1//===---- Delinearization.cpp - MultiDimensional Index Delinearization ----===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This implements an analysis pass that tries to delinearize all GEP 11// instructions in all loops using the SCEV analysis functionality. This pass is 12// only used for testing purposes: if your pass needs delinearization, please 13// use the on-demand SCEVAddRecExpr::delinearize() function. 14// 15//===----------------------------------------------------------------------===// 16 17#define DL_NAME "delinearize" 18#define DEBUG_TYPE DL_NAME 19#include "llvm/IR/Constants.h" 20#include "llvm/IR/DerivedTypes.h" 21#include "llvm/IR/Function.h" 22#include "llvm/IR/Instructions.h" 23#include "llvm/IR/LLVMContext.h" 24#include "llvm/Pass.h" 25#include "llvm/IR/Type.h" 26#include "llvm/Analysis/LoopInfo.h" 27#include "llvm/Analysis/Passes.h" 28#include "llvm/Analysis/ScalarEvolution.h" 29#include "llvm/Analysis/ScalarEvolutionExpressions.h" 30#include "llvm/Support/CommandLine.h" 31#include "llvm/Support/Debug.h" 32#include "llvm/Support/InstIterator.h" 33#include "llvm/Support/raw_ostream.h" 34 35using namespace llvm; 36 37namespace { 38 39class Delinearization : public FunctionPass { 40 Delinearization(const Delinearization &); // do not implement 41protected: 42 Function *F; 43 LoopInfo *LI; 44 ScalarEvolution *SE; 45 46public: 47 static char ID; // Pass identification, replacement for typeid 48 49 Delinearization() : FunctionPass(ID) { 50 initializeDelinearizationPass(*PassRegistry::getPassRegistry()); 51 } 52 virtual bool runOnFunction(Function &F); 53 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 54 virtual void print(raw_ostream &O, const Module *M = 0) const; 55}; 56 57} // end anonymous namespace 58 59void Delinearization::getAnalysisUsage(AnalysisUsage &AU) const { 60 AU.setPreservesAll(); 61 AU.addRequired<LoopInfo>(); 62 AU.addRequired<ScalarEvolution>(); 63} 64 65bool Delinearization::runOnFunction(Function &F) { 66 this->F = &F; 67 SE = &getAnalysis<ScalarEvolution>(); 68 LI = &getAnalysis<LoopInfo>(); 69 return false; 70} 71 72static Value *getPointerOperand(Instruction &Inst) { 73 if (LoadInst *Load = dyn_cast<LoadInst>(&Inst)) 74 return Load->getPointerOperand(); 75 else if (StoreInst *Store = dyn_cast<StoreInst>(&Inst)) 76 return Store->getPointerOperand(); 77 else if (GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(&Inst)) 78 return Gep->getPointerOperand(); 79 return NULL; 80} 81 82void Delinearization::print(raw_ostream &O, const Module *) const { 83 O << "Delinearization on function " << F->getName() << ":\n"; 84 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) { 85 Instruction *Inst = &(*I); 86 87 // Only analyze loads and stores. 88 if (!isa<StoreInst>(Inst) && !isa<LoadInst>(Inst) && 89 !isa<GetElementPtrInst>(Inst)) 90 continue; 91 92 const BasicBlock *BB = Inst->getParent(); 93 // Delinearize the memory access as analyzed in all the surrounding loops. 94 // Do not analyze memory accesses outside loops. 95 for (Loop *L = LI->getLoopFor(BB); L != NULL; L = L->getParentLoop()) { 96 const SCEV *AccessFn = SE->getSCEVAtScope(getPointerOperand(*Inst), L); 97 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(AccessFn); 98 99 // Do not try to delinearize memory accesses that are not AddRecs. 100 if (!AR) 101 break; 102 103 O << "AddRec: " << *AR << "\n"; 104 105 SmallVector<const SCEV *, 3> Subscripts, Sizes; 106 const SCEV *Res = AR->delinearize(*SE, Subscripts, Sizes); 107 int Size = Subscripts.size(); 108 if (Res == AR || Size == 0) { 109 O << "failed to delinearize\n"; 110 continue; 111 } 112 O << "Base offset: " << *Res << "\n"; 113 O << "ArrayDecl[UnknownSize]"; 114 for (int i = 0; i < Size - 1; i++) 115 O << "[" << *Sizes[i] << "]"; 116 O << " with elements of " << *Sizes[Size - 1] << " bytes.\n"; 117 118 O << "ArrayRef"; 119 for (int i = 0; i < Size; i++) 120 O << "[" << *Subscripts[i] << "]"; 121 O << "\n"; 122 } 123 } 124} 125 126char Delinearization::ID = 0; 127static const char delinearization_name[] = "Delinearization"; 128INITIALIZE_PASS_BEGIN(Delinearization, DL_NAME, delinearization_name, true, 129 true) 130INITIALIZE_PASS_DEPENDENCY(LoopInfo) 131INITIALIZE_PASS_END(Delinearization, DL_NAME, delinearization_name, true, true) 132 133FunctionPass *llvm::createDelinearizationPass() { return new Delinearization; } 134