Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 1 | //===- LoopStrengthReduce.cpp - Strength Reduce GEPs in Loops -------------===// |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 2 | // |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
Chris Lattner | 4ee451d | 2007-12-29 20:36:04 +0000 | [diff] [blame] | 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 7 | // |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This pass performs a strength reduction on array references inside loops that |
| 11 | // have as one or more of their components the loop induction variable. This is |
| 12 | // accomplished by creating a new Value to hold the initial value of the array |
| 13 | // access for the first iteration, and then creating a new GEP instruction in |
| 14 | // the loop to increment the value by the appropriate amount. |
| 15 | // |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 16 | //===----------------------------------------------------------------------===// |
| 17 | |
Chris Lattner | be3e521 | 2005-08-03 23:30:08 +0000 | [diff] [blame] | 18 | #define DEBUG_TYPE "loop-reduce" |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 19 | #include "llvm/Transforms/Scalar.h" |
| 20 | #include "llvm/Constants.h" |
| 21 | #include "llvm/Instructions.h" |
Dan Gohman | e5b01be | 2007-05-04 14:59:09 +0000 | [diff] [blame] | 22 | #include "llvm/IntrinsicInst.h" |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 23 | #include "llvm/Type.h" |
Jeff Cohen | 2f3c9b7 | 2005-03-04 04:04:26 +0000 | [diff] [blame] | 24 | #include "llvm/DerivedTypes.h" |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 25 | #include "llvm/Analysis/Dominators.h" |
| 26 | #include "llvm/Analysis/LoopInfo.h" |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 27 | #include "llvm/Analysis/LoopPass.h" |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 28 | #include "llvm/Analysis/ScalarEvolutionExpander.h" |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 29 | #include "llvm/Support/CFG.h" |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 30 | #include "llvm/Support/GetElementPtrTypeIterator.h" |
Chris Lattner | e0391be | 2005-08-12 22:06:11 +0000 | [diff] [blame] | 31 | #include "llvm/Transforms/Utils/BasicBlockUtils.h" |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 32 | #include "llvm/Transforms/Utils/Local.h" |
Jeff Cohen | 2f3c9b7 | 2005-03-04 04:04:26 +0000 | [diff] [blame] | 33 | #include "llvm/Target/TargetData.h" |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 34 | #include "llvm/ADT/SmallPtrSet.h" |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 35 | #include "llvm/ADT/Statistic.h" |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 36 | #include "llvm/Support/Debug.h" |
Chris Lattner | a4f0b3a | 2006-08-27 12:54:02 +0000 | [diff] [blame] | 37 | #include "llvm/Support/Compiler.h" |
Evan Cheng | d277f2c | 2006-03-13 23:14:23 +0000 | [diff] [blame] | 38 | #include "llvm/Target/TargetLowering.h" |
Jeff Cohen | cfb1d42 | 2005-07-30 18:22:27 +0000 | [diff] [blame] | 39 | #include <algorithm> |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 40 | #include <set> |
| 41 | using namespace llvm; |
| 42 | |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 43 | STATISTIC(NumReduced , "Number of GEPs strength reduced"); |
| 44 | STATISTIC(NumInserted, "Number of PHIs inserted"); |
| 45 | STATISTIC(NumVariable, "Number of PHIs with variable strides"); |
| 46 | STATISTIC(NumEliminated , "Number of strides eliminated"); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 47 | |
Chris Lattner | 0e5f499 | 2006-12-19 21:40:18 +0000 | [diff] [blame] | 48 | namespace { |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 49 | |
Jeff Cohen | c01a530 | 2007-03-20 20:43:18 +0000 | [diff] [blame] | 50 | struct BasedUser; |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 51 | |
Chris Lattner | ec3fb63 | 2005-08-03 22:21:05 +0000 | [diff] [blame] | 52 | /// IVStrideUse - Keep track of one use of a strided induction variable, where |
| 53 | /// the stride is stored externally. The Offset member keeps track of the |
Dan Gohman | 9330c3a | 2007-10-29 19:32:39 +0000 | [diff] [blame] | 54 | /// offset from the IV, User is the actual user of the operand, and |
| 55 | /// 'OperandValToReplace' is the operand of the User that is the use. |
Reid Spencer | 9133fe2 | 2007-02-05 23:32:05 +0000 | [diff] [blame] | 56 | struct VISIBILITY_HIDDEN IVStrideUse { |
Chris Lattner | ec3fb63 | 2005-08-03 22:21:05 +0000 | [diff] [blame] | 57 | SCEVHandle Offset; |
| 58 | Instruction *User; |
| 59 | Value *OperandValToReplace; |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 60 | |
| 61 | // isUseOfPostIncrementedValue - True if this should use the |
| 62 | // post-incremented version of this IV, not the preincremented version. |
| 63 | // This can only be set in special cases, such as the terminating setcc |
Chris Lattner | c6bae65 | 2005-09-12 06:04:47 +0000 | [diff] [blame] | 64 | // instruction for a loop or uses dominated by the loop. |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 65 | bool isUseOfPostIncrementedValue; |
Chris Lattner | ec3fb63 | 2005-08-03 22:21:05 +0000 | [diff] [blame] | 66 | |
| 67 | IVStrideUse(const SCEVHandle &Offs, Instruction *U, Value *O) |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 68 | : Offset(Offs), User(U), OperandValToReplace(O), |
| 69 | isUseOfPostIncrementedValue(false) {} |
Chris Lattner | ec3fb63 | 2005-08-03 22:21:05 +0000 | [diff] [blame] | 70 | }; |
| 71 | |
| 72 | /// IVUsersOfOneStride - This structure keeps track of all instructions that |
| 73 | /// have an operand that is based on the trip count multiplied by some stride. |
| 74 | /// The stride for all of these users is common and kept external to this |
| 75 | /// structure. |
Reid Spencer | 9133fe2 | 2007-02-05 23:32:05 +0000 | [diff] [blame] | 76 | struct VISIBILITY_HIDDEN IVUsersOfOneStride { |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 77 | /// Users - Keep track of all of the users of this stride as well as the |
Chris Lattner | ec3fb63 | 2005-08-03 22:21:05 +0000 | [diff] [blame] | 78 | /// initial value and the operand that uses the IV. |
| 79 | std::vector<IVStrideUse> Users; |
| 80 | |
| 81 | void addUser(const SCEVHandle &Offset,Instruction *User, Value *Operand) { |
| 82 | Users.push_back(IVStrideUse(Offset, User, Operand)); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 83 | } |
| 84 | }; |
| 85 | |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 86 | /// IVInfo - This structure keeps track of one IV expression inserted during |
Evan Cheng | 2149577 | 2006-03-18 08:03:12 +0000 | [diff] [blame] | 87 | /// StrengthReduceStridedIVUsers. It contains the stride, the common base, as |
| 88 | /// well as the PHI node and increment value created for rewrite. |
Reid Spencer | 9133fe2 | 2007-02-05 23:32:05 +0000 | [diff] [blame] | 89 | struct VISIBILITY_HIDDEN IVExpr { |
Evan Cheng | 2149577 | 2006-03-18 08:03:12 +0000 | [diff] [blame] | 90 | SCEVHandle Stride; |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 91 | SCEVHandle Base; |
| 92 | PHINode *PHI; |
| 93 | Value *IncV; |
| 94 | |
Evan Cheng | 2149577 | 2006-03-18 08:03:12 +0000 | [diff] [blame] | 95 | IVExpr(const SCEVHandle &stride, const SCEVHandle &base, PHINode *phi, |
| 96 | Value *incv) |
| 97 | : Stride(stride), Base(base), PHI(phi), IncV(incv) {} |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 98 | }; |
| 99 | |
| 100 | /// IVsOfOneStride - This structure keeps track of all IV expression inserted |
| 101 | /// during StrengthReduceStridedIVUsers for a particular stride of the IV. |
Reid Spencer | 9133fe2 | 2007-02-05 23:32:05 +0000 | [diff] [blame] | 102 | struct VISIBILITY_HIDDEN IVsOfOneStride { |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 103 | std::vector<IVExpr> IVs; |
| 104 | |
Evan Cheng | 2149577 | 2006-03-18 08:03:12 +0000 | [diff] [blame] | 105 | void addIV(const SCEVHandle &Stride, const SCEVHandle &Base, PHINode *PHI, |
| 106 | Value *IncV) { |
| 107 | IVs.push_back(IVExpr(Stride, Base, PHI, IncV)); |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 108 | } |
| 109 | }; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 110 | |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 111 | class VISIBILITY_HIDDEN LoopStrengthReduce : public LoopPass { |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 112 | LoopInfo *LI; |
Devang Patel | b7d9dfc | 2007-06-07 21:42:15 +0000 | [diff] [blame] | 113 | DominatorTree *DT; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 114 | ScalarEvolution *SE; |
| 115 | const TargetData *TD; |
| 116 | const Type *UIntPtrTy; |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 117 | bool Changed; |
Chris Lattner | 7e608bb | 2005-08-02 02:52:02 +0000 | [diff] [blame] | 118 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 119 | /// IVUsesByStride - Keep track of all uses of induction variables that we |
| 120 | /// are interested in. The key of the map is the stride of the access. |
Chris Lattner | 50fad70 | 2005-08-10 00:45:21 +0000 | [diff] [blame] | 121 | std::map<SCEVHandle, IVUsersOfOneStride> IVUsesByStride; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 122 | |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 123 | /// IVsByStride - Keep track of all IVs that have been inserted for a |
| 124 | /// particular stride. |
| 125 | std::map<SCEVHandle, IVsOfOneStride> IVsByStride; |
| 126 | |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 127 | /// StrideOrder - An ordering of the keys in IVUsesByStride that is stable: |
| 128 | /// We use this to iterate over the IVUsesByStride collection without being |
| 129 | /// dependent on random ordering of pointers in the process. |
Evan Cheng | 8392772 | 2007-10-30 22:27:26 +0000 | [diff] [blame] | 130 | SmallVector<SCEVHandle, 16> StrideOrder; |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 131 | |
Chris Lattner | 49f72e6 | 2005-08-04 01:19:13 +0000 | [diff] [blame] | 132 | /// CastedValues - As we need to cast values to uintptr_t, this keeps track |
| 133 | /// of the casted version of each value. This is accessed by |
| 134 | /// getCastedVersionOf. |
Evan Cheng | 8392772 | 2007-10-30 22:27:26 +0000 | [diff] [blame] | 135 | DenseMap<Value*, Value*> CastedPointers; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 136 | |
| 137 | /// DeadInsts - Keep track of instructions we may have made dead, so that |
| 138 | /// we can remove them after we are done working. |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 139 | SmallPtrSet<Instruction*,16> DeadInsts; |
Evan Cheng | d277f2c | 2006-03-13 23:14:23 +0000 | [diff] [blame] | 140 | |
| 141 | /// TLI - Keep a pointer of a TargetLowering to consult for determining |
| 142 | /// transformation profitability. |
| 143 | const TargetLowering *TLI; |
| 144 | |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 145 | public: |
Devang Patel | 1997473 | 2007-05-03 01:11:54 +0000 | [diff] [blame] | 146 | static char ID; // Pass ID, replacement for typeid |
Dan Gohman | c2bbfc1 | 2007-08-01 15:32:29 +0000 | [diff] [blame] | 147 | explicit LoopStrengthReduce(const TargetLowering *tli = NULL) : |
Devang Patel | 794fd75 | 2007-05-01 21:15:47 +0000 | [diff] [blame] | 148 | LoopPass((intptr_t)&ID), TLI(tli) { |
Jeff Cohen | 2f3c9b7 | 2005-03-04 04:04:26 +0000 | [diff] [blame] | 149 | } |
| 150 | |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 151 | bool runOnLoop(Loop *L, LPPassManager &LPM); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 152 | |
| 153 | virtual void getAnalysisUsage(AnalysisUsage &AU) const { |
Chris Lattner | aa96ae7 | 2005-08-17 06:35:16 +0000 | [diff] [blame] | 154 | // We split critical edges, so we change the CFG. However, we do update |
| 155 | // many analyses if they are around. |
| 156 | AU.addPreservedID(LoopSimplifyID); |
| 157 | AU.addPreserved<LoopInfo>(); |
Chris Lattner | aa96ae7 | 2005-08-17 06:35:16 +0000 | [diff] [blame] | 158 | AU.addPreserved<DominanceFrontier>(); |
| 159 | AU.addPreserved<DominatorTree>(); |
| 160 | |
Jeff Cohen | f465db6 | 2005-02-27 19:37:07 +0000 | [diff] [blame] | 161 | AU.addRequiredID(LoopSimplifyID); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 162 | AU.addRequired<LoopInfo>(); |
Devang Patel | b7d9dfc | 2007-06-07 21:42:15 +0000 | [diff] [blame] | 163 | AU.addRequired<DominatorTree>(); |
Jeff Cohen | 2f3c9b7 | 2005-03-04 04:04:26 +0000 | [diff] [blame] | 164 | AU.addRequired<TargetData>(); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 165 | AU.addRequired<ScalarEvolution>(); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 166 | } |
Chris Lattner | 49f72e6 | 2005-08-04 01:19:13 +0000 | [diff] [blame] | 167 | |
| 168 | /// getCastedVersionOf - Return the specified value casted to uintptr_t. |
| 169 | /// |
Reid Spencer | 3ba68b9 | 2006-12-13 08:06:42 +0000 | [diff] [blame] | 170 | Value *getCastedVersionOf(Instruction::CastOps opcode, Value *V); |
Chris Lattner | 49f72e6 | 2005-08-04 01:19:13 +0000 | [diff] [blame] | 171 | private: |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 172 | bool AddUsersIfInteresting(Instruction *I, Loop *L, |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 173 | SmallPtrSet<Instruction*,16> &Processed); |
Dan Gohman | 8480bc5 | 2007-10-29 19:31:25 +0000 | [diff] [blame] | 174 | SCEVHandle GetExpressionSCEV(Instruction *E); |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 175 | ICmpInst *ChangeCompareStride(Loop *L, ICmpInst *Cond, |
| 176 | IVStrideUse* &CondUse, |
| 177 | const SCEVHandle* &CondStride); |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 178 | void OptimizeIndvars(Loop *L); |
Chris Lattner | aed01d1 | 2007-04-03 05:11:24 +0000 | [diff] [blame] | 179 | bool FindIVForUser(ICmpInst *Cond, IVStrideUse *&CondUse, |
| 180 | const SCEVHandle *&CondStride); |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 181 | bool RequiresTypeConversion(const Type *Ty, const Type *NewTy); |
Evan Cheng | 2bd122c | 2007-10-26 01:56:11 +0000 | [diff] [blame] | 182 | unsigned CheckForIVReuse(bool, bool, const SCEVHandle&, |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 183 | IVExpr&, const Type*, |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 184 | const std::vector<BasedUser>& UsersToProcess); |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 185 | bool ValidStride(bool, int64_t, |
| 186 | const std::vector<BasedUser>& UsersToProcess); |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 187 | SCEVHandle CollectIVUsers(const SCEVHandle &Stride, |
| 188 | IVUsersOfOneStride &Uses, |
| 189 | Loop *L, |
| 190 | bool &AllUsesAreAddresses, |
| 191 | std::vector<BasedUser> &UsersToProcess); |
Chris Lattner | 50fad70 | 2005-08-10 00:45:21 +0000 | [diff] [blame] | 192 | void StrengthReduceStridedIVUsers(const SCEVHandle &Stride, |
| 193 | IVUsersOfOneStride &Uses, |
Chris Lattner | ec3fb63 | 2005-08-03 22:21:05 +0000 | [diff] [blame] | 194 | Loop *L, bool isOnlyStride); |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 195 | void DeleteTriviallyDeadInstructions(SmallPtrSet<Instruction*,16> &Insts); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 196 | }; |
Devang Patel | 1997473 | 2007-05-03 01:11:54 +0000 | [diff] [blame] | 197 | char LoopStrengthReduce::ID = 0; |
Chris Lattner | 7f8897f | 2006-08-27 22:42:52 +0000 | [diff] [blame] | 198 | RegisterPass<LoopStrengthReduce> X("loop-reduce", "Loop Strength Reduction"); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 199 | } |
| 200 | |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 201 | LoopPass *llvm::createLoopStrengthReducePass(const TargetLowering *TLI) { |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 202 | return new LoopStrengthReduce(TLI); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 203 | } |
| 204 | |
