Srdivacky 839202375Srdivacky // Determine if the product overflows by seeing if the product is 840202375Srdivacky // not equal to the divide. Make sure we do the same kind of divide 841226633Sdim // as in the LHS instruction that we're folding. 842202375Srdivacky bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) : 843202375Srdivacky ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS; 844202375Srdivacky 845202375Srdivacky // Get the ICmp opcode 846202375Srdivacky ICmpInst::Predicate Pred = ICI.getPredicate(); 847202375Srdivacky 848218893Sdim /// If the division is known to be exact, then there is no remainder from the 849218893Sdim /// divide, so the covered range size is unit, otherwise it is the divisor. 850218893Sdim ConstantInt *RangeSize = DivI->isExact() ? getOne(Prod) : DivRHS; 851226633Sdim 852202375Srdivacky // Figure out the interval that is being checked. For example, a comparison 853226633Sdim // like "X /u 5 == 0" is really checking that X is in the interval [0, 5). 854202375Srdivacky // Compute this interval based on the constants involved and the signedness of 855202375Srdivacky // the compare/divide. This computes a half-open interval, keeping track of 856202375Srdivacky // whether either value in the interval overflows. After analysis each 857202375Srdivacky // overflow variable is set to 0 if it's corresponding bound variable is valid 858202375Srdivacky // -1 if overflowed off the bottom end, or +1 if overflowed off the top end. 859202375Srdivacky int LoOverflow = 0, HiOverflow = 0; 860202375Srdivacky Constant *LoBound = 0, *HiBound = 0; 861218893Sdim 862202375Srdivacky if (!DivIsSigned) { // udiv 863202375Srdivacky // e.g. X/5 op 3 --> [15, 20) 864202375Srdivacky LoBound = Prod; 865202375Srdivacky HiOverflow = LoOverflow = ProdOV; 866218893Sdim if (!HiOverflow) { 867218893Sdim // If this is not an exact divide, then many values in the range collapse 868218893Sdim // to the same result value. 869218893Sdim HiOverflow = AddWithOverflow(HiBound, LoBound, RangeSize, false); 870218893Sdim } 871226633Sdim 872202375Srdivacky } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0. 873202375Srdivacky if (CmpRHSV == 0) { // (X / pos) op 0 874202375Srdivacky // Can't overflow. e.g. X/2 op 0 --> [-1, 2) 875218893Sdim LoBound = ConstantExpr::getNeg(SubOne(RangeSize)); 876218893Sdim HiBound = RangeSize; 877202375Srdivacky } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos 878202375Srdivacky LoBound = Prod; // e.g. X/5 op 3 --> [15, 20) 879202375Srdivacky HiOverflow = LoOverflow = ProdOV; 880202375Srdivacky if (!HiOverflow) 881218893Sdim HiOverflow = AddWithOverflow(HiBound, Prod, RangeSize, true); 882202375Srdivacky } else { // (X / pos) op neg 883202375Srdivacky // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14) 884202375Srdivacky HiBound = AddOne(Prod); 885202375Srdivacky LoOverflow = HiOverflow = ProdOV ? -1 : 0; 886202375Srdivacky if (!LoOverflow) { 887218893Sdim ConstantInt *DivNeg =cast<ConstantInt>(ConstantExpr::getNeg(RangeSize)); 888202375Srdivacky LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0; 889218893Sdim } 890202375Srdivacky } 891224145Sdim } else if (DivRHS->isNegative()) { // Divisor is < 0. 892218893Sdim if (DivI->isExact()) 893218893Sdim RangeSize = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize)); 894202375Srdivacky if (CmpRHSV == 0) { // (X / neg) op 0 895202375Srdivacky // e.g. X/-5 op 0 --> [-4, 5) 896218893Sdim LoBound = AddOne(RangeSize); 897218893Sdim HiBound = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize)); 898202375Srdivacky if (HiBound == DivRHS) { // -INTMIN = INTMIN 899202375Srdivacky HiOverflow = 1; // [INTMIN+1, overflow) 900202375Srdivacky HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN 901202375Srdivacky } 902202375Srdivacky } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos 903202375Srdivacky // e.g. X/-5 op 3 --> [-19, -14) 904202375Srdivacky HiBound = AddOne(Prod); 905202375Srdivacky HiOverflow = LoOverflow = ProdOV ? -1 : 0; 906202375Srdivacky if (!LoOverflow) 907218893Sdim LoOverflow = AddWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0; 908202375Srdivacky } else { // (X / neg) op neg 909202375Srdivacky LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20) 910202375Srdivacky LoOverflow = HiOverflow = ProdOV; 911202375Srdivacky if (!HiOverflow) 912218893Sdim HiOverflow = SubWithOverflow(HiBound, Prod, RangeSize, true); 913202375Srdivacky } 914226633Sdim 915202375Srdivacky // Dividing by a negative swaps the condition. LT <-> GT 916202375Srdivacky Pred = ICmpInst::getSwappedPredicate(Pred); 917202375Srdivacky } 918202375Srdivacky 919202375Srdivacky Value *X = DivI->getOperand(0); 920202375Srdivacky switch (Pred) { 921202375Srdivacky default: llvm_unreachable("Unhandled icmp opcode!"); 922202375Srdivacky case ICmpInst::ICMP_EQ: 923202375Srdivacky if (LoOverflow && HiOverflow) 924202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); 925204792Srdivacky if (HiOverflow) 926202375Srdivacky return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : 927202375Srdivacky ICmpInst::ICMP_UGE, X, LoBound); 928204792Srdivacky if (LoOverflow) 929202375Srdivacky return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : 930202375Srdivacky ICmpInst::ICMP_ULT, X, HiBound); 931218893Sdim return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound, 932218893Sdim DivIsSigned, true)); 933202375Srdivacky case ICmpInst::ICMP_NE: 934202375Srdivacky if (LoOverflow && HiOverflow) 935202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); 936204792Srdivacky if (HiOverflow) 937202375Srdivacky return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : 938202375Srdivacky ICmpInst::ICMP_ULT, X, LoBound); 939204792Srdivacky if (LoOverflow) 940202375Srdivacky return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : 941202375Srdivacky ICmpInst::ICMP_UGE, X, HiBound); 942204792Srdivacky return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound, 943204792Srdivacky DivIsSigned, false)); 944202375Srdivacky case ICmpInst::ICMP_ULT: 945202375Srdivacky case ICmpInst::ICMP_SLT: 946202375Srdivacky if (LoOverflow == +1) // Low bound is greater than input range. 947202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); 948202375Srdivacky if (LoOverflow == -1) // Low bound is less than input range. 949202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); 950202375Srdivacky return new ICmpInst(Pred, X, LoBound); 951202375Srdivacky case ICmpInst::ICMP_UGT: 952202375Srdivacky case ICmpInst::ICMP_SGT: 953202375Srdivacky if (HiOverflow == +1) // High bound greater than input range. 954202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); 955218893Sdim if (HiOverflow == -1) // High bound less than input range. 956202375Srdivacky return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); 957202375Srdivacky if (Pred == ICmpInst::ICMP_UGT) 958202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound); 959218893Sdim return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound); 960202375Srdivacky } 961202375Srdivacky} 962202375Srdivacky 963218893Sdim/// FoldICmpShrCst - Handle "icmp(([al]shr X, cst1), cst2)". 964218893SdimInstruction *InstCombiner::FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *Shr, 965218893Sdim ConstantInt *ShAmt) { 966218893Sdim const APInt &CmpRHSV = cast<ConstantInt>(ICI.getOperand(1))->getValue(); 967226633Sdim 968218893Sdim // Check that the shift amount is in range. If not, don't perform 969218893Sdim // undefined shifts. When the shift is visited it will be 970218893Sdim // simplified. 971218893Sdim uint32_t TypeBits = CmpRHSV.getBitWidth(); 972218893Sdim uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); 973218893Sdim if (ShAmtVal >= TypeBits || ShAmtVal == 0) 974218893Sdim return 0; 975226633Sdim 976218893Sdim if (!ICI.isEquality()) { 977218893Sdim // If we have an unsigned comparison and an ashr, we can't simplify this. 978218893Sdim // Similarly for signed comparisons with lshr. 979218893Sdim if (ICI.isSigned() != (Shr->getOpcode() == Instruction::AShr)) 980218893Sdim return 0; 981226633Sdim 982223017Sdim // Otherwise, all lshr and most exact ashr's are equivalent to a udiv/sdiv 983223017Sdim // by a power of 2. Since we already have logic to simplify these, 984223017Sdim // transform to div and then simplify the resultant comparison. 985218893Sdim if (Shr->getOpcode() == Instruction::AShr && 986223017Sdim (!Shr->isExact() || ShAmtVal == TypeBits - 1)) 987218893Sdim return 0; 988226633Sdim 989218893Sdim // Revisit the shift (to delete it). 990218893Sdim Worklist.Add(Shr); 991226633Sdim 992218893Sdim Constant *DivCst = 993218893Sdim ConstantInt::get(Shr->getType(), APInt::getOneBitSet(TypeBits, ShAmtVal)); 994226633Sdim 995218893Sdim Value *Tmp = 996218893Sdim Shr->getOpcode() == Instruction::AShr ? 997218893Sdim Builder->CreateSDiv(Shr->getOperand(0), DivCst, "", Shr->isExact()) : 998218893Sdim Builder->CreateUDiv(Shr->getOperand(0), DivCst, "", Shr->isExact()); 999226633Sdim 1000218893Sdim ICI.setOperand(0, Tmp); 1001226633Sdim 1002218893Sdim // If the builder folded the binop, just return it. 1003218893Sdim BinaryOperator *TheDiv = dyn_cast<BinaryOperator>(Tmp); 1004218893Sdim if (TheDiv == 0) 1005218893Sdim return &ICI; 1006226633Sdim 1007218893Sdim // Otherwise, fold this div/compare. 1008218893Sdim assert(TheDiv->getOpcode() == Instruction::SDiv || 1009218893Sdim TheDiv->getOpcode() == Instruction::UDiv); 1010226633Sdim 1011218893Sdim Instruction *Res = FoldICmpDivCst(ICI, TheDiv, cast<ConstantInt>(DivCst)); 1012218893Sdim assert(Res && "This div/cst should have folded!"); 1013218893Sdim return Res; 1014218893Sdim } 1015226633Sdim 1016226633Sdim 1017218893Sdim // If we are comparing against bits always shifted out, the 1018218893Sdim // comparison cannot succeed. 1019218893Sdim APInt Comp = CmpRHSV << ShAmtVal; 1020218893Sdim ConstantInt *ShiftedCmpRHS = ConstantInt::get(ICI.getContext(), Comp); 1021218893Sdim if (Shr->getOpcode() == Instruction::LShr) 1022218893Sdim Comp = Comp.lshr(ShAmtVal); 1023218893Sdim else 1024218893Sdim Comp = Comp.ashr(ShAmtVal); 1025226633Sdim 1026218893Sdim if (Comp != CmpRHSV) { // Comparing against a bit that we know is zero. 1027218893Sdim bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; 1028218893Sdim Constant *Cst = ConstantInt::get(Type::getInt1Ty(ICI.getContext()), 1029218893Sdim IsICMP_NE); 1030218893Sdim return ReplaceInstUsesWith(ICI, Cst); 1031218893Sdim } 1032226633Sdim 1033218893Sdim // Otherwise, check to see if the bits shifted out are known to be zero. 1034218893Sdim // If so, we can compare against the unshifted value: 1035218893Sdim // (X & 4) >> 1 == 2 --> (X & 4) == 4. 1036218893Sdim if (Shr->hasOneUse() && Shr->isExact()) 1037218893Sdim return new ICmpInst(ICI.getPredicate(), Shr->getOperand(0), ShiftedCmpRHS); 1038226633Sdim 1039218893Sdim if (Shr->hasOneUse()) { 1040218893Sdim // Otherwise strength reduce the shift into an and. 1041218893Sdim APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); 1042218893Sdim Constant *Mask = ConstantInt::get(ICI.getContext(), Val); 1043226633Sdim 1044218893Sdim Value *And = Builder->CreateAnd(Shr->getOperand(0), 1045218893Sdim Mask, Shr->getName()+".mask"); 1046218893Sdim return new ICmpInst(ICI.getPredicate(), And, ShiftedCmpRHS); 1047218893Sdim } 1048218893Sdim return 0; 1049218893Sdim} 1050202375Srdivacky 1051218893Sdim 1052202375Srdivacky/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)". 1053202375Srdivacky/// 1054202375SrdivackyInstruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, 1055202375Srdivacky Instruction *LHSI, 1056202375Srdivacky ConstantInt *RHS) { 1057202375Srdivacky const APInt &RHSV = RHS->getValue(); 1058226633Sdim 1059202375Srdivacky switch (LHSI->getOpcode()) { 1060202375Srdivacky case Instruction::Trunc: 1061202375Srdivacky if (ICI.isEquality() && LHSI->hasOneUse()) { 1062202375Srdivacky // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all 1063202375Srdivacky // of the high bits truncated out of x are known. 1064202375Srdivacky unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(), 1065202375Srdivacky SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits(); 1066202375Srdivacky APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0); 1067234353Sdim ComputeMaskedBits(LHSI->getOperand(0), KnownZero, KnownOne); 1068226633Sdim 1069202375Srdivacky // If all the high bits are known, we can do this xform. 1070202375Srdivacky if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) { 1071202375Srdivacky // Pull in the high bits from known-ones set. 1072218893Sdim APInt NewRHS = RHS->getValue().zext(SrcBits); 1073239462Sdim NewRHS |= KnownOne & APInt::getHighBitsSet(SrcBits, SrcBits-DstBits); 1074202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), 1075202375Srdivacky ConstantInt::get(ICI.getContext(), NewRHS)); 1076202375Srdivacky } 1077202375Srdivacky } 1078202375Srdivacky break; 1079226633Sdim 1080202375Srdivacky case Instruction::Xor: // (icmp pred (xor X, XorCST), CI) 1081202375Srdivacky if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { 1082202375Srdivacky // If this is a comparison that tests the signbit (X < 0) or (x > -1), 1083202375Srdivacky // fold the xor. 1084202375Srdivacky if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) || 1085202375Srdivacky (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) { 1086202375Srdivacky Value *CompareVal = LHSI->getOperand(0); 1087226633Sdim 1088202375Srdivacky // If the sign bit of the XorCST is not set, there is no change to 1089202375Srdivacky // the operation, just stop using the Xor. 1090224145Sdim if (!XorCST->isNegative()) { 1091202375Srdivacky ICI.setOperand(0, CompareVal); 1092202375Srdivacky Worklist.Add(LHSI); 1093202375Srdivacky return &ICI; 1094202375Srdivacky } 1095226633Sdim 1096202375Srdivacky // Was the old condition true if the operand is positive? 1097202375Srdivacky bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT; 1098226633Sdim 1099202375Srdivacky // If so, the new one isn't. 1100202375Srdivacky isTrueIfPositive ^= true; 1101226633Sdim 1102202375Srdivacky if (isTrueIfPositive) 1103202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, 1104202375Srdivacky SubOne(RHS)); 1105202375Srdivacky else 1106202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, 1107202375Srdivacky AddOne(RHS)); 1108202375Srdivacky } 1109202375Srdivacky 1110202375Srdivacky if (LHSI->hasOneUse()) { 1111202375Srdivacky // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit)) 1112202375Srdivacky if (!ICI.isEquality() && XorCST->getValue().isSignBit()) { 1113202375Srdivacky const APInt &SignBit = XorCST->getValue(); 1114202375Srdivacky ICmpInst::Predicate Pred = ICI.isSigned() 1115202375Srdivacky ? ICI.getUnsignedPredicate() 1116202375Srdivacky : ICI.getSignedPredicate(); 1117202375Srdivacky return new ICmpInst(Pred, LHSI->getOperand(0), 1118202375Srdivacky ConstantInt::get(ICI.getContext(), 1119202375Srdivacky 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), 1130202375Srdivacky ConstantInt::get(ICI.getContext(), 1131202375Srdivacky RHSV ^ NotSignBit)); 1132202375Srdivacky } 1133202375Srdivacky } 1134202375Srdivacky } 1135202375Srdivacky break; 1136202375Srdivacky case Instruction::And: // (icmp pred (and X, AndCST), RHS) 1137202375Srdivacky if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) && 1138202375Srdivacky LHSI->getOperand(0)->hasOneUse()) { 1139202375Srdivacky ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1)); 1140226633Sdim 1141202375Srdivacky // If the LHS is an AND of a truncating cast, we can widen the 1142202375Srdivacky // and/compare to be the input width without changing the value 1143202375Srdivacky // produced, eliminating a cast. 1144202375Srdivacky if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) { 1145202375Srdivacky // We can do this transformation if either the AND constant does not 1146226633Sdim // have its sign bit set or if it is an equality comparison. 