InstCombineSelect.cpp revision 11acaa374cdcebb161bf0de5f244265d78a749c1
11c22c80d71d7031fa1d4acb4d22dd91beb5487e6Chris Lattner//===- InstCombineSelect.cpp ----------------------------------------------===// 2c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner// 3c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner// The LLVM Compiler Infrastructure 4c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner// 5c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner// This file is distributed under the University of Illinois Open Source 6c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner// License. See LICENSE.TXT for details. 7c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner// 8c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner//===----------------------------------------------------------------------===// 9c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner// 101c22c80d71d7031fa1d4acb4d22dd91beb5487e6Chris Lattner// This file implements the visitSelect function. 11c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner// 12c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner//===----------------------------------------------------------------------===// 13c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 14c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner#include "InstCombine.h" 15c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner#include "llvm/Support/PatternMatch.h" 16c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerusing namespace llvm; 17c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerusing namespace PatternMatch; 18c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 19c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// MatchSelectPattern - Pattern match integer [SU]MIN, [SU]MAX, and ABS idioms, 20c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// returning the kind and providing the out parameter results if we 21c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// successfully match. 22c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic SelectPatternFlavor 23c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerMatchSelectPattern(Value *V, Value *&LHS, Value *&RHS) { 24c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectInst *SI = dyn_cast<SelectInst>(V); 25c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI == 0) return SPF_UNKNOWN; 26c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 27c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICmpInst *ICI = dyn_cast<ICmpInst>(SI->getCondition()); 28c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ICI == 0) return SPF_UNKNOWN; 29c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 30c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner LHS = ICI->getOperand(0); 31c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner RHS = ICI->getOperand(1); 32c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 33c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // (icmp X, Y) ? X : Y 34c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI->getTrueValue() == ICI->getOperand(0) && 35c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI->getFalseValue() == ICI->getOperand(1)) { 36c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (ICI->getPredicate()) { 37c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: return SPF_UNKNOWN; // Equality. 38c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGT: 39c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGE: return SPF_UMAX; 40c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGT: 41c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGE: return SPF_SMAX; 42c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULT: 43c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULE: return SPF_UMIN; 44c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLT: 45c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLE: return SPF_SMIN; 46c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 47c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 48c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 49c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // (icmp X, Y) ? Y : X 50c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI->getTrueValue() == ICI->getOperand(1) && 51c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI->getFalseValue() == ICI->getOperand(0)) { 52c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (ICI->getPredicate()) { 53c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: return SPF_UNKNOWN; // Equality. 54c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGT: 55c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGE: return SPF_UMIN; 56c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGT: 57c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGE: return SPF_SMIN; 58c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULT: 59c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULE: return SPF_UMAX; 60c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLT: 61c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLE: return SPF_SMAX; 62c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 63c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 64c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 65c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5) 66c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 67c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return SPF_UNKNOWN; 68c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 69c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 70c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 71c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// GetSelectFoldableOperands - We want to turn code that looks like this: 72c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// %C = or %A, %B 73c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// %D = select %cond, %C, %A 74c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// into: 75c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// %C = select %cond, %B, 0 76c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// %D = or %A, %C 77c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 78c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// Assuming that the specified instruction is an operand to the select, return 79c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// a bitmask indicating which operands of this instruction are foldable if they 80c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// equal the other incoming value of the select. 81c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 82c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic unsigned GetSelectFoldableOperands(Instruction *I) { 83c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (I->getOpcode()) { 84c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Add: 85c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Mul: 86c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::And: 87c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Or: 88c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Xor: 89c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 3; // Can fold through either operand. 90c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Sub: // Can only fold on the amount subtracted. 91c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Shl: // Can only fold on the shift amount. 92c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::LShr: 93c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::AShr: 94c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 1; 95c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: 96c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; // Cannot fold 97c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 98c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 99c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 100c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// GetSelectFoldableConstant - For the same transformation as the previous 101c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// function, return the identity constant that goes into the select. 102c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic Constant *GetSelectFoldableConstant(Instruction *I) { 103c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (I->getOpcode()) { 104c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: llvm_unreachable("This cannot happen!"); 105c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Add: 106c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Sub: 107c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Or: 108c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Xor: 109c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Shl: 110c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::LShr: 111c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::AShr: 112c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return Constant::getNullValue(I->getType()); 113c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::And: 114c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return Constant::getAllOnesValue(I->getType()); 115c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Mul: 116c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ConstantInt::get(I->getType(), 1); 117c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 118c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 119c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 120c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI 121c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// have the same opcode and only one use each. Try to simplify this. 122c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI, 123c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *FI) { 124c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->getNumOperands() == 1) { 125c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // If this is a non-volatile load or a cast from the same type, 126c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // merge. 