Reid Spencer | 4da4912 | 2006-12-12 05:05:00 +0000 | [diff] [blame] | 205 | /// getCastedVersionOf - Return the specified value casted to uintptr_t. This |
| 206 | /// assumes that the Value* V is of integer or pointer type only. |
Chris Lattner | 49f72e6 | 2005-08-04 01:19:13 +0000 | [diff] [blame] | 207 | /// |
Reid Spencer | 3ba68b9 | 2006-12-13 08:06:42 +0000 | [diff] [blame] | 208 | Value *LoopStrengthReduce::getCastedVersionOf(Instruction::CastOps opcode, |
| 209 | Value *V) { |
Chris Lattner | 49f72e6 | 2005-08-04 01:19:13 +0000 | [diff] [blame] | 210 | if (V->getType() == UIntPtrTy) return V; |
| 211 | if (Constant *CB = dyn_cast<Constant>(V)) |
Reid Spencer | 3ba68b9 | 2006-12-13 08:06:42 +0000 | [diff] [blame] | 212 | return ConstantExpr::getCast(opcode, CB, UIntPtrTy); |
Chris Lattner | 49f72e6 | 2005-08-04 01:19:13 +0000 | [diff] [blame] | 213 | |
| 214 | Value *&New = CastedPointers[V]; |
| 215 | if (New) return New; |
| 216 | |
Reid Spencer | 3ba68b9 | 2006-12-13 08:06:42 +0000 | [diff] [blame] | 217 | New = SCEVExpander::InsertCastOfTo(opcode, V, UIntPtrTy); |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 218 | DeadInsts.insert(cast<Instruction>(New)); |
| 219 | return New; |
Chris Lattner | 49f72e6 | 2005-08-04 01:19:13 +0000 | [diff] [blame] | 220 | } |
| 221 | |
| 222 | |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 223 | /// DeleteTriviallyDeadInstructions - If any of the instructions is the |
| 224 | /// specified set are trivially dead, delete them and see if this makes any of |
| 225 | /// their operands subsequently dead. |
| 226 | void LoopStrengthReduce:: |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 227 | DeleteTriviallyDeadInstructions(SmallPtrSet<Instruction*,16> &Insts) { |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 228 | while (!Insts.empty()) { |
| 229 | Instruction *I = *Insts.begin(); |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 230 | Insts.erase(I); |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 231 | |
| 232 | if (PHINode *PN = dyn_cast<PHINode>(I)) { |
| 233 | // If all incoming values to the Phi are the same, we can replace the Phi |
| 234 | // with that value. |
| 235 | if (Value *PNV = PN->hasConstantValue()) { |
| 236 | if (Instruction *U = dyn_cast<Instruction>(PNV)) |
| 237 | Insts.insert(U); |
| 238 | PN->replaceAllUsesWith(PNV); |
| 239 | SE->deleteValueFromRecords(PN); |
| 240 | PN->eraseFromParent(); |
| 241 | Changed = true; |
| 242 | continue; |
| 243 | } |
| 244 | } |
| 245 | |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 246 | if (isInstructionTriviallyDead(I)) { |
Jeff Cohen | 0456e4a | 2005-03-01 03:46:11 +0000 | [diff] [blame] | 247 | for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) |
| 248 | if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i))) |
| 249 | Insts.insert(U); |
Dan Gohman | 5cec4db | 2007-06-19 14:28:31 +0000 | [diff] [blame] | 250 | SE->deleteValueFromRecords(I); |
Chris Lattner | 52d83e6 | 2005-08-03 21:36:09 +0000 | [diff] [blame] | 251 | I->eraseFromParent(); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 252 | Changed = true; |
| 253 | } |
| 254 | } |
| 255 | } |
| 256 | |
Jeff Cohen | f465db6 | 2005-02-27 19:37:07 +0000 | [diff] [blame] | 257 | |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 258 | /// GetExpressionSCEV - Compute and return the SCEV for the specified |
| 259 | /// instruction. |
Dan Gohman | 8480bc5 | 2007-10-29 19:31:25 +0000 | [diff] [blame] | 260 | SCEVHandle LoopStrengthReduce::GetExpressionSCEV(Instruction *Exp) { |
Dale Johannesen | da91f49 | 2007-03-26 03:01:27 +0000 | [diff] [blame] | 261 | // Pointer to pointer bitcast instructions return the same value as their |
| 262 | // operand. |
| 263 | if (BitCastInst *BCI = dyn_cast<BitCastInst>(Exp)) { |
| 264 | if (SE->hasSCEV(BCI) || !isa<Instruction>(BCI->getOperand(0))) |
| 265 | return SE->getSCEV(BCI); |
Dan Gohman | 8480bc5 | 2007-10-29 19:31:25 +0000 | [diff] [blame] | 266 | SCEVHandle R = GetExpressionSCEV(cast<Instruction>(BCI->getOperand(0))); |
Dale Johannesen | da91f49 | 2007-03-26 03:01:27 +0000 | [diff] [blame] | 267 | SE->setSCEV(BCI, R); |
| 268 | return R; |
| 269 | } |
| 270 | |
Chris Lattner | 87265ab | 2005-08-09 23:39:36 +0000 | [diff] [blame] | 271 | // Scalar Evolutions doesn't know how to compute SCEV's for GEP instructions. |
| 272 | // If this is a GEP that SE doesn't know about, compute it now and insert it. |
| 273 | // If this is not a GEP, or if we have already done this computation, just let |
| 274 | // SE figure it out. |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 275 | GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Exp); |
Chris Lattner | 87265ab | 2005-08-09 23:39:36 +0000 | [diff] [blame] | 276 | if (!GEP || SE->hasSCEV(GEP)) |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 277 | return SE->getSCEV(Exp); |
| 278 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 279 | // Analyze all of the subscripts of this getelementptr instruction, looking |
Dan Gohman | 8480bc5 | 2007-10-29 19:31:25 +0000 | [diff] [blame] | 280 | // for uses that are determined by the trip count of the loop. First, skip |
| 281 | // all operands the are not dependent on the IV. |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 282 | |
| 283 | // Build up the base expression. Insert an LLVM cast of the pointer to |
| 284 | // uintptr_t first. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 285 | SCEVHandle GEPVal = SE->getUnknown( |
Reid Spencer | 3ba68b9 | 2006-12-13 08:06:42 +0000 | [diff] [blame] | 286 | getCastedVersionOf(Instruction::PtrToInt, GEP->getOperand(0))); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 287 | |
| 288 | gep_type_iterator GTI = gep_type_begin(GEP); |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 289 | |
| 290 | for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 291 | // If this is a use of a recurrence that we can analyze, and it comes before |
| 292 | // Op does in the GEP operand list, we will handle this when we process this |
| 293 | // operand. |
| 294 | if (const StructType *STy = dyn_cast<StructType>(*GTI)) { |
| 295 | const StructLayout *SL = TD->getStructLayout(STy); |
Reid Spencer | b83eb64 | 2006-10-20 07:07:24 +0000 | [diff] [blame] | 296 | unsigned Idx = cast<ConstantInt>(GEP->getOperand(i))->getZExtValue(); |
Chris Lattner | b1919e2 | 2007-02-10 19:55:17 +0000 | [diff] [blame] | 297 | uint64_t Offset = SL->getElementOffset(Idx); |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 298 | GEPVal = SE->getAddExpr(GEPVal, |
| 299 | SE->getIntegerSCEV(Offset, UIntPtrTy)); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 300 | } else { |
Reid Spencer | 3ba68b9 | 2006-12-13 08:06:42 +0000 | [diff] [blame] | 301 | unsigned GEPOpiBits = |
| 302 | GEP->getOperand(i)->getType()->getPrimitiveSizeInBits(); |
| 303 | unsigned IntPtrBits = UIntPtrTy->getPrimitiveSizeInBits(); |
| 304 | Instruction::CastOps opcode = (GEPOpiBits < IntPtrBits ? |
| 305 | Instruction::SExt : (GEPOpiBits > IntPtrBits ? Instruction::Trunc : |
| 306 | Instruction::BitCast)); |
| 307 | Value *OpVal = getCastedVersionOf(opcode, GEP->getOperand(i)); |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 308 | SCEVHandle Idx = SE->getSCEV(OpVal); |
| 309 | |
Dale Johannesen | a7ac2bd | 2007-10-01 23:08:35 +0000 | [diff] [blame] | 310 | uint64_t TypeSize = TD->getABITypeSize(GTI.getIndexedType()); |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 311 | if (TypeSize != 1) |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 312 | Idx = SE->getMulExpr(Idx, |
| 313 | SE->getConstant(ConstantInt::get(UIntPtrTy, |
| 314 | TypeSize))); |
| 315 | GEPVal = SE->getAddExpr(GEPVal, Idx); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 316 | } |
| 317 | } |
| 318 | |
Chris Lattner | 87265ab | 2005-08-09 23:39:36 +0000 | [diff] [blame] | 319 | SE->setSCEV(GEP, GEPVal); |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 320 | return GEPVal; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 321 | } |
| 322 | |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 323 | /// getSCEVStartAndStride - Compute the start and stride of this expression, |
| 324 | /// returning false if the expression is not a start/stride pair, or true if it |
| 325 | /// is. The stride must be a loop invariant expression, but the start may be |
| 326 | /// a mix of loop invariant and loop variant expressions. |
| 327 | static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 328 | SCEVHandle &Start, SCEVHandle &Stride, |
| 329 | ScalarEvolution *SE) { |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 330 | SCEVHandle TheAddRec = Start; // Initialize to zero. |
| 331 | |
| 332 | // If the outer level is an AddExpr, the operands are all start values except |
| 333 | // for a nested AddRecExpr. |
| 334 | if (SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(SH)) { |
| 335 | for (unsigned i = 0, e = AE->getNumOperands(); i != e; ++i) |
| 336 | if (SCEVAddRecExpr *AddRec = |
| 337 | dyn_cast<SCEVAddRecExpr>(AE->getOperand(i))) { |
| 338 | if (AddRec->getLoop() == L) |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 339 | TheAddRec = SE->getAddExpr(AddRec, TheAddRec); |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 340 | else |
| 341 | return false; // Nested IV of some sort? |
| 342 | } else { |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 343 | Start = SE->getAddExpr(Start, AE->getOperand(i)); |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 344 | } |
| 345 | |
Reid Spencer | 3ed469c | 2006-11-02 20:25:50 +0000 | [diff] [blame] | 346 | } else if (isa<SCEVAddRecExpr>(SH)) { |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 347 | TheAddRec = SH; |
| 348 | } else { |
| 349 | return false; // not analyzable. |
| 350 | } |
| 351 | |
| 352 | SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(TheAddRec); |
| 353 | if (!AddRec || AddRec->getLoop() != L) return false; |
| 354 | |
| 355 | // FIXME: Generalize to non-affine IV's. |
| 356 | if (!AddRec->isAffine()) return false; |
| 357 | |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 358 | Start = SE->getAddExpr(Start, AddRec->getOperand(0)); |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 359 | |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 360 | if (!isa<SCEVConstant>(AddRec->getOperand(1))) |
Bill Wendling | b742703 | 2006-11-26 09:46:52 +0000 | [diff] [blame] | 361 | DOUT << "[" << L->getHeader()->getName() |
| 362 | << "] Variable stride: " << *AddRec << "\n"; |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 363 | |
Chris Lattner | 50fad70 | 2005-08-10 00:45:21 +0000 | [diff] [blame] | 364 | Stride = AddRec->getOperand(1); |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 365 | return true; |
| 366 | } |
| 367 | |
Chris Lattner | 0ae33eb | 2005-10-03 01:04:44 +0000 | [diff] [blame] | 368 | /// IVUseShouldUsePostIncValue - We have discovered a "User" of an IV expression |
| 369 | /// and now we need to decide whether the user should use the preinc or post-inc |
| 370 | /// value. If this user should use the post-inc version of the IV, return true. |
| 371 | /// |
| 372 | /// Choosing wrong here can break dominance properties (if we choose to use the |
| 373 | /// post-inc value when we cannot) or it can end up adding extra live-ranges to |
| 374 | /// the loop, resulting in reg-reg copies (if we use the pre-inc value when we |
| 375 | /// should use the post-inc value). |
| 376 | static bool IVUseShouldUsePostIncValue(Instruction *User, Instruction *IV, |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 377 | Loop *L, DominatorTree *DT, Pass *P, |
| 378 | SmallPtrSet<Instruction*,16> &DeadInsts){ |
Chris Lattner | 0ae33eb | 2005-10-03 01:04:44 +0000 | [diff] [blame] | 379 | // If the user is in the loop, use the preinc value. |
| 380 | if (L->contains(User->getParent())) return false; |
| 381 | |
Chris Lattner | 5e8ca66 | 2005-10-03 02:50:05 +0000 | [diff] [blame] | 382 | BasicBlock *LatchBlock = L->getLoopLatch(); |
| 383 | |
| 384 | // Ok, the user is outside of the loop. If it is dominated by the latch |
| 385 | // block, use the post-inc value. |
Devang Patel | b7d9dfc | 2007-06-07 21:42:15 +0000 | [diff] [blame] | 386 | if (DT->dominates(LatchBlock, User->getParent())) |
Chris Lattner | 5e8ca66 | 2005-10-03 02:50:05 +0000 | [diff] [blame] | 387 | return true; |
| 388 | |
| 389 | // There is one case we have to be careful of: PHI nodes. These little guys |
| 390 | // can live in blocks that do not dominate the latch block, but (since their |
| 391 | // uses occur in the predecessor block, not the block the PHI lives in) should |
| 392 | // still use the post-inc value. Check for this case now. |
| 393 | PHINode *PN = dyn_cast<PHINode>(User); |
| 394 | if (!PN) return false; // not a phi, not dominated by latch block. |
| 395 | |
| 396 | // Look at all of the uses of IV by the PHI node. If any use corresponds to |
| 397 | // a block that is not dominated by the latch block, give up and use the |
| 398 | // preincremented value. |
| 399 | unsigned NumUses = 0; |
| 400 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) |
| 401 | if (PN->getIncomingValue(i) == IV) { |
| 402 | ++NumUses; |
Devang Patel | b7d9dfc | 2007-06-07 21:42:15 +0000 | [diff] [blame] | 403 | if (!DT->dominates(LatchBlock, PN->getIncomingBlock(i))) |
Chris Lattner | 5e8ca66 | 2005-10-03 02:50:05 +0000 | [diff] [blame] | 404 | return false; |
| 405 | } |
| 406 | |
| 407 | // Okay, all uses of IV by PN are in predecessor blocks that really are |
| 408 | // dominated by the latch block. Split the critical edges and use the |
| 409 | // post-incremented value. |
| 410 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) |
| 411 | if (PN->getIncomingValue(i) == IV) { |
Evan Cheng | 8392772 | 2007-10-30 22:27:26 +0000 | [diff] [blame] | 412 | SplitCriticalEdge(PN->getIncomingBlock(i), PN->getParent(), P, false); |
Chris Lattner | 1b9c8e7 | 2006-10-28 00:59:20 +0000 | [diff] [blame] | 413 | // Splitting the critical edge can reduce the number of entries in this |
| 414 | // PHI. |
| 415 | e = PN->getNumIncomingValues(); |
Chris Lattner | 5e8ca66 | 2005-10-03 02:50:05 +0000 | [diff] [blame] | 416 | if (--NumUses == 0) break; |
| 417 | } |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 418 | |
| 419 | // PHI node might have become a constant value after SplitCriticalEdge. |
| 420 | DeadInsts.insert(User); |
Chris Lattner | 5e8ca66 | 2005-10-03 02:50:05 +0000 | [diff] [blame] | 421 | |
| 422 | return true; |
Chris Lattner | 0ae33eb | 2005-10-03 01:04:44 +0000 | [diff] [blame] | 423 | } |
| 424 | |
| 425 | |
| 426 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 427 | /// AddUsersIfInteresting - Inspect the specified instruction. If it is a |
| 428 | /// reducible SCEV, recursively add its users to the IVUsesByStride set and |
| 429 | /// return true. Otherwise, return false. |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 430 | bool LoopStrengthReduce::AddUsersIfInteresting(Instruction *I, Loop *L, |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 431 | SmallPtrSet<Instruction*,16> &Processed) { |
Chris Lattner | 42a7551 | 2007-01-15 02:27:26 +0000 | [diff] [blame] | 432 | if (!I->getType()->isInteger() && !isa<PointerType>(I->getType())) |
Chris Lattner | 63ad796 | 2005-10-21 05:45:41 +0000 | [diff] [blame] | 433 | return false; // Void and FP expressions cannot be reduced. |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 434 | if (!Processed.insert(I)) |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 435 | return true; // Instruction already handled. |
| 436 | |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 437 | // Get the symbolic expression for this instruction. |
