InstructionSimplify.cpp revision 223017
1111314Snyan//===- InstructionSimplify.cpp - Fold instruction operands ----------------===// 2111314Snyan// 3111314Snyan// The LLVM Compiler Infrastructure 4111314Snyan// 5111314Snyan// This file is distributed under the University of Illinois Open Source 6111314Snyan// License. See LICENSE.TXT for details. 7111314Snyan// 8111314Snyan//===----------------------------------------------------------------------===// 9111314Snyan// 10111314Snyan// This file implements routines for folding instructions into simpler forms 11111314Snyan// that do not require creating new instructions. This does constant folding 12111314Snyan// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either 13111314Snyan// returning a constant ("and i32 %x, 0" -> "0") or an already existing value 14111314Snyan// ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been 15144512Simp// simplified: This is usually true and assuming it simplifies the logic (if 16111314Snyan// they have not been simplified then results are correct but maybe suboptimal). 17111314Snyan// 18125234Snyan//===----------------------------------------------------------------------===// 19127520Snyan 20111314Snyan#define DEBUG_TYPE "instsimplify" 21111314Snyan#include "llvm/Operator.h" 22111314Snyan#include "llvm/ADT/Statistic.h" 23111314Snyan#include "llvm/Analysis/InstructionSimplify.h" 24111314Snyan#include "llvm/Analysis/ConstantFolding.h" 25111314Snyan#include "llvm/Analysis/Dominators.h" 26122755Snyan#include "llvm/Analysis/ValueTracking.h" 27122755Snyan#include "llvm/Support/ConstantRange.h" 28122755Snyan#include "llvm/Support/PatternMatch.h" 29122755Snyan#include "llvm/Support/ValueHandle.h" 30111314Snyan#include "llvm/Target/TargetData.h" 31111314Snyanusing namespace llvm; 32111314Snyanusing namespace llvm::PatternMatch; 33122056Snyan 34124795Snyanenum { RecursionLimit = 3 }; 35142783Snyan 36142783SnyanSTATISTIC(NumExpand, "Number of expansions"); 37142783SnyanSTATISTIC(NumFactor , "Number of factorizations"); 38142783SnyanSTATISTIC(NumReassoc, "Number of reassociations"); 39142783Snyan 40145743Snyanstatic Value *SimplifyAndInst(Value *, Value *, const TargetData *, 41145743Snyan const DominatorTree *, unsigned); 42145743Snyanstatic Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *, 43145743Snyan const DominatorTree *, unsigned); 44145743Snyanstatic Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *, 45111314Snyan const DominatorTree *, unsigned); 46111314Snyanstatic Value *SimplifyOrInst(Value *, Value *, const TargetData *, 47111314Snyan const DominatorTree *, unsigned); 48111314Snyanstatic Value *SimplifyXorInst(Value *, Value *, const TargetData *, 49111314Snyan const DominatorTree *, unsigned); 50111314Snyan 51111314Snyan/// ValueDominatesPHI - Does the given value dominate the specified phi node? 52111314Snyanstatic bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { 53111314Snyan Instruction *I = dyn_cast<Instruction>(V); 54111314Snyan if (!I) 55111314Snyan // Arguments and constants dominate all instructions. 56111314Snyan return true; 57111314Snyan 58111314Snyan // If we have a DominatorTree then do a precise test. 59111314Snyan if (DT) 60111314Snyan return DT->dominates(I, P); 61124795Snyan 62124795Snyan // Otherwise, if the instruction is in the entry block, and is not an invoke, 63124795Snyan // then it obviously dominates all phi nodes. 64124795Snyan if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() && 65111314Snyan !isa<InvokeInst>(I)) 66111314Snyan return true; 67111314Snyan 68111314Snyan return false; 69111314Snyan} 70111314Snyan 71111314Snyan/// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning 72111314Snyan/// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is 73111314Snyan/// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS. 74111314Snyan/// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)". 75124795Snyan/// Returns the simplified value, or null if no simplification was performed. 76124795Snyanstatic Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS, 77124795Snyan unsigned OpcToExpand, const TargetData *TD, 78127520Snyan const DominatorTree *DT, unsigned MaxRecurse) { 79111314Snyan Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand; 80111314Snyan // Recursion is always used, so bail out at once if we already hit the limit. 81111314Snyan if (!MaxRecurse--) 82125234Snyan return 0; 83137526Snyan 84137526Snyan // Check whether the expression has the form "(A op' B) op C". 85137526Snyan if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS)) 86137526Snyan if (Op0->getOpcode() == OpcodeToExpand) { 87137526Snyan // It does! Try turning it into "(A op C) op' (B op C)". 88124795Snyan Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS; 89127520Snyan // Do "A op C" and "B op C" both simplify? 90124795Snyan if (Value *L = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse)) 91111314Snyan if (Value *R = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) { 92111314Snyan // They do! Return "L op' R" if it simplifies or is already available. 93111314Snyan // If "L op' R" equals "A op' B" then "L op' R" is just the LHS. 94111314Snyan if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand) 95111314Snyan && L == B && R == A)) { 96111314Snyan ++NumExpand; 97111314Snyan return LHS; 98111314Snyan } 99111314Snyan // Otherwise return "L op' R" if it simplifies. 100125234Snyan if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT, 101111314Snyan MaxRecurse)) { 102111314Snyan ++NumExpand; 103111314Snyan return V; 104111314Snyan } 105111314Snyan } 106111314Snyan } 107111314Snyan 108111314Snyan // Check whether the expression has the form "A op (B op' C)". 109111314Snyan if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS)) 110111314Snyan if (Op1->getOpcode() == OpcodeToExpand) { 111111314Snyan // It does! Try turning it into "(A op B) op' (A op C)". 112111314Snyan Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1); 113111314Snyan // Do "A op B" and "A op C" both simplify? 114111314Snyan if (Value *L = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse)) 115111314Snyan if (Value *R = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse)) { 116111314Snyan // They do! Return "L op' R" if it simplifies or is already available. 117111314Snyan // If "L op' R" equals "B op' C" then "L op' R" is just the RHS. 118111314Snyan if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand) 119111314Snyan && L == C && R == B)) { 120125234Snyan ++NumExpand; 121111314Snyan return RHS; 122111314Snyan } 123111314Snyan // Otherwise return "L op' R" if it simplifies. 124111314Snyan if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT, 125111314Snyan MaxRecurse)) { 126111314Snyan ++NumExpand; 127111314Snyan return V; 128111314Snyan } 129111314Snyan } 130111314Snyan } 131111314Snyan 132111314Snyan return 0; 133111314Snyan} 134111314Snyan 135111314Snyan/// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term 136111314Snyan/// using the operation OpCodeToExtract. For example, when Opcode is Add and 137111314Snyan/// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)". 138111314Snyan/// Returns the simplified value, or null if no simplification was performed. 139111314Snyanstatic Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS, 140111314Snyan unsigned OpcToExtract, const TargetData *TD, 141111314Snyan const DominatorTree *DT, unsigned MaxRecurse) { 142111314Snyan Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract; 143111314Snyan // Recursion is always used, so bail out at once if we already hit the limit. 144111314Snyan if (!MaxRecurse--) 145111314Snyan return 0; 146111314Snyan 147111314Snyan BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 148111314Snyan BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 149124795Snyan 150111314Snyan if (!Op0 || Op0->getOpcode() != OpcodeToExtract || 151111314Snyan !Op1 || Op1->getOpcode() != OpcodeToExtract) 152111314Snyan return 0; 153111314Snyan 154124795Snyan // The expression has the form "(A op' B) op (C op' D)". 155124795Snyan Value *A = Op0->getOperand(0), *B = Op0->getOperand(1); 156111314Snyan Value *C = Op1->getOperand(0), *D = Op1->getOperand(1); 157111314Snyan 158111314Snyan // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)". 159111314Snyan // Does the instruction have the form "(A op' B) op (A op' D)" or, in the 160111314Snyan // commutative case, "(A op' B) op (C op' A)"? 161111314Snyan if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) { 162111314Snyan Value *DD = A == C ? D : C; 163111314Snyan // Form "A op' (B op DD)" if it simplifies completely. 164111314Snyan // Does "B op DD" simplify? 165111314Snyan if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, DT, MaxRecurse)) { 166111314Snyan // It does! Return "A op' V" if it simplifies or is already available. 167111314Snyan // If V equals B then "A op' V" is just the LHS. If V equals DD then 168111314Snyan // "A op' V" is just the RHS. 169111314Snyan if (V == B || V == DD) { 170111314Snyan ++NumFactor; 171124795Snyan return V == B ? LHS : RHS; 172111314Snyan } 173111314Snyan // Otherwise return "A op' V" if it simplifies. 174111314Snyan if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, DT, MaxRecurse)) { 175111314Snyan ++NumFactor; 176111314Snyan return W; 177111314Snyan } 178111314Snyan } 179111314Snyan } 180111314Snyan 181111314Snyan // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)". 182111314Snyan // Does the instruction have the form "(A op' B) op (C op' B)" or, in the 183111314Snyan // commutative case, "(A op' B) op (B op' D)"? 184111314Snyan if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) { 185111314Snyan Value *CC = B == D ? C : D; 186111314Snyan // Form "(A op CC) op' B" if it simplifies completely.. 187111314Snyan // Does "A op CC" simplify? 188124795Snyan if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, DT, MaxRecurse)) { 189111314Snyan // It does! Return "V op' B" if it simplifies or is already available. 190111314Snyan // If V equals A then "V op' B" is just the LHS. If V equals CC then 191111314Snyan // "V op' B" is just the RHS. 192111314Snyan if (V == A || V == CC) { 193111314Snyan ++NumFactor; 194111314Snyan return V == A ? LHS : RHS; 195111314Snyan } 196111314Snyan // Otherwise return "V op' B" if it simplifies. 197124408Snyan if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, DT, MaxRecurse)) { 198124408Snyan ++NumFactor; 199111314Snyan return W; 200111314Snyan } 201111314Snyan } 202111314Snyan } 203111314Snyan 204111314Snyan return 0; 205111314Snyan} 206111314Snyan 207111314Snyan/// SimplifyAssociativeBinOp - Generic simplifications for associative binary 208111314Snyan/// operations. Returns the simpler value, or null if none was found. 209123984Sbdestatic Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS, 210123984Sbde const TargetData *TD, 211123984Sbde const DominatorTree *DT, 212123984Sbde unsigned MaxRecurse) { 213111314Snyan Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc; 214111314Snyan assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); 215123984Sbde 216123984Sbde // Recursion is always used, so bail out at once if we already hit the limit. 217111314Snyan if (!MaxRecurse--) 218111314Snyan return 0; 219111314Snyan 220111314Snyan BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); 221111314Snyan BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); 222111314Snyan 223111314Snyan // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. 224111314Snyan if (Op0 && Op0->getOpcode() == Opcode) { 225111314Snyan Value *A = Op0->getOperand(0); 226124795Snyan Value *B = Op0->getOperand(1); 227111314Snyan Value *C = RHS; 228111314Snyan 229111314Snyan // Does "B op C" simplify? 230111314Snyan if (Value *V = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) { 231111314Snyan // It does! Return "A op V" if it simplifies or is already available. 232111314Snyan // If V equals B then "A op V" is just the LHS. 233111314Snyan if (V == B) return LHS; 234111314Snyan // Otherwise return "A op V" if it simplifies. 235111314Snyan if (Value *W = SimplifyBinOp(Opcode, A, V, TD, DT, MaxRecurse)) { 236111314Snyan ++NumReassoc; 237111314Snyan return W; 238111314Snyan } 239111314Snyan } 240111314Snyan } 241111314Snyan 242111314Snyan // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. 243111314Snyan if (Op1 && Op1->getOpcode() == Opcode) { 244111314Snyan Value *A = LHS; 245111314Snyan Value *B = Op1->getOperand(0); 246111314Snyan Value *C = Op1->getOperand(1); 247111314Snyan 248111314Snyan // Does "A op B" simplify? 249111314Snyan if (Value *V = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse)) { 250111314Snyan // It does! Return "V op C" if it simplifies or is already available. 