127c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->isCast()) { 128c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType()) 129c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 130c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else { 131c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; // unknown unary op. 132c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 133c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 134c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Fold this by inserting a select from the input values. 135c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0), 136c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner FI->getOperand(0), SI.getName()+".v"); 137c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(NewSI, SI); 138c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI, 139c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner TI->getType()); 140c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 141c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 142c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Only handle binary operators here. 143c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!isa<BinaryOperator>(TI)) 144c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 145c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 146c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Figure out if the operations have any operands in common. 147c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *MatchOp, *OtherOpT, *OtherOpF; 148c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner bool MatchIsOpZero; 149c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->getOperand(0) == FI->getOperand(0)) { 150c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchOp = TI->getOperand(0); 151c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpT = TI->getOperand(1); 152c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF = FI->getOperand(1); 153c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchIsOpZero = true; 154c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (TI->getOperand(1) == FI->getOperand(1)) { 155c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchOp = TI->getOperand(1); 156c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpT = TI->getOperand(0); 157c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF = FI->getOperand(0); 158c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchIsOpZero = false; 159c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (!TI->isCommutative()) { 160c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 161c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (TI->getOperand(0) == FI->getOperand(1)) { 162c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchOp = TI->getOperand(0); 163c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpT = TI->getOperand(1); 164c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF = FI->getOperand(0); 165c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchIsOpZero = true; 166c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (TI->getOperand(1) == FI->getOperand(0)) { 167c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchOp = TI->getOperand(1); 168c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpT = TI->getOperand(0); 169c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF = FI->getOperand(1); 170c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchIsOpZero = true; 171c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else { 172c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 173c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 174c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 175c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // If we reach here, they do have operations in common. 176c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT, 177c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF, SI.getName()+".v"); 178c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(NewSI, SI); 179c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 180c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) { 181c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (MatchIsOpZero) 182c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI); 183c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner else 184c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp); 185c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 186c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner llvm_unreachable("Shouldn't get here"); 187c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 188c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 189c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 190c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic bool isSelect01(Constant *C1, Constant *C2) { 191c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantInt *C1I = dyn_cast<ConstantInt>(C1); 192c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!C1I) 193c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return false; 194c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantInt *C2I = dyn_cast<ConstantInt>(C2); 195c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!C2I) 196c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return false; 197c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne()); 198c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 199c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 200c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// FoldSelectIntoOp - Try fold the select into one of the operands to 201c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// facilitate further optimization. 202c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal, 203c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *FalseVal) { 204c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See the comment above GetSelectFoldableOperands for a description of the 205c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // transformation we are doing here. 206c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) { 207c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TVI->hasOneUse() && TVI->getNumOperands() == 2 && 208c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !isa<Constant>(FalseVal)) { 209c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (unsigned SFO = GetSelectFoldableOperands(TVI)) { 210c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner unsigned OpToFold = 0; 211c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((SFO & 1) && FalseVal == TVI->getOperand(0)) { 212c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OpToFold = 1; 213c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) { 214c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OpToFold = 2; 215c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 216c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 217c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (OpToFold) { 218c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Constant *C = GetSelectFoldableConstant(TVI); 219c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *OOp = TVI->getOperand(2-OpToFold); 220c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Avoid creating select between 2 constants unless it's selecting 221c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // between 0 and 1. 222c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) { 223c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C); 224c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(NewSel, SI); 225c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NewSel->takeName(TVI); 226c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI)) 227c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel); 228c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner llvm_unreachable("Unknown instruction!!"); 229c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 230c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 231c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 232c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 233c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 234c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 235c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) { 236c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FVI->hasOneUse() && FVI->getNumOperands() == 2 && 237c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !isa<Constant>(TrueVal)) { 238c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (unsigned SFO = GetSelectFoldableOperands(FVI)) { 239c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner unsigned OpToFold = 0; 240c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((SFO & 1) && TrueVal == FVI->getOperand(0)) { 241c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OpToFold = 1; 242c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) { 243c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OpToFold = 2; 244c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 245c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 246c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (OpToFold) { 247c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Constant *C = GetSelectFoldableConstant(FVI); 248c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *OOp = FVI->getOperand(2-OpToFold); 249c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Avoid creating select between 2 constants unless it's selecting 250c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // between 0 and 1. 