Dan Gohman | 8480bc5 | 2007-10-29 19:31:25 +0000 | [diff] [blame] | 438 | SCEVHandle ISE = GetExpressionSCEV(I); |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 439 | if (isa<SCEVCouldNotCompute>(ISE)) return false; |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 440 | |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 441 | // Get the start and stride for this expression. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 442 | SCEVHandle Start = SE->getIntegerSCEV(0, ISE->getType()); |
Chris Lattner | 50fad70 | 2005-08-10 00:45:21 +0000 | [diff] [blame] | 443 | SCEVHandle Stride = Start; |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 444 | if (!getSCEVStartAndStride(ISE, L, Start, Stride, SE)) |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 445 | return false; // Non-reducible symbolic expression, bail out. |
Devang Patel | 4fe2658 | 2007-03-09 21:19:53 +0000 | [diff] [blame] | 446 | |
Devang Patel | 2a5fa18 | 2007-04-23 22:42:03 +0000 | [diff] [blame] | 447 | std::vector<Instruction *> IUsers; |
| 448 | // Collect all I uses now because IVUseShouldUsePostIncValue may |
| 449 | // invalidate use_iterator. |
| 450 | for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; ++UI) |
| 451 | IUsers.push_back(cast<Instruction>(*UI)); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 452 | |
Devang Patel | 2a5fa18 | 2007-04-23 22:42:03 +0000 | [diff] [blame] | 453 | for (unsigned iused_index = 0, iused_size = IUsers.size(); |
| 454 | iused_index != iused_size; ++iused_index) { |
| 455 | |
| 456 | Instruction *User = IUsers[iused_index]; |
Devang Patel | 4fe2658 | 2007-03-09 21:19:53 +0000 | [diff] [blame] | 457 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 458 | // Do not infinitely recurse on PHI nodes. |
Chris Lattner | 396b2ba | 2005-09-13 02:09:55 +0000 | [diff] [blame] | 459 | if (isa<PHINode>(User) && Processed.count(User)) |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 460 | continue; |
| 461 | |
| 462 | // If this is an instruction defined in a nested loop, or outside this loop, |
Chris Lattner | f918659 | 2005-08-04 00:14:11 +0000 | [diff] [blame] | 463 | // don't recurse into it. |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 464 | bool AddUserToIVUsers = false; |
Chris Lattner | f918659 | 2005-08-04 00:14:11 +0000 | [diff] [blame] | 465 | if (LI->getLoopFor(User->getParent()) != L) { |
Bill Wendling | b742703 | 2006-11-26 09:46:52 +0000 | [diff] [blame] | 466 | DOUT << "FOUND USER in other loop: " << *User |
| 467 | << " OF SCEV: " << *ISE << "\n"; |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 468 | AddUserToIVUsers = true; |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 469 | } else if (!AddUsersIfInteresting(User, L, Processed)) { |
Bill Wendling | b742703 | 2006-11-26 09:46:52 +0000 | [diff] [blame] | 470 | DOUT << "FOUND USER: " << *User |
| 471 | << " OF SCEV: " << *ISE << "\n"; |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 472 | AddUserToIVUsers = true; |
| 473 | } |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 474 | |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 475 | if (AddUserToIVUsers) { |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 476 | IVUsersOfOneStride &StrideUses = IVUsesByStride[Stride]; |
| 477 | if (StrideUses.Users.empty()) // First occurance of this stride? |
| 478 | StrideOrder.push_back(Stride); |
| 479 | |
Chris Lattner | a4479ad | 2005-08-04 00:40:47 +0000 | [diff] [blame] | 480 | // Okay, we found a user that we cannot reduce. Analyze the instruction |
Chris Lattner | c6bae65 | 2005-09-12 06:04:47 +0000 | [diff] [blame] | 481 | // and decide what to do with it. If we are a use inside of the loop, use |
| 482 | // the value before incrementation, otherwise use it after incrementation. |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 483 | if (IVUseShouldUsePostIncValue(User, I, L, DT, this, DeadInsts)) { |
Chris Lattner | c6bae65 | 2005-09-12 06:04:47 +0000 | [diff] [blame] | 484 | // The value used will be incremented by the stride more than we are |
| 485 | // expecting, so subtract this off. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 486 | SCEVHandle NewStart = SE->getMinusSCEV(Start, Stride); |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 487 | StrideUses.addUser(NewStart, User, I); |
| 488 | StrideUses.Users.back().isUseOfPostIncrementedValue = true; |
Bill Wendling | b742703 | 2006-11-26 09:46:52 +0000 | [diff] [blame] | 489 | DOUT << " USING POSTINC SCEV, START=" << *NewStart<< "\n"; |
Chris Lattner | 0ae33eb | 2005-10-03 01:04:44 +0000 | [diff] [blame] | 490 | } else { |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 491 | StrideUses.addUser(Start, User, I); |
Chris Lattner | c6bae65 | 2005-09-12 06:04:47 +0000 | [diff] [blame] | 492 | } |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 493 | } |
| 494 | } |
| 495 | return true; |
| 496 | } |
| 497 | |
| 498 | namespace { |
| 499 | /// BasedUser - For a particular base value, keep information about how we've |
| 500 | /// partitioned the expression so far. |
| 501 | struct BasedUser { |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 502 | /// SE - The current ScalarEvolution object. |
| 503 | ScalarEvolution *SE; |
| 504 | |
Chris Lattner | a553b0c | 2005-08-08 22:56:21 +0000 | [diff] [blame] | 505 | /// Base - The Base value for the PHI node that needs to be inserted for |
| 506 | /// this use. As the use is processed, information gets moved from this |
| 507 | /// field to the Imm field (below). BasedUser values are sorted by this |
| 508 | /// field. |
| 509 | SCEVHandle Base; |
| 510 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 511 | /// Inst - The instruction using the induction variable. |
| 512 | Instruction *Inst; |
| 513 | |
Chris Lattner | ec3fb63 | 2005-08-03 22:21:05 +0000 | [diff] [blame] | 514 | /// OperandValToReplace - The operand value of Inst to replace with the |
| 515 | /// EmittedBase. |
| 516 | Value *OperandValToReplace; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 517 | |
| 518 | /// Imm - The immediate value that should be added to the base immediately |
| 519 | /// before Inst, because it will be folded into the imm field of the |
| 520 | /// instruction. |
| 521 | SCEVHandle Imm; |
| 522 | |
| 523 | /// EmittedBase - The actual value* to use for the base value of this |
| 524 | /// operation. This is null if we should just use zero so far. |
| 525 | Value *EmittedBase; |
| 526 | |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 527 | // isUseOfPostIncrementedValue - True if this should use the |
| 528 | // post-incremented version of this IV, not the preincremented version. |
| 529 | // This can only be set in special cases, such as the terminating setcc |
Chris Lattner | c6bae65 | 2005-09-12 06:04:47 +0000 | [diff] [blame] | 530 | // instruction for a loop and uses outside the loop that are dominated by |
| 531 | // the loop. |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 532 | bool isUseOfPostIncrementedValue; |
Chris Lattner | a553b0c | 2005-08-08 22:56:21 +0000 | [diff] [blame] | 533 | |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 534 | BasedUser(IVStrideUse &IVSU, ScalarEvolution *se) |
| 535 | : SE(se), Base(IVSU.Offset), Inst(IVSU.User), |
Chris Lattner | a553b0c | 2005-08-08 22:56:21 +0000 | [diff] [blame] | 536 | OperandValToReplace(IVSU.OperandValToReplace), |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 537 | Imm(SE->getIntegerSCEV(0, Base->getType())), EmittedBase(0), |
Chris Lattner | a553b0c | 2005-08-08 22:56:21 +0000 | [diff] [blame] | 538 | isUseOfPostIncrementedValue(IVSU.isUseOfPostIncrementedValue) {} |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 539 | |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 540 | // Once we rewrite the code to insert the new IVs we want, update the |
| 541 | // operands of Inst to use the new expression 'NewBase', with 'Imm' added |
| 542 | // to it. |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 543 | void RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 544 | SCEVExpander &Rewriter, Loop *L, Pass *P, |
| 545 | SmallPtrSet<Instruction*,16> &DeadInsts); |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 546 | |
| 547 | Value *InsertCodeForBaseAtPosition(const SCEVHandle &NewBase, |
| 548 | SCEVExpander &Rewriter, |
| 549 | Instruction *IP, Loop *L); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 550 | void dump() const; |
| 551 | }; |
| 552 | } |
| 553 | |
| 554 | void BasedUser::dump() const { |
Bill Wendling | e815619 | 2006-12-07 01:30:32 +0000 | [diff] [blame] | 555 | cerr << " Base=" << *Base; |
| 556 | cerr << " Imm=" << *Imm; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 557 | if (EmittedBase) |
Bill Wendling | e815619 | 2006-12-07 01:30:32 +0000 | [diff] [blame] | 558 | cerr << " EB=" << *EmittedBase; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 559 | |
Bill Wendling | e815619 | 2006-12-07 01:30:32 +0000 | [diff] [blame] | 560 | cerr << " Inst: " << *Inst; |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 561 | } |
| 562 | |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 563 | Value *BasedUser::InsertCodeForBaseAtPosition(const SCEVHandle &NewBase, |
| 564 | SCEVExpander &Rewriter, |
| 565 | Instruction *IP, Loop *L) { |
| 566 | // Figure out where we *really* want to insert this code. In particular, if |
| 567 | // the user is inside of a loop that is nested inside of L, we really don't |
| 568 | // want to insert this expression before the user, we'd rather pull it out as |
| 569 | // many loops as possible. |
| 570 | LoopInfo &LI = Rewriter.getLoopInfo(); |
| 571 | Instruction *BaseInsertPt = IP; |
| 572 | |
| 573 | // Figure out the most-nested loop that IP is in. |
| 574 | Loop *InsertLoop = LI.getLoopFor(IP->getParent()); |
| 575 | |
| 576 | // If InsertLoop is not L, and InsertLoop is nested inside of L, figure out |
| 577 | // the preheader of the outer-most loop where NewBase is not loop invariant. |
| 578 | while (InsertLoop && NewBase->isLoopInvariant(InsertLoop)) { |
| 579 | BaseInsertPt = InsertLoop->getLoopPreheader()->getTerminator(); |
| 580 | InsertLoop = InsertLoop->getParentLoop(); |
| 581 | } |
| 582 | |
| 583 | // If there is no immediate value, skip the next part. |
| 584 | if (SCEVConstant *SC = dyn_cast<SCEVConstant>(Imm)) |
Reid Spencer | bee0f66 | 2007-03-02 23:51:25 +0000 | [diff] [blame] | 585 | if (SC->getValue()->isZero()) |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 586 | return Rewriter.expandCodeFor(NewBase, BaseInsertPt); |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 587 | |
| 588 | Value *Base = Rewriter.expandCodeFor(NewBase, BaseInsertPt); |
Chris Lattner | b47f612 | 2007-06-06 01:23:55 +0000 | [diff] [blame] | 589 | |
| 590 | // If we are inserting the base and imm values in the same block, make sure to |
| 591 | // adjust the IP position if insertion reused a result. |
| 592 | if (IP == BaseInsertPt) |
| 593 | IP = Rewriter.getInsertionPoint(); |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 594 | |
| 595 | // Always emit the immediate (if non-zero) into the same block as the user. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 596 | SCEVHandle NewValSCEV = SE->getAddExpr(SE->getUnknown(Base), Imm); |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 597 | return Rewriter.expandCodeFor(NewValSCEV, IP); |
Chris Lattner | b47f612 | 2007-06-06 01:23:55 +0000 | [diff] [blame] | 598 | |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 599 | } |
| 600 | |
| 601 | |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 602 | // Once we rewrite the code to insert the new IVs we want, update the |
| 603 | // operands of Inst to use the new expression 'NewBase', with 'Imm' added |
| 604 | // to it. |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 605 | void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase, |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 606 | SCEVExpander &Rewriter, Loop *L, Pass *P, |
| 607 | SmallPtrSet<Instruction*,16> &DeadInsts) { |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 608 | if (!isa<PHINode>(Inst)) { |
Chris Lattner | c5494af | 2007-04-13 20:42:26 +0000 | [diff] [blame] | 609 | // By default, insert code at the user instruction. |
| 610 | BasicBlock::iterator InsertPt = Inst; |
| 611 | |
| 612 | // However, if the Operand is itself an instruction, the (potentially |
| 613 | // complex) inserted code may be shared by many users. Because of this, we |
| 614 | // want to emit code for the computation of the operand right before its old |
| 615 | // computation. This is usually safe, because we obviously used to use the |
| 616 | // computation when it was computed in its current block. However, in some |
| 617 | // cases (e.g. use of a post-incremented induction variable) the NewBase |
| 618 | // value will be pinned to live somewhere after the original computation. |
| 619 | // In this case, we have to back off. |
| 620 | if (!isUseOfPostIncrementedValue) { |
| 621 | if (Instruction *OpInst = dyn_cast<Instruction>(OperandValToReplace)) { |
| 622 | InsertPt = OpInst; |
| 623 | while (isa<PHINode>(InsertPt)) ++InsertPt; |
| 624 | } |
| 625 | } |
Chris Lattner | c5494af | 2007-04-13 20:42:26 +0000 | [diff] [blame] | 626 | Value *NewVal = InsertCodeForBaseAtPosition(NewBase, Rewriter, InsertPt, L); |
Dan Gohman | a9cfed7 | 2007-07-31 17:22:27 +0000 | [diff] [blame] | 627 | // Adjust the type back to match the Inst. Note that we can't use InsertPt |
| 628 | // here because the SCEVExpander may have inserted the instructions after |
| 629 | // that point, in its efforts to avoid inserting redundant expressions. |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 630 | if (isa<PointerType>(OperandValToReplace->getType())) { |
Dan Gohman | a9cfed7 | 2007-07-31 17:22:27 +0000 | [diff] [blame] | 631 | NewVal = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr, |
| 632 | NewVal, |
| 633 | OperandValToReplace->getType()); |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 634 | } |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 635 | // Replace the use of the operand Value with the new Phi we just created. |
| 636 | Inst->replaceUsesOfWith(OperandValToReplace, NewVal); |
Chris Lattner | 7d8ed8a | 2007-05-11 22:40:34 +0000 | [diff] [blame] | 637 | DOUT << " CHANGED: IMM =" << *Imm; |
| 638 | DOUT << " \tNEWBASE =" << *NewBase; |
| 639 | DOUT << " \tInst = " << *Inst; |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 640 | return; |
| 641 | } |
| 642 | |
| 643 | // PHI nodes are more complex. We have to insert one copy of the NewBase+Imm |
Chris Lattner | c41e345 | 2005-08-10 00:35:32 +0000 | [diff] [blame] | 644 | // expression into each operand block that uses it. Note that PHI nodes can |
| 645 | // have multiple entries for the same predecessor. We use a map to make sure |
| 646 | // that a PHI node only has a single Value* for each predecessor (which also |
| 647 | // prevents us from inserting duplicate code in some blocks). |
Evan Cheng | 8392772 | 2007-10-30 22:27:26 +0000 | [diff] [blame] | 648 | DenseMap<BasicBlock*, Value*> InsertedCode; |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 649 | PHINode *PN = cast<PHINode>(Inst); |
| 650 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
| 651 | if (PN->getIncomingValue(i) == OperandValToReplace) { |
Chris Lattner | e0391be | 2005-08-12 22:06:11 +0000 | [diff] [blame] | 652 | // If this is a critical edge, split the edge so that we do not insert the |
Chris Lattner | 396b2ba | 2005-09-13 02:09:55 +0000 | [diff] [blame] | 653 | // code on all predecessor/successor paths. We do this unless this is the |
| 654 | // canonical backedge for this loop, as this can make some inserted code |
| 655 | // be in an illegal position. |
Chris Lattner | 37edbf0 | 2005-10-03 00:31:52 +0000 | [diff] [blame] | 656 | BasicBlock *PHIPred = PN->getIncomingBlock(i); |
| 657 | if (e != 1 && PHIPred->getTerminator()->getNumSuccessors() > 1 && |
| 658 | (PN->getParent() != L->getHeader() || !L->contains(PHIPred))) { |
