InstCombineSelect.cpp revision 1db071f0dae25d0c5a1af61ca71fa20d0a8e9370
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" 16047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner#include "llvm/Analysis/InstructionSimplify.h" 17c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerusing namespace llvm; 18c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerusing namespace PatternMatch; 19c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 20c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// MatchSelectPattern - Pattern match integer [SU]MIN, [SU]MAX, and ABS idioms, 21c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// returning the kind and providing the out parameter results if we 22c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// successfully match. 23c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic SelectPatternFlavor 24c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerMatchSelectPattern(Value *V, Value *&LHS, Value *&RHS) { 25c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectInst *SI = dyn_cast<SelectInst>(V); 26c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI == 0) return SPF_UNKNOWN; 278d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser 28c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICmpInst *ICI = dyn_cast<ICmpInst>(SI->getCondition()); 29c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ICI == 0) return SPF_UNKNOWN; 308d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser 31c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner LHS = ICI->getOperand(0); 32c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner RHS = ICI->getOperand(1); 338d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser 348d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser // (icmp X, Y) ? X : Y 35c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI->getTrueValue() == ICI->getOperand(0) && 36c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI->getFalseValue() == ICI->getOperand(1)) { 37c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (ICI->getPredicate()) { 38c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: return SPF_UNKNOWN; // Equality. 39c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGT: 40c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGE: return SPF_UMAX; 41c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGT: 42c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGE: return SPF_SMAX; 43c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULT: 44c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULE: return SPF_UMIN; 45c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLT: 46c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLE: return SPF_SMIN; 47c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 48c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 498d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser 508d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser // (icmp X, Y) ? Y : X 51c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI->getTrueValue() == ICI->getOperand(1) && 52c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI->getFalseValue() == ICI->getOperand(0)) { 53c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (ICI->getPredicate()) { 54c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: return SPF_UNKNOWN; // Equality. 55c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGT: 56c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_UGE: return SPF_UMIN; 57c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGT: 58c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SGE: return SPF_SMIN; 59c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULT: 60c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULE: return SPF_UMAX; 61c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLT: 62c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_SLE: return SPF_SMAX; 63c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 64c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 658d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser 66c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5) 678d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser 68c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return SPF_UNKNOWN; 69c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 70c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 71c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 72c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// GetSelectFoldableOperands - We want to turn code that looks like this: 73c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// %C = or %A, %B 74c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// %D = select %cond, %C, %A 75c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// into: 76c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// %C = select %cond, %B, 0 77c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// %D = or %A, %C 78c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 79c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// Assuming that the specified instruction is an operand to the select, return 80c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// a bitmask indicating which operands of this instruction are foldable if they 81c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// equal the other incoming value of the select. 82c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 83c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic unsigned GetSelectFoldableOperands(Instruction *I) { 84c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (I->getOpcode()) { 85c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Add: 86c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Mul: 87c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::And: 88c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Or: 89c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Xor: 90c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 3; // Can fold through either operand. 91c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Sub: // Can only fold on the amount subtracted. 92c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Shl: // Can only fold on the shift amount. 93c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::LShr: 94c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::AShr: 95c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 1; 96c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: 97c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; // Cannot fold 98c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 99c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 100c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 101c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// GetSelectFoldableConstant - For the same transformation as the previous 102c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// function, return the identity constant that goes into the select. 