Reassociate.cpp revision cb2610ea037a17115ef3a01a6bdaab4e3cfdca27
14fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner//===- Reassociate.cpp - Reassociate binary expressions -------------------===// 24fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// 34fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// This pass reassociates commutative expressions in an order that is designed 44fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// to promote better constant propogation, GCSE, LICM, PRE... 54fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// 64fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// For example: 4 + (x + 5) -> x + (4 + 5) 74fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// 84fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// Note that this pass works best if left shifts have been promoted to explicit 94fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// multiplies before this pass executes. 104fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// 114fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// In the implementation of this algorithm, constants are assigned rank = 0, 124fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// function arguments are rank = 1, and other values are assigned ranks 134fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// corresponding to the reverse post order traversal of current function 144fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// (starting at 2), which effectively gives values in deep loops higher rank 154fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// than values not in loops. 164fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// 174fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner//===----------------------------------------------------------------------===// 184fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 194fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Transforms/Scalar.h" 204fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Function.h" 214fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/iOperators.h" 224fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Type.h" 234fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Pass.h" 244fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Constant.h" 254fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Support/CFG.h" 264fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "Support/PostOrderIterator.h" 27a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner#include "Support/Statistic.h" 284fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 294fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnernamespace { 30a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner Statistic<> NumLinear ("reassociate","Number of insts linearized"); 31a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner Statistic<> NumChanged("reassociate","Number of insts reassociated"); 32a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner Statistic<> NumSwapped("reassociate","Number of insts with operands swapped"); 33a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner 344fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner class Reassociate : public FunctionPass { 350c0edf8afc35a42b15a24ebb5fa5f3fc674290aeChris Lattner std::map<BasicBlock*, unsigned> RankMap; 364fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner public: 377e70829632f82de15db187845666aaca6e04b792Chris Lattner bool runOnFunction(Function &F); 384fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 394fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 40cb2610ea037a17115ef3a01a6bdaab4e3cfdca27Chris Lattner AU.setPreservesCFG(); 414fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 424fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner private: 437e70829632f82de15db187845666aaca6e04b792Chris Lattner void BuildRankMap(Function &F); 444fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned getRank(Value *V); 454fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool ReassociateExpr(BinaryOperator *I); 464fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool ReassociateBB(BasicBlock *BB); 474fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner }; 48f629309f74cf1a64aa7fd1cd5784fd7db9a8f59eChris Lattner 49a6275ccdf5e1aa208afde56c498e2b13e16442f0Chris Lattner RegisterOpt<Reassociate> X("reassociate", "Reassociate expressions"); 504fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 514fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 524fd56003ab29e3662c909bb10e47daa97ceb55abChris LattnerPass *createReassociatePass() { return new Reassociate(); } 534fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 547e70829632f82de15db187845666aaca6e04b792Chris Lattnervoid Reassociate::BuildRankMap(Function &F) { 554fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned i = 1; 567e70829632f82de15db187845666aaca6e04b792Chris Lattner ReversePostOrderTraversal<Function*> RPOT(&F); 574fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(), 584fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner E = RPOT.end(); I != E; ++I) 594fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner RankMap[*I] = ++i; 604fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 614fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 624fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnerunsigned Reassociate::getRank(Value *V) { 634fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (isa<Argument>(V)) return 1; // Function argument... 644fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (Instruction *I = dyn_cast<Instruction>(V)) { 654fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // If this is an expression, return the MAX(rank(LHS), rank(RHS)) so that we 664fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // can reassociate expressions for code motion! Since we do not recurse for 674fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // PHI nodes, we cannot have infinite recursion here, because there cannot 684fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // be loops in the value graph (except for PHI nodes). 694fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // 704fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (I->getOpcode() == Instruction::PHINode || 714fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->getOpcode() == Instruction::Alloca || 724fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->getOpcode() == Instruction::Malloc || isa<TerminatorInst>(I) || 734fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->hasSideEffects()) 744fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return RankMap[I->getParent()]; 754fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 76a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner unsigned Rank = 0, MaxRank = RankMap[I->getParent()]; 77a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner for (unsigned i = 0, e = I->getNumOperands(); 78a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner i != e && Rank != MaxRank; ++i) 794fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Rank = std::max(Rank, getRank(I->getOperand(i))); 804fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 814fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return Rank; 824fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 834fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 844fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Otherwise it's a global or constant, rank 0. 854fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return 0; 864fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 874fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 884fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 894fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// isCommutativeOperator - Return true if the specified instruction is 904fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// commutative and associative. If the instruction is not commutative and 914fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// associative, we can not reorder its operands! 924fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// 934fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnerstatic inline BinaryOperator *isCommutativeOperator(Instruction *I) { 944fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Floating point operations do not commute! 954fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (I->getType()->isFloatingPoint()) return 0; 964fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 974fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (I->getOpcode() == Instruction::Add || 984fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->getOpcode() == Instruction::Mul || 994fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->getOpcode() == Instruction::And || 1004fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->getOpcode() == Instruction::Or || 1014fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->getOpcode() == Instruction::Xor) 1024fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return cast<BinaryOperator>(I); 1034fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return 0; 1044fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 1054fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1064fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1074fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnerbool Reassociate::ReassociateExpr(BinaryOperator *I) { 1084fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Value *LHS = I->getOperand(0); 1094fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Value *RHS = I->getOperand(1); 1104fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned LHSRank = getRank(LHS); 1114fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned RHSRank = getRank(RHS); 1124fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1134fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool Changed = false; 1144fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1154fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Make sure the LHS of the operand always has the greater rank... 1164fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (LHSRank < RHSRank) { 1174fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->swapOperands(); 1184fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner std::swap(LHS, RHS); 1194fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner std::swap(LHSRank, RHSRank); 1204fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Changed = true; 1213dec1f272219ee1f8e1499929cdf53f5bc3c2272Chris Lattner ++NumSwapped; 122f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner DEBUG(std::cerr << "Transposed: " << I << " Result BB: " << I->getParent()); 1234fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 1244fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1254fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // If the LHS is the same operator as the current one is, and if we are the 1264fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // only expression using it... 1274fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // 1284fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (BinaryOperator *LHSI = dyn_cast<BinaryOperator>(LHS)) 1294fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (LHSI->getOpcode() == I->getOpcode() && LHSI->use_size() == 1) { 1304fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // If the rank of our current RHS is less than the rank of the LHS's LHS, 1314fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // then we reassociate the two instructions... 1324fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (RHSRank < getRank(LHSI->getOperand(0))) { 1334fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned TakeOp = 0; 1344fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (BinaryOperator *IOp = dyn_cast<BinaryOperator>(LHSI->getOperand(0))) 1354fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (IOp->getOpcode() == LHSI->getOpcode()) 1364fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner TakeOp = 1; // Hoist out non-tree portion 1374fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1384fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Convert ((a + 12) + 10) into (a + (12 + 10)) 1394fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->setOperand(0, LHSI->getOperand(TakeOp)); 1404fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner LHSI->setOperand(TakeOp, RHS); 1414fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->setOperand(1, LHSI); 1424fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1433dec1f272219ee1f8e1499929cdf53f5bc3c2272Chris Lattner ++NumChanged; 144f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner DEBUG(std::cerr << "Reassociated: " << I << " Result BB: " 145f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner << I->getParent()); 1464fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1474fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Since we modified the RHS instruction, make sure that we recheck it. 1484fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner ReassociateExpr(LHSI); 1494fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return true; 1504fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 1514fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 1524fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1534fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return Changed; 1544fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 1554fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1564fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 157a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// NegateValue - Insert instructions before the instruction pointed to by BI, 158a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// that computes the negative version of the value specified. The negative 159a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// version of the value is returned, and BI is left pointing at the instruction 160a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// that should be processed next by the reassociation pass. 161a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// 162a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattnerstatic Value *NegateValue(Value *V, BasicBlock *BB, BasicBlock::iterator &BI) { 163a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // We are trying to expose opportunity for reassociation. One of the things 164a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // that we want to do to achieve this is to push a negation as deep into an 165a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // expression chain as possible, to expose the add instructions. In practice, 166a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // this means that we turn this: 167a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // X = -(A+12+C+D) into X = -A + -12 + -C + -D = -12 + -A + -C + -D 168a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // so that later, a: Y = 12+X could get reassociated with the -12 to eliminate 169a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // the constants. We assume that instcombine will clean up the mess later if 170a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // we introduce tons of unneccesary negation instructions... 171a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 172a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner if (Instruction *I = dyn_cast<Instruction>(V)) 173a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner if (I->getOpcode() == Instruction::Add && I->use_size() == 1) { 174a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Value *RHS = NegateValue(I->getOperand(1), BB, BI); 175a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Value *LHS = NegateValue(I->getOperand(0), BB, BI); 176a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 177a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // We must actually insert a new add instruction here, because the neg 178a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // instructions do not dominate the old add instruction in general. By 179a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // adding it now, we are assured that the neg instructions we just 180a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // inserted dominate the instruction we are about to insert after them. 181a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 1822a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner return BinaryOperator::create(Instruction::Add, LHS, RHS, 1832a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner I->getName()+".neg", 1842a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner cast<Instruction>(RHS)->getNext()); 185a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner } 186a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 187a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Insert a 'neg' instruction that subtracts the value from zero to get the 188a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // negation. 