1147202375Srdivacky // Extending a relational comparison when we're checking the sign 1148202375Srdivacky // bit would not work. 1149224145Sdim if (ICI.isEquality() || 1150224145Sdim (!AndCST->isNegative() && RHSV.isNonNegative())) { 1151224145Sdim Value *NewAnd = 1152202375Srdivacky Builder->CreateAnd(Cast->getOperand(0), 1153224145Sdim ConstantExpr::getZExt(AndCST, Cast->getSrcTy())); 1154224145Sdim NewAnd->takeName(LHSI); 1155202375Srdivacky return new ICmpInst(ICI.getPredicate(), NewAnd, 1156224145Sdim ConstantExpr::getZExt(RHS, Cast->getSrcTy())); 1157202375Srdivacky } 1158202375Srdivacky } 1159224145Sdim 1160224145Sdim // If the LHS is an AND of a zext, and we have an equality compare, we can 1161224145Sdim // shrink the and/compare to the smaller type, eliminating the cast. 1162224145Sdim if (ZExtInst *Cast = dyn_cast<ZExtInst>(LHSI->getOperand(0))) { 1163226633Sdim IntegerType *Ty = cast<IntegerType>(Cast->getSrcTy()); 1164224145Sdim // Make sure we don't compare the upper bits, SimplifyDemandedBits 1165224145Sdim // should fold the icmp to true/false in that case. 1166224145Sdim if (ICI.isEquality() && RHSV.getActiveBits() <= Ty->getBitWidth()) { 1167224145Sdim Value *NewAnd = 1168224145Sdim Builder->CreateAnd(Cast->getOperand(0), 1169224145Sdim ConstantExpr::getTrunc(AndCST, Ty)); 1170224145Sdim NewAnd->takeName(LHSI); 1171224145Sdim return new ICmpInst(ICI.getPredicate(), NewAnd, 1172224145Sdim ConstantExpr::getTrunc(RHS, Ty)); 1173224145Sdim } 1174224145Sdim } 1175224145Sdim 1176202375Srdivacky // If this is: (X >> C1) & C2 != C3 (where any shift and any compare 1177202375Srdivacky // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This 1178202375Srdivacky // happens a LOT in code produced by the C front-end, for bitfield 1179202375Srdivacky // access. 1180202375Srdivacky BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0)); 1181202375Srdivacky if (Shift && !Shift->isShift()) 1182202375Srdivacky Shift = 0; 1183226633Sdim 1184202375Srdivacky ConstantInt *ShAmt; 1185202375Srdivacky ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0; 1186226633Sdim Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift. 1187226633Sdim Type *AndTy = AndCST->getType(); // Type of the and. 1188226633Sdim 1189202375Srdivacky // We can fold this as long as we can't shift unknown bits 1190202375Srdivacky // into the mask. This can only happen with signed shift 1191202375Srdivacky // rights, as they sign-extend. 1192202375Srdivacky if (ShAmt) { 1193202375Srdivacky bool CanFold = Shift->isLogicalShift(); 1194202375Srdivacky if (!CanFold) { 1195202375Srdivacky // To test for the bad case of the signed shr, see if any 1196202375Srdivacky // of the bits shifted in could be tested after the mask. 1197202375Srdivacky uint32_t TyBits = Ty->getPrimitiveSizeInBits(); 1198202375Srdivacky int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits); 1199226633Sdim 1200202375Srdivacky uint32_t BitWidth = AndTy->getPrimitiveSizeInBits(); 1201226633Sdim if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) & 1202202375Srdivacky AndCST->getValue()) == 0) 1203202375Srdivacky CanFold = true; 1204202375Srdivacky } 1205226633Sdim 1206202375Srdivacky if (CanFold) { 1207202375Srdivacky Constant *NewCst; 1208202375Srdivacky if (Shift->getOpcode() == Instruction::Shl) 1209202375Srdivacky NewCst = ConstantExpr::getLShr(RHS, ShAmt); 1210202375Srdivacky else 1211202375Srdivacky NewCst = ConstantExpr::getShl(RHS, ShAmt); 1212226633Sdim 1213202375Srdivacky // Check to see if we are shifting out any of the bits being 1214202375Srdivacky // compared. 1215202375Srdivacky if (ConstantExpr::get(Shift->getOpcode(), 1216202375Srdivacky NewCst, ShAmt) != RHS) { 1217202375Srdivacky // If we shifted bits out, the fold is not going to work out. 1218202375Srdivacky // As a special case, check to see if this means that the 1219202375Srdivacky // result is always true or false now. 1220202375Srdivacky if (ICI.getPredicate() == ICmpInst::ICMP_EQ) 1221202375Srdivacky return ReplaceInstUsesWith(ICI, 1222202375Srdivacky ConstantInt::getFalse(ICI.getContext())); 1223202375Srdivacky if (ICI.getPredicate() == ICmpInst::ICMP_NE) 1224202375Srdivacky return ReplaceInstUsesWith(ICI, 1225202375Srdivacky ConstantInt::getTrue(ICI.getContext())); 1226202375Srdivacky } else { 1227202375Srdivacky ICI.setOperand(1, NewCst); 1228202375Srdivacky Constant *NewAndCST; 1229202375Srdivacky if (Shift->getOpcode() == Instruction::Shl) 1230202375Srdivacky NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt); 1231202375Srdivacky else 1232202375Srdivacky NewAndCST = ConstantExpr::getShl(AndCST, ShAmt); 1233202375Srdivacky LHSI->setOperand(1, NewAndCST); 1234202375Srdivacky LHSI->setOperand(0, Shift->getOperand(0)); 1235202375Srdivacky Worklist.Add(Shift); // Shift is dead. 1236202375Srdivacky return &ICI; 1237202375Srdivacky } 1238202375Srdivacky } 1239202375Srdivacky } 1240226633Sdim 1241202375Srdivacky // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is 1242202375Srdivacky // preferable because it allows the C<<Y expression to be hoisted out 1243202375Srdivacky // of a loop if Y is invariant and X is not. 1244202375Srdivacky if (Shift && Shift->hasOneUse() && RHSV == 0 && 1245202375Srdivacky ICI.isEquality() && !Shift->isArithmeticShift() && 1246202375Srdivacky !isa<Constant>(Shift->getOperand(0))) { 1247202375Srdivacky // Compute C << Y. 1248202375Srdivacky Value *NS; 1249202375Srdivacky if (Shift->getOpcode() == Instruction::LShr) { 1250226633Sdim NS = Builder->CreateShl(AndCST, Shift->getOperand(1)); 1251202375Srdivacky } else { 1252202375Srdivacky // Insert a logical shift. 1253226633Sdim NS = Builder->CreateLShr(AndCST, Shift->getOperand(1)); 1254202375Srdivacky } 1255226633Sdim 1256202375Srdivacky // Compute X & (C << Y). 1257226633Sdim Value *NewAnd = 1258202375Srdivacky Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName()); 1259226633Sdim 1260202375Srdivacky ICI.setOperand(0, NewAnd); 1261202375Srdivacky return &ICI; 1262202375Srdivacky } 1263249423Sdim 1264249423Sdim // Replace ((X & AndCST) > RHSV) with ((X & AndCST) != 0), if any 1265249423Sdim // bit set in (X & AndCST) will produce a result greater than RHSV. 1266249423Sdim if (ICI.getPredicate() == ICmpInst::ICMP_UGT) { 1267249423Sdim unsigned NTZ = AndCST->getValue().countTrailingZeros(); 1268249423Sdim if ((NTZ < AndCST->getBitWidth()) && 1269249423Sdim APInt::getOneBitSet(AndCST->getBitWidth(), NTZ).ugt(RHSV)) 1270249423Sdim return new ICmpInst(ICmpInst::ICMP_NE, LHSI, 1271249423Sdim Constant::getNullValue(RHS->getType())); 1272249423Sdim } 1273202375Srdivacky } 1274226633Sdim 1275202375Srdivacky // Try to optimize things like "A[i]&42 == 0" to index computations. 1276202375Srdivacky if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) { 1277202375Srdivacky if (GetElementPtrInst *GEP = 1278202375Srdivacky dyn_cast<GetElementPtrInst>(LI->getOperand(0))) 1279202375Srdivacky if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) 1280202375Srdivacky if (GV->isConstant() && GV->hasDefinitiveInitializer() && 1281202375Srdivacky !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) { 1282202375Srdivacky ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1)); 1283202375Srdivacky if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C)) 1284202375Srdivacky return Res; 1285202375Srdivacky } 1286202375Srdivacky } 1287202375Srdivacky break; 1288202375Srdivacky 1289202375Srdivacky case Instruction::Or: { 1290202375Srdivacky if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse()) 1291202375Srdivacky break; 1292202375Srdivacky Value *P, *Q; 1293202375Srdivacky if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) { 1294202375Srdivacky // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0 1295202375Srdivacky // -> and (icmp eq P, null), (icmp eq Q, null). 1296202375Srdivacky Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P, 1297202375Srdivacky Constant::getNullValue(P->getType())); 1298202375Srdivacky Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q, 1299202375Srdivacky Constant::getNullValue(Q->getType())); 1300202375Srdivacky Instruction *Op; 1301202375Srdivacky if (ICI.getPredicate() == ICmpInst::ICMP_EQ) 1302202375Srdivacky Op = BinaryOperator::CreateAnd(ICIP, ICIQ); 1303202375Srdivacky else 1304202375Srdivacky Op = BinaryOperator::CreateOr(ICIP, ICIQ); 1305202375Srdivacky return Op; 1306202375Srdivacky } 1307202375Srdivacky break; 1308202375Srdivacky } 1309226633Sdim 1310249423Sdim case Instruction::Mul: { // (icmp pred (mul X, Val), CI) 1311249423Sdim ConstantInt *Val = dyn_cast<ConstantInt>(LHSI->getOperand(1)); 1312249423Sdim if (!Val) break; 1313249423Sdim 1314249423Sdim // If this is a signed comparison to 0 and the mul is sign preserving, 1315249423Sdim // use the mul LHS operand instead. 1316249423Sdim ICmpInst::Predicate pred = ICI.getPredicate(); 1317249423Sdim if (isSignTest(pred, RHS) && !Val->isZero() && 1318249423Sdim cast<BinaryOperator>(LHSI)->hasNoSignedWrap()) 1319249423Sdim return new ICmpInst(Val->isNegative() ? 1320249423Sdim ICmpInst::getSwappedPredicate(pred) : pred, 1321249423Sdim LHSI->getOperand(0), 1322249423Sdim Constant::getNullValue(RHS->getType())); 1323249423Sdim 1324249423Sdim break; 1325249423Sdim } 1326249423Sdim 1327202375Srdivacky case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI) 1328202375Srdivacky ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1)); 1329202375Srdivacky if (!ShAmt) break; 1330226633Sdim 1331202375Srdivacky uint32_t TypeBits = RHSV.getBitWidth(); 1332226633Sdim 1333202375Srdivacky // Check that the shift amount is in range. If not, don't perform 1334202375Srdivacky // undefined shifts. When the shift is visited it will be 1335202375Srdivacky // simplified. 1336202375Srdivacky if (ShAmt->uge(TypeBits)) 1337202375Srdivacky break; 1338226633Sdim 1339202375Srdivacky if (ICI.isEquality()) { 1340202375Srdivacky // If we are comparing against bits always shifted out, the 1341202375Srdivacky // comparison cannot succeed. 1342202375Srdivacky Constant *Comp = 1343202375Srdivacky ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), 1344202375Srdivacky ShAmt); 1345202375Srdivacky if (Comp != RHS) {// Comparing against a bit that we know is zero. 1346202375Srdivacky bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; 1347202375Srdivacky Constant *Cst = 1348202375Srdivacky ConstantInt::get(Type::getInt1Ty(ICI.getContext()), IsICMP_NE); 1349202375Srdivacky return ReplaceInstUsesWith(ICI, Cst); 1350202375Srdivacky } 1351226633Sdim 1352218893Sdim // If the shift is NUW, then it is just shifting out zeros, no need for an 1353218893Sdim // AND. 1354218893Sdim if (cast<BinaryOperator>(LHSI)->hasNoUnsignedWrap()) 1355218893Sdim return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), 1356218893Sdim ConstantExpr::getLShr(RHS, ShAmt)); 1357226633Sdim 1358249423Sdim // If the shift is NSW and we compare to 0, then it is just shifting out 1359249423Sdim // sign bits, no need for an AND either. 1360249423Sdim if (cast<BinaryOperator>(LHSI)->hasNoSignedWrap() && RHSV == 0) 1361249423Sdim return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), 1362249423Sdim ConstantExpr::getLShr(RHS, ShAmt)); 1363249423Sdim 1364202375Srdivacky if (LHSI->hasOneUse()) { 1365202375Srdivacky // Otherwise strength reduce the shift into an and. 1366202375Srdivacky uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); 1367202375Srdivacky Constant *Mask = 1368226633Sdim ConstantInt::get(ICI.getContext(), APInt::getLowBitsSet(TypeBits, 1369202375Srdivacky TypeBits-ShAmtVal)); 1370226633Sdim 1371202375Srdivacky Value *And = 1372202375Srdivacky Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask"); 1373202375Srdivacky return new ICmpInst(ICI.getPredicate(), And, 1374218893Sdim ConstantExpr::getLShr(RHS, ShAmt)); 1375202375Srdivacky } 1376202375Srdivacky } 1377226633Sdim 1378249423Sdim // If this is a signed comparison to 0 and the shift is sign preserving, 1379249423Sdim // use the shift LHS operand instead. 1380249423Sdim ICmpInst::Predicate pred = ICI.getPredicate(); 1381249423Sdim if (isSignTest(pred, RHS) && 1382249423Sdim cast<BinaryOperator>(LHSI)->hasNoSignedWrap()) 1383249423Sdim return new ICmpInst(pred, 1384249423Sdim LHSI->getOperand(0), 1385249423Sdim Constant::getNullValue(RHS->getType())); 1386249423Sdim 1387202375Srdivacky // Otherwise, if this is a comparison of the sign bit, simplify to and/test. 1388202375Srdivacky bool TrueIfSigned = false; 1389202375Srdivacky if (LHSI->hasOneUse() && 1390202375Srdivacky isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) { 1391202375Srdivacky // (X << 31) <s 0 --> (X&1) != 0 1392218893Sdim Constant *Mask = ConstantInt::get(LHSI->getOperand(0)->getType(), 1393226633Sdim APInt::getOneBitSet(TypeBits, 1394218893Sdim TypeBits-ShAmt->getZExtValue()-1)); 1395202375Srdivacky Value *And = 1396202375Srdivacky Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask"); 1397202375Srdivacky return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ, 1398202375Srdivacky And, Constant::getNullValue(And->getType())); 1399202375Srdivacky } 1400249423Sdim 1401249423Sdim // Transform (icmp pred iM (shl iM %v, N), CI) 1402249423Sdim // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (CI>>N)) 1403249423Sdim // Transform the shl to a trunc if (trunc (CI>>N)) has no loss and M-N. 1404249423Sdim // This enables to get rid of the shift in favor of a trunc which can be 1405249423Sdim // free on the target. It has the additional benefit of comparing to a 1406249423Sdim // smaller constant, which will be target friendly. 1407249423Sdim unsigned Amt = ShAmt->getLimitedValue(TypeBits-1); 1408249423Sdim if (LHSI->hasOneUse() && 1409249423Sdim Amt != 0 && RHSV.countTrailingZeros() >= Amt) { 1410249423Sdim Type *NTy = IntegerType::get(ICI.getContext(), TypeBits - Amt); 1411249423Sdim Constant *NCI = ConstantExpr::getTrunc( 1412249423Sdim ConstantExpr::getAShr(RHS, 1413249423Sdim ConstantInt::get(RHS->getType(), Amt)), 1414249423Sdim NTy); 1415249423Sdim return new ICmpInst(ICI.getPredicate(), 1416249423Sdim Builder->CreateTrunc(LHSI->getOperand(0), NTy), 1417249423Sdim NCI); 1418249423Sdim } 1419249423Sdim 1420202375Srdivacky break; 1421202375Srdivacky } 1422226633Sdim 1423202375Srdivacky case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI) 1424221345Sdim case Instruction::AShr: { 1425221345Sdim // Handle equality comparisons of shift-by-constant. 1426221345Sdim BinaryOperator *BO = cast<BinaryOperator>(LHSI); 1427221345Sdim if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { 1428221345Sdim if (Instruction *Res = FoldICmpShrCst(ICI, BO, ShAmt)) 1429218893Sdim return Res; 1430221345Sdim } 1431221345Sdim 1432221345Sdim // Handle exact shr's. 1433221345Sdim if (ICI.isEquality() && BO->isExact() && BO->hasOneUse()) { 1434221345Sdim if (RHSV.isMinValue()) 1435221345Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), RHS); 1436221345Sdim } 1437202375Srdivacky break; 1438221345Sdim } 1439226633Sdim 1440202375Srdivacky case Instruction::SDiv: 1441202375Srdivacky case Instruction::UDiv: 1442202375Srdivacky // Fold: icmp pred ([us]div X, C1), C2 -> range test 1443226633Sdim // Fold this div into the comparison, producing a range check. 