251111314Snyan // If V equals B then "V op C" is just the RHS. 252111314Snyan if (V == B) return RHS; 253111314Snyan // Otherwise return "V op C" if it simplifies. 254111314Snyan if (Value *W = SimplifyBinOp(Opcode, V, C, TD, DT, MaxRecurse)) { 255111314Snyan ++NumReassoc; 256111314Snyan return W; 257111314Snyan } 258111314Snyan } 259111314Snyan } 260111314Snyan 261111314Snyan // The remaining transforms require commutativity as well as associativity. 262111314Snyan if (!Instruction::isCommutative(Opcode)) 263111314Snyan return 0; 264111314Snyan 265111314Snyan // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. 266111314Snyan if (Op0 && Op0->getOpcode() == Opcode) { 267111314Snyan Value *A = Op0->getOperand(0); 268111314Snyan Value *B = Op0->getOperand(1); 269111314Snyan Value *C = RHS; 270111314Snyan 271111314Snyan // Does "C op A" simplify? 272111314Snyan if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) { 273111314Snyan // It does! Return "V op B" if it simplifies or is already available. 274111314Snyan // If V equals A then "V op B" is just the LHS. 275111314Snyan if (V == A) return LHS; 276111314Snyan // Otherwise return "V op B" if it simplifies. 277111314Snyan if (Value *W = SimplifyBinOp(Opcode, V, B, TD, DT, MaxRecurse)) { 278111314Snyan ++NumReassoc; 279111314Snyan return W; 280111314Snyan } 281111314Snyan } 282111314Snyan } 283111314Snyan 284111314Snyan // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. 285111314Snyan if (Op1 && Op1->getOpcode() == Opcode) { 286111314Snyan Value *A = LHS; 287111314Snyan Value *B = Op1->getOperand(0); 288111314Snyan Value *C = Op1->getOperand(1); 289111314Snyan 290111314Snyan // Does "C op A" simplify? 291111314Snyan if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) { 292111314Snyan // It does! Return "B op V" if it simplifies or is already available. 293111314Snyan // If V equals C then "B op V" is just the RHS. 294131815Snyan if (V == C) return RHS; 295111314Snyan // Otherwise return "B op V" if it simplifies. 296111314Snyan if (Value *W = SimplifyBinOp(Opcode, B, V, TD, DT, MaxRecurse)) { 297111314Snyan ++NumReassoc; 298111314Snyan return W; 299111314Snyan } 300111314Snyan } 301111314Snyan } 302111314Snyan 303111314Snyan return 0; 304111314Snyan} 305111314Snyan 306111314Snyan/// ThreadBinOpOverSelect - In the case of a binary operation with a select 307111314Snyan/// instruction as an operand, try to simplify the binop by seeing whether 308111314Snyan/// evaluating it on both branches of the select results in the same value. 309111314Snyan/// Returns the common value if so, otherwise returns null. 310140371Srustatic Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS, 311111314Snyan const TargetData *TD, 312111314Snyan const DominatorTree *DT, 313111314Snyan unsigned MaxRecurse) { 314111314Snyan // Recursion is always used, so bail out at once if we already hit the limit. 315111314Snyan if (!MaxRecurse--) 316111314Snyan return 0; 317111314Snyan 318111314Snyan SelectInst *SI; 319124795Snyan if (isa<SelectInst>(LHS)) { 320124795Snyan SI = cast<SelectInst>(LHS); 321124795Snyan } else { 322111314Snyan assert(isa<SelectInst>(RHS) && "No select instruction operand!"); 323111314Snyan SI = cast<SelectInst>(RHS); 324111314Snyan } 325124795Snyan 326111314Snyan // Evaluate the BinOp on the true and false branches of the select. 327111314Snyan Value *TV; 328126708Snyan Value *FV; 329111314Snyan if (SI == LHS) { 330111314Snyan TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, DT, MaxRecurse); 331145183Snyan FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, DT, MaxRecurse); 332145183Snyan } else { 333145183Snyan TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, DT, MaxRecurse); 334145183Snyan FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, DT, MaxRecurse); 335145183Snyan } 336148235Snyan 337145183Snyan // If they simplified to the same value, then return the common value. 338145183Snyan // If they both failed to simplify then return null. 339145183Snyan if (TV == FV) 340111314Snyan return TV; 341111314Snyan 342111314Snyan // If one branch simplified to undef, return the other one. 343111314Snyan if (TV && isa<UndefValue>(TV)) 344111314Snyan return FV; 345111314Snyan if (FV && isa<UndefValue>(FV)) 346111314Snyan return TV; 347111314Snyan 348111314Snyan // If applying the operation did not change the true and false select values, 349111314Snyan // then the result of the binop is the select itself. 350111314Snyan if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) 351111314Snyan return SI; 352111314Snyan 353111314Snyan // If one branch simplified and the other did not, and the simplified 354111314Snyan // value is equal to the unsimplified one, return the simplified value. 355129384Snyan // For example, select (cond, X, X & Z) & Z -> X & Z. 356129384Snyan if ((FV && !TV) || (TV && !FV)) { 357129384Snyan // Check that the simplified value has the form "X op Y" where "op" is the 358129384Snyan // same as the original operation. 359111314Snyan Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); 360125234Snyan if (Simplified && Simplified->getOpcode() == Opcode) { 361111314Snyan // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". 362111314Snyan // We already know that "op" is the same as for the simplified value. See 363111314Snyan // if the operands match too. If so, return the simplified value. 364111314Snyan Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); 365111314Snyan Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; 366126708Snyan Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; 367111314Snyan if (Simplified->getOperand(0) == UnsimplifiedLHS && 368126708Snyan Simplified->getOperand(1) == UnsimplifiedRHS) 369126708Snyan return Simplified; 370111314Snyan if (Simplified->isCommutative() && 371111314Snyan Simplified->getOperand(1) == UnsimplifiedLHS && 372111314Snyan Simplified->getOperand(0) == UnsimplifiedRHS) 373111314Snyan return Simplified; 374111314Snyan } 375129384Snyan } 376111314Snyan 377111314Snyan return 0; 378111314Snyan} 379111314Snyan 380111314Snyan/// ThreadCmpOverSelect - In the case of a comparison with a select instruction, 381111314Snyan/// try to simplify the comparison by seeing whether both branches of the select 382112840Smdodd/// result in the same value. Returns the common value if so, otherwise returns 383112840Smdodd/// null. 384112840Smdoddstatic Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, 385112840Smdodd Value *RHS, const TargetData *TD, 386112840Smdodd const DominatorTree *DT, 387111314Snyan unsigned MaxRecurse) { 388111314Snyan // Recursion is always used, so bail out at once if we already hit the limit. 389111314Snyan if (!MaxRecurse--) 390111314Snyan return 0; 391111314Snyan 392111314Snyan // Make sure the select is on the LHS. 393111314Snyan if (!isa<SelectInst>(LHS)) { 394111314Snyan std::swap(LHS, RHS); 395111314Snyan Pred = CmpInst::getSwappedPredicate(Pred); 396111314Snyan } 397111314Snyan assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); 398111314Snyan SelectInst *SI = cast<SelectInst>(LHS); 399111314Snyan 400111314Snyan // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. 401111314Snyan // Does "cmp TV, RHS" simplify? 402111314Snyan if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT, 403111314Snyan MaxRecurse)) { 404111314Snyan // It does! Does "cmp FV, RHS" simplify? 405125234Snyan if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT, 406111314Snyan MaxRecurse)) { 407125234Snyan // It does! If they simplified to the same value, then use it as the 408111314Snyan // result of the original comparison. 409111314Snyan if (TCmp == FCmp) 410111314Snyan return TCmp; 411111314Snyan Value *Cond = SI->getCondition(); 412111314Snyan // If the false value simplified to false, then the result of the compare 413111314Snyan // is equal to "Cond && TCmp". This also catches the case when the false 414111314Snyan // value simplified to false and the true value to true, returning "Cond". 415126708Snyan if (match(FCmp, m_Zero())) 416126708Snyan if (Value *V = SimplifyAndInst(Cond, TCmp, TD, DT, MaxRecurse)) 417126708Snyan return V; 418111314Snyan // If the true value simplified to true, then the result of the compare 419111314Snyan // is equal to "Cond || FCmp". 420117918Snyan if (match(TCmp, m_One())) 421117918Snyan if (Value *V = SimplifyOrInst(Cond, FCmp, TD, DT, MaxRecurse)) 422117918Snyan return V; 423117918Snyan // Finally, if the false value simplified to true and the true value to 424142783Snyan // false, then the result of the compare is equal to "!Cond". 425142783Snyan if (match(FCmp, m_One()) && match(TCmp, m_Zero())) 426117918Snyan if (Value *V = 427117918Snyan SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()), 428117918Snyan TD, DT, MaxRecurse)) 429117918Snyan return V; 430111314Snyan } 431111314Snyan } 432111314Snyan 433111314Snyan return 0; 434124795Snyan} 435111314Snyan 436111314Snyan/// ThreadBinOpOverPHI - In the case of a binary operation with an operand that 437111314Snyan/// is a PHI instruction, try to simplify the binop by seeing whether evaluating 438111314Snyan/// it on the incoming phi values yields the same result for every value. If so 439111314Snyan/// returns the common value, otherwise returns null. 440111314Snyanstatic Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS, 441111314Snyan const TargetData *TD, const DominatorTree *DT, 442111314Snyan unsigned MaxRecurse) { 443111314Snyan // Recursion is always used, so bail out at once if we already hit the limit. 444111314Snyan if (!MaxRecurse--) 445128876Sbde return 0; 446127945Snyan 447111314Snyan PHINode *PI; 448111314Snyan if (isa<PHINode>(LHS)) { 449111314Snyan PI = cast<PHINode>(LHS); 450111314Snyan // Bail out if RHS and the phi may be mutually interdependent due to a loop. 451111314Snyan if (!ValueDominatesPHI(RHS, PI, DT)) 452111314Snyan return 0; 453111314Snyan } else { 454111314Snyan assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); 455111314Snyan PI = cast<PHINode>(RHS); 456124795Snyan // Bail out if LHS and the phi may be mutually interdependent due to a loop. 457124795Snyan if (!ValueDominatesPHI(LHS, PI, DT)) 458124795Snyan return 0; 459128221Simp } 460128221Simp 461128221Simp // Evaluate the BinOp on the incoming phi values. 462128221Simp Value *CommonValue = 0; 463128221Simp for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) { 464128221Simp Value *Incoming = PI->getIncomingValue(i); 465128221Simp // If the incoming value is the phi node itself, it can safely be skipped. 466111314Snyan if (Incoming == PI) continue; 467111314Snyan Value *V = PI == LHS ? 468111314Snyan SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) : 469111314Snyan SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, MaxRecurse); 470111314Snyan // If the operation failed to simplify, or simplified to a different value 471111314Snyan // to previously, then give up. 472111314Snyan if (!V || (CommonValue && V != CommonValue)) 473111314Snyan return 0; 474111314Snyan CommonValue = V; 475111314Snyan } 476111314Snyan 477111314Snyan return CommonValue; 478111314Snyan} 479111314Snyan 480111314Snyan/// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try 481111314Snyan/// try to simplify the comparison by seeing whether comparing with all of the 482111314Snyan/// incoming phi values yields the same result every time. If so returns the 483111314Snyan/// common result, otherwise returns null. 484111314Snyanstatic Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, 485111314Snyan const TargetData *TD, const DominatorTree *DT, 486111314Snyan unsigned MaxRecurse) { 487111314Snyan // Recursion is always used, so bail out at once if we already hit the limit. 488132155Sdes if (!MaxRecurse--) 489111314Snyan return 0; 490111314Snyan 491111314Snyan // Make sure the phi is on the LHS. 492111314Snyan if (!isa<PHINode>(LHS)) { 493111314Snyan std::swap(LHS, RHS); 494111314Snyan Pred = CmpInst::getSwappedPredicate(Pred); 495111314Snyan } 496111314Snyan assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); 497111314Snyan PHINode *PI = cast<PHINode>(LHS); 498111314Snyan 499111314Snyan // Bail out if RHS and the phi may be mutually interdependent due to a loop. 500111314Snyan if (!ValueDominatesPHI(RHS, PI, DT)) 501111314Snyan return 0; 502125234Snyan 503111314Snyan // Evaluate the BinOp on the incoming phi values. 504111314Snyan Value *CommonValue = 0; 505111314Snyan for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) { 506111314Snyan Value *Incoming = PI->getIncomingValue(i); 507111314Snyan // If the incoming value is the phi node itself, it can safely be skipped. 