251c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) { 252c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp); 253c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(NewSel, SI); 254c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NewSel->takeName(FVI); 255c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI)) 256c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel); 257c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner llvm_unreachable("Unknown instruction!!"); 258c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 259c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 260c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 261c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 262c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 263c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 264c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 265c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 266c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 267c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// visitSelectInstWithICmp - Visit a SelectInst that has an 268c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// ICmpInst as its first operand. 269c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 270c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI, 271c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICmpInst *ICI) { 272c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner bool Changed = false; 273c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICmpInst::Predicate Pred = ICI->getPredicate(); 274c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *CmpLHS = ICI->getOperand(0); 275c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *CmpRHS = ICI->getOperand(1); 276c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *TrueVal = SI.getTrueValue(); 277c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *FalseVal = SI.getFalseValue(); 278c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 279c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Check cases where the comparison is with a constant that 280c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // can be adjusted to fit the min/max idiom. We may edit ICI in 281c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // place here, so make sure the select is the only user. 282c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ICI->hasOneUse()) 283c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) { 284c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (Pred) { 285c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: break; 286c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULT: 287c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLT: { 288c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // X < MIN ? T : F --> F 289c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT)) 290c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 291c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // X < C ? X : C-1 --> X > C-1 ? C-1 : X 292c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Constant *AdjustedRHS = 293c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantInt::get(CI->getContext(), CI->getValue()-1); 294c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) || 295c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) { 296c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Pred = ICmpInst::getSwappedPredicate(Pred); 297c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner CmpRHS = AdjustedRHS; 298c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner std::swap(FalseVal, TrueVal); 299c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICI->setPredicate(Pred); 300c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICI->setOperand(1, CmpRHS); 301c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(1, TrueVal); 302c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(2, FalseVal); 303c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Changed = true; 304c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 305c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner break; 306c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 307c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGT: 308c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGT: { 309c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // X > MAX ? T : F --> F 310c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT)) 311c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 312c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // X > C ? X : C+1 --> X < C+1 ? C+1 : X 313c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Constant *AdjustedRHS = 314c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantInt::get(CI->getContext(), CI->getValue()+1); 315c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) || 316c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) { 317c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Pred = ICmpInst::getSwappedPredicate(Pred); 318c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner CmpRHS = AdjustedRHS; 319c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner std::swap(FalseVal, TrueVal); 320c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICI->setPredicate(Pred); 321c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICI->setOperand(1, CmpRHS); 322c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(1, TrueVal); 323c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(2, FalseVal); 324c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Changed = true; 325c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 326c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner break; 327c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 328c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 329c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 330c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed 331c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed 332c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE; 333c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (match(TrueVal, m_ConstantInt<-1>()) && 334c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner match(FalseVal, m_ConstantInt<0>())) 335c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Pred = ICI->getPredicate(); 336c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner else if (match(TrueVal, m_ConstantInt<0>()) && 337c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner match(FalseVal, m_ConstantInt<-1>())) 338c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Pred = CmpInst::getInversePredicate(ICI->getPredicate()); 339c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 340c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Pred != CmpInst::BAD_ICMP_PREDICATE) { 341c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // If we are just checking for a icmp eq of a single bit and zext'ing it 342c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // to an integer, then shift the bit to the appropriate place and then 343c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // cast to integer to avoid the comparison. 