Chris Lattner | 37edbf0 | 2005-10-03 00:31:52 +0000 | [diff] [blame] | 659 | |
Chris Lattner | aa96ae7 | 2005-08-17 06:35:16 +0000 | [diff] [blame] | 660 | // First step, split the critical edge. |
Evan Cheng | 8392772 | 2007-10-30 22:27:26 +0000 | [diff] [blame] | 661 | SplitCriticalEdge(PHIPred, PN->getParent(), P, false); |
Chris Lattner | c60fb08 | 2005-08-12 22:22:17 +0000 | [diff] [blame] | 662 | |
Chris Lattner | aa96ae7 | 2005-08-17 06:35:16 +0000 | [diff] [blame] | 663 | // Next step: move the basic block. In particular, if the PHI node |
| 664 | // is outside of the loop, and PredTI is in the loop, we want to |
| 665 | // move the block to be immediately before the PHI block, not |
| 666 | // immediately after PredTI. |
Chris Lattner | 37edbf0 | 2005-10-03 00:31:52 +0000 | [diff] [blame] | 667 | if (L->contains(PHIPred) && !L->contains(PN->getParent())) { |
Chris Lattner | aa96ae7 | 2005-08-17 06:35:16 +0000 | [diff] [blame] | 668 | BasicBlock *NewBB = PN->getIncomingBlock(i); |
| 669 | NewBB->moveBefore(PN->getParent()); |
Chris Lattner | e0391be | 2005-08-12 22:06:11 +0000 | [diff] [blame] | 670 | } |
Chris Lattner | 1b9c8e7 | 2006-10-28 00:59:20 +0000 | [diff] [blame] | 671 | |
| 672 | // Splitting the edge can reduce the number of PHI entries we have. |
| 673 | e = PN->getNumIncomingValues(); |
Chris Lattner | e0391be | 2005-08-12 22:06:11 +0000 | [diff] [blame] | 674 | } |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 675 | |
Chris Lattner | c41e345 | 2005-08-10 00:35:32 +0000 | [diff] [blame] | 676 | Value *&Code = InsertedCode[PN->getIncomingBlock(i)]; |
| 677 | if (!Code) { |
| 678 | // Insert the code into the end of the predecessor block. |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 679 | Instruction *InsertPt = PN->getIncomingBlock(i)->getTerminator(); |
| 680 | Code = InsertCodeForBaseAtPosition(NewBase, Rewriter, InsertPt, L); |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 681 | |
Chris Lattner | 684b22d | 2007-08-02 16:53:43 +0000 | [diff] [blame] | 682 | // Adjust the type back to match the PHI. Note that we can't use |
| 683 | // InsertPt here because the SCEVExpander may have inserted its |
| 684 | // instructions after that point, in its efforts to avoid inserting |
| 685 | // redundant expressions. |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 686 | if (isa<PointerType>(PN->getType())) { |
Dan Gohman | a9cfed7 | 2007-07-31 17:22:27 +0000 | [diff] [blame] | 687 | Code = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr, |
| 688 | Code, |
| 689 | PN->getType()); |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 690 | } |
Chris Lattner | c41e345 | 2005-08-10 00:35:32 +0000 | [diff] [blame] | 691 | } |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 692 | |
| 693 | // Replace the use of the operand Value with the new Phi we just created. |
Chris Lattner | c41e345 | 2005-08-10 00:35:32 +0000 | [diff] [blame] | 694 | PN->setIncomingValue(i, Code); |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 695 | Rewriter.clear(); |
| 696 | } |
| 697 | } |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 698 | |
| 699 | // PHI node might have become a constant value after SplitCriticalEdge. |
| 700 | DeadInsts.insert(Inst); |
| 701 | |
Bill Wendling | b742703 | 2006-11-26 09:46:52 +0000 | [diff] [blame] | 702 | DOUT << " CHANGED: IMM =" << *Imm << " Inst = " << *Inst; |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 703 | } |
| 704 | |
| 705 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 706 | /// isTargetConstant - Return true if the following can be referenced by the |
| 707 | /// immediate field of a target instruction. |
Evan Cheng | 1d95816 | 2007-03-13 20:34:37 +0000 | [diff] [blame] | 708 | static bool isTargetConstant(const SCEVHandle &V, const Type *UseTy, |
| 709 | const TargetLowering *TLI) { |
Chris Lattner | 3821e47 | 2005-08-08 06:25:50 +0000 | [diff] [blame] | 710 | if (SCEVConstant *SC = dyn_cast<SCEVConstant>(V)) { |
Evan Cheng | 5eef2d2 | 2007-03-12 23:27:37 +0000 | [diff] [blame] | 711 | int64_t VC = SC->getValue()->getSExtValue(); |
Chris Lattner | 579633c | 2007-04-09 22:20:14 +0000 | [diff] [blame] | 712 | if (TLI) { |
| 713 | TargetLowering::AddrMode AM; |
| 714 | AM.BaseOffs = VC; |
| 715 | return TLI->isLegalAddressingMode(AM, UseTy); |
| 716 | } else { |
Evan Cheng | d277f2c | 2006-03-13 23:14:23 +0000 | [diff] [blame] | 717 | // Defaults to PPC. PPC allows a sign-extended 16-bit immediate field. |
Evan Cheng | 5eef2d2 | 2007-03-12 23:27:37 +0000 | [diff] [blame] | 718 | return (VC > -(1 << 16) && VC < (1 << 16)-1); |
Chris Lattner | 579633c | 2007-04-09 22:20:14 +0000 | [diff] [blame] | 719 | } |
Chris Lattner | 3821e47 | 2005-08-08 06:25:50 +0000 | [diff] [blame] | 720 | } |
Jeff Cohen | d29b6aa | 2005-07-30 18:33:25 +0000 | [diff] [blame] | 721 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 722 | if (SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) |
| 723 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(SU->getValue())) |
Chris Lattner | 579633c | 2007-04-09 22:20:14 +0000 | [diff] [blame] | 724 | if (TLI && CE->getOpcode() == Instruction::PtrToInt) { |
Evan Cheng | d277f2c | 2006-03-13 23:14:23 +0000 | [diff] [blame] | 725 | Constant *Op0 = CE->getOperand(0); |
Chris Lattner | 579633c | 2007-04-09 22:20:14 +0000 | [diff] [blame] | 726 | if (GlobalValue *GV = dyn_cast<GlobalValue>(Op0)) { |
| 727 | TargetLowering::AddrMode AM; |
| 728 | AM.BaseGV = GV; |
| 729 | return TLI->isLegalAddressingMode(AM, UseTy); |
| 730 | } |
Evan Cheng | d277f2c | 2006-03-13 23:14:23 +0000 | [diff] [blame] | 731 | } |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 732 | return false; |
| 733 | } |
| 734 | |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 735 | /// MoveLoopVariantsToImediateField - Move any subexpressions from Val that are |
| 736 | /// loop varying to the Imm operand. |
| 737 | static void MoveLoopVariantsToImediateField(SCEVHandle &Val, SCEVHandle &Imm, |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 738 | Loop *L, ScalarEvolution *SE) { |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 739 | if (Val->isLoopInvariant(L)) return; // Nothing to do. |
| 740 | |
| 741 | if (SCEVAddExpr *SAE = dyn_cast<SCEVAddExpr>(Val)) { |
| 742 | std::vector<SCEVHandle> NewOps; |
| 743 | NewOps.reserve(SAE->getNumOperands()); |
| 744 | |
| 745 | for (unsigned i = 0; i != SAE->getNumOperands(); ++i) |
| 746 | if (!SAE->getOperand(i)->isLoopInvariant(L)) { |
| 747 | // If this is a loop-variant expression, it must stay in the immediate |
| 748 | // field of the expression. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 749 | Imm = SE->getAddExpr(Imm, SAE->getOperand(i)); |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 750 | } else { |
| 751 | NewOps.push_back(SAE->getOperand(i)); |
| 752 | } |
| 753 | |
| 754 | if (NewOps.empty()) |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 755 | Val = SE->getIntegerSCEV(0, Val->getType()); |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 756 | else |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 757 | Val = SE->getAddExpr(NewOps); |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 758 | } else if (SCEVAddRecExpr *SARE = dyn_cast<SCEVAddRecExpr>(Val)) { |
| 759 | // Try to pull immediates out of the start value of nested addrec's. |
| 760 | SCEVHandle Start = SARE->getStart(); |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 761 | MoveLoopVariantsToImediateField(Start, Imm, L, SE); |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 762 | |
| 763 | std::vector<SCEVHandle> Ops(SARE->op_begin(), SARE->op_end()); |
| 764 | Ops[0] = Start; |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 765 | Val = SE->getAddRecExpr(Ops, SARE->getLoop()); |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 766 | } else { |
| 767 | // Otherwise, all of Val is variant, move the whole thing over. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 768 | Imm = SE->getAddExpr(Imm, Val); |
| 769 | Val = SE->getIntegerSCEV(0, Val->getType()); |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 770 | } |
| 771 | } |
| 772 | |
| 773 | |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 774 | /// MoveImmediateValues - Look at Val, and pull out any additions of constants |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 775 | /// that can fit into the immediate field of instructions in the target. |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 776 | /// Accumulate these immediate values into the Imm value. |
Evan Cheng | d277f2c | 2006-03-13 23:14:23 +0000 | [diff] [blame] | 777 | static void MoveImmediateValues(const TargetLowering *TLI, |
Evan Cheng | 1d95816 | 2007-03-13 20:34:37 +0000 | [diff] [blame] | 778 | Instruction *User, |
Evan Cheng | d277f2c | 2006-03-13 23:14:23 +0000 | [diff] [blame] | 779 | SCEVHandle &Val, SCEVHandle &Imm, |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 780 | bool isAddress, Loop *L, |
| 781 | ScalarEvolution *SE) { |
Evan Cheng | 1d95816 | 2007-03-13 20:34:37 +0000 | [diff] [blame] | 782 | const Type *UseTy = User->getType(); |
| 783 | if (StoreInst *SI = dyn_cast<StoreInst>(User)) |
| 784 | UseTy = SI->getOperand(0)->getType(); |
| 785 | |
Chris Lattner | 7a65839 | 2005-08-03 23:44:42 +0000 | [diff] [blame] | 786 | if (SCEVAddExpr *SAE = dyn_cast<SCEVAddExpr>(Val)) { |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 787 | std::vector<SCEVHandle> NewOps; |
| 788 | NewOps.reserve(SAE->getNumOperands()); |
| 789 | |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 790 | for (unsigned i = 0; i != SAE->getNumOperands(); ++i) { |
| 791 | SCEVHandle NewOp = SAE->getOperand(i); |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 792 | MoveImmediateValues(TLI, User, NewOp, Imm, isAddress, L, SE); |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 793 | |
| 794 | if (!NewOp->isLoopInvariant(L)) { |
Chris Lattner | 7db543f | 2005-08-04 19:08:16 +0000 | [diff] [blame] | 795 | // If this is a loop-variant expression, it must stay in the immediate |
| 796 | // field of the expression. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 797 | Imm = SE->getAddExpr(Imm, NewOp); |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 798 | } else { |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 799 | NewOps.push_back(NewOp); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 800 | } |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 801 | } |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 802 | |
| 803 | if (NewOps.empty()) |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 804 | Val = SE->getIntegerSCEV(0, Val->getType()); |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 805 | else |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 806 | Val = SE->getAddExpr(NewOps); |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 807 | return; |
Chris Lattner | 7a65839 | 2005-08-03 23:44:42 +0000 | [diff] [blame] | 808 | } else if (SCEVAddRecExpr *SARE = dyn_cast<SCEVAddRecExpr>(Val)) { |
| 809 | // Try to pull immediates out of the start value of nested addrec's. |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 810 | SCEVHandle Start = SARE->getStart(); |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 811 | MoveImmediateValues(TLI, User, Start, Imm, isAddress, L, SE); |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 812 | |
| 813 | if (Start != SARE->getStart()) { |
| 814 | std::vector<SCEVHandle> Ops(SARE->op_begin(), SARE->op_end()); |
| 815 | Ops[0] = Start; |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 816 | Val = SE->getAddRecExpr(Ops, SARE->getLoop()); |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 817 | } |
| 818 | return; |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 819 | } else if (SCEVMulExpr *SME = dyn_cast<SCEVMulExpr>(Val)) { |
| 820 | // Transform "8 * (4 + v)" -> "32 + 8*V" if "32" fits in the immed field. |
Evan Cheng | 1d95816 | 2007-03-13 20:34:37 +0000 | [diff] [blame] | 821 | if (isAddress && isTargetConstant(SME->getOperand(0), UseTy, TLI) && |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 822 | SME->getNumOperands() == 2 && SME->isLoopInvariant(L)) { |
| 823 | |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 824 | SCEVHandle SubImm = SE->getIntegerSCEV(0, Val->getType()); |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 825 | SCEVHandle NewOp = SME->getOperand(1); |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 826 | MoveImmediateValues(TLI, User, NewOp, SubImm, isAddress, L, SE); |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 827 | |
| 828 | // If we extracted something out of the subexpressions, see if we can |
| 829 | // simplify this! |
| 830 | if (NewOp != SME->getOperand(1)) { |
| 831 | // Scale SubImm up by "8". If the result is a target constant, we are |
| 832 | // good. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 833 | SubImm = SE->getMulExpr(SubImm, SME->getOperand(0)); |
Evan Cheng | 1d95816 | 2007-03-13 20:34:37 +0000 | [diff] [blame] | 834 | if (isTargetConstant(SubImm, UseTy, TLI)) { |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 835 | // Accumulate the immediate. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 836 | Imm = SE->getAddExpr(Imm, SubImm); |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 837 | |
| 838 | // Update what is left of 'Val'. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 839 | Val = SE->getMulExpr(SME->getOperand(0), NewOp); |
Chris Lattner | 221fc3c | 2006-02-04 07:36:50 +0000 | [diff] [blame] | 840 | return; |
| 841 | } |
| 842 | } |
| 843 | } |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 844 | } |
| 845 | |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 846 | // Loop-variant expressions must stay in the immediate field of the |
| 847 | // expression. |
Evan Cheng | 1d95816 | 2007-03-13 20:34:37 +0000 | [diff] [blame] | 848 | if ((isAddress && isTargetConstant(Val, UseTy, TLI)) || |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 849 | !Val->isLoopInvariant(L)) { |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 850 | Imm = SE->getAddExpr(Imm, Val); |
| 851 | Val = SE->getIntegerSCEV(0, Val->getType()); |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 852 | return; |
Chris Lattner | 7a2ca56 | 2005-08-04 19:26:19 +0000 | [diff] [blame] | 853 | } |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 854 | |
| 855 | // Otherwise, no immediates to move. |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 856 | } |
| 857 | |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 858 | |
Chris Lattner | 7e79b38 | 2006-08-03 06:34:50 +0000 | [diff] [blame] | 859 | /// SeparateSubExprs - Decompose Expr into all of the subexpressions that are |
| 860 | /// added together. This is used to reassociate common addition subexprs |
| 861 | /// together for maximal sharing when rewriting bases. |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 862 | static void SeparateSubExprs(std::vector<SCEVHandle> &SubExprs, |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 863 | SCEVHandle Expr, |
| 864 | ScalarEvolution *SE) { |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 865 | if (SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(Expr)) { |
| 866 | for (unsigned j = 0, e = AE->getNumOperands(); j != e; ++j) |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 867 | SeparateSubExprs(SubExprs, AE->getOperand(j), SE); |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 868 | } else if (SCEVAddRecExpr *SARE = dyn_cast<SCEVAddRecExpr>(Expr)) { |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 869 | SCEVHandle Zero = SE->getIntegerSCEV(0, Expr->getType()); |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 870 | if (SARE->getOperand(0) == Zero) { |
| 871 | SubExprs.push_back(Expr); |
| 872 | } else { |
| 873 | // Compute the addrec with zero as its base. |