508111314Snyan if (Incoming == PI) continue; 509111314Snyan Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse); 510111314Snyan // If the operation failed to simplify, or simplified to a different value 511111314Snyan // to previously, then give up. 512111314Snyan if (!V || (CommonValue && V != CommonValue)) 513125234Snyan return 0; 514111314Snyan CommonValue = V; 515111314Snyan } 516111314Snyan 517111314Snyan return CommonValue; 518111314Snyan} 519111314Snyan 520111314Snyan/// SimplifyAddInst - Given operands for an Add, see if we can 521111314Snyan/// fold the result. If not, this returns null. 522111314Snyanstatic Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 523111314Snyan const TargetData *TD, const DominatorTree *DT, 524111314Snyan unsigned MaxRecurse) { 525111314Snyan if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 526111314Snyan if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 527111314Snyan Constant *Ops[] = { CLHS, CRHS }; 528111314Snyan return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), 529111314Snyan Ops, 2, TD); 530111314Snyan } 531126708Snyan 532111314Snyan // Canonicalize the constant to the RHS. 533111314Snyan std::swap(Op0, Op1); 534111314Snyan } 535111314Snyan 536111314Snyan // X + undef -> undef 537111314Snyan if (match(Op1, m_Undef())) 538111314Snyan return Op1; 539126708Snyan 540111314Snyan // X + 0 -> X 541111314Snyan if (match(Op1, m_Zero())) 542111314Snyan return Op0; 543111314Snyan 544111314Snyan // X + (Y - X) -> Y 545126708Snyan // (Y - X) + X -> Y 546111314Snyan // Eg: X + -X -> 0 547111314Snyan Value *Y = 0; 548111314Snyan if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || 549111314Snyan match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) 550111314Snyan return Y; 551134634Sru 552111314Snyan // X + ~X -> -1 since ~X = -X-1 553111314Snyan if (match(Op0, m_Not(m_Specific(Op1))) || 554111314Snyan match(Op1, m_Not(m_Specific(Op0)))) 555111314Snyan return Constant::getAllOnesValue(Op0->getType()); 556111314Snyan 557126708Snyan /// i1 add -> xor. 558111314Snyan if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 559111314Snyan if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1)) 560125234Snyan return V; 561111314Snyan 562111314Snyan // Try some generic simplifications for associative operations. 563111314Snyan if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT, 564126708Snyan MaxRecurse)) 565111314Snyan return V; 566111314Snyan 567111314Snyan // Mul distributes over Add. Try some generic simplifications based on this. 568111314Snyan if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul, 569126708Snyan TD, DT, MaxRecurse)) 570111314Snyan return V; 571111314Snyan 572111314Snyan // Threading Add over selects and phi nodes is pointless, so don't bother. 573111314Snyan // Threading over the select in "A + select(cond, B, C)" means evaluating 574111314Snyan // "A+B" and "A+C" and seeing if they are equal; but they are equal if and 575134634Sru // only if B and C are equal. If B and C are equal then (since we assume 576111314Snyan // that operands have already been simplified) "select(cond, B, C)" should 577111314Snyan // have been simplified to the common value of B and C already. Analysing 578134634Sru // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly 579111314Snyan // for threading over phi nodes. 580111314Snyan 581134634Sru return 0; 582111314Snyan} 583111314Snyan 584111314SnyanValue *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 585111314Snyan const TargetData *TD, const DominatorTree *DT) { 586111314Snyan return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit); 587134634Sru} 588142783Snyan 589111314Snyan/// SimplifySubInst - Given operands for a Sub, see if we can 590111314Snyan/// fold the result. If not, this returns null. 591134634Srustatic Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 592111314Snyan const TargetData *TD, const DominatorTree *DT, 593111314Snyan unsigned MaxRecurse) { 594111314Snyan if (Constant *CLHS = dyn_cast<Constant>(Op0)) 595111314Snyan if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 596111314Snyan Constant *Ops[] = { CLHS, CRHS }; 597134634Sru return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(), 598142783Snyan Ops, 2, TD); 599111314Snyan } 600111314Snyan 601134634Sru // X - undef -> undef 602134634Sru // undef - X -> undef 603111314Snyan if (match(Op0, m_Undef()) || match(Op1, m_Undef())) 604111314Snyan return UndefValue::get(Op0->getType()); 605134634Sru 606134634Sru // X - 0 -> X 607111314Snyan if (match(Op1, m_Zero())) 608111314Snyan return Op0; 609111314Snyan 610111314Snyan // X - X -> 0 611111314Snyan if (Op0 == Op1) 612111314Snyan return Constant::getNullValue(Op0->getType()); 613111314Snyan 614134634Sru // (X*2) - X -> X 615134634Sru // (X<<1) - X -> X 616111314Snyan Value *X = 0; 617111314Snyan if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) || 618134634Sru match(Op0, m_Shl(m_Specific(Op1), m_One()))) 619142783Snyan return Op1; 620111314Snyan 621111314Snyan // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. 622134634Sru // For example, (X + Y) - Y -> X; (Y + X) - Y -> X 623111314Snyan Value *Y = 0, *Z = Op1; 624111314Snyan if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z 625111314Snyan // See if "V === Y - Z" simplifies. 626111314Snyan if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, DT, MaxRecurse-1)) 627111314Snyan // It does! Now see if "X + V" simplifies. 628124795Snyan if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, DT, 629111314Snyan MaxRecurse-1)) { 630111314Snyan // It does, we successfully reassociated! 631111314Snyan ++NumReassoc; 632111314Snyan return W; 633111314Snyan } 634111314Snyan // See if "V === X - Z" simplifies. 635111314Snyan if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1)) 636111314Snyan // It does! Now see if "Y + V" simplifies. 637111314Snyan if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, DT, 638111314Snyan MaxRecurse-1)) { 639111314Snyan // It does, we successfully reassociated! 640111314Snyan ++NumReassoc; 641111314Snyan return W; 642111314Snyan } 643111314Snyan } 644111314Snyan 645111314Snyan // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. 646111314Snyan // For example, X - (X + 1) -> -1 647111314Snyan X = Op0; 648111314Snyan if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) 649111314Snyan // See if "V === X - Y" simplifies. 650111314Snyan if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, DT, MaxRecurse-1)) 651111314Snyan // It does! Now see if "V - Z" simplifies. 652111314Snyan if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, DT, 653111314Snyan MaxRecurse-1)) { 654111314Snyan // It does, we successfully reassociated! 655111314Snyan ++NumReassoc; 656111314Snyan return W; 657111314Snyan } 658111314Snyan // See if "V === X - Z" simplifies. 659111314Snyan if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1)) 660111314Snyan // It does! Now see if "V - Y" simplifies. 661111314Snyan if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, DT, 662111314Snyan MaxRecurse-1)) { 663111314Snyan // It does, we successfully reassociated! 664111314Snyan ++NumReassoc; 665111314Snyan return W; 666111314Snyan } 667111314Snyan } 668111314Snyan 669111314Snyan // Z - (X - Y) -> (Z - X) + Y if everything simplifies. 670111314Snyan // For example, X - (X - Y) -> Y. 671111314Snyan Z = Op0; 672125234Snyan if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) 673125234Snyan // See if "V === Z - X" simplifies. 674111314Snyan if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, DT, MaxRecurse-1)) 675111314Snyan // It does! Now see if "V + Y" simplifies. 676111314Snyan if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, DT, 677125234Snyan MaxRecurse-1)) { 678111314Snyan // It does, we successfully reassociated! 679111314Snyan ++NumReassoc; 680111314Snyan return W; 681111314Snyan } 682125234Snyan 683125234Snyan // Mul distributes over Sub. Try some generic simplifications based on this. 684111314Snyan if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul, 685111314Snyan TD, DT, MaxRecurse)) 686111314Snyan return V; 687111314Snyan 688111314Snyan // i1 sub -> xor. 689111314Snyan if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 690111314Snyan if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1)) 691111314Snyan return V; 692111314Snyan 693130596Snyan // Threading Sub over selects and phi nodes is pointless, so don't bother. 694111314Snyan // Threading over the select in "A - select(cond, B, C)" means evaluating 695111314Snyan // "A-B" and "A-C" and seeing if they are equal; but they are equal if and 696111314Snyan // only if B and C are equal. If B and C are equal then (since we assume 697111314Snyan // that operands have already been simplified) "select(cond, B, C)" should 698111314Snyan // have been simplified to the common value of B and C already. Analysing 699111314Snyan // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly 700111314Snyan // for threading over phi nodes. 701111314Snyan 702111314Snyan return 0; 703111314Snyan} 704111314Snyan 705111314SnyanValue *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 706111314Snyan const TargetData *TD, const DominatorTree *DT) { 707111314Snyan return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit); 708111314Snyan} 709111314Snyan 710111314Snyan/// SimplifyMulInst - Given operands for a Mul, see if we can 711111314Snyan/// fold the result. If not, this returns null. 712111314Snyanstatic Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD, 713111314Snyan const DominatorTree *DT, unsigned MaxRecurse) { 714111314Snyan if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 715111314Snyan if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 716111314Snyan Constant *Ops[] = { CLHS, CRHS }; 717111314Snyan return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(), 718111314Snyan Ops, 2, TD); 719111314Snyan } 720111314Snyan 721111314Snyan // Canonicalize the constant to the RHS. 722111314Snyan std::swap(Op0, Op1); 723111314Snyan } 724111314Snyan 725111314Snyan // X * undef -> 0 726111314Snyan if (match(Op1, m_Undef())) 727111314Snyan return Constant::getNullValue(Op0->getType()); 728111314Snyan 729111314Snyan // X * 0 -> 0 730111314Snyan if (match(Op1, m_Zero())) 731111314Snyan return Op1; 732111314Snyan 733111314Snyan // X * 1 -> X 734111314Snyan if (match(Op1, m_One())) 735111314Snyan return Op0; 736111314Snyan 737111500Sobrien // (X / Y) * Y -> X if the division is exact. 738132960Snyan Value *X = 0, *Y = 0; 739132960Snyan if ((match(Op0, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y 740132960Snyan (match(Op1, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y) 741132960Snyan BinaryOperator *Div = cast<BinaryOperator>(Y == Op1 ? Op0 : Op1); 742111500Sobrien if (Div->isExact()) 743111500Sobrien return X; 744111500Sobrien } 745111500Sobrien 746111500Sobrien // i1 mul -> and. 747111500Sobrien if (MaxRecurse && Op0->getType()->isIntegerTy(1)) 748111500Sobrien if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1)) 749116382Snyan return V; 750116382Snyan 751111500Sobrien // Try some generic simplifications for associative operations. 752116382Snyan if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT, 753116382Snyan MaxRecurse)) 754116382Snyan return V; 755116382Snyan 756111500Sobrien // Mul distributes over Add. Try some generic simplifications based on this. 757111500Sobrien if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add, 758111500Sobrien TD, DT, MaxRecurse)) 759111500Sobrien return V; 760111500Sobrien 761111500Sobrien // If the operation is with the result of a select instruction, check whether 762111500Sobrien // operating on either branch of the select always yields the same value. 763111500Sobrien if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 764111500Sobrien if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT, 765111500Sobrien MaxRecurse)) 766125086Snyan return V; 767116382Snyan 768116382Snyan // If the operation is with the result of a phi instruction, check whether 769116382Snyan // operating on all incoming values of the phi always yields the same value. 