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Diffstat (limited to 'contrib/llvm/lib/Analysis/InstructionSimplify.cpp')
| -rw-r--r-- | contrib/llvm/lib/Analysis/InstructionSimplify.cpp | 1904 |
1 files changed, 1745 insertions, 159 deletions
diff --git a/contrib/llvm/lib/Analysis/InstructionSimplify.cpp b/contrib/llvm/lib/Analysis/InstructionSimplify.cpp index 24cd343..a2f9862 100644 --- a/contrib/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/contrib/llvm/lib/Analysis/InstructionSimplify.cpp @@ -8,179 +8,1267 @@ //===----------------------------------------------------------------------===// // // This file implements routines for folding instructions into simpler forms -// that do not require creating new instructions. For example, this does -// constant folding, and can handle identities like (X&0)->0. +// 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/ADT/Statistic.h" #include "llvm/Analysis/InstructionSimplify.h" #include "llvm/Analysis/ConstantFolding.h" -#include "llvm/Support/ValueHandle.h" -#include "llvm/Instructions.h" +#include "llvm/Analysis/Dominators.h" +#include "llvm/Analysis/ValueTracking.h" #include "llvm/Support/PatternMatch.h" +#include "llvm/Support/ValueHandle.h" +#include "llvm/Target/TargetData.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"); + +static Value *SimplifyAndInst(Value *, Value *, const TargetData *, + const DominatorTree *, unsigned); +static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *, + const DominatorTree *, unsigned); +static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *, + const DominatorTree *, unsigned); +static Value *SimplifyOrInst(Value *, Value *, const TargetData *, + const DominatorTree *, unsigned); +static Value *SimplifyXorInst(Value *, Value *, const TargetData *, + const DominatorTree *, unsigned); + +/// 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 have a DominatorTree then do a precise test. + if (DT) + 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 TargetData *TD, + const DominatorTree *DT, 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, TD, DT, MaxRecurse)) + if (Value *R = SimplifyBinOp(Opcode, B, C, TD, DT, 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, TD, DT, + 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, TD, DT, MaxRecurse)) + if (Value *R = SimplifyBinOp(Opcode, A, C, TD, DT, 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, TD, DT, + 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 TargetData *TD, + const DominatorTree *DT, 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, TD, DT, 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, TD, DT, 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, TD, DT, 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, TD, DT, 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 TargetData *TD, + const DominatorTree *DT, + 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, TD, DT, 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, TD, DT, 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, TD, DT, 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, TD, DT, 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, TD, DT, 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, TD, DT, 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, TD, DT, 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, TD, DT, 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 TargetData *TD, + const DominatorTree *DT, + 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, TD, DT, MaxRecurse); + FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, DT, MaxRecurse); + } else { + TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, DT, MaxRecurse); + FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, DT, 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 TargetData *TD, + const DominatorTree *DT, + 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); + + // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it. + // Does "cmp TV, RHS" simplify? + if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT, + MaxRecurse)) { + // It does! Does "cmp FV, RHS" simplify? + if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT, + MaxRecurse)) { + // It does! If they simplified to the same value, then use it as the + // result of the original comparison. + if (TCmp == FCmp) + return TCmp; + Value *Cond = SI->getCondition(); + // 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, TD, DT, 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, TD, DT, 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()), + TD, DT, 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 TargetData *TD, const DominatorTree *DT, + 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, 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, 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, TD, DT, MaxRecurse) : + SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, 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 TargetData *TD, const DominatorTree *DT, + 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, 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, TD, DT, 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. -Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, - const TargetData *TD) { +static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, + const TargetData *TD, const DominatorTree *DT, + 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, 2, TD); } - + + // 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, TD, DT, MaxRecurse-1)) + return V; + + // Try some generic simplifications for associative operations. + if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT, + MaxRecurse)) + return V; + + // Mul distributes over Add. Try some generic simplifications based on