Reassociate.cpp revision 6007cb6c4d923e2dee4a1133fb6d1bb00a37062d
14fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner//===- Reassociate.cpp - Reassociate binary expressions -------------------===// 24fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// 34fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner// This pass reassociates commutative expressions in an order that is designed 4e96fda3002dd0769d3dd758ac5008ba8cda92349Chris Lattner// to promote better constant propagation, 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// 17e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner// This code was originally written by Chris Lattner, and was then cleaned up 18e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner// and perfected by Casey Carter. 19e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner// 204fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner//===----------------------------------------------------------------------===// 214fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 224fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Transforms/Scalar.h" 234fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Function.h" 244fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/iOperators.h" 254fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Type.h" 264fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Pass.h" 274fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Constant.h" 284fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "llvm/Support/CFG.h" 296806f5614d2ec260fda954c951d33f58e77ed610Chris Lattner#include "Support/Debug.h" 304fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner#include "Support/PostOrderIterator.h" 31a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner#include "Support/Statistic.h" 324fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 334fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnernamespace { 34a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner Statistic<> NumLinear ("reassociate","Number of insts linearized"); 35a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner Statistic<> NumChanged("reassociate","Number of insts reassociated"); 36a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner Statistic<> NumSwapped("reassociate","Number of insts with operands swapped"); 37a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner 384fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner class Reassociate : public FunctionPass { 390c0edf8afc35a42b15a24ebb5fa5f3fc674290aeChris Lattner std::map<BasicBlock*, unsigned> RankMap; 404d0a82da2daab7bd4eb3b3cd7ea28ba15d0db144Chris Lattner std::map<Instruction*, unsigned> InstRankMap; 414fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner public: 427e70829632f82de15db187845666aaca6e04b792Chris Lattner bool runOnFunction(Function &F); 434fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 444fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 45cb2610ea037a17115ef3a01a6bdaab4e3cfdca27Chris Lattner AU.setPreservesCFG(); 464fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 474fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner private: 487e70829632f82de15db187845666aaca6e04b792Chris Lattner void BuildRankMap(Function &F); 494fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned getRank(Value *V); 504fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool ReassociateExpr(BinaryOperator *I); 514fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool ReassociateBB(BasicBlock *BB); 524fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner }; 53f629309f74cf1a64aa7fd1cd5784fd7db9a8f59eChris Lattner 54a6275ccdf5e1aa208afde56c498e2b13e16442f0Chris Lattner RegisterOpt<Reassociate> X("reassociate", "Reassociate expressions"); 554fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 564fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 574fd56003ab29e3662c909bb10e47daa97ceb55abChris LattnerPass *createReassociatePass() { return new Reassociate(); } 584fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 597e70829632f82de15db187845666aaca6e04b792Chris Lattnervoid Reassociate::BuildRankMap(Function &F) { 606007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner unsigned i = 2; 617e70829632f82de15db187845666aaca6e04b792Chris Lattner ReversePostOrderTraversal<Function*> RPOT(&F); 624fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(), 634fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner E = RPOT.end(); I != E; ++I) 646007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner RankMap[*I] = ++i << 16; 654fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 664fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 674fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnerunsigned Reassociate::getRank(Value *V) { 684fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (isa<Argument>(V)) return 1; // Function argument... 694fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (Instruction *I = dyn_cast<Instruction>(V)) { 706007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner // If this is an expression, return the 1+MAX(rank(LHS), rank(RHS)) so that 716007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner // we can reassociate expressions for code motion! Since we do not recurse 726007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner // for PHI nodes, we cannot have infinite recursion here, because there 736007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner // cannot be loops in the value graph that do not go through PHI nodes. 744fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // 754fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (I->getOpcode() == Instruction::PHINode || 764fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->getOpcode() == Instruction::Alloca || 774fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->getOpcode() == Instruction::Malloc || isa<TerminatorInst>(I) || 78f0a93ed9c59d706494496c6fe4e8354864d24aa7Chris Lattner I->mayWriteToMemory()) // Cannot move inst if it writes to memory! 794fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return RankMap[I->getParent()]; 804fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 814d0a82da2daab7bd4eb3b3cd7ea28ba15d0db144Chris Lattner unsigned &CachedRank = InstRankMap[I]; 824d0a82da2daab7bd4eb3b3cd7ea28ba15d0db144Chris Lattner if (CachedRank) return CachedRank; // Rank already known? 834d0a82da2daab7bd4eb3b3cd7ea28ba15d0db144Chris Lattner 844d0a82da2daab7bd4eb3b3cd7ea28ba15d0db144Chris Lattner // If not, compute it! 85a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner unsigned Rank = 0, MaxRank = RankMap[I->getParent()]; 86a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner for (unsigned i = 0, e = I->getNumOperands(); 87a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner i != e && Rank != MaxRank; ++i) 884fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Rank = std::max(Rank, getRank(I->getOperand(i))); 894fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 906007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner DEBUG(std::cerr << "Calculated Rank[" << V->getName() << "] = " 916007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner << Rank+1 << "\n"); 926007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner 936007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner return CachedRank = Rank+1; 944fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 954fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 964fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Otherwise it's a global or constant, rank 0. 974fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return 0; 984fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 994fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1004fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1014fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnerbool Reassociate::ReassociateExpr(BinaryOperator *I) { 1024fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Value *LHS = I->getOperand(0); 1034fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Value *RHS = I->getOperand(1); 1044fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned LHSRank = getRank(LHS); 1054fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned RHSRank = getRank(RHS); 1064fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1074fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool Changed = false; 1084fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1094fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Make sure the LHS of the operand always has the greater rank... 1104fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (LHSRank < RHSRank) { 111e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner bool Success = !I->swapOperands(); 112e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner assert(Success && "swapOperands failed"); 113e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner 1144fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner std::swap(LHS, RHS); 1154fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner std::swap(LHSRank, RHSRank); 1164fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner Changed = true; 1173dec1f272219ee1f8e1499929cdf53f5bc3c2272Chris Lattner ++NumSwapped; 118680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner DEBUG(std::cerr << "Transposed: " << I 119680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner /* << " Result BB: " << I->getParent()*/); 1204fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 1214fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1224fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // If the LHS is the same operator as the current one is, and if we are the 1234fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // only expression using it... 1244fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // 1254fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (BinaryOperator *LHSI = dyn_cast<BinaryOperator>(LHS)) 1264fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (LHSI->getOpcode() == I->getOpcode() && LHSI->use_size() == 1) { 1274fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // If the rank of our current RHS is less than the rank of the LHS's LHS, 1284fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // then we reassociate the two instructions... 1294fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (RHSRank < getRank(LHSI->getOperand(0))) { 1304fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner unsigned TakeOp = 0; 1314fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (BinaryOperator *IOp = dyn_cast<BinaryOperator>(LHSI->getOperand(0))) 1324fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner if (IOp->getOpcode() == LHSI->getOpcode()) 1334fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner TakeOp = 1; // Hoist out non-tree portion 1344fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1354fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Convert ((a + 12) + 10) into (a + (12 + 10)) 1364fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner I->setOperand(0, LHSI->getOperand(TakeOp)); 137680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner LHSI->setOperand(TakeOp, RHS); 138680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner I->setOperand(1, LHSI); 139e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner 140e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // Move the LHS expression forward, to ensure that it is dominated by 141e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // its operands. 142680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner LHSI->getParent()->getInstList().remove(LHSI); 143680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner I->getParent()->getInstList().insert(I, LHSI); 1444fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1453dec1f272219ee1f8e1499929cdf53f5bc3c2272Chris Lattner ++NumChanged; 146680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner DEBUG(std::cerr << "Reassociated: " << I/* << " Result BB: " 147680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner << I->getParent()*/); 1484fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1494fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Since we modified the RHS instruction, make sure that we recheck it. 150680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner ReassociateExpr(LHSI); 1516007cb6c4d923e2dee4a1133fb6d1bb00a37062dChris Lattner ReassociateExpr(I); 1524fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return true; 1534fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 1544fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 1554fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1564fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return Changed; 1574fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 1584fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 1594fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 160a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// NegateValue - Insert instructions before the instruction pointed to by BI, 161a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// that computes the negative version of the value specified. The negative 162a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// version of the value is returned, and BI is left pointing at the instruction 163a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// that should be processed next by the reassociation pass. 164a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner// 165e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattnerstatic Value *NegateValue(Value *V, BasicBlock::iterator &BI) { 166a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // We are trying to expose opportunity for reassociation. One of the things 167a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // that we want to do to achieve this is to push a negation as deep into an 168a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // expression chain as possible, to expose the add instructions. In practice, 169a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // this means that we turn this: 170a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // X = -(A+12+C+D) into X = -A + -12 + -C + -D = -12 + -A + -C + -D 171a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // so that later, a: Y = 12+X could get reassociated with the -12 to eliminate 172a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // the constants. We assume that instcombine will clean up the mess later if 173a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // we introduce tons of unneccesary negation instructions... 174a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 175a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner if (Instruction *I = dyn_cast<Instruction>(V)) 176a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner if (I->getOpcode() == Instruction::Add && I->use_size() == 1) { 177e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner Value *RHS = NegateValue(I->getOperand(1), BI); 178e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner Value *LHS = NegateValue(I->getOperand(0), BI); 179a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 180a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // We must actually insert a new add instruction here, because the neg 181a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // instructions do not dominate the old add instruction in general. By 182a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // adding it now, we are assured that the neg instructions we just 183a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // inserted dominate the instruction we are about to insert after them. 184a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 1852a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner return BinaryOperator::create(Instruction::Add, LHS, RHS, 1862a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner I->getName()+".neg", 1872a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner cast<Instruction>(RHS)->getNext()); 188a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner } 189a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 190a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Insert a 'neg' instruction that subtracts the value from zero to get the 191a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // negation. 