103c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic Constant *GetSelectFoldableConstant(Instruction *I) { 104c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner switch (I->getOpcode()) { 105c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: llvm_unreachable("This cannot happen!"); 106c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Add: 107c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Sub: 108c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Or: 109c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Xor: 110c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Shl: 111c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::LShr: 112c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::AShr: 113c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return Constant::getNullValue(I->getType()); 114c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::And: 115c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return Constant::getAllOnesValue(I->getType()); 116c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case Instruction::Mul: 117c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ConstantInt::get(I->getType(), 1); 118c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 119c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 120c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 121c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI 122c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// have the same opcode and only one use each. Try to simplify this. 123c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI, 124c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *FI) { 125c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->getNumOperands() == 1) { 126c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // If this is a non-volatile load or a cast from the same type, 127c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // merge. 128c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->isCast()) { 129c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType()) 130c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 131c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else { 132c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; // unknown unary op. 133c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 134c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 135c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Fold this by inserting a select from the input values. 136c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0), 137c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner FI->getOperand(0), SI.getName()+".v"); 138c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(NewSI, SI); 1398d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI, 140c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner TI->getType()); 141c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 142c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 143c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Only handle binary operators here. 144c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!isa<BinaryOperator>(TI)) 145c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 146c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 147c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Figure out if the operations have any operands in common. 148c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *MatchOp, *OtherOpT, *OtherOpF; 149c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner bool MatchIsOpZero; 150c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->getOperand(0) == FI->getOperand(0)) { 151c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchOp = TI->getOperand(0); 152c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpT = TI->getOperand(1); 153c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF = FI->getOperand(1); 154c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchIsOpZero = true; 155c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (TI->getOperand(1) == FI->getOperand(1)) { 156c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchOp = TI->getOperand(1); 157c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpT = TI->getOperand(0); 158c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF = FI->getOperand(0); 159c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchIsOpZero = false; 160c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (!TI->isCommutative()) { 161c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 162c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (TI->getOperand(0) == FI->getOperand(1)) { 163c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchOp = TI->getOperand(0); 164c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpT = TI->getOperand(1); 165c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF = FI->getOperand(0); 166c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchIsOpZero = true; 167c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (TI->getOperand(1) == FI->getOperand(0)) { 168c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchOp = TI->getOperand(1); 169c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpT = TI->getOperand(0); 170c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF = FI->getOperand(1); 171c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner MatchIsOpZero = true; 172c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else { 173c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 174c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 175c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 176c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // If we reach here, they do have operations in common. 177c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT, 178c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherOpF, SI.getName()+".v"); 179c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(NewSI, SI); 180c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 181c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) { 182c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (MatchIsOpZero) 183c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI); 184c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner else 185c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp); 186c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 187c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner llvm_unreachable("Shouldn't get here"); 188c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 189c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 190c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 191c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattnerstatic bool isSelect01(Constant *C1, Constant *C2) { 192c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantInt *C1I = dyn_cast<ConstantInt>(C1); 193c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!C1I) 194c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return false; 195c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantInt *C2I = dyn_cast<ConstantInt>(C2); 196c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!C2I) 197c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return false; 1984ac19470dc26decba85f5bf4dd7e6edb54d77152Benjamin Kramer return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne()); 1994ac19470dc26decba85f5bf4dd7e6edb54d77152Benjamin Kramer} 2004ac19470dc26decba85f5bf4dd7e6edb54d77152Benjamin Kramer 2014ac19470dc26decba85f5bf4dd7e6edb54d77152Benjamin Kramer/// FoldSelectIntoOp - Try fold the select into one of the operands to 202c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// facilitate further optimization. 