| //===- InstructionSimplify.cpp - Fold instruction operands ----------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements routines for folding instructions into simpler forms |
| // that do not require creating new instructions. This does constant folding |
| // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either |
| // returning a constant ("and i32 %x, 0" -> "0") or an already existing value |
| // ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been |
| // simplified: This is usually true and assuming it simplifies the logic (if |
| // they have not been simplified then results are correct but maybe suboptimal). |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "instsimplify" |
| #include "llvm/Analysis/InstructionSimplify.h" |
| #include "llvm/ADT/SetVector.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/Analysis/ConstantFolding.h" |
| #include "llvm/Analysis/Dominators.h" |
| #include "llvm/Analysis/ValueTracking.h" |
| #include "llvm/Analysis/MemoryBuiltins.h" |
| #include "llvm/IR/DataLayout.h" |
| #include "llvm/IR/GlobalAlias.h" |
| #include "llvm/IR/Operator.h" |
| #include "llvm/Support/ConstantRange.h" |
| #include "llvm/Support/GetElementPtrTypeIterator.h" |
| #include "llvm/Support/PatternMatch.h" |
| #include "llvm/Support/ValueHandle.h" |
| using namespace llvm; |
| using namespace llvm::PatternMatch; |
| |
| enum { RecursionLimit = 3 }; |
| |
| STATISTIC(NumExpand, "Number of expansions"); |
| STATISTIC(NumFactor , "Number of factorizations"); |
| STATISTIC(NumReassoc, "Number of reassociations"); |
| |
| struct Query { |
| const DataLayout *TD; |
| const TargetLibraryInfo *TLI; |
| const DominatorTree *DT; |
| |
| Query(const DataLayout *td, const TargetLibraryInfo *tli, |
| const DominatorTree *dt) : TD(td), TLI(tli), DT(dt) {} |
| }; |
| |
| static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned); |
| static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &, |
| unsigned); |
| static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &, |
| unsigned); |
| static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned); |
| static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned); |
| static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned); |
| |
| /// getFalse - For a boolean type, or a vector of boolean type, return false, or |
| /// a vector with every element false, as appropriate for the type. |
| static Constant *getFalse(Type *Ty) { |
| assert(Ty->getScalarType()->isIntegerTy(1) && |
| "Expected i1 type or a vector of i1!"); |
| return Constant::getNullValue(Ty); |
| } |
| |
| /// getTrue - For a boolean type, or a vector of boolean type, return true, or |
| /// a vector with every element true, as appropriate for the type. |
| static Constant *getTrue(Type *Ty) { |
| assert(Ty->getScalarType()->isIntegerTy(1) && |
| "Expected i1 type or a vector of i1!"); |
| return Constant::getAllOnesValue(Ty); |
| } |
| |
| /// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? |
| static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, |
| Value *RHS) { |
| CmpInst *Cmp = dyn_cast<CmpInst>(V); |
| if (!Cmp) |
| return false; |
| CmpInst::Predicate CPred = Cmp->getPredicate(); |
| Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); |
| if (CPred == Pred && CLHS == LHS && CRHS == RHS) |
| return true; |
| return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && |
| CRHS == LHS; |
| } |
| |
| /// ValueDominatesPHI - Does the given value dominate the specified phi node? |
| static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) |
| // Arguments and constants dominate all instructions. |
| return true; |
| |
| // If we are processing instructions (and/or basic blocks) that have not been |
| // fully added to a function, the parent nodes may still be null. Simply |
| // return the conservative answer in these cases. |
| if (!I->getParent() || !P->getParent() || !I->getParent()->getParent()) |
| return false; |
| |
| // If we have a DominatorTree then do a precise test. |
| if (DT) { |
| if (!DT->isReachableFromEntry(P->getParent())) |
| return true; |
| if (!DT->isReachableFromEntry(I->getParent())) |
| return false; |
| return DT->dominates(I, P); |
| } |
| |
| // Otherwise, if the instruction is in the entry block, and is not an invoke, |
| // then it obviously dominates all phi nodes. |
| if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() && |
| !isa<InvokeInst>(I)) |
| return true; |
| |
| return false; |
| } |
| |
| /// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning |
| /// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is |
| /// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS. |
| /// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)". |
| /// Returns the simplified value, or null if no simplification was performed. |
| static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS, |
| unsigned OpcToExpand, const Query &Q, |
| unsigned MaxRecurse) { |
| Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand; |
| // Recursion is always used, so bail out at once if we already hit the limit. |
| if (!MaxRecurse--) |
| return 0; |
| |
| // Check whether the expression has the form "(A op' B) op C". |
| if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS)) |
| if (Op0->getOpcode() == OpcodeToExpand) { |
| // It does! Try turning it into "(A op C) op' (B op C)". |
| Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS; |
| // Do "A op C" and "B op C" both simplify? |
| if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) |
| if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { |
| // They do! Return "L op' R" if it simplifies or is already available. |
| // If "L op' R" equals "A op' B" then "L op' R" is just the LHS. |
| if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand) |
| && L == B && R == A)) { |
| ++NumExpand; |
| return LHS; |
| } |
| // Otherwise return "L op' R" if it simplifies. |
| if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) { |
| ++NumExpand; |
| return V; |
| } |
| } |
| } |
| |
| // Check whether the expression has the form "A op (B op' C)". |
| if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS)) |
| if (Op1->getOpcode() == OpcodeToExpand) { |
| // It does! Try turning it into "(A op B) op' (A op C)". |
| Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1); |
| // Do "A op B" and "A op C" both simplify? |
| if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) |
| if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) { |
| // They do! Return "L op' R" if it simplifies or is already available. |
| // If "L op' R" equals "B op' C" then "L op' R" is just the RHS. |
| if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand) |
| && L == C && R == B)) { |
| ++NumExpand; |
| return RHS; |
| } |
| // Otherwise return "L op' R" if it simplifies. |
| if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) { |
| ++NumExpand; |
| return V; |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| /// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term |
| /// using the operation OpCodeToExtract. For example, when Opcode is Add and |
| /// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)". |
| /// Returns the simplified value, or null if no simplification was performed. |
| static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS, |
| unsigned OpcToExtract, const Query &Q, |
| unsigned MaxRecurse) { |
| Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract; |
| // Recursion is always used, so bail out at once if we already hit the limit. |
| if (!MaxRecurse--) |
| return 0; |
| |
| BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); |
| BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); |
| |
| if (!Op0 || Op0->getOpcode() != OpcodeToExtract || |
| !Op1 || Op1->getOpcode() != OpcodeToExtract) |
| return 0; |
| |
| // The expression has the form "(A op' B) op (C op' D)". |
| Value *A = Op0->getOperand(0), *B = Op0->getOperand(1); |
| Value *C = Op1->getOperand(0), *D = Op1->getOperand(1); |
| |
| // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)". |
| // Does the instruction have the form "(A op' B) op (A op' D)" or, in the |
| // commutative case, "(A op' B) op (C op' A)"? |
| if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) { |
| Value *DD = A == C ? D : C; |
| // Form "A op' (B op DD)" if it simplifies completely. |
| // Does "B op DD" simplify? |
| if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) { |
| // It does! Return "A op' V" if it simplifies or is already available. |
| // If V equals B then "A op' V" is just the LHS. If V equals DD then |
| // "A op' V" is just the RHS. |
| if (V == B || V == DD) { |
| ++NumFactor; |
| return V == B ? LHS : RHS; |
| } |
| // Otherwise return "A op' V" if it simplifies. |
| if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) { |
| ++NumFactor; |
| return W; |
| } |
| } |
| } |
| |
| // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)". |
| // Does the instruction have the form "(A op' B) op (C op' B)" or, in the |
| // commutative case, "(A op' B) op (B op' D)"? |
| if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) { |
| Value *CC = B == D ? C : D; |
| // Form "(A op CC) op' B" if it simplifies completely.. |
| // Does "A op CC" simplify? |
| if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) { |
| // It does! Return "V op' B" if it simplifies or is already available. |
| // If V equals A then "V op' B" is just the LHS. If V equals CC then |
| // "V op' B" is just the RHS. |
| if (V == A || V == CC) { |
| ++NumFactor; |
| return V == A ? LHS : RHS; |
| } |
| // Otherwise return "V op' B" if it simplifies. |
| if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) { |
| ++NumFactor; |
| return W; |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| /// SimplifyAssociativeBinOp - Generic simplifications for associative binary |
| /// operations. Returns the simpler value, or null if none was found. |
| static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS, |
| const Query &Q, unsigned MaxRecurse) { |
| Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc; |
| assert(Instruction::isAssociative(Opcode) && "Not an associative operation!"); |
| |
| // Recursion is always used, so bail out at once if we already hit the limit. |
| if (!MaxRecurse--) |
| return 0; |
| |
| BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS); |
| BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS); |
| |
| // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely. |
| if (Op0 && Op0->getOpcode() == Opcode) { |
| Value *A = Op0->getOperand(0); |
| Value *B = Op0->getOperand(1); |
| Value *C = RHS; |
| |
| // Does "B op C" simplify? |
| if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { |
| // It does! Return "A op V" if it simplifies or is already available. |
| // If V equals B then "A op V" is just the LHS. |
| if (V == B) return LHS; |
| // Otherwise return "A op V" if it simplifies. |
| if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) { |
| ++NumReassoc; |
| return W; |
| } |
| } |
| } |
| |
| // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely. |
| if (Op1 && Op1->getOpcode() == Opcode) { |
| Value *A = LHS; |
| Value *B = Op1->getOperand(0); |
| Value *C = Op1->getOperand(1); |
| |
| // Does "A op B" simplify? |
| if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) { |
| // It does! Return "V op C" if it simplifies or is already available. |
| // If V equals B then "V op C" is just the RHS. |
| if (V == B) return RHS; |
| // Otherwise return "V op C" if it simplifies. |
| if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) { |
| ++NumReassoc; |
| return W; |
| } |
| } |
| } |
| |
| // The remaining transforms require commutativity as well as associativity. |
| if (!Instruction::isCommutative(Opcode)) |
| return 0; |
| |
| // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely. |
| if (Op0 && Op0->getOpcode() == Opcode) { |
| Value *A = Op0->getOperand(0); |
| Value *B = Op0->getOperand(1); |
| Value *C = RHS; |
| |
| // Does "C op A" simplify? |
| if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { |
| // It does! Return "V op B" if it simplifies or is already available. |
| // If V equals A then "V op B" is just the LHS. |
| if (V == A) return LHS; |
| // Otherwise return "V op B" if it simplifies. |
| if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) { |
| ++NumReassoc; |
| return W; |
| } |
| } |
| } |
| |
| // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely. |
| if (Op1 && Op1->getOpcode() == Opcode) { |
| Value *A = LHS; |
| Value *B = Op1->getOperand(0); |
| Value *C = Op1->getOperand(1); |
| |
| // Does "C op A" simplify? |
| if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) { |
| // It does! Return "B op V" if it simplifies or is already available. |
| // If V equals C then "B op V" is just the RHS. |
| if (V == C) return RHS; |
| // Otherwise return "B op V" if it simplifies. |
| if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) { |
| ++NumReassoc; |
