Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 1 | //===- Reassociate.cpp - Reassociate binary expressions -------------------===// |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 2 | // |
John Criswell | b576c94 | 2003-10-20 19:43:21 +0000 | [diff] [blame] | 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file was developed by the LLVM research group and is distributed under |
| 6 | // the University of Illinois Open Source License. See LICENSE.TXT for details. |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 7 | // |
John Criswell | b576c94 | 2003-10-20 19:43:21 +0000 | [diff] [blame] | 8 | //===----------------------------------------------------------------------===// |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 9 | // |
| 10 | // This pass reassociates commutative expressions in an order that is designed |
Chris Lattner | e96fda3 | 2003-05-02 19:26:34 +0000 | [diff] [blame] | 11 | // to promote better constant propagation, GCSE, LICM, PRE... |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 12 | // |
| 13 | // For example: 4 + (x + 5) -> x + (4 + 5) |
| 14 | // |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 15 | // In the implementation of this algorithm, constants are assigned rank = 0, |
| 16 | // function arguments are rank = 1, and other values are assigned ranks |
| 17 | // corresponding to the reverse post order traversal of current function |
| 18 | // (starting at 2), which effectively gives values in deep loops higher rank |
| 19 | // than values not in loops. |
| 20 | // |
| 21 | //===----------------------------------------------------------------------===// |
| 22 | |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 23 | #define DEBUG_TYPE "reassociate" |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 24 | #include "llvm/Transforms/Scalar.h" |
Chris Lattner | 0975ed5 | 2005-05-07 04:24:13 +0000 | [diff] [blame] | 25 | #include "llvm/Constants.h" |
Chris Lattner | ae74f55 | 2006-04-28 04:14:49 +0000 | [diff] [blame] | 26 | #include "llvm/DerivedTypes.h" |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 27 | #include "llvm/Function.h" |
Misha Brukman | d8e1eea | 2004-07-29 17:05:13 +0000 | [diff] [blame] | 28 | #include "llvm/Instructions.h" |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 29 | #include "llvm/Pass.h" |
Chris Lattner | c9fd097 | 2005-05-08 20:09:57 +0000 | [diff] [blame] | 30 | #include "llvm/Assembly/Writer.h" |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 31 | #include "llvm/Support/CFG.h" |
Reid Spencer | 9133fe2 | 2007-02-05 23:32:05 +0000 | [diff] [blame] | 32 | #include "llvm/Support/Compiler.h" |
Reid Spencer | 551ccae | 2004-09-01 22:55:40 +0000 | [diff] [blame] | 33 | #include "llvm/Support/Debug.h" |
| 34 | #include "llvm/ADT/PostOrderIterator.h" |
| 35 | #include "llvm/ADT/Statistic.h" |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 36 | #include <algorithm> |
Chris Lattner | d745602 | 2004-01-09 06:02:20 +0000 | [diff] [blame] | 37 | using namespace llvm; |
Brian Gaeke | d0fde30 | 2003-11-11 22:41:34 +0000 | [diff] [blame] | 38 | |
Chris Lattner | 0e5f499 | 2006-12-19 21:40:18 +0000 | [diff] [blame] | 39 | STATISTIC(NumLinear , "Number of insts linearized"); |
| 40 | STATISTIC(NumChanged, "Number of insts reassociated"); |
| 41 | STATISTIC(NumAnnihil, "Number of expr tree annihilated"); |
| 42 | STATISTIC(NumFactor , "Number of multiplies factored"); |
Chris Lattner | a92f696 | 2002-10-01 22:38:41 +0000 | [diff] [blame] | 43 | |
Chris Lattner | 0e5f499 | 2006-12-19 21:40:18 +0000 | [diff] [blame] | 44 | namespace { |
Reid Spencer | 9133fe2 | 2007-02-05 23:32:05 +0000 | [diff] [blame] | 45 | struct VISIBILITY_HIDDEN ValueEntry { |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 46 | unsigned Rank; |
| 47 | Value *Op; |
| 48 | ValueEntry(unsigned R, Value *O) : Rank(R), Op(O) {} |
| 49 | }; |
| 50 | inline bool operator<(const ValueEntry &LHS, const ValueEntry &RHS) { |
| 51 | return LHS.Rank > RHS.Rank; // Sort so that highest rank goes to start. |
| 52 | } |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 53 | } |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 54 | |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 55 | /// PrintOps - Print out the expression identified in the Ops list. |
| 56 | /// |
| 57 | static void PrintOps(Instruction *I, const std::vector<ValueEntry> &Ops) { |
| 58 | Module *M = I->getParent()->getParent()->getParent(); |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 59 | cerr << Instruction::getOpcodeName(I->getOpcode()) << " " |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 60 | << *Ops[0].Op->getType(); |
| 61 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 62 | WriteAsOperand(*cerr.stream() << " ", Ops[i].Op, false, M) |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 63 | << "," << Ops[i].Rank; |
| 64 | } |
| 65 | |
| 66 | namespace { |
Reid Spencer | 9133fe2 | 2007-02-05 23:32:05 +0000 | [diff] [blame] | 67 | class VISIBILITY_HIDDEN Reassociate : public FunctionPass { |
Chris Lattner | 0c0edf8 | 2002-07-25 06:17:51 +0000 | [diff] [blame] | 68 | std::map<BasicBlock*, unsigned> RankMap; |
Chris Lattner | fb5be09 | 2003-08-13 16:16:26 +0000 | [diff] [blame] | 69 | std::map<Value*, unsigned> ValueRankMap; |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 70 | bool MadeChange; |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 71 | public: |
Devang Patel | 1997473 | 2007-05-03 01:11:54 +0000 | [diff] [blame^] | 72 | static char ID; // Pass identifcation, replacement for typeid |
Devang Patel | 794fd75 | 2007-05-01 21:15:47 +0000 | [diff] [blame] | 73 | Reassociate() : FunctionPass((intptr_t)&ID) {} |
| 74 | |
Chris Lattner | 7e70829 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 75 | bool runOnFunction(Function &F); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 76 | |
| 77 | virtual void getAnalysisUsage(AnalysisUsage &AU) const { |
Chris Lattner | cb2610e | 2002-10-21 20:00:28 +0000 | [diff] [blame] | 78 | AU.setPreservesCFG(); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 79 | } |
| 80 | private: |
Chris Lattner | 7e70829 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 81 | void BuildRankMap(Function &F); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 82 | unsigned getRank(Value *V); |
Chris Lattner | 895b392 | 2006-03-14 07:11:11 +0000 | [diff] [blame] | 83 | void ReassociateExpression(BinaryOperator *I); |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 84 | void RewriteExprTree(BinaryOperator *I, std::vector<ValueEntry> &Ops, |
| 85 | unsigned Idx = 0); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 86 | Value *OptimizeExpression(BinaryOperator *I, std::vector<ValueEntry> &Ops); |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 87 | void LinearizeExprTree(BinaryOperator *I, std::vector<ValueEntry> &Ops); |