770116382Snyan if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 771111500Sobrien if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT, 772111500Sobrien MaxRecurse)) 773111500Sobrien return V; 774116382Snyan 775116382Snyan return 0; 776116382Snyan} 777116382Snyan 778116382SnyanValue *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD, 779116382Snyan const DominatorTree *DT) { 780111582Sru return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit); 781111582Sru} 782111582Sru 783111582Sru/// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can 784111582Sru/// fold the result. If not, this returns null. 785111582Srustatic Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 786111582Sru const TargetData *TD, const DominatorTree *DT, 787111582Sru unsigned MaxRecurse) { 788111582Sru if (Constant *C0 = dyn_cast<Constant>(Op0)) { 789111582Sru if (Constant *C1 = dyn_cast<Constant>(Op1)) { 790111582Sru Constant *Ops[] = { C0, C1 }; 791111582Sru return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD); 792116382Snyan } 793116382Snyan } 794116382Snyan 795116382Snyan bool isSigned = Opcode == Instruction::SDiv; 796111582Sru 797111582Sru // X / undef -> undef 798111582Sru if (match(Op1, m_Undef())) 799116382Snyan return Op1; 800116382Snyan 801111582Sru // undef / X -> 0 802111582Sru if (match(Op0, m_Undef())) 803111582Sru return Constant::getNullValue(Op0->getType()); 804111582Sru 805111582Sru // 0 / X -> 0, we don't need to preserve faults! 806111582Sru if (match(Op0, m_Zero())) 807 return Op0; 808 809 // X / 1 -> X 810 if (match(Op1, m_One())) 811 return Op0; 812 813 if (Op0->getType()->isIntegerTy(1)) 814 // It can't be division by zero, hence it must be division by one. 815 return Op0; 816 817 // X / X -> 1 818 if (Op0 == Op1) 819 return ConstantInt::get(Op0->getType(), 1); 820 821 // (X * Y) / Y -> X if the multiplication does not overflow. 822 Value *X = 0, *Y = 0; 823 if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) { 824 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1 825 BinaryOperator *Mul = cast<BinaryOperator>(Op0); 826 // If the Mul knows it does not overflow, then we are good to go. 827 if ((isSigned && Mul->hasNoSignedWrap()) || 828 (!isSigned && Mul->hasNoUnsignedWrap())) 829 return X; 830 // If X has the form X = A / Y then X * Y cannot overflow. 831 if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X)) 832 if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y) 833 return X; 834 } 835 836 // (X rem Y) / Y -> 0 837 if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || 838 (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1))))) 839 return Constant::getNullValue(Op0->getType()); 840 841 // If the operation is with the result of a select instruction, check whether 842 // operating on either branch of the select always yields the same value. 843 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 844 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse)) 845 return V; 846 847 // If the operation is with the result of a phi instruction, check whether 848 // operating on all incoming values of the phi always yields the same value. 849 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 850 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse)) 851 return V; 852 853 return 0; 854} 855 856/// SimplifySDivInst - Given operands for an SDiv, see if we can 857/// fold the result. If not, this returns null. 858static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD, 859 const DominatorTree *DT, unsigned MaxRecurse) { 860 if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, DT, MaxRecurse)) 861 return V; 862 863 return 0; 864} 865 866Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD, 867 const DominatorTree *DT) { 868 return ::SimplifySDivInst(Op0, Op1, TD, DT, RecursionLimit); 869} 870 871/// SimplifyUDivInst - Given operands for a UDiv, see if we can 872/// fold the result. If not, this returns null. 873static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD, 874 const DominatorTree *DT, unsigned MaxRecurse) { 875 if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, DT, MaxRecurse)) 876 return V; 877 878 return 0; 879} 880 881Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD, 882 const DominatorTree *DT) { 883 return ::SimplifyUDivInst(Op0, Op1, TD, DT, RecursionLimit); 884} 885 886static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *, 887 const DominatorTree *, unsigned) { 888 // undef / X -> undef (the undef could be a snan). 889 if (match(Op0, m_Undef())) 890 return Op0; 891 892 // X / undef -> undef 893 if (match(Op1, m_Undef())) 894 return Op1; 895 896 return 0; 897} 898 899Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD, 900 const DominatorTree *DT) { 901 return ::SimplifyFDivInst(Op0, Op1, TD, DT, RecursionLimit); 902} 903 904/// SimplifyRem - Given operands for an SRem or URem, see if we can 905/// fold the result. If not, this returns null. 906static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, 907 const TargetData *TD, const DominatorTree *DT, 908 unsigned MaxRecurse) { 909 if (Constant *C0 = dyn_cast<Constant>(Op0)) { 910 if (Constant *C1 = dyn_cast<Constant>(Op1)) { 911 Constant *Ops[] = { C0, C1 }; 912 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD); 913 } 914 } 915 916 // X % undef -> undef 917 if (match(Op1, m_Undef())) 918 return Op1; 919 920 // undef % X -> 0 921 if (match(Op0, m_Undef())) 922 return Constant::getNullValue(Op0->getType()); 923 924 // 0 % X -> 0, we don't need to preserve faults! 925 if (match(Op0, m_Zero())) 926 return Op0; 927 928 // X % 0 -> undef, we don't need to preserve faults! 929 if (match(Op1, m_Zero())) 930 return UndefValue::get(Op0->getType()); 931 932 // X % 1 -> 0 933 if (match(Op1, m_One())) 934 return Constant::getNullValue(Op0->getType()); 935 936 if (Op0->getType()->isIntegerTy(1)) 937 // It can't be remainder by zero, hence it must be remainder by one. 938 return Constant::getNullValue(Op0->getType()); 939 940 // X % X -> 0 941 if (Op0 == Op1) 942 return Constant::getNullValue(Op0->getType()); 943 944 // If the operation is with the result of a select instruction, check whether 945 // operating on either branch of the select always yields the same value. 946 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 947 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse)) 948 return V; 949 950 // If the operation is with the result of a phi instruction, check whether 951 // operating on all incoming values of the phi always yields the same value. 952 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 953 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse)) 954 return V; 955 956 return 0; 957} 958 959/// SimplifySRemInst - Given operands for an SRem, see if we can 960/// fold the result. If not, this returns null. 961static Value *SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD, 962 const DominatorTree *DT, unsigned MaxRecurse) { 963 if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, TD, DT, MaxRecurse)) 964 return V; 965 966 return 0; 967} 968 969Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD, 970 const DominatorTree *DT) { 971 return ::SimplifySRemInst(Op0, Op1, TD, DT, RecursionLimit); 972} 973 974/// SimplifyURemInst - Given operands for a URem, see if we can 975/// fold the result. If not, this returns null. 976static Value *SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD, 977 const DominatorTree *DT, unsigned MaxRecurse) { 978 if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, TD, DT, MaxRecurse)) 979 return V; 980 981 return 0; 982} 983 984Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD, 985 const DominatorTree *DT) { 986 return ::SimplifyURemInst(Op0, Op1, TD, DT, RecursionLimit); 987} 988 989static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *, 990 const DominatorTree *, unsigned) { 991 // undef % X -> undef (the undef could be a snan). 992 if (match(Op0, m_Undef())) 993 return Op0; 994 995 // X % undef -> undef 996 if (match(Op1, m_Undef())) 997 return Op1; 998 999 return 0; 1000} 1001 1002Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD, 1003 const DominatorTree *DT) { 1004 return ::SimplifyFRemInst(Op0, Op1, TD, DT, RecursionLimit); 1005} 1006 1007/// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can 1008/// fold the result. If not, this returns null. 1009static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1, 1010 const TargetData *TD, const DominatorTree *DT, 1011 unsigned MaxRecurse) { 1012 if (Constant *C0 = dyn_cast<Constant>(Op0)) { 1013 if (Constant *C1 = dyn_cast<Constant>(Op1)) { 1014 Constant *Ops[] = { C0, C1 }; 1015 return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD); 1016 } 1017 } 1018 1019 // 0 shift by X -> 0 1020 if (match(Op0, m_Zero())) 1021 return Op0; 1022 1023 // X shift by 0 -> X 1024 if (match(Op1, m_Zero())) 1025 return Op0; 1026 1027 // X shift by undef -> undef because it may shift by the bitwidth. 1028 if (match(Op1, m_Undef())) 1029 return Op1; 1030 1031 // Shifting by the bitwidth or more is undefined. 1032 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) 1033 if (CI->getValue().getLimitedValue() >= 1034 Op0->getType()->getScalarSizeInBits()) 1035 return UndefValue::get(Op0->getType()); 1036 1037 // If the operation is with the result of a select instruction, check whether 1038 // operating on either branch of the select always yields the same value. 1039 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1040 if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse)) 1041 return V; 1042 1043 // If the operation is with the result of a phi instruction, check whether 1044 // operating on all incoming values of the phi always yields the same value. 1045 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1046 if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse)) 1047 return V; 1048 1049 return 0; 1050} 1051 1052/// SimplifyShlInst - Given operands for an Shl, see if we can 1053/// fold the result. If not, this returns null. 1054static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1055 const TargetData *TD, const DominatorTree *DT, 1056 unsigned MaxRecurse) { 1057 if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, DT, MaxRecurse)) 1058 return V; 1059 1060 // undef << X -> 0 1061 if (match(Op0, m_Undef())) 1062 return Constant::getNullValue(Op0->getType()); 1063 1064 // (X >> A) << A -> X 1065 Value *X; 1066 if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1))) && 1067 cast<PossiblyExactOperator>(Op0)->isExact()) 1068 return X; 1069 return 0; 1070} 1071 1072Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 1073 const TargetData *TD, const DominatorTree *DT) { 1074 return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit); 1075} 1076 1077/// SimplifyLShrInst - Given operands for an LShr, see if we can 1078/// fold the result. If not, this returns null. 1079static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1080 const TargetData *TD, const DominatorTree *DT, 1081 unsigned MaxRecurse) { 1082 if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, DT, MaxRecurse)) 1083 return V; 1084 1085 // undef >>l X -> 0 1086 if (match(Op0, m_Undef())) 1087 return Constant::getNullValue(Op0->getType()); 1088 1089 // (X << A) >> A -> X 1090 Value *X; 1091 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) && 1092 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap()) 1093 return X; 1094 1095 return 0; 1096} 1097 1098Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 1099 const TargetData *TD, const DominatorTree *DT) { 1100 return ::SimplifyLShrInst(Op0, Op1, isExact, TD, DT, RecursionLimit); 1101} 1102 1103/// SimplifyAShrInst - Given operands for an AShr, see if we can 1104/// fold the result. If not, this returns null. 1105static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1106 const TargetData *TD, const DominatorTree *DT, 1107 unsigned MaxRecurse) { 1108 if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, DT, MaxRecurse)) 1109 return V; 1110 1111 // all ones >>a X -> all ones 1112 if (match(Op0, m_AllOnes())) 1113 return Op0; 1114 1115 // undef >>a X -> all ones 1116 if (match(Op0, m_Undef())) 1117 return Constant::getAllOnesValue(Op0->getType()); 1118 1119 // (X << A) >> A -> X 1120 Value *X; 1121 if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) && 1122 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap()) 1123 return X; 1124 1125 return 0; 1126} 1127 1128Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 1129 const TargetData *TD, const DominatorTree *DT) { 1130 return ::SimplifyAShrInst(Op0, Op1, isExact, TD, DT, RecursionLimit); 1131} 1132 1133/// SimplifyAndInst - Given operands for an And, see if we can 1134/// fold the result. If not, this returns null. 1135static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD, 1136 const DominatorTree *DT, unsigned MaxRecurse) { 1137 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 1138 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 1139 Constant *Ops[] = { CLHS, CRHS }; 1140 return ConstantFoldInstOperands(Instruction::And, CLHS->getType(), 1141 Ops, 2, TD); 1142 } 1143 1144 // Canonicalize the constant to the RHS. 1145 std::swap(Op0, Op1); 1146 } 1147 1148 // X & undef -> 0 1149 if (match(Op1, m_Undef())) 1150 return Constant::getNullValue(Op0->getType()); 1151 1152 // X & X = X 1153 if (Op0 == Op1) 1154 return Op0; 1155 1156 // X & 0 = 0 1157 if (match(Op1, m_Zero())) 1158 return Op1; 1159 1160 // X & -1 = X 1161 if (match(Op1, m_AllOnes())) 1162 return Op0; 1163 1164 // A & ~A = ~A & A = 0 1165 if (match(Op0, m_Not(m_Specific(Op1))) || 1166 match(Op1, m_Not(m_Specific(Op0)))) 1167 return Constant::getNullValue(Op0->getType()); 1168 1169 // (A | ?) & A = A 1170 Value *A = 0, *B = 0; 1171 if (match(Op0, m_Or(m_Value(A), m_Value(B))) && 1172 (A == Op1 || B == Op1)) 1173 return Op1; 1174 1175 // A & (A | ?) = A 1176 if (match(Op1, m_Or(m_Value(A), m_Value(B))) && 1177 (A == Op0 || B == Op0)) 1178 return Op0; 1179 1180 // Try some generic simplifications for associative operations. 