344c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner const APInt &Op1CV = CI->getValue(); 345c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 346c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // sext (x <s 0) to i32 --> x>>s31 true if signbit set. 347c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear. 348c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) || 349c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) { 350c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *In = ICI->getOperand(0); 351c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *Sh = ConstantInt::get(In->getType(), 352c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner In->getType()->getScalarSizeInBits()-1); 353c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh, 354c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner In->getName()+".lobit"), 355c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner *ICI); 356c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (In->getType() != SI.getType()) 357c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner In = CastInst::CreateIntegerCast(In, SI.getType(), 358c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner true/*SExt*/, "tmp", ICI); 359c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 360c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Pred == ICmpInst::ICMP_SGT) 361c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner In = InsertNewInstBefore(BinaryOperator::CreateNot(In, 362c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner In->getName()+".not"), *ICI); 363c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 364c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, In); 365c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 366c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 367c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 368c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 369c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (CmpLHS == TrueVal && CmpRHS == FalseVal) { 370c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X == Y) ? X : Y -> Y 371c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Pred == ICmpInst::ICMP_EQ) 372c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 373c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X != Y) ? X : Y -> X 374c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Pred == ICmpInst::ICMP_NE) 375c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, TrueVal); 376c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner /// NOTE: if we wanted to, this is where to detect integer MIN/MAX 377c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 378c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) { 379c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X == Y) ? Y : X -> X 380c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Pred == ICmpInst::ICMP_EQ) 381c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 382c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X != Y) ? Y : X -> Y 383c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Pred == ICmpInst::ICMP_NE) 384c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, TrueVal); 385c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner /// NOTE: if we wanted to, this is where to detect integer MIN/MAX 386c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 387c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return Changed ? &SI : 0; 388c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 389c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 390c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 391c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// CanSelectOperandBeMappingIntoPredBlock - SI is a select whose condition is a 392c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// PHI node (but the two may be in different blocks). See if the true/false 393c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// values (V) are live in all of the predecessor blocks of the PHI. For 394c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// example, cases like this cannot be mapped: 395c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 396c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// X = phi [ C1, BB1], [C2, BB2] 397c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// Y = add 398c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// Z = select X, Y, 0 399c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 400c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// because Y is not live in BB1/BB2. 401c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 402c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic bool CanSelectOperandBeMappingIntoPredBlock(const Value *V, 403c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner const SelectInst &SI) { 404c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // If the value is a non-instruction value like a constant or argument, it 405c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // can always be mapped. 406c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner const Instruction *I = dyn_cast<Instruction>(V); 407c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (I == 0) return true; 408c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 409c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // If V is a PHI node defined in the same block as the condition PHI, we can 410c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // map the arguments. 411c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner const PHINode *CondPHI = cast<PHINode>(SI.getCondition()); 412c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 413c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (const PHINode *VP = dyn_cast<PHINode>(I)) 414c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (VP->getParent() == CondPHI->getParent()) 415c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return true; 416c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 417c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Otherwise, if the PHI and select are defined in the same block and if V is 418c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // defined in a different block, then we can transform it. 419c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI.getParent() == CondPHI->getParent() && 420c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner I->getParent() != CondPHI->getParent()) 421c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return true; 422c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 423c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Otherwise we have a 'hard' case and we can't tell without doing more 424c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // detailed dominator based analysis, punt. 425c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return false; 426c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 427c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 428c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form: 429c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// SPF2(SPF1(A, B), C) 430c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::FoldSPFofSPF(Instruction *Inner, 431c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectPatternFlavor SPF1, 432c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *A, Value *B, 433c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction &Outer, 434c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectPatternFlavor SPF2, Value *C) { 435c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (C == A || C == B) { 436c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MAX(MAX(A, B), B) -> MAX(A, B) 437c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MIN(MIN(a, b), a) -> MIN(a, b) 438c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SPF1 == SPF2) 439c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(Outer, Inner); 440c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 441c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MAX(MIN(a, b), a) -> a 442c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MIN(MAX(a, b), a) -> a 443c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) || 444c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) || 445c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) || 446c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN)) 447c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(Outer, C); 448c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 449c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 450c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // TODO: MIN(MIN(A, 23), 97) 451c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 452c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 453c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 454c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 455c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 456c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 457c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::visitSelectInst(SelectInst &SI) { 458c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *CondVal = SI.getCondition(); 459c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *TrueVal = SI.getTrueValue(); 460c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *FalseVal = SI.getFalseValue(); 461c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 462c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select true, X, Y -> X 463c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select false, X, Y -> Y 464c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal)) 465c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal); 466c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 467c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select C, X, X -> X 468c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TrueVal == FalseVal) 469c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, TrueVal); 470c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 471c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X 472c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 473c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X 474c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, TrueVal); 475c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y 476c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (isa<Constant>(TrueVal)) 477c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, TrueVal); 478c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner else 479c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 480c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 481c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 48211acaa374cdcebb161bf0de5f244265d78a749c1Benjamin Kramer if (SI.getType()->isInteger(1)) { 483c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) { 484c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (C->getZExtValue()) { 485c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Change: A = select B, true, C --> A = or B, C 486c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateOr(CondVal, FalseVal); 487c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else { 488c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Change: A = select B, false, C --> A = and !B, C 489c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NotCond = 490c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(BinaryOperator::CreateNot(CondVal, 491c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner "not."