203c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal, 204c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *FalseVal) { 205c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See the comment above GetSelectFoldableOperands for a description of the 206c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // transformation we are doing here. 207c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) { 208c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TVI->hasOneUse() && TVI->getNumOperands() == 2 && 209c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !isa<Constant>(FalseVal)) { 210c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (unsigned SFO = GetSelectFoldableOperands(TVI)) { 211c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner unsigned OpToFold = 0; 212c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((SFO & 1) && FalseVal == TVI->getOperand(0)) { 213c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OpToFold = 1; 214c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) { 215c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OpToFold = 2; 216c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 217c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 218c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (OpToFold) { 219c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Constant *C = GetSelectFoldableConstant(TVI); 220c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *OOp = TVI->getOperand(2-OpToFold); 221c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Avoid creating select between 2 constants unless it's selecting 222c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // between 0 and 1. 223c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) { 224c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C); 2254ac19470dc26decba85f5bf4dd7e6edb54d77152Benjamin Kramer InsertNewInstBefore(NewSel, SI); 226c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NewSel->takeName(TVI); 227c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI)) 228c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel); 229c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner llvm_unreachable("Unknown instruction!!"); 230c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 231c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 232c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 233c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 234c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 235c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 236c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) { 237c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FVI->hasOneUse() && FVI->getNumOperands() == 2 && 238c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !isa<Constant>(TrueVal)) { 239c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (unsigned SFO = GetSelectFoldableOperands(FVI)) { 240c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner unsigned OpToFold = 0; 241c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((SFO & 1) && TrueVal == FVI->getOperand(0)) { 242c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OpToFold = 1; 243c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) { 244c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OpToFold = 2; 245c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 246c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 247c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (OpToFold) { 248c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Constant *C = GetSelectFoldableConstant(FVI); 249c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *OOp = FVI->getOperand(2-OpToFold); 250c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Avoid creating select between 2 constants unless it's selecting 251c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // between 0 and 1. 252c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) { 253c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp); 2544ac19470dc26decba85f5bf4dd7e6edb54d77152Benjamin Kramer InsertNewInstBefore(NewSel, SI); 255c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NewSel->takeName(FVI); 256c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI)) 257c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel); 258c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner llvm_unreachable("Unknown instruction!!"); 259c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 260c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 261c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 262c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 263c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 264c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 265c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 266c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 267c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 268c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// visitSelectInstWithICmp - Visit a SelectInst that has an 269c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// ICmpInst as its first operand. 270c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// 271c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI, 272c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICmpInst *ICI) { 273c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner bool Changed = false; 274c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICmpInst::Predicate Pred = ICI->getPredicate(); 275c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *CmpLHS = ICI->getOperand(0); 276c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *CmpRHS = ICI->getOperand(1); 277c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *TrueVal = SI.getTrueValue(); 278c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *FalseVal = SI.getFalseValue(); 279c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 280c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Check cases where the comparison is with a constant that 281c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // can be adjusted to fit the min/max idiom. We may edit ICI in 282c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // place here, so make sure the select is the only user. 283c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ICI->hasOneUse()) 284aa2be8435693dfe73dac64de3e2b6b3f19df1eacTobias Grosser if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) { 285aa2be8435693dfe73dac64de3e2b6b3f19df1eacTobias Grosser switch (Pred) { 286c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner default: break; 287c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner case ICmpInst::ICMP_ULT: 28846431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser case ICmpInst::ICMP_SLT: { 28946431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // X < MIN ? T : F --> F 29046431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT)) 29146431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser return ReplaceInstUsesWith(SI, FalseVal); 29246431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // X < C ? X : C-1 --> X > C-1 ? C-1 : X 29346431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser Constant *AdjustedRHS = 29446431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser ConstantInt::get(CI->getContext(), CI->getValue()-1); 29546431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) || 296c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) { 297c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Pred = ICmpInst::getSwappedPredicate(Pred); 298c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner CmpRHS = AdjustedRHS; 29946431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser std::swap(FalseVal, TrueVal); 300c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICI->setPredicate(Pred); 301c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ICI->setOperand(1, CmpRHS); 302b686eb9186ebefe54b4d33846eb07e1ab0beb234Frits van Bommel SI.setOperand(1, TrueVal); 303b686eb9186ebefe54b4d33846eb07e1ab0beb234Frits van Bommel SI.setOperand(2, FalseVal); 304b686eb9186ebefe54b4d33846eb07e1ab0beb234Frits van Bommel Changed = true; 305b686eb9186ebefe54b4d33846eb07e1ab0beb234Frits van Bommel } 306b686eb9186ebefe54b4d33846eb07e1ab0beb234Frits van Bommel break; 30746431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 30846431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser case ICmpInst::ICMP_UGT: 30946431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser case ICmpInst::ICMP_SGT: { 31046431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // X > MAX ? T : F --> F 31146431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT)) 31246431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser return ReplaceInstUsesWith(SI, FalseVal); 313c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // X > C ? X : C+1 --> X < C+1 ? C+1 : X 31446431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser Constant *AdjustedRHS = 315c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantInt::get(CI->getContext(), CI->getValue()+1); 31646431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) || 31746431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) { 31846431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser Pred = ICmpInst::getSwappedPredicate(Pred); 31946431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser CmpRHS = AdjustedRHS; 32046431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser std::swap(FalseVal, TrueVal); 32146431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser ICI->setPredicate(Pred); 32246431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser ICI->setOperand(1, CmpRHS); 323b686eb9186ebefe54b4d33846eb07e1ab0beb234Frits van Bommel SI.setOperand(1, TrueVal); 324b686eb9186ebefe54b4d33846eb07e1ab0beb234Frits van Bommel SI.setOperand(2, FalseVal); 32546431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser Changed = true; 32646431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 32746431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser break; 32846431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 32946431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 33046431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 33146431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser 33246431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // Transform (X >s -1) ? C1 : C2 --> ((X >>s 31) & (C2 - C1)) + C1 33346431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // and (X <s 0) ? C2 : C1 --> ((X >>s 31) & (C2 - C1)) + C1 33446431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // FIXME: Type and constness constraints could be lifted, but we have to 33546431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // watch code size carefully. We should consider xor instead of 33646431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // sub/add when we decide to do that. 33746431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (const IntegerType *Ty = dyn_cast<IntegerType>(CmpLHS->getType())) { 33846431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (TrueVal->getType() == Ty) { 339b686eb9186ebefe54b4d33846eb07e1ab0beb234Frits van Bommel if (ConstantInt *Cmp = dyn_cast<ConstantInt>(CmpRHS)) { 34046431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser ConstantInt *C1 = NULL, *C2 = NULL; 34146431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (Pred == ICmpInst::ICMP_SGT && Cmp->isAllOnesValue()) { 34246431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser C1 = dyn_cast<ConstantInt>(TrueVal); 34346431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser C2 = dyn_cast<ConstantInt>(FalseVal); 34446431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } else if (Pred == ICmpInst::ICMP_SLT && Cmp->isNullValue()) { 34546431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser C1 = dyn_cast<ConstantInt>(FalseVal); 34646431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser C2 = dyn_cast<ConstantInt>(TrueVal); 34746431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 34846431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (C1 && C2) { 34946431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // This shift results in either -1 or 0. 35046431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser Value *AShr = Builder->CreateAShr(CmpLHS, Ty->getBitWidth()-1); 35146431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser 35246431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // Check if we can express the operation with a single or. 35346431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (C2->isAllOnesValue()) 35446431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser return ReplaceInstUsesWith(SI, Builder->CreateOr(AShr, C1)); 35546431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser 35646431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser Value *And = Builder->CreateAnd(AShr, C2->getValue()-C1->getValue()); 35746431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser return ReplaceInstUsesWith(SI, Builder->CreateAdd(And, C1)); 35846431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 35946431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 36046431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 36146431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } 36246431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser 36346431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (CmpLHS == TrueVal && CmpRHS == FalseVal) { 36446431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser // Transform (X == Y) ? X : Y -> Y 36546431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser if (Pred == ICmpInst::ICMP_EQ) 36646431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser return ReplaceInstUsesWith(SI, FalseVal); 367aa2be8435693dfe73dac64de3e2b6b3f19df1eacTobias Grosser // Transform (X != Y) ? X : Y -> X 368aa2be8435693dfe73dac64de3e2b6b3f19df1eacTobias Grosser if (Pred == ICmpInst::ICMP_NE) 369aa2be8435693dfe73dac64de3e2b6b3f19df1eacTobias Grosser return ReplaceInstUsesWith(SI, TrueVal); 370aa2be8435693dfe73dac64de3e2b6b3f19df1eacTobias Grosser /// NOTE: if we wanted to, this