| 874 | std::vector<SCEVHandle> Ops(SARE->op_begin(), SARE->op_end()); |
| 875 | Ops[0] = Zero; // Start with zero base. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 876 | SubExprs.push_back(SE->getAddRecExpr(Ops, SARE->getLoop())); |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 877 | |
| 878 | |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 879 | SeparateSubExprs(SubExprs, SARE->getOperand(0), SE); |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 880 | } |
| 881 | } else if (!isa<SCEVConstant>(Expr) || |
Reid Spencer | bee0f66 | 2007-03-02 23:51:25 +0000 | [diff] [blame] | 882 | !cast<SCEVConstant>(Expr)->getValue()->isZero()) { |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 883 | // Do not add zero. |
| 884 | SubExprs.push_back(Expr); |
| 885 | } |
| 886 | } |
| 887 | |
| 888 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 889 | /// RemoveCommonExpressionsFromUseBases - Look through all of the uses in Bases, |
| 890 | /// removing any common subexpressions from it. Anything truly common is |
| 891 | /// removed, accumulated, and returned. This looks for things like (a+b+c) and |
| 892 | /// (a+c+d) -> (a+c). The common expression is *removed* from the Bases. |
| 893 | static SCEVHandle |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 894 | RemoveCommonExpressionsFromUseBases(std::vector<BasedUser> &Uses, |
| 895 | ScalarEvolution *SE) { |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 896 | unsigned NumUses = Uses.size(); |
| 897 | |
| 898 | // Only one use? Use its base, regardless of what it is! |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 899 | SCEVHandle Zero = SE->getIntegerSCEV(0, Uses[0].Base->getType()); |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 900 | SCEVHandle Result = Zero; |
| 901 | if (NumUses == 1) { |
| 902 | std::swap(Result, Uses[0].Base); |
| 903 | return Result; |
| 904 | } |
| 905 | |
| 906 | // To find common subexpressions, count how many of Uses use each expression. |
| 907 | // If any subexpressions are used Uses.size() times, they are common. |
| 908 | std::map<SCEVHandle, unsigned> SubExpressionUseCounts; |
| 909 | |
Chris Lattner | d6155e9 | 2005-10-11 18:41:04 +0000 | [diff] [blame] | 910 | // UniqueSubExprs - Keep track of all of the subexpressions we see in the |
| 911 | // order we see them. |
| 912 | std::vector<SCEVHandle> UniqueSubExprs; |
| 913 | |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 914 | std::vector<SCEVHandle> SubExprs; |
| 915 | for (unsigned i = 0; i != NumUses; ++i) { |
| 916 | // If the base is zero (which is common), return zero now, there are no |
| 917 | // CSEs we can find. |
| 918 | if (Uses[i].Base == Zero) return Zero; |
| 919 | |
| 920 | // Split the expression into subexprs. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 921 | SeparateSubExprs(SubExprs, Uses[i].Base, SE); |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 922 | // Add one to SubExpressionUseCounts for each subexpr present. |
| 923 | for (unsigned j = 0, e = SubExprs.size(); j != e; ++j) |
Chris Lattner | d6155e9 | 2005-10-11 18:41:04 +0000 | [diff] [blame] | 924 | if (++SubExpressionUseCounts[SubExprs[j]] == 1) |
| 925 | UniqueSubExprs.push_back(SubExprs[j]); |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 926 | SubExprs.clear(); |
| 927 | } |
| 928 | |
Chris Lattner | d6155e9 | 2005-10-11 18:41:04 +0000 | [diff] [blame] | 929 | // Now that we know how many times each is used, build Result. Iterate over |
| 930 | // UniqueSubexprs so that we have a stable ordering. |
| 931 | for (unsigned i = 0, e = UniqueSubExprs.size(); i != e; ++i) { |
| 932 | std::map<SCEVHandle, unsigned>::iterator I = |
| 933 | SubExpressionUseCounts.find(UniqueSubExprs[i]); |
| 934 | assert(I != SubExpressionUseCounts.end() && "Entry not found?"); |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 935 | if (I->second == NumUses) { // Found CSE! |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 936 | Result = SE->getAddExpr(Result, I->first); |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 937 | } else { |
| 938 | // Remove non-cse's from SubExpressionUseCounts. |
Chris Lattner | d6155e9 | 2005-10-11 18:41:04 +0000 | [diff] [blame] | 939 | SubExpressionUseCounts.erase(I); |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 940 | } |
Chris Lattner | d6155e9 | 2005-10-11 18:41:04 +0000 | [diff] [blame] | 941 | } |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 942 | |
| 943 | // If we found no CSE's, return now. |
| 944 | if (Result == Zero) return Result; |
| 945 | |
| 946 | // Otherwise, remove all of the CSE's we found from each of the base values. |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 947 | for (unsigned i = 0; i != NumUses; ++i) { |
| 948 | // Split the expression into subexprs. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 949 | SeparateSubExprs(SubExprs, Uses[i].Base, SE); |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 950 | |
| 951 | // Remove any common subexpressions. |
| 952 | for (unsigned j = 0, e = SubExprs.size(); j != e; ++j) |
| 953 | if (SubExpressionUseCounts.count(SubExprs[j])) { |
| 954 | SubExprs.erase(SubExprs.begin()+j); |
| 955 | --j; --e; |
| 956 | } |
| 957 | |
| 958 | // Finally, the non-shared expressions together. |
| 959 | if (SubExprs.empty()) |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 960 | Uses[i].Base = Zero; |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 961 | else |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 962 | Uses[i].Base = SE->getAddExpr(SubExprs); |
Chris Lattner | 27e5142 | 2005-08-13 07:42:01 +0000 | [diff] [blame] | 963 | SubExprs.clear(); |
Chris Lattner | 934520a | 2005-08-13 07:27:18 +0000 | [diff] [blame] | 964 | } |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 965 | |
| 966 | return Result; |
| 967 | } |
| 968 | |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 969 | /// isZero - returns true if the scalar evolution expression is zero. |
| 970 | /// |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 971 | static bool isZero(const SCEVHandle &V) { |
| 972 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(V)) |
Reid Spencer | bee0f66 | 2007-03-02 23:51:25 +0000 | [diff] [blame] | 973 | return SC->getValue()->isZero(); |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 974 | return false; |
| 975 | } |
| 976 | |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 977 | /// ValidStride - Check whether the given Scale is valid for all loads and |
Chris Lattner | 579633c | 2007-04-09 22:20:14 +0000 | [diff] [blame] | 978 | /// stores in UsersToProcess. |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 979 | /// |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 980 | bool LoopStrengthReduce::ValidStride(bool HasBaseReg, |
| 981 | int64_t Scale, |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 982 | const std::vector<BasedUser>& UsersToProcess) { |
Evan Cheng | d6b62a5 | 2007-12-19 23:33:23 +0000 | [diff] [blame] | 983 | if (!TLI) |
| 984 | return true; |
| 985 | |
Dale Johannesen | 8e59e16 | 2007-03-20 21:54:54 +0000 | [diff] [blame] | 986 | for (unsigned i=0, e = UsersToProcess.size(); i!=e; ++i) { |
Chris Lattner | 1ebd89e | 2007-04-02 06:34:44 +0000 | [diff] [blame] | 987 | // If this is a load or other access, pass the type of the access in. |
| 988 | const Type *AccessTy = Type::VoidTy; |
| 989 | if (StoreInst *SI = dyn_cast<StoreInst>(UsersToProcess[i].Inst)) |
| 990 | AccessTy = SI->getOperand(0)->getType(); |
| 991 | else if (LoadInst *LI = dyn_cast<LoadInst>(UsersToProcess[i].Inst)) |
| 992 | AccessTy = LI->getType(); |
Evan Cheng | 55e641b | 2008-03-19 22:02:26 +0000 | [diff] [blame] | 993 | else if (isa<PHINode>(UsersToProcess[i].Inst)) |
| 994 | continue; |
Chris Lattner | 1ebd89e | 2007-04-02 06:34:44 +0000 | [diff] [blame] | 995 | |
Chris Lattner | 579633c | 2007-04-09 22:20:14 +0000 | [diff] [blame] | 996 | TargetLowering::AddrMode AM; |
| 997 | if (SCEVConstant *SC = dyn_cast<SCEVConstant>(UsersToProcess[i].Imm)) |
| 998 | AM.BaseOffs = SC->getValue()->getSExtValue(); |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 999 | AM.HasBaseReg = HasBaseReg || !isZero(UsersToProcess[i].Base); |
Chris Lattner | 579633c | 2007-04-09 22:20:14 +0000 | [diff] [blame] | 1000 | AM.Scale = Scale; |
| 1001 | |
| 1002 | // If load[imm+r*scale] is illegal, bail out. |
Evan Cheng | d6b62a5 | 2007-12-19 23:33:23 +0000 | [diff] [blame] | 1003 | if (!TLI->isLegalAddressingMode(AM, AccessTy)) |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 1004 | return false; |
Dale Johannesen | 8e59e16 | 2007-03-20 21:54:54 +0000 | [diff] [blame] | 1005 | } |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 1006 | return true; |
| 1007 | } |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1008 | |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 1009 | /// RequiresTypeConversion - Returns true if converting Ty to NewTy is not |
| 1010 | /// a nop. |
Evan Cheng | 2bd122c | 2007-10-26 01:56:11 +0000 | [diff] [blame] | 1011 | bool LoopStrengthReduce::RequiresTypeConversion(const Type *Ty1, |
| 1012 | const Type *Ty2) { |
| 1013 | if (Ty1 == Ty2) |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 1014 | return false; |
Evan Cheng | 2bd122c | 2007-10-26 01:56:11 +0000 | [diff] [blame] | 1015 | if (TLI && TLI->isTruncateFree(Ty1, Ty2)) |
| 1016 | return false; |
| 1017 | return (!Ty1->canLosslesslyBitCastTo(Ty2) && |
| 1018 | !(isa<PointerType>(Ty2) && |
| 1019 | Ty1->canLosslesslyBitCastTo(UIntPtrTy)) && |
| 1020 | !(isa<PointerType>(Ty1) && |
| 1021 | Ty2->canLosslesslyBitCastTo(UIntPtrTy))); |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 1022 | } |
| 1023 | |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1024 | /// CheckForIVReuse - Returns the multiple if the stride is the multiple |
| 1025 | /// of a previous stride and it is a legal value for the target addressing |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 1026 | /// mode scale component and optional base reg. This allows the users of |
| 1027 | /// this stride to be rewritten as prev iv * factor. It returns 0 if no |
| 1028 | /// reuse is possible. |
| 1029 | unsigned LoopStrengthReduce::CheckForIVReuse(bool HasBaseReg, |
Evan Cheng | 2bd122c | 2007-10-26 01:56:11 +0000 | [diff] [blame] | 1030 | bool AllUsesAreAddresses, |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 1031 | const SCEVHandle &Stride, |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 1032 | IVExpr &IV, const Type *Ty, |
| 1033 | const std::vector<BasedUser>& UsersToProcess) { |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1034 | if (SCEVConstant *SC = dyn_cast<SCEVConstant>(Stride)) { |
Reid Spencer | 502db93 | 2007-03-02 23:37:53 +0000 | [diff] [blame] | 1035 | int64_t SInt = SC->getValue()->getSExtValue(); |
Dale Johannesen | b51b4b5 | 2007-11-17 02:48:01 +0000 | [diff] [blame] | 1036 | for (unsigned NewStride = 0, e = StrideOrder.size(); NewStride != e; |
| 1037 | ++NewStride) { |
| 1038 | std::map<SCEVHandle, IVsOfOneStride>::iterator SI = |
| 1039 | IVsByStride.find(StrideOrder[NewStride]); |
| 1040 | if (SI == IVsByStride.end()) |
| 1041 | continue; |
Evan Cheng | 5eef2d2 | 2007-03-12 23:27:37 +0000 | [diff] [blame] | 1042 | int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue(); |
Evan Cheng | 2bd122c | 2007-10-26 01:56:11 +0000 | [diff] [blame] | 1043 | if (SI->first != Stride && |
Chris Lattner | 1d31290 | 2007-04-02 22:51:58 +0000 | [diff] [blame] | 1044 | (unsigned(abs(SInt)) < SSInt || (SInt % SSInt) != 0)) |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1045 | continue; |
Evan Cheng | 5eef2d2 | 2007-03-12 23:27:37 +0000 | [diff] [blame] | 1046 | int64_t Scale = SInt / SSInt; |
Dale Johannesen | dc42f48 | 2007-03-20 00:47:50 +0000 | [diff] [blame] | 1047 | // Check that this stride is valid for all the types used for loads and |
| 1048 | // stores; if it can be used for some and not others, we might as well use |
| 1049 | // the original stride everywhere, since we have to create the IV for it |
Dan Gohman | aa34331 | 2007-10-29 19:23:53 +0000 | [diff] [blame] | 1050 | // anyway. If the scale is 1, then we don't need to worry about folding |
| 1051 | // multiplications. |
| 1052 | if (Scale == 1 || |
| 1053 | (AllUsesAreAddresses && |
| 1054 | ValidStride(HasBaseReg, Scale, UsersToProcess))) |
Evan Cheng | 5eef2d2 | 2007-03-12 23:27:37 +0000 | [diff] [blame] | 1055 | for (std::vector<IVExpr>::iterator II = SI->second.IVs.begin(), |
| 1056 | IE = SI->second.IVs.end(); II != IE; ++II) |
| 1057 | // FIXME: Only handle base == 0 for now. |
| 1058 | // Only reuse previous IV if it would not require a type conversion. |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 1059 | if (isZero(II->Base) && |
Evan Cheng | 2bd122c | 2007-10-26 01:56:11 +0000 | [diff] [blame] | 1060 | !RequiresTypeConversion(II->Base->getType(), Ty)) { |
Evan Cheng | 5eef2d2 | 2007-03-12 23:27:37 +0000 | [diff] [blame] | 1061 | IV = *II; |
| 1062 | return Scale; |
| 1063 | } |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1064 | } |
| 1065 | } |
Evan Cheng | 2149577 | 2006-03-18 08:03:12 +0000 | [diff] [blame] | 1066 | return 0; |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1067 | } |
| 1068 | |
Chris Lattner | 7e79b38 | 2006-08-03 06:34:50 +0000 | [diff] [blame] | 1069 | /// PartitionByIsUseOfPostIncrementedValue - Simple boolean predicate that |
| 1070 | /// returns true if Val's isUseOfPostIncrementedValue is true. |
| 1071 | static bool PartitionByIsUseOfPostIncrementedValue(const BasedUser &Val) { |
| 1072 | return Val.isUseOfPostIncrementedValue; |
| 1073 | } |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1074 | |
Chris Lattner | fb3e119 | 2007-05-19 01:22:21 +0000 | [diff] [blame] | 1075 | /// isNonConstantNegative - REturn true if the specified scev is negated, but |
| 1076 | /// not a constant. |
| 1077 | static bool isNonConstantNegative(const SCEVHandle &Expr) { |
| 1078 | SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Expr); |
| 1079 | if (!Mul) return false; |
| 1080 | |
| 1081 | // If there is a constant factor, it will be first. |
| 1082 | SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0)); |
| 1083 | if (!SC) return false; |
| 1084 | |
| 1085 | // Return true if the value is negative, this matches things like (-42 * V). |
| 1086 | return SC->getValue()->getValue().isNegative(); |
| 1087 | } |
| 1088 | |
Evan Cheng | d6b62a5 | 2007-12-19 23:33:23 +0000 | [diff] [blame] | 1089 | /// isAddress - Returns true if the specified instruction is using the |
| 1090 | /// specified value as an address. |
| 1091 | static bool isAddressUse(Instruction *Inst, Value *OperandVal) { |
| 1092 | bool isAddress = isa<LoadInst>(Inst); |
| 1093 | if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { |
| 1094 | if (SI->getOperand(1) == OperandVal) |
| 1095 | isAddress = true; |
| 1096 | } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) { |
| 1097 | // Addressing modes can also be folded into prefetches and a variety |
| 1098 | // of intrinsics. |
| 1099 | switch (II->getIntrinsicID()) { |
| 1100 | default: break; |
| 1101 | case Intrinsic::prefetch: |
| 1102 | case Intrinsic::x86_sse2_loadu_dq: |
| 1103 | case Intrinsic::x86_sse2_loadu_pd: |
| 1104 | case Intrinsic::x86_sse_loadu_ps: |
| 1105 | case Intrinsic::x86_sse_storeu_ps: |
| 1106 | case Intrinsic::x86_sse2_storeu_pd: |
| 1107 | case Intrinsic::x86_sse2_storeu_dq: |
| 1108 | case Intrinsic::x86_sse2_storel_dq: |
| 1109 | if (II->getOperand(1) == OperandVal) |
| 1110 | isAddress = true; |
| 1111 | break; |
| 1112 | case Intrinsic::x86_sse2_loadh_pd: |
| 1113 | case Intrinsic::x86_sse2_loadl_pd: |
| 1114 | if (II->getOperand(2) == OperandVal) |
| 1115 | isAddress = true; |
| 1116 | break; |
| 1117 | } |
| 1118 | } |
| 1119 | return isAddress; |
| 1120 | } |
| 1121 | |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 1122 | // CollectIVUsers - Transform our list of users and offsets to a bit more |