1444226633Sdim // Determine, based on the divide type, what the range is being 1445226633Sdim // checked. If there is an overflow on the low or high side, remember 1446202375Srdivacky // it, otherwise compute the range [low, hi) bounding the new value. 1447202375Srdivacky // See: InsertRangeTest above for the kinds of replacements possible. 1448202375Srdivacky if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) 1449202375Srdivacky if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI), 1450202375Srdivacky DivRHS)) 1451202375Srdivacky return R; 1452202375Srdivacky break; 1453202375Srdivacky 1454202375Srdivacky case Instruction::Add: 1455202375Srdivacky // Fold: icmp pred (add X, C1), C2 1456202375Srdivacky if (!ICI.isEquality()) { 1457202375Srdivacky ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1)); 1458202375Srdivacky if (!LHSC) break; 1459202375Srdivacky const APInt &LHSV = LHSC->getValue(); 1460202375Srdivacky 1461202375Srdivacky ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV) 1462202375Srdivacky .subtract(LHSV); 1463202375Srdivacky 1464202375Srdivacky if (ICI.isSigned()) { 1465202375Srdivacky if (CR.getLower().isSignBit()) { 1466202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0), 1467202375Srdivacky ConstantInt::get(ICI.getContext(),CR.getUpper())); 1468202375Srdivacky } else if (CR.getUpper().isSignBit()) { 1469202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0), 1470202375Srdivacky ConstantInt::get(ICI.getContext(),CR.getLower())); 1471202375Srdivacky } 1472202375Srdivacky } else { 1473202375Srdivacky if (CR.getLower().isMinValue()) { 1474202375Srdivacky return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), 1475202375Srdivacky ConstantInt::get(ICI.getContext(),CR.getUpper())); 1476202375Srdivacky } else if (CR.getUpper().isMinValue()) { 1477202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), 1478202375Srdivacky ConstantInt::get(ICI.getContext(),CR.getLower())); 1479202375Srdivacky } 1480202375Srdivacky } 1481202375Srdivacky } 1482202375Srdivacky break; 1483202375Srdivacky } 1484226633Sdim 1485202375Srdivacky // Simplify icmp_eq and icmp_ne instructions with integer constant RHS. 1486202375Srdivacky if (ICI.isEquality()) { 1487202375Srdivacky bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; 1488226633Sdim 1489226633Sdim // If the first operand is (add|sub|and|or|xor|rem) with a constant, and 1490202375Srdivacky // the second operand is a constant, simplify a bit. 1491202375Srdivacky if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) { 1492202375Srdivacky switch (BO->getOpcode()) { 1493202375Srdivacky case Instruction::SRem: 1494202375Srdivacky // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. 1495202375Srdivacky if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){ 1496202375Srdivacky const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue(); 1497207618Srdivacky if (V.sgt(1) && V.isPowerOf2()) { 1498202375Srdivacky Value *NewRem = 1499202375Srdivacky Builder->CreateURem(BO->getOperand(0), BO->getOperand(1), 1500202375Srdivacky BO->getName()); 1501202375Srdivacky return new ICmpInst(ICI.getPredicate(), NewRem, 1502202375Srdivacky Constant::getNullValue(BO->getType())); 1503202375Srdivacky } 1504202375Srdivacky } 1505202375Srdivacky break; 1506202375Srdivacky case Instruction::Add: 1507202375Srdivacky // Replace ((add A, B) != C) with (A != C-B) if B & C are constants. 1508202375Srdivacky if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) { 1509202375Srdivacky if (BO->hasOneUse()) 1510202375Srdivacky return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1511202375Srdivacky ConstantExpr::getSub(RHS, BOp1C)); 1512202375Srdivacky } else if (RHSV == 0) { 1513202375Srdivacky // Replace ((add A, B) != 0) with (A != -B) if A or B is 1514202375Srdivacky // efficiently invertible, or if the add has just this one use. 1515202375Srdivacky Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1); 1516226633Sdim 1517202375Srdivacky if (Value *NegVal = dyn_castNegVal(BOp1)) 1518202375Srdivacky return new ICmpInst(ICI.getPredicate(), BOp0, NegVal); 1519221345Sdim if (Value *NegVal = dyn_castNegVal(BOp0)) 1520202375Srdivacky return new ICmpInst(ICI.getPredicate(), NegVal, BOp1); 1521221345Sdim if (BO->hasOneUse()) { 1522202375Srdivacky Value *Neg = Builder->CreateNeg(BOp1); 1523202375Srdivacky Neg->takeName(BO); 1524202375Srdivacky return new ICmpInst(ICI.getPredicate(), BOp0, Neg); 1525202375Srdivacky } 1526202375Srdivacky } 1527202375Srdivacky break; 1528202375Srdivacky case Instruction::Xor: 1529202375Srdivacky // For the xor case, we can xor two constants together, eliminating 1530202375Srdivacky // the explicit xor. 1531224145Sdim if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) { 1532224145Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1533202375Srdivacky ConstantExpr::getXor(RHS, BOC)); 1534224145Sdim } else if (RHSV == 0) { 1535224145Sdim // Replace ((xor A, B) != 0) with (A != B) 1536224145Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1537224145Sdim BO->getOperand(1)); 1538224145Sdim } 1539224145Sdim break; 1540202375Srdivacky case Instruction::Sub: 1541224145Sdim // Replace ((sub A, B) != C) with (B != A-C) if A & C are constants. 1542224145Sdim if (ConstantInt *BOp0C = dyn_cast<ConstantInt>(BO->getOperand(0))) { 1543224145Sdim if (BO->hasOneUse()) 1544224145Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(1), 1545224145Sdim ConstantExpr::getSub(BOp0C, RHS)); 1546224145Sdim } else if (RHSV == 0) { 1547224145Sdim // Replace ((sub A, B) != 0) with (A != B) 1548202375Srdivacky return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1549202375Srdivacky BO->getOperand(1)); 1550224145Sdim } 1551202375Srdivacky break; 1552202375Srdivacky case Instruction::Or: 1553202375Srdivacky // If bits are being or'd in that are not present in the constant we 1554202375Srdivacky // are comparing against, then the comparison could never succeed! 1555212904Sdim if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { 1556202375Srdivacky Constant *NotCI = ConstantExpr::getNot(RHS); 1557202375Srdivacky if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue()) 1558202375Srdivacky return ReplaceInstUsesWith(ICI, 1559226633Sdim ConstantInt::get(Type::getInt1Ty(ICI.getContext()), 1560202375Srdivacky isICMP_NE)); 1561202375Srdivacky } 1562202375Srdivacky break; 1563226633Sdim 1564202375Srdivacky case Instruction::And: 1565202375Srdivacky if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { 1566202375Srdivacky // If bits are being compared against that are and'd out, then the 1567202375Srdivacky // comparison can never succeed! 1568202375Srdivacky if ((RHSV & ~BOC->getValue()) != 0) 1569202375Srdivacky return ReplaceInstUsesWith(ICI, 1570202375Srdivacky ConstantInt::get(Type::getInt1Ty(ICI.getContext()), 1571202375Srdivacky isICMP_NE)); 1572226633Sdim 1573202375Srdivacky // If we have ((X & C) == C), turn it into ((X & C) != 0). 1574202375Srdivacky if (RHS == BOC && RHSV.isPowerOf2()) 1575202375Srdivacky return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : 1576202375Srdivacky ICmpInst::ICMP_NE, LHSI, 1577202375Srdivacky Constant::getNullValue(RHS->getType())); 1578224145Sdim 1579224145Sdim // Don't perform the following transforms if the AND has multiple uses 1580224145Sdim if (!BO->hasOneUse()) 1581224145Sdim break; 1582224145Sdim 1583202375Srdivacky // Replace (and X, (1 << size(X)-1) != 0) with x s< 0 1584202375Srdivacky if (BOC->getValue().isSignBit()) { 1585202375Srdivacky Value *X = BO->getOperand(0); 1586202375Srdivacky Constant *Zero = Constant::getNullValue(X->getType()); 1587226633Sdim ICmpInst::Predicate pred = isICMP_NE ? 1588202375Srdivacky ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE; 1589202375Srdivacky return new ICmpInst(pred, X, Zero); 1590202375Srdivacky } 1591226633Sdim 1592202375Srdivacky // ((X & ~7) == 0) --> X < 8 1593202375Srdivacky if (RHSV == 0 && isHighOnes(BOC)) { 1594202375Srdivacky Value *X = BO->getOperand(0); 1595202375Srdivacky Constant *NegX = ConstantExpr::getNeg(BOC); 1596226633Sdim ICmpInst::Predicate pred = isICMP_NE ? 1597202375Srdivacky ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT; 1598202375Srdivacky return new ICmpInst(pred, X, NegX); 1599202375Srdivacky } 1600202375Srdivacky } 1601249423Sdim break; 1602249423Sdim case Instruction::Mul: 1603249423Sdim if (RHSV == 0 && BO->hasNoSignedWrap()) { 1604249423Sdim if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { 1605249423Sdim // The trivial case (mul X, 0) is handled by InstSimplify 1606249423Sdim // General case : (mul X, C) != 0 iff X != 0 1607249423Sdim // (mul X, C) == 0 iff X == 0 1608249423Sdim if (!BOC->isZero()) 1609249423Sdim return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), 1610249423Sdim Constant::getNullValue(RHS->getType())); 1611249423Sdim } 1612249423Sdim } 1613249423Sdim break; 1614202375Srdivacky default: break; 1615202375Srdivacky } 1616202375Srdivacky } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) { 1617202375Srdivacky // Handle icmp {eq|ne} <intrinsic>, intcst. 1618202375Srdivacky switch (II->getIntrinsicID()) { 1619202375Srdivacky case Intrinsic::bswap: 1620202375Srdivacky Worklist.Add(II); 1621210299Sed ICI.setOperand(0, II->getArgOperand(0)); 1622202375Srdivacky ICI.setOperand(1, ConstantInt::get(II->getContext(), RHSV.byteSwap())); 1623202375Srdivacky return &ICI; 1624202375Srdivacky case Intrinsic::ctlz: 1625202375Srdivacky case Intrinsic::cttz: 1626202375Srdivacky // ctz(A) == bitwidth(a) -> A == 0 and likewise for != 1627202375Srdivacky if (RHSV == RHS->getType()->getBitWidth()) { 1628202375Srdivacky Worklist.Add(II); 1629210299Sed ICI.setOperand(0, II->getArgOperand(0)); 1630202375Srdivacky ICI.setOperand(1, ConstantInt::get(RHS->getType(), 0)); 1631202375Srdivacky return &ICI; 1632202375Srdivacky } 1633202375Srdivacky break; 1634202375Srdivacky case Intrinsic::ctpop: 1635202375Srdivacky // popcount(A) == 0 -> A == 0 and likewise for != 1636202375Srdivacky if (RHS->isZero()) { 1637202375Srdivacky Worklist.Add(II); 1638210299Sed ICI.setOperand(0, II->getArgOperand(0)); 1639202375Srdivacky ICI.setOperand(1, RHS); 1640202375Srdivacky return &ICI; 1641202375Srdivacky } 1642202375Srdivacky break; 1643202375Srdivacky default: 1644210299Sed break; 1645202375Srdivacky } 1646202375Srdivacky } 1647202375Srdivacky } 1648202375Srdivacky return 0; 1649202375Srdivacky} 1650202375Srdivacky 1651202375Srdivacky/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst). 1652202375Srdivacky/// We only handle extending casts so far. 1653202375Srdivacky/// 1654202375SrdivackyInstruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) { 1655202375Srdivacky const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0)); 1656202375Srdivacky Value *LHSCIOp = LHSCI->getOperand(0); 1657226633Sdim Type *SrcTy = LHSCIOp->getType(); 1658226633Sdim Type *DestTy = LHSCI->getType(); 1659202375Srdivacky Value *RHSCIOp; 1660202375Srdivacky 1661226633Sdim // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the 1662202375Srdivacky // integer type is the same size as the pointer type. 1663202375Srdivacky if (TD && LHSCI->getOpcode() == Instruction::PtrToInt && 1664202375Srdivacky TD->getPointerSizeInBits() == 1665202375Srdivacky cast<IntegerType>(DestTy)->getBitWidth()) { 1666202375Srdivacky Value *RHSOp = 0; 1667202375Srdivacky if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) { 1668202375Srdivacky RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy); 1669202375Srdivacky } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) { 1670202375Srdivacky RHSOp = RHSC->getOperand(0); 1671202375Srdivacky // If the pointer types don't match, insert a bitcast. 1672202375Srdivacky if (LHSCIOp->getType() != RHSOp->getType()) 1673202375Srdivacky RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType()); 1674202375Srdivacky } 1675202375Srdivacky 1676202375Srdivacky if (RHSOp) 1677202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp); 1678202375Srdivacky } 1679226633Sdim 1680202375Srdivacky // The code below only handles extension cast instructions, so far. 1681202375Srdivacky // Enforce this. 1682202375Srdivacky if (LHSCI->getOpcode() != Instruction::ZExt && 1683202375Srdivacky LHSCI->getOpcode() != Instruction::SExt) 1684202375Srdivacky return 0; 1685202375Srdivacky 1686202375Srdivacky bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt; 1687202375Srdivacky bool isSignedCmp = ICI.isSigned(); 1688202375Srdivacky 1689202375Srdivacky if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) { 1690202375Srdivacky // Not an extension from the same type? 1691202375Srdivacky RHSCIOp = CI->getOperand(0); 1692226633Sdim if (RHSCIOp->getType() != LHSCIOp->getType()) 1693202375Srdivacky return 0; 1694226633Sdim 1695202375Srdivacky // If the signedness of the two casts doesn't agree (i.e. one is a sext 1696202375Srdivacky // and the other is a zext), then we can't handle this. 1697202375Srdivacky if (CI->getOpcode() != LHSCI->getOpcode()) 1698202375Srdivacky return 0; 1699202375Srdivacky 1700202375Srdivacky // Deal with equality cases early. 1701202375Srdivacky if (ICI.isEquality()) 1702202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); 1703202375Srdivacky 1704202375Srdivacky // A signed comparison of sign extended values simplifies into a 1705202375Srdivacky // signed comparison. 1706202375Srdivacky if (isSignedCmp && isSignedExt) 1707202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); 1708202375Srdivacky 1709202375Srdivacky // The other three cases all fold into an unsigned comparison. 1710202375Srdivacky return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp); 1711202375Srdivacky } 1712202375Srdivacky 1713202375Srdivacky // If we aren't dealing with a constant on the RHS, exit early 1714202375Srdivacky ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1)); 1715202375Srdivacky if (!CI) 1716202375Srdivacky return 0; 1717202375Srdivacky 1718202375Srdivacky // Compute the constant that would happen if we truncated to SrcTy then 1719202375Srdivacky // reextended to DestTy. 1720202375Srdivacky Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy); 1721202375Srdivacky Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), 1722202375Srdivacky Res1, DestTy); 1723202375Srdivacky 1724202375Srdivacky // If the re-extended constant didn't change... 1725202375Srdivacky if (Res2 == CI) { 1726202375Srdivacky // Deal with equality cases early. 1727202375Srdivacky if (ICI.isEquality()) 1728202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); 1729202375Srdivacky 1730202375Srdivacky // A signed comparison of sign extended values simplifies into a 1731202375Srdivacky // signed comparison. 1732202375Srdivacky if (isSignedExt && isSignedCmp) 1733202375Srdivacky return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); 1734202375Srdivacky 1735202375Srdivacky // The other three cases all fold into an unsigned comparison. 1736202375Srdivacky return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1); 1737202375Srdivacky } 1738202375Srdivacky 1739226633Sdim // The re-extended constant changed so the constant cannot be represented 1740202375Srdivacky // in the shorter type. Consequently, we cannot emit a simple comparison. 