| return W; |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| /// ThreadBinOpOverSelect - In the case of a binary operation with a select |
| /// instruction as an operand, try to simplify the binop by seeing whether |
| /// evaluating it on both branches of the select results in the same value. |
| /// Returns the common value if so, otherwise returns null. |
| static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS, |
| const Query &Q, unsigned MaxRecurse) { |
| // Recursion is always used, so bail out at once if we already hit the limit. |
| if (!MaxRecurse--) |
| return 0; |
| |
| SelectInst *SI; |
| if (isa<SelectInst>(LHS)) { |
| SI = cast<SelectInst>(LHS); |
| } else { |
| assert(isa<SelectInst>(RHS) && "No select instruction operand!"); |
| SI = cast<SelectInst>(RHS); |
| } |
| |
| // Evaluate the BinOp on the true and false branches of the select. |
| Value *TV; |
| Value *FV; |
| if (SI == LHS) { |
| TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse); |
| FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse); |
| } else { |
| TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse); |
| FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse); |
| } |
| |
| // If they simplified to the same value, then return the common value. |
| // If they both failed to simplify then return null. |
| if (TV == FV) |
| return TV; |
| |
| // If one branch simplified to undef, return the other one. |
| if (TV && isa<UndefValue>(TV)) |
| return FV; |
| if (FV && isa<UndefValue>(FV)) |
| return TV; |
| |
| // If applying the operation did not change the true and false select values, |
| // then the result of the binop is the select itself. |
| if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) |
| return SI; |
| |
| // If one branch simplified and the other did not, and the simplified |
| // value is equal to the unsimplified one, return the simplified value. |
| // For example, select (cond, X, X & Z) & Z -> X & Z. |
| if ((FV && !TV) || (TV && !FV)) { |
| // Check that the simplified value has the form "X op Y" where "op" is the |
| // same as the original operation. |
| Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); |
| if (Simplified && Simplified->getOpcode() == Opcode) { |
| // The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS". |
| // We already know that "op" is the same as for the simplified value. See |
| // if the operands match too. If so, return the simplified value. |
| Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue(); |
| Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS; |
| Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch; |
| if (Simplified->getOperand(0) == UnsimplifiedLHS && |
| Simplified->getOperand(1) == UnsimplifiedRHS) |
| return Simplified; |
| if (Simplified->isCommutative() && |
| Simplified->getOperand(1) == UnsimplifiedLHS && |
| Simplified->getOperand(0) == UnsimplifiedRHS) |
| return Simplified; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /// ThreadCmpOverSelect - In the case of a comparison with a select instruction, |
| /// try to simplify the comparison by seeing whether both branches of the select |
| /// result in the same value. Returns the common value if so, otherwise returns |
| /// null. |
| static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS, |
| Value *RHS, const Query &Q, |
| unsigned MaxRecurse) { |
| // Recursion is always used, so bail out at once if we already hit the limit. |
| if (!MaxRecurse--) |
| return 0; |
| |
| // Make sure the select is on the LHS. |
| if (!isa<SelectInst>(LHS)) { |
| std::swap(LHS, RHS); |
| Pred = CmpInst::getSwappedPredicate(Pred); |
| } |
| assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!"); |
| SelectInst *SI = cast<SelectInst>(LHS); |
| Value *Cond = SI->getCondition(); |
| Value *TV = SI->getTrueValue(); |
| Value *FV = SI->getFalseValue(); |
| |
| // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. |
| // Does "cmp TV, RHS" simplify? |
| Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse); |
| if (TCmp == Cond) { |
| // It not only simplified, it simplified to the select condition. Replace |
| // it with 'true'. |
| TCmp = getTrue(Cond->getType()); |
| } else if (!TCmp) { |
| // It didn't simplify. However if "cmp TV, RHS" is equal to the select |
| // condition then we can replace it with 'true'. Otherwise give up. |
| if (!isSameCompare(Cond, Pred, TV, RHS)) |
| return 0; |
| TCmp = getTrue(Cond->getType()); |
| } |
| |
| // Does "cmp FV, RHS" simplify? |
| Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse); |
| if (FCmp == Cond) { |
| // It not only simplified, it simplified to the select condition. Replace |
| // it with 'false'. |
| FCmp = getFalse(Cond->getType()); |
| } else if (!FCmp) { |
| // It didn't simplify. However if "cmp FV, RHS" is equal to the select |
| // condition then we can replace it with 'false'. Otherwise give up. |
| if (!isSameCompare(Cond, Pred, FV, RHS)) |
| return 0; |
| FCmp = getFalse(Cond->getType()); |
| } |
| |
| // If both sides simplified to the same value, then use it as the result of |
| // the original comparison. |
| if (TCmp == FCmp) |
| return TCmp; |
| |
| // The remaining cases only make sense if the select condition has the same |
| // type as the result of the comparison, so bail out if this is not so. |
| if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy()) |
| return 0; |
| // If the false value simplified to false, then the result of the compare |
| // is equal to "Cond && TCmp". This also catches the case when the false |
| // value simplified to false and the true value to true, returning "Cond". |
| if (match(FCmp, m_Zero())) |
| if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse)) |
| return V; |
| // If the true value simplified to true, then the result of the compare |
| // is equal to "Cond || FCmp". |
| if (match(TCmp, m_One())) |
| if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse)) |
| return V; |
| // Finally, if the false value simplified to true and the true value to |
| // false, then the result of the compare is equal to "!Cond". |
| if (match(FCmp, m_One()) && match(TCmp, m_Zero())) |
| if (Value *V = |
| SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()), |
| Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| /// ThreadBinOpOverPHI - In the case of a binary operation with an operand that |
| /// is a PHI instruction, try to simplify the binop by seeing whether evaluating |
| /// it on the incoming phi values yields the same result for every value. If so |
| /// returns the common value, otherwise returns null. |
| static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS, |
| const Query &Q, unsigned MaxRecurse) { |
| // Recursion is always used, so bail out at once if we already hit the limit. |
| if (!MaxRecurse--) |
| return 0; |
| |
| PHINode *PI; |
| if (isa<PHINode>(LHS)) { |
| PI = cast<PHINode>(LHS); |
| // Bail out if RHS and the phi may be mutually interdependent due to a loop. |
| if (!ValueDominatesPHI(RHS, PI, Q.DT)) |
| return 0; |
| } else { |
| assert(isa<PHINode>(RHS) && "No PHI instruction operand!"); |
| PI = cast<PHINode>(RHS); |
| // Bail out if LHS and the phi may be mutually interdependent due to a loop. |
| if (!ValueDominatesPHI(LHS, PI, Q.DT)) |
| return 0; |
| } |
| |
| // Evaluate the BinOp on the incoming phi values. |
| Value *CommonValue = 0; |
| for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) { |
| Value *Incoming = PI->getIncomingValue(i); |
| // If the incoming value is the phi node itself, it can safely be skipped. |
| if (Incoming == PI) continue; |
| Value *V = PI == LHS ? |
| SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) : |
| SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse); |
| // If the operation failed to simplify, or simplified to a different value |
| // to previously, then give up. |
| if (!V || (CommonValue && V != CommonValue)) |
| return 0; |
| CommonValue = V; |
| } |
| |
| return CommonValue; |
| } |
| |
| /// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try |
| /// try to simplify the comparison by seeing whether comparing with all of the |
| /// incoming phi values yields the same result every time. If so returns the |
| /// common result, otherwise returns null. |
| static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS, |
| const Query &Q, unsigned MaxRecurse) { |
| // Recursion is always used, so bail out at once if we already hit the limit. |
| if (!MaxRecurse--) |
| return 0; |
| |
| // Make sure the phi is on the LHS. |
| if (!isa<PHINode>(LHS)) { |
| std::swap(LHS, RHS); |
| Pred = CmpInst::getSwappedPredicate(Pred); |
| } |
| assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!"); |
| PHINode *PI = cast<PHINode>(LHS); |
| |
| // Bail out if RHS and the phi may be mutually interdependent due to a loop. |
| if (!ValueDominatesPHI(RHS, PI, Q.DT)) |
| return 0; |
| |
| // Evaluate the BinOp on the incoming phi values. |
| Value *CommonValue = 0; |
| for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) { |
| Value *Incoming = PI->getIncomingValue(i); |
| // If the incoming value is the phi node itself, it can safely be skipped. |
| if (Incoming == PI) continue; |
| Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse); |
| // If the operation failed to simplify, or simplified to a different value |
| // to previously, then give up. |
| if (!V || (CommonValue && V != CommonValue)) |
| return 0; |
| CommonValue = V; |
| } |
| |
| return CommonValue; |
| } |
| |
| /// SimplifyAddInst - Given operands for an Add, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) { |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(), Ops, |
| Q.TD, Q.TLI); |
| } |
| |
| // Canonicalize the constant to the RHS. |
| std::swap(Op0, Op1); |
| } |
| |
| // X + undef -> undef |
| if (match(Op1, m_Undef())) |
| return Op1; |
| |
| // X + 0 -> X |
| if (match(Op1, m_Zero())) |
| return Op0; |
| |
| // X + (Y - X) -> Y |
| // (Y - X) + X -> Y |
| // Eg: X + -X -> 0 |
| Value *Y = 0; |
| if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) || |
| match(Op0, m_Sub(m_Value(Y), m_Specific(Op1)))) |
| return Y; |
| |
| // X + ~X -> -1 since ~X = -X-1 |
| if (match(Op0, m_Not(m_Specific(Op1))) || |
| match(Op1, m_Not(m_Specific(Op0)))) |
| return Constant::getAllOnesValue(Op0->getType()); |
| |
| /// i1 add -> xor. |
| if (MaxRecurse && Op0->getType()->isIntegerTy(1)) |
| if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) |
| return V; |
| |
| // Try some generic simplifications for associative operations. |
| if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| // Mul distributes over Add. Try some generic simplifications based on this. |
| if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul, |
| Q, MaxRecurse)) |
| return V; |
| |
| // Threading Add over selects and phi nodes is pointless, so don't bother. |
| // Threading over the select in "A + select(cond, B, C)" means evaluating |
| // "A+B" and "A+C" and seeing if they are equal; but they are equal if and |
| // only if B and C are equal. If B and C are equal then (since we assume |
| // that operands have already been simplified) "select(cond, B, C)" should |
| // have been simplified to the common value of B and C already. Analysing |
| // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly |
| // for threading over phi nodes. |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, |
| const DataLayout *TD, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// \brief Compute the base pointer and cumulative constant offsets for V. |
| /// |
| /// This strips all constant offsets off of V, leaving it the base pointer, and |
| /// accumulates the total constant offset applied in the returned constant. It |
| /// returns 0 if V is not a pointer, and returns the constant '0' if there are |
| /// no constant offsets applied. |
| /// |
| /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't |
| /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc. |
| /// folding. |
| static ConstantInt *stripAndComputeConstantOffsets(const DataLayout *TD, |
| Value *&V) { |
| assert(V->getType()->isPointerTy()); |
| |
| // Without DataLayout, just be conservative for now. Theoretically, more could |
| // be done in this case. |
| if (!TD) |
| return ConstantInt::get(IntegerType::get(V->getContext(), 64), 0); |
| |
| unsigned IntPtrWidth = TD->getPointerSizeInBits(); |
| APInt Offset = APInt::getNullValue(IntPtrWidth); |
| |
| // Even though we don't look through PHI nodes, we could be called on an |
| // instruction in an unreachable block, which may be on a cycle. |
| SmallPtrSet<Value *, 4> Visited; |
| Visited.insert(V); |
| do { |
| if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { |
| if (!GEP->isInBounds() || !GEP->accumulateConstantOffset(*TD, Offset)) |
| break; |
| V = GEP->getPointerOperand(); |
| } else if (Operator::getOpcode(V) == Instruction::BitCast) { |
| V = cast<Operator>(V)->getOperand(0); |
| } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { |
| if (GA->mayBeOverridden()) |
| break; |
| V = GA->getAliasee(); |
| } else { |