+CondVal->getName()), SI); 492c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateAnd(NotCond, FalseVal); 493c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 494c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) { 495c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (C->getZExtValue() == false) { 496c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Change: A = select B, C, false --> A = and B, C 497c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateAnd(CondVal, TrueVal); 498c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else { 499c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Change: A = select B, C, true --> A = or !B, C 500c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NotCond = 501c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(BinaryOperator::CreateNot(CondVal, 502c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner "not."+CondVal->getName()), SI); 503c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateOr(NotCond, TrueVal); 504c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 505c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 506c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 507c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select a, b, a -> a&b 508c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select a, a, b -> a|b 509c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (CondVal == TrueVal) 510c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateOr(CondVal, FalseVal); 511c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner else if (CondVal == FalseVal) 512c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateAnd(CondVal, TrueVal); 513c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 514c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 515c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Selecting between two integer constants? 516c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal)) 517c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) { 518c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select C, 1, 0 -> zext C to int 519c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FalseValC->isZero() && TrueValC->getValue() == 1) { 520c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return CastInst::Create(Instruction::ZExt, CondVal, SI.getType()); 521c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (TrueValC->isZero() && FalseValC->getValue() == 1) { 522c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select C, 0, 1 -> zext !C to int 523c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NotCond = 524c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(BinaryOperator::CreateNot(CondVal, 525c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner "not."+CondVal->getName()), SI); 526c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return CastInst::Create(Instruction::ZExt, NotCond, SI.getType()); 527c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 528c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 529c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) { 530c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // If one of the constants is zero (we know they can't both be) and we 531c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // have an icmp instruction with zero, and we have an 'and' with the 532c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // non-constant value, eliminate this whole mess. This corresponds to 533c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // cases like this: ((X & 27) ? 27 : 0) 534c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TrueValC->isZero() || FalseValC->isZero()) 535c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) && 536c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner cast<Constant>(IC->getOperand(1))->isNullValue()) 537c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0))) 538c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ICA->getOpcode() == Instruction::And && 539c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner isa<ConstantInt>(ICA->getOperand(1)) && 540c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (ICA->getOperand(1) == TrueValC || 541c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICA->getOperand(1) == FalseValC) && 542c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner cast<ConstantInt>(ICA->getOperand(1))->getValue().isPowerOf2()) { 543c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Okay, now we know that everything is set up, we just don't 544c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // know whether we have a icmp_ne or icmp_eq and whether the 545c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // true or false val is the zero. 546c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner bool ShouldNotVal = !TrueValC->isZero(); 547c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE; 548c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *V = ICA; 549c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ShouldNotVal) 550c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner V = InsertNewInstBefore(BinaryOperator::Create( 551c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction::Xor, V, ICA->getOperand(1)), SI); 552c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, V); 553c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 554c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 555c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 556c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 557c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See if we are selecting two values based on a comparison of the two values. 558c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) { 559c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) { 560c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X == Y) ? X : Y -> Y 561c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { 562c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // This is not safe in general for floating point: 563c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // consider X== -0, Y== +0. 564c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // It becomes safe if either operand is a nonzero constant. 565c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantFP *CFPt, *CFPf; 566c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) && 567c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !CFPt->getValueAPF().isZero()) || 568c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ((CFPf = dyn_cast<ConstantFP>(FalseVal)) && 569c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !CFPf->getValueAPF().isZero())) 570c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 571c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 572c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X != Y) ? X : Y -> X 573c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FCI->getPredicate() == FCmpInst::FCMP_ONE) 574c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, TrueVal); 575c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // NOTE: if we wanted to, this is where to detect MIN/MAX 576c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 577c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){ 578c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X == Y) ? Y : X -> X 579c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { 580c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // This is not safe in general for floating point: 581c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // consider X== -0, Y== +0. 582c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // It becomes safe if either operand is a nonzero constant. 