1741218893Sdim // All the cases that fold to true or false will have already been handled 1742218893Sdim // by SimplifyICmpInst, so only deal with the tricky case. 1743202375Srdivacky 1744218893Sdim if (isSignedCmp || !isSignedExt) 1745218893Sdim return 0; 1746202375Srdivacky 1747202375Srdivacky // Evaluate the comparison for LT (we invert for GT below). LE and GE cases 1748202375Srdivacky // should have been folded away previously and not enter in here. 1749202375Srdivacky 1750218893Sdim // We're performing an unsigned comp with a sign extended value. 1751218893Sdim // This is true if the input is >= 0. [aka >s -1] 1752218893Sdim Constant *NegOne = Constant::getAllOnesValue(SrcTy); 1753218893Sdim Value *Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName()); 1754218893Sdim 1755202375Srdivacky // Finally, return the value computed. 1756218893Sdim if (ICI.getPredicate() == ICmpInst::ICMP_ULT) 1757202375Srdivacky return ReplaceInstUsesWith(ICI, Result); 1758202375Srdivacky 1759218893Sdim assert(ICI.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!"); 1760202375Srdivacky return BinaryOperator::CreateNot(Result); 1761202375Srdivacky} 1762202375Srdivacky 1763218893Sdim/// ProcessUGT_ADDCST_ADD - The caller has matched a pattern of the form: 1764218893Sdim/// I = icmp ugt (add (add A, B), CI2), CI1 1765218893Sdim/// If this is of the form: 1766218893Sdim/// sum = a + b 1767218893Sdim/// if (sum+128 >u 255) 1768218893Sdim/// Then replace it with llvm.sadd.with.overflow.i8. 1769218893Sdim/// 1770218893Sdimstatic Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B, 1771218893Sdim ConstantInt *CI2, ConstantInt *CI1, 1772218893Sdim InstCombiner &IC) { 1773218893Sdim // The transformation we're trying to do here is to transform this into an 1774218893Sdim // llvm.sadd.with.overflow. To do this, we have to replace the original add 1775218893Sdim // with a narrower add, and discard the add-with-constant that is part of the 1776218893Sdim // range check (if we can't eliminate it, this isn't profitable). 1777226633Sdim 1778218893Sdim // In order to eliminate the add-with-constant, the compare can be its only 1779218893Sdim // use. 1780218893Sdim Instruction *AddWithCst = cast<Instruction>(I.getOperand(0)); 1781218893Sdim if (!AddWithCst->hasOneUse()) return 0; 1782226633Sdim 1783218893Sdim // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow. 1784218893Sdim if (!CI2->getValue().isPowerOf2()) return 0; 1785218893Sdim unsigned NewWidth = CI2->getValue().countTrailingZeros(); 1786218893Sdim if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31) return 0; 1787226633Sdim 1788218893Sdim // The width of the new add formed is 1 more than the bias. 1789218893Sdim ++NewWidth; 1790226633Sdim 1791218893Sdim // Check to see that CI1 is an all-ones value with NewWidth bits. 1792218893Sdim if (CI1->getBitWidth() == NewWidth || 1793218893Sdim CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth)) 1794218893Sdim return 0; 1795226633Sdim 1796234353Sdim // This is only really a signed overflow check if the inputs have been 1797234353Sdim // sign-extended; check for that condition. For example, if CI2 is 2^31 and 1798234353Sdim // the operands of the add are 64 bits wide, we need at least 33 sign bits. 1799234353Sdim unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1; 1800234353Sdim if (IC.ComputeNumSignBits(A) < NeededSignBits || 1801234353Sdim IC.ComputeNumSignBits(B) < NeededSignBits) 1802234353Sdim return 0; 1803234353Sdim 1804226633Sdim // In order to replace the original add with a narrower 1805218893Sdim // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant 1806218893Sdim // and truncates that discard the high bits of the add. Verify that this is 1807218893Sdim // the case. 1808218893Sdim Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0)); 1809218893Sdim for (Value::use_iterator UI = OrigAdd->use_begin(), E = OrigAdd->use_end(); 1810218893Sdim UI != E; ++UI) { 1811218893Sdim if (*UI == AddWithCst) continue; 1812226633Sdim 1813218893Sdim // Only accept truncates for now. We would really like a nice recursive 1814218893Sdim // predicate like SimplifyDemandedBits, but which goes downwards the use-def 1815218893Sdim // chain to see which bits of a value are actually demanded. If the 1816218893Sdim // original add had another add which was then immediately truncated, we 1817218893Sdim // could still do the transformation. 1818218893Sdim TruncInst *TI = dyn_cast<TruncInst>(*UI); 1819218893Sdim if (TI == 0 || 1820218893Sdim TI->getType()->getPrimitiveSizeInBits() > NewWidth) return 0; 1821218893Sdim } 1822226633Sdim 1823218893Sdim // If the pattern matches, truncate the inputs to the narrower type and 1824218893Sdim // use the sadd_with_overflow intrinsic to efficiently compute both the 1825218893Sdim // result and the overflow bit. 1826218893Sdim Module *M = I.getParent()->getParent()->getParent(); 1827226633Sdim 1828224145Sdim Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth); 1829218893Sdim Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow, 1830224145Sdim NewType); 1831202375Srdivacky 1832218893Sdim InstCombiner::BuilderTy *Builder = IC.Builder; 1833226633Sdim 1834218893Sdim // Put the new code above the original add, in case there are any uses of the 1835218893Sdim // add between the add and the compare. 1836218893Sdim Builder->SetInsertPoint(OrigAdd); 1837226633Sdim 1838218893Sdim Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName()+".trunc"); 1839218893Sdim Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName()+".trunc"); 1840218893Sdim CallInst *Call = Builder->CreateCall2(F, TruncA, TruncB, "sadd"); 1841218893Sdim Value *Add = Builder->CreateExtractValue(Call, 0, "sadd.result"); 1842218893Sdim Value *ZExt = Builder->CreateZExt(Add, OrigAdd->getType()); 1843226633Sdim 1844218893Sdim // The inner add was the result of the narrow add, zero extended to the 1845218893Sdim // wider type. Replace it with the result computed by the intrinsic. 1846218893Sdim IC.ReplaceInstUsesWith(*OrigAdd, ZExt); 1847226633Sdim 1848218893Sdim // The original icmp gets replaced with the overflow value. 1849218893Sdim return ExtractValueInst::Create(Call, 1, "sadd.overflow"); 1850218893Sdim} 1851202375Srdivacky 1852218893Sdimstatic Instruction *ProcessUAddIdiom(Instruction &I, Value *OrigAddV, 1853218893Sdim InstCombiner &IC) { 1854218893Sdim // Don't bother doing this transformation for pointers, don't do it for 1855218893Sdim // vectors. 1856218893Sdim if (!isa<IntegerType>(OrigAddV->getType())) return 0; 1857226633Sdim 1858218893Sdim // If the add is a constant expr, then we don't bother transforming it. 1859218893Sdim Instruction *OrigAdd = dyn_cast<Instruction>(OrigAddV); 1860218893Sdim if (OrigAdd == 0) return 0; 1861226633Sdim 1862218893Sdim Value *LHS = OrigAdd->getOperand(0), *RHS = OrigAdd->getOperand(1); 1863226633Sdim 1864218893Sdim // Put the new code above the original add, in case there are any uses of the 1865218893Sdim // add between the add and the compare. 1866218893Sdim InstCombiner::BuilderTy *Builder = IC.Builder; 1867218893Sdim Builder->SetInsertPoint(OrigAdd); 1868218893Sdim 1869218893Sdim Module *M = I.getParent()->getParent()->getParent(); 1870224145Sdim Type *Ty = LHS->getType(); 1871224145Sdim Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty); 1872218893Sdim CallInst *Call = Builder->CreateCall2(F, LHS, RHS, "uadd"); 1873218893Sdim Value *Add = Builder->CreateExtractValue(Call, 0); 1874218893Sdim 1875218893Sdim IC.ReplaceInstUsesWith(*OrigAdd, Add); 1876218893Sdim 1877218893Sdim // The original icmp gets replaced with the overflow value. 1878218893Sdim return ExtractValueInst::Create(Call, 1, "uadd.overflow"); 1879218893Sdim} 1880218893Sdim 1881218893Sdim// DemandedBitsLHSMask - When performing a comparison against a constant, 1882218893Sdim// it is possible that not all the bits in the LHS are demanded. This helper 1883218893Sdim// method computes the mask that IS demanded. 1884218893Sdimstatic APInt DemandedBitsLHSMask(ICmpInst &I, 1885218893Sdim unsigned BitWidth, bool isSignCheck) { 1886218893Sdim if (isSignCheck) 1887218893Sdim return APInt::getSignBit(BitWidth); 1888226633Sdim 1889218893Sdim ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(1)); 1890218893Sdim if (!CI) return APInt::getAllOnesValue(BitWidth); 1891218893Sdim const APInt &RHS = CI->getValue(); 1892226633Sdim 1893218893Sdim switch (I.getPredicate()) { 1894226633Sdim // For a UGT comparison, we don't care about any bits that 1895218893Sdim // correspond to the trailing ones of the comparand. The value of these 1896218893Sdim // bits doesn't impact the outcome of the comparison, because any value 1897218893Sdim // greater than the RHS must differ in a bit higher than these due to carry. 1898218893Sdim case ICmpInst::ICMP_UGT: { 1899218893Sdim unsigned trailingOnes = RHS.countTrailingOnes(); 1900218893Sdim APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingOnes); 1901218893Sdim return ~lowBitsSet; 1902218893Sdim } 1903226633Sdim 1904218893Sdim // Similarly, for a ULT comparison, we don't care about the trailing zeros. 1905218893Sdim // Any value less than the RHS must differ in a higher bit because of carries. 1906218893Sdim case ICmpInst::ICMP_ULT: { 1907218893Sdim unsigned trailingZeros = RHS.countTrailingZeros(); 1908218893Sdim APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingZeros); 1909218893Sdim return ~lowBitsSet; 1910218893Sdim } 1911226633Sdim 1912218893Sdim default: 1913218893Sdim return APInt::getAllOnesValue(BitWidth); 1914218893Sdim } 1915226633Sdim 1916218893Sdim} 1917218893Sdim 1918202375SrdivackyInstruction *InstCombiner::visitICmpInst(ICmpInst &I) { 1919202375Srdivacky bool Changed = false; 1920203954Srdivacky Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); 1921226633Sdim 1922202375Srdivacky /// Orders the operands of the compare so that they are listed from most 1923202375Srdivacky /// complex to least complex. This puts constants before unary operators, 1924202375Srdivacky /// before binary operators. 1925203954Srdivacky if (getComplexity(Op0) < getComplexity(Op1)) { 1926202375Srdivacky I.swapOperands(); 1927203954Srdivacky std::swap(Op0, Op1); 1928202375Srdivacky Changed = true; 1929202375Srdivacky } 1930226633Sdim 1931202375Srdivacky if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD)) 1932202375Srdivacky return ReplaceInstUsesWith(I, V); 1933202375Srdivacky 1934234353Sdim // comparing -val or val with non-zero is the same as just comparing val 1935234353Sdim // ie, abs(val) != 0 -> val != 0 1936234353Sdim if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero())) 1937234353Sdim { 1938234353Sdim Value *Cond, *SelectTrue, *SelectFalse; 1939234353Sdim if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue), 1940234353Sdim m_Value(SelectFalse)))) { 1941234353Sdim if (Value *V = dyn_castNegVal(SelectTrue)) { 1942234353Sdim if (V == SelectFalse) 1943234353Sdim return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1); 1944234353Sdim } 1945234353Sdim else if (Value *V = dyn_castNegVal(SelectFalse)) { 1946234353Sdim if (V == SelectTrue) 1947234353Sdim return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1); 1948234353Sdim } 1949234353Sdim } 1950234353Sdim } 1951234353Sdim 1952226633Sdim Type *Ty = Op0->getType(); 1953226633Sdim 1954202375Srdivacky // icmp's with boolean values can always be turned into bitwise operations 1955203954Srdivacky if (Ty->isIntegerTy(1)) { 1956202375Srdivacky switch (I.getPredicate()) { 1957202375Srdivacky default: llvm_unreachable("Invalid icmp instruction!"); 1958202375Srdivacky case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B) 1959202375Srdivacky Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp"); 1960202375Srdivacky return BinaryOperator::CreateNot(Xor); 1961202375Srdivacky } 1962202375Srdivacky case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B 1963202375Srdivacky return BinaryOperator::CreateXor(Op0, Op1); 1964202375Srdivacky 1965202375Srdivacky case ICmpInst::ICMP_UGT: 1966202375Srdivacky std::swap(Op0, Op1); // Change icmp ugt -> icmp ult 1967202375Srdivacky // FALL THROUGH 1968202375Srdivacky case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B 1969202375Srdivacky Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp"); 1970202375Srdivacky return BinaryOperator::CreateAnd(Not, Op1); 1971202375Srdivacky } 1972202375Srdivacky case ICmpInst::ICMP_SGT: 1973202375Srdivacky std::swap(Op0, Op1); // Change icmp sgt -> icmp slt 1974202375Srdivacky // FALL THROUGH 1975202375Srdivacky case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B 1976202375Srdivacky Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp"); 1977202375Srdivacky return BinaryOperator::CreateAnd(Not, Op0); 1978202375Srdivacky } 1979202375Srdivacky case ICmpInst::ICMP_UGE: 1980202375Srdivacky std::swap(Op0, Op1); // Change icmp uge -> icmp ule 1981202375Srdivacky // FALL THROUGH 1982202375Srdivacky case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B 1983202375Srdivacky Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp"); 1984202375Srdivacky return BinaryOperator::CreateOr(Not, Op1); 1985202375Srdivacky } 1986202375Srdivacky case ICmpInst::ICMP_SGE: 1987202375Srdivacky std::swap(Op0, Op1); // Change icmp sge -> icmp sle 1988202375Srdivacky // FALL THROUGH 1989202375Srdivacky case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B 1990202375Srdivacky Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp"); 1991202375Srdivacky return BinaryOperator::CreateOr(Not, Op0); 1992202375Srdivacky } 1993202375Srdivacky } 1994202375Srdivacky } 1995202375Srdivacky 1996202375Srdivacky unsigned BitWidth = 0; 1997218893Sdim if (Ty->isIntOrIntVectorTy()) 1998218893Sdim BitWidth = Ty->getScalarSizeInBits(); 1999218893Sdim else if (TD) // Pointers require TD info to get their size. 2000202375Srdivacky BitWidth = TD->getTypeSizeInBits(Ty->getScalarType()); 2001226633Sdim 2002202375Srdivacky bool isSignBit = false; 2003202375Srdivacky 2004202375Srdivacky // See if we are doing a comparison with a constant. 2005202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2006202375Srdivacky Value *A = 0, *B = 0; 2007226633Sdim 2008218893Sdim // Match the following pattern, which is a common idiom when writing 2009218893Sdim // overflow-safe integer arithmetic function. The source performs an 2010218893Sdim // addition in wider type, and explicitly checks for overflow using 2011218893Sdim // comparisons against INT_MIN and INT_MAX. Simplify this by using the 2012218893Sdim // sadd_with_overflow intrinsic. 2013218893Sdim // 2014218893Sdim // TODO: This could probably be generalized to handle other overflow-safe 2015226633Sdim // operations if we worked out the formulas to compute the appropriate 2016218893Sdim // magic constants. 