| 88 | void LinearizeExpr(BinaryOperator *I); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 89 | Value *RemoveFactorFromExpression(Value *V, Value *Factor); |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 90 | void ReassociateBB(BasicBlock *BB); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 91 | |
| 92 | void RemoveDeadBinaryOp(Value *V); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 93 | }; |
Chris Lattner | f629309 | 2002-07-23 18:06:35 +0000 | [diff] [blame] | 94 | |
Devang Patel | 1997473 | 2007-05-03 01:11:54 +0000 | [diff] [blame^] | 95 | char Reassociate::ID = 0; |
Chris Lattner | 7f8897f | 2006-08-27 22:42:52 +0000 | [diff] [blame] | 96 | RegisterPass<Reassociate> X("reassociate", "Reassociate expressions"); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 97 | } |
| 98 | |
Brian Gaeke | d0fde30 | 2003-11-11 22:41:34 +0000 | [diff] [blame] | 99 | // Public interface to the Reassociate pass |
Chris Lattner | d745602 | 2004-01-09 06:02:20 +0000 | [diff] [blame] | 100 | FunctionPass *llvm::createReassociatePass() { return new Reassociate(); } |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 101 | |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 102 | void Reassociate::RemoveDeadBinaryOp(Value *V) { |
Reid Spencer | e4d87aa | 2006-12-23 06:05:41 +0000 | [diff] [blame] | 103 | Instruction *Op = dyn_cast<Instruction>(V); |
| 104 | if (!Op || !isa<BinaryOperator>(Op) || !isa<CmpInst>(Op) || !Op->use_empty()) |
| 105 | return; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 106 | |
Reid Spencer | e4d87aa | 2006-12-23 06:05:41 +0000 | [diff] [blame] | 107 | Value *LHS = Op->getOperand(0), *RHS = Op->getOperand(1); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 108 | RemoveDeadBinaryOp(LHS); |
| 109 | RemoveDeadBinaryOp(RHS); |
| 110 | } |
| 111 | |
Chris Lattner | 9c72319 | 2005-05-08 20:57:04 +0000 | [diff] [blame] | 112 | |
| 113 | static bool isUnmovableInstruction(Instruction *I) { |
| 114 | if (I->getOpcode() == Instruction::PHI || |
| 115 | I->getOpcode() == Instruction::Alloca || |
| 116 | I->getOpcode() == Instruction::Load || |
| 117 | I->getOpcode() == Instruction::Malloc || |
| 118 | I->getOpcode() == Instruction::Invoke || |
| 119 | I->getOpcode() == Instruction::Call || |
Reid Spencer | 1628cec | 2006-10-26 06:15:43 +0000 | [diff] [blame] | 120 | I->getOpcode() == Instruction::UDiv || |
| 121 | I->getOpcode() == Instruction::SDiv || |
| 122 | I->getOpcode() == Instruction::FDiv || |
Reid Spencer | 0a783f7 | 2006-11-02 01:53:59 +0000 | [diff] [blame] | 123 | I->getOpcode() == Instruction::URem || |
| 124 | I->getOpcode() == Instruction::SRem || |
| 125 | I->getOpcode() == Instruction::FRem) |
Chris Lattner | 9c72319 | 2005-05-08 20:57:04 +0000 | [diff] [blame] | 126 | return true; |
| 127 | return false; |
| 128 | } |
| 129 | |
Chris Lattner | 7e70829 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 130 | void Reassociate::BuildRankMap(Function &F) { |
Chris Lattner | 6007cb6 | 2003-08-12 20:14:27 +0000 | [diff] [blame] | 131 | unsigned i = 2; |
Chris Lattner | fb5be09 | 2003-08-13 16:16:26 +0000 | [diff] [blame] | 132 | |
| 133 | // Assign distinct ranks to function arguments |
Chris Lattner | e4d5c44 | 2005-03-15 04:54:21 +0000 | [diff] [blame] | 134 | for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) |
Chris Lattner | fb5be09 | 2003-08-13 16:16:26 +0000 | [diff] [blame] | 135 | ValueRankMap[I] = ++i; |
| 136 | |
Chris Lattner | 7e70829 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 137 | ReversePostOrderTraversal<Function*> RPOT(&F); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 138 | for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(), |
Chris Lattner | 9c72319 | 2005-05-08 20:57:04 +0000 | [diff] [blame] | 139 | E = RPOT.end(); I != E; ++I) { |
| 140 | BasicBlock *BB = *I; |
| 141 | unsigned BBRank = RankMap[BB] = ++i << 16; |
| 142 | |
| 143 | // Walk the basic block, adding precomputed ranks for any instructions that |
| 144 | // we cannot move. This ensures that the ranks for these instructions are |
| 145 | // all different in the block. |
| 146 | for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) |
| 147 | if (isUnmovableInstruction(I)) |
| 148 | ValueRankMap[I] = ++BBRank; |
| 149 | } |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 150 | } |
| 151 | |
| 152 | unsigned Reassociate::getRank(Value *V) { |
Chris Lattner | fb5be09 | 2003-08-13 16:16:26 +0000 | [diff] [blame] | 153 | if (isa<Argument>(V)) return ValueRankMap[V]; // Function argument... |
| 154 | |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 155 | Instruction *I = dyn_cast<Instruction>(V); |
| 156 | if (I == 0) return 0; // Otherwise it's a global or constant, rank 0. |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 157 | |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 158 | unsigned &CachedRank = ValueRankMap[I]; |
| 159 | if (CachedRank) return CachedRank; // Rank already known? |
Jeff Cohen | 00b16889 | 2005-07-27 06:12:32 +0000 | [diff] [blame] | 160 | |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 161 | // If this is an expression, return the 1+MAX(rank(LHS), rank(RHS)) so that |
| 162 | // we can reassociate expressions for code motion! Since we do not recurse |
| 163 | // for PHI nodes, we cannot have infinite recursion here, because there |
| 164 | // cannot be loops in the value graph that do not go through PHI nodes. |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 165 | unsigned Rank = 0, MaxRank = RankMap[I->getParent()]; |
| 166 | for (unsigned i = 0, e = I->getNumOperands(); |
| 167 | i != e && Rank != MaxRank; ++i) |
| 168 | Rank = std::max(Rank, getRank(I->getOperand(i))); |
Jeff Cohen | 00b16889 | 2005-07-27 06:12:32 +0000 | [diff] [blame] | 169 | |
Chris Lattner | cc8a2b9 | 2005-05-08 00:08:33 +0000 | [diff] [blame] | 170 | // If this is a not or neg instruction, do not count it for rank. This |
| 171 | // assures us that X and ~X will have the same rank. |
Chris Lattner | 42a7551 | 2007-01-15 02:27:26 +0000 | [diff] [blame] | 172 | if (!I->getType()->isInteger() || |
Chris Lattner | cc8a2b9 | 2005-05-08 00:08:33 +0000 | [diff] [blame] | 173 | (!BinaryOperator::isNot(I) && !BinaryOperator::isNeg(I))) |
| 174 | ++Rank; |
| 175 | |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 176 | //DOUT << "Calculated Rank[" << V->getName() << "] = " |
| 177 | // << Rank << "\n"; |
Jeff Cohen | 00b16889 | 2005-07-27 06:12:32 +0000 | [diff] [blame] | 178 | |
Chris Lattner | cc8a2b9 | 2005-05-08 00:08:33 +0000 | [diff] [blame] | 179 | return CachedRank = Rank; |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 180 | } |
| 181 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 182 | /// isReassociableOp - Return true if V is an instruction of the specified |