| 1123 | // complex table. In this new vector, each 'BasedUser' contains 'Base' the base |
| 1124 | // of the strided accessas well as the old information from Uses. We |
| 1125 | // progressively move information from the Base field to the Imm field, until |
| 1126 | // we eventually have the full access expression to rewrite the use. |
| 1127 | SCEVHandle LoopStrengthReduce::CollectIVUsers(const SCEVHandle &Stride, |
| 1128 | IVUsersOfOneStride &Uses, |
| 1129 | Loop *L, |
| 1130 | bool &AllUsesAreAddresses, |
| 1131 | std::vector<BasedUser> &UsersToProcess) { |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1132 | UsersToProcess.reserve(Uses.Users.size()); |
Chris Lattner | a553b0c | 2005-08-08 22:56:21 +0000 | [diff] [blame] | 1133 | for (unsigned i = 0, e = Uses.Users.size(); i != e; ++i) { |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1134 | UsersToProcess.push_back(BasedUser(Uses.Users[i], SE)); |
Chris Lattner | a553b0c | 2005-08-08 22:56:21 +0000 | [diff] [blame] | 1135 | |
| 1136 | // Move any loop invariant operands from the offset field to the immediate |
| 1137 | // field of the use, so that we don't try to use something before it is |
| 1138 | // computed. |
| 1139 | MoveLoopVariantsToImediateField(UsersToProcess.back().Base, |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1140 | UsersToProcess.back().Imm, L, SE); |
Chris Lattner | a553b0c | 2005-08-08 22:56:21 +0000 | [diff] [blame] | 1141 | assert(UsersToProcess.back().Base->isLoopInvariant(L) && |
Chris Lattner | 26d91f1 | 2005-08-04 22:34:05 +0000 | [diff] [blame] | 1142 | "Base value is not loop invariant!"); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1143 | } |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1144 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1145 | // We now have a whole bunch of uses of like-strided induction variables, but |
| 1146 | // they might all have different bases. We want to emit one PHI node for this |
| 1147 | // stride which we fold as many common expressions (between the IVs) into as |
| 1148 | // possible. Start by identifying the common expressions in the base values |
| 1149 | // for the strides (e.g. if we have "A+C+B" and "A+B+D" as our bases, find |
| 1150 | // "A+B"), emit it to the preheader, then remove the expression from the |
| 1151 | // UsersToProcess base values. |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1152 | SCEVHandle CommonExprs = |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1153 | RemoveCommonExpressionsFromUseBases(UsersToProcess, SE); |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 1154 | |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 1155 | // Next, figure out what we can represent in the immediate fields of |
| 1156 | // instructions. If we can represent anything there, move it to the imm |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1157 | // fields of the BasedUsers. We do this so that it increases the commonality |
| 1158 | // of the remaining uses. |
Evan Cheng | 32e4c7c | 2007-12-20 02:20:53 +0000 | [diff] [blame] | 1159 | unsigned NumPHI = 0; |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 1160 | for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i) { |
Chris Lattner | 80b32b3 | 2005-08-16 00:38:11 +0000 | [diff] [blame] | 1161 | // If the user is not in the current loop, this means it is using the exit |
| 1162 | // value of the IV. Do not put anything in the base, make sure it's all in |
| 1163 | // the immediate field to allow as much factoring as possible. |
| 1164 | if (!L->contains(UsersToProcess[i].Inst->getParent())) { |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1165 | UsersToProcess[i].Imm = SE->getAddExpr(UsersToProcess[i].Imm, |
| 1166 | UsersToProcess[i].Base); |
Chris Lattner | 8385e51 | 2005-08-17 21:22:41 +0000 | [diff] [blame] | 1167 | UsersToProcess[i].Base = |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1168 | SE->getIntegerSCEV(0, UsersToProcess[i].Base->getType()); |
Chris Lattner | 80b32b3 | 2005-08-16 00:38:11 +0000 | [diff] [blame] | 1169 | } else { |
| 1170 | |
| 1171 | // Addressing modes can be folded into loads and stores. Be careful that |
| 1172 | // the store is through the expression, not of the expression though. |
Evan Cheng | 32e4c7c | 2007-12-20 02:20:53 +0000 | [diff] [blame] | 1173 | bool isPHI = false; |
Evan Cheng | d6b62a5 | 2007-12-19 23:33:23 +0000 | [diff] [blame] | 1174 | bool isAddress = isAddressUse(UsersToProcess[i].Inst, |
| 1175 | UsersToProcess[i].OperandValToReplace); |
| 1176 | if (isa<PHINode>(UsersToProcess[i].Inst)) { |
Evan Cheng | 32e4c7c | 2007-12-20 02:20:53 +0000 | [diff] [blame] | 1177 | isPHI = true; |
| 1178 | ++NumPHI; |
Dan Gohman | 2acc760 | 2007-05-03 23:20:33 +0000 | [diff] [blame] | 1179 | } |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 1180 | |
| 1181 | // If this use isn't an address, then not all uses are addresses. |
Evan Cheng | 55e641b | 2008-03-19 22:02:26 +0000 | [diff] [blame] | 1182 | if (!isAddress && !isPHI) |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 1183 | AllUsesAreAddresses = false; |
Chris Lattner | 80b32b3 | 2005-08-16 00:38:11 +0000 | [diff] [blame] | 1184 | |
Evan Cheng | 1d95816 | 2007-03-13 20:34:37 +0000 | [diff] [blame] | 1185 | MoveImmediateValues(TLI, UsersToProcess[i].Inst, UsersToProcess[i].Base, |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1186 | UsersToProcess[i].Imm, isAddress, L, SE); |
Chris Lattner | 80b32b3 | 2005-08-16 00:38:11 +0000 | [diff] [blame] | 1187 | } |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 1188 | } |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1189 | |
Evan Cheng | 32e4c7c | 2007-12-20 02:20:53 +0000 | [diff] [blame] | 1190 | // If one of the use if a PHI node and all other uses are addresses, still |
| 1191 | // allow iv reuse. Essentially we are trading one constant multiplication |
| 1192 | // for one fewer iv. |
| 1193 | if (NumPHI > 1) |
| 1194 | AllUsesAreAddresses = false; |
| 1195 | |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 1196 | return CommonExprs; |
| 1197 | } |
| 1198 | |
| 1199 | /// StrengthReduceStridedIVUsers - Strength reduce all of the users of a single |
| 1200 | /// stride of IV. All of the users may have different starting values, and this |
| 1201 | /// may not be the only stride (we know it is if isOnlyStride is true). |
| 1202 | void LoopStrengthReduce::StrengthReduceStridedIVUsers(const SCEVHandle &Stride, |
| 1203 | IVUsersOfOneStride &Uses, |
| 1204 | Loop *L, |
| 1205 | bool isOnlyStride) { |
| 1206 | // If all the users are moved to another stride, then there is nothing to do. |
Dan Gohman | 3035959 | 2008-01-29 13:02:09 +0000 | [diff] [blame] | 1207 | if (Uses.Users.empty()) |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 1208 | return; |
| 1209 | |
| 1210 | // Keep track if every use in UsersToProcess is an address. If they all are, |
| 1211 | // we may be able to rewrite the entire collection of them in terms of a |
| 1212 | // smaller-stride IV. |
| 1213 | bool AllUsesAreAddresses = true; |
| 1214 | |
| 1215 | // Transform our list of users and offsets to a bit more complex table. In |
| 1216 | // this new vector, each 'BasedUser' contains 'Base' the base of the |
| 1217 | // strided accessas well as the old information from Uses. We progressively |
| 1218 | // move information from the Base field to the Imm field, until we eventually |
| 1219 | // have the full access expression to rewrite the use. |
| 1220 | std::vector<BasedUser> UsersToProcess; |
| 1221 | SCEVHandle CommonExprs = CollectIVUsers(Stride, Uses, L, AllUsesAreAddresses, |
| 1222 | UsersToProcess); |
| 1223 | |
| 1224 | // If we managed to find some expressions in common, we'll need to carry |
| 1225 | // their value in a register and add it in for each use. This will take up |
| 1226 | // a register operand, which potentially restricts what stride values are |
| 1227 | // valid. |
| 1228 | bool HaveCommonExprs = !isZero(CommonExprs); |
| 1229 | |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 1230 | // If all uses are addresses, check if it is possible to reuse an IV with a |
| 1231 | // stride that is a factor of this stride. And that the multiple is a number |
| 1232 | // that can be encoded in the scale field of the target addressing mode. And |
| 1233 | // that we will have a valid instruction after this substition, including the |
| 1234 | // immediate field, if any. |
Dale Johannesen | 8e59e16 | 2007-03-20 21:54:54 +0000 | [diff] [blame] | 1235 | PHINode *NewPHI = NULL; |
| 1236 | Value *IncV = NULL; |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1237 | IVExpr ReuseIV(SE->getIntegerSCEV(0, Type::Int32Ty), |
| 1238 | SE->getIntegerSCEV(0, Type::Int32Ty), |
| 1239 | 0, 0); |
Dan Gohman | 02e4fa7 | 2007-10-22 20:40:42 +0000 | [diff] [blame] | 1240 | unsigned RewriteFactor = 0; |
Evan Cheng | 2bd122c | 2007-10-26 01:56:11 +0000 | [diff] [blame] | 1241 | RewriteFactor = CheckForIVReuse(HaveCommonExprs, AllUsesAreAddresses, |
| 1242 | Stride, ReuseIV, CommonExprs->getType(), |
| 1243 | UsersToProcess); |
Dale Johannesen | 8e59e16 | 2007-03-20 21:54:54 +0000 | [diff] [blame] | 1244 | if (RewriteFactor != 0) { |
| 1245 | DOUT << "BASED ON IV of STRIDE " << *ReuseIV.Stride |
| 1246 | << " and BASE " << *ReuseIV.Base << " :\n"; |
| 1247 | NewPHI = ReuseIV.PHI; |
| 1248 | IncV = ReuseIV.IncV; |
| 1249 | } |
| 1250 | |
Chris Lattner | fe35555 | 2007-04-01 22:21:39 +0000 | [diff] [blame] | 1251 | const Type *ReplacedTy = CommonExprs->getType(); |
| 1252 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1253 | // Now that we know what we need to do, insert the PHI node itself. |
| 1254 | // |
Chris Lattner | fe35555 | 2007-04-01 22:21:39 +0000 | [diff] [blame] | 1255 | DOUT << "INSERTING IV of TYPE " << *ReplacedTy << " of STRIDE " |
Chris Lattner | 7d8ed8a | 2007-05-11 22:40:34 +0000 | [diff] [blame] | 1256 | << *Stride << " and BASE " << *CommonExprs << ": "; |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1257 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1258 | SCEVExpander Rewriter(*SE, *LI); |
| 1259 | SCEVExpander PreheaderRewriter(*SE, *LI); |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 1260 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1261 | BasicBlock *Preheader = L->getLoopPreheader(); |
| 1262 | Instruction *PreInsertPt = Preheader->getTerminator(); |
| 1263 | Instruction *PhiInsertBefore = L->getHeader()->begin(); |
Chris Lattner | 44b807e | 2005-08-08 22:32:34 +0000 | [diff] [blame] | 1264 | |
Chris Lattner | 12b5041 | 2005-09-12 17:11:27 +0000 | [diff] [blame] | 1265 | BasicBlock *LatchBlock = L->getLoopLatch(); |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1266 | |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1267 | |
| 1268 | // Emit the initial base value into the loop preheader. |
| 1269 | Value *CommonBaseV |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 1270 | = PreheaderRewriter.expandCodeFor(CommonExprs, PreInsertPt); |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1271 | |
Evan Cheng | 2149577 | 2006-03-18 08:03:12 +0000 | [diff] [blame] | 1272 | if (RewriteFactor == 0) { |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1273 | // Create a new Phi for this base, and stick it in the loop header. |
| 1274 | NewPHI = new PHINode(ReplacedTy, "iv.", PhiInsertBefore); |
| 1275 | ++NumInserted; |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1276 | |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1277 | // Add common base to the new Phi node. |
| 1278 | NewPHI->addIncoming(CommonBaseV, Preheader); |
| 1279 | |
Chris Lattner | fb3e119 | 2007-05-19 01:22:21 +0000 | [diff] [blame] | 1280 | // If the stride is negative, insert a sub instead of an add for the |
| 1281 | // increment. |
| 1282 | bool isNegative = isNonConstantNegative(Stride); |
| 1283 | SCEVHandle IncAmount = Stride; |
| 1284 | if (isNegative) |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1285 | IncAmount = SE->getNegativeSCEV(Stride); |
Chris Lattner | fb3e119 | 2007-05-19 01:22:21 +0000 | [diff] [blame] | 1286 | |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1287 | // Insert the stride into the preheader. |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 1288 | Value *StrideV = PreheaderRewriter.expandCodeFor(IncAmount, PreInsertPt); |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1289 | if (!isa<ConstantInt>(StrideV)) ++NumVariable; |
Chris Lattner | 50fad70 | 2005-08-10 00:45:21 +0000 | [diff] [blame] | 1290 | |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1291 | // Emit the increment of the base value before the terminator of the loop |
| 1292 | // latch block, and add it to the Phi node. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1293 | SCEVHandle IncExp = SE->getUnknown(StrideV); |
Chris Lattner | fb3e119 | 2007-05-19 01:22:21 +0000 | [diff] [blame] | 1294 | if (isNegative) |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1295 | IncExp = SE->getNegativeSCEV(IncExp); |
| 1296 | IncExp = SE->getAddExpr(SE->getUnknown(NewPHI), IncExp); |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1297 | |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 1298 | IncV = Rewriter.expandCodeFor(IncExp, LatchBlock->getTerminator()); |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1299 | IncV->setName(NewPHI->getName()+".inc"); |
| 1300 | NewPHI->addIncoming(IncV, LatchBlock); |
| 1301 | |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1302 | // Remember this in case a later stride is multiple of this. |
Evan Cheng | 2149577 | 2006-03-18 08:03:12 +0000 | [diff] [blame] | 1303 | IVsByStride[Stride].addIV(Stride, CommonExprs, NewPHI, IncV); |
Chris Lattner | 7d8ed8a | 2007-05-11 22:40:34 +0000 | [diff] [blame] | 1304 | |
| 1305 | DOUT << " IV=%" << NewPHI->getNameStr() << " INC=%" << IncV->getNameStr(); |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1306 | } else { |
| 1307 | Constant *C = dyn_cast<Constant>(CommonBaseV); |
| 1308 | if (!C || |
| 1309 | (!C->isNullValue() && |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1310 | !isTargetConstant(SE->getUnknown(CommonBaseV), ReplacedTy, TLI))) |
Reid Spencer | 3da59db | 2006-11-27 01:05:10 +0000 | [diff] [blame] | 1311 | // We want the common base emitted into the preheader! This is just |
| 1312 | // using cast as a copy so BitCast (no-op cast) is appropriate |
| 1313 | CommonBaseV = new BitCastInst(CommonBaseV, CommonBaseV->getType(), |
| 1314 | "commonbase", PreInsertPt); |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1315 | } |
Chris Lattner | 7d8ed8a | 2007-05-11 22:40:34 +0000 | [diff] [blame] | 1316 | DOUT << "\n"; |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1317 | |
Chris Lattner | 7e79b38 | 2006-08-03 06:34:50 +0000 | [diff] [blame] | 1318 | // We want to emit code for users inside the loop first. To do this, we |
| 1319 | // rearrange BasedUser so that the entries at the end have |
| 1320 | // isUseOfPostIncrementedValue = false, because we pop off the end of the |
| 1321 | // vector (so we handle them first). |
| 1322 | std::partition(UsersToProcess.begin(), UsersToProcess.end(), |
| 1323 | PartitionByIsUseOfPostIncrementedValue); |
| 1324 | |
| 1325 | // Sort this by base, so that things with the same base are handled |
| 1326 | // together. By partitioning first and stable-sorting later, we are |
| 1327 | // guaranteed that within each base we will pop off users from within the |
| 1328 | // loop before users outside of the loop with a particular base. |
| 1329 | // |
| 1330 | // We would like to use stable_sort here, but we can't. The problem is that |
| 1331 | // SCEVHandle's don't have a deterministic ordering w.r.t to each other, so |
| 1332 | // we don't have anything to do a '<' comparison on. Because we think the |