2017226633Sdim // 2018218893Sdim // sum = a + b 2019218893Sdim // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8 2020218893Sdim { 2021218893Sdim ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI 2022218893Sdim if (I.getPredicate() == ICmpInst::ICMP_UGT && 2023218893Sdim match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2)))) 2024218893Sdim if (Instruction *Res = ProcessUGT_ADDCST_ADD(I, A, B, CI2, CI, *this)) 2025218893Sdim return Res; 2026218893Sdim } 2027226633Sdim 2028202375Srdivacky // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B) 2029202375Srdivacky if (I.isEquality() && CI->isZero() && 2030202375Srdivacky match(Op0, m_Sub(m_Value(A), m_Value(B)))) { 2031202375Srdivacky // (icmp cond A B) if cond is equality 2032202375Srdivacky return new ICmpInst(I.getPredicate(), A, B); 2033202375Srdivacky } 2034226633Sdim 2035202375Srdivacky // If we have an icmp le or icmp ge instruction, turn it into the 2036202375Srdivacky // appropriate icmp lt or icmp gt instruction. This allows us to rely on 2037202375Srdivacky // them being folded in the code below. The SimplifyICmpInst code has 2038202375Srdivacky // already handled the edge cases for us, so we just assert on them. 2039202375Srdivacky switch (I.getPredicate()) { 2040202375Srdivacky default: break; 2041202375Srdivacky case ICmpInst::ICMP_ULE: 2042202375Srdivacky assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE 2043202375Srdivacky return new ICmpInst(ICmpInst::ICMP_ULT, Op0, 2044202375Srdivacky ConstantInt::get(CI->getContext(), CI->getValue()+1)); 2045202375Srdivacky case ICmpInst::ICMP_SLE: 2046202375Srdivacky assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE 2047202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, Op0, 2048202375Srdivacky ConstantInt::get(CI->getContext(), CI->getValue()+1)); 2049202375Srdivacky case ICmpInst::ICMP_UGE: 2050221345Sdim assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE 2051202375Srdivacky return new ICmpInst(ICmpInst::ICMP_UGT, Op0, 2052202375Srdivacky ConstantInt::get(CI->getContext(), CI->getValue()-1)); 2053202375Srdivacky case ICmpInst::ICMP_SGE: 2054221345Sdim assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE 2055202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGT, Op0, 2056202375Srdivacky ConstantInt::get(CI->getContext(), CI->getValue()-1)); 2057202375Srdivacky } 2058226633Sdim 2059202375Srdivacky // If this comparison is a normal comparison, it demands all 2060202375Srdivacky // bits, if it is a sign bit comparison, it only demands the sign bit. 2061202375Srdivacky bool UnusedBit; 2062202375Srdivacky isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit); 2063202375Srdivacky } 2064202375Srdivacky 2065202375Srdivacky // See if we can fold the comparison based on range information we can get 2066202375Srdivacky // by checking whether bits are known to be zero or one in the input. 2067202375Srdivacky if (BitWidth != 0) { 2068202375Srdivacky APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0); 2069202375Srdivacky APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0); 2070202375Srdivacky 2071202375Srdivacky if (SimplifyDemandedBits(I.getOperandUse(0), 2072218893Sdim DemandedBitsLHSMask(I, BitWidth, isSignBit), 2073202375Srdivacky Op0KnownZero, Op0KnownOne, 0)) 2074202375Srdivacky return &I; 2075202375Srdivacky if (SimplifyDemandedBits(I.getOperandUse(1), 2076202375Srdivacky APInt::getAllOnesValue(BitWidth), 2077202375Srdivacky Op1KnownZero, Op1KnownOne, 0)) 2078202375Srdivacky return &I; 2079202375Srdivacky 2080202375Srdivacky // Given the known and unknown bits, compute a range that the LHS could be 2081202375Srdivacky // in. Compute the Min, Max and RHS values based on the known bits. For the 2082202375Srdivacky // EQ and NE we use unsigned values. 2083202375Srdivacky APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0); 2084202375Srdivacky APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0); 2085202375Srdivacky if (I.isSigned()) { 2086202375Srdivacky ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne, 2087202375Srdivacky Op0Min, Op0Max); 2088202375Srdivacky ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne, 2089202375Srdivacky Op1Min, Op1Max); 2090202375Srdivacky } else { 2091202375Srdivacky ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne, 2092202375Srdivacky Op0Min, Op0Max); 2093202375Srdivacky ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne, 2094202375Srdivacky Op1Min, Op1Max); 2095202375Srdivacky } 2096202375Srdivacky 2097202375Srdivacky // If Min and Max are known to be the same, then SimplifyDemandedBits 2098202375Srdivacky // figured out that the LHS is a constant. Just constant fold this now so 2099202375Srdivacky // that code below can assume that Min != Max. 2100202375Srdivacky if (!isa<Constant>(Op0) && Op0Min == Op0Max) 2101202375Srdivacky return new ICmpInst(I.getPredicate(), 2102221345Sdim ConstantInt::get(Op0->getType(), Op0Min), Op1); 2103202375Srdivacky if (!isa<Constant>(Op1) && Op1Min == Op1Max) 2104202375Srdivacky return new ICmpInst(I.getPredicate(), Op0, 2105221345Sdim ConstantInt::get(Op1->getType(), Op1Min)); 2106202375Srdivacky 2107202375Srdivacky // Based on the range information we know about the LHS, see if we can 2108221345Sdim // simplify this comparison. For example, (x&4) < 8 is always true. 2109202375Srdivacky switch (I.getPredicate()) { 2110202375Srdivacky default: llvm_unreachable("Unknown icmp opcode!"); 2111218893Sdim case ICmpInst::ICMP_EQ: { 2112202375Srdivacky if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) 2113221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2114226633Sdim 2115218893Sdim // If all bits are known zero except for one, then we know at most one 2116218893Sdim // bit is set. If the comparison is against zero, then this is a check 2117218893Sdim // to see if *that* bit is set. 2118218893Sdim APInt Op0KnownZeroInverted = ~Op0KnownZero; 2119218893Sdim if (~Op1KnownZero == 0 && Op0KnownZeroInverted.isPowerOf2()) { 2120218893Sdim // If the LHS is an AND with the same constant, look through it. 2121218893Sdim Value *LHS = 0; 2122218893Sdim ConstantInt *LHSC = 0; 2123218893Sdim if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) || 2124218893Sdim LHSC->getValue() != Op0KnownZeroInverted) 2125218893Sdim LHS = Op0; 2126226633Sdim 2127218893Sdim // If the LHS is 1 << x, and we know the result is a power of 2 like 8, 2128218893Sdim // then turn "((1 << x)&8) == 0" into "x != 3". 2129218893Sdim Value *X = 0; 2130218893Sdim if (match(LHS, m_Shl(m_One(), m_Value(X)))) { 2131218893Sdim unsigned CmpVal = Op0KnownZeroInverted.countTrailingZeros(); 2132218893Sdim return new ICmpInst(ICmpInst::ICMP_NE, X, 2133218893Sdim ConstantInt::get(X->getType(), CmpVal)); 2134218893Sdim } 2135226633Sdim 2136218893Sdim // If the LHS is 8 >>u x, and we know the result is a power of 2 like 1, 2137218893Sdim // then turn "((8 >>u x)&1) == 0" into "x != 3". 2138218893Sdim const APInt *CI; 2139218893Sdim if (Op0KnownZeroInverted == 1 && 2140218893Sdim match(LHS, m_LShr(m_Power2(CI), m_Value(X)))) 2141218893Sdim return new ICmpInst(ICmpInst::ICMP_NE, X, 2142218893Sdim ConstantInt::get(X->getType(), 2143218893Sdim CI->countTrailingZeros())); 2144218893Sdim } 2145226633Sdim 2146202375Srdivacky break; 2147218893Sdim } 2148218893Sdim case ICmpInst::ICMP_NE: { 2149202375Srdivacky if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) 2150221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2151226633Sdim 2152218893Sdim // If all bits are known zero except for one, then we know at most one 2153218893Sdim // bit is set. If the comparison is against zero, then this is a check 2154218893Sdim // to see if *that* bit is set. 2155218893Sdim APInt Op0KnownZeroInverted = ~Op0KnownZero; 2156218893Sdim if (~Op1KnownZero == 0 && Op0KnownZeroInverted.isPowerOf2()) { 2157218893Sdim // If the LHS is an AND with the same constant, look through it. 2158218893Sdim Value *LHS = 0; 2159218893Sdim ConstantInt *LHSC = 0; 2160218893Sdim if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) || 2161218893Sdim LHSC->getValue() != Op0KnownZeroInverted) 2162218893Sdim LHS = Op0; 2163226633Sdim 2164218893Sdim // If the LHS is 1 << x, and we know the result is a power of 2 like 8, 2165218893Sdim // then turn "((1 << x)&8) != 0" into "x == 3". 2166218893Sdim Value *X = 0; 2167218893Sdim if (match(LHS, m_Shl(m_One(), m_Value(X)))) { 2168218893Sdim unsigned CmpVal = Op0KnownZeroInverted.countTrailingZeros(); 2169218893Sdim return new ICmpInst(ICmpInst::ICMP_EQ, X, 2170218893Sdim ConstantInt::get(X->getType(), CmpVal)); 2171218893Sdim } 2172226633Sdim 2173218893Sdim // If the LHS is 8 >>u x, and we know the result is a power of 2 like 1, 2174218893Sdim // then turn "((8 >>u x)&1) != 0" into "x == 3". 2175218893Sdim const APInt *CI; 2176218893Sdim if (Op0KnownZeroInverted == 1 && 2177218893Sdim match(LHS, m_LShr(m_Power2(CI), m_Value(X)))) 2178218893Sdim return new ICmpInst(ICmpInst::ICMP_EQ, X, 2179218893Sdim ConstantInt::get(X->getType(), 2180218893Sdim CI->countTrailingZeros())); 2181218893Sdim } 2182226633Sdim 2183202375Srdivacky break; 2184218893Sdim } 2185202375Srdivacky case ICmpInst::ICMP_ULT: 2186202375Srdivacky if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B) 2187221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2188202375Srdivacky if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B) 2189221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2190202375Srdivacky if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B) 2191202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); 2192202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2193202375Srdivacky if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C 2194202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Op0, 2195202375Srdivacky ConstantInt::get(CI->getContext(), CI->getValue()-1)); 2196202375Srdivacky 2197202375Srdivacky // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear 2198202375Srdivacky if (CI->isMinValue(true)) 2199202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SGT, Op0, 2200202375Srdivacky Constant::getAllOnesValue(Op0->getType())); 2201202375Srdivacky } 2202202375Srdivacky break; 2203202375Srdivacky case ICmpInst::ICMP_UGT: 2204202375Srdivacky if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B) 2205221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2206202375Srdivacky if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B) 2207221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2208202375Srdivacky 2209202375Srdivacky if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B) 2210202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); 2211202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2212202375Srdivacky if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C 2213202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Op0, 2214202375Srdivacky ConstantInt::get(CI->getContext(), CI->getValue()+1)); 2215202375Srdivacky 2216202375Srdivacky // (x >u 2147483647) -> (x <s 0) -> true if sign bit set 2217202375Srdivacky if (CI->isMaxValue(true)) 2218202375Srdivacky return new ICmpInst(ICmpInst::ICMP_SLT, Op0, 2219202375Srdivacky Constant::getNullValue(Op0->getType())); 2220202375Srdivacky } 2221202375Srdivacky break; 2222202375Srdivacky case ICmpInst::ICMP_SLT: 2223202375Srdivacky if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C) 2224221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2225202375Srdivacky if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C) 2226221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2227202375Srdivacky if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B) 2228202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); 2229202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2230202375Srdivacky if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C 2231202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Op0, 2232202375Srdivacky ConstantInt::get(CI->getContext(), CI->getValue()-1)); 2233202375Srdivacky } 2234202375Srdivacky break; 2235202375Srdivacky case ICmpInst::ICMP_SGT: 2236202375Srdivacky if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B) 2237221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2238202375Srdivacky if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B) 2239221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2240202375Srdivacky 2241202375Srdivacky if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B) 2242202375Srdivacky return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); 2243202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2244202375Srdivacky if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C 2245202375Srdivacky return new ICmpInst(ICmpInst::ICMP_EQ, Op0, 2246202375Srdivacky ConstantInt::get(CI->getContext(), CI->getValue()+1)); 2247202375Srdivacky } 2248202375Srdivacky break; 2249202375Srdivacky case ICmpInst::ICMP_SGE: 2250202375Srdivacky assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!"); 2251202375Srdivacky if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B) 2252221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2253202375Srdivacky if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B) 2254221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2255202375Srdivacky break; 2256202375Srdivacky case ICmpInst::ICMP_SLE: 2257202375Srdivacky assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!"); 2258202375Srdivacky if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B) 2259221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2260202375Srdivacky if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B) 2261221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2262202375Srdivacky break; 2263202375Srdivacky case ICmpInst::ICMP_UGE: 2264202375Srdivacky assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!"); 2265202375Srdivacky if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B) 2266221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2267202375Srdivacky if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B) 2268221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2269202375Srdivacky break; 2270202375Srdivacky case ICmpInst::ICMP_ULE: 2271202375Srdivacky assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!"); 2272202375Srdivacky if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B) 2273221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2274202375Srdivacky if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B) 2275221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2276202375Srdivacky break; 2277202375Srdivacky } 2278202375Srdivacky 2279202375Srdivacky // Turn a signed comparison into an unsigned one if both operands 2280202375Srdivacky // are known to have the same sign. 2281202375Srdivacky if (I.isSigned() && 2282202375Srdivacky ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) || 2283202375Srdivacky (Op0KnownOne.isNegative() && Op1KnownOne.isNegative()))) 2284202375Srdivacky return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1); 2285202375Srdivacky } 2286202375Srdivacky 2287202375Srdivacky // Test if the ICmpInst instruction is used exclusively by a select as 2288202375Srdivacky // part of a minimum or maximum operation. If so, refrain from doing 2289202375Srdivacky // any other folding. This helps out other analyses which understand 2290202375Srdivacky // non-obfuscated minimum and maximum idioms, such as ScalarEvolution 2291202375Srdivacky // and CodeGen. And in this case, at least one of the comparison 2292202375Srdivacky // operands has at least one user besides the compare (the select), 2293202375Srdivacky // which would often largely negate the benefit of folding anyway. 2294202375Srdivacky if (I.hasOneUse()) 2295202375Srdivacky if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin())) 2296202375Srdivacky if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) || 2297202375Srdivacky (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1)) 2298202375Srdivacky return 0; 2299202375Srdivacky 2300202375Srdivacky // See if we are doing a comparison between a constant and an instruction that 2301202375Srdivacky // can be folded into the comparison. 