this. + if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul, + TD, DT, 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 TargetData *TD, const DominatorTree *DT) { + return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit); +} + +/// 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 TargetData *TD, const DominatorTree *DT, + 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, 2, TD); + } + + // 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, TD, DT, MaxRecurse-1)) + // It does! Now see if "X + V" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, DT, + MaxRecurse-1)) { + // It does, we successfully reassociated! + ++NumReassoc; + return W; + } + // See if "V === X - Z" simplifies. + if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1)) + // It does! Now see if "Y + V" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, DT, + 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, TD, DT, MaxRecurse-1)) + // It does! Now see if "V - Z" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, DT, + MaxRecurse-1)) { + // It does, we successfully reassociated! + ++NumReassoc; + return W; + } + // See if "V === X - Z" simplifies. + if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1)) + // It does! Now see if "V - Y" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, DT, + 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, TD, DT, MaxRecurse-1)) + // It does! Now see if "V + Y" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, DT, + MaxRecurse-1)) { + // It does, we successfully reassociated! + ++NumReassoc; + return W; + } + + // Mul distributes over Sub. Try some generic simplifications based on this. + if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul, + TD, DT, MaxRecurse)) + return V; + + // i1 sub -> xor. + if (MaxRecurse && Op0->getType()->isIntegerTy(1)) + if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, 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 TargetData *TD, const DominatorTree *DT) { + return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit); +} + +/// 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 TargetData *TD, + const DominatorTree *DT, 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, 2, TD); + } + // Canonicalize the constant to the RHS. std::swap(Op0, Op1); } - - if (Constant *Op1C = dyn_cast<Constant>(Op1)) { - // X + undef -> undef - if (isa<UndefValue>(Op1C)) - return Op1C; - - // X + 0 --> X - if (Op1C->isNullValue()) - return Op0; - } - - // FIXME: Could pull several more out of instcombine. + + // 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, *Y = 0; + if ((match(Op0, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y + (match(Op1, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y) + BinaryOperator *Div = cast<BinaryOperator>(Y == Op1 ? Op0 : Op1); + if (Div->isExact()) + return X; + } + + // i1 mul -> and. + if (MaxRecurse && Op0->getType()->isIntegerTy(1)) + if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1)) + return V; + + // Try some generic simplifications for associative operations. + if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT, + MaxRecurse)) + return V; + + // Mul distributes over Add. Try some generic simplifications based on this. + if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add, + TD, DT, 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, TD, DT, + 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, TD, DT, + MaxRecurse)) + return V; + + return 0; +} + +Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD, + const DominatorTree *DT) { + return ::SimplifyMulInst(Op0, Op1, TD, 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 TargetData *TD, const DominatorTree *DT, + 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, 2, TD); + } + } + + 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 + BinaryOperator *Mul = cast<BinaryOperator>(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, TD, DT, 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, TD, DT, 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 TargetData *TD, + const DominatorTree *DT, unsigned MaxRecurse) { + if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, DT, MaxRecurse)) + return V; + + return 0; +} + +Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD, + const DominatorTree *DT) { + return ::SimplifySDivInst(Op0, Op1, TD, 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 TargetData *TD, + const DominatorTree *DT, unsigned MaxRecurse) { + if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, DT, MaxRecurse)) + return V; + + return 0; +} + +Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD, + const DominatorTree *DT) { + return ::SimplifyUDivInst(Op0, Op1, TD, DT, RecursionLimit); +} + +static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *, + const DominatorTree *, 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 TargetData *TD, + const DominatorTree *DT) { + return ::SimplifyFDivInst(Op0, Op1, TD, 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 TargetData *TD, const DominatorTree *DT, + 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, 2, TD); + } + } + + // 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, TD, DT, 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, TD, DT, 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 TargetData *TD, const DominatorTree *DT, + unsigned MaxRecurse) { + if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, DT, 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_Shr(m_Value(X), m_Specific(Op1))) && + cast<PossiblyExactOperator>(Op0)->isExact()) + return X; + return 0; +} + +Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, + const TargetData *TD, const DominatorTree *DT) { + return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, TD, 