1181 if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT, 1182 MaxRecurse)) 1183 return V; 1184 1185 // And distributes over Or. Try some generic simplifications based on this. 1186 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or, 1187 TD, DT, MaxRecurse)) 1188 return V; 1189 1190 // And distributes over Xor. Try some generic simplifications based on this. 1191 if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor, 1192 TD, DT, MaxRecurse)) 1193 return V; 1194 1195 // Or distributes over And. Try some generic simplifications based on this. 1196 if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or, 1197 TD, DT, MaxRecurse)) 1198 return V; 1199 1200 // If the operation is with the result of a select instruction, check whether 1201 // operating on either branch of the select always yields the same value. 1202 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1203 if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT, 1204 MaxRecurse)) 1205 return V; 1206 1207 // If the operation is with the result of a phi instruction, check whether 1208 // operating on all incoming values of the phi always yields the same value. 1209 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1210 if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT, 1211 MaxRecurse)) 1212 return V; 1213 1214 return 0; 1215} 1216 1217Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD, 1218 const DominatorTree *DT) { 1219 return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit); 1220} 1221 1222/// SimplifyOrInst - Given operands for an Or, see if we can 1223/// fold the result. If not, this returns null. 1224static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD, 1225 const DominatorTree *DT, unsigned MaxRecurse) { 1226 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 1227 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 1228 Constant *Ops[] = { CLHS, CRHS }; 1229 return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(), 1230 Ops, 2, TD); 1231 } 1232 1233 // Canonicalize the constant to the RHS. 1234 std::swap(Op0, Op1); 1235 } 1236 1237 // X | undef -> -1 1238 if (match(Op1, m_Undef())) 1239 return Constant::getAllOnesValue(Op0->getType()); 1240 1241 // X | X = X 1242 if (Op0 == Op1) 1243 return Op0; 1244 1245 // X | 0 = X 1246 if (match(Op1, m_Zero())) 1247 return Op0; 1248 1249 // X | -1 = -1 1250 if (match(Op1, m_AllOnes())) 1251 return Op1; 1252 1253 // A | ~A = ~A | A = -1 1254 if (match(Op0, m_Not(m_Specific(Op1))) || 1255 match(Op1, m_Not(m_Specific(Op0)))) 1256 return Constant::getAllOnesValue(Op0->getType()); 1257 1258 // (A & ?) | A = A 1259 Value *A = 0, *B = 0; 1260 if (match(Op0, m_And(m_Value(A), m_Value(B))) && 1261 (A == Op1 || B == Op1)) 1262 return Op1; 1263 1264 // A | (A & ?) = A 1265 if (match(Op1, m_And(m_Value(A), m_Value(B))) && 1266 (A == Op0 || B == Op0)) 1267 return Op0; 1268 1269 // ~(A & ?) | A = -1 1270 if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) && 1271 (A == Op1 || B == Op1)) 1272 return Constant::getAllOnesValue(Op1->getType()); 1273 1274 // A | ~(A & ?) = -1 1275 if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) && 1276 (A == Op0 || B == Op0)) 1277 return Constant::getAllOnesValue(Op0->getType()); 1278 1279 // Try some generic simplifications for associative operations. 1280 if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT, 1281 MaxRecurse)) 1282 return V; 1283 1284 // Or distributes over And. Try some generic simplifications based on this. 1285 if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, 1286 TD, DT, MaxRecurse)) 1287 return V; 1288 1289 // And distributes over Or. Try some generic simplifications based on this. 1290 if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And, 1291 TD, DT, MaxRecurse)) 1292 return V; 1293 1294 // If the operation is with the result of a select instruction, check whether 1295 // operating on either branch of the select always yields the same value. 1296 if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) 1297 if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT, 1298 MaxRecurse)) 1299 return V; 1300 1301 // If the operation is with the result of a phi instruction, check whether 1302 // operating on all incoming values of the phi always yields the same value. 1303 if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) 1304 if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT, 1305 MaxRecurse)) 1306 return V; 1307 1308 return 0; 1309} 1310 1311Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD, 1312 const DominatorTree *DT) { 1313 return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit); 1314} 1315 1316/// SimplifyXorInst - Given operands for a Xor, see if we can 1317/// fold the result. If not, this returns null. 1318static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD, 1319 const DominatorTree *DT, unsigned MaxRecurse) { 1320 if (Constant *CLHS = dyn_cast<Constant>(Op0)) { 1321 if (Constant *CRHS = dyn_cast<Constant>(Op1)) { 1322 Constant *Ops[] = { CLHS, CRHS }; 1323 return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(), 1324 Ops, 2, TD); 1325 } 1326 1327 // Canonicalize the constant to the RHS. 1328 std::swap(Op0, Op1); 1329 } 1330 1331 // A ^ undef -> undef 1332 if (match(Op1, m_Undef())) 1333 return Op1; 1334 1335 // A ^ 0 = A 1336 if (match(Op1, m_Zero())) 1337 return Op0; 1338 1339 // A ^ A = 0 1340 if (Op0 == Op1) 1341 return Constant::getNullValue(Op0->getType()); 1342 1343 // A ^ ~A = ~A ^ A = -1 1344 if (match(Op0, m_Not(m_Specific(Op1))) || 1345 match(Op1, m_Not(m_Specific(Op0)))) 1346 return Constant::getAllOnesValue(Op0->getType()); 1347 1348 // Try some generic simplifications for associative operations. 1349 if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT, 1350 MaxRecurse)) 1351 return V; 1352 1353 // And distributes over Xor. Try some generic simplifications based on this. 1354 if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And, 1355 TD, DT, MaxRecurse)) 1356 return V; 1357 1358 // Threading Xor over selects and phi nodes is pointless, so don't bother. 1359 // Threading over the select in "A ^ select(cond, B, C)" means evaluating 1360 // "A^B" and "A^C" and seeing if they are equal; but they are equal if and 1361 // only if B and C are equal. If B and C are equal then (since we assume 1362 // that operands have already been simplified) "select(cond, B, C)" should 1363 // have been simplified to the common value of B and C already. Analysing 1364 // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly 1365 // for threading over phi nodes. 1366 1367 return 0; 1368} 1369 1370Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD, 1371 const DominatorTree *DT) { 1372 return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit); 1373} 1374 1375static const Type *GetCompareTy(Value *Op) { 1376 return CmpInst::makeCmpResultType(Op->getType()); 1377} 1378 1379/// ExtractEquivalentCondition - Rummage around inside V looking for something 1380/// equivalent to the comparison "LHS Pred RHS". Return such a value if found, 1381/// otherwise return null. Helper function for analyzing max/min idioms. 1382static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred, 1383 Value *LHS, Value *RHS) { 1384 SelectInst *SI = dyn_cast<SelectInst>(V); 1385 if (!SI) 1386 return 0; 1387 CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); 1388 if (!Cmp) 1389 return 0; 1390 Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); 1391 if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) 1392 return Cmp; 1393 if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && 1394 LHS == CmpRHS && RHS == CmpLHS) 1395 return Cmp; 1396 return 0; 1397} 1398 1399/// SimplifyICmpInst - Given operands for an ICmpInst, see if we can 1400/// fold the result. If not, this returns null. 1401static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 1402 const TargetData *TD, const DominatorTree *DT, 1403 unsigned MaxRecurse) { 1404 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 1405 assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); 1406 1407 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 1408 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 1409 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD); 1410 1411 // If we have a constant, make sure it is on the RHS. 1412 std::swap(LHS, RHS); 1413 Pred = CmpInst::getSwappedPredicate(Pred); 1414 } 1415 1416 const Type *ITy = GetCompareTy(LHS); // The return type. 1417 const Type *OpTy = LHS->getType(); // The operand type. 1418 1419 // icmp X, X -> true/false 1420 // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false 1421 // because X could be 0. 1422 if (LHS == RHS || isa<UndefValue>(RHS)) 1423 return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); 1424 1425 // Special case logic when the operands have i1 type. 1426 if (OpTy->isIntegerTy(1) || (OpTy->isVectorTy() && 1427 cast<VectorType>(OpTy)->getElementType()->isIntegerTy(1))) { 1428 switch (Pred) { 1429 default: break; 1430 case ICmpInst::ICMP_EQ: 1431 // X == 1 -> X 1432 if (match(RHS, m_One())) 1433 return LHS; 1434 break; 1435 case ICmpInst::ICMP_NE: 1436 // X != 0 -> X 1437 if (match(RHS, m_Zero())) 1438 return LHS; 1439 break; 1440 case ICmpInst::ICMP_UGT: 1441 // X >u 0 -> X 1442 if (match(RHS, m_Zero())) 1443 return LHS; 1444 break; 1445 case ICmpInst::ICMP_UGE: 1446 // X >=u 1 -> X 1447 if (match(RHS, m_One())) 1448 return LHS; 1449 break; 1450 case ICmpInst::ICMP_SLT: 1451 // X <s 0 -> X 1452 if (match(RHS, m_Zero())) 1453 return LHS; 1454 break; 1455 case ICmpInst::ICMP_SLE: 1456 // X <=s -1 -> X 1457 if (match(RHS, m_One())) 1458 return LHS; 1459 break; 1460 } 1461 } 1462 1463 // icmp <alloca*>, <global/alloca*/null> - Different stack variables have 1464 // different addresses, and what's more the address of a stack variable is 1465 // never null or equal to the address of a global. Note that generalizing 1466 // to the case where LHS is a global variable address or null is pointless, 1467 // since if both LHS and RHS are constants then we already constant folded 1468 // the compare, and if only one of them is then we moved it to RHS already. 1469 if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) || 1470 isa<ConstantPointerNull>(RHS))) 1471 // We already know that LHS != RHS. 1472 return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred)); 1473 1474 // If we are comparing with zero then try hard since this is a common case. 1475 if (match(RHS, m_Zero())) { 1476 bool LHSKnownNonNegative, LHSKnownNegative; 1477 switch (Pred) { 1478 default: 1479 assert(false && "Unknown ICmp predicate!"); 1480 case ICmpInst::ICMP_ULT: 1481 // getNullValue also works for vectors, unlike getFalse. 1482 return Constant::getNullValue(ITy); 1483 case ICmpInst::ICMP_UGE: 1484 // getAllOnesValue also works for vectors, unlike getTrue. 1485 return ConstantInt::getAllOnesValue(ITy); 1486 case ICmpInst::ICMP_EQ: 1487 case ICmpInst::ICMP_ULE: 1488 if (isKnownNonZero(LHS, TD)) 1489 return Constant::getNullValue(ITy); 1490 break; 1491 case ICmpInst::ICMP_NE: 1492 case ICmpInst::ICMP_UGT: 1493 if (isKnownNonZero(LHS, TD)) 1494 return ConstantInt::getAllOnesValue(ITy); 1495 break; 1496 case ICmpInst::ICMP_SLT: 1497 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD); 1498 if (LHSKnownNegative) 1499 return ConstantInt::getAllOnesValue(ITy); 1500 if (LHSKnownNonNegative) 1501 return Constant::getNullValue(ITy); 1502 break; 1503 case ICmpInst::ICMP_SLE: 1504 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD); 1505 if (LHSKnownNegative) 1506 return ConstantInt::getAllOnesValue(ITy); 1507 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD)) 1508 return Constant::getNullValue(ITy); 1509 break; 1510 case ICmpInst::ICMP_SGE: 1511 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD); 1512 if (LHSKnownNegative) 1513 return Constant::getNullValue(ITy); 1514 if (LHSKnownNonNegative) 1515 return ConstantInt::getAllOnesValue(ITy); 1516 break; 1517 case ICmpInst::ICMP_SGT: 1518 ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD); 1519 if (LHSKnownNegative) 1520 return Constant::getNullValue(ITy); 1521 if (LHSKnownNonNegative && isKnownNonZero(LHS, TD)) 1522 return ConstantInt::getAllOnesValue(ITy); 1523 break; 1524 } 1525 } 1526 1527 // See if we are doing a comparison with a constant integer. 