| 183 | /// opcode and if it only has one use. |
| 184 | static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode) { |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 185 | if ((V->hasOneUse() || V->use_empty()) && isa<Instruction>(V) && |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 186 | cast<Instruction>(V)->getOpcode() == Opcode) |
| 187 | return cast<BinaryOperator>(V); |
| 188 | return 0; |
| 189 | } |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 190 | |
Chris Lattner | f33151a | 2005-05-08 21:28:52 +0000 | [diff] [blame] | 191 | /// LowerNegateToMultiply - Replace 0-X with X*-1. |
| 192 | /// |
| 193 | static Instruction *LowerNegateToMultiply(Instruction *Neg) { |
Reid Spencer | 24d6da5 | 2007-01-21 00:29:26 +0000 | [diff] [blame] | 194 | Constant *Cst = ConstantInt::getAllOnesValue(Neg->getType()); |
Chris Lattner | f33151a | 2005-05-08 21:28:52 +0000 | [diff] [blame] | 195 | |
Chris Lattner | 6934a04 | 2007-02-11 01:23:03 +0000 | [diff] [blame] | 196 | Instruction *Res = BinaryOperator::createMul(Neg->getOperand(1), Cst, "",Neg); |
| 197 | Res->takeName(Neg); |
Chris Lattner | f33151a | 2005-05-08 21:28:52 +0000 | [diff] [blame] | 198 | Neg->replaceAllUsesWith(Res); |
| 199 | Neg->eraseFromParent(); |
| 200 | return Res; |
| 201 | } |
| 202 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 203 | // Given an expression of the form '(A+B)+(D+C)', turn it into '(((A+B)+C)+D)'. |
| 204 | // Note that if D is also part of the expression tree that we recurse to |
| 205 | // linearize it as well. Besides that case, this does not recurse into A,B, or |
| 206 | // C. |
| 207 | void Reassociate::LinearizeExpr(BinaryOperator *I) { |
| 208 | BinaryOperator *LHS = cast<BinaryOperator>(I->getOperand(0)); |
| 209 | BinaryOperator *RHS = cast<BinaryOperator>(I->getOperand(1)); |
Jeff Cohen | 00b16889 | 2005-07-27 06:12:32 +0000 | [diff] [blame] | 210 | assert(isReassociableOp(LHS, I->getOpcode()) && |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 211 | isReassociableOp(RHS, I->getOpcode()) && |
| 212 | "Not an expression that needs linearization?"); |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 213 | |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 214 | DOUT << "Linear" << *LHS << *RHS << *I; |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 215 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 216 | // Move the RHS instruction to live immediately before I, avoiding breaking |
| 217 | // dominator properties. |
Chris Lattner | 4bc5f80 | 2005-08-08 19:11:57 +0000 | [diff] [blame] | 218 | RHS->moveBefore(I); |
Chris Lattner | e4b7304 | 2002-10-31 17:12:59 +0000 | [diff] [blame] | 219 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 220 | // Move operands around to do the linearization. |
| 221 | I->setOperand(1, RHS->getOperand(0)); |
| 222 | RHS->setOperand(0, LHS); |
| 223 | I->setOperand(0, RHS); |
Jeff Cohen | 00b16889 | 2005-07-27 06:12:32 +0000 | [diff] [blame] | 224 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 225 | ++NumLinear; |
| 226 | MadeChange = true; |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 227 | DOUT << "Linearized: " << *I; |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 228 | |
| 229 | // If D is part of this expression tree, tail recurse. |
| 230 | if (isReassociableOp(I->getOperand(1), I->getOpcode())) |
| 231 | LinearizeExpr(I); |
| 232 | } |
| 233 | |
| 234 | |
| 235 | /// LinearizeExprTree - Given an associative binary expression tree, traverse |
| 236 | /// all of the uses putting it into canonical form. This forces a left-linear |
| 237 | /// form of the the expression (((a+b)+c)+d), and collects information about the |
| 238 | /// rank of the non-tree operands. |
| 239 | /// |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 240 | /// NOTE: These intentionally destroys the expression tree operands (turning |
| 241 | /// them into undef values) to reduce #uses of the values. This means that the |
| 242 | /// caller MUST use something like RewriteExprTree to put the values back in. |
| 243 | /// |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 244 | void Reassociate::LinearizeExprTree(BinaryOperator *I, |
| 245 | std::vector<ValueEntry> &Ops) { |
| 246 | Value *LHS = I->getOperand(0), *RHS = I->getOperand(1); |
| 247 | unsigned Opcode = I->getOpcode(); |
| 248 | |
| 249 | // First step, linearize the expression if it is in ((A+B)+(C+D)) form. |
| 250 | BinaryOperator *LHSBO = isReassociableOp(LHS, Opcode); |
| 251 | BinaryOperator *RHSBO = isReassociableOp(RHS, Opcode); |
| 252 | |
Chris Lattner | f33151a | 2005-05-08 21:28:52 +0000 | [diff] [blame] | 253 | // If this is a multiply expression tree and it contains internal negations, |
| 254 | // transform them into multiplies by -1 so they can be reassociated. |
| 255 | if (I->getOpcode() == Instruction::Mul) { |
| 256 | if (!LHSBO && LHS->hasOneUse() && BinaryOperator::isNeg(LHS)) { |
| 257 | LHS = LowerNegateToMultiply(cast<Instruction>(LHS)); |
| 258 | LHSBO = isReassociableOp(LHS, Opcode); |
| 259 | } |
| 260 | if (!RHSBO && RHS->hasOneUse() && BinaryOperator::isNeg(RHS)) { |
| 261 | RHS = LowerNegateToMultiply(cast<Instruction>(RHS)); |
| 262 | RHSBO = isReassociableOp(RHS, Opcode); |
| 263 | } |
| 264 | } |
| 265 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 266 | if (!LHSBO) { |
| 267 | if (!RHSBO) { |
| 268 | // Neither the LHS or RHS as part of the tree, thus this is a leaf. As |
| 269 | // such, just remember these operands and their rank. |
| 270 | Ops.push_back(ValueEntry(getRank(LHS), LHS)); |
| 271 | Ops.push_back(ValueEntry(getRank(RHS), RHS)); |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 272 | |
| 273 | // Clear the leaves out. |
| 274 | I->setOperand(0, UndefValue::get(I->getType())); |
| 275 | I->setOperand(1, UndefValue::get(I->getType())); |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 276 | return; |
| 277 | } else { |
| 278 | // Turn X+(Y+Z) -> (Y+Z)+X |
| 279 | std::swap(LHSBO, RHSBO); |
| 280 | std::swap(LHS, RHS); |
| 281 | bool Success = !I->swapOperands(); |
| 282 | assert(Success && "swapOperands failed"); |
| 283 | MadeChange = true; |
| 284 | } |
| 285 | } else if (RHSBO) { |
| 286 | // Turn (A+B)+(C+D) -> (((A+B)+C)+D). This guarantees the the RHS is not |
| 287 | // part of the expression tree. |
| 288 | LinearizeExpr(I); |
| 289 | LHS = LHSBO = cast<BinaryOperator>(I->getOperand(0)); |
| 290 | RHS = I->getOperand(1); |
| 291 | RHSBO = 0; |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 292 | } |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 293 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 294 | // Okay, now we know that the LHS is a nested expression and that the RHS is |
| 295 | // not. Perform reassociation. |