is where to detect integer MIN/MAX 371aa2be8435693dfe73dac64de3e2b6b3f19df1eacTobias Grosser 37246431d7a931ecc54d563a7674977a9a566b1d4fbTobias Grosser } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) { 373c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X == Y) ? Y : X -> X 374c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Pred == ICmpInst::ICMP_EQ) 375c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, FalseVal); 376c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Transform (X != Y) ? Y : X -> Y 377c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Pred == ICmpInst::ICMP_NE) 3781db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer return ReplaceInstUsesWith(SI, TrueVal); 3791db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer /// NOTE: if we wanted to, this is where to detect integer MIN/MAX 3801db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer } 3811db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer return Changed ? &SI : 0; 3821db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer} 3831db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer 3841db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer 3851db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// CanSelectOperandBeMappingIntoPredBlock - SI is a select whose condition is a 3861db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// PHI node (but the two may be in different blocks). See if the true/false 3871db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// values (V) are live in all of the predecessor blocks of the PHI. For 3881db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// example, cases like this cannot be mapped: 3891db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// 3901db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// X = phi [ C1, BB1], [C2, BB2] 3911db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// Y = add 3921db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// Z = select X, Y, 0 3931db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// 3941db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// because Y is not live in BB1/BB2. 3951db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer/// 3961db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramerstatic bool CanSelectOperandBeMappingIntoPredBlock(const Value *V, 3971db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer const SelectInst &SI) { 3981db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer // If the value is a non-instruction value like a constant or argument, it 3991db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer // can always be mapped. 4001db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer const Instruction *I = dyn_cast<Instruction>(V); 4011db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer if (I == 0) return true; 4021db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer 4031db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer // If V is a PHI node defined in the same block as the condition PHI, we can 4041db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer // map the arguments. 4051db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer const PHINode *CondPHI = cast<PHINode>(SI.getCondition()); 4061db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer 4071db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer if (const PHINode *VP = dyn_cast<PHINode>(I)) 4081db071f0dae25d0c5a1af61ca71fa20d0a8e9370Benjamin Kramer if (VP->getParent() == CondPHI->getParent()) 409c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return true; 410c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 411c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Otherwise, if the PHI and select are defined in the same block and if V is 412c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // defined in a different block, then we can transform it. 413c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI.getParent() == CondPHI->getParent() && 414c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner I->getParent() != CondPHI->getParent()) 415c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return true; 416c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 417c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Otherwise we have a 'hard' case and we can't tell without doing more 418c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // detailed dominator based analysis, punt. 419c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return false; 420c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 421c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 422c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form: 423c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner/// SPF2(SPF1(A, B), C) 424c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::FoldSPFofSPF(Instruction *Inner, 425c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectPatternFlavor SPF1, 426c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *A, Value *B, 427c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction &Outer, 428c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SelectPatternFlavor SPF2, Value *C) { 429c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (C == A || C == B) { 430c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MAX(MAX(A, B), B) -> MAX(A, B) 431c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MIN(MIN(a, b), a) -> MIN(a, b) 432c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SPF1 == SPF2) 433c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(Outer, Inner); 434c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 435c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MAX(MIN(a, b), a) -> a 436c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MIN(MAX(a, b), a) -> a 437c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) || 438c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) || 439c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) || 440c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN)) 441c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(Outer, C); 442c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 443c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 444c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // TODO: MIN(MIN(A, 23), 97) 445c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 446c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 447c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 4488d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser 449c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 450c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 451c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris LattnerInstruction *InstCombiner::visitSelectInst(SelectInst &SI) { 4528d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser Value *CondVal = SI.getCondition(); 453c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *TrueVal = SI.getTrueValue(); 454c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *FalseVal = SI.getFalseValue(); 455c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 4568d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal, TD)) 457c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, V); 458c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 459c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SI.getType()->isIntegerTy(1)) { 460c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) { 461c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (C->getZExtValue()) { 4628d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser // Change: A = select B, true, C --> A = or B, C 463c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateOr(CondVal, FalseVal); 464c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 465c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Change: A = select B, false, C --> A = and !B, C 466c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NotCond = 467c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(BinaryOperator::CreateNot(CondVal, 468c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner "not."