| break; |
| } |
| assert(V->getType()->isPointerTy() && "Unexpected operand type!"); |
| } while (Visited.insert(V)); |
| |
| Type *IntPtrTy = TD->getIntPtrType(V->getContext()); |
| return cast<ConstantInt>(ConstantInt::get(IntPtrTy, Offset)); |
| } |
| |
| /// \brief Compute the constant difference between two pointer values. |
| /// If the difference is not a constant, returns zero. |
| static Constant *computePointerDifference(const DataLayout *TD, |
| Value *LHS, Value *RHS) { |
| Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS); |
| Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS); |
| |
| // If LHS and RHS are not related via constant offsets to the same base |
| // value, there is nothing we can do here. |
| if (LHS != RHS) |
| return 0; |
| |
| // Otherwise, the difference of LHS - RHS can be computed as: |
| // LHS - RHS |
| // = (LHSOffset + Base) - (RHSOffset + Base) |
| // = LHSOffset - RHSOffset |
| return ConstantExpr::getSub(LHSOffset, RHSOffset); |
| } |
| |
| /// SimplifySubInst - Given operands for a Sub, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(), |
| Ops, Q.TD, Q.TLI); |
| } |
| |
| // X - undef -> undef |
| // undef - X -> undef |
| if (match(Op0, m_Undef()) || match(Op1, m_Undef())) |
| return UndefValue::get(Op0->getType()); |
| |
| // X - 0 -> X |
| if (match(Op1, m_Zero())) |
| return Op0; |
| |
| // X - X -> 0 |
| if (Op0 == Op1) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // (X*2) - X -> X |
| // (X<<1) - X -> X |
| Value *X = 0; |
| if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) || |
| match(Op0, m_Shl(m_Specific(Op1), m_One()))) |
| return Op1; |
| |
| // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. |
| // For example, (X + Y) - Y -> X; (Y + X) - Y -> X |
| Value *Y = 0, *Z = Op1; |
| if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z |
| // See if "V === Y - Z" simplifies. |
| if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1)) |
| // It does! Now see if "X + V" simplifies. |
| if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) { |
| // It does, we successfully reassociated! |
| ++NumReassoc; |
| return W; |
| } |
| // See if "V === X - Z" simplifies. |
| if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) |
| // It does! Now see if "Y + V" simplifies. |
| if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) { |
| // It does, we successfully reassociated! |
| ++NumReassoc; |
| return W; |
| } |
| } |
| |
| // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. |
| // For example, X - (X + 1) -> -1 |
| X = Op0; |
| if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) |
| // See if "V === X - Y" simplifies. |
| if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) |
| // It does! Now see if "V - Z" simplifies. |
| if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) { |
| // It does, we successfully reassociated! |
| ++NumReassoc; |
| return W; |
| } |
| // See if "V === X - Z" simplifies. |
| if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) |
| // It does! Now see if "V - Y" simplifies. |
| if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) { |
| // It does, we successfully reassociated! |
| ++NumReassoc; |
| return W; |
| } |
| } |
| |
| // Z - (X - Y) -> (Z - X) + Y if everything simplifies. |
| // For example, X - (X - Y) -> Y. |
| Z = Op0; |
| if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) |
| // See if "V === Z - X" simplifies. |
| if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1)) |
| // It does! Now see if "V + Y" simplifies. |
| if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) { |
| // It does, we successfully reassociated! |
| ++NumReassoc; |
| return W; |
| } |
| |
| // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. |
| if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && |
| match(Op1, m_Trunc(m_Value(Y)))) |
| if (X->getType() == Y->getType()) |
| // See if "V === X - Y" simplifies. |
| if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) |
| // It does! Now see if "trunc V" simplifies. |
| if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1)) |
| // It does, return the simplified "trunc V". |
| return W; |
| |
| // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). |
| if (match(Op0, m_PtrToInt(m_Value(X))) && |
| match(Op1, m_PtrToInt(m_Value(Y)))) |
| if (Constant *Result = computePointerDifference(Q.TD, X, Y)) |
| return ConstantExpr::getIntegerCast(Result, Op0->getType(), true); |
| |
| // Mul distributes over Sub. Try some generic simplifications based on this. |
| if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul, |
| Q, MaxRecurse)) |
| return V; |
| |
| // i1 sub -> xor. |
| if (MaxRecurse && Op0->getType()->isIntegerTy(1)) |
| if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) |
| return V; |
| |
| // Threading Sub over selects and phi nodes is pointless, so don't bother. |
| // Threading over the select in "A - select(cond, B, C)" means evaluating |
| // "A-B" and "A-C" and seeing if they are equal; but they are equal if and |
| // only if B and C are equal. If B and C are equal then (since we assume |
| // that operands have already been simplified) "select(cond, B, C)" should |
| // have been simplified to the common value of B and C already. Analysing |
| // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly |
| // for threading over phi nodes. |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, |
| const DataLayout *TD, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// Given operands for an FAdd, see if we can fold the result. If not, this |
| /// returns null. |
| static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) { |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::FAdd, CLHS->getType(), |
| Ops, Q.TD, Q.TLI); |
| } |
| |
| // Canonicalize the constant to the RHS. |
| std::swap(Op0, Op1); |
| } |
| |
| // fadd X, -0 ==> X |
| if (match(Op1, m_NegZero())) |
| return Op0; |
| |
| // fadd X, 0 ==> X, when we know X is not -0 |
| if (match(Op1, m_Zero()) && |
| (FMF.noSignedZeros() || CannotBeNegativeZero(Op0))) |
| return Op0; |
| |
| // fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0 |
| // where nnan and ninf have to occur at least once somewhere in this |
| // expression |
| Value *SubOp = 0; |
| if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0)))) |
| SubOp = Op1; |
| else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1)))) |
| SubOp = Op0; |
| if (SubOp) { |
| Instruction *FSub = cast<Instruction>(SubOp); |
| if ((FMF.noNaNs() || FSub->hasNoNaNs()) && |
| (FMF.noInfs() || FSub->hasNoInfs())) |
| return Constant::getNullValue(Op0->getType()); |
| } |
| |
| return 0; |
| } |
| |
| /// Given operands for an FSub, see if we can fold the result. If not, this |
| /// returns null. |
| static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) { |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::FSub, CLHS->getType(), |
| Ops, Q.TD, Q.TLI); |
| } |
| } |
| |
| // fsub X, 0 ==> X |
| if (match(Op1, m_Zero())) |
| return Op0; |
| |
| // fsub X, -0 ==> X, when we know X is not -0 |
| if (match(Op1, m_NegZero()) && |
| (FMF.noSignedZeros() || CannotBeNegativeZero(Op0))) |
| return Op0; |
| |
| // fsub 0, (fsub -0.0, X) ==> X |
| Value *X; |
| if (match(Op0, m_AnyZero())) { |
| if (match(Op1, m_FSub(m_NegZero(), m_Value(X)))) |
| return X; |
| if (FMF.noSignedZeros() && match(Op1, m_FSub(m_AnyZero(), m_Value(X)))) |
| return X; |
| } |
| |
| // fsub nnan ninf x, x ==> 0.0 |
| if (FMF.noNaNs() && FMF.noInfs() && Op0 == Op1) |
| return Constant::getNullValue(Op0->getType()); |
| |
| return 0; |
| } |
| |
| /// Given the operands for an FMul, see if we can fold the result |
| static Value *SimplifyFMulInst(Value *Op0, Value *Op1, |
| FastMathFlags FMF, |
| const Query &Q, |
| unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) { |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::FMul, CLHS->getType(), |
| Ops, Q.TD, Q.TLI); |
| } |
| |
| // Canonicalize the constant to the RHS. |
| std::swap(Op0, Op1); |
| } |
| |
| // fmul X, 1.0 ==> X |
| if (match(Op1, m_FPOne())) |
| return Op0; |
| |
| // fmul nnan nsz X, 0 ==> 0 |
| if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero())) |
| return Op1; |
| |
| return 0; |
| } |
| |
| /// SimplifyMulInst - Given operands for a Mul, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) { |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(), |
| Ops, Q.TD, Q.TLI); |
| } |
| |
| // Canonicalize the constant to the RHS. |
| std::swap(Op0, Op1); |
| } |
| |
| // X * undef -> 0 |
| if (match(Op1, m_Undef())) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // X * 0 -> 0 |
| if (match(Op1, m_Zero())) |
| return Op1; |
| |
| // X * 1 -> X |
| if (match(Op1, m_One())) |
| return Op0; |
| |
| // (X / Y) * Y -> X if the division is exact. |
| Value *X = 0; |
| if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y |
| match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y) |
| return X; |
| |
| // i1 mul -> and. |
| if (MaxRecurse && Op0->getType()->isIntegerTy(1)) |
| if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1)) |
| return V; |
| |
| // Try some generic simplifications for associative operations. |
| if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| // Mul distributes over Add. Try some generic simplifications based on this. |
| if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add, |
| Q, MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a select instruction, check whether |
| // operating on either branch of the select always yields the same value. |
| if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) |
| if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a phi instruction, check whether |
| // operating on all incoming values of the phi always yields the same value. |
| if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) |
| if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, |
| const DataLayout *TD, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyFAddInst(Op0, Op1, FMF, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, |
| const DataLayout *TD, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyFSubInst(Op0, Op1, FMF, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, |
| FastMathFlags FMF, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyFMulInst(Op0, Op1, FMF, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyMulInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Constant *C0 = dyn_cast<Constant>(Op0)) { |
| if (Constant *C1 = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { C0, C1 }; |
| return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); |
| } |
| } |
| |
| bool isSigned = Opcode == Instruction::SDiv; |
| |
| // X / undef -> undef |
| if (match(Op1, m_Undef())) |
| return Op1; |
| |
| // undef / X -> 0 |
| if (match(Op0, m_Undef())) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // 0 / X -> 0, we don't need to preserve faults! |
| if (match(Op0, m_Zero())) |
| return Op0; |
| |
| // X / 1 -> X |
| if (match(Op1, m_One())) |
| return Op0; |
| |
| if (Op0->getType()->isIntegerTy(1)) |
| // It can't be division by zero, hence it must be division by one. |
| return Op0; |
| |
| // X / X -> 1 |
| if (Op0 == Op1) |
| return ConstantInt::get(Op0->getType(), 1); |
| |
| // (X * Y) / Y -> X if the multiplication does not overflow. |
| Value *X = 0, *Y = 0; |
| if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) { |
| if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1 |
| OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0); |
| // If the Mul knows it does not overflow, then we are good to go. |
| if ((isSigned && Mul->hasNoSignedWrap()) || |
| (!isSigned && Mul->hasNoUnsignedWrap())) |
| return X; |
| // If X has the form X = A / Y then X * Y cannot overflow. |
| if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X)) |
| if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y) |
| return X; |
| } |
| |
| // (X rem Y) / Y -> 0 |
| if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || |
| (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1))))) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // If the operation is with the result of a select instruction, check whether |
| // operating on either branch of the select always yields the same value. |
| if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) |
| if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a phi instruction, check whether |
| // operating on all incoming values of the phi always yields the same value. |
| if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) |
| if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| /// SimplifySDivInst - Given operands for an SDiv, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned MaxRecurse) { |
| if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifySDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyUDivInst - Given operands for a UDiv, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned MaxRecurse) { |