| 296 | assert(!isReassociableOp(RHS, Opcode) && "LinearizeExpr failed!"); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 297 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 298 | // Move LHS right before I to make sure that the tree expression dominates all |
| 299 | // values. |
Chris Lattner | 4bc5f80 | 2005-08-08 19:11:57 +0000 | [diff] [blame] | 300 | LHSBO->moveBefore(I); |
Chris Lattner | e9608e3 | 2003-08-12 21:45:24 +0000 | [diff] [blame] | 301 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 302 | // Linearize the expression tree on the LHS. |
| 303 | LinearizeExprTree(LHSBO, Ops); |
Chris Lattner | e4b7304 | 2002-10-31 17:12:59 +0000 | [diff] [blame] | 304 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 305 | // Remember the RHS operand and its rank. |
| 306 | Ops.push_back(ValueEntry(getRank(RHS), RHS)); |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 307 | |
| 308 | // Clear the RHS leaf out. |
| 309 | I->setOperand(1, UndefValue::get(I->getType())); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 310 | } |
| 311 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 312 | // RewriteExprTree - Now that the operands for this expression tree are |
| 313 | // linearized and optimized, emit them in-order. This function is written to be |
| 314 | // tail recursive. |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 315 | void Reassociate::RewriteExprTree(BinaryOperator *I, |
| 316 | std::vector<ValueEntry> &Ops, |
| 317 | unsigned i) { |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 318 | if (i+2 == Ops.size()) { |
| 319 | if (I->getOperand(0) != Ops[i].Op || |
| 320 | I->getOperand(1) != Ops[i+1].Op) { |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 321 | Value *OldLHS = I->getOperand(0); |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 322 | DOUT << "RA: " << *I; |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 323 | I->setOperand(0, Ops[i].Op); |
| 324 | I->setOperand(1, Ops[i+1].Op); |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 325 | DOUT << "TO: " << *I; |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 326 | MadeChange = true; |
| 327 | ++NumChanged; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 328 | |
| 329 | // If we reassociated a tree to fewer operands (e.g. (1+a+2) -> (a+3) |
| 330 | // delete the extra, now dead, nodes. |
| 331 | RemoveDeadBinaryOp(OldLHS); |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 332 | } |
| 333 | return; |
| 334 | } |
| 335 | assert(i+2 < Ops.size() && "Ops index out of range!"); |
| 336 | |
| 337 | if (I->getOperand(1) != Ops[i].Op) { |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 338 | DOUT << "RA: " << *I; |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 339 | I->setOperand(1, Ops[i].Op); |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 340 | DOUT << "TO: " << *I; |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 341 | MadeChange = true; |
| 342 | ++NumChanged; |
| 343 | } |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 344 | |
| 345 | BinaryOperator *LHS = cast<BinaryOperator>(I->getOperand(0)); |
| 346 | assert(LHS->getOpcode() == I->getOpcode() && |
| 347 | "Improper expression tree!"); |
| 348 | |
| 349 | // Compactify the tree instructions together with each other to guarantee |
| 350 | // that the expression tree is dominated by all of Ops. |
| 351 | LHS->moveBefore(I); |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 352 | RewriteExprTree(LHS, Ops, i+1); |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 353 | } |
| 354 | |
| 355 | |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 356 | |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 357 | // NegateValue - Insert instructions before the instruction pointed to by BI, |
| 358 | // that computes the negative version of the value specified. The negative |
| 359 | // version of the value is returned, and BI is left pointing at the instruction |
| 360 | // that should be processed next by the reassociation pass. |
| 361 | // |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 362 | static Value *NegateValue(Value *V, Instruction *BI) { |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 363 | // We are trying to expose opportunity for reassociation. One of the things |
| 364 | // that we want to do to achieve this is to push a negation as deep into an |
| 365 | // expression chain as possible, to expose the add instructions. In practice, |
| 366 | // this means that we turn this: |
| 367 | // X = -(A+12+C+D) into X = -A + -12 + -C + -D = -12 + -A + -C + -D |
| 368 | // so that later, a: Y = 12+X could get reassociated with the -12 to eliminate |
| 369 | // the constants. We assume that instcombine will clean up the mess later if |
Misha Brukman | 5560c9d | 2003-08-18 14:43:39 +0000 | [diff] [blame] | 370 | // we introduce tons of unnecessary negation instructions... |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 371 | // |
| 372 | if (Instruction *I = dyn_cast<Instruction>(V)) |
Chris Lattner | fd05924 | 2003-10-15 16:48:29 +0000 | [diff] [blame] | 373 | if (I->getOpcode() == Instruction::Add && I->hasOneUse()) { |
Chris Lattner | 2cd85da | 2005-09-02 06:38:04 +0000 | [diff] [blame] | 374 | // Push the negates through the add. |
| 375 | I->setOperand(0, NegateValue(I->getOperand(0), BI)); |
| 376 | I->setOperand(1, NegateValue(I->getOperand(1), BI)); |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 377 | |
Chris Lattner | 2cd85da | 2005-09-02 06:38:04 +0000 | [diff] [blame] | 378 | // We must move the add instruction here, because the neg instructions do |
| 379 | // not dominate the old add instruction in general. By moving it, we are |
| 380 | // assured that the neg instructions we just inserted dominate the |
| 381 | // instruction we are about to insert after them. |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 382 | // |
Chris Lattner | 2cd85da | 2005-09-02 06:38:04 +0000 | [diff] [blame] | 383 | I->moveBefore(BI); |
| 384 | I->setName(I->getName()+".neg"); |
| 385 | return I; |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 386 | } |
| 387 | |
| 388 | // Insert a 'neg' instruction that subtracts the value from zero to get the |
| 389 | // negation. |
| 390 | // |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 391 | return BinaryOperator::createNeg(V, V->getName() + ".neg", BI); |
| 392 | } |
| 393 | |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 394 | /// BreakUpSubtract - If we have (X-Y), and if either X is an add, or if this is |
| 395 | /// only used by an add, transform this into (X+(0-Y)) to promote better |
| 396 | /// reassociation. |
| 397 | static Instruction *BreakUpSubtract(Instruction *Sub) { |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 398 | // Don't bother to break this up unless either the LHS is an associable add or |
| 399 | // if this is only used by one. |