2302202375Srdivacky if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { 2303226633Sdim // Since the RHS is a ConstantInt (CI), if the left hand side is an 2304226633Sdim // instruction, see if that instruction also has constants so that the 2305226633Sdim // instruction can be folded into the icmp 2306202375Srdivacky if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) 2307202375Srdivacky if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI)) 2308202375Srdivacky return Res; 2309202375Srdivacky } 2310202375Srdivacky 2311202375Srdivacky // Handle icmp with constant (but not simple integer constant) RHS 2312202375Srdivacky if (Constant *RHSC = dyn_cast<Constant>(Op1)) { 2313202375Srdivacky if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) 2314202375Srdivacky switch (LHSI->getOpcode()) { 2315202375Srdivacky case Instruction::GetElementPtr: 2316202375Srdivacky // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null 2317202375Srdivacky if (RHSC->isNullValue() && 2318202375Srdivacky cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices()) 2319202375Srdivacky return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), 2320202375Srdivacky Constant::getNullValue(LHSI->getOperand(0)->getType())); 2321202375Srdivacky break; 2322202375Srdivacky case Instruction::PHI: 2323202375Srdivacky // Only fold icmp into the PHI if the phi and icmp are in the same 2324202375Srdivacky // block. If in the same block, we're encouraging jump threading. If 2325202375Srdivacky // not, we are just pessimizing the code by making an i1 phi. 2326202375Srdivacky if (LHSI->getParent() == I.getParent()) 2327218893Sdim if (Instruction *NV = FoldOpIntoPhi(I)) 2328202375Srdivacky return NV; 2329202375Srdivacky break; 2330202375Srdivacky case Instruction::Select: { 2331202375Srdivacky // If either operand of the select is a constant, we can fold the 2332202375Srdivacky // comparison into the select arms, which will cause one to be 2333202375Srdivacky // constant folded and the select turned into a bitwise or. 2334202375Srdivacky Value *Op1 = 0, *Op2 = 0; 2335202375Srdivacky if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) 2336202375Srdivacky Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); 2337202375Srdivacky if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) 2338202375Srdivacky Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); 2339202375Srdivacky 2340202375Srdivacky // We only want to perform this transformation if it will not lead to 2341202375Srdivacky // additional code. This is true if either both sides of the select 2342202375Srdivacky // fold to a constant (in which case the icmp is replaced with a select 2343202375Srdivacky // which will usually simplify) or this is the only user of the 2344202375Srdivacky // select (in which case we are trading a select+icmp for a simpler 2345202375Srdivacky // select+icmp). 2346202375Srdivacky if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) { 2347202375Srdivacky if (!Op1) 2348202375Srdivacky Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1), 2349202375Srdivacky RHSC, I.getName()); 2350202375Srdivacky if (!Op2) 2351202375Srdivacky Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2), 2352202375Srdivacky RHSC, I.getName()); 2353202375Srdivacky return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); 2354202375Srdivacky } 2355202375Srdivacky break; 2356202375Srdivacky } 2357202375Srdivacky case Instruction::IntToPtr: 2358202375Srdivacky // icmp pred inttoptr(X), null -> icmp pred X, 0 2359202375Srdivacky if (RHSC->isNullValue() && TD && 2360226633Sdim TD->getIntPtrType(RHSC->getContext()) == 2361202375Srdivacky LHSI->getOperand(0)->getType()) 2362202375Srdivacky return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), 2363202375Srdivacky Constant::getNullValue(LHSI->getOperand(0)->getType())); 2364202375Srdivacky break; 2365202375Srdivacky 2366202375Srdivacky case Instruction::Load: 2367202375Srdivacky // Try to optimize things like "A[i] > 4" to index computations. 2368202375Srdivacky if (GetElementPtrInst *GEP = 2369202375Srdivacky dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) { 2370202375Srdivacky if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) 2371202375Srdivacky if (GV->isConstant() && GV->hasDefinitiveInitializer() && 2372202375Srdivacky !cast<LoadInst>(LHSI)->isVolatile()) 2373202375Srdivacky if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) 2374202375Srdivacky return Res; 2375202375Srdivacky } 2376202375Srdivacky break; 2377202375Srdivacky } 2378202375Srdivacky } 2379202375Srdivacky 2380202375Srdivacky // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now. 2381202375Srdivacky if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0)) 2382202375Srdivacky if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I)) 2383202375Srdivacky return NI; 2384202375Srdivacky if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1)) 2385202375Srdivacky if (Instruction *NI = FoldGEPICmp(GEP, Op0, 2386202375Srdivacky ICmpInst::getSwappedPredicate(I.getPredicate()), I)) 2387202375Srdivacky return NI; 2388202375Srdivacky 2389202375Srdivacky // Test to see if the operands of the icmp are casted versions of other 2390202375Srdivacky // values. If the ptr->ptr cast can be stripped off both arguments, we do so 2391202375Srdivacky // now. 2392202375Srdivacky if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) { 2393226633Sdim if (Op0->getType()->isPointerTy() && 2394226633Sdim (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) { 2395202375Srdivacky // We keep moving the cast from the left operand over to the right 2396202375Srdivacky // operand, where it can often be eliminated completely. 2397202375Srdivacky Op0 = CI->getOperand(0); 2398202375Srdivacky 2399202375Srdivacky // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast 2400202375Srdivacky // so eliminate it as well. 2401202375Srdivacky if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1)) 2402202375Srdivacky Op1 = CI2->getOperand(0); 2403202375Srdivacky 2404202375Srdivacky // If Op1 is a constant, we can fold the cast into the constant. 2405202375Srdivacky if (Op0->getType() != Op1->getType()) { 2406202375Srdivacky if (Constant *Op1C = dyn_cast<Constant>(Op1)) { 2407202375Srdivacky Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType()); 2408202375Srdivacky } else { 2409202375Srdivacky // Otherwise, cast the RHS right before the icmp 2410202375Srdivacky Op1 = Builder->CreateBitCast(Op1, Op0->getType()); 2411202375Srdivacky } 2412202375Srdivacky } 2413202375Srdivacky return new ICmpInst(I.getPredicate(), Op0, Op1); 2414202375Srdivacky } 2415202375Srdivacky } 2416226633Sdim 2417202375Srdivacky if (isa<CastInst>(Op0)) { 2418202375Srdivacky // Handle the special case of: icmp (cast bool to X), <cst> 2419202375Srdivacky // This comes up when you have code like 2420202375Srdivacky // int X = A < B; 2421202375Srdivacky // if (X) ... 2422202375Srdivacky // For generality, we handle any zero-extension of any operand comparison 2423202375Srdivacky // with a constant or another cast from the same type. 2424202375Srdivacky if (isa<Constant>(Op1) || isa<CastInst>(Op1)) 2425202375Srdivacky if (Instruction *R = visitICmpInstWithCastAndCast(I)) 2426202375Srdivacky return R; 2427202375Srdivacky } 2428218893Sdim 2429218893Sdim // Special logic for binary operators. 2430218893Sdim BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0); 2431218893Sdim BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1); 2432218893Sdim if (BO0 || BO1) { 2433218893Sdim CmpInst::Predicate Pred = I.getPredicate(); 2434218893Sdim bool NoOp0WrapProblem = false, NoOp1WrapProblem = false; 2435218893Sdim if (BO0 && isa<OverflowingBinaryOperator>(BO0)) 2436218893Sdim NoOp0WrapProblem = ICmpInst::isEquality(Pred) || 2437218893Sdim (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) || 2438218893Sdim (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap()); 2439218893Sdim if (BO1 && isa<OverflowingBinaryOperator>(BO1)) 2440218893Sdim NoOp1WrapProblem = ICmpInst::isEquality(Pred) || 2441218893Sdim (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) || 2442218893Sdim (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap()); 2443218893Sdim 2444218893Sdim // Analyze the case when either Op0 or Op1 is an add instruction. 2445218893Sdim // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null). 2446218893Sdim Value *A = 0, *B = 0, *C = 0, *D = 0; 2447218893Sdim if (BO0 && BO0->getOpcode() == Instruction::Add) 2448218893Sdim A = BO0->getOperand(0), B = BO0->getOperand(1); 2449218893Sdim if (BO1 && BO1->getOpcode() == Instruction::Add) 2450218893Sdim C = BO1->getOperand(0), D = BO1->getOperand(1); 2451218893Sdim 2452218893Sdim // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 2453218893Sdim if ((A == Op1 || B == Op1) && NoOp0WrapProblem) 2454218893Sdim return new ICmpInst(Pred, A == Op1 ? B : A, 2455218893Sdim Constant::getNullValue(Op1->getType())); 2456218893Sdim 2457218893Sdim // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 2458218893Sdim if ((C == Op0 || D == Op0) && NoOp1WrapProblem) 2459218893Sdim return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()), 2460218893Sdim C == Op0 ? D : C); 2461218893Sdim 2462218893Sdim // icmp (X+Y), (X+Z) -> icmp Y, Z for equalities or if there is no overflow. 2463218893Sdim if (A && C && (A == C || A == D || B == C || B == D) && 2464218893Sdim NoOp0WrapProblem && NoOp1WrapProblem && 2465218893Sdim // Try not to increase register pressure. 2466218893Sdim BO0->hasOneUse() && BO1->hasOneUse()) { 2467218893Sdim // Determine Y and Z in the form icmp (X+Y), (X+Z). 2468243830Sdim Value *Y, *Z; 2469243830Sdim if (A == C) { 2470243830Sdim // C + B == C + D -> B == D 2471243830Sdim Y = B; 2472243830Sdim Z = D; 2473243830Sdim } else if (A == D) { 2474243830Sdim // D + B == C + D -> B == C 2475243830Sdim Y = B; 2476243830Sdim Z = C; 2477243830Sdim } else if (B == C) { 2478243830Sdim // A + C == C + D -> A == D 2479243830Sdim Y = A; 2480243830Sdim Z = D; 2481243830Sdim } else { 2482243830Sdim assert(B == D); 2483243830Sdim // A + D == C + D -> A == C 2484243830Sdim Y = A; 2485243830Sdim Z = C; 2486243830Sdim } 2487218893Sdim return new ICmpInst(Pred, Y, Z); 2488218893Sdim } 2489218893Sdim 2490251662Sdim // icmp slt (X + -1), Y -> icmp sle X, Y 2491251662Sdim if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT && 2492251662Sdim match(B, m_AllOnes())) 2493251662Sdim return new ICmpInst(CmpInst::ICMP_SLE, A, Op1); 2494251662Sdim 2495251662Sdim // icmp sge (X + -1), Y -> icmp sgt X, Y 2496251662Sdim if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE && 2497251662Sdim match(B, m_AllOnes())) 2498251662Sdim return new ICmpInst(CmpInst::ICMP_SGT, A, Op1); 2499251662Sdim 2500251662Sdim // icmp sle (X + 1), Y -> icmp slt X, Y 2501251662Sdim if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE && 2502251662Sdim match(B, m_One())) 2503251662Sdim return new ICmpInst(CmpInst::ICMP_SLT, A, Op1); 2504251662Sdim 2505251662Sdim // icmp sgt (X + 1), Y -> icmp sge X, Y 2506251662Sdim if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT && 2507251662Sdim match(B, m_One())) 2508251662Sdim return new ICmpInst(CmpInst::ICMP_SGE, A, Op1); 2509251662Sdim 2510251662Sdim // if C1 has greater magnitude than C2: 2511251662Sdim // icmp (X + C1), (Y + C2) -> icmp (X + C3), Y 2512251662Sdim // s.t. C3 = C1 - C2 2513251662Sdim // 2514251662Sdim // if C2 has greater magnitude than C1: 2515251662Sdim // icmp (X + C1), (Y + C2) -> icmp X, (Y + C3) 2516251662Sdim // s.t. C3 = C2 - C1 2517251662Sdim if (A && C && NoOp0WrapProblem && NoOp1WrapProblem && 2518251662Sdim (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned()) 2519251662Sdim if (ConstantInt *C1 = dyn_cast<ConstantInt>(B)) 2520251662Sdim if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) { 2521251662Sdim const APInt &AP1 = C1->getValue(); 2522251662Sdim const APInt &AP2 = C2->getValue(); 2523251662Sdim if (AP1.isNegative() == AP2.isNegative()) { 2524251662Sdim APInt AP1Abs = C1->getValue().abs(); 2525251662Sdim APInt AP2Abs = C2->getValue().abs(); 2526251662Sdim if (AP1Abs.uge(AP2Abs)) { 2527251662Sdim ConstantInt *C3 = Builder->getInt(AP1 - AP2); 2528251662Sdim Value *NewAdd = Builder->CreateNSWAdd(A, C3); 2529251662Sdim return new ICmpInst(Pred, NewAdd, C); 2530251662Sdim } else { 2531251662Sdim ConstantInt *C3 = Builder->getInt(AP2 - AP1); 2532251662Sdim Value *NewAdd = Builder->CreateNSWAdd(C, C3); 2533251662Sdim return new ICmpInst(Pred, A, NewAdd); 2534251662Sdim } 2535251662Sdim } 2536251662Sdim } 2537251662Sdim 2538251662Sdim 2539218893Sdim // Analyze the case when either Op0 or Op1 is a sub instruction. 2540218893Sdim // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null). 2541218893Sdim A = 0; B = 0; C = 0; D = 0; 2542218893Sdim if (BO0 && BO0->getOpcode() == Instruction::Sub) 2543218893Sdim A = BO0->getOperand(0), B = BO0->getOperand(1); 2544218893Sdim if (BO1 && BO1->getOpcode() == Instruction::Sub) 2545218893Sdim C = BO1->getOperand(0), D = BO1->getOperand(1); 2546218893Sdim 2547218893Sdim // icmp (X-Y), X -> icmp 0, Y for equalities or if there is no overflow. 2548218893Sdim if (A == Op1 && NoOp0WrapProblem) 2549218893Sdim return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B); 2550218893Sdim 2551218893Sdim // icmp X, (X-Y) -> icmp Y, 0 for equalities or if there is no overflow. 2552218893Sdim if (C == Op0 && NoOp1WrapProblem) 2553218893Sdim return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType())); 2554218893Sdim 2555218893Sdim // icmp (Y-X), (Z-X) -> icmp Y, Z for equalities or if there is no overflow. 2556218893Sdim if (B && D && B == D && NoOp0WrapProblem && NoOp1WrapProblem && 2557218893Sdim // Try not to increase register pressure. 2558218893Sdim BO0->hasOneUse() && BO1->hasOneUse()) 2559218893Sdim return new ICmpInst(Pred, A, C); 2560218893Sdim 2561218893Sdim // icmp (X-Y), (X-Z) -> icmp Z, Y for equalities or if there is no overflow. 2562218893Sdim if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem && 2563218893Sdim // Try not to increase register pressure. 2564218893Sdim BO0->hasOneUse() && BO1->hasOneUse()) 2565218893Sdim return new ICmpInst(Pred, D, B); 2566218893Sdim 2567221345Sdim BinaryOperator *SRem = NULL; 2568221345Sdim // icmp (srem X, Y), Y 2569221345Sdim if (BO0 && BO0->getOpcode() == Instruction::SRem && 2570221345Sdim Op1 == BO0->getOperand(1)) 2571221345Sdim SRem = BO0; 2572221345Sdim // icmp Y, (srem X, Y) 2573221345Sdim else if (BO1 && BO1->getOpcode() == Instruction::SRem && 2574221345Sdim Op0 == BO1->getOperand(1)) 2575221345Sdim SRem = BO1; 2576221345Sdim if (SRem) { 2577221345Sdim // We don't check hasOneUse to avoid increasing register pressure because 2578221345Sdim // the value we use is the same value this instruction was already using. 