| if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyUDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned) { |
| // undef / X -> undef (the undef could be a snan). |
| if (match(Op0, m_Undef())) |
| return Op0; |
| |
| // X / undef -> undef |
| if (match(Op1, m_Undef())) |
| return Op1; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyFDivInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyRem - Given operands for an SRem or URem, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Constant *C0 = dyn_cast<Constant>(Op0)) { |
| if (Constant *C1 = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { C0, C1 }; |
| return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); |
| } |
| } |
| |
| // X % undef -> undef |
| if (match(Op1, m_Undef())) |
| return Op1; |
| |
| // undef % X -> 0 |
| if (match(Op0, m_Undef())) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // 0 % X -> 0, we don't need to preserve faults! |
| if (match(Op0, m_Zero())) |
| return Op0; |
| |
| // X % 0 -> undef, we don't need to preserve faults! |
| if (match(Op1, m_Zero())) |
| return UndefValue::get(Op0->getType()); |
| |
| // X % 1 -> 0 |
| if (match(Op1, m_One())) |
| return Constant::getNullValue(Op0->getType()); |
| |
| if (Op0->getType()->isIntegerTy(1)) |
| // It can't be remainder by zero, hence it must be remainder by one. |
| return Constant::getNullValue(Op0->getType()); |
| |
| // X % X -> 0 |
| if (Op0 == Op1) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // If the operation is with the result of a select instruction, check whether |
| // operating on either branch of the select always yields the same value. |
| if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) |
| if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a phi instruction, check whether |
| // operating on all incoming values of the phi always yields the same value. |
| if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) |
| if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| /// SimplifySRemInst - Given operands for an SRem, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned MaxRecurse) { |
| if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifySRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyURemInst - Given operands for a URem, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned MaxRecurse) { |
| if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyURemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const Query &, |
| unsigned) { |
| // undef % X -> undef (the undef could be a snan). |
| if (match(Op0, m_Undef())) |
| return Op0; |
| |
| // X % undef -> undef |
| if (match(Op1, m_Undef())) |
| return Op1; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyFRemInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Constant *C0 = dyn_cast<Constant>(Op0)) { |
| if (Constant *C1 = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { C0, C1 }; |
| return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, Q.TD, Q.TLI); |
| } |
| } |
| |
| // 0 shift by X -> 0 |
| if (match(Op0, m_Zero())) |
| return Op0; |
| |
| // X shift by 0 -> X |
| if (match(Op1, m_Zero())) |
| return Op0; |
| |
| // X shift by undef -> undef because it may shift by the bitwidth. |
| if (match(Op1, m_Undef())) |
| return Op1; |
| |
| // Shifting by the bitwidth or more is undefined. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) |
| if (CI->getValue().getLimitedValue() >= |
| Op0->getType()->getScalarSizeInBits()) |
| return UndefValue::get(Op0->getType()); |
| |
| // If the operation is with the result of a select instruction, check whether |
| // operating on either branch of the select always yields the same value. |
| if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) |
| if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a phi instruction, check whether |
| // operating on all incoming values of the phi always yields the same value. |
| if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) |
| if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| /// SimplifyShlInst - Given operands for an Shl, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| // undef << X -> 0 |
| if (match(Op0, m_Undef())) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // (X >> A) << A -> X |
| Value *X; |
| if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1))))) |
| return X; |
| return 0; |
| } |
| |
| Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, |
| const DataLayout *TD, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// SimplifyLShrInst - Given operands for an LShr, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| // undef >>l X -> 0 |
| if (match(Op0, m_Undef())) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // (X << A) >> A -> X |
| Value *X; |
| if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) && |
| cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap()) |
| return X; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyLShrInst(Op0, Op1, isExact, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// SimplifyAShrInst - Given operands for an AShr, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, |
| const Query &Q, unsigned MaxRecurse) { |
| if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| // all ones >>a X -> all ones |
| if (match(Op0, m_AllOnes())) |
| return Op0; |
| |
| // undef >>a X -> all ones |
| if (match(Op0, m_Undef())) |
| return Constant::getAllOnesValue(Op0->getType()); |
| |
| // (X << A) >> A -> X |
| Value *X; |
| if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) && |
| cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap()) |
| return X; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyAShrInst(Op0, Op1, isExact, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// SimplifyAndInst - Given operands for an And, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) { |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::And, CLHS->getType(), |
| Ops, Q.TD, Q.TLI); |
| } |
| |
| // Canonicalize the constant to the RHS. |
| std::swap(Op0, Op1); |
| } |
| |
| // X & undef -> 0 |
| if (match(Op1, m_Undef())) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // X & X = X |
| if (Op0 == Op1) |
| return Op0; |
| |
| // X & 0 = 0 |
| if (match(Op1, m_Zero())) |
| return Op1; |
| |
| // X & -1 = X |
| if (match(Op1, m_AllOnes())) |
| return Op0; |
| |
| // A & ~A = ~A & A = 0 |
| if (match(Op0, m_Not(m_Specific(Op1))) || |
| match(Op1, m_Not(m_Specific(Op0)))) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // (A | ?) & A = A |
| Value *A = 0, *B = 0; |
| if (match(Op0, m_Or(m_Value(A), m_Value(B))) && |
| (A == Op1 || B == Op1)) |
| return Op1; |
| |
| // A & (A | ?) = A |
| if (match(Op1, m_Or(m_Value(A), m_Value(B))) && |
| (A == Op0 || B == Op0)) |
| return Op0; |
| |
| // A & (-A) = A if A is a power of two or zero. |
| if (match(Op0, m_Neg(m_Specific(Op1))) || |
| match(Op1, m_Neg(m_Specific(Op0)))) { |
| if (isKnownToBeAPowerOfTwo(Op0, /*OrZero*/true)) |
| return Op0; |
| if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/true)) |
| return Op1; |
| } |
| |
| // Try some generic simplifications for associative operations. |
| if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| // And distributes over Or. Try some generic simplifications based on this. |
| if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or, |
| Q, MaxRecurse)) |
| return V; |
| |
| // And distributes over Xor. Try some generic simplifications based on this. |
| if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor, |
| Q, MaxRecurse)) |
| return V; |
| |
| // Or distributes over And. Try some generic simplifications based on this. |
| if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or, |
| Q, MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a select instruction, check whether |
| // operating on either branch of the select always yields the same value. |
| if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) |
| if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a phi instruction, check whether |
| // operating on all incoming values of the phi always yields the same value. |
| if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) |
| if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyAndInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyOrInst - Given operands for an Or, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) { |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(), |
| Ops, Q.TD, Q.TLI); |
| } |
| |
| // Canonicalize the constant to the RHS. |
| std::swap(Op0, Op1); |
| } |
| |
| // X | undef -> -1 |
| if (match(Op1, m_Undef())) |
| return Constant::getAllOnesValue(Op0->getType()); |
| |
| // X | X = X |
| if (Op0 == Op1) |
| return Op0; |
| |
| // X | 0 = X |
| if (match(Op1, m_Zero())) |
| return Op0; |
| |
| // X | -1 = -1 |
| if (match(Op1, m_AllOnes())) |
| return Op1; |
| |
| // A | ~A = ~A | A = -1 |
| if (match(Op0, m_Not(m_Specific(Op1))) || |
| match(Op1, m_Not(m_Specific(Op0)))) |
| return Constant::getAllOnesValue(Op0->getType()); |
| |
| // (A & ?) | A = A |
| Value *A = 0, *B = 0; |
| if (match(Op0, m_And(m_Value(A), m_Value(B))) && |
| (A == Op1 || B == Op1)) |
| return Op1; |
| |
| // A | (A & ?) = A |
| if (match(Op1, m_And(m_Value(A), m_Value(B))) && |
| (A == Op0 || B == Op0)) |
| return Op0; |
| |
| // ~(A & ?) | A = -1 |
| if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) && |
| (A == Op1 || B == Op1)) |
| return Constant::getAllOnesValue(Op1->getType()); |
| |
| // A | ~(A & ?) = -1 |
| if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) && |
| (A == Op0 || B == Op0)) |
| return Constant::getAllOnesValue(Op0->getType()); |
| |
| // Try some generic simplifications for associative operations. |
| if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| // Or distributes over And. Try some generic simplifications based on this. |
| if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q, |
| MaxRecurse)) |
| return V; |
| |
| // And distributes over Or. Try some generic simplifications based on this. |
| if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And, |
| Q, MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a select instruction, check whether |
| // operating on either branch of the select always yields the same value. |
| if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) |
| if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a phi instruction, check whether |
| // operating on all incoming values of the phi always yields the same value. |
| if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) |
| if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyOrInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyXorInst - Given operands for a Xor, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q, |
| unsigned MaxRecurse) { |
| if (Constant *CLHS = dyn_cast<Constant>(Op0)) { |
| if (Constant *CRHS = dyn_cast<Constant>(Op1)) { |
| Constant *Ops[] = { CLHS, CRHS }; |
| return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(), |
| Ops, Q.TD, Q.TLI); |
| } |
| |
| // Canonicalize the constant to the RHS. |
| std::swap(Op0, Op1); |
| } |
| |
| // A ^ undef -> undef |
| if (match(Op1, m_Undef())) |
| return Op1; |
| |
| // A ^ 0 = A |
| if (match(Op1, m_Zero())) |
| return Op0; |
| |
| // A ^ A = 0 |
| if (Op0 == Op1) |
| return Constant::getNullValue(Op0->getType()); |
| |
| // A ^ ~A = ~A ^ A = -1 |
| if (match(Op0, m_Not(m_Specific(Op1))) || |
| match(Op1, m_Not(m_Specific(Op0)))) |
| return Constant::getAllOnesValue(Op0->getType()); |
| |
| // Try some generic simplifications for associative operations. |
| if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, |
| MaxRecurse)) |
| return V; |
| |
| // And distributes over Xor. Try some generic simplifications based on this. |
| if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And, |
| Q, MaxRecurse)) |
| return V; |
| |
| // Threading Xor over selects and phi nodes is pointless, so don't bother. |
| // Threading over the select in "A ^ select(cond, B, C)" means evaluating |
| // "A^B" and "A^C" and seeing if they are equal; but they are equal if and |
| // only if B and C are equal. If B and C are equal then (since we assume |
| // that operands have already been simplified) "select(cond, B, C)" should |
| // have been simplified to the common value of B and C already. Analysing |
| // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly |
| // for threading over phi nodes. |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyXorInst(Op0, Op1, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| static Type *GetCompareTy(Value *Op) { |
| return CmpInst::makeCmpResultType(Op->getType()); |
| } |
| |
| /// ExtractEquivalentCondition - Rummage around inside V looking for something |
| /// equivalent to the comparison "LHS Pred RHS". Return such a value if found, |
| /// otherwise return null. Helper function for analyzing max/min idioms. |
| static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred, |
| Value *LHS, Value *RHS) { |
| SelectInst *SI = dyn_cast<SelectInst>(V); |
| if (!SI) |
| return 0; |
| CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); |