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 TargetData *TD, const DominatorTree *DT, + unsigned MaxRecurse) { + if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, DT, 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 TargetData *TD, const DominatorTree *DT) { + return ::SimplifyLShrInst(Op0, Op1, isExact, TD, 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 TargetData *TD, const DominatorTree *DT, + unsigned MaxRecurse) { + if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, DT, 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 TargetData *TD, const DominatorTree *DT) { + return ::SimplifyAShrInst(Op0, Op1, isExact, TD, DT, RecursionLimit); +} + /// SimplifyAndInst - Given operands for an And, see if we can /// fold the result. If not, this returns null. -Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD) { +static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD, + const DominatorTree *DT, 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, 2, TD); } - + // Canonicalize the constant to the RHS. std::swap(Op0, Op1); } - + // X & undef -> 0 - if (isa<UndefValue>(Op1)) + if (match(Op1, m_Undef())) return Constant::getNullValue(Op0->getType()); - + // X & X = X if (Op0 == Op1) return Op0; - - // X & <0,0> = <0,0> - if (isa<ConstantAggregateZero>(Op1)) + + // X & 0 = 0 + if (match(Op1, m_Zero())) return Op1; - - // X & <-1,-1> = X - if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) - if (CP->isAllOnesValue()) - return Op0; - - if (ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1)) { - // X & 0 = 0 - if (Op1CI->isZero()) - return Op1CI; - // X & -1 = X - if (Op1CI->isAllOnesValue()) - return Op0; - } - + + // X & -1 = X + if (match(Op1, m_AllOnes())) + return Op0; + // A & ~A = ~A & A = 0 - Value *A, *B; - if ((match(Op0, m_Not(m_Value(A))) && A == Op1) || - (match(Op1, m_Not(m_Value(A))) && A == Op0)) + 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; - + + // Try some generic simplifications for associative operations. + if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT, + MaxRecurse)) + return V; + + // And distributes over Or. Try some generic simplifications based on this. + if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or, + TD, DT, MaxRecurse)) + return V; + + // And distributes over Xor. Try some generic simplifications based on this. + if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor, + TD, DT, MaxRecurse)) + return V; + + // Or distributes over And. Try some generic simplifications based on this. + if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or, + TD, DT, 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, TD, DT, + 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, TD, DT, + MaxRecurse)) + return V; + return 0; } +Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD, + const DominatorTree *DT) { + return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit); +} + /// SimplifyOrInst - Given operands for an Or, see if we can /// fold the result. If not, this returns null. -Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD) { +static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD, + const DominatorTree *DT, 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, 2, TD); } - + // Canonicalize the constant to the RHS. std::swap(Op0, Op1); } - + // X | undef -> -1 - if (isa<UndefValue>(Op1)) + if (match(Op1, m_Undef())) return Constant::getAllOnesValue(Op0->getType()); - + // X | X = X if (Op0 == Op1) return Op0; - // X | <0,0> = X - if (isa<ConstantAggregateZero>(Op1)) + // X | 0 = X + if (match(Op1, m_Zero())) return Op0; - - // X | <-1,-1> = <-1,-1> - if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) - if (CP->isAllOnesValue()) - return Op1; - - if (ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1)) { - // X | 0 = X - if (Op1CI->isZero()) - return Op0; - // X | -1 = -1 - if (Op1CI->isAllOnesValue()) - return Op1CI; - } - + + // X | -1 = -1 + if (match(Op1, m_AllOnes())) + return Op1; + // A | ~A = ~A | A = -1 - Value *A, *B; - if ((match(Op0, m_Not(m_Value(A))) && A == Op1) || - (match(Op1, m_Not(m_Value(A))) && A == Op0)) + 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; - + + // Try some generic simplifications for associative operations. + if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT, + MaxRecurse)) + return V; + + // Or distributes over And. Try some generic simplifications based on this. + if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, + TD, DT, MaxRecurse)) + return V; + + // And distributes over Or. Try some generic simplifications based on this. + if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And, + TD, DT, 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, TD, DT, + 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, TD, DT, + MaxRecurse)) + return V; + return 0; } +Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD, + const DominatorTree *DT) { + return ::SimplifyOrInst(Op0, Op1, TD, 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 TargetData *TD, + const DominatorTree *DT, 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, 2, TD); + } + + // 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, TD, DT, + MaxRecurse)) + return V; + + // And distributes over Xor. Try some generic simplifications based on this. + if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And, + TD, DT, 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 TargetData *TD, + const DominatorTree *DT) { + return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit); +} static const Type *GetCompareTy(Value *Op) { return CmpInst::makeCmpResultType(Op->getType()); } - /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can /// fold the result. If not, this returns null. -Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, - const TargetData *TD) { +static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const TargetData *TD, const DominatorTree *DT, + 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, TD); @@ -189,70 +1277,400 @@ Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, std::swap(LHS, RHS); Pred = CmpInst::getSwappedPredicate(Pred); } - - // ITy - This is the return type of the compare we're considering. - const Type *ITy = GetCompareTy(LHS); - + + const Type *ITy = GetCompareTy(LHS); // The return type. + const 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)); - - // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value - // addresses never equal each other! We already know that Op0 != Op1. - if ((isa<GlobalValue>(LHS) || isa<AllocaInst>(LHS) || - isa<ConstantPointerNull>(LHS)) && - (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) || - isa<ConstantPointerNull>(RHS))) - return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred)); - - // See if we are doing a comparison with a constant. - if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { - // If we have an icmp le or icmp ge instruction, turn it into the - // appropriate icmp lt or icmp gt instruction. This allows us to rely on - // them being folded in the code below. + + // Special case logic when the operands have i1 type. + if (OpTy->isIntegerTy(1) || (OpTy->isVectorTy() && + cast<VectorType>(OpTy)->getElementType()->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; + } + } + + // icmp <alloca*>, <global/alloca*/null> - Different stack variables have + // different addresses, and what's more the address of a stack variable is + // never null or equal to the address of a global. Note that generalizing + // to the case where LHS is a global variable address or null is pointless, + // since if both LHS and RHS are constants then we already constant folded + // the compare, and if only one of them is then we moved it to RHS already. + if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) || + isa<ConstantPointerNull>(RHS))) + // We already know that LHS != LHS. + return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred)); + + // 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: + assert(false && "Unknown ICmp predicate!"); + case ICmpInst::ICMP_ULT: + return ConstantInt::getFalse(LHS->getContext()); + case ICmpInst::ICMP_UGE: + return ConstantInt::getTrue(LHS->getContext()); + case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE: - if (CI->isMaxValue(false)) // A <=u MAX -> TRUE - return ConstantInt::getTrue(CI->getContext()); + if (isKnownNonZero(LHS, TD)) + return ConstantInt::getFalse(LHS->getContext()); + break; + case ICmpInst::ICMP_NE: + case ICmpInst::ICMP_UGT: + if (isKnownNonZero(LHS, TD)) + return ConstantInt::getTrue(LHS->getContext()); + break; + case ICmpInst::ICMP_SLT: + ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD); + if (LHSKnownNegative) + return ConstantInt::getTrue(LHS->getContext()); + if (LHSKnownNonNegative) + return ConstantInt::getFalse(LHS->getContext()); break; case ICmpInst::ICMP_SLE: - if (CI->isMaxValue(true)) // A <=s MAX -> TRUE - return ConstantInt::getTrue(CI->getContext()); + ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD); + if (LHSKnownNegative) + return ConstantInt::getTrue(LHS->getContext()); + if (LHSKnownNonNegative && isKnownNonZero(LHS, TD)) + return ConstantInt::getFalse(LHS->getContext()); + break; + case ICmpInst::ICMP_SGE: + ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD); + if (LHSKnownNegative) + return ConstantInt::getFalse(LHS->getContext()); + if (LHSKnownNonNegative) + return ConstantInt::getTrue(LHS->getContext()); + break; + case ICmpInst::ICMP_SGT: + ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD); + if (LHSKnownNegative) + return ConstantInt::getFalse(LHS->getContext()); + if (LHSKnownNonNegative && isKnownNonZero(LHS, TD)) + return ConstantInt::getTrue(LHS->getContext()); + break; + } + } + + // See if we are doing a comparison with a constant integer. + if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { + switch (Pred) { + default: break; + case ICmpInst::ICMP_UGT: + if (CI->isMaxValue(false)) // A >u MAX -> FALSE + return ConstantInt::getFalse(CI->getContext()); break; case ICmpInst::ICMP_UGE: if (CI->isMinValue(false)) // A >=u MIN -> TRUE return ConstantInt::getTrue(CI->getContext()); break; + case ICmpInst::ICMP_ULT: + if (CI->isMinValue(false)) // A <u MIN -> FALSE + return ConstantInt::getFalse(CI->getContext()); + break; + case ICmpInst::ICMP_ULE: + if (CI->isMaxValue(false)) // A <=u MAX -> TRUE + return ConstantInt::getTrue(CI->getContext()); + break; + case ICmpInst::ICMP_SGT: + if (CI->isMaxValue(true)) // A >s MAX -> FALSE + return ConstantInt::getFalse(CI->getContext()); + break; case ICmpInst::ICMP_SGE: if (CI->isMinValue(true)) // A >=s MIN -> TRUE return ConstantInt::getTrue(CI->getContext()); break; + case ICmpInst::ICMP_SLT: + if (CI->isMinValue(true)) // A <s MIN -> FALSE + return ConstantInt::getFalse(CI->getContext()); + break; + case ICmpInst::ICMP_SLE: + if (CI->isMaxValue(true)) // A <=s MAX -> TRUE + return ConstantInt::getTrue(CI->getContext()); + break; + } + } + + // 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); + const Type *SrcTy = SrcOp->getType(); + const 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 && TD && isa<PtrToIntInst>(LI) && + 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), + TD, DT, 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), + TD, DT, 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), TD, DT, + 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, TD, DT, 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: + assert(false && "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), + TD, DT, 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, TD, DT, + 