2579221345Sdim switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) { 2580221345Sdim default: break; 2581221345Sdim case ICmpInst::ICMP_EQ: 2582221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType())); 2583221345Sdim case ICmpInst::ICMP_NE: 2584221345Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType())); 2585221345Sdim case ICmpInst::ICMP_SGT: 2586221345Sdim case ICmpInst::ICMP_SGE: 2587221345Sdim return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1), 2588221345Sdim Constant::getAllOnesValue(SRem->getType())); 2589221345Sdim case ICmpInst::ICMP_SLT: 2590221345Sdim case ICmpInst::ICMP_SLE: 2591221345Sdim return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1), 2592221345Sdim Constant::getNullValue(SRem->getType())); 2593221345Sdim } 2594221345Sdim } 2595221345Sdim 2596218893Sdim if (BO0 && BO1 && BO0->getOpcode() == BO1->getOpcode() && 2597218893Sdim BO0->hasOneUse() && BO1->hasOneUse() && 2598218893Sdim BO0->getOperand(1) == BO1->getOperand(1)) { 2599218893Sdim switch (BO0->getOpcode()) { 2600218893Sdim default: break; 2601218893Sdim case Instruction::Add: 2602218893Sdim case Instruction::Sub: 2603218893Sdim case Instruction::Xor: 2604218893Sdim if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b 2605218893Sdim return new ICmpInst(I.getPredicate(), BO0->getOperand(0), 2606218893Sdim BO1->getOperand(0)); 2607218893Sdim // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b 2608218893Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) { 2609218893Sdim if (CI->getValue().isSignBit()) { 2610218893Sdim ICmpInst::Predicate Pred = I.isSigned() 2611218893Sdim ? I.getUnsignedPredicate() 2612218893Sdim : I.getSignedPredicate(); 2613218893Sdim return new ICmpInst(Pred, BO0->getOperand(0), 2614218893Sdim BO1->getOperand(0)); 2615202375Srdivacky } 2616226633Sdim 2617224145Sdim if (CI->isMaxValue(true)) { 2618218893Sdim ICmpInst::Predicate Pred = I.isSigned() 2619218893Sdim ? I.getUnsignedPredicate() 2620218893Sdim : I.getSignedPredicate(); 2621218893Sdim Pred = I.getSwappedPredicate(Pred); 2622218893Sdim return new ICmpInst(Pred, BO0->getOperand(0), 2623218893Sdim BO1->getOperand(0)); 2624218893Sdim } 2625218893Sdim } 2626218893Sdim break; 2627218893Sdim case Instruction::Mul: 2628218893Sdim if (!I.isEquality()) 2629202375Srdivacky break; 2630202375Srdivacky 2631218893Sdim if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) { 2632218893Sdim // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask 2633218893Sdim // Mask = -1 >> count-trailing-zeros(Cst). 2634218893Sdim if (!CI->isZero() && !CI->isOne()) { 2635218893Sdim const APInt &AP = CI->getValue(); 2636226633Sdim ConstantInt *Mask = ConstantInt::get(I.getContext(), 2637218893Sdim APInt::getLowBitsSet(AP.getBitWidth(), 2638218893Sdim AP.getBitWidth() - 2639218893Sdim AP.countTrailingZeros())); 2640218893Sdim Value *And1 = Builder->CreateAnd(BO0->getOperand(0), Mask); 2641218893Sdim Value *And2 = Builder->CreateAnd(BO1->getOperand(0), Mask); 2642218893Sdim return new ICmpInst(I.getPredicate(), And1, And2); 2643202375Srdivacky } 2644202375Srdivacky } 2645218893Sdim break; 2646221345Sdim case Instruction::UDiv: 2647221345Sdim case Instruction::LShr: 2648221345Sdim if (I.isSigned()) 2649221345Sdim break; 2650221345Sdim // fall-through 2651221345Sdim case Instruction::SDiv: 2652221345Sdim case Instruction::AShr: 2653223017Sdim if (!BO0->isExact() || !BO1->isExact()) 2654221345Sdim break; 2655221345Sdim return new ICmpInst(I.getPredicate(), BO0->getOperand(0), 2656221345Sdim BO1->getOperand(0)); 2657221345Sdim case Instruction::Shl: { 2658221345Sdim bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap(); 2659221345Sdim bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap(); 2660221345Sdim if (!NUW && !NSW) 2661221345Sdim break; 2662221345Sdim if (!NSW && I.isSigned()) 2663221345Sdim break; 2664221345Sdim return new ICmpInst(I.getPredicate(), BO0->getOperand(0), 2665221345Sdim BO1->getOperand(0)); 2666202375Srdivacky } 2667221345Sdim } 2668202375Srdivacky } 2669202375Srdivacky } 2670226633Sdim 2671202375Srdivacky { Value *A, *B; 2672251662Sdim // Transform (A & ~B) == 0 --> (A & B) != 0 2673251662Sdim // and (A & ~B) != 0 --> (A & B) == 0 2674251662Sdim // if A is a power of 2. 2675251662Sdim if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) && 2676251662Sdim match(Op1, m_Zero()) && isKnownToBeAPowerOfTwo(A) && I.isEquality()) 2677251662Sdim return new ICmpInst(I.getInversePredicate(), 2678251662Sdim Builder->CreateAnd(A, B), 2679251662Sdim Op1); 2680251662Sdim 2681218893Sdim // ~x < ~y --> y < x 2682218893Sdim // ~x < cst --> ~cst < x 2683218893Sdim if (match(Op0, m_Not(m_Value(A)))) { 2684218893Sdim if (match(Op1, m_Not(m_Value(B)))) 2685218893Sdim return new ICmpInst(I.getPredicate(), B, A); 2686218893Sdim if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1)) 2687218893Sdim return new ICmpInst(I.getPredicate(), ConstantExpr::getNot(RHSC), A); 2688218893Sdim } 2689218893Sdim 2690218893Sdim // (a+b) <u a --> llvm.uadd.with.overflow. 2691218893Sdim // (a+b) <u b --> llvm.uadd.with.overflow. 2692218893Sdim if (I.getPredicate() == ICmpInst::ICMP_ULT && 2693226633Sdim match(Op0, m_Add(m_Value(A), m_Value(B))) && 2694218893Sdim (Op1 == A || Op1 == B)) 2695218893Sdim if (Instruction *R = ProcessUAddIdiom(I, Op0, *this)) 2696218893Sdim return R; 2697226633Sdim 2698218893Sdim // a >u (a+b) --> llvm.uadd.with.overflow. 2699218893Sdim // b >u (a+b) --> llvm.uadd.with.overflow. 2700218893Sdim if (I.getPredicate() == ICmpInst::ICMP_UGT && 2701218893Sdim match(Op1, m_Add(m_Value(A), m_Value(B))) && 2702218893Sdim (Op0 == A || Op0 == B)) 2703218893Sdim if (Instruction *R = ProcessUAddIdiom(I, Op1, *this)) 2704218893Sdim return R; 2705202375Srdivacky } 2706226633Sdim 2707202375Srdivacky if (I.isEquality()) { 2708202375Srdivacky Value *A, *B, *C, *D; 2709218893Sdim 2710202375Srdivacky if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) { 2711202375Srdivacky if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0 2712202375Srdivacky Value *OtherVal = A == Op1 ? B : A; 2713202375Srdivacky return new ICmpInst(I.getPredicate(), OtherVal, 2714202375Srdivacky Constant::getNullValue(A->getType())); 2715202375Srdivacky } 2716202375Srdivacky 2717202375Srdivacky if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) { 2718202375Srdivacky // A^c1 == C^c2 --> A == C^(c1^c2) 2719202375Srdivacky ConstantInt *C1, *C2; 2720202375Srdivacky if (match(B, m_ConstantInt(C1)) && 2721202375Srdivacky match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) { 2722202375Srdivacky Constant *NC = ConstantInt::get(I.getContext(), 2723202375Srdivacky C1->getValue() ^ C2->getValue()); 2724226633Sdim Value *Xor = Builder->CreateXor(C, NC); 2725202375Srdivacky return new ICmpInst(I.getPredicate(), A, Xor); 2726202375Srdivacky } 2727226633Sdim 2728202375Srdivacky // A^B == A^D -> B == D 2729202375Srdivacky if (A == C) return new ICmpInst(I.getPredicate(), B, D); 2730202375Srdivacky if (A == D) return new ICmpInst(I.getPredicate(), B, C); 2731202375Srdivacky if (B == C) return new ICmpInst(I.getPredicate(), A, D); 2732202375Srdivacky if (B == D) return new ICmpInst(I.getPredicate(), A, C); 2733202375Srdivacky } 2734202375Srdivacky } 2735226633Sdim 2736202375Srdivacky if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && 2737202375Srdivacky (A == Op0 || B == Op0)) { 2738202375Srdivacky // A == (A^B) -> B == 0 2739202375Srdivacky Value *OtherVal = A == Op0 ? B : A; 2740202375Srdivacky return new ICmpInst(I.getPredicate(), OtherVal, 2741202375Srdivacky Constant::getNullValue(A->getType())); 2742202375Srdivacky } 2743202375Srdivacky 2744202375Srdivacky // (X&Z) == (Y&Z) -> (X^Y) & Z == 0 2745226633Sdim if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) && 2746221345Sdim match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) { 2747202375Srdivacky Value *X = 0, *Y = 0, *Z = 0; 2748226633Sdim 2749202375Srdivacky if (A == C) { 2750202375Srdivacky X = B; Y = D; Z = A; 2751202375Srdivacky } else if (A == D) { 2752202375Srdivacky X = B; Y = C; Z = A; 2753202375Srdivacky } else if (B == C) { 2754202375Srdivacky X = A; Y = D; Z = B; 2755202375Srdivacky } else if (B == D) { 2756202375Srdivacky X = A; Y = C; Z = B; 2757202375Srdivacky } 2758226633Sdim 2759202375Srdivacky if (X) { // Build (X^Y) & Z 2760226633Sdim Op1 = Builder->CreateXor(X, Y); 2761226633Sdim Op1 = Builder->CreateAnd(Op1, Z); 2762202375Srdivacky I.setOperand(0, Op1); 2763202375Srdivacky I.setOperand(1, Constant::getNullValue(Op1->getType())); 2764202375Srdivacky return &I; 2765202375Srdivacky } 2766202375Srdivacky } 2767226633Sdim 2768239462Sdim // Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B) 2769239462Sdim // and (B & (1<<X)-1) == (zext A) --> A == (trunc B) 2770239462Sdim ConstantInt *Cst1; 2771239462Sdim if ((Op0->hasOneUse() && 2772239462Sdim match(Op0, m_ZExt(m_Value(A))) && 2773239462Sdim match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) || 2774239462Sdim (Op1->hasOneUse() && 2775239462Sdim match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) && 2776239462Sdim match(Op1, m_ZExt(m_Value(A))))) { 2777239462Sdim APInt Pow2 = Cst1->getValue() + 1; 2778239462Sdim if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) && 2779239462Sdim Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth()) 2780239462Sdim return new ICmpInst(I.getPredicate(), A, 2781239462Sdim Builder->CreateTrunc(B, A->getType())); 2782239462Sdim } 2783239462Sdim 2784221345Sdim // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to 2785221345Sdim // "icmp (and X, mask), cst" 2786221345Sdim uint64_t ShAmt = 0; 2787221345Sdim if (Op0->hasOneUse() && 2788221345Sdim match(Op0, m_Trunc(m_OneUse(m_LShr(m_Value(A), 2789221345Sdim m_ConstantInt(ShAmt))))) && 2790221345Sdim match(Op1, m_ConstantInt(Cst1)) && 2791221345Sdim // Only do this when A has multiple uses. This is most important to do 2792221345Sdim // when it exposes other optimizations. 2793221345Sdim !A->hasOneUse()) { 2794221345Sdim unsigned ASize =cast<IntegerType>(A->getType())->getPrimitiveSizeInBits(); 2795226633Sdim 2796221345Sdim if (ShAmt < ASize) { 2797221345Sdim APInt MaskV = 2798221345Sdim APInt::getLowBitsSet(ASize, Op0->getType()->getPrimitiveSizeInBits()); 2799221345Sdim MaskV <<= ShAmt; 2800226633Sdim 2801221345Sdim APInt CmpV = Cst1->getValue().zext(ASize); 2802221345Sdim CmpV <<= ShAmt; 2803226633Sdim 2804221345Sdim Value *Mask = Builder->CreateAnd(A, Builder->getInt(MaskV)); 2805221345Sdim return new ICmpInst(I.getPredicate(), Mask, Builder->getInt(CmpV)); 2806221345Sdim } 2807221345Sdim } 2808202375Srdivacky } 2809226633Sdim 2810202375Srdivacky { 2811202375Srdivacky Value *X; ConstantInt *Cst; 2812202375Srdivacky // icmp X+Cst, X 2813202375Srdivacky if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X) 2814202375Srdivacky return FoldICmpAddOpCst(I, X, Cst, I.getPredicate(), Op0); 2815202375Srdivacky 2816202375Srdivacky // icmp X, X+Cst 2817202375Srdivacky if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X) 2818202375Srdivacky return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate(), Op1); 2819202375Srdivacky } 2820202375Srdivacky return Changed ? &I : 0; 2821202375Srdivacky} 2822202375Srdivacky 2823202375Srdivacky 2824202375Srdivacky 2825202375Srdivacky 2826202375Srdivacky 2827202375Srdivacky 2828202375Srdivacky/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible. 2829202375Srdivacky/// 2830202375SrdivackyInstruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I, 2831202375Srdivacky Instruction *LHSI, 2832202375Srdivacky Constant *RHSC) { 2833202375Srdivacky if (!isa<ConstantFP>(RHSC)) return 0; 2834202375Srdivacky const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF(); 2835226633Sdim 2836202375Srdivacky // Get the width of the mantissa. We don't want to hack on conversions that 2837202375Srdivacky // might lose information from the integer, e.g. "i64 -> float" 2838202375Srdivacky int MantissaWidth = LHSI->getType()->getFPMantissaWidth(); 2839202375Srdivacky if (MantissaWidth == -1) return 0; // Unknown. 2840226633Sdim 2841202375Srdivacky // Check to see that the input is converted from an integer type that is small 2842202375Srdivacky // enough that preserves all bits. TODO: check here for "known" sign bits. 2843202375Srdivacky // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e. 2844202375Srdivacky unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits(); 2845226633Sdim 2846202375Srdivacky // If this is a uitofp instruction, we need an extra bit to hold the sign. 2847202375Srdivacky bool LHSUnsigned = isa<UIToFPInst>(LHSI); 2848202375Srdivacky if (LHSUnsigned) 2849202375Srdivacky ++InputSize; 2850226633Sdim 2851202375Srdivacky // If the conversion would lose info, don't hack on this. 2852202375Srdivacky if ((int)InputSize > MantissaWidth) 2853202375Srdivacky return 0; 2854226633Sdim 2855202375Srdivacky // Otherwise, we can potentially simplify the comparison. We know that it 2856202375Srdivacky // will always come through as an integer value and we know the constant is 2857202375Srdivacky // not a NAN (it would have been previously simplified). 2858202375Srdivacky assert(!RHS.isNaN() && "NaN comparison not already folded!"); 2859226633Sdim 2860202375Srdivacky ICmpInst::Predicate Pred; 2861202375Srdivacky switch (I.getPredicate()) { 2862202375Srdivacky default: llvm_unreachable("Unexpected predicate!"); 2863202375Srdivacky case FCmpInst::FCMP_UEQ: 2864202375Srdivacky case FCmpInst::FCMP_OEQ: 2865202375Srdivacky Pred = ICmpInst::ICMP_EQ; 2866202375Srdivacky break; 2867202375Srdivacky case FCmpInst::FCMP_UGT: 2868202375Srdivacky case FCmpInst::FCMP_OGT: 2869202375Srdivacky Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT; 2870202375Srdivacky break; 2871202375Srdivacky case FCmpInst::FCMP_UGE: 2872202375Srdivacky case FCmpInst::FCMP_OGE: 2873202375Srdivacky Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE; 2874202375Srdivacky break; 2875202375Srdivacky case FCmpInst::FCMP_ULT: 2876202375Srdivacky case FCmpInst::FCMP_OLT: 2877202375Srdivacky Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT; 2878202375Srdivacky break; 2879202375Srdivacky case FCmpInst::FCMP_ULE: 2880202375Srdivacky case FCmpInst::FCMP_OLE: 2881202375Srdivacky Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE; 2882202375Srdivacky break; 2883202375Srdivacky case FCmpInst::FCMP_UNE: 2884202375Srdivacky case FCmpInst::FCMP_ONE: 2885202375Srdivacky Pred = ICmpInst::ICMP_NE; 2886202375Srdivacky break; 2887202375Srdivacky case FCmpInst::FCMP_ORD: 2888202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); 2889202375Srdivacky case FCmpInst::FCMP_UNO: 2890202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); 2891202375Srdivacky } 2892226633Sdim 2893226633Sdim IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType()); 2894226633Sdim 2895202375Srdivacky // Now we know that the APFloat is a normal number, zero or inf. 2896226633Sdim 2897202375Srdivacky // See if the FP constant is too large for the integer. For example, 2898202375Srdivacky // comparing an i8 to 300.0. 2899202375Srdivacky unsigned IntWidth = IntTy->getScalarSizeInBits(); 2900226633Sdim 2901202375Srdivacky if (!LHSUnsigned) { 2902202375Srdivacky // If the RHS value is > SignedMax, fold the comparison. This handles +INF 2903202375Srdivacky // and large values. 2904202375Srdivacky APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false); 2905202375Srdivacky SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true, 2906202375Srdivacky APFloat::rmNearestTiesToEven); 2907202375Srdivacky if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0 2908202375Srdivacky if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT || 2909202375Srdivacky Pred == ICmpInst::ICMP_SLE) 2910202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); 2911202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); 2912202375Srdivacky } 2913202375Srdivacky } else { 2914202375Srdivacky // If the RHS value is > UnsignedMax, fold the comparison. This handles 2915202375Srdivacky // +INF and large values. 