| if (!Cmp) |
| return 0; |
| Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1); |
| if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS) |
| return Cmp; |
| if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) && |
| LHS == CmpRHS && RHS == CmpLHS) |
| return Cmp; |
| return 0; |
| } |
| |
| // A significant optimization not implemented here is assuming that alloca |
| // addresses are not equal to incoming argument values. They don't *alias*, |
| // as we say, but that doesn't mean they aren't equal, so we take a |
| // conservative approach. |
| // |
| // This is inspired in part by C++11 5.10p1: |
| // "Two pointers of the same type compare equal if and only if they are both |
| // null, both point to the same function, or both represent the same |
| // address." |
| // |
| // This is pretty permissive. |
| // |
| // It's also partly due to C11 6.5.9p6: |
| // "Two pointers compare equal if and only if both are null pointers, both are |
| // pointers to the same object (including a pointer to an object and a |
| // subobject at its beginning) or function, both are pointers to one past the |
| // last element of the same array object, or one is a pointer to one past the |
| // end of one array object and the other is a pointer to the start of a |
| // different array object that happens to immediately follow the first array |
| // object in the address space.) |
| // |
| // C11's version is more restrictive, however there's no reason why an argument |
| // couldn't be a one-past-the-end value for a stack object in the caller and be |
| // equal to the beginning of a stack object in the callee. |
| // |
| // If the C and C++ standards are ever made sufficiently restrictive in this |
| // area, it may be possible to update LLVM's semantics accordingly and reinstate |
| // this optimization. |
| static Constant *computePointerICmp(const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| CmpInst::Predicate Pred, |
| Value *LHS, Value *RHS) { |
| // First, skip past any trivial no-ops. |
| LHS = LHS->stripPointerCasts(); |
| RHS = RHS->stripPointerCasts(); |
| |
| // A non-null pointer is not equal to a null pointer. |
| if (llvm::isKnownNonNull(LHS) && isa<ConstantPointerNull>(RHS) && |
| (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE)) |
| return ConstantInt::get(GetCompareTy(LHS), |
| !CmpInst::isTrueWhenEqual(Pred)); |
| |
| // We can only fold certain predicates on pointer comparisons. |
| switch (Pred) { |
| default: |
| return 0; |
| |
| // Equality comaprisons are easy to fold. |
| case CmpInst::ICMP_EQ: |
| case CmpInst::ICMP_NE: |
| break; |
| |
| // We can only handle unsigned relational comparisons because 'inbounds' on |
| // a GEP only protects against unsigned wrapping. |
| case CmpInst::ICMP_UGT: |
| case CmpInst::ICMP_UGE: |
| case CmpInst::ICMP_ULT: |
| case CmpInst::ICMP_ULE: |
| // However, we have to switch them to their signed variants to handle |
| // negative indices from the base pointer. |
| Pred = ICmpInst::getSignedPredicate(Pred); |
| break; |
| } |
| |
| // Strip off any constant offsets so that we can reason about them. |
| // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets |
| // here and compare base addresses like AliasAnalysis does, however there are |
| // numerous hazards. AliasAnalysis and its utilities rely on special rules |
| // governing loads and stores which don't apply to icmps. Also, AliasAnalysis |
| // doesn't need to guarantee pointer inequality when it says NoAlias. |
| ConstantInt *LHSOffset = stripAndComputeConstantOffsets(TD, LHS); |
| ConstantInt *RHSOffset = stripAndComputeConstantOffsets(TD, RHS); |
| |
| // If LHS and RHS are related via constant offsets to the same base |
| // value, we can replace it with an icmp which just compares the offsets. |
| if (LHS == RHS) |
| return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset); |
| |
| // Various optimizations for (in)equality comparisons. |
| if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) { |
| // Different non-empty allocations that exist at the same time have |
| // different addresses (if the program can tell). Global variables always |
| // exist, so they always exist during the lifetime of each other and all |
| // allocas. Two different allocas usually have different addresses... |
| // |
| // However, if there's an @llvm.stackrestore dynamically in between two |
| // allocas, they may have the same address. It's tempting to reduce the |
| // scope of the problem by only looking at *static* allocas here. That would |
| // cover the majority of allocas while significantly reducing the likelihood |
| // of having an @llvm.stackrestore pop up in the middle. However, it's not |
| // actually impossible for an @llvm.stackrestore to pop up in the middle of |
| // an entry block. Also, if we have a block that's not attached to a |
| // function, we can't tell if it's "static" under the current definition. |
| // Theoretically, this problem could be fixed by creating a new kind of |
| // instruction kind specifically for static allocas. Such a new instruction |
| // could be required to be at the top of the entry block, thus preventing it |
| // from being subject to a @llvm.stackrestore. Instcombine could even |
| // convert regular allocas into these special allocas. It'd be nifty. |
| // However, until then, this problem remains open. |
| // |
| // So, we'll assume that two non-empty allocas have different addresses |
| // for now. |
| // |
| // With all that, if the offsets are within the bounds of their allocations |
| // (and not one-past-the-end! so we can't use inbounds!), and their |
| // allocations aren't the same, the pointers are not equal. |
| // |
| // Note that it's not necessary to check for LHS being a global variable |
| // address, due to canonicalization and constant folding. |
| if (isa<AllocaInst>(LHS) && |
| (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) { |
| uint64_t LHSSize, RHSSize; |
| if (getObjectSize(LHS, LHSSize, TD, TLI) && |
| getObjectSize(RHS, RHSSize, TD, TLI)) { |
| const APInt &LHSOffsetValue = LHSOffset->getValue(); |
| const APInt &RHSOffsetValue = RHSOffset->getValue(); |
| if (!LHSOffsetValue.isNegative() && |
| !RHSOffsetValue.isNegative() && |
| LHSOffsetValue.ult(LHSSize) && |
| RHSOffsetValue.ult(RHSSize)) { |
| return ConstantInt::get(GetCompareTy(LHS), |
| !CmpInst::isTrueWhenEqual(Pred)); |
| } |
| } |
| |
| // Repeat the above check but this time without depending on DataLayout |
| // or being able to compute a precise size. |
| if (!cast<PointerType>(LHS->getType())->isEmptyTy() && |
| !cast<PointerType>(RHS->getType())->isEmptyTy() && |
| LHSOffset->isNullValue() && |
| RHSOffset->isNullValue()) |
| return ConstantInt::get(GetCompareTy(LHS), |
| !CmpInst::isTrueWhenEqual(Pred)); |
| } |
| } |
| |
| // Otherwise, fail. |
| return 0; |
| } |
| |
| /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| const Query &Q, unsigned MaxRecurse) { |
| CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; |
| assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); |
| |
| if (Constant *CLHS = dyn_cast<Constant>(LHS)) { |
| if (Constant *CRHS = dyn_cast<Constant>(RHS)) |
| return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI); |
| |
| // If we have a constant, make sure it is on the RHS. |
| std::swap(LHS, RHS); |
| Pred = CmpInst::getSwappedPredicate(Pred); |
| } |
| |
| Type *ITy = GetCompareTy(LHS); // The return type. |
| Type *OpTy = LHS->getType(); // The operand type. |
| |
| // icmp X, X -> true/false |
| // X icmp undef -> true/false. For example, icmp ugt %X, undef -> false |
| // because X could be 0. |
| if (LHS == RHS || isa<UndefValue>(RHS)) |
| return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); |
| |
| // Special case logic when the operands have i1 type. |
| if (OpTy->getScalarType()->isIntegerTy(1)) { |
| switch (Pred) { |
| default: break; |
| case ICmpInst::ICMP_EQ: |
| // X == 1 -> X |
| if (match(RHS, m_One())) |
| return LHS; |
| break; |
| case ICmpInst::ICMP_NE: |
| // X != 0 -> X |
| if (match(RHS, m_Zero())) |
| return LHS; |
| break; |
| case ICmpInst::ICMP_UGT: |
| // X >u 0 -> X |
| if (match(RHS, m_Zero())) |
| return LHS; |
| break; |
| case ICmpInst::ICMP_UGE: |
| // X >=u 1 -> X |
| if (match(RHS, m_One())) |
| return LHS; |
| break; |
| case ICmpInst::ICMP_SLT: |
| // X <s 0 -> X |
| if (match(RHS, m_Zero())) |
| return LHS; |
| break; |
| case ICmpInst::ICMP_SLE: |
| // X <=s -1 -> X |
| if (match(RHS, m_One())) |
| return LHS; |
| break; |
| } |
| } |
| |
| // If we are comparing with zero then try hard since this is a common case. |
| if (match(RHS, m_Zero())) { |
| bool LHSKnownNonNegative, LHSKnownNegative; |
| switch (Pred) { |
| default: llvm_unreachable("Unknown ICmp predicate!"); |
| case ICmpInst::ICMP_ULT: |
| return getFalse(ITy); |
| case ICmpInst::ICMP_UGE: |
| return getTrue(ITy); |
| case ICmpInst::ICMP_EQ: |
| case ICmpInst::ICMP_ULE: |
| if (isKnownNonZero(LHS, Q.TD)) |
| return getFalse(ITy); |
| break; |
| case ICmpInst::ICMP_NE: |
| case ICmpInst::ICMP_UGT: |
| if (isKnownNonZero(LHS, Q.TD)) |
| return getTrue(ITy); |
| break; |
| case ICmpInst::ICMP_SLT: |
| ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); |
| if (LHSKnownNegative) |
| return getTrue(ITy); |
| if (LHSKnownNonNegative) |
| return getFalse(ITy); |
| break; |
| case ICmpInst::ICMP_SLE: |
| ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); |
| if (LHSKnownNegative) |
| return getTrue(ITy); |
| if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD)) |
| return getFalse(ITy); |
| break; |
| case ICmpInst::ICMP_SGE: |
| ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); |
| if (LHSKnownNegative) |
| return getFalse(ITy); |
| if (LHSKnownNonNegative) |
| return getTrue(ITy); |
| break; |
| case ICmpInst::ICMP_SGT: |
| ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.TD); |
| if (LHSKnownNegative) |
| return getFalse(ITy); |
| if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.TD)) |
| return getTrue(ITy); |
| break; |
| } |
| } |
| |
| // See if we are doing a comparison with a constant integer. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { |
| // Rule out tautological comparisons (eg., ult 0 or uge 0). |
| ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue()); |
| if (RHS_CR.isEmptySet()) |
| return ConstantInt::getFalse(CI->getContext()); |
| if (RHS_CR.isFullSet()) |
| return ConstantInt::getTrue(CI->getContext()); |
| |
| // Many binary operators with constant RHS have easy to compute constant |
| // range. Use them to check whether the comparison is a tautology. |
| uint32_t Width = CI->getBitWidth(); |
| APInt Lower = APInt(Width, 0); |
| APInt Upper = APInt(Width, 0); |
| ConstantInt *CI2; |
| if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) { |
| // 'urem x, CI2' produces [0, CI2). |
| Upper = CI2->getValue(); |
| } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) { |
| // 'srem x, CI2' produces (-|CI2|, |CI2|). |
| Upper = CI2->getValue().abs(); |
| Lower = (-Upper) + 1; |
| } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) { |
| // 'udiv CI2, x' produces [0, CI2]. |
| Upper = CI2->getValue() + 1; |
| } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) { |
| // 'udiv x, CI2' produces [0, UINT_MAX / CI2]. |
| APInt NegOne = APInt::getAllOnesValue(Width); |
| if (!CI2->isZero()) |
| Upper = NegOne.udiv(CI2->getValue()) + 1; |
| } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) { |
| // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]. |
| APInt IntMin = APInt::getSignedMinValue(Width); |
| APInt IntMax = APInt::getSignedMaxValue(Width); |
| APInt Val = CI2->getValue().abs(); |
| if (!Val.isMinValue()) { |
| Lower = IntMin.sdiv(Val); |
| Upper = IntMax.sdiv(Val) + 1; |
| } |
| } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) { |
| // 'lshr x, CI2' produces [0, UINT_MAX >> CI2]. |
| APInt NegOne = APInt::getAllOnesValue(Width); |
| if (CI2->getValue().ult(Width)) |
| Upper = NegOne.lshr(CI2->getValue()) + 1; |
| } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) { |
| // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2]. |
| APInt IntMin = APInt::getSignedMinValue(Width); |
| APInt IntMax = APInt::getSignedMaxValue(Width); |
| if (CI2->getValue().ult(Width)) { |
| Lower = IntMin.ashr(CI2->getValue()); |
| Upper = IntMax.ashr(CI2->getValue()) + 1; |
| } |
| } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) { |
| // 'or x, CI2' produces [CI2, UINT_MAX]. |
| Lower = CI2->getValue(); |
| } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) { |
| // 'and x, CI2' produces [0, CI2]. |
| Upper = CI2->getValue() + 1; |
| } |
| if (Lower != Upper) { |
| ConstantRange LHS_CR = ConstantRange(Lower, Upper); |
| if (RHS_CR.contains(LHS_CR)) |
| return ConstantInt::getTrue(RHS->getContext()); |
| if (RHS_CR.inverse().contains(LHS_CR)) |
| return ConstantInt::getFalse(RHS->getContext()); |
| } |
| } |
| |
| // Compare of cast, for example (zext X) != 0 -> X != 0 |