192a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 193e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner return BI = BinaryOperator::createNeg(V, V->getName() + ".neg", BI); 194a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner} 195a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 196a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 1974fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattnerbool Reassociate::ReassociateBB(BasicBlock *BB) { 1984fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool Changed = false; 1994fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI) { 2004fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 201680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner DEBUG(std::cerr << "Processing: " << *BI); 202e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner if (BI->getOpcode() == Instruction::Sub && !BinaryOperator::isNeg(BI)) { 203e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // Convert a subtract into an add and a neg instruction... so that sub 204e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // instructions can be commuted with other add instructions... 205e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // 206e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // Calculate the negative value of Operand 1 of the sub instruction... 207e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // and set it as the RHS of the add instruction we just made... 208e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // 209e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner std::string Name = BI->getName(); 210e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner BI->setName(""); 211e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner Instruction *New = 212e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner BinaryOperator::create(Instruction::Add, BI->getOperand(0), 213e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner BI->getOperand(1), Name, BI); 214e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner 215e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // Everyone now refers to the add instruction... 216e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner BI->replaceAllUsesWith(New); 217e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner 218e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner // Put the new add in the place of the subtract... deleting the subtract 219e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner BB->getInstList().erase(BI); 220e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner 221e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner BI = New; 222e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner New->setOperand(1, NegateValue(New->getOperand(1), BI)); 223e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner 224e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner Changed = true; 225680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner DEBUG(std::cerr << "Negated: " << New /*<< " Result BB: " << BB*/); 226e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner } 227e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner 2284fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // If this instruction is a commutative binary operator, and the ranks of 2294fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // the two operands are sorted incorrectly, fix it now. 2304fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // 231e4b730441dab4aff9a69aeddbdea98990e7703c4Chris Lattner if (BI->isAssociative()) { 232e408e25132b8de8c757db1e3ddcd70432dfeb24dChris Lattner BinaryOperator *I = cast<BinaryOperator>(BI); 233a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner if (!I->use_empty()) { 234a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Make sure that we don't have a tree-shaped computation. If we do, 235a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // linearize it. Convert (A+B)+(C+D) into ((A+B)+C)+D 236a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 237a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Instruction *LHSI = dyn_cast<Instruction>(I->getOperand(0)); 238a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Instruction *RHSI = dyn_cast<Instruction>(I->getOperand(1)); 239a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner if (LHSI && (int)LHSI->getOpcode() == I->getOpcode() && 240a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner RHSI && (int)RHSI->getOpcode() == I->getOpcode() && 241a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner RHSI->use_size() == 1) { 242a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Insert a new temporary instruction... (A+B)+C 243a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner BinaryOperator *Tmp = BinaryOperator::create(I->getOpcode(), LHSI, 244a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner RHSI->getOperand(0), 2452a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner RHSI->getName()+".ra", 2462a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner BI); 2472a7c23ef9156a97f426a3fe8d1f5935b75d076d1Chris Lattner BI = Tmp; 248a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner I->setOperand(0, Tmp); 249a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner I->setOperand(1, RHSI->getOperand(1)); 250a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 251a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Process the temporary instruction for reassociation now. 252a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner I = Tmp; 253a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner ++NumLinear; 254a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Changed = true; 255680f0c283d6faf15113687a6eb68482d231d1d91Chris Lattner DEBUG(std::cerr << "Linearized: " << I/* << " Result BB: " << BB*/); 256a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner } 257a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner 258a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // Make sure that this expression is correctly reassociated with respect 259a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // to it's used values... 260a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner // 261a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner Changed |= ReassociateExpr(I); 262a36e6c8cd58c2876decd2d0402064ac349bbec71Chris Lattner } 2634fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 2644fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner } 2654fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2664fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return Changed; 2674fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 2684fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2694fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2707e70829632f82de15db187845666aaca6e04b792Chris Lattnerbool Reassociate::runOnFunction(Function &F) { 2714fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // Recalculate the rank map for F 2724fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner BuildRankMap(F); 2734fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2744fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner bool Changed = false; 2757e70829632f82de15db187845666aaca6e04b792Chris Lattner for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) 2767e70829632f82de15db187845666aaca6e04b792Chris Lattner Changed |= ReassociateBB(FI); 2774fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner 2784fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner // We are done with the rank map... 2794fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner RankMap.clear(); 2804d0a82da2daab7bd4eb3b3cd7ea28ba15d0db144Chris Lattner InstRankMap.clear(); 2814fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner return Changed; 2824fd56003ab29e3662c909bb10e47daa97ceb55abChris Lattner} 283