1528 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 1529 // Rule out tautological comparisons (eg., ult 0 or uge 0). 1530 ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue()); 1531 if (RHS_CR.isEmptySet()) 1532 return ConstantInt::getFalse(CI->getContext()); 1533 if (RHS_CR.isFullSet()) 1534 return ConstantInt::getTrue(CI->getContext()); 1535 1536 // Many binary operators with constant RHS have easy to compute constant 1537 // range. Use them to check whether the comparison is a tautology. 1538 uint32_t Width = CI->getBitWidth(); 1539 APInt Lower = APInt(Width, 0); 1540 APInt Upper = APInt(Width, 0); 1541 ConstantInt *CI2; 1542 if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) { 1543 // 'urem x, CI2' produces [0, CI2). 1544 Upper = CI2->getValue(); 1545 } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) { 1546 // 'srem x, CI2' produces (-|CI2|, |CI2|). 1547 Upper = CI2->getValue().abs(); 1548 Lower = (-Upper) + 1; 1549 } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) { 1550 // 'udiv x, CI2' produces [0, UINT_MAX / CI2]. 1551 APInt NegOne = APInt::getAllOnesValue(Width); 1552 if (!CI2->isZero()) 1553 Upper = NegOne.udiv(CI2->getValue()) + 1; 1554 } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) { 1555 // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]. 1556 APInt IntMin = APInt::getSignedMinValue(Width); 1557 APInt IntMax = APInt::getSignedMaxValue(Width); 1558 APInt Val = CI2->getValue().abs(); 1559 if (!Val.isMinValue()) { 1560 Lower = IntMin.sdiv(Val); 1561 Upper = IntMax.sdiv(Val) + 1; 1562 } 1563 } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) { 1564 // 'lshr x, CI2' produces [0, UINT_MAX >> CI2]. 1565 APInt NegOne = APInt::getAllOnesValue(Width); 1566 if (CI2->getValue().ult(Width)) 1567 Upper = NegOne.lshr(CI2->getValue()) + 1; 1568 } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) { 1569 // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2]. 1570 APInt IntMin = APInt::getSignedMinValue(Width); 1571 APInt IntMax = APInt::getSignedMaxValue(Width); 1572 if (CI2->getValue().ult(Width)) { 1573 Lower = IntMin.ashr(CI2->getValue()); 1574 Upper = IntMax.ashr(CI2->getValue()) + 1; 1575 } 1576 } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) { 1577 // 'or x, CI2' produces [CI2, UINT_MAX]. 1578 Lower = CI2->getValue(); 1579 } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) { 1580 // 'and x, CI2' produces [0, CI2]. 1581 Upper = CI2->getValue() + 1; 1582 } 1583 if (Lower != Upper) { 1584 ConstantRange LHS_CR = ConstantRange(Lower, Upper); 1585 if (RHS_CR.contains(LHS_CR)) 1586 return ConstantInt::getTrue(RHS->getContext()); 1587 if (RHS_CR.inverse().contains(LHS_CR)) 1588 return ConstantInt::getFalse(RHS->getContext()); 1589 } 1590 } 1591 1592 // Compare of cast, for example (zext X) != 0 -> X != 0 1593 if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { 1594 Instruction *LI = cast<CastInst>(LHS); 1595 Value *SrcOp = LI->getOperand(0); 1596 const Type *SrcTy = SrcOp->getType(); 1597 const Type *DstTy = LI->getType(); 1598 1599 // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input 1600 // if the integer type is the same size as the pointer type. 1601 if (MaxRecurse && TD && isa<PtrToIntInst>(LI) && 1602 TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) { 1603 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 1604 // Transfer the cast to the constant. 1605 if (Value *V = SimplifyICmpInst(Pred, SrcOp, 1606 ConstantExpr::getIntToPtr(RHSC, SrcTy), 1607 TD, DT, MaxRecurse-1)) 1608 return V; 1609 } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { 1610 if (RI->getOperand(0)->getType() == SrcTy) 1611 // Compare without the cast. 1612 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 1613 TD, DT, MaxRecurse-1)) 1614 return V; 1615 } 1616 } 1617 1618 if (isa<ZExtInst>(LHS)) { 1619 // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the 1620 // same type. 1621 if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { 1622 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 1623 // Compare X and Y. Note that signed predicates become unsigned. 1624 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 1625 SrcOp, RI->getOperand(0), TD, DT, 1626 MaxRecurse-1)) 1627 return V; 1628 } 1629 // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended 1630 // too. If not, then try to deduce the result of the comparison. 1631 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 1632 // Compute the constant that would happen if we truncated to SrcTy then 1633 // reextended to DstTy. 1634 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 1635 Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy); 1636 1637 // If the re-extended constant didn't change then this is effectively 1638 // also a case of comparing two zero-extended values. 1639 if (RExt == CI && MaxRecurse) 1640 if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), 1641 SrcOp, Trunc, TD, DT, MaxRecurse-1)) 1642 return V; 1643 1644 // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit 1645 // there. Use this to work out the result of the comparison. 1646 if (RExt != CI) { 1647 switch (Pred) { 1648 default: 1649 assert(false && "Unknown ICmp predicate!"); 1650 // LHS <u RHS. 1651 case ICmpInst::ICMP_EQ: 1652 case ICmpInst::ICMP_UGT: 1653 case ICmpInst::ICMP_UGE: 1654 return ConstantInt::getFalse(CI->getContext()); 1655 1656 case ICmpInst::ICMP_NE: 1657 case ICmpInst::ICMP_ULT: 1658 case ICmpInst::ICMP_ULE: 1659 return ConstantInt::getTrue(CI->getContext()); 1660 1661 // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS 1662 // is non-negative then LHS <s RHS. 1663 case ICmpInst::ICMP_SGT: 1664 case ICmpInst::ICMP_SGE: 1665 return CI->getValue().isNegative() ? 1666 ConstantInt::getTrue(CI->getContext()) : 1667 ConstantInt::getFalse(CI->getContext()); 1668 1669 case ICmpInst::ICMP_SLT: 1670 case ICmpInst::ICMP_SLE: 1671 return CI->getValue().isNegative() ? 1672 ConstantInt::getFalse(CI->getContext()) : 1673 ConstantInt::getTrue(CI->getContext()); 1674 } 1675 } 1676 } 1677 } 1678 1679 if (isa<SExtInst>(LHS)) { 1680 // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the 1681 // same type. 1682 if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { 1683 if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) 1684 // Compare X and Y. Note that the predicate does not change. 1685 if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), 1686 TD, DT, MaxRecurse-1)) 1687 return V; 1688 } 1689 // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended 1690 // too. If not, then try to deduce the result of the comparison. 1691 else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { 1692 // Compute the constant that would happen if we truncated to SrcTy then 1693 // reextended to DstTy. 1694 Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); 1695 Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy); 1696 1697 // If the re-extended constant didn't change then this is effectively 1698 // also a case of comparing two sign-extended values. 1699 if (RExt == CI && MaxRecurse) 1700 if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, DT, 1701 MaxRecurse-1)) 1702 return V; 1703 1704 // Otherwise the upper bits of LHS are all equal, while RHS has varying 1705 // bits there. Use this to work out the result of the comparison. 1706 if (RExt != CI) { 1707 switch (Pred) { 1708 default: 1709 assert(false && "Unknown ICmp predicate!"); 1710 case ICmpInst::ICMP_EQ: 1711 return ConstantInt::getFalse(CI->getContext()); 1712 case ICmpInst::ICMP_NE: 1713 return ConstantInt::getTrue(CI->getContext()); 1714 1715 // If RHS is non-negative then LHS <s RHS. If RHS is negative then 1716 // LHS >s RHS. 1717 case ICmpInst::ICMP_SGT: 1718 case ICmpInst::ICMP_SGE: 1719 return CI->getValue().isNegative() ? 1720 ConstantInt::getTrue(CI->getContext()) : 1721 ConstantInt::getFalse(CI->getContext()); 1722 case ICmpInst::ICMP_SLT: 1723 case ICmpInst::ICMP_SLE: 1724 return CI->getValue().isNegative() ? 1725 ConstantInt::getFalse(CI->getContext()) : 1726 ConstantInt::getTrue(CI->getContext()); 1727 1728 // If LHS is non-negative then LHS <u RHS. If LHS is negative then 1729 // LHS >u RHS. 1730 case ICmpInst::ICMP_UGT: 1731 case ICmpInst::ICMP_UGE: 1732 // Comparison is true iff the LHS <s 0. 1733 if (MaxRecurse) 1734 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, 1735 Constant::getNullValue(SrcTy), 1736 TD, DT, MaxRecurse-1)) 1737 return V; 1738 break; 1739 case ICmpInst::ICMP_ULT: 1740 case ICmpInst::ICMP_ULE: 1741 // Comparison is true iff the LHS >=s 0. 1742 if (MaxRecurse) 1743 if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, 1744 Constant::getNullValue(SrcTy), 1745 TD, DT, MaxRecurse-1)) 1746 return V; 1747 break; 1748 } 1749 } 1750 } 1751 } 1752 } 1753 1754 // Special logic for binary operators. 1755 BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); 1756 BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); 1757 if (MaxRecurse && (LBO || RBO)) { 1758 // Analyze the case when either LHS or RHS is an add instruction. 1759 Value *A = 0, *B = 0, *C = 0, *D = 0; 1760 // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). 1761 bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; 1762 if (LBO && LBO->getOpcode() == Instruction::Add) { 1763 A = LBO->getOperand(0); B = LBO->getOperand(1); 1764 NoLHSWrapProblem = ICmpInst::isEquality(Pred) || 1765 (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) || 1766 (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap()); 1767 } 1768 if (RBO && RBO->getOpcode() == Instruction::Add) { 1769 C = RBO->getOperand(0); D = RBO->getOperand(1); 1770 NoRHSWrapProblem = ICmpInst::isEquality(Pred) || 1771 (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) || 1772 (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap()); 1773 } 1774 1775 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. 1776 if ((A == RHS || B == RHS) && NoLHSWrapProblem) 1777 if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A, 1778 Constant::getNullValue(RHS->getType()), 1779 TD, DT, MaxRecurse-1)) 1780 return V; 1781 1782 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. 1783 if ((C == LHS || D == LHS) && NoRHSWrapProblem) 1784 if (Value *V = SimplifyICmpInst(Pred, 1785 Constant::getNullValue(LHS->getType()), 1786 C == LHS ? D : C, TD, DT, MaxRecurse-1)) 1787 return V; 1788 1789 // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. 1790 if (A && C && (A == C || A == D || B == C || B == D) && 1791 NoLHSWrapProblem && NoRHSWrapProblem) { 1792 // Determine Y and Z in the form icmp (X+Y), (X+Z). 1793 Value *Y = (A == C || A == D) ? B : A; 1794 Value *Z = (C == A || C == B) ? D : C; 1795 if (Value *V = SimplifyICmpInst(Pred, Y, Z, TD, DT, MaxRecurse-1)) 1796 return V; 1797 } 1798 } 1799 1800 if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { 1801 bool KnownNonNegative, KnownNegative; 1802 switch (Pred) { 1803 default: 1804 break; 1805 case ICmpInst::ICMP_SGT: 1806 case ICmpInst::ICMP_SGE: 1807 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD); 1808 if (!KnownNonNegative) 1809 break; 1810 // fall-through 1811 case ICmpInst::ICMP_EQ: 1812 case ICmpInst::ICMP_UGT: 1813 case ICmpInst::ICMP_UGE: 1814 // getNullValue also works for vectors, unlike getFalse. 1815 return Constant::getNullValue(ITy); 1816 case ICmpInst::ICMP_SLT: 1817 case ICmpInst::ICMP_SLE: 1818 ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD); 1819 if (!KnownNonNegative) 1820 break; 1821 // fall-through 1822 case ICmpInst::ICMP_NE: 1823 case ICmpInst::ICMP_ULT: 1824 case ICmpInst::ICMP_ULE: 1825 // getAllOnesValue also works for vectors, unlike getTrue. 1826 return Constant::getAllOnesValue(ITy); 1827 } 1828 } 1829 if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) { 1830 bool KnownNonNegative, KnownNegative; 1831 switch (Pred) { 1832 default: 1833 break; 1834 case ICmpInst::ICMP_SGT: 1835 case ICmpInst::ICMP_SGE: 1836 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD); 1837 if (!KnownNonNegative) 1838 break; 1839 // fall-through 1840 case ICmpInst::ICMP_NE: 1841 case ICmpInst::ICMP_UGT: 1842 case ICmpInst::ICMP_UGE: 1843 // getAllOnesValue also works for vectors, unlike getTrue. 1844 return Constant::getAllOnesValue(ITy); 1845 case ICmpInst::ICMP_SLT: 1846 case ICmpInst::ICMP_SLE: 1847 ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD); 1848 if (!KnownNonNegative) 1849 break; 1850 // fall-through 1851 case ICmpInst::ICMP_EQ: 1852 case ICmpInst::ICMP_ULT: 1853 case ICmpInst::ICMP_ULE: 1854 // getNullValue also works for vectors, unlike getFalse. 