| if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { |
| Instruction *LI = cast<CastInst>(LHS); |
| Value *SrcOp = LI->getOperand(0); |
| Type *SrcTy = SrcOp->getType(); |
| Type *DstTy = LI->getType(); |
| |
| // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input |
| // if the integer type is the same size as the pointer type. |
| if (MaxRecurse && Q.TD && isa<PtrToIntInst>(LI) && |
| Q.TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) { |
| if (Constant *RHSC = dyn_cast<Constant>(RHS)) { |
| // Transfer the cast to the constant. |
| if (Value *V = SimplifyICmpInst(Pred, SrcOp, |
| ConstantExpr::getIntToPtr(RHSC, SrcTy), |
| Q, MaxRecurse-1)) |
| return V; |
| } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { |
| if (RI->getOperand(0)->getType() == SrcTy) |
| // Compare without the cast. |
| if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), |
| Q, MaxRecurse-1)) |
| return V; |
| } |
| } |
| |
| if (isa<ZExtInst>(LHS)) { |
| // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the |
| // same type. |
| if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { |
| if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) |
| // Compare X and Y. Note that signed predicates become unsigned. |
| if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), |
| SrcOp, RI->getOperand(0), Q, |
| MaxRecurse-1)) |
| return V; |
| } |
| // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended |
| // too. If not, then try to deduce the result of the comparison. |
| else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { |
| // Compute the constant that would happen if we truncated to SrcTy then |
| // reextended to DstTy. |
| Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); |
| Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy); |
| |
| // If the re-extended constant didn't change then this is effectively |
| // also a case of comparing two zero-extended values. |
| if (RExt == CI && MaxRecurse) |
| if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), |
| SrcOp, Trunc, Q, MaxRecurse-1)) |
| return V; |
| |
| // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit |
| // there. Use this to work out the result of the comparison. |
| if (RExt != CI) { |
| switch (Pred) { |
| default: llvm_unreachable("Unknown ICmp predicate!"); |
| // LHS <u RHS. |
| case ICmpInst::ICMP_EQ: |
| case ICmpInst::ICMP_UGT: |
| case ICmpInst::ICMP_UGE: |
| return ConstantInt::getFalse(CI->getContext()); |
| |
| case ICmpInst::ICMP_NE: |
| case ICmpInst::ICMP_ULT: |
| case ICmpInst::ICMP_ULE: |
| return ConstantInt::getTrue(CI->getContext()); |
| |
| // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS |
| // is non-negative then LHS <s RHS. |
| case ICmpInst::ICMP_SGT: |
| case ICmpInst::ICMP_SGE: |
| return CI->getValue().isNegative() ? |
| ConstantInt::getTrue(CI->getContext()) : |
| ConstantInt::getFalse(CI->getContext()); |
| |
| case ICmpInst::ICMP_SLT: |
| case ICmpInst::ICMP_SLE: |
| return CI->getValue().isNegative() ? |
| ConstantInt::getFalse(CI->getContext()) : |
| ConstantInt::getTrue(CI->getContext()); |
| } |
| } |
| } |
| } |
| |
| if (isa<SExtInst>(LHS)) { |
| // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the |
| // same type. |
| if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { |
| if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) |
| // Compare X and Y. Note that the predicate does not change. |
| if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), |
| Q, MaxRecurse-1)) |
| return V; |
| } |
| // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended |
| // too. If not, then try to deduce the result of the comparison. |
| else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { |
| // Compute the constant that would happen if we truncated to SrcTy then |
| // reextended to DstTy. |
| Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); |
| Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy); |
| |
| // If the re-extended constant didn't change then this is effectively |
| // also a case of comparing two sign-extended values. |
| if (RExt == CI && MaxRecurse) |
| if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1)) |
| return V; |
| |
| // Otherwise the upper bits of LHS are all equal, while RHS has varying |
| // bits there. Use this to work out the result of the comparison. |
| if (RExt != CI) { |
| switch (Pred) { |
| default: llvm_unreachable("Unknown ICmp predicate!"); |
| case ICmpInst::ICMP_EQ: |
| return ConstantInt::getFalse(CI->getContext()); |
| case ICmpInst::ICMP_NE: |
| return ConstantInt::getTrue(CI->getContext()); |
| |
| // If RHS is non-negative then LHS <s RHS. If RHS is negative then |
| // LHS >s RHS. |
| case ICmpInst::ICMP_SGT: |
| case ICmpInst::ICMP_SGE: |
| return CI->getValue().isNegative() ? |
| ConstantInt::getTrue(CI->getContext()) : |
| ConstantInt::getFalse(CI->getContext()); |
| case ICmpInst::ICMP_SLT: |
| case ICmpInst::ICMP_SLE: |
| return CI->getValue().isNegative() ? |
| ConstantInt::getFalse(CI->getContext()) : |
| ConstantInt::getTrue(CI->getContext()); |
| |
| // If LHS is non-negative then LHS <u RHS. If LHS is negative then |
| // LHS >u RHS. |
| case ICmpInst::ICMP_UGT: |
| case ICmpInst::ICMP_UGE: |
| // Comparison is true iff the LHS <s 0. |
| if (MaxRecurse) |
| if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, |
| Constant::getNullValue(SrcTy), |
| Q, MaxRecurse-1)) |
| return V; |
| break; |
| case ICmpInst::ICMP_ULT: |
| case ICmpInst::ICMP_ULE: |
| // Comparison is true iff the LHS >=s 0. |
| if (MaxRecurse) |
| if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, |
| Constant::getNullValue(SrcTy), |
| Q, MaxRecurse-1)) |
| return V; |
| break; |
| } |
| } |
| } |
| } |
| } |
| |
| // Special logic for binary operators. |
| BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS); |
| BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS); |
| if (MaxRecurse && (LBO || RBO)) { |
| // Analyze the case when either LHS or RHS is an add instruction. |
| Value *A = 0, *B = 0, *C = 0, *D = 0; |
| // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null). |
| bool NoLHSWrapProblem = false, NoRHSWrapProblem = false; |
| if (LBO && LBO->getOpcode() == Instruction::Add) { |
| A = LBO->getOperand(0); B = LBO->getOperand(1); |
| NoLHSWrapProblem = ICmpInst::isEquality(Pred) || |
| (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) || |
| (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap()); |
| } |
| if (RBO && RBO->getOpcode() == Instruction::Add) { |
| C = RBO->getOperand(0); D = RBO->getOperand(1); |
| NoRHSWrapProblem = ICmpInst::isEquality(Pred) || |
| (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) || |
| (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap()); |
| } |
| |
| // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow. |
| if ((A == RHS || B == RHS) && NoLHSWrapProblem) |
| if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A, |
| Constant::getNullValue(RHS->getType()), |
| Q, MaxRecurse-1)) |
| return V; |
| |
| // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow. |
| if ((C == LHS || D == LHS) && NoRHSWrapProblem) |
| if (Value *V = SimplifyICmpInst(Pred, |
| Constant::getNullValue(LHS->getType()), |
| C == LHS ? D : C, Q, MaxRecurse-1)) |
| return V; |
| |
| // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow. |
| if (A && C && (A == C || A == D || B == C || B == D) && |
| NoLHSWrapProblem && NoRHSWrapProblem) { |
| // Determine Y and Z in the form icmp (X+Y), (X+Z). |
| Value *Y, *Z; |
| if (A == C) { |
| // C + B == C + D -> B == D |
| Y = B; |
| Z = D; |
| } else if (A == D) { |
| // D + B == C + D -> B == C |
| Y = B; |
| Z = C; |
| } else if (B == C) { |
| // A + C == C + D -> A == D |
| Y = A; |
| Z = D; |
| } else { |
| assert(B == D); |
| // A + D == C + D -> A == C |
| Y = A; |
| Z = C; |
| } |
| if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1)) |
| return V; |
| } |
| } |
| |
| if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { |
| bool KnownNonNegative, KnownNegative; |
| switch (Pred) { |
| default: |
| break; |
| case ICmpInst::ICMP_SGT: |
| case ICmpInst::ICMP_SGE: |
| ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD); |
| if (!KnownNonNegative) |
| break; |
| // fall-through |
| case ICmpInst::ICMP_EQ: |
| case ICmpInst::ICMP_UGT: |
| case ICmpInst::ICMP_UGE: |
| return getFalse(ITy); |
| case ICmpInst::ICMP_SLT: |
| case ICmpInst::ICMP_SLE: |
| ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.TD); |
| if (!KnownNonNegative) |
| break; |
| // fall-through |
| case ICmpInst::ICMP_NE: |
| case ICmpInst::ICMP_ULT: |
| case ICmpInst::ICMP_ULE: |
| return getTrue(ITy); |
| } |
| } |
| if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) { |
| bool KnownNonNegative, KnownNegative; |
| switch (Pred) { |
| default: |
| break; |
| case ICmpInst::ICMP_SGT: |
| case ICmpInst::ICMP_SGE: |
| ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD); |
| if (!KnownNonNegative) |
| break; |
| // fall-through |
| case ICmpInst::ICMP_NE: |
| case ICmpInst::ICMP_UGT: |
| case ICmpInst::ICMP_UGE: |
| return getTrue(ITy); |
| case ICmpInst::ICMP_SLT: |
| case ICmpInst::ICMP_SLE: |
| ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.TD); |
| if (!KnownNonNegative) |
| break; |
| // fall-through |
| case ICmpInst::ICMP_EQ: |
| case ICmpInst::ICMP_ULT: |
| case ICmpInst::ICMP_ULE: |
| return getFalse(ITy); |
| } |
| } |
| |
| // x udiv y <=u x. |
| if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) { |
| // icmp pred (X /u Y), X |
| if (Pred == ICmpInst::ICMP_UGT) |
| return getFalse(ITy); |
| if (Pred == ICmpInst::ICMP_ULE) |
| return getTrue(ITy); |
| } |
| |
| if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() && |
| LBO->getOperand(1) == RBO->getOperand(1)) { |
| switch (LBO->getOpcode()) { |
| default: break; |
| case Instruction::UDiv: |
| case Instruction::LShr: |
| if (ICmpInst::isSigned(Pred)) |
| break; |
| // fall-through |
| case Instruction::SDiv: |
| case Instruction::AShr: |
| if (!LBO->isExact() || !RBO->isExact()) |
| break; |
| if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), |
| RBO->getOperand(0), Q, MaxRecurse-1)) |
| return V; |
| break; |
| case Instruction::Shl: { |
| bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap(); |
| bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap(); |
| if (!NUW && !NSW) |
| break; |
| if (!NSW && ICmpInst::isSigned(Pred)) |
| break; |
| if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), |
| RBO->getOperand(0), Q, MaxRecurse-1)) |
| return V; |
| break; |
| } |
| } |
| } |
| |
| // Simplify comparisons involving max/min. |
| Value *A, *B; |
| CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE; |
| CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B". |
| |
| // Signed variants on "max(a,b)>=a -> true". |
| if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { |
| if (A != RHS) std::swap(A, B); // smax(A, B) pred A. |
| EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". |
| // We analyze this as smax(A, B) pred A. |
| P = Pred; |
| } else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) && |
| (A == LHS || B == LHS)) { |
| if (A != LHS) std::swap(A, B); // A pred smax(A, B). |
| EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B". |
| // We analyze this as smax(A, B) swapped-pred A. |
| P = CmpInst::getSwappedPredicate(Pred); |
| } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && |
| (A == RHS || B == RHS)) { |
| if (A != RHS) std::swap(A, B); // smin(A, B) pred A. |
| EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". |
| // We analyze this as smax(-A, -B) swapped-pred -A. |
| // Note that we do not need to actually form -A or -B thanks to EqP. |
| P = CmpInst::getSwappedPredicate(Pred); |
| } else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) && |
| (A == LHS || B == LHS)) { |
| if (A != LHS) std::swap(A, B); // A pred smin(A, B). |
| EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B". |
| // We analyze this as smax(-A, -B) pred -A. |
| // Note that we do not need to actually form -A or -B thanks to EqP. |
| P = Pred; |
| } |
| if (P != CmpInst::BAD_ICMP_PREDICATE) { |
| // Cases correspond to "max(A, B) p A". |
| switch (P) { |
| default: |
| break; |
| case CmpInst::ICMP_EQ: |
| case CmpInst::ICMP_SLE: |
| // Equivalent to "A EqP B". This may be the same as the condition tested |
| // in the max/min; if so, we can just return that. |
| if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) |
| return V; |
| if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) |
| return V; |
| // Otherwise, see if "A EqP B" simplifies. |
| if (MaxRecurse) |
| if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1)) |
| return V; |
| break; |
| case CmpInst::ICMP_NE: |
| case CmpInst::ICMP_SGT: { |
| CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); |
| // Equivalent to "A InvEqP B". This may be the same as the condition |
| // tested in the max/min; if so, we can just return that. |
| if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) |
| return V; |
| if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) |