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: + assert(false && "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), + TD, DT, 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), + TD, DT, 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()), + TD, DT, 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, TD, DT, 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 = (A == C || A == D) ? B : A; + Value *Z = (C == A || C == B) ? D : C; + if (Value *V = SimplifyICmpInst(Pred, Y, Z, TD, DT, MaxRecurse-1)) + return V; + } + } + + // 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, TD, DT, 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, TD, DT, MaxRecurse)) + return V; + return 0; } +Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const TargetData *TD, const DominatorTree *DT) { + return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit); +} + /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can /// fold the result. If not, this returns null. -Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, - const TargetData *TD) { +static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const TargetData *TD, const DominatorTree *DT, + 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, TD); - + // 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); @@ -269,7 +1687,7 @@ Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 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. @@ -310,23 +1728,40 @@ Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, } } } - + + // 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, TD, DT, 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, TD, DT, MaxRecurse)) + return V; + return 0; } +Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const TargetData *TD, const DominatorTree *DT) { + return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit); +} + /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold /// the result. If not, this returns null. Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal, - const TargetData *TD) { + const TargetData *TD, const DominatorTree *) { // 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>(TrueVal)) // select C, undef, X -> X return FalseVal; if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X @@ -336,98 +1771,249 @@ Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal, return TrueVal; return FalseVal; } - - - + return 0; } - /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can /// fold the result. If not, this returns null. Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps, - const TargetData *TD) { + const TargetData *TD, const DominatorTree *) { + // The type of the GEP pointer operand. + const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType()); + // getelementptr P -> P. if (NumOps == 1) return Ops[0]; - // TODO. - //if (isa<UndefValue>(Ops[0])) - // return UndefValue::get(GEP.getType()); + if (isa<UndefValue>(Ops[0])) { + // Compute the (pointer) type returned by the GEP instruction. + const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1], + NumOps-1); + const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace()); + return UndefValue::get(GEPTy); + } - // getelementptr P, 0 -> P. - if (NumOps == 2) + if (NumOps == 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 (TD) { + const Type *Ty = PtrTy->getElementType(); + if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0) + return Ops[0]; + } + } + // Check to see if this is constant foldable. for (unsigned i = 0; i != NumOps; ++i) if (!isa<Constant>(Ops[i])) return 0; - + return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]), (Constant *const*)Ops+1, NumOps-1); } +/// SimplifyPHINode - See if we can fold the given phi. If not, returns null. +static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) { + // 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, DT) ? CommonValue : 0; + + return CommonValue; +} + //=== 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. -Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, - const TargetData *TD) { +static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, + const TargetData *TD, const DominatorTree *DT, + unsigned MaxRecurse) { switch (Opcode) { - case Instruction::And: return SimplifyAndInst(LHS, RHS, TD); - case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD); + case Instruction::Add: + return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, + TD, DT, MaxRecurse); + case Instruction::Sub: + return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, + TD, DT, MaxRecurse); + case Instruction::Mul: return SimplifyMulInst (LHS, RHS, TD, DT, MaxRecurse); + case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, DT, MaxRecurse); + case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, DT, MaxRecurse); + case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, DT, MaxRecurse); + case Instruction::Shl: + return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false, + TD, DT, MaxRecurse); + case Instruction::LShr: + return SimplifyLShrInst(LHS, RHS, /*isExact*/false, TD, DT, MaxRecurse); + case Instruction::AShr: + return SimplifyAShrInst(LHS, RHS, /*isExact*/false, TD, DT, MaxRecurse); + case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse); + case Instruction::Or: return SimplifyOrInst (LHS, RHS, TD, DT, MaxRecurse); + case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, 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, 2, TD); } + + // If the operation is associative, try some generic simplifications. + if (Instruction::isAssociative(Opcode)) + if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT, + 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, TD, DT, + 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, TD, DT, MaxRecurse)) + return