+CondVal->getName()), SI); 4698d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser return BinaryOperator::CreateAnd(NotCond, FalseVal); 470c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) { 471c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (C->getZExtValue() == false) { 472c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Change: A = select B, C, false --> A = and B, C 473c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateAnd(CondVal, TrueVal); 474c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 475c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Change: A = select B, C, true --> A = or !B, C 476c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NotCond = 477c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner InsertNewInstBefore(BinaryOperator::CreateNot(CondVal, 478c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner "not."+CondVal->getName()), SI); 479c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateOr(NotCond, TrueVal); 4808d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser } 481c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 482c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select a, b, a -> a&b 483c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select a, a, b -> a|b 484c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (CondVal == TrueVal) 485c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateOr(CondVal, FalseVal); 486c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner else if (CondVal == FalseVal) 487c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return BinaryOperator::CreateAnd(CondVal, TrueVal); 488c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 4898d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser 490c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // Selecting between two integer constants? 491c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal)) 492c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) { 493c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select C, 1, 0 -> zext C to int 494c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (FalseValC->isZero() && TrueValC->getValue() == 1) 49520e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer return new ZExtInst(CondVal, SI.getType()); 49620e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer 49720e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // select C, -1, 0 -> sext C to int 49820e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (FalseValC->isZero() && TrueValC->isAllOnesValue()) 49920e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer return new SExtInst(CondVal, SI.getType()); 50020e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer 50120e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // select C, 0, 1 -> zext !C to int 50220e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (TrueValC->isZero() && FalseValC->getValue() == 1) { 50320e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer Value *NotCond = Builder->CreateNot(CondVal, "not."+CondVal->getName()); 50420e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer return new ZExtInst(NotCond, SI.getType()); 50520e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer } 5066b4972518cff5b0f76ec63fc8b93b74ae64c3f3dBenjamin Kramer 5076b4972518cff5b0f76ec63fc8b93b74ae64c3f3dBenjamin Kramer // select C, 0, -1 -> sext !C to int 50820e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (TrueValC->isZero() && FalseValC->isAllOnesValue()) { 50920e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer Value *NotCond = Builder->CreateNot(CondVal, "not."+CondVal->getName()); 51020e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer return new SExtInst(NotCond, SI.getType()); 51120e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer } 51220e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer 51320e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) { 51420e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // If one of the constants is zero (we know they can't both be) and we 5152f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer // have an icmp instruction with zero, and we have an 'and' with the 5162f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer // non-constant value, eliminate this whole mess. This corresponds to 5172f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer // cases like this: ((X & 27) ? 27 : 0) 5182f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer if (TrueValC->isZero() || FalseValC->isZero()) 5192f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) && 5202f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer cast<Constant>(IC->getOperand(1))->isNullValue()) 5212f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0))) 5222f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer if (ICA->getOpcode() == Instruction::And && 5232f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer isa<ConstantInt>(ICA->getOperand(1)) && 5242f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer (ICA->getOperand(1) == TrueValC || 5252f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer ICA->getOperand(1) == FalseValC) && 5262f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer cast<ConstantInt>(ICA->getOperand(1))->getValue().isPowerOf2()) { 5272f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer // Okay, now we know that everything is set up, we just don't 5282f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer // know whether we have a icmp_ne or icmp_eq and whether the 5292f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer // true or false val is the zero. 5302f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer bool ShouldNotVal = !TrueValC->isZero(); 5312f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE; 5322f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer Value *V = ICA; 53320e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (ShouldNotVal) 53420e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer V = Builder->CreateXor(V, ICA->getOperand(1)); 53520e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer return ReplaceInstUsesWith(SI, V); 53620e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer } 53720e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer } 53820e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer } 53920e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer 54020e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // See if we are selecting two values based on a comparison of the two values. 