583c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantFP *CFPt, *CFPf; 584c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) && 585c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !CFPt->getValueAPF().isZero()) || 586c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ((CFPf = dyn_cast<ConstantFP>(FalseVal)) && 587c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !CFPf->getValueAPF().isZero())) 588c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 589c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 590c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X != Y) ? Y : X -> Y 591c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FCI->getPredicate() == FCmpInst::FCMP_ONE) 592c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, TrueVal); 593c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // NOTE: if we wanted to, this is where to detect MIN/MAX 594c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 595c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // NOTE: if we wanted to, this is where to detect ABS 596c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 597c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 598c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See if we are selecting two values based on a comparison of the two values. 599c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal)) 600c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *Result = visitSelectInstWithICmp(SI, ICI)) 601c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return Result; 602c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 603c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *TI = dyn_cast<Instruction>(TrueVal)) 604c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *FI = dyn_cast<Instruction>(FalseVal)) 605c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->hasOneUse() && FI->hasOneUse()) { 606c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *AddOp = 0, *SubOp = 0; 607c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 608c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z)) 609c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->getOpcode() == FI->getOpcode()) 610c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *IV = FoldSelectOpOp(SI, TI, FI)) 611c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return IV; 612c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 613c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is 614c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // even legal for FP. 615c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((TI->getOpcode() == Instruction::Sub && 616c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner FI->getOpcode() == Instruction::Add) || 617c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (TI->getOpcode() == Instruction::FSub && 618c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner FI->getOpcode() == Instruction::FAdd)) { 619c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner AddOp = FI; SubOp = TI; 620c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if ((FI->getOpcode() == Instruction::Sub && 621c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner TI->getOpcode() == Instruction::Add) || 622c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (FI->getOpcode() == Instruction::FSub && 623c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner TI->getOpcode() == Instruction::FAdd)) { 624c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner AddOp = TI; SubOp = FI; 625c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 626c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 627c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (AddOp) { 628c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *OtherAddOp = 0; 629c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SubOp->getOperand(0) == AddOp->getOperand(0)) { 630c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherAddOp = AddOp->getOperand(1); 631c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) { 632c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherAddOp = AddOp->getOperand(0); 633c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 634c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 635c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (OtherAddOp) { 636c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // So at this point we know we have (Y -> OtherAddOp): 637c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select C, (add X, Y), (sub X, Z) 638c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NegVal; // Compute -Z 639c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) { 640c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NegVal = ConstantExpr::getNeg(C); 641c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else { 642c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NegVal = InsertNewInstBefore( 643c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner BinaryOperator::CreateNeg(SubOp->getOperand(1), 644c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner "tmp"), SI); 645c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 646c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 647c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NewTrueOp = OtherAddOp; 648c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NewFalseOp = NegVal; 649c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (AddOp != TI) 650c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner std::swap(NewTrueOp, NewFalseOp); 651c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *NewSel = 652c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectInst::Create(CondVal, NewTrueOp, 653c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NewFalseOp, SI.getName() + ".p"); 654c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 655c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NewSel = InsertNewInstBefore(NewSel, SI); 656c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel); 657c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 658c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 659c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 660c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 661c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See if we can fold the select into one of our operands. 662c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI.getType()->isInteger()) { 663c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal)) 664c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return FoldI; 665c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 666c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MAX(MAX(a, b), a) -> MAX(a, b) 667c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MIN(MIN(a, b), a) -> MIN(a, b) 668c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MAX(MIN(a, b), a) -> a 669c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MIN(MAX(a, b), a) -> a 670c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *LHS, *RHS, *LHS2, *RHS2; 671c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SelectPatternFlavor SPF = MatchSelectPattern(&SI, LHS, RHS)) { 672c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SelectPatternFlavor SPF2 = MatchSelectPattern(LHS, LHS2, RHS2)) 673c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2, 674c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI, SPF, RHS)) 675c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return R; 676c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SelectPatternFlavor SPF2 = MatchSelectPattern(RHS, LHS2, RHS2)) 677c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *R = FoldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2, 678c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI, SPF, LHS)) 679c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return R; 680c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 681c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 682c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // TODO. 683c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // ABS(-X) -> ABS(X) 684c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // ABS(ABS(X)) -> ABS(X) 685c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 686c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 687c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See if we can fold the select into a phi node if the condition is a select. 688c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (isa<PHINode>(SI.getCondition())) 689c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // The true/false values have to be live in the PHI predecessor's blocks. 690c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (CanSelectOperandBeMappingIntoPredBlock(TrueVal, SI) && 691c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner CanSelectOperandBeMappingIntoPredBlock(FalseVal, SI)) 692c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *NV = FoldOpIntoPhi(SI)) 693c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return NV; 694c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 695c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (BinaryOperator::isNot(CondVal)) { 696c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(0, BinaryOperator::getNotArgument(CondVal)); 697c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(1, FalseVal); 698c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(2, TrueVal); 699c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return &SI; 700c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 701c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 702c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 703c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 704