1855 return Constant::getNullValue(ITy); 1856 } 1857 } 1858 1859 if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() && 1860 LBO->getOperand(1) == RBO->getOperand(1)) { 1861 switch (LBO->getOpcode()) { 1862 default: break; 1863 case Instruction::UDiv: 1864 case Instruction::LShr: 1865 if (ICmpInst::isSigned(Pred)) 1866 break; 1867 // fall-through 1868 case Instruction::SDiv: 1869 case Instruction::AShr: 1870 if (!LBO->isExact() || !RBO->isExact()) 1871 break; 1872 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 1873 RBO->getOperand(0), TD, DT, MaxRecurse-1)) 1874 return V; 1875 break; 1876 case Instruction::Shl: { 1877 bool NUW = LBO->hasNoUnsignedWrap() && LBO->hasNoUnsignedWrap(); 1878 bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap(); 1879 if (!NUW && !NSW) 1880 break; 1881 if (!NSW && ICmpInst::isSigned(Pred)) 1882 break; 1883 if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), 1884 RBO->getOperand(0), TD, DT, MaxRecurse-1)) 1885 return V; 1886 break; 1887 } 1888 } 1889 } 1890 1891 // Simplify comparisons involving max/min. 1892 Value *A, *B; 1893 CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; 1894 CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". 1895 1896 // Signed variants on "max(a,b)>=a -> true". 1897 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 1898 if (A != RHS) std::swap(A, B); // smax(A, B) pred A. 1899 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 1900 // We analyze this as smax(A, B) pred A. 1901 P = Pred; 1902 } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && 1903 (A == LHS || B == LHS)) { 1904 if (A != LHS) std::swap(A, B); // A pred smax(A, B). 1905 EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". 1906 // We analyze this as smax(A, B) swapped-pred A. 1907 P = CmpInst::getSwappedPredicate(Pred); 1908 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 1909 (A == RHS || B == RHS)) { 1910 if (A != RHS) std::swap(A, B); // smin(A, B) pred A. 1911 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 1912 // We analyze this as smax(-A, -B) swapped-pred -A. 1913 // Note that we do not need to actually form -A or -B thanks to EqP. 1914 P = CmpInst::getSwappedPredicate(Pred); 1915 } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && 1916 (A == LHS || B == LHS)) { 1917 if (A != LHS) std::swap(A, B); // A pred smin(A, B). 1918 EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". 1919 // We analyze this as smax(-A, -B) pred -A. 1920 // Note that we do not need to actually form -A or -B thanks to EqP. 1921 P = Pred; 1922 } 1923 if (P != CmpInst::BAD_ICMP_PREDICATE) { 1924 // Cases correspond to "max(A, B) p A". 1925 switch (P) { 1926 default: 1927 break; 1928 case CmpInst::ICMP_EQ: 1929 case CmpInst::ICMP_SLE: 1930 // Equivalent to "A EqP B". This may be the same as the condition tested 1931 // in the max/min; if so, we can just return that. 1932 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 1933 return V; 1934 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 1935 return V; 1936 // Otherwise, see if "A EqP B" simplifies. 1937 if (MaxRecurse) 1938 if (Value *V = SimplifyICmpInst(EqP, A, B, TD, DT, MaxRecurse-1)) 1939 return V; 1940 break; 1941 case CmpInst::ICMP_NE: 1942 case CmpInst::ICMP_SGT: { 1943 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 1944 // Equivalent to "A InvEqP B". This may be the same as the condition 1945 // tested in the max/min; if so, we can just return that. 1946 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 1947 return V; 1948 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 1949 return V; 1950 // Otherwise, see if "A InvEqP B" simplifies. 1951 if (MaxRecurse) 1952 if (Value *V = SimplifyICmpInst(InvEqP, A, B, TD, DT, MaxRecurse-1)) 1953 return V; 1954 break; 1955 } 1956 case CmpInst::ICMP_SGE: 1957 // Always true. 1958 return Constant::getAllOnesValue(ITy); 1959 case CmpInst::ICMP_SLT: 1960 // Always false. 1961 return Constant::getNullValue(ITy); 1962 } 1963 } 1964 1965 // Unsigned variants on "max(a,b)>=a -> true". 1966 P = CmpInst::BAD_ICMP_PREDICATE; 1967 if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { 1968 if (A != RHS) std::swap(A, B); // umax(A, B) pred A. 1969 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 1970 // We analyze this as umax(A, B) pred A. 1971 P = Pred; 1972 } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && 1973 (A == LHS || B == LHS)) { 1974 if (A != LHS) std::swap(A, B); // A pred umax(A, B). 1975 EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". 1976 // We analyze this as umax(A, B) swapped-pred A. 1977 P = CmpInst::getSwappedPredicate(Pred); 1978 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 1979 (A == RHS || B == RHS)) { 1980 if (A != RHS) std::swap(A, B); // umin(A, B) pred A. 1981 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 1982 // We analyze this as umax(-A, -B) swapped-pred -A. 1983 // Note that we do not need to actually form -A or -B thanks to EqP. 1984 P = CmpInst::getSwappedPredicate(Pred); 1985 } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && 1986 (A == LHS || B == LHS)) { 1987 if (A != LHS) std::swap(A, B); // A pred umin(A, B). 1988 EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". 1989 // We analyze this as umax(-A, -B) pred -A. 1990 // Note that we do not need to actually form -A or -B thanks to EqP. 1991 P = Pred; 1992 } 1993 if (P != CmpInst::BAD_ICMP_PREDICATE) { 1994 // Cases correspond to "max(A, B) p A". 1995 switch (P) { 1996 default: 1997 break; 1998 case CmpInst::ICMP_EQ: 1999 case CmpInst::ICMP_ULE: 2000 // Equivalent to "A EqP B". This may be the same as the condition tested 2001 // in the max/min; if so, we can just return that. 2002 if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) 2003 return V; 2004 if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) 2005 return V; 2006 // Otherwise, see if "A EqP B" simplifies. 2007 if (MaxRecurse) 2008 if (Value *V = SimplifyICmpInst(EqP, A, B, TD, DT, MaxRecurse-1)) 2009 return V; 2010 break; 2011 case CmpInst::ICMP_NE: 2012 case CmpInst::ICMP_UGT: { 2013 CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); 2014 // Equivalent to "A InvEqP B". This may be the same as the condition 2015 // tested in the max/min; if so, we can just return that. 2016 if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) 2017 return V; 2018 if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) 2019 return V; 2020 // Otherwise, see if "A InvEqP B" simplifies. 2021 if (MaxRecurse) 2022 if (Value *V = SimplifyICmpInst(InvEqP, A, B, TD, DT, MaxRecurse-1)) 2023 return V; 2024 break; 2025 } 2026 case CmpInst::ICMP_UGE: 2027 // Always true. 2028 return Constant::getAllOnesValue(ITy); 2029 case CmpInst::ICMP_ULT: 2030 // Always false. 2031 return Constant::getNullValue(ITy); 2032 } 2033 } 2034 2035 // Variants on "max(x,y) >= min(x,z)". 2036 Value *C, *D; 2037 if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && 2038 match(RHS, m_SMin(m_Value(C), m_Value(D))) && 2039 (A == C || A == D || B == C || B == D)) { 2040 // max(x, ?) pred min(x, ?). 2041 if (Pred == CmpInst::ICMP_SGE) 2042 // Always true. 2043 return Constant::getAllOnesValue(ITy); 2044 if (Pred == CmpInst::ICMP_SLT) 2045 // Always false. 2046 return Constant::getNullValue(ITy); 2047 } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && 2048 match(RHS, m_SMax(m_Value(C), m_Value(D))) && 2049 (A == C || A == D || B == C || B == D)) { 2050 // min(x, ?) pred max(x, ?). 2051 if (Pred == CmpInst::ICMP_SLE) 2052 // Always true. 2053 return Constant::getAllOnesValue(ITy); 2054 if (Pred == CmpInst::ICMP_SGT) 2055 // Always false. 2056 return Constant::getNullValue(ITy); 2057 } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && 2058 match(RHS, m_UMin(m_Value(C), m_Value(D))) && 2059 (A == C || A == D || B == C || B == D)) { 2060 // max(x, ?) pred min(x, ?). 2061 if (Pred == CmpInst::ICMP_UGE) 2062 // Always true. 2063 return Constant::getAllOnesValue(ITy); 2064 if (Pred == CmpInst::ICMP_ULT) 2065 // Always false. 2066 return Constant::getNullValue(ITy); 2067 } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && 2068 match(RHS, m_UMax(m_Value(C), m_Value(D))) && 2069 (A == C || A == D || B == C || B == D)) { 2070 // min(x, ?) pred max(x, ?). 2071 if (Pred == CmpInst::ICMP_ULE) 2072 // Always true. 2073 return Constant::getAllOnesValue(ITy); 2074 if (Pred == CmpInst::ICMP_UGT) 2075 // Always false. 2076 return Constant::getNullValue(ITy); 2077 } 2078 2079 // If the comparison is with the result of a select instruction, check whether 2080 // comparing with either branch of the select always yields the same value. 2081 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2082 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse)) 2083 return V; 2084 2085 // If the comparison is with the result of a phi instruction, check whether 2086 // doing the compare with each incoming phi value yields a common result. 2087 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2088 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse)) 2089 return V; 2090 2091 return 0; 2092} 2093 2094Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2095 const TargetData *TD, const DominatorTree *DT) { 2096 return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit); 2097} 2098 2099/// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can 2100/// fold the result. If not, this returns null. 2101static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2102 const TargetData *TD, const DominatorTree *DT, 2103 unsigned MaxRecurse) { 2104 CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; 2105 assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); 2106 2107 if (Constant *CLHS = dyn_cast<Constant>(LHS)) { 2108 if (Constant *CRHS = dyn_cast<Constant>(RHS)) 2109 return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD); 2110 2111 // If we have a constant, make sure it is on the RHS. 2112 std::swap(LHS, RHS); 2113 Pred = CmpInst::getSwappedPredicate(Pred); 2114 } 2115 2116 // Fold trivial predicates. 2117 if (Pred == FCmpInst::FCMP_FALSE) 2118 return ConstantInt::get(GetCompareTy(LHS), 0); 2119 if (Pred == FCmpInst::FCMP_TRUE) 2120 return ConstantInt::get(GetCompareTy(LHS), 1); 2121 2122 if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef 2123 return UndefValue::get(GetCompareTy(LHS)); 2124 2125 // fcmp x,x -> true/false. Not all compares are foldable. 2126 if (LHS == RHS) { 2127 if (CmpInst::isTrueWhenEqual(Pred)) 2128 return ConstantInt::get(GetCompareTy(LHS), 1); 2129 if (CmpInst::isFalseWhenEqual(Pred)) 2130 return ConstantInt::get(GetCompareTy(LHS), 0); 2131 } 2132 2133 // Handle fcmp with constant RHS 2134 if (Constant *RHSC = dyn_cast<Constant>(RHS)) { 2135 // If the constant is a nan, see if we can fold the comparison based on it. 2136 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) { 2137 if (CFP->getValueAPF().isNaN()) { 2138 if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo" 2139 return ConstantInt::getFalse(CFP->getContext()); 2140 assert(FCmpInst::isUnordered(Pred) && 2141 "Comparison must be either ordered or unordered!"); 2142 // True if unordered. 2143 return ConstantInt::getTrue(CFP->getContext()); 2144 } 2145 // Check whether the constant is an infinity. 2146 if (CFP->getValueAPF().isInfinity()) { 2147 if (CFP->getValueAPF().isNegative()) { 2148 switch (Pred) { 2149 case FCmpInst::FCMP_OLT: 2150 // No value is ordered and less than negative infinity. 2151 return ConstantInt::getFalse(CFP->getContext()); 2152 case FCmpInst::FCMP_UGE: 2153 // All values are unordered with or at least negative infinity. 2154 return ConstantInt::getTrue(CFP->getContext()); 2155 default: 2156 break; 2157 } 2158 } else { 2159 switch (Pred) { 2160 case FCmpInst::FCMP_OGT: 2161 // No value is ordered and greater than infinity. 2162 return ConstantInt::getFalse(CFP->getContext()); 2163 case FCmpInst::FCMP_ULE: 2164 // All values are unordered with and at most infinity. 2165 return ConstantInt::getTrue(CFP->getContext()); 2166 default: 2167 break; 2168 } 2169 } 2170 } 2171 } 2172 } 2173 2174 // If the comparison is with the result of a select instruction, check whether 2175 // comparing with either branch of the select always yields the same value. 2176 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2177 if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse)) 2178 return V; 2179 2180 // If the comparison is with the result of a phi instruction, check whether 2181 // doing the compare with each incoming phi value yields a common result. 