| return V; |
| // Otherwise, see if "A InvEqP B" simplifies. |
| if (MaxRecurse) |
| if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1)) |
| return V; |
| break; |
| } |
| case CmpInst::ICMP_SGE: |
| // Always true. |
| return getTrue(ITy); |
| case CmpInst::ICMP_SLT: |
| // Always false. |
| return getFalse(ITy); |
| } |
| } |
| |
| // Unsigned variants on "max(a,b)>=a -> true". |
| P = CmpInst::BAD_ICMP_PREDICATE; |
| if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) { |
| if (A != RHS) std::swap(A, B); // umax(A, B) pred A. |
| EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". |
| // We analyze this as umax(A, B) pred A. |
| P = Pred; |
| } else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) && |
| (A == LHS || B == LHS)) { |
| if (A != LHS) std::swap(A, B); // A pred umax(A, B). |
| EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B". |
| // We analyze this as umax(A, B) swapped-pred A. |
| P = CmpInst::getSwappedPredicate(Pred); |
| } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && |
| (A == RHS || B == RHS)) { |
| if (A != RHS) std::swap(A, B); // umin(A, B) pred A. |
| EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". |
| // We analyze this as umax(-A, -B) swapped-pred -A. |
| // Note that we do not need to actually form -A or -B thanks to EqP. |
| P = CmpInst::getSwappedPredicate(Pred); |
| } else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) && |
| (A == LHS || B == LHS)) { |
| if (A != LHS) std::swap(A, B); // A pred umin(A, B). |
| EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B". |
| // We analyze this as umax(-A, -B) pred -A. |
| // Note that we do not need to actually form -A or -B thanks to EqP. |
| P = Pred; |
| } |
| if (P != CmpInst::BAD_ICMP_PREDICATE) { |
| // Cases correspond to "max(A, B) p A". |
| switch (P) { |
| default: |
| break; |
| case CmpInst::ICMP_EQ: |
| case CmpInst::ICMP_ULE: |
| // Equivalent to "A EqP B". This may be the same as the condition tested |
| // in the max/min; if so, we can just return that. |
| if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B)) |
| return V; |
| if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B)) |
| return V; |
| // Otherwise, see if "A EqP B" simplifies. |
| if (MaxRecurse) |
| if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1)) |
| return V; |
| break; |
| case CmpInst::ICMP_NE: |
| case CmpInst::ICMP_UGT: { |
| CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP); |
| // Equivalent to "A InvEqP B". This may be the same as the condition |
| // tested in the max/min; if so, we can just return that. |
| if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B)) |
| return V; |
| if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B)) |
| return V; |
| // Otherwise, see if "A InvEqP B" simplifies. |
| if (MaxRecurse) |
| if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1)) |
| return V; |
| break; |
| } |
| case CmpInst::ICMP_UGE: |
| // Always true. |
| return getTrue(ITy); |
| case CmpInst::ICMP_ULT: |
| // Always false. |
| return getFalse(ITy); |
| } |
| } |
| |
| // Variants on "max(x,y) >= min(x,z)". |
| Value *C, *D; |
| if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && |
| match(RHS, m_SMin(m_Value(C), m_Value(D))) && |
| (A == C || A == D || B == C || B == D)) { |
| // max(x, ?) pred min(x, ?). |
| if (Pred == CmpInst::ICMP_SGE) |
| // Always true. |
| return getTrue(ITy); |
| if (Pred == CmpInst::ICMP_SLT) |
| // Always false. |
| return getFalse(ITy); |
| } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && |
| match(RHS, m_SMax(m_Value(C), m_Value(D))) && |
| (A == C || A == D || B == C || B == D)) { |
| // min(x, ?) pred max(x, ?). |
| if (Pred == CmpInst::ICMP_SLE) |
| // Always true. |
| return getTrue(ITy); |
| if (Pred == CmpInst::ICMP_SGT) |
| // Always false. |
| return getFalse(ITy); |
| } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && |
| match(RHS, m_UMin(m_Value(C), m_Value(D))) && |
| (A == C || A == D || B == C || B == D)) { |
| // max(x, ?) pred min(x, ?). |
| if (Pred == CmpInst::ICMP_UGE) |
| // Always true. |
| return getTrue(ITy); |
| if (Pred == CmpInst::ICMP_ULT) |
| // Always false. |
| return getFalse(ITy); |
| } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && |
| match(RHS, m_UMax(m_Value(C), m_Value(D))) && |
| (A == C || A == D || B == C || B == D)) { |
| // min(x, ?) pred max(x, ?). |
| if (Pred == CmpInst::ICMP_ULE) |
| // Always true. |
| return getTrue(ITy); |
| if (Pred == CmpInst::ICMP_UGT) |
| // Always false. |
| return getFalse(ITy); |
| } |
| |
| // Simplify comparisons of related pointers using a powerful, recursive |
| // GEP-walk when we have target data available.. |
| if (LHS->getType()->isPointerTy()) |
| if (Constant *C = computePointerICmp(Q.TD, Q.TLI, Pred, LHS, RHS)) |
| return C; |
| |
| if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) { |
| if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) { |
| if (GLHS->getPointerOperand() == GRHS->getPointerOperand() && |
| GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() && |
| (ICmpInst::isEquality(Pred) || |
| (GLHS->isInBounds() && GRHS->isInBounds() && |
| Pred == ICmpInst::getSignedPredicate(Pred)))) { |
| // The bases are equal and the indices are constant. Build a constant |
| // expression GEP with the same indices and a null base pointer to see |
| // what constant folding can make out of it. |
| Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType()); |
| SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end()); |
| Constant *NewLHS = ConstantExpr::getGetElementPtr(Null, IndicesLHS); |
| |
| SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end()); |
| Constant *NewRHS = ConstantExpr::getGetElementPtr(Null, IndicesRHS); |
| return ConstantExpr::getICmp(Pred, NewLHS, NewRHS); |
| } |
| } |
| } |
| |
| // If the comparison is with the result of a select instruction, check whether |
| // comparing with either branch of the select always yields the same value. |
| if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) |
| if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) |
| return V; |
| |
| // If the comparison is with the result of a phi instruction, check whether |
| // doing the compare with each incoming phi value yields a common result. |
| if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) |
| if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyICmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| const Query &Q, unsigned MaxRecurse) { |
| CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; |
| assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); |
| |
| if (Constant *CLHS = dyn_cast<Constant>(LHS)) { |
| if (Constant *CRHS = dyn_cast<Constant>(RHS)) |
| return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.TD, Q.TLI); |
| |
| // If we have a constant, make sure it is on the RHS. |
| std::swap(LHS, RHS); |
| Pred = CmpInst::getSwappedPredicate(Pred); |
| } |
| |
| // Fold trivial predicates. |
| if (Pred == FCmpInst::FCMP_FALSE) |
| return ConstantInt::get(GetCompareTy(LHS), 0); |
| if (Pred == FCmpInst::FCMP_TRUE) |
| return ConstantInt::get(GetCompareTy(LHS), 1); |
| |
| if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef |
| return UndefValue::get(GetCompareTy(LHS)); |
| |
| // fcmp x,x -> true/false. Not all compares are foldable. |
| if (LHS == RHS) { |
| if (CmpInst::isTrueWhenEqual(Pred)) |
| return ConstantInt::get(GetCompareTy(LHS), 1); |
| if (CmpInst::isFalseWhenEqual(Pred)) |
| return ConstantInt::get(GetCompareTy(LHS), 0); |
| } |
| |
| // Handle fcmp with constant RHS |
| if (Constant *RHSC = dyn_cast<Constant>(RHS)) { |
| // If the constant is a nan, see if we can fold the comparison based on it. |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) { |
| if (CFP->getValueAPF().isNaN()) { |
| if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo" |
| return ConstantInt::getFalse(CFP->getContext()); |
| assert(FCmpInst::isUnordered(Pred) && |
| "Comparison must be either ordered or unordered!"); |
| // True if unordered. |
| return ConstantInt::getTrue(CFP->getContext()); |
| } |
| // Check whether the constant is an infinity. |
| if (CFP->getValueAPF().isInfinity()) { |
| if (CFP->getValueAPF().isNegative()) { |
| switch (Pred) { |
| case FCmpInst::FCMP_OLT: |
| // No value is ordered and less than negative infinity. |
| return ConstantInt::getFalse(CFP->getContext()); |
| case FCmpInst::FCMP_UGE: |
| // All values are unordered with or at least negative infinity. |
| return ConstantInt::getTrue(CFP->getContext()); |
| default: |
| break; |
| } |
| } else { |
| switch (Pred) { |
| case FCmpInst::FCMP_OGT: |
| // No value is ordered and greater than infinity. |
| return ConstantInt::getFalse(CFP->getContext()); |
| case FCmpInst::FCMP_ULE: |
| // All values are unordered with and at most infinity. |
| return ConstantInt::getTrue(CFP->getContext()); |
| default: |
| break; |
| } |
| } |
| } |
| } |
| } |
| |
| // If the comparison is with the result of a select instruction, check whether |
| // comparing with either branch of the select always yields the same value. |
| if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) |
| if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) |
| return V; |
| |
| // If the comparison is with the result of a phi instruction, check whether |
| // doing the compare with each incoming phi value yields a common result. |
| if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) |
| if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyFCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold |
| /// the result. If not, this returns null. |
| static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal, |
| Value *FalseVal, const Query &Q, |
| unsigned MaxRecurse) { |
| // select true, X, Y -> X |
| // select false, X, Y -> Y |
| if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal)) |
| return CB->getZExtValue() ? TrueVal : FalseVal; |
| |
| // select C, X, X -> X |
| if (TrueVal == FalseVal) |
| return TrueVal; |
| |
| if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y |
| if (isa<Constant>(TrueVal)) |
| return TrueVal; |
| return FalseVal; |
| } |
| if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X |
| return FalseVal; |
| if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X |
| return TrueVal; |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyGEPInst(ArrayRef<Value *> Ops, const Query &Q, unsigned) { |
| // The type of the GEP pointer operand. |
| PointerType *PtrTy = dyn_cast<PointerType>(Ops[0]->getType()); |
| // The GEP pointer operand is not a pointer, it's a vector of pointers. |
| if (!PtrTy) |
| return 0; |
| |
| // getelementptr P -> P. |
| if (Ops.size() == 1) |
| return Ops[0]; |
| |
| if (isa<UndefValue>(Ops[0])) { |
| // Compute the (pointer) type returned by the GEP instruction. |
| Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, Ops.slice(1)); |
| Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace()); |
| return UndefValue::get(GEPTy); |
| } |
| |
| if (Ops.size() == 2) { |
| // getelementptr P, 0 -> P. |
| if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1])) |
| if (C->isZero()) |
| return Ops[0]; |
| // getelementptr P, N -> P if P points to a type of zero size. |
| if (Q.TD) { |
| Type *Ty = PtrTy->getElementType(); |
| if (Ty->isSized() && Q.TD->getTypeAllocSize(Ty) == 0) |
| return Ops[0]; |
| } |
| } |
| |
| // Check to see if this is constant foldable. |
| for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| if (!isa<Constant>(Ops[i])) |
| return 0; |
| |
| return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), Ops.slice(1)); |
| } |
| |
| Value *llvm::SimplifyGEPInst(ArrayRef<Value *> Ops, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyGEPInst(Ops, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyInsertValueInst - Given operands for an InsertValueInst, see if we |
| /// can fold the result. If not, this returns null. |
| static Value *SimplifyInsertValueInst(Value *Agg, Value *Val, |
| ArrayRef<unsigned> Idxs, const Query &Q, |
| unsigned) { |
| if (Constant *CAgg = dyn_cast<Constant>(Agg)) |
| if (Constant *CVal = dyn_cast<Constant>(Val)) |
| return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs); |
| |
| // insertvalue x, undef, n -> x |
| if (match(Val, m_Undef())) |
| return Agg; |
| |
| // insertvalue x, (extractvalue y, n), n |
| if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) |
| if (EV->getAggregateOperand()->getType() == Agg->getType() && |
| EV->getIndices() == Idxs) { |
| // insertvalue undef, (extractvalue y, n), n -> y |
| if (match(Agg, m_Undef())) |
| return EV->getAggregateOperand(); |
| |
| // insertvalue y, (extractvalue y, n), n -> y |
| if (Agg == EV->getAggregateOperand()) |
| return Agg; |
| } |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val, |
| ArrayRef<unsigned> Idxs, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// SimplifyPHINode - See if we can fold the given phi. If not, returns null. |
| static Value *SimplifyPHINode(PHINode *PN, const Query &Q) { |