| 1333 | // number of uses is small, do a horrible bubble sort which just relies on |
| 1334 | // ==. |
| 1335 | for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i) { |
| 1336 | // Get a base value. |
| 1337 | SCEVHandle Base = UsersToProcess[i].Base; |
| 1338 | |
Evan Cheng | 8392772 | 2007-10-30 22:27:26 +0000 | [diff] [blame] | 1339 | // Compact everything with this base to be consequtive with this one. |
Chris Lattner | 7e79b38 | 2006-08-03 06:34:50 +0000 | [diff] [blame] | 1340 | for (unsigned j = i+1; j != e; ++j) { |
| 1341 | if (UsersToProcess[j].Base == Base) { |
| 1342 | std::swap(UsersToProcess[i+1], UsersToProcess[j]); |
| 1343 | ++i; |
| 1344 | } |
| 1345 | } |
| 1346 | } |
| 1347 | |
| 1348 | // Process all the users now. This outer loop handles all bases, the inner |
| 1349 | // loop handles all users of a particular base. |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1350 | while (!UsersToProcess.empty()) { |
Chris Lattner | 7b445c5 | 2005-10-11 18:30:57 +0000 | [diff] [blame] | 1351 | SCEVHandle Base = UsersToProcess.back().Base; |
Chris Lattner | be3e521 | 2005-08-03 23:30:08 +0000 | [diff] [blame] | 1352 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1353 | // Emit the code for Base into the preheader. |
Dan Gohman | d19534a | 2007-06-15 14:38:12 +0000 | [diff] [blame] | 1354 | Value *BaseV = PreheaderRewriter.expandCodeFor(Base, PreInsertPt); |
Chris Lattner | 7d8ed8a | 2007-05-11 22:40:34 +0000 | [diff] [blame] | 1355 | |
| 1356 | DOUT << " INSERTING code for BASE = " << *Base << ":"; |
| 1357 | if (BaseV->hasName()) |
| 1358 | DOUT << " Result value name = %" << BaseV->getNameStr(); |
| 1359 | DOUT << "\n"; |
| 1360 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1361 | // If BaseV is a constant other than 0, make sure that it gets inserted into |
| 1362 | // the preheader, instead of being forward substituted into the uses. We do |
Reid Spencer | 3da59db | 2006-11-27 01:05:10 +0000 | [diff] [blame] | 1363 | // this by forcing a BitCast (noop cast) to be inserted into the preheader |
| 1364 | // in this case. |
Chris Lattner | 7e79b38 | 2006-08-03 06:34:50 +0000 | [diff] [blame] | 1365 | if (Constant *C = dyn_cast<Constant>(BaseV)) { |
Evan Cheng | 1d95816 | 2007-03-13 20:34:37 +0000 | [diff] [blame] | 1366 | if (!C->isNullValue() && !isTargetConstant(Base, ReplacedTy, TLI)) { |
Reid Spencer | 3da59db | 2006-11-27 01:05:10 +0000 | [diff] [blame] | 1367 | // We want this constant emitted into the preheader! This is just |
| 1368 | // using cast as a copy so BitCast (no-op cast) is appropriate |
| 1369 | BaseV = new BitCastInst(BaseV, BaseV->getType(), "preheaderinsert", |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1370 | PreInsertPt); |
| 1371 | } |
Chris Lattner | 7e79b38 | 2006-08-03 06:34:50 +0000 | [diff] [blame] | 1372 | } |
| 1373 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1374 | // Emit the code to add the immediate offset to the Phi value, just before |
Chris Lattner | 2351aba | 2005-08-03 22:51:21 +0000 | [diff] [blame] | 1375 | // the instructions that we identified as using this stride and base. |
Chris Lattner | 7b445c5 | 2005-10-11 18:30:57 +0000 | [diff] [blame] | 1376 | do { |
Chris Lattner | 7e79b38 | 2006-08-03 06:34:50 +0000 | [diff] [blame] | 1377 | // FIXME: Use emitted users to emit other users. |
Chris Lattner | 7b445c5 | 2005-10-11 18:30:57 +0000 | [diff] [blame] | 1378 | BasedUser &User = UsersToProcess.back(); |
Jeff Cohen | d29b6aa | 2005-07-30 18:33:25 +0000 | [diff] [blame] | 1379 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1380 | // If this instruction wants to use the post-incremented value, move it |
| 1381 | // after the post-inc and use its value instead of the PHI. |
| 1382 | Value *RewriteOp = NewPHI; |
| 1383 | if (User.isUseOfPostIncrementedValue) { |
| 1384 | RewriteOp = IncV; |
Chris Lattner | c6bae65 | 2005-09-12 06:04:47 +0000 | [diff] [blame] | 1385 | |
| 1386 | // If this user is in the loop, make sure it is the last thing in the |
| 1387 | // loop to ensure it is dominated by the increment. |
| 1388 | if (L->contains(User.Inst->getParent())) |
| 1389 | User.Inst->moveBefore(LatchBlock->getTerminator()); |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1390 | } |
Reid Spencer | 3ba68b9 | 2006-12-13 08:06:42 +0000 | [diff] [blame] | 1391 | if (RewriteOp->getType() != ReplacedTy) { |
| 1392 | Instruction::CastOps opcode = Instruction::Trunc; |
| 1393 | if (ReplacedTy->getPrimitiveSizeInBits() == |
| 1394 | RewriteOp->getType()->getPrimitiveSizeInBits()) |
| 1395 | opcode = Instruction::BitCast; |
| 1396 | RewriteOp = SCEVExpander::InsertCastOfTo(opcode, RewriteOp, ReplacedTy); |
| 1397 | } |
Evan Cheng | 86c75d3 | 2006-06-09 00:12:42 +0000 | [diff] [blame] | 1398 | |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1399 | SCEVHandle RewriteExpr = SE->getUnknown(RewriteOp); |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1400 | |
Chris Lattner | 2351aba | 2005-08-03 22:51:21 +0000 | [diff] [blame] | 1401 | // Clear the SCEVExpander's expression map so that we are guaranteed |
| 1402 | // to have the code emitted where we expect it. |
| 1403 | Rewriter.clear(); |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1404 | |
| 1405 | // If we are reusing the iv, then it must be multiplied by a constant |
| 1406 | // factor take advantage of addressing mode scale component. |
Evan Cheng | 2149577 | 2006-03-18 08:03:12 +0000 | [diff] [blame] | 1407 | if (RewriteFactor != 0) { |
Evan Cheng | 8392772 | 2007-10-30 22:27:26 +0000 | [diff] [blame] | 1408 | RewriteExpr = SE->getMulExpr(SE->getIntegerSCEV(RewriteFactor, |
| 1409 | RewriteExpr->getType()), |
| 1410 | RewriteExpr); |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1411 | |
| 1412 | // The common base is emitted in the loop preheader. But since we |
| 1413 | // are reusing an IV, it has not been used to initialize the PHI node. |
| 1414 | // Add it to the expression used to rewrite the uses. |
| 1415 | if (!isa<ConstantInt>(CommonBaseV) || |
Reid Spencer | bee0f66 | 2007-03-02 23:51:25 +0000 | [diff] [blame] | 1416 | !cast<ConstantInt>(CommonBaseV)->isZero()) |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1417 | RewriteExpr = SE->getAddExpr(RewriteExpr, |
| 1418 | SE->getUnknown(CommonBaseV)); |
Evan Cheng | eb8f9e2 | 2006-03-17 19:52:23 +0000 | [diff] [blame] | 1419 | } |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1420 | |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 1421 | // Now that we know what we need to do, insert code before User for the |
| 1422 | // immediate and any loop-variant expressions. |
Reid Spencer | bee0f66 | 2007-03-02 23:51:25 +0000 | [diff] [blame] | 1423 | if (!isa<ConstantInt>(BaseV) || !cast<ConstantInt>(BaseV)->isZero()) |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1424 | // Add BaseV to the PHI value if needed. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1425 | RewriteExpr = SE->getAddExpr(RewriteExpr, SE->getUnknown(BaseV)); |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1426 | |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 1427 | User.RewriteInstructionToUseNewBase(RewriteExpr, Rewriter, L, this, |
| 1428 | DeadInsts); |
Jeff Cohen | d29b6aa | 2005-07-30 18:33:25 +0000 | [diff] [blame] | 1429 | |
Chris Lattner | 2351aba | 2005-08-03 22:51:21 +0000 | [diff] [blame] | 1430 | // Mark old value we replaced as possibly dead, so that it is elminated |
| 1431 | // if we just replaced the last use of that value. |
Chris Lattner | 2114b27 | 2005-08-04 20:03:32 +0000 | [diff] [blame] | 1432 | DeadInsts.insert(cast<Instruction>(User.OperandValToReplace)); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1433 | |
Chris Lattner | 7b445c5 | 2005-10-11 18:30:57 +0000 | [diff] [blame] | 1434 | UsersToProcess.pop_back(); |
Chris Lattner | 2351aba | 2005-08-03 22:51:21 +0000 | [diff] [blame] | 1435 | ++NumReduced; |
Chris Lattner | 7b445c5 | 2005-10-11 18:30:57 +0000 | [diff] [blame] | 1436 | |
Chris Lattner | 7e79b38 | 2006-08-03 06:34:50 +0000 | [diff] [blame] | 1437 | // If there are any more users to process with the same base, process them |
| 1438 | // now. We sorted by base above, so we just have to check the last elt. |
Chris Lattner | 7b445c5 | 2005-10-11 18:30:57 +0000 | [diff] [blame] | 1439 | } while (!UsersToProcess.empty() && UsersToProcess.back().Base == Base); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1440 | // TODO: Next, find out which base index is the most common, pull it out. |
| 1441 | } |
| 1442 | |
| 1443 | // IMPORTANT TODO: Figure out how to partition the IV's with this stride, but |
| 1444 | // different starting values, into different PHIs. |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1445 | } |
| 1446 | |
Chris Lattner | aed01d1 | 2007-04-03 05:11:24 +0000 | [diff] [blame] | 1447 | /// FindIVForUser - If Cond has an operand that is an expression of an IV, |
| 1448 | /// set the IV user and stride information and return true, otherwise return |
| 1449 | /// false. |
| 1450 | bool LoopStrengthReduce::FindIVForUser(ICmpInst *Cond, IVStrideUse *&CondUse, |
| 1451 | const SCEVHandle *&CondStride) { |
| 1452 | for (unsigned Stride = 0, e = StrideOrder.size(); Stride != e && !CondUse; |
| 1453 | ++Stride) { |
| 1454 | std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI = |
| 1455 | IVUsesByStride.find(StrideOrder[Stride]); |
| 1456 | assert(SI != IVUsesByStride.end() && "Stride doesn't exist!"); |
| 1457 | |
| 1458 | for (std::vector<IVStrideUse>::iterator UI = SI->second.Users.begin(), |
| 1459 | E = SI->second.Users.end(); UI != E; ++UI) |
| 1460 | if (UI->User == Cond) { |
| 1461 | // NOTE: we could handle setcc instructions with multiple uses here, but |
| 1462 | // InstCombine does it as well for simple uses, it's not clear that it |
| 1463 | // occurs enough in real life to handle. |
| 1464 | CondUse = &*UI; |
| 1465 | CondStride = &SI->first; |
| 1466 | return true; |
| 1467 | } |
| 1468 | } |
| 1469 | return false; |
| 1470 | } |
| 1471 | |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1472 | namespace { |
| 1473 | // Constant strides come first which in turns are sorted by their absolute |
| 1474 | // values. If absolute values are the same, then positive strides comes first. |
| 1475 | // e.g. |
| 1476 | // 4, -1, X, 1, 2 ==> 1, -1, 2, 4, X |
| 1477 | struct StrideCompare { |
| 1478 | bool operator()(const SCEVHandle &LHS, const SCEVHandle &RHS) { |
| 1479 | SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS); |
| 1480 | SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS); |
| 1481 | if (LHSC && RHSC) { |
| 1482 | int64_t LV = LHSC->getValue()->getSExtValue(); |
| 1483 | int64_t RV = RHSC->getValue()->getSExtValue(); |
| 1484 | uint64_t ALV = (LV < 0) ? -LV : LV; |
| 1485 | uint64_t ARV = (RV < 0) ? -RV : RV; |
| 1486 | if (ALV == ARV) |
| 1487 | return LV > RV; |
| 1488 | else |
| 1489 | return ALV < ARV; |
| 1490 | } |
| 1491 | return (LHSC && !RHSC); |
| 1492 | } |
| 1493 | }; |
| 1494 | } |
| 1495 | |
| 1496 | /// ChangeCompareStride - If a loop termination compare instruction is the |
| 1497 | /// only use of its stride, and the compaison is against a constant value, |
| 1498 | /// try eliminate the stride by moving the compare instruction to another |
| 1499 | /// stride and change its constant operand accordingly. e.g. |
| 1500 | /// |
| 1501 | /// loop: |
| 1502 | /// ... |
| 1503 | /// v1 = v1 + 3 |
| 1504 | /// v2 = v2 + 1 |
| 1505 | /// if (v2 < 10) goto loop |
| 1506 | /// => |
| 1507 | /// loop: |
| 1508 | /// ... |
| 1509 | /// v1 = v1 + 3 |
| 1510 | /// if (v1 < 30) goto loop |
| 1511 | ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond, |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 1512 | IVStrideUse* &CondUse, |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1513 | const SCEVHandle* &CondStride) { |
| 1514 | if (StrideOrder.size() < 2 || |
| 1515 | IVUsesByStride[*CondStride].Users.size() != 1) |
| 1516 | return Cond; |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1517 | const SCEVConstant *SC = dyn_cast<SCEVConstant>(*CondStride); |
| 1518 | if (!SC) return Cond; |
| 1519 | ConstantInt *C = dyn_cast<ConstantInt>(Cond->getOperand(1)); |
| 1520 | if (!C) return Cond; |
| 1521 | |
| 1522 | ICmpInst::Predicate Predicate = Cond->getPredicate(); |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1523 | int64_t CmpSSInt = SC->getValue()->getSExtValue(); |
| 1524 | int64_t CmpVal = C->getValue().getSExtValue(); |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1525 | unsigned BitWidth = C->getValue().getBitWidth(); |
| 1526 | uint64_t SignBit = 1ULL << (BitWidth-1); |
| 1527 | const Type *CmpTy = C->getType(); |
| 1528 | const Type *NewCmpTy = NULL; |
Evan Cheng | af62c09 | 2007-10-29 22:07:18 +0000 | [diff] [blame] | 1529 | unsigned TyBits = CmpTy->getPrimitiveSizeInBits(); |
| 1530 | unsigned NewTyBits = 0; |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1531 | int64_t NewCmpVal = CmpVal; |
| 1532 | SCEVHandle *NewStride = NULL; |
| 1533 | Value *NewIncV = NULL; |
| 1534 | int64_t Scale = 1; |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1535 | |
| 1536 | // Look for a suitable stride / iv as replacement. |
| 1537 | std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare()); |
| 1538 | for (unsigned i = 0, e = StrideOrder.size(); i != e; ++i) { |
| 1539 | std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI = |
| 1540 | IVUsesByStride.find(StrideOrder[i]); |
| 1541 | if (!isa<SCEVConstant>(SI->first)) |
| 1542 | continue; |
| 1543 | int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue(); |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1544 | if (abs(SSInt) <= abs(CmpSSInt) || (SSInt % CmpSSInt) != 0) |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1545 | continue; |
| 1546 | |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1547 | Scale = SSInt / CmpSSInt; |
| 1548 | NewCmpVal = CmpVal * Scale; |
| 1549 | APInt Mul = APInt(BitWidth, NewCmpVal); |
| 1550 | // Check for overflow. |
| 1551 | if (Mul.getSExtValue() != NewCmpVal) { |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1552 | NewCmpVal = CmpVal; |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1553 | continue; |
| 1554 | } |
| 1555 | |
| 1556 | // Watch out for overflow. |
| 1557 | if (ICmpInst::isSignedPredicate(Predicate) && |
| 1558 | (CmpVal & SignBit) != (NewCmpVal & SignBit)) |
| 1559 | NewCmpVal = CmpVal; |
| 1560 | |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1561 | if (NewCmpVal != CmpVal) { |
| 1562 | // Pick the best iv to use trying to avoid a cast. |
| 1563 | NewIncV = NULL; |
| 1564 | for (std::vector<IVStrideUse>::iterator UI = SI->second.Users.begin(), |
| 1565 | E = SI->second.Users.end(); UI != E; ++UI) { |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1566 | NewIncV = UI->OperandValToReplace; |
| 1567 | if (NewIncV->getType() == CmpTy) |
| 1568 | break; |
| 1569 | } |
| 1570 | if (!NewIncV) { |
| 1571 | NewCmpVal = CmpVal; |
| 1572 | continue; |
| 1573 | } |
| 1574 | |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1575 | NewCmpTy = NewIncV->getType(); |
Evan Cheng | af62c09 | 2007-10-29 22:07:18 +0000 | [diff] [blame] | 1576 | NewTyBits = isa<PointerType>(NewCmpTy) |
| 1577 | ? UIntPtrTy->getPrimitiveSizeInBits() |
| 1578 | : NewCmpTy->getPrimitiveSizeInBits(); |
| 1579 | if (RequiresTypeConversion(NewCmpTy, CmpTy)) { |
| 1580 | // Check if it is possible to rewrite it using a iv / stride of a smaller |
| 1581 | // integer type. |
| 1582 | bool TruncOk = false; |
| 1583 | if (NewCmpTy->isInteger()) { |
| 1584 | unsigned Bits = NewTyBits; |
| 1585 | if (ICmpInst::isSignedPredicate(Predicate)) |
| 1586 | --Bits; |
| 1587 | uint64_t Mask = (1ULL << Bits) - 1; |
| 1588 | if (((uint64_t)NewCmpVal & Mask) == (uint64_t)NewCmpVal) |
| 1589 | TruncOk = true; |
| 1590 | } |
| 1591 | if (!TruncOk) { |
| 1592 | NewCmpVal = CmpVal; |