54120e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) { 54220e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) { 54320e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // Transform (X == Y) ? X : Y -> Y 54420e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { 54520e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // This is not safe in general for floating point: 54620e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // consider X== -0, Y== +0. 54720e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // It becomes safe if either operand is a nonzero constant. 54820e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer ConstantFP *CFPt, *CFPf; 54920e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) && 55020e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer !CFPt->getValueAPF().isZero()) || 55120e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer ((CFPf = dyn_cast<ConstantFP>(FalseVal)) && 55220e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer !CFPf->getValueAPF().isZero())) 55320e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer return ReplaceInstUsesWith(SI, FalseVal); 55420e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer } 55520e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // Transform (X une Y) ? X : Y -> X 55620e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (FCI->getPredicate() == FCmpInst::FCMP_UNE) { 55720e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer // This is not safe in general for floating point: 5582f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer // consider X== -0, Y== +0. 5592f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer // It becomes safe if either operand is a nonzero constant. 5602f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer ConstantFP *CFPt, *CFPf; 5612f7228b80c6a129fa1d8eef8c3075085003d5b87Benjamin Kramer if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) && 56220e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer !CFPt->getValueAPF().isZero()) || 56320e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer ((CFPf = dyn_cast<ConstantFP>(FalseVal)) && 564c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !CFPf->getValueAPF().isZero())) 565c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return ReplaceInstUsesWith(SI, TrueVal); 566c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 567c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // NOTE: if we wanted to, this is where to detect MIN/MAX 568c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 569c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){ 570047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner // Transform (X == Y) ? Y : X -> X 571047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { 572c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // This is not safe in general for floating point: 573b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands // consider X== -0, Y== +0. 574c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // It becomes safe if either operand is a nonzero constant. 575c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantFP *CFPt, *CFPf; 576c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) && 577c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner !CFPt->getValueAPF().isZero()) || 578c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ((CFPf = dyn_cast<ConstantFP>(FalseVal)) && 579047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner !CFPf->getValueAPF().isZero())) 580047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner return ReplaceInstUsesWith(SI, FalseVal); 581047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner } 582047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner // Transform (X une Y) ? Y : X -> Y 583047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner if (FCI->getPredicate() == FCmpInst::FCMP_UNE) { 584c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // This is not safe in general for floating point: 585c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // consider X== -0, Y== +0. 586c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // It becomes safe if either operand is a nonzero constant. 587c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner ConstantFP *CFPt, *CFPf; 588c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) && 589047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner !CFPt->getValueAPF().isZero()) || 590047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner ((CFPf = dyn_cast<ConstantFP>(FalseVal)) && 591047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner !CFPf->getValueAPF().isZero())) 592047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner return ReplaceInstUsesWith(SI, TrueVal); 593047542669a20505fc7c5f2d93caa5610aa3db2c5Chris Lattner } 594c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // NOTE: if we wanted to, this is where to detect MIN/MAX 5958d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser } 596c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // NOTE: if we wanted to, this is where to detect ABS 597c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 598c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 599c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See if we are selecting two values based on a comparison of the two values. 600c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal)) 601c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *Result = visitSelectInstWithICmp(SI, ICI)) 602c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return Result; 603c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 604c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *TI = dyn_cast<Instruction>(TrueVal)) 605c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *FI = dyn_cast<Instruction>(FalseVal)) 606c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (TI->hasOneUse() && FI->hasOneUse()) { 607c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Instruction *AddOp = 0, *SubOp = 0; 608abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner 609abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z)) 610abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner if (TI->getOpcode() == FI->getOpcode()) 611abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner if (Instruction *IV = FoldSelectOpOp(SI, TI, FI)) 612abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner return IV; 613abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner 6148d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is 615abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner // even legal for FP. 616abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner if ((TI->getOpcode() == Instruction::Sub && 617abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner FI->getOpcode() == Instruction::Add) || 618abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner (TI->getOpcode() == Instruction::FSub && 