| 400 | if (!isReassociableOp(Sub->getOperand(0), Instruction::Add) && |
| 401 | !isReassociableOp(Sub->getOperand(1), Instruction::Add) && |
| 402 | !(Sub->hasOneUse() &&isReassociableOp(Sub->use_back(), Instruction::Add))) |
| 403 | return 0; |
| 404 | |
| 405 | // Convert a subtract into an add and a neg instruction... so that sub |
| 406 | // instructions can be commuted with other add instructions... |
| 407 | // |
| 408 | // Calculate the negative value of Operand 1 of the sub instruction... |
| 409 | // and set it as the RHS of the add instruction we just made... |
| 410 | // |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 411 | Value *NegVal = NegateValue(Sub->getOperand(1), Sub); |
| 412 | Instruction *New = |
Chris Lattner | 6934a04 | 2007-02-11 01:23:03 +0000 | [diff] [blame] | 413 | BinaryOperator::createAdd(Sub->getOperand(0), NegVal, "", Sub); |
| 414 | New->takeName(Sub); |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 415 | |
| 416 | // Everyone now refers to the add instruction. |
| 417 | Sub->replaceAllUsesWith(New); |
| 418 | Sub->eraseFromParent(); |
Jeff Cohen | 00b16889 | 2005-07-27 06:12:32 +0000 | [diff] [blame] | 419 | |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 420 | DOUT << "Negated: " << *New; |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 421 | return New; |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 422 | } |
| 423 | |
Chris Lattner | 0975ed5 | 2005-05-07 04:24:13 +0000 | [diff] [blame] | 424 | /// ConvertShiftToMul - If this is a shift of a reassociable multiply or is used |
| 425 | /// by one, change this into a multiply by a constant to assist with further |
| 426 | /// reassociation. |
| 427 | static Instruction *ConvertShiftToMul(Instruction *Shl) { |
Chris Lattner | 22a66c4 | 2006-03-14 06:55:18 +0000 | [diff] [blame] | 428 | // If an operand of this shift is a reassociable multiply, or if the shift |
| 429 | // is used by a reassociable multiply or add, turn into a multiply. |
| 430 | if (isReassociableOp(Shl->getOperand(0), Instruction::Mul) || |
| 431 | (Shl->hasOneUse() && |
| 432 | (isReassociableOp(Shl->use_back(), Instruction::Mul) || |
| 433 | isReassociableOp(Shl->use_back(), Instruction::Add)))) { |
| 434 | Constant *MulCst = ConstantInt::get(Shl->getType(), 1); |
| 435 | MulCst = ConstantExpr::getShl(MulCst, cast<Constant>(Shl->getOperand(1))); |
| 436 | |
Chris Lattner | 22a66c4 | 2006-03-14 06:55:18 +0000 | [diff] [blame] | 437 | Instruction *Mul = BinaryOperator::createMul(Shl->getOperand(0), MulCst, |
Chris Lattner | 6934a04 | 2007-02-11 01:23:03 +0000 | [diff] [blame] | 438 | "", Shl); |
| 439 | Mul->takeName(Shl); |
Chris Lattner | 22a66c4 | 2006-03-14 06:55:18 +0000 | [diff] [blame] | 440 | Shl->replaceAllUsesWith(Mul); |
| 441 | Shl->eraseFromParent(); |
| 442 | return Mul; |
| 443 | } |
| 444 | return 0; |
Chris Lattner | 0975ed5 | 2005-05-07 04:24:13 +0000 | [diff] [blame] | 445 | } |
| 446 | |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 447 | // Scan backwards and forwards among values with the same rank as element i to |
| 448 | // see if X exists. If X does not exist, return i. |
| 449 | static unsigned FindInOperandList(std::vector<ValueEntry> &Ops, unsigned i, |
| 450 | Value *X) { |
| 451 | unsigned XRank = Ops[i].Rank; |
| 452 | unsigned e = Ops.size(); |
| 453 | for (unsigned j = i+1; j != e && Ops[j].Rank == XRank; ++j) |
| 454 | if (Ops[j].Op == X) |
| 455 | return j; |
| 456 | // Scan backwards |
| 457 | for (unsigned j = i-1; j != ~0U && Ops[j].Rank == XRank; --j) |
| 458 | if (Ops[j].Op == X) |
| 459 | return j; |
| 460 | return i; |
| 461 | } |
| 462 | |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 463 | /// EmitAddTreeOfValues - Emit a tree of add instructions, summing Ops together |
| 464 | /// and returning the result. Insert the tree before I. |
| 465 | static Value *EmitAddTreeOfValues(Instruction *I, std::vector<Value*> &Ops) { |
| 466 | if (Ops.size() == 1) return Ops.back(); |
| 467 | |
| 468 | Value *V1 = Ops.back(); |
| 469 | Ops.pop_back(); |
| 470 | Value *V2 = EmitAddTreeOfValues(I, Ops); |
| 471 | return BinaryOperator::createAdd(V2, V1, "tmp", I); |
| 472 | } |
| 473 | |
| 474 | /// RemoveFactorFromExpression - If V is an expression tree that is a |
| 475 | /// multiplication sequence, and if this sequence contains a multiply by Factor, |
| 476 | /// remove Factor from the tree and return the new tree. |
| 477 | Value *Reassociate::RemoveFactorFromExpression(Value *V, Value *Factor) { |
| 478 | BinaryOperator *BO = isReassociableOp(V, Instruction::Mul); |
| 479 | if (!BO) return 0; |
| 480 | |
| 481 | std::vector<ValueEntry> Factors; |
| 482 | LinearizeExprTree(BO, Factors); |
| 483 | |
| 484 | bool FoundFactor = false; |
| 485 | for (unsigned i = 0, e = Factors.size(); i != e; ++i) |
| 486 | if (Factors[i].Op == Factor) { |
| 487 | FoundFactor = true; |
| 488 | Factors.erase(Factors.begin()+i); |
| 489 | break; |
| 490 | } |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 491 | if (!FoundFactor) { |
| 492 | // Make sure to restore the operands to the expression tree. |
| 493 | RewriteExprTree(BO, Factors); |
| 494 | return 0; |
| 495 | } |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 496 | |
| 497 | if (Factors.size() == 1) return Factors[0].Op; |
| 498 | |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 499 | RewriteExprTree(BO, Factors); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 500 | return BO; |
| 501 | } |
| 502 | |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 503 | /// FindSingleUseMultiplyFactors - If V is a single-use multiply, recursively |
| 504 | /// add its operands as factors, otherwise add V to the list of factors. |
| 505 | static void FindSingleUseMultiplyFactors(Value *V, |
| 506 | std::vector<Value*> &Factors) { |
| 507 | BinaryOperator *BO; |
| 508 | if ((!V->hasOneUse() && !V->use_empty()) || |
| 509 | !(BO = dyn_cast<BinaryOperator>(V)) || |
| 510 | BO->getOpcode() != Instruction::Mul) { |
| 511 | Factors.push_back(V); |
| 512 | return; |
| 513 | } |
| 514 | |
| 515 | // Otherwise, add the LHS and RHS to the list of factors. |
| 516 | FindSingleUseMultiplyFactors(BO->getOperand(1), Factors); |
| 517 | FindSingleUseMultiplyFactors(BO->getOperand(0), Factors); |
| 518 | } |
| 519 | |
| 520 | |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 521 | |
| 522 | Value *Reassociate::OptimizeExpression(BinaryOperator *I, |
| 523 | std::vector<ValueEntry> &Ops) { |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 524 | // Now that we have the linearized expression tree, try to optimize it. |
| 525 | // Start by folding any constants that we found. |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 526 | bool IterateOptimization = false; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 527 | if (Ops.size() == 1) return Ops[0].Op; |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 528 | |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 529 | unsigned Opcode = I->getOpcode(); |