2916202375Srdivacky APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false); 2917202375Srdivacky UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false, 2918202375Srdivacky APFloat::rmNearestTiesToEven); 2919202375Srdivacky if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0 2920202375Srdivacky if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT || 2921202375Srdivacky Pred == ICmpInst::ICMP_ULE) 2922202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); 2923202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); 2924202375Srdivacky } 2925202375Srdivacky } 2926226633Sdim 2927202375Srdivacky if (!LHSUnsigned) { 2928202375Srdivacky // See if the RHS value is < SignedMin. 2929202375Srdivacky APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false); 2930202375Srdivacky SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true, 2931202375Srdivacky APFloat::rmNearestTiesToEven); 2932202375Srdivacky if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0 2933202375Srdivacky if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT || 2934202375Srdivacky Pred == ICmpInst::ICMP_SGE) 2935202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); 2936202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); 2937202375Srdivacky } 2938234353Sdim } else { 2939234353Sdim // See if the RHS value is < UnsignedMin. 2940234353Sdim APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false); 2941234353Sdim SMin.convertFromAPInt(APInt::getMinValue(IntWidth), true, 2942234353Sdim APFloat::rmNearestTiesToEven); 2943234353Sdim if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // umin > 12312.0 2944234353Sdim if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_UGT || 2945234353Sdim Pred == ICmpInst::ICMP_UGE) 2946234353Sdim return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); 2947234353Sdim return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); 2948234353Sdim } 2949202375Srdivacky } 2950202375Srdivacky 2951202375Srdivacky // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or 2952202375Srdivacky // [0, UMAX], but it may still be fractional. See if it is fractional by 2953202375Srdivacky // casting the FP value to the integer value and back, checking for equality. 2954202375Srdivacky // Don't do this for zero, because -0.0 is not fractional. 2955202375Srdivacky Constant *RHSInt = LHSUnsigned 2956202375Srdivacky ? ConstantExpr::getFPToUI(RHSC, IntTy) 2957202375Srdivacky : ConstantExpr::getFPToSI(RHSC, IntTy); 2958202375Srdivacky if (!RHS.isZero()) { 2959202375Srdivacky bool Equal = LHSUnsigned 2960202375Srdivacky ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC 2961202375Srdivacky : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC; 2962202375Srdivacky if (!Equal) { 2963202375Srdivacky // If we had a comparison against a fractional value, we have to adjust 2964202375Srdivacky // the compare predicate and sometimes the value. RHSC is rounded towards 2965202375Srdivacky // zero at this point. 2966202375Srdivacky switch (Pred) { 2967202375Srdivacky default: llvm_unreachable("Unexpected integer comparison!"); 2968202375Srdivacky case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true 2969202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); 2970202375Srdivacky case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false 2971202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); 2972202375Srdivacky case ICmpInst::ICMP_ULE: 2973202375Srdivacky // (float)int <= 4.4 --> int <= 4 2974202375Srdivacky // (float)int <= -4.4 --> false 2975202375Srdivacky if (RHS.isNegative()) 2976202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); 2977202375Srdivacky break; 2978202375Srdivacky case ICmpInst::ICMP_SLE: 2979202375Srdivacky // (float)int <= 4.4 --> int <= 4 2980202375Srdivacky // (float)int <= -4.4 --> int < -4 2981202375Srdivacky if (RHS.isNegative()) 2982202375Srdivacky Pred = ICmpInst::ICMP_SLT; 2983202375Srdivacky break; 2984202375Srdivacky case ICmpInst::ICMP_ULT: 2985202375Srdivacky // (float)int < -4.4 --> false 2986202375Srdivacky // (float)int < 4.4 --> int <= 4 2987202375Srdivacky if (RHS.isNegative()) 2988202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); 2989202375Srdivacky Pred = ICmpInst::ICMP_ULE; 2990202375Srdivacky break; 2991202375Srdivacky case ICmpInst::ICMP_SLT: 2992202375Srdivacky // (float)int < -4.4 --> int < -4 2993202375Srdivacky // (float)int < 4.4 --> int <= 4 2994202375Srdivacky if (!RHS.isNegative()) 2995202375Srdivacky Pred = ICmpInst::ICMP_SLE; 2996202375Srdivacky break; 2997202375Srdivacky case ICmpInst::ICMP_UGT: 2998202375Srdivacky // (float)int > 4.4 --> int > 4 2999202375Srdivacky // (float)int > -4.4 --> true 3000202375Srdivacky if (RHS.isNegative()) 3001202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); 3002202375Srdivacky break; 3003202375Srdivacky case ICmpInst::ICMP_SGT: 3004202375Srdivacky // (float)int > 4.4 --> int > 4 3005202375Srdivacky // (float)int > -4.4 --> int >= -4 3006202375Srdivacky if (RHS.isNegative()) 3007202375Srdivacky Pred = ICmpInst::ICMP_SGE; 3008202375Srdivacky break; 3009202375Srdivacky case ICmpInst::ICMP_UGE: 3010202375Srdivacky // (float)int >= -4.4 --> true 3011202375Srdivacky // (float)int >= 4.4 --> int > 4 3012239462Sdim if (RHS.isNegative()) 3013202375Srdivacky return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); 3014202375Srdivacky Pred = ICmpInst::ICMP_UGT; 3015202375Srdivacky break; 3016202375Srdivacky case ICmpInst::ICMP_SGE: 3017202375Srdivacky // (float)int >= -4.4 --> int >= -4 3018202375Srdivacky // (float)int >= 4.4 --> int > 4 3019202375Srdivacky if (!RHS.isNegative()) 3020202375Srdivacky Pred = ICmpInst::ICMP_SGT; 3021202375Srdivacky break; 3022202375Srdivacky } 3023202375Srdivacky } 3024202375Srdivacky } 3025202375Srdivacky 3026202375Srdivacky // Lower this FP comparison into an appropriate integer version of the 3027202375Srdivacky // comparison. 3028202375Srdivacky return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt); 3029202375Srdivacky} 3030202375Srdivacky 3031202375SrdivackyInstruction *InstCombiner::visitFCmpInst(FCmpInst &I) { 3032202375Srdivacky bool Changed = false; 3033226633Sdim 3034202375Srdivacky /// Orders the operands of the compare so that they are listed from most 3035202375Srdivacky /// complex to least complex. This puts constants before unary operators, 3036202375Srdivacky /// before binary operators. 3037202375Srdivacky if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) { 3038202375Srdivacky I.swapOperands(); 3039202375Srdivacky Changed = true; 3040202375Srdivacky } 3041202375Srdivacky 3042202375Srdivacky Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); 3043226633Sdim 3044202375Srdivacky if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, TD)) 3045202375Srdivacky return ReplaceInstUsesWith(I, V); 3046202375Srdivacky 3047202375Srdivacky // Simplify 'fcmp pred X, X' 3048202375Srdivacky if (Op0 == Op1) { 3049202375Srdivacky switch (I.getPredicate()) { 3050202375Srdivacky default: llvm_unreachable("Unknown predicate!"); 3051202375Srdivacky case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y) 3052202375Srdivacky case FCmpInst::FCMP_ULT: // True if unordered or less than 3053202375Srdivacky case FCmpInst::FCMP_UGT: // True if unordered or greater than 3054202375Srdivacky case FCmpInst::FCMP_UNE: // True if unordered or not equal 3055202375Srdivacky // Canonicalize these to be 'fcmp uno %X, 0.0'. 3056202375Srdivacky I.setPredicate(FCmpInst::FCMP_UNO); 3057202375Srdivacky I.setOperand(1, Constant::getNullValue(Op0->getType())); 3058202375Srdivacky return &I; 3059226633Sdim 3060202375Srdivacky case FCmpInst::FCMP_ORD: // True if ordered (no nans) 3061202375Srdivacky case FCmpInst::FCMP_OEQ: // True if ordered and equal 3062202375Srdivacky case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal 3063202375Srdivacky case FCmpInst::FCMP_OLE: // True if ordered and less than or equal 3064202375Srdivacky // Canonicalize these to be 'fcmp ord %X, 0.0'. 3065202375Srdivacky I.setPredicate(FCmpInst::FCMP_ORD); 3066202375Srdivacky I.setOperand(1, Constant::getNullValue(Op0->getType())); 3067202375Srdivacky return &I; 3068202375Srdivacky } 3069202375Srdivacky } 3070226633Sdim 3071202375Srdivacky // Handle fcmp with constant RHS 3072202375Srdivacky if (Constant *RHSC = dyn_cast<Constant>(Op1)) { 3073202375Srdivacky if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) 3074202375Srdivacky switch (LHSI->getOpcode()) { 3075221345Sdim case Instruction::FPExt: { 3076221345Sdim // fcmp (fpext x), C -> fcmp x, (fptrunc C) if fptrunc is lossless 3077221345Sdim FPExtInst *LHSExt = cast<FPExtInst>(LHSI); 3078221345Sdim ConstantFP *RHSF = dyn_cast<ConstantFP>(RHSC); 3079221345Sdim if (!RHSF) 3080221345Sdim break; 3081221345Sdim 3082221345Sdim const fltSemantics *Sem; 3083221345Sdim // FIXME: This shouldn't be here. 3084234353Sdim if (LHSExt->getSrcTy()->isHalfTy()) 3085234353Sdim Sem = &APFloat::IEEEhalf; 3086234353Sdim else if (LHSExt->getSrcTy()->isFloatTy()) 3087221345Sdim Sem = &APFloat::IEEEsingle; 3088221345Sdim else if (LHSExt->getSrcTy()->isDoubleTy()) 3089221345Sdim Sem = &APFloat::IEEEdouble; 3090221345Sdim else if (LHSExt->getSrcTy()->isFP128Ty()) 3091221345Sdim Sem = &APFloat::IEEEquad; 3092221345Sdim else if (LHSExt->getSrcTy()->isX86_FP80Ty()) 3093221345Sdim Sem = &APFloat::x87DoubleExtended; 3094243830Sdim else if (LHSExt->getSrcTy()->isPPC_FP128Ty()) 3095243830Sdim Sem = &APFloat::PPCDoubleDouble; 3096221345Sdim else 3097221345Sdim break; 3098221345Sdim 3099221345Sdim bool Lossy; 3100221345Sdim APFloat F = RHSF->getValueAPF(); 3101221345Sdim F.convert(*Sem, APFloat::rmNearestTiesToEven, &Lossy); 3102221345Sdim 3103226633Sdim // Avoid lossy conversions and denormals. Zero is a special case 3104226633Sdim // that's OK to convert. 3105226633Sdim APFloat Fabs = F; 3106226633Sdim Fabs.clearSign(); 3107221345Sdim if (!Lossy && 3108226633Sdim ((Fabs.compare(APFloat::getSmallestNormalized(*Sem)) != 3109226633Sdim APFloat::cmpLessThan) || Fabs.isZero())) 3110226633Sdim 3111221345Sdim return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0), 3112221345Sdim ConstantFP::get(RHSC->getContext(), F)); 3113221345Sdim break; 3114221345Sdim } 3115202375Srdivacky case Instruction::PHI: 3116202375Srdivacky // Only fold fcmp into the PHI if the phi and fcmp are in the same 3117202375Srdivacky // block. If in the same block, we're encouraging jump threading. If 3118202375Srdivacky // not, we are just pessimizing the code by making an i1 phi. 3119202375Srdivacky if (LHSI->getParent() == I.getParent()) 3120218893Sdim if (Instruction *NV = FoldOpIntoPhi(I)) 3121202375Srdivacky return NV; 3122202375Srdivacky break; 3123202375Srdivacky case Instruction::SIToFP: 3124202375Srdivacky case Instruction::UIToFP: 3125202375Srdivacky if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC)) 3126202375Srdivacky return NV; 3127202375Srdivacky break; 3128202375Srdivacky case Instruction::Select: { 3129202375Srdivacky // If either operand of the select is a constant, we can fold the 3130202375Srdivacky // comparison into the select arms, which will cause one to be 3131202375Srdivacky // constant folded and the select turned into a bitwise or. 3132202375Srdivacky Value *Op1 = 0, *Op2 = 0; 3133202375Srdivacky if (LHSI->hasOneUse()) { 3134202375Srdivacky if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) { 3135202375Srdivacky // Fold the known value into the constant operand. 3136202375Srdivacky Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); 3137202375Srdivacky // Insert a new FCmp of the other select operand. 3138202375Srdivacky Op2 = Builder->CreateFCmp(I.getPredicate(), 3139202375Srdivacky LHSI->getOperand(2), RHSC, I.getName()); 3140202375Srdivacky } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) { 3141202375Srdivacky // Fold the known value into the constant operand. 3142202375Srdivacky Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); 3143202375Srdivacky // Insert a new FCmp of the other select operand. 3144202375Srdivacky Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1), 3145202375Srdivacky RHSC, I.getName()); 3146202375Srdivacky } 3147202375Srdivacky } 3148202375Srdivacky 3149202375Srdivacky if (Op1) 3150202375Srdivacky return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); 3151202375Srdivacky break; 3152202375Srdivacky } 3153221345Sdim case Instruction::FSub: { 3154221345Sdim // fcmp pred (fneg x), C -> fcmp swap(pred) x, -C 3155221345Sdim Value *Op; 3156221345Sdim if (match(LHSI, m_FNeg(m_Value(Op)))) 3157221345Sdim return new FCmpInst(I.getSwappedPredicate(), Op, 3158221345Sdim ConstantExpr::getFNeg(RHSC)); 3159221345Sdim break; 3160221345Sdim } 3161204642Srdivacky case Instruction::Load: 3162204642Srdivacky if (GetElementPtrInst *GEP = 3163204642Srdivacky dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) { 3164204642Srdivacky if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) 3165204642Srdivacky if (GV->isConstant() && GV->hasDefinitiveInitializer() && 3166204642Srdivacky !cast<LoadInst>(LHSI)->isVolatile()) 3167204642Srdivacky if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) 3168204642Srdivacky return Res; 3169204642Srdivacky } 3170204642Srdivacky break; 3171243830Sdim case Instruction::Call: { 3172243830Sdim CallInst *CI = cast<CallInst>(LHSI); 3173243830Sdim LibFunc::Func Func; 3174243830Sdim // Various optimization for fabs compared with zero. 3175243830Sdim if (RHSC->isNullValue() && CI->getCalledFunction() && 3176243830Sdim TLI->getLibFunc(CI->getCalledFunction()->getName(), Func) && 3177243830Sdim TLI->has(Func)) { 3178243830Sdim if (Func == LibFunc::fabs || Func == LibFunc::fabsf || 3179243830Sdim Func == LibFunc::fabsl) { 3180243830Sdim switch (I.getPredicate()) { 3181243830Sdim default: break; 3182243830Sdim // fabs(x) < 0 --> false 3183243830Sdim case FCmpInst::FCMP_OLT: 3184243830Sdim return ReplaceInstUsesWith(I, Builder->getFalse()); 3185243830Sdim // fabs(x) > 0 --> x != 0 3186243830Sdim case FCmpInst::FCMP_OGT: 3187243830Sdim return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0), 3188243830Sdim RHSC); 3189243830Sdim // fabs(x) <= 0 --> x == 0 3190243830Sdim case FCmpInst::FCMP_OLE: 3191243830Sdim return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0), 3192243830Sdim RHSC); 3193243830Sdim // fabs(x) >= 0 --> !isnan(x) 3194243830Sdim case FCmpInst::FCMP_OGE: 3195243830Sdim return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0), 3196243830Sdim RHSC); 3197243830Sdim // fabs(x) == 0 --> x == 0 3198243830Sdim // fabs(x) != 0 --> x != 0 3199243830Sdim case FCmpInst::FCMP_OEQ: 3200243830Sdim case FCmpInst::FCMP_UEQ: 3201243830Sdim case FCmpInst::FCMP_ONE: 3202243830Sdim case FCmpInst::FCMP_UNE: 3203243830Sdim return new FCmpInst(I.getPredicate(), CI->getArgOperand(0), 3204243830Sdim RHSC); 3205243830Sdim } 3206243830Sdim } 3207243830Sdim } 3208202375Srdivacky } 3209243830Sdim } 3210202375Srdivacky } 3211202375Srdivacky 3212221345Sdim // fcmp pred (fneg x), (fneg y) -> fcmp swap(pred) x, y 3213221345Sdim Value *X, *Y; 3214221345Sdim if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_FNeg(m_Value(Y)))) 3215221345Sdim return new FCmpInst(I.getSwappedPredicate(), X, Y); 3216221345Sdim 3217221345Sdim // fcmp (fpext x), (fpext y) -> fcmp x, y 3218221345Sdim if (FPExtInst *LHSExt = dyn_cast<FPExtInst>(Op0)) 3219221345Sdim if (FPExtInst *RHSExt = dyn_cast<FPExtInst>(Op1)) 3220221345Sdim if (LHSExt->getSrcTy() == RHSExt->getSrcTy()) 3221221345Sdim return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0), 3222221345Sdim RHSExt->getOperand(0)); 3223221345Sdim 3224202375Srdivacky return Changed ? &I : 0; 3225202375Srdivacky} 3226