2182 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2183 if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse)) 2184 return V; 2185 2186 return 0; 2187} 2188 2189Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2190 const TargetData *TD, const DominatorTree *DT) { 2191 return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit); 2192} 2193 2194/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold 2195/// the result. If not, this returns null. 2196Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal, 2197 const TargetData *TD, const DominatorTree *) { 2198 // select true, X, Y -> X 2199 // select false, X, Y -> Y 2200 if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal)) 2201 return CB->getZExtValue() ? TrueVal : FalseVal; 2202 2203 // select C, X, X -> X 2204 if (TrueVal == FalseVal) 2205 return TrueVal; 2206 2207 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X 2208 return FalseVal; 2209 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X 2210 return TrueVal; 2211 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y 2212 if (isa<Constant>(TrueVal)) 2213 return TrueVal; 2214 return FalseVal; 2215 } 2216 2217 return 0; 2218} 2219 2220/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can 2221/// fold the result. If not, this returns null. 2222Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps, 2223 const TargetData *TD, const DominatorTree *) { 2224 // The type of the GEP pointer operand. 2225 const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType()); 2226 2227 // getelementptr P -> P. 2228 if (NumOps == 1) 2229 return Ops[0]; 2230 2231 if (isa<UndefValue>(Ops[0])) { 2232 // Compute the (pointer) type returned by the GEP instruction. 2233 const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1], 2234 NumOps-1); 2235 const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace()); 2236 return UndefValue::get(GEPTy); 2237 } 2238 2239 if (NumOps == 2) { 2240 // getelementptr P, 0 -> P. 2241 if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1])) 2242 if (C->isZero()) 2243 return Ops[0]; 2244 // getelementptr P, N -> P if P points to a type of zero size. 2245 if (TD) { 2246 const Type *Ty = PtrTy->getElementType(); 2247 if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0) 2248 return Ops[0]; 2249 } 2250 } 2251 2252 // Check to see if this is constant foldable. 2253 for (unsigned i = 0; i != NumOps; ++i) 2254 if (!isa<Constant>(Ops[i])) 2255 return 0; 2256 2257 return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), 2258 (Constant *const*)Ops+1, NumOps-1); 2259} 2260 2261/// SimplifyPHINode - See if we can fold the given phi. If not, returns null. 2262static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) { 2263 // If all of the PHI's incoming values are the same then replace the PHI node 2264 // with the common value. 2265 Value *CommonValue = 0; 2266 bool HasUndefInput = false; 2267 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 2268 Value *Incoming = PN->getIncomingValue(i); 2269 // If the incoming value is the phi node itself, it can safely be skipped. 2270 if (Incoming == PN) continue; 2271 if (isa<UndefValue>(Incoming)) { 2272 // Remember that we saw an undef value, but otherwise ignore them. 2273 HasUndefInput = true; 2274 continue; 2275 } 2276 if (CommonValue && Incoming != CommonValue) 2277 return 0; // Not the same, bail out. 2278 CommonValue = Incoming; 2279 } 2280 2281 // If CommonValue is null then all of the incoming values were either undef or 2282 // equal to the phi node itself. 2283 if (!CommonValue) 2284 return UndefValue::get(PN->getType()); 2285 2286 // If we have a PHI node like phi(X, undef, X), where X is defined by some 2287 // instruction, we cannot return X as the result of the PHI node unless it 2288 // dominates the PHI block. 2289 if (HasUndefInput) 2290 return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0; 2291 2292 return CommonValue; 2293} 2294 2295 2296//=== Helper functions for higher up the class hierarchy. 2297 2298/// SimplifyBinOp - Given operands for a BinaryOperator, see if we can 2299/// fold the result. If not, this returns null. 2300static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 2301 const TargetData *TD, const DominatorTree *DT, 2302 unsigned MaxRecurse) { 2303 switch (Opcode) { 2304 case Instruction::Add: 2305 return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2306 TD, DT, MaxRecurse); 2307 case Instruction::Sub: 2308 return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2309 TD, DT, MaxRecurse); 2310 case Instruction::Mul: return SimplifyMulInst (LHS, RHS, TD, DT, MaxRecurse); 2311 case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, DT, MaxRecurse); 2312 case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, DT, MaxRecurse); 2313 case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, DT, MaxRecurse); 2314 case Instruction::SRem: return SimplifySRemInst(LHS, RHS, TD, DT, MaxRecurse); 2315 case Instruction::URem: return SimplifyURemInst(LHS, RHS, TD, DT, MaxRecurse); 2316 case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, TD, DT, MaxRecurse); 2317 case Instruction::Shl: 2318 return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, 2319 TD, DT, MaxRecurse); 2320 case Instruction::LShr: 2321 return SimplifyLShrInst(LHS, RHS, /*isExact*/false, TD, DT, MaxRecurse); 2322 case Instruction::AShr: 2323 return SimplifyAShrInst(LHS, RHS, /*isExact*/false, TD, DT, MaxRecurse); 2324 case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse); 2325 case Instruction::Or: return SimplifyOrInst (LHS, RHS, TD, DT, MaxRecurse); 2326 case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse); 2327 default: 2328 if (Constant *CLHS = dyn_cast<Constant>(LHS)) 2329 if (Constant *CRHS = dyn_cast<Constant>(RHS)) { 2330 Constant *COps[] = {CLHS, CRHS}; 2331 return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD); 2332 } 2333 2334 // If the operation is associative, try some generic simplifications. 2335 if (Instruction::isAssociative(Opcode)) 2336 if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT, 2337 MaxRecurse)) 2338 return V; 2339 2340 // If the operation is with the result of a select instruction, check whether 2341 // operating on either branch of the select always yields the same value. 2342 if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) 2343 if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT, 2344 MaxRecurse)) 2345 return V; 2346 2347 // If the operation is with the result of a phi instruction, check whether 2348 // operating on all incoming values of the phi always yields the same value. 2349 if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) 2350 if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse)) 2351 return V; 2352 2353 return 0; 2354 } 2355} 2356 2357Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 2358 const TargetData *TD, const DominatorTree *DT) { 2359 return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit); 2360} 2361 2362/// SimplifyCmpInst - Given operands for a CmpInst, see if we can 2363/// fold the result. 2364static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2365 const TargetData *TD, const DominatorTree *DT, 2366 unsigned MaxRecurse) { 2367 if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) 2368 return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse); 2369 return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse); 2370} 2371 2372Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 2373 const TargetData *TD, const DominatorTree *DT) { 2374 return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit); 2375} 2376 2377/// SimplifyInstruction - See if we can compute a simplified version of this 2378/// instruction. If not, this returns null. 2379Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD, 2380 const DominatorTree *DT) { 2381 Value *Result; 2382 2383 switch (I->getOpcode()) { 2384 default: 2385 Result = ConstantFoldInstruction(I, TD); 2386 break; 2387 case Instruction::Add: 2388 Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1), 2389 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2390 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2391 TD, DT); 2392 break; 2393 case Instruction::Sub: 2394 Result = SimplifySubInst(I->getOperand(0), I->getOperand(1), 2395 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2396 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2397 TD, DT); 2398 break; 2399 case Instruction::Mul: 2400 Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT); 2401 break; 2402 case Instruction::SDiv: 2403 Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, DT); 2404 break; 2405 case Instruction::UDiv: 2406 Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, DT); 2407 break; 2408 case Instruction::FDiv: 2409 Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, DT); 2410 break; 2411 case Instruction::SRem: 2412 Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, DT); 2413 break; 2414 case Instruction::URem: 2415 Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, DT); 2416 break; 2417 case Instruction::FRem: 2418 Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, DT); 2419 break; 2420 case Instruction::Shl: 2421 Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1), 2422 cast<BinaryOperator>(I)->hasNoSignedWrap(), 2423 cast<BinaryOperator>(I)->hasNoUnsignedWrap(), 2424 TD, DT); 2425 break; 2426 case Instruction::LShr: 2427 Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), 2428 cast<BinaryOperator>(I)->isExact(), 2429 TD, DT); 2430 break; 2431 case Instruction::AShr: 2432 Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), 2433 cast<BinaryOperator>(I)->isExact(), 2434 TD, DT); 2435 break; 2436 case Instruction::And: 2437 Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT); 2438 break; 2439 case Instruction::Or: 2440 Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT); 2441 break; 2442 case Instruction::Xor: 2443 Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT); 2444 break; 2445 case Instruction::ICmp: 2446 Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), 2447 I->getOperand(0), I->getOperand(1), TD, DT); 2448 break; 2449 case Instruction::FCmp: 2450 Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), 2451 I->getOperand(0), I->getOperand(1), TD, DT); 2452 break; 2453 case Instruction::Select: 2454 Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1), 2455 I->getOperand(2), TD, DT); 2456 break; 2457 case Instruction::GetElementPtr: { 2458 SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end()); 2459 Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT); 2460 break; 2461 } 2462 case Instruction::PHI: 2463 Result = SimplifyPHINode(cast<PHINode>(I), DT); 2464 break; 2465 } 2466 2467 /// If called on unreachable code, the above logic may report that the 2468 /// instruction simplified to itself. Make life easier for users by 2469 /// detecting that case here, returning a safe value instead. 2470 return Result == I ? UndefValue::get(I->getType()) : Result; 2471} 2472 2473/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then 2474/// delete the From instruction. In addition to a basic RAUW, this does a 2475/// recursive simplification of the newly formed instructions. This catches 2476/// things where one simplification exposes other opportunities. This only 2477/// simplifies and deletes scalar operations, it does not change the CFG. 2478/// 2479void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To, 2480 const TargetData *TD, 2481 const DominatorTree *DT) { 2482 assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!"); 2483 2484 // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that 2485 // we can know if it gets deleted out from under us or replaced in a 2486 // recursive simplification. 2487 WeakVH FromHandle(From); 2488 WeakVH ToHandle(To); 2489 2490 while (!From->use_empty()) { 2491 // Update the instruction to use the new value. 2492 Use &TheUse = From->use_begin().getUse(); 2493 Instruction *User = cast<Instruction>(TheUse.getUser()); 2494 TheUse = To; 2495 2496 // Check to see if the instruction can be folded due to the operand 2497 // replacement. For example changing (or X, Y) into (or X, -1) can replace 2498 // the 'or' with -1. 2499 Value *SimplifiedVal; 2500 { 2501 // Sanity check to make sure 'User' doesn't dangle across 2502 // SimplifyInstruction. 2503 AssertingVH<> UserHandle(User); 2504 2505 SimplifiedVal = SimplifyInstruction(User, TD, DT); 2506 if (SimplifiedVal == 0) continue; 2507 } 2508 2509 // Recursively simplify this user to the new value. 2510 ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT); 2511 From = dyn_cast_or_null<Instruction>((Value*)FromHandle); 2512 To = ToHandle; 2513 2514 assert(ToHandle && "To value deleted by recursive simplification?"); 2515 2516 // If the recursive simplification ended up revisiting and deleting 2517 // 'From' then we're done. 2518 if (From == 0) 2519 return; 2520 } 2521 2522 // If 'From' has value handles referring to it, do a real RAUW to update them. 2523 From->replaceAllUsesWith(To); 2524 2525 From->eraseFromParent(); 2526} 2527