| 530 | |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 531 | if (Constant *V1 = dyn_cast<Constant>(Ops[Ops.size()-2].Op)) |
| 532 | if (Constant *V2 = dyn_cast<Constant>(Ops.back().Op)) { |
| 533 | Ops.pop_back(); |
| 534 | Ops.back().Op = ConstantExpr::get(Opcode, V1, V2); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 535 | return OptimizeExpression(I, Ops); |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 536 | } |
| 537 | |
| 538 | // Check for destructive annihilation due to a constant being used. |
Zhou Sheng | 6b6b6ef | 2007-01-11 12:24:14 +0000 | [diff] [blame] | 539 | if (ConstantInt *CstVal = dyn_cast<ConstantInt>(Ops.back().Op)) |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 540 | switch (Opcode) { |
| 541 | default: break; |
| 542 | case Instruction::And: |
Reid Spencer | cae5754 | 2007-03-02 00:28:52 +0000 | [diff] [blame] | 543 | if (CstVal->isZero()) { // ... & 0 -> 0 |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 544 | ++NumAnnihil; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 545 | return CstVal; |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 546 | } else if (CstVal->isAllOnesValue()) { // ... & -1 -> ... |
| 547 | Ops.pop_back(); |
| 548 | } |
| 549 | break; |
| 550 | case Instruction::Mul: |
Reid Spencer | cae5754 | 2007-03-02 00:28:52 +0000 | [diff] [blame] | 551 | if (CstVal->isZero()) { // ... * 0 -> 0 |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 552 | ++NumAnnihil; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 553 | return CstVal; |
Reid Spencer | cae5754 | 2007-03-02 00:28:52 +0000 | [diff] [blame] | 554 | } else if (cast<ConstantInt>(CstVal)->isOne()) { |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 555 | Ops.pop_back(); // ... * 1 -> ... |
| 556 | } |
| 557 | break; |
| 558 | case Instruction::Or: |
| 559 | if (CstVal->isAllOnesValue()) { // ... | -1 -> -1 |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 560 | ++NumAnnihil; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 561 | return CstVal; |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 562 | } |
| 563 | // FALLTHROUGH! |
| 564 | case Instruction::Add: |
| 565 | case Instruction::Xor: |
Reid Spencer | cae5754 | 2007-03-02 00:28:52 +0000 | [diff] [blame] | 566 | if (CstVal->isZero()) // ... [|^+] 0 -> ... |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 567 | Ops.pop_back(); |
| 568 | break; |
| 569 | } |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 570 | if (Ops.size() == 1) return Ops[0].Op; |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 571 | |
| 572 | // Handle destructive annihilation do to identities between elements in the |
| 573 | // argument list here. |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 574 | switch (Opcode) { |
| 575 | default: break; |
| 576 | case Instruction::And: |
| 577 | case Instruction::Or: |
| 578 | case Instruction::Xor: |
| 579 | // Scan the operand lists looking for X and ~X pairs, along with X,X pairs. |
| 580 | // If we find any, we can simplify the expression. X&~X == 0, X|~X == -1. |
| 581 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
| 582 | // First, check for X and ~X in the operand list. |
Chris Lattner | 368a3aa | 2005-09-02 05:23:22 +0000 | [diff] [blame] | 583 | assert(i < Ops.size()); |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 584 | if (BinaryOperator::isNot(Ops[i].Op)) { // Cannot occur for ^. |
| 585 | Value *X = BinaryOperator::getNotArgument(Ops[i].Op); |
| 586 | unsigned FoundX = FindInOperandList(Ops, i, X); |
| 587 | if (FoundX != i) { |
| 588 | if (Opcode == Instruction::And) { // ...&X&~X = 0 |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 589 | ++NumAnnihil; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 590 | return Constant::getNullValue(X->getType()); |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 591 | } else if (Opcode == Instruction::Or) { // ...|X|~X = -1 |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 592 | ++NumAnnihil; |
Zhou Sheng | 6b6b6ef | 2007-01-11 12:24:14 +0000 | [diff] [blame] | 593 | return ConstantInt::getAllOnesValue(X->getType()); |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 594 | } |
| 595 | } |
| 596 | } |
| 597 | |
| 598 | // Next, check for duplicate pairs of values, which we assume are next to |
| 599 | // each other, due to our sorting criteria. |
Chris Lattner | 368a3aa | 2005-09-02 05:23:22 +0000 | [diff] [blame] | 600 | assert(i < Ops.size()); |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 601 | if (i+1 != Ops.size() && Ops[i+1].Op == Ops[i].Op) { |
| 602 | if (Opcode == Instruction::And || Opcode == Instruction::Or) { |
| 603 | // Drop duplicate values. |
| 604 | Ops.erase(Ops.begin()+i); |
| 605 | --i; --e; |
| 606 | IterateOptimization = true; |
| 607 | ++NumAnnihil; |
| 608 | } else { |
| 609 | assert(Opcode == Instruction::Xor); |
Chris Lattner | ac83b03 | 2005-08-24 17:55:32 +0000 | [diff] [blame] | 610 | if (e == 2) { |
Chris Lattner | ac83b03 | 2005-08-24 17:55:32 +0000 | [diff] [blame] | 611 | ++NumAnnihil; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 612 | return Constant::getNullValue(Ops[0].Op->getType()); |
Chris Lattner | ac83b03 | 2005-08-24 17:55:32 +0000 | [diff] [blame] | 613 | } |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 614 | // ... X^X -> ... |
| 615 | Ops.erase(Ops.begin()+i, Ops.begin()+i+2); |
Chris Lattner | ac83b03 | 2005-08-24 17:55:32 +0000 | [diff] [blame] | 616 | i -= 1; e -= 2; |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 617 | IterateOptimization = true; |
| 618 | ++NumAnnihil; |
| 619 | } |
| 620 | } |
| 621 | } |
| 622 | break; |
| 623 | |
| 624 | case Instruction::Add: |
| 625 | // Scan the operand lists looking for X and -X pairs. If we find any, we |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 626 | // can simplify the expression. X+-X == 0. |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 627 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
Chris Lattner | 368a3aa | 2005-09-02 05:23:22 +0000 | [diff] [blame] | 628 | assert(i < Ops.size()); |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 629 | // Check for X and -X in the operand list. |
| 630 | if (BinaryOperator::isNeg(Ops[i].Op)) { |
| 631 | Value *X = BinaryOperator::getNegArgument(Ops[i].Op); |
| 632 | unsigned FoundX = FindInOperandList(Ops, i, X); |
| 633 | if (FoundX != i) { |
| 634 | // Remove X and -X from the operand list. |
| 635 | if (Ops.size() == 2) { |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 636 | ++NumAnnihil; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 637 | return Constant::getNullValue(X->getType()); |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 638 | } else { |