619c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner FI->getOpcode() == Instruction::FAdd)) { 620c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner AddOp = FI; SubOp = TI; 621abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner } else if ((FI->getOpcode() == Instruction::Sub && 622abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner TI->getOpcode() == Instruction::Add) || 623abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner (FI->getOpcode() == Instruction::FSub && 624abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner TI->getOpcode() == Instruction::FAdd)) { 625abb992d6a3d2dc05d3f3c62a367ea8977a7dd070Chris Lattner AddOp = TI; SubOp = FI; 62620e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer } 62720e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer 62820e3b4b380e949af32eeb4f184c51bfd62286f1aBenjamin Kramer if (AddOp) { 629c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *OtherAddOp = 0; 630c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SubOp->getOperand(0) == AddOp->getOperand(0)) { 631c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherAddOp = AddOp->getOperand(1); 632c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) { 633c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner OtherAddOp = AddOp->getOperand(0); 634c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 635c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 6368d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser if (OtherAddOp) { 637c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // So at this point we know we have (Y -> OtherAddOp): 638c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // select C, (add X, Y), (sub X, Z) 639c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *NegVal; // Compute -Z 640c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) { 641c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NegVal = ConstantExpr::getNeg(C); 642c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } else { 643c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NegVal = InsertNewInstBefore( 644c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner BinaryOperator::CreateNeg(SubOp->getOperand(1), 645c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner "tmp"), SI); 64621dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman } 64721dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman 6488d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser Value *NewTrueOp = OtherAddOp; 64921dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman Value *NewFalseOp = NegVal; 65021dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman if (AddOp != TI) 65121dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman std::swap(NewTrueOp, NewFalseOp); 65221dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman Instruction *NewSel = 65321dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman SelectInst::Create(CondVal, NewTrueOp, 65421dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman NewFalseOp, SI.getName() + ".p"); 65521dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman 656c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner NewSel = InsertNewInstBefore(NewSel, SI); 65721dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel); 658c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 659c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 660c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 661c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 662c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See if we can fold the select into one of our operands. 6638d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser if (SI.getType()->isIntegerTy()) { 664c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal)) 665c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return FoldI; 666c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 667c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MAX(MAX(a, b), a) -> MAX(a, b) 668c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MIN(MIN(a, b), a) -> MIN(a, b) 669c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MAX(MIN(a, b), a) -> a 670c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // MIN(MAX(a, b), a) -> a 671c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner Value *LHS, *RHS, *LHS2, *RHS2; 672c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (SelectPatternFlavor SPF = MatchSelectPattern(&SI, LHS, RHS)) { 67321dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman if (SelectPatternFlavor SPF2 = MatchSelectPattern(LHS, LHS2, RHS2)) 67421dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2, 6758d088bd1e4543e48f6e085885ab3a944fb3f2c93Tobias Grosser SI, SPF, RHS)) 67621dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman return R; 67721dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman if (SelectPatternFlavor SPF2 = MatchSelectPattern(RHS, LHS2, RHS2)) 67821dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman if (Instruction *R = FoldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2, 67921dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman SI, SPF, LHS)) 68021dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman return R; 68121dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman } 68221dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman 68321dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman // TODO. 68421dc20cbd62e0b4617cad7df947318801eec81e6Dan Gohman // ABS(-X) -> ABS(X) 685c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // ABS(ABS(X)) -> ABS(X) 686c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 687c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 688c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // See if we can fold the select into a phi node if the condition is a select. 689c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (isa<PHINode>(SI.getCondition())) 690c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner // The true/false values have to be live in the PHI predecessor's blocks. 691c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (CanSelectOperandBeMappingIntoPredBlock(TrueVal, SI) && 692c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner CanSelectOperandBeMappingIntoPredBlock(FalseVal, SI)) 693c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (Instruction *NV = FoldOpIntoPhi(SI)) 694c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return NV; 695c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 696c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner if (BinaryOperator::isNot(CondVal)) { 697c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(0, BinaryOperator::getNotArgument(CondVal)); 698c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(1, FalseVal); 699c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner SI.setOperand(2, TrueVal); 700c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return &SI; 701c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner } 702c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner 703c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner return 0; 704c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner} 705c6334b97e1de7c7c67c7279bdc44eb99ea65c78cChris Lattner