V; + return 0; } } +Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, + const TargetData *TD, const DominatorTree *DT) { + return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit); +} + /// SimplifyCmpInst - Given operands for a CmpInst, see if we can /// fold the result. -Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, - const TargetData *TD) { +static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const TargetData *TD, const DominatorTree *DT, + unsigned MaxRecurse) { if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) - return SimplifyICmpInst(Predicate, LHS, RHS, TD); - return SimplifyFCmpInst(Predicate, LHS, RHS, TD); + return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse); + return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse); } +Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const TargetData *TD, const DominatorTree *DT) { + return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, 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 TargetData *TD) { +Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD, + const DominatorTree *DT) { + Value *Result; + switch (I->getOpcode()) { default: - return ConstantFoldInstruction(I, TD); + Result = ConstantFoldInstruction(I, TD); + break; case Instruction::Add: - return SimplifyAddInst(I->getOperand(0), I->getOperand(1), - cast<BinaryOperator>(I)->hasNoSignedWrap(), - cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD); + Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1), + cast<BinaryOperator>(I)->hasNoSignedWrap(), + cast<BinaryOperator>(I)->hasNoUnsignedWrap(), + TD, DT); + break; + case Instruction::Sub: + Result = SimplifySubInst(I->getOperand(0), I->getOperand(1), + cast<BinaryOperator>(I)->hasNoSignedWrap(), + cast<BinaryOperator>(I)->hasNoUnsignedWrap(), + TD, DT); + break; + case Instruction::Mul: + Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT); + break; + case Instruction::SDiv: + Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, DT); + break; + case Instruction::UDiv: + Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, DT); + break; + case Instruction::FDiv: + Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, DT); + break; + case Instruction::Shl: + Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1), + cast<BinaryOperator>(I)->hasNoSignedWrap(), + cast<BinaryOperator>(I)->hasNoUnsignedWrap(), + TD, DT); + break; + case Instruction::LShr: + Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), + cast<BinaryOperator>(I)->isExact(), + TD, DT); + break; + case Instruction::AShr: + Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), + cast<BinaryOperator>(I)->isExact(), + TD, DT); + break; case Instruction::And: - return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD); + Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT); + break; case Instruction::Or: - return SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD); + Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT); + break; + case Instruction::Xor: + Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT); + break; case Instruction::ICmp: - return SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), - I->getOperand(0), I->getOperand(1), TD); + Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), + I->getOperand(0), I->getOperand(1), TD, DT); + break; case Instruction::FCmp: - return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), - I->getOperand(0), I->getOperand(1), TD); + Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), + I->getOperand(0), I->getOperand(1), TD, DT); + break; case Instruction::Select: - return SimplifySelectInst(I->getOperand(0), I->getOperand(1), - I->getOperand(2), TD); + Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1), + I->getOperand(2), TD, DT); + break; case Instruction::GetElementPtr: { SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end()); - return SimplifyGEPInst(&Ops[0], Ops.size(), TD); + Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT); + break; } + case Instruction::PHI: + Result = SimplifyPHINode(cast<PHINode>(I), 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; } /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then @@ -437,15 +2023,16 @@ Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD) { /// simplifies and deletes scalar operations, it does not change the CFG. /// void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To, - const TargetData *TD) { + const TargetData *TD, + const DominatorTree *DT) { assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!"); - + // FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that // we can know if it gets deleted out from under us or replaced in a // recursive simplification. WeakVH FromHandle(From); WeakVH ToHandle(To); - + while (!From->use_empty()) { // Update the instruction to use the new value. Use &TheUse = From->use_begin().getUse(); @@ -460,27 +2047,26 @@ void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To, // Sanity check to make sure 'User' doesn't dangle across // SimplifyInstruction. AssertingVH<> UserHandle(User); - - SimplifiedVal = SimplifyInstruction(User, TD); + + SimplifiedVal = SimplifyInstruction(User, TD, DT); if (SimplifiedVal == 0) continue; } - + // Recursively simplify this user to the new value. - ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD); + ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT); From = dyn_cast_or_null<Instruction>((Value*)FromHandle); To = ToHandle; - + assert(ToHandle && "To value deleted by recursive simplification?"); - + // If the recursive simplification ended up revisiting and deleting // 'From' then we're done. if (From == 0) return; } - + // If 'From' has value handles referring to it, do a real RAUW to update them. From->replaceAllUsesWith(To); - + From->eraseFromParent(); } - |