| 639 | Ops.erase(Ops.begin()+i); |
Chris Lattner | 368a3aa | 2005-09-02 05:23:22 +0000 | [diff] [blame] | 640 | if (i < FoundX) |
| 641 | --FoundX; |
| 642 | else |
| 643 | --i; // Need to back up an extra one. |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 644 | Ops.erase(Ops.begin()+FoundX); |
| 645 | IterateOptimization = true; |
| 646 | ++NumAnnihil; |
Chris Lattner | 368a3aa | 2005-09-02 05:23:22 +0000 | [diff] [blame] | 647 | --i; // Revisit element. |
| 648 | e -= 2; // Removed two elements. |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 649 | } |
| 650 | } |
| 651 | } |
| 652 | } |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 653 | |
| 654 | |
| 655 | // Scan the operand list, checking to see if there are any common factors |
| 656 | // between operands. Consider something like A*A+A*B*C+D. We would like to |
| 657 | // reassociate this to A*(A+B*C)+D, which reduces the number of multiplies. |
| 658 | // To efficiently find this, we count the number of times a factor occurs |
| 659 | // for any ADD operands that are MULs. |
| 660 | std::map<Value*, unsigned> FactorOccurrences; |
| 661 | unsigned MaxOcc = 0; |
| 662 | Value *MaxOccVal = 0; |
Reid Spencer | 24d6da5 | 2007-01-21 00:29:26 +0000 | [diff] [blame] | 663 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
| 664 | if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Ops[i].Op)) { |
| 665 | if (BOp->getOpcode() == Instruction::Mul && BOp->use_empty()) { |
| 666 | // Compute all of the factors of this added value. |
| 667 | std::vector<Value*> Factors; |
| 668 | FindSingleUseMultiplyFactors(BOp, Factors); |
| 669 | assert(Factors.size() > 1 && "Bad linearize!"); |
| 670 | |
| 671 | // Add one to FactorOccurrences for each unique factor in this op. |
| 672 | if (Factors.size() == 2) { |
| 673 | unsigned Occ = ++FactorOccurrences[Factors[0]]; |
| 674 | if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[0]; } |
| 675 | if (Factors[0] != Factors[1]) { // Don't double count A*A. |
| 676 | Occ = ++FactorOccurrences[Factors[1]]; |
| 677 | if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[1]; } |
| 678 | } |
| 679 | } else { |
| 680 | std::set<Value*> Duplicates; |
| 681 | for (unsigned i = 0, e = Factors.size(); i != e; ++i) { |
| 682 | if (Duplicates.insert(Factors[i]).second) { |
| 683 | unsigned Occ = ++FactorOccurrences[Factors[i]]; |
| 684 | if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[i]; } |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 685 | } |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 686 | } |
| 687 | } |
Reid Spencer | 24d6da5 | 2007-01-21 00:29:26 +0000 | [diff] [blame] | 688 | } |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 689 | } |
| 690 | } |
| 691 | |
| 692 | // If any factor occurred more than one time, we can pull it out. |
| 693 | if (MaxOcc > 1) { |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 694 | DOUT << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << "\n"; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 695 | |
| 696 | // Create a new instruction that uses the MaxOccVal twice. If we don't do |
| 697 | // this, we could otherwise run into situations where removing a factor |
| 698 | // from an expression will drop a use of maxocc, and this can cause |
| 699 | // RemoveFactorFromExpression on successive values to behave differently. |
| 700 | Instruction *DummyInst = BinaryOperator::createAdd(MaxOccVal, MaxOccVal); |
| 701 | std::vector<Value*> NewMulOps; |
| 702 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
| 703 | if (Value *V = RemoveFactorFromExpression(Ops[i].Op, MaxOccVal)) { |
| 704 | NewMulOps.push_back(V); |
| 705 | Ops.erase(Ops.begin()+i); |
| 706 | --i; --e; |
| 707 | } |
| 708 | } |
| 709 | |
| 710 | // No need for extra uses anymore. |
| 711 | delete DummyInst; |
| 712 | |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 713 | unsigned NumAddedValues = NewMulOps.size(); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 714 | Value *V = EmitAddTreeOfValues(I, NewMulOps); |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 715 | Value *V2 = BinaryOperator::createMul(V, MaxOccVal, "tmp", I); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 716 | |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 717 | // Now that we have inserted V and its sole use, optimize it. This allows |
| 718 | // us to handle cases that require multiple factoring steps, such as this: |
| 719 | // A*A*B + A*A*C --> A*(A*B+A*C) --> A*(A*(B+C)) |
| 720 | if (NumAddedValues > 1) |
| 721 | ReassociateExpression(cast<BinaryOperator>(V)); |
| 722 | |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 723 | ++NumFactor; |
| 724 | |
| 725 | if (Ops.size() == 0) |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 726 | return V2; |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 727 | |
| 728 | // Add the new value to the list of things being added. |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 729 | Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2)); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 730 | |
| 731 | // Rewrite the tree so that there is now a use of V. |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 732 | RewriteExprTree(I, Ops); |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 733 | return OptimizeExpression(I, Ops); |
| 734 | } |
Chris Lattner | 109d34d | 2005-05-08 18:59:37 +0000 | [diff] [blame] | 735 | break; |
| 736 | //case Instruction::Mul: |
| 737 | } |
| 738 | |
Jeff Cohen | 00b16889 | 2005-07-27 06:12:32 +0000 | [diff] [blame] | 739 | if (IterateOptimization) |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 740 | return OptimizeExpression(I, Ops); |
| 741 | return 0; |
Chris Lattner | 4690010 | 2005-05-08 00:19:31 +0000 | [diff] [blame] | 742 | } |
| 743 | |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 744 | |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 745 | /// ReassociateBB - Inspect all of the instructions in this basic block, |
| 746 | /// reassociating them as we go. |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 747 | void Reassociate::ReassociateBB(BasicBlock *BB) { |
Chris Lattner | e5022fe | 2006-03-04 09:31:13 +0000 | [diff] [blame] | 748 | for (BasicBlock::iterator BBI = BB->begin(); BBI != BB->end(); ) { |
| 749 | Instruction *BI = BBI++; |
Chris Lattner | 641f02f | 2005-05-10 03:39:25 +0000 | [diff] [blame] | 750 | if (BI->getOpcode() == Instruction::Shl && |
| 751 | isa<ConstantInt>(BI->getOperand(1))) |
| 752 | if (Instruction *NI = ConvertShiftToMul(BI)) { |
| 753 | MadeChange = true; |
| 754 | BI = NI; |
| 755 | } |
| 756 | |
Chris Lattner | 6f15685 | 2005-05-08 21:33:47 +0000 | [diff] [blame] | 757 | // Reject cases where it is pointless to do this. |