| 1593 | continue; |
| 1594 | } |
| 1595 | } |
| 1596 | |
| 1597 | // Don't rewrite if use offset is non-constant and the new type is |
| 1598 | // of a different type. |
| 1599 | // FIXME: too conservative? |
| 1600 | if (NewTyBits != TyBits && !isa<SCEVConstant>(CondUse->Offset)) { |
Evan Cheng | 5f8ebaa | 2007-10-25 22:45:20 +0000 | [diff] [blame] | 1601 | NewCmpVal = CmpVal; |
| 1602 | continue; |
| 1603 | } |
| 1604 | |
| 1605 | bool AllUsesAreAddresses = true; |
| 1606 | std::vector<BasedUser> UsersToProcess; |
| 1607 | SCEVHandle CommonExprs = CollectIVUsers(SI->first, SI->second, L, |
| 1608 | AllUsesAreAddresses, |
| 1609 | UsersToProcess); |
| 1610 | // Avoid rewriting the compare instruction with an iv of new stride |
| 1611 | // if it's likely the new stride uses will be rewritten using the |
| 1612 | if (AllUsesAreAddresses && |
| 1613 | ValidStride(!isZero(CommonExprs), Scale, UsersToProcess)) { |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1614 | NewCmpVal = CmpVal; |
| 1615 | continue; |
| 1616 | } |
| 1617 | |
| 1618 | // If scale is negative, use inverse predicate unless it's testing |
| 1619 | // for equality. |
| 1620 | if (Scale < 0 && !Cond->isEquality()) |
| 1621 | Predicate = ICmpInst::getInversePredicate(Predicate); |
| 1622 | |
| 1623 | NewStride = &StrideOrder[i]; |
| 1624 | break; |
| 1625 | } |
| 1626 | } |
| 1627 | |
| 1628 | if (NewCmpVal != CmpVal) { |
| 1629 | // Create a new compare instruction using new stride / iv. |
| 1630 | ICmpInst *OldCond = Cond; |
Evan Cheng | af62c09 | 2007-10-29 22:07:18 +0000 | [diff] [blame] | 1631 | Value *RHS; |
| 1632 | if (!isa<PointerType>(NewCmpTy)) |
| 1633 | RHS = ConstantInt::get(NewCmpTy, NewCmpVal); |
| 1634 | else { |
| 1635 | RHS = ConstantInt::get(UIntPtrTy, NewCmpVal); |
| 1636 | RHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr, RHS, NewCmpTy); |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1637 | } |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1638 | // Insert new compare instruction. |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1639 | Cond = new ICmpInst(Predicate, NewIncV, RHS); |
| 1640 | Cond->setName(L->getHeader()->getName() + ".termcond"); |
| 1641 | OldCond->getParent()->getInstList().insert(OldCond, Cond); |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1642 | |
| 1643 | // Remove the old compare instruction. The old indvar is probably dead too. |
| 1644 | DeadInsts.insert(cast<Instruction>(CondUse->OperandValToReplace)); |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1645 | OldCond->replaceAllUsesWith(Cond); |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1646 | SE->deleteValueFromRecords(OldCond); |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1647 | OldCond->eraseFromParent(); |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1648 | |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1649 | IVUsesByStride[*CondStride].Users.pop_back(); |
Evan Cheng | af62c09 | 2007-10-29 22:07:18 +0000 | [diff] [blame] | 1650 | SCEVHandle NewOffset = TyBits == NewTyBits |
| 1651 | ? SE->getMulExpr(CondUse->Offset, |
| 1652 | SE->getConstant(ConstantInt::get(CmpTy, Scale))) |
| 1653 | : SE->getConstant(ConstantInt::get(NewCmpTy, |
| 1654 | cast<SCEVConstant>(CondUse->Offset)->getValue()->getSExtValue()*Scale)); |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1655 | IVUsesByStride[*NewStride].addUser(NewOffset, Cond, NewIncV); |
| 1656 | CondUse = &IVUsesByStride[*NewStride].Users.back(); |
| 1657 | CondStride = NewStride; |
| 1658 | ++NumEliminated; |
| 1659 | } |
| 1660 | |
| 1661 | return Cond; |
| 1662 | } |
| 1663 | |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1664 | // OptimizeIndvars - Now that IVUsesByStride is set up with all of the indvar |
| 1665 | // uses in the loop, look to see if we can eliminate some, in favor of using |
| 1666 | // common indvars for the different uses. |
| 1667 | void LoopStrengthReduce::OptimizeIndvars(Loop *L) { |
| 1668 | // TODO: implement optzns here. |
| 1669 | |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1670 | // Finally, get the terminating condition for the loop if possible. If we |
| 1671 | // can, we want to change it to use a post-incremented version of its |
Chris Lattner | 98d9811 | 2006-03-24 07:14:34 +0000 | [diff] [blame] | 1672 | // induction variable, to allow coalescing the live ranges for the IV into |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1673 | // one register value. |
| 1674 | PHINode *SomePHI = cast<PHINode>(L->getHeader()->begin()); |
| 1675 | BasicBlock *Preheader = L->getLoopPreheader(); |
| 1676 | BasicBlock *LatchBlock = |
| 1677 | SomePHI->getIncomingBlock(SomePHI->getIncomingBlock(0) == Preheader); |
| 1678 | BranchInst *TermBr = dyn_cast<BranchInst>(LatchBlock->getTerminator()); |
Reid Spencer | e4d87aa | 2006-12-23 06:05:41 +0000 | [diff] [blame] | 1679 | if (!TermBr || TermBr->isUnconditional() || |
| 1680 | !isa<ICmpInst>(TermBr->getCondition())) |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1681 | return; |
Reid Spencer | e4d87aa | 2006-12-23 06:05:41 +0000 | [diff] [blame] | 1682 | ICmpInst *Cond = cast<ICmpInst>(TermBr->getCondition()); |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1683 | |
| 1684 | // Search IVUsesByStride to find Cond's IVUse if there is one. |
| 1685 | IVStrideUse *CondUse = 0; |
Chris Lattner | 50fad70 | 2005-08-10 00:45:21 +0000 | [diff] [blame] | 1686 | const SCEVHandle *CondStride = 0; |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1687 | |
Chris Lattner | aed01d1 | 2007-04-03 05:11:24 +0000 | [diff] [blame] | 1688 | if (!FindIVForUser(Cond, CondUse, CondStride)) |
| 1689 | return; // setcc doesn't use the IV. |
Evan Cheng | cdf43b1 | 2007-10-25 09:11:16 +0000 | [diff] [blame] | 1690 | |
| 1691 | // If possible, change stride and operands of the compare instruction to |
| 1692 | // eliminate one stride. |
| 1693 | Cond = ChangeCompareStride(L, Cond, CondUse, CondStride); |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1694 | |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1695 | // It's possible for the setcc instruction to be anywhere in the loop, and |
| 1696 | // possible for it to have multiple users. If it is not immediately before |
| 1697 | // the latch block branch, move it. |
| 1698 | if (&*++BasicBlock::iterator(Cond) != (Instruction*)TermBr) { |
| 1699 | if (Cond->hasOneUse()) { // Condition has a single use, just move it. |
| 1700 | Cond->moveBefore(TermBr); |
| 1701 | } else { |
| 1702 | // Otherwise, clone the terminating condition and insert into the loopend. |
Reid Spencer | e4d87aa | 2006-12-23 06:05:41 +0000 | [diff] [blame] | 1703 | Cond = cast<ICmpInst>(Cond->clone()); |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1704 | Cond->setName(L->getHeader()->getName() + ".termcond"); |
| 1705 | LatchBlock->getInstList().insert(TermBr, Cond); |
| 1706 | |
| 1707 | // Clone the IVUse, as the old use still exists! |
Chris Lattner | 50fad70 | 2005-08-10 00:45:21 +0000 | [diff] [blame] | 1708 | IVUsesByStride[*CondStride].addUser(CondUse->Offset, Cond, |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1709 | CondUse->OperandValToReplace); |
Chris Lattner | 50fad70 | 2005-08-10 00:45:21 +0000 | [diff] [blame] | 1710 | CondUse = &IVUsesByStride[*CondStride].Users.back(); |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1711 | } |
| 1712 | } |
| 1713 | |
| 1714 | // If we get to here, we know that we can transform the setcc instruction to |
Chris Lattner | 98d9811 | 2006-03-24 07:14:34 +0000 | [diff] [blame] | 1715 | // use the post-incremented version of the IV, allowing us to coalesce the |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1716 | // live ranges for the IV correctly. |
Dan Gohman | 246b256 | 2007-10-22 18:31:58 +0000 | [diff] [blame] | 1717 | CondUse->Offset = SE->getMinusSCEV(CondUse->Offset, *CondStride); |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1718 | CondUse->isUseOfPostIncrementedValue = true; |
| 1719 | } |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1720 | |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 1721 | bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager &LPM) { |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 1722 | |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 1723 | LI = &getAnalysis<LoopInfo>(); |
Devang Patel | b7d9dfc | 2007-06-07 21:42:15 +0000 | [diff] [blame] | 1724 | DT = &getAnalysis<DominatorTree>(); |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 1725 | SE = &getAnalysis<ScalarEvolution>(); |
| 1726 | TD = &getAnalysis<TargetData>(); |
| 1727 | UIntPtrTy = TD->getIntPtrType(); |
| 1728 | |
| 1729 | // Find all uses of induction variables in this loop, and catagorize |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1730 | // them by stride. Start by finding all of the PHI nodes in the header for |
| 1731 | // this loop. If they are induction variables, inspect their uses. |
Evan Cheng | 168a66b | 2007-10-26 23:08:19 +0000 | [diff] [blame] | 1732 | SmallPtrSet<Instruction*,16> Processed; // Don't reprocess instructions. |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1733 | for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) |
Chris Lattner | 3416e5f | 2005-08-04 17:40:30 +0000 | [diff] [blame] | 1734 | AddUsersIfInteresting(I, L, Processed); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 1735 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1736 | // If we have nothing to do, return. |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 1737 | if (IVUsesByStride.empty()) return false; |
Chris Lattner | 010de25 | 2005-08-08 05:28:22 +0000 | [diff] [blame] | 1738 | |
| 1739 | // Optimize induction variables. Some indvar uses can be transformed to use |
| 1740 | // strides that will be needed for other purposes. A common example of this |
| 1741 | // is the exit test for the loop, which can often be rewritten to use the |
| 1742 | // computation of some other indvar to decide when to terminate the loop. |
| 1743 | OptimizeIndvars(L); |
| 1744 | |
Misha Brukman | fd93908 | 2005-04-21 23:48:37 +0000 | [diff] [blame] | 1745 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1746 | // FIXME: We can widen subreg IV's here for RISC targets. e.g. instead of |
| 1747 | // doing computation in byte values, promote to 32-bit values if safe. |
| 1748 | |
| 1749 | // FIXME: Attempt to reuse values across multiple IV's. In particular, we |
| 1750 | // could have something like "for(i) { foo(i*8); bar(i*16) }", which should be |
| 1751 | // codegened as "for (j = 0;; j+=8) { foo(j); bar(j+j); }" on X86/PPC. Need |
| 1752 | // to be careful that IV's are all the same type. Only works for intptr_t |
| 1753 | // indvars. |
| 1754 | |
| 1755 | // If we only have one stride, we can more aggressively eliminate some things. |
| 1756 | bool HasOneStride = IVUsesByStride.size() == 1; |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1757 | |
| 1758 | #ifndef NDEBUG |
Bill Wendling | b742703 | 2006-11-26 09:46:52 +0000 | [diff] [blame] | 1759 | DOUT << "\nLSR on "; |
Evan Cheng | d1d6b5c | 2006-03-16 21:53:05 +0000 | [diff] [blame] | 1760 | DEBUG(L->dump()); |
| 1761 | #endif |
| 1762 | |
| 1763 | // IVsByStride keeps IVs for one particular loop. |
| 1764 | IVsByStride.clear(); |
| 1765 | |
Evan Cheng | 4496a50 | 2006-03-18 00:44:49 +0000 | [diff] [blame] | 1766 | // Sort the StrideOrder so we process larger strides first. |
| 1767 | std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare()); |
| 1768 | |
Chris Lattner | 1bbae0c | 2005-08-09 00:18:09 +0000 | [diff] [blame] | 1769 | // Note: this processes each stride/type pair individually. All users passed |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 1770 | // into StrengthReduceStridedIVUsers have the same type AND stride. Also, |
Dan Gohman | b66cf43 | 2007-10-29 19:26:14 +0000 | [diff] [blame] | 1771 | // note that we iterate over IVUsesByStride indirectly by using StrideOrder. |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 1772 | // This extra layer of indirection makes the ordering of strides deterministic |
| 1773 | // - not dependent on map order. |
| 1774 | for (unsigned Stride = 0, e = StrideOrder.size(); Stride != e; ++Stride) { |
| 1775 | std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI = |
| 1776 | IVUsesByStride.find(StrideOrder[Stride]); |
| 1777 | assert(SI != IVUsesByStride.end() && "Stride doesn't exist!"); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1778 | StrengthReduceStridedIVUsers(SI->first, SI->second, L, HasOneStride); |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 1779 | } |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 1780 | |
| 1781 | // Clean up after ourselves |
| 1782 | if (!DeadInsts.empty()) { |
| 1783 | DeleteTriviallyDeadInstructions(DeadInsts); |
| 1784 | |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1785 | BasicBlock::iterator I = L->getHeader()->begin(); |
| 1786 | PHINode *PN; |
Chris Lattner | e9100c6 | 2005-08-02 02:44:31 +0000 | [diff] [blame] | 1787 | while ((PN = dyn_cast<PHINode>(I))) { |
Chris Lattner | 1060e09 | 2005-08-02 00:41:11 +0000 | [diff] [blame] | 1788 | ++I; // Preincrement iterator to avoid invalidating it when deleting PN. |
Evan Cheng | 0e0014d | 2007-10-30 23:45:15 +0000 | [diff] [blame] | 1789 | |
Chris Lattner | 87265ab | 2005-08-09 23:39:36 +0000 | [diff] [blame] | 1790 | // At this point, we know that we have killed one or more GEP |
| 1791 | // instructions. It is worth checking to see if the cann indvar is also |
| 1792 | // dead, so that we can remove it as well. The requirements for the cann |
| 1793 | // indvar to be considered dead are: |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1794 | // 1. the cann indvar has one use |
| 1795 | // 2. the use is an add instruction |
| 1796 | // 3. the add has one use |
| 1797 | // 4. the add is used by the cann indvar |
| 1798 | // If all four cases above are true, then we can remove both the add and |
| 1799 | // the cann indvar. |
| 1800 | // FIXME: this needs to eliminate an induction variable even if it's being |
| 1801 | // compared against some value to decide loop termination. |
| 1802 | if (PN->hasOneUse()) { |
Reid Spencer | e4d87aa | 2006-12-23 06:05:41 +0000 | [diff] [blame] | 1803 | Instruction *BO = dyn_cast<Instruction>(*PN->use_begin()); |
| 1804 | if (BO && (isa<BinaryOperator>(BO) || isa<CmpInst>(BO))) { |
| 1805 | if (BO->hasOneUse() && PN == *(BO->use_begin())) { |
Chris Lattner | 7e608bb | 2005-08-02 02:52:02 +0000 | [diff] [blame] | 1806 | DeadInsts.insert(BO); |
| 1807 | // Break the cycle, then delete the PHI. |
| 1808 | PN->replaceAllUsesWith(UndefValue::get(PN->getType())); |
Dan Gohman | 5cec4db | 2007-06-19 14:28:31 +0000 | [diff] [blame] | 1809 | SE->deleteValueFromRecords(PN); |
Chris Lattner | 7e608bb | 2005-08-02 02:52:02 +0000 | [diff] [blame] | 1810 | PN->eraseFromParent(); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 1811 | } |
Chris Lattner | 7e608bb | 2005-08-02 02:52:02 +0000 | [diff] [blame] | 1812 | } |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1813 | } |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 1814 | } |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1815 | DeleteTriviallyDeadInstructions(DeadInsts); |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 1816 | } |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1817 | |
Chris Lattner | 9a59fbb | 2005-08-05 01:30:11 +0000 | [diff] [blame] | 1818 | CastedPointers.clear(); |
Nate Begeman | 1699748 | 2005-07-30 00:15:07 +0000 | [diff] [blame] | 1819 | IVUsesByStride.clear(); |
Chris Lattner | 7305ae2 | 2005-10-09 06:20:55 +0000 | [diff] [blame] | 1820 | StrideOrder.clear(); |
Devang Patel | 0f54dcb | 2007-03-06 21:14:09 +0000 | [diff] [blame] | 1821 | return false; |
Nate Begeman | eaa1385 | 2004-10-18 21:08:22 +0000 | [diff] [blame] | 1822 | } |