189a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 190a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Instruction *Neg = 191a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner BinaryOperator::create(Instruction::Sub, 192a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Constant::getNullValue(V->getType()), V, 1932a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner V->getName()+".neg", BI); 1942a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner --BI; 195a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner return Neg; 196a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner} 197a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 198a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 1994fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnerbool Reassociate::ReassociateBB(BasicBlock *BB) { 2004fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool Changed = false; 2014fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI) { 2024fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2034fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // If this instruction is a commutative binary operator, and the ranks of 2044fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // the two operands are sorted incorrectly, fix it now. 2054fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // 2067e70829632f82de15db187845666aaca6e04b792Chris Lattner if (BinaryOperator *I = isCommutativeOperator(BI)) { 207a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner if (!I->use_empty()) { 208a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Make sure that we don't have a tree-shaped computation. If we do, 209a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // linearize it. Convert (A+B)+(C+D) into ((A+B)+C)+D 210a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 211a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Instruction *LHSI = dyn_cast<Instruction>(I->getOperand(0)); 212a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Instruction *RHSI = dyn_cast<Instruction>(I->getOperand(1)); 213a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner if (LHSI && (int)LHSI->getOpcode() == I->getOpcode() && 214a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner RHSI && (int)RHSI->getOpcode() == I->getOpcode() && 215a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner RHSI->use_size() == 1) { 216a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Insert a new temporary instruction... (A+B)+C 217a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner BinaryOperator *Tmp = BinaryOperator::create(I->getOpcode(), LHSI, 218a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner RHSI->getOperand(0), 2192a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner RHSI->getName()+".ra", 2202a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner BI); 2212a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner BI = Tmp; 222a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner I->setOperand(0, Tmp); 223a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner I->setOperand(1, RHSI->getOperand(1)); 224a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 225a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Process the temporary instruction for reassociation now. 226a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner I = Tmp; 227a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner ++NumLinear; 228a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Changed = true; 229f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner DEBUG(std::cerr << "Linearized: " << I << " Result BB: " << BB); 230a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner } 231a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 232a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Make sure that this expression is correctly reassociated with respect 233a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // to it's used values... 234a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 235a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Changed |= ReassociateExpr(I); 236a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner } 2374fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2387e70829632f82de15db187845666aaca6e04b792Chris Lattner } else if (BI->getOpcode() == Instruction::Sub && 2397e70829632f82de15db187845666aaca6e04b792Chris Lattner BI->getOperand(0) != Constant::getNullValue(BI->getType())) { 2404fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Convert a subtract into an add and a neg instruction... so that sub 2414fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // instructions can be commuted with other add instructions... 2424fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // 2434fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Instruction *New = BinaryOperator::create(Instruction::Add, 2447e70829632f82de15db187845666aaca6e04b792Chris Lattner BI->getOperand(0), 2457e70829632f82de15db187845666aaca6e04b792Chris Lattner BI->getOperand(1), 2467e70829632f82de15db187845666aaca6e04b792Chris Lattner BI->getName()); 2477e70829632f82de15db187845666aaca6e04b792Chris Lattner Value *NegatedValue = BI->getOperand(1); 248a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 2494fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Everyone now refers to the add instruction... 2507e70829632f82de15db187845666aaca6e04b792Chris Lattner BI->replaceAllUsesWith(New); 2514fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 252a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Put the new add in the place of the subtract... deleting the subtract 2537e70829632f82de15db187845666aaca6e04b792Chris Lattner BI = BB->getInstList().erase(BI); 2547e70829632f82de15db187845666aaca6e04b792Chris Lattner BI = ++BB->getInstList().insert(BI, New); 255a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 256a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Calculate the negative value of Operand 1 of the sub instruction... 257a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // and set it as the RHS of the add instruction we just made... 258a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner New->setOperand(1, NegateValue(NegatedValue, BB, BI)); 259a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner --BI; 2604fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Changed = true; 261f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner DEBUG(std::cerr << "Negated: " << New << " Result BB: " << BB); 2624fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 2634fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 2644fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2654fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return Changed; 2664fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 2674fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2684fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2697e70829632f82de15db187845666aaca6e04b792Chris Lattnerbool Reassociate::runOnFunction(Function &F) { 2704fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Recalculate the rank map for F 2714fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner BuildRankMap(F); 2724fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2734fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool Changed = false; 2747e70829632f82de15db187845666aaca6e04b792Chris Lattner for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) 2757e70829632f82de15db187845666aaca6e04b792Chris Lattner Changed |= ReassociateBB(FI); 2764fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2774fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // We are done with the rank map... 2784fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner RankMap.clear(); 2794fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return Changed; 2804fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 281