| // If all of the PHI's incoming values are the same then replace the PHI node |
| // with the common value. |
| Value *CommonValue = 0; |
| bool HasUndefInput = false; |
| for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
| Value *Incoming = PN->getIncomingValue(i); |
| // If the incoming value is the phi node itself, it can safely be skipped. |
| if (Incoming == PN) continue; |
| if (isa<UndefValue>(Incoming)) { |
| // Remember that we saw an undef value, but otherwise ignore them. |
| HasUndefInput = true; |
| continue; |
| } |
| if (CommonValue && Incoming != CommonValue) |
| return 0; // Not the same, bail out. |
| CommonValue = Incoming; |
| } |
| |
| // If CommonValue is null then all of the incoming values were either undef or |
| // equal to the phi node itself. |
| if (!CommonValue) |
| return UndefValue::get(PN->getType()); |
| |
| // If we have a PHI node like phi(X, undef, X), where X is defined by some |
| // instruction, we cannot return X as the result of the PHI node unless it |
| // dominates the PHI block. |
| if (HasUndefInput) |
| return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : 0; |
| |
| return CommonValue; |
| } |
| |
| static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) { |
| if (Constant *C = dyn_cast<Constant>(Op)) |
| return ConstantFoldInstOperands(Instruction::Trunc, Ty, C, Q.TD, Q.TLI); |
| |
| return 0; |
| } |
| |
| Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyTruncInst(Op, Ty, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| //=== Helper functions for higher up the class hierarchy. |
| |
| /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can |
| /// fold the result. If not, this returns null. |
| static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, |
| const Query &Q, unsigned MaxRecurse) { |
| switch (Opcode) { |
| case Instruction::Add: |
| return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, |
| Q, MaxRecurse); |
| case Instruction::FAdd: |
| return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); |
| |
| case Instruction::Sub: |
| return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, |
| Q, MaxRecurse); |
| case Instruction::FSub: |
| return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); |
| |
| case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse); |
| case Instruction::FMul: |
| return SimplifyFMulInst (LHS, RHS, FastMathFlags(), Q, MaxRecurse); |
| case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse); |
| case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse); |
| case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, Q, MaxRecurse); |
| case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse); |
| case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse); |
| case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, Q, MaxRecurse); |
| case Instruction::Shl: |
| return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, |
| Q, MaxRecurse); |
| case Instruction::LShr: |
| return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse); |
| case Instruction::AShr: |
| return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse); |
| case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse); |
| case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse); |
| case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse); |
| default: |
| if (Constant *CLHS = dyn_cast<Constant>(LHS)) |
| if (Constant *CRHS = dyn_cast<Constant>(RHS)) { |
| Constant *COps[] = {CLHS, CRHS}; |
| return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, Q.TD, |
| Q.TLI); |
| } |
| |
| // If the operation is associative, try some generic simplifications. |
| if (Instruction::isAssociative(Opcode)) |
| if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a select instruction check whether |
| // operating on either branch of the select always yields the same value. |
| if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) |
| if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse)) |
| return V; |
| |
| // If the operation is with the result of a phi instruction, check whether |
| // operating on all incoming values of the phi always yields the same value. |
| if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) |
| if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse)) |
| return V; |
| |
| return 0; |
| } |
| } |
| |
| Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, |
| const DataLayout *TD, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyBinOp(Opcode, LHS, RHS, Query (TD, TLI, DT), RecursionLimit); |
| } |
| |
| /// SimplifyCmpInst - Given operands for a CmpInst, see if we can |
| /// fold the result. |
| static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| const Query &Q, unsigned MaxRecurse) { |
| if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) |
| return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); |
| return SimplifyFCmpInst(Predicate, LHS, RHS, Q, MaxRecurse); |
| } |
| |
| Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| const DataLayout *TD, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyCmpInst(Predicate, LHS, RHS, Query (TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| template <typename IterTy> |
| static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd, |
| const Query &Q, unsigned MaxRecurse) { |
| Type *Ty = V->getType(); |
| if (PointerType *PTy = dyn_cast<PointerType>(Ty)) |
| Ty = PTy->getElementType(); |
| FunctionType *FTy = cast<FunctionType>(Ty); |
| |
| // call undef -> undef |
| if (isa<UndefValue>(V)) |
| return UndefValue::get(FTy->getReturnType()); |
| |
| Function *F = dyn_cast<Function>(V); |
| if (!F) |
| return 0; |
| |
| if (!canConstantFoldCallTo(F)) |
| return 0; |
| |
| SmallVector<Constant *, 4> ConstantArgs; |
| ConstantArgs.reserve(ArgEnd - ArgBegin); |
| for (IterTy I = ArgBegin, E = ArgEnd; I != E; ++I) { |
| Constant *C = dyn_cast<Constant>(*I); |
| if (!C) |
| return 0; |
| ConstantArgs.push_back(C); |
| } |
| |
| return ConstantFoldCall(F, ConstantArgs, Q.TLI); |
| } |
| |
| Value *llvm::SimplifyCall(Value *V, User::op_iterator ArgBegin, |
| User::op_iterator ArgEnd, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyCall(V, ArgBegin, ArgEnd, Query(TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| Value *llvm::SimplifyCall(Value *V, ArrayRef<Value *> Args, |
| const DataLayout *TD, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return ::SimplifyCall(V, Args.begin(), Args.end(), Query(TD, TLI, DT), |
| RecursionLimit); |
| } |
| |
| /// SimplifyInstruction - See if we can compute a simplified version of this |
| /// instruction. If not, this returns null. |
| Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| Value *Result; |
| |
| switch (I->getOpcode()) { |
| default: |
| Result = ConstantFoldInstruction(I, TD, TLI); |
| break; |
| case Instruction::FAdd: |
| Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1), |
| I->getFastMathFlags(), TD, TLI, DT); |
| break; |
| case Instruction::Add: |
| Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1), |
| cast<BinaryOperator>(I)->hasNoSignedWrap(), |
| cast<BinaryOperator>(I)->hasNoUnsignedWrap(), |
| TD, TLI, DT); |
| break; |
| case Instruction::FSub: |
| Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1), |
| I->getFastMathFlags(), TD, TLI, DT); |
| break; |
| case Instruction::Sub: |
| Result = SimplifySubInst(I->getOperand(0), I->getOperand(1), |
| cast<BinaryOperator>(I)->hasNoSignedWrap(), |
| cast<BinaryOperator>(I)->hasNoUnsignedWrap(), |
| TD, TLI, DT); |
| break; |
| case Instruction::FMul: |
| Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1), |
| I->getFastMathFlags(), TD, TLI, DT); |
| break; |
| case Instruction::Mul: |
| Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::SDiv: |
| Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::UDiv: |
| Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::FDiv: |
| Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::SRem: |
| Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::URem: |
| Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::FRem: |
| Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::Shl: |
| Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1), |
| cast<BinaryOperator>(I)->hasNoSignedWrap(), |
| cast<BinaryOperator>(I)->hasNoUnsignedWrap(), |
| TD, TLI, DT); |
| break; |
| case Instruction::LShr: |
| Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), |
| cast<BinaryOperator>(I)->isExact(), |
| TD, TLI, DT); |
| break; |
| case Instruction::AShr: |
| Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), |
| cast<BinaryOperator>(I)->isExact(), |
| TD, TLI, DT); |
| break; |
| case Instruction::And: |
| Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::Or: |
| Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::Xor: |
| Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::ICmp: |
| Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), |
| I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::FCmp: |
| Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), |
| I->getOperand(0), I->getOperand(1), TD, TLI, DT); |
| break; |
| case Instruction::Select: |
| Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1), |
| I->getOperand(2), TD, TLI, DT); |
| break; |
| case Instruction::GetElementPtr: { |
| SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end()); |
| Result = SimplifyGEPInst(Ops, TD, TLI, DT); |
| break; |
| } |
| case Instruction::InsertValue: { |
| InsertValueInst *IV = cast<InsertValueInst>(I); |
| Result = SimplifyInsertValueInst(IV->getAggregateOperand(), |
| IV->getInsertedValueOperand(), |
| IV->getIndices(), TD, TLI, DT); |
| break; |
| } |
| case Instruction::PHI: |
| Result = SimplifyPHINode(cast<PHINode>(I), Query (TD, TLI, DT)); |
| break; |
| case Instruction::Call: { |
| CallSite CS(cast<CallInst>(I)); |
| Result = SimplifyCall(CS.getCalledValue(), CS.arg_begin(), CS.arg_end(), |
| TD, TLI, DT); |
| break; |
| } |
| case Instruction::Trunc: |
| Result = SimplifyTruncInst(I->getOperand(0), I->getType(), TD, TLI, DT); |
| break; |
| } |
| |
| /// If called on unreachable code, the above logic may report that the |
| /// instruction simplified to itself. Make life easier for users by |
| /// detecting that case here, returning a safe value instead. |
| return Result == I ? UndefValue::get(I->getType()) : Result; |
| } |
| |
| /// \brief Implementation of recursive simplification through an instructions |
| /// uses. |
| /// |
| /// This is the common implementation of the recursive simplification routines. |
| /// If we have a pre-simplified value in 'SimpleV', that is forcibly used to |
| /// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of |
| /// instructions to process and attempt to simplify it using |
| /// InstructionSimplify. |
| /// |
| /// This routine returns 'true' only when *it* simplifies something. The passed |
| /// in simplified value does not count toward this. |
| static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| bool Simplified = false; |
| SmallSetVector<Instruction *, 8> Worklist; |
| |
| // If we have an explicit value to collapse to, do that round of the |
| // simplification loop by hand initially. |
| if (SimpleV) { |
| for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE; |
| ++UI) |
| if (*UI != I) |
| Worklist.insert(cast<Instruction>(*UI)); |
| |
| // Replace the instruction with its simplified value. |
| I->replaceAllUsesWith(SimpleV); |
| |
| // Gracefully handle edge cases where the instruction is not wired into any |
| // parent block. |
| if (I->getParent()) |
| I->eraseFromParent(); |
| } else { |
| Worklist.insert(I); |
| } |
| |
| // Note that we must test the size on each iteration, the worklist can grow. |
| for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { |
| I = Worklist[Idx]; |
| |
| // See if this instruction simplifies. |
| SimpleV = SimplifyInstruction(I, TD, TLI, DT); |
| if (!SimpleV) |
| continue; |
| |
| Simplified = true; |
| |
| // Stash away all the uses of the old instruction so we can check them for |
| // recursive simplifications after a RAUW. This is cheaper than checking all |
| // uses of To on the recursive step in most cases. |
| for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE; |
| ++UI) |
| Worklist.insert(cast<Instruction>(*UI)); |
| |
| // Replace the instruction with its simplified value. |
| I->replaceAllUsesWith(SimpleV); |
| |
| // Gracefully handle edge cases where the instruction is not wired into any |
| // parent block. |
| if (I->getParent()) |
| I->eraseFromParent(); |
| } |
| return Simplified; |
| } |
| |
| bool llvm::recursivelySimplifyInstruction(Instruction *I, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| return replaceAndRecursivelySimplifyImpl(I, 0, TD, TLI, DT); |
| } |
| |
| bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| const DominatorTree *DT) { |
| assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!"); |
| assert(SimpleV && "Must provide a simplified value."); |
| return replaceAndRecursivelySimplifyImpl(I, SimpleV, TD, TLI, DT); |
| } |