Reid Spencer | e4d87aa | 2006-12-23 06:05:41 +0000 | [diff] [blame] | 758 | if (!isa<BinaryOperator>(BI) || BI->getType()->isFloatingPoint() || |
Reid Spencer | 9d6565a | 2007-02-15 02:26:10 +0000 | [diff] [blame] | 759 | isa<VectorType>(BI->getType())) |
Chris Lattner | 6f15685 | 2005-05-08 21:33:47 +0000 | [diff] [blame] | 760 | continue; // Floating point ops are not associative. |
| 761 | |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 762 | // If this is a subtract instruction which is not already in negate form, |
| 763 | // see if we can convert it to X+-Y. |
Chris Lattner | f33151a | 2005-05-08 21:28:52 +0000 | [diff] [blame] | 764 | if (BI->getOpcode() == Instruction::Sub) { |
| 765 | if (!BinaryOperator::isNeg(BI)) { |
| 766 | if (Instruction *NI = BreakUpSubtract(BI)) { |
| 767 | MadeChange = true; |
| 768 | BI = NI; |
| 769 | } |
| 770 | } else { |
| 771 | // Otherwise, this is a negation. See if the operand is a multiply tree |
| 772 | // and if this is not an inner node of a multiply tree. |
| 773 | if (isReassociableOp(BI->getOperand(1), Instruction::Mul) && |
| 774 | (!BI->hasOneUse() || |
| 775 | !isReassociableOp(BI->use_back(), Instruction::Mul))) { |
| 776 | BI = LowerNegateToMultiply(BI); |
| 777 | MadeChange = true; |
| 778 | } |
Chris Lattner | 08b4392 | 2005-05-07 04:08:02 +0000 | [diff] [blame] | 779 | } |
Chris Lattner | f33151a | 2005-05-08 21:28:52 +0000 | [diff] [blame] | 780 | } |
Chris Lattner | e4b7304 | 2002-10-31 17:12:59 +0000 | [diff] [blame] | 781 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 782 | // If this instruction is a commutative binary operator, process it. |
| 783 | if (!BI->isAssociative()) continue; |
| 784 | BinaryOperator *I = cast<BinaryOperator>(BI); |
Jeff Cohen | 00b16889 | 2005-07-27 06:12:32 +0000 | [diff] [blame] | 785 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 786 | // If this is an interior node of a reassociable tree, ignore it until we |
| 787 | // get to the root of the tree, to avoid N^2 analysis. |
| 788 | if (I->hasOneUse() && isReassociableOp(I->use_back(), I->getOpcode())) |
| 789 | continue; |
Chris Lattner | a36e6c8 | 2002-05-16 04:37:07 +0000 | [diff] [blame] | 790 | |
Chris Lattner | 7b4ad94 | 2005-09-02 07:07:58 +0000 | [diff] [blame] | 791 | // If this is an add tree that is used by a sub instruction, ignore it |
| 792 | // until we process the subtract. |
| 793 | if (I->hasOneUse() && I->getOpcode() == Instruction::Add && |
| 794 | cast<Instruction>(I->use_back())->getOpcode() == Instruction::Sub) |
| 795 | continue; |
| 796 | |
Chris Lattner | 895b392 | 2006-03-14 07:11:11 +0000 | [diff] [blame] | 797 | ReassociateExpression(I); |
| 798 | } |
| 799 | } |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 800 | |
Chris Lattner | 895b392 | 2006-03-14 07:11:11 +0000 | [diff] [blame] | 801 | void Reassociate::ReassociateExpression(BinaryOperator *I) { |
| 802 | |
| 803 | // First, walk the expression tree, linearizing the tree, collecting |
| 804 | std::vector<ValueEntry> Ops; |
| 805 | LinearizeExprTree(I, Ops); |
| 806 | |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 807 | DOUT << "RAIn:\t"; DEBUG(PrintOps(I, Ops)); DOUT << "\n"; |
Chris Lattner | 895b392 | 2006-03-14 07:11:11 +0000 | [diff] [blame] | 808 | |
| 809 | // Now that we have linearized the tree to a list and have gathered all of |
| 810 | // the operands and their ranks, sort the operands by their rank. Use a |
| 811 | // stable_sort so that values with equal ranks will have their relative |
| 812 | // positions maintained (and so the compiler is deterministic). Note that |
| 813 | // this sorts so that the highest ranking values end up at the beginning of |
| 814 | // the vector. |
| 815 | std::stable_sort(Ops.begin(), Ops.end()); |
| 816 | |
| 817 | // OptimizeExpression - Now that we have the expression tree in a convenient |
| 818 | // sorted form, optimize it globally if possible. |
| 819 | if (Value *V = OptimizeExpression(I, Ops)) { |
| 820 | // This expression tree simplified to something that isn't a tree, |
| 821 | // eliminate it. |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 822 | DOUT << "Reassoc to scalar: " << *V << "\n"; |
Chris Lattner | 895b392 | 2006-03-14 07:11:11 +0000 | [diff] [blame] | 823 | I->replaceAllUsesWith(V); |
| 824 | RemoveDeadBinaryOp(I); |
| 825 | return; |
| 826 | } |
| 827 | |
| 828 | // We want to sink immediates as deeply as possible except in the case where |
| 829 | // this is a multiply tree used only by an add, and the immediate is a -1. |
| 830 | // In this case we reassociate to put the negation on the outside so that we |
| 831 | // can fold the negation into the add: (-X)*Y + Z -> Z-X*Y |
| 832 | if (I->getOpcode() == Instruction::Mul && I->hasOneUse() && |
| 833 | cast<Instruction>(I->use_back())->getOpcode() == Instruction::Add && |
| 834 | isa<ConstantInt>(Ops.back().Op) && |
| 835 | cast<ConstantInt>(Ops.back().Op)->isAllOnesValue()) { |
| 836 | Ops.insert(Ops.begin(), Ops.back()); |
| 837 | Ops.pop_back(); |
| 838 | } |
| 839 | |
Bill Wendling | 832171c | 2006-12-07 20:04:42 +0000 | [diff] [blame] | 840 | DOUT << "RAOut:\t"; DEBUG(PrintOps(I, Ops)); DOUT << "\n"; |
Chris Lattner | 895b392 | 2006-03-14 07:11:11 +0000 | [diff] [blame] | 841 | |
| 842 | if (Ops.size() == 1) { |
| 843 | // This expression tree simplified to something that isn't a tree, |
| 844 | // eliminate it. |
| 845 | I->replaceAllUsesWith(Ops[0].Op); |
| 846 | RemoveDeadBinaryOp(I); |
| 847 | } else { |
| 848 | // Now that we ordered and optimized the expressions, splat them back into |
| 849 | // the expression tree, removing any unneeded nodes. |
Chris Lattner | e9efecb | 2006-03-14 16:04:29 +0000 | [diff] [blame] | 850 | RewriteExprTree(I, Ops); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 851 | } |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 852 | } |
| 853 | |
| 854 | |
Chris Lattner | 7e70829 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 855 | bool Reassociate::runOnFunction(Function &F) { |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 856 | // Recalculate the rank map for F |
| 857 | BuildRankMap(F); |
| 858 | |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 859 | MadeChange = false; |
Chris Lattner | 7e70829 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 860 | for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 861 | ReassociateBB(FI); |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 862 | |
| 863 | // We are done with the rank map... |
| 864 | RankMap.clear(); |
Chris Lattner | fb5be09 | 2003-08-13 16:16:26 +0000 | [diff] [blame] | 865 | ValueRankMap.clear(); |
Chris Lattner | c0649ac | 2005-05-07 21:59:39 +0000 | [diff] [blame] | 866 | return MadeChange; |
Chris Lattner | 4fd5600 | 2002-05-08 22:19:27 +0000 | [diff] [blame] | 867 | } |
Brian Gaeke | d0fde30 | 2003-11-11 22:41:34 +0000 | [diff] [blame] | 868 | |